Anti-atherosclerotic potential of gossypetin via inhibiting LDL oxidation and foam cell formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Jing-Hsien; Department of Medical Research, Chung Shan Medical University Hospital, Taichung, Taiwan; Tsai, Chia-Wen

Gossypetin, a flavone originally isolated from Hibiscus species, has been shown to possess antioxidant, antimicrobial, and antimutagenic activities. Here, we investigated the mechanism(s) underlying the anti-atherosclerotic potential of gossypetin. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) scavenging activity assay showed that the addition of > 50 μM of gossypetin could scavenge over 50% of DPPH radicals. The inhibitory effects of gossypetin on the lipid and protein oxidation of LDL were defined by thiobarbituric acid reactive substance (TBARS) assay, the relative electrophoretic mobility (REM) of oxidized LDL (ox-LDL), and fragmentation of apoB in the Cu{sup 2+}-induced oxidation of LDL. Gossypetin showed potential in reducing ox-LDL-induced foammore » cell formation and intracellular lipid accumulation, and uptake ability of macrophages under non-cytotoxic concentrations. Molecular data showed that these influences of gossypetin might be mediated via peroxisome proliferator-activated receptor α (PPARα)/liver-X receptor α (LXRα)/ATP-binding cassette transporter A1 (ABCA1) and PPARγ/scavenger receptor CD36 pathways, as demonstrated by the transfection of PPARα siRNA or PPARγ expression vector. Our data implied that gossypetin regulated the PPAR signals, which in turn led to stimulation of cholesterol removal from macrophages and delay atherosclerosis. These results suggested that gossypetin potentially could be developed as an anti-atherosclerotic agent. - Highlights: • The anti-atherosclerotic effect of gossypetin in vitro was examined. • Gossypetin inhibited LDL oxidation. • Gossypetin showed potential in reducing on the formation of foam cells. • Gossypetin functions against ox-LDL through PPARa activation and PPARγ depression.« less

Scavenger Receptor Class B Type 1 Deletion Led to Coronary Atherosclerosis and Ischemic Heart Disease in Low-density Lipoprotein Receptor Knockout Mice on Modified Western-type Diet

PubMed Central

Liao, Jiawei; Guo, Xin; Wang, Mengyu; Dong, Chengyan; Gao, Mingming; Wang, Huan; Kayoumu, Abudurexiti; Shen, Qiang; Wang, Yuhui; Wang, Fan; Liu, George

2017-01-01

Aim: Atherosclerosis-prone apolipoprotein E (apoE) or low-density lipoprotein receptor (LDL-R) knockout (KO) mice are generally resistant to developing coronary atherosclerosis (CA) and ischemic heart disease (IHD). However, studies have demonstrated the occurrence of spontaneous CA and IHD in scavenger receptor class B type 1 (SR-BI)/apoE double KO (dKO) mice, which suggests that SR-BI could be a potential target for the prevention and therapy of CA and IHD. This possibility was later investigated in SR-BI/LDL-R dKO mice, but no signs of CA or IHD was identified when mice were fed a normal western-type diet. Here we explored whether SR-BI deletion could result in CA and IHD in LDL-R KO mice when fed a modified western-type diet containing higher (0.5%) cholesterol. Methods: Cardiac functions were detected by electrocardiography, single photon emission computed tomography (SPECT), echocardiography (Echo) and 2,3,5-triphenyltetrazolium chloride staining. CA was visualized by hematoxylin-eosin staining. Results: After 12 weeks on the modified diet, SR-BI/LDL-R dKO mice developed cardiac ischemia/infarction, together with systolic dysfunction and left ventricular dilatation. CA was most severe at the aortic sinus level to an extent that no dKO mice survived to 20 weeks on the modified diet. None of control mice, however, developed CA or IHD. Conclusions: SR-BI deletion led to CA and IHD in LDL-R KO mice when fed the modified western-type diet. We established SR-BI/LDL-R dKO mice as a diet-induced murine model of human IHD and developed detection methods, using a combination of SPECT and Echo, for effective in vivo evaluation of cardiac functions. PMID:27373983

Genome-wide RNAi screen reveals ALK1 mediates LDL uptake and transcytosis in endothelial cells

PubMed Central

Kraehling, Jan R.; Chidlow, John H.; Rajagopal, Chitra; Sugiyama, Michael G.; Fowler, Joseph W.; Lee, Monica Y.; Zhang, Xinbo; Ramírez, Cristina M.; Park, Eon Joo; Tao, Bo; Chen, Keyang; Kuruvilla, Leena; Larriveé, Bruno; Folta-Stogniew, Ewa; Ola, Roxana; Rotllan, Noemi; Zhou, Wenping; Nagle, Michael W.; Herz, Joachim; Williams, Kevin Jon; Eichmann, Anne; Lee, Warren L.; Fernández-Hernando, Carlos; Sessa, William C.

2016-01-01

In humans and animals lacking functional LDL receptor (LDLR), LDL from plasma still readily traverses the endothelium. To identify the pathways of LDL uptake, a genome-wide RNAi screen was performed in endothelial cells and cross-referenced with GWAS-data sets. Here we show that the activin-like kinase 1 (ALK1) mediates LDL uptake into endothelial cells. ALK1 binds LDL with lower affinity than LDLR and saturates only at hypercholesterolemic concentrations. ALK1 mediates uptake of LDL into endothelial cells via an unusual endocytic pathway that diverts the ligand from lysosomal degradation and promotes LDL transcytosis. The endothelium-specific genetic ablation of Alk1 in Ldlr-KO animals leads to less LDL uptake into the aortic endothelium, showing its physiological role in endothelial lipoprotein metabolism. In summary, identification of pathways mediating LDLR-independent uptake of LDL may provide unique opportunities to block the initiation of LDL accumulation in the vessel wall or augment hepatic LDLR-dependent clearance of LDL. PMID:27869117

Genome-wide RNAi screen reveals ALK1 mediates LDL uptake and transcytosis in endothelial cells.

PubMed

Kraehling, Jan R; Chidlow, John H; Rajagopal, Chitra; Sugiyama, Michael G; Fowler, Joseph W; Lee, Monica Y; Zhang, Xinbo; Ramírez, Cristina M; Park, Eon Joo; Tao, Bo; Chen, Keyang; Kuruvilla, Leena; Larriveé, Bruno; Folta-Stogniew, Ewa; Ola, Roxana; Rotllan, Noemi; Zhou, Wenping; Nagle, Michael W; Herz, Joachim; Williams, Kevin Jon; Eichmann, Anne; Lee, Warren L; Fernández-Hernando, Carlos; Sessa, William C

2016-11-21

In humans and animals lacking functional LDL receptor (LDLR), LDL from plasma still readily traverses the endothelium. To identify the pathways of LDL uptake, a genome-wide RNAi screen was performed in endothelial cells and cross-referenced with GWAS-data sets. Here we show that the activin-like kinase 1 (ALK1) mediates LDL uptake into endothelial cells. ALK1 binds LDL with lower affinity than LDLR and saturates only at hypercholesterolemic concentrations. ALK1 mediates uptake of LDL into endothelial cells via an unusual endocytic pathway that diverts the ligand from lysosomal degradation and promotes LDL transcytosis. The endothelium-specific genetic ablation of Alk1 in Ldlr-KO animals leads to less LDL uptake into the aortic endothelium, showing its physiological role in endothelial lipoprotein metabolism. In summary, identification of pathways mediating LDLR-independent uptake of LDL may provide unique opportunities to block the initiation of LDL accumulation in the vessel wall or augment hepatic LDLR-dependent clearance of LDL.

FH Afrikaner-3 LDL receptor mutation results in defective LDL receptors and causes a mild form of familial hypercholesterolemia.

PubMed

Graadt van Roggen, J F; van der Westhuyzen, D R; Coetzee, G A; Marais, A D; Steyn, K; Langenhoven, E; Kotze, M J

1995-06-01

Three founder-related gene mutations (FH Afrikaner-1, -2, and -3) that affect the LDL receptor are responsible for 90% of the familial hypercholesterolemia (FH) in South African Afrikaners. Patients heterozygous for the FH Afrikaner-1 (FH1) mutation, which results in receptors having approximately 20% of normal receptor activity, have significantly lower plasma cholesterol levels and milder clinical symptoms than heterozygotes with the FH Afrikaner-2 mutation, which completely abolishes LDL receptor activity. In this study we re-created the FH3 mutation (Asp154-->Asn) in exon 4 by site-directed mutagenesis and analyzed the expression of the mutant receptors in Chinese hamster ovary cells. The mutation resulted in the formation of LDL receptors that are markedly defective in their ability to bind LDL, whereas binding of apoE-containing beta-VLDL is less affected. The mutant receptors are poorly expressed on the cell surface as a result of significant degradation of receptor precursors. The plasma cholesterol levels of 31 FH3 heterozygotes were similar to FH1 heterozygotes but significantly lower than FH2 heterozygotes. The FH1 and FH3 heterozygotes also tended to be less severely affected clinically (by coronary heart disease and xanthomata) than FH2 patients. This study demonstrates that mutational heterogeneity in the LDL receptor gene influences the phenotypic expression of heterozygous FH and that severity of expression correlates with the activity of the LDL receptor measured in vitro. The results further indicate that knowledge of the specific mutation underlying FH in heterozygotes is valuable in determining the potential risk of premature atherosclerosis and should influence the clinical management of FH patients.

Inflammation Stimulates the Expression of PCSK9

PubMed Central

Feingold, Kenneth R.; Moser, Arthur H.; Shigenaga, Judy K.; Patzek, Sophie M.; Grunfeld, Carl

2008-01-01

Inflammation induces marked changes in lipid and lipoprotein metabolism. Proprotein convertase subtilisin kexin 9 (PCSK9) plays an important role in regulating LDL receptor degradation. Here we demonstrate that LPS decreases hepatic LDL receptor protein but at the same time hepatic LDL receptor mRNA levels are not decreased. We therefore explored the effect of LPS on PCSK9 expression. LPS results in a marked increase in hepatic PCSK9 mRNA levels (4 hours-2.5 fold increase; 38 hours-12.5 fold increase). The increase in PCSK9 is a sensitive response with 1 ug LPS inducing a ½ maximal response. LPS also increased PCSK9 expression in the kidney. Finally, zymosan and turpentine, other treatments that induce inflammation, also stimulated hepatic expression of PCSK9. Thus, inflammation stimulates PCSK9 expression leading to increased LDL receptor degradation and decreasing LDL receptors thereby increasing serum LDL, which could have beneficial effects on host defense. PMID:18638454

Activation of Peroxisome Proliferator-activated Receptor γ (PPARγ) and CD36 Protein Expression

PubMed Central

Yang, Xiaoxiao; Zhang, Wenwen; Chen, Yuanli; Li, Yan; Sun, Lei; Liu, Ying; Liu, Mengyang; Yu, Miao; Li, Xiaoju; Han, Jihong; Duan, Yajun

2016-01-01

Progesterone or its analog, one of components of hormone replacement therapy, may attenuate the cardioprotective effects of estrogen. However, the underlying mechanisms have not been fully elucidated. Expression of CD36, a receptor for oxidized LDL (oxLDL) that enhances macrophage/foam cell formation, is activated by the transcription factor peroxisome proliferator-activated receptor γ (PPARγ). CD36 also functions as a fatty acid transporter to influence fatty acid metabolism and the pathophysiological status of several diseases. In this study, we determined that progesterone induced macrophage CD36 expression, which is related to progesterone receptor (PR) activity. Progesterone enhanced cellular oxLDL uptake in a CD36-dependent manner. Mechanistically, progesterone increased PPARγ expression and PPARγ promoter activity in a PR-dependent manner and the binding of PR with the progesterone response element in the PPARγ promoter. Specific deletion of macrophage PPARγ (MφPPARγ KO) expression in mice abolished progesterone-induced macrophage CD36 expression and cellular oxLDL accumulation. We also determined that, associated with gestation and increased serum progesterone levels, CD36 and PPARγ expression in mouse adipose tissue, skeletal muscle, and peritoneal macrophages were substantially activated. Taken together, our study demonstrates that progesterone can play dual pathophysiological roles by activating PPARγ expression, in which progesterone increases macrophage CD36 expression and oxLDL accumulation, a negative effect on atherosclerosis, and enhances the PPARγ-CD36 pathway in adipose tissue and skeletal muscle, a protective effect on pregnancy. PMID:27226602

G-protein estrogen receptor as a regulator of low-density lipoprotein cholesterol metabolism: cellular and population genetic studies.

PubMed

Hussain, Yasin; Ding, Qingming; Connelly, Philip W; Brunt, J Howard; Ban, Matthew R; McIntyre, Adam D; Huff, Murray W; Gros, Robert; Hegele, Robert A; Feldman, Ross D

2015-01-01

Estrogen deficiency is linked with increased low-density lipoprotein (LDL) cholesterol. The hormone receptor mediating this effect is unknown. G-protein estrogen receptor (GPER) is a recently recognized G-protein-coupled receptor that is activated by estrogens. We recently identified a common hypofunctional missense variant of GPER, namely P16L. However, the role of GPER in LDL metabolism is unknown. Therefore, we examined the association of the P16L genotype with plasma LDL cholesterol level. Furthermore, we studied the role of GPER in regulating expression of the LDL receptor and proprotein convertase subtilisin kexin type 9. Our discovery cohort was a genetically isolated population of Northern European descent, and our validation cohort consisted of normal, healthy women aged 18 to 56 years from London, Ontario. In addition, we examined the effect of GPER on the regulation of proprotein convertase subtilisin kexin type 9 and LDL receptor expression by the treatment with the GPER agonist, G1. In the discovery cohort, GPER P16L genotype was associated with a significant increase in LDL cholesterol (mean±SEM): 3.18±0.05, 3.25±0.08, and 4.25±0.33 mmol/L, respectively, in subjects with CC (homozygous for P16), CT (heterozygotes), and TT (homozygous for L16) genotypes (P<0.05). In the validation cohort (n=339), the GPER P16L genotype was associated with a similar increase in LDL cholesterol: 2.17±0.05, 2.34±0.06, and 2.42±0.16 mmol/L, respectively, in subjects with CC, CT, and TT genotypes (P<0.05). In the human hepatic carcinoma cell line, the GPER agonist, G1, mediated a concentration-dependent increase in LDL receptor expression, blocked by either pretreatment with the GPER antagonist G15 or by shRNA-mediated GPER downregulation. G1 also mediated a GPER- and concentration-dependent decrease in proprotein convertase subtilisin kexin type 9 expression. GPER activation upregulates LDL receptor expression, probably at least, in part, via proprotein convertase subtilisin kexin type 9 downregulation. Furthermore, humans carrying the hypofunctional P16L genetic variant of GPER have increased plasma LDL cholesterol. In aggregate, these data suggest an important role of GPER in the regulation of LDL receptor expression and consequently LDL metabolism. © 2014 American Heart Association, Inc.

More Than Cholesterol Transporters: Lipoprotein Receptors in CNS Function and Neurodegeneration

PubMed Central

Lane-Donovan, Courtney E.; Philips, Gary T.; Herz, Joachim

2014-01-01

Members of the low-density lipoprotein (LDL) receptor gene family have a diverse set of biological functions that transcend lipid metabolism. Lipoprotein receptors have broad effects in both the developing and adult brain and participate in synapse development, cargo trafficking, and signal transduction. In addition, several family members play key roles in Alzheimer's disease pathogenesis and neurodegeneration. This review summarizes our current understanding of the role lipoprotein receptors play in CNS function and AD pathology, with a special emphasis on amyloid-independent roles in endocytosis and synaptic dysfunction. PMID:25144875

Fcgamma chain deficiency on hematopoietic cells ameliorates atherosclerosis in apoe-knockout mice by promoting Th2 responses

USDA-ARS?s Scientific Manuscript database

We have previously shown that oxLDL-immune complexes (oxLDL-IC) binding to Fcgamma receptors (Fc gamma R) expressed on human monocytes leads to induction of pro-inflammatory cytokines. Four classes of mouse Fc gamma Rs have been defined: Fc gamma RI, II, III, and IV. Functionally, Fc gamma Rs can be...

Emerging Treatments for Heterozygous and Homozygous Familial Hypercholesterolemia.

PubMed

Baum, Seth J; Soffer, Daniel; Barton Duell, P

Familial hypercholesterolemia (FH) is an autosomal co-dominant disorder marked by extremely high low-density lipoprotein (LDL) cholesterol levels and concomitant premature vascular disease. FH is caused by mutations that most commonly affect three genes integrally involved in the LDL receptor's ability to clear LDL particles from the circulation. Primary intervention efforts to lower LDL cholesterol have centered on therapies that upregulate the LDL receptor. Unfortunately, most patients are insufficiently responsive to traditional LDL-lowering medications. This article focuses primarily on the clinical management of homozygous FH.

Metabolism of native and naturally occurring multiple modified low density lipoprotein in smooth muscle cells of human aortic intima.

PubMed

Tertov, V V; Orekhov, A N

1997-01-01

The subfraction of low density lipoprotein (LDL) with low sialic acid content that caused accumulation of cholesterol esters in human aortic smooth muscle cells has been found in the blood of coronary atherosclerosis patients. It was demonstrated that this subfraction consists of LDL with small size, high electronegative charge, reduced lipid content, altered tertiary structure of apolipoprotein B, etc. LDL of this subfraction is naturally occurring multiple-modified LDL (nomLDL). In this study we compared the binding, uptake and proteolytic degradation of native LDL and nomLDL by smooth muscle cells cultured from human grossly normal intima, fatty streaks, and atherosclerotic plaques. Uptake of nomLDL by normal and atherosclerotic cells was 3.5- and 6-fold, respectively, higher than uptake of native LDL. Increased uptake of nomLDL was due to increased binding of this LDL by intimal smooth muscle cells. The enhanced binding is explained by the interaction of nomLDL with cellular receptors other than LDL-receptor. Modified LDL interacted with the scavenger receptor, asialoglycoprotein receptor, and also with cell surface proteoglycans. Rates of degradation of nomLDL were 1.5- and 5-fold lower than degradation of native LDL by normal and atherosclerotic cells, respectively. A low rate of nomLDL degradation was also demonstrated in homogenates of intimal cells. Activities of lysosomal proteinases of atherosclerotic cells were decreased compared with normal cells. Pepstatin A, a cathepsin D inhibitor, completely inhibited lipoprotein degradation, while serine, thiol, or metallo-proteinase inhibitors had partial effect. This fact reveals that cathepsin D is involved in initial stages of apoB degradation by intimal smooth muscle cells. Obtained data show that increased uptake and decreased lysosomal degradation of nomLDL may be the main cause of LDL accumulation in human aortic smooth muscle cells, leading to foam cell formation.

PCSK9 inhibitors in the current management of atherosclerosis.

PubMed

Whayne, Thomas F

The history of proprotein convertase subtilisin/kexin type 9 (PCSK9) in medical science is fascinating and the evolution of knowledge of its function has resulted in new medications of major importance for the cardiovascular (CV) patient. PCSK9 functions as a negative control or feedback for the cell surface receptors for low-density lipoprotein including its component of cholesterol (LDL-C). The initial and key findings were that different abnormalities of PCSK9 can result in an increase or a decrease of LDL-C because of more or less suppression of cell surface receptors. These observations gave hints and awoke interest that it might be possible to prepare monoclonal antibodies to PCSK9 and decrease its activity, after which there should be more active LDL-C cell receptors. The rest is a fascinating story that currently has resulted in two PCSK9 inhibitors, alirocumab and evolocumab, which, on average, decrease LDL-C approximately 50%. Nevertheless, if there are no contraindications, statins remain the standard of prevention for the high-risk CV patient and this includes both secondary and primary prevention. The new inhibitors are for the patient that does not attain the desired target for LDL-C reduction while taking a maximum statin dose or who does not tolerate any statin dose whatsoever. Atherosclerosis can be considered a metabolic disease and the clinician needs to realize this and think more and more of CV prevention. These inhibitors can contribute to both the stabilization and regression of atherosclerotic plaques and thereby avoid or delay major adverse cardiac events. (United States). Copyright © 2016 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

A nonsense mutation in the LDL receptor gene leads to familial hypercholesterolemia in the Druze sect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landsberger, D.; Meiner, V.; Reshef, A.

1992-02-01

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the LDL receptor gene. Here the authors characterize and LDL receptor mutation that is associated with a distinct haplotype and causes FH in the Druze, a small Middle Eastern Islamic sect with a high degree of inbreeding. The mutation was found in FH families from two distinct Druze villages from the Golan Heights (northern Israel). It was not found either in another Druze FH family residing in a different geographical area nor in eight Arab and four Jewish FH heterozygote index cases whose hypercholesterolemia cosegregates with an identicalmore » LDL receptor gene haplotype. The mutation, a single-base substitution, results in a termination codon in exon 4 of the LDL receptor gene that encodes for the fourth repeat of the binding domain of the mature receptor. It can be diagnosed by allele-specific oligonucleotide hybridization of PCR-amplified DNA from FH patients.« less

Activation of Peroxisome Proliferator-activated Receptor γ (PPARγ) and CD36 Protein Expression: THE DUAL PATHOPHYSIOLOGICAL ROLES OF PROGESTERONE.

PubMed

Yang, Xiaoxiao; Zhang, Wenwen; Chen, Yuanli; Li, Yan; Sun, Lei; Liu, Ying; Liu, Mengyang; Yu, Miao; Li, Xiaoju; Han, Jihong; Duan, Yajun

2016-07-15

Progesterone or its analog, one of components of hormone replacement therapy, may attenuate the cardioprotective effects of estrogen. However, the underlying mechanisms have not been fully elucidated. Expression of CD36, a receptor for oxidized LDL (oxLDL) that enhances macrophage/foam cell formation, is activated by the transcription factor peroxisome proliferator-activated receptor γ (PPARγ). CD36 also functions as a fatty acid transporter to influence fatty acid metabolism and the pathophysiological status of several diseases. In this study, we determined that progesterone induced macrophage CD36 expression, which is related to progesterone receptor (PR) activity. Progesterone enhanced cellular oxLDL uptake in a CD36-dependent manner. Mechanistically, progesterone increased PPARγ expression and PPARγ promoter activity in a PR-dependent manner and the binding of PR with the progesterone response element in the PPARγ promoter. Specific deletion of macrophage PPARγ (MφPPARγ KO) expression in mice abolished progesterone-induced macrophage CD36 expression and cellular oxLDL accumulation. We also determined that, associated with gestation and increased serum progesterone levels, CD36 and PPARγ expression in mouse adipose tissue, skeletal muscle, and peritoneal macrophages were substantially activated. Taken together, our study demonstrates that progesterone can play dual pathophysiological roles by activating PPARγ expression, in which progesterone increases macrophage CD36 expression and oxLDL accumulation, a negative effect on atherosclerosis, and enhances the PPARγ-CD36 pathway in adipose tissue and skeletal muscle, a protective effect on pregnancy. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Lipid accumulation in smooth muscle cells under LDL loading is independent of LDL receptor pathway and enhanced by hypoxic conditions.

PubMed

Wada, Youichiro; Sugiyama, Akira; Yamamoto, Takashi; Naito, Makoto; Noguchi, Noriko; Yokoyama, Shinji; Tsujita, Maki; Kawabe, Yoshiki; Kobayashi, Mika; Izumi, Akashi; Kohro, Takahide; Tanaka, Toshiya; Taniguchi, Hirokazu; Koyama, Hidenori; Hirano, Ken-ichi; Yamashita, Shizuya; Matsuzawa, Yuji; Niki, Etsuo; Hamakubo, Takao; Kodama, Tatsuhiko

2002-10-01

The effect of a variety of hypoxic conditions on lipid accumulation in smooth muscle cells (SMCs) was studied in an arterial wall coculture and monocultivation model. Low density lipoprotein (LDL) was loaded under various levels of oxygen tension. Oil red O staining of rabbit and human SMCs revealed that lipid accumulation was greater under lower oxygen tension. Cholesterol esters were shown to accumulate in an oxygen tension-dependent manner by high-performance liquid chromatographic analysis. Autoradiograms using radiolabeled LDL indicated that LDL uptake was more pronounced under hypoxia. This result holds in the case of LDL receptor-deficient rabbit SMCs. However, cholesterol biosynthesis and cellular cholesterol release were unaffected by oxygen tension. Hypoxia significantly increases LDL uptake and enhances lipid accumulation in arterial SMCs, exclusive of LDL receptor activity. Although the molecular mechanism is not clear, the model is useful for studying lipid accumulation in arterial wall cells and the difficult-to-elucidate events in the initial stage of atherogenesis.

Fluid-phase pinocytosis of LDL by macrophages: a novel target to reduce macrophage cholesterol accumulation in atherosclerotic lesions.

PubMed

Kruth, Howar S

2013-01-01

Circulating low-density lipoprotein (LDL) that enters the blood vessel wall is the main source of cholesterol that accumulates within atherosclerotic plaques. Much of the deposited cholesterol accumulates within plaque macrophages converting these macrophages into cholesterol-rich foamy looking cells. Cholesterol accumulation in macrophages contributes to cholesterol retention within the vessel wall, and promotes vessel wall inflammation and thrombogenicity. Thus, how macrophages accumulate cholesterol and become foam cells has been the subject of intense investigation. It is generally believed that macrophages accumulate cholesterol only through scavenger receptor-mediated uptake of modified LDL. However, an alternative mechanism for macrophage foam cell formation that does not depend on LDL modification or macrophage receptors has been elucidated. By this alternative mechanism, macrophages show receptor-independent uptake of unmodified native LDL that is mediated by fluid-phase pinocytosis. In receptor-independent, fluid-phase pinocytosis, macrophages take up LDL as part of the fluid that they ingest during micropinocytosis within small vesicles called micropinosomes, and by macropinocytosis within larger vacuoles called macropinosomes. This produces cholesterol accumulation in macrophages to levels characteristic of macrophage foam cells in atherosclerotic plaques. Fluid-phase pinocytosis of LDL is a plausible mechanism that can explain how macrophages accumulate cholesterol and become disease-causing foam cells. Fluid-phase pinocytosis of LDL is a relevant pathway to target for modulating macrophage cholesterol accumulation in atherosclerosis. Recent studies show that phosphoinositide 3-kinase (PI3K), liver X receptors (LXRs), the macrophage colony-stimulating factor (M-CSF) receptor, and protein kinase C (PKC) mediate macrophage macropinocytosis of LDL, and thus, these may be relevant targets to inhibit macrophage cholesterol accumulation in atherosclerosis.

Upregulation of endothelial receptor for oxidized LDL (LOX-1) by oxidized LDL and implications in apoptosis of human coronary artery endothelial cells: evidence from use of antisense LOX-1 mRNA and chemical inhibitors.

PubMed

Li, D; Mehta, J L

2000-04-01

A specific lectin-like endothelial receptor for oxidized low density lipoprotein (LOX-1), distinct from the scavenger receptor in monocytes/macrophages, has been identified and cloned. In this study, we examined the regulation of LOX-1 by oxidized low density lipoprotein (ox-LDL) and determined the role of LOX-1 in ox-LDL-induced apoptosis of cultured human coronary artery endothelial cells (HCAECs). Incubation of HCAECs with ox-LDL (40 microg/mL), but not native LDL, for 24 hours markedly increased LOX-1 expression (mRNA and protein). After 48 hours of preincubation of HCAECs with a specific antisense to LOX-1 mRNA (antisense LOX-1), ox-LDL-mediated upregulation of LOX-1 was suppressed (P<0.01). In contrast, treatment of HCAECs with sense LOX-1 had no effect. Ox-LDL also induced apoptosis (determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling and DNA laddering) of HCAECs in a concentration- and time-dependent fashion. LOX-1 played an important role in ox-LDL-mediated apoptosis of HCAECs because antisense LOX-1 inhibited this effect of ox-LDL. Polyinosinic acid and carrageenan, 2 different chemical inhibitors of LOX-1, also decreased ox-LDL-mediated apoptosis of HCAECs. Nuclear factor (NF)-kappaB was markedly activated in ox-LDL-treated HCAECs. The critical role of NF-kappaB activation became evident in experiments with antisense LOX-1, which abolished ox-LDL-mediated NF-kappaB activation. In this process, an NF-kappaB inhibitor, caffeic acid phenethyl ester, also inhibited ox-LDL-mediated apoptosis of HCAECs. These findings indicate that ox-LDL upregulates its own endothelial receptor. Ox-LDL-induced apoptosis is mediated by the action of LOX-1. In this process, NF-kappaB activation may play an important role as a signal transduction mechanism.

Two common low density lipoprotein receptor gene mutations cause familial hypercholesterolemia in Afrikaners.

PubMed

Leitersdorf, E; Van der Westhuyzen, D R; Coetzee, G A; Hobbs, H H

1989-09-01

Familial hypercholesterolemia (FH), an autosomal dominant disease caused by mutations in the LDL receptor gene, is five times more frequent in the Afrikaner population of South Africa than it is in the population of the United States and Europe. It has been proposed that the high frequency is due to a founder effect. In this paper, we characterized 24 mutant LDL receptor alleles from 12 Afrikaner individuals homozygous for FH. We identified two mutations that together makeup greater than 95% of the mutant LDL receptor genes represented in our sample. Both mutations were basepair substitutions that result in single-amino acid changes. Each mutation can be detected readily with the polymerase chain reaction and restriction analysis. The finding of two common LDL receptor mutations in the Afrikaner FH homozygotes predicts that these mutations will predominate in the Afrikaner population and that the high frequency of FH is due to a founder effect. The increased incidence of ischemic heart disease in the Afrikaner population may in part be due to the high frequency of these two mutations in the LDL receptor gene.

Two common low density lipoprotein receptor gene mutations cause familial hypercholesterolemia in Afrikaners.

PubMed Central

Leitersdorf, E; Van der Westhuyzen, D R; Coetzee, G A; Hobbs, H H

1989-01-01

Familial hypercholesterolemia (FH), an autosomal dominant disease caused by mutations in the LDL receptor gene, is five times more frequent in the Afrikaner population of South Africa than it is in the population of the United States and Europe. It has been proposed that the high frequency is due to a founder effect. In this paper, we characterized 24 mutant LDL receptor alleles from 12 Afrikaner individuals homozygous for FH. We identified two mutations that together makeup greater than 95% of the mutant LDL receptor genes represented in our sample. Both mutations were basepair substitutions that result in single-amino acid changes. Each mutation can be detected readily with the polymerase chain reaction and restriction analysis. The finding of two common LDL receptor mutations in the Afrikaner FH homozygotes predicts that these mutations will predominate in the Afrikaner population and that the high frequency of FH is due to a founder effect. The increased incidence of ischemic heart disease in the Afrikaner population may in part be due to the high frequency of these two mutations in the LDL receptor gene. Images PMID:2569482

The low density lipoprotein receptor-related protein 1B retains beta-amyloid precursor protein at the cell surface and reduces amyloid-beta peptide production.

PubMed

Cam, Judy A; Zerbinatti, Celina V; Knisely, Jane M; Hecimovic, Silva; Li, Yonghe; Bu, Guojun

2004-07-09

The low density lipoprotein (LDL) receptor-related protein 1B (LRP1B) is a newly identified member of the LDL receptor family that shares high homology with the LDL receptor-related protein (LRP). LRP1B was originally described as a putative tumor suppressor in lung cancer cells; however, its expression profile in several regions of adult human brain suggests it may have additional functions in the central nervous system. Since LRP1B has overlapping ligand binding properties with LRP, we investigated whether LRP1B, like LRP, could interact with the beta-amyloid precursor protein (APP) and modulate its processing to amyloid-beta peptides (Abetas). Using an LRP1B minireceptor (mLRP1B4) generated to study the trafficking of LRP1B, we found that mLRP1B4 and APP form an immunoprecipitable complex. Furthermore mLRP1B4 bound and facilitated the degradation of a soluble isoform of APP containing a Kunitz proteinase inhibitor domain but not soluble APP lacking a Kunitz proteinase inhibitor domain. A functional consequence of mLRP1B4 expression was a significant accumulation of APP at the cell surface, which is likely related to the slow endocytosis rate of LRP1B. More importantly, mLRP1B4-expressing cells that accumulated cell surface APP produced less Abeta and secreted more soluble APP. These findings reveal that LRP1B is a novel binding partner of APP that functions to decrease APP processing to Abeta. Consequently LRP1B expression could function to protect against the pathogenesis of Alzheimer's disease.

Interaction study between synthetic glycoconjugate ligands and endocytic receptors using flow cytometry.

PubMed

Yura, Hirofumi; Ishihara, Masayuki; Kanatani, Yasuhiro; Takase, Bonpei; Hattori, Hidemi; Suzuki, Shinya; Kawakami, Mitsuyuki; Matsui, Takemi

2006-04-01

Flow cytometric analysis of synthetic galactosyl polymers, asialofetuin and LDL derivatives labeled with FITC (Fluorescein Isothiocyanate) was carried out to determine the phenotypes of endocytic receptors, such as asialoglycoprotein (ASPG) and the LDL receptor, on various types of cells. When FITC-labeled galactosyl polystyrene (GalCPS), being a synthetic ligand of ASPG, was applied to rat hepatocytes and human cancer cells (Hep G2 and Chang Liver), surface fluorescence intensities varied according to receptor expression on the cells. The fluorescence intensity originates from the calcium-dependent binding of the FITC-labeled GalCPS. Although unaltered by pre-treatment with glucosyl polystyrene (GluCPS), fetuin and LDL, the fluorescence intensity was suppressed by pre-treatment with (non-labeled) GalCPS and asialofetuin. Flow cytometry allowed us to demonstrate that the calcium-dependent binding of FITC-labeled LDL (prepared from rabbits) upon the addition of 17alpha-ethinyl estradiol enhances LDL receptor expression, and the expression is suppressed upon the addition of a monoclonal antibody to the LDL receptor. The binding efficiency based on the combination of FITC-labeled ligands suggests a possible application for the classification of cell types and conditions corresponding to endocytic receptor expression without the need for immuno-active antibodies or radiolabeled substances. Furthermore, the synthetic glycoconjugate (GalCPS) is shown to be a sensitive and useful marker for classification based on cell phenotype using flow cytometry.

Role of contact inhibition in the regulation of receptor-mediated uptake of low density lipoprotein in cultured vascular endothelial cells.

PubMed Central

Vlodavsky, I; Fielding, P E; Fielding, C J; Gospodarowicz, D

1978-01-01

Bovine vascular endothelial cells during logarithmic growth bind, internalize, and degrade low density lipoprotein (LDL) via a receptor-mediated pathway. However, contact-inhibited (confluent) monolayers bind but do not internalize LDL. This is in contrast to aortic smooth muscle cells or endothelial cells that have lost the property of contact inhibition. These cells internalize and degrade LDL at both high and low cell densities. The LDL receptors of smooth muscle and sparse endothelial cells down-regulate in response to LDL. In contrast, normal endothelial cells at confluency show little response. When contact inhibition in endothelial monolayers was locally released by wounding, and LDL was present, only cells released from contact inhibition accumulated LDL cholesterol. In smooth muscle cells under the same conditions, the entire culture interiorized lipid. It thus appears that in endothelial cells, unlike smooth muscle cells, contact inhibition is the major factor regulating cellular uptake of LDL cholesteryl ester. Reversal of contact inhibition by wounding provides a mechanism by which the endothelium could be the primary initiator of the atherosclerotic plaque. Images PMID:203937

Oxidized LDL binding to LOX-1 upregulates VEGF expression in cultured bovine chondrocytes through activation of PPAR-{gamma}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanata, Sohya; Akagi, Masao; Nishimura, Shunji

It has been reported that vascular endothelial growth factor (VEGF) and its receptors play an important role in the destruction of articular cartilage in osteoarthritis through increased production of matrix metalloproteinases. We investigated whether the oxidized low-density lipoprotein (ox-LDL) binding to lectin-like ox-LDL receptor-1 (LOX-1) upregulates VEGF expression in cultured bovine articular chondrocytes (BACs). Ox-LDL markedly increased VEGF mRNA expression and protein release in time- and dose-dependent manners, which was significantly suppressed by anti-LOX-1 antibody pretreatment. Activation of peroxisome proliferator-activated receptor (PPAR)-{gamma} was evident in BACs with ox-LDL addition and was attenuated by anti-LOX-1 antibody. The specific PPAR-{gamma} inhibitor GW9662more » suppressed ox-LDL-induced VEGF expression. These results suggest that the ox-LDL/LOX-1 system upregulates VEGF expression in articular cartilage, at least in part, through activation of PPAR-{gamma} and supports the hypothesis that ox-LDL is involved in cartilage degradation via LOX-1.« less

MicroRNA-155 silencing enhances inflammatory response and lipid uptake in oxidized low-density lipoprotein-stimulated human THP-1 macrophages.

PubMed

Huang, Ri-sheng; Hu, Guan-qiong; Lin, Bin; Lin, Zhi-yi; Sun, Cheng-chao

2010-12-01

It has been proposed that the inflammatory response of monocytes/macrophages induced by oxidized low-density lipoprotein (oxLDL) is a key event in the pathogenesis of atherosclerosis. MicroRNA-155 (miR-155) is an important regulator of the immune system and has been shown to be involved in acute inflammatory response. However, the function of miR-155 in oxLDL-stimulated inflammation and atherosclerosis remains unclear. Here, we show that the exposure of human THP-1 macrophages to oxLDL led to a marked up-regulation of miR-155 in a dose-dependent manner. Silencing of endogenous miR-155 in THP-1 cells using locked nucleic acid-modified antisense oligonucleotides significantly enhanced oxLDL-induced lipid uptake, up-regulated the expression of scavenger receptors (lectinlike oxidized LDL receptor-1, cluster of differentiation 36 [CD36], and CD68), and promoted the release of several cytokines including interleukin (IL)-6, -8, and tumor necrosis factor α (TNF-α). Luciferase reporter assay showed that targeting miR-155 promoted nuclear factor-kappa B (NF-κB) nuclear translocation and potentiated the NF-κB-driven transcription activity. Moreover, miR-155 knockdown resulted in a marked increase in the protein amount of myeloid differentiation primary response gene 88 (MyD88), an important adapter protein used by Toll-like receptors to activate the NF-κB pathway. Our data demonstrate that miR-155 serves as a negative feedback regulator in oxLDL-stimulated THP-1 inflammatory responses and lipid uptake and thus might have potential therapeutic implications in atherosclerosis.

Clinical and pathophysiological evidence supporting the safety of extremely low LDL levels-The zero-LDL hypothesis.

PubMed

Masana, Luis; Girona, Josefa; Ibarretxe, Daiana; Rodríguez-Calvo, Ricardo; Rosales, Roser; Vallvé, Joan-Carles; Rodríguez-Borjabad, Cèlia; Guardiola, Montserrat; Rodríguez, Marina; Guaita-Esteruelas, Sandra; Oliva, Iris; Martínez-Micaelo, Neus; Heras, Mercedes; Ferré, Raimon; Ribalta, Josep; Plana, Núria

While the impact of very low concentrations of low-density lipoprotein cholesterol (LDL-C) on cardiovascular prevention is very reassuring, it is intriguing to know what effect these extremely low LDL-C concentrations have on lipid homoeostasis. The evidence supporting the safety of extremely low LDL levels comes from genetic studies and clinical drug trials. Individuals with lifelong low LDL levels due to mutations in genes associated with increased LDL-LDL receptor (LDLR) activity reveal no safety issues. Patients achieving extremely low LDL levels in the IMPROVE-IT and FOURIER, and the PROFICIO and ODYSSEY programs seem not to have an increased prevalence of adverse effects. The main concern regarding extremely low LDL-C plasma concentrations is the adequacy of the supply of cholesterol, and other molecules, to peripheral tissues. However, LDL proteomic and kinetic studies reaffirm that LDL is the final product of endogenous lipoprotein metabolism. Four of 5 LDL particles are cleared through the LDL-LDLR pathway in the liver. Given that mammalian cells have no enzymatic systems to degrade cholesterol, the LDL-LDLR pathway is the main mechanism for removal of cholesterol from the body. Our focus, therefore, is to review, from a physiological perspective, why such extremely low LDL-C concentrations do not appear to be detrimental. We suggest that extremely low LDL-C levels due to increased LDLR activity may be a surrogate of adequate LDL-LDLR pathway function. Copyright © 2018 National Lipid Association. Published by Elsevier Inc. All rights reserved.

LDL oxidation by platelets propagates platelet activation via an oxidative stress-mediated mechanism.

PubMed

Carnevale, Roberto; Bartimoccia, Simona; Nocella, Cristina; Di Santo, Serena; Loffredo, Lorenzo; Illuminati, Giulio; Lombardi, Elisabetta; Boz, Valentina; Del Ben, Maria; De Marco, Luigi; Pignatelli, Pasquale; Violi, Francesco

2014-11-01

Platelets generate oxidized LDL (ox-LDL) via NOX2-derived oxidative stress. We investigated if once generated by activated platelets ox-LDL can propagate platelet activation. Experiments were performed in platelets from healthy subjects (HS), hyper-cholesterolemic patients and patients with NOX2 hereditary deficiency. Agonist-stimulated platelets from HS added with LDL were associated with a dose-dependent increase of reactive oxidant species and ox-LDL. Agonist-stimulated platelets from HS added with a fixed dose of LDL (57.14 μmol/L) or added with homogenized human atherosclerotic plaque showed enhanced ox-LDL formation (approximately +50% and +30% respectively), which was lowered by a NOX2 inhibitor (approximately -35% and -25% respectively). Compared to HS, ox-LDL production was more pronounced in agonist-stimulated platelet rich plasma (PRP) from hyper-cholesterolemic patients but was almost absent in PRP from NOX2-deficient patients. Platelet aggregation and 8-iso-PGF2α-ΙΙΙ formation increased in LDL-treated washed platelets (+42% and +53% respectively) and PRP (+31% and +53% respectively). Also, LDL enhanced platelet-dependent thrombosis at arterial shear rate (+33%) but did not affect platelet activation in NOX2-deficient patients. Platelet activation by LDL was significantly inhibited by CD36 or LOX1 blocking peptides, two ox-LDL receptor antagonists, or by a NOX2 inhibitor. LDL-added platelets showed increased p38MAPK (+59%) and PKC (+51%) phosphorylation, p47(phox) translocation to platelet membrane (+34%) and NOX2 activation (+30%), which were inhibited by ox-LDL receptor antagonists. Platelets oxidize LDL, which in turn amplify platelet activation via specific ox-LDL receptors; both effects are mediated by NOX2 activation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

EETs Attenuate Ox-LDL-Induced LTB4 Production and Activity by Inhibiting p38 MAPK Phosphorylation and 5-LO/BLT1 Receptor Expression in Rat Pulmonary Arterial Endothelial Cells.

PubMed

Jiang, Jun-xia; Zhang, Shui-juan; Xiong, Yao-kang; Jia, Yong-liang; Sun, Yan-hong; Lin, Xi-xi; Shen, Hui-juan; Xie, Qiang-min; Yan, Xiao-feng

2015-01-01

Cytochrome P-450 epoxygenase (EPOX)-derived epoxyeicosatrienoic acids (EETs), 5-lipoxygenase (5-LO), and leukotriene B4 (LTB4), the product of 5-LO, all play a pivotal role in the vascular inflammatory process. We have previously shown that EETs can alleviate oxidized low-density lipoprotein (ox-LDL)-induced endothelial inflammation in primary rat pulmonary artery endothelial cells (RPAECs). Here, we investigated whether ox-LDL can promote LTB4 production through the 5-LO pathway. We further explored how exogenous EETs influence ox-LDL-induced LTB4 production and activity. We found that treatment with ox-LDL increased the production of LTB4 and further led to the expression and release of both monocyte chemoattractant protein-1 (MCP-1/CCL2) and intercellular adhesion molecule-1 (ICAM-1). All of the above ox-LDL-induced changes were attenuated by the presence of 11,12-EET and 14,15-EET, as these molecules inhibited the 5-LO pathway. Furthermore, the LTB4 receptor 1 (BLT1 receptor) antagonist U75302 attenuated ox-LDL-induced ICAM-1 and MCP-1/CCL2 expression and production, whereas LY255283, a LTB4 receptor 2 (BLT2 receptor) antagonist, produced no such effects. Moreover, in RPAECs, we demonstrated that the increased expression of 5-LO and BLT1 following ox-LDL treatment resulted from the activation of nuclear factor-κB (NF-κB) via the p38 mitogen-activated protein kinase (MAPK) pathway. Our results indicated that EETs suppress ox-LDL-induced LTB4 production and subsequent inflammatory responses by downregulating the 5-LO/BLT1 receptor pathway, in which p38 MAPK phosphorylation activates NF-κB. These results suggest that the metabolism of arachidonic acid via the 5-LO and EPOX pathways may present a mutual constraint on the physiological regulation of vascular endothelial cells.

EETs Attenuate Ox-LDL-Induced LTB4 Production and Activity by Inhibiting p38 MAPK Phosphorylation and 5-LO/BLT1 Receptor Expression in Rat Pulmonary Arterial Endothelial Cells

PubMed Central

Xiong, Yao-kang; Jia, Yong-liang; Sun, Yan-hong; Lin, Xi-xi; Shen, Hui-juan; Xie, Qiang-min; Yan, Xiao-feng

2015-01-01

Cytochrome P-450 epoxygenase (EPOX)-derived epoxyeicosatrienoic acids (EETs), 5-lipoxygenase (5-LO), and leukotriene B4 (LTB4), the product of 5-LO, all play a pivotal role in the vascular inflammatory process. We have previously shown that EETs can alleviate oxidized low-density lipoprotein (ox-LDL)-induced endothelial inflammation in primary rat pulmonary artery endothelial cells (RPAECs). Here, we investigated whether ox-LDL can promote LTB4 production through the 5-LO pathway. We further explored how exogenous EETs influence ox-LDL-induced LTB4 production and activity. We found that treatment with ox-LDL increased the production of LTB4 and further led to the expression and release of both monocyte chemoattractant protein-1 (MCP-1/CCL2) and intercellular adhesion molecule-1 (ICAM-1). All of the above ox-LDL-induced changes were attenuated by the presence of 11,12-EET and 14,15-EET, as these molecules inhibited the 5-LO pathway. Furthermore, the LTB4 receptor 1 (BLT1 receptor) antagonist U75302 attenuated ox-LDL-induced ICAM-1 and MCP-1/CCL2 expression and production, whereas LY255283, a LTB4 receptor 2 (BLT2 receptor) antagonist, produced no such effects. Moreover, in RPAECs, we demonstrated that the increased expression of 5-LO and BLT1 following ox-LDL treatment resulted from the activation of nuclear factor-κB (NF-κB) via the p38 mitogen-activated protein kinase (MAPK) pathway. Our results indicated that EETs suppress ox-LDL-induced LTB4 production and subsequent inflammatory responses by downregulating the 5-LO/BLT1 receptor pathway, in which p38 MAPK phosphorylation activates NF-κB. These results suggest that the metabolism of arachidonic acid via the 5-LO and EPOX pathways may present a mutual constraint on the physiological regulation of vascular endothelial cells. PMID:26035589

Horizontal semi-dry electroblotting for the detection of the low density lipoprotein receptor in solubilized liver membranes.

PubMed

Himber, J

1993-08-01

A high efficiency transfer of the low density lipoprotein (LDL) receptor proteins from polyacrylamide slab gel onto immobilizing nitrocellulose membranes using the horizontal semi-dry electrophoretic system is described. The transfer of the LDL receptors from solubilized rat liver microsomes was performed between two graphite plate electrodes in a continuous buffer system containing methanol and sodium dodecyl sulfate. The protein transfer was achieved in only 150 min at a constant current of 0.8 mA/cm2 at room temperature with very low Joule heat development. The homogeneous electric field yield between the two electrode plates produced a satisfactory transfer of the LDL-receptor protein band in spite of its high molecular weight, and only few protein traces remained in the polyacrylamide gel after blotting. This improved method allows a rapid and quantitative transfer of the LDL receptors without protein denaturation, since the specific binding activity of the blotted receptor is retained as demonstrated by ligand-blotting and immunoblotting.

Aggregated low-density lipoprotein induces LRP1 stabilization through E3 ubiquitin ligase CHFR downregulation in human vascular smooth muscle cells.

PubMed

Cal, Roi; García-Arguinzonis, Maisa; Revuelta-López, Elena; Castellano, José; Padró, Teresa; Badimon, Lina; Llorente-Cortés, Vicenta

2013-02-01

Low density lipoprotein retention and aggregation in the arterial intima are key processes in atherogenesis. Aggregated LDL (agLDL) is taken up through low-density lipoprotein receptor-related protein 1 (LRP1) by human vascular smooth muscle cells (VSMC). AgLDL increases LRP1 expression, at least in part, by downregulation of sterol regulatory element-binding proteins. It is unknown whether agLDL has some effect on the ubiquitin-proteasome system, and therefore on the LRP1 receptor turnover. The objective of this study was to analyze the effect of agLDL on the degradation of LRP1 by the ubiquitin-proteasome system in human VSMC. Human VSMC were isolated from the media of human coronary arteries. Ubiquitinylated LRP1 protein levels were significantly reduced in human VSMC exposed to agLDL (100 μg/mL) for 20 hours (agLDL: 3.70±0.44 a.u. versus control: 9.68±0.55 a.u). Studies performed with cycloheximide showed that agLDL prolongs the LRP1 protein half life. Pulse-chase analysis showed that LRP1 turnover rate is reduced in agLDL-exposed VSMC. Two-dimensional electrophoresis shows an alteration in the proteomic profile of a RING type E3 ubiquitin ligase, CHFR. Real-time PCR and Western blot analysis showed that agLDL (100 μg/mL) decreased the transcriptional and protein expression of CHFR. CHFR silencing increased VSMC, but not macrophage, LRP1 expression. However, CHFR silencing did not exert any effect on the classical low-density lipoprotein receptor protein levels. Furthermore, immunoprecipitation experiments demonstrated that the physical interaction between CHFR and LRP1 decreased in the presence of agLDL. Our results demonstrate that agLDL prolongs the half life of LRP1 by preventing the receptor ubiquitinylation, at least in part, through CHFR targeting. This mechanism seems to be specific for LRP1 and VSMC.

The low density lipoprotein receptor-related protein 1: Unique tissue-specific functions revealed by selective gene knockout studies

PubMed Central

Lillis, Anna P.; Van Duyn, Lauren B.; Murphy-Ullrich, Joanne E.; Strickland, Dudley K.

2008-01-01

The low-density lipoprotein (LDL) receptor-related protein (originally called LRP, but now referred to as LRP1) is a large endocytic receptor that is widely expressed in several tissues. LRP1 is a member of the LDL receptor family that plays diverse roles in various biological processes including lipoprotein metabolism, degradation of proteases, activation of lysosomal enzymes and cellular entry of bacterial toxins and viruses. Deletion of the LRP1 gene leads to lethality in mice, revealing a critical, but as of yet, undefined role in development. Tissue-specific gene deletion studies reveal an important contribution of LRP1 in the vasculature, central nervous system, in macrophages and in adipocytes. Three important properties of LRP1 dictate its diverse role in physiology: first, its ability to recognize more than thirty distinct ligands; second, its ability to bind a large number of cytoplasmic adaptor proteins via determinants located on its cytoplasmic domain in a phosphorylation-specific manner; and third, its ability to associate with and modulate the activity of other transmembrane receptors such as integrins and receptor tyrosine kinases. PMID:18626063

Haloperidol inhibits the development of atherosclerotic lesions in LDL receptor knockout mice.

PubMed

van der Sluis, Ronald J; Nahon, Joya E; Reuwer, Anne Q; Van Eck, Miranda; Hoekstra, Menno

2015-05-01

Antipsychotic drugs have been shown to modulate the expression of ATP-binding cassette transporter A1 (ABCA1), a key factor in the anti-atherogenic reverse cholesterol transport process, in vitro. Here we evaluated the potential of the typical antipsychotic drug haloperidol to modulate the cholesterol efflux function of macrophages in vitro and their susceptibility to atherosclerosis in vivo. Thioglycollate-elicited peritoneal macrophages were used for in vitro studies. Hyperlipidaemic low-density lipoprotein (LDL) receptor knockout mice were implanted with a haloperidol-containing pellet and subsequently fed a Western-type diet for 5 weeks to induce the development of atherosclerotic lesions in vivo. Haloperidol induced a 54% decrease in the mRNA expression of ABCA1 in peritoneal macrophages. This coincided with a 30% decrease in the capacity of macrophages to efflux cholesterol to apolipoprotein A1. Haloperidol treatment stimulated the expression of ABCA1 (+51%) and other genes involved in reverse cholesterol transport, that is, CYP7A1 (+98%) in livers of LDL receptor knockout mice. No change in splenic ABCA1 expression was noted. However, the average size of the atherosclerotic size was significantly smaller (-31%) in the context of a mildly more atherogenic metabolic phenotype upon haloperidol treatment. More importantly, haloperidol markedly lowered MCP-1 expression (-70%) and secretion (-28%) by peritoneal macrophages. Haloperidol treatment lowered the susceptibility of hyperlipidaemic LDL receptor knockout mice to develop atherosclerotic lesions. Our findings suggest that the beneficial effect of haloperidol on atherosclerosis susceptibility can be attributed to its ability to inhibit macrophage chemotaxis. © 2015 The British Pharmacological Society.

Proprotein convertase subtilisin/kexin type 9 (PCSK9): from structure-function relation to therapeutic inhibition.

PubMed

Tibolla, G; Norata, G D; Artali, R; Meneghetti, F; Catapano, A L

2011-11-01

This short review aims at summarizing the current information on Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) structure and function focusing also on the therapeutic possibilities based on the inhibition of this protein. PCSK9 has been recently discovered as the third gene involved in autosomal dominant hypercholesterolemia. PCSK9 binds and favors degradation of the low-density lipoprotein receptor (LDLR) and thereby modulates the plasma levels of LDL-cholesterol (LDL-C). Some of the natural occurring PCSK9 mutations increase the protein function (gain of function) and cause hypercholesterolemia, whereas loss of function mutations associate with hypocholesterolemia. Since the loss of a functional PCSK9 in humans is not associated with apparent deleterious effects, this protease is an attractive target for the development of lowering plasma LDL-C agents, either alone or in combination with statins. Inhibition of PCSK9 is emerging as a novel strategy for the treatment of hypercholesterolemia and data obtained from pre-clinical studies show that use of monoclonal antibodies, antisense oligonucleotides and short interfering RNA are effective in reducing LDL-C, clinical studies, accompanied by a better understanding of PCSK9 biology, are now necessary to address whether these new compounds will have a future in clinical practice. Copyright © 2011 Elsevier B.V. All rights reserved.

The Role of Siglec-1 and SR-BI Interaction in the Phagocytosis of Oxidized Low Density Lipoprotein by Macrophages

PubMed Central

Li, Chang; Zhu, Lin; Wu, Li-juan; Zhong, Ren-qian

2013-01-01

Background Macrophages play a proatherosclerotic role in atherosclerosis via oxLDL uptake. As an adhesion molecular of I-type lectins, Siglec-1 is highly expressed on circulating monocytes and plaque macrophages of atherosclerotic patients, but the exact role of Siglec-1 has not been elucidated. Methods In this study, oxLDL was used to stimulate Siglec-1 and some oxLDL receptors (SR-BI, CD64, CD32B, LOX-1 and TLR-4) expression on bone marrow-derived macrophages, whereas small interfering RNA was used to down-regulate Siglec-1. Meanwhile, an ELISA-based assay for Siglec-1-oxLDL interaction was performed, and co-immunoprecipitation (co-IP) and laser scanning confocal microscopy (LSCM) were used to determine the role of Siglec-1 in oxLDL uptake by macrophages. Results We found that oxLDL could up-regulate the expression of various potential oxLDL receptors, including Siglec-1, in a dose-dependent manner. Moreover, down-regulation of Siglec-1 could attenuate oxLDL uptake by Oil red O staining. LSCM revealed that Siglec-1 and CD64/SR-BI may colocalize on oxLDL-stimulated macrophage surface, whereas co-IP showed that Siglec-1 and SR-BI can be immunoprecipitated by each other. However, no direct interaction between Siglec-1 and oxLDL was found in the in vitro protein interaction system. Conclusions Thus, Siglec-1 can interact with SR-BI in the phagocytosis of oxLDL by macrophages, rather than act as an independent receptor for oxLDL. PMID:23520536

Refolding and characterization of the functional ligand-binding domain of human lectin-like oxidized LDL receptor.

PubMed

Xie, Qiuhong; Matsunaga, Shigeru; Shi, Xiaohua; Ogawa, Setsuko; Niimi, Setsuko; Wen, Zhesheng; Tokuyasu, Ken; Machida, Sachiko

2003-11-01

Lectin-like oxidized low-density lipoprotein receptor (LOX-1), a type II membrane protein that can recognize a variety of structurally unrelated macromolecules, plays an important role in host defense and is implicated in atherogenesis. To understand the interaction between human LOX-1 and its ligands, in this study the functional C-type lectin-like domain (CTLD) of LOX-1 was reconstituted at high efficiency from inactive aggregates in Escherichia coli using a refolding technique based on an artificial chaperone. The CD spectra of the purified domain suggested that the domain has alpha-helical structure and the blue shift of Trp residues was observed on refolding of the domain. Like wild-type hLOX-1, the refolded CTLD domain was able to bind modified LDL. Thus, even though CTLD contains six Cys residues that form disulfide bonds, it recovered its specific binding ability on refolding. This suggests that the correct disulfide bonds in CTLD were formed by the artificial chaperone technique. Although the domain lacked N-glycosylation, it showed high affinity for its ligand in surface plasmon resonance experiments. Thus, unglycosylated CTLD is sufficient for binding modified LDL.

microRNA-150 inhibits the formation of macrophage foam cells through targeting adiponectin receptor 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jing; Zhang, Suhua, E-mail: drsuhuangzhang@qq.com

Transformation of macrophages into foam cells plays a critical role in the pathogenesis of atherosclerosis. The aim of this study was to determine the expression and biological roles of microRNA (miR)-150 in the formation of macrophage foam cells and to identify its functional target(s). Exposure to 50 μg/ml oxidized low-density lipoprotein (oxLDL) led to a significant upregulation of miR-150 in THP-1 macrophages. Overexpression of miR-150 inhibited oxLDL-induced lipid accumulation in THP-1 macrophages, while knockdown of miR-150 enhanced lipid accumulation. apoA-I- and HDL-mediated cholesterol efflux was increased by 66% and 43%, respectively, in miR-150-overexpressing macrophages relative to control cells. In contrast, downregulationmore » of miR-150 significantly reduced cholesterol efflux from oxLDL-laden macrophages. Bioinformatic analysis and luciferase reporter assay revealed adiponectin receptor 2 (AdipoR2) as a direct target of miR-150. Small interfering RNA-mediated downregulation of AdipoR2 phenocopied the effects of miR-150 overexpression, reducing lipid accumulation and facilitating cholesterol efflux in oxLDL-treated THP-1 macrophages. Knockdown of AdipoR2 induced the expression of proliferator-activated receptor gamma (PPARγ), liver X receptor alpha (LXRα), ABCA1, and ABCG1. Moreover, pharmacological inhibition of PPARγ or LXRα impaired AdipoR2 silencing-induced upregulation of ABCA1 and ABCG1. Taken together, our results indicate that miR-150 can attenuate oxLDL-induced lipid accumulation in macrophages via promotion of cholesterol efflux. The suppressive effects of miR-150 on macrophage foam cell formation are mediated through targeting of AdipoR2. Delivery of miR-150 may represent a potential approach to prevent macrophage foam cell formation in atherosclerosis. -- Highlights: •miR-150 inhibits macrophage foam cell formation. •miR-150 accelerates cholesterol efflux from oxLDL-laden macrophages. •miR-150 suppresses macrophage foam cell formation by targeting AdipoR2.« less

Involvement of neuron-derived orphan receptor-1 (NOR-1) in LDL-induced mitogenic stimulus in vascular smooth muscle cells: role of CREB.

PubMed

Rius, Jordi; Martínez-González, José; Crespo, Javier; Badimon, Lina

2004-04-01

Low density lipoproteins (LDLs) modulate the expression of key genes involved in atherogenesis. Recently, we have shown that the transcription factor neuron-derived orphan receptor-1 (NOR-1) is involved in vascular smooth muscle cell (VSMC) proliferation. Our aim was to analyze whether NOR-1 is involved in LDL-induced mitogenic effects in VSMC. LDL induced NOR-1 expression in a time- and dose-dependent manner. Antisense oligonucleotides against NOR-1 inhibit DNA synthesis induced by LDL in VSMCs as efficiently as antisense against the protooncogene c-fos. The upregulation of NOR-1 mRNA levels by LDL involves pertusis-sensitive G protein-coupled receptors, Ca2+ mobilization, protein kinases A (PKA) and C (PKC) activation, and mitogen-activated protein kinase pathways (MAPK) (p44/p42 and p38). LDL promotes cAMP response element binding protein (CREB) activation (phosphorylation in Ser133). In transfection assays a dominant-negative of CREB inhibits NOR-1 promoter activity, while mutation of specific (cAMP response element) CRE sites in the NOR-1 promoter abolishes LDL-induced NOR-1 promoter activity. In VSMCs, LDL-induced mitogenesis involves NOR-1 upregulation through a CREB-dependent mechanism. CREB could play a role in the modulation by LDL of key genes (containing CRE sites) involved in atherogenesis.

The ligand-binding profile of HARE: hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E.

PubMed

Harris, Edward N; Weigel, Paul H

2008-08-01

The hyaluronic acid receptor for endocytosis (HARE)/ Stabilin-2 is the primary systemic scavenger receptor for hyaluronan (HA), the chondroitin sulfates (CS), dermatan sulfate (DS), and nonglycosaminoglycan (GAG) ligands such as acetylated low-density lipoprotein (AcLDL), pro-collagen propeptides, and advanced glycation end products. We recently discovered that HARE is also a systemic scavenger receptor for heparin (Hep) (Harris EN, Weigel JA, Weigel PH. 2008. The human hyaluronan receptor for endocytosis [HARE/Stabilin-2] is a systemic clearance receptor for heparin. J Biol Chem. 283:17341-17350). Our goal was to map the binding sites of eight different ligands within HARE. We used biotinylated GAGs and radio-iodinated streptavidin or AcLDL to assess the binding activities of ligands directly or indirectly (by competition with unlabeled ligands) in endocytosis assays using stable cell lines expressing the 315 or 190 kDa HA receptor for endocytosis (315- or 190-HARE) isoforms, and ELISA-like assays, with purified recombinant soluble 190-HARE ecto-domain. For example, Hep binding to HARE was competed by DS, CS-E, AcLDL, and dextran sulfate, but not by other CS types, HA, dextran, or heparosan. (125)I-AcLDL binding to HARE was partially competed by Hep and dextran sulfate, but not competed by HA. Two ligands, DS and CS-E, competed with both Hep and HA to some degree. Hep and HA binding or endocytosis is mutually inclusive; binding of these two GAGs occurs with functionally separate, noncompetitive, and apparently noninteracting domains. Thus, HARE binds to HA and Hep simultaneously. Although the domain(s) responsible for Hep binding remains unknown, the Link domain was required for HARE binding to HA, CS-A, CS-C, and CS-D. These results enable us to outline, for the first time, a binding activity map for multiple ligands of HARE.

The ligand-binding profile of HARE: hyaluronan and chondroitin sulfates A, C, and D bind to overlapping sites distinct from the sites for heparin, acetylated low-density lipoprotein, dermatan sulfate, and CS-E

PubMed Central

Harris, Edward N.; Weigel, Paul H.

2008-01-01

The hyaluronic acid receptor for endocytosis (HARE)/ Stabilin-2 is the primary systemic scavenger receptor for hyaluronan (HA), the chondroitin sulfates (CS), dermatan sulfate (DS), and nonglycosaminoglycan (GAG) ligands such as acetylated low-density lipoprotein (AcLDL), pro-collagen propeptides, and advanced glycation end products. We recently discovered that HARE is also a systemic scavenger receptor for heparin (Hep) (Harris EN, Weigel JA, Weigel PH. 2008. The human hyaluronan receptor for endocytosis [HARE/Stabilin-2] is a systemic clearance receptor for heparin. J Biol Chem. 283:17341–17350). Our goal was to map the binding sites of eight different ligands within HARE. We used biotinylated GAGs and radio-iodinated streptavidin or AcLDL to assess the binding activities of ligands directly or indirectly (by competition with unlabeled ligands) in endocytosis assays using stable cell lines expressing the 315 or 190 kDa HA receptor for endocytosis (315- or 190-HARE) isoforms, and ELISA-like assays, with purified recombinant soluble 190-HARE ecto-domain. For example, Hep binding to HARE was competed by DS, CS-E, AcLDL, and dextran sulfate, but not by other CS types, HA, dextran, or heparosan. 125I-AcLDL binding to HARE was partially competed by Hep and dextran sulfate, but not competed by HA. Two ligands, DS and CS-E, competed with both Hep and HA to some degree. Hep and HA binding or endocytosis is mutually inclusive; binding of these two GAGs occurs with functionally separate, noncompetitive, and apparently noninteracting domains. Thus, HARE binds to HA and Hep simultaneously. Although the domain(s) responsible for Hep binding remains unknown, the Link domain was required for HARE binding to HA, CS-A, CS-C, and CS-D. These results enable us to outline, for the first time, a binding activity map for multiple ligands of HARE. PMID:18499864

Lectin-like oxidized LDL receptor-1 expresses in mouse bone marrow-derived mesenchymal stem cells and stimulates their proliferation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fenxi; Stem Cell and Biotheraphy Technology Research Center, College of Lifescience and Technology, Xinxiang Medical University, Xinxiang 453003; Wang, Congrui

The bone marrow-derived mesenchymal stem cells (bmMSCs) have been widely used in cell transplant therapy, and the proliferative ability of bmMSCs is one of the determinants of the therapy efficiency. Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) as a transmembrane protein is responsible for binding, internalizing and degrading oxidized low density lipoprotein (ox-LDL). It has been identified that LOX-1 is expressed in endothelial cells, vascular smooth muscle cells, cardiomyocytes, fibroblasts and monocytes. In these cells, low concentration of ox-LDL (<40 μg/mL) stimulates their proliferation via LOX-1 activation. However, it is poor understood that whether LOX-1 is expressed in bmMSCs andmore » which role it plays. In this study, we investigated the status of LOX-1 expression in bmMSCs and its function on bmMSC proliferation. Our results showed that primary bmMSCs exhibiting a typical fibroblast-like morphology are positive for CD44 and CD90, but negative for CD34 and CD45. LOX-1 in both mRNA and protein levels is highly expressed in bmMSCs. Meanwhile, bmMSCs exhibit a strong potential to take up ox-LDL. Moreover, LOX-1 expression in bmMSCs is upregulated by ox-LDL with a dose- and time-dependent manner. Presence of ox-LDL also enhances the proliferation of bmMSCs. Knockdown of LOX-1 expression significantly inhibits ox-LDL-induced bmMSC proliferation. These findings indicate that LOX-1 plays a role in bmMSC proliferation. - Highlights: ► LOX-1 expresses in bmMSCs and mediates uptake of ox-LDL. ► Ox-LDL stimulates upregulation of LOX-1 in bmMSCs. ► Ox-LDL promotes bmMSC proliferation and expression of Mdm2, phosphor-Akt, phosphor-ERK1/2 and phosphor-NF-κB. ► LOX-1 siRNA inhibits ox-LDL-induced bmMSC proliferation and expression cell survival signals.« less

TRPV4 calcium-permeable channel is a novel regulator of oxidized LDL-induced macrophage foam cell formation.

PubMed

Goswami, Rishov; Merth, Michael; Sharma, Shweta; Alharbi, Mazen O; Aranda-Espinoza, Helim; Zhu, Xiaoping; Rahaman, Shaik O

2017-09-01

Cardiovascular disease is the number one cause of death in United States, and atherosclerosis, a chronic inflammatory arterial disease, is the most dominant underlying pathology. Macrophages are thought to orchestrate atherosclerosis by generating lipid-laden foam cells and by secreting inflammatory mediators. Emerging data support a role for a mechanical factor, e.g., matrix stiffness, in regulation of macrophage function, vascular elasticity, and atherogenesis. However, the identity of the plasma membrane mechanosensor and the mechanisms by which pro-atherogenic signals are transduced/maintained are unknown. We have obtained evidence that TRPV4, an ion channel in the transient receptor potential vanilloid family and a known mechanosensor, is the likely mediator of oxidized low-density lipoprotein (oxLDL)-dependent macrophage foam cell formation, a critical process in atherogenesis. Specifically, we found that: i) genetic ablation of TRPV4 or pharmacologic inhibition of TRPV4 activity by a specific antagonist blocked oxLDL-induced macrophage foam cell formation, and ii) TRPV4 deficiency prevented pathophysiological range matrix stiffness or scratch-induced exacerbation of oxLDL-induced foam cell formation. Mechanistically, we found that: i) plasma membrane localization of TRPV4 was sensitized to the increasing level of matrix stiffness, ii) lack of foam cell formation in TRPV4 null cells was not due to lack of expression of CD36, a major receptor for oxLDL, and iii) TRPV4 channel activity regulated oxLDL uptake but not its binding on macrophages. Altogether, these findings identify a novel role for TRPV4 in regulating macrophage foam cell formation by modulating uptake of oxLDL. These findings suggest that therapeutic targeting of TRPV4 may provide a selective approach to the treatment of atherosclerosis. Copyright © 2017. Published by Elsevier Inc.

Oxidized Low-Density Lipoprotein Suppresses Expression of Prostaglandin E Receptor Subtype EP3 in Human THP-1 Macrophages

PubMed Central

Sui, Xuxia; Liu, Yanmin; Li, Qi; Liu, Gefei; Song, Xuhong; Su, Zhongjing; Chang, Xiaolan; Zhou, Yingbi; Liang, Bin; Huang, Dongyang

2014-01-01

EP3, one of four prostaglandin E2 (PGE2) receptors, is significantly lower in atherosclerotic plaques than in normal arteries and is localized predominantly in macrophages of the plaque shoulder region. However, mechanisms behind this EP3 expression pattern are still unknown. We investigated the underlying mechanism of EP3 expression in phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 macrophages with oxidized low-density lipoprotein (oxLDL) treatment. We found that oxLDL decreased EP3 expression, in a dose-dependent manner, at both the mRNA and protein levels. Moreover, oxLDL inhibited nuclear factor-κB (NF-κB)-dependent transcription of the EP3 gene by the activation of peroxisome proliferator-activated receptor-γ (PPAR-γ). Finally, chromatin immunoprecipitation revealed decreased binding of NF-κB to the EP3 promoter with oxLDL and PPAR-γ agonist treatment. Our results show that oxLDL suppresses EP3 expression by activation of PPAR-γ and subsequent inhibition of NF-κB in macrophages. These results suggest that down-regulation of EP3 expression by oxLDL is associated with impairment of EP3-mediated anti-inflammatory effects, and that EP3 receptor activity may exert a beneficial effect on atherosclerosis. PMID:25333975

Development of a new LDL-based transport system for hydrophobic/amphiphilic drug delivery to cancer cells.

PubMed

Huntosova, Veronika; Buzova, Diana; Petrovajova, Dana; Kasak, Peter; Nadova, Zuzana; Jancura, Daniel; Sureau, Franck; Miskovsky, Pavol

2012-10-15

Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic/amphiphilic photosensitizers to tumor cells in photodynamic therapy of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by dextran. Fluorescence spectroscopy, confocal fluorescence imaging, stopped-flow experiments and flow-cytometry were used to characterize redistribution of hypericin (Hyp), a natural occurring potent photosensitizer, loaded in LDL/dextran complex to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It is shown that the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. The modification of LDL molecules by dextran does not inhibit their recognition by cellular LDL receptors and U-87 MG cellular uptake of Hyp loaded in LDL/dextran complex appears to be similar to that one observed for Hyp transported by unmodified LDL particles. Thus, it is proposed that dextran modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic/amphiphilic drugs to cancer cells expressing high level of LDL receptors. Copyright © 2012 Elsevier B.V. All rights reserved.

Andrographolide Inhibits Oxidized LDL-Induced Cholesterol Accumulation and Foam Cell Formation in Macrophages.

PubMed

Lin, Hung-Chih; Lii, Chong-Kuei; Chen, Hui-Chun; Lin, Ai-Hsuan; Yang, Ya-Chen; Chen, Haw-Wen

2018-01-01

oxLDL is involved in the pathogenesis of atherosclerotic lesions through cholesterol accumulation in macrophage foam cells. Andrographolide, the bioactive component of Andrographis paniculata, possesses several biological activities such as anti-inflammatory, anti-oxidant, and anticancer functions. Scavenger receptors (SRs), including class A SR (SR-A) and CD36, are responsible for the internalization of oxLDL. In contrast, receptors for reverse cholesterol transport, including ABCA1 and ABCG1, mediate the efflux of cholesterol from macrophage foam cells. Transcription factor liver X receptor [Formula: see text] (LXR[Formula: see text] plays a key role in lipid metabolism and inflammation as well as in the regulation of ABCA1 and ABCG1 expression. Because of the contribution of inflammation to macrophage foam cell formation and the potent anti-inflammatory activity of andrographolide, we hypothesized that andrographolide might inhibit oxLDL-induced macrophage foam cell formation. The results showed that andrographolide reduced oxLDL-induced lipid accumulation in macrophage foam cells. Andrographolide decreased the mRNA and protein expression of CD36 by inducing the degradation of CD36 mRNA; however, andrographolide had no effect on SR-A expression. In contrast, andrographolide increased the mRNA and protein expression of ABCA1 and ABCG1, which were dependent on LXR[Formula: see text]. Andrographolide enhanced LXR[Formula: see text] nuclear translocation and DNA binding activity. Treatment with the LXR[Formula: see text] antagonist GGPP and transfection with LXR[Formula: see text] siRNA reversed the ability of andrographolide to stimulate ABCA1 and ABCG1 protein expression. In conclusion, inhibition of CD36-mediated oxLDL uptake and induction of ABCA1- and ABCG1-dependent cholesterol efflux are two working mechanisms by which andrographolide inhibits macrophage foam cell formation, which suggests that andrographolide could be a potential candidate to prevent atherosclerosis.

Towards increased selectivity of drug delivery to cancer cells: development of a LDL-based nanodelivery system for hydrophobic photosensitizers

NASA Astrophysics Data System (ADS)

Buzova, Diana; Huntosova, Veronika; Kasak, Peter; Petrovajova, Dana; Joniova, Jaroslava; Dzurova, Lenka; Nadova, Zuzana; Sureau, Franck; Midkovsky, Pavol; Jancura, Daniel

2012-10-01

Low-density lipoproteins (LDL), a natural in vivo carrier of cholesterol in the vascular system, play a key role in the delivery of hydrophobic photosensitizers (pts) to tumor cells in photodynamic therapy (PDT) of cancer. To make this delivery system even more efficient, we have constructed a nano-delivery system by coating of LDL surface by polyethylene glycol (PEG) and dextran. Fluorescence spectroscopy and confocal fluorescence imaging were used to characterize redistribution of hypericin (Hyp), a natural potent pts, loaded in LDL/PEG and LDL/dextran complexes to free LDL molecules as well as to monitor cellular uptake of Hyp by U87-MG cells. It was shown than the redistribution process of Hyp between LDL molecules is significantly suppressed by dextran coating of LDL surface. On the other hand, PEG does not significantly influence this process. The modification of LDL molecules by the polymers does not inhibit their recognition by cellular LDL receptors. U-87 MG cellular uptake of Hyp loaded in LDL/PEG and LDL/dextran complexes appears to be similar to that one observed for Hyp transported by unmodified LDL particles. It is proposed that by polymers modified LDL molecules could be used as a basis for construction of a drug transport system for targeted delivery of hydrophobic drugs to cancer cells expressing high level of LDL receptors.

The Effect of a Shear Flow on the Uptake of LDL and Ac-LDL by Cultured Vascular Endothelial Cells

NASA Astrophysics Data System (ADS)

Niwa, Koichi; Karino, Takeshi

The effects of a shear flow on the uptake of fluorescence-labeled low-density lipoprotein (DiI-LDL), acetylated LDL (DiI-Ac-LDL), and lucifer yellow (LY; a tracer of fluid-phase endocytosis) by cultured bovine aortic ECs were studied using a rotating-disk shearing apparatus. It was found that 2hours’ exposure of ECs to a laminar shear flow that imposed ECs an area-mean shear stress of 10dynes/cm2 caused an increase in the uptake of DiI-LDL and LY. By contrast, the uptake of DiI-Ac-LDL was decreased by exposure of the ECs to a shear flow. Addition of dextran sulfate (DS), a competitive inhibitor of scavenger receptors, reversed the effect of a shear flow on the uptake of DiI-Ac-LDL, resulting in an increase by the imposition of a shear flow, while the uptake of DiI-LDL and LY remained unaffected. It was concluded that a shear flow promotes the endocytosis of DiI-LDL and LY by ECs, but suppresses the uptake of DiI-Ac-LDL by ECs by inhibiting scavenger receptor-mediated endocytosis.

CCC- and WASH-mediated endosomal sorting of LDLR is required for normal clearance of circulating LDL.

PubMed

Bartuzi, Paulina; Billadeau, Daniel D; Favier, Robert; Rong, Shunxing; Dekker, Daphne; Fedoseienko, Alina; Fieten, Hille; Wijers, Melinde; Levels, Johannes H; Huijkman, Nicolette; Kloosterhuis, Niels; van der Molen, Henk; Brufau, Gemma; Groen, Albert K; Elliott, Alison M; Kuivenhoven, Jan Albert; Plecko, Barbara; Grangl, Gernot; McGaughran, Julie; Horton, Jay D; Burstein, Ezra; Hofker, Marten H; van de Sluis, Bart

2016-03-11

The low-density lipoprotein receptor (LDLR) plays a pivotal role in clearing atherogenic circulating low-density lipoprotein (LDL) cholesterol. Here we show that the COMMD/CCDC22/CCDC93 (CCC) and the Wiskott-Aldrich syndrome protein and SCAR homologue (WASH) complexes are both crucial for endosomal sorting of LDLR and for its function. We find that patients with X-linked intellectual disability caused by mutations in CCDC22 are hypercholesterolaemic, and that COMMD1-deficient dogs and liver-specific Commd1 knockout mice have elevated plasma LDL cholesterol levels. Furthermore, Commd1 depletion results in mislocalization of LDLR, accompanied by decreased LDL uptake. Increased total plasma cholesterol levels are also seen in hepatic COMMD9-deficient mice. Inactivation of the CCC-associated WASH complex causes LDLR mislocalization, increased lysosomal degradation of LDLR and impaired LDL uptake. Furthermore, a mutation in the WASH component KIAA0196 (strumpellin) is associated with hypercholesterolaemia in humans. Altogether, this study provides valuable insights into the mechanisms regulating cholesterol homeostasis and LDLR trafficking.

Oxidized LDL triggers changes in oxidative stress and inflammatory biomarkers in human macrophages.

PubMed

Lara-Guzmán, Oscar J; Gil-Izquierdo, Ángel; Medina, Sonia; Osorio, Edison; Álvarez-Quintero, Rafael; Zuluaga, Natalia; Oger, Camille; Galano, Jean-Marie; Durand, Thierry; Muñoz-Durango, Katalina

2018-05-01

Oxidized low-density lipoprotein (oxLDL) is a well-recognized proatherogenic particle that functions in atherosclerosis. In this study, we established conditions to generate human oxLDL, characterized according to the grade of lipid and protein oxidation, particle size and oxylipin content. The induction effect of the cellular proatherogenic response was assessed in foam cells by using an oxLDL-macrophage interaction model. Uptake of oxLDL, reactive oxygen species production and expression of oxLDL receptors (CD36, SR-A and LOX-1) were significantly increased in THP-1 macrophages. Analyses of 35 oxylipins revealed that isoprostanes (IsoP) and prostaglandins (PGs) derived from the oxidation of arachidonic, dihomo gamma-linolenic and eicosapentaenoic acids were strongly and significantly induced in macrophages stimulated with oxLDL. Importantly, the main metabolites responsible for the THP1-macrophage response to oxLDL exposure were the oxidative stress markers 5-epi-5-F 2t -IsoP, 15-E 1t -IsoP, 8-F 3t -IsoP and 15-keto-15-F 2t -IsoP as well as inflammatory markers PGDM, 17-trans-PGF 3α , and 11β-PGF 2α , all of which are reported here, for the first time, to function in the interaction of oxLDL with THP-1 macrophages. By contrast, a salvage pathway mediated by anti-inflammatory PGs (PGE 1 and 17-trans-PGF 3α ) was also identified, suggesting a response to oxLDL-induced injury. In conclusion, when THP-1 macrophages were treated with oxLDL, a specific induction of biomarkers related to oxidative stress and inflammation was triggered. This work contributes to our understanding of initial atherogenic events mediated by oxLDL-macrophage interactions and helps to generate new approaches for their modulation. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Influence of specific mutations at the LDL-receptor gene locus on the response to simvastatin therapy in Afrikaner patients with heterozygous familial hypercholesterolaemia.

PubMed

Jeenah, M; September, W; Graadt van Roggen, F; de Villiers, W; Seftel, H; Marais, D

1993-01-04

Simvastatin, an inhibitor of HMG CoA reductase, lowers the plasma total cholesterol and LDL-cholesterol concentration in familial hypercholesterolemic patients. The efficacy of the drug shows considerable inter-individual variation, however. In this study we have assessed the influence of certain LDL-receptor gene mutations on this variation. A group of 20 male and female heterozygotic familial hypercholesterolemic patients, all Afrikaners and each bearing one of two different LDL receptor gene mutations, FH Afrikaner-1 (FH1) and FH Afrikaner-2 (FH2), was treated with simvastatin (40 mg once daily) for 18 months. The average reduction in total plasma cholesterol was 35.3% in the case of the FH2 men but only 23.2% in that of the FH1 men (P = 0.005); the reduction in LDL cholesterol concentrations was also greater in the FH2 group (39% as opposed to 27.1%, P = 0.02). The better response of the FH2 group was also evident when men and women were considered together. Female FH1 patients responded better to simvastatin treatment, however, than did males with the same gene defect. Mutations at the LDL-receptor locus may thus play a significant role in the variable efficacy of the drug. The particular mutations in the males of this group may have contributed up to 35% of the variance in total cholesterol response and 29% of the variance in LDL-cholesterol response to simvastatin treatment.

Haloperidol inhibits the development of atherosclerotic lesions in LDL receptor knockout mice

PubMed Central

van der Sluis, Ronald J; Nahon, Joya E; Reuwer, Anne Q; Van Eck, Miranda; Hoekstra, Menno

2015-01-01

Background and Purpose Antipsychotic drugs have been shown to modulate the expression of ATP-binding cassette transporter A1 (ABCA1), a key factor in the anti-atherogenic reverse cholesterol transport process, in vitro. Here we evaluated the potential of the typical antipsychotic drug haloperidol to modulate the cholesterol efflux function of macrophages in vitro and their susceptibility to atherosclerosis in vivo. Experimental Approach Thioglycollate-elicited peritoneal macrophages were used for in vitro studies. Hyperlipidaemic low-density lipoprotein (LDL) receptor knockout mice were implanted with a haloperidol-containing pellet and subsequently fed a Western-type diet for 5 weeks to induce the development of atherosclerotic lesions in vivo. Key Results Haloperidol induced a 54% decrease in the mRNA expression of ABCA1 in peritoneal macrophages. This coincided with a 30% decrease in the capacity of macrophages to efflux cholesterol to apolipoprotein A1. Haloperidol treatment stimulated the expression of ABCA1 (+51%) and other genes involved in reverse cholesterol transport, that is, CYP7A1 (+98%) in livers of LDL receptor knockout mice. No change in splenic ABCA1 expression was noted. However, the average size of the atherosclerotic size was significantly smaller (−31%) in the context of a mildly more atherogenic metabolic phenotype upon haloperidol treatment. More importantly, haloperidol markedly lowered MCP-1 expression (−70%) and secretion (−28%) by peritoneal macrophages. Conclusions and Implications Haloperidol treatment lowered the susceptibility of hyperlipidaemic LDL receptor knockout mice to develop atherosclerotic lesions. Our findings suggest that the beneficial effect of haloperidol on atherosclerosis susceptibility can be attributed to its ability to inhibit macrophage chemotaxis. PMID:25572138

[Homozygous familial hypercholesterolemia].

PubMed

Kayikçioğlu, Meral

2014-10-01

Familial hypercholesterolemia (FH) is caused by genetic deficiency of LDL receptors leading to extremely high cholesterol levels and atherosclerosis at early ages. For the prevention of early atherosclerotic cardiovascular events, effective reduction of LDL-cholesterol is necessary from the early ages. However, particularly in homozygous patients, it's almost impossible to achieve target LDL-cholesterol levels with antilipid agents including statin agents, due to the severe LDL receptor dysfunction. LDL apheresis is an effective treatment modality in severe AH patients. However, the invasive, chronic time consuming nature of this treatment decreases the compliance of these patients. Moreover, atherosclerosis progress in 25% of the patients undergoing regular and effective apheresis even though since early ages. Clinical data also indicate that there is still an unmet medical need for new effective treatments for AH patients. This review will address new therapeutic strategies targeting Apolipoprotein (Apo) B including MTTP inhibitor Lomitapideand oligonucleotide Mipomersen. As both agents are targeted against ApoB, they are expected to be effective even in receptor negative homozygous AH patients.

Mitogenic signaling of urokinase receptor-deficient kidney fibroblasts: actions of an alternative urokinase receptor and LDL receptor-related protein.

PubMed

Zhang, Guoqiang; Cai, Xiaohe; López-Guisa, Jesús M; Collins, Sarah J; Eddy, Allison A

2004-08-01

The urokinase receptor (uPAR) attenuates myofibroblast recruitment and fibrosis in the kidney. This study examined the role of uPAR and its co-receptor LDL receptor-related protein (LRP) in the regulation of kidney fibroblast proliferation and extracellular signal-regulated kinase (ERK) signaling. Compared with uPAR+/+ cells, uPAR-/- kidney fibroblasts were hyperproliferative. UPAR-/- fibroblast proliferation was 60% inhibited by an ERK kinase inhibitor. LRP protein was reduced and extracellular accumulation of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor type 1 (PAI-1) proteins were greater in uPAR-/- cultures. Addition of functional uPA protein or LRP antisense RNA significantly increased ERK signaling and cell mitosis in both genotypes. Enhanced uPAR-/- fibroblast proliferation was reversed by a recombinant nonfunctional uPA peptide. The density of cell-bound fluor-uPA was similar between uPAR-/- and uPAR+/+ fibroblasts (78 +/- 6 versus 92 +/- 16 units). These data suggest that uPAR-deficient kidney fibroblasts express lower levels of its scavenger co-receptor LRP, resulting in greater extracellular accumulation of uPA and PAI-1. Enhanced proliferation of uPAR-/- fibroblasts seems to be mediated by uPA-dependent ERK signaling via an alternative urokinase receptor.

Ursodeoxycholic acid increases low-density lipoprotein binding, uptake and degradation in isolated hamster hepatocytes.

PubMed Central

Bouscarel, B; Fromm, H; Ceryak, S; Cassidy, M M

1991-01-01

Ursodeoxycholic acid (UDCA), in contrast to both chenodeoxycholic acid (CDCA), its 7 alpha-epimer, and lithocholic acid, enhanced receptor-dependent low-density lipoprotein (LDL) uptake and degradation in isolated hamster hepatocytes. The increase in cell-associated LDL was time- and concentration-dependent, with a maximum effect observed at approx. 60 min with 1 mM-UDCA. This increase was not associated with a detergent effect of UDCA, as no significant modifications were observed either in the cellular release of lactate dehydrogenase or in Trypan Blue exclusion. The effect of UDCA was not due to a modification of the LDL particle, but rather was receptor-related. UDCA (1 mM) maximally increased the number of 125I-LDL-binding sites (Bmax.) by 35%, from 176 to 240 ng/mg of protein, without a significant modification of the binding affinity. Furthermore, following proteolytic degradation of the LDL receptor with Pronase, specific LDL binding decreased to the level of non-specific binding, and the effect of UDCA was abolished. Conversely, the trihydroxy 7 beta-hydroxy bile acid ursocholic acid and its 7 alpha-epimer, cholic acid, induced a significant decrease in LDL binding by approx. 15%. The C23 analogue of UDCA (nor-UDCA) and CDCA did not affect LDL binding. On the other hand, UDCA conjugated with either glycine (GUDCA) or taurine (TUDCA), increased LDL binding to the same extent as did the free bile acid. The half maximum time (t1/2) to reach the full effect was 1-2 min for UDCA and TUDCA, while GUDCA had a much slower t1/2 of 8.3 min. Ketoconazole (50 microM), an antifungal agent, increased LDL binding, but this effect was not additive when tested in the presence of 0.7 mM-UDCA. The results of the studies indicate that, in isolated hamster hepatocytes, the UDCA-induced increase in receptor-dependent LDL binding and uptake represents a direct effect of this bile acid. The action of the bile acid is closely related to its specific structural conformation, since UDCA and its conjugates are the only bile acids shown to express this ability thus far. However, certain agents other than bile acids, such as ketoconazole, have a similar effect. Finally, the studies suggest that the recruitment of LDL receptors from a latent pool in the hepatocellular membrane may be the mechanism by which UDCA exerts its direct effect. Images Fig. 6. PMID:1764022

FXR activation by obeticholic acid or nonsteroidal agonists induces a human-like lipoprotein cholesterol change in mice with humanized chimeric liver.

PubMed

Papazyan, Romeo; Liu, Xueqing; Liu, Jingwen; Dong, Bin; Plummer, Emily M; Lewis, Ronald D; Roth, Jonathan D; Young, Mark A

2018-06-01

Obeticholic acid (OCA) is a selective farnesoid X receptor (FXR) agonist that regulates bile acid and lipid metabolism. FXR activation induces distinct changes in circulating cholesterol among animal models and humans. The mechanistic basis of these effects has been elusive because of difficulties in studying lipoprotein homeostasis in mice, which predominantly package circulating cholesterol in HDLs. Here, we tested the effects of OCA in chimeric mice whose livers are mostly composed (≥80%) of human hepatocytes. Chimeric mice exhibited a human-like ratio of serum LDL cholesterol (LDL-C) to HDL cholesterol (HDL-C) at baseline. OCA treatment in chimeric mice increased circulating LDL-C and decreased circulating HDL-C levels, demonstrating that these mice closely model the cholesterol effects of FXR activation in humans. Mechanistically, OCA treatment increased hepatic cholesterol in chimeric mice but not in control mice. This increase correlated with decreased SREBP-2 activity and target gene expression, including a significant reduction in LDL receptor protein. Cotreatment with atorvastatin reduced total cholesterol, rescued LDL receptor protein levels, and normalized serum LDL-C. Treatment with two clinically relevant nonsteroidal FXR agonists elicited similar lipoprotein and hepatic changes in chimeric mice, suggesting that the increase in circulating LDL-C is a class effect of FXR activation.

Developmental programming of lipid metabolism and aortic vascular function in C57BL/6 mice: a novel study suggesting an involvement of LDL-receptor.

PubMed

Chechi, Kanta; McGuire, John J; Cheema, Sukhinder K

2009-04-01

We have previously shown that a maternal high-fat diet, rich in saturated fatty acids (SFA), alters the lipid metabolism of their adult offspring. The present study was designed to investigate 1) whether alterations in hepatic LDL-receptor (LDL-r) expression may serve as a potential mechanism of developmental programming behind the altered lipid metabolism of the offspring, 2) whether altered lipid metabolism leads to aortic vascular dysfunction in the offspring, 3) whether deleterious effects of SFA exposure preweaning are influenced by postweaning diet, and 4) whether gender-specific programming effects are observed. Female C57Bl/6 mice were fed a high-SFA diet or regular chow during gestation and lactation while their pups, both male and female, received either SFA or a chow diet after weaning. Male offspring obtained from mothers fed an SFA diet and those who continued on chow postweaning had higher plasma triglycerides and total cholesterol, whereas female offspring had higher plasma total and LDL cholesterol levels, lower hepatic LDL-r mRNA expression, and reduced aortic contractile responses compared with the offspring that were fed chow throughout the study. A comparison of the postweaning diet revealed significantly lower hepatic LDL-r expression along with significantly higher plasma LDL-cholesterol concentration in the female offspring that were obtained from mothers fed an SFA diet and who continued on an SFA diet postweaning, compared with the female offspring that were obtained from mothers fed an SFA diet but who continued on chow postweaning. In conclusion, we report a novel observation of hepatic LDL-r-mediated programming of altered lipid metabolism, along with aortic vascular dysfunction, in the female offspring of mothers fed a high-SFA diet. Male offspring only exhibited dyslipidemia, suggesting gender-mediated programming. This study further highlighted the role of postweaning diets in overriding the effects of maternal programming.

Impaired binding affinity of electronegative low-density lipoprotein (LDL) to the LDL receptor is related to nonesterified fatty acids and lysophosphatidylcholine content.

PubMed

Benítez, Sonia; Villegas, Virtudes; Bancells, Cristina; Jorba, Oscar; González-Sastre, Francesc; Ordóñez-Llanos, Jordi; Sánchez-Quesada, José Luis

2004-12-21

The binding characteristics of electropositive [LDL(+)] and electronegative LDL [LDL(-)] subfractions to the LDL receptor (LDLr) were studied. Saturation kinetic studies in cultured human fibroblasts demonstrated that LDL(-) from normolipemic (NL) and familial hypercholesterolemic (FH) subjects had lower binding affinity than their respective LDL(+) fractions (P < 0.05), as indicated by higher dissociation constant (K(D)) values. FH-LDL(+) also showed lower binding affinity (P < 0.05) than NL-LDL(+) (K(D), sorted from lower to higher affinity: NL-LDL(-), 33.0 +/- 24.4 nM; FH-LDL(-), 24.4 +/- 7.1 nM; FH-LDL(+), 16.6 +/- 7.0 nM; NL-LDL(+), 10.9 +/- 5.7 nM). These results were confirmed by binding displacement studies. The impaired affinity binding of LDL(-) could be attributed to altered secondary and tertiary structure of apolipoprotein B, but circular dichroism (CD) and tryptophan fluorescence (TrpF) studies revealed no structural differences between LDL(+) and LDL(-). To ascertain the role of increased nonesterified fatty acids (NEFA) and lysophosphatidylcholine (LPC) content in LDL(-), LDL(+) was enriched in NEFA or hydrolyzed with secretory phospholipase A(2). Modification of LDL gradually decreased the affinity to LDLr in parallel to the increasing content of NEFA and/or LPC. Modified LDLs with a NEFA content similar to that of LDL(-) displayed similar affinity. ApoB structure studies of modified LDLs by CD and TrpF showed no difference compared to LDL(+) or LDL(-). Our results indicate that NEFA loading or phospholipase A(2) lipolysis of LDL leads to changes that affect the affinity of LDL to LDLr with no major effect on apoB structure. Impaired affinity to the LDLr shown by LDL(-) is related to NEFA and/or LPC content rather than to structural differences in apolipoprotein B.

LOX-1 in atherosclerosis: biological functions and pharmacological modifiers

PubMed Central

Xu, Suowen; Ogura, Sayoko; Chen, Jiawei; Little, Peter J.; Moss, Joel; Liu, Peiqing

2013-01-01

Lectin-like oxidized LDL (oxLDL) receptor-1 (LOX-1, also known as OLR-1), is a class E scavenger receptor that mediates the uptake of oxLDL by vascular cells. LOX-1 is involved in endothelial dysfunction, monocyte adhesion, the proliferation, migration, and apoptosis of smooth muscle cells, foam cell formation, platelet activation, as well as plaque instability; all of these events are critical in the pathogenesis of atherosclerosis. These LOX-1-dependent biological processes contribute to plaque instability and the ultimate clinical sequelae of plaque rupture and life-threatening tissue ischemia. Administration of anti-LOX-1 antibodies inhibits atherosclerosis by decreasing these cellular events. Over the past decade, multiple drugs including naturally occurring antioxidants, statins, antiinflammatory agents, antihypertensive and antihyperglycemic drugs have been demonstrated to inhibit vascular LOX-1 expression and activity. Therefore, LOX-1 represents an attractive therapeutic target for the treatment of human atherosclerotic diseases. This review aims to integrate the current understanding of LOX-1 signaling, regulation of LOX-1 by vasculoprotective drugs, and the importance of LOX-1 in the pathogenesis of atherosclerosis. PMID:23124189

Regulation of the LDL receptor gene expression by hormones.

PubMed

Streicher, R; Kotzka, J; Müller-Wieland, D; Krone, W

1998-01-01

Promoter activity of the LDL receptor gene is stimulated by insulin and estradiol and mediated by SRE-1, which acts as a hormone sensitive cis-elemente. Using the antisense technique we reveal that SREBP-1 is selectively involved in the signal transduction pathway of insulin and IGF-I.

Fluid-Phase Pinocytosis of Native Low Density Lipoprotein Promotes Murine M-CSF Differentiated Macrophage Foam Cell Formation

PubMed Central

Xu, Qing; Bohnacker, Thomas; Wymann, Matthias P.; Kruth, Howard S.

2013-01-01

During atherosclerosis, low-density lipoprotein (LDL)-derived cholesterol accumulates in macrophages to form foam cells. Macrophage uptake of LDL promotes foam cell formation but the mechanism mediating this process is not clear. The present study investigates the mechanism of LDL uptake for macrophage colony-stimulating factor (M-CSF)-differentiated murine bone marrow-derived macrophages. LDL receptor-null (LDLR−/−) macrophages incubated with LDL showed non-saturable accumulation of cholesterol that did not down-regulate for the 24 h examined. Incubation of LDLR−/− macrophages with increasing concentrations of 125I-LDL showed non-saturable macrophage LDL uptake. A 20-fold excess of unlabeled LDL had no effect on 125I-LDL uptake by wild-type macrophages and genetic deletion of the macrophage scavenger receptors CD36 and SRA did not affect 125I-LDL uptake, showing that LDL uptake occurred by fluid-phase pinocytosis independently of receptors. Cholesterol accumulation was inhibited approximately 50% in wild-type and LDLR−/− mice treated with LY294002 or wortmannin, inhibitors of all classes of phosphoinositide 3-kinases (PI3K). Time-lapse, phase-contrast microscopy showed that macropinocytosis, an important fluid-phase uptake pathway in macrophages, was blocked almost completely by PI3K inhibition with wortmannin. Pharmacological inhibition of the class I PI3K isoforms alpha, beta, gamma or delta did not affect macrophage LDL-derived cholesterol accumulation or macropinocytosis. Furthermore, macrophages from mice expressing kinase-dead class I PI3K beta, gamma or delta isoforms showed no decrease in cholesterol accumulation or macropinocytosis when compared with wild-type macrophages. Thus, non-class I PI3K isoforms mediated macropinocytosis in these macrophages. Further characterization of the components necessary for LDL uptake, cholesterol accumulation, and macropinocytosis identified dynamin, microtubules, actin, and vacuolar type H(+)-ATPase as contributing to uptake. However, Pak1, Rac1, and Src-family kinases, which mediate fluid-phase pinocytosis in certain other cell types, were unnecessary. In conclusion, our findings provide evidence that targeting those components mediating macrophage macropinocytosis with inhibitors may be an effective strategy to limit macrophage accumulation of LDL-derived cholesterol in arteries. PMID:23536783

Expression of lectin-like oxidized LDL receptor-1 in smooth muscle cells after vascular injury

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eto, Hideyuki; Miyata, Masaaki; Kume, Noriaki

Lectin-like oxidized LDL receptor-1 (LOX-1) is an oxidized LDL receptor, and its role in restenosis after angioplasty remains unknown. We used a balloon-injury model of rabbit aorta, and reverse transcription-polymerase chain reaction revealed that LOX-1 mRNA expression was modest in the non-injured aorta, reached a peak level 2 days after injury, and remained elevated until 24 weeks after injury. Immunohistochemistry and in situ hybridization showed that LOX-1 was not detected in the media of non-injured aorta but expressed in both medial and neointimal smooth muscle cells (SMC) at 2 and 24 weeks after injury. Low concentrations of ox-LDL (10 {mu}g/mL)more » stimulated the cultured SMC proliferation, which was inhibited by antisense oligonucleotides of LOX-1 mRNA. Double immunofluorescense staining showed the colocalization of LOX-1 and proliferating cell nuclear antigen in human restenotic lesion. These results suggest that LOX-1 mediates ox-LDL-induced SMC proliferation and plays a role in neointimal formation after vascular injury.« less

Expression of lectin-like oxidized LDL receptor-1 in smooth muscle cells after vascular injury.

PubMed

Eto, Hideyuki; Miyata, Masaaki; Kume, Noriaki; Minami, Manabu; Itabe, Hiroyuki; Orihara, Koji; Hamasaki, Shuichi; Biro, Sadatoshi; Otsuji, Yutaka; Kita, Toru; Tei, Chuwa

2006-03-10

Lectin-like oxidized LDL receptor-1 (LOX-1) is an oxidized LDL receptor, and its role in restenosis after angioplasty remains unknown. We used a balloon-injury model of rabbit aorta, and reverse transcription-polymerase chain reaction revealed that LOX-1 mRNA expression was modest in the non-injured aorta, reached a peak level 2 days after injury, and remained elevated until 24 weeks after injury. Immunohistochemistry and in situ hybridization showed that LOX-1 was not detected in the media of non-injured aorta but expressed in both medial and neointimal smooth muscle cells (SMC) at 2 and 24 weeks after injury. Low concentrations of ox-LDL (10 microg/mL) stimulated the cultured SMC proliferation, which was inhibited by antisense oligonucleotides of LOX-1 mRNA. Double immunofluorescence staining showed the colocalization of LOX-1 and proliferating cell nuclear antigen in human restenotic lesion. These results suggest that LOX-1 mediates ox-LDL-induced SMC proliferation and plays a role in neointimal formation after vascular injury.

LOX-1, OxLDL, and Atherosclerosis

PubMed Central

Catapano, Alberico Luigi

2013-01-01

Oxidized low-density lipoprotein (OxLDL) contributes to the atherosclerotic plaque formation and progression by several mechanisms, including the induction of endothelial cell activation and dysfunction, macrophage foam cell formation, and smooth muscle cell migration and proliferation. Vascular wall cells express on their surface several scavenger receptors that mediate the cellular effects of OxLDL. The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is the main OxLDL receptor of endothelial cells, and it is expressed also in macrophages and smooth muscle cells. LOX-1 is almost undetectable under physiological conditions, but it is upregulated following the exposure to several proinflammatory and proatherogenic stimuli and can be detected in animal and human atherosclerotic lesions. The key contribution of LOX-1 to the atherogenic process has been confirmed in animal models; LOX-1 knockout mice exhibit reduced intima thickness and inflammation and increased expression of protective factors; on the contrary, LOX-1 overexpressing mice present an accelerated atherosclerotic lesion formation which is associated with increased inflammation. In humans, LOX-1 gene polymorphisms were associated with increased susceptibility to myocardial infarction. Inhibition of the LOX-1 receptor with chemicals or antisense nucleotides is currently being investigated and represents an emerging approach for controlling OxLDL-LOX-1 mediated proatherogenic effects. PMID:23935243

CCC- and WASH-mediated endosomal sorting of LDLR is required for normal clearance of circulating LDL

PubMed Central

Bartuzi, Paulina; Billadeau, Daniel D.; Favier, Robert; Rong, Shunxing; Dekker, Daphne; Fedoseienko, Alina; Fieten, Hille; Wijers, Melinde; Levels, Johannes H.; Huijkman, Nicolette; Kloosterhuis, Niels; van der Molen, Henk; Brufau, Gemma; Groen, Albert K.; Elliott, Alison M.; Kuivenhoven, Jan Albert; Plecko, Barbara; Grangl, Gernot; McGaughran, Julie; Horton, Jay D.; Burstein, Ezra; Hofker, Marten H.; van de Sluis, Bart

2016-01-01

The low-density lipoprotein receptor (LDLR) plays a pivotal role in clearing atherogenic circulating low-density lipoprotein (LDL) cholesterol. Here we show that the COMMD/CCDC22/CCDC93 (CCC) and the Wiskott–Aldrich syndrome protein and SCAR homologue (WASH) complexes are both crucial for endosomal sorting of LDLR and for its function. We find that patients with X-linked intellectual disability caused by mutations in CCDC22 are hypercholesterolaemic, and that COMMD1-deficient dogs and liver-specific Commd1 knockout mice have elevated plasma LDL cholesterol levels. Furthermore, Commd1 depletion results in mislocalization of LDLR, accompanied by decreased LDL uptake. Increased total plasma cholesterol levels are also seen in hepatic COMMD9-deficient mice. Inactivation of the CCC-associated WASH complex causes LDLR mislocalization, increased lysosomal degradation of LDLR and impaired LDL uptake. Furthermore, a mutation in the WASH component KIAA0196 (strumpellin) is associated with hypercholesterolaemia in humans. Altogether, this study provides valuable insights into the mechanisms regulating cholesterol homeostasis and LDLR trafficking. PMID:26965651

PCSK9 inhibition fails to alter hepatic LDLR, circulating cholesterol, and atherosclerosis in the absence of ApoE.

PubMed

Ason, Brandon; van der Hoorn, José W A; Chan, Joyce; Lee, Edward; Pieterman, Elsbet J; Nguyen, Kathy Khanh; Di, Mei; Shetterly, Susan; Tang, Jie; Yeh, Wen-Chen; Schwarz, Margrit; Jukema, J Wouter; Scott, Rob; Wasserman, Scott M; Princen, Hans M G; Jackson, Simon

2014-11-01

LDL cholesterol (LDL-C) contributes to coronary heart disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9) increases LDL-C by inhibiting LDL-C clearance. The therapeutic potential for PCSK9 inhibitors is highlighted by the fact that PCSK9 loss-of-function carriers exhibit 15-30% lower circulating LDL-C and a disproportionately lower risk (47-88%) of experiencing a cardiovascular event. Here, we utilized pcsk9(-/-) mice and an anti-PCSK9 antibody to study the role of the LDL receptor (LDLR) and ApoE in PCSK9-mediated regulation of plasma cholesterol and atherosclerotic lesion development. We found that circulating cholesterol and atherosclerotic lesions were minimally modified in pcsk9(-/-) mice on either an LDLR- or ApoE-deficient background. Acute administration of an anti-PCSK9 antibody did not reduce circulating cholesterol in an ApoE-deficient background, but did reduce circulating cholesterol (-45%) and TGs (-36%) in APOE*3Leiden.cholesteryl ester transfer protein (CETP) mice, which contain mouse ApoE, human mutant APOE3*Leiden, and a functional LDLR. Chronic anti-PCSK9 antibody treatment in APOE*3Leiden.CETP mice resulted in a significant reduction in atherosclerotic lesion area (-91%) and reduced lesion complexity. Taken together, these results indicate that both LDLR and ApoE are required for PCSK9 inhibitor-mediated reductions in atherosclerosis, as both are needed to increase hepatic LDLR expression. Copyright © 2014 by the American Society for Biochemistry and Molecular Biology, Inc.

SIRT1 decreases Lox-1-mediated foam cell formation in atherogenesis

PubMed Central

Stein, Sokrates; Lohmann, Christine; Schäfer, Nicola; Hofmann, Janin; Rohrer, Lucia; Besler, Christian; Rothgiesser, Karin M.; Becher, Burkhard; Hottiger, Michael O.; Borén, Jan; McBurney, Michael W.; Landmesser, Ulf; Lüscher, Thomas F.; Matter, Christian M.

2010-01-01

Aims Endothelial activation, macrophage infiltration, and foam cell formation are pivotal steps in atherogenesis. Our aim in this study was to analyse the role of SIRT1, a class III deacetylase with important metabolic functions, in plaque macrophages and atherogenesis. Methods and results Using partial SIRT1 deletion in atherosclerotic mice, we demonstrate that SIRT1 protects against atherosclerosis by reducing macrophage foam cell formation. Peritoneal macrophages from heterozygous SIRT1 mice accumulate more oxidized low-density lipoprotein (oxLDL), thereby promoting foam cell formation. Bone marrow-restricted SIRT1 deletion confirmed that SIRT1 function in macrophages is sufficient to decrease atherogenesis. Moreover, we show that SIRT1 reduces the uptake of oxLDL by diminishing the expression of lectin-like oxLDL receptor-1 (Lox-1) via suppression of the NF-κB signalling pathway. Conclusion Our findings demonstrate protective effects of SIRT1 in atherogenesis and suggest pharmacological SIRT1 activation as a novel anti-atherosclerotic strategy by reducing macrophage foam cell formation. PMID:20418343

Myeloperoxidase-generated reactive nitrogen species convert LDL into an atherogenic form in vitro

PubMed Central

Podrez, Eugene A.; Schmitt, David; Hoff, Henry F.; Hazen, Stanley L.

1999-01-01

Oxidized LDL is implicated in atherosclerosis; however, the pathways that convert LDL into an atherogenic form in vivo are not established. Production of reactive nitrogen species may be one important pathway, since LDL recovered from human atherosclerotic aorta is enriched in nitrotyrosine. We now report that reactive nitrogen species generated by the MPO-H2O2-NO2– system of monocytes convert LDL into a form (NO2-LDL) that is avidly taken up and degraded by macrophages, leading to massive cholesterol deposition and foam cell formation, essential steps in lesion development. Incubation of LDL with isolated MPO, an H2O2-generating system, and nitrite (NO2–)— a major end-product of NO metabolism—resulted in nitration of apolipoprotein B 100 tyrosyl residues and initiation of LDL lipid peroxidation. The time course of LDL protein nitration and lipid peroxidation paralleled the acquisition of high-affinity, concentration-dependent, and saturable binding of NO2-LDL to human monocyte–derived macrophages and mouse peritoneal macrophages. LDL modification and conversion into a high-uptake form occurred in the absence of free metal ions, required NO2–, occurred at physiological levels of Cl–, and was inhibited by heme poisons, catalase, and BHT. Macrophage binding of NO2-LDL was specific and mediated by neither the LDL receptor nor the scavenger receptor class A type I. Exposure of macrophages to NO2-LDL promoted cholesteryl ester synthesis, intracellular cholesterol and cholesteryl ester accumulation, and foam cell formation. Collectively, these results identify MPO-generated reactive nitrogen species as a physiologically plausible pathway for converting LDL into an atherogenic form. PMID:10359564

PCSK9 inhibition in the management of familial hypercholesterolemia.

PubMed

Ogura, Masatsune

2018-01-01

Familial hypercholesterolemia (FH) is a frequent hereditary metabolic disease characterized by high serum low-density lipoprotein (LDL) cholesterol concentration and premature atherosclerotic cardiovascular disease (ASCVD). The discovery of the LDL receptor as one of the causative genes of FH enabled us to understand the pathophysiology of FH and paved the way for developing statins. Similar to LDL receptor, discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9) also created an opportunity for developing its inhibitors. Since PCSK9 degrades LDL receptor protein, inhibiting PCSK9 will be an effective strategy. Evolocumab and alirocumab, anti-PCSK9 antibodies that inhibit binding between PCSK9 and LDL receptors, are now available in Japan. Adding an anti-PCSK9 antibody to standard therapy with statin alone or statin combined with ezetimibe further reduced serum LDL cholesterol levels by around 60% and they significantly decrease cardiovascular event incidence as compared with placebo. Additionally, the strong LDL cholesterol lowering effect of anti-PCSK9 antibody therapies has reportedly enabled the frequency of lipoprotein apheresis to be reduced or to be discontinued. As alternative strategies against PCSK9, antisense oligonucleotide agents that inhibit PCSK9 protein synthesis as well as a small interfering (or short interference) RNA (siRNA) for PCSK9 are also being developed. While relatively high cost can be given as a problem, PCSK9 inhibitors are able to reduce LDL cholesterol dramatically even in FH patients who could not achieve targets until now. To ensure that these drugs are given to the patients who really need them, it is necessary to raise the diagnosis rate and family screening has to be more actively conducted. Finally, it has been reported that PCSK9 is expressed not only in hepatocytes but also in other cells such as epithelial cells in small intestine and vascular smooth muscle cells in atherosclerotic plaque. Further research regarding extra-hepatic pathophysiology of PCSK9 is expected. Copyright © 2017 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Increased binding of LDL and VLDL to apo B,E receptors of hepatic plasma membrane of rats treated with Fibernat.

PubMed

Venkatesan, Nandini; Devaraj, S Niranjali; Devaraj, H

2003-10-01

Research has focussed on the hypocholesterolemic effects of certain types of dietary fiber such as enhancing conversion of hepatic cholesterol to bile acids or increase in catabolism of low density lipoprotein (LDL) via the apo B,E receptor. The effect of oral administration of a unique fibre cocktail of fenugreek seed powder, guar gum and wheat bran (Fibernat) and its varied effects on some aspects of lipid metabolism and cholesterol homeostasis in rats were examined. Rats were administered Fibernat along with the atherogenic diet containing 1.5 % cholesterol and 0.1 % cholic acid. Amounts of hepatic lipids, hepatic and fecal bile acids and activity of hepatic triglyceride lipase (HTGL) were determined. Transmission electron microscopic examination of the liver tissue and extent of uptake of (125)I-LDL and (125)I-VLDL by the hepatic apo B,E receptor was carried out. Food intake and body weight gain were similar between the 3 different dietary groups. Fibernat intake significantly increased apo B,E receptor expression in rat liver as reflected by an increase in the maximum binding capacity (B(max)) of the apo B,E receptor to (125)I-LDL and (125)I-VLDL. The activity of HTGL was increased by approximately 1.5-fold in Fibernat-fed rats as compared to those fed the atherogenic diet alone. A marked hypocholesterolemic effect was observed. Cholesterol homeostasis was achieved in Fibernat-fed rats. Two possible mechanisms are postulated to be responsible for the observed hypocholesterolemic effect a) an increase in conversion of cholesterol to bile acids and b) possibly by intra-luminal binding which resulted in increased fecal excretion of bile acids and neutral sterols. The resulting reduction in cholesterol content of liver cells coupled with upregulation of hepatic apo B,E receptors and increased clearance of circulating atherogenic lipoproteins-LDL and very low density lipoprotein (LDL and VLDL)-is the main mechanism involved in the hypocholesterolemic effect of Fibernat. The results suggest that Fibernat's effect on plasma LDL concentration is also possibly mediated by increased receptor-mediated catabolism of VLDL. Thus, Fibernat therapy is an effective adjunct to diet therapy and might find potential use in the therapy of hyperlipidemic subjects.

Sirtuin 1 Mediates the Actions of Peroxisome Proliferator-Activated Receptor δ on the Oxidized Low-Density Lipoprotein-Triggered Migration and Proliferation of Vascular Smooth Muscle Cells.

PubMed

Hwang, Jung Seok; Ham, Sun Ah; Yoo, Taesik; Lee, Won Jin; Paek, Kyung Shin; Lee, Chi-Ho; Seo, Han Geuk

2016-11-01

Peroxisome proliferator-activated receptor δ (PPARδ) has been implicated in vascular pathophysiology. However, its functions in atherogenic changes of the vascular wall have not been fully elucidated. PPARδ activated by GW501516 (2-[2-methyl-4-[[4-methyl-2-[4-(trifluoromethyl)phenyl]-1,3-thiazol-5-yl]methylsulfanyl]phenoxy]acetic acid) significantly inhibited the migration and proliferation of vascular smooth muscle cells (VSMCs) triggered by oxidized low-density lipoprotein (oxLDL). These GW501516-mediated effects were significantly reversed by PPARδ-targeting small-interfering RNA (siRNA), indicating that PPARδ is involved in the action of GW501516. The antiproliferative effect of GW501516 was directly linked to cell cycle arrest at the G 0 /G 1 to S phase transition, which was followed by the down-regulation of cyclin-dependent kinase 4 along with increased levels of p21 and p53. In VSMCs treated with GW501516, the expression of sirtuin 1 (SIRT1) mRNA and protein was time-dependently increased. This GW501516-mediated up-regulation of SIRT1 expression was also demonstrated even in the presence of oxLDL. In addition, GW501516-dependent inhibition of oxLDL-triggered migration and proliferation of VSMCs was almost completely abolished in the presence of SIRT1-targeting siRNA. These effects of GW501516 on oxLDL-triggered phenotypic changes of VSMCs were also demonstrated via activation or inhibition of SIRT1 activity by resveratrol or sirtinol, respectively. Finally, gain or loss of SIRT1 function imitated the action of PPARδ on oxLDL-triggered migration and proliferation of VSMCs. Taken together, these observations indicate that PPARδ-dependent up-regulation of SIRT1 contributes to the antiatherogenic activities of PPARδ by suppressing the migration and proliferation of VSMCs linked to vascular diseases such as restenosis and atherosclerosis. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Carbamylated low-density lipoprotein attenuates glucose uptake via a nitric oxide-mediated pathway in rat L6 skeletal muscle cells.

PubMed

Choi, Hye-Jung; Lee, Kyoung Jae; Hwang, Eun Ah; Mun, Kyo-Cheol; Ha, Eunyoung

2015-07-01

Carbamylation is a cyanate-mediated posttranslational modification. We previously reported that carbamylated low-density lipoprotein (cLDL) increases reactive oxygen species and apoptosis via a lectin-like oxidized LDL receptor mediated pathway in human umbilical vein endothelial cells. A recent study reported an association between cLDL and type 2 diabetes mellitus (T2DM). In the current study, the effects of cLDL on glucose transport were explored in skeletal muscle cells. The effect of cLDL on glucose uptake, glucose transporter 4 (GLUT4) translocation, and signaling pathway were examined in cultured rat L6 muscle cells using 2-deoxyglucose uptake, immunofluorescence staining and western blot analysis. The quantity of nitric oxide (NO) was evaluated by the Griess reaction. The effect of native LDL (nLDL) from patients with chronic renal failure (CRF-nLDL) on glucose uptake was also determined. It was observed that cLDL significantly attenuated glucose uptake and GLUT4 translocation to the membrane, which was mediated via the increase in inducible nitric oxide synthase (iNOS)-induced NO production. Tyrosine nitration of the insulin receptor substrate-1 (IRS‑1) was increased. It was demonstrated that CRF-nLDL markedly reduced glucose uptake compared with nLDL from healthy subjects. Collectively, these findings indicate that cLDL, alone, attenuates glucose uptake via NO-mediated tyrosine nitration of IRS‑1 in L6 rat muscle cells and suggests the possibility that cLDL is involved in the pathogenesis of T2DM.

Selective uptake and efflux of cholesteryl linoleate in LDL by macrophages expressing 12/15-lipoxygenase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takahashi, Yoshitaka; Zhu, Hong; Xu, Wanpeng

Oxidation of low density lipoprotein (LDL) is a critical step for airtightness, and the role of the 12/15-lipoxygenase (12/15-Lox) as well as LDL receptor-related protein (Lp) expressed in macrophages in this process has been suggested. The oxygenation of cholesteryl linoleate in LDL by mouse macrophage-like Joe.1 cells over expressing 12/15-Lox was inhibited by an anti-Lp antibody but not by an anti-LDL receptor antibody. When the cells were incubated with LDL double-labeled by [{sup 3}H]cholesteryl linoleate and [{sup 125}I]apo B, association with the cells of [{sup 3}H]cholesteryl linoleate expressed as LDL protein equivalent exceeded that of [{sup 125}I]apo B, indicating selectivemore » uptake of [{sup 3}H]cholesteryl linoleate from LDL to these cells. An anti-Lp antibody inhibited the selective uptake of [{sup 3}H]cholesteryl ester by 62% and 81% with the 12/15-Lox-expressing cells and macrophages, respectively. Furthermore, addition of LDL to the culture medium of the [{sup 3}H]cholesteryl linoleate-labeled 12/15-Lox-expressing cells increased the release of [{sup 3}H]cholesteryl linoleate to the medium in LDL concentration- and time-dependent manners. The transport of [{sup 3}H]cholesteryl linoleate from the cells to LDL was also inhibited by an anti-Lp antibody by 75%. These results strongly suggest that Lp contributes to the LDL oxidation by 12/15-Lox in macrophages by selective uptake and efflux of cholesteryl ester in the LDL particle.« less

Expression of the macrophage scavenger receptor, a multifunctional lipoprotein receptor, in microglia associated with senile plaques in Alzheimer's disease.

PubMed Central

Christie, R. H.; Freeman, M.; Hyman, B. T.

1996-01-01

The macrophage scavenger receptor is a multifunctional receptor whose ligands include oxidized low density lipoprotein (LDL), as well as several other polyanionic macromolecules. Although the capacity of the receptor to bind modified LDL has implicated it in the process of atherosclerosis, its physiological role remains uncertain. We have examined human brain for expression of macrophage scavenger receptor as part of ongoing studies of lipoprotein receptors in the central nervous system. The receptor is expressed on microglia, but not on astrocytes, neurons, or vessel-associated structures. In Alzheimer disease, there is strong expression of the scavenger receptor in association with senile plaques. Images Figure 2 Figure 3 Figure 4 PMID:8579103

CD36 signaling inhibits the translation of heat shock protein 70 induced by oxidized low density lipoprotein through activation of peroxisome proliferators-activated receptor γ

PubMed Central

Lee, Kyoung-Jin; Ha, Eun-Soo; Kim, Min-Kyoung; Lee, Sang-Hoon; Suh, Jae Sung; Lee, Sun-Hee; Park, Kyeong Han; Park, Jeong Hyun; Kim, Dae Joong; Kang, Dongmin; Kim, Byung-Chul; Jeoung, Dooil; Kim, Young-Kyoun; Kim, Ho-Dirk

2008-01-01

Oxidized LDL (OxLDL), a causal factor in atherosclerosis, induces the expression of heat shock proteins (Hsp) in a variety of cells. In this study, we investigated the role of CD36, an OxLDL receptor, and peroxisome proliferator-activated receptor γ (PPARγ) in OxLDL-induced Hsp70 expression. Overexpression of dominant-negative forms of CD36 or knockdown of CD36 by siRNA transfection increased OxLDL-induced Hsp70 protein expression in human monocytic U937 cells, suggesting that CD36 signaling inhibits Hsp70 expression. Similar results were obtained by the inhibition of PPARγ activity or knockdown of PPARγ expression. In contrast, overexpression of CD36, which is induced by treatment of MCF-7 cells with troglitazone, decreased Hsp70 protein expression induced by OxLDL. Interestingly, activation of PPARγ through a synthetic ligand, ciglitazone or troglitazone, decreased the expression levels of Hsp70 protein in OxLDL-treated U937 cells. However, major changes in Hsp70 mRNA levels were not observed. Cycloheximide studies demonstrate that troglitazone attenuates Hsp70 translation but not Hsp70 protein stability. PPARγ siRNA transfection reversed the inhibitory effects of troglitazone on Hsp70 translation. These results suggest that CD36 signaling may inhibit stress-induced gene expression by suppressing translation via activation of PPARγ in monocytes. These findings reveal a new molecular basis for the anti-inflammatory effects of PPARγ. PMID:19116451

Effect of resveratrol, tyrosol and beta-sitosterol on oxidised low-density lipoprotein-stimulated oxidative stress, arachidonic acid release and prostaglandin E2 synthesis by RAW 264.7 macrophages.

PubMed

Vivancos, Marta; Moreno, Juan J

2008-06-01

Oxidation of LDL is hypothesised as an early and critical event in atherogenesis. Oxidised LDL (oxLDL) favour the transformation of macrophages into foam cells, an important cell involved in atherosclerosis. Furthermore, oxLDL cause multiple changes in macrophage functions. Thus, oxLDL induces certain genes, suppresses others and alters cell lipid metabolism. Consumption of a Mediterranean diet is associated with a low incidence of atherosclerotic disease, but data about the specific dietary constituents involved and mechanisms conferring cardioprotection are still sparse. The aim of the present study was to determine the effect of representative minor components of wine and olive oil on reactive oxygen species and eicosanoid synthesis induced by oxLDL-stimulated macrophages. We observed that exposure to non-toxic oxLDL concentrations leads to the production of H2O2 by RAW 264.7 macrophages and this effect was reverted by apocynin, a NADPH oxidase inhibitor. Moreover, oxLDL induced arachidonic acid (AA) release, cyclo-oxygenase-2 overexpression and subsequent PGE2 release. We observed that resveratrol and tyrosol revert H2O2 production induced by oxLDL as well as AA release and PGE2 synthesis and that these effects were not as a consequence of these compounds interfering with the oxLDL binding to their receptors. Interestingly, beta-sitosterol presence enhances these polyphenol actions. Thus, we found a synergistic action of polyphenols of olive oil and wine and beta-sitosterol of olive oil led to the modulation of the effects of oxLDL on oxidative stress and PGE2 synthesis.

Low-density lipoprotein receptor genetic polymorphism in chronic hepatitis C virus Egyptian patients affects treatment response

PubMed Central

Naga, Mazen; Amin, Mona; Algendy, Dina; Elbadry, Ahmed; Fawzi, May; Foda, Ayman; Esmat, Serag; Sabry, Dina; Rashed, Laila; Gabal, Samia; Kamal, Manal

2015-01-01

AIM: To correlate a genetic polymorphism of the low-density lipoprotein (LDL) receptor with antiviral responses in Egyptian chronic hepatitis C virus (HCV) patients. METHODS: Our study included 657 HCV-infected patients with genotype 4 who received interferon-based combination therapy. Patients were divided into two groups based on their response to therapy: 356 were responders, and 301 were non-responders. Patients were compared to 160 healthy controls. All patients and controls underwent a thorough physical examination, measurement of body mass index (BMI) and the following laboratory tests: serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, total bilirubin, direct bilirubin, prothrombin time, prothrombin concentration, INR, complete blood count, serum creatinine, fasting blood sugar, HCV antibody, and hepatitis B surface antigen. All HCV patients were further subjected to the following laboratory tests: HCV-RNA using quantitative polymerase chain reaction (PCR), antinuclear antibodies, thyroid-stimulating hormone, an LDL receptor (LDLR) genotype study of LDLR exon8c.1171G>A and exon10c.1413G>A using real-time PCR-based assays, abdominal ultrasonography, ultrasonographic-guided liver biopsy, and histopathological examination of liver biopsies. Correlations of LDL receptor polymorphisms with HAI, METAVIR score, presence of steatosis, and BMI were performed in all cases. RESULTS: There were no statistically significant differences in response rates between the different types of interferon used or LDLR exon10c.1413G>A. However, there was a significant difference in the frequency of the LDL receptor exon8c.1171G>A genotype between cases (AA: 25.9%, GA: 22.2%, GG: 51.9%) and controls (AA: 3.8%, GA: 53.1% and GG: 43.1%) (P < 0.001). There was a statistically significant difference in the frequency of the LDLR exon 8C:1171 G>A polymorphism between responders (AA: 3.6%, GA: 15.2%, GG: 81.2%) and non-responders (AA: 52.2%, GA: 30.6%, GG: 17.2%) (P < 0.001). The G allele of LDL receptor exon8c.1171G>A predominated in cases and controls over the A allele, and a statistically significant association with response to interferon was observed. The frequency of the LDLR exon8c.1171G>A allele in non-responders was: A: 67.4% and G: 32.6 vs A: 11.2% and G: 88.8% in responders (P < 0.001). Therefore, carriers of the A allele exhibited a 16.4 times greater risk for non-response. There was a significant association between LDL receptors exon8 c.1171G>A and HAI (P < 0.011). There was a significant association between LDL receptors exon8c.1171G>A and BMI. The mean BMI level was highest in patients carrying the AA genotype (28.7 ± 4.7 kg/m2) followed by the GA genotype (28.1 ± 4.8 kg/m2). The lowest BMI was the GG genotype (26.6 ± 4.3 kg/m2) (P < 0.001). The only significant associations were found between LDL receptors exon8 c.1171G>A and METAVIR score or steatosis (P < 0.001). CONCLUSION: LDL receptor gene polymorphisms play a role in the treatment response of HCV and the modulation of disease progression in Egyptians infected with chronic HCV. PMID:26494968

Low-density lipoprotein receptor genetic polymorphism in chronic hepatitis C virus Egyptian patients affects treatment response.

PubMed

Naga, Mazen; Amin, Mona; Algendy, Dina; Elbadry, Ahmed; Fawzi, May; Foda, Ayman; Esmat, Serag; Sabry, Dina; Rashed, Laila; Gabal, Samia; Kamal, Manal

2015-10-21

To correlate a genetic polymorphism of the low-density lipoprotein (LDL) receptor with antiviral responses in Egyptian chronic hepatitis C virus (HCV) patients. Our study included 657 HCV-infected patients with genotype 4 who received interferon-based combination therapy. Patients were divided into two groups based on their response to therapy: 356 were responders, and 301 were non-responders. Patients were compared to 160 healthy controls. All patients and controls underwent a thorough physical examination, measurement of body mass index (BMI) and the following laboratory tests: serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, albumin, total bilirubin, direct bilirubin, prothrombin time, prothrombin concentration, INR, complete blood count, serum creatinine, fasting blood sugar, HCV antibody, and hepatitis B surface antigen. All HCV patients were further subjected to the following laboratory tests: HCV-RNA using quantitative polymerase chain reaction (PCR), antinuclear antibodies, thyroid-stimulating hormone, an LDL receptor (LDLR) genotype study of LDLR exon8c.1171G>A and exon10c.1413G>A using real-time PCR-based assays, abdominal ultrasonography, ultrasonographic-guided liver biopsy, and histopathological examination of liver biopsies. Correlations of LDL receptor polymorphisms with HAI, METAVIR score, presence of steatosis, and BMI were performed in all cases. There were no statistically significant differences in response rates between the different types of interferon used or LDLR exon10c.1413G>A. However, there was a significant difference in the frequency of the LDL receptor exon8c.1171G>A genotype between cases (AA: 25.9%, GA: 22.2%, GG: 51.9%) and controls (AA: 3.8%, GA: 53.1% and GG: 43.1%) (P < 0.001). There was a statistically significant difference in the frequency of the LDLR exon 8C:1171 G>A polymorphism between responders (AA: 3.6%, GA: 15.2%, GG: 81.2%) and non-responders (AA: 52.2%, GA: 30.6%, GG: 17.2%) (P < 0.001). The G allele of LDL receptor exon8c.1171G>A predominated in cases and controls over the A allele, and a statistically significant association with response to interferon was observed. The frequency of the LDLR exon8c.1171G>A allele in non-responders was: A: 67.4% and G: 32.6 vs A: 11.2% and G: 88.8% in responders (P < 0.001). Therefore, carriers of the A allele exhibited a 16.4 times greater risk for non-response. There was a significant association between LDL receptors exon8 c.1171G>A and HAI (P < 0.011). There was a significant association between LDL receptors exon8c.1171G>A and BMI. The mean BMI level was highest in patients carrying the AA genotype (28.7 ± 4.7 kg/m(2)) followed by the GA genotype (28.1 ± 4.8 kg/m(2)). The lowest BMI was the GG genotype (26.6 ± 4.3 kg/m(2)) (P < 0.001). The only significant associations were found between LDL receptors exon8 c.1171G>A and METAVIR score or steatosis (P < 0.001). LDL receptor gene polymorphisms play a role in the treatment response of HCV and the modulation of disease progression in Egyptians infected with chronic HCV.

Use of LDL receptor-targeting peptide vectors for in vitro and in vivo cargo transport across the blood-brain barrier.

PubMed

Molino, Yves; David, Marion; Varini, Karine; Jabès, Françoise; Gaudin, Nicolas; Fortoul, Aude; Bakloul, Karima; Masse, Maxime; Bernard, Anne; Drobecq, Lucile; Lécorché, Pascaline; Temsamani, Jamal; Jacquot, Guillaume; Khrestchatisky, Michel

2017-05-01

The blood-brain barrier (BBB) prevents the entry of many drugs into the brain and, thus, is a major obstacle in the treatment of CNS diseases. There is some evidence that the LDL receptor (LDLR) is expressed at the BBB and may participate in the transport of endogenous ligands from blood to brain, a process referred to as receptor-mediated transcytosis. We previously described a family of peptide vectors that were developed to target the LDLR. In the present study, in vitro BBB models that were derived from wild-type and LDLR-knockout animals ( ldlr -/- ) were used to validate the specific LDLR-dependent transcytosis of LDL via a nondegradative route. We next showed that LDLR-targeting peptide vectors, whether in fusion or chemically conjugated to an Ab Fc fragment, promote binding to apical LDLR and transendothelial transfer of the Fc fragment across BBB monolayers via the same route as LDL. Finally, we demonstrated in vivo that LDLR significantly contributes to the brain uptake of vectorized Fc. We thus provide further evidence that LDLR is a relevant receptor for CNS drug delivery via receptor-mediated transcytosis and that the peptide vectors we developed have the potential to transport drugs, including proteins or Ab based, across the BBB.-Molino, Y., David, M., Varini, K., Jabès, F., Gaudin, N., Fortoul, A., Bakloul, K., Masse, M., Bernard, A., Drobecq, L., Lécorché, P., Temsamani, J., Jacquot, G., Khrestchatisky, M. Use of LDL receptor-targeting peptide vectors for in vitro and in vivo cargo transport across the blood-brain barrier. © FASEB.

The moderate essential amino acid restriction entailed by low-protein vegan diets may promote vascular health by stimulating FGF21 secretion.

PubMed

McCarty, Mark F

2016-02-12

The serum total and LDL cholesterol levels of long-term vegans tend to be very low. The characteristically low ratio of saturated to unsaturated fat in vegan diets, and the absence of cholesterol in such diets, clearly contribute to this effect. But there is reason to suspect that the quantity and composition of dietary protein also play a role in this regard. Vegan diets of moderate protein intake tend to be relatively low in certain essential amino acids, and as a result may increase hepatic activity of the kinase GCN2, which functions as a gauge of amino acid status. GCN2 activation boosts the liver's production of fibroblast growth factor 21 (FGF21), a factor which favorably affects serum lipids and metabolic syndrome. The ability of FGF21 to decrease LDL cholesterol has now been traced to at least two mechanisms: a suppression of hepatocyte expression of sterol response element-binding protein-2 (SREBP-2), which in turn leads to a reduction in cholesterol synthesis; and up-regulated expression of hepatocyte LDL receptors, reflecting inhibition of a mechanism that promotes proteasomal degradation of these receptors. In mice, the vascular benefits of FGF21 are also mediated by favorable effects on adipocyte function - most notably, increased adipocyte secretion of adiponectin, which directly exerts anti-inflammatory effects on the vasculature which complement the concurrent reduction in LDL particles in preventing or reversing atherosclerosis. If, as has been proposed, plant proteins preferentially stimulate glucagon secretion owing to their amino acid composition, this would represent an additional mechanism whereby plant protein promotes FGF21 activity, as glucagon acts on the liver to boost transcription of the FGF21 gene.

Effects of PCSK9 inhibition with alirocumab on lipoprotein metabolism in healthy humans

USDA-ARS?s Scientific Manuscript database

Background: Alirocumab, a monoclonal antibody to proprotein convertase subtilisin/kexin type 9 (PCSK9), lowers plasma low density lipoprotein cholesterol (LDL-C) and apolipoprotein B100 (apoB). Although studies in mice and cells have identified increased hepatic LDL receptors as the basis for LDL lo...

Human LDL Structural Diversity Studied by IR Spectroscopy

PubMed Central

Fernández-Higuero, José A.; Salvador, Ana M.; Martín, Cesar; Milicua, José Carlos G.; Arrondo, José L. R.

2014-01-01

Lipoproteins are responsible for cholesterol traffic in humans. Low density lipoprotein (LDL) delivers cholesterol from liver to peripheral tissues. A misleading delivery can lead to the formation of atherosclerotic plaques. LDL has a single protein, apoB-100, that binds to a specific receptor. It is known that the failure associated with a deficient protein-receptor binding leads to plaque formation. ApoB-100 is a large single lipid-associated polypeptide difficulting the study of its structure. IR spectroscopy is a technique suitable to follow the different conformational changes produced in apoB-100 because it is not affected by the size of the protein or the turbidity of the sample. We have analyzed LDL spectra of different individuals and shown that, even if there are not big structural changes, a different pattern in the intensity of the band located around 1617 cm−1 related with strands embedded in the lipid monolayer, can be associated with a different conformational rearrangement that could affect to a protein interacting region with the receptor. PMID:24642788

MicroRNA-98 rescues proliferation and alleviates ox-LDL-induced apoptosis in HUVECs by targeting LOX-1

PubMed Central

Chen, Zhibo; Wang, Mian; He, Qiong; Li, Zilun; Zhao, Yang; Wang, Wenjian; Ma, Jieyi; Li, Yongxin; Chang, Guangqi

2017-01-01

Oxidized low-density lipoprotein (ox-LDL) is a major and critical mediator of atherosclerosis, and the underlying mechanism is thought to involve the ox-LDL-induced dysfunction of endothelial cells (ECs). MicroRNAs (miRNAs), which are a group of small non-coding RNA molecules that post-transcriptionally regulate the expression of target genes, have been associated with diverse cellular functions and the pathogenesis of various diseases, including atherosclerosis. miRNA-98 (miR-98) has been demonstrated to be involved in the regulation of cellular apoptosis; however, the role of miR-98 in ox-LDL-induced dysfunction of ECs and atherosclerosis has yet to be elucidated. Therefore, the present study aimed to investigate the role of miR-98 in ox-LDL-induced dysfunction of ECs and the underlying mechanism. It was demonstrated that miR-98 expression was markedly downregulated in ox-LDL-treated human umbilical vein ECs (HUVECs) and that miR-98 promoted the proliferation and alleviated apoptosis of HUVECs exposed to ox-LDL. In addition, the results demonstrated that lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1) was a direct target of miR-98 in HUVECs, as indicated by a luciferase assay. The results of the present study suggested that miR-98 may inhibit the uptake of toxic ox-LDL, maintain HUVEC proliferation and protect HUVECs against apoptosis via the suppression of LOX-1. PMID:28565756

Oxytocin inhibits ox-LDL-induced adhesion of monocytic THP-1 cells to human brain microvascular endothelial cells.

PubMed

Liu, Shuyan; Pan, Shengying; Tan, Jing; Zhao, Weina; Liu, Fengguo

2017-12-15

The attachment of monocytes to human brain microvascular endothelial cells (HBMVEs) caused by oxidized low-density lipoprotein (ox-LDL) is associated with an early event and the pathological progression of cerebrovascular diseases. Oxytocin (OT) is a human peptide hormone that is traditionally used as a medication to facilitate childbirth. However, little information is available regarding the physiological function of OT in brain endothelial dysfunction. In the present study, our results indicate that the oxytocin receptor (OTR) was expressed in human brain microvascular endothelial cells (HBMVEs) and was upregulated in response to ox-LDL in a concentration-dependent manner. Notably, OT significantly suppressed ox-LDL-induced attachment of THP-1 monocytes to HBMVEs. Furthermore, we found that OT reduced the expression of adhesion molecules, such as VCAM-1 and E-selectin. Interestingly, it was shown that OT could restore ox-LDL-induced reduction of KLF4 in HBMVEs. Importantly, knockdown of KLF4 abolished the inhibitory effects of OT on ox-LDL-induced expressions of VCAM-1 and E-selectin as well as the adhesion of human monocytic THP-1 cells to endothelial HBMVEs. Mechanistically, we found that the stimulatory effects of OT on KLF4 expression are mediated by the MEK5/MEF2A pathway. Copyright © 2017. Published by Elsevier Inc.

Uptake of lactosylated low-density lipoprotein by galactose-specific receptors in rat liver.

PubMed

Bijsterbosch, M K; Van Berkel, T J

1990-08-15

The liver contains two types of galactose receptors, specific for Kupffer and parenchymal cells respectively. These receptors are only expressed in the liver, and therefore are attractive targets for the specific delivery of drugs. We provided low-density lipoprotein (LDL), a particle with a diameter of 23 nm in which a variety of drugs can be incorporated, with terminal galactose residues by lactosylation. Radioiodinated LDL, lactosylated to various extents (60-400 mol of lactose/ mol of LDL), was injected into rats. The plasma clearance and hepatic uptake of radioactivity were correlated with the extent of lactosylation. Highly lactosylated LDL (greater than 300 lactose/LDL) is completely cleared from the blood by liver within 10 min. Pre-injection with N-acetylgalactosamine blocks liver uptake, which indicates that the hepatic recognition sites are galactose-specific. The hepatic uptake occurs mainly by parenchymal and Kupffer cells. At a low degree of lactosylation, approx. 60 lactose/LDL, the specific uptake (ng/mg of cell protein) is 28 times higher in Kupffer cells than in parenchymal cells. However, because of their much larger mass, parenchymal cells are the main site of uptake. At high degrees of lactosylation (greater than 300 lactose/LDL), the specific uptake in Kupffer cells is 70-95 times that in parenchymal cells. Under these conditions, Kupffer cells are, despite their much smaller mass, the main site of uptake. Thus not only the size but also the surface density of galactose on lactosylated LDL is important for the balance of uptake between Kupffer and parenchymal cells. This knowledge should allow us to design particulate galactose-bearing carriers for the rapid transport of various drugs to either parenchymal cells or Kupffer cells.

CD14 is a key mediator of both lysophosphatidic acid and lipopolysaccharide induction of foam cell formation.

PubMed

An, Dong; Hao, Feng; Zhang, Fuqiang; Kong, Wei; Chun, Jerold; Xu, Xuemin; Cui, Mei-Zhen

2017-09-01

Macrophage uptake of oxidized low-density lipoprotein (oxLDL) plays an important role in foam cell formation and the pathogenesis of atherosclerosis. We report here that lysophosphatidic acid (LPA) enhances lipopolysaccharide (LPS)-induced oxLDL uptake in macrophages. Our data revealed that both LPA and LPS highly induce the CD14 expression at messenger RNA and protein levels in macrophages. The role of CD14, one component of the LPS receptor cluster, in LPA-induced biological functions has been unknown. We took several steps to examine the role of CD14 in LPA signaling pathways. Knockdown of CD14 expression nearly completely blocked LPA/LPS-induced oxLDL uptake in macrophages, demonstrating for the first time that CD14 is a key mediator responsible for both LPA- and LPS-induced oxLDL uptake/foam cell formation. To determine the molecular mechanism mediating CD14 function, we demonstrated that both LPA and LPS significantly induce the expression of scavenger receptor class A type I (SR-AI), which has been implicated in lipid uptake process, and depletion of CD14 levels blocked LPA/LPS-induced SR-AI expression. We further showed that the SR-AI-specific antibody, which quenches SR-AI function, blocked LPA- and LPS-induced foam cell formation. Thus, SR-AI is the downstream mediator of CD14 in regulating LPA-, LPS-, and LPA/LPS-induced foam cell formation. Taken together, our results provide the first experimental evidence that CD14 is a novel connecting molecule linking both LPA and LPS pathways and is a key mediator responsible for LPA/LPS-induced foam cell formation. The LPA/LPS-CD14-SR-AI nexus might be the new convergent pathway, contributing to the worsening of atherosclerosis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Developing Strategies to Block Beta-Catenin Action in Signaling and Cell Adhesion During Carcinogenesis

DTIC Science & Technology

2001-07-01

denatured digoxigenin-labeled antisense RNA , washed at7;dorsal tcalo. 1997; riesguaorEscof andorsal, closure 70’C once each with lx HYB, 2:1 HYB/PBT and 1...reelin receptors, perhaps as a heteromeric rons and their synaptic contacts7",, although neurexins complex: members of the LDL -receptor-related...Disheveled I Fat I Dachsous I sive mechanisms and cellular responses of different Flamingo/ Starry night I Reelin I LDL -receptor I mDab I I Fyn I DN

Inhibitory effect of Piper betel leaf extracts on copper-mediated LDL oxidation and oxLDL-induced lipid accumulation via inducing reverse cholesterol transport in macrophages.

PubMed

Ma, Gwo-Chin; Wu, Pei-Fang; Tseng, Hsien-Chun; Chyau, Charng-Cherng; Lu, Hsiu-Chin; Chou, Fen-Pi

2013-12-15

Piper betel leaf (PBL) has the biological capabilities of detoxification and can work as an anti-inflammatory agent and an anti-oxidant. In this study, we evaluated the anti-oxidative activity of the extract of Piper betel leaves (PBLs) on the basis of Cu(2+)-mediated oxidation, and its ability to prevent foam cell formation in a model for oxidised low density lipoprotein (oxLDL)-induced lipid accumulation in macrophages. Our data demonstrated that PBLs were able to inhibit LDL oxidation in vitro and are able to reduce the lipid accumulation in macrophages. We showed the underlying mechanisms to be the following: PBLs up-regulated the protein levels of the class A and class B scavenger receptors, the membrane lipid transporter ABCA1, and its upstream regulator Liver X receptor (LXR) in the macrophages exposed to oxLDL. The results suggested that PBLs activated the reverse cholesterol transport mechanism to enhance the metabolism of the oxLDL that could prevent both lipid accumulation and foam cell formation and further minimise the possible damage of vessels caused by the oxLDL. Copyright © 2013 Elsevier Ltd. All rights reserved.

Suppression of endothelial cell adhesion by XJP-1, a new phenolic compound derived from banana peel.

PubMed

Fu, Rong; Yan, Tianhua; Wang, Qiujuan; Guo, Qinglong; Yao, Hequan; Wu, Xiaoming; Li, Yang

2012-01-01

The adhesion of monocytes to activated vascular endothelial cells is a critical event in the initiation of atherosclerosis. Adhesion is mediated by oxidized low-density lipoprotein (ox-LDL) which up-regulates inflammatory markers on endothelial cells. Here we report that (±) 7, 8-dihydroxy-3-methyl-isochromanone-4 (XJP-1), an inhibitor of ox-LDL-induced adhesion of monocytes to endothelial cells blocks cellular functions which are associated with adhesion. We show that XJP-1 down-regulates ox-LDL-induced over-expression of adhesion molecules (ICAM-1 and VCAM-1) in a dose-dependent manner in human umbilical vein endothelial cells (HUVECs), attenuates ox-LDL-induced up-regulation of low-density lipoprotein receptor (LOX)-1, decreases generation of reactive oxygen species (ROS), blocks translocation of nuclear factor-kappa B (NF-κB) activity, and prevents activation of c-Jun N-terminal kinase (JNK)/p38 pathways in endothelial cells. These findings suggest that XJP-1 may attenuate ox-LDL-induced endothelial adhesion of monocytes by blocking expression of adhesion molecules through suppressing ROS/NF-κB, JNK and p38 pathways. Copyright © 2012 Elsevier Inc. All rights reserved.

Antihyperlipidemic therapies targeting PCSK9.

PubMed

Weinreich, Michael; Frishman, William H

2014-01-01

Hyperlipidemia is a major cause of cardiovascular disease despite the availability of first-line cholesterol-lowering agents such as statins. A new therapeutic approach to lowering low-density lipoprotein-cholesterol (LDL-C) acts by blocking LDL-receptor degradation by serum proprotein convertase subtilisin kexin 9 (PCSK9). Human monoclonal antibodies that target PCSK9 and its interaction with the LDL receptor are now in clinical trials (REGN727/SAR23653, AMG145, and RN316). These agents are administered by either subcutaneous or intravenous routes, and have been shown to have major LDL-C and apolipoprotein B effects when combined with statins. A phase III clinical trial program evaluating clinical endpoints is now in progress. Other PCSK9-targeted approaches are in early stages of investigation, including natural inhibitors of PCSK9, RNA interference, and antisense inhibitors.

LRP1 influences trafficking of N-type calcium channels via interaction with the auxiliary α2δ-1 subunit

PubMed Central

Kadurin, Ivan; Rothwell, Simon W.; Lana, Beatrice; Nieto-Rostro, Manuela; Dolphin, Annette C.

2017-01-01

Voltage-gated Ca2+ (CaV) channels consist of a pore-forming α1 subunit, which determines the main functional and pharmacological attributes of the channel. The CaV1 and CaV2 channels are associated with auxiliary β- and α2δ-subunits. The molecular mechanisms involved in α2δ subunit trafficking, and the effect of α2δ subunits on trafficking calcium channel complexes remain poorly understood. Here we show that α2δ-1 is a ligand for the Low Density Lipoprotein (LDL) Receptor-related Protein-1 (LRP1), a multifunctional receptor which mediates trafficking of cargoes. This interaction with LRP1 is direct, and is modulated by the LRP chaperone, Receptor-Associated Protein (RAP). LRP1 regulates α2δ binding to gabapentin, and influences calcium channel trafficking and function. Whereas LRP1 alone reduces α2δ-1 trafficking to the cell-surface, the LRP1/RAP combination enhances mature glycosylation, proteolytic processing and cell-surface expression of α2δ-1, and also increase plasma-membrane expression and function of CaV2.2 when co-expressed with α2δ-1. Furthermore RAP alone produced a small increase in cell-surface expression of CaV2.2, α2δ-1 and the associated calcium currents. It is likely to be interacting with an endogenous member of the LDL receptor family to have these effects. Our findings now provide a key insight and new tools to investigate the trafficking of calcium channel α2δ subunits. PMID:28256585

Inhibition of Macrophage CD36 Expression and Cellular Oxidized Low Density Lipoprotein (oxLDL) Accumulation by Tamoxifen: A PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR)γ-DEPENDENT MECHANISM.

PubMed

Yu, Miao; Jiang, Meixiu; Chen, Yuanli; Zhang, Shuang; Zhang, Wenwen; Yang, Xiaoxiao; Li, Xiaoju; Li, Yan; Duan, Shengzhong; Han, Jihong; Duan, Yajun

2016-08-12

Macrophage CD36 binds and internalizes oxidized low density lipoprotein (oxLDL) to facilitate foam cell formation. CD36 expression is activated by peroxisome proliferator-activated receptor γ (PPARγ). Tamoxifen, an anti-breast cancer medicine, has demonstrated pleiotropic functions including cardioprotection with unfully elucidated mechanisms. In this study, we determined that treatment of ApoE-deficient mice with tamoxifen reduced atherosclerosis, which was associated with decreased CD36 and PPARγ expression in lesion areas. At the cellular level, we observed that tamoxifen inhibited CD36 protein expression in human THP-1 monocytes, THP-1/PMA macrophages, and human blood monocyte-derived macrophages. Associated with decreased CD36 protein expression, tamoxifen reduced cellular oxLDL accumulation in a CD36-dependent manner. At the transcriptional level, tamoxifen decreased CD36 mRNA expression, promoter activity, and the binding of the PPARγ response element in CD36 promoter to PPARγ protein. Tamoxifen blocked ligand-induced PPARγ nuclear translocation and CD36 expression, but it increased PPARγ phosphorylation, which was due to that tamoxifen-activated ERK1/2. Furthermore, deficiency of PPARγ expression in macrophages abolished the inhibitory effect of tamoxifen on CD36 expression or cellular oxLDL accumulation both in vitro and in vivo Taken together, our study demonstrates that tamoxifen inhibits CD36 expression and cellular oxLDL accumulation by inactivating the PPARγ signaling pathway, and the inhibition of macrophage CD36 expression can be attributed to the anti-atherogenic properties of tamoxifen. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Mipomersen: evidence-based review of its potential in the treatment of homozygous and severe heterozygous familial hypercholesterolemia.

PubMed

Parhofer, Klaus G

2012-01-01

Familial hypercholesterolemia (FH) is an autosomal-dominant inherited disease with a prevalence of one in 500 (heterozygous) to one in 1,000,000 (homozygous). Mutations of the low-density lipoprotein (LDL) receptor gene, the apolipoprotein B100 gene, or the PCSK9 gene may be responsible for the disease. The resulting LDL hypercholesterolemia results in premature atherosclerosis as early as childhood (homozygous FH) or in adulthood (heterozygous FH). Current treatment modalities include lifestyle modification, combination drug therapy (statin-based), and apheresis. Mipomersen is an antisense oligonucleotide which inhibits apolipoprotein B production independent of LDL receptor function and thus works in homozygous FH, heterozygous FH, and other forms of hypercholesterolemia. Mipomersen is given 200 mg/week subcutaneously. Phase III studies indicate that the LDL cholesterol concentration can be reduced by 25%-47%, lipoprotein(a) levels by 20%-40%, and triglyceride concentrations by approximately 10%. In general, mipomersen has no effect on high-density lipoprotein cholesterol concentrations. Although there is considerable interindividual variability, the observed lipid effects are largely independent of age, gender, concomitant statin therapy, and underlying dyslipoproteinemia. The most common side effects are injection site reactions (70%-100%), flu-like symptoms (29%-46%), and elevated transaminases associated with an increased liver fat content (6%-15%). Mipomersen may be an interesting addon drug in patients with heterozygous or homozygous FH not reaching treatment goals, either because baseline values are very high or because high-dose statins are not tolerated.

Mipomersen: evidence-based review of its potential in the treatment of homozygous and severe heterozygous familial hypercholesterolemia

PubMed Central

Parhofer, Klaus G

2012-01-01

Familial hypercholesterolemia (FH) is an autosomal-dominant inherited disease with a prevalence of one in 500 (heterozygous) to one in 1,000,000 (homozygous). Mutations of the low-density lipoprotein (LDL) receptor gene, the apolipoprotein B100 gene, or the PCSK9 gene may be responsible for the disease. The resulting LDL hypercholesterolemia results in premature atherosclerosis as early as childhood (homozygous FH) or in adulthood (heterozygous FH). Current treatment modalities include lifestyle modification, combination drug therapy (statin-based), and apheresis. Mipomersen is an antisense oligonucleotide which inhibits apolipoprotein B production independent of LDL receptor function and thus works in homozygous FH, heterozygous FH, and other forms of hypercholesterolemia. Mipomersen is given 200 mg/week subcutaneously. Phase III studies indicate that the LDL cholesterol concentration can be reduced by 25%–47%, lipoprotein(a) levels by 20%–40%, and triglyceride concentrations by approximately 10%. In general, mipomersen has no effect on high-density lipoprotein cholesterol concentrations. Although there is considerable interindividual variability, the observed lipid effects are largely independent of age, gender, concomitant statin therapy, and underlying dyslipoproteinemia. The most common side effects are injection site reactions (70%–100%), flu-like symptoms (29%–46%), and elevated transaminases associated with an increased liver fat content (6%–15%). Mipomersen may be an interesting addon drug in patients with heterozygous or homozygous FH not reaching treatment goals, either because baseline values are very high or because high-dose statins are not tolerated. PMID:22701100

Familial Hypercholesterolaemia

PubMed Central

Marais, A David

2004-01-01

Familial hypercholesterolaemia (FH), defined as the heritable occurrence of severe hypercholesterolaemia with cholesterol deposits in tendons and premature heart disease, is caused by at least four genes in sterol and lipoprotein pathways and displays varying gene-dose effects. The genes are the low-density lipoprotein (LDL) receptor, apolipoprotein (apo) B, proprotein convertase subtilisin/kexin 9, and the autosomal recessive hypercholesterolaemia (ARH) adaptor protein. All of these disorders have in common defective clearance of LDL within a complex system of lipid and lipoprotein metabolism and regulation. Normal cellular cholesterol and lipoprotein metabolism is reviewed before describing the disorders, their metabolic derangements and their clinical effects. FH is classified as two simplified phenotypes of disease according to the severity of the metabolic derangement. The dominantly inherited heterozygous phenotype comprises defects in the LDL receptor, apoB100, and neural apoptosis regulatory cleavage protein. The homozygous phenotype is co-dominant in defects of the LDL receptor, and occurs also as the ARH of adapter protein mutations. Defective binding of apoB100 does not result in a significant gene dose effect, but enhances the severity of heterozygotes for LDL receptor mutations. The genetic diagnosis of FH has provided greater accuracy in definition and detection of disease and exposes information about migration of populations. All of these disorders pose a high risk of atherosclerosis, especially in the homozygous phenotype. Studies of influences on the phenotype and responses to treatment are also discussed in the context of the metabolic derangements. PMID:18516203

An exon 4 mutation identified in the majority of South African familial hypercholesterolaemics.

PubMed Central

Kotze, M J; Warnich, L; Langenhoven, E; du Plessis, L; Retief, A E

1990-01-01

The prevalence of familial hypercholesterolaemia (FH) is significantly higher in the Afrikaans speaking population (Afrikaners) of South Africa than reported in most other populations. A founder gene effect has been proposed to explain the high FH frequency, implying that the same low density lipoprotein (LDL) receptor gene defect is present in the majority of affected Afrikaners. By using DNA amplification and sequence determination, we have detected a point mutation in DNA from two Afrikaner FH homozygotes. A cytosine to guanine base substitution at nucleotide position 681 of the LDL receptor cDNA results in an amino acid change from aspartic acid to glutamic acid at residue 206 in the cysteine rich ligand binding domain of the LDL receptor. Since three previously mapped transport deficient alleles of the LDL receptor were also traced to cysteine rich repeats of the protein, these results suggest that the mutation is responsible for the receptor defective mutation predominantly found in Afrikaner FH homozygotes. The mutation gives rise to an additional DdeI restriction site in DNA of affected subjects and segregation of the mutation with the disease was confirmed in five large Afrikaner FH families. We predict that 65% of affected South African Afrikaners carry this particular base substitution. Amplification of genomic DNA, using the polymerase chain reaction method, and restriction enzyme analysis now permit accurate diagnosis of the mutation in subjects with FH. Images PMID:2352257

α- and β-d-Glucans from the edible mushroom Pleurotus albidus differentially regulate lipid-induced inflammation and foam cell formation in human macrophage-like THP-1 cells.

PubMed

Castro-Alves, Victor Costa; Nascimento, João Roberto Oliveira do

2018-05-01

Macrophages play an essential role in lipid metabolism; however, the excessive uptake of modified lipids and cholesterol crystals (CC) leads to the formation of pro-inflammatory lipid-laden macrophages called foam cells. Since the α-1,6- and β-1,3-d-glucans from the basidiome and the mycelium of the edible mushroom Pleurotus albidus have previously been shown to regulate macrophage function, these glucans were tested in macrophage-like THP-1 cells previously exposed to acetylated low-density lipoproteins (acLDL) or CC. The glucans inhibited lipid-induced inflammation, but only the β-1,3-d-glucan regulated both the NLRP3 inflammasome activation and the expression of genes involved on lipid efflux in acLDL- or CC-pretreated cells, thereby reducing foam cell formation. In contrast, the two α-1,6-glucans tested inhibited foam cell formation only in acLDL-pretreated cells and had no effect on the expression of the peroxisome proliferator-activated receptor gamma and liver X receptor alpha genes, suggesting that these glucans regulate lipid influx rather than lipid efflux. Thus, α- and β-d-glucans differentially regulate lipid-induced inflammation and foam cell formation in macrophage-like cells. Furthermore, results emphasize that P. albidus has potential to be used as a functional food or as a source for the extraction of biologically-active glucans. Copyright © 2018 Elsevier B.V. All rights reserved.

Site-specific O-glycosylation of members of the low-density lipoprotein receptor superfamily enhances ligand interactions.

PubMed

Wang, Shengjun; Mao, Yang; Narimatsu, Yoshiki; Ye, Zilu; Tian, Weihua; Goth, Christoffer K; Lira-Navarrete, Erandi; Pedersen, Nis B; Benito-Vicente, Asier; Martin, Cesar; Uribe, Kepa B; Hurtado-Guerrero, Ramon; Christoffersen, Christina; Seidah, Nabil G; Nielsen, Rikke; Christensen, Erik I; Hansen, Lars; Bennett, Eric P; Vakhrushev, Sergey Y; Schjoldager, Katrine T; Clausen, Henrik

2018-05-11

The low-density lipoprotein receptor (LDLR) and related receptors are important for the transport of diverse biomolecules across cell membranes and barriers. Their functions are especially relevant for cholesterol homeostasis and diseases, including neurodegenerative and kidney disorders. Members of the LDLR-related protein family share LDLR class A (LA) repeats providing binding properties for lipoproteins and other biomolecules. We previously demonstrated that short linker regions between these LA repeats contain conserved O -glycan sites. Moreover, we found that O -glycan modifications at these sites are selectively controlled by the GalNAc-transferase isoform, GalNAc-T11. However, the effects of GalNAc-T11-mediated O -glycosylation on LDLR and related receptor localization and function are unknown. Here, we characterized O -glycosylation of LDLR-related proteins and identified conserved O -glycosylation sites in the LA linker regions of VLDLR, LRP1, and LRP2 (Megalin) from both cell lines and rat organs. Using a panel of gene-edited isogenic cell line models, we demonstrate that GalNAc-T11-mediated LDLR and VLDLR O -glycosylation is not required for transport and cell-surface expression and stability of these receptors but markedly enhances LDL and VLDL binding and uptake. Direct ELISA-based binding assays with truncated LDLR constructs revealed that O -glycosylation increased affinity for LDL by ∼5-fold. The molecular basis for this observation is currently unknown, but these findings open up new avenues for exploring the roles of LDLR-related proteins in disease. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

Systematic Cell-Based Phenotyping of Missense Alleles Empowers Rare Variant Association Studies: A Case for LDLR and Myocardial Infarction

PubMed Central

Schuberth, Christian; Won, Hong-Hee; Blattmann, Peter; Joggerst-Thomalla, Brigitte; Theiss, Susanne; Asselta, Rosanna; Duga, Stefano; Merlini, Pier Angelica; Ardissino, Diego; Lander, Eric S.; Gabriel, Stacey; Rader, Daniel J.; Peloso, Gina M.; Kathiresan, Sekar; Runz, Heiko

2015-01-01

A fundamental challenge to contemporary genetics is to distinguish rare missense alleles that disrupt protein functions from the majority of alleles neutral on protein activities. High-throughput experimental tools to securely discriminate between disruptive and non-disruptive missense alleles are currently missing. Here we establish a scalable cell-based strategy to profile the biological effects and likely disease relevance of rare missense variants in vitro. We apply this strategy to systematically characterize missense alleles in the low-density lipoprotein receptor (LDLR) gene identified through exome sequencing of 3,235 individuals and exome-chip profiling of 39,186 individuals. Our strategy reliably identifies disruptive missense alleles, and disruptive-allele carriers have higher plasma LDL-cholesterol (LDL-C). Importantly, considering experimental data refined the risk of rare LDLR allele carriers from 4.5- to 25.3-fold for high LDL-C, and from 2.1- to 20-fold for early-onset myocardial infarction. Our study generates proof-of-concept that systematic functional variant profiling may empower rare variant-association studies by orders of magnitude. PMID:25647241

Lipid effects of peroxisome proliferator-activated receptor-δ agonist GW501516 in subjects with low high-density lipoprotein cholesterol: characteristics of metabolic syndrome.

PubMed

Olson, Eric J; Pearce, Gregory L; Jones, Nigel P; Sprecher, Dennis L

2012-09-01

Peroxisome proliferator-activated receptor-δ-induced upregulation in skeletal muscle fatty acid oxidation would predict the modulation of lipid/lipoproteins. GW501516 (2.5, 5.0, or 10.0 mg) or placebo was given for 12 weeks to patients (n=268) with high-density lipoprotein (HDL) cholesterol <1.16 mmol/L. Fasting lipids/apolipoproteins (apos), insulin, glucose, and free fatty acid were measured; changes from baseline were calculated and assessed. A second smaller exploratory study (n=37) in a similar population was conducted using a sequence of 5 and 10 mg dosing for the assessment of lipoprotein particle concentration. GW501516 demonstrated HDL cholesterol increases up to 16.9% (10 mg) and apoA-I increases up to 6.6%. Reductions were observed in low-density lipoprotein (LDL) cholesterol (-7.3%), triglycerides (-16.9%), apoB (-14.9%), and free fatty acids (-19.4%). The exploratory study showed significant reductions in the concentration of very LDL (-19%), intermediate-density lipoprotein (-52%), and LDL (-14%, predominantly a reduction in small particles), whereas the number of HDL particles increased (+10%; predominantly medium and large HDL). GW501516 produced significant changes in HDL cholesterol, LDL cholesterol, apoA1, and apoB. Fewer very LDL and larger LDL support a transition toward less atherogenic lipoprotein profiles. These data are consistent with peroxisome proliferator-activated receptor-δ being a potentially important target for providing cardiovascular protection in metabolic syndrome-like patients.

Overexpression of 15-lipoxygenase in the vascular endothelium is associated with increased thymic apoptosis in LDL receptor-deficient mice.

PubMed

Afek, A; Zurgil, N; Bar-Dayan, Y; Polak-Charcon, S; Goldberg, I; Deutsch, M; Kopolovich, J; Keren, G; Harats, D; George, J

2004-01-01

15-Lipoxygenase (15-LO) is a nonheme iron-containing enzyme that catalyzes the peroxidation of fatty acids. Herein, we studied the effect of 15-LO overexpression in the vascular endothelium on thymocyte apoptosis by evaluating thymuses from low-density lipoprotein receptor-deficient (LDL-RD) mice and LDL-RD/15-LO mice. Thymuses were evaluated by immunohistochemistry and by TUNEL whereas in vitro studies were carried out by employing freshly isolated thymocytes from the respective mice and evaluation of apoptosis by propidium iodide and annexin V cytometry. The apoptotic index in LDL-RD/15-LO mice was significantly higher than in the LDL-RD mice. In the thymic medulla the difference was smaller, although still significant. Freshly isolated thymus cells from LDL-RD/15-LO mice exhibited a higher rate of spontaneous cell death than controls. Incubation of thymus cells in the presence of the cell-permeable caspase-3 inhibitor DEVD-CMK resulted in a decrease in the frequency of apoptotic cells in LDL-RD/15-LO thymocytes, whereas no effect was evident in control thymocytes. The antioxidant N-acetylcysteine causes the increase in apoptosis in both groups. LDL-RD/15-LO mice exhibit increased thymocyte apoptosis both in vivo and in vitro. These findings may suggest a role for 15-LO in the natural selection of thymocytes.

Very low density lipoprotein receptor in Alzheimer disease.

PubMed

Helbecque, N; Amouyel, P

2000-08-15

The apolipoprotein (APO) E4 isoform is associated with an accelerated rate of Alzheimer disease (AD) expression in sporadic as well as late-onset familial forms of the disease but the precise mechanism is unknown. In an attempt to approach the possible mechanisms involved, APOE receptors have been studied. They all belong to the low density lipoprotein (LDL) receptor family and share the same structural motifs. Some of them are preferentially expressed in the brain such as the LDL receptor related protein, the apolipoprotein E receptor 2, and the very low density lipoprotein (VLDL) receptor. These receptors have been suspected to be involved in Alzheimer disease at various levels. Among them, the VLDL receptor was extensively explored. Although genetic studies conducted on a polymorphism in the promoter of the VLDL receptor in Japanese and Caucasian populations gave divergent results, this does not exclude a possible involvement of the VLDL receptor in AD. Copyright 2000 Wiley-Liss, Inc.

The ApoE receptors Vldlr and Apoer2 in central nervous system function and disease.

PubMed

Lane-Donovan, Courtney; Herz, Joachim

2017-06-01

The LDL receptor (LDLR) family has long been studied for its role in cholesterol transport and metabolism; however, the identification of ApoE4, an LDLR ligand, as a genetic risk factor for late-onset Alzheimer's disease has focused attention on the role this receptor family plays in the CNS. Surprisingly, it was discovered that two LDLR family members, ApoE receptor 2 (Apoer2) and VLDL receptor (Vldlr), play key roles in brain development and adult synaptic plasticity, primarily by mediating Reelin signaling. This review focuses on Apoer2 and Vldlr signaling in the CNS and its role in human disease. Copyright © 2017 by the American Society for Biochemistry and Molecular Biology, Inc.

Inhibition of low-density lipoprotein oxidation and up-regulation of low-density lipoprotein receptor in HepG2 cells by tropical plant extracts.

PubMed

Salleh, Mohd Nizar; Runnie, Irine; Roach, Paul D; Mohamed, Suhaila; Abeywardena, Mahinda Y

2002-06-19

Twelve edible plant extracts rich in polyphenols were screened for their potential to inhibit oxidation of low-density lipoprotein (LDL) in vitro and to modulate LDL receptor (LDLr) activity in cultured HepG2 cells. The antioxidant activity (inhibition of LDL oxidation) was determined by measuring the formation of conjugated dienes (lag time) and thiobarbituric acid reagent substances (TBARS). Betel leaf (94%), cashew shoot (63%), Japanese mint (52%), semambu leaf (50%), palm frond (41%), sweet potato shoot, chilli fruit, papaya shoot, roselle calyx, and maman showed significantly increased lag time (>55 min, P < 0.05) and inhibition of TBARS formation (P < 0.05) compared to control. LDLr was significantly up-regulated (P < 0.05) by Japanese mint (67%), semambu (51%), cashew (50%), and noni (49%). Except for noni and betel leaf, most plant extracts studied demonstrated a positive association between antioxidant activity and the ability to up-regulate LDL receptor. Findings suggest that reported protective actions of plant polyphenols on lipoprotein metabolism might be exerted at different biochemical mechanisms.

Low-density lipoprotein apheresis: an evidence-based analysis.

PubMed

2007-01-01

To assess the effectiveness and safety of low-density lipoprotein (LDL) apheresis performed with the heparin-induced extracorporeal LDL precipitation (HELP) system for the treatment of patients with refractory homozygous (HMZ) and heterozygous (HTZ) familial hypercholesterolemia (FH). BACKGROUND ON FAMILIAL HYPERCHOLESTEROLEMIA: Familial hypercholesterolemia is a genetic autosomal dominant disorder that is caused by several mutations in the LDL-receptor gene. The reduced number or absence of functional LDL receptors results in impaired hepatic clearance of circulating low-density lipoprotein cholesterol (LDL-C) particles, which results in extremely high levels of LDL-C in the bloodstream. Familial hypercholesterolemia is characterized by excess LDL-C deposits in tendons and arterial walls, early onset of atherosclerotic disease, and premature cardiac death. Familial hypercholesterolemia occurs in both HTZ and HMZ forms. Heterozygous FH is one of the most common monogenic metabolic disorders in the general population, occurring in approximately 1 in 500 individuals. Nevertheless, HTZ FH is largely undiagnosed and an accurate diagnosis occurs in only about 15% of affected patients in Canada. Thus, it is estimated that there are approximately 3,800 diagnosed and 21,680 undiagnosed cases of HTZ FH in Ontario. In HTZ FH patients, half of the LDL receptors do not work properly or are absent, resulting in plasma LDL-C levels 2- to 3-fold higher than normal (range 7-15mmol/L or 300-500mg/dL). Most HTZ FH patients are not diagnosed until middle age when either they or one of their siblings present with symptomatic coronary artery disease (CAD). Without lipid-lowering treatment, 50% of males die before the age of 50 and 25% of females die before the age of 60, from myocardial infarction or sudden death. In contrast to the HTZ form, HMZ FH is rare (occurring in 1 case per million persons) and more severe, with a 6- to 8-fold elevation in plasma LDL-C levels (range 15-25mmol/L or 500-1000mg/dL). Homozygous FH patients are typically diagnosed in infancy, usually due to the presence of cholesterol deposits in the skin and tendons. The main complication of HMZ FH is supravalvular aortic stenosis, which is caused by cholesterol deposits on the aortic valve and in the ascending aorta. The average life expectancy of affected individuals is 23 to 25 years. In Ontario, it is estimated that there are 13 to 15 cases of HMZ FH. An Ontario clinical expert confirmed that 9 HMZ FH patients have been identified to date. There are 2 accepted clinical diagnostic criterion for the diagnosis of FH: the Simon Broome FH Register criteria from the United Kingdom and the Dutch Lipid Network criteria from the Netherlands. The criterion supplement cholesterol levels with clinical history, physical signs and family history. DNA-based-mutation-screening methods permit a definitive diagnosis of HTZ FH to be made. However, given that there are over 1000 identified mutations in the LDL receptor gene and that the detection rates of current techniques are low, genetic testing becomes problematic in countries with high genetic heterogeneity, such as Canada. The primary aim of treatment in both HTZ and HMZ FH is to reduce plasma LDL-C levels in order to reduce the risk of developing atherosclerosis and CAD. The first line of treatment is dietary intervention, however it alone is rarely sufficient for the treatment of FH patients. Patients are frequently treated with lipid-lowering drugs such as resins, fibrates, niacin, statins and cholesterol absorption-inhibiting drugs (ezetimibe). Most HTZ FH patients require a combination of drugs to achieve or approach target cholesterol levels. A small number of HTZ FH patients are refractory to treatment or intolerant to lipid-lowering medication. According to clinical experts, the prevalence of refractory HTZ FH in Ontario is between 1 to 5%. Using the mean of 3%, it is estimated that there are approximately 765 refractory HTZ FH patients in Ontario, of which 115 are diagnosed and 650 are undiagnosed. Drug therapy is less effective in HMZ FH patients since the effects of the majority of cholesterol-lowering drugs are mediated by the upregulation of LDL receptors, which are often absent or function poorly in HMZ FH patients. Some HMZ FH patients may still benefit from drug therapy, however this rarely reduces LDL-C levels to targeted levels. EXISTING TECHNOLOGY: PLASMA EXCHANGE An option currently available in Ontario for FH patients who do not respond to standard diet and drug therapy is plasma exchange (PE). Patients are treated with this lifelong therapy on a weekly or biweekly basis with concomitant drug therapy. Plasma exchange is nonspecific and eliminates virtually all plasma proteins such as albumin, immunoglobulins, coagulation factors, fibrinolytic factors and HDL-C, in addition to acutely lowering LDL-C by about 50%. Blood is removed from the patient, plasma is isolated, discarded and replaced with a substitution fluid. The substitution fluid and the remaining cellular components of the blood are then returned to the patient. The major limitation of PE is its nonspecificity. The removal of HDL-C prevents successful vascular remodeling of the areas stenosed by atherosclerosis. In addition, there is an increased susceptibility to infections, and costs are incurred by the need for replacement fluid. Adverse events can be expected to occur in 12% of procedures. OTHER ALTERNATIVES: Surgical alternatives for FH patients include portocaval shunt, ileal bypass and liver transplantation. However, these are risky procedures and are associated with a high morbidity rate. Results with gene therapy are not convincing to date. LDL APHERESIS An alternative to PE is LDL apheresis. Unlike PE, LDL apheresis is a selective treatment that removes LDL-C and other atherogenic lipoproteins from the blood while minimally impacting other plasma components such as HDL-C, total serum protein, albumin and immunoglobulins. As with PE, FH patients require lifelong therapy with LDL apheresis on a weekly/biweekly basis with concomitant drug therapy. HEPARIN-INDUCED EXTRACORPOREAL LDL PRECIPITATION: Heparin-induced extracorporeal LDL precipitation (HELP) is one of the most widely used methods of LDL apheresis. It is a continuous closed-loop system that processes blood extracorporeally. It operates on the principle that at a low pH, LDL and lipoprotein (a) [Lp(a)] bind to heparin and fibrinogen to form a precipitate which is then removed by filtration. In general, the total duration of treatment is approximately 2 to 3 hours. Results from early trials indicate that LDL-C concentration is reduced by 65% to 70% immediately following treatment in both HMZ and HTZ FH and then rapidly begins to rise. Typically patients with HTZ FH are treated every 2 weeks while patients with HMZ FH require weekly therapy. Heparin-induced extracorporeal LDL precipitation also produces small transient decreases in HDL-C, however levels generally return to baseline within 2 days. After several months of therapy, long-term reductions in LDL-C and increases in HDL-C have been reported. In addition to having an impact on plasma cholesterol concentrations, HELP lowers plasma fibrinogen, a risk factor for atherosclerosis, and reduces concentrations of cellular adhesion molecules, which play a role in early atherogenesis. In comparison with PE, HELP LDL apheresis does not have major effects on essential plasma proteins and does not require replacement fluid, thus decreasing susceptibility to infections. One study noted that adverse events were documented in 2.9% of LDL apheresis treatments using the HELP system compared with 12% using PE. As per the manufacturer, patients must weigh at least 30kgs to be eligible for treatment with HELP. The H.E.L.P.® System (B.Braun Medizintechnologie GmbH, Germany) has been licensed by Health Canada since December 2000 as a Class 3 medical device (Licence # 26023) for performing LDL apheresis to acutely remove LDL from the plasma of 3 high-risk patient populations for whom diet has been ineffective and maximum drug therapy has either been ineffective or not tolerated. The 3 patient groups are as follows: Functional hypercholesterolemic homozygotes with LDL-C >500 mg/dL (>13mmol/L);Functional hypercholesterolemic heterozygotes with LDL-C >300 mg/dL (>7.8mmol/L);Functional hypercholesterolemic heterozygotes with LDL-C >200 mg/dL (>5.2mmol/L) and documented CADNo other LDL apheresis system is currently licensed in Canada. The Medical Advisory Secretariat systematically reviewed the literature to assess the effectiveness and safety of LDL apheresis performed with the HELP system for the treatment of patients with refractory HMZ and HTZ FH. A standard search methodology was used to retrieve international health technology assessments and English-language journal articles from selected databases. The GRADE approach was used to systematically and explicitly make judgments about the quality of evidence and strength of recommendations. The search identified 398 articles published from January 1, 1998 to May 30, 2007. Eight studies met the inclusion criteria. Five case series, 2 case series nested within comparative studies, and one retrospective review, were included in the analysis. A health technology assessment conducted by the Alberta Heritage Foundation for Medical Research, and a review by the United States Food and Drug Administration were also included. Large heterogeneity among the studies was observed. Studies varied in inclusion criteria, baseline patient characteristics and methodology. Overall, the mean acute relative decrease in LDL-C with HELP LDL apheresis ranged from 53 to 77%. The mean acute relative reductions ranged as follows: total cholesterol (TC) 47 to 64%, HDL-C +0. (ABSTRACT TRUNCATED)

Strategies for proprotein convertase subtilisin kexin 9 modulation: a perspective on recent patents.

PubMed

Abifadel, Marianne; Pakradouni, Jihane; Collin, Matthieu; Samson-Bouma, Marie-Elisabeth; Varret, Mathilde; Rabès, Jean-Pierre; Boileau, Catherine

2010-11-01

Proprotein convertase subtilisin kexin 9 (PCSK9) is a new actor discovered in 2003 that is implicated in autosomal dominant hypercholesterolemia, cholesterol homeostasis and coronary heart disease. It has been shown to degrade the low-density lipoprotein (LDL) receptor independently of its catalytic activity. Several pharmacological strategies to reduce PCSK9 are being thoroughly investigated. This article reviews all different strategies that are presently pursued to modulate the functional activity of PCSK9 which is a prime target for controlling LDL-cholesterol. It also provides a briefing of all the patents up to July 2010 from various organizations including pharmaceutical companies and academic institutions that have been submitted and/or approved. This review is addressed to researchers from academia and pharmaceutical companies who are engaged in PCSK9 research/cholesterol regulation and in the development of cholesterol lowering drugs. Readers will gain an up-to-date overview of the different strategies that have been investigated to reduce PCSK9 including antisense technology and specific antibodies. Clinical trials have been launched using RNA interference approaches to reduce PCSK9 expression or specific antibodies targeting and inhibiting PCSK9 interaction with the LDL receptor. They constitute very promising approaches to reducing cholesterol levels and coronary heart disease.

High susceptibility to fatty liver disease in two-pore channel 2-deficient mice.

PubMed

Grimm, Christian; Holdt, Lesca M; Chen, Cheng-Chang; Hassan, Sami; Müller, Christoph; Jörs, Simone; Cuny, Hartmut; Kissing, Sandra; Schröder, Bernd; Butz, Elisabeth; Northoff, Bernd; Castonguay, Jan; Luber, Christian A; Moser, Markus; Spahn, Saskia; Lüllmann-Rauch, Renate; Fendel, Christina; Klugbauer, Norbert; Griesbeck, Oliver; Haas, Albert; Mann, Matthias; Bracher, Franz; Teupser, Daniel; Saftig, Paul; Biel, Martin; Wahl-Schott, Christian

2014-08-21

Endolysosomal organelles play a key role in trafficking, breakdown and receptor-mediated recycling of different macromolecules such as low-density lipoprotein (LDL)-cholesterol, epithelial growth factor (EGF) or transferrin. Here we examine the role of two-pore channel (TPC) 2, an endolysosomal cation channel, in these processes. Embryonic mouse fibroblasts and hepatocytes lacking TPC2 display a profound impairment of LDL-cholesterol and EGF/EGF-receptor trafficking. Mechanistically, both defects can be attributed to a dysfunction of the endolysosomal degradation pathway most likely on the level of late endosome to lysosome fusion. Importantly, endolysosomal acidification or lysosomal enzyme function are normal in TPC2-deficient cells. TPC2-deficient mice are highly susceptible to hepatic cholesterol overload and liver damage consistent with non-alcoholic fatty liver hepatitis. These findings indicate reduced metabolic reserve of hepatic cholesterol handling. Our results suggest that TPC2 plays a crucial role in trafficking in the endolysosomal degradation pathway and, thus, is potentially involved in the homoeostatic control of many macromolecules and cell metabolites.

The effect of essential oils of dietary wormwood (Artemisia princeps), with and without added vitamin E, on oxidative stress and some genes involved in cholesterol metabolism.

PubMed

Chung, Mi Ja; Kang, Ah-Young; Park, Sung-Ok; Park, Kuen-Woo; Jun, Hee-Jin; Lee, Sung-Joon

2007-08-01

Wormwood (Artemisia princeps) due to the abundance of antioxidant in its essential oils (EO), has been used as a traditional drug and health food in Korea. Oxidative stress plays an important role in the etiology of atherosclerosis thus antioxidative chemicals improves hepatic lipid metabolism partly by reducing oxysterol formation. The antioxidant activity was assessed using two methods, human low-density lipoprotein (LDL) oxidation and the anti-DPPH free radical assays. It was found that the antioxidant activity of EO with vitamin E higher than EO alone. To study mechanisms accounting for the antiatherosclerotic properties of this wormwood EO, we examined the expression of key genes in cholesterol metabolism such as the LDL receptor, the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase and sterol regulatory element binding proteins. The induction was increased up to twofold at 0.05 mg/mL of EO treatment in HepG2 cells for 24h. When EO (0.2 mg/mL) was co-incubated with vitamin E, interestingly, the LDL receptor was dramatically induced by 5-6-folds. HMG-CoA reductase did not change. However, treatment with the higher concentration resulted in cytotoxicity. Our data suggest that wormwood EO with vitamin E may be anti-atherogenic due to their inhibition of LDL oxidation and upregulation of the LDL receptor.

Common Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Epitopes Mediate Multiple Routes for Internalization and Function

PubMed Central

DeVay, Rachel M.; Yamamoto, Lynn; Shelton, David L.; Liang, Hong

2015-01-01

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a soluble protein that directs membrane-bound receptors to lysosomes for degradation. In the most studied example of this, PCSK9 binding leads to the degradation of low density lipoprotein receptor (LDLR), significantly affecting circulating LDL-C levels. The mechanism mediating this degradation, however, is not completely understood. We show here that LDLR facilitates PCSK9 interactions with amyloid precursor like protein 2 (APLP2) at neutral pH leading to PCSK9 internalization, although direct binding between PCSK9 and LDLR is not required. Moreover, binding to APLP2 or LDLR is independently sufficient for PCSK9 endocytosis in hepatocytes, while LDL can compete with APLP2 for PCSK9 binding to indirectly mediate PCSK9 endocytosis. Finally, we show that APLP2 and LDLR are also required for the degradation of another PCSK9 target, APOER2, necessitating a general role for LDLR and APLP2 in PCSK9 function. Together, these findings provide evidence that PCSK9 has at least two endocytic epitopes that are utilized by a variety of internalization mechanisms and clarifies how PCSK9 may direct proteins to lysosomes. PMID:25905719

Increased LDL electronegativity in chronic kidney disease disrupts calcium homeostasis resulting in cardiac dysfunction.

PubMed

Chang, Kuan-Cheng; Lee, An-Sheng; Chen, Wei-Yu; Lin, Yen-Nien; Hsu, Jing-Fang; Chan, Hua-Chen; Chang, Chia-Ming; Chang, Shih-Sheng; Pan, Chia-Chi; Sawamura, Tatsuya; Chang, Chi-Tzong; Su, Ming-Jai; Chen, Chu-Huang

2015-07-01

Chronic kidney disease (CKD), an independent risk factor for cardiovascular disease, is associated with abnormal lipoprotein metabolism. We examined whether electronegative low-density lipoprotein (LDL) is mechanistically linked to cardiac dysfunction in patients with early CKD. We compared echocardiographic parameters between patients with stage 2 CKD (n = 88) and normal controls (n = 89) and found that impaired relaxation was more common in CKD patients. Reduction in estimated glomerular filtration rate was an independent predictor of left ventricular relaxation dysfunction. We then examined cardiac function in a rat model of early CKD induced by unilateral nephrectomy (UNx) by analyzing pressure-volume loop data. The time constant of isovolumic pressure decay was longer and the maximal velocity of pressure fall was slower in UNx rats than in controls. When we investigated the mechanisms underlying relaxation dysfunction, we found that LDL from CKD patients and UNx rats was more electronegative than LDL from their respective controls and that LDL from UNx rats induced intracellular calcium overload in H9c2 cardiomyocytes in vitro. Furthermore, chronic administration of electronegative LDL, which signals through lectin-like oxidized LDL receptor-1 (LOX-1), induced relaxation dysfunction in wild-type but not LOX-1(-/-) mice. In in vitro and in vivo experiments, impaired cardiac relaxation was associated with increased calcium transient resulting from nitric oxide (NO)-dependent nitrosylation of SERCA2a due to increases in inducible NO synthase expression and endothelial NO synthase uncoupling. In conclusion, LDL becomes more electronegative in early CKD. This change disrupts SERCA2a-regulated calcium homeostasis, which may be the mechanism underlying cardiorenal syndrome. Copyright © 2015 Elsevier Ltd. All rights reserved.

Phenotype diversity among patients with homozygous familial hypercholesterolemia: A cohort study.

PubMed

Raal, Frederick J; Sjouke, Barbara; Hovingh, G Kees; Isaac, Barton F

2016-05-01

Homozygous familial hypercholesterolaemia (HoFH) is a rare disorder usually caused by mutations in both alleles of the low-density lipoprotein receptor gene (LDLR). Premature death, often before the age of 20 years, was a common fate for patients with HoFH prior to the introduction of statins in 1990 and the use of lipoprotein apheresis. Consequently, HoFH has been widely considered a condition exclusive to a population comprising very young patients with extremely high LDL cholesterol (LDL-C) levels. However, recent epidemiologic and genetic studies have shown that the HoFH patient population is far more diverse in terms of age, LDL-C levels, and genetic aetiology than previously realised. We set out to investigate the clinical characteristics regarding age and LDL-C ranges of patients with HoFH. We analysed the data from 3 recent international studies comprising a total of 167 HoFH patients. The age of the patients ranged from 1 to 75 years, and a large proportion of the patients, both treated and untreated, exhibited LDL-C levels well below the recommended clinical diagnostic threshold for HoFH. LDL-C levels ranged from 4.4 mmol/L to 27.2 mmol/L (170-1052 mg/dL) for untreated patients, and from 2.6 mmol/L to 20.3 mmol/L (101-785 mg/dL) for treated patients. When patients were stratified according to LDLR functionality, a similarly wide range of age and LDL-C values was observed regardless of LDLR mutation status. These results demonstrate that HoFH is not restricted to very young patients or those with extremely high LDL-C levels. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Role of six single nucleotide polymorphisms, risk factors in coronary disease, in OLR1 alternative splicing

PubMed Central

Tejedor, J. Ramón; Tilgner, Hagen; Iannone, Camilla; Guigó, Roderic; Valcárcel, Juan

2015-01-01

The OLR1 gene encodes the oxidized low-density lipoprotein receptor (LOX-1), which is responsible for the cellular uptake of oxidized LDL (Ox-LDL), foam cell formation in atheroma plaques and atherosclerotic plaque rupture. Alternative splicing (AS) of OLR1 exon 5 generates two protein isoforms with antagonistic functions in Ox-LDL uptake. Previous work identified six single nucleotide polymorphisms (SNPs) in linkage disequilibrium that influence the inclusion levels of OLR1 exon 5 and correlate with the risk of cardiovascular disease. Here we use minigenes to recapitulate the effects of two allelic series (Low- and High-Risk) on OLR1 AS and identify one SNP in intron 4 (rs3736234) as the main contributor to the differences in exon 5 inclusion, while the other SNPs in the allelic series attenuate the drastic effects of this key SNP. Bioinformatic, proteomic, mutational and functional high-throughput analyses allowed us to define regulatory sequence motifs and identify SR protein family members (SRSF1, SRSF2) and HMGA1 as factors involved in the regulation of OLR1 AS. Our results suggest that antagonism between SRSF1 and SRSF2/HMGA1, and differential recognition of their regulatory motifs depending on the identity of the rs3736234 polymorphism, influence OLR1 exon 5 inclusion and the efficiency of Ox-LDL uptake, with potential implications for atherosclerosis and coronary disease. PMID:25904137

N-acetylcysteine inhibits in vivo oxidation of native low-density lipoprotein

PubMed Central

Cui, Yuqi; Narasimhulu, Chandrakala A.; Liu, Lingjuan; Zhang, Qingbin; Liu, Patrick Z.; Li, Xin; Xiao, Yuan; Zhang, Jia; Hao, Hong; Xie, Xiaoyun; He, Guanglong; Cui, Lianqun; Parthasarathy, Sampath; Liu, Zhenguo

2015-01-01

Low-density lipoprotein (LDL) is non-atherogenic, while oxidized LDL (ox-LDL) is critical to atherosclerosis. N-acetylcysteine (NAC) has anti-atherosclerotic effect with largely unknown mechanisms. The present study aimed to determine if NAC could attenuate in vivo LDL oxidation and inhibit atherosclerosis. A single dose of human native LDL was injected intravenously into male C57BL/6 mice with and without NAC treatment. Serum human ox-LDL was detected 30 min after injection, reached the peak in 3 hours, and became undetectable in 12 hours. NAC treatment significantly reduced serum ox-LDL level without detectable serum ox-LDL 6 hours after LDL injection. No difference in ox-LDL clearance was observed in NAC-treated animals. NAC treatment also significantly decreased serum ox-LDL level in patients with coronary artery diseases and hyperlipidemia without effect on LDL level. Intracellular and extracellular reactive oxidative species (ROS) production was significantly increased in the animals treated with native LDL, or ox-LDL and in hyperlipidemic LDL receptor knockout (LDLR−/−) mice that was effectively prevented with NAC treatment. NAC also significantly reduced atherosclerotic plaque formation in hyperlipidemic LDLR−/− mice. NAC attenuated in vivo oxidation of native LDL and ROS formation from ox-LDL associated with decreased atherosclerotic plaque formation in hyperlipidemia. PMID:26536834

C1q/TNF-Related Protein-9 Ameliorates Ox-LDL-Induced Endothelial Dysfunction via PGC-1α/AMPK-Mediated Antioxidant Enzyme Induction

PubMed Central

Sun, Haijian; Zhu, Xuexue; Zhou, Yuetao; Cai, Weiwei; Qiu, Liying

2017-01-01

Oxidized low-density lipoprotein (ox-LDL) accumulation is one of the critical determinants in endothelial dysfunction in many cardiovascular diseases such as atherosclerosis. C1q/TNF-related protein 9 (CTRP9) is identified to be an adipocytokine with cardioprotective properties. However, the potential roles of CTRP9 in endothelial function remain largely elusive. In the present study, the effects of CTRP9 on the proliferation, apoptosis, migration, angiogenesis, nitric oxide (NO) production and oxidative stress in human umbilical vein endothelial cells (HUVECs) exposed to ox-LDL were investigated. We observed that treatment with ox-LDL inhibited the proliferation, migration, angiogenesis and the generation of NO, while stimulated the apoptosis and reactive oxygen species (ROS) production in HUVECs. Incubation of HUVECs with CTRP9 rescued ox-LDL-induced endothelial injury. CTRP9 treatment reversed ox-LDL-evoked decreases in antioxidant enzymes including heme oxygenase-1 (HO-1), nicotinamide adenine dinucleotide phosphate (NAD(P)H) dehydrogenase quinone 1, and glutamate-cysteine ligase (GCL), as well as endothelial nitric oxide synthase (eNOS). Furthermore, CTRP9 induced activation of peroxisome proliferator-activated receptor γ co-activator 1α (PGC1-α) and phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). Of interest, AMPK inhibition or PGC1-α silencing abolished CTRP9-mediated antioxidant enzymes levels, eNOS expressions, and endothelial protective effects. Collectively, we provided the first evidence that CTRP9 attenuated ox-LDL-induced endothelial injury by antioxidant enzyme inductions dependent on PGC-1α/AMPK activation. PMID:28587104

Streptococcal Serum Opacity Factor Increases Hepatocyte Uptake of Human Plasma High Density Lipoprotein-Cholesterol1

PubMed Central

Gillard, Baiba K.; Rosales, Corina; Pillai, Biju K.; Lin, Hu Yu; Courtney, Harry S.; Pownall, Henry J.

2010-01-01

Serum opacity factor (SOF), a virulence determinant of Streptococcus pyogenes, converts plasma high density lipoproteins (HDL) to three distinct species: lipid-free apolipoprotein (apo) A-I, neo HDL, a small discoidal HDL-like particle, and a large cholesteryl ester-rich microemulsion (CERM), that contains the cholesterol esters (CE) of up to ~400,000 HDL particles and apo E as its major protein. Similar SOF reaction products are obtained with HDL, total plasma lipoproteins and whole plasma. We hypothesized that hepatic uptake of CERM-CE via multiple apo E dependent receptors would be faster than that of HDL-CE. We tested our hypothesis using human hepatoma cells and lipoprotein receptor-specific Chinese hamster ovary (CHO) cells. [3H]CE uptake by HepG2 and Huh7 cells from HDL after SOF treatment, which transfers >90% of HDL-CE to CERM, was respectively 2.4 and 4.5 times faster than from control HDL. CERM-[3H]CE uptake was inhibited by LDL and HDL, suggestive of uptake by both the LDL receptor (LDL-R) and scavenger receptor class B type I (SR-BI). Studies in CHO cells specifically expressing LDL-R and SR-BI confirmed CERM-[3H]CE uptake by both receptors. RAP and heparin inhibit CERM-[3H]CE but not HDL-[3H]CE uptake thereby implicating LRP-1 and cell surface proteoglycans in this process. These data demonstrate that SOF treatment of HDL increases CE uptake via multiple hepatic apo E receptors. In so doing, SOF might increase hepatic disposal of plasma cholesterol in a way that is therapeutically useful. PMID:20879789

Two novel partial deletions of LDL-receptor gene in Italian patients with familial hypercholesterolemia (FH Siracusa and FH Reggio Emilia).

PubMed

Garuti, R; Lelli, N; Barozzini, M; Tiozzo, R; Ghisellini, M; Simone, M L; Li Volti, S; Garozzo, R; Mollica, F; Vergoni, W; Bertolini, S; Calandra, S

1996-03-01

In the present study we report two novel partial deletions of the LDL-R gene. The first (FH Siracusa), found in an FH-heterozygote, consists of a 20 kb deletion spanning from the 5' flanking region to the intron 2 of the LDL-receptor gene. The elimination of the promoter and the first two exons prevents the transcription of the deleted allele, as shown by Northern blot analysis of LDL-R mRNA isolated from the proband's fibroblasts. The second deletion (FH Reggio Emilia), which eliminates 11 nucleotides of exon 10, was also found in an FH heterozygote. The characterization of this deletion was made possible by a combination of techniques such as single strand conformation polymorphism (SSCP) analysis, direct sequence of exon 10 and cloning of the normal and deleted exon 10 from the proband's DNA. The 11 nt deletion occurs in a region of exon 10 which contains three triplets (CTG) and two four-nucleotides (CTGG) direct repeats. This structural feature might render this region more susceptible to a slipped mispairing during DNA duplication. Since this deletion causes a shift of the BamHI site at the 5' end of exon 10, a method has been devised for its rapid screening which is based on the PCR amplification of exon 10 followed by BamHI digestion. FH Reggio Emilia deletion produces a shift in the reading frame downstream from Lys458, leading to a sequence of 51 novel amino acids before the occurrence of a premature stop codon (truncated receptor). However, since RT-PCR failed to demonstrate the presence of the mutant LDL-R mRNA in proband fibroblasts, it is likely that the amount of truncated receptor produced in these cells is negligible.

Ocimum basilicum ethanolic extract decreases cholesterol synthesis and lipid accumulation in human macrophages.

PubMed

Bravo, Elena; Amrani, Souliman; Aziz, Mohammed; Harnafi, Hicham; Napolitano, Mariarosaria

2008-12-01

Macrophage lipid accumulation induced by low density lipoproteins (LDL) plays a pivotal role in atherosclerotic plaque development. Previous work showed that Ocimum basilicum extract, used as hypocholesterolemic agent by traditional medicine in Morocco, has hypolipidemic activity in rat acute hyperlipimidemia. This study investigated the effects of ethanolic extract of O. basilicum on lipid accumulation in human macrophages. As modification of LDL increase atherogenicity of the particles we evaluated the effects of the extract on LDL oxidation. The extract caused a dose-related increase of LDL-resistance to Cu(2+)-induced oxidation. Furthermore, at the dose of 60 microg/ml, significantly decreases the accumulation of macrophage lipid droplets induced by modified LDL evaluated as by red-oil staining. Cholesterol esterification and triacylglycerol synthesis in the cells were not affected. Macrophage treatment with 60 microg/ml, but not 20 microg/ml, of the extract reduced newly synthesized unesterified cholesterol by about 60% and decreased scavenger receptors activity by about 20-30%, evaluated by the internalization of cholesterol carried by [(3)H]CE-aggregated-LDL. The results suggest that O. basilicum ethanolic extract has the capability to reduce foam cell formation through the reduction of cholesterol synthesis and the modulation of the activity of surface scavenger receptors.

The cannabinoid WIN55,212-2 protects against oxidized LDL-induced inflammatory response in murine macrophages[S

PubMed Central

Hao, Ming-xiu; Jiang, Li-sheng; Fang, Ning-yuan; Pu, Jun; Hu, Liu-hua; Shen, Ling-Hong; Song, Wei; He, Ben

2010-01-01

The endocannabinoid system has recently been attracted interest for its anti-inflammatory and anti-oxidative properties. In this study, we investigated the role of the endocannabinoid system in regulating the oxidized low-density lipoprotein (oxLDL)-induced inflammatory response in macrophages. RAW264.7 mouse macrophages and peritoneal macrophages isolated from Sprague-Dawley (SD) rats were exposed to oxLDL with or without the synthetic cannabinoid WIN55,212-2. To assess the inflammatory response, reactive oxygen species (ROS) and tumor necrosis factor alpha (TNF- α) levels were determined, and activation of the mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-kappa B signaling pathways were assessed. We observed that: i) oxLDL strongly induced ROS generation and TNF- α secretion in murine macrophages; ii) oxLDL-induced TNF- α and ROS levels could be lowered considerably by WIN55,212-2 via inhibition of MAPK (ERK1/2) signaling and NF-kappa B activity; and iii) the effects of WIN55212-2 were attenuated by the selective CB2 receptor antagonist AM630. These results demonstrate the involvement of the endocannabinoid system in regulating the oxLDL-induced inflammatory response in macrophages, and indicate that the CB2 receptor may offer a novel pharmaceutical target for treating atherosclerosis. PMID:20305287

FH Tulsa-1 and -2: Two unique alleles for familial hypercholesterolemia presenting in an affected two-year-old African-American male

DOE Office of Scientific and Technical Information (OSTI.GOV)

Blackett, P.R.; Altmiller, D.H.; Jelley, D.

1995-11-20

A two-year-old African American boy presented with cutaneous xanthomata and extreme hypercholesterolemia. Subsequent studies revealed that the LDL-cholesterol was 1,001 mg/dl and apoB 507 mg/dl. LDL-receptor activity was almost undetectable, which is compatible with the finding of two newly described defective alleles on exon 4 of the LDL-receptor gene coding for part of the ligand-binding domain. One allele contained a 21 base-pair insertion from codon 200 to 207 whereas the other had a point mutation at codon 207. The rarity of genes for FH reported in individuals of African ancestry is discussed. 16 refs., 2 figs., 2 tabs.

Design and Rationale of the LAPLACE-TIMI 57 Trial: A Phase II, Double-Blind, Placebo-Controlled Study of the Efficacy and Tolerability of a Monoclonal Antibody Inhibitor of PCSK9 in Subjects With Hypercholesterolemia on Background Statin Therapy

PubMed Central

Kohli, Payal; Desai, Nihar R.; Giugliano, Robert P.; Kim, Jae B.; Somaratne, Ransi; Huang, Fannie; Knusel, Beat; McDonald, Shannon; Abrahamsen, Timothy; Wasserman, Scott M.; Scott, Robert; Sabatine, Marc S.

2013-01-01

Lowering low-density lipoprotein cholesterol (LDL-C) is a cornerstone for the prevention of atherosclerotic heart disease, improving clinical outcomes and reducing vascular mortality in patients with hypercholesterolemia. The clinical benefits of LDL-C reduction appear to extend even to patients starting with LDL-C as low as 60–80 mg/dL prior to initiating therapy. Statins are the first-line agents for treating hypercholesterolemia and are effective in reducing LDL-C, but many patients are unable to achieve their optimal lipid targets despite intensive statin therapy. Therefore, there has been a strong impetus for the development of novel pharmacologic agents designed to lower LDL-C further in patients already on statin therapy. Genetic mutations resulting in altered cholesterol homeostasis provide valuable information regarding novel approaches for treating hypercholesterolemia. To that end, mutations in proprotein convertase subtilisin/kexin type 9 (PCSK9) were linked to altered levels of LDL-C, illustrating this protein’s role in lipid metabolism. PCSK9 promotes degradation of the LDL receptor, preventing its transport back to the cell surface and thereby increasing circulating LDL-C. Conversely, inhibition of PCSK9 can profoundly decrease circulating LDL-C, and thus is an attractive new target for LDL-C–lowering therapy. AMG 145 is a fully human monoclonal immunoglobulin G2 antibody that binds specifically to human PCSK9 and inhibits its interaction with the low-density lipoprotein receptor. In this manuscript, we describe the rationale and design of LDL-C Assessment with PCSK9 Monoclonal Antibody Inhibition Combined With Statin Therapy–Thrombolysis In Myocardial Infarction 57 (LAPLACE-TIMI 57; NCT01380730), a 12-week, randomized, double-blind, dose-ranging, placebo-controlled study designed to assess the safety and efficacy of AMG 145 when added to statin therapy in patients with hypercholesterolemia. PMID:22714699

Exendin-4 ameliorates oxidized-LDL-induced inhibition of macrophage migration in vitro via the NF-κB pathway

PubMed Central

Ma, Ge-fei; Chen, Song; Yin, Lei; Gao, Xiang-dong; Yao, Wen-bing

2014-01-01

Aim: To investigate the effects of the glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 on oxidized low-density lipoprotein (ox-LDL)-induced inhibition of macrophage migration and the mechanisms underlying the effects of exendin-4. Methods: Primary peritoneal macrophages were extracted from the peritoneal cavity of mice treated with 3% thioglycollate (2 mL, ip). Migration of the macrophages was examined using a cell migration assay. Macrophage migration-related factors including leptin-like ox-LDL receptor (LOX-1), cyclooxygenase 2 (COX-2), tumor necrosis factor (TNF)-α, interleukin-1 (IL-1)β, matrix metalloproteinase-2 (MMP-2), intercellular adhesion molecule (ICAM)-1 and macrophage migration inhibitory factor (MIF) were measured using semi-quantitative RT-PCR. Expression of MIF and ICAM-1 proteins was examined with ELISA. Gelatin zymography was used to evaluate the activity of MMP-9. Activation of the NF-κB pathway was determined by confocal laser scanning microscopy. Results: Treatment of the macrophages with ox-LDL (50 μg/mL) markedly suppressed the macrophage migration. Furthermore, ox-LDL treatment substantially increased the expression of the macrophage migration-related factors, the activity of MMP-9 and the translocation of the NF-κB p65 subunit. These effects of ox-LDL were significantly ameliorated by pretreatment with the specific NF-κB inhibitor ammonium pyrrolidine dithiocarbamate (100 μmol/L). These effects of ox-LDL were also significantly ameliorated by pretreatment with exendin-4 (25 and 50 nmol/L). Conclusion: Exendin-4 ameliorates the inhibition of ox-LDL on macrophage migration in vitro, via suppressing ox-LDL-induced expression of ICAM-1 and MIF, which is probably mediated by the NF-κB pathway. PMID:24335838

Exendin-4 ameliorates oxidized-LDL-induced inhibition of macrophage migration in vitro via the NF-κB pathway.

PubMed

Ma, Ge-fei; Chen, Song; Yin, Lei; Gao, Xiang-dong; Yao, Wen-bing

2014-02-01

To investigate the effects of the glucagon-like peptide-1 (GLP-1) receptor agonist exendin-4 on oxidized low-density lipoprotein (ox-LDL)-induced inhibition of macrophage migration and the mechanisms underlying the effects of exendin-4. Primary peritoneal macrophages were extracted from the peritoneal cavity of mice treated with 3% thioglycollate (2 mL, ip). Migration of the macrophages was examined using a cell migration assay. Macrophage migration-related factors including leptin-like ox-LDL receptor (LOX-1), cyclooxygenase 2 (COX-2), tumor necrosis factor (TNF)-α, interleukin-1 (IL-1)β, matrix metalloproteinase-2 (MMP-2), intercellular adhesion molecule (ICAM)-1 and macrophage migration inhibitory factor (MIF) were measured using semi-quantitative RT-PCR. Expression of MIF and ICAM-1 proteins was examined with ELISA. Gelatin zymography was used to evaluate the activity of MMP-9. Activation of the NF-κB pathway was determined by confocal laser scanning microscopy. Treatment of the macrophages with ox-LDL (50 μg/mL) markedly suppressed the macrophage migration. Furthermore, ox-LDL treatment substantially increased the expression of the macrophage migration-related factors, the activity of MMP-9 and the translocation of the NF-κB p65 subunit. These effects of ox-LDL were significantly ameliorated by pretreatment with the specific NF-κB inhibitor ammonium pyrrolidine dithiocarbamate (100 μmol/L). These effects of ox-LDL were also significantly ameliorated by pretreatment with exendin-4 (25 and 50 nmol/L). Exendin-4 ameliorates the inhibition of ox-LDL on macrophage migration in vitro, via suppressing ox-LDL-induced expression of ICAM-1 and MIF, which is probably mediated by the NF-κB pathway.

Oxidized low density lipoprotein increases RANKL level in human vascular cells. Involvement of oxidative stress

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazière, Cécile, E-mail: maziere.cecile@chu-amiens.fr; Salle, Valéry; INSERM U1088

Highlights: •Oxidized LDL enhances RANKL level in human smooth muscle cells. •The effect of OxLDL is mediated by the transcription factor NFAT. •UVA, H{sub 2}O{sub 2} and buthionine sulfoximine also increase RANKL level. •All these effects are observed in human fibroblasts and endothelial cells. -- Abstract: Receptor Activator of NFκB Ligand (RANKL) and its decoy receptor osteoprotegerin (OPG) have been shown to play a role not only in bone remodeling but also in inflammation, arterial calcification and atherosclerotic plaque rupture. In human smooth muscle cells, Cu{sup 2+}-oxidized LDL (CuLDL) 10–50 μg/ml increased reactive oxygen species (ROS) and RANKL level inmore » a dose-dependent manner, whereas OPG level was not affected. The lipid extract of CuLDL reproduced the effects of the whole particle. Vivit, an inhibitor of the transcription factor NFAT, reduced the CuLDL-induced increase in RANKL, whereas PKA and NFκB inhibitors were ineffective. LDL oxidized by myeloperoxidase (MPO-LDL), or other pro-oxidant conditions such as ultraviolet A (UVA) irradiation, incubation with H{sub 2}O{sub 2} or with buthionine sulfoximine (BSO), an inhibitor of glutathione synthesis{sub ,} also induced an oxidative stress and enhanced RANKL level. The increase in RANKL in pro-oxidant conditions was also observed in fibroblasts and endothelial cells. Since RANKL is involved in myocardial inflammation, vascular calcification and plaque rupture, this study highlights a new mechanism whereby OxLDL might, by generation of an oxidative stress, exert a deleterious effect on different cell types of the arterial wall.« less

Pioglitazone inhibits LOX-1 expression in human coronary artery endothelial cells by reducing intracellular superoxide radical generation.

PubMed

Mehta, Jawahar L; Hu, Bo; Chen, Jiawei; Li, Dayuan

2003-12-01

LOX-1, a novel lectin-like receptor for oxidized LDL (ox-LDL), is expressed in response to ox-LDL, angiotensin II (Ang II), tumor necrosis factor (TNF)-alpha, and other stress stimuli. It is highly expressed in atherosclerotic tissues. Peroxisome proliferator-activated receptor (PPAR)-gamma ligands, such as pioglitazone, exert antiatherosclerotic effects. This study examined the regulation of LOX-1 expression in human coronary artery endothelial cells (HCAECs) by pioglitazone. Fourth generation HCAECs were treated with ox-LDL, Ang II, or TNF-alpha with or without pioglitazone pretreatment. All 3 stimuli upregulated LOX-1 expression (mRNA and protein). Pioglitazone, in a concentration-dependent manner, reduced LOX-1 expression (P<0.01 versus ox-LDL, Ang II, or TNF-alpha alone). Ox-LDL, Ang II, and TNF-alpha each enhanced intracellular superoxide radical generation, and pioglitazone pretreatment reduced superoxide generation (P<0.01 versus ox-LDL, Ang II, or TNF-alpha). Furthermore, all 3 stimuli upregulated the expression of the transcription factors nuclear factor-kappaB and activator protein-1 (determined by electrophoretic mobility shift assay), and pioglitazone pretreatment reduced this expression (P<0.01 versus ox-LDL, Ang II, or TNF-alpha). To determine the biological significance of pioglitazone-mediated downregulation of LOX-1, we studied monocyte adhesion to ox-LDL-treated HCAECs. Pioglitazone reduced the adhesion of monocytes to activated HCAECs in a fashion similar to that produced by antisense to LOX-1 mRNA. These observations suggest that the PPAR-gamma ligand pioglitazone reduces intracellular superoxide radical generation and subsequently reduces the expression of transcription factors, expression of the LOX-1 gene, and monocyte adhesion to activated endothelium. The salutary effect of PPAR-gamma ligands in atherogenesis may involve the inhibition of LOX-1 and the adhesion of monocytes to endothelium.

The oxidized low-density lipoprotein receptor mediates vascular effects of inhaled vehicle emissions

EPA Science Inventory

Rationale: To determine vascular signaling pathways involved in air pollution (vehicular engine emission) exposure -induced exacerbation of atherosclerosis, associated with onset of clinical cardiovascular events. Objective: To elucidate the role of oxidized LDL (oxLDL) and its ...

PTEN Regulates Beta-Catenin in Androgen Signaling: Implication in Prostate Cancer Progression

DTIC Science & Technology

2006-03-01

interacts with a single transmembrane LDL receptor-related protein 5/6 (LRP5/6) [14,15]. A number of different secreted proteins, such as secreted...cells [30,33,47,48,51]. Reduction of cellular levels of b-catenin by antisense or shRNA constructs decreases the expression of the PSA gene, a downstream...Zeng, LDL receptor- related proteins 5 and 6 inWnt/beta-catenin signaling: arrows point the way, Development 131 (2004) 1663–1677. [15] J.C. Hsieh

Dan-Lou Prescription Inhibits Foam Cell Formation Induced by ox-LDL via the TLR4/NF-κB and PPARγ Signaling Pathways.

PubMed

Gao, Li-Na; Zhou, Xin; Lu, Yu-Ren; Li, Kefeng; Gao, Shan; Yu, Chun-Quan; Cui, Yuan-Lu

2018-01-01

Atherosclerosis is the major worldwide cause of mortality for patients with coronary heart disease. Many traditional Chinese medicine compound prescriptions for atherosclerosis treatment have been tried in patients. Dan-Lou prescription, which is improved from Gualou-Xiebai-Banxia decoction, has been used to treat chest discomfort (coronary atherosclerosis) for approximately 2,000 years in China. Although the anti-inflammatory activities of Dan-Lou prescription have been proposed previously, the mechanism remains to be explored. Based on the interaction between inflammation and atherosclerosis, we further investigated the effect of Dan-Lou prescription on macrophage-derived foam cell formation and disclosed the underlying mechanisms. In the oxidative low-density lipoprotein (ox-LDL) induced foam cells model using murine macrophage RAW 264.7 cells, the ethanol extract from Dan-Lou prescription (EEDL) reduced ox-LDL uptake and lipid deposition by inhibiting the protein and mRNA expression of Toll-like receptor (TLR)4 and scavenger receptor (SR)B1. After stimulation with ox-LDL, the metabolic profile of macrophages was also changed, while the intervention of the EEDL mainly regulated the metabolism of isovalerylcarnitine, arachidonic acid, cholesterol, aspartic acid, arginine, lysine, L-glutamine and phosphatidylethanolamine (36:3), which participated in the regulation of the inflammatory response, lipid accumulation and cell apoptosis. In total, 27 inflammation-related gene targets were screened, and the biological mechanisms, pathways and biological functions of the EEDL on macrophage-derived foam cells were systemically analyzed by Ingenuity Pathway Analysis system (IPA). After verification, we found that EEDL alleviated ox-LDL induced macrophage foam cell formation by antagonizing the mRNA and protein over-expression of PPARγ, blocking the phosphorylation of IKKα/β, IκBα and NF-κB p65 and maintaining the expression balance between Bax and Bcl-2. In conclusion, we provided evidences that Dan-Lou prescription effectively attenuated macrophage foam cell formation via the TLR4/NF-κB and PPARγ signaling pathways.

PCSK9: Regulation and Target for Drug Development for Dyslipidemia.

PubMed

Burke, Amy C; Dron, Jacqueline S; Hegele, Robert A; Huff, Murray W

2017-01-06

Proprotein convertase subtilisin/kexin type-9 (PCSK9) is a secreted zymogen expressed primarily in the liver. PCSK9 circulates in plasma, binds to cell surface low-density lipoprotein (LDL) receptors, is internalized, and then targets the receptors to lysosomal degradation. Studies of naturally occurring PCSK9 gene variants that caused extreme plasma LDL cholesterol (LDL-C) deviations and altered atherosclerosis risk unleashed a torrent of biological and pharmacological research. Rapid progress in understanding the physiological regulation of PCSK9 was soon translated into commercially available biological inhibitors of PCSK9 that reduced LDL-C levels and likely also cardiovascular outcomes. Here we review the swift evolution of PCSK9 from novel gene to drug target, to animal and human testing, and finally to outcome trials and clinical applications. In addition, we explore how the genetics-guided path to PCSK9 inhibitor development exemplifies a new paradigm in pharmacology. Finally, we consider some potential challenges as PCSK9 inhibition becomes established in the clinic.

The protective effect of bergamot oil extract on lecitine-like oxyLDL receptor-1 expression in balloon injury-related neointima formation.

PubMed

Mollace, Vincenzo; Ragusa, Salvatore; Sacco, Iolanda; Muscoli, Carolina; Sculco, Francesca; Visalli, Valeria; Palma, Ernesto; Muscoli, Saverio; Mondello, Luigi; Dugo, Paola; Rotiroti, Domenicantonio; Romeo, Francesco

2008-06-01

Lectin-like oxyLDL receptor-1 (LOX-1) has recently been suggested to be involved in smooth muscle cell (SMC) proliferation and neointima formation in injured blood vessels. This study evaluates the effect of the nonvolatile fraction (NVF), the antioxidant component of bergamot essential oil (BEO), on LOX-1 expression and free radical generation in a model of rat angioplasty. Common carotid arteries injured by balloon angioplasty were removed after 14 days for histopathological, biochemical, and immunohistochemical studies. Balloon injury led to a significant restenosis with SMC proliferation and neointima formation, accompanied by increased expression of LOX-1 receptor, malondialdehyde and superoxide formation, and nitrotyrosine staining. Pretreatment of rats with BEO-NVF reduced the neointima proliferation together with free radical formation and LOX-1 expression in a dose-dependent manner. These results suggest that natural antioxidants may be relevant in the treatment of vascular disorders in which proliferation of SMCs and oxyLDL-related endothelial cell dysfunction are involved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharpe, Laura J.; Brown, Andrew J.

As a key regulator of cholesterol homeostasis, sterol-regulatory element binding protein-2 (SREBP-2) up-regulates expression of genes involved in cholesterol synthesis (e.g., 3-hydroxy-3-methyl-glutaryl-coenzyme A (HMG-CoA) Reductase) and uptake (the low density lipoprotein (LDL)-receptor). Previously, we showed that Akt, a critical kinase in cell growth and proliferation, contributes to SREBP-2 activation. However, the specific Akt target involved is unknown. A potential candidate is the mammalian target of rapamycin, mTOR. Rapamycin can cause hyperlipidaemia clinically, and we hypothesised that this may be mediated via an effect of mTOR on SREBP-2. Herein, we found that SREBP-2 activation and HMG-CoA Reductase gene expression were unaffectedmore » by rapamycin treatment. However, LDL-receptor gene expression was decreased by rapamycin, suggesting that this may contribute to the hyperlipidaemia observed in rapamycin-treated patients. Rapamycin did not affect mRNA stability, so the decrease in LDL-receptor gene expression is likely to be occurring at the transcriptional level, although independently of SREBP-2.« less

Hematopoietic Stem/Progenitor Cell Proliferation and Differentiation Is Differentially Regulated by High-Density and Low-Density Lipoproteins in Mice

PubMed Central

Feng, Yingmei; Schouteden, Sarah; Geenens, Rachel; Van Duppen, Vik; Herijgers, Paul; Holvoet, Paul; Van Veldhoven, Paul P.; Verfaillie, Catherine M.

2012-01-01

Rationale Hematopoietic stem/progenitor cells (HSPC) are responsible for maintaining the blood system as a result of their self-renewal and multilineage differentiation capacity. Recently, studies have suggested that HDL cholesterol may inhibit and impaired cholesterol efflux may increase HSPC proliferation and differentiation. Objectives We hypothesized that LDL may enhance HSPC proliferation and differentiation while HDL might have the opposing effect which might influence the size of the pool of inflammatory cells. Methods and Results HSPC number and function were studied in hypercholesterolemic LDL receptor knockout (LDLr−/−) mice on high fat diet. Hypercholesterolemia was associated with increased frequency of HSPC, monocytes and granulocytes in the peripheral blood (PB). In addition, an increased proportion of BM HSPC was in G2M of the cell cycle, and the percentage of HSPC and granulocyte-macrophage progenitors (GMP) increased in BM of LDLr−/− mice. When BM Lin-Sca-1+cKit+ (i.e. “LSK”) cells were cultured in the presence of LDL in vitro we also found enhanced differentiation towards monocytes and granulocytes. Furthermore, LDL promoted lineage negative (Lin−) cells motility. The modulation by LDL on HSPC differentiation into granulocytes and motility was inhibited by inhibiting ERK phosphorylation. By contrast, when mice were infused with human apoA-I (the major apolipoprotein of HDL) or reconstituted HDL (rHDL), the frequency and proliferation of HSPC was reduced in BM in vivo. HDL also reversed the LDL-induced monocyte and granulocyte differentiation in vitro. Conclusion Our data suggest that LDL and HDL have opposing effects on HSPC proliferation and differentiation. It will be of interest to determine if breakdown of HSPC homeostasis by hypercholesterolemia contributes to inflammation and atherosclerosis progression. PMID:23144813

Sphingosine 1-phosphate, present in serum-derived lipoproteins, activates matriptase.

PubMed

Benaud, Christelle; Oberst, Michael; Hobson, John P; Spiegel, Sarah; Dickson, Robert B; Lin, Chen-Yong

2002-03-22

We describe here a novel biological function of sphingosine 1-phosphate (S1P): the activation of a serine protease, matriptase. Matriptase is a type II integral membrane serine protease, expressed on the surface of a variety of epithelial cells; it may play an important role in tissue remodeling. We have previously reported that the activation of matriptase is regulated by serum. We have now identified the bioactive component from serum. First, the activity was observed to co-purify with lipoproteins by conventional liquid chromatography and immunoaffinity chromatography. The ability of lipoproteins to induce the activation of matriptase was further confirmed with commercial preparations of low density lipoprotein (LDL) and very low density lipoprotein (VLDL). Next, we observed that the bioactive component of LDL is associated with the phospholipid components of LDL. Fractionation of lipid components of LDL by thin layer chromatography (TLC) revealed that the bioactive component of LDL comigrates with S1P. Nanomolar concentrations of commercially obtained S1P were then observed to induce the rapid activation of matriptase on the surfaces of nontransformed human mammary epithelial cells. Other structurally related sphingolipids, including dihydro-S1P, ceramide 1-phosphates, and sphingosine phosphocholine as well as lysophosphatidic acid, can also induce the activation of matriptase, but at significantly higher concentrations than S1P. Furthermore, S1P-dependent matriptase activation is dependent on Ca(2+) but not via G(i) protein-coupled receptors. Our results demonstrate that bioactive phospholipids can function as nonprotein activators of a cell surface protease, suggesting a possible mechanistic link between S1P and normal and possibly pathologic tissue remodeling.

Ginkgolide B Reduces LOX-1 Expression by Inhibiting Akt Phosphorylation and Increasing Sirt1 Expression in Oxidized LDL-Stimulated Human Umbilical Vein Endothelial Cells

PubMed Central

Chen, Beidong; Li, Xingguang; Qi, Ruomei

2013-01-01

Oxidized low-density lipoprotein (ox-LDL) is an important risk factor in the development of atherosclerosis. LOX-1, a lectin-like receptor for ox-LDL, is present primarily on endothelial cells and upregulated by ox-LDL, tumor necrosis factor a, shear stress, and cytokines in atherosclerosis. Recent studies demonstrated that ginkgolide B, a platelet-activating factor receptor antagonist, has antiinflammatory and antioxidant effects on endothelial and nerve cells. The present study investigated the effects of ginkgolide B on LOX-1 expression and the possible mechanism of action. Our results showed that ginkgolide B inhibited LOX-1 and intercellular cell adhesion molecule-1 (ICAM-1) expression in ox-LDL-stimulated endothelial cells through a mechanism associated with the attenuation of Akt activation. Similar data were obtained by silencing Akt and LY294002. We also evaluated Sirt1 and nuclear factor erythroid 2-related factor 2 (Nrf2) expression. These molecules play a protective role in endothelial cell injury. The results showed that ginkgolide B increased Sirt1 expression in ox-LDL-treated cells. The inhibitory effects of ginkgolide B on LOX-1 and ICAM-1 expression were reduced in Sirt1 siRNA-transfected cells. Nrf2 expression was increased in ox-LDL-treated cells, and ginkgolide B downregulated Nrf2 expression. These results suggest that ginkgolide B reduces Nrf2 expression by inhibiting LOX-1 expression, consequently reducing oxidative stress injury in ox-LDL-stimulated cells. Altogether, these results indicate that the protective effect of ginkgolide B on endothelial cells may be attributable to a decrease in LOX-1 expression and an increase in Sirt1 expression in ox-LDL-stimulated endothelial cells, the mechanism of which is linked to the inhibition of Akt activation. Ginkgolide B may be a multiple-target drug that exerts protective effects in ox-LDL-treated human umbilical vein endothelial cells. PMID:24069345

Thematic review series: patient-oriented research. What we have learned about VLDL and LDL metabolism from human kinetics studies.

PubMed

Parhofer, Klaus G; Barrett, P Hugh R

2006-08-01

Lipoprotein metabolism is the result of a complex network of many individual components. Abnormal lipoprotein concentrations can result from changes in the production, conversion, or catabolism of lipoprotein particles. Studies in hypolipoproteinemia and hyperlipoproteinemia have elucidated the processes that control VLDL secretion as well as VLDL and LDL catabolism. Here, we review the current knowledge regarding apolipoprotein B (apoB) metabolism, focusing on selected clinically relevant conditions. In hypobetalipoproteinemia attributable to truncations in apoB, the rate of secretion is closely linked to the length of apoB. On the other hand, in patients with the metabolic syndrome, it appears that substrate, in the form of free fatty acids, coupled to the state of insulin resistance can induce hypersecretion of VLDL-apoB. Studies in patients with familial hypercholesterolemia, familial defective apoB, and mutant forms of proprotein convertase subtilisin/kexin type 9 show that mutations in the LDL receptor, the ligand for the receptor, or an intracellular chaperone for the receptor are the most important determinants in regulating LDL catabolism. This review also demonstrates the variance of results within similar, or even the same, phenotypic conditions. This underscores the sensitivity of metabolic studies to methodological aspects and thus the importance of the inclusion of adequate controls in studies.

A randomized trial and novel SPR technique identifies altered lipoprotein-LDL receptor binding as a mechanism underlying elevated LDL-cholesterol in APOE4s

PubMed Central

Calabuig-Navarro, M. V.; Jackson, K. G.; Kemp, C. F.; Leake, D. S.; Walden, C. M.; Lovegrove, J. A.; Minihane, A. M.

2017-01-01

At a population level APOE4 carriers (~25% Caucasians) are at higher risk of cardiovascular diseases. The penetrance of genotype is however variable and influenced by dietary fat composition, with the APOE4 allele associated with greater LDL-cholesterol elevation in response to saturated fatty acids (SFA). The etiology of this greater responsiveness is unknown. Here a novel surface plasmon resonance technique (SPR) is developed and used, along with hepatocyte (with the liver being the main organ modulating lipoprotein metabolism and plasma lipid levels) uptake studies to establish the impact of dietary fatty acid composition on, lipoprotein-LDL receptor (LDLR) binding, and hepatocyte uptake, according to APOE genotype status. In men prospectively recruited according to APOE genotype (APOE3/3 common genotype, or APOE3/E4), triglyceride-rich lipoproteins (TRLs) were isolated at fasting and 4–6 h following test meals rich in SFA, unsaturated fat and SFA with fish oil. In APOE4s a greater LDLR binding affinity of postprandial TRL after SFA, and lower LDL binding and hepatocyte internalization, provide mechanisms for the greater LDL-cholesterol raising effect. The SPR technique developed may be used for the future study of the impact of genotype, and physiological and behavioral variables on lipoprotein metabolism. Trial registration number NCT01522482. PMID:28276521

Vinpocetine attenuates lipid accumulation and atherosclerosis formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cai, Yujun; Li, Jian-Dong; Yan, Chen, E-mail: Chen_Yan@urmc.rochester.edu

Highlights: •Vinpocetine attenuates hyperlipidemia-induced atherosclerosis in a mouse model. •Vinpocetine antagonizes ox-LDL uptake and accumulation in macrophages. •Vinpocetine blocks the induction of ox-LDL receptor LOX-1 in vitro and in vivo. -- Abstract: Atherosclerosis, the major cause of myocardial infarction and stroke, is a chronic arterial disease characterized by lipid deposition and inflammation in the vessel wall. Cholesterol, in low-density lipoprotein (LDL), plays a critical role in the pathogenesis of atherosclerosis. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. Recent study indicated that vinpocetine is a potent anti-inflammatorymore » agent. However, its role in the pathogenesis of atherosclerosis remains unexplored. In the present study, we show that vinpocetine significantly reduced atherosclerotic lesion formation in ApoE knockout mice fed with a high-fat diet. In cultured murine macrophage RAW264.7 cells, vinpocetine markedly attenuated oxidized LDL (ox-LDL) uptake and foam cell formation. Moreover, vinpocetine greatly blocked the induction of ox-LDL receptor 1 (LOX-1) in cultured macrophages as well as in the LOX-1 level in atherosclerotic lesions. Taken together, our data reveal a novel role of vinpocetine in reduction of pathogenesis of atherosclerosis, at least partially through suppressing LOX-1 signaling pathway. Given the excellent safety profile of vinpocetine, this study suggests vinpocetine may be a therapeutic candidate for treating atherosclerosis.« less

L-arginine prevents xanthoma development and inhibits atherosclerosis in LDL receptor knockout mice.

PubMed

Aji, W; Ravalli, S; Szabolcs, M; Jiang, X C; Sciacca, R R; Michler, R E; Cannon, P J

1997-01-21

The potential antiatherosclerotic actions of NO were investigated in four groups of mice (n = 10 per group) lacking functional LDL receptor genes, an animal model of familial hypercholesterolemia. Group 1 was fed a regular chow diet. Groups 2 through 4 were fed a 1.25% high-cholesterol diet. In addition, group 3 received supplemental L-arginine and group 4 received L-arginine and N omega-nitro-L-arginine (L-NA), an inhibitor of NO synthase (NOS). Animals were killed at 6 months; aortas were stained with oil red O for planimetry and with antibodies against constitutive and inducible NOSs. Plasma cholesterol was markedly increased in the animals receiving the high-cholesterol diet. Xanthomas appeared in all mice fed the high-cholesterol diet alone but not in those receiving L-arginine. Aortic atherosclerosis was present in all mice on the high-cholesterol diet. The mean atherosclerotic lesion area was reduced significantly (P < .01) in the cholesterol-fed mice given L-arginine compared with those receiving the high-cholesterol diet alone. The mean atherosclerotic lesion area was significantly larger (P < .01) in cholesterol-fed mice receiving L-arginine + L-NA than in those on the high-cholesterol diet alone. Within the atherosclerotic plaques, endothelial cells immunoreacted for endothelial cell NOS; macrophages, foam cells, and smooth muscle cells immunostained strongly for inducible NOS and nitrotyrosine residues. The data indicate that L-arginine prevents xanthoma formation and reduces atherosclerosis in LDL receptor knockout mice fed a high-cholesterol diet. The abrogation of the beneficial effects of L-arginine by L-NA suggests that the antiatherosclerotic actions of L-arginine are mediated by NOS. The data suggest that L-arginine may be beneficial in familial hypercholesterolemia.

Hematopoietic Sphingosine 1-Phosphate Lyase Deficiency Decreases Atherosclerotic Lesion Development in LDL-Receptor Deficient Mice

PubMed Central

Bot, Martine; Van Veldhoven, Paul P.; de Jager, Saskia C. A.; Johnson, Jason; Nijstad, Niels; Van Santbrink, Peter J.; Westra, Marijke M.; Van Der Hoeven, Gerd; Gijbels, Marion J.; Müller-Tidow, Carsten; Varga, Georg; Tietge, Uwe J. F.; Kuiper, Johan; Van Berkel, Theo J. C.; Nofer, Jerzy-Roch

2013-01-01

Aims Altered sphingosine 1-phosphate (S1P) homeostasis and signaling is implicated in various inflammatory diseases including atherosclerosis. As S1P levels are tightly controlled by S1P lyase, we investigated the impact of hematopoietic S1P lyase (Sgpl1−/−) deficiency on leukocyte subsets relevant to atherosclerosis. Methods and Results LDL receptor deficient mice that were transplanted with Sgpl1−/− bone marrow showed disrupted S1P gradients translating into lymphopenia and abrogated lymphocyte mitogenic and cytokine response as compared to controls. Remarkably however, Sgpl1−/− chimeras displayed mild monocytosis, due to impeded stromal retention and myelopoiesis, and plasma cytokine and macrophage expression patterns, that were largely compatible with classical macrophage activation. Collectively these two phenotypic features of Sgpl1 deficiency culminated in diminished atherogenic response. Conclusions Here we not only firmly establish the critical role of hematopoietic S1P lyase in controlling S1P levels and T cell trafficking in blood and lymphoid tissue, but also identify leukocyte Sgpl1 as critical factor in monocyte macrophage differentiation and function. Its, partly counterbalancing, pro- and anti-inflammatory activity spectrum imply that intervention in S1P lyase function in inflammatory disorders such as atherosclerosis should be considered with caution. PMID:23700419

Pleiotropic Effects of Thyroid Hormones: Learning from Hypothyroidism

PubMed Central

Franco, Martha; Chávez, Edmundo; Pérez-Méndez, Oscar

2011-01-01

Hypothyroidism induces several metabolic changes that allow understanding some physiopathological mechanisms. Under experimental hypothyroid conditions in rats, heart and kidney are protected against oxidative damage induced by ischemia reperfusion. An increased resistance to opening of the permeability transition pore seems to be at the basis of such protection. Moreover, glomerular filtration rate of hypothyroid kidney is low as a result of adenosine receptors-induced renal vasoconstriction. The vascular tone of aorta is also regulated by adenosine in hypothyroid conditions. In other context, thyroid hormones regulate lipoprotein metabolism. High plasma level of LDL cholesterol is a common feature in hypothyroidism, due to a low expression of the hepatic LDL receptor. In contrast, HDL-cholesterol plasma levels are variable in hypothyroidism; several proteins involved in HDL metabolism and structure are expressed at lower levels in experimental hypothyroidism. Based on the positive influence of thyroid hormones on lipoprotein metabolism, thyromimetic drugs are promising for the treatment of dyslipidemias. In summary, hypothyroid status has been useful to understand molecular mechanisms involved in ischemia reperfusion, regulation of vascular function and intravascular metabolism of lipoproteins. PMID:21760977

Biomimetics: reconstitution of low-density lipoprotein for targeted drug delivery and related theranostic applications.

PubMed

Zhu, Chunlei; Xia, Younan

2017-12-11

Low-density lipoprotein (LDL), one of the four major groups of lipoproteins for lipid transport in vivo, is emerging as an attractive carrier for the targeted delivery of theranostic agents. In contrast to the synthetic systems, LDL particles are intrinsically biocompatible and biodegradable, together with reduced immunogenicity and natural capabilities to target cancerous cells and to escape from the recognition and elimination by the reticuloendothelial system. Enticed by these attributes, a number of strategies have been developed for reconstituting LDL particles, including conjugation to the apolipoprotein, insertion into the phospholipid layer, and loading into the core. Here we present a tutorial review on the development of reconstituted LDL (rLDL) particles for theranostic applications. We start with a brief introduction to LDL and LDL receptor, as well as the advantages of using rLDL particles as a natural and versatile platform for the targeted delivery of theranostic agents. After a discussion of commonly used strategies for the reconstitution of LDL, we highlight the applications of rLDL particles in the staging of disease progression, treatment of lesioned tissues, and delivery of photosensitizers for photodynamic cancer therapy. We finish this review with a perspective on the remaining challenges and future directions.

Reduction of arteriosclerotic nanoplaque formation and size by n-3 fatty acids in patients after valvular defect operation.

PubMed

Koppe, Cordelia; Rodríguez, Miguel; Winkler, Karl; Pietzsch, Jens; Neumann, Konrad; Hiemann, Nicola E; Hetzer, Roland; Malmsten, Martin; Siegel, Günter

2009-08-01

Coating a silica surface with the isolated lipoprotein receptor heparan sulfate proteoglycan (HS-PG) from arterial endothelium and vascular matrices, we could observe the very earliest stages of arteriosclerotic plaque development by ellipsometric techniques in vitro (patent EP 0 946 876). This so-called nanoplaque formation is represented by the ternary aggregational complex of the HS-PG receptor, lipoprotein particles and calcium ions. The model was validated in several clinical studies on statins in cardiovascular high-risk patients applying their native blood lipoprotein fractions. In 7 patients who had undergone a valvular defect operation, the reduction of arteriosclerotic nanoplaque formation in normal Krebs solution amounted to 6.1 +/- 2.3% (p < 0.0156) and of nanoplaque size to 37.5 +/- 13.2% (p < 0.0312), respectively, after a 3-month therapy with n-3 fatty acids (3 ..3 g daily, Ameu 500 mg). Additionally, the quotient oxLDL/LDL was lowered by 6.8 +/- 2.1% (p < 0.0166), the MDA concentration remained unchanged and the lipoprotein(a) concentration decreased by 15.8 +/- 5.6% (p < 0.0469) in the patients' blood. The concentration of the nanoplaque promoting particles VLDL and total triglycerides was diminished by 34.1 +/- 11.6% (p < 0.0469) and 26.7 +/- 10.8% (p < 0.0156), respectively. Furthermore, the ratio of the strongly atherogenic small dense to the total LDL cholesterol (LDL5+LDL6)/LDLtot decreased by 9.9 +/- 3.0% (p < 0.0174). A combinatorial regression analysis revealed a basis for a mechanistic explanation of nanoplaque reduction under n-3 fatty acid treatment. This effect was possibly due to the beneficial changes in lipid concentrations and an attenuation of the risk factors oxLDL/LDL and (LDL5+LDL6)/LDLtot. Copyright 2009 S. Karger AG, Basel.

Arsenic augments the uptake of oxidized LDL by upregulating the expression of lectin-like oxidized LDL receptor in mouse aortic endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, Ekhtear; Ota, Akinobu, E-mail: aota@aichi-med-u.ac.jp; Karnan, Sivasundaram

Although chronic arsenic exposure is a well-known risk factor for cardiovascular diseases, including atherosclerosis, the molecular mechanism underlying arsenic-induced atherosclerosis remains obscure. Therefore, this study aimed to elucidate this molecular mechanism. We examined changes in the mRNA level of the lectin-like oxidized LDL (oxLDL) receptor (LOX-1) in a mouse aortic endothelial cell line, END-D, after sodium arsenite (SA) treatment. SA treatment significantly upregulated LOX-1 mRNA expression; this finding was also verified at the protein expression level. Flow cytometry and fluorescence microscopy analyses showed that the cellular uptake of fluorescence (Dil)-labeled oxLDL was significantly augmented with SA treatment. In addition, anmore » anti-LOX-1 antibody completely abrogated the augmented uptake of Dil-oxLDL. We observed that SA increased the levels of the phosphorylated forms of nuclear factor of kappa light polypeptide gene enhancer in B cells (NF-κB)/p65. SA-induced upregulation of LOX-1 protein expression was clearly prevented by treatment with an antioxidant, N-acetylcysteine (NAC), or an NF-κB inhibitor, caffeic acid phenethylester (CAPE). Furthermore, SA-augmented uptake of Dil-oxLDL was also prevented by treatment with NAC or CAPE. Taken together, our results indicate that arsenic upregulates LOX-1 expression through the reactive oxygen species-mediated NF-κB signaling pathway, followed by augmented cellular oxLDL uptake, thus highlighting a critical role of the aberrant LOX-1 signaling pathway in the pathogenesis of arsenic-induced atherosclerosis. - Highlights: • Sodium arsenite (SA) increases LOX-1 expression in mouse aortic endothelial cells. • SA enhances cellular uptake of oxidized LDL in dose-dependent manner. • SA-induced ROS generation enhances phosphorylation of NF-κB. • SA upregulates LOX-1 expression through ROS-activated NF-κB signaling pathway.« less

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy

PubMed Central

Chen, Mingyi; Qiu, Hong; Lin, Xin; Nam, David; Ogbu-Nwobodo, Lucy; Archibald, Hannah; Joslin, Amelia; Wun, Ted; Sawamura, Tatsuya; Green, Ralph

2017-01-01

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications. PMID:27519944

In vitro study of LDL transport under pressurized (convective) conditions.

PubMed

Cancel, Limary M; Fitting, Andrew; Tarbell, John M

2007-07-01

It is difficult to assess the transport pathways that carry low-density lipoprotein (LDL) into the artery wall in vivo, and there has been no previous in vitro study that has examined transendothelial transport under physiologically relevant pressurized (convective) conditions. Therefore, we measured water, albumin, and LDL fluxes across bovine aortic endothelial cell (BAEC) monolayers in vitro and determined the relative contributions of vesicles, paracellular transport through "breaks" in the tight junction, and "leaky" junctions associated with dying or dividing cells. Our results show that leaky junctions are the dominant pathway for LDL transport (>90%) under convective conditions and that albumin also has a significant component of transport through leaky junctions (44%). Transcellular transport of LDL by receptor-mediated processes makes a minor contribution (<10%) to overall transport under convective conditions.

Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages.

PubMed

Lanuti, Mirko; Talamonti, Emanuela; Maccarrone, Mauro; Chiurchiù, Valerio

2015-01-01

The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9)-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases.

Activation of GPR55 Receptors Exacerbates oxLDL-Induced Lipid Accumulation and Inflammatory Responses, while Reducing Cholesterol Efflux from Human Macrophages

PubMed Central

Lanuti, Mirko; Talamonti, Emanuela; Maccarrone, Mauro; Chiurchiù, Valerio

2015-01-01

The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with bone remodelling, nervous system excitability, vascular homeostasis as well as in several pathophysiological conditions including obesity and cancer. However, its physiological role and underlying mechanism remain unclear. In the present work, we demonstrate for the first time its presence in human macrophages and its increased expression in ox-LDL-induced foam cells. In addition, pharmacological activation of GPR55 by its selective agonist O-1602 increased CD36- and SRB-I-mediated lipid accumulation and blocked cholesterol efflux by downregulating ATP-binding cassette (ABC) transporters ABCA1 and ABCG1, as well as enhanced cytokine- and pro-metalloprotease-9 (pro-MMP-9)-induced proinflammatory responses in foam cells. Treatment with cannabidiol, a selective antagonist of GPR55, counteracted these pro-atherogenic and proinflammatory O-1602-mediated effects. Our data suggest that GPR55 could play deleterious role in ox-LDL-induced foam cells and could be a novel pharmacological target to manage atherosclerosis and other related cardiovascular diseases. PMID:25970609

Liver heparan sulfate proteoglycans mediate clearance of triglyceride-rich lipoproteins independently of LDL receptor family members

PubMed Central

MacArthur, Jennifer M.; Bishop, Joseph R.; Stanford, Kristin I.; Wang, Lianchun; Bensadoun, André; Witztum, Joseph L.; Esko, Jeffrey D.

2007-01-01

We examined the role of hepatic heparan sulfate in triglyceride-rich lipoprotein metabolism by inactivating the biosynthetic gene GlcNAc N-deacetylase/N-sulfotransferase 1 (Ndst1) in hepatocytes using the Cre-loxP system, which resulted in an approximately 50% reduction in sulfation of liver heparan sulfate. Mice were viable and healthy, but they accumulated triglyceride-rich lipoprotein particles containing apoB-100, apoB-48, apoE, and apoCI-IV. Compounding the mutation with LDL receptor deficiency caused enhanced accumulation of both cholesterol- and triglyceride-rich particles compared with mice lacking only LDL receptors, suggesting that heparan sulfate participates in the clearance of cholesterol-rich lipoproteins as well. Mutant mice synthesized VLDL normally but showed reduced plasma clearance of human VLDL and a corresponding reduction in hepatic VLDL uptake. Retinyl ester excursion studies revealed that clearance of intestinally derived lipoproteins also depended on hepatocyte heparan sulfate. These findings show that under normal physiological conditions, hepatic heparan sulfate proteoglycans play a crucial role in the clearance of both intestinally derived and hepatic lipoprotein particles. PMID:17200715

PCSK9 Inhibitors: Novel Therapeutic Strategies for Lowering LDL-Cholesterol.

PubMed

Liu, Zhao-Peng; Wang, Yan

2018-04-22

Statins are currently the major therapeutic strategies to lower low-density lipoprotein cholesterol (LDL-C) levels. However, a number of hypercholesterolemia patients still have a residual cardiovascular disease (CVD) risk despite taking the maximum-tolerated dose of statins. Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low-density lipoprotein receptor (LDLR), inducing its degradation in the lysosome and inhibiting LDLR recirculating to the cell membranes. The gain-of-function mutations in PCSK9 elevate the LDL-C levels in plasma. Therefore, PCSK9 inhibitors become novel therapeutic approaches in the treatment of hypercholesterolemia. Several PCSK9 inhibitors have been under investigation, and much progress has been made in clinical trials, especially for monoclonal antibodies (MoAbs). Two MoAbs, evolocumab and alirocumab, are now in clinical use. In this review, we summarize the development of PCSK9 inhibitors, including antisense oligonucleotides (ASOs), small interfering RNA (siRNA), small molecule inhibitor, MoAbs, mimetic peptides and adnectins, and the related safety issues. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Novel treatments for familial hypercholesterolemia: pharmacogenetics at work.

PubMed

Marbach, Jeffrey A; McKeon, Jessica L; Ross, Joyce L; Duffy, Danielle

2014-09-01

The familial hypercholesterolemias (FHs) are inherited disorders of lipoprotein metabolism that are among the most prevalent genetically inherited disorders. Various genetic mutations ultimately lead to greatly increased low-density lipoprotein-cholesterol (LDL-C) levels over a lifetime. Consequently, patients with FH develop coronary artery disease at significantly earlier ages and at a greater frequency than the general population. Current therapies revolve around aggressive lifestyle modifications, cholesterol-lowering medications, and in some cases LDL apheresis. Despite maximal medical therapy, LDL-C is not sufficiently reduced in some patients, and they remain at a substantially increased risk of coronary heart disease. Recent advances in genetic-based pharmacology have enabled the development of three novel classes of medications for FH. Two of those compounds, mipomersen and lomitapide, result in decreased LDL-C production and were approved by the Food and Drug Administration in the past 18 months for treatment of homozygous FH. Mipomersen is an antisense oligonucleotide that inhibits the translation of apolipoprotein B-100, and lomitapide is an inhibitor of the microsomal triglyceride transfer protein, which prevents the incorporation of triglycerides into lipoproteins. A third class of drugs, the proprotein convertase subtilisin/kexin type 9 inhibitors, is still in development, although studies in patients with heterozygous or receptor-defective homozygous FH have demonstrated substantial reductions in LDL-C by decreasing the degradation of LDL receptors. Development of these novel treatments for hypercholesterolemia resulted from the application of known genetic mutations and is the focus of this review. © 2014 Pharmacotherapy Publications, Inc.

Electronegative LDL induces priming and inflammasome activation leading to IL-1β release in human monocytes and macrophages.

PubMed

Estruch, M; Rajamäki, K; Sanchez-Quesada, J L; Kovanen, P T; Öörni, K; Benitez, S; Ordoñez-Llanos, J

2015-11-01

Electronegative LDL (LDL(−)), a modified LDL fraction found in blood, induces the release of inflammatory mediators in endothelial cells and leukocytes. However, the inflammatory pathways activated by LDL(−) have not been fully defined. We aim to study whether LDL(−) induced release of the first-wave proinflammatory IL-1β in monocytes and monocyte-derived macrophages (MDM) and the mechanisms involved. LDL(−) was isolated from total LDL by anion exchange chromatography. Monocytes and MDM were isolated from healthy donors and stimulated with LDL(+) and LDL(−) (100 mg apoB/L). In monocytes, LDL(−) promoted IL-1β release in a time-dependent manner, obtaining at 20 h-incubation the double of IL-1β release induced by LDL(−) than by native LDL. LDL(−)-induced IL-1β release involved activation of the CD14-TLR4 receptor complex. LDL(−) induced priming, the first step of IL-1β release, since it increased the transcription of pro-IL-1β (8-fold) and NLRP3 (3-fold) compared to native LDL. Several findings show that LDL(−) induced inflammasome activation, the second step necessary for IL-1β release. Preincubation of monocytes with K+ channel inhibitors decreased LDL(−)-induced IL-1β release. LDL(−) induced formation of the NLRP3-ASC complex. LDL(−) triggered 2-fold caspase-1 activation compared to native LDL and IL-1β release was strongly diminished in the presence of the caspase-1 inhibitor Z-YVAD. In MDM, LDL(−) promoted IL-1β release, which was also associated with caspase-1 activation. LDL(−) promotes release of biologically active IL-1β in monocytes and MDM by induction of the two steps involved: priming and NLRP3 inflammasome activation. By IL-1β release, LDL(−) could regulate inflammation in atherosclerosis.

Ground Beef High in Total Fat and Saturated Fatty Acids Decreases X Receptor Signaling Targets in Peripheral Blood Mononuclear Cells of Men and Women.

PubMed

Choi, Seong H; Gharahmany, Ghazal; Walzem, Rosemary L; Meade, Thomas H; Smith, Stephen B

2018-03-01

We hypothesized that consumption of saturated fatty acids in the form of high-fat ground beef for 5 weeks would depress liver X receptor signaling targets in peripheral blood mononuclear cells (PBMC) and that changes in gene expression would be associated with the corresponding changes in lipoprotein cholesterol (C) concentrations. Older men (n = 5, age 68.0 ± 4.6 years) and postmenopausal women (n = 7, age 60.9 ± 3.1 years) were assigned randomly to consume ground-beef containing 18% total fat (18F) or 25% total fat (25F), five patties per week for 5 weeks with an intervening 4-week washout period. The 25F and 18F ground-beef increased (p < 0.05) the intake of saturated fat, monounsaturated fat, palmitic acid, and stearic acid, but the 25F ground-beef increased only the intake of oleic acid (p < 0.05). The ground-beefs 18F and 25F increased the plasma concentration of palmitic acid (p < 0.05) and decreased the plasma concentrations of arachidonic, eicosapentaenoic, and docosahexaenic acids (p < 0.05). The interventions of 18F and 25F ground-beef decreased very low-density lipoprotein C concentrations and increased particle diameters and low-density lipoprotein (LDL)-I-C and LDL-II-C concentrations (p < 0.05). The ground-beef 25F decreased PBMC mRNA levels for the adenosine triphosphate (ATP) binding cassette A, ATP binding cassette G1, sterol regulatory element binding protein-1, and LDL receptor (LDLR) (p < 0.05). The ground-beef 18F increased mRNA levels for stearoyl-CoA desaturase-1 (p < 0.05). We conclude that the increased LDL particle size and LDL-I-C and LDL-II-C concentrations following the 25F ground-beef intervention may have been caused by decreased hepatic LDLR gene expression. © 2018 AOCS.

Increased atherosclerosis in mice with increased vascular biglycan content.

PubMed

Thompson, Joel C; Tang, Tao; Wilson, Patricia G; Yoder, Meghan H; Tannock, Lisa R

2014-07-01

The response to retention hypothesis of atherogenesis proposes that atherosclerosis is initiated via the retention of atherogenic lipoproteins by vascular proteoglycans. Co-localization studies suggest that of all the vascular proteoglycans, biglycan is the one most closely co-localized with LDL. The goal of this study was to determine if over-expression of biglycan in hyperlipidemic mice would increase atherosclerosis development. Transgenic mice were developed by expressing biglycan under control of the smooth muscle actin promoter, and were crossed to the LDL receptor deficient (C57BL/6 background) atherosclerotic mouse model. Biglycan transgenic and non-transgenic control mice were fed an atherogenic Western diet for 4-12 weeks. LDL receptor deficient mice overexpressing biglycan under control of the smooth muscle alpha actin promoter had increased atherosclerosis development that correlated with vascular biglycan content. Increased vascular biglycan content predisposes to increased lipid retention and increased atherosclerosis development. Published by Elsevier Ireland Ltd.

Dihydromyricetin ameliorates atherosclerosis in LDL receptor deficient mice.

PubMed

Liu, Ting Ting; Zeng, Yi; Tang, Kun; Chen, XueMeng; Zhang, Wei; Xu, Xiao Le

2017-07-01

Dihydromyricetin, the most abundant flavonoid in Ampelopsis grossedentata, exerts numerous pharmacological activities, including anti-inflammatory, antioxidant, hepatoprotective, and lipid regulatory activities; however, its protective effect against atherosclerosis remains poorly understood. The aim of the present study was to evaluate the effects of dihydromyricetin on high fat diet (HFD)-induced atherosclerosis using LDL receptor deficient (LDLr -/- ) mice. Blood samples were collected for determination of serum lipid profiles, oxidized LDL (ox-LDL) and pro-inflammatory cytokines. Histology, hepatic lipid content, quantification of atherosclerosis, assessment of oxidative stress and inflammation were performed on liver and aorta samples by molecular biology methods. The effects of dihydromyricetin on ox-LDL-induced human umbilical vein endothelial cells (HUVECs) dysfunction and foam cell formation were further studied. (1) Dihydromyricetin ameliorated hyperlipidemia, reduced serum ox-LDL, IL-6 and TNF-α levels in HFD-fed LDLr -/- mice. Moreover, (2) dihydromyricetin suppressed hepatic lipid accumulation and increased protein expressions of PPARα, LXRα and ABCA1. (3) It inhibited atherosclerotic lesion formation and favoured features of plaque stability. (4) Dihydromyricetin prevented hepatic and aortic inflammation as evidenced by the reduced IL-6 and TNF-α mRNA expression; (5) it prevented hepatic and aortic oxidative stress by normalizing activities of antioxidant enzymes in the liver and suppressing reactive oxygen species generation and NOX2 protein expression in both liver and aorta; (6) it inhibited oxLDL-induced injury, monocytes adhesion and oxidative stress in HUVECs and (7) inhibited macrophage foam cell formation and enhanced cholesterol efflux. These findings suggest that dihydromyricetin could reduce atherosclerosis via its pleiotropic effects, including improvement of endothelial dysfunction, inhibition of macrophage foam cell formation, amelioration of lipid profiles, anti-inflammatory action and anti-oxidative effect. Copyright © 2017 Elsevier B.V. All rights reserved.

Delineation of molecular pathways that regulate hepatic PCSK9 and LDL receptor expression during fasting in normolipidemic hamsters

PubMed Central

Wu, Minhao; Dong, Bin; Cao, Aiqin; Li, Hai; Liu, Jingwen

2015-01-01

Background PCSK9 has emerged as a key regulator of serum LDL-C metabolism by promoting the degradation of hepatic LDL receptor (LDLR). In this study, we investigated the effect of fasting on serum PCSK9, LDL-C, and hepatic LDLR expression in hamsters and further delineated the molecular pathways involved in fasting-induced repression of PCSK9 transcription. Results Fasting had insignificant effects on serum total cholesterol and HDL-C levels, but reduced LDL-C, triglyceride and insulin levels. The decrease in serum LDL-C was accompanied by marked reductions of hepatic PCSK9 mRNA and serum PCSK9 protein levels with concomitant increases of hepatic LDLR protein amounts. Fasting produced a profound impact on SREBP1 expression and its transactivating activity, while having modest effects on mRNA expressions of SREBP2 target genes in hamster liver. Although PPARα mRNA levels in hamster liver were elevated by fasting, ligand-induced activation of PPARα with WY14643 compound in hamster primary hepatocytes did not affect PCSK9 mRNA or protein expressions. Further investigation on HNF1α, a critical transactivator of PCSK9, revealed that fasting did not alter its mRNA expression, however, the protein abundance of HNF1α in nuclear extracts of hamster liver was markedly reduced by prolonged fasting. Conclusion Fasting lowered serum LDL-C in hamsters by increasing hepatic LDLR protein amounts via reductions of serum PCSK9 levels. Importantly, our results suggest that attenuation of SREBP1 transactivating activity owing to decreased insulin levels during fasting is primarily responsible for compromised PCSK9 gene transcription, which was further suppressed after prolonged fasting by a reduction of nuclear HNF1α protein abundance. PMID:22954675

Chronic kidney disease alters lipid trafficking and inflammatory responses in macrophages: effects of liver X receptor agonism.

PubMed

Kaseda, Ryohei; Tsuchida, Yohei; Yang, Hai-Chun; Yancey, Patricia G; Zhong, Jianyong; Tao, Huan; Bian, Aihua; Fogo, Agnes B; Linton, Mac Rae F; Fazio, Sergio; Ikizler, Talat Alp; Kon, Valentina

2018-01-27

Our aim was to evaluate lipid trafficking and inflammatory response of macrophages exposed to lipoproteins from subjects with moderate to severe chronic kidney disease (CKD), and to investigate the potential benefits of activating cellular cholesterol transporters via liver X receptor (LXR) agonism. LDL and HDL were isolated by sequential density gradient ultracentrifugation of plasma from patients with stage 3-4 CKD and individuals without kidney disease (HDL CKD and HDL Cont , respectively). Uptake of LDL, cholesterol efflux to HDL, and cellular inflammatory responses were assessed in human THP-1 cells. HDL effects on inflammatory markers (MCP-1, TNF-α, IL-1β), Toll-like receptors-2 (TLR-2) and - 4 (TLR-4), ATP-binding cassette class A transporter (ABCA1), NF-κB, extracellular signal regulated protein kinases 1/2 (ERK1/2) were assessed by RT-PCR and western blot before and after in vitro treatment with an LXR agonist. There was no difference in macrophage uptake of LDL isolated from CKD versus controls. By contrast, HD CKD was significantly less effective than HDL Cont in accepting cholesterol from cholesterol-enriched macrophages (median 20.8% [IQR 16.1-23.7] vs control (26.5% [IQR 19.6-28.5]; p = 0.008). LXR agonist upregulated ABCA1 expression and increased cholesterol efflux to HDL of both normal and CKD subjects, although the latter continued to show lower efflux capacity. HDL CKD increased macrophage cytokine response (TNF-α, MCP-1, IL-1β, and NF-κB) versus HDL Cont . The heightened cytokine response to HDL CKD was further amplified in cells treated with LXR agonist. The LXR-augmentation of inflammation was associated with increased TLR-2 and TLR-4 and ERK1/2. Moderate to severe impairment in kidney function promotes foam cell formation that reflects impairment in cholesterol acceptor function of HDL CKD . Activation of cellular cholesterol transporters by LXR agonism improves but does not normalize efflux to HDL CKD . However, LXR agonism actually increases the pro-inflammatory effects of HDL CKD through activation of TLRs and ERK1/2 pathways.

Berberine as a photosensitizing agent for antitumoral photodynamic therapy: Insights into its association to low density lipoproteins.

PubMed

Luiza Andreazza, Nathalia; Vevert-Bizet, Christine; Bourg-Heckly, Geneviève; Sureau, Franck; José Salvador, Marcos; Bonneau, Stephanie

2016-08-20

Recent years have seen a growing interest in Berberine, a phytochemical with multispectrum therapeutic activities, as anti-tumoral agent for photodynamic therapy (PDT). In this context, low density lipoproteins (LDL) play a key role in the delivery of the photosensitizer in tumor cells. We correlate the physicochemical parameters of the berberine association to LDL with the influence of LDL-delivery on its accumulation in a glioma cell line and on its photo-induced activity in view of antitumor PDT. Our results evidence an important binding of 400 berberine molecules per LDL. Changes in berberine and apoprotein fluorescence suggest different fixation types, involving various LDL compartments including the vicinity of the apoprotein. The berberine association to LDL does not affect their recognition by the specific B/E receptors, of which over-expression increases the cellular uptake of LDL-preloaded berberine. Fluorescence microscopy evidences the mitochondrial labeling of the glioma model cells, with no significant modification upon LDL-delivery. Moreover, the cellular delivery of berberine by LDL increases its photocytotoxic effects on such cells. So, this research illustrates the potential of berberine as a photosensitizing agent for PDT, in particular due to their behavior towards LDL as plasma vehicles, and gives insights into its mechanisms of cell uptake. Copyright © 2016. Published by Elsevier B.V.

Activation of PKC{beta}{sub II} and PKC{theta} is essential for LDL-induced cell proliferation of human aortic smooth muscle cells via Gi-mediated Erk1/2 activation and Egr-1 upregulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heo, Kyung-Sun; Department of Pharmacy, Chungnam National University, Yuseong, Daejeon; Kim, Dong-Uk

Native LDL may be a mitogenic stimulus of VSMC proliferation in lesions where endothelial disruption occurs. Recent studies have demonstrated that the mitogenic effects of LDL are accompanied by Erk1/2 activation via an unknown G-protein-coupled receptor (GPCR). In this article, we report that LDL translocated PKC{beta}{sub II} and PKC{theta} from cytosol to plasma membrane, and inhibition of PKC{beta}{sub II} and PKC{theta} decreased LDL effects via the deactivation of Erk1/2. Moreover, pertussis toxin, but not cholera toxin or heparin, inhibited LDL-induced translocation of PKC{beta}{sub II} and PKC{theta}, suggesting that Gi protein plays a role in LDL effects. Of LPA, S1P, andmore » LDL, whose signaling is conveyed via Gi/o proteins, only LDL induced translocation of PKC{beta}{sub II} and PKC{theta}. Inhibition of PKC{beta}{sub II} or PKC{theta}, as well as of Erk1/2 and GPCR, decreases LDL-induced upregulation of Egr-1, which is critical for cell proliferation. This is the first report, to our knowledge, that the participation of PKC{theta} in VSMC proliferation is unique.« less

Trapping of oxidized LDL in lysosomes of Kupffer cells is a trigger for hepatic inflammation.

PubMed

Bieghs, Veerle; Walenbergh, Sofie M A; Hendrikx, Tim; van Gorp, Patrick J; Verheyen, Fons; Olde Damink, Steven W; Masclee, Ad A; Koek, Ger H; Hofker, Marten H; Binder, Christoph J; Shiri-Sverdlov, Ronit

2013-08-01

Non-alcoholic steatohepatitis (NASH) is characterized by steatosis and inflammation. The transition from steatosis towards NASH represents a key step in pathogenesis, as it will set the stage for further severe liver damage. Under normal conditions, lipoproteins that are endocytosed by Kupffer cells (KCs) are easily transferred from the lysosomes into the cytoplasm. Oxidized LDL (oxLDL) that is taken up by the macrophages in vitro is trapped within the lysosomes, while acetylated LDL (acLDL) is leading to normal lysosomal hydrolysis, resulting in cytoplasmic storage. We have recently demonstrated that hepatic inflammation is correlated with lysosomal trapping of lipids. So far, a link between lysosomal trapping of oxLDL and inflammation was not established. We hypothesized that lysosomal trapping of oxLDL in KCs will lead to hepatic inflammation. Ldlr(-/-) mice were injected with LDL, acLDL and oxLDL and sacrificed after 2, 6 and 24 h. Electron microscopy of KCs demonstrated that after oxLDL injection, small lipid inclusions were present inside the lysosomes after all time points and were mostly pronounced after 6 and 24 h. In contrast, no lipid inclusions were present inside KCs after LDL or acLDL injection. Hepatic expression of several inflammatory genes and scavenger receptors was higher after oxLDL injections compared with LDL or acLDL. These data suggest that trapping of oxLDL inside lysosomes of KCs in vivo is causally linked to increased hepatic inflammatory gene expression. Our novel observations provide new bases for prevention and treatment of NASH. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Low-density lipoprotein reconstituted by pyropheophorbide cholesteryl oleate as target-specific photosensitizer.

PubMed

Zheng, Gang; Li, Hui; Zhang, Min; Lund-Katz, Sissel; Chance, Britton; Glickson, Jerry D

2002-01-01

To target tumors overexpressing low-density lipoprotein receptors (LDLr), a pyropheophorbide cholesterol oleate conjugate was synthesized and successfully reconstituted into the low-density lipoprotein (LDL) lipid core. Laser scanning confocal microscopy studies demonstrated that this photosensitizer-reconstituted LDL can be internalized via LDLr by human hepatoblastoma G(2) (HepG(2)) tumor cells.

APOC3 Loss-of-Function Mutations, Remnant Cholesterol, Low-Density Lipoprotein Cholesterol, and Cardiovascular Risk: Mediation- and Meta-Analyses of 137 895 Individuals.

PubMed

Wulff, Anders B; Nordestgaard, Børge G; Tybjærg-Hansen, Anne

2018-03-01

Loss-of-function mutations in APOC3 associate with low remnant cholesterol levels and low risk of ischemic vascular disease (IVD). Because some studies show an additional association with low levels of low-density lipoprotein cholesterol (LDL-C), low LDL-C may explain the low risk of IVD in APOC3 loss-of-function heterozygotes. We tested to what extent the low risk of IVD in APOC3 loss-of-function heterozygotes is mediated by low plasma remnant cholesterol and LDL-C. In APOC3 loss-of-function heterozygotes versus noncarriers, we first determined remnant cholesterol and LDL-C levels in meta-analyses of 137 895 individuals. Second, we determined whether the association with LDL-C was masked by lipid-lowering therapy. Finally, using mediation analysis, we determined the fraction of the low risk of IVD and ischemic heart disease mediated by remnant cholesterol and LDL-C. In meta-analyses, remnant cholesterol was 43% lower (95% confidence interval, 40%-47%), and LDL-C was 4% lower (1%-6%) in loss-of-function heterozygotes (n=776) versus noncarriers. In the general population, LDL-C was 3% lower in loss-of-function heterozygotes versus noncarriers, 4% lower when correcting for lipid-lowering therapy, and 3% lower in untreated individuals ( P values, 0.06-0.008). Remnant cholesterol mediated 37% of the observed 41% lower risk of IVD and 54% of the observed 36% lower risk of ischemic heart disease; corresponding values mediated by LDL-C were 1% and 2%. The low risk of IVD observed in APOC3 loss-of-function heterozygotes is mainly mediated by the associated low remnant cholesterol and not by low LDL-C. Furthermore, the contribution of LDL-C to IVD risk was not masked by lipid-lowering therapy. This suggests APOC3 and remnant cholesterol as important new targets for reducing cardiovascular risk. © 2018 American Heart Association, Inc.

Hematopoietic G-protein-coupled receptor kinase 2 deficiency decreases atherosclerotic lesion formation in LDL receptor-knockout mice

PubMed Central

Otten, Jeroen J. T.; de Jager, Saskia C. A.; Kavelaars, Annemieke; Seijkens, Tom; Bot, Ilze; Wijnands, Erwin; Beckers, Linda; Westra, Marijke M.; Bot, Martine; Busch, Matthias; Bermudez, Beatriz; van Berkel, Theo J. C.; Heijnen, Cobi J.; Biessen, Erik A. L.

2013-01-01

Leukocyte chemotaxis is deemed instrumental in initiation and progression of atherosclerosis. It is mediated by G-protein-coupled receptors (e.g., CCR2 and CCR5), the activity of which is controlled by G-protein-coupled receptor kinases (GRKs). In this study, we analyzed the effect of hematopoietic deficiency of a potent regulator kinase of chemotaxis (GRK2) on atherogenesis. LDL receptor-deficient (LDLr−/−) mice with heterozygous hematopoietic GRK2 deficiency, generated by bone marrow transplantation (n=15), displayed a dramatic attenuation of plaque development, with 79% reduction in necrotic core and increased macrophage content. Circulating monocytes decreased and granulocytes increased in GRK2+/− chimeras, which could be attributed to diminished granulocyte colony-forming units in bone marrow. Collectively, these data pointed to myeloid cells as major mediators of the impaired atherogenic response in GRK2+/− chimeras. LDLr−/− mice with macrophage/granulocyte-specific GRK2 deficiency (LysM-Cre GRK2flox/flox; n=8) failed to mimic the aforementioned phenotype, acquitting these cells as major responsible subsets for GRK2 deficiency-associated atheroprotection. To conclude, even partial hematopoietic GRK2 deficiency prevents atherosclerotic lesion progression beyond the fatty streak stage, identifying hematopoietic GRK2 as a potential target for intervention in atherosclerosis.—Otten, J. J. T., de Jager, S. C. A., Kavelaars, A., Seijkens, T., Bot, I., Wijnands, E., Beckers, L., Westra, M. M., Bot, M., Busch, M., Bermudez, B., van Berkel, T. J. C., Heijnen, C. J., Biessen, E. A. L. Hematopoietic G-protein-coupled receptor kinase 2 deficiency decreases atherosclerotic lesion formation in LDL receptor-knockout mice. PMID:23047899

New clinical perspectives of hypolipidemic drug therapy in severe hypercholesterolemia.

PubMed

Stefanutti, C; Morozzi, C; Di Giacomo, S

2012-01-01

Patients with homozygous familial hypercholesterolemia (HoFH) represent the most severe patients within the spectrum of dyslipidemias. Untreated Low-Density Lipoprotein Cholesterol (LDL-C) levels in these patients are usually in the range 500 to 1200 mg/dL. Moreover, these patients exhibit a scarce responsiveness or even non responsiveness to oral lipid lowering agents. Patients with heterozygous familial hypercholesterolemia (HetFH) tend to have untreated LDL-C levels of 250-500 mg/dL. Many of these patients are responsive to 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA-reductase) inhibitors (statins) and/or other specific drugs. Unfortunately, a significant subset of these patients (5-10%) have a severe and/or refractory form of HetFH and after current maximal oral therapy, they remain significantly far from treatment goals (The National Cholesterol Education Program (NCEP) ATPIII guidelines). This would be defined as LDL-C levels of ≥ 190 mg/dL - prior Coronary Heart Disease (CHD) or CHD equivalent - or ≥ 250 mg/dL (no prior CHD or CHD risk-equivalent). The only current therapy option for these patients is Low Density Lipoprotein-apheresis (LDL_a). While LDL_a is very effective in reducing LDL-C, many patients do not receive this extracorporeal therapy because of costs and limited availability of LDL_a centers. Recently, new potent lipid-lowering drugs have been developed and are currently under investigation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a critical role controlling the levels of LDL-C. Studies have demonstrated that PCSK9 acts mainly by enhancing degradation of the Low-Density Lipoprotein receptor (LDLR) protein in the liver. Inactivation of PCSK9 in mice reduces plasma cholesterol levels. Since the loss of a functional PCSK9 in human is not associated with apparent deleterious effects, this protease is becoming an attractive target for lowering plasma LDL-C levels either alone or in combination with statins. Mipomersen, an apolipoprotein B (ApoB) synthesis inhibitor, for lowering of LDL-C showed to be an effective therapy to reduce LDL-C concentrations in patients with HoFH who are already receiving lipid-lowering drugs, including high-dose statins. Lomitapide is a potent inhibitor of microsomal triglyceride transfer protein and is highly efficacious in reducing LDL-C and triglycerides (TG). Lomitapide is currently being developed for patients with HoFH at doses up to 60 mg/d. These new powerful lipid-lowering drugs might be possibly superior than available hypolipidemic agents. Their mechanisms of action, effectiveness, safety, and indication in severe, genetically determined dyslipidemias, are reviewed.

Regulation of hepatic LDL receptors by mTORC1 and PCSK9 in mice

PubMed Central

Ai, Ding; Chen, Chiyuan; Han, Seongah; Ganda, Anjali; Murphy, Andrew J.; Haeusler, Rebecca; Thorp, Edward; Accili, Domenico; Horton, Jay D.; Tall, Alan R.

2012-01-01

Individuals with type 2 diabetes have an increased risk of atherosclerosis. One factor underlying this is dyslipidemia, which in hyperinsulinemic subjects with early type 2 diabetes is typically characterized by increased VLDL secretion but normal LDL cholesterol levels, possibly reflecting enhanced catabolism of LDL via hepatic LDLRs. Recent studies have also suggested that hepatic insulin signaling sustains LDLR levels. We therefore sought to elucidate the mechanisms linking hepatic insulin signaling to regulation of LDLR levels. In WT mice, insulin receptor knockdown by shRNA resulted in decreased hepatic mTORC1 signaling and LDLR protein levels. It also led to increased expression of PCSK9, a known post-transcriptional regulator of LDLR expression. Administration of the mTORC1 inhibitor rapamycin caused increased expression of PCSK9, decreased levels of hepatic LDLR protein, and increased levels of VLDL/LDL cholesterol in WT but not Pcsk9–/– mice. Conversely, mice with increased hepatic mTORC1 activity exhibited decreased expression of PCSK9 and increased levels of hepatic LDLR protein levels. Pcsk9 is regulated by the transcription factor HNF1α, and our further detailed analyses suggest that increased mTORC1 activity leads to activation of PKCδ, reduced activity of HNF4α and HNF1α, decreased PCSK9 expression, and ultimately increased hepatic LDLR protein levels, which result in decreased circulating LDL levels. We therefore suggest that PCSK9 inhibition could be an effective way to reduce the adverse side effect of increased LDL levels that is observed in transplant patients taking rapamycin as immunosuppressive therapy. PMID:22426206

Measurement of /sup 125/I-low density lipoprotein uptake in selected tissues of the squirrel monkey by quantitative autoradiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tompkins, R.G.; Schnitzer, J.J.; Yarmush, M.L.

1988-09-01

A recently developed technique of absolute quantitative light microscopic autoradiography of /sup 125/I-labeled proteins in biologic specimens was used to measure /sup 125/I-low density lipoprotein (/sup 125/I-LDL) concentration levels in various tissues of the squirrel monkey after 30 minutes of in vivo LDL circulation. Liver and adrenal cortex exhibited high /sup 125/I-LDL concentrations, presumably because of binding to specific cell surface receptors and/or internalization in vascular beds with high permeability to LDL. High tissue concentrations of LDL were associated with the zona fasciculata and reticularis of the adrenal cortex and the interstitial cells of Leydig in the testis; significantly lowermore » levels of /sup 125/I-LDL were observed in the adrenal medulla, the zona glomerulosa, and germinal centers of the testis. Contrary to previous reports, low /sup 125/I-LDL concentrations were observed throughout the gastrointestinal tract and in lymph nodes. In addition, multiple arterial intramural focal areas of high /sup 125/I-LDL concentrations were identified in arteries supplying the adrenal gland, lymph node, small bowel, and liver.« less

Naphthalocyanine-reconstituted LDL nanoparticles for in vivo cancer imaging and treatment

PubMed Central

Song, Liping; Li, Hui; Sunar, Ulas; Chen, Juan; Corbin, Ian; Yodh, Arjun G; Zheng, Gang

2007-01-01

Low density lipoproteins (LDLs) are naturally occurring nanoparticles that are biocompatible, biodegradable and non-immunogenic. Moreover, the size of LDL particle is precisely controlled (~22 nm) by its apoB-100 component, setting them apart from liposomes and lipid micelles. LDL particles have long been proposed as a nanocarrier for targeted delivery of diagnostics and therapeutics to LDL receptor (LDLR)-positive cancers. Here, we report the design and synthesis of a novel naphthalocyanine (Nc)-based photodynamic therapy (PDT) agent, SiNcBOA, and describe its efficient reconstitution into LDL core (100:1 payload). Possessing a near-infrared (NIR) absorption wavelength (>800 nm) and extremely high extinction coefficient (>105 M–1cm–1), SiNcBOA holds the promise of treating deeply seated tumors. Reconstituted LDL particles (r-Nc-LDL) maintain the size and shape of native LDL as determined by transmission electron microscopy, and also retain their LDLR-mediated uptake by cancer cells as demonstrated by confocal microscopy. Its preferential uptake by tumor vs normal tissue was confirmed in vivo by noninvasive optical imaging technique, demonstrating the feasibility of using this nanoparticle for NIR imaging-guided PDT of cancer. PMID:18203443

Impact of high-fat diet and voluntary running on body weight and endothelial function in LDL receptor knockout mice.

PubMed

Langbein, Heike; Hofmann, Anja; Brunssen, Coy; Goettsch, Winfried; Morawietz, Henning

2015-05-01

Obesity and physical inactivity are important cardiovascular risk factors. Regular physical exercise has been shown to mediate beneficial effects in the prevention of cardiovascular diseases. However, the impact of physical exercise on endothelial function in proatherosclerotic low-density lipoprotein receptor deficient (LDLR(-/-)) mice has not been studied so far. Six-week-old male LDLR(-/-) mice were fed a standard diet or a high-fat diet (39 kcal% fat diet) for 20 weeks. The impact of high-fat diet and voluntary running on body weight and amount of white adipose tissue was monitored. Basal tone and endothelial function was investigated in aortic rings using a Mulvany myograph. LDLR(-/-) mice on high-fat diet had increased cumulative food energy intake, but also higher physical activity compared to mice on control diet. Body weight and amount of visceral and retroperitoneal white adipose tissue of LDLR(-/-) mice were significantly increased by high-fat diet and partially reduced by voluntary running. Endothelial function in aortae of LDLR(-/-) mice was impaired after 20 weeks on standard and high-fat diet and could not be improved by voluntary running. Basal tone showed a trend to be increased by high-fat diet. Voluntary running reduced body weight and amount of white adipose tissue in LDLR(-/-) mice. Endothelial dysfunction in LDLR(-/-) mice could not be improved by voluntary running. In a clinical context, physical exercise alone might not have an influence on functional parameters and LDL-C levels in patients with familial hypercholesterolemia. However, physical activity in these patients may be in general beneficial and should be performed. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Regulation of hepatic 7 alpha-hydroxylase expression by dietary psyllium in the hamster.

PubMed Central

Horton, J D; Cuthbert, J A; Spady, D K

1994-01-01

Soluble fiber consistently lowers plasma total and low density lipoprotein (LDL)-cholesterol concentrations in humans and various animal models including the hamster; however, the mechanism of this effect remains incompletely defined. We performed studies to determine the activity of dietary psyllium on hepatic 7 alpha-hydroxylase, 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase and LDL receptor expression in the hamster. In animals fed a cholesterol-free semisynthetic diet containing 7.5% cellulose (avicel) as a fiber source, substitution of psyllium for avicel increased hepatic 7 alpha-hydroxylase activity and mRNA levels by 3-4-fold. Comparable effects on 7 alpha-hydroxylase expression were observed with 1% cholestyramine. Psyllium also increased hepatic 7 alpha-hydroxylase activity and mRNA in animals fed a diet enriched with cholesterol and triglyceride. Activation of 7 alpha-hydroxylase was associated with an increase in hepatic cholesterol synthesis that was apparently not fully compensatory since the cholesterol content of the liver declined. Although dietary psyllium did not increase hepatic LDL receptor expression in animals fed the cholesterol-free, very-low-fat diet, it did increase (or at least restore) receptor expression that had been downregulated by dietary cholesterol and triglyceride. Thus, 7.5% dietary psyllium produced effects on hepatic 7 alpha-hydroxylase and LDL metabolism that were similar to those of 1% cholestyramine. Induction of hepatic 7 alpha-hydroxylase activity by dietary psyllium may account, in large part, for the hypocholesterolemic effect of this soluble fiber. Images PMID:8182140

Regulation of PCSK9 by nutraceuticals.

PubMed

Momtazi, Amir Abbas; Banach, Maciej; Pirro, Matteo; Katsiki, Niki; Sahebkar, Amirhossein

2017-06-01

PCSK9 (proprotein convertase subtilisin kexin type 9) is a liver secretory enzyme that regulates plasma low-density lipoprotein (LDL) cholesterol (LDL-C) levels through modulation of LDL receptor (LDLR) density on the surface of hepatocytes. Inhibition of PCSK9 using monoclonal antibodies can efficiently lower plasma LDL-C, non-high-density lipoprotein cholesterol and lipoprotein (a). PCSK9 inhibition is also an effective adjunct to statin therapy; however, the cost-effectiveness of currently available PCSK9 inhibitors is under question. Nutraceuticals offer a safe and cost-effective option for PCSK9 inhibition. Several nutraceuticals have been reported to modulate PCSK9 levels and exert LDL-lowering activity. Mechanistically, those nutraceuticals that inhibit PCSK9 through a SREBP (sterol-responsive element binding protein)-independent pathway can be more effective in lowering plasma LDL-C levels compared with those inhibiting PCSK9 through the SREBP pathway. The present review aims to collect available data on the nutraceuticals with PCSK9-inhibitory effect and the underlying mechanisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mutation in the PCSK9 Gene in Omani Arab Subjects with Autosomal Dominant Hypercholesterolemia and its Effect on PCSK9 Protein Structure.

PubMed

Al-Waili, Khalid; Al-Zidi, Ward Al-Muna; Al-Abri, Abdul Rahim; Al-Rasadi, Khalid; Al-Sabti, Hilal Ali; Shah, Karna; Al-Futaisi, Abdullah; Al-Zakwani, Ibrahim; Banerjee, Yajnavalka

2013-01-01

Proprotein convertase subtilisin/kexin type (PCSK9) is a crucial protein in LDL cholesterol (LDL-C) metabolism by virtue of its pivotal role in the degradation of the LDL receptor. Mutations in the PCSK9 gene have previously been found to segregate with autosomal dominant familial hypercholesterolemia (ADFH). In this study, DNA sequencing of the 12 exons of the PCSK9 gene has been performed for two patients with a clinical diagnosis of familial hypercholesterolemia where mutation in the LDL-receptor gene hasn't been excluded. One missense mutation was detected in the exon 9 PCSK9 gene in the two ADFH patients. The patients were found to be heterozygote for Ile474Val (SNP rs562556). Using an array of in silico tools, we have investigated the effect of the above mutation on different structural levels of the PCSK9 protein. Although, the mutation has already been reported in the literature for other populations, to the best of our knowledge this is the first report of a mutation in the PCSK9 gene from the Arab population, including the Omani population.

SKI-II--a sphingosine kinase 1 inhibitor--exacerbates atherosclerosis in low-density lipoprotein receptor-deficient (LDL-R-/-) mice on high cholesterol diet.

PubMed

Potì, Francesco; Ceglarek, Uta; Burkhardt, Ralph; Simoni, Manuela; Nofer, Jerzy-Roch

2015-05-01

Sphingosine 1-phosphate (S1P) is a lysosphingolipid associated with high-density lipoproteins (HDL) that contributes to their anti-atherogenic potential. We investigated whether a reduction in S1P plasma levels affects atherosclerosis in low-density lipoprotein receptor deficient (LDL-R-/-) mice. LDL-R-/- mice on Western diet containing low (0.25% w/w) or high (1.25% w/w) cholesterol were treated for 16 weeks with SKI-II, a sphingosine kinase 1 inhibitor that significantly reduced plasma S1P levels. SKI-II treatment increased atherosclerotic lesions in the thoracic aorta in mice on high but not low cholesterol diet. This compound did not affect body weight, blood cell counts and plasma total and HDL cholesterol, but decreased triglycerides. In addition, mice on high cholesterol diet receiving SKI-II showed elevated levels of tumor necrosis factor-α and endothelial adhesion molecules (sICAM-1, sVCAM-1). Prolonged lowering of plasma S1P produces pro-atherogenic effects in LDL-R-/- mice that are evident under condition of pronounced hypercholesterolemia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Mode-of-action evaluation for the effect of trans fatty acids on low-density lipoprotein cholesterol.

PubMed

Reichard, John F; Haber, Lynne T

2016-12-01

The purpose of this work is to systematically consider the data relating to the mode of action (MOA) for the effects of industrially produced trans fatty acid (iTFA) on plasma low-density lipoprotein (LDL) levels. The hypothesized MOA is composed of two key events: increased LDL production and decreased LDL clearance. A substantial database supports this MOA, although the key events are likely to be interdependent, rather than sequential. Both key events are functions of nonlinear biological processes including rate-limited clearance, receptor-mediated transcription, and both positive and negative feedback regulation. Each key event was evaluated based on weight-of-evidence analysis and for human relevance. We conclude that the data are inadequate for a detailed dose-response analysis in the context of the evolved Bradford Hill considerations; however, the weight of evidence is strong and the overall shape of the dose-response curves for markers of the key events and the key determinants of those relationships is well understood in many cases and is nonlinear. Feedback controls are responsible for maintaining homeostasis of cholesterol and triglyceride levels and underlie both of the key events, resulting in a less-than-linear or thresholded relationship between TFA and LDL-C. The inconsistencies and gaps in the database are discussed. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

PCSK9 LNA antisense oligonucleotides induce sustained reduction of LDL cholesterol in nonhuman primates.

PubMed

Lindholm, Marie W; Elmén, Joacim; Fisker, Niels; Hansen, Henrik F; Persson, Robert; Møller, Marianne R; Rosenbohm, Christoph; Ørum, Henrik; Straarup, Ellen M; Koch, Troels

2012-02-01

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as a therapeutic target for the reduction of low-density lipoprotein cholesterol (LDL-C). PCSK9 increases the degradation of the LDL receptor, resulting in high LDL-C in individuals with high PCSK9 activity. Here, we show that two locked nucleic acid (LNA) antisense oligonucleotides targeting PCSK9 produce sustained reduction of LDL-C in nonhuman primates after a loading dose (20 mg/kg) and four weekly maintenance doses (5 mg/kg). PCSK9 messenger RNA (mRNA) and serum PCSK9 protein were reduced by 85% which resulted in a 50% reduction in circulating LDL-C. Serum total cholesterol (TC) levels were reduced to the same extent as LDL-C with no reduction in high-density lipoprotein levels, demonstrating a specific pharmacological effect on LDL-C. The reduction in hepatic PCSK9 mRNA correlated with liver LNA oligonucleotide content. This verified that anti-PCSK9 LNA oligonucleotides regulated LDL-C through an antisense mechanism. The compounds were well tolerated with no observed effects on toxicological parameters (liver and kidney histology, alanine aminotransferase, aspartate aminotransferase, urea, and creatinine). The pharmacologic evidence and initial safety profile of the compounds used in this study indicate that LNA antisense oligonucleotides targeting PCSK9 provide a viable therapeutic strategy and are potential complements to statins in managing high LDL-C.

Associations Between Polymorphisms in the Glucocorticoid-Receptor Gene and Cardiovascular Risk Factors in a Chinese Population

PubMed Central

Yan, Yu-Xiang; Dong, Jing; Wu, Li-Juan; Shao, Shuang; Zhang, Jie; Zhang, Ling; Wang, Wei; He, Yan; Liu, You-Qin

2013-01-01

Background Glucocorticoid is an important regulator of energy homeostasis. Glucocorticoid receptor (GR) gene polymorphisms that contribute to variability in glucocorticoid sensitivity have been identified. We explored the associations of single-nucleotide polymorphisms (SNPs) of the GR gene with traditional cardiovascular risk factors in the Chinese Han population. Methods We recruited 762 consecutive adults who underwent a regular physical examination at Beijing Xuanwu Hospital. Blood pressure, glucose, lipid levels (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein [LDL] cholesterol and triglycerides), body mass index (BMI), and waist-to-hip ratio were measured. Fourteen tag SNPs and 5 functional SNPs were selected and genotyped using the high-throughput Sequenom genotyping platform. Differences between genotypes/alleles for each SNP were adjusted for sex and age and tested using a general linear model procedure. Various models of inheritance, including additive, dominant, and recessive, were tested. Results Among the 19 SNPs examined, 5 markers were associated with cardiovascular risk factors. The rs41423247 GG genotype and the rs7701443 AA genotype were associated with higher BMI and systolic blood pressure (P < 0.0004), and the rs17209251 GG genotype was associated with higher systolic blood pressure (P < 0.0004). Lower systolic blood pressure, total cholesterol, and LDL cholesterol were observed among rs10052957 A allele carriers (P < 0.0004), and lower plasma glucose and LDL-cholesterol concentrations were observed among rs2963156 TT carriers (P < 0.0004). Conclusions Polymorphism of the GR gene was associated with cardiovascular risk factors and may contribute to susceptibility to cardiovascular disease. PMID:23892712

Electronegative Low-Density Lipoprotein Increases C-Reactive Protein Expression in Vascular Endothelial Cells through the LOX-1 Receptor

PubMed Central

Chu, Chih-Sheng; Wang, Yu-Chen; Lu, Long-Sheng; Walton, Brian; Yilmaz, H. Ramazan; Huang, Roger Y.; Sawamura, Tatsuya; Dixon, Richard A. F.; Lai, Wen-Ter; Chen, Chu-Huang; Lu, Jonathan

2013-01-01

Objectives Increased plasma C-reactive protein (CRP) levels are associated with the occurrence and severity of acute coronary syndrome. We investigated whether CRP can be generated in vascular endothelial cells (ECs) after exposure to the most electronegative subfraction of low-density lipoprotein (LDL), L5, which is atherogenic to ECs. Because L5 and CRP are both ligands for the lectin-like oxidized LDL receptor-1 (LOX-1), we also examined the role of LOX-1. Methods and Results Plasma LDL samples isolated from asymptomatic hypercholesterolemic (LDL cholesterol [LDL-C] levels, 154.6±20 mg/dL; n = 7) patients and normocholesterolemic (LDL-C levels, 86.1±21 mg/dL; P<0.001; n = 7) control individuals were chromatographically resolved into 5 subfractions, L1-L5. The L5 percentage (L5%) and the plasma L5 concentration ([L5]  =  L5% × LDL-C) in the patient and control groups were 8.1±2% vs. 2.3±1% (P<0.001) and 12.6±4 mg/dL vs. 1.9±1 mg/dL (P<0.001), respectively. In hypercholesterolemic patients treated with atorvastatin for 6 months (10 mg/day), [L5] decreased from 12.6±4 mg/dL to 4.5±1.1 mg/dL (P = 0.011; n = 5), whereas both [L5] and L5% returned to baseline levels in 2 noncompliant patients 3 months after discontinuation. In cultured human aortic ECs (HAECs), L5 upregulated CRP expression in a dose- and time-dependent manner up to 2.5-fold (P<0.01), whereas the least electronegative subfraction, L1, had no effect. DiI-labeled L1, internalized through the LDL receptor, became visible inside HAECs within 30 seconds. In contrast, DiI-labeled L5, internalized through LOX-1, became apparent after 5 minutes. L5-induced CRP expression manifested at 30 minutes and was attenuated by neutralizing LOX-1. After 30 minutes, L5 but not L1 induced reactive oxygen species (ROS) production. Both L5-induced ROS and CRP production were attenuated by ROS inhibitor N-acetyl cysteine. Conclusions Our results suggest that CRP, L5, and LOX-1 form a cyclic mechanism in atherogenesis and that reducing plasma L5 levels with atorvastatin disrupts the vascular toxicity of L5. PMID:23950953

Receptor-mediated endocytosis and intracellular trafficking of insulin and low-density lipoprotein by retinal vascular endothelial cells.

PubMed

Stitt, A W; Anderson, H R; Gardiner, T A; Bailie, J R; Archer, D B

1994-08-01

The authors investigated the receptor-mediated endocytosis (RME) and intracellular trafficking of insulin and low-density lipoprotein (LDL) in cultured retinal vascular endothelial cells (RVECs). Low-density lipoprotein and insulin were conjugated to 10 nm colloidal gold, and these ligands were added to cultured bovine RVECs for 20 minutes at 4 degrees C. The cultures were then warmed to 37 degrees C and fixed after incubation times between 30 seconds and 1 hour. Control cells were incubated with unconjugated gold colloid at times and concentrations similar to those of the ligands. Additional control cells were exposed to several concentrations of anti-insulin receptor antibody or a saturating solution of unconjugated insulin before incubation with gold insulin. Using transmission electron microscopy, insulin gold and LDL gold were both observed at various stages of RME. Insulin-gold particles were first seen to bind to the apical plasma membrane (PM) before clustering in clathrin-coated pits and internalization in coated vesicles. Gold was later visualized in uncoated cytoplasmic vesicles, corresponding to early endosomes and multivesicular bodies (MVBs) or late endosomes. In several instances, localized regions of the limiting membrane of the MVBs appeared coated, a feature of endosomal membranes not previously described. After RME at the apical PM and passage through the endosomal system, the greater part of both insulin- and LDL-gold conjugates was seen to accumulate in large lysosome-like compartments. However, a small but significant proportion of the internalized ligands was transcytosed and released as discrete membrane-associated quanta at the basal cell surface. The uptake of LDL gold was greatly increased in highly vacuolated, late-passage RVECs. In controls, anti-insulin receptor antibody and excess unconjugated insulin caused up to 89% inhibition in gold-insulin binding and internalization. These results illustrate the internalization and intracellular trafficking by RVECs of insulin and LDL through highly efficient RME, and they provide evidence for at least two possible fates for the endocytosed ligands. This study outlines a route by which vital macromolecules may cross the inner blood-retinal barrier.

LRP1 integrates murine macrophage cholesterol homeostasis and inflammatory responses in atherosclerosis

PubMed Central

Zhou, Li; Plattner, Florian; Liu, Mingxia; Parks, John S; Hammer, Robert E; Boucher, Philippe; Tsai, Shirling

2017-01-01

Low-density lipoprotein receptor-related protein 1 (LRP1) is a multifunctional cell surface receptor with diverse physiological roles, ranging from cellular uptake of lipoproteins and other cargo by endocytosis to sensor of the extracellular environment and integrator of a wide range of signaling mechanisms. As a chylomicron remnant receptor, LRP1 controls systemic lipid metabolism in concert with the LDL receptor in the liver, whereas in smooth muscle cells (SMC) LRP1 functions as a co-receptor for TGFβ and PDGFRβ in reverse cholesterol transport and the maintenance of vascular wall integrity. Here we used a knockin mouse model to uncover a novel atheroprotective role for LRP1 in macrophages where tyrosine phosphorylation of an NPxY motif in its intracellular domain initiates a signaling cascade along an LRP1/SHC1/PI3K/AKT/PPARγ/LXR axis to regulate and integrate cellular cholesterol homeostasis through the expression of the major cholesterol exporter ABCA1 with apoptotic cell removal and inflammatory responses. PMID:29144234

Electronegative L5-LDL induces the production of G-CSF and GM-CSF in human macrophages through LOX-1 involving NF-κB and ERK2 activation.

PubMed

Yang, Tzu-Ching; Chang, Po-Yuan; Kuo, Tzu-Ling; Lu, Shao-Chun

2017-12-01

Circulating levels of granulocyte colony-stimulating factor (G-CSF) and granulocyte macrophage colony-stimulating factor (GM-CSF) are associated with the severity of acute myocardial infarction (AMI). However, what causes increases in G-CSF and GM-CSF is unclear. In this study, we investigated whether L5-low-density lipoprotein (LDL), a mildly oxidized LDL from AMI, can induce G-CSF and GM-CSF production in human macrophages. L1-LDL and L5-LDL were isolated through anion-exchange chromatography from AMI plasma. Human macrophages derived from THP-1 and peripheral blood mononuclear cells were treated with L1-LDL, L5-LDL, or copper-oxidized LDL (Cu-oxLDL) and G-CSF and GM-CSF protein levels in the medium were determined. In addition, the effects of L5-LDL on G-CSF and GM-CSF production were tested in lectin-type oxidized LDL receptor-1 (LOX-1), CD36, extracellular signal-regulated kinase (ERK) 1, and ERK2 knockdown THP-1 macrophages. L5-LDL but not L1-LDL or Cu-oxLDL significantly induced production of G-CSF and GM-CSF in macrophages. In vitro oxidation of L1-LDL and L5-LDL altered their ability to induce G-CSF and GM-CSF, suggesting that the degree of oxidation is critical for the effects. Knockdown and antibody neutralization experiments suggested that the effects were caused by LOX-1. In addition, nuclear factor (NF)-κB and ERK1/2 inhibition resulted in marked reductions of L5-LDL-induced G-CSF and GM-CSF production. Moreover, knockdown of ERK2, but not ERK1, hindered L5-LDL-induced G-CSF and GM-CSF production. The results indicate that L5-LDL, a naturally occurring mild oxidized LDL, induced G-CSF and GM-CSF production in human macrophages through LOX-1, ERK2, and NF-κB dependent pathways. Copyright © 2017 Elsevier B.V. All rights reserved.

PPARδ modulates oxLDL-induced apoptosis of vascular smooth muscle cells through a TGF-β/FAK signaling axis.

PubMed

Hwang, Jung Seok; Eun, So Young; Ham, Sun Ah; Yoo, Taesik; Lee, Won Jin; Paek, Kyung Shin; Do, Jeong Tae; Lim, Dae-Seog; Seo, Han Geuk

2015-05-01

The peroxisome proliferator-activated receptor delta (PPARδ) has been implicated in the modulation of vascular homeostasis. However, its roles in the apoptotic cell death of vascular smooth muscle cells (VSMCs) are poorly understood. Here, we demonstrate that PPARδ modulates oxidized low-density lipoprotein (oxLDL)-induced apoptosis of VSMCs through the transforming growth factor-β (TGF-β) and focal adhesion kinase (FAK) signaling pathways. Activation of PPARδ by GW501516, which is a specific ligand, significantly inhibited oxLDL-induced cell death and generation of reactive oxygen species in VSMCs. These inhibitory effects were significantly reversed in the presence of small interfering (si)RNA against PPARδ, or by blockade of the TGF-β or FAK signaling pathways. Furthermore, PPARδ-mediated recovery of FAK phosphorylation suppressed by oxLDL was reversed by SB431542, a specific ALK5 receptor inhibitor, indicating that a TGF-β/FAK signaling axis is involved in the action of PPARδ. Among the protein kinases activated by oxLDL, p38 mitogen-activated protein kinase was suppressed by ligand-activated PPARδ. In addition, oxLDL-induced expression and translocation of pro-apoptotic or anti-apoptotic factors were markedly affected in the presence of GW501516. Those effects were reversed by PPARδ siRNA, or inhibitors of TGF-β or FAK, which also suggests that PPARδ exerts its anti-apoptotic effect via a TGF-β/FAK signaling axis. Taken together, these findings indicate that PPARδ plays an important role in the pathophysiology of disease associated with apoptosis of VSMC, such as atherosclerosis and restanosis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Macrophage heterogeneity and cholesterol homeostasis: classically-activated macrophages are associated with reduced cholesterol accumulation following treatment with oxidized LDL.

PubMed

Chu, Eugene M; Tai, Daven C; Beer, Jennifer L; Hill, John S

2013-02-01

Macrophages are centrally involved during atherosclerosis development and are the predominant cell type that accumulates cholesterol in the plaque. Macrophages however, are heterogeneous in nature reflecting a variety of microenvironments and different phenotypes may be more prone to contribute towards atherosclerosis progression. Using primary human monocyte-derived macrophages, we sought to evaluate one aspect of atherogenic potential of different macrophage phenotypes by determining their propensity to associate with and accumulate oxidized low density lipoprotein (oxLDL). Classically-activated macrophages treated simultaneously with interferon γ (IFNγ) and tumor necrosis factor α (TNFα) associated with less oxLDL and accumulated less cholesterol compared to untreated controls. The combined treatment of IFNγ and TNFα reduced the mRNA expression of CD36 and the expression of both cell surface CD36 and macrophage scavenger receptor 1 (MSR1) protein. Under oxLDL loaded conditions, IFNγ and TNFα did not reduce macrophage protein expression of the transcription factor peroxisome proliferator-actived receptor γ (PPARγ) which is known to positively regulate CD36 expression. However, macrophages treated with IFNγ attenuated the ability of the PPARγ-specific agonist rosiglitazone from upregulating cell surface CD36 protein expression. Our results demonstrate that the observed reduction of cholesterol accumulation in macrophages treated with IFNγ and TNFα following oxLDL treatment was due at least in part to reduced cell surface CD36 and MSR1 protein expression. Copyright © 2012 Elsevier B.V. All rights reserved.

F-spondin inhibits migration and differentiation of osteoclastic precursors.

PubMed

Oka, Hiroko; Mori, Maya; Kihara, Hisae

2011-12-01

Clinically, severe cemental resorption is a rare consequence of periodontitis, although alveolar bone resorption by osteoclasts is one of the main pathologic changes. F-spondin is a secreted neuronal glycoprotein that localizes to the cementum. F-spondin is among the cementum-specific factors in periodontal tissue that have been reported. However, the effects of F-spondin on osteoclastogenesis have not yet been established. We examined the effects of F-spondin on stages of osteoclastogenesis, migration, and differentiation in a mouse osteoclastic precursor model, RAW 264 cells. RAW 264 cells were treated with recombinant F-spondin. Macrophage colony stimulating factor (M-CSF)-induced cell migration was examined by migration assay performed with cell culture inserts. Osteoclastic differentiation was measured by counting tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. In a transmigration assay, F-spondin significantly downregulated M-CSF-induced cell migration. Further, F-spondin significantly reduced the number of receptor activator of nuclear factor-kappa B ligand-induced TRAP-positive multinucleated cells. The receptor-associated protein, an antagonist of the low-density lipoprotein (LDL) receptor family, blocked the effects of F-spondin on M-CSF-induced migration. The suppressive effect of F-spondin on M-CSF-induced cell migration was blocked by knockdown of LDL receptor-related protein 8 (LRP8), a member of the LDL receptor family. Our findings suggest that F-spondin downregulates recruitment to the root side of periodontal tissue via LRP8 and inhibits differentiation of osteoclastic precursors. It is suggested that F-spondin is essential to protect the root surface from resorption.

Inhibition of the NLRP3 inflammasome attenuates foam cell formation of THP-1 macrophages by suppressing ox-LDL uptake and promoting cholesterol efflux.

PubMed

Chen, Liang; Yao, Qiying; Xu, Siwei; Wang, Hongyan; Qu, Peng

2018-01-01

The NOD-like receptor family, pyrin domain-containing protein 3 (NLRP3) inflammasome plays an important role in the development of atherosclerosis. The activated NLRP3 inflammasome has been reported to promote macrophage foam cell formation, but not all studies have obtained the same result, and how NLRP3 inflammasome is involved in the formation of foam cells remains elusive. We used selective NLRP3 inflammasome inhibitors and NLRP3-deficient THP-1 cells to assess the effect of NLRP3 inflammasome inhibition on macrophage foam cell formation, oxidized low-density lipoprotein (ox-LDL) uptake, esterification, and cholesterol efflux, as well as the expression of associated proteins. Inhibition of the NLRP3 inflammasome attenuated foam cell formation, diminished ox-LDL uptake, and promoted cholesterol efflux from THP-1 macrophages. Moreover, it downregulated CD36, acyl coenzyme A: cholesterol acyltransferase-1 and neutral cholesterol ester hydrolase expression; upregulated ATP-binding cassette transporter A1 (ABCA1) and scavenger receptor class B type I (SR-BI) expression; but had no effect on the expression of scavenger receptor class A and ATP-binding cassette transporter G1. Collectively, our findings show that inhibition of the NLRP3 inflammasome decreases foam cell formation of THP-1 macrophages via suppression of ox-LDL uptake and enhancement of cholesterol efflux, which may be due to downregulation of CD36 expression and upregulation of ABCA1 and SR-BI expression, respectively. Copyright © 2017 Elsevier Inc. All rights reserved.

Involvement of toll-like receptor 2 and 4 in association between dyslipidemia and osteoclast differentiation in apolipoprotein E deficient rat periodontium

PubMed Central

2013-01-01

Background Dyslipidemia increases circulating levels of oxidized low-density lipoprotein (OxLDL) and this may induce alveolar bone loss through toll-like receptor (TLR) 2 and 4. The purpose of this study was to investigate the effects of dyslipidemia on osteoclast differentiation associated with TLR2 and TLR4 in periodontal tissues using a rat dyslipidemia (apolipoprotein E deficient) model. Methods Levels of plasma OxLDL, and the cholesterol and phospholipid profiles in plasma lipoproteins were compared between apolipoprotein E-deficient rats (16-week-old males) and wild-type (control) rats. In the periodontal tissue, we evaluated the changes in TLR2, TLR4, receptor activator of nuclear factor kappa B ligand (RANKL) and tartrate resistant acid phosphatase (TRAP) expression. Results Apolipoprotein E-deficient rats showed higher plasma levels of OxLDL than control rats (p<0.05), with higher plasma levels of total cholesterol (p<0.05) and LDL-cholesterol (p<0.05) and lower plasma levels of high-density lipoprotein cholesterol (p<0.05). Their periodontal tissue also exhibited a higher ratio of RANKL-positive cells and a higher number of TRAP-positive osteoclasts than control rats (p<0.05). Furthermore, periodontal gene expression of TLR2, TLR4 and RANKL was higher in apolipoprotein E-deficient rats than in control rats (p<0.05). Conclusion These findings underscore the important role for TLR2 and TLR4 in mediating the osteoclast differentiation on alveolar bone response to dyslipidemia. PMID:23295061

Lipids, cardiovascular disease, and oral contraceptives: a practical perspective.

PubMed

Upton, G V

1990-01-01

Figure 9 is an attempt to summate the influences of life-style on lipid parameters. Based on the work of Nikkila, it shows the source of the production of HDL and LDL, the factors that can affect these lipoprotein levels, and where in the cascade of lipoprotein metabolism these factors exert influence. The source of HDL production is the liver and the intestine. At this stage, diet, exercise, hormones, genetics, drugs, and certain disease states can affect HDL levels. Lecithin-cholesterol acyl transferase (LCAT) esterifies HDL-free cholesterol in plasma, and HDL3 is formed that in turn is transformed to HDL2. At the same time, VLDL from the gut and the liver will be converted, under the influence of LPL, to HDL2 and LDL. Thus HDL2 is being formed by the breakdown of VLDL and from the transformation of HDL3 to HDL2. Insulin, exercise, alcohol, fats, drugs, and diet affect lipoprotein lipase and consequently influence levels of LDL and HDL2 indirectly. Progestogens increase and estrogens decrease hepatic endothelial lipase, thus affecting the HDL2 concentration. It is at this point that combination OCs influence HDL2. The balance between estrogen and progestogen in a given contraceptive determines the extent and direction of HDL2 concentration. A separate pathway in the liver also catabolizes HDL2 and HDL3. LDL is generated partly from catabolism of VLDL and is partly secreted from the liver. The removal of LDL is mediated by receptors in both the liver and peripheral tissues. It is here that the Brown-Goldstein theory plays a major role. If LDL receptors are present in an insufficient number or are defective, then the C will accumulate and atherosclerosis may follow. Thus two key enzymes, LCAT and LPL, control the production of HDL2 and LDL, whereas a third enzyme, hepatic endothelial lipase, catabolizes HDL2.

Factor VIII Interacts with the Endocytic Receptor Low-density Lipoprotein Receptor-related Protein 1 via an Extended Surface Comprising "Hot-Spot" Lysine Residues.

PubMed

van den Biggelaar, Maartje; Madsen, Jesper J; Faber, Johan H; Zuurveld, Marleen G; van der Zwaan, Carmen; Olsen, Ole H; Stennicke, Henning R; Mertens, Koen; Meijer, Alexander B

2015-07-03

Lysine residues are implicated in driving the ligand binding to the LDL receptor family. However, it has remained unclear how specificity is regulated. Using coagulation factor VIII as a model ligand, we now study the contribution of individual lysine residues in the interaction with the largest member of the LDL receptor family, low-density lipoprotein receptor-related protein (LRP1). Using hydrogen-deuterium exchange mass spectrometry (HDX-MS) and SPR interaction analysis on a library of lysine replacement variants as two independent approaches, we demonstrate that the interaction between factor VIII (FVIII) and LRP1 occurs over an extended surface containing multiple lysine residues. None of the individual lysine residues account completely for LRP1 binding, suggesting an additive binding model. Together with structural docking studies, our data suggest that FVIII interacts with LRP1 via an extended surface of multiple lysine residues that starts at the bottom of the C1 domain and winds around the FVIII molecule. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Oxidation-labile subfraction of human plasma low density lipoprotein isolated by ion-exchange chromatography.

PubMed

Shimano, H; Yamada, N; Ishibashi, S; Mokuno, H; Mori, N; Gotoda, T; Harada, K; Akanuma, Y; Murase, T; Yazaki, Y

1991-05-01

We isolated subfractions of human plasma low density lipoprotein (LDL) using ion-exchange chromatography. Plasma LDL from normolipidemic subjects were applied to a DEAE Sepharose 6B column. After elution of the bulk of LDL at 150 mM NaCl (the major fraction), the residual LDL was eluted at 500 mM NaCl and designated as the minor fraction. The minor fraction, only less than 1% of total LDL, tended to be somewhat similar in certain properties to oxidized LDL, e.g., an increased negative charge, higher protein/cholesterol ratio, and a higher flotation density than native LDL. These results were consistent with data reported by Avogaro et al. (1988. Arteriosclerosis. 8: 79-87). However, assays of 125I-labeled LDL binding activity for LDL receptors equal to that of the major fraction. Incorporation of [14C]oleate into cholesteryl ester [acyl-CoA:cholesterol acyltransferase (ACAT) activity] in mouse peritoneal macrophages incubated with the minor fraction was only slightly greater than that with the major fraction. Incubation of the minor fraction with 0.5 microM Cu2+ caused a remarkable stimulation of ACAT activity, while stimulation by the major fraction required incubation with 5 microM Cu2+, suggesting that the minor fraction was relatively labile to oxidation. The minor but definite presence of a plasma LDL subfraction more negative and susceptible to oxidation implicates the possibility of its association with atherogenesis.

Compared with saturated fatty acids, dietary monounsaturated fatty acids and carbohydrates increase atherosclerosis and VLDL cholesterol levels in LDL receptor-deficient, but not apolipoprotein E-deficient, mice

PubMed Central

Merkel, Martin; Velez-Carrasco, Wanda; Hudgins, Lisa C.; Breslow, Jan L.

2001-01-01

Heart-healthy dietary recommendations include decreasing the intake of saturated fatty acids (SFA). However, the relative benefit of replacing SFA with monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), or carbohydrates (CARB) is still being debated. We have used two mouse models of atherosclerosis, low density lipoprotein receptor-deficient (LDLRKO) and apolipoprotein E-deficient (apoEKO) mice to measure the effects of four isocaloric diets enriched with either SFA, MUFA, PUFA, or CARB on atherosclerotic lesion area and lipoprotein levels. In LDLRKO mice, compared with the SFA diet, the MUFA and CARB diets significantly increased atherosclerosis in both sexes, but the PUFA diet had no effect. The MUFA and CARB diets also increased very low density lipoprotein-cholesterol (VLDL-C) and LDL-cholesterol (LDL-C) in males and VLDL-C levels in females. Analysis of data from LDLRKO mice on all diets showed that atherosclerotic lesion area correlated positively with VLDL-C levels (males: r = 0.47, P < 0.005; females: r = 0.52, P < 0.001). In contrast, in apoEKO mice there were no significant dietary effects on atherosclerosis in either sex. Compared with the SFA diet, the CARB diet significantly decreased VLDL-C in males and the MUFA, PUFA, and CARB diets decreased VLDL-C and the CARB diet decreased LDL-C in females. In summary, in LDLRKO mice the replacement of dietary SFA by either MUFA or CARB causes a proportionate increase in both atherosclerotic lesion area and VLDL-C. There were no significant dietary effects on atherosclerotic lesion area in apoEKO mice. These results are surprising and suggest that, depending on the underlying genotype, dietary MUFA and CARB can actually increase atherosclerosis susceptibility, probably by raising VLDL-C levels through a non-LDL receptor, apoE-dependent pathway. PMID:11606787

Compared with saturated fatty acids, dietary monounsaturated fatty acids and carbohydrates increase atherosclerosis and VLDL cholesterol levels in LDL receptor-deficient, but not apolipoprotein E-deficient, mice.

PubMed

Merkel, M; Velez-Carrasco, W; Hudgins, L C; Breslow, J L

2001-11-06

Heart-healthy dietary recommendations include decreasing the intake of saturated fatty acids (SFA). However, the relative benefit of replacing SFA with monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), or carbohydrates (CARB) is still being debated. We have used two mouse models of atherosclerosis, low density lipoprotein receptor-deficient (LDLRKO) and apolipoprotein E-deficient (apoEKO) mice to measure the effects of four isocaloric diets enriched with either SFA, MUFA, PUFA, or CARB on atherosclerotic lesion area and lipoprotein levels. In LDLRKO mice, compared with the SFA diet, the MUFA and CARB diets significantly increased atherosclerosis in both sexes, but the PUFA diet had no effect. The MUFA and CARB diets also increased very low density lipoprotein-cholesterol (VLDL-C) and LDL-cholesterol (LDL-C) in males and VLDL-C levels in females. Analysis of data from LDLRKO mice on all diets showed that atherosclerotic lesion area correlated positively with VLDL-C levels (males: r = 0.47, P < 0.005; females: r = 0.52, P < 0.001). In contrast, in apoEKO mice there were no significant dietary effects on atherosclerosis in either sex. Compared with the SFA diet, the CARB diet significantly decreased VLDL-C in males and the MUFA, PUFA, and CARB diets decreased VLDL-C and the CARB diet decreased LDL-C in females. In summary, in LDLRKO mice the replacement of dietary SFA by either MUFA or CARB causes a proportionate increase in both atherosclerotic lesion area and VLDL-C. There were no significant dietary effects on atherosclerotic lesion area in apoEKO mice. These results are surprising and suggest that, depending on the underlying genotype, dietary MUFA and CARB can actually increase atherosclerosis susceptibility, probably by raising VLDL-C levels through a non-LDL receptor, apoE-dependent pathway.

Ox-LDL increases OX40L in endothelial cells through a LOX-1-dependent mechanism

PubMed Central

Dong, Q.; Xiang, R.; Zhang, D.Y.; Qin, S.

2013-01-01

Oxidative low-density lipoprotein (Ox-LDL) is a key risk factor for the development of atherosclerosis, and it can stimulate the expression of a variety of inflammatory signals. As a new and highly sensitive inflammation index, OX40L may be a key to understanding the mechanisms that regulate interactions between cells within the vessel wall and inflammatory mediators during the development of atherosclerosis. To investigate whether Ox-LDL regulates OX40L expression through an oxidized LDL-1 receptor (LOX-1)-mediated mechanism, we investigated the effect of different concentrations of Ox-LDL (50, 100, 150 µg/mL) on endothelial cell proliferation and apoptosis. Stimulation with Ox-LDL increased OX40L protein 1.44-fold and mRNA 4.0-fold in endothelial cells, and these effects were inhibited by blocking LOX-1. These results indicate that LOX-1 plays an important role in the chronic inflammatory process in blood vessel walls. Inhibiting LOX-1 may reduce blood vessel inflammation and provide a therapeutic option to limit atherosclerosis progression. PMID:24068192

Novel Therapies for Low-Density Lipoprotein Cholesterol Reduction.

PubMed

Toth, Peter P

2016-09-15

Although many clinical trials and meta-analyses have demonstrated that lower serum low-density lipoprotein cholesterol (LDL-C) levels are associated with proportionately greater reductions in the risk of cardiovascular disease events, not all patients with hypercholesterolemia are able to attain risk-stratified LDL-C goals with statin monotherapy. Elucidation of the pathophysiology of genetic disorders of lipid metabolism (e.g., familial hypercholesterolemia) has led to the development of several novel lipid-lowering strategies, including blocking the degradation of hepatic LDL-C receptors that are important in LDL-C clearance, or the inhibition of apoprotein synthesis and lipidation. Mipomersen and lomitapide are highly efficacious new agents available for the treatment of patients with homozygous familial hypercholesterolemia. The recent introduction of PCSK9 inhibitors (alirocumab and evolocumab) have made it possible for many patients to achieve very low LDL-C concentrations (e.g., <40 mg/dl) that are usually not attainable with statin monotherapy. Ongoing clinical trials are examining the impact of very low LDL-C levels on cardiovascular disease event rates and the long-term safety of this approach. Copyright © 2016. Published by Elsevier Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koivisto, U.M.; Viikari, J.S.; Kontula, K.

Two deletions of the low-density lipoprotein (LDL) receptor gene were previously shown to account for about two thirds of all mutations causing familial hypercholesterolemia (FH) in Finland. We screened the DNA samples from a cohort representing the remaining 30% of Finnish heterozygous FH patients by amplifying all the 18 exons of the receptor gene by PCR and searching for DNA variations with the SSCP technique. Ten novel mutations were identified, comprising two nonsense and seven missense mutations as well as one frameshift mutation caused by a 13-bp deletion. A single nucleotide change, substituting adenine for guanidine at position 2533 andmore » resulting in an amino acid change of glycine to aspartic acid at codon 823, was found in DNA samples from 14 unrelated FH probands. This mutation (FH-Turku) affects the sequence encoding the putative basolateral sorting signal of the LDL receptor protein; however, the exact functional consequences of this mutation are yet to be examined. The FH-Turku gene and another point mutation (Leu380{r_arrow}His or FH-Pori) together account for {approximately}8% of the FH-causing genes in Finland and are particularly common among FH patients from the southwestern part of the country (combined, 30%). Primer-introduced restriction analysis was applied for convenient assay of the FH-Turku and FH-Pori point mutations. In conclusion, this paper demonstrates the unique genetic background of FH in Finland and describes a commonly occurring FH gene with a missense mutation closest to the C terminus thus far reported. 32 refs., 5 figs., 2 tabs.« less

Familial hypercholesterolemia

MedlinePlus

Type II hyperlipoproteinemia; Hypercholesterolemic xanthomatosis; Low density lipoprotein receptor mutation ... defect makes the body unable to remove low density lipoprotein (LDL, or bad) cholesterol from the blood. ...

Streptococcal serum opacity factor promotes cholesterol ester metabolism and bile acid secretion in vitro and in vivo.

PubMed

Gillard, Baiba K; Rodriguez, Perla J; Fields, David W; Raya, Joe L; Lagor, William R; Rosales, Corina; Courtney, Harry S; Gotto, Antonio M; Pownall, Henry J

2016-03-01

Plasma high density lipoprotein-cholesterol (HDL-C) concentrations negatively correlate with atherosclerotic cardiovascular disease. HDL is thought to have several atheroprotective functions, which are likely distinct from the epidemiological inverse relationship between HDL-C levels and risk. Specifically, strategies that reduce HDL-C while promoting reverse cholesterol transport (RCT) may have therapeutic value. The major product of the serum opacity factor (SOF) reaction versus HDL is a cholesteryl ester (CE)-rich microemulsion (CERM), which contains apo E and the CE of ~400,000 HDL particles. Huh7 hepatocytes take up CE faster when delivered as CERM than as HDL, in part via the LDL-receptor (LDLR). Here we compared the final RCT step, hepatic uptake and subsequent intracellular processing to cholesterol and bile salts for radiolabeled HDL-, CERM- and LDL-CE by Huh7 cells and in vivo in C57BL/6J mice. In Huh7 cells, uptake from LDL was greater than from CERM (2-4X) and HDL (5-10X). Halftimes for [(14)C]CE hydrolysis were 3.0±0.2, 4.4±0.6 and 5.4±0.7h respectively for HDL, CERM and LDL-CE. The fraction of sterols secreted as bile acids was ~50% by 8h for all three particles. HDL, CERM and LDL-CE metabolism in mice showed efficient plasma clearance of CERM-CE, liver uptake and metabolism, and secretion as bile acids into the gall bladder. This work supports the therapeutic potential of the SOF reaction, which diverts HDL-CE to the LDLR, thereby increasing hepatic CE uptake, and sterol disposal as bile acids. Copyright © 2015 Elsevier B.V. All rights reserved.

Impact of Cyanidin-3-Glucoside on Glycated LDL-Induced NADPH Oxidase Activation, Mitochondrial Dysfunction and Cell Viability in Cultured Vascular Endothelial Cells

PubMed Central

Xie, Xueping; Zhao, Ruozhi; Shen, Garry X.

2012-01-01

Elevated levels of glycated low density lipoprotein (glyLDL) are frequently detected in diabetic patients. Previous studies demonstrated that glyLDL increased the production of reactive oxygen species (ROS), activated NADPH oxidase (NOX) and suppressed mitochondrial electron transport chain (mETC) enzyme activities in vascular endothelial cells (EC). The present study examined the effects of cyanidin-3-glucoside (C3G), a type of anthocyanin abundant in dark-skinned berries, on glyLDL-induced ROS production, NOX activation and mETC enzyme activity in porcine aortic EC (PAEC). Co-treatment of C3G prevented glyLDL-induced upregulation of NOX4 and intracellular superoxide production in EC. C3G normalized glyLDL-induced inhibition on the enzyme activities of mETC Complex I and III, as well as the abundances of NADH dehydrogenase 1 in Complex I and cytochrome b in Complex III in EC. Blocking antibody for the receptor of advanced glycation end products (RAGE) prevented glyLDL-induced changes in NOX and mETC enzymes. Combination of C3G and RAGE antibody did not significantly enhance glyLDL-induced inhibition of NOX or mETC enzymes. C3G reduced glyLDL-induced RAGE expression with the presence of RAGE antibody. C3G prevented prolonged incubation with the glyLDL-induced decrease in cell viability and the imbalance between key regulators for cell viability (cleaved caspase 3 and B cell Lyphoma-2) in EC. The findings suggest that RAGE plays an important role in glyLDL-induced oxidative stress in vascular EC. C3G may prevent glyLDL-induced NOX activation, the impairment of mETC enzymes and cell viability in cultured vascular EC. PMID:23443099

Impact of cyanidin-3-glucoside on glycated LDL-induced NADPH oxidase activation, mitochondrial dysfunction and cell viability in cultured vascular endothelial cells.

PubMed

Xie, Xueping; Zhao, Ruozhi; Shen, Garry X

2012-11-27

Elevated levels of glycated low density lipoprotein (glyLDL) are frequently detected in diabetic patients. Previous studies demonstrated that glyLDL increased the production of reactive oxygen species (ROS), activated NADPH oxidase (NOX) and suppressed mitochondrial electron transport chain (mETC) enzyme activities in vascular endothelial cells (EC). The present study examined the effects of cyanidin-3-glucoside (C3G), a type of anthocyanin abundant in dark-skinned berries, on glyLDL-induced ROS production, NOX activation and mETC enzyme activity in porcine aortic EC (PAEC). Co-treatment of C3G prevented glyLDL-induced upregulation of NOX4 and intracellular superoxide production in EC. C3G normalized glyLDL-induced inhibition on the enzyme activities of mETC Complex I and III, as well as the abundances of NADH dehydrogenase 1 in Complex I and cytochrome b in Complex III in EC. Blocking antibody for the receptor of advanced glycation end products (RAGE) prevented glyLDL-induced changes in NOX and mETC enzymes. Combination of C3G and RAGE antibody did not significantly enhance glyLDL-induced inhibition of NOX or mETC enzymes. C3G reduced glyLDL-induced RAGE expression with the presence of RAGE antibody. C3G prevented prolonged incubation with the glyLDL-induced decrease in cell viability and the imbalance between key regulators for cell viability (cleaved caspase 3 and B cell Lyphoma-2) in EC. The findings suggest that RAGE plays an important role in glyLDL-induced oxidative stress in vascular EC. C3G may prevent glyLDL-induced NOX activation, the impairment of mETC enzymes and cell viability in cultured vascular EC.

Prevention of oxLDL uptake leads to decreased atherosclerosis in hematopoietic NPC1-deficient Ldlr-/- mice.

PubMed

Jeurissen, Mike L J; Walenbergh, Sofie M A; Houben, Tom; Gijbels, Marion J J; Li, Jieyi; Hendrikx, Tim; Oligschlaeger, Yvonne; van Gorp, Patrick J; Binder, Christoph J; Donners, Marjo M P C; Shiri-Sverdlov, Ronit

2016-12-01

Atherosclerosis is a chronic inflammatory disease of medium and large vessels and is typically characterized by the predominant accumulation of low-density lipoprotein (LDL)-cholesterol inside macrophages that reside in the vessel walls. Previous studies clearly demonstrated an association specifically between the oxidized type of LDL (oxLDL) and atherosclerotic lesion formation. Further observations revealed that these atherosclerotic lesions displayed enlarged, lipid-loaded lysosomes. By increasing natural antibodies against oxLDL, pneumococcal vaccination has been shown to reduce atherosclerosis in LDL receptor knockout (Ldlr -/- ) mice. Relevantly, loss of the lysosomal membrane protein Niemann-Pick Type C1 (NPC1) led to lysosomal accumulation of various lipids and promoted atherosclerosis. Yet, the importance of lysosomal oxLDL accumulation inside macrophages, compared to non-modified LDL, in atherosclerosis has never been established. By transplanting NPC1 bone marrow into lethally irradiated Ldlr -/- mice, a hematopoietic mouse model for lysosomal cholesterol accumulation was created. Through injections with heat-inactivated pneumococci, we aimed to demonstrate the specific contribution of lysosomal oxLDL accumulation inside macrophages in atherosclerosis development. While there were no differences in plaque morphology, a reduction in plaque size and plaque inflammation was found in immunized NPC1 mut -transplanted mice, compared to non-immunized NPC1 mut -transplanted mice. Lysosomal oxLDL accumulation within macrophages contributes to murine atherosclerosis. Future intervention strategies should focus specifically on preventing oxLDL, unlike non-modified LDL, from being internalized into lysosomes. Such an intervention can have an additive effect to current existing treatments against atherosclerosis. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Pleiotropic Effect of Lipoprotein-Apheresis on the Soluble Form of Activated Leukocyte Cell Adhesion Molecule (sALCAM) in Familial Hypercholesterolaemia.

PubMed

von Bauer, Rüdiger; Oikonomou, Dimitrios; Sulaj, Alba; Kopf, Stefan; Fleming, Thomas; Rudofsky, Gottfried; Nawroth, Peter

2018-06-11

Atherosclerosis is an inflammatory disorder in which several converging immune responses modulate and induce lipid accumulation in macrophages. Activated leukocyte cell adhesion molecule (ALCAM) has been described as a structural homologue of HDL-receptor and functions as a pattern recognition receptor (PRR), while its soluble form sALCAM is involved in ALCAM-dependent and -independent immune mechanisms. The aim of this study was to investigate the effect of aggressive removal of low density lipoprotein-cholesterol (LDL-C) and lipoprotein(a) (Lp [a]) by lipoprotein-apheresis (LA) on sALCAM and blood viscosity as well as to evaluate its association with lipoproteins and serum markers of inflammation. © Georg Thieme Verlag KG Stuttgart · New York.

Linkage study of the low-density lipoprotein-receptor gene and cholesterol levels in an Afrikaner family. Quantitative genetics and identification of a minor founder effect.

PubMed

Brink, P A; Brink, L T; Torrington, M; Bester, A J

1990-03-17

Overlap of clinical and biochemical characteristics between hypercholesterolaemia in members of the general population and familial hypercholesterolaemic (FH) individuals may lead to misdiagnosis. Quantitative analysis of family data may circumvent this problem. A way of looking for an association between plasma cholesterol levels and restriction fragment length polymorphism markers (RFLP) on the low-density lipoprotein (LDL) receptor gene by using reference cholesterol distributions was explored. Linkage, with a logarithm of the odds (LOD) score of 6.8 at theta 0, was detected between cholesterol levels and the LDL receptor in an extended Afrikaner family. Two RFLP-haplotypes, one previously found in a majority of Afrikaner FH homozygotes, and a second, Stu I-, BstE II+, Pvu II+, Nco I+, were associated with high cholesterol levels in this pedigree.

Proteomic Plasma Membrane Profiling Reveals an Essential Role for gp96 in the Cell Surface Expression of LDLR Family Members, Including the LDL Receptor and LRP6

PubMed Central

2012-01-01

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96. PMID:22292497

Proteomic plasma membrane profiling reveals an essential role for gp96 in the cell surface expression of LDLR family members, including the LDL receptor and LRP6.

PubMed

Weekes, Michael P; Antrobus, Robin; Talbot, Suzanne; Hör, Simon; Simecek, Nikol; Smith, Duncan L; Bloor, Stuart; Randow, Felix; Lehner, Paul J

2012-03-02

The endoplasmic reticulum chaperone gp96 is required for the cell surface expression of a narrow range of proteins, including toll-like receptors (TLRs) and integrins. To identify a more comprehensive repertoire of proteins whose cell surface expression is dependent on gp96, we developed plasma membrane profiling (PMP), a technique that combines SILAC labeling with selective cell surface aminooxy-biotinylation. This approach allowed us to compare the relative abundance of plasma membrane (PM) proteins on gp96-deficient versus gp96-reconstituted murine pre-B cells. Analysis of unfractionated tryptic peptides initially identified 113 PM proteins, which extended to 706 PM proteins using peptide prefractionation. We confirmed a requirement for gp96 in the cell surface expression of certain TLRs and integrins and found a marked decrease in cell surface expression of four members of the extended LDL receptor family (LDLR, LRP6, Sorl1 and LRP8) in the absence of gp96. Other novel gp96 client proteins included CD180/Ly86, important in the B-cell response to lipopolysaccharide. We highlight common structural motifs in these client proteins that may be recognized by gp96, including the beta-propeller and leucine-rich repeat. This study therefore identifies the extended LDL receptor family as an important new family of proteins whose cell surface expression is regulated by gp96.

Detection of atherosclerotic lesions and intimal macrophages using CD36-targeted nanovesicles.

PubMed

Nie, Shufang; Zhang, Jia; Martinez-Zaguilan, Raul; Sennoune, Souad; Hossen, Md Nazir; Lichtenstein, Alice H; Cao, Jun; Meyerrose, Gary E; Paone, Ralph; Soontrapa, Suthipong; Fan, Zhaoyang; Wang, Shu

2015-12-28

Current approaches to the diagnosis and therapy of atherosclerosis cannot target lesion-determinant cells in the artery wall. Intimal macrophage infiltration promotes atherosclerotic lesion development by facilitating the accumulation of oxidized low-density lipoproteins (oxLDL) and increasing inflammatory responses. The presence of these cells is positively associated with lesion progression, severity and destabilization. Hence, they are an important diagnostic and therapeutic target. The objective of this study was to noninvasively assess the distribution and accumulation of intimal macrophages using CD36-targeted nanovesicles. Soy phosphatidylcholine was used to synthesize liposome-like nanovesicles. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine was incorporated on their surface to target the CD36 receptor. All in vitro data demonstrate that these targeted nanovesicles had a high binding affinity for the oxLDL binding site of the CD36 receptor and participated in CD36-mediated recognition and uptake of nanovesicles by macrophages. Intravenous administration into LDL receptor null mice of targeted compared to non-targeted nanovesicles resulted in higher uptake in aortic lesions. The nanovesicles co-localized with macrophages and their CD36 receptors in aortic lesions. This molecular target approach may facilitate the in vivo noninvasive imaging of atherosclerotic lesions in terms of intimal macrophage accumulation and distribution and disclose lesion features related to inflammation and possibly vulnerability thereby facilitate early lesion detection and targeted delivery of therapeutic compounds to intimal macrophages. Copyright © 2015 Elsevier B.V. All rights reserved.

Regulation of low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase expression by Zingiber officinale in the liver of high-fat diet-fed rats.

PubMed

Nammi, Srinivas; Kim, Moon S; Gavande, Navnath S; Li, George Q; Roufogalis, Basil D

2010-05-01

Zingiber officinale has been used to control lipid disorders and reported to possess remarkable cholesterol-lowering activity in experimental hyperlipidaemia. In the present study, the effect of a characterized and standardized extract of Zingiber officinale on the hepatic lipid levels as well as on the hepatic mRNA and protein expression of low-density lipoprotein (LDL) receptor and 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase was investigated in a high-fat diet-fed rat model. Rats were treated with an ethanol extract of Zingiber officinale (400 mg/kg) extract along with a high-fat diet for 6 weeks. The extract of Zingiber officinale significantly decreased hepatic triglyceride and tended to decrease hepatic cholesterol levels when administered over 6 weeks to the rats fed a high-fat diet. We found that in parallel, the extract up-regulated both LDL receptor mRNA and protein level and down-regulated HMG-CoA reductase protein expression in the liver of these rats. The metabolic control of body lipid homeostasis is in part due to enhanced cholesterol biosynthesis and reduced expression of LDL receptor sites following long-term consumption of high-fat diets. The present results show restoration of transcriptional and post-transcriptional changes in low-density lipoprotein and HMG CoA reductase by Zingiber officinale administration with a high-fat diet and provide a rational explanation for the effect of ginger in the treatment of hyperlipidaemia.

Hypocholesterolemic effect of stilbenes containing extract-fraction from Cajanus cajan L. on diet-induced hypercholesterolemia in mice.

PubMed

Luo, Qing-Feng; Sun, Lan; Si, Jian-Yong; Chen, Di-Hua

2008-11-01

Cajanus cajan (L) is a natural plant which contains a lot of potential active components. In the present study, we identified the effects of the stilbenes containing extract-fraction from Cajanus cajan L (sECC) on diet-induced (for 4 weeks) hypercholesterolemia in Kunming mice. All experimental mice were divided into 5 groups: control group, model group, sECC-treated with 200 or 100 mg/kg/day, and simvastatin group. The effects of sECC were investigated by monitoring serum and liver lipid profile (cholesterol homeostasis and triglyceride) as well as serum superoxide dismutase activity in those mice. To further explore the mechanism of sECC, hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase), cholesterol 7α-hydroxylase (CYP7A1), and low density lipoprotein receptor (LDL receptor) expressions in cholesterol homeostasis were analyzed by reverse transcription PCR. After 4 weeks pretreatment, compared with model group, the increased serum and hepatic total cholesterol were markedly attenuated by sECC (200 mg/kg) by 31.4% and 22.7% (p<0.01), respectively, the triglyceride levels of serum and liver were also lowered by 22.98% and 14.39%, respectively. At the same time, serum LDL cholesterol decreased by 52.8% (p<0.01) accompanied with the activities of serum superoxide dismutase increased by 20.98%. Atherogenic index and body weight were also reduced markedly. The mRNA expressions of HMG-CoA reductase, CYP7A1, and LDL-receptor were significantly enhanced in the mice administered with sECC (200 mg/kg/day), whereas those expressions were suppressed by the hypercholesterolemic diet. These data indicate that sECC reduces the atherogenic properties of dietary cholesterol in mice. Its hypocholesterolemic effect may involve enhancement of the hepatic LDL-receptor and cholesterol 7alpha-hydroxylase expression levels and bile acid synthesis.

Estimation of the prevalence of familial hypercholesterolaemia in a rural Afrikaner community by direct screening for three Afrikaner founder low density lipoprotein receptor gene mutations.

PubMed

Steyn, K; Goldberg, Y P; Kotze, M J; Steyn, M; Swanepoel, A S; Fourie, J M; Coetzee, G A; Van der Westhuyzen, D R

1996-10-01

We have determined the prevalence of familial hypercholesterolaemia (FH) in a rural Afrikaner community by means of direct DNA screening for three founder-related Afrikaner low density lipoprotein (LDL) receptor gene mutations. A random sample of 1612 persons, aged 15-64 years, was selected as a subsample of 4583 subjects from an Afrikaner community living in the south-western Cape, South Africa. Participants who had a total serum cholesterol (TC) in the high TC category as defined in the consensus recommendations by the Southern African Heart Foundation, were screened for three founder-related LDL receptor gene mutations, causing FH in 90% of Afrikaners. Of the subsample, 201 participants (12.5%) had TC levels above the 80th percentile. In this group the combined prevalence of the three common Afrikaner LDL receptor gene defects (D206E, FH Afrikaner-1; V408M, FH Afrikaner-2; D154N, FH Afrikaner-3) was calculated as 1: 83. When taking into account the reported background prevalence of other FH gene defects of 1:500 in this community, their overall prevalence of FH was estimated to be 1:72. The significant differences found between the FH patients and other high risk patients with raised cholesterol levels were higher TC and LDL cholesterol levels and lower high density lipoprotein cholesterol levels in FH patients. The treatment status of the molecularly identified FH patients and other hypercholesterolaemic persons suggests that this condition is inadequately diagnosed and poorly managed in this study population. An extrapolation to the entire South African population suggests that there are about 112000 FH patients in the country who are under-diagnosed as a group and therefore not receiving the care that would help to reduce the burden of FH-associated ischaemic heart disease in South Africa.

Full-length amyloid precursor protein regulates lipoprotein metabolism and amyloid-β clearance in human astrocytes.

PubMed

Fong, Lauren K; Yang, Max M; Dos Santos Chaves, Rodrigo; Reyna, Sol M; Langness, Vanessa F; Woodruff, Grace; Roberts, Elizabeth A; Young, Jessica E; Goldstein, Lawrence S B

2018-06-01

Mounting evidence suggests that alterations in cholesterol homeostasis are involved in Alzheimer's disease (AD) pathogenesis. Amyloid precursor protein (APP) or multiple fragments generated by proteolytic processing of APP have previously been implicated in the regulation of cholesterol metabolism. However, the physiological function of APP in regulating lipoprotein homeostasis in astrocytes, which are responsible for de novo cholesterol biosynthesis and regulation in the brain, remains unclear. To address this, here we used CRISPR/Cas9 genome editing to generate isogenic APP-knockout (KO) human induced pluripotent stem cells (hiPSCs) and differentiated them into human astrocytes. We found that APP-KO astrocytes have reduced cholesterol and elevated levels of sterol regulatory element-binding protein (SREBP) target gene transcripts and proteins, which were both downstream consequences of reduced lipoprotein endocytosis. To elucidate which APP fragments regulate cholesterol homeostasis and examine whether familial AD mutations in APP affect lipoprotein metabolism, we analyzed an isogenic allelic series harboring the APP Swedish and APP V717F variants. Only astrocytes homozygous for the APP Swedish (APP Swe/Swe ) mutation, which had reduced full-length APP (FL APP) due to increased β-secretase cleavage, recapitulated the APP-KO phenotypes. Astrocytic internalization of amyloid-β (Aβ), another ligand for low-density lipoprotein (LDL) receptors, was also impaired in APP-KO and APP Swe/Swe astrocytes. Finally, impairing cleavage of FL APP through β-secretase inhibition in APP Swe/Swe astrocytes reversed the LDL and Aβ endocytosis defects. In conclusion, FL APP is involved in the endocytosis of LDL receptor ligands and required for proper cholesterol homeostasis and Aβ clearance in human astrocytes. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss.

PubMed

Graham, Lucia S; Parhami, Farhad; Tintut, Yin; Kitchen, Christina M R; Demer, Linda L; Effros, Rita B

2009-11-01

Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of receptor activator of NFkappaB ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NFkappaB pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis.

Diet, atherosclerosis, and fish oil.

PubMed

Connor, W E; Connor, S L

1990-01-01

The principal goal of dietary prevention and treatment of atherosclerotic coronary heart disease is the achievement of physiological levels of the plasma total and LDL cholesterol, triglyceride, and VLDL. These goals have been well delineated by the National Cholesterol Education Program of the National Heart, Lung and Blood Institute and the American Heart Association. Dietary treatment is first accomplished by enhancing LDL receptor activity and at the same time depressing liver synthesis of cholesterol and triglyceride. Both dietary cholesterol and saturated fat decrease LDL receptor activity and inhibit the removal of LDL from the plasma by the liver. Saturated fat decreases LDL receptor activity, especially when cholesterol is concurrently present in the diet. The total amount of dietary fat is of importance also. The greater the flux of chylomicron remnants is into the liver, the greater is the influx of cholesterol ester. In addition, factors that affect VLDL and LDL synthesis could be important. These include excessive calories (obesity), which enhance triglyceride and VLDL and hence LDL synthesis. Weight loss and omega-3 fatty acids from fish oil depress synthesis of both VLDL and triglyceride in the liver. The optimal diet for the treatment of children and adults to prevent coronary disease has the following characteristics: cholesterol (100 mg/day), total fat (20% of calories, 6% saturated with the balance from omega-3 and omega-6 polyunsaturated and monounsaturated fat), carbohydrate (65% of calories, two thirds from starch including 11 to 15 gm of soluble fiber), and protein (15% of calories). This low-fat, high-carbohydrate diet can lower the plasma cholesterol 18% to 21%. This diet is also an antithrombotic diet, thrombosis being another major consideration in preventing coronary heart disease. Dietary therapy is the mainstay of the prevention and treatment of coronary heart disease through the control of plasma lipid and lipoprotein levels. The exact place of the omega-3 fatty acids from fish and fish oil remains to be defined. However, this much seems certain. Fish provides an excellent substitute for meat in the diet. Fish is lower in fat, especially saturated fat, and contains the omega-3 fatty acids. Fish oil may have promise as a therapeutic agent in certain hyperlipidemic states, especially the chylomicronemia of type V hyperlipidemia. Fish oil has logical and well-defined antithrombotic and anti-atherosclerotic activities since it depresses thromboxane A2 production and inhibits cellular proliferation responsible for the progression of atherosclerosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Athero-inflammatory nanotherapeutics: Ferulic acid-based poly(anhydride-ester) nanoparticles attenuate foam cell formation by regulating macrophage lipogenesis and reactive oxygen species generation.

PubMed

Chmielowski, Rebecca A; Abdelhamid, Dalia S; Faig, Jonathan J; Petersen, Latrisha K; Gardner, Carol R; Uhrich, Kathryn E; Joseph, Laurie B; Moghe, Prabhas V

2017-07-15

Enhanced bioactive anti-oxidant formulations are critical for treatment of inflammatory diseases, such as atherosclerosis. A hallmark of early atherosclerosis is the uptake of oxidized low density lipoprotein (oxLDL) by macrophages, which results in foam cell and plaque formation in the arterial wall. The hypolipidemic, anti-inflammatory, and antioxidative properties of polyphenol compounds make them attractive targets for treatment of atherosclerosis. However, high concentrations of antioxidants can reverse their anti-atheroprotective properties and cause oxidative stress within the artery. Here, we designed a new class of nanoparticles with anti-oxidant polymer cores and shells comprised of scavenger receptor targeting amphiphilic macromolecules (AMs). Specifically, we designed ferulic acid-based poly(anhydride-ester) nanoparticles to counteract the uptake of high levels of oxLDL and regulate reactive oxygen species generation (ROS) in human monocyte derived macrophages (HMDMs). Compared to all compositions examined, nanoparticles with core ferulic acid-based polymers linked by diglycolic acid (PFAG) showed the greatest inhibition of oxLDL uptake. At high oxLDL concentrations, the ferulic acid diacids and polymer nanoparticles displayed similar oxLDL uptake. Treatment with the PFAG nanoparticles downregulated the expression of macrophage scavenger receptors, CD-36, MSR-1, and LOX-1 by about 20-50%, one of the causal factors for the decrease in oxLDL uptake. The PFAG nanoparticle lowered ROS production by HMDMs, which is important for maintaining macrophage growth and prevention of apoptosis. Based on these results, we propose that ferulic acid-based poly(anhydride ester) nanoparticles may offer an integrative strategy for the localized passivation of the early stages of the atheroinflammatory cascade in cardiovascular disease. Future development of anti-oxidant formulations for atherosclerosis applications is essential to deliver an efficacious dose while limiting localized concentrations of pro-oxidants. In this study, we illustrate the potential of degradable ferulic acid-based polymer nanoparticles to control macrophage foam cell formation by significantly reducing oxLDL uptake through downregulation of scavenger receptors, CD-36, MSR-1, and LOX-1. Another critical finding is the ability of the degradable ferulate-based polymer nanoparticles to lower macrophage reactive oxygen species (ROS) levels, a precursor to apoptosis and plaque escalation. The degradable ferulic acid-based polymer nanoparticles hold significant promise as a means to alter the treatment and progression of atherosclerosis. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Low density lipoprotein receptor gene Ava II polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

PubMed Central

2011-01-01

Background Several common genetic polymorphisms in the low density lipoprotein receptor (LDL-R) gene have associated with modifications of serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels, but the results are not consistent in different populations. Bai Ku Yao is a special subgroup of the Yao minority in China. The present study was undertaken to detect the association of LDL-R gene Ava Ⅱ polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations. Methods A total of 1024 subjects of Bai Ku Yao and 792 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the LDL-R gene Ava Ⅱ polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. Results The levels of serum TC, high density lipoprotein cholesterol (HDL-C), LDL-C, apolipoprotein (Apo) A1 and the ratio of ApoA1 to ApoB were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of A- and A+ alleles was 65.5% and 34.5% in Bai Ku Yao, and 80.7% and 19.3% in Han (P < 0.001); respectively. The frequency of A-A-, A-A+ and A+A+ genotypes was 42.6%, 45.9% and 11.5% in Bai Ku Yao, and 64.9%, 31.6% and 3.5% in Han (P < 0.001); respectively. There was also significant difference in the genotypic frequencies between males and females in Bai Ku Yao (P <0.05), and in the genotypic and allelic frequencies between normal LDL-C (≤ 3.20 mmol/L) and high LDL-C (>3.20 mmol/L) subgroups in Bai Ku Yao (P < 0.05 for each) and between males and females in Han (P < 0.05 for each). The levels of LDL-C in males and TC and HDL-C in females were different among the three genotypes (P < 0.05 for all) in Bai Ku Yao, whereas the levels of HDL-C in males and HDL-C and ApoA1 in females were different among the three genotypes (P < 0.05-0.001) in Han. The subjects with A+A+ genotype had higher serum LDL-C, TC, HDL-C or ApoA1 levels than the subjects with A-A+ and A-A- genotypes. Spearman rank correlation analysis revealed that the levels of LDL-C in Bai Ku Yao and HDL-C in Han were correlated with genotypes (P < 0.05 and P < 0.01; respectively). Conclusions The association of LDL-R gene Ava Ⅱ polymorphism and serum lipid levels is different between the Bai Ku Yao and Han populations. The discrepancy might partly result from different LDL-R gene Ava Ⅱ polymorphism or LDL-R gene-enviromental interactions. PMID:21345210

Kimchi methanol extract and the kimchi active compound, 3'-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid, downregulate CD36 in THP-1 macrophages stimulated by oxLDL.

PubMed

Yun, Ye-Rang; Kim, Hyun-Ju; Song, Yeong-Ok

2014-08-01

Macrophage foam cell formation by oxidized low-density lipoprotein (oxLDL) is a key step in the progression of atherosclerosis, which is involved in cholesterol influx and efflux in macrophages mediated by related proteins such as peroxisome proliferator-activated receptor γ (PPARγ), CD36, PPARα, liver-X receptor α (LXRα), and ATP-binding cassette transporter A1 (ABCA1). The aim of this study was to investigate the beneficial effects of kimchi methanol extract (KME) and a kimchi active compound, 3-(4'-hydroxyl-3',5'-dimethoxyphenyl)propionic acid (HDMPPA) on cholesterol flux in THP-1-derived macrophages treated with oxLDL. The effects of KME and HDMPPA on cell viability and lipid peroxidation were determined. Furthermore, the protein expression of PPARγ, CD36, PPARα, LXRα, and ABCA1 was examined. OxLDL strongly induced cell death and lipid peroxidation in THP-1-derived macrophages. However, KME and HDMPPA significantly improved cell viability and inhibited lipid peroxidation induced by oxLDL in THP-1-derived macrophages (P<.05). Moreover, KME and HDMPPA suppressed CD36 and PPARγ expressions, both of which participate in cholesterol influx. In contrast, KME and HDMPPA augmented LXRα, PPARα, and ABCA1 expression, which are associated with cholesterol efflux. Consequently, KME and HDMPPA suppressed lipid accumulation. These results indicate that KME and HDMPPA may inhibit lipid accumulation, in part, by regulating cholesterol influx- and efflux-related proteins. These findings will thus be useful for future prevention strategies against atherosclerosis.

Elevated Levels of LDL-C are Associated With ApoE4 but Not With the rs688 Polymorphism in the LDLR Gene.

PubMed

Cahua-Pablo, Gabriel; Cruz, Miguel; Moral-Hernández, Oscar Del; Leyva-Vázquez, Marco A; Antúnez-Ortiz, Diana L; Cahua-Pablo, José A; Alarcón-Romero, Luz Del Carmen; Ortuño-Pineda, Carlos; Moreno-Godínez, Ma Elena; Hernández-Sotelo, Daniel; Flores-Alfaro, Eugenia

2016-07-01

Apolipoprotein E (ApoE) 4 isoform has been associated with elevated levels of cholesterol, low-density lipoprotein cholesterol (LDL-C), and triglycerides (TGs), meanwhile several polymorphisms in the LDL receptor (LDLR) gene have been associated with increased levels of total cholesterol and LDL-C. We studied 400 women from Southwest Mexico. Anthropometric features and biochemical profile were evaluated, and genotyping of single nucleotide polymorphisms rs429358 and rs7412 in the APOE gene and rs688 in the LDLR gene was determined by TaqMan assays. We found significant association between LDL-C (odds ratio [OR] = 3.3, 95% confidence interval [CI]: 1.9-5.7) and marginal association with TG (OR = 1.7, 95% CI: 1.0-2.9) of atherogenic risk in women carriers of the ApoE4 isoform compared to ApoE3. The TT genotype of rs688 in the LDLR gene was not found to be associated with elevated levels of total cholesterol or LDL-C. Our results show that carrier women of the ApoE4 isoform are more likely to have elevated levels of LDL-C and therefore increased risk of developing atherosclerosis. © The Author(s) 2015.

Structural changes induced by acidic pH in human apolipoprotein B-100

PubMed Central

Fernández-Higuero, José A.; Benito-Vicente, Asier; Etxebarria, Aitor; Milicua, José Carlos G.; Ostolaza, Helena; Arrondo, José L. R.; Martín, Cesar

2016-01-01

Acidification in the endosome causes lipoprotein release by promoting a conformational change in the LDLR allowing its recycling and degradation of LDL. Notwithstanding conformational changes occurring in the LDLR have expanded considerably, structural changes occurring in LDL particles have not been fully explored yet. The objectives of the present work were to study structural changes occurring in apoB100 by infrared spectroscopy (IR) and also LDL size and morphology by dynamic light scattering (DLS) and electron microscopy (EM) at both pH 7.4 and 5.0. We determined by IR that pH acidification from 7.4 to 5.0, resembling that occurring within endosomal environment, induces a huge reversible structural rearrangement of apoB100 that is characterized by a reduction of beta-sheet content in favor of alpha-helix structures. Data obtained from DLS and EM showed no appreciable differences in size and morphology of LDL. These structural changes observed in apoB100, which are likely implied in particle release from lipoprotein receptor, also compromise the apoprotein stability what would facilitate LDL degradation. In conclusion, the obtained results reveal a more dynamic picture of the LDL/LDLR dissociation process than previously perceived and provide new structural insights into LDL/LDLR interactions than can occur at endosomal low-pH milieu. PMID:27824107

Food restriction by intermittent fasting induces diabetes and obesity and aggravates spontaneous atherosclerosis development in hypercholesterolaemic mice.

PubMed

Dorighello, Gabriel G; Rovani, Juliana C; Luhman, Christopher J F; Paim, Bruno A; Raposo, Helena F; Vercesi, Anibal E; Oliveira, Helena C F

2014-03-28

Different regimens of food restriction have been associated with protection against obesity, diabetes and CVD. In the present study, we hypothesised that food restriction would bring benefits to atherosclerosis- and diabetes-prone hypercholesterolaemic LDL-receptor knockout mice. For this purpose, 2-month-old mice were submitted to an intermittent fasting (IF) regimen (fasting every other day) over a 3-month period, which resulted in an overall 20 % reduction in food intake. Contrary to our expectation, epididymal and carcass fat depots and adipocyte size were significantly enlarged by 15, 72 and 68 %, respectively, in the IF mice compared with the ad libitum-fed mice. Accordingly, plasma levels of leptin were 50 % higher in the IF mice than in the ad libitum-fed mice. In addition, the IF mice showed increased plasma levels of total cholesterol (37 %), VLDL-cholesterol (195 %) and LDL-cholesterol (50 %). As expected, in wild-type mice, the IF regimen decreased plasma cholesterol levels and epididymal fat mass. Glucose homeostasis was also disturbed by the IF regimen in LDL-receptor knockout mice. Elevated levels of glycaemia (40 %), insulinaemia (50 %), glucose intolerance and insulin resistance were observed in the IF mice. Systemic inflammatory markers, TNF-α and C-reactive protein, were significantly increased and spontaneous atherosclerosis development were markedly increased (3-fold) in the IF mice. In conclusion, the IF regimen induced obesity and diabetes and worsened the development of spontaneous atherosclerosis in LDL-receptor knockout mice. Although being efficient in a wild-type background, this type of food restriction is not beneficial in the context of genetic hypercholesterolaemia.

Lysophosphatidic acid directly induces macrophage-derived foam cell formation by blocking the expression of SRBI.

PubMed

Chen, Linmu; Zhang, Jun; Deng, Xiao; Liu, Yan; Yang, Xi; Wu, Qiong; Yu, Chao

2017-09-23

The leading cause of morbidity and mortality is the result of cardiovascular disease, mainly atherosclerosis. The formation of macrophage foam cells by ingesting ox-LDL and focal retention in the subendothelial space are the hallmarks of the early atherosclerotic lesion. Lysophosphatidic acid (LPA), which is a low-molecular weight lysophospholipid enriched in oxidized LDL, exerts a range of effects on the cardiovascular system. Previous reports show that LPA increases the uptake of ox-LDL to promote the formation of foam cells. However, as the most active component of ox-LDL, there is no report showing whether LPA directly affects foam cell formation. The aim of this study was to investigate the effects of LPA on foam cell formation, as well as to elucidate the underlying mechanism. Oil red O staining and a Cholesterol/cholesteryl ester quantitation assay were used to evaluate foam cell formation in Raw264.7 macrophage cells. We utilized a Western blot and RT-PCR to investigate the relationship between LPA receptors and lipid transport related proteins. We found that LPA promoted foam cell formation, using 200 μM for 24 h. Meanwhile, the expression of the Scavenger receptor BI (SRBI), which promotes the efflux of free cholesterol, was decreased. Furthermore, the LPA 1/3 receptor antagonist Ki16425 significantly abolished the LPA effects, indicating that LPA 1/3 was involved in the foam cell formation and SRBI expression induced by LPA. Additionally, the LPA-induced foam cell formation was blocked with an AKT inhibitor. Our results suggest that LPA-enhanced foam cell formation is mediated by LPA 1/3 -AKT activation and subsequent SRBI expression. Copyright © 2017. Published by Elsevier Inc.

Maternal inheritance does not predict cholesterol levels in children with familial hypercholesterolemia.

PubMed

Narverud, Ingunn; van Lennep, Jeanine Roeters; Christensen, Jacob J; Versmissen, Jorie; Gran, Jon Michael; Iversen, Per Ole; Aukrust, Pål; Halvorsen, Bente; Ueland, Thor; Ulven, Stine M; Ose, Leiv; Veierød, Marit B; Sijbrands, Eric; Retterstøl, Kjetil; Holven, Kirsten B

2015-11-01

Pregnancy exerts metabolic changes with increasing levels of total cholesterol and triglycerides as prominent features. Maternal hypercholesterolemia may thus contribute to an unfavorable in utero environment potentially influencing the susceptibility of adult cardiovascular disease in the offspring. We investigated the impact of maternal familial hypercholesterolemia (FH) on pre-treatment plasma lipids and C-reactive protein (CRP) levels in non-statin treated FH children. Children with FH (n = 1063) aged between 0 and 19 years were included. Of these, 500 had inherited FH maternally, 563 paternally and 97.6% had a verified FH mutation. Information about inheritance, mutation type and pretreatment levels of blood lipids and CRP was retrieved from the medical records. There were no significant differences in the plasma levels of lipids and C-reactive protein (CRP) in children with maternal FH compared with children with paternal FH, (0.12 ≤ P ≤ 0.90). Independent of which parent transmitted FH, children with LDL receptor negative mutations had significantly higher levels of total and LDL cholesterol and Apolipoprotein (Apo) B, and lower levels of HDL cholesterol and ApoA1, compared with children with other LDL receptor mutations (P < 0.001). Maternal inheritance of FH was not associated with detectable long-term effects in the offspring's phenotype measured by adverse lipid profiles and increased CRP levels, whereas a LDL receptor negative mutation was associated with an unfavorably phenotype in FH offspring. Our findings do not support the fetal origin of adulthood disease hypothesis, while at the same time not excluding the hypothesis since other pathways leading to atherosclerosis may be involved. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Heart Disease in Women: Unappreciated Challenges, GPER as a New Target.

PubMed

Feldman, Ross D

2016-05-18

Heart disease in women remains underappreciated, underdiagnosed and undertreated. Further, although we are starting to understand some of the social and behavioral determinants for this, the biological basis for the increased rate of rise in atherosclerosis risk in women after menopause remains very poorly understand. In this review we will outline the scope of the clinical issues related to heart disease in women, the emerging findings regarding the biological basis underlying the increased prevalence of atherosclerotic risk factors in postmenopausal women (vs. men) and the role of the G protein-coupled estrogen receptor (GPER) and its genetic regulation as a determinant of these sex-specific risks. GPER is a recently appreciated GPCR that mediates the rapid effects of estrogen and aldosterone. Recent studies have identified that GPER activation regulates both blood pressure. We have shown that regulation of GPER function via expression of a hypofunctional GPER genetic variant is an important determinant of blood pressure and risk of hypertension in women. Further, our most recent studies have identified that GPER activation is an important regulator of low density lipoprotein (LDL) receptor metabolism and that expression of the hypofunctional GPER genetic variant is an important contributor to the development of hypercholesterolemia in women. GPER appears to be an important determinant of the two major risk factors for coronary artery disease-blood pressure and LDL cholesterol. Further, the importance of this mechanism appears to be greater in women. Thus, the appreciation of the role of GPER function as a determinant of the progression of atherosclerotic disease may be important both in our understanding of cardiometabolic function but also in opening the way to greater appreciation of the sex-specific regulation of atherosclerotic risk factors.

Detection and imaging of the reconstituted pyropheophorbide-cholesterol oleate labeled low-density lipoprotein in the HepG2 tumor

NASA Astrophysics Data System (ADS)

Blessington, Dana M.; Zhang, Zhihong; Li, Hui; Zhang, Min; Zhou, Lanlan; Glickson, Jerry D.; Zheng, Gang; Chance, Britton

2003-07-01

We utilized the nude mouse model bearing the human hepatoblastoma G2 (HepG2) tumor and B-16 Murine Melanoma tumor to study the delivery and detection of the reconstituted Pyropheophorbide Cholesterol Oleate (r-pyroCE) molecular beacon. The delivery vehicle, low-density lipoprotein (LDL), labeled with the porphyrin derivative, was employed in response of the overexpression of LDL receptors in the HepG2 tumor. The B-16 melanoma tumor was also observed in this study for its overexpression of the LDL receptors. The tumors were imaged using the 3D low temperature scanner to produce images throughout several sliced sections of each tumor. The fluorescence signal of the pyropheophorbide was detected at 720nm when excited at 670nm in the tumor tissue. The uniform distribution of the signal in the HepG2 tumor shows extravasation of the beacon from the blood vessels. The B-16 tumor did not exhibit strong fluorescent signals and successful delivery as the HepG2 tumor outside the blood vessels and into the tumor tissue.

Targeted Delivery of Drugs to Brain Tumors (LBNL Summer Lecture Series)

ScienceCinema

Forte, Trudy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Life Sciences Division; Children’s Hospital Oakland Research Inst. (CHORI), Oakland, CA (United States)

2017-12-15

Summer Lecture Series 2007: Trudy Forte of Berkeley Lab's Life Sciences Division will discuss her work developing nano-sized low-density lipoprotein (LDL) particles that can be used as a safe and effective means of delivering anticancer drugs to brain tumors, particularly glioblastoma multiforme. This is the most common malignant brain tumor in adults and one of the deadliest forms of cancer. Her research team found that the synthetic LDL particles can target and kill such tumors cells in vitro. The nanoparticles are composed of a lipid core surrounded by a peptide. The peptide contains an amino acid sequence that recognizes the LDL receptor, and the lipid core has the ability to accumulate anti-cancer drugs.

N-Succinyl-chitosan nanoparticles coupled with low-density lipoprotein for targeted osthole-loaded delivery to low-density lipoprotein receptor-rich tumors

PubMed Central

Zhang, Chun-ge; Zhu, Qiao-ling; Zhou, Yi; Liu, Yang; Chen, Wei-liang; Yuan, Zhi-Qiang; Yang, Shu-di; Zhou, Xiao-feng; Zhu, Ai-jun; Zhang, Xue-nong; Jin, Yong

2014-01-01

N-Succinyl-chitosan (NSC) was synthesized and NSC nanoparticles (NPs) with loaded osthole (Ost) (Ost/NSC-NPs) were prepared by emulsion solvent diffusion. Subsequently, low-density lipoprotein (LDL)-mediated NSC-NPs with loaded Ost (Ost/LDL-NSC-NPs) were obtained by coupling LDL with Ost/NSC-NPs through amide linkage. The average particle size of Ost/NSC-NPs was approximately 145 nm, the entrapment efficiency was 78.28%±2.06%, and the drug-loading amount was 18.09%±0.17%. The release of Ost from Ost/NSC-NPs in vitro showed a more evident sustained effect than the native material. The half maximal inhibitory concentration of Ost/LDL-NSC-NPs was only 16.23% that of the free Ost at 24 hours in HepG2 cells. Ost inhibited HepG2 cell proliferation by arresting cells in the synthesis phase of the cell cycle and by triggering apoptosis. Cellular uptake and subcellular localization in vitro and near-infrared fluorescence real-time imaging in vivo showed that Ost/LDL-NSC-NPs had high targeting efficacy. Therefore, LDL-NSC-NPs are a promising system for targeted Ost delivery to liver tumor. PMID:24966673

Homozygous autosomal dominant hypercholesterolaemia: prevalence, diagnosis, and current and future treatment perspectives.

PubMed

Sjouke, Barbara; Hovingh, G Kees; Kastelein, John J P; Stefanutti, Claudia

2015-06-01

Homozygous autosomal dominant hypercholesterolemia (hoADH) is a rare genetic disorder caused by mutations in LDL receptor, apolipoprotein B, and/or proprotein convertase subtilisin-kexin type 9. Both the genetic mutations and the clinical phenotype vary largely among individual patients, but patients with hoADH are typically characterized by extremely elevated LDL-cholesterol (LDL-C) levels, and a very high-risk for premature cardiovascular disease. Current lipid-lowering therapies include bile acid sequestrants, statins, and ezetimibe. To further decrease LDL-C levels in hoADH, lipoprotein apheresis is recommended, but this therapy is not available in all countries. Recently, the microsomal triglyceride transfer protein inhibitor lomitapide and the RNA antisense inhibitor of apolipoprotein B mipomersen were approved by the Food and Drug Administration/European Medicine Agency and the Food and Drug Administration, respectively. Several other LDL-C-lowering strategies and therapeutics targeting the HDL-C pathway are currently in the clinical stage of development. Novel therapies have been introduced for LDL-C-lowering and innovative drug candidates for HDL-C modulation for the treatment of hoADH. Here, we review the current available literature on the prevalence, diagnosis, and therapeutic strategies for hoADH.

Further LDL cholesterol lowering through targeting PCSK9 for coronary artery disease.

PubMed

Cao, Guoqing; Qian, Yue-Wei; Kowala, Mark C; Konrad, Robert J

2008-12-01

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a serine protease that belongs to the proprotein convertase family. PCSK9 is synthesized as a zymogen and its prodomain is cleaved by its own catalytic activity. The cleaved prodomain forms a protein complex with the rest of the PCSK9 carboxyl terminus within the endoplasmic reticulum and is secreted. Secreted PCSK9 has been shown to be able to reduce low-density lipoprotein receptor (LDLR) levels in vitro and in vivo. Thus PCSK9 has emerged as an important player modulating LDLR levels and plasma LDL cholesterol. Furthermore, PCSK9 deficiency leads to significantly lowered LDL cholesterol levels in humans and provides dramatic protection against coronary heart disease. We review here the current understanding of PCSK9 and its potential as a therapeutic target through which to reduce LDL cholesterol for prevention and treatment of coronary heart disease.

LDL-oxidation, serum uric acid, kidney function and pulse-wave velocity: Data from the Brisighella Heart Study cohort.

PubMed

Cicero, Arrigo F G; Kuwabara, Masanari; Johnson, Richard; Bove, Marilisa; Fogacci, Federica; Rosticci, Martina; Giovannini, Marina; D'Addato, Sergio; Borghi, Claudio

2018-06-15

Serum uric acid (SUA) and oxidized LDL (oxLDL) may be associated with arterial aging. The aim of our study was to evaluate the relationship between SUA, oxLDL and arterial stiffness in subjects with normal renal function and in patients with mild or moderate renal impairment. From the database of the 2012 Brisighella Heart Study, we compared age-matched adult, non-smoker subjects without cardiovascular disease and with normal renal function (n = 205), subjects with stage II chronic kidney disease (CKD) (n = 118) and subjects with stage III CKD (n = 94). All subjects underwent a determination of the LDL oxidative susceptibility, oxLDL levels, SUA and Pulse Wave Velocity (PWV). By univariate analysis, PWV correlated with a large number of clinical, haemodynamic and metabolic parameters, including estimated glomerular filtration rate (eGFR) in subjects with normal renal function and in those with stage II or III CKD. Stepwise multiple regression analyses showed that in the presence of normal renal function or stage II CKD, the main predictors of PWV were age, systolic blood pressure (SBP), ox-LDL, apolipoprotein B and SUA (p < 0.05), while in the presence of stage III CKD only age, SBP and apolipoprotein B remained significant (p < 0.05). Both ox-LDL and SUA independently predicts PWV only in subjects with normal or mildly reduced renal function, but not in the subjects with more compromised eGFR. This study confirms the complex relationship of SUA with cardiovascular and metabolic disease in the patient with established renal disease. Copyright © 2018 Elsevier B.V. All rights reserved.

Familial hypercholesterolemia with extensive coronary artery disease and tuberous and tendinous xanthomas: A case report and mutation analysis.

PubMed

Agirbasli, Deniz; Hyatt, Tommy; Agirbasli, Mehmet

2018-04-26

This is a case report of a 38-year-old Syrian refugee male with early-onset extensive atherosclerosis. The physical and laboratory examination were remarkable with severe xanthomas in the upper and lower extremities and with low-density lipoprotein cholesterol (LDL-C) 417 mg/dL, total cholesterol 495 mg/dL, high-density lipoprotein cholesterol 30 mg/dL, and triglycerides 242 mg/dL. LDL-C level responded poorly to the high-dose statin treatment. The genetic analysis indicated that the patient had a large homozygous deletion in LDL receptor gene including the exons 7-14. A 12-kb deletion had occurred between the 2 Alu repetitive sequences that were oriented in opposite directions, one in intron 6 and the other in intron 14. This deletion eliminated exons 7-14, which exactly corresponded to the entire exon sequence coding the epidermal growth factor precursor homology domain. This deletion in LDL receptor was previously reported. This rare case of homozygous familial hypercholesterolemia presenting with multiple large and widely distributed xanthomas implicates the need for novel treatment options in familial hypercholesterolemia patients. The case is a Syrian refugee and emphasizes the urgent need to address orphan disease in refugee populations throughout the world. Copyright © 2018 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Blueberry diet protect against atherosclerosis in apoE-deficient mice by inhibiting scavenger receptor expression

USDA-ARS?s Scientific Manuscript database

Atherosclerosis is an inflammatory process that leads to the onset of cardiovascular disease. The scavenger receptor-mediated uptake of oxLDL by macrophages leads to foam cell formation, which is an initial event in the formation of atherosclerotic fatty streak lesions. In this report, the mechanism...

Inhibition of lysophosphatidic acid receptors 1 and 3 attenuates atherosclerosis development in LDL-receptor deficient mice.

PubMed

Kritikou, Eva; van Puijvelde, Gijs H M; van der Heijden, Thomas; van Santbrink, Peter J; Swart, Maarten; Schaftenaar, Frank H; Kröner, Mara J; Kuiper, Johan; Bot, Ilze

2016-11-24

Lysophosphatidic acid (LPA) is a natural lysophospholipid present at high concentrations within lipid-rich atherosclerotic plaques. Upon local accumulation in the damaged vessels, LPA can act as a potent activator for various types of immune cells through its specific membrane receptors LPA 1/3. LPA elicits chemotactic, pro-inflammatory and apoptotic effects that lead to atherosclerotic plaque progression. In this study we aimed to inhibit LPA signaling by means of LPA 1/3 antagonism using the small molecule Ki16425. We show that LPA 1/3 inhibition significantly impaired atherosclerosis progression. Treatment with Ki16425 also resulted in reduced CCL2 production and secretion, which led to less monocyte and neutrophil infiltration. Furthermore, we provide evidence that LPA 1/3 blockade enhanced the percentage of non-inflammatory, Ly6C low monocytes and CD4 + CD25 + FoxP3 + T-regulatory cells. Finally, we demonstrate that LPA 1/3 antagonism mildly reduced plasma LDL cholesterol levels. Therefore, pharmacological inhibition of LPA 1/3 receptors may prove a promising approach to diminish atherosclerosis development.

Liver Histology During Mipomersen Therapy for Severe Hypercholesterolemia

PubMed Central

Hashemi, Nikroo; Odze, Robert D.; McGowan, Mary P.; Santos, Raul D.; Stroes, Erik S.G.; Cohen, David E.

2014-01-01

Background Mipomersen is an antisense oligonucleotide that inhibits apolipoprotein (apo) B synthesis and lowers plasma low density lipoprotein (LDL) cholesterol even in the absence of LDL receptor function, presumably due to the inhibition of hepatic production of triglyceride-rich very low density lipoprotein (VLDL) particles. By virtue of this mechanism, mipomersen therapy commonly results in the development of hepatic steatosis. Because this is frequently accompanied by alanine aminotransferase (ALT) elevations, concern has arisen that mipomersen could promote the development of steatohepatitis, which could in turn lead to fibrosis and cirrhosis over time. Objective The objective of this study was to assess the liver biopsy findings in patients treated with mipomersen. Methods We describe 7 patients who underwent liver biopsy during the mipomersen clinical development programs. Liver biopsies were reviewed by a single, blinded pathologist. Results The histopathological features were characterized by simple steatosis, without significant inflammation or fibrosis. Conclusion These findings suggest that hepatic steatosis due to mipomersen is distinct from non-alcoholic steatohepatitis. PMID:25499943

Common low-density lipoprotein receptor p.G116S variant has a large effect on plasma low-density lipoprotein cholesterol in circumpolar inuit populations.

PubMed

Dubé, Joseph B; Wang, Jian; Cao, Henian; McIntyre, Adam D; Johansen, Christopher T; Hopkins, Scarlett E; Stringer, Randa; Hosseinzadeh, Siyavash; Kennedy, Brooke A; Ban, Matthew R; Young, T Kue; Connelly, Philip W; Dewailly, Eric; Bjerregaard, Peter; Boyer, Bert B; Hegele, Robert A

2015-02-01

Inuit are considered to be vulnerable to cardiovascular disease because their lifestyles are becoming more Westernized. During sequence analysis of Inuit individuals at extremes of lipid traits, we identified 2 nonsynonymous variants in low-density lipoprotein receptor (LDLR), namely p.G116S and p.R730W. Genotyping these variants in 3324 Inuit from Alaska, Canada, and Greenland showed they were common, with allele frequencies 10% to 15%. Only p.G116S was associated with dyslipidemia: the increase in LDL cholesterol was 0.54 mmol/L (20.9 mg/dL) per allele (P=5.6×10(-49)), which was >3× larger than the largest effect sizes seen with other common variants in other populations. Carriers of p.G116S had a 3.02-fold increased risk of hypercholesterolemia (95% confidence interval, 2.34-3.90; P=1.7×10(-17)), but did not have classical familial hypercholesterolemia. In vitro, p.G116S showed 60% reduced ligand-binding activity compared with wild-type receptor. In contrast, p.R730W was associated with neither LDL cholesterol level nor altered in vitro activity. LDLR p.G116S is thus unique: a common dysfunctional variant in Inuit whose large effect on LDL cholesterol may have public health implications. © 2014 American Heart Association, Inc.

Calpain Inhibition Attenuates Angiotensin II-induced Abdominal Aortic Aneurysms and Atherosclerosis in LDL Receptor Deficient Mice

PubMed Central

Subramanian, Venkateswaran; Uchida, Haruhito Adam; Ijaz, Talha; Moorleghen, Jessica J.; Howatt, Deborah A.; Balakrishnan, Anju

2011-01-01

Chronic infusion of angiotensin II (AngII) augments atherosclerosis and abdominal aortic aneurysm (AAAs) formation in hypercholesterolemic mice. AngII-induced AAAs are associated with medial macrophage accumulation and matrix metalloproteinase (MMP) activation. Inhibition of calpain, a calcium-activated neutral cysteine protease, by overexpression of its endogenous inhibitor, calpastatin, attenuates AngII-induced leukocyte infiltration, perivascular inflammation, and MMP activation in mice. The purpose of this study was to define whether pharmacological inhibition of calpain influences AngII-induced AAAs in hypercholesterolemic mice. Male LDL receptor −/− mice were fed a fat-enriched diet and administered with either vehicle or a calpain-specific inhibitor, BDA-410 (30 mg/kg/day) for 5 weeks. After 1 week of feeding, mice were infused with AngII (1,000 ng/kg/min) for 4 weeks. AngII-infusion profoundly increased aortic calpain protein and activity. BDA-410 administration had no effect on plasma cholesterol concentrations or AngII-increased systolic blood pressure. Calpain inhibition significantly attenuated AngII-induced AAA formation and atherosclerosis development. BDA-410 administration attenuated activation of MMP12, pro-inflammatory cytokines (IL-6, MCP-1) and macrophage infiltration into the aorta. BDA-410 administration significantly attenuated thioglycollate-elicited macrophage accumulation in the peritoneal cavity. We conclude that calpain inhibition using BDA-410 attenuated AngII-induced AAA formation and atherosclerosis development in LDL receptor −/− mice. PMID:21964156

OxLDL or TLR2-induced cytokine response is enhanced by oxLDL-independent novel domain on mouse CD35

USDA-ARS?s Scientific Manuscript database

OxLDL binding to CD36 is shown to result in macrophage activation and foam cell formation that have been implicated in atherosclerosis. However, CD36 has also been shown to induce inflammatory response to other ligands besides oxLDL. During the course of blocking CD36 oxLDL binding function using an...

Phthalocyanine-labeled LDL for tumor imaging and photodynamic therapy

NASA Astrophysics Data System (ADS)

Li, Hui; Marotta, Diane; Kim, Soungkyoo; Chance, Britton; Glickson, Jerry D.; Busch, Theresa M.; Zheng, Gang

2005-01-01

Current limitation of both near-infrared (NIR) tumor imaging and photodynamic therapy (PDT) is their lack of sufficient tumor-to-tissue contrast due to the relatively non-specific nature of delivering dye to the tumor, which has led to false negatives for NIR imaging and inadequate therapeutic ratio for PDT. Hence, agents targeting "cancer signatures", i.e. molecules that accumulate selectively in cancer cells, are particular attractive. One of these signatures is low-density-lipoprotein receptor (LDLR), which is overexpressed in many tumors. We have developed pyropheophorbide cholesterol oleate reconstituted LDL as a LDLR-targeting photosensitizer (PS) and demonstrated its LDLR-mediated uptake in vitro and in vivo. To improve the labeling efficiency for achieving high probe/protein ratio, tetra-t-butyl silicon phthalocyanine bearing two oleate moieties at its axial positions, (tBu)4SiPcBOA, was designed and synthesized. This compound was designed to 1) prevent the PS aggregation; 2) improve the PS solubility in non-polar solvent; and 3) maximize the PS binding to LDL phospholipid monolayer. Using this novel strategy, (tBu)4SiPcBOA was reconstituted into LDL (r-SiPcBOA-LDL) with a very high payload (500:1 molar ratio). In addition, (tBu)4SiPcBOA reconstituted acetylated LDL (r-SiPcBOA)-AcLDL with similar payload was also prepared. Since Ac-LDL cannot bind to LDLR, (r-SiPcBOA)-AcLDL can serve as the negative control to evaluate LDLR targeting specificity. For biological evaluation of these new agents, confocal microscopy and in vitro PDT protocols were performed using LDLR-overexpressing human hepatoblastoma G2 (HepG2) tumor model. These studies suggest that LDL serves as a delivery vehicle to bring large amount of the NIR/PDT agents selectively to tumor cells overexpressing LDLR.

ATVB Council Statement: Non-statin LDL-lowering Therapy and Cardiovascular Risk Reduction

PubMed Central

Hegele, Robert A.; Gidding, Samuel S.; Ginsberg, Henry N.; McPherson, Ruth; Raal, Frederick J.; Rader, Daniel J.; Robinson, Jennifer G.; Welty, Francine K.

2015-01-01

Pharmacologic reduction of low-density lipoprotein (LDL) cholesterol using statin drugs is foundational therapy to reduce cardiovascular disease (CVD) risk. Here we consider the place of non-statin therapies that also reduce LDL cholesterol in prevention of CVD. Among conventional non-statins, placebo-controlled randomized clinical trials showed that bile acid sequestrants, niacin and fibrates given as monotherapy each reduce CVD end points. From trials in which patients’ LDL cholesterol was already well-controlled on a statin, adding ezetimibe incrementally reduced CVD end points, while adding a fibrate or niacin showed no incremental benefit. Among emerging non-statins, monoclonal antibodies against proprotein convertase subtilisin kexin type 9 (PCSK9) added to a statin and given for up to 78 weeks showed preliminary evidence of reductions in CVD outcomes. While these promising early findings contributed to the recent approval of these agents in Europe and the US, much larger and longer duration outcomes studies are ongoing for definitive proof of CVD benefits. Other non-statin agents recently approved in the US include lomitapide and mipomersen, which both act via distinctive LDL-receptor independent mechanisms to substantially reduce LDL cholesterol in homozygous familial hypercholesterolemia. We also address some unanswered questions, including measuring alternative biochemical variables to LDL cholesterol, evidence for treating children with monitoring of subclinical atherosclerosis, and potential risks of extremely low LDL cholesterol. As evidence for benefit in CVD prevention accumulates, we anticipate that clinical practice will shift towards more assertive LDL-lowering treatment, using both statins and non-statins initiated earlier in appropriately selected patients. PMID:26376908

A vitamin D pathway gene-gene interaction affects low-density lipoprotein cholesterol levels.

PubMed

Grave, Nathália; Tovo-Rodrigues, Luciana; da Silveira, Janaína; Rovaris, Diego Luiz; Dal Bosco, Simone Morelo; Contini, Verônica; Genro, Júlia Pasqualini

2016-12-01

Much evidence suggests an association between vitamin D deficiency and chronic diseases such as obesity and dyslipidemia. Although genetic factors play an important role in the etiology of these diseases, only a few studies have investigated the relationship between vitamin D-related genes and anthropometric and lipid profiles. The aim of this study was to investigate the association of three vitamin D-related genes with anthropometric and lipid parameters in 542 adult individuals. We analyzed the rs2228570 polymorphism in the vitamin D receptor gene (VDR), rs2134095 in the retinoid X receptor gamma gene (RXRG) and rs7041 in the vitamin D-binding protein gene (GC). Polymorphisms were genotyped by TaqMan allelic discrimination. Gene-gene interactions were evaluated by the general linear model. The functionality of the polymorphisms was investigated using the following predictors and databases: SIFT (Sorting Intolerant from Tolerant), PolyPhen-2 (Polymorphism Phenotyping v2) and Human Splicing Finder 3. We identified a significant effect of the interaction between RXRG (rs2134095) and GC (rs7041) on low-density lipoprotein cholesterol (LDL-c) levels (P=.005). Furthermore, our in silico analysis suggested a functional role for both variants in the regulation of the gene products. Our results suggest that the vitamin D-related genes RXRG and GC affect LDL-c levels. These findings are in agreement with other studies that consistently associate vitamin D and lipid profile. Together, our results corroborate the idea that analyzing gene-gene interaction would be helpful to clarify the genetic component of lipid profile. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of soy protein foods on low-density lipoprotein oxidation and ex vivo sex hormone receptor activity--a controlled crossover trial.

PubMed

Jenkins, D J; Kendall, C W; Garsetti, M; Rosenberg-Zand, R S; Jackson, C J; Agarwal, S; Rao, A V; Diamandis, E P; Parker, T; Faulkner, D; Vuksan, V; Vidgen, E

2000-04-01

Plant-derived estrogen analogs (phytoestrogens) may confer significant health advantages including cholesterol reduction, antioxidant activity, and possibly a reduced cancer risk. However, the concern has also been raised that phytoestrogens may be endocrine disrupters and major health hazards. We therefore assessed the effects of soy foods as a rich source of isoflavonoid phytoestrogens on LDL oxidation and sex hormone receptor activity. Thirty-one hyperlipidemic subjects underwent two 1-month low-fat metabolic diets in a randomized crossover study. The major differences between the test and control diets were an increase in soy protein foods (33 g/d soy protein) providing 86 mg isoflavones/2,000 kcal/d and a doubling of the soluble fiber intake. Fasting blood samples were obtained at the start and at weeks 2 and 4, with 24-hour urine collections at the end of each phase. Soy foods increased urinary isoflavone excretion on the test diet versus the control (3.8+/-0.7 v 0.0+/-0.0 mg/d, P < .001). The test diet decreased both oxidized LDL measured as conjugated dienes in the LDL fraction (56+/-3 v 63+/-3 micromol/L, P < .001) and the ratio of conjugated dienes to LDL cholesterol (15.0+/-1.0 v 15.7+/-0.9, P = .032), even in subjects already using vitamin E supplements (400 to 800 mg/d). No significant difference was detected in ex vivo sex hormone activity between urine samples from the test and control periods. In conclusion, consumption of high-isoflavone foods was associated with reduced levels of circulating oxidized LDL even in subjects taking vitamin E, with no evidence of increased urinary estrogenic activity. Soy consumption may reduce cardiovascular disease risk without increasing the risk for hormone-dependent cancers.

Coordinate up-regulation of low-density lipoprotein receptor and cyclo-oxygenase-2 gene expression in human colorectal cells and in colorectal adenocarcinoma biopsies

NASA Technical Reports Server (NTRS)

Lum, D. F.; McQuaid, K. R.; Gilbertson, V. L.; Hughes-Fulford, M.

1999-01-01

Many colorectal cancers have high levels of cyclo-oxygenase 2 (COX-2), an enzyme that metabolizes the essential fatty acids into prostaglandins. Since the low-density lipoprotein receptor (LDLr) is involved in the uptake of essential fatty acids, we studied the effect of LDL on growth and gene regulation in colorectal cancer cells. DiFi cells grown in lipoprotein-deficient sera (LPDS) grew more slowly than cells with LDL. LDLr antibody caused significant inhibition of tumor cell growth but did not affect controls. In addition, LDL uptake did not change in the presence of excess LDL, suggesting that ldlr mRNA lacks normal feedback regulation in some colorectal cancers. Analysis of the ldlr mRNA showed that excess LDL in the medium did not cause down-regulation of the message even after 24 hr. The second portion of the study examined the mRNA expression of ldlr and its co-regulation with cox-2 in normal and tumor specimens from patients with colorectal adenocarcinomas. The ratio of tumor:paired normal mucosa of mRNA expression of ldlr and of cox-2 was measured in specimens taken during colonoscopy. ldlr and cox-2 transcripts were apparent in 11 of 11 carcinomas. There was significant coordinate up-regulation both of ldlr and of cox-2 in 6 of 11 (55%) tumors compared with normal colonic mucosa. There was no up-regulation of cox-2 without concomitant up-regulation of ldlr. These data suggest that the LDLr is abnormally regulated in some colorectal tumors and may play a role in the up-regulation of cox-2. Copyright 1999 Wiley-Liss, Inc.

Mechanism of tacrolimus-induced chronic renal fibrosis following transplantation is regulated by ox-LDL and its receptor, LOX-1

PubMed Central

Deng, Shi; Jin, Tao; Zhang, Li; Bu, Hong; Zhang, Peng

2016-01-01

Chronic renal allograft dysfunction (CRAD) is the most common cause of graft failure following renal transplantation. However, the underlying mechanisms remain to be fully elucidated. Immunosuppressants and hyperlipidemia are associated with renal fibrosis following long-term use. The present study aimed to determine the effects of tacrolimus (FK506) and lipid metabolism disorder on CRAD. In vitro and in vivo models were used for this investigation. Cells of the mouse proximal renal tubular epithelial cell strain, NRK-52E, were cultured either with oxidized low-density lipoprotein (ox-LDL), FK506, ox-LDL combined with FK506, or vehicle, respectively. Changes in cell morphology and changes in the levels of lectin-like ox-LDL receptor-1 (LOX-1), reactive oxygen species (ROS), hydrogen peroxide and fibrosis-associated genes were evaluated at 24, 48 and 72 h. In separate experiment, total of 60 Sprague-Dawley rats were divided randomly into four groups, which included a high-fat group, FK506 group, high-fat combined with FK506 group, and control group. After 2, 4 and 8 weeks, the serum lipid levels, the levels of ox-LDL, ROS, and the expression levels of transforming growth factor (TGF)-β1 and connective tissue growth factor were determined. The in vitro and in vivo models revealed that lipid metabolism disorder and FK506 caused oxidative stress and a fibrogenic response. In addition, decreased levels of LOX-1 markedly reduced the levels of TGF-β1 in the in vitro model. Taken together, FK506 and dyslipidemia were found to be associated with CRAD following transplantation. PMID:27633115

An improved method on stimulated T-lymphocytes to functionally characterize novel and known LDLR mutations[S

PubMed Central

Romano, Maria; Di Taranto, Maria Donata; Mirabelli, Peppino; D'Agostino, Maria Nicoletta; Iannuzzi, Arcangelo; Marotta, Gennaro; Gentile, Marco; Raia, Maddalena; Di Noto, Rosa; Del Vecchio, Luigi; Rubba, Paolo; Fortunato, Giuliana

2011-01-01

The main causes of familial hypercholesterolemia (FH) are mutations in LDL receptor (LDLR) gene. Functional studies are necessary to demonstrate the LDLR function impairment caused by mutations and would be useful as a diagnostic tool if they allow discrimination between FH patients and controls. In order to identify the best method to detect LDLR activity, we compared continuous Epstein-Barr virus (EBV)-transformed B-lymphocytes and mitogen stimulated T-lymphocytes. In addition, we characterized both novel and known mutations in the LDLR gene. T-lymphocytes and EBV-transformed B-lymphocytes were obtained from peripheral blood of 24 FH patients and 24 control subjects. Functional assays were performed by incubation with fluorescent LDL followed by flow cytometry analysis. Residual LDLR activity was calculated normalizing fluorescence for the mean fluorescence of controls. With stimulated T-lymphocytes we obtained a better discrimination capacity between controls and FH patients compared with EBV-transformed B-lymphocytes as demonstrated by receiver operating characteristic (ROC) curve analysis (the areas under the curve are 1.000 and 0.984 respectively; P < 0.0001 both). The characterization of LDLR activity through T-lymphocytes is more simple and faster than the use of EBV-transformed B-lymphocytes and allows a complete discrimination between controls and FH patients. Therefore the evaluation of residual LDLR activity could be helpful not only for mutation characterization but also for diagnostic purposes. PMID:21865347

Suppression of atherosclerosis by synthetic REV-ERB agonist

PubMed Central

Sitaula, Sadichha; Billon, Cyrielle; Kamenecka, Theodore M.; Solt, Laura A.; Burris, Thomas P.

2015-01-01

The nuclear receptors for heme, REV-ERBα and REV-ERBβ, play important roles in the regulation of metabolism and inflammation. Recently it was demonstrated that reduced REV-ERBα expression in hematopoetic cells in LDL receptor null mice led to increased atherosclerosis. We sought to determine if synthetic REV-ERB agonists that we have developed might have the ability to suppress atherosclerosis in this model. A previously characterized synthetic REV-ERB agonist, SR9009, was used to determine if activation of REV-ERB activity would affect atherosclerosis in LDL receptor deficient mice. Atherosclerotic plaque size was significantly reduced (p < 0.05) in mice administered SR9009 (100 mg/kg) for seven weeks compared to control mice (n = 10 per group). SR9009 treatment of bone marrow-derived mouse macrophages (BMDM) reduced the polarization of BMDMs to proinflammatory M1 macrophage while increasing the polarization of BMDMs to anti-inflammatory M2 macrophages. Our results suggest that pharmacological targeting of REV-ERBs may be a viable therapeutic option for treatment of atherosclerosis. PMID:25800870

Analysis of the Afrikaner mutation in exon 9 of the low-density lipoprotein receptor gene in a large Dutch kindred suffering from familial hypercholesterolaemia.

PubMed

Defesche, J C; Lansberg, P J; Reymer, P W; Lamping, R J; Kastelein, J J

1993-02-01

Familial hypercholesterolaemia (FH) is the most common genetic metabolic disorder, affecting about 1 in 500 persons in the general population. With novel techniques, it is possible to identify the molecular defects underlying FH in the gene coding for the low-density lipoprotein (LDL) receptor, thereby confirming the diagnosis of FH. In this study we present a large family with a specific mutation in exon 9 of the LDL-receptor gene (an Afrikaner mutation) and we demonstrate that by a large-scale case-finding study in this family, carriers of such a mutation can be detected. Of 63 family members, 13 were shown to be at risk for cardiovascular disease as judged by their lipoprotein profile or the presence of the Afrikaner mutation. Two persons were detected, affected with a dyslipidaemia other than FH. Medical management was initiated in order to reduce the high cardiovascular risk associated with this disorder.

ABCG1-mediated generation of extracellular cholesterol microdomains[S

PubMed Central

Freeman, Sebastian R.; Jin, Xueting; Anzinger, Joshua J.; Xu, Qing; Purushothaman, Sonya; Fessler, Michael B.; Addadi, Lia; Kruth, Howard S.

2014-01-01

Previous studies have demonstrated that the ATP-binding cassette transporters (ABC)A1 and ABCG1 function in many aspects of cholesterol efflux from macrophages. In this current study, we continued our investigation of extracellular cholesterol microdomains that form during enrichment of macrophages with cholesterol. Human monocyte-derived macrophages and mouse bone marrow-derived macrophages, differentiated with macrophage colony-stimulating factor (M-CSF) or granulocyte macrophage colony-stimulation factor (GM-CSF), were incubated with acetylated LDL (AcLDL) to allow for cholesterol enrichment and processing. We utilized an anti-cholesterol microdomain monoclonal antibody to reveal pools of unesterified cholesterol, which were found both in the extracellular matrix and associated with the cell surface, that we show function in reverse cholesterol transport. Coincubation of AcLDL with 50 μg/ml apoA-I eliminated all extracellular and cell surface-associated cholesterol microdomains, while coincubation with the same concentration of HDL only removed extracellular matrix-associated cholesterol microdomains. Only at an HDL concentration of 200 µg/ml did HDL eliminate the cholesterol microdomains that were cell-surface associated. The deposition of cholesterol microdomains was inhibited by probucol, but it was increased by the liver X receptor (LXR) agonist TO901317, which upregulates ABCA1 and ABCG1. Extracellular cholesterol microdomains did not develop when ABCG1-deficient mouse bone marrow-derived macrophages were enriched with cholesterol. Our findings show that generation of extracellular cholesterol microdomains is mediated by ABCG1 and that reverse cholesterol transport occurs not only at the cell surface but also within the extracellular space. PMID:24212237

Telomerase Activation in Atherosclerosis and Induction of Telomerase Reverse Transcriptase Expression by Inflammatory Stimuli in Macrophages

PubMed Central

Gizard, Florence; Heywood, Elizabeth B.; Findeisen, Hannes M.; Zhao, Yue; Jones, Karrie L.; Cudejko, Cèline; Post, Ginell R.; Staels, Bart; Bruemmer, Dennis

2010-01-01

Objective Telomerase serves as a critical regulator of tissue renewal. Although telomerase activity is inducible in response to various environmental cues, it remains unknown whether telomerase is activated during the inflammatory remodeling underlying atherosclerosis formation. To address this question, we investigated in the present study the regulation of telomerase in macrophages and during atherosclerosis development in LDL-receptor-deficient mice. Methods and Results We demonstrate that inflammatory stimuli activate telomerase in macrophages by inducing the expression of the catalytic subunit telomerase reverse transcriptase (TERT). Reporter and chromatin immunoprecipitation assays identified a previously unrecognized NF-κB response element in the TERT promoter, to which NF-κB is recruited during inflammation. Inhibition of NF-κB signaling completely abolished the induction of TERT expression, characterizing TERT as a bona fide NF-κB target gene. Furthermore, functional experiments revealed that TERT-deficiency results in a senescent cell phenotype. Finally, we demonstrate high levels of TERT expression in macrophages of human atherosclerotic lesions and establish that telomerase is activated during atherosclerosis development in LDL-receptor-deficient mice. Conclusion These results characterize TERT as a previously unrecognized NF-κB target gene in macrophages and demonstrate that telomerase is activated during atherosclerosis. This induction of TERT expression prevents macrophage senescence and may have important implications for the development of atherosclerosis. PMID:21106948

Liver-specific inhibition of acyl-coenzyme a:cholesterol acyltransferase 2 with antisense oligonucleotides limits atherosclerosis development in apolipoprotein B100-only low-density lipoprotein receptor-/- mice.

PubMed

Bell, Thomas A; Brown, J Mark; Graham, Mark J; Lemonidis, Kristina M; Crooke, Rosanne M; Rudel, Lawrence L

2006-08-01

The purpose of this study was to determine the effects of liver-specific inhibition of acyl-coenzyme A:cholesterol acyltransferase 2 (ACAT2) on the development of hypercholesterolemia and atherosclerosis in mice. Apolipoprotein B100-only low-density lipoprotein (LDL) receptor-/- mice were given saline, a nontargeting control antisense oligonucleotide (ASO), or ASOs targeting ACAT2 biweekly for a period spanning 16 weeks. Mice treated with ACAT2 targeting ASOs had liver-specific reduction in ACAT2 mRNA, yet intestinal ACAT2 and cholesterol absorption was left undisturbed. ASO-mediated knockdown of ACAT2 resulted in reduction of total plasma cholesterol, increased levels of plasma triglyceride, and a shift in LDL cholesteryl ester (CE) fatty acid composition from mainly saturated and monounsaturated to polyunsaturated fatty acid enrichment. Furthermore, the liver-specific depletion of ACAT2 resulted in protection against diet-induced hypercholesterolemia and aortic CE deposition. This is the first demonstration that specific pharmacological inhibition of ACAT2, without affecting ACAT1, is atheroprotective. Hepatic ACAT2 plays a critical role in driving the production of atherogenic lipoproteins, and therapeutic interventions, such as the ACAT2-specific ASOs used here, which reduce acyltransferase 2 (ACAT2) function in the liver without affecting ACAT1, may provide clinical benefit for cardiovascular disease prevention.

Superiority of dietary safflower oil over olive oil in lowering serum cholesterol and increasing hepatic mRnas for the LDL receptor and cholesterol 7alpha-hydroxylase in exogenously hypercholesterolemic (exHC) rats.

PubMed

Sato, M; Yoshida, S; Nagao, K; Imaizumi, K

2000-06-01

The exogenously hypercholesterolemic (ExHC) rat is a strain segregated from SD rats with a high response to dietary cholesterol. To understand the underlying mechanism(s) for this hypercholesterolemia, the interactive effects of dietary fatty acid and the susceptibility of rats to dietary cholesterol on the serum cholesterol concentration and hepatic mRNA abundance of the low-density lipoprotein (LDL) receptor, cholesterol 7alpha-hydroxylase (7alpha-hydroxylase) and 3-hydroxyl-3methylglutaryl (HMG) CoA reductase were examined. Both strains were fed on a diet supplemented with 10% each of olive, safflower or coconut oil with or without the addition of 1% cholesterol for one week. The ExHC rats fed on olive, safflower and coconut oil in combination with cholesterol respectively resulted in a 3.5-, 2.0- and 2.1-fold higher serum cholesterol concentration than that in the animals fed on the corresponding dietary fats without any supplementation of cholesterol (p < 0.01 by dietary cholesterol or type of fat). The dietary cholesterol dependent-elevation of serum cholesterol in the SD rats was less than 1.5-fold (p<0.01) and there was no dietary fat effect. The ExHC rats fed on the safflower oil-containing diet supplemented with cholesterol resulted in a higher mRNA abundance of the LDL receptor and 7alpha-hydroxylase than in the corresponding fat-fed rats without cholesterol (p<0.05). There was no dietary cholesterol-dependent change of mRNA abundance in either strain fed on olive or coconut oil, except for a decreased abundance of HMG CoA reductase mRNA in the olive oil-fed ExHC rats and coconut oil-fed Sprague-Dawley (SD) rats (p<0.05). These results indicate that the hepatic mRNA abundance of the LDL receptor and of 7alpha-hydroxylase depended on the dietary combination of cholesterol and a fatty acid and suggest that a linoleic acid-rich diet may alleviate exogenous hypercholesterolemia by activating the process involved in the hepatic uptake and biliary excretion of serum cholesterol.

Decorin GAG synthesis and TGF-β signaling mediate Ox-LDL-induced mineralization of human vascular smooth muscle cells.

PubMed

Yan, Jianyun; Stringer, Sally E; Hamilton, Andrew; Charlton-Menys, Valentine; Götting, Christian; Müller, Benjamin; Aeschlimann, Daniel; Alexander, M Yvonne

2011-03-01

Decorin and oxidized low-density lipoprotein (Ox-LDL) independently induce osteogenic differentiation of vascular smooth muscle cells (VSMCs). We aimed to determine whether decorin glycosaminoglycan (GAG) chain synthesis contributes to Ox-LDL-induced differentiation and calcification of human VSMCs in vitro. Human VSMCs treated with Ox-LDL to induce oxidative stress showed increased alkaline phosphatase (ALP) activity, accelerated mineralization, and a difference in both decorin GAG chain biosynthesis and CS/DS structure compared with untreated controls. Ox-LDL increased mRNA abundance of both xylosyltransferase (XT)-I, the key enzyme responsible for GAG chain biosynthesis and Msx2, a marker of osteogenic differentiation. Furthermore, downregulation of XT-I expression using small interfering RNA blocked Ox-LDL-induced VSMC mineralization. Adenoviral-mediated overexpression of decorin, but not a mutated unglycanated form, accelerated mineralization of VSMCs, suggesting GAG chain addition on decorin is crucial for the process of differentiation. The decorin-induced VSMC osteogenic differentiation involved activation of the transforming growth factor (TGF)-β pathway, because it was attenuated by blocking of TGF-β receptor signaling and because decorin overexpression potentiated phosphorylation of the downstream signaling molecule smad2. These studies provide direct evidence that oxidative stress-mediated decorin GAG chain synthesis triggers TGF-β signaling and mineralization of VSMCs in vitro.

Gender disparity in LDL-induced cardiovascular damage and the protective role of estrogens against electronegative LDL

PubMed Central

2014-01-01

Background Increased levels of the most electronegative type of LDL, L5, have been observed in the plasma of patients with metabolic syndrome (MetS) and ST-segment elevation myocardial infarction and can induce endothelial dysfunction. Because men have a higher predisposition to developing coronary artery disease than do premenopausal women, we hypothesized that LDL electronegativity is increased in men and promotes endothelial damage. Methods L5 levels were compared between middle-aged men and age-matched, premenopausal women with or without MetS. We further studied the effects of gender-influenced LDL electronegativity on aortic cellular senescence and DNA damage in leptin receptor–deficient (db/db) mice by using senescence-associated–β-galactosidase and γH2AX staining, respectively. We also studied the protective effects of 17β-estradiol and genistein against electronegative LDL–induced senescence in cultured bovine aortic endothelial cells (BAECs). Results L5 levels were higher in MetS patients than in healthy subjects (P < 0.001), particularly in men (P = 0.001). LDL isolated from male db/db mice was more electronegative than that from male or female wild-type mice. In addition, LDL from male db/db mice contained abundantly more apolipoprotein CIII and induced more BAEC senescence than did female db/db or wild-type LDL. In the aortas of db/db mice but not wild-type mice, we observed cellular senescence and DNA damage, and the effect was more significant in male than in female db/db mice. Pretreatment with 17β-estradiol or genistein inhibited BAEC senescence induced by male or female db/db LDL and downregulated the expression of lectin-like oxidized LDL receptor-1 and tumor necrosis factor-alpha protein. Conclusion The gender dichotomy of LDL-induced cardiovascular damage may underlie the increased propensity to coronary artery disease in men. PMID:24666525

Fluorine-18 radiolabeling of low-density lipoproteins: a potential approach for characterization and differentiation of metabolism of native and oxidized low-density lipoproteins in vivo.

PubMed

Pietzsch, Jens; Bergmann, Ralf; Rode, Katrin; Hultsch, Christina; Pawelke, Beate; Wuest, Frank; van den Hoff, Joerg

2004-11-01

Oxidative modification of low-density lipoprotein (LDL) is regarded as a crucial event in atherogenesis. Assessing the metabolic fate of oxidized LDL (oxLDL) in vivo with radiotracer techniques is hindered by the lack of suitable sensitive and specific radiolabeling methods. We evaluated an improved methodology based on the radiolabeling of native LDL (nLDL) and oxLDL with the positron emitter fluorine-18 ((18)F) by conjugation with N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). We investigated whether radiolabeling of LDL induces adverse structural modifications. Results suggest that radiolabeling of both nLDL and oxLDL using [(18)F]SFB causes neither additional oxidative structural modifications of LDL lipids and proteins nor alteration of their biological activity and functionality, respectively. Thus, radiolabeling of LDL using [(18)F]SFB could prove to be a promising approach for studying the kinetics of oxLDL in vivo.

Treatment of homozygous familial hypercholesterolaemia in paediatric patients: A monocentric experience.

PubMed

Buonuomo, Paola S; Macchiaiolo, Marina; Leone, Giovanna; Valente, Paola; Mastrogiorgio, Gerarda; Gnazzo, Maria; Rana, Ippolita; Gonfiantini, Michaela V; Gagliardi, Maria G; Romano, Francesca; Bartuli, Andrea

2018-01-01

Background Homozygous familial hypercholesterolaemia is a rare life-threatening disease characterized by markedly elevated low-density lipoprotein cholesterol (LDL-C) concentrations and accelerated atherosclerosis. The presence of double gene defects in the LDL-Receptor, either the same defect (homozygous) or two different LDL-raising mutations (compound heterozygotes) or other variants, identify the homozygous phenotype (HopFH). Apheresis is a procedure in which plasma is separated from red blood cells before the physical removal of LDL-C or the LDL-C is directly removed from whole blood. It is currently the treatment of choice for patients with HopFH whose LDL-C levels are not able to be reduced to target levels with conventional lipid-lowering drug therapy. Design The aim of this study is to report a cohort of six paediatric patients and to evaluate the long term efficacy of combined medical therapy and LDL-apheresis on LDL-C reduction. Methods We collected data from six children with confirmed diagnosis of HopFH (two females and four males; age range at diagnosis 3-8 years, mean 6 ± 1 years) from a single clinical hospital in Italy from 2007 to 2017. Results Clinical manifestations and outcomes may greatly vary in children with HopFH. Medical therapy and LDL-apheresis for the severe form should be started promptly in order to prevent cardiovascular disease. Conclusions Lipoprotein apheresis is a very important tool in managing patients with HopFH at high risk of cardiovascular disease. Based on our experience and the literature data, the method is feasible in very young children, efficient regarding biological results and cardiac events, and safe with minor side-effects and technical problems. We advise treating homozygous and compound heterozygous children as soon as possible.

The Oxidized Low-Density Lipoprotein Receptor Mediates Vascular Effects of Inhaled Vehicle Emissions

PubMed Central

Lucero, JoAnn; Harman, Melissa; Madden, Michael C.; McDonald, Jacob D.; Seagrave, Jean Clare; Campen, Matthew J.

2011-01-01

Rationale: To determine vascular signaling pathways involved in inhaled air pollution (vehicular engine emission) exposure–induced exacerbation of atherosclerosis that are associated with onset of clinical cardiovascular events. Objectives: To elucidate the role of oxidized low-density lipoprotein (oxLDL) and its primary receptor on endothelial cells, the lectin-like oxLDL receptor (LOX-1), in regulation of endothelin-1 expression and matrix metalloproteinase activity associated with inhalational exposure to vehicular engine emissions. Methods: Atherosclerotic apolipoprotein E knockout mice were exposed by inhalation to filtered air or mixed whole engine emissions (250 μg particulate matter [PM]/m3 diesel + 50 μg PM/m3 gasoline exhausts) 6 h/d for 7 days. Concurrently, mice were treated with either mouse IgG or neutralizing antibodies to LOX-1 every other day. Vascular and plasma markers of oxidative stress and expression proatherogenic factors were assessed. In a parallel study, healthy human subjects were exposed to either 100 μg PM/m3 diesel whole exhaust or high-efficiency particulate air and charcoal-filtered “clean” air (control subjects) for 2 hours, on separate occasions. Measurements and Main Results: Mixed emissions exposure increased oxLDL and vascular reactive oxygen species, as well as LOX-1, matrix metalloproteinase-9, and endothelin-1 mRNA expression and also monocyte/macrophage infiltration, each of which was attenuated with LOX-1 antibody treatment. In a parallel study, diesel exhaust exposure in volunteer human subjects induced significant increases in plasma-soluble LOX-1. Conclusions: These findings demonstrate that acute exposure to vehicular source pollutants results in up-regulation of vascular factors associated with progression of atherosclerosis, endothelin-1, and matrix metalloproteinase-9, mediated through oxLDL–LOX-1 receptor signaling, which may serve as a novel target for future therapy. PMID:21493736

Low-dose atorvastatin improves dyslipidemia and vascular function in patients with primary biliary cirrhosis after one year of treatment.

PubMed

Stojakovic, Tatjana; Claudel, Thierry; Putz-Bankuti, Csilla; Fauler, Günter; Scharnagl, Hubert; Wagner, Martin; Sourij, Harald; Stauber, Rudolf E; Winkler, Karl; März, Winfried; Wascher, Thomas C; Trauner, Michael

2010-03-01

Primary biliary cirrhosis (PBC) is frequently associated with hypercholesterolemia and with an increased cardiovascular morbidity and mortality. Statins lower serum cholesterol levels and may thus improve the cardiovascular risk in PBC patients. The aim of our study was to prospectively examine the efficacy of low-dose atorvastatin on cholestasis as well as cardiovascular risk markers such as dyslipidemia and vascular function in patients with PBC. Nineteen patients with early-stage (biopsy proven and AMA positive) PBC and low-density lipoprotein cholesterol (LDL-C) above 130mg/dL were included in this single-center study and treated with atorvastatin 10mg per day for one year. Concentrations of total cholesterol, LDL-C, LDL triglycerides, oxLDL, IgG and sVCAM-1 decreased significantly after 48 weeks of atorvastatin treatment. Flow-mediated dilation (FMD) of the brachial artery as an indicator of vascular function significantly increased, while carotid artery intima-media thickness and vascular wall stiffness did not progress under treatment. No statistical differences in liver enzymes were observed except a transient increase of alkaline phosphatase. Treatment with low-dose atorvastatin is safe in early-stage PBC, effectively reduces total cholesterol, LDL-C, LDL triglycerides, oxLDL and sVCAM-1 and improves vascular function as reflected by FMD, without affecting cholestasis progression. Therefore, statin therapy should be considered in PBC patients with additional risk factors for cardiovascular disease.

Thyroid hormone reduces PCSK9 and stimulates bile acid synthesis in humans[S

PubMed Central

Bonde, Ylva; Breuer, Olof; Lütjohann, Dieter; Sjöberg, Stefan; Angelin, Bo; Rudling, Mats

2014-01-01

Reduced plasma LDL-cholesterol is a hallmark of hyperthyroidism and is caused by transcriptional stimulation of LDL receptors in the liver. Here, we investigated whether thyroid hormone (TH) actions involve other mechanisms that may also account for the reduction in LDL-cholesterol, including effects on proprotein convertase subtilisin/kexin type 9 (PCSK9) and bile acid synthesis. Twenty hyperthyroid patients were studied before and after clinical normalization, and the responses to hyperthyroidism were compared with those in 14 healthy individuals after 14 days of treatment with the liver-selective TH analog eprotirome. Both hyperthyroidism and eprotirome treatment reduced circulating PCSK9, lipoprotein cholesterol, apoB and AI, and lipoprotein(a), while cholesterol synthesis was stable. Hyperthyroidism, but not eprotirome treatment, markedly increased bile acid synthesis and reduced fibroblast growth factor (FGF) 19 and dietary cholesterol absorption. Eprotirome treatment, but not hyperthyroidism, reduced plasma triglycerides. Neither hyperthyroidism nor eprotirome treatment altered insulin, glucose, or FGF21 levels. TH reduces circulating PSCK9, thereby likely contributing to lower plasma LDL-cholesterol in hyperthyroidism. TH also stimulates bile acid synthesis, although this response is not critical for its LDL-lowering effect. PMID:25172631

Effects of obeticholic acid on lipoprotein metabolism in healthy volunteers.

PubMed

Pencek, R; Marmon, T; Roth, J D; Liberman, A; Hooshmand-Rad, R; Young, M A

2016-09-01

The bile acid analogue obeticholic acid (OCA) is a selective farnesoid X receptor (FXR) agonist in development for treatment of several chronic liver diseases. FXR activation regulates lipoprotein homeostasis. The effects of OCA on cholesterol and lipoprotein metabolism in healthy individuals were assessed. Two phase I studies were conducted to evaluate the effects of repeated oral doses of 5, 10 or 25 mg OCA on lipid variables after 14 or 20 days of consecutive administration in 68 healthy adults. Changes in HDL and LDL cholesterol levels were examined, in addition to nuclear magnetic resonance analysis of particle sizes and sub-fraction concentrations. OCA elicited changes in circulating cholesterol and particle size of LDL and HDL. OCA decreased HDL cholesterol and increased LDL cholesterol, independently of dose. HDL particle concentrations declined as a result of a reduction in medium and small HDL. Total LDL particle concentrations increased because of an increase in large LDL particles. Changes in lipoprotein metabolism attributable to OCA in healthy individuals were found to be consistent with previously reported changes in patients receiving OCA with non-alcoholic fatty liver disease or non-alcoholic steatohepatitis. © 2016 John Wiley & Sons Ltd.

Circulating PCSK9 in patients with type 2 diabetes and related metabolic disorders.

PubMed

Ibarretxe, Daiana; Girona, Josefa; Plana, Núria; Cabré, Anna; Ferré, Raimón; Amigó, Núria; Guaita, Sandra; Mallol, Roger; Heras, Mercedes; Masana, Luis

2016-01-01

PCSK9 is a pivotal molecule in the regulation of lipid metabolism. Previous studies have suggested that PCSK9 expression and its function in LDL receptor regulation could be altered in the context of diabetes. The aim was to assess PCSK9 plasma levels in patients with type 2 diabetes (T2DM) and other related metabolic disorders as well as its relation to the metabolomic profile generated by nuclear magnetic resonance (NMR) and glucose homeostasis. There were recruited a total of 457 patients suffering from T2DM and other metabolic disorders (metabolic syndrome (MetS), obesity and atherogenic dyslipidaemia (AD) and other disorders). Anamnesis, anthropometry and physical examinations were conducted, and vascular and abdominal adiposity imaging were carried out. Biochemical studies were performed to determine PCSK9 plasma levels 6 weeks after lipid lowering drug wash-out in treated patients. A complete metabolomic lipid profile was also generated by NMR. The rs505151 and rs11591147 genetic variants of PCSK9 gene were identified in patients. The results showed that PCSK9 levels are increased in patients with T2DM and MetS (14% and 13%; p<0.005, respectively). Circulating PCSK9 levels were correlated with an atherogenic lipid profile and with insulin resistance parameters. PCSK9 levels were also positively associated with AD, as defined by lipoprotein particle number and size. The rs11591147 genetic variant resulted in lower levels of circulating PCSK9 and LDL cholesterol (LDL-C). PCSK9 plasma levels are increased in T2DM and MetS patients and are associated with LDL-C and other parameters of AD and glucose metabolism. Copyright © 2015 Sociedad Española de Arteriosclerosis. Published by Elsevier España. All rights reserved.

PCSK9 inhibition: the dawn of a new age in cholesterol lowering?

PubMed

Preiss, David; Mafham, Marion

2017-03-01

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulating enzyme of hepatic origin that plays a key role in LDL receptor turnover. Genetic studies have confirmed that individuals with gain-of-function PCSK9 mutations have increased PCSK9 activity, elevated LDL-cholesterol levels and a severe form of familial hypercholesterolaemia. Those with variants leading to reduced PCSK9 have lower LDL-cholesterol levels and a reduced risk of coronary heart disease, and this has led to the development of various strategies aimed at reducing circulating PCSK9. Monoclonal antibodies to PCSK9, given every 2-4 weeks by subcutaneous injection, have been shown to reduce LDL-cholesterol by 50-60% compared with placebo in individuals with and without diabetes. PCSK9 inhibition also reduces lipoprotein(a), an atherogenic lipid particle, by around 20-30%. Major cardiovascular outcome trials for two agents, evolocumab and alirocumab, are expected to report from 2017. These trials involve over 45,000 participants and are likely to include about 15,000 individuals with diabetes. PCSK9-binding adnectins have been employed as an alternative method of removing circulating PCSK9. Small interfering RNA targeting messenger RNA for PCSK9, which acts by reducing hepatic production of PCSK9, is also under investigation. These agents may only need to be given by subcutaneous injection once every 4-6 months. Ongoing trials will determine whether anti-PCSK9 antibody therapy safely reduces cardiovascular risk, although high cost may limit its use. Development of PCSK9-lowering technologies cheaper than monoclonal antibodies will be necessary for large numbers of individuals to benefit from this approach to lowering cholesterol.

Relationship between biomarkers of inflammation, oxidative stress and endothelial/microcirculatory function in successful aging versus healthy youth: a transversal study.

PubMed

Bottino, Daniel Alexandre; Lopes, Flávia Gomes; de Oliveira, Francisco José; Mecenas, Anete de Souza; Clapauch, Ruth; Bouskela, Eliete

2015-04-08

There is a functional decline of endothelial- dependent vasodilatation in the aging process. The aims of this study were to investigate if various microcirculatory parameters could correlate to anthropometrical variables, oxidative stress and inflammatory biomarkers in successful aging and compare the results to young healthy controls. Healthy elderly women (HE, 74.0 ± 8.7 years, n = 11) and young controls (YC, 23.1 ± 3.6 years, n = 24) were evaluated through nailfold videocapillaroscopy (NVC), venous occlusion plethysmography (VOP) and laboratorial analysis. Functional capillary density (FCD) and diameters, maximum red blood cell velocity (RBCVmax) during the reactive hyperemia response/RBCVbaseline after 1 min arterial occlusion at the finger base, time to reach RBCVmax were determined by NVC, peak increment of forearm blood flow (FBF) during the reactive hyperemia response (%Hyper) and after 0.4 mg sublingual nitroglycerin (%Nitro) by VOP and lipidogram, fibrinogen, fasting and postload glucose, oxidized LDL-cholesterol (oxLDL), sICAM, sVCAM, sE-Selectin, interleukines 1 and 6 and TNF-α by laboratorial analysis. Correlations and linear multiple regression (LMR) between %Hyper, %Nitro, microcirculatory parameters, oxidative stress and inflammatory biomarkers were investigated. sVCAM, sE-Selectin and oxLDL were higher and RBCVmax/RBCVbaseline and %Hyper lower in HE, while %Nitro and FCD remained unchanged. Fibrinogen, LDL-cholesterol, oxLDL correlated negatively to %Hyper while sVCAM correlated negatively to %Hyper and RBCVmax/RBCVbaseline. Healthy aged women presented dilated capillaries with sustained perfusion and endothelial dysfunction with preserved vascular smooth muscle reactivity. Fibrinogen, LDL-cholesterol, oxidized-LDL and sVCAM correlated negatively to endothelial function but not to microcirculatory parameters. Oxidized-LDL and sVCAM could determine %Hyper through LMR. Oxidized-LDL and sVCAM might be used as endothelial dysfunction biomarkers for elderly with normal cardiovascular risk factors.

Epidermal growth factor receptor plays a role in the regulation of liver and plasma lipid levels in adult male mice.

PubMed

Scheving, Lawrence A; Zhang, Xiuqi; Garcia, Oscar A; Wang, Rebecca F; Stevenson, Mary C; Threadgill, David W; Russell, William E

2014-03-01

Dsk5 mice have a gain of function in the epidermal growth factor receptor (EGFR), caused by a point mutation in the kinase domain. We analyzed the effect of this mutation on liver size, histology, and composition. We found that the livers of 12-wk-old male Dsk5 heterozygotes (+/Dsk5) were 62% heavier compared with those of wild-type controls (+/+). The livers of the +/Dsk5 mice compared with +/+ mice had larger hepatocytes with prominent, polyploid nuclei and showed modestly increased cell proliferation indices in both hepatocytes and nonparenchymal cells. An analysis of total protein, DNA, and RNA (expressed relative to liver weight) revealed no differences between the mutant and wild-type mice. However, the livers of the +/Dsk5 mice had more cholesterol but less phospholipid and fatty acid. Circulating cholesterol levels were twice as high in adult male +/Dsk5 mice but not in postweaned young male or female mice. The elevated total plasma cholesterol resulted mainly from an increase in low-density lipoprotein (LDL). The +/Dsk5 adult mouse liver expressed markedly reduced protein levels of LDL receptor, no change in proprotein convertase subtilisin/kexin type 9, and a markedly increased fatty acid synthase and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Increased expression of transcription factors associated with enhanced cholesterol synthesis was also observed. Together, these findings suggest that the EGFR may play a regulatory role in hepatocyte proliferation and lipid metabolism in adult male mice, explaining why elevated levels of EGF or EGF-like peptides have been positively correlated to increased cholesterol levels in human studies.

HEMOGLOBIN A1C, BLOOD PRESSURE, AND LDL-CHOLESTEROL CONTROL AMONG HISPANIC/LATINO ADULTS WITH DIABETES: RESULTS FROM THE HISPANIC COMMUNITY HEALTH STUDY/STUDY OF LATINOS (HCHS/SOL).

PubMed

Casagrande, Sarah Stark; Aviles-Santa, Larissa; Corsino, Leonor; Daviglus, Martha L; Gallo, Linda C; Espinoza Giacinto, Rebeca A; Llabre, Maria M; Reina, Samantha A; Savage, Peter J; Schneiderman, Neil; Talavera, Gregory A; Cowie, Catherine C

2017-10-01

To determine the prevalence of Hispanic/Latino adults with diabetes who meet target hemoglobin A1c, blood pressure (BP), and low-density-lipoprotein cholesterol (LDL-C) recommendations, and angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blocker (ARB) and statin medication use by heritage and sociodemographic and diabetes-related characteristics. Data were cross-sectional, collected between 2008 and 2011, and included adults age 18 to 74 years who reported a physician diagnosis of diabetes in the Hispanic Community Health Study/Study of Latinos (N = 2,148). Chi-square tests compared the prevalence of hemoglobin A1c, BP, and LDL-C targets and ACE/ARB and statin use across participant characteristics. Predictive margins regression was used to determine the prevalence adjusted for sociodemographic characteristics. The overall prevalence of A1c <7.0% (53 mmol/mol), BP <130/80 mm Hg, and LDL-C <100 mg/dL was 43.0, 48.7, and 36.6%, respectively, with 8.4% meeting all three targets. Younger adults aged 18 to 39 years with diabetes were less likely to have A1c <7.0% (53 mmol/mol) or LDL-C <100 mg/dL compared to those aged 65 to 74 years; younger adults were more likely to have BP <130/80 mm Hg (P<.05 for all). Individuals of Mexican heritage were significantly less likely to have A1c <7.0% (53 mmol/mol) compared to those with Cuban heritage, but they were more likely to have BP <130/80 mm Hg compared to those with Dominican, Cuban, or Puerto Rican heritage (P<.05 for all); there was no difference in LDL-C by heritage. Overall, 38.2% of adults with diabetes were taking a statin, and 50.5% were taking ACE/ARB medications. Hemoglobin A1c, BP, and LDL-C control are suboptimal among Hispanic/Latinos with diabetes living in the U.S. With 8.4% meeting all three recommendations, substantial opportunity exists to improve diabetes control in this population. A1c = hemoglobin A1c; ABC = hemoglobin A1c, blood pressure, low-density-lipoprotein cholesterol; ACE = angiotensin-converting enzyme; ADA = American Diabetes Association; ARB = angiotensin receptor blocker; BMI = body mass index; BP = blood pressure; CHD = coronary heart disease; CVD = cardiovascular disease; HCHS/SOL = Hispanic Community Health Study/Study of Latinos; LDL-C = low-density-lipoprotein cholesterol; NHANES = National Health and Nutrition Examination Survey; PAD = peripheral artery disease.

Activation of Adiponectin Receptor Regulates Proprotein Convertase Subtilisin/Kexin Type 9 Expression and Inhibits Lesions in ApoE-Deficient Mice.

PubMed

Sun, Lei; Yang, Xiaoxiao; Li, Qi; Zeng, Peng; Liu, Ying; Liu, Lipei; Chen, Yuanli; Yu, Miao; Ma, Chuanrui; Li, Xiaoju; Li, Yan; Zhang, Rongxin; Zhu, Yan; Miao, Qing Robert; Han, Jihong; Duan, Yajun

2017-07-01

The reduced adiponectin levels are associated with atherosclerosis. Adiponectin exerts its functions by activating adiponectin receptor (AdipoR). Proprotein convertase subtilisin kexin type 9 (PCSK9) degrades LDLR protein (low-density lipoprotein receptor) to increase serum LDL-cholesterol levels. PCSK9 expression can be regulated by PPARγ (peroxisome proliferator-activated receptor γ) or SREBP2 (sterol regulatory element-binding protein 2). The effects of AdipoR agonists on PCSK9 and LDLR expression, serum lipid profiles, and atherosclerosis remain unknown. At cellular levels, AdipoR agonists (ADP355 and AdipoRon) induced PCSK9 transcription/expression that solely depended on activation of PPAR-responsive element in the PCSK9 promoter. AdipoR agonists induced PPARγ expression; thus, the AdipoR agonist-activated PCSK9 expression/production was impaired in PPARγ deficient hepatocytes. Meanwhile, AdipoR agonists transcriptionally activated LDLR expression by activating SRE in the LDLR promoter. Moreover, AMP-activated protein kinase α (AMPKα) was involved in AdipoR agonist-activated PCSK9 expression. In wild-type mice, ADP355 increased PCSK9 and LDLR expression and serum PCSK9 levels, which was associated with activation of PPARγ, AMPKα and SREBP2 and reduction of LDL-cholesterol levels. In contrast, ADP355 reduced PCSK9 expression/secretion in apoE-deficient (apoE -/- ) mice, but it still activated hepatic LDLR, PPARγ, AMPKα, and SREBP2. More importantly, ADP355 inhibited lesions in en face aortas and sinus lesions in aortic root in apoE -/- mice with amelioration of lipid profiles. Our study demonstrates that AdipoR activation by agonists regulated PCSK9 expression differently in wild-type and apoE -/- mice. However, ADP355 activated hepatic LDLR expression and ameliorated lipid metabolism in both types of mice and inhibited atherosclerosis in apoE -/- mice. © 2017 American Heart Association, Inc.

Non-conventional Frizzled ligands and Wnt receptors.

PubMed

Hendrickx, Marijke; Leyns, Luc

2008-05-01

The Wnt family of secreted signaling factors plays numerous roles in embryonic development and in stem cell biology. In the adult, Wnt signaling is involved in tissue homeostasis and mutations that lead to the overexpression of Wnt can be linked to cancer. Wnt signaling is transduced intracellularly by the Frizzled (Fzd) family of receptors. In the canonical pathway, accumulation of beta-catenin and the subsequent formation of a complex with T cell factors (TCF) or lymphoid enhancing factors (Lef) lead to target gene activation. The identification of Ryk as an alternative Wnt receptor and the discovery of the novel Fzd ligands Norrie disease protein (NDP) and R-Spondin, changed the traditional view of Wnts binding to Fzd receptors. Mouse R-Spondin cooperates with Wnt signaling and Low density lipoprotein (LDL) receptor related protein (LRP) to activate beta-catenin dependent gene expression and is involved in processes such as limb and placental development in the mouse. NDP is the product of the Norrie disease gene and controls vascular development in the retina, inner ear and in the female reproductive system during pregnancy. In this review a functional overview of the interactions of the different Wnt and non-Wnt ligands with the Fzd receptors is given as well as a survey of Wnts binding to Ryk and we discuss the biological significance of these interactions.

Apolipoprotein B, the villain in the drama?

PubMed

Yu, Qi; Zhang, Yaping; Xu, Cang-Bao

2015-02-05

Low-density lipoprotein (LDL) is the major atherogenic lipoprotein and the primary target of lipid-lowering therapy for treating ischemic cardiovascular disease. Apolipoprotein B (apoB), an important structural component of LDL, plays a key role in cholesterol transport and removal in vascular wall. On the other hand, under pathological process, apoB interacts with the arterial wall to initiate the cascade of events that leads to atherosclerosis. However, interactions between apoB and vascular wall remain to be determined. Here, we address a pathological role of apoB per se and whole LDL particle in dysfunction of vascular endothelium and smooth muscle cells i.e. decreased endothelium-dependent vasodilation and increased receptor-mediated vasoconstriction. We intend to discuss: i) how apoB is responsible for the deleterious effects of LDL in the development of ischemic cardiovascular disease; ii) why vaccine based on peptides derived from apoB-100 is a promising therapy for treating ischemic cardiovascular disease, and iii) direct inhibition of apoB production should be a better therapeutic option than simple LDL-cholesterol lowering therapy in the patients with severe hypercholesterolemia at high cardiovascular risk with statin intolerance. In conclusion, apoB, but not cholesterol, plays a major role in LDL-induced dysfunction of endothelium, suggesting that direct apoB-targeting agents might be a promising therapy for the treatment of ischemic cardiovascular disease. Copyright © 2014 Elsevier B.V. All rights reserved.

Genome-wide screen for modulation of hepatic apolipoprotein A-I (ApoA-I) secretion.

PubMed

Miles, Rebecca R; Perry, William; Haas, Joseph V; Mosior, Marian K; N'Cho, Mathias; Wang, Jian W J; Yu, Peng; Calley, John; Yue, Yong; Carter, Quincy; Han, Bomie; Foxworthy, Patricia; Kowala, Mark C; Ryan, Timothy P; Solenberg, Patricia J; Michael, Laura F

2013-03-01

Control of plasma cholesterol levels is a major therapeutic strategy for management of coronary artery disease (CAD). Although reducing LDL cholesterol (LDL-c) levels decreases morbidity and mortality, this therapeutic intervention only translates into a 25-40% reduction in cardiovascular events. Epidemiological studies have shown that a high LDL-c level is not the only risk factor for CAD; low HDL cholesterol (HDL-c) is an independent risk factor for CAD. Apolipoprotein A-I (ApoA-I) is the major protein component of HDL-c that mediates reverse cholesterol transport from tissues to the liver for excretion. Therefore, increasing ApoA-I levels is an attractive strategy for HDL-c elevation. Using genome-wide siRNA screening, targets that regulate hepatocyte ApoA-I secretion were identified through transfection of 21,789 siRNAs into hepatocytes whereby cell supernatants were assayed for ApoA-I. Approximately 800 genes were identified and triaged using a convergence of information, including genetic associations with HDL-c levels, tissue-specific gene expression, druggability assessments, and pathway analysis. Fifty-nine genes were selected for reconfirmation; 40 genes were confirmed. Here we describe the siRNA screening strategy, assay implementation and validation, data triaging, and example genes of interest. The genes of interest include known and novel genes encoding secreted enzymes, proteases, G-protein-coupled receptors, metabolic enzymes, ion transporters, and proteins of unknown function. Repression of farnesyltransferase (FNTA) by siRNA and the enzyme inhibitor manumycin A caused elevation of ApoA-I secretion from hepatocytes and from transgenic mice expressing hApoA-I and cholesterol ester transfer protein transgenes. In total, this work underscores the power of functional genetic assessment to identify new therapeutic targets.

Endoplasmic reticulum stress in diabetic mouse or glycated LDL-treated endothelial cells: protective effect of Saskatoon berry powder and cyanidin glycans.

PubMed

Zhao, Ruozhi; Xie, Xueping; Le, Khuong; Li, Wende; Moghadasian, Mohammed H; Beta, Trust; Shen, Garry X

2015-11-01

Endoplasmic reticulum (ER) stress is associated with insulin resistance and diabetic cardiovascular complications, and mechanism or remedy for ER stress remains to be determined. The results of the present study demonstrated that the levels of ER stress or unfolded protein response (UPR) markers, the intensity of thioflavin T (ThT) fluorescence and the abundances of GRP78/94, XBP-1 and CHOP proteins were elevated in cardiovascular tissue of diabetic leptin receptor-deficient (db/db) mice. Cyanidin-3-glucoside (C3G) and cyanidin-3-galactoside (C3Ga) are major anthocyanins in Saskatoon berry (SB) powder. The administration of 5% SB powder for 4 weeks attenuated ThT fluorescence and the UPR markers in hearts and aortae of wild-type and db/db mice. Treatment with glycated low-density lipoprotein (gLDL) increased ThT intensity in human umbilical vein endothelial cells (ECs). Elevated UPR markers were detected in gLDL-treated EC compared to control cultures. The involvement of ER stress in gLDL-treated EC was supported by that the addition of 4-phenyl butyrate acid (a known ER stress antagonist) inhibited gLDL-induced increases in ER stress or UPR markers. C3G at 30 μM or C3Ga at 100 μM reached their maximal inhibition on gLDL-induced increases in ThT, GRP78/94, XBP-1 and CHOP in EC. The results demonstrated that ER stress was enhanced in cardiovascular tissue of db/db mice or gLDL-treated EC. SB powder or cyanidin glycans prevented the abnormal increases in ER stress and UPR markers in cardiovascular tissue of diabetic db/db mice or gLDL-treated EC. Copyright © 2015 Elsevier Inc. All rights reserved.

Hyperglycemia and oxidized-LDL exert a deleterious effect on endothelial progenitor cell migration in type 2 diabetes mellitus.

PubMed

Hamed, Saher; Brenner, Benjamin; Abassi, Zaid; Aharon, Anat; Daoud, Deeb; Roguin, Ariel

2010-09-01

Type 2 diabetes mellitus (DM) patients with coronary artery disease (CAD) have elevated plasma oxidized-LDL (OxLDL) levels and impaired neovascularization. Hyperglycemia and hyperlipidemia impair endothelial progenitor cell (EPC) migration, and endothelial nitric oxide (NO) bioavailability and NO synthase (NOS) activity are essential for EPC migration. Stromal-derived factor-1alpha (SDF1alpha) contributes to EPC mobilization and homing by stimulating the CXC receptor-4 (CXCR4) on the EPC plasmalemma to activate the Pi3K/Akt/eNOS signaling pathway. Therefore, we investigated the effect of high glucose (HG) and OxLDL on the migration and NO bioavailability of EPCs from healthy individuals, and then correlated the findings with those of EPCs from type 2 DM patients with and without CAD. EPCs from 15 healthy and 55 patients were exposed to HG, OxLDL, or both before evaluating EPC count, migration and NO production, and expression of CXCR4 and members of Pi3K/Akt/eNOS signaling cascade. Counts, migration, CXCR4 expression, and NO production were significantly reduced in EPCs from DM and CAD patients compared with that obtained in EPCs from healthy, and were further reduced in DM patients with CAD. The expression of CXCR4 and activation of Pi3K/Akt/eNOS signaling cascade were suppressed in OxLDL- and HG-treated EPCs, and this suppression was exacerbated when EPCs were treated simultaneously with HG and OxLDL. Hyperglycemia and elevated circulating OxLDL in DM patients with CAD severely impair EPC migration. These results suggest that the underlying mechanism for this impaired EPC migration is linked to the CXCR4/Pi3K/Akt/eNOS signaling pathway. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Tempol improves lipid profile and prevents left ventricular hypertrophy in LDL receptor gene knockout (LDLr-/-) mice on a high-fat diet.

PubMed

Viana Gonçalves, Igor Cândido; Cerdeira, Cláudio Daniel; Poletti Camara, Eduardo; Dias Garcia, José Antônio; Ribeiro Pereira Lima Brigagão, Maísa; Bessa Veloso Silva, Roberta; Bitencourt Dos Santos, Gérsika

2017-09-01

Dyslipidemia is associated with increased risk of cardiovascular disease and atherosclerosis, and hence with high morbidity and mortality. This study investigated the effects of the nitroxide 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (Tempol) on lipid profile and cardiac morphology in low-density lipoprotein (LDL) receptor gene knockout (LDLr-/-) mice. Male LDLr-/- mice (three months old, approximately 22 g weight) were divided into the following groups: controls, including (1) standard chow (SC, n=8) and (2) high-fat diet (HFD, n=8); and treatment, including (3) standard chow + Tempol (SC+T, n=8) (30 mg/kg administered by gavage, once daily) and (4) high-fat diet + Tempol (HFD+T, n=8) (30 mg/kg). After 30 days of the diet/treatment, whole blood was collected for analysis of biochemical parameters (total cholesterol, triglycerides [TG], high-density lipoprotein [HDL], LDL, and very low-density lipoprotein [VLDL]). The heart was removed through thoracotomy and histological analysis of the left ventricle was performed. A significant increase in TG, LDL, and VLDL and marked left ventricular hypertrophy (LVH) were demonstrated in the HFD group relative to the SC group (p<0.05), while Tempol treatment (HFD+T group) significantly (p<0.05) prevented increases in the levels of these lipid profile markers and attenuated LVH compared with the HFD group. In this study, Tempol showed potential for the prevention of events related to serious diseases of the cardiovascular system. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

Protective Effects of Let-7a and Let-7b on Oxidized Low-Density Lipoprotein Induced Endothelial Cell Injuries

PubMed Central

Bao, Mei-hua; Zhang, Yi-wen; Lou, Xiao-ya; Cheng, Yu; Zhou, Hong-hao

2014-01-01

Lectin-like low-density lipoprotein receptor 1 (LOX-1) is a receptor for oxidized low density lipoprotein (oxLDL) in endothelial cells. The activation of LOX-1 by oxLDL stimulates the apoptosis and dysfunction of endothelial cells, and contributes to atherogenesis. However, the regulatory factors for LOX-1 are still unclear. MicroRNAs are small, endogenous, non-coding RNAs that regulate gene expressions at a post-transcriptional level. The let-7 family is the second microRNA been discovered, which plays important roles in cardiovascular diseases. Let-7a and let-7b were predicted to target LOX-1 3′-UTR and be highly expressed in endothelial cells. The present study demonstrated that LOX-1 was a target of let-7a and let-7b. They inhibited the expression of LOX-1 by targeting the positions of 310-316 in LOX-1 3′-UTR. Over-expression of let-7a and let-7b inhibited the oxLDL-induced endothelial cell apoptosis, NO deficiency, ROS over-production, LOX-1 upregulation and endothelial nitric oxide synthase (eNOS) downregulation. Moreover, we found that oxLDL treatment induced p38MAPK phosphorylation, NF-κB nuclear translocation, IκB degradation and PKB dephosphorylation. Let-7a or let-7b over-expression attenuated these alterations significantly. The present study may provide a new insight into the protective properties of let-7a and let-7b in preventing the endothelial dysfunction associated with cardiovascular disease, such as atherosclerosis. PMID:25247304

Apolipoprotein B antisense inhibition--update on mipomersen.

PubMed

Gebhard, Catherine; Huard, Gabriel; Kritikou, Ekaterini A; Tardif, Jean-Claude

2013-01-01

Dyslipidemia is one of the main risk factors leading to cardiovascular disease (CVD). The standard of therapy, administration of statins, in conjunction with lifestyle and habit changes, can improve high cholesterol levels in the majority of patients. However, some patients with familial hypercholesterolemia (FH) need low-density-lipoprotein cholesterol (LDL-C) apheresis, as the available medications fail to reduce LDL-C levels sufficiently even at maximum doses. Intense research on cholesterol reducing agents and rapid progress in drug design have yielded many approaches that reduce cholesterol absorption or inhibit its synthesis. Antisense oligonucleotides (ASOs) targeting the production of apolipoprotein B-100 (apoB-100), inhibitors of proprotein convertase subtilisin/kexin type 9, microsomal triglyceride transfer protein inhibitors, squalene synthase inhibitors, peroxisome proliferator-activated receptor agonists, and thyroid hormone receptor agonists are some of the evolving approaches for lipid-lowering therapies. We provide an overview of the apoB ASO approach and its potential role in the management of dyslipidemia. Mipomersen (ISIS-301012, KYNAMRO™) is a synthetic ASO targeting the mRNA of apoB-100, which is an essential component of LDL particles and related atherogenic lipoproteins. ASOs bind to target mRNAs and induce their degradation thereby resulting in reduced levels of the corresponding protein levels. Mipomersen has been investigated in different indications including homozygous and heterozygous FH, as well as in high-risk hypercholesterolemic patients. Recent phase II and III clinical studies have shown a 25-47% reduction in LDL-C levels in mipomersen-treated patients. If future studies continue to show such promising results, mipomersen would likely be a viable additional lipid-lowering therapy for high-risk populations.

New Drugs for Treating Dyslipidemia: Beyond Statins

PubMed Central

Ahn, Chang Ho

2015-01-01

Statins have been shown to be very effective and safe in numerous randomized clinical trials, and became the implacable first-line treatment against atherogenic dyslipidemia. However, even with optimal statin treatment, 60% to 80% of residual cardiovascular risk still exists. The patients with familial hypercholesterolemia which results in extremely high level of low density lipoprotein cholesterol (LDL-C) level and the patients who are intolerant or unresponsive to statins are the other hurdles of statin treatment. Recently, new classes of lipid-lowering drugs have been developed and some of them are available for the clinical practice. The pro-protein convertase subtilisin/kexintype 9 (PCSK9) inhibitor increases the expression of low density lipoprotein (LDL) receptor in hepatocytes by enhancing LDL receptor recycling. The microsomal triglyceride transport protein (MTP) inhibitor and antisense oligonucleotide against apolipoprotein B (ApoB) reduce the ApoB containing lipoprotein by blocking the hepatic very low density lipoprotein synthesis pathway. The apolipoprotein A1 (ApoA1) mimetics pursuing the beneficial effect of high density lipoprotein cholesterol and can reverse the course of atherosclerosis. ApoA1 mimetics had many controversial clinical data and need more validation in humans. The PCSK9 inhibitor recently showed promising results of significant LDL-C lowering in familial hypercholesterolemia (FH) patients from the long-term phase III trials. The MTP inhibitor and antisesnse oligonucleotide against ApoB were approved for the treatment of homozygous FH but still needs more consolidated evidences about hepatic safety such as hepatosteatosis. We would discuss the benefits and concerns of these new lipid-lowering drugs anticipating additional benefits beyond statin treatment. PMID:25922802

Effects of small interfering RNA-mediated hepatic glucagon receptor inhibition on lipid metabolism in db/db mice.

PubMed

Han, Seongah; Akiyama, Taro E; Previs, Stephen F; Herath, Kithsiri; Roddy, Thomas P; Jensen, Kristian K; Guan, Hong-Ping; Murphy, Beth A; McNamara, Lesley A; Shen, Xun; Strapps, Walter; Hubbard, Brian K; Pinto, Shirly; Li, Cai; Li, Jing

2013-10-01

Hepatic glucose overproduction is a major characteristic of type 2 diabetes. Because glucagon is a key regulator for glucose homeostasis, antagonizing the glucagon receptor (GCGR) is a possible therapeutic strategy for the treatment of diabetes mellitus. To study the effect of hepatic GCGR inhibition on the regulation of lipid metabolism, we generated siRNA-mediated GCGR knockdown (si-GCGR) in the db/db mouse. The hepatic knockdown of GCGR markedly reduced plasma glucose levels; however, total plasma cholesterol was increased. The detailed lipid analysis showed an increase in the LDL fraction, and no change in VLDL HDL fractions. Further studies showed that the increase in LDL was the result of over-expression of hepatic lipogenic genes and elevated de novo lipid synthesis. Inhibition of hepatic glucagon signaling via siRNA-mediated GCGR knockdown had an effect on both glucose and lipid metabolism in db/db mice.

LDL-Induced Impairment of Human Vascular Smooth Muscle Cells Repair Function Is Reversed by HMG-CoA Reductase Inhibition

PubMed Central

Padró, Teresa; Lugano, Roberta; García-Arguinzonis, Maisa; Badimon, Lina

2012-01-01

Growing human atherosclerotic plaques show a progressive loss of vascular smooth muscle cells (VSMC) becoming soft and vulnerable. Lipid loaded-VSMC show impaired vascular repair function and motility due to changes in cytoskeleton proteins involved in cell-migration. Clinical benefits of statins reducing coronary events have been related to repopulation of vulnerable plaques with VSMC. Here, we investigated whether HMG-CoA reductase inhibition with rosuvastatin can reverse the effects induced by atherogenic concentrations of LDL either in the native (nLDL) form or modified by aggregation (agLDL) on human VSMC motility. Using a model of wound repair, we showed that treatment of human coronary VSMC with rosuvastatin significantly prevented (and reversed) the inhibitory effect of nLDL and agLDL in the repair of the cell depleted areas. In addition, rosuvastatin significantly abolished the agLDL-induced dephosphorylation of myosin regulatory light chain as demonstrated by 2DE-electrophoresis and mass spectrometry. Besides, confocal microscopy showed that rosuvastatin enhances actin-cytoskeleton reorganization during lipid-loaded-VSMC attachment and spreading. The effects of rosuvastatin on actin-cytoskeleton dynamics and cell migration were dependent on ROCK-signalling. Furthermore, rosuvastatin caused a significant increase in RhoA-GTP in the cytosol of VSMC. Taken together, our study demonstrated that inhibition of HMG-CoA reductase restores the migratory capacity and repair function of VSMC that is impaired by native and aggregated LDL. This mechanism may contribute to the stabilization of lipid-rich atherosclerotic plaques afforded by statins. PMID:22719992

Efficacy and safety of lipid lowering by alirocumab in chronic kidney disease.

PubMed

Toth, Peter P; Dwyer, Jamie P; Cannon, Christopher P; Colhoun, Helen M; Rader, Daniel J; Upadhyay, Ashish; Louie, Michael J; Koren, Andrew; Letierce, Alexia; Mandel, Jonas; Banach, Maciej

2018-06-01

Individuals with chronic kidney disease are at increased risk of premature cardiovascular disease. Among them, many with elevated low-density lipoprotein cholesterol (LDL-C) are unable to achieve optimal LDL-C on statins and require additional lipid-lowering therapy. To study this, we compared the LDL-C-lowering efficacy and safety of alirocumab in individuals with hypercholesterolemia with impaired renal function, defined as eGFR 30-59 ml/min/1.73 m 2 , to those without impaired renal function eGFR ≥60 ml/min/1.73 m 2 . A total of 4629 hypercholesterolemic individuals without or with impaired renal function, pooled from eight phase 3 ODYSSEY trials (double-blind treatments of 24-104 weeks), were on alirocumab 150 mg or 75/150 mg every two weeks vs. placebo or ezetimibe. Overall, 10.1% had impaired renal function and over 99% were receiving statin treatment. Baseline LDL-C in alirocumab and control groups was comparable in subgroups analyzed. LDL-C reductions at week 24 ranged from 46.1 to 62.2% or 48.3 to 60.1% with alirocumab among individuals with or without impaired renal function, respectively. Similar reductions were observed for lipoprotein (a), non-high-density lipoprotein cholesterol, apolipoprotein B, and triglycerides. Safety data were similar in both treatment subgroups, regardless of the degree of CKD. Renal function did not change over time in response to alirocumab. This post hoc efficacy analysis is limited by evaluation of alirocumab treatment effects on renal and lipid parameters by serum biochemistry. Thus, alirocumab consistently lowered LDL-C regardless of impaired renal function, with safety comparable to control, among individuals with hypercholesterolemia who nearly all were on statin treatment. Copyright © 2018 International Society of Nephrology. Published by Elsevier Inc. All rights reserved.

Mechanism of action of a peroxisome proliferator-activated receptor (PPAR)-delta agonist on lipoprotein metabolism in dyslipidemic subjects with central obesity.

PubMed

Ooi, Esther M M; Watts, Gerald F; Sprecher, Dennis L; Chan, Dick C; Barrett, P Hugh R

2011-10-01

Dyslipidemia increases the risk of cardiovascular disease in obesity. Peroxisome proliferator-activated receptor (PPAR)-δ agonists decrease plasma triglycerides and increase high-density lipoprotein (HDL)-cholesterol in humans. The aim of the study was to examine the effect of GW501516, a PPAR-δ agonist, on lipoprotein metabolism. Design, Setting, and Intervention: We conducted a randomized, double-blind, crossover trial of 6-wk intervention periods with placebo or GW501516 (2.5 mg/d), with 2-wk placebo washout between treatment periods. We recruited 13 dyslipidemic men with central obesity from the general community. We measured the kinetics of very low-density lipoprotein (VLDL)-, intermediate-density lipoprotein-, and low-density lipoprotein (LDL)-apolipoprotein (apo) B-100, plasma apoC-III, and high-density lipoprotein (HDL) particles (LpA-I and LpA-I:A-II). GW501516 decreased plasma triglycerides, fatty acid, apoB-100, and apoB-48 concentrations. GW501516 decreased the concentrations of VLDL-apoB by increasing its fractional catabolism and of apoC-III by decreasing its production rate (P < 0.05). GW501516 reduced VLDL-to-LDL conversion and LDL-apoB production. GW501516 increased HDL-cholesterol, apoA-II, and LpA-I:A-II concentrations by increasing apoA-II and LpA-I:A-II production (P < 0.05). GW501516 decreased cholesteryl ester transfer protein activity, and this was paralleled by falls in the triglyceride content of VLDL, LDL, and HDL and the cholesterol content of VLDL and LDL. GW501516 increased the hepatic removal of VLDL particles, which might have resulted from decreased apoC-III concentration. GW501516 increased apoA-II production, resulting in an increased concentration of LpA-I:A-II particles. This study elucidates the mechanism of action of this PPAR-δ agonist on lipoprotein metabolism and supports its potential use in treating dyslipidemia in obesity.

Cot/tpl2 participates in the activation of macrophages by adiponectin.

PubMed

Sanz-Garcia, Carlos; Nagy, Laura E; Lasunción, Miguel A; Fernandez, Margarita; Alemany, Susana

2014-06-01

Whereas the main function of APN is to enhance insulin activity, it is also involved in modulating the macrophage phenotype. Here, we demonstrate that at physiological concentrations, APN activates Erk1/2 via the IKKβ-p105/NF-κΒ1-Cot/tpl2 intracellular signal transduction cassette in macrophages. In peritoneal macrophages stimulated with APN, Cot/tpl2 influences the ability to phagocytose beads. However, Cot/tpl2 did not modulate the known capacity of APN to decrease lipid content in peritoneal macrophages in response to treatment with oxLDL or acLDL. A microarray analysis of gene-expression profiles in BMDMs exposed to APN revealed that APN modulated the expression of ∼3300 genes; the most significantly affected biological functions were the inflammatory and the infectious disease responses. qRT-PCR analysis of WT and Cot/tpl2 KO macrophages stimulated with APN for 0, 3, and 18 h revealed that Cot/tpl2 participated in the up-regulation of APN target inflammatory mediators included in the cytokine-cytokine receptor interaction pathway (KEGG ID 4060). In accordance with these data, macrophages stimulated with APN increased secretion of cytokines and chemokines, including IL-1β, IL-1α, TNF-α, IL-10, IL-12, IL-6, and CCL2. Moreover, Cot/tpl2 also played an important role in the production of these inflammatory mediators upon stimulation of macrophages with APN. It has been reported that different types of signals that stimulate TLRs, IL-1R, TNFR, FcγR, and proteinase-activated receptor-1 activate Cot/tpl2. Here, we demonstrate that APN is a new signal that activates the IKKβ-p105/NF-κΒ1-Cot/tpl2-MKK1/2-Erk1/2 axis in macrophages. Furthermore, this signaling cassette modulates the biological functions triggered by APN in macrophages. © 2014 Society for Leukocyte Biology.

Cot/tpl2 participates in the activation of macrophages by adiponectin

PubMed Central

Sanz-Garcia, Carlos; Nagy, Laura E.; Lasunción, Miguel A.; Fernandez, Margarita; Alemany, Susana

2014-01-01

Whereas the main function of APN is to enhance insulin activity, it is also involved in modulating the macrophage phenotype. Here, we demonstrate that at physiological concentrations, APN activates Erk1/2 via the IKKβ-p105/NF-κΒ1-Cot/tpl2 intracellular signal transduction cassette in macrophages. In peritoneal macrophages stimulated with APN, Cot/tpl2 influences the ability to phagocytose beads. However, Cot/tpl2 did not modulate the known capacity of APN to decrease lipid content in peritoneal macrophages in response to treatment with oxLDL or acLDL. A microarray analysis of gene-expression profiles in BMDMs exposed to APN revealed that APN modulated the expression of ∼3300 genes; the most significantly affected biological functions were the inflammatory and the infectious disease responses. qRT-PCR analysis of WT and Cot/tpl2 KO macrophages stimulated with APN for 0, 3, and 18 h revealed that Cot/tpl2 participated in the up-regulation of APN target inflammatory mediators included in the cytokine–cytokine receptor interaction pathway (KEGG ID 4060). In accordance with these data, macrophages stimulated with APN increased secretion of cytokines and chemokines, including IL-1β, IL-1α, TNF-α, IL-10, IL-12, IL-6, and CCL2. Moreover, Cot/tpl2 also played an important role in the production of these inflammatory mediators upon stimulation of macrophages with APN. It has been reported that different types of signals that stimulate TLRs, IL-1R, TNFR, FcγR, and proteinase-activated receptor-1 activate Cot/tpl2. Here, we demonstrate that APN is a new signal that activates the IKKβ-p105/NF-κΒ1-Cot/tpl2-MKK1/2-Erk1/2 axis in macrophages. Furthermore, this signaling cassette modulates the biological functions triggered by APN in macrophages. PMID:24532642

Primate-Specific Evolution of an LDLR Enhancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qian-fei; Prabhakar, Shyam; Wang, Qianben

2006-06-28

Sequence changes in regulatory regions have often beeninvoked to explain phenotypic divergence among species, but molecularexamples of this have been difficult to obtain. In this study, weidentified an anthropoid primate specific sequence element thatcontributed to the regulatory evolution of the LDL receptor. Using acombination of close and distant species genomic sequence comparisonscoupled with in vivo and in vitro studies, we show that a functionalcholesterol-sensing sequence motif arose and was fixed within apre-existing enhancer in the common ancestor of anthropoid primates. Ourstudy demonstrates one molecular mechanism by which ancestral mammalianregulatory elements can evolve to perform new functions in the primatelineage leadingmore » to human.« less

Higher incidence of mild cognitive impairment in familial hypercholesterolemia

PubMed Central

Zambón, D.; Quintana, M.; Mata, P.; Alonso, R.; Benavent, J.; Cruz-Sánchez, F.; Gich, J.; Pocoví, M.; Civeira, F.; Capurro, S.; Bachman, D.; Sambamurti, K.; Nicholas, J.; Pappolla, M. A.

2010-01-01

Objective Hypercholesterolemia is an early risk factor for Alzheimer’s disease. Low density lipoprotein (LDL) receptors may be involved in this disorder. Our objective was to determine the risk of mild cognitive impairment in a population of patients with heterozygous familial hypercholesterolemia, a condition involving LDL receptors dysfunction and life long hypercholesterolemia. Methods Using a cohort study design, patients with (N=47) meeting inclusion criteria and comparison patients without familial hypercholesterolemia (N=70) were consecutively selected from academic specialty and primary care clinics respectively. All patients were older than 50 years. Those with disorders which could impact cognition, including history of stroke or transient ischemic attacks, were excluded from both groups. Thirteen standardized neuropsychological tests were performed in all subjects. Mutational analysis was performed in patients with familial hypercholesterolemia and brain imaging was obtained in those with familial hypercholesterolemia and mild cognitive impairment. Results Patients with familial hypercholesterolemia showed a very high incidence of mild cognitive impairment compared to those without familial hypercholesterolemia (21.3% vs. 2.9%; p = 0.00). This diagnosis was unrelated to structural pathology or white matter disease. There were significant differences between the familial hypercholesterolemia and the no-familial hypercholesterolemia groups in several cognitive measures, all in the direction of worse performance for familial hypercholesterolemia patients, independent of apoE4 or apoE2 status. Conclusions Because prior studies have shown that older patients with sporadic hypercholesterolemia do not show higher incidence of mild cognitive impairment, the findings presented here suggest that early exposure to elevated cholesterol or LDL receptors dysfunction may be risk factors for mild cognitive impairment. PMID:20193836

Uptake of gold- and [3H]cholesteryl linoleate-labeled human low density lipoprotein by cultured rat granulosa cells: cellular mechanisms involved in lipoprotein metabolism and their importance to steroidogenesis

PubMed Central

1985-01-01

We used electron microscopy, acid hydrolase cytochemistry, and biochemistry to analyze the uptake and metabolism of colloidal gold- and [3H]cholesteryl linoleate-labeled human low density lipoprotein (LDL) by cultured rat granulosa cells. The initial interaction of gold- LDL conjugates with granulosa cells occurred at binding sites diffusely distributed over the plasma membrane. After incubation with ligand in the cold, 99.9% of the conjugates were at the cell surface but less than 4% lay over coated pits. Uptake was specific since it was decreased 93-95% by excess unconjugated LDL and heparin, but only 34- 38% by excess unconjugated human high density lipoprotein. LDL uptake was related to granulosa cell differentiation; well-luteinized cells bound 2-3 times as much gold-LDL as did poorly luteinized cells. Ligand internalization was initiated by warming and involved coated pits, coated vesicles, pale multivesicular bodies (MVBs), dense MVBs, and lysosomes. A key event in this process was the translocation of gold- LDL conjugates from the cell periphery to the Golgi zone. This step was carried out by the pale MVB, a prelysosomal compartment that behaves like an endosome. Granulosa cells exposed to LDL labeled with gold and [3H]cholesteryl linoleate converted [3H]sterol to [3H]progestin in a time-dependent manner. This conversion was paralleled by increased gold- labeling of lysosomes and blocked by chloroquine, an inhibitor of lysosomal activity. In brief, granulosa cells deliver LDL to lysosomes by a receptor-mediated mechanism for the hydrolysis of cholesteryl esters. The resulting cholesterol is, in turn, transferred to other cellular compartments, where conversion to steroid occurs. These events comprise the pathway used by steroid-secreting cells to obtain the LDL- cholesterol vital for steroidogenesis. PMID:3920223

Regulatory role of NADPH oxidase in glycated LDL-induced upregulation of plasminogen activator inhibitor-1 and heat shock factor-1 in mouse embryo fibroblasts and diabetic mice.

PubMed

Zhao, Ruozhi; Le, Khuong; Moghadasian, Mohammed H; Shen, Garry X

2013-08-01

Cardiovascular disease is the predominant cause of death in diabetic patients. Fibroblasts are one of the major types of cells in the heart or vascular wall. Increased levels of glycated low-density lipoprotein (glyLDL) were detected in diabetic patients. Previous studies in our group demonstrated that oxidized LDL increased the amounts of NADPH oxidase (NOX), plasminogen activator inhibitor-1 (PAI-1), and heat shock factor-1 (HSF1) in fibroblasts. This study examined the expression of NOX, PAI-1, and HSF1 in glyLDL-treated wild-type or HSF1-deficient mouse embryo fibroblasts (MEFs) and in leptin receptor-knockout (db/db) diabetic mice. Treatment with physiologically relevant levels of glyLDL increased superoxide and H2O2 release and the levels of NOX4 and p22phox (an essential component of multiple NOX complexes) in wild-type or HSF1-deficient MEFs. The levels of HSF1 and PAI-1 were increased by glyLDL in wild-type MEFs, but not in HSF1-deficient MEFs. Diphenyleneiodonium (a nonspecific NOX inhibitor) or small interfering RNA for p22phox prevented glyLDL-induced increases in the levels of NOX4, HSF1, or PAI-1 in MEFs. The amounts of NOX4, HSF1, and PAI-1 were elevated in hearts of db/db diabetic mice compared to wild-type mice. The results suggest that glyLDL increased the abundance of NOX4 or p22phox via an HSF1-independent pathway, but that of PAI-1 via an HSF1-dependent manner. NOX4 plays a crucial role in glyLDL-induced expression of HSF1 and PAI-1 in mouse fibroblasts. Increased expression of NOX4, HSF1, and PAI-1 was detected in cardiovascular tissue of diabetic mice. Copyright © 2013 Elsevier Inc. All rights reserved.

Mitotic spindle defects and chromosome mis-segregation induced by LDL/cholesterol-implications for Niemann-Pick C1, Alzheimer's disease, and atherosclerosis.

PubMed

Granic, Antoneta; Potter, Huntington

2013-01-01

Elevated low-density lipoprotein (LDL)-cholesterol is a risk factor for both Alzheimer's disease (AD) and Atherosclerosis (CVD), suggesting a common lipid-sensitive step in their pathogenesis. Previous results show that AD and CVD also share a cell cycle defect: chromosome instability and up to 30% aneuploidy-in neurons and other cells in AD and in smooth muscle cells in atherosclerotic plaques in CVD. Indeed, specific degeneration of aneuploid neurons accounts for 90% of neuronal loss in AD brain, indicating that aneuploidy underlies AD neurodegeneration. Cell/mouse models of AD develop similar aneuploidy through amyloid-beta (Aß) inhibition of specific microtubule motors and consequent disruption of mitotic spindles. Here we tested the hypothesis that, like upregulated Aß, elevated LDL/cholesterol and altered intracellular cholesterol homeostasis also causes chromosomal instability. Specifically we found that: 1) high dietary cholesterol induces aneuploidy in mice, satisfying the hypothesis' first prediction, 2) Niemann-Pick C1 patients accumulate aneuploid fibroblasts, neurons, and glia, demonstrating a similar aneugenic effect of intracellular cholesterol accumulation in humans 3) oxidized LDL, LDL, and cholesterol, but not high-density lipoprotein (HDL), induce chromosome mis-segregation and aneuploidy in cultured cells, including neuronal precursors, indicating that LDL/cholesterol directly affects the cell cycle, 4) LDL-induced aneuploidy requires the LDL receptor, but not Aß, showing that LDL works differently than Aß, with the same end result, 5) cholesterol treatment disrupts the structure of the mitotic spindle, providing a cell biological mechanism for its aneugenic activity, and 6) ethanol or calcium chelation attenuates lipoprotein-induced chromosome mis-segregation, providing molecular insights into cholesterol's aneugenic mechanism, specifically through its rigidifying effect on the cell membrane, and potentially explaining why ethanol consumption reduces the risk of developing atherosclerosis or AD. These results suggest a novel, cell cycle mechanism by which aberrant cholesterol homeostasis promotes neurodegeneration and atherosclerosis by disrupting chromosome segregation and potentially other aspects of microtubule physiology.

Mitotic Spindle Defects and Chromosome Mis-Segregation Induced by LDL/Cholesterol—Implications for Niemann-Pick C1, Alzheimer’s Disease, and Atherosclerosis

PubMed Central

Granic, Antoneta; Potter, Huntington

2013-01-01

Elevated low-density lipoprotein (LDL)-cholesterol is a risk factor for both Alzheimer’s disease (AD) and Atherosclerosis (CVD), suggesting a common lipid-sensitive step in their pathogenesis. Previous results show that AD and CVD also share a cell cycle defect: chromosome instability and up to 30% aneuploidy–in neurons and other cells in AD and in smooth muscle cells in atherosclerotic plaques in CVD. Indeed, specific degeneration of aneuploid neurons accounts for 90% of neuronal loss in AD brain, indicating that aneuploidy underlies AD neurodegeneration. Cell/mouse models of AD develop similar aneuploidy through amyloid-beta (Aß) inhibition of specific microtubule motors and consequent disruption of mitotic spindles. Here we tested the hypothesis that, like upregulated Aß, elevated LDL/cholesterol and altered intracellular cholesterol homeostasis also causes chromosomal instability. Specifically we found that: 1) high dietary cholesterol induces aneuploidy in mice, satisfying the hypothesis’ first prediction, 2) Niemann-Pick C1 patients accumulate aneuploid fibroblasts, neurons, and glia, demonstrating a similar aneugenic effect of intracellular cholesterol accumulation in humans 3) oxidized LDL, LDL, and cholesterol, but not high-density lipoprotein (HDL), induce chromosome mis-segregation and aneuploidy in cultured cells, including neuronal precursors, indicating that LDL/cholesterol directly affects the cell cycle, 4) LDL-induced aneuploidy requires the LDL receptor, but not Aß, showing that LDL works differently than Aß, with the same end result, 5) cholesterol treatment disrupts the structure of the mitotic spindle, providing a cell biological mechanism for its aneugenic activity, and 6) ethanol or calcium chelation attenuates lipoprotein-induced chromosome mis-segregation, providing molecular insights into cholesterol’s aneugenic mechanism, specifically through its rigidifying effect on the cell membrane, and potentially explaining why ethanol consumption reduces the risk of developing atherosclerosis or AD. These results suggest a novel, cell cycle mechanism by which aberrant cholesterol homeostasis promotes neurodegeneration and atherosclerosis by disrupting chromosome segregation and potentially other aspects of microtubule physiology. PMID:23593294

Expression of lipoprotein receptor and apolipoprotein E genes by perinatal rat lipid-laden pulmonary fibroblasts.

PubMed

McGowan, S E; Doro, M M; Jackson, S

Lipid-laden interstitial fibroblasts (LIFs) are abundant during alveolar septal formation in rats and accumulate droplets of neutral lipids. The mechanisms controlling lipid acquisition by LIFs are incompletely understood and accumulation varies during postnatal development, because lipid droplets are usually a transient phenotype. We hypothesized that plasma lipoproteins may be an important source of lipids and that the cells may alter their acquisition of lipoproteins by changing the expression of lipoprotein receptors and apolipoprotein E. We quantified the accumulation low-density lipoproteins (LDLs) and very-low-density lipoproteins (VLDLs) by LIFs and the expression of LDL and VLDL receptors mRNA and protein at various perinatal ages and found no significant age-related differences. Apolipoprotein E mRNA was maximal at postnatal day 15, whereas immunoreactive apolipoprotein E protein was maximal at gestational day 21, suggesting complex regulation. Our findings indicate that the age-related difference in the lipid droplet contents of LIFs is not primarily related to differences in LDL or VLDL receptor expression. They suggest that changes in the quantities of plasma lipoproteins, which are presented to LIFs in the lung at various perinatal ages, are more likely to be responsible for age-related alterations in lipid droplet size and abundance.

Site-specific O-glycosylation of N-terminal serine residues by polypeptide GalNAc-transferase 2 modulates human δ-opioid receptor turnover at the plasma membrane.

PubMed

Lackman, Jarkko J; Goth, Christoffer K; Halim, Adnan; Vakhrushev, Sergey Y; Clausen, Henrik; Petäjä-Repo, Ulla E

2018-01-01

G protein-coupled receptors (GPCRs) are an important protein family of signalling receptors that govern a wide variety of physiological functions. The capacity to transmit extracellular signals and the extent of cellular response are largely determined by the amount of functional receptors at the cell surface that is subject to complex and fine-tuned regulation. Here, we demonstrate that the cell surface expression level of an inhibitory GPCR, the human δ-opioid receptor (hδOR) involved in pain and mood regulation, is modulated by site-specific N-acetylgalactosamine (GalNAc) -type O-glycosylation. Importantly, we identified one out of the 20 polypeptide GalNAc-transferase isoforms, GalNAc-T2, as the specific regulator of O-glycosylation of Ser6, Ser25 and Ser29 in the N-terminal ectodomain of the receptor. This was demonstrated by in vitro glycosylation assays using peptides corresponding to the hδOR N-terminus, Vicia villosa lectin affinity purification of receptors expressed in HEK293 SimpleCells capable of synthesizing only truncated O-glycans, GalNAc-T edited cell line model systems, and site-directed mutagenesis of the putative O-glycosylation sites. Interestingly, a single-nucleotide polymorphism, at residue 27 (F27C), was found to alter O-glycosylation of the receptor in efficiency as well as in glycosite usage. Furthermore, flow cytometry and cell surface biotinylation assays using O-glycan deficient CHO-ldlD cells revealed that the absence of O-glycans results in decreased receptor levels at the plasma membrane due to enhanced turnover. In addition, mutation of the identified O-glycosylation sites led to a decrease in the number of ligand-binding competent receptors and impaired agonist-mediated inhibition of cyclic AMP accumulation in HEK293 cells. Thus, site-specific O-glycosylation by a selected GalNAc-T isoform can increase the stability of a GPCR, in a process that modulates the constitutive turnover and steady-state levels of functional receptors at the cell surface. Copyright © 2017 Elsevier Inc. All rights reserved.

JCL roundtable: drug treatment of severe forms of familial hypercholesterolemia.

PubMed

Brown, W Virgil; Rader, Daniel J; Goldberg, Anne C

2014-01-01

Clinical lipidologists are often asked to manage patients with severely elevated low-density lipoprotein cholesterol (LDL-C) and other apolipoprotein B-containing lipoproteins. Statins at maximum doses and in combination with other drugs may not achieve adequate reductions in LDL-C in such patients. The most dramatic elevations are usually in patients with genetic abnormalities in the LDL receptor gene on both chromosome pairs. LDL-C values well in excess of 400 mg/dL are not fully responsive to current treatments. In the past few months, the Food and Drug Administration has approved 2 new drugs for special use in such patients; these are mipomersen and lomitapide. During the National Lipid Association's Scientific Sessions, 2 highly experienced clinician scientists who have completed research studies with these agents agreed to answer questions pertinent to the prescription use of these agents. These scientists are Dr Anne Goldberg from Washington University in St. Louis and Dr Daniel Rader from the University of Pennsylvania. Copyright © 2014 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Purple grape juice improves endothelial function and reduces the susceptibility of LDL cholesterol to oxidation in patients with coronary artery disease.

PubMed

Stein, J H; Keevil, J G; Wiebe, D A; Aeschlimann, S; Folts, J D

1999-09-07

In vitro, the flavonoid components of red wine and purple grape juice are powerful antioxidants that induce endothelium-dependent vasodilation of vascular rings derived from rat aortas and human coronary arteries. Although improved endothelial function and inhibition of LDL oxidation may be potential mechanisms by which red wine and flavonoids reduce cardiovascular risk, the in vivo effects of grape products on endothelial function and LDL oxidation have not been investigated. This study assessed the effects of ingesting purple grape juice on endothelial function and LDL susceptibility to oxidation in patients with coronary artery disease (CAD). Fifteen adults with angiographically documented CAD ingested 7.7+/-1.2 mL. kg(-1). d(-1) of purple grape juice for 14 days. Flow-mediated vasodilation (FMD) was measured using high-resolution brachial artery ultrasonography. Susceptibility of LDL particles to oxidation was determined from the rate of conjugated diene formation after exposure to copper chloride. At baseline, FMD was impaired (2.2+/-2. 9%). After ingestion of grape juice, FMD increased to 6.4+/-4.7% (P=0.003). In a linear regression model that included age, artery diameter, lipid values, and use of lipid-lowering and antioxidant therapies, the effect of grape juice on FMD remained significant (mean change 4.2+/-4.4%, P<0.001). After ingestion of grape juice, lag time increased by 34.5% (P=0.015). Short-term ingestion of purple grape juice improves FMD and reduces LDL susceptibility to oxidation in CAD patients. Improved endothelium-dependent vasodilation and prevention of LDL oxidation are potential mechanisms by which flavonoids in purple grape products may prevent cardiovascular events, independent of alcohol content.

Endoplasmic Reticulum Stress Links Oxidative Stress to Impaired Pancreatic Beta-Cell Function Caused by Human Oxidized LDL.

PubMed

Plaisance, Valérie; Brajkovic, Saška; Tenenbaum, Mathie; Favre, Dimitri; Ezanno, Hélène; Bonnefond, Amélie; Bonner, Caroline; Gmyr, Valéry; Kerr-Conte, Julie; Gauthier, Benoit R; Widmann, Christian; Waeber, Gérard; Pattou, François; Froguel, Philippe; Abderrahmani, Amar

2016-01-01

Elevated plasma concentration of the pro-atherogenic oxidized low density lipoprotein cholesterol (LDL) triggers adverse effects in pancreatic beta-cells and is associated with type 2 diabetes. Here, we investigated whether the endoplasmic reticulum (ER) stress is a key player coupling oxidative stress to beta-cell dysfunction and death elicited by human oxidized LDL. We found that human oxidized LDL activates ER stress as evidenced by the activation of the inositol requiring 1α, and the elevated expression of both DDIT3 (also called CHOP) and DNAJC3 (also called P58IPK) ER stress markers in isolated human islets and the mouse insulin secreting MIN6 cells. Silencing of Chop and inhibition of ER stress markers by the chemical chaperone phenyl butyric acid (PBA) prevented cell death caused by oxidized LDL. Finally, we found that oxidative stress accounts for activation of ER stress markers induced by oxidized LDL. Induction of Chop/CHOP and p58IPK/P58IPK by oxidized LDL was mimicked by hydrogen peroxide and was blocked by co-treatment with the N-acetylcystein antioxidant. As a conclusion, the harmful effects of oxidized LDL in beta-cells requires ER stress activation in a manner that involves oxidative stress. This mechanism may account for impaired beta-cell function in diabetes and can be reversed by antioxidant treatment.

LDL-C levels in older people: Cholesterol homeostasis and the free radical theory of ageing converge.

PubMed

Mc Auley, Mark T; Mooney, Kathleen M

2017-07-01

The cardiovascular disease (CVD) risk factor, low density lipoprotein cholesterol (LDL-C) increases with age, up until the midpoint of life in males and females. However, LDL-C can decrease with age in older men and women. Intriguingly, a recent systematic review also revealed an inverse association between LDL-C levels and cardiovascular mortality in older people; low levels of LDL-C were associated with reduced risk of mortality. Such findings are puzzling and require a biological explanation. In this paper a hypothesis is proposed to explain these observations. We hypothesize that the free radical theory of ageing (FRTA) together with disrupted cholesterol homeostasis can account for these observations. Based on this hypothesis, dysregulated hepatic cholesterol homeostasis in older people is characterised by two distinct metabolic states. The first state accounts for an older person who has elevated plasma LDL-C. This state is underpinned by the FRTA which suggests there is a decrease in cellular antioxidant capacity with age. This deficiency enables hepatic reactive oxidative species (ROS) to induce the total activation of HMG-CoA reductase, the key rate limiting enzyme in cholesterol biosynthesis. An increase in cholesterol synthesis elicits a corresponding rise in LDL-C, due to the downregulation of LDL receptor synthesis, and increased production of very low density lipoprotein cholesterol (VLDL-C). In the second state of dysregulation, ROS also trigger the total activation of HMG-CoA reductase. However, due to an age associated decrease in the activity of cholesterol-esterifying enzyme, acyl CoA: cholesterol acyltransferase, there is restricted conversion of excess free cholesterol (FC) to cholesterol esters. Consequently, the secretion of VLDL-C drops, and there is a corresponding decrease in LDL-C. As intracellular levels of FC accumulate, this state progresses to a pathophysiological condition akin to nonalcoholic fatty liver disease. It is our conjecture this deleterious state has the potential to account for the inverse association between LDL-C level and CVD risk observed in older people. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synergetic cholesterol-lowering effects of main alkaloids from Rhizoma Coptidis in HepG2 cells and hypercholesterolemia hamsters.

PubMed

Kou, Shuming; Han, Bing; Wang, Yue; Huang, Tao; He, Kai; Han, Yulong; Zhou, Xia; Ye, Xiaoli; Li, Xuegang

2016-04-15

Hyperlipidemia contributes to the progression of cardiovascular diseases. Main alkaloids from Rhizoma Coptidis including berberine (BBR), coptisine (COP), palmatine (PAL), epiberberine (EPI) and jatrorrhizine (JAT), improved dyslipidemia in hypercholesterolemic hamsters to a different degree. In this study, HepG2 cells and hypercholesterolemic hamsters were used to investigate the synergetic cholesterol-lowering efficacy of these five main alkaloids. The cellular lipid and cholesterol accumulation and in HepG2 cells were evaluated by Oil Red O staining and HPLC analysis. LDL receptor, 3-Hydroxy-3-methylglutaryl CoA reductase (HMGCR) and cholesterol 7-alpha-hydroxylase (CYP7A1) that involving cholesterol metabolism in HepG2 cells were measured by qRT-PCR, western blot and immunofluorescence analysis. The serum profiles including total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-c) and high-density lipoprotein cholesterol (HDL-c), as well as TC and total bile acids (TBA) of feces in hypercholesterolemic hamsters were also measured. As compared to single alkaloids, the combination of five main alkaloids (COM) reduced the lipid and cholesterol accumulation in HepG2 cells more effectively and performed an advantageous effect on controlling TC, TG, LDL-c and HDL-c in hypercholesterolemic hamsters. More effective reduction of TBA and TC levels in feces of hamsters were achieved after the administration of COM. These effects were derived from the up-regulation of LDL receptor and CYP7A1, as well as HMGCR downregulation. Our results demonstrated that COM showed a synergetic cholesterol-lowering efficacy, which was better than single alkaloids and it might be considered as a potential therapy for hypercholesterolemia. Copyright © 2016 Elsevier Inc. All rights reserved.

Calnuc Function in Endosomal Sorting of Lysosomal Receptors.

PubMed

Larkin, Heidi; Costantino, Santiago; Seaman, Matthew N J; Lavoie, Christine

2016-04-01

Calnuc is a ubiquitous Ca(2+)-binding protein present on the trans-Golgi network (TGN) and endosomes. However, the precise role of Calnuc in these organelles is poorly characterized. We previously highlighted the role of Calnuc in the transport of LRP9, a new member of a low-density lipoprotein (LDL) receptor subfamily that cycles between the TGN and endosomes. The objective of this study was to explore the role of Calnuc in the endocytic sorting of mannose-6-phosphate receptor (MPR) and Sortilin, two well-characterized lysosomal receptors that transit between the TGN and endosomes. Using biochemical and microscopy assays, we showed that Calnuc depletion [by small interfering RNA (siRNA)] causes the misdelivery to and degradation in lysosomes of cationic-independent mannose-6-phosphate receptor (CI-MPR) and Sortilin due to a defect in the endosomal recruitment of retromers, which are key components of the endosome-to-Golgi retrieval machinery. Indeed, we demonstrated that Calnuc depletion impairs the activation and membrane association of Rab7, a small G protein required for the endosomal recruitment of retromers. Overall, our data indicate a novel role for Calnuc in the endosome-to-TGN retrograde transport of lysosomal receptors through the regulation of Rab7 activity and the recruitment of retromers to endosomes. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

LDL receptor-related protein mediates cell-surface clustering and hepatic sequestration of chylomicron remnants in LDLR-deficient mice.

PubMed

Yu, K C; Chen, W; Cooper, A D

2001-06-01

It has been proposed that in the liver, chylomicron remnants (lipoproteins carrying dietary lipid) may be sequestered before being internalized by hepatocytes. To study this, chylomicron remnants labeled with a fluorescent dye were perfused into isolated livers of LDL receptor-deficient (LDLR-deficient) mice (Ldlr(-/-)) and examined by confocal microscopy. In contrast to livers from normal mice, there was clustering of the chylomicron remnants on the cell surface in the space of DISSE: These remnant clusters colocalized with clusters of LDLR-related protein (LRP) and could be eliminated by low concentrations of receptor-associated protein, an inhibitor of LRP. When competed with ligands of heparan sulfate proteoglycans (HSPGs), the remnant clusters still appeared but were fewer in number, although syndecans (membrane HSPGs) colocalized with the remnant clusters. This suggests that the clustering of remnants is not dependent on syndecans but that the syndecans may modify the binding of remnants. These results establish that sequestration is a novel process, the clustering of remnants in the space of DISSE: The clustering involves remnants binding to the LRP, and this may be stabilized by binding with syndecans, eventually followed by endocytosis.

Accumulation of cholesterol and increased demand for zinc in serum-deprived RPE cells

PubMed Central

Mishra, Sanghamitra; Peterson, Katherine; Yin, Lili; Berger, Alan; Fan, Jianguo

2016-01-01

Purpose Having observed that confluent ARPE-19 cells (derived from human RPE) survive well in high-glucose serum-free medium (SFM) without further feeding for several days, we investigated the expression profile of RPE cells under the same conditions. Methods Expression profiles were examined with microarray and quantitative PCR (qPCR) analyses, followed by western blot analysis of key regulated proteins. The effects of low-density lipoprotein (LDL) and zinc supplementation were examined with qPCR. Immunofluorescence was used to localize the LDL receptor and to examine LDL uptake. Cellular cholesterol levels were measured with filipin binding. Expression patterns in primary fetal RPE cells were compared using qPCR. Results Microarray analyses of gene expression in ARPE-19, confirmed with qPCR, showed upregulation of lipid and cholesterol biosynthesis pathways in SFM. At the protein level, the cholesterol synthesis control factor SRBEF2 was activated, and other key lipid synthesis proteins increased. Supplementation of SFM with LDL reversed the upregulation of lipid and cholesterol synthesis genes, but not of cholesterol transport genes. The LDL receptor relocated to the plasma membrane, and LDL uptake was activated by day 5–7 in SFM, suggesting increased demand for cholesterol. Confluent ARPE-19 cells in SFM accumulated intracellular cholesterol, compared with cells supplemented with serum, over 7 days. Over the same time course in SFM, the expression of metallothioneins decreased while the major zinc transporter was upregulated, consistent with a parallel increase in demand for zinc. Supplementation with zinc reversed expression changes for metallothionein genes, but not for other zinc-related genes. Similar patterns of regulation were also seen in primary fetal human RPE cells in SFM. Conclusions ARPE-19 cells respond to serum deprivation and starvation with upregulation of the lipid and cholesterol pathways, accumulation of intracellular cholesterol, and increased demand for zinc. Similar trends are seen in primary fetal RPE cells. Cholesterol accumulation basal to RPE is a prominent feature of age-related macular degeneration (AMD), while dietary zinc is protective. It is conceivable that accumulating defects in Bruch’s membrane and dysfunction of the choriocapillaris could impede transport between RPE and vasculature in AMD. Thus, this pattern of response to serum deprivation in RPE-derived cells may have relevance for some aspects of the progression of AMD. PMID:28003730

Lipid-lowering effects of TAK-475, a squalene synthase inhibitor, in animal models of familial hypercholesterolemia.

PubMed

Amano, Yuichiro; Nishimoto, Tomoyuki; Tozawa, Ryu ichi; Ishikawa, Eiichiro; Imura, Yoshimi; Sugiyama, Yasuo

2003-04-11

The lipid-lowering effects of 1-[2-[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-1,2,3,5-tetrahydro-2-oxo-5-(2,3-dimethoxyphenyl)-4,1-benzoxazepine-3-yl] acetyl] piperidin-4-acetic acid (TAK-475), a novel squalene synthase inhibitor, were examined in two models of familial hypercholesterolemia, low-density lipoprotein (LDL) receptor knockout mice and Watanabe heritable hyperlipidemic (WHHL) rabbits. Two weeks of treatment with TAK-475 in a diet admixture (0.02% and 0.07%; approximately 30 and 110 mg/kg/day, respectively) significantly lowered plasma non-high-density lipoprotein (HDL) cholesterol levels by 19% and 41%, respectively, in homozygous LDL receptor knockout mice. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, simvastatin and atorvastatin (in 0.02% and 0.07% admixtures), also reduced plasma levels of non-HDL cholesterol. In homozygous WHHL rabbits, 4 weeks of treatment with TAK-475 (0.27%; approximately 100 mg/kg/day) lowered plasma total cholesterol, triglyceride and phospholipid levels by 17%, 52% and 26%, respectively. In Triton WR-1339-treated rabbits, TAK-475 inhibited to the same extent the rate of secretion from the liver of the cholesterol, triglyceride and phospholipid components of very-low-density lipoprotein (VLDL). These results suggest that the lipid-lowering effects of TAK-475 in WHHL rabbits are based partially on the inhibition of secretion of VLDL from the liver. TAK-475 had no effect on plasma aspartate aminotransferase and alanine aminotransferase activities. Thus, the squalene synthase inhibitor TAK-475 revealed lipid-lowering effects in both LDL receptor knockout mice and WHHL rabbits.

Zinc oxide nanoparticles induce migration and adhesion of monocytes to endothelial cells and accelerate foam cell formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suzuki, Yuka; Tada-Oikawa, Saeko; Ichihara, Gaku

Metal oxide nanoparticles are widely used in industry, cosmetics, and biomedicine. However, the effects of exposure to these nanoparticles on the cardiovascular system remain unknown. The present study investigated the effects of nanosized TiO{sub 2} and ZnO particles on the migration and adhesion of monocytes, which are essential processes in atherosclerogenesis, using an in vitro set-up of human umbilical vein endothelial cells (HUVECs) and human monocytic leukemia cells (THP-1). We also examined the effects of exposure to nanosized metal oxide particles on macrophage cholesterol uptake and foam cell formation. The 16-hour exposure to ZnO particles increased the level of monocytemore » chemotactic protein-1 (MCP-1) and induced the migration of THP-1 monocyte mediated by increased MCP-1. Exposure to ZnO particles also induced adhesion of THP-1 cells to HUVECs. Moreover, exposure to ZnO particles, but not TiO{sub 2} particles, upregulated the expression of membrane scavenger receptors of modified LDL and increased cholesterol uptake in THP-1 monocytes/macrophages. In the present study, we found that exposure to ZnO particles increased macrophage cholesterol uptake, which was mediated by an upregulation of membrane scavenger receptors of modified LDL. These results suggest that nanosized ZnO particles could potentially enhance atherosclerogenesis and accelerate foam cell formation. - Highlights: • Effects of metal oxide nanoparticles on foam cell formation were investigated. • Exposure to ZnO nanoparticles induced migration and adhesion of monocytes. • Exposure to ZnO nanoparticles increased macrophage cholesterol uptake. • Expression of membrane scavenger receptors of modified LDL was also increased. • These effects were not observed after exposure to TiO{sub 2} nanoparticles.« less

Blockade of cholesterol absorption by ezetimibe reveals a complex homeostatic network in enterocytes[S

PubMed Central

Engelking, Luke J.; McFarlane, Matthew R.; Li, Christina K.; Liang, Guosheng

2012-01-01

Enterocyte cholesterol homeostasis reflects aggregated rates of sterol synthesis, efflux, and uptake from plasma and gut lumen. Cholesterol synthesis and LDL uptake are coordinately regulated by sterol regulatory element-binding proteins (SREBP), whereas sterol efflux is regulated by liver X receptors (LXR). How these processes are coordinately regulated in enterocytes, the site of cholesterol absorption, is not well understood. Here, we treat mice with ezetimibe to investigate the effect of blocking cholesterol absorption on intestinal SREBPs, LXRs, and their effectors. Ezetimibe increased nuclear SREBP-2 8-fold. HMG-CoA reductase (HMGR) and LDL receptor (LDLR) mRNA levels increased less than 3-fold, whereas their protein levels increased 30- and 10-fold, respectively. Expression of inducible degrader of LDLR (IDOL), an LXR-regulated gene that degrades LDLRs, was reduced 50% by ezetimibe. Coadministration of ezetimibe with the LXR agonist T0901317 abolished the reduction in IDOL and prevented the increase in LDLR protein. Ezetimibe-stimulated LDLR expression was independent of proprotein convertase subtilisin/kexin type 9 (PSCK9), a protein that degrades LDLRs. To maintain cholesterol homeostasis in the face of ezetimibe, enterocytes boost LDL uptake by increasing LDLR number, and they boost sterol synthesis by increasing HMGR and other cholesterologenic genes. These studies reveal a hitherto undescribed homeostatic network in enterocytes triggered by blockade of cholesterol absorption. PMID:22523394

Antisense inhibition of proprotein convertase subtilisin/kexin type 9 reduces serum LDL in hyperlipidemic mice.

PubMed

Graham, Mark J; Lemonidis, Kristina M; Whipple, Charles P; Subramaniam, Amuthakannan; Monia, Brett P; Crooke, Stanley T; Crooke, Rosanne M

2007-04-01

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a member of a family of proteases that is thought to promote the degradation of the low density lipoprotein receptor (LDLR) through an as yet undefined mechanism. We developed second generation antisense oligonucleotide (ASO) inhibitors targeting murine PCSK9 to determine their potential as lipid-lowering agents. Administration of a PCSK9 ASO to high fat-fed mice for 6 weeks reduced total cholesterol and LDL by 53% and 38%, respectively. Moreover, inhibition of PCSK9 expression resulted in a 2-fold increase in hepatic LDLR protein levels. This phenotype closely resembles that reported previously in Pcsk9-deficient mice. The absence of cholesterol lowering in Ldlr-deficient mice effectively demonstrated a critical role for this receptor in mediating the lipid-lowering effects of PCSK9 inhibition. Antisense inhibition of PCSK9 is an attractive and novel therapeutic approach for treating hypercholesterolemia in human.

Effect of Hyp delivery system on PKCα activity: What will happen after pkcα gene silencing and Hyp photo-activation?

NASA Astrophysics Data System (ADS)

Misuth, Matus; Joniova, Jaroslava; Ferencakova, Michaela; Miskovsky, Pavol; Nadova, Zuzana

2015-08-01

Low density lipoproteins (LDL) are considered as suitable natural in vivo delivery system for hydrophobic photosensitizers (pts) such as hypericin (Hyp) and it was shown that over expression of LDL-receptors in tumor cells can be used for specific targeting. Activation of pts by irradiation results in a formation of reactive oxygen species (ROS) at the place of light application and starts destructive mechanism. PKCα plays a key role in the cell survival and its overexpression was observed in glioma cell lines. In the present study we aim to present the effectivity of the pts delivery in the glioma cells and consequences of silencing pkcα gene on cell death/survival after Hyp photo-activation. Pts can be delivered through two pathways: endocytosis - when cells are incubated with LDL/Hyp complex and Hyp transport through cellular membrane without any carrier. Preliminary results show that incubation of cells with or without LDL leads to PKCα activation. Photo-activated Hyp seems to be more effective in terms of apoptosis induction when compared to photo-activated LDL/Hyp complex. We have evaluated the influence of photo-activated Hyp on cell death in non-transfected and transfected (PKCα-) human glioma cells (U87-MG). Level of ROS production and type of cell death was notably affected by silencing pkca gene resulting in significant increase of necrosis after Hyp photo-activation.

LOX-1 activation by oxLDL triggers an epithelial mesenchymal transition and promotes tumorigenic potential in prostate cancer cells.

PubMed

González-Chavarría, I; Fernandez, E; Gutierrez, N; González-Horta, E E; Sandoval, F; Cifuentes, P; Castillo, C; Cerro, R; Sanchez, O; Toledo, Jorge R

2018-02-01

Obesity is related to an increased risk of developing prostate cancer with high malignancy stages or metastasis. Recent results demonstrated that LOX-1, a receptor associated with obesity and atherosclerosis, is overexpressed in advanced and metastatic prostate cancer. Furthermore, high levels of oxLDL, the main ligand for LOX-1, have been found in patients with advanced prostate cancer. However, the role of LOX-1 in prostate cancer has not been unraveled completely yet. Here, we show that LOX-1 is overexpressed in prostate cancer cells and its activation by oxLDL promotes an epithelial to mesenchymal transition, through of lowered expression of epithelial markers (E-cadherin and plakoglobin) and an increased expression of mesenchymal markers (vimentin, N-cadherin, snail, slug, MMP-2 and MMP-9). Consequently, LOX-1 activation by oxLDL promotes actin cytoskeleton restructuration and MMP-2 and MMP-9 activity inducing prostate cancer cell invasion and migration. Additionally, LOX-1 increased the tumorigenic potential of prostate cancer cells and its expression was necessary for tumor growth in nude mice. In conclusion, our results suggest that oxLDL/LOX-1 could be ones of mechanisms that explain why obese patients with prostate cancer have an accelerated tumor progression and a greater probability of developing metastasis. Copyright © 2017 Elsevier B.V. All rights reserved.

Pleiotropic Effects of Statins on the Cardiovascular System

PubMed Central

Oesterle, Adam; Laufs, Ulrich; Liao, James K

2017-01-01

The 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors (statins), have been used for thirty years to prevent coronary artery disease and stroke. Their primary mechanism of action is the lowering of serum cholesterol through inhibiting hepatic cholesterol biosynthesis thereby upregulating the hepatic low-density lipoprotein (LDL) receptors and increasing the clearance of LDL-cholesterol (LDL-C). Statins may exert cardiovascular protective effects that are independent of LDL-C lowering called “pleiotropic” effects. Because statins inhibit the production of isoprenoid intermediates in the cholesterol biosynthetic pathway, the post-translational prenylation of small guanosine triphosphate binding proteins such as Rho and Rac, and their downstream effectors such as Rho kinase and nicotinamide adenine dinucleotide phosphate oxidases are also inhibited. In cell culture and animal studies, these effects alter the expression of endothelial nitric oxide synthase, the stability of atherosclerotic plaques, the production of pro-inflammatory cytokines and reactive oxygen species, the reactivity of platelets, and the development of cardiac hypertrophy and fibrosis. The relative contributions of statin pleiotropy to clinical outcomes, however, remain a matter of debate and are hard to quantify since the degree of isoprenoid inhibition by statins correlates to some extent with the amount of LDL-C reduction. This review examines some of the currently proposed molecular mechanisms for statin pleiotropy and discusses whether they could have any clinical relevance in cardiovascular disease. PMID:28057795

Impact of Ezetimibe Alone or in Addition to a Statin on Plasma PCSK9 Concentrations in Patients with Type 2 Diabetes and Hypercholesterolemia: A Pilot Study.

PubMed

Miyoshi, Toru; Nakamura, Keigo; Doi, Masayuki; Ito, Hiroshi

2015-06-01

The increase in proprotein convertase subtilisin/kexin type 9 (PCSK9) leads to low-density lipoprotein (LDL) receptor degradation. Statins significantly reduce LDL-cholesterol levels, but upregulate PCSK9. This study evaluated the effect of ezetimibe monotherapy or ezetimibe in combination with a statin on serum levels of PCSK9 in patients with type 2 diabetes and hypercholesterolemia. Ezetimibe treatment was given to ten patients with diabetes without statin therapy and ten patients with statin therapy. Plasma levels of PCSK9 were examined at baseline and 24 weeks after treatment. At baseline, PCSK9 concentrations in patients with statin therapy were significantly higher than those in patients without statin use and in control subjects [median (25th-75th percentile) 411 (272-467) and 382 (356-453) ng/mL, respectively, p < 0.01]. After ezetimibe treatment for 24 weeks, LDL-cholesterol, triglyceride and remnant-like lipoprotein cholesterol were significantly decreased in both groups. However, PCSK9 concentration did not change compared with baseline measurements in both groups. The percentage change in LDL-cholesterol after ezetimibe therapy for 24 weeks was not correlated with the percentage change in PCSK9 concentration. Ezetimibe may reduce LDL-cholesterol levels without affecting PCSK9 in patients with type 2 diabetes and hypercholesterolemia.

Bivariate and multivariate analyses of the correlations between stability of the erythrocyte membrane, serum lipids and hematological variables.

PubMed

Bernardino Neto, M; de Avelar, E B; Arantes, T S; Jordão, I A; da Costa Huss, J C; de Souza, T M T; de Souza Penha, V A; da Silva, S C; de Souza, P C A; Tavares, M; Penha-Silva, N

2013-01-01

The observation that the fluidity must remain within a critical interval, outside which the stability and functionality of the cell tends to decrease, shows that stability, fluidity and function are related and that the measure of erythrocyte stability allows inferences about the fluidity or functionality of these cells. This study determined the biochemical and hematological variables that are directly or indirectly related to erythrocyte stability in a population of 71 volunteers. Data were evaluated by bivariate and multivariate analysis. The erythrocyte stability showed a greater association with hematological variables than the biochemical variables. The RDW stands out for its strong correlation with the stability of erythrocyte membrane, without being heavily influenced by other factors. Regarding the biochemical variables, the erythrocyte stability was more sensitive to LDL-C. Erythrocyte stability was significantly associated with RDW and LDL-C. Thus, the level of LDL-C is a consistent link between stability and functionality, suggesting that a measure of stability could be more one indirect parameter for assessing the risk of degenerative processes associated with high levels of LDL-C.

Catabolism of native and oxidized low density lipoproteins: in vivo insights from small animal positron emission tomography studies.

PubMed

Pietzsch, J; Bergmann, R; Wuest, F; Pawelke, B; Hultsch, C; van den Hoff, J

2005-12-01

The human organism is exposed to numerous processes that generate reactive oxygen species (ROS). ROS may directly or indirectly cause oxidative modification and damage of proteins. Protein oxidation is regarded as a crucial event in the pathogenesis of various diseases ranging from rheumatoid arthritis to Alzheimer's disease and atherosclerosis. As a representative example, oxidation of low density lipoprotein (LDL) is regarded as a crucial event in atherogenesis. Data concerning the role of circulating oxidized LDL (oxLDL) in the development and outcome of diseases are scarce. One reason for this is the shortage of methods for direct assessment of the metabolic fate of circulating oxLDL in vivo. We present an improved methodology based on the radiolabelling of apoB-100 of native LDL (nLDL) and oxLDL, respectively, with the positron emitter fluorine-18 ((18)F) by conjugation with N-succinimidyl-4-[(18)F]fluorobenzoate ([(18)F]SFB). Radiolabelling of both nLDL and oxLDL using [(18)F]SFB causes neither additional oxidative structural modifications of LDL lipids and proteins nor alteration of their biological activity and functionality, respectively, in vitro. The method was further evaluated with respect to the radiopharmacological properties of both [(18)F]fluorobenzoylated nLDL and oxLDL by biodistribution studies in male Wistar rats. The metabolic fate of [(18)F]fluorobenzoylated nLDL and oxLDL in rats in vivo was further delineated by dynamic positron emission tomography (PET) using a dedicated small animal tomograph (spatial resolution of 2 mm). From this study we conclude that the use of [(18)F]FB-labelled LDL particles is an attractive alternative to, e.g., LDL iodination methods, and is of value to characterize and to discriminate the kinetics and the metabolic fate of nLDL and oxLDL in small animals in vivo.

Functional Roles of the Interaction of APP and Lipoprotein Receptors

PubMed Central

Pohlkamp, Theresa; Wasser, Catherine R.; Herz, Joachim

2017-01-01

The biological fates of the key initiator of Alzheimer’s disease (AD), the amyloid precursor protein (APP), and a family of lipoprotein receptors, the low-density lipoprotein (LDL) receptor-related proteins (LRPs) and their molecular roles in the neurodegenerative disease process are inseparably interwoven. Not only does APP bind tightly to the extracellular domains (ECDs) of several members of the LRP group, their intracellular portions are also connected through scaffolds like the one established by FE65 proteins and through interactions with adaptor proteins such as X11/Mint and Dab1. Moreover, the ECDs of APP and LRPs share common ligands, most notably Reelin, a regulator of neuronal migration during embryonic development and modulator of synaptic transmission in the adult brain, and Agrin, another signaling protein which is essential for the formation and maintenance of the neuromuscular junction (NMJ) and which likely also has critical, though at this time less well defined, roles for the regulation of central synapses. Furthermore, the major independent risk factors for AD, Apolipoprotein (Apo) E and ApoJ/Clusterin, are lipoprotein ligands for LRPs. Receptors and ligands mutually influence their intracellular trafficking and thereby the functions and abilities of neurons and the blood-brain-barrier to turn over and remove the pathological product of APP, the amyloid-β peptide. This article will review and summarize the molecular mechanisms that are shared by APP and LRPs and discuss their relative contributions to AD. PMID:28298885

LRP5 and plasma cholesterol levels modulate the canonical Wnt pathway in peripheral blood leukocytes.

PubMed

Borrell-Pages, Maria; Carolina Romero, July; Badimon, Lina

2015-08-01

Inflammation is triggered after invasion or injury to restore homeostasis. Although the activation of Wnt/β-catenin signaling is one of the first molecular responses to cellular damage, its role in inflammation is still unclear. It was our hypothesis that the low-density lipoprotein (LDL) receptor-related protein 5 (LRP5) and the canonical Wnt signaling pathway are modulators of inflammatory mechanisms. Wild-type (WT) and LRP5(-/-) mice were fed a hypercholesterolemic (HC) diet to trigger dislipidemia and chronic inflammation. Diets were supplemented with plant sterol esters (PSEs) to induce LDL cholesterol lowering and the reduction of inflammation. HC WT mice showed increased serum cholesterol levels that correlated with increased Lrp5 and Wnt/β-catenin gene expression while in the HC LRP5(-/-) mice Wnt/β-catenin pathway was shut down. Functionally, HC induced pro-inflammatory gene expression in LRP5(-/-) mice, suggesting an inhibitory role of the Wnt pathway in inflammation. Dietary PSE administration downregulated serum cholesterol levels in WT and LRP5(-/-) mice. Furthermore, in WT mice PSE increased anti-inflammatory genes expression and inhibited Wnt/β-catenin activation. Hepatic gene expression of Vldlr, Lrp2 and Lrp6 was increased after HC feeding in WT mice but not in LRP5(-/-) mice, suggesting a role for these receptors in the clearance of plasmatic lipoproteins. Finally, an antiatherogenic role for LRP5 was demonstrated as HC LRP5(-/-) mice developed larger aortic atherosclerotic lesions than WT mice. Our results show an anti-inflammatory, pro-survival role for LRP5 and the Wnt signaling pathway in peripheral blood leukocytes.

From mucolipidosis type IV to Ebola: TRPML and two-pore channels at the crossroads of endo-lysosomal trafficking and disease.

PubMed

Grimm, Christian; Butz, Elisabeth; Chen, Cheng-Chang; Wahl-Schott, Christian; Biel, Martin

2017-11-01

What do lysosomal storage disorders such as mucolipidosis type IV have in common with Ebola, cancer cell migration, or LDL-cholesterol trafficking? LDL-cholesterol, certain bacterial toxins and viruses, growth factors, receptors, integrins, macromolecules destined for degradation or secretion are all sorted and transported via the endolysosomal system (ES). There are several pathways known in the ES, e.g. the degradation, the recycling, or the retrograde trafficking pathway. The ES comprises early and late endosomes, lysosomes and recycling endosomes as well as autophagosomes and lysosome related organelles. Contact sites between the ES and the endoplasmic reticulum or the Golgi apparatus may also be considered part of it. Dysfunction of this complex intracellular machinery can cause or contribute to the development of a number of diseases ranging from neurodegenerative, infectious, or metabolic diseases to retinal and pigmentation disorders as well as cancer and autophagy-related diseases. Endolysosomal ion channels such as mucolipins (TRPMLs) and two-pore channels (TPCs) play an important role in intracellular cation/calcium signaling and homeostasis and appear to critically contribute to the proper function of the endolysosomal trafficking network. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cholesterol accumulation in tissues of the Niemann-pick type C mouse is determined by the rate of lipoprotein-cholesterol uptake through the coated-pit pathway in each organ.

PubMed

Xie, C; Turley, S D; Dietschy, J M

1999-10-12

Niemann-Pick type C (NPC) disease is associated with the accumulation of unesterified cholesterol in nearly all tissues and with progressive neurodegeneration. A murine model of this disease, the NPC mouse, was used to determine whether this sequestered cholesterol represented sterol carried in low density lipoprotein (LDL) and chylomicrons (CMs) taken up into the tissues through the coated-pit pathway. By 7 weeks of age, the sterol pool in the NPC mice had increased from 2,165 to 5,669 mg/kg body weight because of the daily sequestration of 67 mg of cholesterol per kg in the various organs. This was 7-fold greater than the rate of accumulation in control mice. The rate of LDL clearance in the NPC mouse was normal (523 ml/day per kg) and accounted for the uptake of 78 mg/day per kg of cholesterol in LDL whereas 8 mg/day per kg was taken up from CMs. Deletion of the LDL receptor in NPC mice altered the concentration of unesterified cholesterol in every organ in a manner consistent with the changes also observed in the rate of LDL cholesterol uptake in those tissues. Similarly, altering the flow of cholesterol to the liver through the CM pathway changed the concentration of unesterified cholesterol in that organ. Together, these observations strongly support the conclusion that, in NPC disease, it is cholesterol carried in LDL and CMs that is sequestered in the tissues and not sterol that is newly synthesized and carried in high density lipoprotein.

Novel lipid modifying drugs to lower LDL cholesterol.

PubMed

Cupido, Arjen J; Reeskamp, Laurens F; Kastelein, John J P

2017-08-01

Statins have long been the cornerstone for the prevention of cardiovascular disease (CVD). However, because of perceived adverse effects and insufficient efficacy in certain groups of patients, considerable interest exists in the search for alternatives to lower LDL-cholesterol (LDL-C), and the recent approvals of proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors underlines the success of this quest. Here, we give an updated overview on the most recent developments in the area of LDL-C lowering agents. The clinical effects of the PCSK9 inhibitors are promising, especially now that the FOURIER and SPIRE programmes are published. Most cholesterylester-transfer protein inhibitors, however, except anacetrapib, have been discontinued because of either toxicity or lack of efficacy in large cardiovascular outcome trials. Other agents - like mipomersen, lomitapide, ETC-1002, and gemcabene - aim to lower LDL-C in different ways than solely through the LDL receptor, opening up possibilities for treating patients not responding to conventional therapies. New discoveries are also being made at the DNA and RNA level, with mipomersen being the first approved therapy based on RNA intervention in the United States for homozygous familial hypercholesterolemia. Recent years have witnessed a new beginning for cholesterol-lowering compounds. With increased knowledge of lipid metabolism a score of new therapeutic targets has been identified. Mechanisms for modulation of those targets are also becoming more diverse while statins remain the backbone of CVD prevention, the new alternatives, such as PCSK9 monoclonals will probably play an important additional role in treatment of patients at risk for CVD.

P2Y(2)R activation by nucleotides released from oxLDL-treated endothelial cells (ECs) mediates the interaction between ECs and immune cells through RAGE expression and reactive oxygen species production.

PubMed

Eun, So Young; Park, Sang Won; Lee, Jae Heun; Chang, Ki Churl; Kim, Hye Jung

2014-04-01

Lipoprotein oxidation, inflammation, and immune responses involving the vascular endothelium and immune cells contribute to the pathogenesis of atherosclerosis. In an atherosclerotic animal model, P2Y2 receptor (P2Y2R) upregulation and stimulation were previously shown to induce intimal hyperplasia and increased intimal monocyte infiltration. Thus, we investigated the role of P2Y2R in oxidized low-density lipoprotein (oxLDL)-mediated oxidative stress and the subsequent interaction between endothelial cells (ECs) and immune cells. The treatment of human ECs with oxLDL caused the rapid release of ATP (maximum after 5 min). ECs treated with oxLDL or the P2Y2R agonists ATP/UTP for 1h exhibited significant reactive oxygen species (ROS) production, but this effect was not observed in P2Y2R siRNA-transfected ECs. In addition, oxLDL and ATP/UTP both induced RAGE expression, which was P2Y2R dependent. Oxidized LDL- and ATP/UTP-mediated ROS production was diminished in RAGE siRNA-transfected ECs, suggesting that RAGE is an important mediator in P2Y2R-mediated ROS production. Treatment with oxLDL for 24h induced P2Y2R expression in the human monocyte cell line THP-1 and increased THP-1 cell migration toward ECs. The addition of apyrase, an enzyme that hydrolyzes nucleotides, or diphenyleneiodonium (DPI), a well-known inhibitor of NADPH oxidase, significantly inhibited the increase in cell migration caused by oxLDL. P2Y2R siRNA-transfected THP-1 cells did not migrate in response to oxLDL or ATP/UTP treatment, indicating a critical role for P2Y2R and nucleotide release in oxLDL-induced monocyte migration. Last, oxLDL and ATP/UTP effectively increased ICAM-1 and VCAM-1 expression and the subsequent binding of THP-1 cells to ECs, which was inhibited by pretreatment with DPI or by siRNA against P2Y2R or RAGE, suggesting that P2Y2R is an important mediator in oxLDL-mediated monocyte adhesion to ECs through the regulation of ROS-dependent adhesion molecule expression in ECs. Taken together, our findings suggest that P2Y2R could be a therapeutic target for the prevention of vascular disorders, including atherosclerosis. Copyright © 2014 Elsevier Inc. All rights reserved.

Vinpocetine attenuates lipid accumulation and atherosclerosis formation.

PubMed

Cai, Yujun; Li, Jian-Dong; Yan, Chen

2013-05-10

Atherosclerosis, the major cause of myocardial infarction and stroke, is a chronic arterial disease characterized by lipid deposition and inflammation in the vessel wall. Cholesterol, in low-density lipoprotein (LDL), plays a critical role in the pathogenesis of atherosclerosis. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. Recent study indicated that vinpocetine is a potent anti-inflammatory agent. However, its role in the pathogenesis of atherosclerosis remains unexplored. In the present study, we show that vinpocetine significantly reduced atherosclerotic lesion formation in ApoE knockout mice fed with a high-fat diet. In cultured murine macrophage RAW264.7 cells, vinpocetine markedly attenuated oxidized LDL (ox-LDL) uptake and foam cell formation. Moreover, vinpocetine greatly blocked the induction of ox-LDL receptor 1 (LOX-1) in cultured macrophages as well as in the LOX-1 level in atherosclerotic lesions. Taken together, our data reveal a novel role of vinpocetine in reduction of pathogenesis of atherosclerosis, at least partially through suppressing LOX-1 signaling pathway. Given the excellent safety profile of vinpocetine, this study suggests vinpocetine may be a therapeutic candidate for treating atherosclerosis. Copyright © 2013 Elsevier Inc. All rights reserved.

Vinpocetine Attenuates Lipid Accumulation and Atherosclerosis Formation

PubMed Central

Cai, Yujun; Li, Jian-Dong; Yan, Chen

2013-01-01

Atherosclerosis, the major cause of myocardial infarction and stroke, is a chronic arterial disease characterized by lipid deposition and inflammation in the vessel wall. Cholesterol, in low-density lipoprotein (LDL), plays a critical role in the pathogenesis of atherosclerosis. Vinpocetine, a derivative of the alkaloid vincamine, has long been used as a cerebral blood flow enhancer for treating cognitive impairment. Recent study indicated that vinpocetine is a potent inflammatory agent. However, its role in the pathogenesis of atherosclerosis remains unexplored. In the present study, we show that vinpocetine significantly reduced atherosclerotic lesion formation in ApoE knockout mice fed with a high-fat diet. In cultured murine macrophage RAW264.7 cells, vinpocetine markedly attenuated oxidized LDL (ox-LDL) uptake and foam cell formation. Moreover, vinpocetine greatly blocked the induction of ox-LDL receptor 1 (LOX-1) in cultured macrophages as well as in the LOX-1 level in atherosclerotic lesions. Taken together, our data reveal a novel role of vinpocetine in reduction of pathogenesis of atherosclerosis, at least partially through suppressing LOX-1 signaling pathway. Given the excellent safety profile of vinpocetine, this study suggests vinpocetine may be a therapeutic candidate for treating atherosclerosis PMID:23583194

Proprotein convertase subtilisin/kexin 9 inhibitors: an emerging lipid-lowering therapy?

PubMed

Dragan, Simona; Serban, Maria-Corina; Banach, Maciej

2015-03-01

Proprotein convertase subtilisin/kexin 9 (PCSK9) is part of the proteinase K subfamily of subtilases and plays a key role in lipid metabolism. It increases degradation of the low-density lipoprotein receptor (LDL-R), modulates cholesterol metabolism and transport, and contributes to the production of apolipoprotein B (apoB) in intestinal cells. Exogenous PCSK9 modifies the activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase and acyl coenzyme A:cholesterol acyltransferase and enhances secretion of chylomicrons by modulating production of lipids and apoB-48. Statins increase PCSK9 messenger RNA expression and attenuate the capacity to increase LDL-R levels. Therefore, the inhibition of PCSK9 in combination with statins provides a promising approach for lowering low-density lipoprotein cholesterol (LDL-C) concentrations. This review will address new therapeutic strategies targeting PCSK9, including monoclonal antibodies, antisense oligonucleotides, small interfering RNAs, and other small molecule inhibitors. Further studies are still needed to determine the efficacy and safety of the PCSK9 inhibitors not only to decrease LDL-C but also to investigate the potential underlying mechanisms involved and to test whether these compounds actually reduce cardiovascular end points and mortality. © The Author(s) 2014.

PCSK9: an emerging target for treatment of hypercholesterolemia.

PubMed

Duff, Christopher J; Hooper, Nigel M

2011-02-01

Increased plasma low-density lipoprotein (LDL) cholesterol is a significant risk factor for cardiovascular disease. Plasma LDL-cholesterol is controlled through its uptake into cells upon binding the LDL receptor (LDLR). Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the LDLR and promotes its degradation, resulting in increased plasma LDL-cholesterol. Inhibiting the action of PCSK9 on the LDLR has emerged as a novel therapeutic target for hypercholesterolemia. We briefly describe the identification and initial characterisation of PCSK9, before detailing the molecular mechanisms involved in its interaction with the LDLR. We highlight the potential sites for therapeutic intervention in this pathway and describe the current status of therapeutic approaches, including blocking antibodies, siRNA, antisense oligonucleotides and small-molecule inhibitors. The potential limitations of such approaches are also discussed. There is a wealth of evidence indicating that inhibition of PCSK9 is a highly desirable approach to combat hypercholesterolemia, with several agents in preclinical and clinical development. However, further research is required to fully understand the biological role of PCSK9 and whether its inhibition may have adverse effects in certain groups of patients, for example, those with liver disease.

Exome sequencing identifies rare LDLR and APOA5 alleles conferring risk for myocardial infarction.

PubMed

Do, Ron; Stitziel, Nathan O; Won, Hong-Hee; Jørgensen, Anders Berg; Duga, Stefano; Angelica Merlini, Pier; Kiezun, Adam; Farrall, Martin; Goel, Anuj; Zuk, Or; Guella, Illaria; Asselta, Rosanna; Lange, Leslie A; Peloso, Gina M; Auer, Paul L; Girelli, Domenico; Martinelli, Nicola; Farlow, Deborah N; DePristo, Mark A; Roberts, Robert; Stewart, Alexander F R; Saleheen, Danish; Danesh, John; Epstein, Stephen E; Sivapalaratnam, Suthesh; Hovingh, G Kees; Kastelein, John J; Samani, Nilesh J; Schunkert, Heribert; Erdmann, Jeanette; Shah, Svati H; Kraus, William E; Davies, Robert; Nikpay, Majid; Johansen, Christopher T; Wang, Jian; Hegele, Robert A; Hechter, Eliana; Marz, Winfried; Kleber, Marcus E; Huang, Jie; Johnson, Andrew D; Li, Mingyao; Burke, Greg L; Gross, Myron; Liu, Yongmei; Assimes, Themistocles L; Heiss, Gerardo; Lange, Ethan M; Folsom, Aaron R; Taylor, Herman A; Olivieri, Oliviero; Hamsten, Anders; Clarke, Robert; Reilly, Dermot F; Yin, Wu; Rivas, Manuel A; Donnelly, Peter; Rossouw, Jacques E; Psaty, Bruce M; Herrington, David M; Wilson, James G; Rich, Stephen S; Bamshad, Michael J; Tracy, Russell P; Cupples, L Adrienne; Rader, Daniel J; Reilly, Muredach P; Spertus, John A; Cresci, Sharon; Hartiala, Jaana; Tang, W H Wilson; Hazen, Stanley L; Allayee, Hooman; Reiner, Alex P; Carlson, Christopher S; Kooperberg, Charles; Jackson, Rebecca D; Boerwinkle, Eric; Lander, Eric S; Schwartz, Stephen M; Siscovick, David S; McPherson, Ruth; Tybjaerg-Hansen, Anne; Abecasis, Goncalo R; Watkins, Hugh; Nickerson, Deborah A; Ardissino, Diego; Sunyaev, Shamil R; O'Donnell, Christopher J; Altshuler, David; Gabriel, Stacey; Kathiresan, Sekar

2015-02-05

Myocardial infarction (MI), a leading cause of death around the world, displays a complex pattern of inheritance. When MI occurs early in life, genetic inheritance is a major component to risk. Previously, rare mutations in low-density lipoprotein (LDL) genes have been shown to contribute to MI risk in individual families, whereas common variants at more than 45 loci have been associated with MI risk in the population. Here we evaluate how rare mutations contribute to early-onset MI risk in the population. We sequenced the protein-coding regions of 9,793 genomes from patients with MI at an early age (≤50 years in males and ≤60 years in females) along with MI-free controls. We identified two genes in which rare coding-sequence mutations were more frequent in MI cases versus controls at exome-wide significance. At low-density lipoprotein receptor (LDLR), carriers of rare non-synonymous mutations were at 4.2-fold increased risk for MI; carriers of null alleles at LDLR were at even higher risk (13-fold difference). Approximately 2% of early MI cases harbour a rare, damaging mutation in LDLR; this estimate is similar to one made more than 40 years ago using an analysis of total cholesterol. Among controls, about 1 in 217 carried an LDLR coding-sequence mutation and had plasma LDL cholesterol > 190 mg dl(-1). At apolipoprotein A-V (APOA5), carriers of rare non-synonymous mutations were at 2.2-fold increased risk for MI. When compared with non-carriers, LDLR mutation carriers had higher plasma LDL cholesterol, whereas APOA5 mutation carriers had higher plasma triglycerides. Recent evidence has connected MI risk with coding-sequence mutations at two genes functionally related to APOA5, namely lipoprotein lipase and apolipoprotein C-III (refs 18, 19). Combined, these observations suggest that, as well as LDL cholesterol, disordered metabolism of triglyceride-rich lipoproteins contributes to MI risk.

Accumulation of oxidized LDL in the tendon tissues of C57BL/6 or apolipoprotein E knock-out mice that consume a high fat diet: potential impact on tendon health.

PubMed

Grewal, Navdeep; Thornton, Gail M; Behzad, Hayedeh; Sharma, Aishwariya; Lu, Alex; Zhang, Peng; Reid, W Darlene; Granville Alex Scott, David J

2014-01-01

Clinical studies have suggested an association between dyslipidemia and tendon injuries or chronic tendon pain; the mechanisms underlying this association are not yet known. The objectives of this study were (1) to evaluate the impact of a high fat diet on the function of load-bearing tendons and on the distribution in tendons of oxidized low density lipoprotein (oxLDL), and (2) to examine the effect of oxLDL on tendon fibroblast proliferation and gene expression. Gene expression (Mmp2, Tgfb1, Col1a1, Col3a1), fat content (Oil Red O staining), oxLDL levels (immunohistochemistry) and tendon biomechanical properties were examined in mice (C57Bl/6 or ApoE -/-) receiving a standard or a high fat diet. Human tendon fibroblast proliferation and gene expression (COL1A1, COL3A1, MMP2) were examined following oxLDL exposure. In both types of mice (C57Bl/6 or ApoE -/-), consumption of a high fat diet led to a marked increase in oxLDL deposition in the load-bearing extracellular matrix of the tendon. The consumption of a high fat diet also reduced the failure stress and load of the patellar tendon in both mouse types, and increased Mmp2 expression. ApoE -/- mice exhibited more pronounced reductions in tendon function than wild-type mice, and decreased expression of Col1a1 compared to wild type mice. Human tendon fibroblasts responded to oxLDL by increasing their proliferation and their mRNA levels of MMP2, while decreasing their mRNA levels for COL1A1 and COL3A1. The consumption of a high fat diet resulted in deleterious changes in tendon function, and these changes may be explained in part by the effects of oxLDL, which induced a proliferative, matrix-degrading phenotype in human tenocytes.

Oxidized-LDL induce morphological changes and increase stiffness of endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chouinard, Julie A.; Research Centre on Aging, Sherbrooke Geriatric University Institute, Sherbrooke, Quebec; Grenier, Guillaume

There is increasing evidence suggesting that oxidized low-density lipoproteins (ox-LDL) play a critical role in endothelial injury contributing to the age-related physio-pathological process of atherosclerosis. In this study, the effects of native LDL and ox-LDL on the mechanical properties of living human umbilical vein endothelial cells (HUVEC) were investigated by atomic force microscopy (AFM) force measurements. The contribution of filamentous actin (F-actin) and vimentin on cytoskeletal network organization were also examined by fluorescence microscopy. Our results revealed that ox-LDL had an impact on the HUVEC shape by interfering with F-actin and vimentin while native LDL showed no effect. AFM colloidalmore » force measurements on living individual HUVEC were successfully used to measure stiffness of cells exposed to native and ox-LDL. AFM results demonstrated that the cell body became significantly stiffer when cells were exposed for 24 h to ox-LDL while cells exposed for 24 h to native LDL displayed similar rigidity to that of the control cells. Young's moduli of LDL-exposed HUVEC were calculated using two models. This study thus provides quantitative evidence on biomechanical mechanisms related to endothelial cell dysfunction and may give new insight on strategies aiming to protect endothelial function in atherosclerosis.« less

Low density lipoprotein for oxidation and metabolic studies. Isolation from small volumes of plasma using a tabletop ultracentrifuge.

PubMed

Himber, J; Bühler, E; Moll, D; Moser, U K

1995-01-01

A rapid method is described for the isolation of small volumes of plasma low density lipoprotein (LDL) free of plasma protein contaminants using the TL-100 Tabletop Ultracentrifuge (Beckman). The isolation of LDL was achieved by a 25 min discontinuous gradient density centrifugation between the density range of 1.006 and 1.21 g/ml, recovery of LDL by tube slicing followed by a 90 min flotation step (d = 1.12 g/ml). The purity of LDL and apolipoprotein B100 (apo B100) were monitored by agarose electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), radial immunodiffusion and micropreparative fast protein liquid chromatography (FPLC). The ability of LDL oxidation was assessed by following absorbance at 234 nm after addition of copper ions. The functional integrity of the isolated LDL was checked by clearance kinetics after injection of [125I]-labelled LDL in estrogen-treated rats. The additional purification step led to LDL fractions free of protein contamination and left apo B100, alpha-tocopherol and beta-carotene intact. The LDL prepared in this way was free of albumin, as evident from analytic tests and from its enhanced oxidative modification by copper ions. Used for analytical purposes, this method allows LDL preparations from plasma volumes up to 570 microliters. This method is also convenient for metabolic studies in small animals, especially those relating to the determination of kinetic parameters of LDL in which LDL-apo B100 has to be specifically radiolabelled.

Advances in the management of dyslipidemia.

PubMed

Kampangkaew, June; Pickett, Stephen; Nambi, Vijay

2017-07-01

Cardiovascular disease is the leading cause of morbidity and mortality in the United States and therapies aimed at lipid modification are important for the reduction of cardiovascular risk. There have been many exciting advances in lipid management over the recent years. This review discusses these recent advances as well as the direction of future studies. Several recent clinical trials support low-density lipoprotein cholesterol (LDL-c) reduction beyond maximal statin therapy for improved cardiovascular outcomes. Ezetimibe reduced LDL-c beyond maximal statin therapy and was associated with improved cardiovascular outcomes for high-risk populations. Further LDL-c reduction may also be achieved with proprotein convertase subtilisin/kexin type-9 (PCSK9) inhibition and a recent trial, Further Cardiovascular Outcomes Research with PCSK9 Inhibition in Subjects with Elevated Risk (FOURIER), was the first to show reduction in cardiovascular events for evolocumab. Additional outcome studies of monoclonal antibody and RNA-targeted PCSK9 inhibitors are underway. Quantitative high-density lipoprotein cholesterol (HDL-c) improvements have failed to have clinical impact to date; most recently, cholesteryl ester transfer protein inhibitors and apolipoprotein infusions have demonstrated disappointing results. There are still ongoing trials in both of these areas, but some newer therapies are focusing on HDL functionality and not just the absolute HDL-c levels. There are several ongoing studies in triglyceride reduction including fatty acid therapy, inhibition of apolipoprotein C-3 or ANGTPL3 and peroxisome proliferator-activated receptor-α agonists. Lipid management continues to evolve and these advances have the potential to change clinical practice in the coming years.

Homocysteine up-regulates vascular transmembrane chemokine CXCL16 and induces CXCR6+ lymphocyte recruitment in vitro and in vivo.

PubMed

Postea, O; Koenen, R R; Hristov, M; Weber, C; Ludwig, A

2008-01-01

Hyperhomocysteinemia induces endothelial dysfunction and promotes atherosclerotic vascular disease. Infiltrates of activated macrophages and lymphocytes are observed in human and experimental atherosclerotic lesions, their emigration being guided by endothelial-leukocyte adhesion molecules and chemoattractants. The CXC-chemokine CXCL16 functions as an adhesion molecule by interacting with its receptor (CXCR6) and also as a scavenger for oxidized low density lipoprotein (oxLDL). We investigated the modulation of CXCL16 on cultured endothelial cells (EC) and the recruitment of CXCR6(+) lymphocytes in response to homocysteine (Hcy), in vitro and in vivo. Hcy-stimulated EC show a significant increase in CXCL16 mRNA and protein expression. Incubation of EC with d,l-Hcy and l-Hcy significantly increased CXCR6(+) lymphocyte adhesion to EC while l-Cysteine (l-Cys) had no effect. Furthermore, EC stimulation with Hcy increased uptake of DiI-oxLDL. An anti-CXCL16 monoclonal antibody, antioxidants (Tiron) and PPAR-gamma agonists (Pioglitazone) considerably reduced CXCR6(+) lymphocyte adhesion and uptake of DiI-oxLDL. Upon injection in the peritoneal cavities of mice, l-Hcy and not l-Cys, increased the number of CXCR6(+) lymphocytes, which was reduced by coinjection with Pioglitazone or anti-human CXCL16 antibody. Hyperhomocysteinemia up-regulates CXCL16 leading to increased recruitment of CXCR6(+) lymphocytes and scavenging of modified lipids via a potential involvement of a PPAR-gamma-dependent mechanism. CXCL16 may therefore contribute to the formation and progression of atherosclerotic lesions under conditions of hyperhomocysteinemia.

Homocysteine up-regulates vascular transmembrane chemokine CXCL16 and induces CXCR6+ lymphocyte recruitment in vitro and in vivo

PubMed Central

Postea, O; Koenen, R R; Hristov, M; Weber, C; Ludwig, A

2008-01-01

Abstract Objective: Hyperhomocysteinemia induces endothelial dysfunction and promotes atherosclerotic vascular disease. Infiltrates of activated macrophages and lymphocytes are observed in human and experimental atherosclerotic lesions, their emigration being guided by endothelial-leukocyte adhesion molecules and chemoattractants. The CXC-chemokine CXCL16 functions as an adhesion molecule by interacting with its receptor (CXCR6) and also as a scavenger for oxidized low density lipoprotein (oxLDL). We investigated the modulation of CXCL16 on cultured endothelial cells (EC) and the recruitment of CXCR6+ lymphocytes in response to homocysteine (Hcy), in vitro and in vivo. Methods and Results: Hcy-stimulated EC show a significant increase in CXCL16 mRNA and protein expression. Incubation of EC with d,l-Hcy and l-Hcy significantly increased CXCR6+ lymphocyte adhesion to EC while l-Cysteine (l-Cys) had no effect. Furthermore, EC stimulation with Hcy increased uptake of DiI-oxLDL. An anti-CXCL16 monoclonal antibody, antioxidants (Tiron) and PPAR-γ agonists (Pioglitazone) considerably reduced CXCR6+ lymphocyte adhesion and uptake of DiI-oxLDL. Upon injection in the peritoneal cavities of mice, l-Hcy and not l-Cys, increased the number of CXCR6+ lymphocytes, which was reduced by coinjection with Pioglitazone or anti-human CXCL16 antibody. Conclusions: Hyperhomocysteinemia up-regulates CXCL16 leading to increased recruitment of CXCR6+ lymphocytes and scavenging of modified lipids via a potential involvement of a PPAR-γ-dependent mechanism. CXCL16 may therefore contribute to the formation and progression of atherosclerotic lesions under conditions of hyperhomocysteinemia. PMID:18194461

Effect of an RNA interference drug on the synthesis of proprotein convertase subtilisin/kexin type 9 (PCSK9) and the concentration of serum LDL cholesterol in healthy volunteers: a randomised, single-blind, placebo-controlled, phase 1 trial.

PubMed

Fitzgerald, Kevin; Frank-Kamenetsky, Maria; Shulga-Morskaya, Svetlana; Liebow, Abigail; Bettencourt, Brian R; Sutherland, Jessica E; Hutabarat, Renta M; Clausen, Valerie A; Karsten, Verena; Cehelsky, Jeffrey; Nochur, Saraswathy V; Kotelianski, Victor; Horton, Jay; Mant, Timothy; Chiesa, Joseph; Ritter, James; Munisamy, Malathy; Vaishnaw, Akshay K; Gollob, Jared A; Simon, Amy

2014-01-04

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to LDL receptors, leading to their degradation. Genetics studies have shown that loss-of-function mutations in PCSK9 result in reduced plasma LDL cholesterol and decreased risk of coronary heart disease. We aimed to investigate the safety and efficacy of ALN-PCS, a small interfering RNA that inhibits PCSK9 synthesis, in healthy volunteers with raised cholesterol who were not on lipid-lowering treatment. We did a randomised, single-blind, placebo-controlled, phase 1 dose-escalation study in healthy adult volunteers with serum LDL cholesterol of 3·00 mmol/L or higher. Participants were randomly assigned in a 3:1 ratio by computer algorithm to receive one dose of intravenous ALN-PCS (with doses ranging from 0·015 to 0·400 mg/kg) or placebo. The primary endpoint was safety and tolerability of ALN-PCS. Secondary endpoints were the pharmacokinetic characteristics of ALN-PCS and its pharmacodynamic effects on PCSK9 and LDL cholesterol. Study participants were masked to treatment assignment. Analysis was per protocol and we used ANCOVA to analyse pharmacodynamic endpoint data. This trial is registered with ClinicalTrials.gov, number NCT01437059. Of 32 participants, 24 were randomly allocated to receive a single dose of ALN-PCS (0·015 mg/kg [n=3], 0·045 mg/kg [n=3], 0·090 mg/kg [n=3], 0·150 mg/kg [n=3], 0·250 mg/kg [n=6], or 0·400 mg/kg [n=6]) and eight to placebo. The proportions of patients affected by treatment-emergent adverse events were similar in the ALN-PCS and placebo groups (19 [79%] vs seven [88%]). ALN-PCS was rapidly distributed, with peak concentration and area under the curve (0 to last measurement) increasing in a roughly dose-proportional way across the dose range tested. In the group given 0·400 mg/kg of ALN-PCS, treatment resulted in a mean 70% reduction in circulating PCSK9 plasma protein (p<0·0001) and a mean 40% reduction in LDL cholesterol from baseline relative to placebo (p<0·0001). Our results suggest that inhibition of PCSK9 synthesis by RNA interference (RNAi) provides a potentially safe mechanism to reduce LDL cholesterol concentration in healthy individuals with raised cholesterol. These results support the further assessment of ALN-PCS in patients with hypercholesterolaemia, including those being treated with statins. This study is the first to show an RNAi drug being used to affect a clinically validated endpoint (ie, LDL cholesterol) in human beings. Alnylam Pharmaceuticals. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nur77 inhibits oxLDL induced apoptosis of macrophages via the p38 MAPK signaling pathway

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shao, Qin; Han, Fei; Peng, Shi

2016-03-18

The interaction between macrophages and oxLDL plays a crucial role in the initiation and progression of atherosclerosis. As a key initiator in a number of plaque promoting processes, oxLDL induces variable effects such as cell apoptosis or proliferation. Orphan nuclear receptor Nur77 is potently induced in macrophages by diverse stimuli, suggesting that it is of importance in vascular inflammation resulting in atherosclerosis, but whether Nur77 induction is detrimental or protective is unclear. In our study, we explore the role of Nur77 in the regulation of oxLDL-induced macrophage apoptosis and the signaling pathways that are involved. We found that oxLDL inducedmore » Nur77 expression in a dose and time dependent fashion, and cell viability was decreased in parallel. To determine whether Nur77 induction contributes to the loss of cell viability or is a protective mechanism, the effect of Nur77 overexpression was examined. Importantly, Nur77 overexpression inhibited the oxLDL-induced decrease of cell viability, inhibited the production of apoptotic bodies and restored DNA synthesis following oxLDL exposure. Furthermore, we found that Nur77 induction is mediated through the p38 MAPK signaling pathway. After pretreatment with SB203580, cell viability was decreased, the expression of CyclinA2 and PCNA was attenuated and the percentage of cell apoptosis was enhanced. Likewise, Nur77 overexpression increased the expression of the cell cycle genes PCNA and p21, and attenuated the increase in caspase-3. On the other hand, knockdown of Nur77 expression by specific siRNA resulted in the increased expression of caspase 3. The results demonstrate that Nur77 is induced by oxLDL via the p38 MAPK signaling pathway, which is involved in the regulation of cell survival. Nur77 enhanced cell survival via suppressing apoptosis, without affecting cell proliferation of activated macrophages, which may be beneficial in patients with atherosclerosis. - Highlights: • oxLDL could induce Nur77 expression. • Nur77 overexpression inhibited oxLDL-induced cell viability, production of apoptotic bodies and restored DNA synthesis. • Cell viability, CyclinA2 and PCNA expression and cell apoptosis were mediated through the p38 MAPK signaling pathway. • Nur77 overexpression mediated the expression of genes PCNA, p21, and caspase-3.« less

Laminar shear stress regulates endothelial kinin B1 receptor expression and function: potential implication in atherogenesis

PubMed Central

Duchene, Johan; Cayla, Cécile; Vessillier, Sandrine; Scotland, Ramona; Yamashiro, Kazuo; Lecomte, Florence; Syed, Irfan; Vo, Phuong; Marrelli, Alessandra; Pitzalis, Costantino; Cipollone, Francesco; Schanstra, Joost; Bascands, Jean-Loup; Hobbs, Adrian J; Perretti, Mauro; Ahluwalia, Amrita

2009-01-01

OBJECTIVE The pro-inflammatory phenotype induced by low laminar shear stress (LSS) is implicated in atherogenesis. The kinin B1 receptor (B1R), known to be induced by inflammatory stimuli, exerts many pro-inflammatory effects including vasodilatation and leukocyte recruitment. We investigated whether low LSS is a stimulus for endothelial B1R expression and function. METHODS AND RESULTS Human and mouse atherosclerotic plaques expressed high level of B1R mRNA and protein. In addition, B1R expression was upregulated in the aortic arch (low LSS region) of ApoE-/- mice fed a high fat diet compared to vascular regions of high LSS and animals fed normal chow. Of interest, a greater expression of B1R was noticed in endothelial cells from regions of low LSS in aortic arch of ApoE-/- mice. B1R was also upregulated in human umbilical vein endothelial cells (HUVEC) exposed to low LSS (0-2dyn/cm2) compared to physiological LSS (6-10dyn/cm2): an effect similarly evident in murine vascular tissue perfused ex vivo. Functionally, B1R activation increased prostaglandin and CXCL5 expression in cells exposed to low, but not physiological, LSS. IL-1β and ox-LDL induced B1R expression and function in HUVECs, a response substantially enhanced under low LSS conditions and inhibited by blockade of NFκB activation. CONCLUSION Herein, we show that LSS is a major determinant of functional B1R expression in endothelium. Furthermore, whilst physiological high LSS is a powerful repressor of this inflammatory receptor, low LSS at sites of atheroma are associated with substantial upregulation, identifying this receptor as a potential therapeutic target. CONDENSED ABSTRACT Low laminar shear stress (LSS) underlies the pro-inflammatory processes in atherogenesis. Herein, we demonstrate that whilst physiological LSS represses inflammatory kinin B1 receptor (B1R) expression/function, low atherogenic LSS is associated with profound upregulation of both in atherosclerosis in both humans and animal models, highlighting B1R as an exciting potential therapeutic target. PMID:19661485

First-Generation Antipsychotic Haloperidol Alters the Functionality of the Late Endosomal/Lysosomal Compartment in Vitro.

PubMed

Canfrán-Duque, Alberto; Barrio, Luis C; Lerma, Milagros; de la Peña, Gema; Serna, Jorge; Pastor, Oscar; Lasunción, Miguel A; Busto, Rebeca

2016-03-18

First- and second-generation antipsychotics (FGAs and SGAs, respectively), have the ability to inhibit cholesterol biosynthesis and also to interrupt the intracellular cholesterol trafficking, interfering with low-density lipoprotein (LDL)-derived cholesterol egress from late endosomes/lysosomes. In the present work, we examined the effects of FGA haloperidol on the functionality of late endosomes/lysosomes in vitro. In HepG2 hepatocarcinoma cells incubated in the presence of 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocarbocyanineperchlorate (DiI)-LDL, treatment with haloperidol caused the enlargement of organelles positive for late endosome markers lysosome-associated membrane protein 2 (LAMP-2) and LBPA (lysobisphosphatidic acid), which also showed increased content of both free-cholesterol and DiI derived from LDL. This indicates the accumulation of LDL-lipids in the late endosomal/lysosomal compartment caused by haloperidol. In contrast, LDL traffic through early endosomes and the Golgi apparatus appeared to be unaffected by the antipsychotic as the distribution of both early endosome antigen 1 (EEA1) and coatomer subunit β (β-COP) were not perturbed. Notably, treatment with haloperidol significantly increased the lysosomal pH and decreased the activities of lysosomal protease and β-d-galactosidase in a dose-dependent manner. We conclude that the alkalinization of the lysosomes' internal milieu induced by haloperidol affects lysosomal functionality.

G Protein-coupled Estrogen Receptor Protects from Atherosclerosis

PubMed Central

Meyer, Matthias R.; Fredette, Natalie C.; Howard, Tamara A.; Hu, Chelin; Ramesh, Chinnasamy; Daniel, Christoph; Amann, Kerstin; Arterburn, Jeffrey B.; Barton, Matthias; Prossnitz, Eric R.

2014-01-01

Coronary atherosclerosis and myocardial infarction in postmenopausal women have been linked to inflammation and reduced nitric oxide (NO) formation. Natural estrogen exerts protective effects on both processes, yet also displays uterotrophic activity. Here, we used genetic and pharmacologic approaches to investigate the role of the G protein-coupled estrogen receptor (GPER) in atherosclerosis. In ovary-intact mice, deletion of gper increased atherosclerosis progression, total and LDL cholesterol levels and inflammation while reducing vascular NO bioactivity, effects that were in some cases aggravated by surgical menopause. In human endothelial cells, GPER was expressed on intracellular membranes and mediated eNOS activation and NO formation, partially accounting for estrogen-mediated effects. Chronic treatment with G-1, a synthetic, highly selective small molecule agonist of GPER, reduced postmenopausal atherosclerosis and inflammation without uterotrophic effects. In summary, this study reveals an atheroprotective function of GPER and introduces selective GPER activation as a novel therapeutic approach to inhibit postmenopausal atherosclerosis and inflammation in the absence of uterotrophic activity. PMID:25532911

MicroRNAs expression in ox-LDL treated HUVECs: MiR-365 modulates apoptosis and Bcl-2 expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qin, Bing; Xiao, Bo; Liang, Desheng

Highlights: {yields} We evaluated the role of miRNAs in ox-LDL induced apoptosis in ECs. {yields} We found 4 up-regulated and 11 down-regulated miRNAs in apoptotic ECs. {yields} Target genes of the dysregulated miRNAs regulate ECs apoptosis and atherosclerosis. {yields} MiR-365 promotes ECs apoptosis via suppressing Bcl-2 expression. {yields} MiR-365 inhibitor alleviates ECs apoptosis induced by ox-LDL. -- Abstract: Endothelial cells (ECs) apoptosis induced by oxidized low-density lipoprotein (ox-LDL) is thought to play a critical role in atherosclerosis. MicroRNAs (miRNAs) are a class of noncoding RNAs that posttranscriptionally regulate the expression of genes involved in diverse cell functions, including differentiation, growth,more » proliferation, and apoptosis. However, whether miRNAs are associated with ox-LDL induced apoptosis and their effect on ECs is still unknown. Therefore, this study evaluated potential miRNAs and their involvement in ECs apoptosis in response to ox-LDL stimulation. Microarray and qRT-PCR analysis performed on human umbilical vein endothelial cells (HUVECs) exposed to ox-LDL identified 15 differentially expressed (4 up- and 11 down-regulated) miRNAs. Web-based query tools were utilized to predict the target genes of the differentially expressed miRNAs, and the potential target genes were classified into different function categories with the gene ontology (GO) term and KEGG pathway annotation. In particular, bioinformatics analysis suggested that anti-apoptotic protein B-cell CLL/lymphoma 2 (Bcl-2) is a target gene of miR-365, an apoptomir up-regulated by ox-LDL stimulation in HUVECs. We further showed that transfection of miR-365 inhibitor partly restored Bcl-2 expression at both mRNA and protein levels, leading to a reduction of ox-LDL-mediated apoptosis in HUVECs. Taken together, our findings indicate that miRNAs participate in ox-LDL-mediated apoptosis in HUVECs. MiR-365 potentiates ox-LDL-induced ECs apoptosis by regulating the expression of Bcl-2, suggesting potential novel therapeutic targets for atherosclerosis.« less

Different responses to oxidized low-density lipoproteins in human polarized macrophages

PubMed Central

2011-01-01

Background Oxidized low-density lipoprotein (oxLDL) uptake by macrophages plays an important role in foam cell formation. It has been suggested the presence of heterogeneous subsets of macrophage, such as M1 and M2, in human atherosclerotic lesions. To evaluate which types of macrophages contribute to atherogenesis, we performed cDNA microarray analysis to determine oxLDL-induced transcriptional alterations of each subset of macrophages. Results Human monocyte-derived macrophages were polarized toward the M1 or M2 subset, followed by treatment with oxLDL. Then gene expression levels during oxLDL treatment in each subset of macrophages were evaluated by cDNA microarray analysis and quantitative real-time RT-PCR. In terms of high-ranking upregulated genes and functional ontologies, the alterations during oxLDL treatment in M2 macrophages were similar to those in nonpolarized macrophages (M0). Molecular network analysis showed that most of the molecules in the oxLDL-induced highest scoring molecular network of M1 macrophages were directly or indirectly related to transforming growth factor (TGF)-β1. Hierarchical cluster analysis revealed commonly upregulated genes in all subset of macrophages, some of which contained antioxidant response elements (ARE) in their promoter regions. A cluster of genes that were specifically upregulated in M1 macrophages included those encoding molecules related to nuclear factor of kappa light polypeptide gene enhancer in B-cells (NF-κB) signaling pathway. Quantitative real-time RT-PCR showed that the gene expression of interleukin (IL)-8 after oxLDL treatment in M2 macrophages was markedly lower than those in M0 and M1 cells. HMOX1 gene expression levels were almost the same in all 3 subsets of macrophages even after oxLDL treatment. Conclusions The present study demonstrated transcriptional alterations in polarized macrophages during oxLDL treatment. The data suggested that oxLDL uptake may affect TGF-β1- and NF-κB-mediated functions of M1 macrophages, but not those of M0 or M2 macrophages. It is likely that M1 macrophages characteristically respond to oxLDL. PMID:21199582

Serum lipoproteins are not associated with the severity of asthma.

PubMed

Scaduto, Federica; Giglio, Rosaria Vincenza; Benfante, Alida; Nikolic, Dragana; Montalto, Giuseppe; Rizzo, Manfredi; Scichilone, Nicola

2018-06-01

Asthma is a chronic inflammatory disorder of the bronchi with a complicated and largely unknown pathogenesis. In this context, an emerging role is attributed to the apolipoproteins which serve as structural components of plasma lipoproteins. Low density lipoproteins (LDL) may be involved in the inflammatory pathways of the asthmatic airways; in particular, small dense LDL (sdLDL) particles were associated with increased oxidative susceptibility compared to medium and large sized LDL. In our previous study, we found a positive correlation between forced expiratory volume 1 s (FEV 1 ) % predicted and larger LDL particles (LDL-1), and an inverse correlation between FEV 1 % predicted and sdLDL (LDL-3) in mild, untreated asthmatics. Although LDL appear to be important modulators of inflammation, data on their clinical implications are still lacking. The aim of the study is to investigate whether LDL subclasses correlate with the severity of asthma, assuming that the atherogenic and most pro-inflammatory LDL contribute to ignite and perpetuate the airway inflammatory processes. The study was conducted in one visit, and included clinical and lung functional assessments, as well as measurements of serum concentrations of the LDL subclasses. Non-denaturing, linear polyacrylamide gel electrophoresis was used to separate and measure LDL subclasses, with the LipoPrint © System (Quantimetrix Corporation, Redondo Beach, CA, USA). LDL subclasses were distributed as seven bands (LDL-1 to LDL-7), LDL-1 and -2 being defined as large LDL (least pro-inflammatory), and LDL-3 to 7 defined as sdLDL (most pro-inflammatory). 70 asthmatics under inhaled treatment (M/F: 35/35) were enrolled; 10 healthy subjects (M/F: 3/7) served as controls. In the asthmatic group, FEV 1 % predicted was 81 ± 22% (mean ± SD), vital capacity (VC) % predicted was 97 ± 18%, and FEV 1 /FVC was 0.68 ± 0.1. The mean asthma control test (ACT) score was 18 ± 5. LDL-1 were significantly lower in asthmatics as compared to controls (18 ± 4% vs. 22 ± 4%, p = 0.008). On the contrary, LDL-2 (12 ± 4% vs. 12 ± 5%) and LDL-3 (3 ± 3% vs. 2 ± 2%) were not statistically different between the two groups; smaller subclasses were undetectable. To comply with the design of the study, subjects were classified according to their degree of severity into the 5 Global Initiative for Asthma (GINA) steps: Step 1 (M/F: 4/3, 44 ± 12 yrs), Step 2 (M/F: 1/2, 37 ± 11 yrs), Step 3 (M/F: 12/7, 47 ± 12 yrs), Step 4 (M/F: 8/15, 54 ± 12 yrs), and Step 5 (M/F: 7/9, 56 ± 9 yrs). None of the LDL subclasses showed significant differences between classes of severity: LDL-1 were 16.1 ± 5.6% in Step 1, 18 ± 2.8% in Step 2, 16.7 ± 3.7% in Step 3, 18 ± 3.3% in Step 4, and 19.5 ± 3.2% in Step 5 (p = NS); LDL2 were 14 ± 3.6%, 15 ± 3.4%, 12.4 ± 5.3%, 12.7 ± 4.4% and 11.3 ± 4.2%, respectively (p = NS); LDL3 were 5 ± 5.2%, 4.4 ± 2.6%, 3.3 ± 3.6%, 3.2 ± 2.6% and 2.4 ± 1.8%, p = NS. Finally, no relationship was detected between LDL subclasses and lung function parameters as well as the ACT scores. The current findings confirm a role of LDL as a potential biomarker in the diagnostic process for asthma, and suggest that LDL cannot be used as marker of severity of the disease. Copyright © 2018. Published by Elsevier Ltd.

Appropriateness of the hamster as a model to study diet-induced atherosclerosis

USDA-ARS?s Scientific Manuscript database

Golden-Syrian hamsters have been used as an animal model to assess diet-induced atherosclerosis since the early 1980s. Advantages appeared to include a low rate of endogenous cholesterol synthesis, receptor-mediated uptake of LDL cholesterol, cholesteryl ester transfer protein activity, hepatic apo...

Negatively Cooperative Binding of High Density Lipoprotein to the HDL Receptor SR-BI†

PubMed Central

Nieland, Thomas J.F.; Xu, Shangzhe; Penman, Marsha; Krieger, Monty

2011-01-01

Scavenger receptor class B, type I (SR-BI) is a high-density lipoprotein (HDL) receptor, which also binds low density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a co-receptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high affinity binding sites (one site model). We have re-investigated the ligand concentration dependence of 125I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [3H]CE from [3H]CE-HDL using an expanded range of ligand concentrations (<1 µg protein/ml, lower than previously reported). Scatchard and non-linear least squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites, or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects (‘ lattice model’). Similar results were observed for LDL. Application of the ‘infinite dilution’ dissociation rate method established that the binding of 125I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport and cell signaling. PMID:21254782

Multiple levels of regulation determine the role of the receptor for AGE (RAGE) as common soil in inflammation, immune responses and diabetes mellitus and its complications.

PubMed

Bierhaus, A; Nawroth, P P

2009-11-01

The pattern recognition receptor or receptor for AGE (RAGE) is constitutionally expressed in a few cell types only. However in almost all cells studied so far it is induced by reactions known to initiate inflammation. Its biological activity seems to be mainly dependent on the presence of its various ligands, including AGE, S100-calcium binding protein/calgranulins, high-mobility group protein 1, amyloid-beta-peptides and the family of beta-sheet fibrils, all known to be elevated in chronic metabolic, malignant and inflammatory diseases. The RAGE pathway interacts with cytokine-, lipopolysaccharide-, oxidised LDL- and glucose-triggered cellular reactions by turning a short-lasting inflammatory response into a sustained change of cellular function driven by perpetuated activation of the proinflammatory transcription factor, nuclear factor kappa-B. RAGE-mediated persistent cell activation is of pivotal importance in various experimental and clinical settings, including diabetes and its complications, neurodegeneration, ageing, tumour growth, and autoimmune and infectious inflammatory disease. Due to RAGE's central role in maintaining perpetuated cell activation, various therapeutic attempts to block RAGE or its ligands are currently under investigation. Despite broad experimental evidence for the role of RAGE in chronic disease, knowledge of its physiological function is still missing, limiting predictions about safety of long-term inhibition of RAGE x ligand interaction in chronic diseases.

Store-operated calcium entry-activated autophagy protects EPC proliferation via the CAMKK2-MTOR pathway in ox-LDL exposure.

PubMed

Yang, Jie; Yu, Jie; Li, Dongdong; Yu, Sanjiu; Ke, Jingbin; Wang, Lianyou; Wang, Yanwei; Qiu, Youzhu; Gao, Xubin; Zhang, Jihang; Huang, Lan

2017-01-02

Improving biological functions of endothelial progenitor cells (EPCs) is beneficial to maintaining endothelium homeostasis and promoting vascular re-endothelialization. Because macroautophagy/autophagy has been documented as a double-edged sword in cell functions, its effects on EPCs remain to be elucidated. This study was designed to explore the role and molecular mechanisms of store-operated calcium entry (SOCE)-activated autophagy in proliferation of EPCs under hypercholesterolemia. We employed oxidized low-density lipoprotein (ox-LDL) to mimic hypercholesterolemia in bone marrow-derived EPCs from rat. Ox-LDL dose-dependently activated autophagy flux, while inhibiting EPC proliferation. Importantly, inhibition of autophagy either by silencing Atg7 or by 3-methyladenine treatment, further aggravated proliferative inhibition by ox-LDL, suggesting the protective effects of autophagy against ox-LDL. Interestingly, ox-LDL increased STIM1 expression and intracellular Ca 2+ concentration. Either Ca 2+ chelators or deficiency in STIM1 attenuated ox-LDL-induced autophagy activation, confirming the involvement of SOCE in the process. Furthermore, CAMKK2 (calcium/calmodulin-dependent protein kinase kinase 2, β) activation and MTOR (mechanistic target of rapamycin [serine/threonine kinase]) deactivation were associated with autophagy modulation. Together, our results reveal a novel signaling pathway of SOCE-CAMKK2 in the regulation of autophagy and offer new insights into the important roles of autophagy in maintaining proliferation and promoting the survival capability of EPCs. This may be beneficial to improving EPC transplantation efficacy and enhancing vascular re-endothelialization in patients with hypercholesterolemia.

The babel of the ABCs: novel transporters involved in the regulation of sterol absorption and excretion.

PubMed

Ordovas, Jose M; Tai, E Shyong

2002-01-01

Hypercholesterolaemia is a major risk factor for coronary heart disease (CHD). Therefore, the reduction of low-density lipoprotein (LDL) cholesterol is one of the primary targets of the current recommendations to decrease CHD risk in the population. Whereas, the mechanisms involved in de novo cholesterol synthesis and its uptake by cells via the LDL receptor are well known, we still need better understanding about the mechanisms involved in intestinal cholesterol absorption and excretion. The recent discovery of ABCG5 and ABCG8 transporters will significantly improve our understanding of cholesterol trafficking and it will lead to better and new therapeutic strategies to maintain cholesterol homeostasis.

Oxidized LDL at low concentration promotes in-vitro angiogenesis and activates nitric oxide synthase through PI3K/Akt/eNOS pathway in human coronary artery endothelial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Shan; Division of Cardiology, Department of Medicine and Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong; Wong, Siu Ling

Research highlights: {yields} Low-concentration oxidized LDL enhances angiogenesis through nitric oxide (NO). {yields} Oxidized LDL increases intracellular NO levels via eNOS phosphorylation. {yields} Akt/PI3K signaling mediates oxidized LDL-induced eNOS phosphorylation. -- Abstract: It has long been considered that oxidized low-density lipoprotein (oxLDL) causes endothelial dysfunction and is remarkably related to the development of atherosclerosis. However, the effect of oxLDL at very low concentration (<10 {mu}g/ml) on the endothelial cells remains speculative. Nitric oxide (NO) has a crucial role in the endothelial cell function. In this study, we investigated the effect of oxLDL at low concentration on NO production and proliferation,more » migration, tube formation of the human coronary artery endothelial cells (HCAEC). Results showed that oxLDL at 5 {mu}g/ml enhanced HCAEC proliferation, migration and tube formation. These phenomena were accompanied by an increased intracellular NO production. L-NAME (a NOS inhibitor), LY294002 and wortmannin (PI3K inhibitors) could abolish oxLDL-induced angiogenic effects and prevent NO production in the HCAEC. The phosphorylation of Akt, PI3K and eNOS were up-regulated by oxLDL, which was attenuated by LY294002. Our results suggested that oxLDL at low concentration could promote in-vitro angiogenesis and activate nitric oxide synthesis through PI3K/Akt/eNOS pathway in HCAEC.« less

Mechanisms of foam cell formation in atherosclerosis.

PubMed

Chistiakov, Dimitry A; Melnichenko, Alexandra A; Myasoedova, Veronika A; Grechko, Andrey V; Orekhov, Alexander N

2017-11-01

Low-density lipoprotein (LDL) and cholesterol homeostasis in the peripheral blood is maintained by specialized cells, such as macrophages. Macrophages express a variety of scavenger receptors (SR) that interact with lipoproteins, including SR-A1, CD36, and lectin-like oxLDL receptor-1 (LOX-1). These cells also have several cholesterol transporters, including ATP-binding cassette transporter ABCA1, ABCG1, and SR-BI, that are involved in reverse cholesterol transport. Lipids internalized by phagocytosis are transported to late endosomes/lysosomes, where lysosomal acid lipase (LAL) digests cholesteryl esters releasing free cholesterol. Free cholesterol in turn is processed by acetyl-CoA acetyltransferase (ACAT1), an enzyme that transforms cholesterol to cholesteryl esters. The endoplasmic reticulum serves as a depot for maintaining newly synthesized cholesteryl esters that can be processed by neutral cholesterol ester hydrolase (NCEH), which generates free cholesterol that can exit via cholesterol transporters. In atherosclerosis, pro-inflammatory stimuli upregulate expression of scavenger receptors, especially LOX-1, and downregulate expression of cholesterol transporters. ACAT1 is also increased, while NCEH expression is reduced. This results in deposition of free and esterified cholesterol in macrophages and generation of foam cells. Moreover, other cell types, such as endothelial (ECs) and vascular smooth muscle cells (VSMCs), can also become foam cells. In this review, we discuss known pathways of foam cell formation in atherosclerosis.

Suppression of atherosclerosis by synthetic REV-ERB agonist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sitaula, Sadichha; Billon, Cyrielle; Kamenecka, Theodore M.

2015-05-08

The nuclear receptors for heme, REV-ERBα and REV-ERBβ, play important roles in the regulation of metabolism and inflammation. Recently it was demonstrated that reduced REV-ERBα expression in hematopoetic cells in LDL receptor null mice led to increased atherosclerosis. We sought to determine if synthetic REV-ERB agonists that we have developed might have the ability to suppress atherosclerosis in this model. A previously characterized synthetic REV-ERB agonist, SR9009, was used to determine if activation of REV-ERB activity would affect atherosclerosis in LDL receptor deficient mice. Atherosclerotic plaque size was significantly reduced (p < 0.05) in mice administered SR9009 (100 mg/kg) for seven weeks comparedmore » to control mice (n = 10 per group). SR9009 treatment of bone marrow-derived mouse macrophages (BMDM) reduced the polarization of BMDMs to proinflammatory M1 macrophage while increasing the polarization of BMDMs to anti-inflammatory M2 macrophages. Our results suggest that pharmacological targeting of REV-ERBs may be a viable therapeutic option for treatment of atherosclerosis. - Highlights: • Synthetic REV-ERB agonist treatment reduced atherosclerosis in a mouse model. • Pharmacological activation of REV-ERB decreased M1 macrophage polarization. • Pharmacological activation of REV-ERB increased M2 macrophage polarization.« less

Biophysical Analysis of Apolipoprotein E3 Variants Linked with Development of Type III Hyperlipoproteinemia

PubMed Central

Georgiadou, Dimitra; Chroni, Angeliki; Vezeridis, Alexander; Zannis, Vassilis I.; Stratikos, Efstratios

2011-01-01

Background Apolipoprotein E (apoE) is a major protein of the lipoprotein transport system that plays important roles in lipid homeostasis and protection from atherosclerosis. ApoE is characterized by structural plasticity and thermodynamic instability and can undergo significant structural rearrangements as part of its biological function. Mutations in the 136–150 region of the N-terminal domain of apoE, reduce its low density lipoprotein (LDL) receptor binding capacity and have been linked with lipoprotein disorders, such as type III hyperlipoproteinemia (HLP) in humans. However, the LDL-receptor binding defects for these apoE variants do not correlate well with the severity of dyslipidemia, indicating that these variants may carry additional properties that contribute to their pathogenic potential. Methodology/Principal Findings In this study we examined whether three type III HLP predisposing apoE3 variants, namely R136S, R145C and K146E affect the biophysical properties of the protein. Circular dichroism (CD) spectroscopy revealed that these mutations do not significantly alter the secondary structure of the protein. Thermal and chemical unfolding analysis revealed small thermodynamic alterations in each variant compared to wild-type apoE3, as well as effects in the reversibility of the unfolding transition. All variants were able to remodel multillamelar 1,2-Dimyristoyl-sn-glycero-3-phosphocholine (DMPC) vesicles, but R136S and R145C had reduced kinetics. Dynamic light scattering analysis indicated that the variant R136S exists in a higher-order oligomerization state in solution. Finally, 1-anilinonaphthalene-8-sulfonic acid (ANS) binding suggested that the variant R145C exposes a larger amount of hydrophobic surface to the solvent. Conclusions/Significance Overall, our findings suggest that single amino acid changes in the functionally important region 136–150 of apoE3 can affect the molecule's stability and conformation in solution and may underlie functional consequences. However, the magnitude and the non-concerted nature of these changes, make it unlikely that they constitute a distinct unifying mechanism leading to type III HLP pathogenesis. PMID:22069485

Modification of antisense phosphodiester oligodeoxynucleotides by a 5' cholesteryl moiety increases cellular association and improves efficacy.

PubMed

Krieg, A M; Tonkinson, J; Matson, S; Zhao, Q; Saxon, M; Zhang, L M; Bhanja, U; Yakubov, L; Stein, C A

1993-02-01

Phosphodiester oligodeoxynucleotides bearing a 5' cholesteryl (chol) modification bind to low density lipoprotein (LDL), apparently by partitioning the chol-modified oligonucleotides into the lipid layer. Both HL60 cells and primary mouse spleen T and B cells incubated with fluorescently labeled chol-modified oligonucleotide showed substantially increased cellular association by flow cytometry and increased internalization by confocal microscopy compared to an identical molecule not bearing the chol group. Cellular internalization of chol-modified oligonucleotide occurred at least partially through the LDL receptor; it was increased in mouse spleen cells by cell culture in lipoprotein-deficient medium and/or lovastatin, and it was decreased by culture in high serum medium. To determine whether chol-modified oligonucleotides are more potent antisense agents, we titered antisense unmodified phosphodiester and chol-modified oligonucleotides targeted against a mouse immunosuppressive protein. Murine spleen cells cultured with 20 microM phosphodiester antisense oligonucleotides had a 2-fold increase in RNA synthesis, indicating the expected lymphocyte activation. Antisense chol-modified oligonucleotides showed an 8-fold increase in relative potency: they caused a 2-fold increase in RNA synthesis at just 2.5 microM. The increased efficacy was blocked by heparin and was further increased by cell culture in 1% (vs. 10%) fetal bovine serum, suggesting that the effect may, at least in part, be mediated via the LDL receptor. Antisense chol-modified oligonucleotides are sequence specific and have increased potency as compared to unmodified oligonucleotides.

Salidroside protects against foam cell formation and apoptosis, possibly via the MAPK and AKT signaling pathways.

PubMed

Ni, Jing; Li, Yuanmin; Li, Weiming; Guo, Rong

2017-10-10

Foam cell formation and apoptosis are closely associated with atherosclerosis pathogenesis. We determined the effect of salidroside on oxidized low-density lipoprotein (ox-LDL)-induced foam cell formation and apoptosis in THP1 human acute monocytic leukemia cells and investigated the associated molecular mechanisms. THP1-derived macrophages were incubated with salidroside for 5 h and then exposed to ox-LDL for 24 h to induce foam cell formation. Cytotoxicity, lipid deposition, apoptosis, and the expression of various proteins were tested using the CCK8 kit, Oil Red O staining, flow cytometry, and western blotting, respectively. Ox-LDL treatment alone promoted macrophage-derived foam cell formation, while salidroside treatment alone inhibited it (p < 0.05). The number of early/late apoptotic cells decreased with salidroside treatment in a dose-dependent manner (p < 0.05). Salidroside dramatically upregulated nuclear factor erythroid 2-related factor 2, but had no effect on heme oxygenase-1 expression; moreover, it markedly downregulated ox-LDL receptor 1 and upregulated ATP-binding cassette transporter A1. Salidroside also obviously decreased the phosphorylation of JNK, ERK, p38 MAPK, and increased that of Akt. However, the total expression of these proteins was not affected. Based on our findings, we speculate that salidroside can suppress ox-LDL-induced THP1-derived foam cell formation and apoptosis, partly by regulating the MAPK and Akt signaling pathways.

Endothelial LOX-1 activation differentially regulates arterial thrombus formation depending on oxLDL levels: role of the Oct-1/SIRT1 and ERK1/2 pathways.

PubMed

Akhmedov, Alexander; Camici, Giovanni G; Reiner, Martin F; Bonetti, Nicole R; Costantino, Sarah; Holy, Erik W; Spescha, Remo D; Stivala, Simona; Schaub Clerigué, Ariane; Speer, Thimoteus; Breitenstein, Alexander; Manz, Jasmin; Lohmann, Christine; Paneni, Francesco; Beer, Juerg-Hans; Lüscher, Thomas F

2017-04-01

The lectin-like oxLDL receptor-1 (LOX-1) promotes endothelial uptake of oxidized low-density lipoprotein (oxLDL) and plays an important role in atherosclerosis and acute coronary syndromes (ACS). However, its role in arterial thrombus formation remains unknown. We investigated whether LOX-1 plays a role in arterial thrombus formation in vivo at different levels of oxLDL using endothelial-specific LOX-1 transgenic mice (LOX-1TG) and a photochemical injury thrombosis model of the carotid artery. In mice fed a normal chow diet, time to arterial occlusion was unexpectedly prolonged in LOX-1TG as compared to WT. In line with this, tissue factor (TF) expression and activity in carotid arteries of LOX-1TG mice were reduced by half. This effect was mediated by activation of octamer transcription factor 1 (Oct-1) leading to upregulation of the mammalian deacetylase silent information regulator-two 1 (SIRT1) via binding to its promoter and subsequent inhibition of NF-κB signaling. In contrast, intravenous injection of oxLDL as well as high cholesterol diet for 6 weeks led to a switch from the Oct-1/SIRT1 signal transduction pathway to the ERK1/2 pathway and in turn to an enhanced thrombotic response with shortened occlusion time. Thus, LOX-1 differentially regulates thrombus formation in vivo depending on the degree of activation by oxLDL. At low oxLDL levels LOX-1 activates the protective Oct-1/SIRT1 pathway, while at higher levels of the lipoprotein switches to the thrombogenic ERK1/2 pathway. These findings may be important for arterial thrombus formation in ACS and suggest that SIRT1 may represent a novel therapeutic target in this context. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

Sex-dependent Association of a Common Low Density Lipoprotein Receptor Polymorphism with RNA Splicing Efficiency in the Brain and Alzheimers Disease

PubMed Central

Zou, Fanggeng; Gopalraj, Rangaraj K.; Lok, Johann; Zhu, Haiyan; Ling, I-Fang; Simpson, James F.; Tucker, H. Michael; Kelly, Jeremiah F.; Younkin, Samuel G.; Dickson, Dennis W.; Petersen, Ronald C; Graff-Radford, Neill R.; Bennett, David A.; Crook, Julia E.; G.Younkin, Steven; Estus, Steven

2008-01-01

Since apoE allele status is the predominant Alzheimers disease (AD) genetic risk factor, functional single nucleotide polymorphisms (SNP)s in brain apoE receptors represent excellent candidates for association with AD. Recently, we identified a SNP, rs688, as modulating the splicing efficiency of low-density lipoprotein receptor (LDLR) exon 12 in the female human liver and in minigene transfected HepG2 cells. Moreover, the rs688T minor allele associated with significantly higher LDL and total cholesterol in women in the Framingham Offspring Study. Since LDLR is a major apoE receptor in the brain, we hypothesized that rs688 modulates LDLR splicing in neural tissues and associates with AD. To evaluate this hypothesis, we first transfected LDLR minigenes into SH-SY5Y neuroblastoma cells and found that rs688T reduces exon 12 inclusion in this neural model. We then evaluated rs688 association with exon 12 splicing efficiency in vivo by quantifying LDLR splicing in human anterior cingulate tissue obtained at autopsy; the rs688T allele associated with decreased LDLR exon 12 splicing efficiency in aged men but not women. Lastly, we evaluated whether rs688 associates with AD by genotyping DNA from 1,457 men and 2,055 women drawn from three case-control series. The rs688T/T genotype was associated with increased AD odds in males (recessive model, odds ratio (OR) of 1.49, 95% confidence interval (CI) of 1.13−1.97, uncorrected p=0.005), but not in females. In summary, these studies identify a functional apoE receptor SNP that is associated with AD in a sex-dependent fashion. PMID:18065781

The Natural Compound Dansameum Reduces foam Cell Formation by Downregulating CD36 and Peroxisome Proliferator-activated Receptor-gamma; Expression

PubMed Central

Park, Kang-Seo; Ahn, Sang Hyun; Lee, Kang Pa; Park, Sun-Young; Cheon, Jin Hong; Choi, Jun-Yong; Kim, Kibong

2017-01-01

Background: Atherosclerosis-induced vascular disorders are major causes of death in most western countries. During the development of atherosclerotic lesions, foam cell formation is essential and formed through the expression of CD36 and the peroxisome proliferator-activated receptor gamma (PPAR-γ). Objective: To investigate whether dansameum extract (DSE) could show anti-atherosclerotic effect through down-regulating cellular redox state including CD36 and PARP-γ expression in oxidative low-density lipoprotein (oxLDL)-treated RAW264.7 cells and on differentiated foam cells in ApoE Knockout (ApoE-/-) mice. Materials and Methods: The Korean polyherbal medicine DSE was prepared from three plants in the following proportions: 40 g of Salvia miltiorrhiza root, 4 g of Amomumxanthioides fruit, and 4 g of Santalum album lignum. The immunohistochemistry and reverse transcription-polymerase chain reaction was used for analysis of protein and mRNA involved in foam cell formation. Results: We first showed that effects of DSE on foam cell formation in both oxLDL-induced RAW264.7 cells and in blood vessels from apolipoprotein E deficientApoE-/- mice with high fat diet-fed. DSE treatment significantly reduced the expression of CD36 and PPAR-γ in oxLDL-stimulated RAW264.7 cells and ApoE-/-mice, in the latter case by regulating heme oxygenase-1. Furthermore, DSE treatment also reduced cellular lipid content in vitro and in vivo experiments. Conclusion: Our data suggest that DSE may have anti-atherosclerotic properties through regulating foam cell formation. SUMMARY Dansameum extract (DSE) Regulates the expression of CD36 and peroxisome proliferator-activated receptor gamma in oxidative low-density lipoprotein-stimulated RAW264.7 Cells and ApoE Knockout (ApoE Knockout [ApoE-/-]) miceDSE Regulates Cholesterol Levels in the Serum of ApoE-deficient (ApoE-/-) miceDSE Reduced the Formation of Foam Cells by Regulating heme oxygenase-1 in ApoE-/- mice with high fat diet-fed. Abbreviations used: DSE: Dansameum extract, PPAR-γ: Peroxisome proliferator-activated receptor γ, HO-1: Heme oxygenase-1, CVD: Cardiovascular diseases PMID:29491646

The Natural Compound Dansameum Reduces foam Cell Formation by Downregulating CD36 and Peroxisome Proliferator-activated Receptor-gamma; Expression.

PubMed

Park, Kang-Seo; Ahn, Sang Hyun; Lee, Kang Pa; Park, Sun-Young; Cheon, Jin Hong; Choi, Jun-Yong; Kim, Kibong

2018-01-01

Atherosclerosis-induced vascular disorders are major causes of death in most western countries. During the development of atherosclerotic lesions, foam cell formation is essential and formed through the expression of CD36 and the peroxisome proliferator-activated receptor gamma (PPAR-γ). To investigate whether dansameum extract (DSE) could show anti-atherosclerotic effect through down-regulating cellular redox state including CD36 and PARP-γ expression in oxidative low-density lipoprotein (oxLDL)-treated RAW264.7 cells and on differentiated foam cells in ApoE Knockout (ApoE-/-) mice. The Korean polyherbal medicine DSE was prepared from three plants in the following proportions: 40 g of Salvia miltiorrhiza root, 4 g of Amomumxanthioides fruit, and 4 g of Santalum album lignum. The immunohistochemistry and reverse transcription-polymerase chain reaction was used for analysis of protein and mRNA involved in foam cell formation. We first showed that effects of DSE on foam cell formation in both oxLDL-induced RAW264.7 cells and in blood vessels from apolipoprotein E deficientApoE-/- mice with high fat diet-fed. DSE treatment significantly reduced the expression of CD36 and PPAR-γ in oxLDL-stimulated RAW264.7 cells and ApoE-/-mice, in the latter case by regulating heme oxygenase-1. Furthermore, DSE treatment also reduced cellular lipid content in vitro and in vivo experiments. Our data suggest that DSE may have anti-atherosclerotic properties through regulating foam cell formation. Dansameum extract (DSE) Regulates the expression of CD36 and peroxisome proliferator-activated receptor gamma in oxidative low-density lipoprotein-stimulated RAW264.7 Cells and ApoE Knockout (ApoE Knockout [ApoE-/-]) miceDSE Regulates Cholesterol Levels in the Serum of ApoE-deficient (ApoE-/-) miceDSE Reduced the Formation of Foam Cells by Regulating heme oxygenase-1 in ApoE-/- mice with high fat diet-fed. Abbreviations used: DSE: Dansameum extract, PPAR-γ: Peroxisome proliferator-activated receptor γ, HO-1: Heme oxygenase-1, CVD: Cardiovascular diseases.

LDL receptor-related protein 1 regulates the abundance of diverse cell-signaling proteins in the plasma membrane proteome.

PubMed

Gaultier, Alban; Simon, Gabriel; Niessen, Sherry; Dix, Melissa; Takimoto, Shinako; Cravatt, Benjamin F; Gonias, Steven L

2010-12-03

LDL receptor-related protein 1 (LRP1) is an endocytic receptor, reported to regulate the abundance of other receptors in the plasma membrane, including uPAR and tissue factor. The goal of this study was to identify novel plasma membrane proteins, involved in cell-signaling, that are regulated by LRP1. Membrane protein ectodomains were prepared from RAW 264.7 cells in which LRP1 was silenced and control cells using protease K. Peptides were identified by LC-MS/MS. By analysis of spectral counts, 31 transmembrane and secreted proteins were regulated in abundance at least 2-fold when LRP1 was silenced. Validation studies confirmed that semaphorin4D (Sema4D), plexin domain-containing protein-1 (Plxdc1), and neuropilin-1 were more abundant in the membranes of LRP1 gene-silenced cells. Regulation of Plxdc1 by LRP1 was confirmed in CHO cells, as a second model system. Plxdc1 coimmunoprecipitated with LRP1 from extracts of RAW 264.7 cells and mouse liver. Although Sema4D did not coimmunoprecipitate with LRP1, the cell-surface level of Sema4D was increased by RAP, which binds to LRP1 and inhibits binding of other ligands. These studies identify Plxdc1, Sema4D, and neuropilin-1 as novel LRP1-regulated cell-signaling proteins. Overall, LRP1 emerges as a generalized regulator of the plasma membrane proteome.

Lower Squalene Epoxidase and Higher Scavenger Receptor Class B Type 1 Protein Levels Are Involved in Reduced Serum Cholesterol Levels in Stroke-Prone Spontaneously Hypertensive Rats.

PubMed

Michihara, Akihiro; Mido, Mayuko; Matsuoka, Hiroshi; Mizutani, Yurika

2015-01-01

A lower serum cholesterol level was recently shown to be one of the causes of stroke in an epidemiological study. Spontaneously hypertensive rats stroke-prone (SHRSP) have lower serum cholesterol levels than normotensive Wistar-Kyoto rats (WKY). To elucidate the mechanisms responsible for the lower serum cholesterol levels in SHRSP, we determined whether the amounts of cholesterol biosynthetic enzymes or the receptor and transporter involved in cholesterol uptake and efflux in the liver were altered in SHRSP. When the mRNA levels of seven cholesterol biosynthetic enzymes were measured using real-time polymerase chain reaction (PCR), farnesyl pyrophosphate synthase and squalene epoxidase (SQE) levels in the liver of SHRSP were significantly lower than those in WKY. SQE protein levels were significantly reduced in tissues other than the brain of SHRSP. No significant differences were observed in low-density lipoprotein (LDL) receptor (uptake of serum LDL-cholesterol) or ATP-binding cassette transporter A1 (efflux of cholesterol from the liver/formation of high-density lipoprotein (HDL)) protein levels in the liver and testis between SHRSP and WKY, whereas scavenger receptor class B type 1 (SRB1: uptake of serum HDL-cholesterol) protein levels were higher in the livers of SHRSP. These results indicated that the lower protein levels of SQE and higher protein levels of SRB1 in the liver were involved in the reduced serum cholesterol levels in SHRSP.

Efficacy of Rosuvastatin in Children With Homozygous Familial Hypercholesterolemia and Association With Underlying Genetic Mutations.

PubMed

Stein, Evan A; Dann, Eldad J; Wiegman, Albert; Skovby, Flemming; Gaudet, Daniel; Sokal, Etienne; Charng, Min-Ji; Mohamed, Mafauzy; Luirink, Ilse; Raichlen, Joel S; Sundén, Mattias; Carlsson, Stefan C; Raal, Frederick J; Kastelein, John J P

2017-08-29

Homozygous familial hypercholesterolemia (HoFH), a rare genetic disorder, is characterized by extremely elevated levels of low-density lipoprotein cholesterol (LDL-C) and accelerated atherosclerotic cardiovascular disease. Statin treatment starts at diagnosis, but no statin has been formally evaluated in, or approved for, HoFH children. The authors sought to assess the LDL-C efficacy of rosuvastatin versus placebo in HoFH children, and the relationship with underlying genetic mutations. This was a randomized, double-blind, 12-week, crossover study of rosuvastatin 20 mg versus placebo, followed by 12 weeks of open-label rosuvastatin. Patients discontinued all lipid-lowering treatment except ezetimibe and/or apheresis. Clinical and laboratory assessments were performed every 6 weeks. The relationship between LDL-C response and genetic mutations was assessed by adding children and adults from a prior HoFH rosuvastatin trial. Twenty patients were screened, 14 randomized, and 13 completed the study. The mean age was 10.9 years; 8 patients were on ezetimibe and 7 on apheresis. Mean LDL-C was 481 mg/dl (range: 229 to 742 mg/dl) on placebo and 396 mg/dl (range: 130 to 700 mg/dl) on rosuvastatin, producing a mean 85.4 mg/dl (22.3%) difference (p = 0.005). Efficacy was similar regardless of age or use of ezetimibe or apheresis, and was maintained for 12 weeks. Adverse events were few and not serious. Patients with 2 defective versus 2 negative LDL receptor mutations had mean LDL-C reductions of 23.5% (p = 0.0044) and 14% (p = 0.038), respectively. This first-ever pediatric HoFH statin trial demonstrated safe and effective LDL-C reduction with rosuvastatin 20 mg alone or added to ezetimibe and/or apheresis. The LDL-C response in children and adults was related to underlying genetic mutations. (A Study to Evaluate the Efficacy and Safety of Rosuvastatin in Children and Adolescents With Homozygous Familial Hypercholesterolemia [HYDRA]; NCT02226198). Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Potential role of lycopene in targeting proprotein convertase subtilisin/kexin type-9 to combat hypercholesterolemia.

PubMed

Sultan Alvi, Sahir; Ansari, Irfan A; Khan, Imran; Iqbal, Johar; Khan, M Salman

2017-07-01

Proprotein convertase subtilisin/kexin type 9 (PCSK-9) is a serine protease of the proprotien convertase (PC) family that has profound effects on plasma low density lipoprotein cholesterol (LDL-C) levels, the major risk factor for coronary heart disease (CHD), through its ability to mediate LDL receptor (LDL-R) protein degradation and reduced recycling to the surface of hepatocytes. Thus, the current study was premeditated not only to evaluate the role of lycopene in targeting the inhibition of PCSK-9 via modulation of genes involved in cholesterol homeostasis in HFD rats but also to examine a correlation between HFD induced inflammatory cascades and subsequent regulation of PCSK-9 expression. Besides the effect of lycopene on hepatic PCSK-9 gene expression, PPI studies for PCSK-9-Lycopene complex and EGF-A of LDL-R were also performed via molecular informatics approach to assess the dual mode of action of lycopene in LDL-R recycling and increased removal of circulatory LDL-C. We for the first time deciphered that lycopene treatment significantly down-regulates the expression of hepatic PCSK-9 and HMGR, whereas, hepatic LDL-R expression was significantly up-regulated. Furthermore, lycopene ameliorated inflammation stimulated expression of PCSK-9 via suppressing the expression of inflammatory markers. The results from our molecular informatics studies confirmed that lycopene, while occupying the active site of PCSK-9 crystal structure, reduces the affinity of PCSK-9 to complex with EGF-A of LDL-R, whereas, atorvastatin makes PCSK-9-EGF-A complex formation more feasible than both of PCSK-9-EGF-A alone and Lycopene-PCSK-9-EGF-A complex. Based on above results, it can be concluded that lycopene exhibits potent hypolipidemic activities via molecular mechanisms that are either identical (HMGR inhibition) or distinct from that of statins (down-regulation of PCSK-9 mRNA synthesis). To the best of our knowledge, this is the first report that lycopene has this specific biological property. Being a natural, safer and alternative therapeutic agent, lycopene could be used as a complete regulator of cholesterol homeostasis and ASCVD. Copyright © 2017 Elsevier Inc. All rights reserved.

The food matrix and sterol characteristics affect the plasma cholesterol lowering of phytosterol/phytostanol.

PubMed

Cusack, Laura Kells; Fernandez, Maria Luz; Volek, Jeff S

2013-11-01

Foods with added phytosterols/phytostanols (PS) are recommended to lower LDL cholesterol (LDL-c) concentrations. Manufacturers have incorporated PS into a variety of common foods. Understanding the cholesterol-lowering impact of the food matrix and the PS characteristics would maximize their success and increase the benefit to consumers. This review systematically examines whether the PS characteristics and the fatty acid composition of foods with added PS affects serum LDL-c. A total of 33 studies published between the years 1998 and 2011 inclusive of 66 individual primary variables (strata) were evaluated. The functional food matrices included margarine, mayonnaise, yogurt, milk, cheese, meat, grain, juice, and chocolate. Consistently, ≥10% reductions in LDL-c were reported when the characteristics of the food matrix included poly- and monounsaturated fatty acids known to lower LDL-c. Also, >10% mean reductions in LDL-c were reported when β-sitostanol and campestanol as well as stanol esters were used. These characteristics allow both low-fat and high-fat foods to successfully incorporate PS and significantly lower LDL-c.

Pleiotropic Effects of Statins on the Cardiovascular System.

PubMed

Oesterle, Adam; Laufs, Ulrich; Liao, James K

2017-01-06

The statins have been used for 30 years to prevent coronary artery disease and stroke. Their primary mechanism of action is the lowering of serum cholesterol through inhibiting hepatic cholesterol biosynthesis thereby upregulating the hepatic low-density lipoprotein (LDL) receptors and increasing the clearance of LDL-cholesterol. Statins may exert cardiovascular protective effects that are independent of LDL-cholesterol lowering called pleiotropic effects. Because statins inhibit the production of isoprenoid intermediates in the cholesterol biosynthetic pathway, the post-translational prenylation of small GTP-binding proteins such as Rho and Rac, and their downstream effectors such as Rho kinase and nicotinamide adenine dinucleotide phosphate oxidases are also inhibited. In cell culture and animal studies, these effects alter the expression of endothelial nitric oxide synthase, the stability of atherosclerotic plaques, the production of proinflammatory cytokines and reactive oxygen species, the reactivity of platelets, and the development of cardiac hypertrophy and fibrosis. The relative contributions of statin pleiotropy to clinical outcomes, however, remain a matter of debate and are hard to quantify because the degree of isoprenoid inhibition by statins correlates to some extent with the amount of LDL-cholesterol reduction. This review examines some of the currently proposed molecular mechanisms for statin pleiotropy and discusses whether they could have any clinical relevance in cardiovascular disease. © 2017 American Heart Association, Inc.

Autosomal recessive hypercholesterolemia in Spain.

PubMed

Sánchez-Hernández, Rosa María; Prieto-Matos, Pablo; Civeira, Fernando; Lafuente, Eduardo Esteve; Vargas, Manuel Frías; Real, José T; Goicoechea, Fernando Goñi; Fuentes, Francisco J; Pocovi, Miguel; Boronat, Mauro; Wägner, Ana María; Masana, Luis

2018-02-01

Autosomal recessive hypercholesterolemia (ARH) is a very rare disease, caused by mutations in LDL protein receptor adaptor 1 (LDLRAP1). It is characterized by high levels of low-density lipoprotein cholesterol (LDL-C) and increased risk of premature cardiovascular disease. We aimed to characterize ARH in Spain. Data were collected from the Dyslipidemia Registry of the Spanish Atherosclerosis Society. A literature search was performed up to June 2017, and all diagnostic genetic studies for familial hypercholesterolemia of Spain were reviewed. Seven patients with ARH were identified, 6 true homozygous and one compound heterozygous with a novel mutation: c.[863C>T];p.[Ser288Leu]. High genetic heterogeneity was found in this cohort. True homozygous subjects for LDLRAP1 have more severe phenotypes than the compound heterozygous patient, but similar to patients with homozygous familial hypercholesterolemia (HoFH). Cardiovascular disease was present in 14% of the ARH patients. LDL-C under treatment was above 185 mg/dl and the response to PCSK9 inhibitors was heterogeneous. Finally, the estimated prevalence in Spain is very low, with just 1 case per 6.5 million people. ARH is a very rare disease in Spain, showing high genetic heterogeneity, similarly high LDL-C concentrations, but lower incidence of ASCVD than HoFH. Copyright © 2017 Elsevier B.V. All rights reserved.

Purified low-density lipoprotein and bovine serum albumin efficiency to internalise lycopene into adipocytes.

PubMed

Gouranton, Erwan; Yazidi, Claire El; Cardinault, Nicolas; Amiot, Marie Josèphe; Borel, Patrick; Landrier, Jean-François

2008-12-01

Epidemiological studies have suggested that lycopene has protective effects against various diseases including cardiovascular diseases. However, mechanistic studies to understand these effects are difficult due to the insolubility of lycopene in aqueous culture medium. The objective of the present study was to use LDL or BSA as physiological vehicles for lycopene and to compare them with various classical vehicles. Among tested vehicles, only LDL, BSA, THF/BHT, beadlets, and liposomes were able to solubilise lycopene. No cytotoxicity was observed with these vehicles. LDL and BSA allowed good stability of lycopene during incubation (52% and 43% for 2microM lycopene solutions), but remained less efficient than THF/BHT or beadlets (67% and 62%). Incubation of adipocytes (3T3-L1) with the different vehicles for 24 and 48h showed that beadlets best delivered lycopene to cells. Finally, whatever the vehicle used, intracellular localization of lycopene was the same: lipid droplets (32-51%), plasma membrane (32-37%) and nuclear membrane (19-29%). As a conclusion, LDL or BSA display comparable properties to THF/BHT or beadlets. It is the first time that lycopene carried by physiological vehicles is shown to reach different subcellular compartments supporting molecular effects in adipocyte, such as cell signaling or nuclear receptor interacting.

Therapeutic Management of Familial Hypercholesterolemia: Current and Emerging Drug Therapies.

PubMed

Patel, Roshni S; Scopelliti, Emily M; Savelloni, Julie

2015-12-01

Familial hypercholesterolemia (FH) is a genetic disorder characterized by significantly elevated low-density lipoprotein cholesterol (LDL-C) concentrations that result from mutations of the LDL receptor, apolipoprotein B (apo B-100), and proprotein convertase subtilisin/kexin type 9 (PCSK9). Early and aggressive treatment can prevent premature atherosclerotic cardiovascular disease in these high-risk patients. Given that the cardiovascular consequences of FH are similar to typical hypercholesterolemia, traditional therapies are utilized to decrease LDL-C levels. Patients with FH should receive statins as first-line treatment; high-potency statins at high doses are often required. Despite the use of statins, additional treatments are often necessary to achieve appropriate LDL-C lowering in this patient population. Novel drug therapies that target the pathophysiologic defects of the condition are continuously emerging. Contemporary therapies including mipomersen (Kynamro, Genzyme), an oligonucleotide inhibitor of apo B-100 synthesis; lomitapide (Juxtapid, Aegerion), a microsomal triglyceride transfer protein inhibitor; and alirocumab (Praluent, Sanofi-Aventis/Regeneron) and evolocumab (Repatha, Amgen), PCSK9 inhibitors, are currently approved by the U.S. Food and Drug Administration for use in FH. This review highlights traditional as well as emerging contemporary therapies with supporting clinical data to evaluate current recommendations and discuss the future direction of FH management. © 2015 Pharmacotherapy Publications, Inc.

[Compliance with recommendations in secondary prevention of stroke in primary care].

PubMed

Tamayo-Ojeda, Carmen; Parellada-Esquius, Neus; Salvador-González, Betlem; Oriol-Torón, Pilar Ángeles; Rodríguez-Garrido, M Dolores; Muñoz-Segura, Dolores

Knowing compliance with secondary prevention recommendations of stroke in primary care and to identify factors associated with compliance. Multi-centre cross-sectional. Health primary care centres in a metropolitan area (944,280 inhabitants). Patients aged 18years and over with ischemic brain disease diagnosis prior to 6months before the study. Clinical history records of demographic variables, risk factors and cardiovascular comorbidity, drugs, blood pressure values (BP), LDL-cholesterol and medical visits by doctor and nurses after the event. Good adherence was considered when BP <140/90 mmHg, LDL-cholesterol <100 mg/dL, smoking abstention and preventive drugs prescription (anti-platelet/anticoagulants, statins and angiotensin-converting-enzyme inhibitors/angiotensin-receptor-antagonists or diuretics) during the last 18months. A total of 21,976 patients, mean age 73.12 years (SD: 12.13), 48% women, 72.7% with stroke. Co-morbidity: hypertension 70.8%, dyslipidemia 55.1%, DM 30.9%, atrial fibrillation 14.1%, ischemic heart disease 13.5%, chronic renal failure 12.5%, heart failure 8.8%, peripheral arterial disease 6.2%, dementia 7.8%. No record was found for smoking in 3.7%, for BP in 3.5% and for LDL in 6.5%. Optimal control: abstention smoking in 3.7%, BP <140/90 in 65.7% and LDL <100 mg/dL in 41.0%. 86.2% anti-platelet/anticoagulants, 61.3% statins and 61.8% angiotensin-converting-enzyme inhibitors, angiotensin-receptor-antagonists or diuretic. Registration and risk factors control was higher in 66-79years aged and lower in 18-40years aged. The implementation of clinical guidelines recommendations for stroke prevention in primary care must be improved, especially among younger population. Organizational changes and more active involvement by professionals and strategies against therapeutic inertia must be taken. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Accumulation of Oxidized LDL in the Tendon Tissues of C57BL/6 or Apolipoprotein E Knock-Out Mice That Consume a High Fat Diet: Potential Impact on Tendon Health

PubMed Central

Grewal, Navdeep; Thornton, Gail M.; Behzad, Hayedeh; Sharma, Aishwariya; Lu, Alex; Zhang, Peng; Reid, W. Darlene; Granville, David J.; Scott, Alex

2014-01-01

Objective Clinical studies have suggested an association between dyslipidemia and tendon injuries or chronic tendon pain; the mechanisms underlying this association are not yet known. The objectives of this study were (1) to evaluate the impact of a high fat diet on the function of load-bearing tendons and on the distribution in tendons of oxidized low density lipoprotein (oxLDL), and (2) to examine the effect of oxLDL on tendon fibroblast proliferation and gene expression. Methods Gene expression (Mmp2, Tgfb1, Col1a1, Col3a1), fat content (Oil Red O staining), oxLDL levels (immunohistochemistry) and tendon biomechanical properties were examined in mice (C57Bl/6 or ApoE -/-) receiving a standard or a high fat diet. Human tendon fibroblast proliferation and gene expression (COL1A1, COL3A1, MMP2) were examined following oxLDL exposure. Results In both types of mice (C57Bl/6 or ApoE -/-), consumption of a high fat diet led to a marked increase in oxLDL deposition in the load-bearing extracellular matrix of the tendon. The consumption of a high fat diet also reduced the failure stress and load of the patellar tendon in both mouse types, and increased Mmp2 expression. ApoE -/- mice exhibited more pronounced reductions in tendon function than wild-type mice, and decreased expression of Col1a1 compared to wild type mice. Human tendon fibroblasts responded to oxLDL by increasing their proliferation and their mRNA levels of MMP2, while decreasing their mRNA levels for COL1A1 and COL3A1. Conclusion The consumption of a high fat diet resulted in deleterious changes in tendon function, and these changes may be explained in part by the effects of oxLDL, which induced a proliferative, matrix-degrading phenotype in human tenocytes. PMID:25502628

First-Generation Antipsychotic Haloperidol Alters the Functionality of the Late Endosomal/Lysosomal Compartment in Vitro

PubMed Central

Canfrán-Duque, Alberto; Barrio, Luis C.; Lerma, Milagros; de la Peña, Gema; Serna, Jorge; Pastor, Oscar; Lasunción, Miguel A.; Busto, Rebeca

2016-01-01

First- and second-generation antipsychotics (FGAs and SGAs, respectively), have the ability to inhibit cholesterol biosynthesis and also to interrupt the intracellular cholesterol trafficking, interfering with low-density lipoprotein (LDL)-derived cholesterol egress from late endosomes/lysosomes. In the present work, we examined the effects of FGA haloperidol on the functionality of late endosomes/lysosomes in vitro. In HepG2 hepatocarcinoma cells incubated in the presence of 1,1′-dioctadecyl-3,3,3,3′-tetramethylindocarbocyanineperchlorate (DiI)-LDL, treatment with haloperidol caused the enlargement of organelles positive for late endosome markers lysosome-associated membrane protein 2 (LAMP-2) and LBPA (lysobisphosphatidic acid), which also showed increased content of both free-cholesterol and DiI derived from LDL. This indicates the accumulation of LDL-lipids in the late endosomal/lysosomal compartment caused by haloperidol. In contrast, LDL traffic through early endosomes and the Golgi apparatus appeared to be unaffected by the antipsychotic as the distribution of both early endosome antigen 1 (EEA1) and coatomer subunit β (β-COP) were not perturbed. Notably, treatment with haloperidol significantly increased the lysosomal pH and decreased the activities of lysosomal protease and β-d-galactosidase in a dose-dependent manner. We conclude that the alkalinization of the lysosomes’ internal milieu induced by haloperidol affects lysosomal functionality. PMID:26999125

Expression of very low density lipoprotein receptor mRNA in circulating human monocytes: its up-regulation by hypoxia.

PubMed

Nakazato, K; Ishibashi, T; Nagata, K; Seino, Y; Wada, Y; Sakamoto, T; Matsuoka, R; Teramoto, T; Sekimata, M; Homma, Y; Maruyama, Y

2001-04-01

Although very low density lipoprotein (VLDL) receptor expression by macrophages has been shown in the vascular wall, it is not clear whether or not circulating monocytes express the VLDL receptor. We investigated the expression of VLDL receptor mRNA in human peripheral blood monocytes and monocyte-derived macrophages by reverse transcriptase polymerase chain reaction (RT-PCR) and nucleotide sequencing after subcloning of PCR product. VLDL receptor mRNA was detected both in peripheral blood monocytes and monocyte-derived macrophages. Expression of VLDL receptor mRNA was upregulated by hypoxia in monocytes, whereas treatment with oxidized LDL, interleukin-1beta or monocyte chemoattractant protein-1 did not affect the levels of VLDL receptor mRNA in monocytes and macrophages. The present study shows a novel response of VLDL receptor mRNA to hypoxia, suggesting a role for VLDL receptor in the metabolism of lipoproteins in the vascular wall and the development of atherosclerosis.

Protective effect of Xingnaojia formulation on rats with brain and liver damage caused by chronic alcoholism.

PubMed

Li, Shuang; Wang, S U; Guo, Zhi-Gang; Huang, Ning; Zhao, Fan-Rong; Zhu, Mo-Li; Ma, Li-Juan; Liang, Jin-Ying; Zhang, Yu-Lin; Huang, Zhong-Lin; Wan, Guang-Rui

2015-11-01

The aim of this study was to observe the effect of a formulation of traditional Chinese medicine extracts known as Xingnaojia (XNJ) on the liver function, learning ability and memory of rats with chronic alcoholism and to verify the mechanism by which it protects the brain and liver. A rat model of chronic alcoholism was used in the study. The spatial learning ability and memory of the rats were tested. The rats were then sacrificed and their brains and hepatic tissues were isolated. The activity of superoxide dismutase (SOD) and levels of glutamate (Glu), N-methyl D-aspartate receptor subtype 2B (NR2B), cyclin-dependent kinase 5 (CDK5) and cannabinoid receptor 1 (CB1) in the hippocampus were analyzed. The ultrastructure of the hepatic tissue was observed by electron microscopy. In addition, the activities of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in serum were tested and the levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG) and total cholesterol (TCHOL) were analyzed. XNJ enhanced the learning and memory of rats with chronic alcoholism. Treatment with XNJ increased the activity of SOD, and decreased the expression levels of NR2B mRNA and NR2B, CB1 and CDK5 proteins in the brain tissues compared with those in the model rats. It also increased the activity of ALDH in the serum and liver, decreased the serum levels of LDL, TG and TCHOL and increased the serum level of HDL. These results indicate that XNJ exhibited a protective effect against brain and liver damage in rats with chronic alcoholism.

Lysophosphatidylcholine-induced cytotoxicity in osteoblast-like MG-63 cells: involvement of transient receptor potential vanilloid 2 (TRPV2) channels.

PubMed

Fallah, Abdallah; Pierre, Rachel; Abed, Elie; Moreau, Robert

2013-01-01

Epidemiological studies indicate that patients suffering from atherosclerosis are predisposed to develop osteoporosis. Accordingly, atherogenic determinants such as oxidized low density lipoprotein (OxLDL) particles have been shown to alter bone cell functions. In this work, we investigated the cytotoxicity of lysophosphatidylcholine (lysoPC), a major phospholipid component generated upon LDL oxidation, on bone-forming MG-63 osteoblast-like cells. Cell viability was reduced by lysoPC in a concentration-dependent manner with a LC50 of 18.7±0.7 μM. LysoPC-induced cell death was attributed to induction of both apoptosis and necrosis. Since impairment of intracellular calcium homeostasis is often involved in mechanism of cell death, we determined the involvement of calcium in lysoPC-induced cytotoxicity. LysoPC promoted a rapid and transient increase in intracellular calcium attributed to mobilization from calcium stores, followed by a sustained influx. Intracellular calcium mobilization was associated to phospholipase C (PLC)-dependent mobilization of calcium from the endoplasmic reticulum since inhibition of PLC or calcium depletion of reticulum endoplasmic with thapsigargin prevented the calcium mobilization. The calcium influx induced by lysoPC was abolished by inhibition of transient receptor potential vanilloid (TRPV) channels with ruthenium red whereas gadolinium, which inhibits canonical TRP (TRPC) channels, was without effect. Accordingly, expression of TRPV2 and TRPV4 were shown in MG-63 cells. The addition of TRPV2 inhibitor Tranilast in the incubation medium prevent the calcium influx triggered by lysoPC and reduced lysoPC-induced cytotoxicity whereas TRPV4 inhibitor RN 1734 was without effect, which confirms the involvement of TRPV2 activation in lysoPC-induced cell death.

Effect of thyroid function on LDL oxidation.

PubMed

Costantini, F; Pierdomenico, S D; De Cesare, D; De Remigis, P; Bucciarelli, T; Bittolo-Bon, G; Cazzolato, G; Nubile, G; Guagnano, M T; Sensi, S; Cuccurullo, F; Mezzetti, A

1998-05-01

In this study, the effect of different levels of thyroid hormone and metabolic activity on low density lipoprotein (LDL) oxidation was investigated. Thus, in 16 patients with hyperthyroidism, 16 with hypothyroidism, and 16 age- and sex-matched healthy normolipidemic control subjects, the native LDL content in lipid peroxides, vitamin E, beta-carotene, and lycopene, as well as the susceptibility of these particles to undergo lipid peroxidation, was assessed. Hyperthyroidism was associated with significantly higher lipid peroxidation, as characterized by a higher native LDL content in lipid peroxides, a lower lag phase, and a higher oxidation rate than in the other two groups. This elevated lipid peroxidation was associated with a lower LDL antioxidant concentration. Interestingly, hypothyroid patients showed an intermediate behavior. In fact, in hypothyroidism, LDL oxidation was significantly lower than in hyperthyroidism but higher than in the control group. Hypothyroidism was also characterized by the highest beta-carotene LDL content, whereas vitamin E was significantly lower than in control subjects. In hyperthyroidism but not in the other two groups, LDL oxidation was strongly influenced by free thyroxine blood content. In fact in this group, the native LDL lipid peroxide content and the lag phase were directly and indirectly, respectively, related to free thyroxine blood levels. On the contrary, in hypothyroidism LDL oxidation was strongly and significantly related to serum lipids. In conclusion, both hypothyroidism and hyperthyroidism are characterized by higher levels of LDL oxidation when compared with normolipidemic control subjects. In hyperthyroid patients, the increased lipid peroxidation was strictly related to free thyroxine levels, whereas in hypothyroidism it was strongly influenced by serum lipids.

Curcumin modulation of high fat diet-induced atherosclerosis and steatohepatosis in LDL receptor deficient mice

USDA-ARS?s Scientific Manuscript database

Consuming curcumin may benefit health by modulating lipid metabolism and suppressing atherogenesis. Fatty acid binding proteins (FABP-4/aP2) and CD36 expression are key factors in lipid accumulation in macrophages and foam cell formation in atherogenesis. Our earlier observations suggest that curcum...

Antiatherosclerotic effects of Artemisia princeps Pampanini cv. Sajabal in LDL receptor deficient mice.

PubMed

Han, Jong-Min; Kim, Min-Jung; Baek, Seung-Hwa; An, Sojin; Jin, Yue-Yan; Chung, Hae-Gon; Baek, Nam-In; Choi, Myung-Sook; Lee, Kyung-Tae; Jeong, Tae-Sook

2009-02-25

Antiatherosclerotic effects of ethanolic extracts of Artemisia princeps Pampanini cv. Sajabal (ESJ) were investigated in low-density lipoprotein receptor deficient (LDLR(-/-)) mice. The Western diet-induced high levels of total cholesterol and triglyceride were similar in the ESJ and control groups. However, circulating oxidized LDL was significantly decreased in the ESJ group (p < 0.05). ESJ also markedly decreased aortic expression levels of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1 beta (IL-1 beta), and reduced the aortic lesion formation and macrophage accumulation by 36.7% (p < 0.05) and 43% (p < 0.01) in the control group, respectively. Additionally, ESJ inhibited atherogenic properties with cytokine-induced surface expression of cell adhesion molecules, chemokines, and monocyte adhesion to the human umbilical vein endothelial cells (HUVECs), and simultaneously suppressed nuclear factor-kappaB (NF-kappaB) activation. These results suggest that ethanolic extracts of Artemisia princeps Pampanini cv. Sajabal contributes to the antiatherosclerotic and anti-inflammatory activities in LDLR(-/-) mice.

Role of dietary supplements in lowering low-density lipoprotein cholesterol: a review.

PubMed

Nijjar, Prabhjot S; Burke, Frances M; Bloesch, Annette; Rader, Daniel J

2010-01-01

Coronary heart disease (CHD) remains a major source of morbidity and mortality. As the epidemic of obesity, diabetes, and hypertension continues to grow among young adults, the population at risk for atherosclerotic CHD is ever increasing. More than a century of laboratory and human findings link cholesterol levels with a propensity to develop atherosclerosis. Low-density lipoprotein (LDL) is the major atherogenic lipoprotein, and numerous clinical trials have shown the efficacy of lowering LDL-cholesterol (LDL-C) for reducing CHD risk. New trial data have resulted in LDL-C goals being lowered over time and expansion of the population of patients that are candidates for LDL-lowering therapy to decrease their lifetime risk of CHD. Although statins are relatively safe and well tolerated, there are still significant numbers of patients who cannot tolerate them and many others who only require mild LDL-C reduction and prefer nonprescription alternatives to statin therapy. A number of dietary supplements and functional foods have been suggested to reduce LDL-C levels, but only a few have withstood the rigors of randomized controlled trials. Here we review the evidence in support of dietary supplements and their LDL-C-lowering effects. We also review supplements that, after initial excitement about their purported effect, were not found to lower LDL-C significantly. Copyright © 2010 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Group 1B phospholipase A₂ inactivation suppresses atherosclerosis and metabolic diseases in LDL receptor-deficient mice.

PubMed

Hollie, Norris I; Konaniah, Eddy S; Goodin, Colleen; Hui, David Y

2014-06-01

Previous studies have shown that inactivation of the group 1B phospholipase A2 (Pla2g1b) suppresses diet-induced obesity, hyperglycemia, insulin resistance, and hyperlipidemia in C57BL/6 mice. A possible influence of Pla2g1b inactivation on atherosclerosis has not been addressed previously. The current study utilized LDL receptor-deficient (Ldlr(-/-)) mice with plasma lipid levels and distribution similar to hyperlipidemic human subjects as a preclinical animal model to test the effectiveness of Pla2g1b inactivation on atherosclerosis. The Pla2g1b(+/+)Ldlr(-/-) and Pla2g1b(-/-)Ldlr(-/-) mice were fed a low fat chow diet or a hypercaloric diet with 58.5 kcal% fat and 25 kcal% sucrose for 10 weeks. Minimal differences were observed between Pla2g1b(+/+)Ldlr(-/-) and Pla2g1b(-/-)Ldlr(-/-) mice when the animals were maintained on the low fat chow diet. However, when the animals were maintained on the hypercaloric diet, the Pla2g1(+/+)Ldlr(-/-) mice showed the expected body weight gain but the Pla2g1b(-/-)Ldlr(-/-) mice were resistant to diet-induced body weight gain. The Pla2g1b(-/-)Ldlr(-/-) mice also displayed lower fasting glucose, insulin, and plasma lipid levels compared to the Pla2g1b(+/+)Ldlr(-/-) mice, which displayed robust hyperglycemia, hyperinsulinemia, and hyperlipidemia in response to the hypercaloric diet. Importantly, atherosclerotic lesions in the aortic roots were also reduced 7-fold in the Pla2g1b(-/-)Ldlr(-/-) mice. The effectiveness of Pla2g1b inactivation to suppress diet-induced body weight gain and reduce diabetes and atherosclerosis in LDL receptor-deficient mice suggests that pharmacological inhibition of Pla2g1b may be a viable strategy to decrease diet-induced obesity and the risk of diabetes and atherosclerosis in humans. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Polymorphic haplotypes and recombination rates at the LDL receptor gene locus in subjects with and without familial hypercholesterolemia who are from different populations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miserez, A.R.; Chiodetti, N.; Keller, U.

1993-04-01

RFLPs at the low-density lipoprotein (LDL) receptor locus for TaqI, StuI, HincII, AvaII, ApaLI (5[prime] and 3[prime]), PvuII, and NcoI were studied in Swiss and German families with familial hypercholesterolemia (FH). A total of 1,104 LDL receptor alleles were analyzed using Southern blotting and new PCR-based techniques for detection of the TaqI, StuI, HincII, AvaII, NcoI RFLPs. Two hundred fifty-six independent haplotypes from 368 individuals of 61 unrelated Swiss families, as well as 114 independent haplotypes from 184 subjects of 25 unrelated German families, were constructed. In 76 families, clinical diagnosis of FH was confirmed by cosegregation analysis. Of themore » 43 unique haplotypes consisting of seven RFLPs detected in the Swiss and Germans, only 9 were common in both population samples. Analysis of linkage disequilibrium revealed nonrandom associations between several of the investigated RFLPs. ApaLI (5[prime]), NcoI, PvuII, TaqI, and AvaII or HincII were particularly informative. Relative frequencies, heterozygosity indexes, and PICs of the RFLPs from the Swiss and Germans were compared with values calculated from reported haplotype data for Italians, Icelanders, North American Caucasians, South African Caucasians, and Japanese. Pairwise comparisons of population samples by common RFLPs demonstrated unexpected differences even between geographically adjacent populations (e.g., the Swiss and Germans). Furthermore, genetic distances from the Germans to the other Caucasians were larger than to the Japanese. An unexpected lack of correlation between linkage disequilibria and physical distances was detected for the German and Japanese data, possibly because of nonuniform recombination with excessively high rates between exon 13 and intron 15. Hence, the present study revealed a striking variety of polymorphic haplotypes and heterogeneity of RFLP frequencies and recombination rates among the seven population samples. 60 refs., 2 figs., 8 tabs.« less

Relationship of lipid oxidation with subclinical atherosclerosis and 10-year coronary events in general population.

PubMed

Gómez, Miquel; Vila, Joan; Elosua, Roberto; Molina, Lluís; Bruguera, Jordi; Sala, Joan; Masià, Rafel; Covas, Maria Isabel; Marrugat, Jaume; Fitó, Montserrat

2014-01-01

To assess 1) the association of lipid oxidation biomarkers with 10-year coronary artery disease (CAD) events and subclinical atherosclerosis, and 2) the reclassification capacity of these biomarkers over Framingham-derived CAD risk functions, in a general population. Within the framework of the REGICOR study, 4782 individuals aged between 25 and 74 years were recruited in a population-based cohort study. Follow-up of the 4042 who met the eligibility criteria was carried out. Plasma, circulating oxidized low-density lipoprotein (oxLDL) and oxLDL antibodies (OLAB) were measured in a random sample of 2793 participants. End-points included fatal and non-fatal acute myocardial infarction (AMI) and angina. Carotid intima-media thickness (IMT) in the highest quintile and ankle-brachial index <0.9 were considered indicators of subclinical atherosclerosis. Mean age was 50.0 (13.4) years, and 52.4% were women. There were 103 CAD events (34 myocardial infarction, 43 angina, 26 coronary deaths), and 306 subclinical atherosclerosis cases. Oxidized LDL was independently associated with higher incidence of CAD events (HR = 1.70; 95% Confidence Interval: 1.02-2.84), but not with subclinical atherosclerosis. The net classification index of the Framingham-derived CAD risk function was significantly improved when ox-LDL was included (NRI = 14.67% [4.90; 24.45], P = 0.003). No associations were found between OLAB and clinical or subclinical events. The reference values for oxLDL and OLAB are also provided (percentiles). OxLDL was independently associated with 10-year CAD events but not subclinical atherosclerosis in a general population, and improved the reclassification capacity of Framingham-derived CAD risk functions. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Differential inhibition of oxidized LDL-induced apoptosis in human endothelial cells treated with different flavonoids.

PubMed

Jeong, Yu-Jin; Choi, Yean-Jung; Kwon, Hyang-Mi; Kang, Sang-Wook; Park, Hyoung-Sook; Lee, Myungsook; Kang, Young-Hee

2005-05-01

High plasma level of cholesterol is a well-known risk factor for atherosclerotic diseases. Oxidized LDL induces cellular and nuclear damage that leads to apoptotic cell death. We tested the hypothesis that flavonoids may function as antioxidants with regard to LDL incubated with 5 microm-Cu(2+) alone or in combination with human umbilical vein endothelial cells (HUVEC). Cytotoxicity and formation of thiobarbituric acid-reactive substances induced by Cu(2+)-oxidized LDL were examined in the presence of various subtypes of flavonoid. Flavanols, flavonols and flavanones at a non-toxic dose of 50 microm markedly inhibited LDL oxidation by inhibiting the formation of peroxidative products. In contrast, the flavones luteolin and apigenin had no such effect, with >30 % of cells killed after exposure to 0.1 mg LDL/ml. Protective flavonoids, especially (-)-epigallocatechin gallate, quercetin, rutin and hesperetin, inhibited HUVEC nuclear condensation and fragmentation induced by Cu(2+)-oxidized LDL. In addition, immunochemical staining and Western blot analysis revealed that anti-apoptotic Bcl-2 expression was enhanced following treatment with these protective flavonoids. However, Bax expression and caspase-3 cleavage stimulated by 18 h incubation with oxidized LDL were reduced following treatment with these protective flavonoids. The down-regulation of Bcl-2 and up-regulation of caspase-3 activation were reversed by the cytoprotective flavonoids, (-)-epigallocatechin gallate, quercetin and hesperetin, at >/=10 microm. These results suggest that flavonoids may differentially prevent Cu(2+)-oxidized LDL-induced apoptosis and promote cell survival as potent antioxidants. Survival potentials of certain flavonoids against cytotoxic oxidized LDL appeared to stem from their disparate chemical structure. Furthermore, dietary flavonoids may have therapeutic potential for protecting the endothelium from oxidative stress and oxidized LDL-triggered atherogenesis.

Consumption of a high-fat, high-calorie meal is associated with an increase in intracellular co-localization of PPAR-γ mRNA and protein in monocytes.

PubMed

Henning, Andrea L; McFarlin, Brian K

2017-01-01

Acute and habitual dietary habits contribute to the onset and progression of many forms of cardiovascular disease. Circulating peripheral blood monocytes have been a target of pre-clinical research related to the risk of atherosclerosis. Specifically, when monocytes migrate into the subendothelial space and endocytosize modified LDL (i.e. acLDL or oxLDL) they phenotypically transform into foam cells. The endocytosis of modified LDL is mediated by the scavenger receptor CD36, whose expression is in tern regulated by the transcription factor PPAR-γ. In this report, we describe a novel technique for the simultaneous measurement of intracellular PPAR-γ mRNA and protein in peripheral blood monocytes collected from human subjects in fasted state or 3 and 5-h after consuming a high-calorie (65% of daily calorie needs), high-fat meal. Intracellular detection and co-localization of PPAR-γ was made possible using a combination of image-based flow cytometry (MilliporeSigma FlowSight) and an amplified mRNA FISH staining technique (Affymetrix/eBioscience PrimeFlow). Consumption of a high-calorie, high-fat meal increased the percentage of co-localization at both 3 and 5-h post prandial compared to pre-meal. No obvious difference in co-localization was observed when cells were treated by acLDL in vitro. More research is needed to determine how to best use this method to study pre-clinical risk of atherosclerosis. Copyright © 2016. Published by Elsevier Inc.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Xiaolin; Li, Qian; Pang, Liewen

Highlights: •Arctigenin enhanced cholesterol efflux in oxLDL-loaded THP-1 macrophages. •The expression of ABCA1, ABCG1 and apoE was upregulated in arctigenin-treated cells. •Arctigenin promoted the expression of PPAR-γ and LXR-α. •Inhibition of PPAR-γ or LXR-α reversed arctigenin-mediated biological effects. •Arctigenin promotes cholesterol efflux via activation of PPAR-γ/LXR-α/ABCA1 pathway. -- Abstract: Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-densitymore » lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α.« less

Formulation, characteristics and antiatherogenic bioactivities of CD36-targeted epigallocatechin gallate (EGCG)-loaded nanoparticles.

PubMed

Zhang, Jia; Nie, Shufang; Martinez-Zaguilan, Raul; Sennoune, Souad R; Wang, Shu

2016-04-01

Intimal macrophages are determinant cells for atherosclerotic lesion formation by releasing inflammatory factors and taking up oxidized low-density lipoprotein (oxLDL) via scavenger receptors, primarily the CD36 receptor. (-)-Epigallocatechin-3-gallate (EGCG) has a potential to decrease cholesterol accumulation and inflammatory responses in macrophages. We made EGCG-loaded nanoparticles (Enano) using phosphatidylcholine, kolliphor HS15, alpha-tocopherol acetate and EGCG. 1-(Palmitoyl)-2-(5-keto-6-octene-dioyl) phosphatidylcholine (KOdiA-PC), a CD36-targeted ligand found on oxLDL, was incorporated on the surface of Enano to make ligand-Enano (L-Enano). The objectives of this study are to deliver EGCG to macrophages via CD36-targeted L-Enano and to determine its antiatherogenic bioactivities. The optimized nanoparticles obtained in our study were spherical and around 108 nm in diameter, and had about 10% of EGCG loading capacity and 96% of EGCG encapsulation efficiency. Compared to Enano, CD36-targeted L-Enano had significantly higher binding affinity to and uptake by macrophages at the same pattern as oxLDL. CD36-targeted L-Enano dramatically improved EGCG stability, increased macrophage EGCG content, delivered EGCG to macrophage cytosol and avoided lysosomes. L-Enano significantly decreased macrophage mRNA levels and protein secretion of monocyte chemoattractant protein 1, but did not significantly change macrophage cholesterol content. The innovative CD36-targeted nanoparticles may facilitate targeted delivery of diagnostic, preventive and therapeutic compounds to intimal macrophages for the diagnosis, prevention and treatment of atherosclerosis with enhanced efficacy and decreased side effects. Copyright © 2015 Elsevier Inc. All rights reserved.

Ezetimibe increases intestinal expression of the LDL receptor gene in dyslipidaemic men with insulin resistance.

PubMed

Drouin-Chartier, Jean-Philippe; Tremblay, André J; Lemelin, Valéry; Lépine, Marie-Claude; Lamarche, Benoît; Couture, Patrick

2016-12-01

To gain further insight into intestinal cholesterol homeostasis in dyslipidaemic men with insulin resistance (IR) by examining the impact of treatment with ezetimibe on the expression of key genes involved in cholesterol synthesis and LDL receptor (R)-mediated uptake of lipoproteins. A total of 25 men with dyslipidaemia and IR were recruited to participate in this double-blind, randomized, crossover, placebo-controlled trial. Participants received 10 mg/day ezetimibe or placebo for periods of 12 weeks each. Intestinal gene expression was measured by quantitative PCR in duodenal biopsy samples collected by gastroduodenoscopy at the end of each treatment. A total of 20 participants completed the protocol. Treatment with ezetimibe significantly increased intestinal LDLR (+16.2%; P = .01), 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoAR; +14.0%; P = .04) and acetyl-Coenzyme A acetyltransferase 2 (ACAT-2) mRNA expression (+12.5%; P = .03). Changes in sterol regulatory element-binding transcription factor 2 (SREBP-2) expression were significantly correlated with changes in HMG-CoAR (r = 0.55; P < .05), ACAT-2 (r = 0.69; P < .001) and proprotein convertase substilisin/kexin type 9 (PCSK9) expression (r = 0.45; P < .05). These results show that inhibition of intestinal cholesterol absorption by ezetimibe increases expression of the LDLR gene, supporting the concept that increased LDL clearance with ezetimibe treatment occurs not only in the liver but also in the small intestine. © 2016 John Wiley & Sons Ltd.

Discordant response of low-density lipoprotein cholesterol and lipoprotein(a) levels to monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9.

PubMed

Edmiston, Jonathan B; Brooks, Nathan; Tavori, Hagai; Minnier, Jessica; Duell, Bart; Purnell, Jonathan Q; Kaufman, Tina; Wojcik, Cezary; Voros, Szilard; Fazio, Sergio; Shapiro, Michael D

Clinical trials testing proprotein convertase subtilisin/kexin type 9 inhibitors (PCSK9i) have demonstrated an unanticipated but significant lipoprotein (a) (Lp(a))-lowering effect, on the order of 25% to 30%. Although the 50% to 60% reduction in low-density lipoprotein (LDL)-cholesterol (LDL-C) achieved by PCSK9i is mediated through its effect on LDL receptor (LDLR) preservation, the mechanism for Lp(a) lowering is unknown. We sought to characterize the degree of concordance between LDL-C and Lp(a) lowering because of PCSK9i in a standard of care patient cohort. Participants were selected from our Center for Preventive Cardiology, an outpatient referral center in a tertiary academic medical center. Subjects were included in this study if they had (1) at least 1 measurement of LDL-C and Lp(a) before and after initiation of the PCSK9i; (2) baseline Lp(a) > 10 mg/dL; and (3) continued adherence to PCSK9i therapy. They were excluded if (1) they were undergoing LDL apheresis; (2) pre- or post-PCSK9i LDL-C or Lp(a) laboratory values were censored; or (3) subjects discontinued other lipid-modifying therapies. In total, 103 subjects were identified as taking a PCSK9i and 26 met all inclusion and exclusion criteria. Concordant response to therapy was defined as an LDL-C reduction >35% and an Lp(a) reduction >10%. The cohort consisted of 26 subjects (15 females, 11 males, mean age 63 ± 12 years). Baseline mean LDL-C and median Lp(a) levels were 167.4 ± 72 mg/dL and 81 mg/dL (interquartile range 38-136 mg/dL), respectively. The average percent reductions in LDL-C and Lp(a) were 52.8% (47.0-58.6) and 20.2% (12.2-28.1). The correlation between %LDL and %Lp(a) reduction was moderate, with a Spearman's correlation of 0.56 (P < .01). All subjects except for 1 had a protocol-appropriate LDL-C response to therapy. However, only 16 of the 26 (62%; 95% confidence interval 41%-82%) subjects had a protocol-concordant Lp(a) response. Although some subjects demonstrated negligible Lp(a) reduction associated with PCSK9i, there were some whose Lp(a) decreased as much as 60%. In this standard-of-care setting, we demonstrate moderate correlation but large discordance (∼40%) in these 2 lipid fractions in response to PCSK9i. The results suggest that pathways beyond the LDLR are responsible for Lp(a) lowering and indicate that PCSK9i have the potential to significantly lower Lp(a) in select patients, although confirmation in larger multicenter studies is required. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

Lipoprotein(a) levels in familial hipercholesterolaemia: an important predictor for cardiovascular disease independent of the type of LDL-receptor mutation

USDA-ARS?s Scientific Manuscript database

To determine the relationship between lipoprotein(a) [Lp(a)] and cardiovascular disease (CVD) in a large cohort of heterozygous familial hypercholesterolemia (FH) patients. Lipoprotein(a) is considered a cardiovascular risk factor. Nevertheless, the role of Lp(a) as a predictor of CVD in FH has been...

Inhibiting LDL glycation ameliorates increased cholesteryl ester synthesis in macrophages and hypercholesterolemia and aortic lipid peroxidation in streptozotocin diabetic rats

PubMed Central

Cohen, Margo P.; Shea, Elizabeth A.; Wu, Van-Yu

2009-01-01

Increased nonenzymatic glycation of apoB-containing lipoproteins impairs uptake and metabolism by the high affinity low density lipoprotein (LDL) receptor, and is one of the post-secretory modifications contributory to accelerated atherosclerosis in diabetes. The present study evaluated in vitro and in vivo effects of 2,2-chlorophenylaminophenylacetate (CAP22) to probe the influence of glycated lipoprotein on cholesterol homeostasis. This compound prevented the increased formation of glycated products in LDL incubated with 200 mM glucose and the increased cholesteryl ester synthesis in THP-1 macrophages induced by apoB-containing lipoproteins preincubated with high glucose concentration. The elevated circulating concentrations of glycated lipoprotein and cholesterol and higher vascular levels of lipid peroxidation products observed in streptozotocin diabetic rats compared to nondiabetic controls were significantly reduced in diabetic animals treated for six months with test compound. These results are the first to demonstrate that inhibiting nonenzymatic glycation of apoB-containing lipoproteins ameliorates abnormalities contributory to hypercholesterolemia and atherogenic risk in diabetes. PMID:19922964

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tong, Meng, E-mail: tong.59@osu.edu; Han, Byungdo B.; Holpuch, Andrew S.

The presence of the EMT (epithelial-mesenchymal transition), EndMT (endothelial-mesenchymal transition) and VM (vasculogenic mimicry) demonstrates the multidirectional extent of phenotypic plasticity in cancers. Previous findings demonstrating the crosstalk between head and neck squamous cell carcinoma (HNSCC) and vascular endothelial growth factor (VEGF) imply that HNSCC cells share some functional commonalities with endothelial cells. Our current results reveal that cultured HNSCC cells not only possess endothelial-specific markers, but also display endotheliod functional features including low density lipoprotein uptake, formation of tube-like structures on Matrigel and growth state responsiveness to VEGF and endostatin. HNSCC cell subpopulations are also highly responsive to transformingmore » growth factor-β1 and express its auxiliary receptor, endoglin. Furthermore, the endotheliod characteristics observed in vitro recapitulate phenotypic features observed in human HNSCC tumors. Conversely, cultured normal human oral keratinocytes and intact or ulcerated human oral epithelia do not express comparable endotheliod characteristics, which imply that assumption of endotheliod features is restricted to transformed keratinocytes. In addition, this phenotypic state reciprocity facilitates HNSCC progression by increasing production of factors that are concurrently pro-proliferative and pro-angiogenic, conserving cell energy stores by LDL internalization and enhancing cell mobility. Finally, recognition of this endotheliod phenotypic transition provides a solid rationale to evaluate the antitumorigenic potential of therapeutic agents formerly regarded as exclusively angiostatic in scope. - Highlights: ► HNSCC tumor cells express endothelial specific markers VE-cadherin, CD31 and vimentin. ► Similarly, cultured HNSCC cells retain expression of these markers. ► HNSCC cells demonstrate functional endotheliod characteristics i.e. AcLDL uptake. ► HNSCC cell subpopulations are highly responsive to TGF- β1, VEGF and endostatin. ► TGF-β1 facilitates cadherin switching and augments invasiveness of HNSCC subpopulations.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahman, Shaikh M., E-mail: rmizanoor@hotmail.com; Choudhury, Mahua; Janssen, Rachel C.

Highlights: Black-Right-Pointing-Pointer LXR agonist activation increases liver TG accumulation by increasing lipogenesis. Black-Right-Pointing-Pointer C/EBP{beta}{sup -/-} mouse prevents LXR activation-mediated induction of hepatic lipogenesis. Black-Right-Pointing-Pointer C/EBP{beta} deletion increases mitochondrial transport chain function. Black-Right-Pointing-Pointer Beneficial effects of LXR activation on liver cholesterol metabolism did not change. Black-Right-Pointing-Pointer C/EBP{beta} inhibition might have important therapeutic potential. -- Abstract: Drugs designed specifically to activate liver X receptors (LXRs) have beneficial effects on lowering cholesterol metabolism and inflammation but unfortunately lead to severe hepatic steatosis. The transcription factor CCAAT/enhancer binding protein beta (C/EBP{beta}) is an important regulator of liver gene expression but little is known aboutmore » its involvement in LXR-based steatosis and cholesterol metabolism. The present study investigated the role of C/EBP{beta} expression in LXR agonist (T0901317)-mediated alteration of hepatic triglyceride (TG) and lipogenesis in mice. C/EBP{beta} deletion in mice prevented LXR agonist-mediated induction of lipogenic gene expression in liver in conjunction with significant reduction of liver TG accumulation. Surprisingly, C/EBP{beta}{sup -/-} mice showed a major increase in liver mitochondrial electron chain function compared to WT mice. Furthermore, LXR activation in C/EBP{beta}{sup -/-} mice increased the expression of liver ATP-binding cassette transporter ABCG1, a gene implicated in cholesterol efflux and reducing blood levels of total and LDL-cholesterol. Together, these findings establish a central role for C/EBP{beta} in the LXR-mediated steatosis and mitochondrial function, without impairing the influence of LXR activation on lowering LDL and increasing HDL-cholesterol. Inactivation of C/EBP{beta} might therefore be an important therapeutic strategy to prevent LXR activation-mediated adverse effects on liver TG metabolism without disrupting its beneficial effects on cholesterol metabolism.« less

The Effect of a Three-Week Adaptation to a Low Carbohydrate/High Fat Diet on Metabolism and Cognitive Performance

DTIC Science & Technology

1990-04-11

triglycerides , insulin, glucagon, cholesterol (total, high density lipoprotein ( HDL ), low density lipoprotein (LDL)I, cortisol, thyroid hormone...thyroid function, triglycerides , total cholesterol , high density lipoprotein cholesterol ( HDL ), low density lipoprotein cholesterol (LDL), ketone... density lipoprotein ( HDL ) fraction of cholesterol was

Dual Ca2+ requirement for optimal lipid peroxidation of low density lipoprotein by activated human monocytes.

PubMed

Li, Q; Tallant, A; Cathcart, M K

1993-04-01

The oxidative modification of LDL seems a key event in atherogenesis and may participate in inflammatory tissue injury. Our previous studies suggested that the process of LDL oxidation by activated human monocytes/macrophages required O2- and activity of intracellular lipoxygenase. Herein, we studied the mechanisms involved in this oxidative modification of LDL. In this study, we used the human monocytoid cell line U937 to examine the role of Ca2+ in U937 cell-mediated lipid peroxidation of LDL. U937 cells were activated by opsonized zymosan. Removal of Ca2+ from cell culture medium by EGTA inhibited U937 cell-mediated peroxidation of LDL lipids. Therefore, Ca2+ influx and mobilization were examined for their influence on U937 cell-mediated LDL lipid peroxidation. Ca2+ channel blockers nifedipine and verapamil blocked both Ca2+ influx and LDL lipid peroxidation by activated U937 cells. The inhibitory effects of nifedipine and verapamil were dose dependent. TMB-8 and ryanodine, agents known to prevent Ca2+ release from intracellular stores, also caused a dose-dependent inhibition of LDL lipid peroxidation by activated U937 cells while exhibiting no effect on Ca2+ influx. Thus, both Ca2+ influx through functional calcium channels and Ca2+ mobilization from intracellular stores participate in the oxidative modification of LDL by activated U937 cells. 45Ca2+ uptake experiments revealed profound Ca2+ influx during the early stages of U937 cell activation, however, the Ca2+ ionophore 4-bromo A23187 was unable to induce activation of U937 cells and peroxidation of LDL lipids. Release of intracellular Ca2+ by thapsigargin only caused a suboptimal peroxidation of LDL lipids. Our results indicate that although increases in intracellular Ca2+ levels provided by both influx and intracellular Ca2+ mobilization are required, other intracellular signals may be involved for optimal peroxidation of LDL lipids by activated human monocytes.

Current and future pharmacologic options for the management of patients unable to achieve low-density lipoprotein-cholesterol goals with statins.

PubMed

El Harchaoui, Karim; Akdim, Fatima; Stroes, Erik S G; Trip, Mieke D; Kastelein, John J P

2008-01-01

Low-density lipoprotein-cholesterol (LDL-C) lowering is the mainstay of the current treatment guidelines in the management of cardiovascular risk. HMG-CoA reductase inhibitors (statins) are currently the most effective LDL-C-lowering drugs. However, a substantial number of patients do not reach treatment targets with statins. Therefore, an unmet medical need exists for lipid-lowering drugs with novel mechanisms of action to reach the recommended cholesterol target levels, either by monotherapy or combination therapy. Upregulation of the LDL receptor with squalene synthase inhibitors has shown promising results in animal studies but the clinical development of the lead compound lapaquistat (TAK-475) has recently been discontinued. Ezetimibe combined with statins allowed significantly more patients to reach their LDL-C targets. Other inhibitors of intestinal cholesterol absorption such as disodium ascorbyl phytostanol phosphate (FM-VP4) and bile acid transport inhibitors have shown positive results in early development trials, whereas the prospect of acyl coenzyme A: cholesterol acyltransferase inhibition in cardiovascular prevention is dire. Selective inhibition of messenger RNA (mRNA) by antisense oligonucleotides is a new approach to modify cholesterol levels. The inhibition of apolipoprotein B mRNA is in advanced development and mipomersen sodium (ISIS 301012) has shown striking results in phase II studies both as monotherapy as well as in combination with statins.

High hydrostatic pressure specifically affects molecular dynamics and shape of low-density lipoprotein particles

PubMed Central

Golub, M.; Lehofer, B.; Martinez, N.; Ollivier, J.; Kohlbrecher, J.; Prassl, R.; Peters, J.

2017-01-01

Lipid composition of human low-density lipoprotein (LDL) and its physicochemical characteristics are relevant for proper functioning of lipid transport in the blood circulation. To explore dynamical and structural features of LDL particles with either a normal or a triglyceride-rich lipid composition we combined coherent and incoherent neutron scattering methods. The investigations were carried out under high hydrostatic pressure (HHP), which is a versatile tool to study the physicochemical behavior of biomolecules in solution at a molecular level. Within both neutron techniques we applied HHP to probe the shape and degree of freedom of the possible motions (within the time windows of 15 and 100 ps) and consequently the flexibility of LDL particles. We found that HHP does not change the types of motion in LDL, but influences the portion of motions participating. Contrary to our assumption that lipoprotein particles, like membranes, are highly sensitive to pressure we determined that LDL copes surprisingly well with high pressure conditions, although the lipid composition, particularly the triglyceride content of the particles, impacts the molecular dynamics and shape arrangement of LDL under pressure. PMID:28382948

High hydrostatic pressure specifically affects molecular dynamics and shape of low-density lipoprotein particles

NASA Astrophysics Data System (ADS)

Golub, M.; Lehofer, B.; Martinez, N.; Ollivier, J.; Kohlbrecher, J.; Prassl, R.; Peters, J.

2017-04-01

Lipid composition of human low-density lipoprotein (LDL) and its physicochemical characteristics are relevant for proper functioning of lipid transport in the blood circulation. To explore dynamical and structural features of LDL particles with either a normal or a triglyceride-rich lipid composition we combined coherent and incoherent neutron scattering methods. The investigations were carried out under high hydrostatic pressure (HHP), which is a versatile tool to study the physicochemical behavior of biomolecules in solution at a molecular level. Within both neutron techniques we applied HHP to probe the shape and degree of freedom of the possible motions (within the time windows of 15 and 100 ps) and consequently the flexibility of LDL particles. We found that HHP does not change the types of motion in LDL, but influences the portion of motions participating. Contrary to our assumption that lipoprotein particles, like membranes, are highly sensitive to pressure we determined that LDL copes surprisingly well with high pressure conditions, although the lipid composition, particularly the triglyceride content of the particles, impacts the molecular dynamics and shape arrangement of LDL under pressure.

HEMOGLOBIN A1C, BLOOD PRESSURE, AND LDL-CHOLESTEROL CONTROL AMONG HISPANIC/LATINO ADULTS WITH DIABETES: RESULTS FROM THE HISPANIC COMMUNITY HEALTH STUDY/STUDY OF LATINOS (HCHS/SOL)

PubMed Central

Casagrande, Sarah Stark; Aviles-Santa, Larissa; Corsino, Leonor; Daviglus, Martha L.; Gallo, Linda C.; Espinoza Giacinto, Rebeca A.; Llabre, Maria M.; Reina, Samantha A.; Savage, Peter J.; Schneiderman, Neil; Talavera, Gregory A.; Cowie, Catherine C.

2018-01-01

Objective To determine the prevalence of Hispanic/Latino adults with diabetes who meet target hemoglobin A1c, blood pressure (BP), and low-density-lipoprotein cholesterol (LDL-C) recommendations, and angiotensin-converting enzyme (ACE) inhibitors/angiotensin receptor blocker (ARB) and statin medication use by heritage and sociodemographic and diabetes-related characteristics. Methods Data were cross-sectional, collected between 2008 and 2011, and included adults age 18 to 74 years who reported a physician diagnosis of diabetes in the Hispanic Community Health Study/Study of Latinos (N = 2,148). Chi-square tests compared the prevalence of hemoglobin A1c, BP, and LDL-C targets and ACE/ARB and statin use across participant characteristics. Predictive margins regression was used to determine the prevalence adjusted for sociodemographic characteristics. Results The overall prevalence of A1c <7.0% (53 mmol/mol), BP <130/80 mm Hg, and LDL-C <100 mg/dL was 43.0, 48.7, and 36.6%, respectively, with 8.4% meeting all three targets. Younger adults aged 18 to 39 years with diabetes were less likely to have A1c <7.0% (53 mmol/mol) or LDL-C <100 mg/dL compared to those aged 65 to 74 years; younger adults were more likely to have BP <130/80 mm Hg (P<.05 for all). Individuals of Mexican heritage were significantly less likely to have A1c <7.0% (53 mmol/mol) compared to those with Cuban heritage, but they were more likely to have BP <130/80 mm Hg compared to those with Dominican, Cuban, or Puerto Rican heritage (P<.05 for all); there was no difference in LDL-C by heritage. Overall, 38.2% of adults with diabetes were taking a statin, and 50.5% were taking ACE/ARB medications. Conclusion Hemoglobin A1c, BP, and LDL-C control are suboptimal among Hispanic/Latinos with diabetes living in the U.S. With 8.4% meeting all three recommendations, substantial opportunity exists to improve diabetes control in this population. PMID:28816530

Evaluation of the Potential Role of Alirocumab in the Management of Hypercholesterolemia in Patients with High-Risk Cardiovascular Disease.

PubMed

Okere, Arinze Nkemdirim; Serra, Courtney

2015-08-01

A high level of low-density lipoprotein cholesterol (LDL-C) has proved to have a positive correlation with mortality from cardiovascular disease, and it is the key modifiable risk factor for cardiovascular disease. Lowering levels of LDL-C with statins reduces both vascular morbidity and mortality; however, myalgias occur in 10% to 15% of patients, and many patients managed with statins achieve suboptimal levels of LDL-C. The injectable drug alirocumab-the first of a new class of drugs called proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors-is a monoclonal antibody to the PCSK9 gene, which regulates LDL receptor expression and circulating levels of LDL-C. In this review, we evaluated the efficacy and safety of alirocumab and its potential role in the management of patients with high-risk cardiovascular disease. Data were gathered from articles indexed in the PubMed database (2006-April 2015). All English-language, prospective, randomized, double-blinded trials evaluating the efficacy of alirocumab, as a monotherapy or in combination with statins, for treatment of hypercholesterolemia were identified. Five clinical trials were evaluated, and the results from these studies revealed that the use of alirocumab, both as monotherapy or in combination with statins, significantly reduced LDL-C levels. Patients treated with alirocumab, with or without statins, were more likely to achieve LDL-C goals of less than 100 or 70 mg/dl compared with placebo. Despite its ability to lower LDL-C level, one study did not show any antiinflammatory activity (i.e., reduced C-reactive protein level) among patients who received alirocumab; however, more clinical trials will be needed to further assess this effect. Alirocumab also appears to cause regression of plaque. The most commonly reported adverse effect was mild injection-site reaction. With increased odds of statin discontinuation among patients taking high-intensity statins, alirocumab will contribute to atherosclerotic cardiovascular disease risk reduction. However, morbidity and mortality data, as well as long-term safety data, are pending. Therefore, we propose that alirocumab will better serve as an adjuvant therapy for the management of hypercholesterolemia in patients at high risk for cardiovascular events. As with all new promising injectable drugs, cost will also be a key consideration. © 2015 Pharmacotherapy Publications, Inc.

Mipomersen, an apolipoprotein B synthesis inhibitor, for lowering of LDL cholesterol concentrations in patients with homozygous familial hypercholesterolaemia: a randomised, double-blind, placebo-controlled trial.

PubMed

Raal, Frederick J; Santos, Raul D; Blom, Dirk J; Marais, A David; Charng, Min-Ji; Cromwell, William C; Lachmann, Robin H; Gaudet, Daniel; Tan, Ju L; Chasan-Taber, Scott; Tribble, Diane L; Flaim, Joann D; Crooke, Stanley T

2010-03-20

Homozygous familial hypercholesterolaemia is a rare genetic disorder in which both LDL-receptor alleles are defective, resulting in very high concentrations of LDL cholesterol in plasma and premature coronary artery disease. This study investigated whether an antisense inhibitor of apolipoprotein B synthesis, mipomersen, is effective and safe as an adjunctive agent to lower LDL cholesterol concentrations in patients with this disease. This randomised, double-blind, placebo-controlled, phase 3 study was undertaken in nine lipid clinics in seven countries. Patients aged 12 years and older with clinical diagnosis or genetic confirmation of homozygous familial hypercholesterolaemia, who were already receiving the maximum tolerated dose of a lipid-lowering drug, were randomly assigned to mipomersen 200 mg subcutaneously every week or placebo for 26 weeks. Randomisation was computer generated and stratified by weight (<50 kg vs >/=50 kg) in a centralised blocked randomisation, implemented with a computerised interactive voice response system. All clinical, medical, and pharmacy personnel, and patients were masked to treatment allocation. The primary endpoint was percentage change in LDL cholesterol concentration from baseline. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00607373. 34 patients were assigned to mipomersen and 17 to placebo; data for all patients were analysed. 45 patients completed the 26-week treatment period (28 mipomersen, 17 placebo). Mean concentrations of LDL cholesterol at baseline were 11.4 mmol/L (SD 3.6) in the mipomersen group and 10.4 mmol/L (3.7) in the placebo group. The mean percentage change in LDL cholesterol concentration was significantly greater with mipomersen (-24.7%, 95% CI -31.6 to -17.7) than with placebo (-3.3%, -12.1 to 5.5; p=0.0003). The most common adverse events were injection-site reactions (26 [76%] patients in mipomersen group vs four [24%] in placebo group). Four (12%) patients in the mipomersen group but none in the placebo group had increases in concentrations of alanine aminotransferase of three times or more the upper limit of normal. Inhibition of apolipoprotein B synthesis by mipomersen represents a novel, effective therapy to reduce LDL cholesterol concentrations in patients with homozygous familial hypercholesterolaemia who are already receiving lipid-lowering drugs, including high-dose statins. ISIS Pharmaceuticals and Genzyme Corporation. Copyright 2010 Elsevier Ltd. All rights reserved.

Difficulties in reaching therapeutic goals for hypertension and dysplipidaemia in patients with type 2 diabetes in general practice.

PubMed

Knudsen, Søren Tang; Mosbech, Thomas Hammershaimb; Hansen, Birtha; Kønig, Else; Johnsen, Peter Christian; Kamper, Anne-Lise

2013-12-01

National guidelines recommend strict control of blood pressure (BP) and plasma low-density lipoprotein cholesterol (LDL) in type 2 diabetes (T2DM), aiming at a BP ≤ 130/80 mmHg and an LDL concentration ≤ 2.5 mmol/l. Angiotensin-converting enzyme inhibitors (ACEI) or angiotensin II-receptor blockers (ARB) are recommended as primary antihypertensive therapy (AHT). To which extent these targets are met in Danish primary care is unknown. This study was based on data from 2,057 patients with T2DM who were randomly selected from 64 general practitioners (GPs) from different regions of Denmark. Data were collected from the GPs' electronic records. The mean age ± standard deviation was 66.2 ± 11.6 years; 58.7% were male. The mean systolic BP ± standard deviation was 132.6 ± 14.6 mmHg and the mean diastolic BP ± standard deviation was 78.1 ± 9.0 mmHg. 47.7% of the patients met the BP target. 79.5% of the patients were on AHT. 55.1% of the untreated and 46.0% of the treated patients met the BP target. 83.4% of the treated patients received ACEI or ARB. The median LDL was 2.2 (1.7-2.7) mmol/l. 63.7% of the patients met the LDL target. 73.7% of the patients received lipid-lowering therapy. 32.8% of the untreated and 74.4% of the treated patients met the LDL target. AHT including ACEI and ARB and lipid-lowering therapy are widely used in T2DM in Danish primary care, but only half of the patients are at target for BP and two thirds are at target for LDL. Increased use of diuretics may improve BP control. This study was funded by a grant from Boehringer Ingelheim, Denmark. The grant covered costs related to data collection, time spent by the general practitioners and data analysis by the DTU. not relevant.

JNK1 Mediates Lipopolysaccharide-Induced CD14 and SR-AI Expression and Macrophage Foam Cell Formation.

PubMed

An, Dong; Hao, Feng; Hu, Chen; Kong, Wei; Xu, Xuemin; Cui, Mei-Zhen

2017-01-01

Foam cell formation is the key process in the development of atherosclerosis. The uptake of oxidized low-density lipoprotein (oxLDL) converts macrophages into foam cells. We recently reported that lipopolysaccharide (LPS)-induced foam cell formation is regulated by CD14 and scavenger receptor AI (SR-AI). In this study, we employed pharmaceutical and gene knockdown approaches to determine the upstream molecular mediators, which control LPS-induced foam cell formation. Our results demonstrated that the specific c-Jun N-terminal kinase (JNK) pathway inhibitor, SP600125, but neither the specific inhibitor of extracellular signaling-regulated kinase (ERK) kinase MEK1/2, U0126, nor the specific inhibitor of p38 MAPK, SB203580, significantly blocks LPS-induced oxLDL uptake, suggesting that the JNK pathway is the upstream mediator of LPS-induced oxLDL uptake/foam cell formation. To address whether JNK pathway mediates LPS-induced oxLDL uptake is due to JNK pathway-regulated CD14 and SR-AI expression, we assessed whether the pharmaceutical inhibitor of JNK influences LPS-induced expression of CD14 and SR-AI. Our results indicate that JNK pathway mediates LPS-induced CD14 and SR-AI expression. To conclusively address the isoform role of JNK family, we depleted JNK isoforms using the JNK isoform-specific siRNA. Our data showed that the depletion of JNK1, but not JNK2 blocked LPS-induced CD14/SR-AI expression and foam cell formation. Taken together, our results reveal for the first time that JNK1 is the key mediator of LPS-induced CD14 and SR-AI expression in macrophages, leading to LPS-induced oxLDL uptake/foam cell formation. We conclude that the novel JNK1/CD14/SR-AI pathway controls macrophage oxLDL uptake/foam cell formation.

The Sirt1 activator SRT3025 provides atheroprotection in Apoe−/− mice by reducing hepatic Pcsk9 secretion and enhancing Ldlr expression

PubMed Central

Miranda, Melroy X.; van Tits, Lambertus J.; Lohmann, Christine; Arsiwala, Tasneem; Winnik, Stephan; Tailleux, Anne; Stein, Sokrates; Gomes, Ana P.; Suri, Vipin; Ellis, James L.; Lutz, Thomas A.; Hottiger, Michael O.; Sinclair, David A.; Auwerx, Johan; Schoonjans, Kristina; Staels, Bart; Lüscher, Thomas F.; Matter, Christian M.

2015-01-01

Aims The deacetylase sirtuin 1 (Sirt1) exerts beneficial effects on lipid metabolism, but its roles in plasma LDL-cholesterol regulation and atherosclerosis are controversial. Thus, we applied the pharmacological Sirt1 activator SRT3025 in a mouse model of atherosclerosis and in hepatocyte culture. Methods and results Apolipoprotein E-deficient (Apoe−/−) mice were fed a high-cholesterol diet (1.25% w/w) supplemented with SRT3025 (3.18 g kg−1 diet) for 12 weeks. In vitro, the drug activated wild-type Sirt1 protein, but not the activation-resistant Sirt1 mutant; in vivo, it increased deacetylation of hepatic p65 and skeletal muscle Foxo1. SRT3025 treatment decreased plasma levels of LDL-cholesterol and total cholesterol and reduced atherosclerosis. Drug treatment did not change mRNA expression of hepatic LDL receptor (Ldlr) and proprotein convertase subtilisin/kexin type 9 (Pcsk9), but increased their protein expression indicating post-translational effects. Consistent with hepatocyte Ldlr and Pcsk9 accumulation, we found reduced plasma levels of Pcsk9 after pharmacological Sirt1 activation. In vitro administration of SRT3025 to cultured AML12 hepatocytes attenuated Pcsk9 secretion and its binding to Ldlr, thereby reducing Pcsk9-mediated Ldlr degradation and increasing Ldlr expression and LDL uptake. Co-administration of exogenous Pcsk9 with SRT3025 blunted these effects. Sirt1 activation with SRT3025 in Ldlr−/− mice reduced neither plasma Pcsk9, nor LDL-cholesterol levels, nor atherosclerosis. Conclusion We identify reduction in Pcsk9 secretion as a novel effect of Sirt1 activity and uncover Ldlr as a prerequisite for Sirt1-mediated atheroprotection in mice. Pharmacological activation of Sirt1 appears promising to be tested in patients for its effects on plasma Pcsk9, LDL-cholesterol, and atherosclerosis. PMID:24603306

The role of antisense oligonucleotide therapy in patients with familial hypercholesterolemia: risks, benefits, and management recommendations.

PubMed

Agarwala, Anandita; Jones, Peter; Nambi, Vijay

2015-01-01

Antisense oligonucleotide therapy is a promising approach for the treatment of a broad variety of medical conditions. It functions at the cellular level by interfering with RNA function, often leading to degradation of specifically targeted abnormal gene products implicated in the disease process. Mipomersen is a novel antisense oligonucleotide directed at apolipoprotein (apoB)-100, the primary apolipoprotein associated with low-density lipoprotein cholesterol (LDL-C), which has recently been approved for the treatment of familial hypercholesterolemia. A number of clinical studies have demonstrated its efficacy in lowering LDL-C and apoB levels in patients with elevated LDL-C despite maximal medical therapy using conventional lipid-lowering agents. This review outlines the risks and benefits of therapy and provides recommendations on the use of mipomersen.

Diagnostic Yield of Sequencing Familial Hypercholesterolemia Genes in Severe Hypercholesterolemia

PubMed Central

Khera, Amit V.; Won, Hong-Hee; Peloso, Gina M.; Lawson, Kim S.; Bartz, Traci M.; Deng, Xuan; van Leeuwen, Elisabeth M.; Natarajan, Pradeep; Emdin, Connor A.; Bick, Alexander G.; Morrison, Alanna C.; Brody, Jennifer A.; Gupta, Namrata; Nomura, Akihiro; Kessler, Thorsten; Duga, Stefano; Bis, Joshua C.; van Duijn, Cornelia M.; Cupples, L. Adrienne; Psaty, Bruce; Rader, Daniel J.; Danesh, John; Schunkert, Heribert; McPherson, Ruth; Farrall, Martin; Watkins, Hugh; Lander, Eric; Wilson, James G.; Correa, Adolfo; Boerwinkle, Eric; Merlini, Piera Angelica; Ardissino, Diego; Saleheen, Danish; Gabriel, Stacey; Kathiresan, Sekar

2017-01-01

Background About 7% of US adults have severe hypercholesterolemia (untreated LDL cholesterol ≥190 mg/dl). Such high LDL levels may be due to familial hypercholesterolemia (FH), a condition caused by a single mutation in any of three genes. Lifelong elevations in LDL cholesterol in FH mutation carriers may confer CAD risk beyond that captured by a single LDL cholesterol measurement. Objectives Assess the prevalence of a FH mutation among those with severe hypercholesterolemia and determine whether CAD risk varies according to mutation status beyond the observed LDL cholesterol. Methods Three genes causative for FH (LDLR, APOB, PCSK9) were sequenced in 26,025 participants from 7 case-control studies (5,540 CAD cases, 8,577 CAD-free controls) and 5 prospective cohort studies (11,908 participants). FH mutations included loss-of-function variants in LDLR, missense mutations in LDLR predicted to be damaging, and variants linked to FH in ClinVar, a clinical genetics database. Results Among 8,577 CAD-free control participants, 430 had LDL cholesterol ≥190 mg/dl; of these, only eight (1.9%) carried a FH mutation. Similarly, among 11,908 participants from 5 prospective cohorts, 956 had LDL cholesterol ≥190 mg/dl and of these, only 16 (1.7%) carried a FH mutation. Within any stratum of observed LDL cholesterol, risk of CAD was higher among FH mutation carriers when compared with non-carriers. When compared to a reference group with LDL cholesterol <130 mg/dl and no mutation, participants with LDL cholesterol ≥190 mg/dl and no FH mutation had six-fold higher risk for CAD (OR 6.0; 95%CI 5.2–6.9) whereas those with LDL cholesterol ≥190 mg/dl as well as a FH mutation demonstrated twenty-two fold increased risk (OR 22.3; 95%CI 10.7–53.2). Conclusions Among individuals with LDL cholesterol ≥190 mg/dl, gene sequencing identified a FH mutation in <2%. However, for any given observed LDL cholesterol, FH mutation carriers are at substantially increased risk for CAD. PMID:27050191

Nonlinear Associations between Plasma Cholesterol Levels and Neuropsychological Function

PubMed Central

Wendell, Carrington R.; Zonderman, Alan B.; Katzel, Leslie I.; Rosenberger, William F.; Plamadeala, Victoria V.; Hosey, Megan M.; Waldstein, Shari R.

2016-01-01

Objective Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery. Method Participants were 190 older adults (53% men, ages 54–83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed/dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as <70 vs. 70+) as an effect modifier. Results A significant quadratic effect of total cholesterol2 × age was identified for Logical Memory II (b=−.0013, p=.039), such that the 70+ group performed best at high and low levels of total cholesterol than at mid-range total cholesterol (U-shaped), and the <70 group performed worse at high and low levels of total cholesterol than at mid-range total cholesterol (inverted U-shape). Similarly, significant U- and J-shaped effects of LDL cholesterol2 × age were identified for Visual Reproduction II (b=−.0020, p=.026) and log of Trails B (b=.0001, p=.044). Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant. Conclusions Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. PMID:27280580

Rationale and study design of a clinical trial to assess the effects of LDL apheresis on proteinuria in diabetic patients with severe proteinuria and dyslipidemia.

PubMed

Wada, Takashi; Muso, Eri; Maruyama, Shoichi; Hara, Akinori; Furuichi, Kengo; Yoshimura, Kenichi; Miyazaki, Mariko; Sato, Eiichi; Abe, Masanori; Shibagaki, Yugo; Narita, Ichiei; Yokoyama, Hitoshi; Mori, Noriko; Yuzawa, Yukio; Matsubara, Takeshi; Tsukamoto, Tatsuo; Wada, Jun; Ito, Takafumi; Masutani, Kosuke; Tsuruya, Kazuhiko; Fujimoto, Shoichi; Tsuda, Akihiro; Suzuki, Hitoshi; Kasuno, Kenji; Terada, Yoshio; Nakata, Takeshi; Iino, Noriaki; Kobayashi, Shuzo

2018-06-01

Diabetic nephropathy is a leading cause of end-stage kidney disease in the world. Although various types of treatment for diabetes, hypertension and dyslipidemia have improved prognosis and quality of life in patients with diabetic nephropathy, there still exist some diabetic patients with severe proteinuria showing poor prognosis. This clinical trial, LICENSE, aims to confirm the impact of LDL apheresis on proteinuria exhibiting hyporesponsiveness to treatment. This ongoing trial is a multicenter, prospective study of diabetic patients with severe proteinuria. The objective is to examine the impact of LDL apheresis on proteinuria in patients with diabetic nephropathy. The other subject is to investigate safety of LDL apheresis in these patients. The subjects consist of diabetic patients with serum creatinine (Cr) levels below 2 mg/dL who present severe proteinuria above 3 g/g Cr or 3 g/day and LDL cholesterol above 120 mg/dL. The target number of registered patients will be 35 patients. Urinary protein excretion and renal function will be observed for 24 weeks after the treatment of LDL apheresis. This study will determine the effectiveness and safety of LDL apheresis for diabetic nephropathy patients with severe proteinuria and dyslipidemia.

Oxidized LDL activates blood platelets through CD36/NOX2–mediated inhibition of the cGMP/protein kinase G signaling cascade

PubMed Central

Magwenzi, Simbarashe; Woodward, Casey; Wraith, Katie S.; Aburima, Ahmed; Raslan, Zaher; Jones, Huw; McNeil, Catriona; Wheatcroft, Stephen; Yuldasheva, Nadira; Febbriao, Maria; Kearney, Mark

2015-01-01

Oxidized low-density lipoprotein (oxLDL) promotes unregulated platelet activation in dyslipidemic disorders. Although oxLDL stimulates activatory signaling, it is unclear how these events drive accelerated thrombosis. Here, we describe a mechanism for oxLDL-mediated platelet hyperactivity that requires generation of reactive oxygen species (ROS). Under arterial flow, oxLDL triggered sustained generation of platelet intracellular ROS, which was blocked by CD36 inhibitors, mimicked by CD36-specific oxidized phospholipids, and ablated in CD36−/− murine platelets. oxLDL-induced ROS generation was blocked by the reduced NAD phosphate oxidase 2 (NOX2) inhibitor, gp91ds-tat, and absent in NOX2−/− mice. The synthesis of ROS by oxLDL/CD36 required Src-family kinases and protein kinase C (PKC)-dependent phosphorylation and activation of NOX2. In functional assays, oxLDL abolished guanosine 3′,5′-cyclic monophosphate (cGMP)-mediated signaling and inhibited platelet aggregation and arrest under flow. This was prevented by either pharmacologic inhibition of NOX2 in human platelets or genetic ablation of NOX2 in murine platelets. Platelets from hyperlipidemic mice were also found to have a diminished sensitivity to cGMP when tested ex vivo, a phenotype that was corrected by infusion of gp91ds-tat into the mice. This study demonstrates that oxLDL and hyperlipidemia stimulate the generation of NOX2-derived ROS through a CD36-PKC pathway and may promote platelet hyperactivity through modulation of cGMP signaling. PMID:25710879

ATP-binding cassette transporter 1 participates in LDL oxidation by artery wall cells.

PubMed

Reddy, Srinivasa T; Hama, Susan; Ng, Carey; Grijalva, Victor; Navab, Mohamad; Fogelman, Alan M

2002-11-01

We have previously reported that products of the lipoxygenase pathway, hydroperoxyoctadecadienoic acid and hydroperoxyeicosatetraenoic acid, as well as cholesterol linoleate hydroperoxides, collectively termed seeding molecules, are removed by apolipoprotein A-I (apoA-I) from the artery wall cells and render low density lipoprotein (LDL) resistant to oxidation by human artery wall cells. The mechanisms by which oxidized lipids are transported and/or transferred to lipoproteins and the pathways by which apoA-I facilitates their removal remain unclear. ATP-binding cassette transporter 1 (ABCA1) is known to facilitate the release of cellular phospholipids and cholesterol from the plasma membrane to apoA-I and high density lipoprotein. Therefore, we evaluated whether ABCA1 participates in LDL oxidation. In this report, we show that (1) chemical inhibitors of ABCA1 function, glyburide and DIDS, block artery wall cell-mediated oxidative modification of LDL, (2) inhibition of ABCA1 with the use of antisense (but not sense) oligonucleotides prevents LDL-induced lipid hydroperoxide formation and LDL-induced monocyte chemotactic activity by the artery wall cells, and (3) oxysterols that induce ABCA1 expression, such as 22(R)hydroxycholesterol, enhance cell-mediated LDL oxidation. Furthermore, we also show that 22(R)hydroxycholesterol induces the production of reactive oxygen species in the artery wall cells, which can be removed by incubating the artery wall cells with apoA-I. Our data suggest that ABCA1 plays an important role in artery wall cell-mediated modification/oxidation of LDL by modulating the release of reactive oxygen species from artery wall cells that are necessary for LDL oxidation.

Population differences in allele frequencies at the OLR1 locus may suggest geographic disparities in cardiovascular risk events.

PubMed

Predazzi, Irene M; Martínez-Labarga, Cristina; Vecchione, Lucia; Mango, Ruggiero; Ciccacci, Cinzia; Amati, Francesca; Ottoni, Claudio; Crawford, Michael H; Rickards, Olga; Romeo, Francesco; Novelli, Giuseppe

2010-04-01

Several studies have demonstrated a link between cardiovascular disease (CVD) susceptibility and the genetic background of populations. Endothelial activation and dysfunction induced by oxidized low-density lipoprotein (ox-LDL) is one of the key steps in the initiation of atherosclerosis. The oxidized low density lipoprotein (lectin-like) receptor 1 (OLR1) gene is the main receptor of ox-LDL. We have previously characterized two polymorphisms (rs3736235 and rs11053646) associated with the risk for coronary artery disease (CAD) and acute myocardial infarction (AMI). Given their clinical significance, it is of interest to know the distribution of these variants in populations from different continents. A total of 1229 individuals from 17 different African, Asian and European populations was genotyped for the two considered markers. The high frequencies of ancestral alleles in South-Saharan populations is concordant with the African origin of our species. The results highlight that African populations are closer to Asians, and clearly separated from the Europeans. The results confirm significant genetic structuring among populations and suggest a possible basis for varying susceptibility to CVD among groups correlated with the geographical location of populations linked with the migrations out of Africa, or with different lifestyle.

Low-density lipoprotein peptide-combined DNA nanocomplex as an efficient anticancer drug delivery vehicle.

PubMed

Zhang, Nan; Tao, Jun; Hua, Haiying; Sun, Pengchao; Zhao, Yongxing

2015-08-01

DNA is a type of potential biomaterials for drug delivery due to its nanoscale geometry, loading capacity of therapeutics, biocompatibility, and biodegradability. Unfortunately, DNA is easily degraded by DNases in the body circulation and has low intracellular uptake. In the present study, we selected three cationic polymers polyethylenimine (PEI), hexadecyl trimethyl ammonium bromide (CTAB), and low-density lipoprotein (LDL) receptor targeted peptide (RLT), to modify DNA and improve the issues. A potent anti-tumor anthracycline-doxorubicin (DOX) was intercalated into DNA non-covalently and the DOX/DNA was then combined with PEI, CTAB, and RLT, respectively. Compact nanocomplexes were formed by electrostatic interaction and could potentially protect DNA from DNases. More importantly, RLT had the potential to enhance intracellular uptake by LDL receptor mediated endocytosis. In a series of in vitro experiments, RLT complexed DNA enhanced intracellular delivery of DOX, increased tumor cell death and intracellular ROS production, and reduced intracellular elimination of DOX. All results suggested that the easily prepared and targeted RLT/DNA nanocomplexes had great potential to be developed into a formulation for doxorubicin with enhanced anti-tumor activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Macrophagic CD146 promotes foam cell formation and retention during atherosclerosis

PubMed Central

Luo, Yongting; Duan, Hongxia; Qian, Yining; Feng, Liqun; Wu, Zhenzhen; Wang, Fei; Feng, Jing; Yang, Dongling; Qin, Zhihai; Yan, Xiyun

2017-01-01

The persistence of cholesterol-engorged macrophages (foam cells) in the artery wall fuels the development of atherosclerosis. However, the mechanism that regulates the formation of macrophage foam cells and impedes their emigration out of inflamed plaques is still elusive. Here, we report that adhesion receptor CD146 controls the formation of macrophage foam cells and their retention within the plaque during atherosclerosis exacerbation. CD146 is expressed on the macrophages in human and mouse atheroma and can be upregulated by oxidized low-density lipoprotein (oxLDL). CD146 triggers macrophage activation by driving the internalization of scavenger receptor CD36 during lipid uptake. In response to oxLDL, macrophages show reduced migratory capacity toward chemokines CCL19 and CCL21; this capacity can be restored by blocking CD146. Genetic deletion of macrophagic CD146 or targeting of CD146 with an antibody result in much less complex plaques in high-fat diet-fed ApoE−/− mice by causing lipid-loaded macrophages to leave plaques. Collectively, our findings identify CD146 as a novel retention signal that traps macrophages within the artery wall, and a promising therapeutic target in atherosclerosis treatment. PMID:28084332

Rhynchophylla total alkaloid rescues autophagy, decreases oxidative stress and improves endothelial vasodilation in spontaneous hypertensive rats.

PubMed

Li, Chao; Jiang, Feng; Li, Yun-Lun; Jiang, Yue-Hua; Yang, Wen-Qing; Sheng, Jie; Xu, Wen-Juan; Zhu, Qing-Jun

2018-03-01

Autophagy plays an important role in alleviating oxidative stress and stabilizing atherosclerotic plaques. However, the potential role of autophagy in endothelial vasodilation function has rarely been studied. This study aimed to investigate whether rhynchophylla total alkaloid (RTA) has a positive role in enhancing autophagy through decreasing oxidative stress, and improving endothelial vasodilation. In oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs), RTA (200 mg/L) significantly suppressed ox-LDL-induced oxidative stress through rescuing autophagy, and decreased cell apoptosis. In spontaneous hypertensive rats (SHR), administration of RTA (50 mg·kg -1 ·d -1 , ip, for 6 weeks) improved endothelin-dependent vasodilation of thoracic aorta rings. Furthermore, RTA administration significantly increased the antioxidant capacity and alleviated oxidative stress through enhancing autophagy in SHR. In ox-LDL-treated HUVECs, we found that the promotion of autophagy by RTA resulted in activation of the AMP-activated protein kinase (AMPK) signaling pathway. Our results show that RTA treatment rescues the ox-LDL-induced autophagy impairment in HUVECs and improves endothelium-dependent vasodilation function in SHR.

Serum cortisol as a useful predictor of cardiac events in patients with chronic heart failure: the impact of oxidative stress.

PubMed

Yamaji, Masayuki; Tsutamoto, Takayoshi; Kawahara, Chiho; Nishiyama, Keizo; Yamamoto, Takashi; Fujii, Masanori; Horie, Minoru

2009-11-01

The pathophysiological role of cortisol, which binds to the mineralocorticoid receptor with an affinity equal to that of aldosterone (ALD), may be influenced by oxidative stress in patients with chronic heart failure. We evaluated cardiac event prediction using cortisol levels in chronic heart failure, in comparison with ALD, adrenocorticotropic hormone, and brain natriuretic peptide (BNP), and the impact of oxidative stress. We measured the plasma levels of biomarkers such as BNP, ALD, adrenocorticotropic hormone, serum cortisol, and oxidized low-density lipoprotein (oxLDL), a biomarker of oxidative stress, in 319 consecutive symptomatic patients with chronic heart failure, and we followed these patients for a mean period of 33 months. During the follow-up period, 29 patients had cardiac events (death or hospitalization). Plasma levels of BNP, ALD, adrenocorticotropic hormone, oxLDL, and serum cortisol (16.8+/-1.8 microg/dL versus 12.4+/-0.3 microg/dL, P=0.01) were significantly higher in patients with cardiac events than in those without cardiac events. On stepwise multivariate analyses, high levels of BNP (P=0.0003), renin (P=0.002), cortisol (P=0.02), and oxLDL (P=0.002) were independent predictors of cardiac events, but ALD and adrenocorticotropic hormone levels were not. In patients with serum cortisol > or =12.5 microg/dL, the hazard ratio of cardiac events in patients with oxLDL > or =12 U/mL was 3.5 compared with that in patients with oxLDL <12 U/mL (P=0.008). These findings indicate that serum cortisol levels were a complementary and incremental cardiac event risk predictor in combination with BNP in patients with chronic heart failure and that cardiac event prediction based on cortisol levels was influenced by oxidative stress.

The severe hypercholesterolemia phenotype: clinical diagnosis, management, and emerging therapies.

PubMed

Sniderman, Allan D; Tsimikas, Sotirios; Fazio, Sergio

2014-05-20

The severe hypercholesterolemia phenotype includes all patients with marked elevation of low-density lipoprotein cholesterol (LDL-C) levels. The most common cause is autosomal dominant hypercholesterolemia, an inherited disorder caused by mutations either in LDL receptor, apolipoprotein B (APOB), or proprotein convertase subtilisin kexin type 9 (PCSK9) genes. However, it is now known that many subjects with severe inherited hypercholesterolemia have no defects in these genes. These cases are caused either by mutations in genes yet to be identified or are consequences of polygenic, epigenetic, or acquired defects. Because the clinical consequences of extreme hypercholesterolemia are the same no matter the cause, the focus should be on the identification of subjects with severe hypercholesterolemia, followed by phenotypic screening of family members. Genetic screening is not necessary to diagnose or initiate treatment for the severe hypercholesterolemia phenotype. Management of severe hypercholesterolemia is based on risk factor modification and use of multiple lipid-lowering medications. Lipoprotein apheresis is indicated for coronary artery disease (CAD) patients taking maximally tolerated therapy and with LDL-C levels >200 mg/dl (>300 mg/dl if without CAD). A microsomal triglyceride transfer protein inhibitor and an antisense oligonucleotide against APOB have recently been approved for use in subjects with clinically diagnosed homozygous familial hypercholesterolemia. PCSK9 inhibitors, currently in phase II and III trials, lower LDL-C up to an additional 70% in the setting of maximally tolerated medical therapy and have the potential to reduce LDL-C to <70 mg/dl in most patients. Early identification of affected individuals and aggressive treatment should significantly reduce the burden of cardiovascular disease in society. Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Obesity induced during sexual maturation is linked to LDL-triacylglycerols in Yucatan miniature swine.

PubMed

Sébert, Sylvain P; Lecannu, Gérard; Sené, Sandrine; Hucteau, Séverine; Chetiveaux, Maud; Ouguerram, Khadija; Champ, Martine M-J

2005-08-01

The incidence of childhood obesity is rising dramatically throughout industrialised countries. To evaluate and study the impact of childhood obesity on lipoprotein metabolism, we developed a new animal model of premature obesity. Yucatan mini-pigs aged 4 months were studied over a 12-month period from childhood to adulthood. Animals were divided into two groups: the first group were overfed a Western misbalanced diet; the second group were normally fed a recommended human-type diet. Cholesterol and triacylglycerol concentrations in VLDL-, LDL- and HDL-lipoproteins were followed from baseline to adulthood by fast protein liquid chromatography. At 10 (the end of sexual maturation) and 16 months old (adulthood), liver, visceral and subcutaneous adipose tissues were sampled. Real-time RT-PCR was performed in order to compare apo AI, apo B, apo C-III, PPAR-alpha, insulin receptor and lipoprotein lipase gene expression between groups and ages. Differences between groups were observed only after sexual maturity. Adult overfed mini-pigs had a higher LDL-cholesterol:HDL-cholesterol ratio (P < 0.05; 0.55 (SE 0.06) for overfed v. 0.42 (SE 0.04) for normally fed pigs at the tenth month of the study). In both groups, VLDL-triacylglycerol decreased (P < 0.05). VLDL-triacylglycerol evolution in the overfed group was associated with an increase in LDL-triacylglycerol plasma concentrations (P < 0.05) after sexual maturation. LDL-triacylglycerol concentration in overfed mini-pigs went from an average of 0.28 mmol/l before sexual maturation to reach an average concentration of 0.56 mmol/l afterwards. This phenomenon has never been observed in similar studies when obesity is induced in adult mini-pigs and may represent a specific hallmark of an obesity induced during sexual maturity.

Vascular peroxide 1 promotes ox-LDL-induced programmed necrosis in endothelial cells through a mechanism involving β-catenin signaling.

PubMed

Zhang, Yin-Zhuang; Wang, Lei; Zhang, Jie-Jie; Xiong, Xiao-Ming; Zhang, Di; Tang, Xuan-Meng; Luo, Xiu-Ju; Ma, Qi-Lin; Peng, Jun

2018-05-03

Vascular peroxidase 1 (VPO1) plays a key role in mediation of cardiovascular oxidative injury. This study aims to determine whether VPO1 can promote programmed necrosis of endothelial cells and the underlying mechanisms. Human umbilical vein endothelial cells (HUVECs) were incubated with oxidized low-density lipoprotein (ox-LDL, 100 μg/mL) for 48 h to induce cell injury, which showed an elevation in cell necrosis (reflected by the increased propidium iodide (PI) positive-staining cells, LDH release and decreased cell viability), concomitant with an increase in programmed necrosis-relevant proteins including receptor-interacting protein kinase 1/3 (RIPK1/3), p-RIPK3 and mixed lineage kinase domain like (MLKL); these phenomena were attenuated by necrostatin-1(Nec-1) and RIPK3 siRNA. Meanwhile, VPO1 was up-regulated in ox-LDL-treated endothelial cells accompanied by a decrease in GSK-3β activity and p-β-catenin levels, and an elevation of β-catenin levels; these phenomena were reversed in the presence of VPO1 siRNA or hypochlorous acid (HOCl) inhibitor; replacement of ox-LDL with HOCl could also induce endothelial programmed necrosis and activate the β-catenin signaling; β-catenin inhibitor could also suppress ox-LDL-induced RIPK-dependent necrosis. In hyperlipidemic patients, the plasma level of VPO1 was obviously increased concomitant with an elevation in plasma levels of RIPK1, RIPK3 and MLKL, and they were positively correlated. VPO1 plays an important role in promotion of endothelial programmed necrosis under hyperlipidemic conditions through activation of β-catenin signaling. It may serve as a novel therapeutic target for prevention of endothelial dysfunction in hyperlipidemia. Copyright © 2018 Elsevier B.V. All rights reserved.

Aronia berry polyphenol consumption reduces plasma total and low-density lipoprotein cholesterol in former smokers without lowering biomarkers of inflammation and oxidative stress: a randomized controlled trial.

PubMed

Xie, Liyang; Vance, Terrence; Kim, Bohkyung; Lee, Sang Gil; Caceres, Christian; Wang, Ying; Hubert, Patrice A; Lee, Ji-Young; Chun, Ock K; Bolling, Bradley W

2017-01-01

Former smokers are at increased risk for cardiovascular disease. We hypothesized that dietary aronia polyphenols would reduce biomarkers of cardiovascular disease risk, inflammation, and oxidative stress in former smokers. We also determined the extent these effects were associated with polyphenol bioavailability. A 12-week, randomized, placebo-controlled trial was conducted in 49 healthy adult former smokers (n = 24/placebo, n = 25/aronia) to evaluate if daily consumption of 500 mg aronia extract modulated plasma lipids, blood pressure, biomarkers of inflammation and oxidative stress, and lipid transport genes of peripheral blood mononuclear cells. The primary outcome was change in low-density lipoprotein cholesterol (LDL-C) from baseline, and multivariate correlation analysis was performed to determine if changes in lipids were associated with urinary polyphenol excretion. Aronia consumption reduced fasting plasma total cholesterol by 8% (P = .0140), LDL-C by 11% (P = .0285), and LDL receptor protein in peripheral blood mononuclear cells (P = .0036) at 12 weeks compared with the placebo group. Positive changes in the urinary polyphenol metabolites peonidin-3-O-galactoside, 3-(4-hydroxyphenyl) propionic acid, and unmetabolized anthocyanin cyanidin-3-O-galactoside were associated with lower plasma total cholesterol and LDL-C in the aronia group. Aronia consumption did not change blood pressure or biomarkers of inflammation and oxidative stress. Aronia polyphenols reduced total and LDL-C in former smokers but did not improve biomarkers of oxidative stress and chronic inflammation. The cholesterol-lowering activity of aronia extract was most closely associated with urinary levels of cyanidin-3-O-galactoside and peonidin-3-O-galactoside, its methylated metabolite. This trial was registered at ClinicalTrials.gov as NCT01541826. Copyright © 2016 Elsevier Inc. All rights reserved.

Pharmacologic profile of the Adnectin BMS-962476, a small protein biologic alternative to PCSK9 antibodies for low-density lipoprotein lowering.

PubMed

Mitchell, Tracy; Chao, Ginger; Sitkoff, Doree; Lo, Fred; Monshizadegan, Hossain; Meyers, Daniel; Low, Simon; Russo, Katie; DiBella, Rose; Denhez, Fabienne; Gao, Mian; Myers, Joseph; Duke, Gerald; Witmer, Mark; Miao, Bowman; Ho, Siew P; Khan, Javed; Parker, Rex A

2014-08-01

Proprotein convertase subtilisin kexin-9 (PCSK9) is an important pharmacological target for decreasing low-density lipoprotein (LDL) in cardiovascular disease, although seemingly inaccessible to small molecule approaches. Compared with therapeutic IgG antibodies currently in development, targeting circulating PCSK9 with smaller molecular scaffolds could offer different profiles and reduced dose burdens. This inspired genesis of PCSK9-binding Adnectins, a protein family derived from human fibronectin-10th-type III-domain and engineered for high-affinity target binding. BMS-962476, an ∼11-kDa polypeptide conjugated to polyethylene glycol to enhance pharmacokinetics, binds with subnanomolar affinity to human. The X-ray cocrystal structure of PCSK9 with a progenitor Adnectin shows ∼910 Å(2) of PCSK9 surface covered next to the LDL receptor binding site, largely by residues of a single loop of the Adnectin. In hypercholesterolemic, overexpressing human PCSK9 transgenic mice, BMS-962476 rapidly lowered cholesterol and free PCSK9 levels. In genomic transgenic mice, BMS-962476 potently reduced free human PCSK9 (ED50 ∼0.01 mg/kg) followed by ∼2-fold increases in total PCSK9 before return to baseline. Treatment of cynomolgus monkeys with BMS-962476 rapidly suppressed free PCSK9 >99% and LDL-cholesterol ∼55% with subsequent 6-fold increase in total PCSK9, suggesting reduced clearance of circulating complex. Liver sterol response genes were consequently downregulated, following which LDL and total PCSK9 returned to baseline. These studies highlight the rapid dynamics of PCSK9 control over LDL and liver cholesterol metabolism and characterize BMS-962476 as a potent and efficacious PCSK9 inhibitor. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Molecular sources of residual cardiovascular risk, clinical signals, and innovative solutions: relationship with subclinical disease, undertreatment, and poor adherence: implications of new evidence upon optimizing cardiovascular patient outcomes

PubMed Central

Kones, Richard

2013-01-01

Residual risk, the ongoing appreciable risk of major cardiovascular events (MCVE) in statin-treated patients who have achieved evidence-based lipid goals, remains a concern among cardiologists. Factors that contribute to this continuing risk are atherogenic non-low-density lipoprotein (LDL) particles and atherogenic processes unrelated to LDL cholesterol, including other risk factors, the inherent properties of statin drugs, and patient characteristics, ie, genetics and behaviors. In addition, providers, health care systems, the community, public policies, and the environment play a role. Major statin studies suggest an average 28% reduction in LDL cholesterol and a 31% reduction in relative risk, leaving a residual risk of about 69%. Incomplete reductions in risk, and failure to improve conditions that create risk, may result in ongoing progression of atherosclerosis, with new and recurring lesions in original and distant culprit sites, remodeling, arrhythmias, rehospitalizations, invasive procedures, and terminal disability. As a result, identification of additional agents to reduce residual risk, particularly administered together with statin drugs, has been an ongoing quest. The current model of atherosclerosis involves many steps during which disease may progress independently of guideline-defined elevations in LDL cholesterol. Differences in genetic responsiveness to statin therapy, differences in ability of the endothelium to regenerate and repair, and differences in susceptibility to nonlipid risk factors, such as tobacco smoking, hypertension, and molecular changes associated with obesity and diabetes, may all create residual risk. A large number of inflammatory and metabolic processes may also provide eventual therapeutic targets to lower residual risk. Classically, epidemiologic and other evidence suggested that raising high-density lipoprotein (HDL) cholesterol would be cardioprotective. When LDL cholesterol is aggressively lowered to targets, low HDL cholesterol levels are still inversely related to MCVE. The efflux capacity, or ability to relocate cholesterol out of macrophages, is believed to be a major antiatherogenic mechanism responsible for reduction in MCVE mediated in part by healthy HDL. HDL cholesterol is a complex molecule with antioxidative, anti-inflammatory, anti-thrombotic, antiplatelet, and vasodilatory properties, among which is protection of LDL from oxidation. HDL-associated paraoxonase-1 has a major effect on endothelial function. Further, HDL promotes endothelial repair and progenitor cell health, and supports production of nitric oxide. HDL from patients with cardiovascular disease, diabetes, and autoimmune disease may fail to protect or even become proinflammatory or pro-oxidant. Mendelian randomization and other clinical studies in which raising HDL cholesterol has not been beneficial suggest that high plasma levels do not necessarily reduce cardiovascular risk. These data, coupled with extensive preclinical information about the functional heterogeneity of HDL, challenge the “HDL hypothesis”, ie, raising HDL cholesterol per se will reduce MCVE. After the equivocal AIM-HIGH (Atherothrombosis Intervention in Metabolic Syndrome With Low HDL/High Triglycerides: Impact on Global Health Outcomes) study and withdrawal of two major cholesteryl ester transfer protein compounds, one for off-target adverse effects and the other for lack of efficacy, development continues for two other agents, ie, anacetrapib and evacetrapib, both of which lower LDL cholesterol substantially. The negative but controversial HPS2-THRIVE (the Heart Protection Study 2-Treatment of HDL to Reduce the Incidence of Vascular Events) trial casts further doubt on the HDL cholesterol hypothesis. The growing impression that HDL functionality, rather than abundance, is clinically important is supported by experimental evidence highlighting the conditional pleiotropic actions of HDL. Non-HDL cholesterol reflects the cholesterol in all atherogenic particles containing apolipoprotein B, and has outperformed LDL cholesterol as a lipid marker of cardiovascular risk and future mortality. In addition to including a measure of residual risk, the advantages of using non-HDL cholesterol as a primary lipid target are now compelling. Reinterpretation of data from the Treating to New Targets study suggests that better control of smoking, body weight, hypertension, and diabetes will help lower residual risk. Although much improved, control of risk factors other than LDL cholesterol currently remains inadequate due to shortfalls in compliance with guidelines and poor patient adherence. More efficient and greater use of proven simple therapies, such as aspirin, beta-blockers, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers, combined with statin therapy, may be more fruitful in improving outcomes than using other complex therapies. Comprehensive, intensive, multimechanistic, global, and national programs using primordial, primary, and secondary prevention to lower the total level of cardiovascular risk are necessary. PMID:24174878

Modification of SR-PSOX functions by multi-point mutations of basic amino acid residues.

PubMed

Liu, Weiwei; Yin, Lan; Dai, Yalei

2013-02-01

SR-PSOX can function as a scavenger receptor, a chemokine and an adhesion molecule, and it could be an interesting player in the formation of atherosclerotic lesions. Our previous studies demonstrated that basic amino acid residues in the chemokine domain of SR-PSOX are critical for its functions. In this study the combinations of the key basic amino acids in the chemokine domain of SR-PSOX have been identified. Five combinations of basic amino acid residues that may form conformational motif for SR-PSOX functions were selected for multi-point mutants. The double mutants of K61AR62A, R76AK79A, R82AH85A, and treble mutants of R76AR78AK79A, R78AR82AH85A were successfully constructed by replacing the combinations of two or three basic amino acid residues with alanine. After successful expression of these mutants on the cells, the functional studies showed that the cells expressing R76AK79A and R82AH85A mutants significantly increased the activity of oxLDL uptake compared with that of wild-type SR-PSOX. Meanwhile, the cells expressing R76AK79A mutant also dramatically enhanced the phagocytotic activity of SR-PSOX. However, the cells expressing the construct of combination of R78A mutation in R76AK79A or R82AH85A could abolish these effects. More interestingly, the adhesive activities were remarkably down regulated in the cells expressing the multi-point mutants respectively. This study revealed that some conformational motifs of basic amino acid residues, especially R76 with K79 in SR-PSOX, may form a common functional motif for its critical functions. R78 in SR-PSOX has the potential action to stabilize the function of oxLDL uptake and bacterial phagocytosis. The results obtained may provide new insight for the development of drug target of atherosclerosis. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Quercetin is a potent anti-atherosclerotic compound by activation of SIRT1 signaling under oxLDL stimulation.

PubMed

Hung, Ching-Hsia; Chan, Shih-Hung; Chu, Pei-Ming; Tsai, Kun-Ling

2015-10-01

Atherosclerosis is believed to be an independent predictor of cardiovascular diseases. A growing body of evidence suggests that quercetin is a potent antioxidant and anti-inflammatory compound. The molecular mechanisms underlying its protective effects against oxidative stress in human endothelial cells remain unclear. This study was designed to confirm the hypothesis that quercetin inhibits oxidized LDL (oxLDL) induced endothelial oxidative damage by activating sirtuin 1 (SIRT1) and to explore the role of adenosine monophosphate activated protein kinase (AMPK), which is a negative regulator of Nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase) and free radicals. Human umbilical vein endothelial cells were treated with oxLDL with or without quercetin pretreatment. We found that quercetin pretreatment increased SIRT1 mRNA expression. In fact, quercetin protected against oxLDL-impaired SIRT1 and AMPK activities and reduced oxLDL-activated NOX2 and NOX4. However, silencing SIRT1 and AMPK diminished the protective function of quercetin against oxidative injuries. The results also indicated that oxLDL suppressed AKT/endothelial NO synthase, impaired mitochondrial dysfunction, and enhanced reactive oxygen species formation, activating the Nuclear Factor Kappa B (NF-κB) pathway. These results provide new insight regarding the possible molecular mechanisms of quercetin. Quercetin suppresses oxLDL-induced endothelial oxidative injuries by activating SIRT1 and modulating the AMPK/NADPH oxidase/AKT/endothelial NO synthase signaling pathway. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The role of the lectin-like oxLDL receptor (LOX-1) in traffic-generated air pollution exposure-mediated alteration of the brain microvasculature in Apolipoprotein (Apo) E knockout mice.

PubMed

Lucero, JoAnn; Suwannasual, Usa; Herbert, Lindsay M; McDonald, Jacob D; Lund, Amie K

2017-05-01

Recent studies have shown a strong correlation between air pollution-exposure and detrimental outcomes in the central nervous system, including alterations in blood brain barrier (BBB) integrity, neuroinflammation, and neurodegeneration. However, the mechanisms mediating these pathologies have not yet been fully elucidated. We have previously reported that exposure to traffic-generated air pollution results in increased circulating oxidized low-density lipoprotein (oxLDL), associated with alterations in BBB integrity, in atherosclerotic Apolipoprotein E null (ApoE -/- ) mice. Thus, we investigated the role of the lectin-like oxLDL receptor (LOX)-1 in mediating these deleterious effects in ApoE -/- mice exposed to a mixture of gasoline and diesel engine exhaust (MVE: 100 PM µg/m 3 ) for 6 h/d, 7d/week, for 30 d by inhalation. Concurrent with exposures, a subset of mice were treated with neutralizing antibodies to LOX-1 (LOX-1 Ab) i.p., or IgG (control) i.p., every other day during exposures. Resulting brain microvascular integrity, tight junction (TJ) protein expression, matrix metalloproteinase (MMP)-9/-2 activity, ROS, and markers of cellular adhesion and monocyte/macrophage sequestration were assessed. MVE-exposure resulted in decreased BBB integrity and alterations in microvascular TJ protein expression, associated with increased LOX-1 expression, MMP-9/-2 activities, and lipid peroxidation, each of which was attenuated with LOX-1 Ab treatment. Furthermore, MVE-exposure induced cerebral microvascular ROS and adhesion molecules, expression of which was not normalized through LOX-1 Ab-treatment. Such findings suggest that alterations in brain microvascular structure and integrity observed with MVE-exposure may be mediated, at least in part, via LOX-1 signaling.

Obeticholic acid raises LDL-cholesterol and reduces HDL-cholesterol in the Diet-Induced NASH (DIN) hamster model.

PubMed

Briand, François; Brousseau, Emmanuel; Quinsat, Marjolaine; Burcelin, Rémy; Sulpice, Thierry

2018-01-05

The use of rat and mouse models limits the translation to humans for developing novel drugs targeting nonalcoholic steatohepatitis (NASH). Obeticholic acid (OCA) illustrates this limitation since its dyslipidemic effect in humans cannot be observed in these rodents. Conversely, Golden Syrian hamsters have a lipoprotein metabolism mimicking human dyslipidemia since it does express the cholesteryl ester transfer protein (CETP). We therefore developed a Diet-Induced NASH (DIN) hamster model and evaluated the impact of OCA. Compared with chow fed controls, hamsters fed for 20 weeks with a free-choice (FC) diet, developed obesity, insulin resistance, dyslipidemia and NASH (microvesicular steatosis, inflammation, hepatocyte ballooning and perisinusoidal to bridging fibrosis). After 20 weeks of diet, FC fed hamsters were treated without or with obeticholic acid (15mg/kg/day) for 5 weeks. Although a non-significant trend towards higher dietary caloric intake was observed, OCA significantly lowered body weight after 5 weeks of treatment. OCA significantly increased CETP activity and LDL-C levels by 20% and 27%, and reduced HDL-C levels by 20%. OCA blunted hepatic gene expression of Cyp7a1 and Cyp8b1 and reduced fecal bile acids mass excretion by 64% (P < 0.05). Hamsters treated with OCA showed a trend towards higher scavenger receptor Class B type I (SR-BI) and lower LDL-receptor hepatic protein expression. OCA reduced NAS score for inflammation (P < 0.01) and total NAS score, although not significantly. Compared to mouse and rat models, the DIN hamster replicates benefits and side effects of OCA as observed in humans, and should be useful for evaluating novel drugs targeting NASH. Copyright © 2017 Elsevier B.V. All rights reserved.

A Genomic DNA Reporter Screen Identifies Squalene Synthase Inhibitors That Act Cooperatively with Statins to Upregulate the Low-Density Lipoprotein Receptor

PubMed Central

Kerr, Alastair G.; Tam, Lawrence C. S.; Hale, Ashley B.; Cioroch, Milena; Douglas, Gillian; Agkatsev, Sarina; Hibbitt, Olivia; Mason, Joseph; Holt-Martyn, James; Bataille, Carole J. R.; Wynne, Graham M.; Channon, Keith M.; Russell, Angela J.

2017-01-01

Hypercholesterolemia remains one of the leading risk factors for the development of cardiovascular disease. Many large double-blind studies have demonstrated that lowering low-density lipoprotein (LDL) cholesterol using a statin can reduce the risk of having a cardiovascular event by approximately 30%. However, despite the success of statins, some patient populations are unable to lower their LDL cholesterol to meet the targeted lipid levels, due to compliance or potency issues. This is especially true for patients with heterozygous familial hypercholesterolemia who may require additional upregulation of the low-density lipoprotein receptor (LDLR) to reduce LDL cholesterol levels below those achievable with maximal dosing of statins. Here we identify a series of small molecules from a genomic DNA reporter screen that upregulate the LDLR in mouse and human liver cell lines at nanomolar potencies (EC50 = 39 nM). Structure-activity relationship studies carried out on the lead compound, OX03771 [(E)-N,N-dimethyl-3-(4-styrylphenoxy)propan-1-amine], led to the identification of compound OX03050 [(E)-3-(4-styrylphenoxy)propan-1-ol], which had similar potency (EC50 = 26 nM) but a much-improved pharmacokinetic profile and showed in vivo efficacy. Compounds OX03050 and OX03771 were found to inhibit squalene synthase, the first committed step in cholesterol biosynthesis. These squalene synthase inhibitors were shown to act cooperatively with statins to increase LDLR expression in vitro. Overall, we demonstrated here a novel series of small molecules with the potential to be further developed to treat patients either alone or in combination with statins. PMID:28360334

CD47 and Nox1 Mediate Dynamic Fluid-Phase Macropinocytosis of Native LDL

PubMed Central

Csányi, Gábor; Feck, Douglas M.; Ghoshal, Pushpankur; Singla, Bhupesh; Lin, Huiping; Nagarajan, Shanmugam; Meijles, Daniel N.; Al Ghouleh, Imad; Cantu-Medellin, Nadiezhda; Kelley, Eric E.; Mateuszuk, Lukasz; Isenberg, Jeffrey S.; Watkins, Simon

2017-01-01

Abstract Aims: Macropinocytosis has been implicated in cardiovascular and other disorders, yet physiological factors that initiate fluid-phase internalization and the signaling mechanisms involved remain poorly identified. The present study was designed to examine whether matrix protein thrombospondin-1 (TSP1) stimulates macrophage macropinocytosis and, if so, to investigate the potential signaling mechanism involved. Results: TSP1 treatment of human and murine macrophages stimulated membrane ruffle formation and pericellular solute internalization by macropinocytosis. Blockade of TSP1 cognate receptor CD47 and NADPH oxidase 1 (Nox1) signaling, inhibition of phosphoinositide 3-kinase, and transcriptional knockdown of myotubularin-related protein 6 abolished TSP1-induced macropinocytosis. Our results demonstrate that Nox1 signaling leads to dephosphorylation of actin-binding protein cofilin at Ser-3, actin remodeling, and macropinocytotic uptake of unmodified native low-density lipoprotein (nLDL), leading to foam cell formation. Finally, peritoneal chimera studies suggest the role of CD47 in macrophage lipid macropinocytosis in hypercholesterolemic ApoE−/− mice in vivo. Innovation: Activation of a previously unidentified TSP1-CD47 signaling pathway in macrophages stimulates direct receptor-independent internalization of nLDL, leading to significant lipid accumulation and foam cell formation. These findings reveal a new paradigm in which delimited Nox1-mediated redox signaling, independent of classical lipid oxidation, contributes to early propagation of vascular inflammatory disease. Conclusions: The findings of the present study demonstrate a new mechanism of solute uptake with implications for a wide array of cell types, including macrophages, dendritic cells, and cancer cells, and multiple pathological conditions in which matrix proteins are upregulated. Antioxid. Redox Signal. 26, 886–901. PMID:27958762

Lipid-lowering properties of TAK-475, a squalene synthase inhibitor, in vivo and in vitro.

PubMed

Nishimoto, Tomoyuki; Amano, Yuichiro; Tozawa, Ryuichi; Ishikawa, Eiichiro; Imura, Yoshimi; Yukimasa, Hidefumi; Sugiyama, Yasuo

2003-07-01

1. Squalene synthase is the enzyme that converts farnesyl pyrophosphate to squalene in the cholesterol biosynthesis pathway. We examined the lipid-lowering properties of 1-[[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-5-(2,3-dimethoxyphenyl)-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]acetyl]piperidine-4-acetic acid (TAK-475), a novel squalene synthase inhibitor. 2. TAK-475 inhibited hepatic cholesterol biosynthesis in rats (ED(50), 2.9 mg kg(-1)) and showed lipid-lowering effects in beagle dogs, marmosets, cynomolgus monkeys and Wistar fatty rats. 3. In marmosets, TAK-475 (30, 100 mg kg(-1), p.o., for 4 days) lowered both plasma non-high-density lipoprotein (HDL) cholesterol and triglyceride, but did not affect plasma HDL cholesterol. On the other hand, atorvastatin (10, 30 mg kg(-1), p.o., for 4 days) lowered the levels of all these lipids. A correlation between decrease in triglyceride and increase in HDL cholesterol was observed, and TAK-475 increased HDL cholesterol with a smaller decrease in triglyceride than did atorvastatin. 4. TAK-475 (60 mg kg(-1), p.o., for 15 days) suppressed the rate of triglyceride secretion from the liver in hypertriglyceridemic Wistar fatty rats, which show an enhanced triglyceride secretion rate from the liver compared with their lean littermates. 5. In HepG2 cells, TAK-475 and its pharmacologically active metabolite, T-91485, increased the binding of (125)I-low-density lipoprotein (LDL) to LDL receptors. 6. These results suggest that TAK-475 has clear hypolipidemic effects in animals via inhibition of hepatic triglyceride secretion and upregulation of LDL receptors, and that TAK-475 might increase HDL cholesterol by decreasing triglyceride. Thus, TAK-475 is expected to be useful for the treatment of dyslipidemia.

Lipid-lowering properties of TAK-475, a squalene synthase inhibitor, in vivo and in vitro

PubMed Central

Nishimoto, Tomoyuki; Amano, Yuichiro; Tozawa, Ryuichi; Ishikawa, Eiichiro; Imura, Yoshimi; Yukimasa, Hidefumi; Sugiyama, Yasuo

2003-01-01

Squalene synthase is the enzyme that converts farnesyl pyrophosphate to squalene in the cholesterol biosynthesis pathway. We examined the lipid-lowering properties of 1-[[(3R,5S)-1-(3-acetoxy-2,2-dimethylpropyl)-7-chloro-5-(2,3-dimethoxyphenyl)-2-oxo-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-yl]acetyl]piperidine-4-acetic acid (TAK-475), a novel squalene synthase inhibitor. TAK-475 inhibited hepatic cholesterol biosynthesis in rats (ED50, 2.9 mg kg−1) and showed lipid-lowering effects in beagle dogs, marmosets, cynomolgus monkeys and Wistar fatty rats. In marmosets, TAK-475 (30, 100 mg kg−1, p.o., for 4 days) lowered both plasma non-high-density lipoprotein (HDL) cholesterol and triglyceride, but did not affect plasma HDL cholesterol. On the other hand, atorvastatin (10, 30 mg kg−1, p.o., for 4 days) lowered the levels of all these lipids. A correlation between decrease in triglyceride and increase in HDL cholesterol was observed, and TAK-475 increased HDL cholesterol with a smaller decrease in triglyceride than did atorvastatin. TAK-475 (60 mg kg−1, p.o., for 15 days) suppressed the rate of triglyceride secretion from the liver in hypertriglyceridemic Wistar fatty rats, which show an enhanced triglyceride secretion rate from the liver compared with their lean littermates. In HepG2 cells, TAK-475 and its pharmacologically active metabolite, T-91485, increased the binding of 125I-low-density lipoprotein (LDL) to LDL receptors. 6 These results suggest that TAK-475 has clear hypolipidemic effects in animals via inhibition of hepatic triglyceride secretion and upregulation of LDL receptors, and that TAK-475 might increase HDL cholesterol by decreasing triglyceride. Thus, TAK-475 is expected to be useful for the treatment of dyslipidemia. PMID:12839864

Newer antiatherosclerosis treatment strategies.

PubMed

Aggarwal, Amitesh; Singh, Safal

2011-01-01

Atherosclerosis has been a target of much clinical and molecular research. As a result of this extensive research, it is amply clear that atherogenesis is a multifactorial process involving an interplay of metabolic, immune and inflammatory mechanisms. Antiatherosclerotic strategies are today aiming for a multipronged approach targeting each arm of this multifactorial process. The newer agents under development can be divided into three broad categories: anti-inflammatory agents, modulators of intermediary metabolism and antiatherosclerosis vaccines. Potential targets for anti-inflammatory agents include inhibition of conversion of low-density lipoprotein (LDL) to oxidised LDL, blocking or downregulation of cell adhesion molecules, chemokine modulation and macrophage receptor blockade. Beyond inhibition of plaque formation, efforts are also ongoing to develop agents which stabilise the plaque by increasing its fibrous content and inhibiting its disruption. So far as research in the sphere of intermediary metabolism is concerned, the focus is now primarily on raising high-density lipoprotein and promoting reverse cholesterol transport; potential targets include cholesteryl ester transfer protein, liver X-receptor, lecithin cholesterol acyltransferase and high-density lipoprotein mimetics. Acyl-coenzymeA: cholesterol acyltransferase is another enzyme whose selective and differential inhibition is under active investigation. The concept of immunisation against a non-communicable disease such as atherosclerosis is still in its nascent stages. However, with increasing evidence to suggest the role of antigen-specific T-cell-mediated immunity in atherogenesis, this approach is potentially promising. Possible antigens under evaluation include oxidised LDL and its subparticles, heat-shock proteins and cholesteryl ester transfer protein. With cardiovascular disease being the single leading cause of death worldwide, the development of a safe and successful antiatherosclerosis strategy (possibly employing a combination of agents acting at various levels) will indeed be a major 21st-century achievement.

Independent Link Between Levels of Proprotein Convertase Subtilisin/Kexin Type 9 and FABP4 in a General Population Without Medication.

PubMed

Furuhashi, Masato; Omori, Akina; Matsumoto, Megumi; Kataoka, Yu; Tanaka, Marenao; Moniwa, Norihito; Ohnishi, Hirofumi; Yoshida, Hideaki; Saitoh, Shigeyuki; Shimamoto, Kazuaki; Miura, Tetsuji

2016-07-15

Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to and degrades the low-density lipoprotein (LDL) receptor, leading to hypercholesterolemia and cardiovascular risk. Fatty acid binding protein 4 (FABP4/adipocyte FABP/aP2) is secreted from adipocytes in association with lipolysis, and circulating FABP4 has been reported to act as an adipokine for the development of insulin resistance and atherosclerosis. Elevated serum FABP4 level is associated with obesity, insulin resistance, dyslipidemia, and atherosclerosis. In this study, we examined the association between circulating levels of FABP4 and PCSK9 in a general population. A total of 265 subjects (male/female: 98/167) who were not on medication were recruited from subjects of the Tanno-Sobetsu Study, and concentrations of FABP4 and PCSK9 were measured. The level of FABP4, but not that of PCSK9, showed a gender difference, being higher in women than in men. FABP4 level was independently associated with gender, adiposity, renal dysfunction, and levels of cholesterol and PCSK9. There was a significant and gender-different correlation between PCSK9 level and age: negatively in men (r = -0.250, p = 0.013) and positively in women (r = 0.183, p = 0.018). After adjustment of age, gender, and LDL cholesterol level, PCSK9 level was positively and independently correlated with FABP4 concentration. In conclusion, PCSK9 level is differentially regulated by gender during aging. Circulating FABP4 is independently associated with the PCSK9 level, suggesting that elevation of FABP4 level as an adipokine leads to dyslipidemia through increased PCSK9 level and subsequent degradation of the LDL receptor. Copyright © 2016 Elsevier Inc. All rights reserved.

Polyphenol-rich black chokeberry (Aronia melanocarpa) extract regulates the expression of genes critical for intestinal cholesterol flux in Caco-2 cells.

PubMed

Kim, Bohkyung; Park, Youngki; Wegner, Casey J; Bolling, Bradley W; Lee, Jiyoung

2013-09-01

Black chokeberry (Aronia melanocarpa) is a rich source of polyphenols. The hypolipidemic effects of polyphenol-rich black chokeberry extract (CBE) have been reported, but underlying mechanisms have not been well characterized. We investigated the effect of CBE on the expression of genes involved in intestinal lipid metabolism. Caco-2 cells were incubated with 50 or 100 μg/ml of CBE for 24 h for quantitative realtime polymerase chain reaction analysis. Expression of genes for cholesterol synthesis (3-hydroxy-3-methylglutaryl coenzyme A reductase and sterol regulatory element binding protein 2), apical cholesterol uptake (Niemann-Pick C1 Like 1 and scavenger receptor class B Type 1) and basolateral cholesterol efflux [ATP-binding cassette transporter A1 (ABCA1)] was significantly decreased by CBE compared with control. Western blot analysis confirmed that CBE inhibited expression of these proteins. In contrast, CBE markedly induced mRNA and/or protein levels of ABCG5 and ABCG8 that mediate apical cholesterol efflux to the intestinal lumen. Furthermore, CBE significantly increased mRNA and protein levels of low-density lipoprotein (LDL) receptor, and cellular LDL uptake. Expression of genes involved in lipid metabolism and lipoprotein assembly, including sterol regulatory element-binding protein 1c, fatty acid synthase and acyl-CoA oxidase 1, was significantly decreased by CBE in a dose-dependent manner. Concomitantly, CBE significantly increased sirtuin 1, 3 and 5 mRNA levels, while it decreased SIRT-2. Our data suggest that hypolipidemic effects of CBE may be attributed, at least in part, to increased apical efflux of LDL-derived cholesterol and to decreased chylomicron formation in the intestine; and specific isoforms of SIRT may play an important role in this process. Copyright © 2013 Elsevier Inc. All rights reserved.

Characterization of a mammalian Golgi-localized protein complex, COG, that is required for normal Golgi morphology and function

PubMed Central

Ungar, Daniel; Oka, Toshihiko; Brittle, Elizabeth E.; Vasile, Eliza; Lupashin, Vladimir V.; Chatterton, Jon E.; Heuser, John E.; Krieger, Monty; Waters, M. Gerard

2002-01-01

Multiprotein complexes are key determinants of Golgi apparatus structure and its capacity for intracellular transport and glycoprotein modification. Three complexes that have previously been partially characterized include (a) the Golgi transport complex (GTC), identified in an in vitro membrane transport assay, (b) the ldlCp complex, identified in analyses of CHO cell mutants with defects in Golgi-associated glycosylation reactions, and (c) the mammalian Sec34 complex, identified by homology to yeast Sec34p, implicated in vesicular transport. We show that these three complexes are identical and rename them the conserved oligomeric Golgi (COG) complex. The COG complex comprises four previously characterized proteins (Cog1/ldlBp, Cog2/ldlCp, Cog3/Sec34, and Cog5/GTC-90), three homologues of yeast Sec34/35 complex subunits (Cog4, -6, and -8), and a previously unidentified Golgi-associated protein (Cog7). EM of ldlB and ldlC mutants established that COG is required for normal Golgi morphology. “Deep etch” EM of purified COG revealed an ∼37-nm-long structure comprised of two similarly sized globular domains connected by smaller extensions. Consideration of biochemical and genetic data for mammalian COG and its yeast homologue suggests a model for the subunit distribution within this complex, which plays critical roles in Golgi structure and function. PMID:11980916

Homozygous familial hypercholesterolemia (HoFH) in Germany: an epidemiological survey.

PubMed

Walzer, S; Travers, K; Rieder, S; Erazo-Fischer, E; Matusiewicz, D

2013-01-01

In Europe a disease is recognized as rare if less than 1 in 2000 people suffer from the specific disease. In patients with familial homozygous hypercholesterolemia (HoFH) the accumulation of low-density lipoprotein cholesterol (LDL-C) leads to generalized atherosclerosis due to an insufficient functioning of the LDL-C receptors. Patients die early sometimes even in the mid-30s, from myocardial infarction or stroke. For the German population, insufficient epidemiological evidence exists. A systematic literature search in EMBASE and Medline was performed in conjunction with a targeted manual search for epidemiological HoFH studies. Additionally a nationwide survey was conducted in Germany in all identified apheresis- and lipid centers. The purpose of the survey was the validation of the systematic literature search results based on empirical (practice) data. In total 961 publications were found, 874 were excluded based on pre-defined exclusion criteria leaving only 87 for further review. After review of the identified abstracts (n = 87) 23 publications were identified as epidemiological studies. Only one publication was found which reported a prevalence of 1:1,000,000. The qualitative survey among 187 physicians in Germany also revealed a low prevalence: 95 HoFH patients were identified in 35 centers. The estimated frequency of homozygous familial hypercholesterolemia patients in Germany is around 95 (1:860,000) and the disease should be recognized as rare according to the definition of the European Medical Agency.

Connective Tissue Growth Factor Domain 4 Amplifies Fibrotic Kidney Disease through Activation of LDL Receptor-Related Protein 6.

PubMed

Johnson, Bryce G; Ren, Shuyu; Karaca, Gamze; Gomez, Ivan G; Fligny, Cécile; Smith, Benjamin; Ergun, Ayla; Locke, George; Gao, Benbo; Hayes, Sebastian; MacDonnell, Scott; Duffield, Jeremy S

2017-06-01

Connective tissue growth factor (CTGF), a matrix-associated protein with four distinct cytokine binding domains, has roles in vasculogenesis, wound healing responses, and fibrogenesis and is upregulated in fibroblasts and myofibroblasts in disease. Here, we investigated the role of CTGF in fibrogenic cells. In mice, tissue-specific inducible overexpression of CTGF by kidney pericytes and fibroblasts had no bearing on nephrogenesis or kidney homeostasis but exacerbated inflammation and fibrosis after ureteral obstruction. These effects required the WNT receptor LDL receptor-related protein 6 (LRP6). Additionally, pericytes isolated from these mice became hypermigratory and hyperproliferative on overexpression of CTGF. CTGF is cleaved in vivo into distinct domains. Treatment with recombinant domain 1, 1+2 (N terminus), or 4 (C terminus) independently activated myofibroblast differentiation and wound healing responses in cultured pericytes, but domain 4 showed the broadest profibrotic activity. Domain 4 exhibited low-affinity binding to LRP6 in in vitro binding assays, and inhibition of LRP6 or critical signaling cascades downstream of LRP6, including JNK and WNT/ β -catenin, inhibited the biologic activity of domain 4. Administration of blocking antibodies specifically against CTGF domain 4 or recombinant Dickkopf-related protein-1, an endogenous inhibitor of LRP6, effectively inhibited inflammation and fibrosis associated with ureteral obstruction in vivo Therefore, domain 4 of CTGF and the WNT signaling pathway are important new targets in fibrosis. Copyright © 2017 by the American Society of Nephrology.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) can mediate degradation of the low density lipoprotein receptor-related protein 1 (LRP-1).

PubMed

Canuel, Maryssa; Sun, Xiaowei; Asselin, Marie-Claude; Paramithiotis, Eustache; Prat, Annik; Seidah, Nabil G

2013-01-01

Elevated LDL-cholesterol (LDLc) levels are a major risk factor for cardiovascular disease and atherosclerosis. LDLc is cleared from circulation by the LDL receptor (LDLR). Proprotein convertase subtilisin/kexin 9 (PCSK9) enhances the degradation of the LDLR in endosomes/lysosomes, resulting in increased circulating LDLc. PCSK9 can also mediate the degradation of LDLR lacking its cytosolic tail, suggesting the presence of as yet undefined lysosomal-targeting factor(s). Herein, we confirm this, and also eliminate a role for the transmembrane-domain of the LDLR in mediating its PCSK9-induced internalization and degradation. Recent findings from our laboratory also suggest a role for PCSK9 in enhancing tumor metastasis. We show herein that while the LDLR is insensitive to PCSK9 in murine B16F1 melanoma cells, PCSK9 is able to induce degradation of the low density lipoprotein receptor-related protein 1 (LRP-1), suggesting distinct targeting mechanisms for these receptors. Furthermore, PCSK9 is still capable of acting upon the LDLR in CHO 13-5-1 cells lacking LRP-1. Conversely, PCSK9 also acts on LRP-1 in the absence of the LDLR in CHO-A7 cells, where re-introduction of the LDLR leads to reduced PCSK9-mediated degradation of LRP-1. Thus, while PCSK9 is capable of inducing degradation of LRP-1, the latter is not an essential factor for LDLR regulation, but the LDLR effectively competes with LRP-1 for PCSK9 activity. Identification of PCSK9 targets should allow a better understanding of the consequences of PCSK9 inhibition for lowering LDLc and tumor metastasis.

Novel developmental biology-based protocol of embryonic stem cell differentiation to morphologically sound and functional yet immature hepatocytes.

PubMed

Bukong, Terence N; Lo, Tracie; Szabo, Gyongyi; Dolganiuc, Angela

2012-05-01

Liver diseases are common in the United States and often require liver transplantation; however, donated organs are limited and thus alternative sources for liver cells are in high demand. Embryonic stem cells (ESC) can provide a continuous and readily available source of liver cells. ESC differentiation to liver cells is yet to be fully understood and comprehensive differentiation protocols are yet to be defined. Here, we aimed to achieve human (h)ESC differentiation into mature hepatocytes using defined recombinant differentiation factors and metabolites. Embryonic stem cell H1 line was sub-cultured on feeder layer. We induced hESCs into endodermal differentiation succeeded by early/late hepatic specification and finally into hepatocyte maturation using step combinations of Activin A and fibroblast growth factor (FGF)-2 for 7 days; followed by FGF-4 and bone morphogenic protein 2 (BMP2) for 7 days, succeeded by FGF-10 + hepatocyte growth factor 4 + epidermal growth factor for 14 days. Specific inhibitors/stimulators were added sequentially throughout differentiation. Cells were analysed by PCR, flow cytometry, microscopy or functional assays. Our hESC differentiation protocol resulted in viable cells with hepatocyte shape and morphology. We observed gradual changes in cell transcriptome, including up-regulation of differentiation-promoting GATA4, GATA6, POU5F1 and HNF4 transcription factors, steady levels of stemness-promoting SOX-2 and low levels of Nanog, as defined by PCR. The hESC-derived hepatocytes expressed alpha-antitrypsin, CD81, cytokeratin 8 and low density lipoprotein (LDL) receptor. The levels of alpha-fetoprotein and proliferation marker Ki-67 in hESC-derived hepatocytes remained elevated. Unlike stem cells, the hESC-derived hepatocytes performed LDL uptake, produced albumin and alanine aminotransferase and had functional alcohol dehydrogenase. We report a novel protocol for hESC differentiation into morphological and functional yet immature hepatocytes as an alternative method for hepatocyte generation. © 2012 John Wiley & Sons A/S.

Intake of up to 3 Eggs per Day Is Associated with Changes in HDL Function and Increased Plasma Antioxidants in Healthy, Young Adults.

PubMed

DiMarco, Diana M; Norris, Gregory H; Millar, Courtney L; Blesso, Christopher N; Fernandez, Maria Luz

2017-03-01

Background: HDL function may be more important than HDL concentration in determining risk for cardiovascular disease. In addition, HDL is a carrier of carotenoids and antioxidant enzymes, which protect HDL and LDL particles against oxidation. Objective: The goal of this study was to determine the impact of consuming 0-3 eggs/d on LDL and HDL particle size, HDL function, and plasma antioxidants in a young, healthy population. Methods: Thirty-eight healthy men and women [age 18-30 y, body mass index (in kg/m 2 ) 18.5-29.9] participated in this 14-wk crossover intervention. Subjects underwent a 2-wk washout (0 eggs/d) followed by sequentially increasing intake of 1, 2, and 3 eggs/d for 4 wk each. After each period, fasting blood was collected for analysis of lipoprotein subfractions, plasma apolipoprotein (apo) concentration, lutein and zeaxanthin concentration, and activities of lecithin-cholesterol acyltransferase, cholesteryl ester transfer protein, and paraoxonase-1. Results: Compared with intake of 0 eggs/d, consuming 1-3 eggs/d resulted in increased large-LDL (21-37%) and large-HDL (6-13%) particle concentrations, plasma apoAI (9-15%), and lecithin-cholesterol acyltransferase activity (5-15%) ( P < 0.05 for all biomarkers). Intake of 2-3 eggs/d also promoted an 11% increase in apoAII ( P < 0.05) and a 20-31% increase in plasma lutein and zeaxanthin ( P < 0.05), whereas intake of 3 eggs/d resulted in a 9-16% increase in serum paraoxonase-1 activity compared with intake of 1-2 eggs/d ( P < 0.05). Egg intake did not affect cholesteryl ester transfer protein activity. Conclusions: Intake of 1 egg/d was sufficient to increase HDL function and large-LDL particle concentration; however, intake of 2-3 eggs/d supported greater improvements in HDL function as well as increased plasma carotenoids. Overall, intake of ≤3 eggs/d favored a less atherogenic LDL particle profile, improved HDL function, and increased plasma antioxidants in young, healthy adults. This trial was registered at clinicaltrials.gov as NCT02531958. © 2017 American Society for Nutrition.

Mechanism of transfer of LDL-derived free cholesterol to HDL subfractions in human plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miida, T.; Fielding, C.J.; Fielding, P.E.

1990-11-01

The transfer of ({sup 3}H)cholesterol in low-density lipoprotein (LDL) to different high-density lipoprotein (HDL) species in native human plasma was determined by using nondenaturing two-dimensional electrophoresis. Transfer from LDL had a t{sub 1/2} at 37{degree}C of 51 {plus minus} 8 min and an activation energy of 18.0 kCal mol{sup {minus}1}. There was unexpected specificity among HDL species as acceptors of LDL-derived labeled cholesterol. The largest fraction of the major {alpha}-migrating class (HDL{sub 2b}) was the major initial acceptor of LDL-derived cholesterol. Kinetic analysis indicated a rapid secondary transfer from HDL{sub 2b} to smaller {alpha}HDL (particularly HDL{sub 3}) driven enzymatically bymore » the lecithin-cholesterol acyltransferase reaction. Rates of transfer among {alpha}HDL were most rapid from the largest {alpha}HDL fraction (HDL{sub 2b}), suggesting possible protein-mediated facilitation. Simultaneous measurements of the transport of LDL-derived and cell-derived isotopic cholesterol indicated that the former preferably utilized the {alpha}HDL pathyway, with little label in pre-{beta}HDL. The same experiments confirmed earlier data that cell-derived cholesterol is preferentially channeled through pre-{beta}HDL. The authors suggest that the functional heterogeneity of HDL demonstrated here includes the ability to independently process cell- and LDL-derived free cholesterol.« less

In vitro knockout of human p47phox blocks superoxide anion production and LDL oxidation by activated human monocytes.

PubMed

Bey, E A; Cathcart, M K

2000-03-01

We previously reported that superoxide dismutase (SOD) blocked human monocyte oxidation of LDL and therefore concluded that superoxide anion (O(2)(.-)) was required for oxidation. Others, however, have suggested that SOD may inhibit by mechanisms alternative to the dismutation of O(2)(.-). This study definitively addresses the involvement of O(2)(.-) in monocyte oxidation of LDL. Using an antisense ODN designed to target p47phox mRNA, we found that treatment of monocytes with antisense ODN caused a substantial and selective decrease in expression of p47phox protein, whereas sense ODN was without effect. Corresponding functional assays demonstrated that antisense ODN inhibited production of O(2)(.-). As sense ODN caused no inhibition of O(2)(.-) production, these results suggested that inhibition of p47phox expression caused reduction in O(2)(.-) production. Evaluation of the contribution of O(2)(.-) production to monocyte-mediated oxidation of LDL lipids confirmed that O(2)(.-) production is required for LDL lipid oxidation as antisense ODN treatment significantly inhibited LDL oxidation whereas sense ODN treatment caused no inhibition. This is the first report of the reduction of NADPH oxidase activity in intact human monocytes by directly targeting the mRNA of a significant member of this enzyme complex. Our results provide convincing data that O(2)(.-) is indeed required for monocyte-mediated LDL oxidation.

Cholesterol-lowering Action of BNA-based Antisense Oligonucleotides Targeting PCSK9 in Atherogenic Diet-induced Hypercholesterolemic Mice.

PubMed

Yamamoto, Tsuyoshi; Harada-Shiba, Mariko; Nakatani, Moeka; Wada, Shunsuke; Yasuhara, Hidenori; Narukawa, Keisuke; Sasaki, Kiyomi; Shibata, Masa-Aki; Torigoe, Hidetaka; Yamaoka, Tetsuji; Imanishi, Takeshi; Obika, Satoshi

2012-05-15

Recent findings in molecular biology implicate the involvement of proprotein convertase subtilisin/kexin type 9 (PCSK9) in low-density lipoprotein receptor (LDLR) protein regulation. The cholesterol-lowering potential of anti-PCSK9 antisense oligonucleotides (AONs) modified with bridged nucleic acids (BNA-AONs) including 2',4'-BNA (also called as locked nucleic acid (LNA)) and 2',4'-BNA(NC) chemistries were demonstrated both in vitro and in vivo. An in vitro transfection study revealed that all of the BNA-AONs induce dose-dependent reductions in PCSK9 messenger RNA (mRNA) levels concomitantly with increases in LDLR protein levels. BNA-AONs were administered to atherogenic diet-fed C57BL/6J mice twice weekly for 6 weeks; 2',4'-BNA-AON that targeted murine PCSK9 induced a dose-dependent reduction in hepatic PCSK9 mRNA and LDL cholesterol (LDL-C); the 43% reduction of serum LDL-C was achieved at a dose of 20 mg/kg/injection with only moderate increases in toxicological indicators. In addition, the serum high-density lipoprotein cholesterol (HDL-C) levels increased. These results support antisense inhibition of PCSK9 as a potential therapeutic approach. When compared with 2',4'-BNA-AON, 2',4'-BNA(NC)-AON showed an earlier LDL-C-lowering effect and was more tolerable in mice. Our results validate the optimization of 2',4'-BNA(NC)-based anti-PCSK9 antisense molecules to produce a promising therapeutic agent for the treatment of hypercholesterolemia.

My Approach to the Patient With Familial Hypercholesterolemia

PubMed Central

Safarova, Maya S.; Kullo, Iftikhar J.

2017-01-01

Familial hypercholesterolemia (FH), a relatively common Mendelian genetic disorder, is associated with a dramatically increased lifetime risk of premature atherosclerotic cardiovascular disease due to elevated plasma low-density lipoprotein cholesterol (LDL-C) levels. The diagnosis of FH is based on clinical presentation or genetic testing. Early identification of patients with FH is of great public health importance because preventive strategies can lower the absolute lifetime cardiovascular risk and screening can detect affected relatives. However, low awareness, detection, and control of FH pose hurdles in the prevention of FH-related cardiovascular events. Of the estimated 0.65 million to 1 million patients with FH in the United States, less than 10% carry a diagnosis of FH. Based on registry data, a substantial proportion of patients with FH are receiving no or inadequate lipid-lowering therapy. Statins remain the mainstay of treatment for patients with FH. Lipoprotein apheresis and newly approved lipid-lowering drugs are valuable adjuncts to statin therapy, particularly when the LDL-C–lowering response is suboptimal. Monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9 provide an additional approximately 60% lowering of LDL-C levels and are approved for use in patients with FH. For homozygous FH, 2 new drugs that work independent of the LDL receptor pathway are available: an apolipoprotein B antisense oligonucleotide (mipomersen) and a microsomal triglyceride transfer protein inhibitor (lomitapide). This review attempts to critically examine the available data to provide a summary of the current evidence for managing patients with FH, including screening, diagnosis, treatment, and surveillance. PMID:27261867

Optimization of LDL targeted nanostructured lipid carriers of 5-FU by a full factorial design.

PubMed

Andalib, Sare; Varshosaz, Jaleh; Hassanzadeh, Farshid; Sadeghi, Hojjat

2012-01-01

Nanostructured lipid carriers (NLC) are a mixture of solid and liquid lipids or oils as colloidal carrier systems that lead to an imperfect matrix structure with high ability for loading water soluble drugs. The aim of this study was to find the best proportion of liquid and solid lipids of different types for optimization of the production of LDL targeted NLCs used in carrying 5-Fu by the emulsification-solvent evaporation method. The influence of the lipid type, cholesterol or cholesteryl stearate for targeting LDL receptors, oil type (oleic acid or octanol), lipid and oil% on particle size, surface charge, drug loading efficiency, and drug released percent from the NLCs were studied by a full factorial design. The NLCs prepared by 54.5% cholesterol and 25% of oleic acid, showed optimum results with particle size of 105.8 nm, relatively high zeta potential of -25 mV, drug loading efficiency of 38% and release efficiency of about 40%. Scanning electron microscopy of nanoparticles confirmed the results of dynamic light scattering method used in measuring the particle size of NLCs. The optimization method by a full factorial statistical design is a useful optimization method for production of nanostructured lipid carriers.

Nonlinear associations between plasma cholesterol levels and neuropsychological function.

PubMed

Wendell, Carrington R; Zonderman, Alan B; Katzel, Leslie I; Rosenberger, William F; Plamadeala, Victoria V; Hosey, Megan M; Waldstein, Shari R

2016-11-01

Although both high and low levels of total and low-density lipoprotein (LDL) cholesterol have been associated with poor neuropsychological function, little research has examined nonlinear effects. We examined quadratic relations of cholesterol to performance on a comprehensive neuropsychological battery. Participants were 190 older adults (53% men, ages 54-83) free of major medical, neurologic, and psychiatric disease. Measures of fasting plasma total and high-density lipoprotein (HDL) cholesterol were assayed, and LDL cholesterol was calculated. Participants completed neuropsychological measures of attention, executive function, memory, visuospatial judgment, and manual speed and dexterity. Multiple regression analyses examined cholesterol levels as quadratic predictors of each measure of cognitive performance, with age (dichotomized as <70 vs. 70+) as an effect modifier. A significant quadratic effect of Total Cholesterol² × Age was identified for Logical Memory II ( b = -.0013, p = .039), such that the 70+ group performed best at high and low levels of total cholesterol than at midrange total cholesterol (U-shaped) and the <70 group performed worse at high and low levels of total cholesterol than at midrange total cholesterol (inverted U shape). Similarly, significant U- and J-shaped effects of LDL Cholesterol² × Age were identified for Visual Reproduction II ( b = -.0020, p = .026) and log of the Trail Making Test, Part B (b = .0001, p = .044). Quadratic associations between HDL cholesterol and cognitive performance were nonsignificant. Results indicate differential associations between cholesterol and neuropsychological function across different ages and domains of function. High and low total and LDL cholesterol may confer both risk and benefit for suboptimal cognitive function at different ages. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Rare intracranial cholesterol deposition and a homozygous mutation of LDLR in a familial hypercholesterolemia patient.

PubMed

Li, Haoxian; Zhang, Yanghui; Wei, Xianda; Peng, Ying; Yang, Pu; Tan, Hu; Chen, Chen; Pan, Qian; Liang, Desheng; Wu, Lingqian

2015-09-15

Familial hypercholesterolemia (FH MIM# 143890) is one of the most common autosomal inherited diseases. FH is characterized by elevated plasma levels of total cholesterol and low-density lipoprotein-cholesterol. Mutation in the LDLR gene, which encodes the LDL receptor protein, is responsible for most of the morbidity of FH. The incidence of heterozygous FH is about 1/500, whereas the incidence of homozygous FH is only 1/1,000,000 in Caucasian population. In this study, we report a homozygous LDLR mutation (c.298G>A) in a familial hypercholesterolemia patient, who exhibited intracranial cholesterol deposition, which is a rare addition to the common FH phenotypes. The proband's consanguineous parents have the same heterozygous mutation with elevated concentrations of LDL-C but no xanthoma. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of Aggressive lipid-lowering treatment with Rosuvastatin on vascular endoTHelium function: evaluation of vascular endothelium function (EARTH study).

PubMed

Takayama, Tadateru; Hiro, Takafumi; Yoda, Shunichi; Fukamachi, Daisuke; Haruta, Hironori; Kogo, Takaaki; Mineki, Takashi; Murata, Hironobu; Oshima, Toru; Hirayama, Atsushi

2018-06-01

Vascular endothelial dysfunction plays an important role in the process of atherosclerosis up to the final stage of plaque rupture. Vascular endothelial dysfunction is reversible, and can be recovered by medications and life-style changes. Improvement in endothelial function may reduce cardiovascular events and improve long-term prognosis. A total of 50 patients with stable angina and dyslipidemia were enrolled, including patients who had not received prior treatment with statins and had serum LDL-C levels ≥ 100 mg/dL, and patients who had previously received statin treatment. All agreed to register regardless of their LDL-C level. Rosuvastatin was initially administered at a dose of 2.5 mg and appropriately titrated up to the maximum dose of 20 mg or until LDL-C levels lower than 80 mg/dL were achieved, for 24 weeks. Endothelial function was assessed by the reactive hyperemia peripheral arterial tonometry (RH-PAT) index in the radial artery by Endo-PAT ® 2000 (Endo-PAT ® 2000, software version 3.0.4, Itamar Medical Ltd., Caesarea, Israel). RH-PAT data were digitally analyzed online by Endo-PAT ® 2000 at baseline and at 24 weeks. LDL-C and MDA-LDL-C decreased from 112.6 ± 23.3 to 85.5 ± 20.2 mg/dL and from 135.1 ± 36.4 to 113.9 ± 23.5 mg/dL respectively (p < 0.0001). However, HDL-C, hs-CRP and TG did not change significantly after treatment. RH-PAT index levels significantly improved, from 1.60 ± 0.31 to 1.77 ± 0.57 (p = 0.04) after treatment, and the percent change of the RH-PAT index was 12.8 ± 36.9%. Results of multivariate analysis show that serum LDL-C levels over 24 weeks did not act as a predictor of improvement of the RH-PAT index. However, HbA1c at baseline was an independent predictor which influenced the 24-week RH-PAT index level. The RH-PAT index of patients with high HbA1c at baseline did not improve after administration of rosuvastatin but it did improve in patients with low HbA1c at baseline. Aggressive lowering of LDL-C with rosuvastatin significantly improved the RH-PAT index, suggesting that it may improve endothelial function in patients with coronary artery disease.Clinical Trial Registration No: UMIN-CTR, UMIN000010040.

Impact of Hormonal Contraception and Weight Loss on HDL-C efflux and Lipoprotein Particles in Women with Polycystic Ovary Syndrome

PubMed Central

Dokras, Anuja; Playford, Martin; Kris-Etherton, Penny M.; Kunselman, Allen R.; Stetter, Christy M.; Williams, Nancy I.; Gnatuk, Carol L.; Estes, Stephanie J.; Sarwer, David B; Allison, Kelly C; Coutifaris, Christos; Mehta, Nehal; Legro, Richard S

2017-01-01

Objective To study the effects of oral contraceptive pills (OCP), the first line treatment for PCOS, on HDL-C function (reverse cholesterol efflux capacity) and lipoprotein particles measured by NMR spectroscopy. Design Secondary analysis of a randomized controlled trial (OWL-PCOS) of OCP or Lifestyle (intensive lifestyle modification) or Combined (OCP+Lifestyle) treatment for 16 weeks. Patients 87 overweight/obese women with PCOS at two academic centers Measurements Change in HDL-C efflux capacity and lipoprotein particles. Results HDL-C efflux capacity increased significantly at 16 weeks in the OCP group (0.11; 95% CI 0.03, 0.18, p=0.008) but not in the Lifestyle (p=0.39) or Combined group (p=0.18). After adjusting for HDL-C and TG levels, there was significant mean change in efflux in the Combined group (0.09; 95% CI 0.01, 0.15; p=0.01). Change in HDL-C efflux correlated inversely with change in serum testosterone (rs = −0.21; p=0.05). In contrast, OCP use induced an atherogenic LDL-C profile with increase in small (p=0.006) and large LDL-particles (p=0.002). Change in small LDL-particles correlated with change in serum testosterone (rs = −0.31, p=0.009) and insulin sensitivity index (rs = −0.31, p=0.02). Both Lifestyle and Combined groups did not show significant changes in the atherogenic LDL-particles. Conclusions OCP use is associated with improved HDL-C function and a concomitant atherogenic LDL-C profile. Combination of a Lifestyle program with OCP use improved HDL-C function and mitigated adverse effects of OCP on lipoproteins. Our study provides evidence for use of OCP in overweight/obese women with PCOS when combined with Lifestyle changes. PMID:28199736

Metabolic alterations, HFE gene mutations and atherogenic lipoprotein modifications in patients with primary iron overload.

PubMed

Meroño, Tomás; Brites, Fernando; Dauteuille, Carolane; Lhomme, Marie; Menafra, Martín; Arteaga, Alejandra; Castro, Marcelo; Saez, María Soledad; Ballerga, Esteban González; Sorroche, Patricia; Rey, Jorge; Lesnik, Philippe; Sordá, Juan Andrés; Chapman, M John; Kontush, Anatol; Daruich, Jorge

2015-05-01

Iron overload (IO) has been associated with glucose metabolism alterations and increased risk of cardiovascular disease (CVD). Primary IO is associated with mutations in the HFE gene. To which extent HFE gene mutations and metabolic alterations contribute to the presence of atherogenic lipoprotein modifications in primary IO remains undetermined. The present study aimed to assess small, dense low-density lipoprotein (LDL) levels, chemical composition of LDL and high-density lipoprotein (HDL) particles, and HDL functionality in IO patients. Eighteen male patients with primary IO and 16 sex- and age-matched controls were recruited. HFE mutations (C282Y, H63D and S65C), measures of insulin sensitivity and secretion (calculated from the oral glucose tolerance test), chemical composition and distribution profile of LDL and HDL subfractions (isolated by gradient density ultracentrifugation) and HDL functionality (as cholesterol efflux and antioxidative activity) were studied. IO patients compared with controls exhibited insulin resistance (HOMA-IR (homoeostasis model assessment-estimated insulin resistance): +93%, P< 0.001). Metabolic profiles differed across HFE genotypes. C282Y homozygotes (n=7) presented a reduced β-cell function and insulin secretion compared with non-C282Y patients (n=11) (-58% and -73%, respectively, P< 0.05). In addition, C282Y homozygotes featured a predominance of large, buoyant LDL particles (C282Y: 43±5; non-C282Y: 25±8; controls: 32±7%; P< 0.001), whereas non-C282Y patients presented higher amounts of small, dense LDL (C282Y: 23±5; non-C282Y: 39±10; controls: 26±4%; P< 0.01). HDL particles were altered in C282Y homozygotes. However, HDL functionality was conserved. In conclusion, metabolic alterations and HFE gene mutations are involved in the presence of atherogenic lipoprotein modifications in primary IO. To what extent such alterations could account for an increase in CVD risk remains to be determined.

Activation function 2 (AF2) of estrogen receptor-α is required for the atheroprotective action of estradiol but not to accelerate endothelial healing

PubMed Central

Billon-Galés, Audrey; Krust, Andrée; Fontaine, Coralie; Abot, Anne; Flouriot, Gilles; Toutain, Céline; Berges, Hortense; Gadeau, Alain-Pierre; Lenfant, Françoise; Gourdy, Pierre; Chambon, Pierre; Arnal, Jean-François

2011-01-01

17β-Estradiol (E2) regulates estrogen receptor-α (ERα) target gene transcription through the two independent activation functions (AFs), AF1 and AF2, located in the N-terminal and ligand binding domain of ERα, respectively. We previously reported that ERα is required for the E2 atheroprotective action as well as for its accelerative action on endothelial healing, but its AF1 function is dispensable. Here, we investigated the role of ERαAF2 in these two major beneficial actions of E2 by electively targeting ERαAF2 (named ERαAF20). Our results prove four points. (i) Compared with WT ERα, the ability of ERαAF20 to stimulate the C3 complement or the estrogen response element-thymidine kinase promoter in two cell lines was dramatically decreased, confirming the importance of AF2 in the E2-induced transcriptional activity of ERα. (ii) The uterotrophic action of E2 was totally absent in ERαAF20 mice, showing the crucial role of ERαAF2 in E2-induced uterus hyperplasia. (iii) ERαAF2 was dispensable for the accelerative action of E2 on endothelial healing, underlining the functionality of ERαAF20 in vivo. (iv) Finally, the atheroprotective effect of E2 was abrogated in ERαAF20 LDL-r−/− mice. Thus, whereas ERαAF1 and ERαAF2 are both required for the uterotrophic action of E2, we show that only ERαAF2 is necessary for its atheroprotective effect. PMID:21788522

The small, dense LDL phenotype and the risk of coronary heart disease: epidemiology, patho-physiology and therapeutic aspects.

PubMed

Lamarche, B; Lemieux, I; Després, J P

1999-09-01

More than decade ago, several cross-sectional studies have reported differences in LDL particle size, density and composition between coronary heart disease (CHD) patients and healthy controls. Three recent prospective, nested case-control studies have since confirmed that the presence of small, dense LDL particles was associated with more than a three-fold increase in the risk of CHD. The small, dense LDL phenotype rarely occurs as an isolated disorder. It is most frequently accompanied by hypertriglyceridemia, reduced HDL cholesterol levels, abdominal obesity, insulin resistance and by a series of other metabolic alterations predictive of an impaired endothelial function and increased susceptibility to thrombosis. Whether or not the small, dense LDL phenotype should be considered an independent CHD risk factor remains to be clearly established. The cluster of metabolic abnormalities associated with small, dense LDL particles has been referred to as the insulin resistance-dyslipidemic phenotype of abdominal obesity. Results from the Québec Cardiovascular Study have indicated that individuals displaying three of the numerous features of insulin resistance (elevated plasma insulin and apolipoprotein B concentrations and small, dense LDL particles) showed a remarkable increase in CHD risk. Our data suggest that the increased risk of CHD associated with having small, dense LDL particles may be modulated to a significant extent by the presence/absence of insulin resistance, abdominal obesity and increased LDL particle concentration. We suggest that the complex interactions among the metabolic alterations of the insulin resistance syndrome should be considered when evaluating the risk of CHD associated with the small, dense LDL phenotype. From a therapeutic standpoint, the treatment of this condition should not only aim at reducing plasma triglyceride levels, but also at improving all features of the insulin resistance syndrome, for which body weight loss and mobilization of abdominal fat appear as key elements. Finally, interventions leading to reduction in fasting triglyceride levels will increase LDL particle size and contribute to reduce CHD risk, particularly if plasma apolipoprotein B concentration (as a surrogate of the number of atherogenic particles) is also reduced.

Fatty acid regulates gene expression and growth of human prostate cancer PC-3 cells

NASA Technical Reports Server (NTRS)

Hughes-Fulford, M.; Chen, Y.; Tjandrawinata, R. R.

2001-01-01

It has been proposed that the omega-6 fatty acids increase the rate of tumor growth. Here we test that hypothesis in the PC-3 human prostate tumor. We found that the essential fatty acids, linoleic acid (LA) and arachidonic acid (AA), and the AA metabolite PGE(2) stimulate tumor growth while oleic acid (OA) and the omega-3 fatty acid, eicosapentaenoic acid (EPA) inhibited growth. In examining the role of AA in growth response, we extended our studies to analyze changes in early gene expression induced by AA. We demonstrate that c-fos expression is increased within minutes of addition in a dose-dependent manner. Moreover, the immediate early gene cox-2 is also increased in the presence of AA in a dose-dependent manner, while the constitutive cox-1 message was not increased. Three hours after exposure to AA, the synthesis of PGE(2) via COX-2 was also increased. Previous studies have demonstrated that AA was primarily delivered by low density lipoprotein (LDL) via its receptor (LDLr). Since it is known that hepatomas, acute myelogenous leukemia and colorectal tumors lack normal cholesterol feedback, we examined the role of the LDLr in growth regulation of the PC-3 prostate cancer cells. Analysis of ldlr mRNA expression and LDLr function demonstrated that human PC-3 prostate cancer cells lack normal feedback regulation. While exogenous LDL caused a significant stimulation of cell growth and PGE(2) synthesis, no change was seen in regulation of the LDLr by LDL. Taken together, these data show that normal cholesterol feedback of ldlr message and protein is lost in prostate cancer. These data suggest that unregulated over-expression of LDLr in tumor cells would permit increased availability of AA, which induces immediate early genes c-fos and cox-2 within minutes of uptake.

Fatty acid regulates gene expression and growth of human prostate cancer PC-3 cells.

PubMed

Hughes-Fulford, M; Chen, Y; Tjandrawinata, R R

2001-05-01

It has been proposed that the omega-6 fatty acids increase the rate of tumor growth. Here we test that hypothesis in the PC-3 human prostate tumor. We found that the essential fatty acids, linoleic acid (LA) and arachidonic acid (AA), and the AA metabolite PGE(2) stimulate tumor growth while oleic acid (OA) and the omega-3 fatty acid, eicosapentaenoic acid (EPA) inhibited growth. In examining the role of AA in growth response, we extended our studies to analyze changes in early gene expression induced by AA. We demonstrate that c-fos expression is increased within minutes of addition in a dose-dependent manner. Moreover, the immediate early gene cox-2 is also increased in the presence of AA in a dose-dependent manner, while the constitutive cox-1 message was not increased. Three hours after exposure to AA, the synthesis of PGE(2) via COX-2 was also increased. Previous studies have demonstrated that AA was primarily delivered by low density lipoprotein (LDL) via its receptor (LDLr). Since it is known that hepatomas, acute myelogenous leukemia and colorectal tumors lack normal cholesterol feedback, we examined the role of the LDLr in growth regulation of the PC-3 prostate cancer cells. Analysis of ldlr mRNA expression and LDLr function demonstrated that human PC-3 prostate cancer cells lack normal feedback regulation. While exogenous LDL caused a significant stimulation of cell growth and PGE(2) synthesis, no change was seen in regulation of the LDLr by LDL. Taken together, these data show that normal cholesterol feedback of ldlr message and protein is lost in prostate cancer. These data suggest that unregulated over-expression of LDLr in tumor cells would permit increased availability of AA, which induces immediate early genes c-fos and cox-2 within minutes of uptake.

Zinc deficiency induces vascular pro-inflammatory parameters associated with NF-kappaB and PPAR signaling.

PubMed

Shen, Huiyun; Oesterling, Elizabeth; Stromberg, Arnold; Toborek, Michal; MacDonald, Ruth; Hennig, Bernhard

2008-10-01

Marginal intake of dietary zinc can be associated with increased risk of cardiovascular diseases. In the current study we hypothesized that vascular dysfunction and associated inflammatory events are activated during a zinc deficient state. We tested this hypothesis using both vascular endothelial cells and mice lacking the functional LDL-receptor gene. Zinc deficiency increased oxidative stress and NF-kappaB DNA binding activity, and induced COX-2 and E-selectin gene expression, as well as monocyte adhesion in cultured endothelial cells. The NF-kappaB inhibitor CAPE significantly reduced the zinc deficiency-induced COX-2 expression, suggesting regulation through NF-kappaB signaling. PPAR can inhibit NF-kappaB signaling, and our previous data have shown that PPAR transactivation activity requires adequate zinc. Zinc deficiency down-regulated PPARalpha expression in cultured endothelial cells. Furthermore, the PPARgamma agonist rosiglitazone was unable to inhibit the adhesion of monocytes to endothelial cells during zinc deficiency, an event which could be reversed by zinc supplementation. Our in vivo data support the importance of PPAR dysregulation during zinc deficiency. For example, rosiglitazone induced inflammatory genes (e.g., MCP-1) only during zinc deficiency, and adequate zinc was required for rosiglitazone to down-regulate pro-inflammatory markers such as iNOS. In addition, rosiglitazone increased IkappaBalpha protein expression only in zinc adequate mice. Finally, plasma data from LDL-R-deficient mice suggest an overall pro-inflammatory environment during zinc deficiency and support the concept that zinc is required for proper anti-inflammatory or protective functions of PPAR. These studies suggest that zinc nutrition can markedly modulate mechanisms of the pathology of inflammatory diseases such as atherosclerosis.

Prediction of subtle left ventricular systolic dysfunction in homozygous and heterozygous familial hypercholesterolemia: Genetic analyses and speckle tracking echocardiography study.

PubMed

Saracoglu, Erhan; Kılıç, Salih; Vuruşkan, Ertan; Düzen, Irfan; Çekici, Yusuf; Kuzu, Zülfiye; Yıldırım, Arafat; Küçükosmanoğlu, Mehmet; Çetin, Mustafa

2018-06-05

Few studies have shown the direct effect of familial hypercholesterolemia (FH) on myocardial systolic function. Studies focused on heterozygote FH patients but not homozygote ones, and they did not perform genetic analyses. We aimed to evaluate all types of patients with FH using the potentially more sensitive speckle tracking echocardiography (STE) technique to identify early left ventricular (LV) dysfunction. Genetic analyses of patients with FH were conducted for LDL-receptor, PCSK9, and ApoB100. Nine homozygote, two compound heterozygote, and 82 heterozygote FH patients and 85 healthy subjects were prospectively studied. Longitudinal and circumferential strain measurements and conventional echocardiography findings were obtained. LV ejection fractions were similar for all (homozygote, heterozygote, and control) groups. The LV average longitudinal strain (aLS) and average circumferential strain (aCS) levels were significantly reduced in the homozygote and heterozygote groups when compared with the controls (for aLS, P = .008 (<.001); for aCS, P =< .001). A significant inverse correlation was found between LDL-C levels and LS (P < .001, r = .728) and CS (P < .001, r = .642) for all FH patients. This study demonstrates the potential of using systolic strain values obtained using 2D STE for determining lipotoxicity in the myocardium owing to hypercholesterolemia. Our study found that cardiac functions of homozygote patients who had the highest cholesterol levels were disrupted at very early ages. Therefore, starting lipid reduction treatment and early reverse LV remodelling therapy at early ages may be beneficial for high-risk patients. © 2018 Wiley Periodicals, Inc.

Short-term cooling increases serum triglycerides and small high-density lipoprotein levels in humans.

PubMed

Hoeke, Geerte; Nahon, Kimberly J; Bakker, Leontine E H; Norkauer, Sabine S C; Dinnes, Donna L M; Kockx, Maaike; Lichtenstein, Laeticia; Drettwan, Diana; Reifel-Miller, Anne; Coskun, Tamer; Pagel, Philipp; Romijn, Fred P H T M; Cobbaert, Christa M; Jazet, Ingrid M; Martinez, Laurent O; Kritharides, Leonard; Berbée, Jimmy F P; Boon, Mariëtte R; Rensen, Patrick C N

Cold exposure and β3-adrenergic receptor agonism, which both activate brown adipose tissue, markedly influence lipoprotein metabolism by enhancing lipoprotein lipase-mediated catabolism of triglyceride-rich lipoproteins and increasing plasma high-density lipoprotein (HDL) levels and functionality in mice. However, the effect of short-term cooling on human lipid and lipoprotein metabolism remained largely elusive. The objective was to assess the effect of short-term cooling on the serum lipoprotein profile and HDL functionality in men. Body mass index-matched young, lean men were exposed to a personalized cooling protocol for 2 hours. Before and after cooling, serum samples were collected for analysis of lipids and lipoprotein composition by 1 H-nuclear magnetic resonance. Adenosine triphosphate-binding cassette A1 (ABCA1)-mediated cholesterol efflux capacity of HDL was measured using [ 3 H]cholesterol-loaded ABCA1-transfected Chinese hamster ovary cells. Short-term cooling increased serum levels of free fatty acids, triglycerides, and cholesterol. Cooling increased the concentration of large very low-density lipoprotein (VLDL) particles accompanied by increased mean size of VLDL particles. In addition, cooling enhanced the concentration of small LDL and small HDL particles as well as the cholesterol levels within these particles. The increase in small HDL was accompanied by increased ABCA1-dependent cholesterol efflux in vitro. Our data show that short-term cooling increases the concentration of large VLDL particles and increases the generation of small LDL and HDL particles. We interpret that cooling increases VLDL production and turnover, which results in formation of surface remnants that form small HDL particles that attract cellular cholesterol. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

2017 Taiwan lipid guidelines for high risk patients.

PubMed

Li, Yi-Heng; Ueng, Kwo-Chang; Jeng, Jiann-Shing; Charng, Min-Ji; Lin, Tsung-Hsien; Chien, Kuo-Liong; Wang, Chih-Yuan; Chao, Ting-Hsing; Liu, Ping-Yen; Su, Cheng-Huang; Chien, Shih-Chieh; Liou, Chia-Wei; Tang, Sung-Chun; Lee, Chun-Chuan; Yu, Tse-Ya; Chen, Jaw-Wen; Wu, Chau-Chung; Yeh, Hung-I

2017-04-01

In Taiwan, the prevalence of hyperlipidemia increased due to lifestyle and dietary habit changes. Low density lipoprotein cholesterol (LDL-C) and non-high density lipoprotein cholesterol (non-HDL-C) are all significant predicting factors of coronary artery disease in Taiwan. We recognized that lipid control is especially important in patients with existed atherosclerotic cardiovascular diseases (ASCVD), including coronary artery disease (CAD), ischemic stroke and peripheral arterial disease (PAD). Because the risk of ASCVD is high in patients with diabetes mellitus (DM), chronic kidney disease (CKD) and familial hypercholesterolemia (FH), lipid control is also necessary in these patients. Lifestyle modification is the first step to control lipid. Weight reduction, regular physical exercise and limitation of alcohol intake all reduce triglyceride (TG) levels. Lipid-lowering drugs include HMG-CoA reductase inhibitors (statins), cholesterol absorption inhibitors (ezetimibe), proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, nicotinic acids (niacin), fibric acids derivatives (fibrates), and long-chain omega-3 fatty acids. Statin is usually the first line therapy. Combination therapy with statin and other lipid-lowering agents may be considered in some clinical settings. For patients with acute coronary syndrome (ACS) and stable CAD, LDL-C < 70 mg/dL is the major target. A lower target of LDL-C <55 mg/dL can be considered in ACS patients with DM. After treating LDL-C to target, non-HDL-C can be considered as a secondary target for patients with TG ≥ 200 mg/dL. The suggested non-HDL-C target is < 100 mg/dL in ACS and CAD patients. For patients with ischemic stroke or transient ischemic attack presumed to be of atherosclerotic origin, statin therapy is beneficial and LDL-C < 100 mg/dL is the suggested target. For patients with symptomatic carotid stenosis or intracranial arterial stenosis, in addition to antiplatelets and blood pressure control, LDL-C should be lowered to < 100 mg/dL. Statin is necessary for DM patients with CV disease and the LDL-C target is < 70 mg/dL. For diabetic patients who are ≥ 40 years of age, or who are < 40 years of age but have additional CV risk factors, the LDL-C target should be < 100 mg/dL. After achieving LDL-C target, combination of other lipid-lowering agents with statin is reasonable to attain TG < 150 mg/dL and HDL-C >40 in men and >50 mg/dL in women in DM. LDL-C increased CV risk in patients with CKD. In adults with glomerular filtration rate (GFR) < 60 mL/min/1.73m 2 without chronic dialysis (CKD stage 3-5), statin therapy should be initiated if LDL-C ≥ 100 mg/dL. Ezetimibe can be added to statin to consolidate the CV protection in CKD patients. Mutations in LDL receptor, apolipoprotein B and PCSK9 genes are the common causes of FH. Diagnosis of FH usually depends on family history, clinical history of premature CAD, physical findings of xanthoma or corneal arcus and high levels of LDL-C. In addition to conventional lipid lowering therapies, adjunctive treatment with mipomersen, lomitapide, or PCSK9 inhibitors become necessary to further reduce LDL-C in patients with FH. Overall, these recommendations are to help the health care professionals in Taiwan to treat hyperlipidemia with current scientific evidences. We hope the prescription rate of lipid lowering drugs and control rate of hyperlipidemia in high risk patients could be increased by implementation of the clinical guidelines. The major purpose is to improve clinical outcomes of these high risk patients through the control of hyperlipidemia. Copyright © 2016. Published by Elsevier B.V.

Dietary cholesterol worsens adipose tissue macrophage accumulation and atherosclerosis in obese LDL receptor-deficient mice

PubMed Central

Subramanian, Savitha; Han, Chang Yeop; Chiba, Tsuyoshi; McMillen, Timothy S.; Wang, Shari A.; Haw, Antonio; Kirk, Elizabeth A.; O’Brien, Kevin D.; Chait, Alan

2009-01-01

Objective Chronic systemic inflammation accompanies obesity and predicts development of cardiovascular disease. Dietary cholesterol has been shown to increase inflammation and atherosclerosis in LDL receptor-deficient (LDLR-/-) mice. This study was undertaken to determine whether dietary cholesterol and obesity have additive effects on inflammation and atherosclerosis. Methods and Results LDLR-/- mice were fed chow, high fat, high carbohydrate (diabetogenic) diet without (DD) or with added cholesterol (DDC) for 24 weeks. Effects on adipose tissue, inflammatory markers and atherosclerosis were studied. Despite similar weight gain between DD and DDC groups, addition of dietary cholesterol increased insulin resistance relative to DD. Adipocyte hypertrophy, macrophage accumulation and local inflammation were observed in intra-abdominal adipose tissue in DD and DDC, but were significantly higher in the DDC group. Circulating levels of the inflammatory protein serum amyloid A (SAA) were 4.4-fold higher in DD animals and 15-fold higher in DDC animals than controls, suggesting chronic systemic inflammation. Hepatic SAA mRNA levels were similarly elevated. Atherosclerosis was increased in the DD-fed animals and further increased in the DDC group. Conclusions Obesity-induced macrophage accumulation in adipose tissue is exacerbated by dietary cholesterol. These local inflammatory changes in adipose tissue are associated with insulin resistance, systemic inflammation and increased atherosclerosis in this mouse model. PMID:18239153

Arctigenin promotes cholesterol efflux from THP-1 macrophages through PPAR-γ/LXR-α signaling pathway.

PubMed

Xu, Xiaolin; Li, Qian; Pang, Liewen; Huang, Guoqian; Huang, Jiechun; Shi, Meng; Sun, Xiaotian; Wang, Yiqing

2013-11-15

Cholesterol efflux from macrophages is a critical mechanism to prevent the development of atherosclerosis. Here, we sought to investigate the effects of arctigenin, a bioactive component of Arctium lappa, on the cholesterol efflux in oxidized low-density lipoprotein (oxLDL)-loaded THP-1 macrophages. Our data showed that arctigenin significantly accelerated apolipoprotein A-I- and high-density lipoprotein-induced cholesterol efflux in both dose- and time-dependent manners. Moreover, arctigenin treatment enhanced the expression of ATP binding cassette transporter A1 (ABCA1), ABCG1, and apoE, all of which are key molecules in the initial step of cholesterol efflux, at both mRNA and protein levels. Arctigenin also caused a concentration-dependent elevation in the expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α). The arctigenin-mediated induction of ABCA1, ABCG1, and apoE was abolished by specific inhibition of PPAR-γ or LXR-α using small interfering RNA technology. Our results collectively indicate that arctigenin promotes cholesterol efflux in oxLDL-loaded THP-1 macrophages through upregulation of ABCA1, ABCG1 and apoE, which is dependent on the enhanced expression of PPAR-γ and LXR-α. Copyright © 2013 Elsevier Inc. All rights reserved.

Higher HDL cholesterol is associated with better cognitive function: the Maine-Syracuse study.

PubMed

Crichton, Georgina E; Elias, Merrill F; Davey, Adam; Sullivan, Kevin J; Robbins, Michael A

2014-11-01

Few studies have examined associations between different subcategories of cholesterol and cognitive function. We examined relationships between total cholesterol (TC), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), triglyceride levels and cognitive performance in the Maine-Syracuse Longitudinal Study, a community-based study of cardiovascular risk factors. Cross-sectional analyses were undertaken on data from 540 participants, aged 60 to 98 years, free of dementia and stroke. TC, HDL, LDL, and triglyceride levels were obtained. Cognitive function was assessed using a thorough neuropsychological test battery, including domains of cognitive function indexed by multiple cognitive tests. The cognitive outcomes studied were as follows: Visual-Spatial Memory and Organization, Verbal and Working Memory, Scanning and Tracking, Abstract Reasoning, a Global Composite score, and the Mini-Mental State Examination (MMSE). Significant positive associations were observed between HDL-cholesterol and the Global Composite score, Working Memory, and the MMSE after adjustment for demographic and cardiovascular risk factors. Participants with desirable levels of HDL (≥60 mg/dL) had the highest scores on all cognitive outcomes. There were no significant associations observed between TC, LDL, or triglyceride concentrations and cognition. In older individuals, HDL-cholesterol was related to a composite of Working Memory tests and for general measures of cognitive ability when adjusted for cardiovascular variables. We speculate that persons over 60 are survivors and thus less likely to show cognitive deficit in relation to TC, LDL-cholesterol, and triglycerides. Longitudinal studies are needed to examine relations between specific cognitive abilities and the different subcategories of cholesterol.

Sec34 is implicated in traffic from the endoplasmic reticulum to the Golgi and exists in a complex with GTC-90 and ldlBp.

PubMed

Loh, Eva; Hong, Wanjin

2002-06-14

Sec34p/Grd20p has been implicated in endoplasmic reticulum (ER)-to-Golgi transport and/or post-Golgi trafficking events and exists in a protein complex consisting of at least eight subunits in yeast. Although the mammalian counterpart (Sec34) of Sec34p has been molecularly identified, its role and interacting partners remain undefined. In this study, we have prepared antibodies specifically against the recombinant N-terminal fragment of Sec34 that recognize a polypeptide of about 93 kDa and label the Golgi apparatus. In a well-characterized semi-intact cell assay that reconstitutes transport of the envelope glycoprotein (VSVG) of vesicular stomatitis virus from the ER to the Golgi apparatus, anti-Sec34 antibodies inhibited the transport in a dose-dependent manner. The inhibition by anti-Sec34 antibodies could be neutralized by a noninhibitory amount of the antigen. Large-scale immunoprecipitation of rat liver cytosol with immobilized anti-Sec34 antibodies has co-immunoprecipitated GTC-90 and ldlBp, two peripheral Golgi proteins previously shown to exist in separate protein complexes. Two mammalian homologues (Dor1 and Cod1) of the yeast Sec34 complex were similarly recovered in the Sec34 immunoprecipitates. When expressed in transfected cells, epitope-tagged ldlCp and Cod2 were co-immunoprecipitated with anti-Sec34 antibodies with efficiencies comparable to that observed for tagged ldlBp, Dor1, and Cod1. Direct interactions of Sec34 with ldlBp and ldlCp were further demonstrated in vitro. These results suggest that Sec34, GTC-90, and ldlBp/ldlCp are part of the same protein complex(es) that regulates diverse aspects of Golgi function, including transport from the ER to the Golgi apparatus.

Investigation into the distinct subcellular effects of docosahexaenoic acid loaded low-density lipoprotein nanoparticles in normal and malignant murine liver cells

PubMed Central

Moss, Lacy R.; Mulik, Rohit S.; Van Treuren, Tim; Kim, Soo Young; Corbin, Ian R.

2016-01-01

Background Recent studies have shown that low density lipoproteins reconstituted with the natural omega 3 fatty acid docosahexaenoic acid (LDL-DHA) is selectively cytotoxic to liver cancer cells over normal hepatocytes. To date, little is known about the subcellular events which transpire following LDL-DHA treatment. Methods Herein, murine noncancer and cancer liver cells, TIB-73 and TIB-75 respectively, were investigated utilizing confocal microscopy, flow cytometry and viability assays to demonstrate differential actions of LDL-DHA nanoparticles in normal versus malignant cells. Results Our studies first showed that basal levels of oxidative stress are significantly higher in the malignant TIB-75 cells compared to the normal TIB-73 cells. As such, upon entry of LDL-DHA into the malignant TIB-75 cells, DHA is rapidly oxidized precipitating global and lysosomal lipid peroxidation along with increased lysosomal permeability. This leakage of lysosomal contents and lipid peroxidation products trigger subsequent mitochondrial dysfunction and nuclear injury. The cascade of LDL-DHA mediated lipid peroxidation and organelle damage was partially reversed by the administration of the antioxidant, N-acetylcysteine, or the iron-chelator, deferoxamine. LDL-DHA treatment in the normal TIB-73 cells was well tolerated and did not elicit any cell or organelle injury. Conclusion These studies have shown that LDL-DHA is selectively cytotoxic to liver cancer cells and that increased levels of ROS and iron catalyzed reactions promote the peroxidation of DHA which lead to organelle dysfunction and ultimately the demise of the cancer cell. General significance LDL-DHA selectively disrupts lysosomal, mitochondrial and nuclear function in cancer cells as a novel pathway for eliminating cancer cells. PMID:27418237

Interaction of human low density lipoprotein and apolipoprotein B with ternary lipid microemulsion. Physical and functional properties.

PubMed

Chun, P W; Brumbaugh, E E; Shiremann, R B

1986-12-31

Based on data from sedimentation velocity experiments, electrophoresis, electron microscopy, cellular uptake studies, scanning molecular sieve chromatography using a quasi-three-dimensional data display and flow performance liquid chromatography (FPLC), models for the interaction of human serum low density lipoprotein (LDL) and of apolipoprotein B (apo B) with a ternary lipid microemulsion (ME) are proposed. The initial step in the interaction of LDL (Stokes radius 110 A) with the ternary microemulsion (Stokes radius 270 A) appears to be attachment of the LDL to emulsion particles. This attachment is followed by a very slow fusion into particles having a radius of approx. 280 A. Sonication of this mixture yields large aggregates. Electron micrographs of deoxycholate-solubilized apo B indicate an arrangement of apo B resembling strings of beads. During incubation, these particles also attach to the ternary microemulsion particles and, upon sonication, spherical particles result which resemble native LDL particles in size. Scanning chromatography corroborates the electron microscopy results. By appropriate choice of display angles in a quasi-three-dimensional display of the scanning data (corrected for gel apparent absorbance) taken at equal time intervals during passage of a sample through the column, changes in molecular radius of less than 10 A can be detected visually. Such a display gives a quantitative estimate of 101 +/- 2 A for these particles (compared to 110 A for native LDL). The LDL-ME particles and apo B-ME particles compete efficiently with native LDL for cellular binding and uptake. Cellular association studies indicate that both LDL- and apo B-ME particles are effective vehicles for lipid delivery into cells.

Mice Fed a High-Cholesterol Diet Supplemented with Quercetin-3-Glucoside Show Attenuated Hyperlipidemia and Hyperinsulinemia Associated with Differential Regulation of PCSK9 and LDLR in their Liver and Pancreas.

PubMed

Mbikay, Majambu; Mayne, Janice; Sirois, Francine; Fedoryak, Olesya; Raymond, Angela; Noad, Jennifer; Chrétien, Michel

2018-05-01

Hepatic LDL receptor (LDLR) and proprotein convertase subtilisin/kexin type 9 (PCSK9) regulate the clearance of plasma LDL-cholesterol (LDL-C): LDLR promotes it, and PCSK9 opposes it. These proteins also express in pancreatic β cells. Using cultured hepatocytes, we previously showed that the plant flavonoid quercetin-3-glucoside (Q3G) inhibits PCSK9 secretion, stimulated LDLR expression, and enhanced LDL-C uptake. Here, we examine whether Q3G supplementation could reverse the hyperlipidemia and hyperinsulinemia of mice fed a high-cholesterol diet, and how it affects hepatic and pancreatic LDLR and PCSK9 expression. For 12 weeks, mice are fed a low- (0%) or high- (1%) cholesterol diet (LCD or HCD), supplemented or not with Q3G at 0.05 or 0.1% (w/w). Tissue LDLR and PCSK9 is analyzed by immunoblotting, plasma PCSK9 and insulin by ELISA, and plasma cholesterol and glucose by colorimetry. In LCD-fed mice, Q3G has no effect. In HCD-fed mice, it attenuates the increase in plasma cholesterol and insulin, accentuates the decrease in plasma PCSK9, and increases hepatic and pancreatic LDLR and PCSK9. In cultured pancreatic β cells, however, it stimulates PCSK9 secretion. In mice, dietary Q3G could counter HCD-induced hyperlipidemia and hyperinsulinemia, in part by oppositely modulating hepatic and pancreatic PCSK9 secretion. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Three-dimensional cryoEM reconstruction of native LDL particles to 16Å resolution at physiological body temperature.

PubMed

Kumar, Vibhor; Butcher, Sarah J; Öörni, Katariina; Engelhardt, Peter; Heikkonen, Jukka; Kaski, Kimmo; Ala-Korpela, Mika; Kovanen, Petri T

2011-05-09

Low-density lipoprotein (LDL) particles, the major carriers of cholesterol in the human circulation, have a key role in cholesterol physiology and in the development of atherosclerosis. The most prominent structural components in LDL are the core-forming cholesteryl esters (CE) and the particle-encircling single copy of a huge, non-exchangeable protein, the apolipoprotein B-100 (apoB-100). The shape of native LDL particles and the conformation of native apoB-100 on the particles remain incompletely characterized at the physiological human body temperature (37 °C). To study native LDL particles, we applied cryo-electron microscopy to calculate 3D reconstructions of LDL particles in their hydrated state. Images of the particles vitrified at 6 °C and 37 °C resulted in reconstructions at ~16 Å resolution at both temperatures. 3D variance map analysis revealed rigid and flexible domains of lipids and apoB-100 at both temperatures. The reconstructions showed less variability at 6 °C than at 37 °C, which reflected increased order of the core CE molecules, rather than decreased mobility of the apoB-100. Compact molecular packing of the core and order in a lipid-binding domain of apoB-100 were observed at 6 °C, but not at 37 °C. At 37 °C we were able to highlight features in the LDL particles that are not clearly separable in 3D maps at 6 °C. Segmentation of apoB-100 density, fitting of lipovitellin X-ray structure, and antibody mapping, jointly revealed the approximate locations of the individual domains of apoB-100 on the surface of native LDL particles. Our study provides molecular background for further understanding of the link between structure and function of native LDL particles at physiological body temperature.

Bergamot polyphenolic fraction enhances rosuvastatin-induced effect on LDL-cholesterol, LOX-1 expression and protein kinase B phosphorylation in patients with hyperlipidemia.

PubMed

Gliozzi, Micaela; Walker, Ross; Muscoli, Saverio; Vitale, Cristiana; Gratteri, Santo; Carresi, Cristina; Musolino, Vincenzo; Russo, Vanessa; Janda, Elzbieta; Ragusa, Salvatore; Aloe, Antonio; Palma, Ernesto; Muscoli, Carolina; Romeo, Franco; Mollace, Vincenzo

2013-12-10

Statins are the most commonly prescribed drugs to reduce cardiometabolic risk. Besides the well-known efficacy of such compounds in both preventing and treating cardiometabolic disorders, some patients experience statin-induced side effects. We hypothesize that the use of natural bergamot-derived polyphenols may allow patients undergoing statin treatment to reduce effective doses while achieving target lipid values. The aim of the present study is to investigate the occurrence of an enhanced effect of bergamot-derived polyphenolic fraction (BPF) on rosuvastatin-induced hypolipidemic and vasoprotective response in patients with mixed hyperlipidemia. A prospective, open-label, parallel group, placebo-controlled study on 77 patients with elevated serum LDL-C and triglycerides was designed. Patients were randomly assigned to a control group receiving placebo (n=15), two groups receiving orally administered rosuvastatin (10 and 20mg/daily for 30 days; n=16 for each group), a group receiving BPF alone orally (1000 mg/daily for 30 days; n=15) and a group receiving BPF (1000 mg/daily given orally) plus rosuvastatin (10mg/daily for 30 days; n=15). Both doses of rosuvastatin and BPF reduced total cholesterol, LDL-C, the LDL-C/HDL-C ratio and urinary mevalonate in hyperlipidemic patients, compared to control group. The cholesterol lowering effect was accompanied by reductions of malondialdehyde, oxyLDL receptor LOX-1 and phosphoPKB, which are all biomarkers of oxidative vascular damage, in peripheral polymorphonuclear cells. Addition of BPF to rosuvastatin significantly enhanced rosuvastatin-induced effect on serum lipemic profile compared to rosuvastatin alone. This lipid-lowering effect was associated with significant reductions of biomarkers used for detecting oxidative vascular damage, suggesting a multi-action enhanced potential for BPF in patients on statin therapy. © 2013. Published by Elsevier Ireland Ltd. All rights reserved.

Omega-3 fatty acids attenuate constitutive and insulin-induced CD36 expression through a suppression of PPAR α/γ activity in microvascular endothelial cells.

PubMed

Madonna, Rosalinda; Salerni, Sara; Schiavone, Deborah; Glatz, Jan F; Geng, Yong-Jian; De Caterina, Raffaele

2011-09-01

Microvascular dysfunction occurs in insulin resistance and/or hyperinsulinaemia. Enhanced uptake of free fatty acids (FFA) and oxidised low-density lipoproteins (oxLDL) may lead to oxidative stress and microvascular dysfunction interacting with CD36, a PPARα/γ-regulated scavenger receptor and long-chain FFA transporter. We investigated CD36 expression and CD36-mediated oxLDL uptake before and after insulin treatment in human dermal microvascular endothelial cells (HMVECs), ± different types of fatty acids (FA), including palmitic, oleic, linoleic, arachidonic, eicosapentaenoic (EPA), and docosahexaenoic (DHA) acids. Insulin (10(-8) and 10(-7) M) time-dependently increased DiI-oxLDL uptake and CD36 surface expression (by 30 ± 13%, p<0.05 vs. untreated control after 24 hours incubation), as assessed by ELISA and flow cytometry, an effect that was potentiated by the PI3-kinase inhibitor wortmannin and reverted by the ERK1/2 inhibitor PD98059 and the PPARα/γ antagonist GW9662. A ≥ 24 hour exposure to 50 μM DHA or EPA, but not other FA, blunted both the constitutive (by 23 ± 3% and 29 ± 2%, respectively, p<0.05 for both) and insulin-induced CD36 expressions (by 45 ± 27 % and 12 ± 3 %, respectively, p<0.05 for both), along with insulin-induced uptake of DiI-oxLDL and the downregulation of phosphorylated endothelial nitric oxide synthase (P-eNOS). At gel shift assays, DHA reverted insulin-induced basal and oxLDL-stimulated transactivation of PPRE and DNA binding of PPARα/γ and NF-κB. In conclusion, omega-3 fatty acids blunt the increased CD36 expression and activity promoted by high concentrations of insulin. Such mechanisms may be the basis for the use of omega-3 fatty acids in diabetic microvasculopathy.

Oxidized low-density lipoprotein and β-glycerophosphate synergistically induce endothelial progenitor cell ossification

PubMed Central

Liu, Li; Liu, Zhi-zhong; Chen, Hui; Zhang, Guo-jun; Kong, Yu-hua; Kang, Xi-xiong

2011-01-01

Aim: To investigate the ability of ox-LDL to induce ossification of endothelial progenitor cells (EPCs) in vitro and explored whether oxidative stress, especially hypoxia inducible factor-1α (HIF-1α) and reactive oxygen species (ROS), participate in the ossific process. Methods: Rat bone marrow-derived endothelial progenitor cells (BMEPCs) were cultured in endothelial growth medium supplemented with VEGF (40 ng/mL) and bFGF (10 ng/mL). The cells were treated with oxidized low-density lipoprotein (ox-LDL, 5 μg/mL) and/or β-glycerophosphate (β-GP, 10 mmol/L). Calcium content and Von Kossa staining were used as the measures of calcium deposition. Ossific gene expression was determined using RT-PCR. The expression of osteocalcin (OCN) was detected with immunofluorescence. Alkaline phosphatase (ALP) activity was analyzed using colorimetric assay. Intercellular reactive oxygen species (ROS) were measured with flow cytometry. Results: BMEPCs exhibited a spindle-like shape. The percentage of cells that expressed the cell markers of EPCs CD34, CD133 and kinase insert domain-containing receptor (KDR) were 46.2%±5.8%, 23.5%±4.0% and 74.3%±8.8%, respectively. Among the total cells, 78.3%±4.2% were stained with endothelial-specific fluorescence. Treatment of BMEPCs with ox-LDL significantly promoted calcium deposition, which was further significantly enhanced by co-treatment with β-GP. The same treatments significantly increased the gene expression of core-binding factor a-1 (cbfa-1) and OCN, while decreased the gene expression of osteoprotegerin (OPG). The treatments also significantly enhanced the activity of ALP, but did not affect the number of OCN+ cells. Furthermore, the treatments significantly increased ROS and activated the hypoxia inducible factor-1α (HIF-1α). In all these effects, ox-LDL acted synergistically with β-GP. Conclusion: Ox-LDL and β-GP synergistically induce ossification of BMEPCs, in which an oxidizing mechanism is involved. PMID:22036865

Oxidized low-density lipoprotein and β-glycerophosphate synergistically induce endothelial progenitor cell ossification.

PubMed

Liu, Li; Liu, Zhi-zhong; Chen, Hui; Zhang, Guo-jun; Kong, Yu-hua; Kang, Xi-xiong

2011-12-01

To investigate the ability of ox-LDL to induce ossification of endothelial progenitor cells (EPCs) in vitro and explored whether oxidative stress, especially hypoxia inducible factor-1α (HIF-1α) and reactive oxygen species (ROS), participate in the ossific process. Rat bone marrow-derived endothelial progenitor cells (BMEPCs) were cultured in endothelial growth medium supplemented with VEGF (40 ng/mL) and bFGF (10 ng/mL). The cells were treated with oxidized low-density lipoprotein (ox-LDL, 5 μg/mL) and/or β-glycerophosphate (β-GP, 10 mmol/L). Calcium content and Von Kossa staining were used as the measures of calcium deposition. Ossific gene expression was determined using RT-PCR. The expression of osteocalcin (OCN) was detected with immunofluorescence. Alkaline phosphatase (ALP) activity was analyzed using colorimetric assay. Intercellular reactive oxygen species (ROS) were measured with flow cytometry. BMEPCs exhibited a spindle-like shape. The percentage of cells that expressed the cell markers of EPCs CD34, CD133 and kinase insert domain-containing receptor (KDR) were 46.2%±5.8%, 23.5%±4.0% and 74.3%±8.8%, respectively. Among the total cells, 78.3%±4.2% were stained with endothelial-specific fluorescence. Treatment of BMEPCs with ox-LDL significantly promoted calcium deposition, which was further significantly enhanced by co-treatment with β-GP. The same treatments significantly increased the gene expression of core-binding factor a-1 (cbfa-1) and OCN, while decreased the gene expression of osteoprotegerin (OPG). The treatments also significantly enhanced the activity of ALP, but did not affect the number of OCN(+) cells. Furthermore, the treatments significantly increased ROS and activated the hypoxia inducible factor-1α (HIF-1α). In all these effects, ox-LDL acted synergistically with β-GP. Ox-LDL and β-GP synergistically induce ossification of BMEPCs, in which an oxidizing mechanism is involved.

Low Density Lipoproteins Promote Unstable Calcium Handling Accompanied by Reduced SERCA2 and Connexin-40 Expression in Cardiomyocytes

PubMed Central

Cabello, Nuria; Llach, Anna; Vallmitjana, Alexander; Benítez, Raúl; Badimon, Lina; Cinca, Juan; Llorente-Cortés, Vicenta; Hove-Madsen, Leif

2013-01-01

The damaging effects of high plasma levels of cholesterol in the cardiovascular system are widely known, but little attention has been paid to direct effects on cardiomyocyte function. We therefore aimed at testing the hypothesis that Low Density Lipoprotein (LDL) cholesterol affects calcium dynamics and signal propagation in cultured atrial myocytes. For this purpose, mRNA and protein expression levels were determined by real time PCR and western blot analysis, respectively, and intracellular calcium was visualized in fluo-4 loaded atrial HL-1 myocyte cultures subjected to field stimulation. At low stimulation frequencies all cultures had uniform calcium transients at all tested LDL concentrations. However, 500 µg LDL/mL maximally reduced the calcium transient amplitude by 43% from 0.30±0.04 to 0.17±0.02 (p<0.05). Moreover, LDL-cholesterol dose-dependently increased the fraction of alternating and irregular beat-to-beat responses observed when the stimulation interval was shortened. This effect was linked to a concurrent reduction in SERCA2, RyR2, IP3RI and IP3RII mRNA levels. SERCA2 protein levels were also reduced by 43% at 200 µg LDL/mL (p<0.05) and SR calcium loading was reduced by 38±6% (p<0.001). By contrast, HDL-cholesterol had no significant effect on SERCA expression or SR calcium loading. LDL-cholesterol also slowed the conduction velocity of the calcium signal from 3.2+0.2 mm/s without LDL to 1.7±0.1 mm/s with 500 µg LDL/mL (p<0.05). This coincided with a reduction in Cx40 expression (by 44±3%; p<0.05 for mRNA and by 79±2%; p<0.05 for Cx40 protein at 200 µg/ml LDL) whereas the Cx-43 expression did not significantly change. In conclusion, LDL-cholesterol destabilizes calcium handling in cultured atrial myocytes subjected to rapid pacing by reducing SERCA2 and Cx40 expression and by slowing the conduction velocity of the calcium signal. PMID:23516438

Hypocholesterolemia is an independent risk factor for depression disorder and suicide attempt in Northern Mexican population.

PubMed

Segoviano-Mendoza, Marcela; Cárdenas-de la Cruz, Manuel; Salas-Pacheco, José; Vázquez-Alaniz, Fernando; La Llave-León, Osmel; Castellanos-Juárez, Francisco; Méndez-Hernández, Jazmín; Barraza-Salas, Marcelo; Miranda-Morales, Ernesto; Arias-Carrión, Oscar; Méndez-Hernández, Edna

2018-01-15

Cholesterol has been associated as a risk factor for cardiovascular disease. Recently, however, there is growing evidence about crucial requirement of neuron membrane cholesterol in the organization and function of the 5-HT 1A serotonin receptor. For this, low cholesterol level has been reported to be associated with depression and suicidality. However there have been inconsistent reports about this finding and the exact relationship between these factors remains controversial. Therefore, we investigated the link between serum cholesterol and its fractions with depression disorder and suicide attempt in 467 adult subjects in Mexican mestizo population. Plasma levels of total cholesterol, triglycerides, and high-density lipoprotein cholesterol (HDL-c) and low density lipoprotein cholesterol (LDL-c) were determined in 261 MDD patients meeting the DSM-5 criteria for major depressive disorder (MDD), 59 of whom had undergone an episode of suicide attempt, and 206 healthy controls. A significant decrease in total cholesterol, LDL-cholesterol, VLDL-cholesterol and triglyceride serum levels was observed in the groups of MDD patients and suicide attempt compared to those without suicidal behavior (p < 0.05). After adjusting for covariates, lower cholesterol levels were significantly associated with MDD (OR 4.229 CI 95% 2.555 - 7.000, p<.001) and suicide attempt (OR 5.540 CI 95% 2.825 - 10.866, p<.001) CONCLUSIONS: These results support the hypothesis that lower levels of cholesterol are associated with mood disorders like MDD and suicidal behavior. More mechanistic studies are needed to further explain this association.

LDLR promoter variant and exon 14 mutation on the same chromosome are associated with an unusually severe FH phenotype and treatment resistance

PubMed Central

Snozek, Christine LH; Lagerstedt, Susan A; Khoo, Teck K; Rubenfire, Melvyn; Isley, William L; Train, Laura J; Baudhuin, Linnea M

2009-01-01

Familial hypercholesterolemia (FH) is the most common form of autosomal-dominant hypercholesterolemia, and is caused by mutations in the low-density lipoprotein receptor (LDLR) gene. Heterozygous FH is characterized by elevated low-density lipoprotein (LDL) cholesterol and early-onset cardiovascular disease, whereas homozygous FH results in more severe LDL cholesterol elevation with death by 20 years of age. We present here the case of an African-American female FH patient presenting with a myocardial infarction at the age of 48, recurrent angina pectoris and numerous coronary artery stents. Her pretreated LDL cholesterol levels were more typical of a homozygous FH pattern and she was resistant to conventional lipid-lowering treatment, yet her other clinical parameters were not necessarily consistent with homozygous FH. Genetic testing revealed two LDLR variants on the same chromosome: one a novel missense mutation in exon 14 (Cys681Gly) and the other a promoter variant (IVS1-217C>T) previously shown to result in increased LDLR transcription. Disease-associated PCSK9 or APOB mutations were not identified in this individual. Overall, her genetic and clinical profile suggests that enhanced expression of the mutant LDLR allele resulted in a severe phenotype with characteristics of both heterozygous and homozygous FH. PMID:18648394

Clusterin/ApoJ enhances central leptin signaling through Lrp2-mediated endocytosis.

PubMed

Byun, Kyunghee; Gil, So Young; Namkoong, Churl; Youn, Byung-Soo; Huang, Hu; Shin, Mi-Seon; Kang, Gil Myoung; Kim, Hyun-Kyong; Lee, Bonghee; Kim, Young-Bum; Kim, Min-Seon

2014-07-01

Hypothalamic leptin signaling plays a central role in maintaining body weight homeostasis. Here, we show that clusterin/ApoJ, recently identified as an anorexigenic neuropeptide, is an important regulator in the hypothalamic leptin signaling pathway. Coadministration of clusterin potentiates the anorexigenic effect of leptin and boosts leptin-induced hypothalamic Stat3 activation. In cultured neurons, clusterin enhances receptor binding and subsequent endocytosis of leptin. These effects are mainly mediated through the LDL receptor-related protein-2 (Lrp2). Notably, inhibition of hypothalamic clusterin, Lrp2 or endocytosis abrogates anorexia and hypothalamic Stat3 activation caused by leptin. These findings propose a novel regulatory mechanism in central leptin signaling pathways. © 2014 The Authors.

Uptake of acetaldehyde-modified (ethylated) low-density lipoproteins by mouse peritoneal macrophages.

PubMed

Wehr, Hanna; Mirkiewicz, Ewa; Rodo, Maria; Bednarska-Makaruk, Malgorzata

2002-04-01

The uptake of acetaldehyde-modified (ethylated) low-density lipoproteins (LDLs) by murine peritoneal macrophages is described and compared with the uptake of acetylated LDLs. The fluorescent marker DiI was used. No competition between ethylated and acetylated LDLs was observed. Ethylated LDL uptake was not inhibited by polyinosinic acid or fucoidin. Our conclusion is that uptake of ethylated and acetylated LDLs can be done by two different receptors.

The Association between KIF6 Single Nucleotide Polymorphism rs20455 and Serum Lipids in Filipino-American Women

PubMed Central

Ancheta, Irma B.; Battie, Cynthia A.; Ancheta, Christine V.; Volgman, Annabelle S.; Conley, Yvette

2014-01-01

The Trp719Arg allele of KIF6 rs20455, a putative risk factor for CHD especially in those with elevated low-density lipoprotein cholesterol (LDL-C), was investigated in Filipino-American women (FAW, n = 235) participating in health screenings in four cities. The rs20455 genotype of each subject was determined by a multiplex assay using a Luminex-OLA procedure. The risk allele Trp719Arg was present in 77% of the subjects. The genotype distribution was 23% Trp/Trp, 51% Arg/Trp, and 26% Arg/Arg. Genotype did not predict the presence of CHD risk factors. Moreover, LDL-C, HDL-C, and triglycerides mean values did not vary as a function of genotype. However, those with the Arg/Arg genotype on statin medication exhibited a significantly higher mean triglycerides level (P < 0.01). Approximately 60% of participants regardless of genotype exhibited LDL-C levels ≥100 mg/dL but were not taking medication. Approximately 43% of those with the Trp719Arg risk allele on statins exhibited elevated LDL-C levels. Our study suggests that the Trp719Arg allele of KIF 6 rs20455 is common among Filipino-American women; thus, even with borderline LDL-C levels would benefit from statin treatment. Secondly, many participants did not exhibit guideline recommended LDL-C levels including many who were on statin drugs. PMID:24587901

OxLDL enhances L-type Ca2+ currents via lysophosphatidylcholine-induced mitochondrial reactive oxygen species (ROS) production.

PubMed

Fearon, Ian M

2006-03-01

To examine the mechanisms underlying oxidised LDL- (oxLDL)-induced alterations in Ca(2+) currents, an effect which underlies altered vascular contractility and cardiac myocyte function. Ca(2+) currents (I(Ca)) were recorded by whole-cell patch-clamp in HEK293 cells expressing L-type Ca(2+) channel alpha(1C) subunits or isolated rat ventricular myocytes. oxLDL (but not native LDL) significantly enhanced recombinant I(Ca), an effect mimicked by 1 microM lysophosphatidylcholine (LPC). LPC failed to enhance I(Ca) either in mitochondrial electron transport chain-depleted rho(0) cells, or in the presence of rotenone (1 microM), or MPP(+) (10 microM). The LPC response was similarly ablated by ascorbate (200 microM) or TROLOX (500 microM) and by the mitochondria-targeted antioxidant, MitoQ (250 nM). In myocytes, enhancement of I(Ca) due to LPC was similarly abrogated with rotenone and MitoQ. These data suggest that LPC enhanced recombinant Ca(2+) currents due to increased mitochondrial ROS production. In support with this, LPC enhanced fluorescence in HEK293 cells and cardiac myocytes loaded with a ROS-sensitive mitochondrial dye, reduced mitotracker red. LPC up-regulates L-type Ca(2+) currents due to altered mitochondrial ROS production, an effect which mediates the response of the native I(Ca) in cardiac myocytes to oxLDL.

Usefulness of anti-oxidized LDL antibody determination for assessment of clinical control in patients with heart failure.

PubMed

George, Jacob; Wexler, Dov; Roth, Arie; Barak, Tomer; Sheps, David; Keren, Gad

2006-01-01

It has been suggested that oxidative stress may play a role in the pathogenesis of heart failure, this may have potential implications for therapeutic strategies. However, measures of oxidative stress are subject to confounding inaccuracies. IgG antibodies to oxidized LDL reflect exposure to the lipoprotein over an extended period and may thus mirror oxidative stress over a prolonged time frame. Therefore, we tested the hypothesis that anti-oxLDL antibodies correlate with the control of heart failure (HF), as manifested by hospital admissions for cardiac dysfunction. One hundred and two consecutive patients attending the HF clinic with either systolic or diastolic HF were enrolled and the quality of clinical control was evaluated by assessing hospital admissions over the year prior to index determination of the oxidative stress marker. Antibodies to oxLDL were determined by ELISA and pro-BNP levels were also measured. Most patients (mean age 71.5 years) had systolic HF; mean NYHA functional class was 2.7 and mean left ventricular ejection fraction was 39.7%. Anti-oxLDL antibodies, but not pro-BNP, correlated significantly with mean NYHA score (averaged from all clinic visits in the year prior to blood testing), and with hospital admissions over the year prior to blood testing. Mean IgG anti-oxLDL antibody levels in patients with hospital admissions were 3.4 times higher than those in subjects not hospitalized over the previous year. IgG anti-oxLDL antibody levels correlate with the severity of HF.

Ceruloplasmin and cardiovascular disease

NASA Technical Reports Server (NTRS)

Fox, P. L.; Mazumder, B.; Ehrenwald, E.; Mukhopadhyay, C. K.

2000-01-01

Transition metal ion-mediated oxidation is a commonly used model system for studies of the chemical, structural, and functional modifications of low-density lipoprotein (LDL). The physiological relevance of studies using free metal ions is unclear and has led to an exploration of free metal ion-independent mechanisms of oxidation. We and others have investigated the role of human ceruloplasmin (Cp) in oxidative processes because it the principal copper-containing protein in serum. There is an abundance of epidemiological data that suggests that serum Cp may be an important risk factor predicting myocardial infarction and cardiovascular disease. Biochemical studies have shown that Cp is a potent catalyst of LDL oxidation in vitro. The pro-oxidant activity of Cp requires an intact structure, and a single copper atom at the surface of the protein, near His(426), is required for LDL oxidation. Under conditions where inhibitory protein (such as albumin) is present, LDL oxidation by Cp is optimal in the presence of superoxide, which reduces the surface copper atom of Cp. Cultured vascular endothelial and smooth muscle cells also oxidize LDL in the presence of Cp. Superoxide release by these cells is a critical factor regulating the rate of oxidation. Cultured monocytic cells, when activated by zymosan, can oxidize LDL, but these cells are unique in their secretion of Cp. Inhibitor studies using Cp-specific antibodies and antisense oligonucleotides show that Cp is a major contributor to LDL oxidation by these cells. The role of Cp in lipoprotein oxidation and atherosclerotic lesion progression in vivo has not been directly assessed and is an important area for future studies.

Lipid profiles in the untreated patients with Hashimoto thyroiditis and the effects of thyroxine treatment on subclinical hypothyroidism with Hashimoto thyroiditis.

PubMed

Tagami, Tetsuya; Tamanaha, Tamiko; Shimazu, Satoko; Honda, Kyoko; Nanba, Kazutaka; Nomura, Hidenari; Yoriko, Sakane Ueda; Usui, Takeshi; Shimatsu, Akira; Naruse, Mitsuhide

2010-01-01

To evaluate the prevalence of dyslipidemia in the population of Hashimoto thyroiditis, we reviewed medical records on the consecutive 1181 cases with adult Hashimoto thyroiditis and 830 cases were adopted for the study. First, the serum TSH level increased and serum free T4 level decreased, slightly but significantly, with increasing age. There were significant positive correlations between serum TSH levels and lipid parameters such as total cholesterol (TC), triglyceride (TG), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), non-HDL-C and LDL-C/HDL-C ratio (L/H). In contrast, there were significant negative correlations between serum free T4 levels and all of these lipid parameters. According to the thyroid function, the cases were classified into 4 groups such as thyrotoxicosis (TT), euthyroidism (EU), subclinical hypothyroidism (SH) and overt hypothyroidism (OH). TC, HDL-C, non-HDL-C and LDL-C of TT were significantly lower than those in EU. In contrast, TC, TG, non-HDL-C, LDL-C, L/H and age of OH were significantly higher than those in EU. Interestingly, LDL-C and L/H of SH were significantly higher compared with EU. Thirty-two of SH patients were treated with small doses of levothyroxine and the effects on the lipid profile were examined. The TC, non-HDL-C, LDL-C and L/H were significantly decreased after treatment. In conclusion, the prevalence of dyslipidemia increases along with hypofunction of the thyroid and T4 replacement therapy may improve lipid profile in the cases of SH with Hashimoto thyroiditis.

Structure-function relationships in reconstituted HDL: Focus on antioxidative activity and cholesterol efflux capacity.

PubMed

Cukier, Alexandre M O; Therond, Patrice; Didichenko, Svetlana A; Guillas, Isabelle; Chapman, M John; Wright, Samuel D; Kontush, Anatol

2017-09-01

High-density lipoprotein (HDL) contains multiple components that endow it with biological activities. Apolipoprotein A-I (apoA-I) and surface phospholipids contribute to these activities; however, structure-function relationships in HDL particles remain incompletely characterised. Reconstituted HDLs (rHDLs) were prepared from apoA-I and soy phosphatidylcholine (PC) at molar ratios of 1:50, 1:100 and 1:150. Oxidative status of apoA-I was varied using controlled oxidation of Met112 residue. HDL-mediated inactivation of PC hydroperoxides (PCOOH) derived from mildly pre-oxidized low-density lipoprotein (LDL) was evaluated by HPLC with chemiluminescent detection in HDL+LDL mixtures and re-isolated LDL. Cellular cholesterol efflux was characterised in RAW264.7 macrophages. rHDL inactivated LDL-derived PCOOH in a dose- and time-dependent manner. The capacity of rHDL to both inactivate PCOOH and efflux cholesterol via ATP-binding cassette transporter A1 (ABCA1) increased with increasing apoA-I/PC ratio proportionally to the apoA-I content in rHDL. Controlled oxidation of apoA-I Met112 gradually decreased PCOOH-inactivating capacity of rHDL but increased ABCA1-mediated cellular cholesterol efflux. Increasing apoA-I content in rHDL enhanced its antioxidative activity towards oxidized LDL and cholesterol efflux capacity via ABCA1, whereas oxidation of apoA-I Met112 decreased the antioxidative activity but increased the cholesterol efflux. These findings provide important considerations in the design of future HDL therapeutics. Non-standard abbreviations and acronyms: AAPH, 2,2'-azobis(-amidinopropane) dihydrochloride; ABCA1, ATP-binding cassette transporter A1; apoA-I, apolipoprotein A-I; BHT, butylated hydroxytoluene; CV, cardiovascular; EDTA, ethylenediaminetetraacetic acid; HDL-C, high-density lipoprotein cholesterol; LOOH, lipid hydroperoxides; Met(O), methionine sulfoxide; Met112, methionine 112 residue; Met86, methionine 86 residue; oxLDL, oxidized low-density lipoprotein; PBS, phosphate-buffered saline; PC, phosphatidylcholine; PL, phospholipid; PCOOH, phosphatidylcholine hydroperoxide; PLOOH, phospholipid hydroperoxide. Copyright © 2017 Elsevier B.V. All rights reserved.

Decursin inhibits vasculogenesis in early tumor progression by suppression of endothelial progenitor cell differentiation and function.

PubMed

Jung, Seok Yun; Choi, Jin Hwa; Kwon, Sang-Mo; Masuda, Haruchika; Asahara, Takayuki; Lee, You-Mie

2012-05-01

Endothelial progenitor cells (EPCs) contribute to the tumor vasculature during tumor progression. Decursin isolated from the herb Angelica gigas is known to possess potent anti-inflammatory activities. Recently, we reported that decursin is a novel candidate for an angiogenesis inhibitor [Jung et al., 2009]. In this study, we investigated whether decursin regulates EPC differentiation and function to inhibit tumor vasculogenesis. We isolated AC133+ cells from human cord blood and decursin significantly decreased the number of EPC colony forming units of human cord blood-derived AC133+ cells that produce functional EPC progenies. Decursin dose-dependently decreased the cell number of EPC committing cells as demonstrated by EPC expansion studies. Decursin inhibited EPC differentiation from progenitor cells into spindle-shaped EPC colonies. Additionally, decursin inhibited proliferation and migration of early EPCs isolated from mouse bone marrow. Furthermore, decursin suppressed expression of angiopoietin-2, angiopoietin receptor Tie-2, Flk-1 (vascular endothelial growth factor receptor-2), and endothelial nitric oxide synthase in mouse BM derived EPCs in a dose-dependent manner. Decursin suppressed tube formation ability of EPCs in collaboration with HUVEC. Decursin (4 mg/kg) inhibited tumor-induced mobilization of circulating EPCs (CD34 + /VEGFR-2+ cells) from bone marrow and early incorporation of Dil-Ac-LDL-labeled or green fluorescent protein (GFP)+ EPCs into neovessels of xenograft Lewis lung carcinoma tumors in wild-type- or bone-marrow-transplanted mice. Accordingly, decursin attenuated EPC-derived endothelial cells in neovessels of Lewis lung carcinoma tumor masses grown in mice. Together, decursin likely affects EPC differentiation and function, thereby inhibiting tumor vasculogenesis in early tumorigenesis. Copyright © 2012 Wiley Periodicals, Inc.

Toll-like receptor 7 promotes the apoptosis of THP-1-derived macrophages through the CHOP-dependent pathway.

PubMed

Yu, Xiaochen; Wang, Yang; Zhao, Wenhui; Zhou, Haizhou; Yang, Wei; Guan, Xiuru

2014-09-01

Macrophage apoptosis is a prominent characteristic of advanced atherosclerotic plaques and leads to plaque destabilization. Certain studies have confirmed that influenza virus A (IVA) infection is related to acute myocardial infarction (AMI). However, it remains unknown as to whether this phenomenon is associated with Toll-like receptor (TLR)7, since single-stranded RNA (ssRNA) of IVA is a natural ligand of TLR7. Thus, in the present study, THP-1‑derived macrophages were infected with IVA or treated with imiquimod (IMQ) in the presence or absence of pre-treatment with oxidized low-density lipoprotein (oxLDL). The macrophages were pre-treated with oxLDL (5 µg/ml) for 24 h to mimic high lipid conditions. Cell viability and apoptosis were detected by 3-(4,5-dimethylthiazol-2-y-1)‑2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and flow cytometry, respectively. Our results revealed that TLR7 played an important role in macrophage apoptosis and cytokine secretion. Both IVA infection and IMQ treatment increased TLR7 expression, as well as the secretion of pro-inflammatory cytokines [interleukin (IL)-6, monocyte chemotactic protein (MCP)-1] and apoptosis. However, this increase in cytokine secretion occurred independently of cell apoptosis. oxLDL had potential synergistic pro-apoptotic effects combined with TLR7 activation. To determine whether endoplasmic reticulum (ER) stress plays a role in cell apoptosis, the mRNA and protein expression of known markers of ER stress [glucose-regulated protein (GRP)78 and C/EBP homologous protein (CHOP)] was detected by reverse transcription PCR (RT-PCR), quantitative reverse transcription PCR (qRT-PCR) and western blot analysis. Our results revealed that apoptosis aggravated ER stress, as shown by the overexpression of the pro-apoptotic sensor, CHOP. In conclusion, our study demonstrates the converging role of oxLDL pre-treatment, IVA infection and IMQ in ER stress-induced cell apoptosis.

Soya phytoestrogens, genistein and daidzein, decrease apolipoprotein B secretion from HepG2 cells through multiple mechanisms.

PubMed Central

Borradaile, Nica M; de Dreu, Linda E; Wilcox, Lisa J; Edwards, Jane Y; Huff, Murray W

2002-01-01

Diets containing the soya-derived phytoestrogens, genistein and daidzein, decrease plasma cholesterol in humans and experimental animals. The mechanisms responsible for the hypocholesterolaemic effects of these isoflavones are unknown. The present study was conducted to determine if genistein and daidzein regulate hepatocyte cholesterol metabolism and apolipoprotein (apo) B secretion in cultured human hepatoma (HepG2) cells. ApoB secretion was decreased dose-dependently by up to 63% and 71% by genistein and daidzein (100 microM; P<0.0001) respectively. In contrast, no effect on apoAI secretion was observed. Cellular cholesterol synthesis was inhibited 41% by genistein (100 microM; P<0.005) and 18% by daidzein (100 microM; P<0.05), which was associated with significant increases in 3-hydroxy-3-methylglutaryl-CoA reductase mRNA. Cellular cholesterol esterification was decreased 56% by genistein (100 microM; P<0.04) and 29% by daidzein (100 microM; P<0.04); however, mRNA levels for acyl-CoA:cholesterol acyltransferase (ACAT) 1 and ACAT2 were unaffected. At 100 microM, both isoflavones equally inhibited the activities of both forms of ACAT in cells transfected with either ACAT1 or ACAT2. Genistein (100 microM) and daidzein (100 microM) significantly decreased the activity of microsomal triacylglycerol transfer protein (MTP) by 30% and 24% respectively, and significantly decreased MTP mRNA levels by 35% and 55%. Both isoflavones increased low-density lipoprotein (LDL)-receptor mRNA levels by 3- to 6-fold (100 microM; P<0.03) and significantly increased the binding, uptake and degradation of (125)I-labelled LDL, suggesting that enhanced reuptake of newly secreted apoB-containing lipoproteins contributed to the net decrease in apoB secretion. These results indicate that genistein and daidzein inhibit hepatocyte apoB secretion through several mechanisms, including inhibition of cholesterol synthesis and esterification, inhibition of MTP activity and expression and increased expression of the LDL-receptor. PMID:12030847

P2X7R is involved in the progression of atherosclerosis by promoting NLRP3 inflammasome activation

PubMed Central

PENG, KUANG; LIU, LUSHAN; WEI, DANGHENG; LV, YUNCHENG; WANG, GANG; XIONG, WENHAO; WANG, XIAOQING; ALTAF, AFRASYAB; WANG, LILI; HE, DAN; WANG, HONGYAN; QU, PENG

2015-01-01

Purinergic 2X7 receptor (P2X7R) and nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) are expressed in macrophages in atherosclerotic lesions. However, the mechanisms through which P2X7R participates in the inflammatory response in atherosclerosis remain largely unknown. The aim of the present study was to investigate the role of P2X7R in atherosclerosis and the mechanisms of action of the NLRP3 inflammasome following stimulation with oxidized low-density lipoprotein (oxLDL). We observed the expression and distribution of P2X7R in the atherosclerotic plaque in the coronary arteries from an autopsy specimen and in that of the aortic sinuses of apoE−/− mice by immunohistochemistry and immunofluorescence staining. The specificity of short interfering RNA (siRNA) was used to suppress P2X7R and NLRP3 mRNA expression. RT-qPCR and western blot analysis were used to analyze mRNA and protein expression, respectively. Co-immunoprecipitation was used to examine the interaction between protein kinase R (PKR) phosphorylation and NLRP3. P2X7R and NLRP3 were expressed at high levels in the atherosclerotic plaque in the coronary arteries. Stimulation with oxLDL upregulated P2X7R, NLRP3 and interleukin (IL)-1β expression. P2X7R knockdown by siRNA suppressed NLRP3 inflammasome activation by inhibiting the PKR phosphorylation mediated by oxLDL. In the atherosclerotic lesions in the aortic sinuses of apoE−/− mice, P2X7R expression was found at high levels. Moreover, P2X7R siRNA attenuated the development of atherosclerosis in the apoE−/− mice. In conclusion, our results demonstrate that P2X7R plays a significant role in the development of atherosclerosis and regulates NLRP3 inflammasome activation by promoting PKR phosphorylation. PMID:25761252

Tauroursodeoxycholic Acid Attenuates Lipid Accumulation in Endoplasmic Reticulum-Stressed Macrophages

PubMed Central

Hua, Yinan; Kandadi, Machender R.; Zhu, Meijun; Ren, Jun; Sreejayan, Nair

2011-01-01

Background/Aim Recent evidence suggests that endoplasmic reticulum (ER) stress provoked under diabetic conditions augments the expression of scavenger receptors on macrophages, promoting the uptake of oxidized low-density lipoprotein (ox-LDL) uptake and atherogenesis. The aim of the present study was to test the hypothesis that the chemical chaperone tauroursodeoxycholic acid (TUDCA) attenuates lipid accumulation in macrophages subjected to ER stress. Methods Cultured human macrophages were subjected to ER-stress by treating them with tunicamycin. Lipid-uptake by macrophages subjected to ER-stress in the presence or absence of TUDCA was assessed by oil red O staining and by assessing the cellular uptake of Dil-ox-LDL by fluorescence measurement. Protein levels and phosphorylation status of ER stress markers, insulin-signalling molecules and scavenger receptor were assessed by Western blotting. Results Treatment of cultured human macrophages with the ER-stressor tunicamycin caused an increase in the protein levels of CD-36, and augmentation of lipid-uptake both of which were inhibited by TUDCA. TUDCA-treatment inhibited tunicamycin-induced ER-stress as evidenced by the attenuation of phosphorylation of eukaryotic translation initiation factor-2α and glucose reactive protein-78. In addition, TUDCA improved insulin signaling in macrophages by augmenting Akt-phosphorylation and blunting c-Jun N-terminal kinase activity. Conclusion Inhibition of macrophage ER-stress may represent a potential strategy in preventing atherogenesis under diabetic conditions. PMID:19834331

Mangifera indica L. extract (Vimang®) reduces plasma and liver cholesterol and leucocyte oxidative stress in hypercholesterolemic LDL receptor deficient mice.

PubMed

Dorighello, Gabriel G; Inada, Natália M; Paim, Bruno A; Pardo-Andreu, Gilberto L; Vercesi, Anibal E; Oliveira, Helena C F

2018-06-01

Cardiovascular diseases are major causes of death worldwide. Beyond the classical cholesterol risk factor, other conditions such as oxidative stress are well documented to promote atherosclerosis. The Mangifera indica L. extract (Vimang®) was reported to present antioxidant and hypocholesterolemic properties. Thus, here we evaluate the effects of Vimang treatment on risk factors of the atherosclerosis prone model of familial hypercholesterolemia, the LDL receptor knockout mice. Mice were treated with Vimang during 2 weeks and were fed a cholesterol-enriched diet during the second week. The Vimang treated mice presented significantly reduced levels of plasma (15%) and liver (20%) cholesterol, increased plasma total antioxidant capacity (10%) and decreased reactive oxygen species (ROS) production by spleen mononuclear cells (50%), P < 0.05 for all. In spite of these benefits, the average size of aortic atherosclerotic lesions stablished in this short experimental period did not change significantly in Vimang treated mice. Therefore, in this study we demonstrated that Vimang has protective effects on systemic and tissue-specific risk factors, but it is not sufficient to promote a reduction in the initial steps of atherosclerosis development. In addition, we disclosed a new antioxidant target of Vimang, the spleen mononuclear cells that might be relevant for more advanced stages of atherosclerosis. © 2018 International Federation for Cell Biology.

Expression of the peroxisome proliferator-activated receptor γ (PPARγ) in human atherosclerosis and regulation in macrophages by colony stimulating factors and oxidized low density lipoprotein

PubMed Central

Ricote, Mercedes; Huang, Jannet; Fajas, Luis; Li, Andrew; Welch, John; Najib, Jamila; Witztum, Joseph L.; Auwerx, Johan; Palinski, Wulf; Glass, Christopher K.

1998-01-01

The peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor that has been demonstrated to regulate fat cell development and glucose homeostasis. PPARγ is also expressed in a subset of macrophages and negatively regulates the expression of several proinflammatory genes in response to natural and synthetic ligands. We here demonstrate that PPARγ is expressed in macrophage foam cells of human atherosclerotic lesions, in a pattern that is highly correlated with that of oxidation-specific epitopes. Oxidized low density lipoprotein (oxLDL) and macrophage colony-stimulating factor, which are known to be present in atherosclerotic lesions, stimulated PPARγ expression in primary macrophages and monocytic cell lines. PPARγ mRNA expression was also induced in primary macrophages and THP-1 monocytic leukemia cells by the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA). Inhibition of protein kinase C blocked the induction of PPARγ expression by TPA, but not by oxLDL, suggesting that more than one signaling pathway regulates PPARγ expression in macrophages. TPA induced the expression of PPARγ in RAW 264.7 macrophages by increasing transcription from the PPARγ1 and PPARγ3 promoters. In concert, these observations provide insights into the regulation of PPARγ expression in activated macrophages and raise the possibility that PPARγ ligands may influence the progression of atherosclerosis. PMID:9636198

Glomerular clusterin is associated with PKC-alpha/beta regulation and good outcome of membranous glomerulonephritis in humans.

PubMed

Rastaldi, M P; Candiano, G; Musante, L; Bruschi, M; Armelloni, S; Rimoldi, L; Tardanico, R; Sanna-Cherchi, S; Cherchi, S Sanna; Ferrario, F; Montinaro, V; Haupt, R; Parodi, S; Carnevali, M L; Allegri, L; Camussi, G; Gesualdo, L; Scolari, F; Ghiggeri, G M

2006-08-01

Mechanisms for human membranous glomerulonephritis (MGN) remain elusive. Most up-to-date concepts still rely on the rat model of Passive Heymann Nephritis that derives from an autoimmune response to glomerular megalin, with complement activation and membrane attack complex assembly. Clusterin has been reported as a megalin ligand in immunodeposits, although its role has not been clarified. We studied renal biopsies of 60 MGN patients by immunohistochemistry utilizing antibodies against clusterin, C5b-9, and phosphorylated-protien kinase C (PKC) isoforms (pPKC). In vitro experiments were performed to investigate the role of clusterin during podocyte damage by MGN serum and define clusterin binding to human podocytes, where megalin is known to be absent. Clusterin, C5b-9, and pPKC-alpha/beta showed highly variable glomerular staining, where high clusterin profiles were inversely correlated to C5b-9 and PKC-alpha/beta expression (P=0.029), and co-localized with the low-density lipoprotein receptor (LDL-R). Glomerular clusterin emerged as the single factor influencing proteinuria at multivariate analysis and was associated with a reduction of proteinuria after a follow-up of 1.5 years (-88.1%, P=0.027). Incubation of podocytes with MGN sera determined strong upregulation of pPKC-alpha/beta that was reverted by pre-incubation with clusterin, serum de-complementation, or protein-A treatment. Preliminary in vitro experiments showed podocyte binding of biotinilated clusterin, co-localization with LDL-R and specific binding inhibition with anti-LDL-R antibodies and with specific ligands. These data suggest a central role for glomerular clusterin in MGN as a modulator of inflammation that potentially influences the clinical outcome. Binding of clusterin to the LDL-R might offer an interpretative key for the pathogenesis of MGN in humans.

Exchanging a few commercial, regularly consumed food items with improved fat quality reduces total cholesterol and LDL-cholesterol: a double-blind, randomised controlled trial.

PubMed

Ulven, Stine M; Leder, Lena; Elind, Elisabeth; Ottestad, Inger; Christensen, Jacob J; Telle-Hansen, Vibeke H; Skjetne, Anne J; Raael, Ellen; Sheikh, Navida A; Holck, Marianne; Torvik, Kristin; Lamglait, Amandine; Thyholt, Kari; Byfuglien, Marte G; Granlund, Linda; Andersen, Lene F; Holven, Kirsten B

2016-10-01

The healthy Nordic diet has been previously shown to have health beneficial effects among subjects at risk of CVD. However, the extent of food changes needed to achieve these effects is less explored. The aim of the present study was to investigate the effects of exchanging a few commercially available, regularly consumed key food items (e.g. spread on bread, fat for cooking, cheese, bread and cereals) with improved fat quality on total cholesterol, LDL-cholesterol and inflammatory markers in a double-blind randomised, controlled trial. In total, 115 moderately hypercholesterolaemic, non-statin-treated adults (25-70 years) were randomly assigned to an experimental diet group (Ex-diet group) or control diet group (C-diet group) for 8 weeks with commercially available food items with different fatty acid composition (replacing SFA with mostly n-6 PUFA). In the Ex-diet group, serum total cholesterol (P<0·001) and LDL-cholesterol (P<0·001) were reduced after 8 weeks, compared with the C-diet group. The difference in change between the two groups at the end of the study was -9 and -11 % in total cholesterol and LDL-cholesterol, respectively. No difference in change in plasma levels of inflammatory markers (high-sensitive C-reactive protein, IL-6, soluble TNF receptor 1 and interferon-γ) was observed between the groups. In conclusion, exchanging a few regularly consumed food items with improved fat quality reduces total cholesterol, with no negative effect on levels of inflammatory markers. This shows that an exchange of a few commercially available food items was easy and manageable and led to clinically relevant cholesterol reduction, potentially affecting future CVD risk.

In vivo biochemical and gene expression analyses of the antioxidant activities and hypocholesterolaemic properties of Tamarindus indica fruit pulp extract.

PubMed

Lim, Chor Yin; Mat Junit, Sarni; Abdulla, Mahmood Ameen; Abdul Aziz, Azlina

2013-01-01

Tamarindus indica (T. indica) is a medicinal plant with many biological activities including anti-diabetic, hypolipidaemic and anti-bacterial activities. A recent study demonstrated the hypolipidaemic effect of T. indica fruit pulp in hamsters. However, the biochemical and molecular mechanisms responsible for these effects have not been fully elucidated. Hence, the aims of this study were to evaluate the antioxidant activities and potential hypocholesterolaemic properties of T. indica, using in vitro and in vivo approaches. The in vitro study demonstrated that T. indica fruit pulp had significant amount of phenolic (244.9 ± 10.1 mg GAE/extract) and flavonoid (93.9 ± 2.6 mg RE/g extract) content and possessed antioxidant activities. In the in vivo study, hamsters fed with high-cholesterol diet for ten weeks showed elevated serum triglyceride, total cholesterol, HDL-C and LDL-C levels. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters significantly lowered serum triglyceride, total cholesterol and LDL-C levels but had no effect on the HDL-C level. The lipid-lowering effect was accompanied with significant increase in the expression of Apo A1, Abcg5 and LDL receptor genes and significant decrease in the expression of HMG-CoA reductase and Mtp genes. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters also protected against oxidative damage by increasing hepatic antioxidant enzymes, antioxidant activities and preventing hepatic lipid peroxidation. It is postulated that tamarind fruit pulp exerts its hypocholesterolaemic effect by increasing cholesterol efflux, enhancing LDL-C uptake and clearance, suppressing triglyceride accumulation and inhibiting cholesterol biosynthesis. T. indica fruit pulp has potential antioxidative effects and is potentially protective against diet-induced hypercholesterolaemia.

In Vivo Biochemical and Gene Expression Analyses of the Antioxidant Activities and Hypocholesterolaemic Properties of Tamarindus indica Fruit Pulp Extract

PubMed Central

Lim, Chor Yin; Mat Junit, Sarni; Abdulla, Mahmood Ameen; Abdul Aziz, Azlina

2013-01-01

Background Tamarindus indica (T. indica) is a medicinal plant with many biological activities including anti-diabetic, hypolipidaemic and anti-bacterial activities. A recent study demonstrated the hypolipidaemic effect of T. indica fruit pulp in hamsters. However, the biochemical and molecular mechanisms responsible for these effects have not been fully elucidated. Hence, the aims of this study were to evaluate the antioxidant activities and potential hypocholesterolaemic properties of T. indica, using in vitro and in vivo approaches. Methodology/Principal Findings The in vitro study demonstrated that T. indica fruit pulp had significant amount of phenolic (244.9±10.1 mg GAE/extract) and flavonoid (93.9±2.6 mg RE/g extract) content and possessed antioxidant activities. In the in vivo study, hamsters fed with high-cholesterol diet for ten weeks showed elevated serum triglyceride, total cholesterol, HDL-C and LDL-C levels. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters significantly lowered serum triglyceride, total cholesterol and LDL-C levels but had no effect on the HDL-C level. The lipid-lowering effect was accompanied with significant increase in the expression of Apo A1, Abcg5 and LDL receptor genes and significant decrease in the expression of HMG-CoA reductase and Mtp genes. Administration of T. indica fruit pulp to hypercholesterolaemic hamsters also protected against oxidative damage by increasing hepatic antioxidant enzymes, antioxidant activities and preventing hepatic lipid peroxidation. Conclusion/Significance It is postulated that tamarind fruit pulp exerts its hypocholesterolaemic effect by increasing cholesterol efflux, enhancing LDL-C uptake and clearance, suppressing triglyceride accumulation and inhibiting cholesterol biosynthesis. T. indica fruit pulp has potential antioxidative effects and is potentially protective against diet-induced hypercholesterolaemia. PMID:23894592

Target drug delivery system as a new scarring modulation after glaucoma filtration surgery

PubMed Central

2011-01-01

Background Excessive wound healing following glaucoma filtration surgery is the main determinant of surgical failure, resulting from the activation of human Tenon's capsule fibroblasts (HTFs). To mitigate the excessive wound healing, the topicall use of antiproliferative agents, such as mitomycin C (MMC) and 5-fluorouracil (5-FU), has increased the surgery success rate, but the traditional administration of these agents can result in a variety of toxicities with nonspecific damage. However, modulation of the wound healing process to prevent excessive fibroblast proliferation and scar formation can play a major role in improving the outcome of surgery. Therefore, the search for alternative modes of drug delivery and new agents is needed to minimize the ocular complications and improve the success of surgery. We have shown that there is a postoperative overexpression of the LDL receptor (LDLr) in the activated HTFs may provide a novel target for drug delivery systems. Presentation of the Hypothesis We hypothesize that antifibrotic agents (MMC) encapsulated in LDLr targeting drug delivery system (LDL-MMC-chitosan nanoparticles) may be proposed in anti-scarring therapy to increase the safety and effectiveness and to reduce toxicity. Testing the Hypothesis A chitosan-based polymeric predrug of MMC was synthesized and its cytotoxicity was proved to be low. In addition, we propose hyaluronic acid film as a container to release LDL-MMC-chitosan nanoparticles gradually at subconjunctival filtering site after glaucoma filtration surgery to eliminate the LDL-MMC-chitosan nanoparticles. Implications of the Hypothesis and discussion This strategy can be applicable to anti-scarring therapy during excessive conjunctival wound healing. This hypothesis integrates advantages of the targeting drug delivery and antifibrotic agents, such as high efficiency, convenience, and lower the toxicity. PMID:21736763

Prognostic value of fasting versus nonfasting low-density lipoprotein cholesterol levels on long-term mortality: insight from the National Health and Nutrition Examination Survey III (NHANES-III).

PubMed

Doran, Bethany; Guo, Yu; Xu, Jinfeng; Weintraub, Howard; Mora, Samia; Maron, David J; Bangalore, Sripal

2014-08-12

National and international guidelines recommend fasting lipid panel measurement for risk stratification of patients for prevention of cardiovascular events. However, the prognostic value of fasting versus nonfasting low-density lipoprotein cholesterol (LDL-C) is uncertain. Patients enrolled in the National Health and Nutrition Examination Survey III (NHANES-III), a nationally representative cross-sectional survey performed from 1988 to 1994, were stratified on the basis of fasting status (≥8 or <8 hours) and followed for a mean of 14.0 (±0.22) years. Propensity score matching was used to assemble fasting and nonfasting cohorts with similar baseline characteristics. The risk of outcomes as a function of LDL-C and fasting status was assessed with the use of receiver operating characteristic curves and bootstrapping methods. The interaction between fasting status and LDL-C was assessed with Cox proportional hazards modeling. Primary outcome was all-cause mortality. Secondary outcome was cardiovascular mortality. One-to-one matching based on propensity score yielded 4299 pairs of fasting and nonfasting individuals. For the primary outcome, fasting LDL-C yielded prognostic value similar to that for nonfasting LDL-C (C statistic=0.59 [95% confidence interval, 0.57-0.61] versus 0.58 [95% confidence interval, 0.56-0.60]; P=0.73), and LDL-C by fasting status interaction term in the Cox proportional hazards model was not significant (Pinteraction=0.11). Similar results were seen for the secondary outcome (fasting versus nonfasting C statistic=0.62 [95% confidence interval, 0.60-0.66] versus 0.62 [95% confidence interval, 0.60-0.66]; P=0.96; Pinteraction=0.34). Nonfasting LDL-C has prognostic value similar to that of fasting LDL-C. National and international agencies should consider reevaluating the recommendation that patients fast before obtaining a lipid panel. © 2014 American Heart Association, Inc.

One-Year Conservative Care Using Sodium Bicarbonate Supplementation Is Associated with a Decrease in Electronegative LDL in Chronic Kidney Disease Patients: A Pilot Study.

PubMed

Rizzetto, Felipe; Mafra, Denise; Barra, Ana Beatriz; Pires de Melo, Gisella; Abdalla, Dulcinéia Saes Parra; Leite, Maurilo

2017-10-01

Chronic kidney disease (CKD) patients develop metabolic acidosis when approaching stages 3 and 4, a period in which accelerated atherogenesis may ensue. Studies in vitro show that low pH may increase low-density lipoprotein (LDL) oxidation, suggesting a role for chronic metabolic acidosis in atherosclerosis. The present study attempted to evaluate the effects of conservative care using oral sodium bicarbonate (NaHCO 3 ) supplementation on the electronegative LDL [LDL(-)], a minimally oxidized LDL, plasma levels in CKD patients. Thirty-one CKD patients were followed by a multidisciplinary team during 15 months of care in which 1.0 mmol/kg/day oral NaHCO 3 supplementation was first given in the third month. Blood samples were collected 3 months before the initiation of oral NaHCO 3 supplementation (T1), at the time of the beginning of supplementation (T2), and thereafter, each 4 months (T3, T4 and T5) until month 15 of care. Blood parameters and LDL(-) were measured from these collections. After 12 months of conservative care, creatinine clearance (MDRD) was kept stable, and serum bicarbonate (HCO 3 - ) increased from 20.5 ± 2.9 to 22.6 ± 1.1 mM ( p < 0.003). LDL(-) plasma levels declined from 4.5 ± 3.3 to 2.1 ± 0.9 U/L ( p < 0.007) after reaching mean serum HCO 3 - levels of 22.6 ± 1.1 mM. Conservative care using oral NaHCO 3 supplementation was able to stabilize renal function and decrease serum levels of LDL(-), a modified proatherogenic lipoprotein, only when mean serum HCO 3 - levels approached 22 mM. This study constitutes evidence that alkali therapy, in addition to its beneficial effect on renal disease progression, might serve as a preventive strategy to attenuate atherogenesis in CKD patients.

Three-dimensional visualization of coated vesicle formation in fibroblasts

PubMed Central

1980-01-01

Fibroblasts apparently ingest low density lipoproteins (LDL) by a selective mechanism of receptor-mediated endocytosis involving the formation of coated vesicles from the plasma membrane. However, it is not known exactly how coated vesicles collect LDL receptors and pinch off from the plasma membrane. In this report, the quick-freeze, deep- etch, rotary-replication method has been applied to fibroblasts; it displays with unusual clarity the coats that appear under the plasma membrane at the start of receptor-mediated endocytosis. These coats appear to be polygonal networks of 7-nm strands or struts arranged into 30-nm polygons, most of which are hexagons but some of which are 5- and 7-sided rings. The proportion of pentagons in each network increases as the coated area of the plasma membrane puckers up from its planar configuration (where the network is mostly hexagons) to its most sharply curved condition as a pinched-off coated vesicle. Coats around the smallest vesicles (which are icosahedrons of hexagons and pentagons) appear only slightly different from "empty coats" purified from homogenized brain, which are less symmetrical baskets containing more pentagons than hexagons. A search for structural intermediates in this coat transformation allows a test of T. Kanaseki and K. Kadota's (1969. J. Cell Biol. 42:202--220.) original idea that an internal rearrangement in this basketwork from hexagons to pentagons could "power" coated vesicle formation. The most noteworthy variations in the typical hexagonal honeycomb are focal juxtapositions of 5- and 7-sided polygons at points of partial contraction and curvature in the basketwork. These appear to precede complete contraction into individual pentagons completely surrounded by hexagons, which is the pattern that characterizes the final spherical baskets around coated vesicles. PMID:6987244

Effect of exercise on serum vitamin D and tissue vitamin D receptors in experimentally induced type 2 Diabetes Mellitus.

PubMed

Aly, Yosria E; Abdou, Azza S; Rashad, Mona M; Nassef, Menatallah M

2016-09-01

This work aimed to study the effect of swimming exercise on serum vitamin D level and tissue vitamin D receptors in experimentally induced type 2 Diabetes Mellitus. Sixty adult male rats were divided into control and diabetic groups. Each was further subdivided into sedentary and exercised subgroups. Diabetes Mellitus was induced by a single intraperitoneal dose of streptozotocin (50 mg/kg) dissolved in cold 0.01 M citrate buffer (pH 4.5). The exercised subgroups underwent swimming for 60 min, 5 times a week for 4 weeks. Serum glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), lipids, vitamin D and tissue Vitamin D receptors (VDR) were evaluated. Significant increase in serum glucose, insulin, HOMA-IR, cholesterol, triglycerides, and low density lipoprotein (LDL) levels in sedentary diabetic rats was detected. On the other hand, high density lipoprotein (HDL), free fatty acids, serum vitamin D and pancreatic, adipose, and muscular VDR showed a significant decrease in the same group. It is evident that all these parameters were reversed by swimming exercise indicating its beneficial role in type 2 Diabetes. In diabetic groups; serum vitamin D was found to be correlated negatively with serum glucose, insulin, HOMA, cholesterol, triglycerides, and LDL and positively correlated with HDL and tissue VDR. In conclusion, Disturbed vitamin D is associated with metabolic impairments in sedentary diabetic rats. Moderate swimming exercise is beneficial in improving these consequences through modulation of vitamin D status. Future studies could be designed to investigate the effect of the combination of vitamin D intake with exercise in diabetic patients.

Dysregulation of hepatic fatty acid metabolism in chronic kidney disease.

PubMed

Jin, Kyubok; Norris, Keith; Vaziri, Nosratola D

2013-02-01

Chronic kidney disease (CKD) results in hypertriglyceridemia which is largely due to impaired clearance of triglyceride-rich lipoproteins occasioned by downregulation of lipoprotein lipase and very low-density lipoprotein (LDL) receptor in the skeletal muscle and adipose tissue and of hepatic lipase and LDL receptor-related protein in the liver. However, data on the effect of CKD on fatty acid metabolism in the liver is limited and was investigated here. Male Sprague-Dawley rats were randomized to undergo 5/6 nephrectomy (CRF) or sham operation (control) and observed for 12 weeks. The animals were then euthanized and their liver tissue tested for nuclear translocation (activation) of carbohydrate-responsive element binding protein (ChREBP) and sterol-responsive element binding protein-1 (SREBP-1) which independently regulate the expression of key enzyme in fatty acid synthesis, i.e. fatty acid synthase (FAS) and acyl-CoA carboxylase (ACC) as well as nuclear Peroxisome proliferator-activated receptor alpha (PPARα) which regulates the expression of enzymes involved in fatty acid oxidation and transport, i.e. L-FABP and CPT1A. In addition, the expression of ATP synthase α, ATP synthase β, glycogen synthase and diglyceride acyltransferase 1 (DGAT1) and DGAT2 were determined. Compared with controls, the CKD rats exhibited hypertriglyceridemia, elevated plasma and liver tissue free fatty acids, increased nuclear ChREBP and reduced nuclear SREBP-1 and PPARα, upregulation of ACC and FAS and downregulation of L-FABP, CPT1A, ATP synthase α, glycogen synthase and DGAT in the liver tissue. Liver in animals with advanced CKD exhibits ChREBP-mediated upregulation of enzymes involved in fatty acid synthesis, downregulation of PPARα-regulated fatty acid oxidation system and reduction of DGAT resulting in reduced fatty acid incorporation in triglyceride.

Impaired compensatory beta-cell function and growth in response to high-fat diet in LDL receptor knockout mice

PubMed Central

Oliveira, Ricardo B d; Carvalho, Carolina P d F; Polo, Carla C; Dorighello, Gabriel d G; Boschero, Antônio C; Oliveira, Helena C F d; Collares-Buzato, Carla B

2014-01-01

In this study, we investigated the effect of low density lipoprotein receptor (LDLr) deficiency on gap junctional connexin 36 (Cx36) islet content and on the functional and growth response of pancreatic beta-cells in C57BL/6 mice fed a high-fat (HF) diet. After 60 days on regular or HF diet, the metabolic state and morphometric islet parameters of wild-type (WT) and LDLr−/− mice were assessed. HF diet-fed WT animals became obese and hypercholesterolaemic as well as hyperglycaemic, hyperinsulinaemic, glucose intolerant and insulin resistant, characterizing them as prediabetic. Also they showed a significant decrease in beta-cell secretory response to glucose. Overall, LDLr−/− mice displayed greater susceptibility to HF diet as judged by their marked cholesterolaemia, intolerance to glucose and pronounced decrease in glucose-stimulated insulin secretion. HF diet induced similarly in WT and LDLr−/− mice, a significant decrease in Cx36 beta-cell content as revealed by immunoblotting. Prediabetic WT mice displayed marked increase in beta-cell mass mainly due to beta-cell hypertrophy/replication. Nevertheless, HF diet-fed LDLr−/− mice showed no significant changes in beta-cell mass, but lower islet–duct association (neogenesis) and higher beta-cell apoptosis index were seen as compared to controls. The higher metabolic susceptibility to HF diet of LDLr−/− mice may be explained by a deficiency in insulin secretory response to glucose associated with lack of compensatory beta-cell expansion. PMID:24853046

Statin action enriches HDL3 in polyunsaturated phospholipids and plasmalogens and reduces LDL-derived phospholipid hydroperoxides in atherogenic mixed dyslipidemia

PubMed Central

Tan, Ricardo; Giral, Philippe; Robillard, Paul; Kontush, Anatol; Chapman, M. John

2016-01-01

Atherogenic mixed dyslipidemia associates with oxidative stress and defective HDL antioxidative function in metabolic syndrome (MetS). The impact of statin treatment on the capacity of HDL to inactivate LDL-derived, redox-active phospholipid hydroperoxides (PCOOHs) in MetS is indeterminate. Insulin-resistant, hypertriglyceridemic, hypertensive, obese males were treated with pitavastatin (4 mg/day) for 180 days, resulting in marked reduction in plasma TGs (−41%) and LDL-cholesterol (−38%), with minor effects on HDL-cholesterol and apoAI. Native plasma LDL (baseline vs. 180 days) was oxidized by aqueous free radicals under mild conditions in vitro either alone or in the presence of the corresponding pre- or poststatin HDL2 or HDL3 at authentic plasma mass ratios. Lipidomic analyses revealed that statin treatment i) reduced the content of oxidizable polyunsaturated phosphatidylcholine (PUPC) species containing DHA and linoleic acid in LDL; ii) preferentially increased the content of PUPC species containing arachidonic acid (AA) in small, dense HDL3; iii) induced significant elevation in the content of phosphatidylcholine and phosphatidylethanolamine (PE) plasmalogens containing AA and DHA in HDL3; and iv) induced formation of HDL3 particles with increased capacity to inactivate PCOOH with formation of redox-inactive phospholipid hydroxide. Statin action attenuated LDL oxidability Concomitantly, the capacity of HDL3 to inactivate redox-active PCOOH was enhanced relative to HDL2, consistent with preferential enrichment of PE plasmalogens and PUPC in HDL3. PMID:27581680

Human plasma paraoxonase 1 (PON1) arylesterase activity during aging: correlation with susceptibility of LDL oxidation.

PubMed

Mehdi, Mohammad Murtaza; Rizvi, Syed Ibrahim

2012-08-01

The role of free radicals has long been proposed as a cause for the aging process. Oxidative stress is considered a major factor for altering many physiological processes and enzymatic activities during aging and is also known to play a major role in the development of several age-dependent diseases. Paraoxonase 1 (PON1) is an anti-atherosclerotic enzyme that mainly prevents accumulation of lipoperoxides and inhibits the lipid oxidation in low-density lipoproteins (LDL). This study was undertaken to investigate the antioxidant behavior of PON1 by measuring its arylesterase activity. The susceptibility of LDL for oxidation and the radical scavenging activity of plasma were also measured during aging in humans. Arylesterase activity of PON1 was measured in plasma of human subjects between 20 and 81 years of age of both genders. The susceptibility of LDL for oxidation and radical scavenging activity were measured in plasma. Decrease in plasma arylesterase activity of PON1, increase in susceptibility of LDL for oxidation and decrease in plasma radical scavenging activity were observed as a function of human age. The study provides evidence of a relationship between PON1 activity, LDL oxidation and free radical scavenging activity of plasma. The present results emphasize the dependency of PON1 activity to prevailing oxidative stress during human aging. Our findings assume significance in view of the possible categorization of PON1 as a longevity gene. Copyright © 2012 IMSS. Published by Elsevier Inc. All rights reserved.

Circulating Endothelial Progenitor Cells Present an Inflammatory Phenotype and Function in Patients With Alcoholic Liver Cirrhosis

PubMed Central

Kaur, Savneet; Sehgal, Rashi; Shastry, Saggere M.; McCaughan, Geoffrey; McGuire, Helen M.; Fazekas St de Groth, Barbara; Sarin, Shiv; Trehanpati, Nirupma; Seth, Devanshi

2018-01-01

Background and Aim: Endothelial progenitor cells (EPCs) have been implicated in liver injury and repair. However, the phenotype and potential of these heterogenous EPCs remain elusive. In particular, their involvement in the pathogenesis of alcoholic liver cirrhosis (ALC) remains unclear. The current study extensively characterized the phenotype and functions of EPCs to understand their role in ALC pathogenesis. Methods: Circulating EPCs were identified as CD34+CD133+CD31+ cells by flow cytometer in ALC patients (n = 7) and healthy controls (HC, n = 7). A comprehensive characterization of circulating EPCs using more than 30 phenotype markers was performed by mass cytometer time of flight (CyTOF) in an independent cohort of age and gender matched ALC patients (n = 4) and controls (n = 5). Ex vivo cultures of circulating EPCs from ALC patients (n = 20) and controls (n = 18) were also tested for their functions, including colony formation, LDL uptake, lectin binding and cytokine secretion (ELISA). Results: Three distinct populations of circulating EPCs (CD34+CD133+CD31+) were identified, classified on their CD45 expression (negative: CD45−; intermediate: CD45int; high: CD45hi). CD45int and CD45hi EPCs significantly increased in ALC patients compared to controls (p-val = 0.006). CyTOF data showed that CD45hi EPCs were distinct from CD45− and CD45int EPCs, with higher expression of T cell and myeloid markers, including CD3, CD4, HLA-DR, and chemokine receptors, CCR2, CCR5, CCR7, and CX3CR1. Similar to circulating EPCs, percentage of CD45hiCD34+CD31+ EPCs in ex-vivo cultures from patients, were significantly higher compared to controls (p < 0.05). Cultured EPCs from patients also showed increased LDL uptake, lectin binding and release of TNF-alpha, RANTES, FGF-2, and VEGF. Conclusions: We report the first extensive characterization of circulating human EPCs with distinct EPC subtypes. Increase in CD45hi EPC subtype in ALC patients with enhanced functions, inflammatory cytokines and angiogenic mediators in patients suggests an inflammatory role for these cells in ALC. PMID:29872403

Weight-loss changes PPAR expression, reduces atherosclerosis and improves cardiovascular function in obese insulin-resistant mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Verreth, Wim; Verhamme, Peter; Pelat, Michael

2003-09-01

Weight-loss in obese insulin-resistant, but not in insulin-sensitive, persons reduces CHD risk. It is not known to what extent changes in the adipose gene expression profile are important for reducing CHD risk. We studied the effect of diet restriction-induced weight-loss on gene expression in adipose tissue, atherosclerosis and cardiovascular function in mice with combined leptin and LDL-receptor deficiency. Obesity, hypertriglyceridemia and insulin-resistance are associated with hypertension, impaired left ventricle function and accelerated atherosclerosis in those mice. Diet restriction during 12 weeks caused a 45% weight-loss and changes in the gene expression in adipose tissue of PPARa and PPAR? and ofmore » key genes regulating glucose transport and insulin sensitivity, lipid metabolism, oxidative stress and inflammation, most of which are under the transcriptional control of PPARs. These changes were associated with increased insulin-sensitivity, decreased hypertriglyceridemia, reduced mean 24-hour blood pressure and heart rate, restored circadian variations of blood pressure and heart rate, increased ejection fraction, and reduced atherosclerosis. Thus, induction of PPARa and PPAR? in adipose tissue is a key mechanism for reducing atherosclerosis and improving cardiovascular function resulting from weight-loss. Our observations point to the critical role of PPARs in the pathogenesis of cardiovascular features of the metabolic syndrome.« less

Validation of the Martin Method for Estimating Low-Density Lipoprotein Cholesterol Levels in Korean Adults: Findings from the Korea National Health and Nutrition Examination Survey, 2009-2011

PubMed Central

Lee, Jongseok; Jang, Sungok; Son, Heejeong

2016-01-01

Despite the importance of accurate assessment for low-density lipoprotein cholesterol (LDL-C), the Friedewald formula has primarily been used as a cost-effective method to estimate LDL-C when triglycerides are less than 400 mg/dL. In a recent study, an alternative to the formula was proposed to improve estimation of LDL-C. We evaluated the performance of the novel method versus the Friedewald formula using a sample of 5,642 Korean adults with LDL-C measured by an enzymatic homogeneous assay (LDL-CD). Friedewald LDL-C (LDL-CF) was estimated using a fixed factor of 5 for the ratio of triglycerides to very-low-density lipoprotein cholesterol (TG:VLDL-C ratio). However, the novel LDL-C (LDL-CN) estimates were calculated using the N-strata-specific median TG:VLDL-C ratios, LDL-C5 and LDL-C25 from respective ratios derived from our data set, and LDL-C180 from the 180-cell table reported by the original study. Compared with LDL-CF, each LDL-CN estimate exhibited a significantly higher overall concordance in the NCEP-ATP III guideline classification with LDL-CD (p< 0.001 for each comparison). Overall concordance was 78.2% for LDL-CF, 81.6% for LDL-C5, 82.3% for LDL-C25, and 82.0% for LDL-C180. Compared to LDL-C5, LDL-C25 significantly but slightly improved overall concordance (p = 0.008). LDL-C25 and LDL-C180 provided almost the same overall concordance; however, LDL-C180 achieved superior improvement in classifying LDL-C < 70 mg/dL compared to the other estimates. In subjects with triglycerides of 200 to 399 mg/dL, each LDL-CN estimate showed a significantly higher concordance than that of LDL-CF (p< 0.001 for each comparison). The novel method offers a significant improvement in LDL-C estimation when compared with the Friedewald formula. However, it requires further modification and validation considering the racial differences as well as the specific character of the applied measuring method. PMID:26824910

Differential reactivities of four homogeneous assays for LDL-cholesterol in serum to intermediate-density lipoproteins and small dense LDL: comparisons with the Friedewald equation.

PubMed

Yamashita, Shizuya; Kawase, Ryota; Nakaoka, Hajime; Nakatani, Kazuhiro; Inagaki, Miwako; Yuasa-Kawase, Miyako; Tsubakio-Yamamoto, Kazumi; Sandoval, Jose C; Masuda, Daisaku; Ohama, Tohru; Nakagawa-Toyama, Yumiko; Matsuyama, Akifumi; Nishida, Makoto; Ishigami, Masato

2009-12-01

In routine clinical laboratory testing and numerous epidemiological studies, LDL-cholesterol (LDL-C) has been estimated commonly using the Friedewald equation. We investigated the relationship between the Friedewald equation and 4 homogeneous assays for LDL-C. LDL-C was determined by 4 homogeneous assays [liquid selective detergent method: LDL-C (L), selective solubilization method: LDL-C (S), elimination method: LDL-C (E), and enzyme selective protecting method: LDL-C (P)]. Samples with discrepancies between the Friedewald equation and the 4 homogeneous assays for LDL-C were subjected to polyacrylamide gel electrophoresis and the beta-quantification method. The correlations between the Friedewald equation and the 4 homogeneous LDL-C assays were as follows: LDL-C (L) (r=0.962), LDL-C (S) (r=0.986), LDL-C (E) (r=0.946) and LDL-C (P) (r=0.963). Discrepancies were observed in sera from type III hyperlipoproteinemia patients and in sera containing large amounts of midband and small dense LDL on polyacrylamide gel electrophoresis. LDL-C (S) was most strongly correlated with the beta-quantification method even in sera from patients with type III hyperlipoproteinemia. Of the 4 homogeneous assays for LDL-C, LDL-C (S) exhibited the closest correlation with the Friedewald equation and the beta-quantification method, thus reflecting the current clinical databases for coronary heart disease.

Actions of placental and fetal adrenal steroid hormones in primate pregnancy.

PubMed

Pepe, G J; Albrecht, E D

1995-10-01

It is clear that steroid hormones of placental and fetal adrenal origin have critically important roles in regulating key physiological events essential to the maintenance of pregnancy and development of the fetus for extrauterine life. Thus, progesterone has suppressive actions on lymphocyte proliferation and activity and on the immune system to prevent rejection of the developing fetus and placenta (see Fig. 9). Progesterone also suppresses the calcium-calmodulin-MLCK system and thus activity of uterine smooth muscle, thereby promoting myometrial quiescence to ensure the maintenance of pregnancy. Estrogen enhances uteroplacental blood flow and possibly placental neovascularization to provide optimal gas exchange and the nutrients required for the rapidly developing fetus and placenta. In turn, estrogen has specific stimulatory effects on the receptor-mediated uptake of LDL by, and P-450scc activity within, syncytiotrophoblasts, thus promoting the biosynthesis of progesterone. Moreover, there is an estrogen-dependent developmental regulation of expression of the LDL receptor and NAD-dependent 11 beta-HSD in the placenta, processes reflecting functional/biochemical differentiation of the trophoblast cells with advancing gestation. The increase in 11 beta-HSD causes a change in transplacental corticosteroid metabolism, which results in activation of the HPAA in the fetus. As a result of this cascade of events, there is an increase in expression of pituitary POMC/ACTH and key enzymes, e.g. 3 beta-HSD and P-450 17 alpha-hydroxylase, important for de novo cortisol formation by, and consequently maturation of, the fetal adrenal gland. In turn, cortisol has well defined actions on surfactant biosynthesis and consequently fetal lung maturation, as well as effects on placental CRH/POMC release, which may be important to the initiation of labor. At midgestation, estrogen also selectively feeds back on the fetal adrenal to suppress DHA and maintain physiologically normal levels of estrogen. Preparation of the breast for lactation and nourishment of the newborn appears to involve a multifactorial system of regulation that includes estrogen. It is apparent, therefore, that autocrine/paracrine, as well as endocrine, systems of regulation are operative within the fetoplacental unit during primate pregnancy. A major goal of this review has been to illustrate the critically close functional communication existing between the developing placenta and fetus in the biosynthesis and the actions of steroid hormones during primate pregnancy. The functional interaction of the human fetal adrenal and placenta with respect to the biosynthesis of estrogen was demonstrated many years ago. However, the recent studies presented in this review show that the endocrine interaction between the fetus and placenta is more extensive, involving complex physiological regulatory mechanisms. Thus, as illustrated in Fig. 9, estrogen, acting via its receptor within the placenta and other reproductive tissues, orchestrates the dynamic interchange between the placenta and fetus responsible for the developmental regulation of the biosynthesis of the various steroid and peptide hormones and their receptors necessary for the maintenance of pregnancy and development of a live newborn. It would appear, therefore, that the immediate and long range challenges in this area of reproductive endocrinology are to employ in vitro molecular and in vivo experimental approaches simultaneously to elucidate the nature of these complex interactions and define the cellular and molecular mechanisms underlying these important regulatory events.

The low density lipoprotein receptor modulates the effects of hypogonadism on diet-induced obesity and related metabolic perturbations

PubMed Central

Constantinou, Caterina; Mpatsoulis, Diogenis; Natsos, Anastasios; Petropoulou, Peristera-Ioanna; Zvintzou, Evangelia; Traish, Abdulmaged M.; Voshol, Peter J.; Karagiannides, Iordanes; Kypreos, Kyriakos E.

2014-01-01

Here, we investigated how LDL receptor deficiency (Ldlr−/−) modulates the effects of testosterone on obesity and related metabolic dysfunctions. Though sham-operated Ldlr−/− mice fed Western-type diet for 12 weeks became obese and showed disturbed plasma glucose metabolism and plasma cholesterol and TG profiles, castrated mice were resistant to diet-induced obesity and had improved glucose metabolism and reduced plasma TG levels, despite a further deterioration in their plasma cholesterol profile. The effect of hypogonadism on diet-induced weight gain of Ldlr−/− mice was independent of ApoE and Lrp1. Indirect calorimetry analysis indicated that hypogonadism in Ldlr−/− mice was associated with increased metabolic rate. Indeed, mitochondrial cytochrome c and uncoupling protein 1 expression were elevated, primarily in white adipose tissue, confirming increased mitochondrial metabolic activity due to thermogenesis. Testosterone replacement in castrated Ldlr−/− mice for a period of 8 weeks promoted diet-induced obesity, indicating a direct role of testosterone in the observed phenotype. Treatment of sham-operated Ldlr−/− mice with the aromatase inhibitor exemestane for 8 weeks showed that the obesity of castrated Ldlr−/− mice is independent of estrogens. Overall, our data reveal a novel role of Ldlr as functional modulator of metabolic alterations associated with hypogonadism. PMID:24837748

Sterols regulate 3β-hydroxysterol Δ24-reductase (DHCR24) via dual sterol regulatory elements: cooperative induction of key enzymes in lipid synthesis by Sterol Regulatory Element Binding Proteins.

PubMed

Zerenturk, Eser J; Sharpe, Laura J; Brown, Andrew J

2012-10-01

3β-Hydroxysterol Δ24-reductase (DHCR24) catalyzes a final step in cholesterol synthesis, and has been ascribed diverse functions, such as being anti-apoptotic and anti-inflammatory. How this enzyme is regulated transcriptionally by sterols is currently unclear. Some studies have suggested that its expression is regulated by Sterol Regulatory Element Binding Proteins (SREBPs) while another suggests it is through the Liver X Receptor (LXR). However, these transcription factors have opposing effects on cellular sterol levels, so it is likely that one predominates. Here we establish that sterol regulation of DHCR24 occurs predominantly through SREBP-2, and identify the particular region of the DHCR24 promoter to which SREBP-2 binds. We demonstrate that sterol regulation is mediated by two sterol regulatory elements (SREs) in the promoter of the gene, assisted by two nearby NF-Y binding sites. Moreover, we present evidence that the dual SREs work cooperatively to regulate DHCR24 expression by comparison to two known SREBP target genes, the LDL receptor with one SRE, and farnesyl-diphosphate farnesyltransferase 1, with two SREs. Copyright © 2012 Elsevier B.V. All rights reserved.