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Sample records for low-density lipoprotein receptor

  1. Low-density-lipoprotein receptors in different rabbit liver cells.

    PubMed Central

    Nenseter, M S; Myklebost, O; Blomhoff, R; Drevon, C A; Nilsson, A; Norum, K R; Berg, T

    1989-01-01

    Receptor-dependent uptake mechanisms for low-density lipoprotein (LDL) were studied in rabbit liver parenchymal and non-parenchymal cells. Hybridization studies with a cDNA probe revealed that mRNA for the apo (apolipoprotein) B,E receptor was present in endothelial and Kupffer cells as well as in parenchymal cells. By ligand-blotting experiments we showed that apo B,E-receptor protein was present in both parenchymal and non-parenchymal cells. Studies of binding of homologous LDL in cultured rabbit parenchymal cells suggested that about 63% of the specific LDL binding was mediated via the apo B,E receptor. Approx. 47% of the specific LDL binding was dependent on Ca2+, suggesting that specific Ca2+-dependent as well as Ca2+-independent LDL-binding sites exist in liver parenchymal cells. Methylated LDL bound to the parenchymal cells in a saturable manner. Taken together, our results showed that apo B,E receptors are present in rabbit liver endothelial and Kupffer cells as well as in the parenchymal cells, and that an additional saturable binding activity for LDL may exist on rabbit liver parenchymal cells. This binding activity was not inhibited by EGTA or reductive methylation of lysine residues in apo B. LDL degradation in parenchymal cells was mainly mediated via the apo B,E receptor. Images Fig. 1. Fig. 2. PMID:2549976

  2. Distinct Hepatic Receptors for Low Density Lipoprotein and Apolipoprotein E in Humans

    NASA Astrophysics Data System (ADS)

    Hoeg, Jeffrey M.; Demosky, Stephen J.; Gregg, Richard E.; Schaefer, Ernst J.; Brewer, H. Bryan

    1985-02-01

    Since the liver is a central organ for lipid and lipoprotein synthesis and catabolism, hepatic receptors for specific apolipoproteins on plasma lipoproteins would be expected to modulate lipid and lipoprotein metabolism. The role of hepatic receptors for low density lipoproteins and apolipoprotein E-containing lipoproteins was evaluated in patients with complementary disorders in lipoprotein metabolism: abetalipoproteinemia and homozygous familial hypercholesterolemia. In addition, hepatic membranes from a patient with familial hypercholesterolemia were studied and compared before and after portacaval shunt surgery. The results establish that the human liver has receptors for apolipoproteins B and E. Furthermore, in the human, hepatic receptors for low density lipoproteins and apolipoprotein E are genetically distinct and can undergo independent control.

  3. Phagocytosis of aggregated lipoprotein by macrophages: Low density lipoprotein receptor-dependent foam-cell formation

    SciTech Connect

    Suits, A.G.; Chait, A.; Aviram, M.; Heinecke, J.W. )

    1989-04-01

    Low density lipoprotein (LDL) modified by incubation with phospholipase C (PLC-LDL) aggregates in solution and is rapidly taken up and degraded by human and mouse macrophages, producing foam cells in vitro. Human, mouse, and rabbit macrophages degraded {sup 125}I-labeled PLC-LDL ({sup 125}I-PLC-LDL) more rapidly than native {sup 125}I-labeled LDL ({sup 125}I-LDL), while nonphagocytic cells such as human fibroblasts and bovine aortic endothelial cells degraded {sup 125}I-PLC-LDL more slowly than {sup 125}I-LDL. This suggested the mechanism for internalization of PLC-LDL was phagocytosis. When examined by electron microscopy, mouse peritoneal macrophages appeared to be phagocytosing PLC-LDL. The uptake and degradation of {sup 125}I-PLC-LDL by human macrophages was inhibited >80% by the monoclonal antibody C7 (IgG2b) produced by hybridoma C7, which blocks the ligand binding domain of the LDL receptor. Similarly, methylation of {sup 125}I-LDL ({sup 125}I-MeLDL) prior to treatment with phospholipase C decreased its subsequent uptake and degradation by human macrophages by >90%. The uptake and degradation of phospholipase C-modified {sup 125}I-MeLDL by macrophages could be restored by incubation of the methylated lipoprotein with apoprotein E, a ligand recognized by the LDL receptor. These results indicate that macrophages internalize PLC-LDL by LDL receptor-dependent phagocytosis.

  4. Low density lipoprotein receptor related protein 1 variant interacts with saturated fatty acids in Puerto Ricans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low density lipoprotein related receptor protein 1 (LRP1) is a multi-functional endocytic receptor that is highly expressed in adipocytes and the hypothalamus. Animal models and in vitro studies support a role for LRP1 in adipocyte metabolism and leptin signaling, but genetic polymorphisms have not ...

  5. Particulate Matter Promotes In Vitro Receptor-Recognizable Low-Density Lipoprotein Oxidation and Dysfunction of Lipid Receptors

    PubMed Central

    Manzano-León, Natalia; Mas-Oliva, Jaime; Sevilla-Tapia, Laura; Morales-Bárcenas, Rocío; Serrano, Jesús; O’Neill, Marie S.; García-Cuellar, Claudia M.; Quintana, Raúl; Vázquez-López, Inés

    2015-01-01

    Particulate matter may promote cardiovascular disease, possibly as a consequence of its oxidative potential. Studies using susceptible animals indicate that particulate matter aggravates atherosclerosis by increasing lipid/macrophage content in plaques. Macrophage lipid uptake requires oxidized low-density lipoprotein and scavenger receptors; same receptors are involved in particulate matter uptake. We studied in vitro particulate matter potential to oxidize low-density lipoproteins and subsequent cell uptake through scavenger receptors. Particulate matter-induced low-density lipoproteins oxidation was evaluated by the thiobarbituric acid assay. Binding/internalization was tested in wild type and scavenger receptor–transfected Chinese hamster ovary cells, and in RAW264.7 cells using fluorescently labeled low-density lipoproteins. Dose-dependent binding/internalization only occurred in scavenger receptor–transfected Chinese hamster ovary cells and RAW264.7 cells. Competition binding/internalization using particles showed that particulate matter induced decreased binding (~50%) and internalization (~70%) of particle-oxidized low-density lipoproteins and native low-density lipoproteins. Results indicate that particulate matter was capable of oxidizing low-density lipoproteins, favoring macrophage internalization, and also altered scavenger and low-density lipoproteins receptor function. PMID:23297186

  6. Low-density lipoprotein receptor-related protein-1 facilitates heme scavenging after intracerebral hemorrhage in mice.

    PubMed

    Wang, Gaiqing; Manaenko, Anatol; Shao, Anwen; Ou, Yibo; Yang, Peng; Budbazar, Enkhjargal; Nowrangi, Derek; Zhang, John H; Tang, Jiping

    2016-06-17

    Heme-degradation after erythrocyte lysis plays an important role in the pathophysiology of intracerebral hemorrhage. Low-density lipoprotein receptor-related protein-1 is a receptor expressed predominately at the neurovascular interface, which facilitates the clearance of the hemopexin and heme complex. In the present study, we investigated the role of low-density lipoprotein receptor-related protein-1 in heme removal and neuroprotection in a mouse model of intracerebral hemorrhage. Endogenous low-density lipoprotein receptor-related protein-1 and hemopexin were increased in ipsilateral brain after intracerebral hemorrhage, accompanied by increased hemoglobin levels, brain water content, blood-brain barrier permeability and neurological deficits. Exogenous human recombinant low-density lipoprotein receptor-related protein-1 protein reduced hematoma volume, brain water content surrounding hematoma, blood-brain barrier permeability and improved neurological function three days after intracerebral hemorrhage. The expression of malondialdehyde, fluoro-Jade C positive cells and cleaved caspase 3 was increased three days after intracerebral hemorrhage in the ipsilateral brain tissues and decreased with recombinant low-density lipoprotein receptor-related protein-1. Intracerebral hemorrhage decreased and recombinant low-density lipoprotein receptor-related protein-1 increased the levels of superoxide dismutase 1. Low-density lipoprotein receptor-related protein-1 siRNA reduced the effect of human recombinant low-density lipoprotein receptor-related protein-1 on all outcomes measured. Collectively, our findings suggest that low-density lipoprotein receptor-related protein-1 contributed to heme clearance and blood-brain barrier protection after intracerebral hemorrhage. The use of low-density lipoprotein receptor-related protein-1 as supplement provides a novel approach to ameliorating intracerebral hemorrhage brain injury via its pleiotropic neuroprotective effects.

  7. The low-density lipoprotein receptor gene family: a cellular Swiss army knife?

    PubMed

    Nykjaer, Anders; Willnow, Thomas E

    2002-06-01

    The low-density lipoprotein receptor gene family is an evolutionarily conserved group of cell-surface receptors produced by mammals and other organisms. Initially thought to be endocytic receptors that mediate the uptake of lipoproteins, recent findings have shown that these receptors have other roles in a range of cellular processes. Among other activities, members of this family act as signal transducers in neuronal migration processes, regulate synaptic plasticity or control vitamin homeostasis. Such multifunctionality is achieved by interaction with diverse cell-surface proteins including glycolipid-anchored receptors, G-protein-coupled receptors and ion channels. Here, we review the molecular interactions of this protein family with other cell-surface proteins that provide specificity and versatility - a versatility that may be reminiscent of a cellular Swiss army knife.

  8. Collagenase-3 binds to a specific receptor and requires the low density lipoprotein receptor-related protein for internalization

    NASA Technical Reports Server (NTRS)

    Barmina, O. Y.; Walling, H. W.; Fiacco, G. J.; Freije, J. M.; Lopez-Otin, C.; Jeffrey, J. J.; Partridge, N. C.

    1999-01-01

    We have previously identified a specific receptor for collagenase-3 that mediates the binding, internalization, and degradation of this ligand in UMR 106-01 rat osteoblastic osteosarcoma cells. In the present study, we show that collagenase-3 binding is calcium-dependent and occurs in a variety of cell types, including osteoblastic and fibroblastic cells. We also present evidence supporting a two-step mechanism of collagenase-3 binding and internalization involving both a specific collagenase-3 receptor and the low density lipoprotein receptor-related protein. Ligand blot analysis shows that (125)I-collagenase-3 binds specifically to two proteins ( approximately 170 kDa and approximately 600 kDa) present in UMR 106-01 cells. Western blotting identified the 600-kDa protein as the low density lipoprotein receptor-related protein. Our data suggest that the 170-kDa protein is a specific collagenase-3 receptor. Low density lipoprotein receptor-related protein-null mouse embryo fibroblasts bind but fail to internalize collagenase-3, whereas UMR 106-01 and wild-type mouse embryo fibroblasts bind and internalize collagenase-3. Internalization, but not binding, is inhibited by the 39-kDa receptor-associated protein. We conclude that the internalization of collagenase-3 requires the participation of the low density lipoprotein receptor-related protein and propose a model in which the cell surface interaction of this ligand requires a sequential contribution from two receptors, with the collagenase-3 receptor acting as a high affinity primary binding site and the low density lipoprotein receptor-related protein mediating internalization.

  9. Giardia lamblia low-density lipoprotein receptor-related protein is involved in selective lipoprotein endocytosis and parasite replication.

    PubMed

    Rivero, Maria R; Miras, Silvana L; Quiroga, Rodrigo; Rópolo, Andrea S; Touz, Maria C

    2011-03-01

    As Giardia lamblia is unable to synthesize cholesterol de novo, this steroid might be obtained from the host's intestinal milieu by endocytosis of lipoproteins. In this work, we identified a putative Giardia lamblia low-density lipoprotein receptor-related proteins (GlLRP), a type I membrane protein, which shares the substrate N-terminal binding domain and a FXNPXY-type endocytic motif with human LRPs. Expression of tagged GlLRP showed that it was localized predominantly in the endoplasmic reticulum, lysosomal-like peripheral vacuoles and plasma membrane. However, the FXNPXY-deleted GlLRP was retained at the plasma membrane suggesting that it is abnormally transported and processed. The low-density lipoprotein and chylomicrons interacted with GlLRP, with this interaction being necessary for lipoprotein internalization and cell proliferation. Finally, we show that GlLRP binds directly to the medium subunit of Giardia adaptor protein 2, indicating that receptor-mediated internalization occurs through an adaptin mechanism.

  10. New low-density lipoprotein receptor upregulators acting via a novel mechanism.

    PubMed

    Ashton, M J; Brown, T J; Fenton, G; Halley, F; Harper, M F; Lockey, P M; Porter, B; Roach, A G; Stuttle, K A; Vicker, N; Walsh, R J

    1996-08-16

    The synthesis and biological activity of a new series of benzamides and related compounds that upregulate the expression of the low-density lipoprotein (LDL) receptor in human hepatocytes (HepG2 cells) by a novel mechanism are described. The lead compound, N-[5-[(3-cyclohexylpropionyl)amino]-2-methylphenyl]-4-hydroxybe nzamide (1, RPR102359), increased the expression of the LDL receptors in HepG2 cells by 80% when tested at a concentration of 3 microM. Mevinolin (lovastatin) was found to increase the LDL receptor expression by 70% at the same concentration. In contrast to mevinolin, 1 was found to have no effect on cholesterol biosynthesis in liver homogenates or in HepG2 cells at doses where substantial upregulation of the LDL receptor was observed and thus stimulated LDL receptor expression by a novel mechanism.

  11. Identification of low density lipoprotein as a regulator of Fc receptor-mediated phagocytosis.

    PubMed Central

    Bigler, R D; Khoo, M; Lund-Katz, S; Scerbo, L; Esfahani, M

    1990-01-01

    Optimal expression of the high-affinity Fc receptor for IgG (FcRI) by the human monocyte cell line U-937 requires the presence of low density lipoprotein (LDL), and neither cholesterol nor high density lipoprotein can provide the component necessary for optimal FcRI expression. Here we show that FcR-mediated phagocytosis also requires LDL. U-937 cells were cultured in medium containing interferon gamma and either fetal calf serum (FCS) or delipidated FCS (DLFCS). The phagocytosis of IgG-coated erythrocytes was measured by a colorimetric assay. U-937 cells cultured in DLFCS medium had less than 16% of the phagocytic activity of cells cultured in normal FCS medium. Phagocytosis of IgG-coated erythrocytes could be inhibited 85% by the addition of murine IgG2a myeloma protein (5 micrograms/ml). U-937 cells cultured in DLFCS medium supplemented with pure cholesterol in ethanol (10 micrograms/ml) had only 30% of the phagocytic activity of cells grown in FCS medium. Addition of very low density lipoprotein (0.2 mg of protein per ml) to DLFCS medium also failed to increase phagocytosis. However, the addition of LDL (0.2 mg of protein per ml) to DLFCS medium restored 90% of the phagocytic activity. Since neither pure cholesterol nor very low density lipoprotein restored normal phagocytic function to U-937 cells despite a normalization of cellular cholesterol content, the restoration of phagocytosis observed with LDL replacement cannot be explained by mere delivery of cholesterol by LDL. Thus, LDL is required for the expression of FcRI and FcR-mediated phagocytosis by U-937 cells and may be an important regulator of phagocytic activity of monocytes and macrophages in vivo. PMID:2367519

  12. Inhibitors of cholesterol biosynthesis increase hepatic low-density lipoprotein receptor protein degradation.

    PubMed

    Ness, G C; Zhao, Z; Lopez, D

    1996-01-15

    Inhibitors of cholesterol biosynthesis are believed to lower serum cholesterol levels by enhancing the removal of serum low-density lipoprotein (LDL) by increasing hepatic LDL receptor function. Thus, the effects of several different inhibitors of cholesterol biosynthesis were examined for their effects on the expression of the hepatic LDL receptor in rats. We found that administration of inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase such as lovastatin, pravastatin, fluvastatin, and rivastatin resulted in increased hepatic LDL receptor mRNA levels. Surprisingly, these agents failed to increase levels of immunoreactive LDL receptor protein in rat liver even when the dose and length of treatment were increased. Treatment of rats with zaragozic acid A, an inhibitor of squalene synthase, caused even greater increases in hepatic LDL receptor mRNA levels, but did not increase levels of immunoreactive protein. Further investigation revealed that the rate of degradation of the hepatic LDL receptor was increased in rats given inhibitors of cholesterol biosynthesis. The greatest increase in the rate of degradation was seen in animals treated with zaragozic acid A which caused the largest increase in hepatic LDL receptor mRNA levels. In contrast, hepatic LDL receptor protein was stabilized in cholesterol-fed rats. It appears that increased potential for LDL receptor protein synthesis, reflected in increased mRNA levels, is offset by a corresponding increase in the rate of receptor protein degradation resulting in constant steady-state levels of hepatic LDL receptor protein. These findings are suggestive of increased cycling of the hepatic LDL receptor. This postulated mechanism can provide for enhanced hepatic uptake of lipoproteins without increasing steady-state levels of LDL receptor protein.

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

    PubMed

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

    2016-09-01

    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.

  14. 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

  15. Low-Density Lipoprotein Receptor Contributes to β-Carotene Uptake in the Maternal Liver

    PubMed Central

    Shete, Varsha; Costabile, Brianna K.; Kim, Youn-Kyung; Quadro, Loredana

    2016-01-01

    Vitamin A regulates many essential mammalian biological processes, including embryonic development. β-carotene is the main source of vitamin A in the human diet. Once ingested, it is packaged into lipoproteins, predominantly low-density lipoproteins (LDL), and transported to different sites within the body, including the liver and developing tissues, where it can either be stored or metabolized to retinoids (vitamin A and its derivatives). The molecular mechanisms of β-carotene uptake by the liver or developing tissues remain elusive. Here, we investigated the role of the LDL receptor (LDLr) in β-carotene uptake by maternal liver, placenta and embryo. We administered a single dose of β-carotene to Ldlr+/− and Ldlr−/− pregnant mice via intraperitoneal injection at mid-gestation and monitored the changes in β-carotene content among maternal lipoproteins and the liver, as well as the accumulation of β-carotene in the placental–fetal unit. We showed an abnormal β-carotene distribution among serum lipoproteins and reduced hepatic β-carotene uptake in Ldlr−/− dams. These data strongly imply that LDLr significantly contributes to β-carotene uptake in the adult mouse liver. In contrast, LDLr does not seem to mediate acquisition of β-carotene by the placental–fetal unit. PMID:27916814

  16. A green tea catechin extract upregulates the hepatic low-density lipoprotein receptor in rats.

    PubMed

    Bursill, Christina A; Roach, Paul D

    2007-07-01

    Green tea extracts have hypocholesterolaemic properties in epidemiological and animal intervention studies. Upregulation of the low-density lipoprotein (LDL) receptor may be one mechanism to explain this as it is the main way cholesterol is removed from the circulation. This study aimed to determine if a green tea extract could upregulate the hepatic LDL receptor in vivo in the rat. A green tea extract (GTE) enriched in its anti-oxidant constituents, the catechins, was fed to rats (n = 6) at concentrations of either 0, 0.5, 1.0 or 2.0% (w/w) mixed in with their normal chow along with 0.25% (w/w) cholesterol for 12 days. Administration of the GTE had no effect on plasma total or LDL cholesterol concentrations but high-density lipoprotein significantly increased (41%; p < 0.05). Interestingly, there was a significant increase in LDL receptor binding activity (2.7-fold) and LDL receptor protein (3.4-fold) in the 2% (w/w) treatment group compared to controls. There were also significant reductions in liver total and unesterified cholesterol (40%). Administration of the GTE significantly reduced cholesterol absorption (24%) but did not affect cholesterol synthesis. These results show that, despite no effect on plasma cholesterol, the GTE upregulated the LDL receptor in vivo. This appears to be via a reduction in liver cholesterol concentration and suggests that the green tea extract was able to increase the efflux of cholesterol from liver cells.

  17. Low Density Lipoprotein Receptor Related Proteins as Regulators of Neural Stem and Progenitor Cell Function

    PubMed Central

    Landowski, Lila M.; Young, Kaylene M.

    2016-01-01

    The central nervous system (CNS) is a highly organised structure. Many signalling systems work in concert to ensure that neural stem cells are appropriately directed to generate progenitor cells, which in turn mature into functional cell types including projection neurons, interneurons, astrocytes, and oligodendrocytes. Herein we explore the role of the low density lipoprotein (LDL) receptor family, in particular family members LRP1 and LRP2, in regulating the behaviour of neural stem and progenitor cells during development and adulthood. The ability of LRP1 and LRP2 to bind a diverse and extensive range of ligands, regulate ligand endocytosis, recruit nonreceptor tyrosine kinases for direct signal transduction and signal in conjunction with other receptors, enables them to modulate many crucial neural cell functions. PMID:26949399

  18. Secreted PCSK9 downregulates low density lipoprotein receptor through receptor-mediated endocytosis.

    PubMed

    Qian, Yue-Wei; Schmidt, Robert J; Zhang, Youyan; Chu, Shaoyou; Lin, Aimin; Wang, He; Wang, Xiliang; Beyer, Thomas P; Bensch, William R; Li, Weiming; Ehsani, Mariam E; Lu, Deshun; Konrad, Robert J; Eacho, Patrick I; Moller, David E; Karathanasis, Sotirios K; Cao, Guoqing

    2007-07-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protease that regulates low density lipoprotein receptor (LDLR) protein levels. The mechanisms of this action, however, remain to be defined. We show here that recombinant human PCSK9 expressed in HEK293 cells was readily secreted into the medium, with the prosegment associated with the C-terminal domain. Secreted PCSK9 mediated cell surface LDLR degradation in a concentration- and time-dependent manner when added to HEK293 cells. Accordingly, cellular LDL uptake was significantly reduced as well. When infused directly into C57B6 mice, purified human PCSK9 substantially reduced hepatic LDLR protein levels and resulted in increased plasma LDL cholesterol. When added to culture medium, fluorescently labeled PCSK9 was endocytosed and displayed endosomal-lysosomal intracellular localization in HepG2 cells, as was demonstrated by colocalization with DiI-LDL. PCSK9 endocytosis was mediated by LDLR as LDLR deficiency (hepatocytes from LDLR null mice), or RNA interference-mediated knockdown of LDLR markedly reduced PCSK9 endocytosis. In addition, RNA interference knockdown of the autosomal recessive hypercholesterolemia (ARH) gene product also significantly reduced PCSK9 endocytosis. Biochemical analysis revealed that the LDLR extracellular domain interacted directly with secreted PCSK9; thus, overexpression of the LDLR extracellular domain was able to attenuate the reduction of cell surface LDLR levels by secreted PCSK9. Together, these results reveal that secreted PCSK9 retains biological activity, is able to bind directly to the LDLR extracellular domain, and undergoes LDLR-ARH-mediated endocytosis, leading to accelerated intracellular degradation of the LDLR.

  19. Familial hypercholesterolemia in a rhesus monkey pedigree: molecular basis of low density lipoprotein receptor deficiency.

    PubMed Central

    Hummel, M; Li, Z G; Pfaffinger, D; Neven, L; Scanu, A M

    1990-01-01

    We have recently identified a family of rhesus monkeys with members exhibiting a spontaneous hypercholesterolemia associated with a low density lipoprotein receptor (LDLR) deficiency. By using the polymerase chain reaction, we now show that the affected monkeys are heterozygous for a nonsense mutation in exon 6 of the LDLR gene. This mutation changes the sequence of the codon for amino acid 284 (tryptophan) from TGG to TAG, thereby generating a nonsense codon potentially resulting in a truncated 283-amino acid protein, which needs documentation, however. This G----A mutation also creates a site for the restriction endonuclease Spe I. Using this site as a marker for this nonsense mutation, we have shown that the mutation is present in all of the affected members of the pedigree and absent in unaffected members and that the mutation segregates with the phenotype of spontaneous hypercholesterolemia through three generations. Quantitative analyses of RNA obtained from liver biopsies show that the abundance of the LDLR RNA is also reduced by about 50%. Thus, we have identified a primate model for human familial hypercholesterolemia which will be useful for studying the relationship between the LDLR and lipoprotein metabolism and for assessing the efficacy of diets and drugs in the treatment of human familial hypercholesterolemia. Images PMID:2326270

  20. Purification and Characterization of a Bovine Acetyl Low Density Lipoprotein Receptor

    NASA Astrophysics Data System (ADS)

    Kodama, Tatsuhiko; Reddy, Pranhitha; Kishimoto, Chiharu; Krieger, Monty

    1988-12-01

    The acetyl low density lipoprotein (LDL) receptor is expressed on macrophages and some endothelial cells and mediates macrophage--foam cell formation in culture. A 220-kDa acetyl LDL binding protein was partially purified from bovine liver membranes and was used to make a specific monoclonal antibody. The 220-kDa protein immunoprecipitated by this antibody retained binding activity, and the antibody was used to detect this protein in cells lining bovine liver sinusoids and on the surface of cultured bovine alveolar macrophages. In the human monocytic cell line THP-1, the expression of both acetyl LDL receptor activity and a 220-kDa acetyl LDL binding protein were dramatically induced in parallel after differentiation to a macrophage-like state induced by phorbol ester. The ligand specificity, tissue and cell-type specificity, and coinduction data indicated that this 220-kDa cell-surface binding protein is probably a receptor that mediates acetyl LDL endocytosis. The 220-kDa protein, which was purified 238,000-fold from bovine lung membranes to near homogeneity using monoclonal antibody affinity chromatography, is a trimer of 77-kDa subunits that contain asparagine-linked carbohydrate chains.

  1. Lipopolysaccharide Is Cleared from the Circulation by Hepatocytes via the Low Density Lipoprotein Receptor

    PubMed Central

    Topchiy, Elena; Cirstea, Mihai; Kong, HyeJin Julia; Boyd, John H.; Wang, Yingjin; Russell, James A.; Walley, Keith R.

    2016-01-01

    Sepsis is the leading cause of death in critically ill patients. While decreased Proprotein Convertase Subtilisin/Kexin type 9 (PCSK9) function improves clinical outcomes in murine and human sepsis, the mechanisms involved have not been fully elucidated. We tested the hypothesis that lipopolysaccharide (LPS), the major Gram-negative bacteria endotoxin, is cleared from the circulation by hepatocyte Low Density Lipoprotein Receptors (LDLR)—receptors downregulated by PCSK9. We directly visualized LPS uptake and found that LPS is rapidly taken up by hepatocytes into the cell periphery. Over the course of 4 hours LPS is transported towards the cell center. We next found that clearance of injected LPS from the blood was reduced substantially in Ldlr knockout (Ldlr-/-) mice compared to wild type controls and, simultaneously, hepatic uptake of LPS was also reduced in Ldlr-/- mice. Specifically examining the role of hepatocytes, we further found that primary hepatocytes isolated from Ldlr-/- mice had greatly decreased LPS uptake. In the HepG2 immortalized human hepatocyte cell line, LDLR silencing similarly resulted in decreased LPS uptake. PCSK9 treatment reduces LDLR density on hepatocytes and, therefore, was another independent strategy to test our hypothesis. Incubation with PCSK9 reduced LPS uptake by hepatocytes. Taken together, these findings demonstrate that hepatocytes clear LPS from the circulation via the LDLR and PCSK9 regulates LPS clearance from the circulation during sepsis by downregulation of hepatic LDLR. PMID:27171436

  2. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein.

    PubMed

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L; Varughese, Kottayil I

    2015-11-18

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.

  3. Alpha-2-macroglobulin gene, oxidized low-density lipoprotein receptor-1 locus, and sporadic Alzheimer's disease.

    PubMed

    Colacicco, Anna Maria; Solfrizzi, Vincenzo; D'Introno, Alessia; Capurso, Cristiano; Kehoe, Patrick G; Seripa, Davide; Pilotto, Alberto; Santamato, Andrea; Capurso, Antonio; Panza, Francesco

    2009-09-01

    A total sample of 169 AD patients, and 264 age- and sex-matched unrelated caregivers from Apulia, southern Italy, were genotypized for alpha-2-macroglobulin (A2M) Val1000/Ile single-nucleotide polymorphism (SNP) (rs669), apolipoprotein E (APOE), and SNPs (+1073 and +1071) in the oxidized low-density lipoprotein receptor-1 (OLR1) gene on chromosome 12. A2M allele and genotype frequencies were similar between AD patients and controls, also after stratification for late onset (>/=70 years) and early onset (<70 years) or APOE varepsilon4 status. However, there was evidence in support of LD between the OLR1+1071, the OLR1+1073, and the rs669 SNPs, with T-C-A haplotype being associated with significant increased risk of AD in both the whole sample and when we stratified according to early and late onset AD subjects, with the allelic association with AD predominantly from the OLR1+1073 SNP, further supporting the role of OLR1 as a candidate risk gene for sporadic AD.

  4. Polymorphisms in the oxidized low-density lipoprotein receptor-1 gene and risk of Alzheimer's disease.

    PubMed

    D'Introno, Alessia; Solfrizzi, Vincenzo; Colacicco, Anna M; Capurso, Cristiano; Torres, Francesco; Capurso, Sabrina A; Capurso, Antonio; Panza, Francesco

    2005-03-01

    The +1073 C/T polymorphism of the oxidized low-density lipoprotein receptor-1 (OLR1) gene has been reported to be associated with late-onset Alzheimer's disease, whereas for the +1071 T/A polymorphism no association was found. We genotyped 169 sporadic Alzheimer's disease patients and 264 sex- and age-matched nondemented controls from Southern Italy for OLR1 +1073 C/T and +1071 T/A polymorphisms and for apolipoprotein E and LBP-1c/CP2/LSF. We also performed haplotype analysis. For the +1073 C/T polymorphism, the C allele and the CC genotype have been associated with a higher risk for Alzheimer's disease without apolipoprotein E or CP2 interaction. The two polymorphisms were in linkage disequilibrium, with the haplotype T-C at significant increased risk of developing Alzheimer's disease in the whole sample and in elderly persons 70 years or older. In our population, the +1073 C/T OLR1 polymorphism exhibited a significant association with Alzheimer's disease, further supporting the role of OLR1 as a candidate risk gene for sporadic Alzheimer's disease.

  5. Dietary corn fractions reduce atherogenesis in low-density lipoprotein receptor knockout mice.

    PubMed

    Masisi, Kabo; Le, Khuong; Ghazzawi, Nora; Moghadasian, Mohammed H; Beta, Trust

    2017-01-01

    Accumulating evidence has suggested that intake of whole grains is a protective factor against pathogenesis of coronary artery disease. The exact mechanisms, however, are still not clearly understood. In this study, we hypothesized that adequate intake of corn fractions (aleurone, endosperm and germ) can modify lipid profiles in relation to atherosclerotic lesion development in low-density lipoprotein receptor knockout (LDLr-KO) mice. The purpose of the present study was to investigate the potential cardiovascular benefits of corn fractions in LDLr-KO mice through a number of biomarkers including lipid profile, and morphologic and morphometrical analysis of atherosclerotic lesions in aortic root. Four groups of male LDLr-KO mice were fed with the experimental diets supplemented with (3 treated) or without (control) 5% (wt/wt) of each of corn fractions for 10 weeks. All diets were supplemented with 0.06% (wt/wt) cholesterol. Compared with mice in the control group, atherosclerotic lesions in the aortic roots were significantly reduced (P=.003) in the mice that were fed diet supplemented with aleurone and germ fractions. This effect was associated with significant reductions in plasma total (P=.02) and LDL (P=.03) cholesterol levels, and an increase in fecal cholesterol excretion (P=.04). Furthermore, abdominal fat mass was significantly reduced by consumption of aleurone (P=.03). In summary, the consumption of aleurone and germ may help attenuate atherosclerosis by reducing plasma total and LDL cholesterol levels.

  6. Low Density Lipoprotein Receptor-Related Protein and Apolipoprotein E Expression is Altered in Schizophrenia

    PubMed Central

    Gibbons, Andrew Stuart; Thomas, Elizabeth A.; Scarr, Elizabeth; Dean, Brian

    2010-01-01

    Our recent microarray study reported altered mRNA expression of several low density lipoprotein receptor-related proteins (LRP) associated with the first 4 years following diagnosis with schizophrenia. Whilst this finding is novel, apolipoprotein E (APOE), which mediates its activity through LRPs, has been reported by several studies to be altered in brains of subjects with schizophrenia. We used qPCR to measure the expression of LRP2, LRP4, LRP6, LRP8, LRP10 and LRP12 mRNA in Brodmann's area (BA) 46 of the dorsolateral prefrontal cortex in 15 subjects with short duration of illness schizophrenia (SDS) and 15 pair matched controls. We also used Western blotting to measure APOE protein expression in BA46 from these subjects. Amongst the LRPs examined, LRP10 expression was significantly increased (P = 0.03) and LRP12 was significantly decreased (P < 0.01) in SDS. APOE protein expression was also increased in SDS (P = 0.01). No other marker examined in this study was altered with diagnosis. Our data supports a role for distinct members of the LRP family in the pathology of schizophrenia and adds weight to the hypothesis that aberrant apolipoprotein signaling is involved in the early stages of schizophrenia. PMID:21423430

  7. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein

    NASA Astrophysics Data System (ADS)

    Thakkar, Shraddha; Wang, Xianwei; Khaidakov, Magomed; Dai, Yao; Gokulan, Kuppan; Mehta, Jawahar L.; Varughese, Kottayil I.

    2015-11-01

    Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.

  8. Targeting low-density lipoprotein receptors with protein-only nanoparticles

    NASA Astrophysics Data System (ADS)

    Xu, Zhikun; Céspedes, María Virtudes; Unzueta, Ugutz; Álamo, Patricia; Pesarrodona, Mireia; Mangues, Ramón; Vázquez, Esther; Villaverde, Antonio; Ferrer-Miralles, Neus

    2015-03-01

    Low-density lipoprotein receptors (LDLR) are appealing cell surface targets in drug delivery, as they are expressed in the blood-brain barrier (BBB) endothelium and are able to mediate transcytosis of functionalized drugs for molecular therapies of the central nervous system (CNS). On the other hand, brain-targeted drug delivery is currently limited, among others, by the poor availability of biocompatible vehicles, as most of the nanoparticles under development as drug carriers pose severe toxicity issues. In this context, protein nanoparticles offer functional versatility, easy and cost-effective bioproduction, and full biocompatibility. In this study, we have designed and characterized several chimerical proteins containing different LDLR ligands, regarding their ability to bind and internalize target cells and to self-organize as viral mimetic nanoparticles of about 18 nm in diameter. While the self-assembling of LDLR-binding proteins as nanoparticles positively influences cell penetration in vitro, the nanoparticulate architecture might be not favoring BBB crossing in vivo. These findings are discussed in the context of the use of nanostructured materials as vehicles for the systemic treatment of CNS diseases.

  9. Increased expression of low-density lipoprotein receptors in a Smith-Lemli-Opitz infant with elevated bilirubin levels.

    PubMed

    Ness, G C; Lopez, D; Borrego, O; Gilbert-Barness, E

    1997-01-31

    We report on an infant girl with severe RSH or Smith-Lemli-Opitz syndrome with hyperbilirubinemia. The infant died at age 2 months. Sterol analysis of liver and brain tissues showed marked elevations of 7-dehydrocholesterol with decreased levels of cholesterol. Immunocytochemical analysis demonstrated remarkable increases in low-density lipoprotein (LDL) receptors in these tissues, indicative of a deficiency in available cholesterol for tissue needs.

  10. Peroxisome proliferator-activated receptor-γ regulates the expression and function of very-low-density lipoprotein receptor

    PubMed Central

    Tao, Huan; Aakula, Srikanth; Abumrad, Naji N.

    2010-01-01

    Very-low-density lipoprotein receptor (VLDLR) is a member of the low-density receptor family, highly expressed in adipose tissue, heart, and skeletal muscle. It binds apolipoprotein E-triglyceride-rich lipoproteins and plays a significant role in triglyceride metabolism. PPARγ is a primary regulator of lipid metabolism in adipocytes and controls the expression of an array of genes involved in lipid trafficking in adipocytes. However, it is not known whether VLDLR is also under the control of PPARγ. In this study, we investigated the role of PPARγ in the regulation of VLDLR expression and function in vivo and in vitro. During the differentiation of 3T3-L1 preadipocytes, the levels of VLDLR protein and mRNA increased in parallel with the induction of PPARγ expression and reached maximum in mature adipocytes. Treatment of differentiated adipocytes with PPARγ agonist pioglitazone upregulated VLDLR expression in dose- and time-dependent manners. In contrast, specific inhibition of PPARγ significantly downregulated the protein level of VLDLR. Induction of VLDLR is also demonstrated in vivo in adipose tissue of wild-type (WT) mice treated with pioglitazone. In addition, pioglitazone increased plasma triglyceride-rich lipoprotein clearance and increased epididymal fat mass in WT mice but failed to induce similar effects in vldlr−/− mice. These results were further corroborated by the finding that pioglitazone treatment enhanced adipogenesis and lipid deposition in preadipocytes of WT mice, while its effect in VLDLR-null preadipocytes was significantly blunted. These findings provide direct evidence that VLDLR expression is regulated by PPARγ and contributes in lipid uptake and adipogenesis. PMID:19861583

  11. 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

  12. Serum amyloid A stimulates macrophage foam cell formation via lectin-like oxidized low-density lipoprotein receptor 1 upregulation

    SciTech Connect

    Lee, Ha Young; Kim, Sang Doo; Baek, Suk-Hwan; Choi, Joon Hyuk; Cho, Kyung-Hyun; Zabel, Brian A.; Bae, Yoe-Sik

    2013-03-29

    Highlights: ► SAA induced macrophage foam cell formation. ► SAA stimulated upregulation of lectin-like oxidized low-density lipoprotein receptor 1 (LOX1). ► SAA-induced LOX1 expression and foam cell formation is mediated by JNK/NF-κB signaling. ► HDL-conjugated SAA also stimulates foam cell formation via LOX1 upregulation. ► The finding reveals a novel mechanism of action of SAA in the pathogenesis of atherosclerosis. -- Abstract: Elevated levels of serum amyloid A (SAA) is a risk factor for cardiovascular diseases, however, the role of SAA in the pathophysiology of atherosclerosis remains unclear. Here we show that SAA induced macrophage foam cell formation. SAA-stimulated foam cell formation was mediated by c-jun N-terminal kinase (JNK) signaling. Moreover, both SAA and SAA-conjugated high density lipoprotein stimulated the expression of the important scavenger receptor lectin-like oxidized low-density lipoprotein receptor 1 (LOX1) via nuclear factor-κB (NF-κB). A LOX1 antagonist carrageenan significantly blocked SAA-induced foam cell formation, indicating that SAA promotes foam cell formation via LOX1 expression. Our findings therefore suggest that SAA stimulates foam cell formation via LOX1 induction, and thus likely contributes to atherogenesis.

  13. Homozygous Deletion of the Very Low Density Lipoprotein Receptor Gene Causes Autosomal Recessive Cerebellar Hypoplasia with Cerebral Gyral Simplification

    PubMed Central

    Boycott, Kym M.; Flavelle, Shauna; Bureau, Alexandre; Glass, Hannah C.; Fujiwara, T. Mary; Wirrell, Elaine; Davey, Krista; Chudley, Albert E.; Scott, James N.; McLeod, D. Ross; Parboosingh, Jillian S.

    2005-01-01

    An autosomal recessive syndrome of nonprogressive cerebellar ataxia and mental retardation is associated with inferior cerebellar hypoplasia and mild cerebral gyral simplification in the Hutterite population. An identity-by-descent mapping approach using eight patients from three interrelated Hutterite families localized the gene for this syndrome to chromosome region 9p24. Haplotype analysis identified familial and ancestral recombination events and refined the minimal region to a 2-Mb interval between markers D9S129 and D9S1871. A 199-kb homozygous deletion encompassing the entire very low density lipoprotein receptor (VLDLR) gene was present in all affected individuals. VLDLR is part of the reelin signaling pathway, which guides neuroblast migration in the cerebral cortex and cerebellum. To our knowledge, this syndrome represents the first human lipoprotein receptor malformation syndrome and the second human disease associated with a reelin pathway defect. PMID:16080122

  14. cDNA cloning of the bovine low density lipoprotein receptor: feedback regulation of a receptor mRNA.

    PubMed Central

    Russell, D W; Yamamoto, T; Schneider, W J; Slaughter, C J; Brown, M S; Goldstein, J L

    1983-01-01

    The low density lipoprotein (LDL) receptor belongs to a class of migrant cell surface proteins that mediate endocytosis of macromolecular ligands. No cDNAs for this class of proteins have been isolated to date. In the current paper, we report the isolation of a cDNA clone for the LDL receptor from a bovine adrenal cDNA library. The library was constructed by the Okayama-Berg method from poly(A)+ RNA that had been enriched in receptor mRNA by immunopurification of polysomes. Mixtures of synthetic oligonucleotides encoding the amino acid sequence of two neighboring regions of a single cyanogen bromide fragment were used as hybridization probes to identify a recombinant plasmid containing the LDL receptor cDNA. This plasmid, designated pLDLR-1, contains a 2.8-kilobase (kb) insert that includes a sequence which corresponds to the known amino acid sequence of a 36-residue cyanogen bromide fragment of the receptor. pLDLR-1 hybridized to a mRNA of approximately equal to 5.5 kb in the bovine adrenal gland. This mRNA, like the receptor protein, was 9-fold more abundant in bovine adrenal than in bovine liver. pLDLR-1 cross-hybridized to a mRNA of approximately equal to 5.5 kb in cultured human epidermoid carcinoma A-431 cells. This mRNA was markedly reduced in amount when sterols were added to the culture medium, an observation that explains the previously observed feedback regulation of LDL receptor protein. Southern blot analysis of bovine genomic DNA with 32P-labeled pLDLR-1 revealed a simple pattern of hybridization, consistent with a single-copy gene containing introns. Images PMID:6143315

  15. Ghrelin Receptor Deficiency does not Affect Diet-Induced Atherosclerosis in Low-Density Lipoprotein Receptor-Null Mice

    PubMed Central

    Habegger, Kirk M.; Grant, Erin; Pfluger, Paul Thomas; Perez-Tilve, Diego; Daugherty, Alan; Bruemmer, Dennis; Tschöp, Matthias H.; Hofmann, Susanna M.

    2011-01-01

    Objective: Ghrelin, a stomach-derived, secreted peptide, and its receptor (growth hormone secretagogue receptor, GHSR) are known to modulate food intake and energy homeostasis. The ghrelin system is also expressed broadly in cardiovascular tissues. Since ghrelin has been associated with anti-inflammatory and anti-atherogenic properties, but is also well known to promote obesity and impair glucose metabolism, we investigated whether ghrelin has any impact on the development of atherosclerosis. The hypothesis that endogenous ghrelin signaling may be involved in atherosclerosis has not been tested previously. Methods and Results: We crossed ghrelin receptor knockout mice (GHSr−/−) into a low-density lipoprotein receptor-null (Ldlr−/−) mouse line. In this model, atherosclerotic lesions were promoted by feeding a high-fat, high-cholesterol Western-type diet for 13 months, following a standard protocol. Body composition and glucose homeostasis were similar between Ldlr−/− and Ldlr/GHSR−/−ko mice throughout the study. Absence or presence of GHSr did not alter the apolipoprotein profile changes in response to diet exposure on an LDLRko background. Atherosclerotic plaque volume in the aortic arch and thoracic aorta were also not affected differentially in mice without ghrelin signaling due to GHSR gene disruption as compared to control LDLRko littermates. In light of the associations reported for ghrelin with cardiovascular disease in humans, the lack of a phenotype in these loss-of-function studies in mice suggests no direct role for endogenous ghrelin in either the inhibition or the promotion of diet-induced atherosclerosis. Conclusion: These data indicate that, surprisingly, the complex and multifaceted actions of endogenous ghrelin receptor mediated signaling on the cardiovascular system have minimal direct impact on atherosclerotic plaque progression as based on a loss-of-function mouse model of the disease. PMID:22649381

  16. 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

  17. IDOL stimulates clathrin-independent endocytosis and multivesicular body-mediated lysosomal degradation of the low-density lipoprotein receptor.

    PubMed

    Scotti, Elena; Calamai, Martino; Goulbourne, Chris N; Zhang, Li; Hong, Cynthia; Lin, Ron R; Choi, Jinkuk; Pilch, Paul F; Fong, Loren G; Zou, Peng; Ting, Alice Y; Pavone, Francesco S; Young, Stephen G; Tontonoz, Peter

    2013-04-01

    The low-density lipoprotein receptor (LDLR) is a critical determinant of plasma cholesterol levels that internalizes lipoprotein cargo via clathrin-mediated endocytosis. Here, we show that the E3 ubiquitin ligase IDOL stimulates a previously unrecognized, clathrin-independent pathway for LDLR internalization. Real-time single-particle tracking and electron microscopy reveal that IDOL is recruited to the plasma membrane by LDLR, promotes LDLR internalization in the absence of clathrin or caveolae, and facilitates LDLR degradation by shuttling it into the multivesicular body (MVB) protein-sorting pathway. The IDOL-dependent degradation pathway is distinct from that mediated by PCSK9 as only IDOL employs ESCRT (endosomal-sorting complex required for transport) complexes to recognize and traffic LDLR to lysosomes. Small interfering RNA (siRNA)-mediated knockdown of ESCRT-0 (HGS) or ESCRT-I (TSG101) components prevents IDOL-mediated LDLR degradation. We further show that USP8 acts downstream of IDOL to deubiquitinate LDLR and that USP8 is required for LDLR entry into the MVB pathway. These results provide key mechanistic insights into an evolutionarily conserved pathway for the control of lipoprotein receptor expression and cellular lipid uptake.

  18. mRNA for low density lipoprotein receptor in brain and spinal cord of immature and mature rabbits

    SciTech Connect

    Hofmann, S.L.; Russell, D.W.; Goldstein, J.L.; Brown, M.S.

    1987-09-01

    Hybridization studies with (/sup 32/P)cDNA probes revealed detectable amounts of mRNA for the low density lipoprotein (LDL) receptor in the central nervous system (CNS) of rabbits. mRNA levels were highest in the medulla/pons and spinal cord, which were the most heavily myelinated regions that were studied. Lower, but detectable levels were present in cerebral cortex, hypothalamus, thalamus, midbrain, and cerebellum. In the medulla/pons and spinal cord, the levels of receptor mRNA were in a range comparable to that detected in the liver. The levels of receptor mRNA in whole brain were constant from 3 days of age to adulthood and, thus, did not vary in proportion to the rate of myelin synthesis. LDL receptor mRNA in the CNS was produced by the same gene that produced the liver and adrenal mRNA as revealed by the demonstration of a deletion in the neural mRNA of Watanabe-heritable hyperlipidemic (WHHL) rabbits identical to the deletion in the LDL receptor gene of these mutant animals. Using antibodies directed against the bovine LDL receptor, the authors showed that LDL receptor protein is present in the medulla/pons of adult cows. The cell types that express LDL receptors in the CNS and the functions of these receptors are unknown.

  19. Antagonism of Secreted PCSK9 Increases Low Density Lipoprotein Receptor Expression in HepG2 Cells

    SciTech Connect

    McNutt, Markey C.; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R.; Horton, Jay D.; Lagace, Thomas A.

    2009-07-10

    PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

  20. Antagonism of secreted PCSK9 increases low density lipoprotein receptor expression in HepG2 cells.

    PubMed

    McNutt, Markey C; Kwon, Hyock Joo; Chen, Chiyuan; Chen, Justin R; Horton, Jay D; Lagace, Thomas A

    2009-04-17

    PCSK9 is a secreted protein that degrades low density lipoprotein receptors (LDLRs) in liver by binding to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR. It is not known whether PCSK9 causes degradation of LDLRs within the secretory pathway or following secretion and reuptake via endocytosis. Here we show that a mutation in the LDLR EGF-A domain associated with familial hypercholesterolemia, H306Y, results in increased sensitivity to exogenous PCSK9-mediated cellular degradation because of enhanced PCSK9 binding affinity. The crystal structure of the PCSK9-EGF-A(H306Y) complex shows that Tyr-306 forms a hydrogen bond with Asp-374 in PCSK9 at neutral pH, which strengthens the interaction with PCSK9. To block secreted PCSK9 activity, LDLR (H306Y) subfragments were added to the medium of HepG2 cells stably overexpressing wild-type PCSK9 or gain-of-function PCSK9 mutants associated with hypercholesterolemia (D374Y or S127R). These subfragments blocked secreted PCSK9 binding to cell surface LDLRs and resulted in the recovery of LDLR levels to those of control cells. We conclude that PCSK9 acts primarily as a secreted factor to cause LDLR degradation. These studies support the concept that pharmacological inhibition of the PCSK9-LDLR interaction extracellularly will increase hepatic LDLR expression and lower plasma low density lipoprotein levels.

  1. [PCSK9: Structure and function. PCSK9 and low-density lipoprotein receptor. Mutations and their effects].

    PubMed

    Pedro-Botet, Juan; Badimón, Lina

    2016-05-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein receptor (LDLr) and then targets it for lysosomal degradation in cells, thus preventing LDLr from recycling back to the hepatocyte surface, with a consequent decrease in LDLr density and clearance of LDL-cholesterol (LDLc). There have been reports of both gain-of-function mutations in the PCSK9 gene that cause a marked increase in LDLc conentrations and loss-of-function mutations, which lead to modest reductions in LDLc and low rates of coronary heart disease. The PCSK9 gene has become a promising therapeutic target to reduce blood cholesterol levels. This review discusses the most interesting recent data on PCSK9 regulation and its molecular function in cholesterol homeostasis.

  2. Characterization of the role of EGF-A of low density lipoprotein receptor in PCSK9 binding.

    PubMed

    Gu, Hong-mei; Adijiang, Ayinuer; Mah, Matthew; Zhang, Da-wei

    2013-12-01

    Proprotein convertase subtilisin kexin-like 9 (PCSK9) promotes the degradation of low density lipoprotein receptor (LDLR) and plays an important role in regulating plasma LDL-cholesterol levels. We have shown that the epidermal growth factor precursor homology domain A (EGF-A) of the LDLR is critical for PCSK9 binding at the cell surface (pH 7.4). Here, we further characterized the role of EGF-A in binding of PCSK9 to the LDLR. We found that PCSK9 efficiently bound to the LDLR but not to other LDLR family members. Replacement of EGF-A in the very low density lipoprotein receptor (VLDLR) with EGF-A of the LDLR promoted the degradation of the mutant VLDLR induced by PCSK9. Furthermore, we found that PCSK9 bound to recombinant EGF-A in a pH-dependent manner with stronger binding at pH 6.0. We also identified amino acid residues in EGF-A of the LDLR important for PCSK9 binding. Mutations G293H, D299V, L318D, and L318H reduced PCSK9 binding to the LDLR at neutral pH without effect at pH 6.0, while mutations R329P and E332G reduced PCSK9 binding at both pH values. Thus, our findings reveal that EGF-A of the LDLR is critical for PCSK9 binding at the cell surface (neutral pH) and at the acidic endosomal environment (pH 6.0), but different determinants contribute to efficient PCSK9 binding in different pH environments.

  3. Characterization of the role of EGF-A of low density lipoprotein receptor in PCSK9 binding

    PubMed Central

    Gu, Hong-mei; Adijiang, Ayinuer; Mah, Matthew; Zhang, Da-wei

    2013-01-01

    Proprotein convertase subtilisin kexin-like 9 (PCSK9) promotes the degradation of low density lipoprotein receptor (LDLR) and plays an important role in regulating plasma LDL-cholesterol levels. We have shown that the epidermal growth factor precursor homology domain A (EGF-A) of the LDLR is critical for PCSK9 binding at the cell surface (pH 7.4). Here, we further characterized the role of EGF-A in binding of PCSK9 to the LDLR. We found that PCSK9 efficiently bound to the LDLR but not to other LDLR family members. Replacement of EGF-A in the very low density lipoprotein receptor (VLDLR) with EGF-A of the LDLR promoted the degradation of the mutant VLDLR induced by PCSK9. Furthermore, we found that PCSK9 bound to recombinant EGF-A in a pH-dependent manner with stronger binding at pH 6.0. We also identified amino acid residues in EGF-A of the LDLR important for PCSK9 binding. Mutations G293H, D299V, L318D, and L318H reduced PCSK9 binding to the LDLR at neutral pH without effect at pH 6.0, while mutations R329P and E332G reduced PCSK9 binding at both pH values. Thus, our findings reveal that EGF-A of the LDLR is critical for PCSK9 binding at the cell surface (neutral pH) and at the acidic endosomal environment (pH 6.0), but different determinants contribute to efficient PCSK9 binding in different pH environments. PMID:24103783

  4. Adaptor protein disabled-2 modulates low density lipoprotein receptor synthesis in fibroblasts from patients with autosomal recessive hypercholesterolaemia.

    PubMed

    Eden, Emily R; Sun, Xi-Ming; Patel, Dilipkumar D; Soutar, Anne K

    2007-11-15

    Autosomal recessive hypercholesterolaemia (ARH), characterized clinically by severe inherited hypercholesterolaemia, is caused by recessive null mutations in LDLRAP1 (formerly ARH). Immortalized lymphocytes and monocyte-macrophages, and presumably hepatocytes, from ARH patients fail to take up and degrade plasma low density lipoproteins (LDL) because they lack LDLRAP1, a cargo-specific adaptor required for clathrin-mediated endocytosis of the LDL receptor. Surprisingly, LDL-receptor function is normal in ARH patients' skin fibroblasts in culture. Disabled-2 (Dab2) has been implicated previously in clathrin-mediated internalization of LDL-receptor family members, and we show here that Dab2 is highly expressed in skin fibroblasts, but not in lymphocytes. SiRNA-depletion of Dab2 profoundly reduced LDL-receptor activity in ARH fibroblasts as a result of profound reduction in LDL-receptor protein, but not mRNA; heterologous expression of murine Dab2 reversed this effect. In contrast, LDL-receptor protein content was unchanged in Dab-2-depleted control cells. Incorporation of 35S-labelled amino acids into LDL receptor protein revealed a corresponding apparent reduction in accumulation of newly synthesized LDL-receptor protein on depletion of Dab2 in ARH, but not in control, cells. This reduction in LDL-receptor protein in Dab2-depleted ARH cells could not be reversed by treatment of the cells with proteasomal or lysosomal inhibitors. Thus, we propose a novel role for Dab2 in ARH fibroblasts, where it is apparently required to allow normal translation of LDL receptor mRNA.

  5. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis

    SciTech Connect

    Williams, K.J.; Vallabhajosula, S.; Rahman, I.U.; Donnelly, T.M.; Parker, T.S.; Weinrauch, M.; Goldsmith, S.J.

    1988-01-01

    The metabolism of infused /sup 111/In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t/sub 1/2/) for clearance of /sup 111/In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits. By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue sores. Disappearance of excess plasma cholesterol was > 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative ..gamma.. camera imaging, hepatic trapping of /sup 111/In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance. Aortic uptake of /sup 111/In was < 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, the results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia.

  6. Silencing Triggering Receptors Expressed on Myeloid Cells-1 Impaired the Inflammatory Response to Oxidized Low-Density Lipoprotein in Macrophages.

    PubMed

    Li, Houxuan; Hong, Feifei; Pan, Shengbo; Lei, Lang; Yan, Fuhua

    2016-02-01

    Atherosclerosis is a chronic progressive inflammatory disease characterized by the accumulation of lipid contents in arterial walls. Previous studies suggest participation of Toll-like receptors (TLRs) in lipid deposition and inflammatory response in vascular wall. The triggering receptor expressed on myeloid cells 1 (TREM-1) is a cell surface receptor of the immunoglobulin superfamily, which amplifies signal transduction of TLR pathway and enhances immune response to microbial infections. The aim of the present study was to investigate the effect of the oxidized low-density lipoprotein (oxLDL) on the expression of the TREM-1, as well as its engagement in proinflammatory cytokine production and foam cell formation in RAW264.7 mice macrophages. oxLDL enhanced TREM-1 and TLR-4, but not TLR-2 gene expression in macrophages; furthermore, silencing TREM-1 expression by short hairpin interfering RNA inhibited lipid phagocytosis and proinflammatory tumor necrosis factor-α (TNF-α) as well as interleukin-6 (IL-6) production in macrophages; moreover, application of synthetic antagonist, LP-17 polypeptide, reduced IL-6 production upon oxLDL stimulation in vitro and in vivo. In conclusion, in macrophages, oxLDL enhanced expression of TREM-1, which amplifies the innate immune response of TLR pathway; activation of TREM-1 contributes to atherogenesis process by enhancing proinflammatory cytokine production and foam cell formation.

  7. Prickly pear (Opuntia sp.) pectin reverses low density lipoprotein receptor suppression induced by a hypercholesterolemic diet in guinea pigs.

    PubMed

    Fernandez, M L; Lin, E C; Trejo, A; McNamara, D J

    1992-12-01

    The effects of prickly pear pectin on plasma LDL metabolism were investigated by feeding guinea pigs either a diet containing 15 g/100 g lard and 0.25 g/100 g cholesterol (LC diet) or the LC diet in which cellulose was partially replaced (2.5 g/100 g) by prickly pear pectin (LC-P diet). The LC-P diet lowered plasma LDL cholesterol concentrations by 33% (P < 0.001). Low density lipoprotein composition was modified by intake of prickly pear pectin; the relative percentages of free and esterified cholesterol were lower and triglycerides were higher in LDL from animals fed the LC-P diet (P < 0.05). Intake of prickly pear pectin did not affect hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity; however, hepatic free and esterified cholesterol concentrations were lowered by 46 and 64%, respectively. Hepatic apolipoprotein B/E receptor expression (Bmax) was 60% higher in animals fed the LC-P diet (P < 0.01). Similar to the in vitro data, receptor-mediated LDL fractional catabolic rates were 190% higher in animals fed the LC-P diet (P < 0.05), whereas apolipoprotein LDL flux rates were not affected. Apolipoprotein LDL pool size and fractional catabolic rates exhibited a significant correlation (r = -0.52, P < 0.01). These data indicate that an increase in apolipoprotein B/E receptor expression is a major metabolic response by which intake of prickly pear pectin decreases plasma LDL concentrations.

  8. A two-step binding model of PCSK9 interaction with the low density lipoprotein receptor.

    PubMed

    Yamamoto, Taichi; Lu, Christine; Ryan, Robert O

    2011-02-18

    PCSK9 (proprotein convertase subtilisin-like/kexin type 9) is an emerging target for pharmaceutical intervention. This multidomain protein interacts with the LDL receptor (LDLR), promoting receptor degradation. Insofar as PCSK9 inhibition induces a decrease in plasma cholesterol levels, understanding the nature of the binding interaction between PCSK9 and the LDLR is of critical importance. In this study, the ability of PCSK9 to compete with apoE3 N-terminal domain-containing reconstituted HDL for receptor binding was examined. Whereas full-length PCSK9 was an effective competitor, the N-terminal domain (composed of the prodomain and catalytic domain) was not. Surprisingly, the C-terminal domain (CT domain) of PCSK9 was able to compete. Using a direct binding interaction assay, we show that the PCSK9 CT domain bound to the LDLR in a calcium-dependent manner and that co-incubation with the prodomain and catalytic domain had no effect on this binding. To further characterize this interaction, two LDLR fragments, the classical ligand-binding domain (LBD) and the EGF precursor homology domain, were expressed in stably transfected HEK 293 cells and isolated. Binding assays showed that the PCSK9 CT domain bound to the LBD at pH 5.4. Thus, CT domain interaction with the LBD of the LDLR at endosomal pH constitutes a second step in the PCSK9-mediated LDLR binding that leads to receptor degradation.

  9. Disrupted recycling of the low density lipoprotein receptor by PCSK9 is not mediated by residues of the cytoplasmic domain.

    PubMed

    Strøm, Thea Bismo; Holla, Øystein L; Tveten, Kristian; Cameron, Jamie; Berge, Knut Erik; Leren, Trond P

    2010-09-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) post-translationally regulates the number of cell-surface low density lipoprotein receptors (LDLR). This is accomplished by the ability of PCSK9 to mediate degradation of the LDLR. The underlying mechanism involves binding of secreted PCSK9 to the epidermal growth factor-like repeat A of the extracellular domain of the LDLR at the cell surface, followed by lysosomal degradation of the internalized LDLR:PCSK9 complex. However, the mechanism by which the normal recycling of the LDLR is disrupted by PCSK9, remains to be determined. In this study we have investigated the role of the cytoplasmic domain of the LDLR for this process. This has been done by studying the ability of a mutant LDLR (K811X-LDLR) which lacks the cytoplasmic domain, to be degraded by PCSK9. We show that this mutant receptor is degraded by PCSK9. Thus, the machinery which directs the LDLR:PCSK9 complex to the lysosomes for degradation, does not interact with the cytoplasmic domain of the LDLR.

  10. The modular adaptor protein autosomal recessive hypercholesterolemia (ARH) promotes low density lipoprotein receptor clustering into clathrin-coated pits.

    PubMed

    Garuti, Rita; Jones, Christopher; Li, Wei-Ping; Michaely, Peter; Herz, Joachim; Gerard, Robert D; Cohen, Jonathan C; Hobbs, Helen H

    2005-12-09

    Autosomal recessive hypercholesterolemia is characterized by a cell type-specific defect in low density lipoprotein receptor (LDLR) endocytosis. LDLR-mediated uptake of LDL is impaired in the liver, but not in fibroblasts of subjects with this disorder. The disease is caused by mutations in ARH, which encodes a putative adaptor protein that interacts with the cytoplasmic tail of the LDLR, phospholipids, and two components of the clathrin endocytic machinery, clathrin and adaptor protein-2 (AP-2) in vitro. To determine the physiological relevance of these interactions, we examined the effect of mutations in the ARH on LDLR location and function in polarized hepatocytes (WIF-B). The integrity of the FDNPVY sequence in the LDLR cytoplasmic tail was required for ARH-associated LDLR clustering into clathrin-coated pits. The phosphotyrosine binding domain of ARH plus either the clathrin box or the AP-2 binding region were required for both clustering and internalization of the LDLR. Parallel studies performed in vivo with the same recombinant forms of ARH in livers of Arh(-/-) mice confirmed the relevance of the cell culture findings. These results demonstrate that ARH must bind the LDLR tail and either clathrin or AP-2 to promote receptor clustering and internalization of LDL.

  11. Significance of the variant and full-length forms of the very low density lipoprotein receptor in brain.

    PubMed

    Nakamura, Y; Yamamoto, M; Kumamaru, E

    2001-12-20

    The very low density lipoprotein receptor (VLDLR) is a newly described receptor which binds to apolipoprotein E (apoE) specifically. The authors designed a synthetic peptide of 17 amino acids representing the N-terminus of the putative first ligand binding domain of human VLDLR, this being a unique domain for VLDLR. When the synthetic peptide was used as the antigen, two different monoclonal antibodies were obtained (anti-VLDLR1 and anti-VLDLR2). Expressional cloning revealed that anti-VLDLR1 recognized the variant form of VLDLR which lacks 84 bp of O-linked sugar domain and anti-VLDLR2 recognized the full length form of VLDLR. The variant VLDLR was expressed in neuroblasts as well as matrix cells and Cajal-Retzius cells in the early stages of the developing human brain; later its expression was sequentially found in glioblasts, astrocytes, oligodendrocytes and finally in myelin. The expression of a full length form of VLDLR was detected in senile plaques and some neurons and satellite glia in aged and Alzheimer brains. This suggests that the variant VLDLR is important for the developing human brain and the full length VLDLR has modified functions in aged and Alzheimer brains.

  12. LRP6 protein regulates low density lipoprotein (LDL) receptor-mediated LDL uptake.

    PubMed

    Ye, Zhi-jia; Go, Gwang-Woong; Singh, Rajvir; Liu, Wenzhong; Keramati, Ali Reza; Mani, Arya

    2012-01-06

    Genetic variations in LRP6 gene are associated with high serum LDL cholesterol levels. We have previously shown that LDL clearance in peripheral B-lymphocytes of the LRP6(R611C) mutation carriers is significantly impaired. In this study we have examined the role of wild type LRP6 (LRP6(WT)) and LRP6(R611C) in LDL receptor (LDLR)-mediated LDL uptake. LDL binding and uptake were increased when LRP6(WT) was overexpressed and modestly reduced when it was knocked down in LDLR-deficient CHO (ldlA7) cells. These findings implicated LRP6 in LDLR-independent cellular LDL binding and uptake. However, LRP6 knockdown in wild type CHO cells resulted in a much greater decline in LDL binding and uptake compared with CHO-ldlA7 cells, suggesting impaired function of the LDLR. LDLR internalization was severely diminished when LRP6 was knocked down and was restored after LRP6 was reintroduced. Further analysis revealed that LRP6(WT) forms a complex with LDLR, clathrin, and ARH and undergoes a clathrin-mediated internalization after stimulation with LDL. LDLR and LRP6 internalizations as well as LDL uptake were all impaired in CHO-k1 cells expressing LRP6(R611C). These studies identify LRP6 as a critical modulator of receptor-mediated LDL endocytosis and introduce a mechanism by which variation in LRP6 may contribute to high serum LDL levels.

  13. Low density lipoprotein receptor-independent hepatic uptake of a synthetic, cholesterol-scavenging lipoprotein: implications for the treatment of receptor-deficient atherosclerosis.

    PubMed Central

    Williams, K J; Vallabhajosula, S; Rahman, I U; Donnelly, T M; Parker, T S; Weinrauch, M; Goldsmith, S J

    1988-01-01

    The metabolism of infused 111In-labeled phospholipid liposomes was examined in Watanabe heritable hyperlipidemic (WHHL) rabbits, which lack low density lipoprotein (LDL) receptors, and in normal control rabbits. The half-times (t1/2) for clearance of 111In and excess phospholipid from plasma were 20.8 +/- 0.9 hr and 20.3 +/- 4.6 hr in WHHL and 20.0 +/- 0.8 hr and 19.6 +/- 2.2 hr in the normal rabbits (means +/- SEM; n = 4). By 6 hr postinfusion, the plasma concentration of unesterified cholesterol increased by 2.2 +/- 0.23 mmol/liter in WHHL and 2.1 +/- 0.04 mmol/liter in normal rabbits, presumably reflecting mobilization of tissue stores. Disappearance of excess plasma cholesterol was greater than 90% complete in both groups of rabbits by 70 hr postinfusion. By quantitative gamma camera imaging, hepatic trapping of 111In-labeled liposomes over time was indistinguishable between the two groups. At autopsy, the liver was the major organ of clearance, acquiring 22.0% +/- 1.7% (WHHL) and 16.8% +/- 1.0% (normal of total 111In. Aortic uptake of 111In was less than 0.02%. Thus, mobilization of cholesterol and hepatic uptake of phospholipid liposomes do not require LDL receptors. Because phospholipid infusions produce rapid substantial regression of atherosclerosis in genetically normal animals, our results suggest that phospholipid liposomes or triglyceride phospholipid emulsions (e.g., Intralipid) might reduce atherosclerosis in WHHL rabbits and in humans with familial hypercholesterolemia. PMID:3422421

  14. Age- and sex-related differences in extra-hepatic low-density lipoprotein receptor.

    PubMed

    Segatto, Marco; Trapani, Laura; Marino, Maria; Pallottini, Valentina

    2011-10-01

    To determine whether differences in LDLr behavior in extra-hepatic tissues and whether extra-hepatic receptors could differentially contribute to cholesterol homeostasis under physiological conditions, we evaluated the presence and regulation of LDLr from both a gender and an aging perspective. We used the brain cortex, the gastrocnemius, and the heart ventricle of 3- and 12-month-old male and female rats. We observed a protein decrease of total LDLr in 12-month-old female rat brains that was completely restored by 17-β estradiol treatment. In the gastrocnemius, LDLr accumulates in the skeletal muscle in both male and female aged rats as a precursor probably due to a glycosylation impairment. In the heart, no modifications were observed in either older rats or rats of a specific gender. These data highlight a tissue-specific dysregulation of LDLr that is age- and gender-dependent.

  15. Ethanol extract of propolis protects endothelial cells from oxidized low density lipoprotein-induced injury by inhibiting lectin-like oxidized low density lipoprotein receptor-1-mediated oxidative stress.

    PubMed

    Fang, Yongqi; Li, Jinguo; Ding, Mingde; Xu, Xiaoyan; Zhang, Jiajun; Jiao, Peng; Han, Ping; Wang, Jiafu; Yao, Shutong

    2014-12-01

    Lectin-like oxidized low density lipoprotein receptor-1 (LOX-1), as the primary oxidized low-density lipoprotein (ox-LDL) receptor on endothelial cells, plays a crucial role in endothelial injury, which is a driving force in the initiation and development of atherosclerosis. Our previous studies have shown that ethanol extract of propolis (EEP) promotes reverse cholesterol transport and inhibits atherosclerotic lesion development. However, the protective effects of EEP against ox-LDL-induced injury in endothelial cells and the underlying mechanisms are still unknown. This study was designed to test the hypothesis that EEP attenuates ox-LDL-induced endothelial oxidative injury via modulation of LOX-1-mediated oxidative stress. Our results showed that exposure of human umbilical vein endothelial cells (HUVECs) to ox-LDL (100 mg/L) led to the decrease in cell viability and increase in lactate dehydrogenase (LDH) release, caspase-3 activation, and apoptosis, whereas pretreatment with EEP (7.5, 15 and 30 mg/L) protected against such damages in a dose-dependent manner. In addition, EEP mitigated ox-LDL uptake by HUVECs and attenuated ox-LDL-upregulated LOX-1 expression both at the mRNA and protein levels. Moreover, EEP suppressed the ox-LDL-induced oxidative stress as assessed by decreased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation, reactive oxygen species (ROS), and malondialdehyde (MDA) generation as well as increased antioxidant enzyme activities. Similar results were observed in the anti-LOX-1 antibody or diphenyleneiodonium (DPI)-pretreated HUVECs. These data indicate that EEP may protect HUVECs from ox-LDL-induced injury and that the mechanism at least partially involves its ability to inhibit endothelial LOX-1 upregulation and subsequent oxidative stress.

  16. Low-density Lipoprotein Receptor-related Proteins in a Novel Mechanism of Axon Guidance and Peripheral Nerve Regeneration.

    PubMed

    Landowski, Lila M; Pavez, Macarena; Brown, Lachlan S; Gasperini, Robert; Taylor, Bruce V; West, Adrian K; Foa, Lisa

    2016-01-15

    The low-density lipoprotein receptor-related protein receptors 1 and 2 (LRP1 and LRP2) are emerging as important cell signaling mediators in modulating neuronal growth and repair. We examined whether LRP1 and LRP2 are able to mediate a specific aspect of neuronal growth: axon guidance. We sought to identify LRP1 and LRP2 ligands that could induce axonal chemoattraction, which might have therapeutic potential. Using embryonic sensory neurons (rat dorsal root ganglia) in a growth cone turning assay, we tested a range of LRP1 and LRP2 ligands for the ability to guide growth cone navigation. Three ligands were chemorepulsive: α-2-macroglobulin, tissue plasminogen activator, and metallothionein III. Conversely, only one LRP ligand, metallothionein II, was found to be chemoattractive. Chemoattraction toward a gradient of metallothionein II was calcium-dependent, required the expression of both LRP1 and LRP2, and likely involves further co-receptors such as the tropomyosin-related kinase A (TrkA) receptor. The potential for LRP-mediated chemoattraction to mediate axonal regeneration was examined in vivo in a model of chemical denervation in adult rats. In these in vivo studies, metallothionein II was shown to enhance epidermal nerve fiber regeneration so that it was complete within 7 days compared with 14 days in saline-treated animals. Our data demonstrate that both LRP1 and LRP2 are necessary for metallothionein II-mediated chemotactic signal transduction and that they may form part of a signaling complex. Furthermore, the data suggest that LRP-mediated chemoattraction represents a novel, non-classical signaling system that has therapeutic potential as a disease-modifying agent for the injured peripheral nervous system.

  17. Dysregulation of the Low-Density Lipoprotein Receptor Pathway Is Involved in Lipid Disorder-Mediated Organ Injury

    PubMed Central

    Zhang, Yang; Ma, Kun Ling; Ruan, Xiong Zhong; Liu, Bi Cheng

    2016-01-01

    The low-density lipoprotein receptor (LDLR) pathway is a negative feedback system that plays important roles in the regulation of plasma and intracellular cholesterol homeostasis. To maintain a cholesterol homeostasis, LDLR expression is tightly regulated by sterol regulatory element-binding protein-2 (SREBP-2) and SREBP cleavage-activating protein (SCAP) in transcriptional level and by proprotein convertase subtilisin/kexin type 9 (PCSK9) in posttranscriptional level. The dysregulation of LDLR expression results in abnormal lipid accumulation in cells and tissues, such as vascular smooth muscle cells, hepatic cells, renal mesangial cells, renal tubular cells and podocytes. It has been demonstrated that inflammation, renin-angiotensin system (RAS) activation, and hyperglycemia induce the disruption of LDLR pathway, which might contribute to lipid disorder-mediated organ injury (atherosclerosis, non-alcoholic fatty liver disease, kidney fibrosis, etc). The mammalian target of rapamycin (mTOR) pathway is a critical mediator in the disruption of LDLR pathway caused by pathogenic factors. The mTOR complex1 activation upregulates LDLR expression at the transcriptional and posttranscriptional levels, consequently resulting in lipid deposition. This paper mainly reviews the mechanisms for the dysregulation of LDLR pathway and its roles in lipid disorder-mediated organ injury under various pathogenic conditions. Understanding these mechanisms leading to the abnormality of LDLR expression contributes to find potential new drug targets in lipid disorder-mediated diseases. PMID:27019638

  18. Low density lipoprotein receptor-related protein 1 mediated endocytosis of β1-integrin influences cell adhesion and cell migration.

    PubMed

    Rabiej, Verena K; Pflanzner, Thorsten; Wagner, Timo; Goetze, Kristina; Storck, Steffen E; Eble, Johannes A; Weggen, Sascha; Mueller-Klieser, Wolfgang; Pietrzik, Claus U

    2016-01-01

    The low density lipoprotein receptor-related protein 1 (LRP1) has been shown to interact with β1-integrin and regulate its surface expression. LRP1 knock-out cells exhibit altered cytoskeleton organization and decreased cell migration. Here we demonstrate coupled endocytosis of LRP1 and β1-integrin and the involvement of the intracellular NPxY2 motif of LRP1 in this process. Mouse embryonic fibroblasts harboring a knock in replacement of the NPxY2 motif of LRP1 by a multiple alanine cassette (AAxA) showed elevated surface expression of β1-integrin and decreased β1-integrin internalization rates. As a consequence, cell spreading was altered and adhesion rates were increased in our cell model. Cells formed more focal adhesion complexes, whereby in vitro cell migration rates were decreased. Similar results could be observed in a corresponding mouse model, the C57Bl6 LRP1 NPxYxxL knock in mice, therefore, the biochemistry of cellular adhesion was altered in primary cortical neurons. In vivo cell migration experiments demonstrated a disturbance of neuroblast cell migration along the rostral migratory stream. In summary, our results indicate that LRP1 interacts with β1-integrin mediating integrin internalization and thus correlates with downstream signaling of β1-integrin such as focal adhesion dynamics. Consequently, the disturbance of this interaction resulted in a dysfunction in in vivo and in vitro cell adhesion and cell migration.

  19. Normal sorting but defective endocytosis of the low density lipoprotein receptor in mice with autosomal recessive hypercholesterolemia.

    PubMed

    Jones, Christopher; Hammer, Robert E; Li, Wei-Ping; Cohen, Jonathan C; Hobbs, Helen H; Herz, Joachim

    2003-08-01

    Autosomal recessive hypercholesterolemia (ARH) is a genetic form of hypercholesterolemia that clinically resembles familial hypercholesterolemia (FH). As in FH, the rate of clearance of circulating low density lipoprotein (LDL) by the LDL receptor (LDLR) in the liver is markedly reduced in ARH. Unlike FH, LDL uptake in cultured fibroblasts from ARH patients is normal or only slightly impaired. The gene defective in ARH encodes a putative adaptor protein that has been implicated in linking the LDLR to the endocytic machinery. To determine the role of ARH in the liver, ARH-deficient mice were developed. Plasma levels of LDL-cholesterol were elevated in the chow-fed Arh-/- mice (83 +/- 8 mg/dl versus 68 +/- 8 mg/dl) but were lower than those of mice expressing no LDLR (Ldlr-/-) (197 +/- 8 mg/dl). Cholesterol feeding elevated plasma cholesterol levels in both strains. The fractional clearance rate of radiolabeled LDL was reduced to similar levels in the Arh-/- and Ldlr-/- mice, whereas the rate of removal of alpha2-macroglobulin by the LDLR-related protein, which also interacts with ARH, was unchanged. Immunolocalization studies revealed that a much greater proportion of immunodetectable LDLR, but not LDLR-related protein, was present on the sinusoidal surface of hepatocytes in the Arh-/- mice. Taken together, these results are consistent with ARH playing a critical and specific role in LDLR endocytosis in the liver.

  20. Ultrasound-targeted microbubble destruction improves the low density lipoprotein receptor gene expression in HepG{sub 2} cells

    SciTech Connect

    Guo Dongping; Li Xiaoyu; Sun, Ping; Tang Yibo; Chen Xiuying; Chen Qi; Fan Leming . E-mail: lmfan@njmu.edu.cn; Zang Bin; Shao Lizheng; Li Xiaorong

    2006-05-05

    Ultrasound-targeted microbubble destruction had been employed in gene delivery and promised great potential. Liver has unique features that make it attractive for gene therapy. However, it poses formidable obstacles to hepatocyte-specific gene delivery. This study was designed to test the efficiency of therapeutic gene transfer and expression mediated by ultrasound/microbubble strategy in HepG{sub 2} cell line. Air-filled albumin microbubbles were prepared and mixed with plasmid DNA encoding low density lipoprotein receptor (LDLR) and green fluorescent protein. The mixture of the DNA and microbubbles was administer to cultured HepG{sub 2} cells under variable ultrasound conditions. Transfection rate of the transferred gene and cell viability were assessed by FACS analysis, confocal laser scanning microscopy, Western blot analysis and Trypan blue staining. The result demonstrated that microbubbles with ultrasound irradiation can significantly elevate exogenous LDLR gene expression and the expressed LDLRs were functional and active to uptake their ligands. We conclude that ultrasound-targeted microbubble destruction has the potential to promote safe and efficient LDLR gene transfer into hepatocytes. With further refinement, it may represent an effective nonviral avenue of gene therapy for liver-involved genetic diseases.

  1. Common genetic variation within the Low-Density Lipoprotein Receptor-Related Protein 6 and late-onset Alzheimer's disease

    PubMed Central

    De Ferrari, Giancarlo V.; Papassotiropoulos, Andreas; Biechele, Travis; Wavrant De-Vrieze, Fabienne; Avila, Miguel E.; Major, Michael B.; Myers, Amanda; Sáez, Katia; Henríquez, Juan P.; Zhao, Alice; Wollmer, M. Axel; Nitsch, Roger M.; Hock, Christoph; Morris, Chris M.; Hardy, John; Moon, Randall T.

    2007-01-01

    Genome-wide linkage studies have defined a broad susceptibility region for late-onset Alzheimer's disease on chromosome 12, which contains the Low-Density Lipoprotein Receptor-Related Protein 6 (LRP6) gene, a coreceptor for Wnt signaling. Here, we report the association between common LRP6 variants and late-onset Alzheimer's disease in a multicenter case-control series as well as in a large family-based series ascertained by the National Institute of Mental Health–National Institute on Aging Genetics Initiative. As shown in the genome-wide linkage studies, our association depends mainly on apolipoprotein E-ε4 (APOE-ε4) carrier status. Haplotype tagging single-nucleotide polymorphisms (SNPs) with a set of seven allelic variants of LRP6 identified a putative risk haplotype, which includes a highly conserved coding sequence SNP: Ile-1062 → Val. Functional analyses revealed that the associated allele Val-1062, an allele previously linked to low bone mass, has decreased β-catenin signaling in HEK293T cells. Our study unveils a genetic relationship between LRP6 and APOE and supports the hypothesis that altered Wnt/β-catenin signaling may be involved in this neurodegenerative disease. PMID:17517621

  2. A novel peroxisome proliferator response element modulates hepatic low-density lipoprotein receptor gene transcription in response to PPARδ activation.

    PubMed

    Shende, Vikram R; Singh, Amar Bahadur; Liu, Jingwen

    2015-12-15

    The hepatic expression of low-density lipoprotein (LDL) receptor (LDLR) gene is regulated primarily at the transcriptional level by a sterol-regulatory element (SRE) in its proximal promoter region which is the site of action of SRE-binding protein 2 (SREBP2). However whether additional cis-regulatory elements contribute to LDLR transcription has not been fully explored. We investigated the function of a putative peroxisome proliferator-activated receptor (PPAR)-response element (PPRE) sequence motif located at -768 to -752 bases upstream of the transcription start site of human LDLR gene in response to PPARδ activation. Promoter luciferase reporter analyses showed that treating HepG2 cells with PPARδ agonist L165041 markedly increased the activity of a full-length LDLR promoter construct (pLDLR-1192) without any effects on the shorter promoter reporter pLDLR-234 that contains only the core regulatory elements SRE-1 and SP1 sites. Importantly, mutation of the PPRE sequence greatly attenuated the induction of the full-length LDLR promoter activity by L165041 without affecting rosuvastatin (RSV)-mediated transactivation. EMSA and ChIP assay further confirmed the binding of PPARδ to the LDLR-PPRE site. Treating HepG2 cells with L165041 elevated the mRNA and protein expressions of LDLR without affecting the LDLR mRNA decay rate. The induction of LDLR expression by PPARδ agonist was further observed in liver tissue of mice and hamsters treated with L165041. Altogether, our studies identify a novel PPRE-mediated regulatory mechanism for LDLR transcription and suggest that combined treatment of statin with PPARδ agonists may have advantageous effects on LDLR expression.

  3. Expression of the very low-density lipoprotein receptor (VLDL-r), an apolipoprotein-E receptor, in the central nervous system and in Alzheimer`s disease

    SciTech Connect

    Christie, R.H.; Chung, Haeyong; Rebeck, G.W.; Hyman, B.T.

    1996-04-01

    The very low density lipoprotein receptor (VLDL-r) is a cell-surface molecule specialized for the internalization of multiple diverse ligands, including apolipoprotein E (apoE)-containing lipoprotein particles, via clathrin-coated pits. Its structure is similar to the low-density lipoprotein receptor (LDL-r), although the two have substantially different systemic distributions and regulatory pathways. The present work examines the distribution of VLDL-r in the central nervous system (CNS) and in relation to senile plaques in Alzheimer disease (AD). VLDL-r is present on resting and activated microglia, particularly those associated with senile plaques (SPs). VLDL-r immunoreactivity is also found in cortical neurons. Two exons of VLDL-r mRNA are differentially spliced in the mature receptor mRNA. One set of splice forms gives rise to receptors containing (or lacking) an extracellular O-linked glycosylation domain near the transmembrane portion of the molecule. The other set of splice forms appears to be brain-specific, and is responsible for the presence or absence of one of the cysteine-rich repeat regions in the binding region of the molecule. Ratios of the receptor variants generated from these splice forms do not differ substantially across different cortical areas or in AD. We hypothesize that VLDL-r might contribute to metabolism of apoE and apoE/A{beta} complexes in the brain. Further characterization of apoE receptors in Alzheimer brain may help lay the groundwork for understanding the role of apoE in the CNS and in the pathophysiology of AD. 43 refs., 5 figs.

  4. Annexin A2 is a C-terminal PCSK9-binding protein that regulates endogenous low density lipoprotein receptor levels.

    PubMed

    Mayer, Gaétan; Poirier, Steve; Seidah, Nabil G

    2008-11-14

    The proprotein convertase subtilisin/kexin-type 9 (PCSK9), which promotes degradation of the hepatic low density lipoprotein receptor (LDLR), is now recognized as a major player in plasma cholesterol metabolism. Several gain-of-function mutations in PCSK9 cause hypercholesterolemia and premature atherosclerosis, and thus, inhibition of PCSK9-induced degradation of the LDLR may be used to treat this deadly disease. Herein, we discovered an endogenous PCSK9 binding partner by Far Western blotting, co-immunoprecipitation, and pull-down assays. Following two-dimensional gel electrophoresis and mass spectrometry analysis, we demonstrated that PCSK9 binds to a approximately 33-kDa protein identified as annexin A2 (AnxA2) but not to the closely related annexin A1. Furthermore, our functional LDLR assays and small hairpin RNA studies show that AnxA2 and the AnxA2.p11 complex could prevent PCSK9-directed LDLR degradation in HuH7, HepG2, and Chinese hamster ovary cells. Immunocytochemistry revealed that PCSK9 and AnxA2 co-localize at the cell surface, indicating a possible competition with the LDLR. Structure-function analyses demonstrated that the C-terminal cysteine-histidine-rich domain of PCSK9 interacts specifically with the N-terminal repeat R1 of AnxA2. Mutational analysis of this 70-amino acid-long repeat indicated that the RRTKK81 sequence of AnxA2 is implicated in this binding because its mutation to AATAA81 prevents its interaction with PCSK9. To our knowledge, this work constitutes the first to show that PCSK9 activity on LDLR can be regulated by an endogenous inhibitor. The identification of the minimal inhibitory sequence of AnxA2 should pave the way toward the development of PCSK9 inhibitory lead molecules for the treatment of hypercholesterolemia.

  5. Dissection of the endogenous cellular pathways of PCSK9-induced low density lipoprotein receptor degradation: evidence for an intracellular route.

    PubMed

    Poirier, Steve; Mayer, Gaetan; Poupon, Viviane; McPherson, Peter S; Desjardins, Roxane; Ly, Kevin; Asselin, Marie-Claude; Day, Robert; Duclos, Franck J; Witmer, Mark; Parker, Rex; Prat, Annik; Seidah, Nabil G

    2009-10-16

    Elevated levels of plasma low density lipoprotein (LDL)-cholesterol, leading to familial hypercholesterolemia, are enhanced by mutations in at least three major genes, the LDL receptor (LDLR), its ligand apolipoprotein B, and the proprotein convertase PCSK9. Single point mutations in PCSK9 are associated with either hyper- or hypocholesterolemia. Accordingly, PCSK9 is an attractive target for treatment of dyslipidemia. PCSK9 binds the epidermal growth factor domain A (EGF-A) of the LDLR and directs it to endosomes/lysosomes for destruction. Although the mechanism by which PCSK9 regulates LDLR degradation is not fully resolved, it seems to involve both intracellular and extracellular pathways. Here, we show that clathrin light chain small interfering RNAs that block intracellular trafficking from the trans-Golgi network to lysosomes rapidly increased LDLR levels within HepG2 cells in a PCSK9-dependent fashion without affecting the ability of exogenous PCSK9 to enhance LDLR degradation. In contrast, blocking the extracellular LDLR endocytosis/degradation pathway by a 4-, 6-, or 24-h incubation of cells with Dynasore or an EGF-AB peptide or by knockdown of endogenous autosomal recessive hypercholesterolemia did not significantly affect LDLR levels. The present data from HepG2 cells and mouse primary hepatocytes favor a model whereby depending on the dose and/or incubation period, endogenous PCSK9 enhances the degradation of the LDLR both extra- and intracellularly. Therefore, targeting either pathway, or both, would be an effective method to reduce PCSK9 activity in the treatment of hypercholesterolemia and coronary heart disease.

  6. Transcriptional Activation of Low-Density Lipoprotein Receptor Gene by DJ-1 and Effect of DJ-1 on Cholesterol Homeostasis

    PubMed Central

    Takahashi-Niki, Kazuko; Kato, Izumi; Niki, Takeshi; Goldberg, Matthew S.; Shen, Jie; Ishimoto, Kenji; Doi, Takefumi; Iguchi-Ariga, Sanae M. M.; Ariga, Hiroyoshi

    2012-01-01

    DJ-1 is a novel oncogene and also causative gene for familial Parkinson’s disease park7. DJ-1 has multiple functions that include transcriptional regulation, anti-oxidative reaction and chaperone and mitochondrial regulation. For transcriptional regulation, DJ-1 acts as a coactivator that binds to various transcription factors, resulting in stimulation or repression of the expression of their target genes. In this study, we found the low-density lipoprotein receptor (LDLR) gene is a transcriptional target gene for DJ-1. Reduced expression of LDLR mRNA and protein was observed in DJ-1-knockdown cells and DJ-1-knockout mice and this occurred at the transcription level. Reporter gene assays using various deletion and point mutations of the LDLR promoter showed that DJ-1 stimulated promoter activity by binding to the sterol regulatory element (SRE) with sterol regulatory element binding protein (SREBP) and that stimulating activity of DJ-1 toward LDLR promoter activity was enhanced by oxidation of DJ-1. Chromatin immunoprecipitation, gel-mobility shift and co-immunoprecipitation assays showed that DJ-1 made a complex with SREBP on the SRE. Furthermore, it was found that serum LDL cholesterol level was increased in DJ-1-knockout male, but not female, mice and that the increased serum LDL cholesterol level in DJ-1-knockout male mice was cancelled by administration with estrogen, suggesting that estrogen compensates the increased level of serum LDL cholesterol in DJ-1-knockout female mice. This is the first report that DJ-1 participates in metabolism of fatty acid synthesis through transcriptional regulation of the LDLR gene. PMID:22666465

  7. Transcriptional activation of low-density lipoprotein receptor gene by DJ-1 and effect of DJ-1 on cholesterol homeostasis.

    PubMed

    Yamaguchi, Shiori; Yamane, Takuya; Takahashi-Niki, Kazuko; Kato, Izumi; Niki, Takeshi; Goldberg, Matthew S; Shen, Jie; Ishimoto, Kenji; Doi, Takefumi; Iguchi-Ariga, Sanae M M; Ariga, Hiroyoshi

    2012-01-01

    DJ-1 is a novel oncogene and also causative gene for familial Parkinson's disease park7. DJ-1 has multiple functions that include transcriptional regulation, anti-oxidative reaction and chaperone and mitochondrial regulation. For transcriptional regulation, DJ-1 acts as a coactivator that binds to various transcription factors, resulting in stimulation or repression of the expression of their target genes. In this study, we found the low-density lipoprotein receptor (LDLR) gene is a transcriptional target gene for DJ-1. Reduced expression of LDLR mRNA and protein was observed in DJ-1-knockdown cells and DJ-1-knockout mice and this occurred at the transcription level. Reporter gene assays using various deletion and point mutations of the LDLR promoter showed that DJ-1 stimulated promoter activity by binding to the sterol regulatory element (SRE) with sterol regulatory element binding protein (SREBP) and that stimulating activity of DJ-1 toward LDLR promoter activity was enhanced by oxidation of DJ-1. Chromatin immunoprecipitation, gel-mobility shift and co-immunoprecipitation assays showed that DJ-1 made a complex with SREBP on the SRE. Furthermore, it was found that serum LDL cholesterol level was increased in DJ-1-knockout male, but not female, mice and that the increased serum LDL cholesterol level in DJ-1-knockout male mice was cancelled by administration with estrogen, suggesting that estrogen compensates the increased level of serum LDL cholesterol in DJ-1-knockout female mice. This is the first report that DJ-1 participates in metabolism of fatty acid synthesis through transcriptional regulation of the LDLR gene.

  8. Tissue-type plasminogen activator suppresses activated stellate cells through low-density lipoprotein receptor-related protein 1

    PubMed Central

    Kang, Liang-I; Isse, Kumiko; Koral, Kelly; Bowen, William C; Muratoglu, Selen; Strickland, Dudley K; Michalopoulos, George K; Mars, Wendy M

    2015-01-01

    Hepatic stellate cell (HSC) activation and trans-differentiation into myofibroblast (MFB)-like cells is key for fibrogenesis after liver injury and a potential therapeutic target. Recent studies demonstrated that low-density lipoprotein receptor-related protein 1 (LRP1)-dependent signaling by tissue-type plasminogen activator (t-PA) is a pro-fibrotic regulator of the MFB phenotype in kidney. This study investigated whether LRP1 signaling by t-PA is also relevant to HSC activation following injury. Primary and immortalized rat HSCs were treated with t-PA and assayed by western blot, MTT, and TUNEL. In vitro results were then verified using an in vivo, acute carbon tetrachloride (CCl4) injury model that examined the phenotype and recovery kinetics of MFBs from wild-type animals vs mice with a global (t-PA) or HSC-targeted (LRP1) deletion. In vitro, in contrast to kidney MFBs, exogenous, proteolytically inactive t-PA suppressed, rather than induced, activation markers in HSCs following phosphorylation of LRP1. This process was mediated by LRP1 as inhibition of t-PA binding to LRP1 blocked the effects of t-PA. In vivo, following acute injury, phosphorylation of LRP1 on activated HSCs occurred immediately prior to their disappearance. Mice lacking t-PA or LRP1 retained higher densities of activated HSCs for a longer time period compared with control mice after injury cessation. Hence, t-PA, an FDA-approved drug, contributes to the suppression of activated HSCs following injury repair via signaling through LRP1. This renders t-PA a potential target for exploitation in treating patients with fibrosis. PMID:26237273

  9. Intermittent hypoxia and hypercapnia induce pulmonary artery atherosclerosis and ventricular dysfunction in low density lipoprotein receptor deficient mice

    PubMed Central

    Bowden, Karen; Pattison, Jennifer; Peterson, Alexander B.; Juliano, Joseph; Dalton, Nancy D.; Gu, Yusu; Alvarez, Erika; Imamura, Toshihiro; Peterson, Kirk L.; Witztum, Joseph L.; Haddad, Gabriel G.; Li, Andrew C.

    2013-01-01

    Patients with obstructive sleep apnea, who experience episodic hypoxia and hypercapnia during sleep, often demonstrate increased inflammation, oxidative stress, and dyslipidemia. We hypothesized that sleep apnea patients would be predisposed to the development of atherosclerosis. To dissect the mechanisms involved, we developed an animal model in mice whereby we expose mice to intermittent hypoxia/hypercapnia (IHH) in normobaric environments. Two- to three-month-old low-density lipoprotein receptor deficient (Ldlr−/−) mice were fed a high-fat diet for 8 or 16 wk while being exposed to IHH for either 10 h/day or 24 h/day. Plasma lipid levels, pulmonary artery and aortic atherosclerotic lesions, and cardiac function were then assayed. Surprisingly, atherosclerosis in the aorta of IHH mice was similar compared with controls. However, in IHH mice, atherosclerosis was markedly increased in the trunk and proximal branches of the pulmonary artery of exposed mice; even though plasma cholesterol and triglycerides were lower than in controls. Hemodynamic analysis revealed that right ventricular maximum pressure and isovolumic relaxation constant were significantly increased in IHH exposed mice and left ventricular % fractional shortening was reduced. In conclusion, 1) Intermittent hypoxia/hypercapnia remarkably accelerated atherosclerotic lesions in the pulmonary artery of Ldlr−/− mice and 2) increased lesion formation in the pulmonary artery was associated with right and left ventricular dysfunction. These findings raise the possibility that patients with obstructive sleep apnea may be susceptible to atherosclerotic disease in the pulmonary vasculature, an observation that has not been previously recognized. PMID:23990245

  10. Development of Accelerated Coronary Atherosclerosis Model Using Low Density Lipoprotein Receptor Knock-Out Swine with Balloon Injury

    PubMed Central

    Ogita, Manabu; Miyauchi, Katsumi; Onishi, Akira; Tsuboi, Shuta; Wada, Hideki; Konishi, Hirokazu; Naito, Ryo; Dohi, Tomotaka; Kasai, Takatoshi; Kojima, Yuko; Schwartz, Robert S.; Daida, Hiroyuki

    2016-01-01

    Background Several animal models have facilitated the evaluation and pathological understanding of atherosclerosis, but a definitive animal model of coronary atherosclerosis is not available. We therefore developed low density lipoprotein receptor knockout (LDLR-KO) pigs with hypercholesterolemia, a model which rapidly developed coronary atherosclerosis following balloon injury. Methods and Results We deleted LDLR exon regions from cultured porcine fetal fibroblasts and cloned LDLR knockout (LDLR-KO) embryos microinjecting fetal fibroblast nuclei into enucleated oocytes. Twelve LDLR-KO pigs were fed a 2.0% cholesterol and 20% fat diet. Baseline serum LDL cholesterol level was 510.0±86.1 mg/dL. Balloon injury was created in 46 coronary segments and necropsy were obtained 2, 4, 8 and 12 weeks later. Coronary artery sections were reviewed to evaluate lesion progression. We found lipid accumulation with foam cells and inflammatory cells beginning four weeks after balloon injury. The mean ratio of macrophages to plaque area was significantly higher in the four- weeks and eight-week animals compared with those at 2-weeks (8.79% ± 5.98% and 17.00% ± 10.38% vs. 1.14% ± 1.88%, P < 0.0001). At 12 weeks the ratio decreased toward the level at 2 week level (4.00% ± 4.56%, P = 0.66 vs. baseline). Advanced coronary atherosclerotic lesions contained lipid pools at eight-weeks with fibrous components beginning at 12 weeks. Conclusions We developed a model of rapid coronary atherosclerosis using LDLR KO pigs with balloon injury. This model may be useful for preclinical evaluation of medication or devices, and may also help investigate mechanisms of plaque progression. PMID:27631974

  11. 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

  12. Severe Atherosclerosis and Hypercholesterolemia in Mice Lacking Both the Melanocortin Type 4 Receptor and Low Density Lipoprotein Receptor

    PubMed Central

    Meusel, Andrej; Teupser, Daniel; Ricken, Albert; Thiery, Joachim; Schiller, Jürgen; Huster, Daniel; Schöneberg, Torsten

    2016-01-01

    Dysfunction of the melanocortin system can result in severe obesity accompanied with dyslipidemia and symptoms of the metabolic syndrome but the effect on vascular atherogenesis is not known. To study the impact of obesity and dyslipidemia on the cardiovascular system, we generated mice double-deficient for the melanocortin type 4 receptor (Mc4rmut mice) and the LDL receptor (Ldlr-/- mice). Mc4rmut mice develop obesity due to hyperphagia. Double-mutant mice (Mc4rmut;Ldlr-/-) exhibited massive increases in body weight, plasma cholesterol and triacylglycerol levels and developed atherosclerosis. Atherosclerotic lesion size was affected throughout the aortic root and brachiocephalic artery not only under semisynthetic, cholesterol-containing diet but also under cholesterol-free standard chow. The Mc4rmut mice developed a hepatic steatosis which contributes to increased plasma cholesterol levels even under cholesterol-free standard chow. Transcripts of cholesterol biosynthesis components and liver cholesterol levels did not significantly differ between wild-type and all mutant mouse strains but RNA sequencing data and biochemical measurements point to an altered bile acid elimination in Mc4rmut;Ldlr-/-. Therefore, the unchanged endogenous cholesterol biosynthesis together with a reduced hepatic VLDL and LDL-cholesterol clearance most likely led to increased plasma lipid levels and consequently to atherosclerosis in this animal model. Our data indicate that dysfunction of the melanocortin-regulated food intake and the resulting obesity significantly add to the proatherogenic lipoprotein profile caused by LDL receptor deficiency and, therefore, can be regarded as relevant risk factor for atherosclerosis. PMID:28030540

  13. Lectin-like, oxidized low-density lipoprotein receptor-1-deficient mice show resistance to age-related knee osteoarthritis

    PubMed Central

    Hashimoto, Kazuhiko; Oda, Yutaka; Nakamura, Fumihisa; Kakinoki, Ryosuke; Akagi, Masao

    2017-01-01

    The lectin-like, oxidized low-density lipoprotein (ox-LDL) receptor-1 (LOX-1)/ox-LDL system contributes to atherosclerosis and may be involved in cartilage degeneration. The purpose of this study was to determine whether the LOX-1/ox-LDL system contributes to age-related osteoarthritis (OA) in vivo, using LOX-1 knockout (LOX-1 KO) mice. Knee cartilage from 6, 12, and 18-month old (n = 10/group) C57Bl/6 wild-type (WT) and LOX-1 KO mice was evaluated by determining the Osteoarthritis Research Society International (OARSI) score of Safranin-O stained samples. The prevalence of knee OA in both mouse strains was also investigated. Expression levels of LOX-1, ox-LDL, runt-related transcription factor-2 (Runx2), type-X collagen (COL X), and matrix metalloproteinase-13 (MMP-13) in the articular chondrocytes were analyzed immunohistologically. No significant difference was observed in the mean scores of WT (2.00±0.61) and LOX-1 KO mice (2.00±0.49) at 6 months of age (P=1.00, n=10). At 12 and 18 months of age, the mean scores of LOX-1 KO mice (3.75±0.93 and 5.50±0.78) were significantly lower than those of WT mice (5.25±1.14 and 9.00±1.01; P<0.001 in both cases; n=10). The prevalence of OA in LOX-1 KO mice was lower than that in WT mice at 12 and 18 months of age (40 vs 70%, 70 vs 90%, respectively; n=10). The expression levels of Runx2, COL X, and MMP-13 in articular chondrocytes significantly decreased in LOX-1 KO, mice compared with those in WT mice. The study indicated that the LOX-1/ox-LDL system in chondrocytes plays a role in the pathogenesis of age-related knee OA, which is potentially a target for preventing OA progression. PMID:28348422

  14. CXCL16 Is Expressed in Podocytes and Acts as a Scavenger Receptor for Oxidized Low-Density Lipoprotein

    PubMed Central

    Gutwein, Paul; Abdel-Bakky, Mohamed Sadek; Schramme, Anja; Doberstein, Kai; Kämpfer-Kolb, Nicole; Amann, Kerstin; Hauser, Ingeborg A.; Obermüller, Nicholas; Bartel, Christine; Abdel-Aziz, Abdel-Aziz H.; El Sayed, El Sayed M.; Pfeilschifter, Josef

    2009-01-01

    Podocytes are a crucial cell type in the kidney and play an important role in the pathology of glomerular kidney diseases like membranous nephropathy (MN). The identification of new factors involved in the progression of glomerular kidney diseases is of great importance to the development of new strategies for the treatment of renal injury. Here we demonstrate that CXCL16 and ADAM10 are constitutively expressed in human podocytes in normal renal tissue. Proinflammatory cytokines like interferon-γ and tumor necrosis factor-α induced the expression of cellular CXCL16 and the release of its soluble form from human podocytes. Using different metalloproteinase inhibitors, we provide evidence that ADAM10 is involved in the interferon-γ- and tumor necrosis factor-α-induced shedding of CXCL16 from human podocytes. In addition, ADAM10 knockdown by siRNA significantly increased both CXCL16 levels and, surprisingly, its ADAM17-mediated release. Notably, targeting of CXCL16 in human podocytes both decreased the chemotaxis of CXCR6-expressing T cells and strongly reduced oxidized low-density lipoprotein uptake in human podocytes. Importantly, in kidney biopsies of patients with MN, increased glomerular CXCL16 expression was accompanied by high levels of oxidized low-density lipoprotein and decreased expression of ADAM10. In addition, we found increased glomerular ADAM17 expression in patients diagnosed with MN. In summary, we presume important roles for CXCL16, ADAM10, and ADAM17 in the development of MN, suggesting these proteins as new therapeutic targets in this glomerular kidney disease. PMID:19435795

  15. Baculovirus-mediated expression of human apolipoprotein E in Manduca sexta larvae generates particles that bind to the low density lipoprotein receptor.

    PubMed Central

    Gretch, D G; Sturley, S L; Friesen, P D; Beckage, N E; Attie, A D

    1991-01-01

    Human apolipoprotein E (apoE) is a ligand for the low density lipoprotein (LDL) receptor and mediates the catabolism of several classes of lipoprotein particles. Binding of apoE to the LDL receptor requires association of apoE with lipid in a vesicle or a lipoprotein particle. Because of this requirement, purified apoE or apoE derived directly from bacterial expression systems does not bind to the LDL receptor. To overcome this problem and to facilitate analysis of apoE structure, recombinant baculoviruses containing the human apoE cDNA fused to the polyhedrin promoter of Autographa californica nuclear polyhedrosis virus were constructed. The recombinant viruses were used to infect larvae of the tobacco hornworm Manduca sexta in vivo. High levels of lipoprotein particles containing human apoE were present in the hemolymph of infected larvae. In contrast to apoE produced by recombinant baculovirus-infected insect cells in vitro, these particles were excellent ligands for the LDL receptor. Images PMID:1924311

  16. Low density lipoprotein receptor-binding activity in human tissues: Quantitative importance of hepatic receptors and evidence for regulation of their expression in vivo

    SciTech Connect

    Rudling, M.J. Karolinska Institutet, Stockholm ); Reihner, E.; Einarsson, K.; Ewerth, S.; Angelin, B. )

    1990-05-01

    The heparin-sensitive binding of {sup 125}I-labeled low-density lipoprotein (LDL) to homogenates from 18 different normal human tissues and some solid tumors was determined. The binding to adrenal and liver homogenates fulfilled criteria established for the binding of LDL to its receptor--namely, (i) saturability, (ii) sensitivity to proteolytic destruction, (iii) inhibition by EDTA, and (iv) heat sensitivity. When the binding of {sup 125}I-labeled LDL was assayed at a constant concentration, the adrenal gland and the ovary had the highest binding of normal tissues. The highest binding per g of tissue overall was obtained in homogenates of a gastric carcinoma and a parotid adenoma. When the weights of the parenchymatous organs were considered, the major amount of LDL receptors was contained in the liver. To study the possible regulation of hepatic LDL-receptor expression, 11 patients were pretreated with cholestyramine. Increased binding activity was obtained in homogenates from liver biopsies from the cholestyramine-treated patients as compared with 12 untreated controls. It is concluded that the liver is the most important organ for LDL catabolism in humans and that the receptor activity in this organ can be regulated upon pharmacologic intervention. Further studies are needed to confirm the possibility that certain solid tumors can exhibit high numbers of LDL receptors.

  17. Hypercholesterolemia in low density lipoprotein receptor knockout mice and its reversal by adenovirus-mediated gene delivery.

    PubMed Central

    Ishibashi, S; Brown, M S; Goldstein, J L; Gerard, R D; Hammer, R E; Herz, J

    1993-01-01

    We employed homologous recombination in embryonic stem cells to produce mice lacking functional LDL receptor genes. Homozygous male and female mice lacking LDL receptors (LDLR-/- mice) were viable and fertile. Total plasma cholesterol levels were twofold higher than those of wild-type litter-mates, owing to a seven- to ninefold increase in intermediate density lipoproteins (IDL) and LDL without a significant change in HDL. Plasma triglyceride levels were normal. The half-lives for intravenously administered 125I-VLDL and 125I-LDL were prolonged by 30-fold and 2.5-fold, respectively, but the clearance of 125I-HDL was normal in the LDLR-/- mice. Unlike wild-type mice, LDLR-/- mice responded to moderate amounts of dietary cholesterol (0.2% cholesterol/10% coconut oil) with a major increase in the cholesterol content of IDL and LDL particles. The elevated IDL/LDL level of LDLR-/- mice was reduced to normal 4 d after the intravenous injection of a recombinant replication-defective adenovirus encoding the human LDL receptor driven by the cytomegalovirus promoter. The virus restored expression of LDL receptor protein in the liver and increased the clearance of 125I-VLDL. We conclude that the LDL receptor is responsible in part for the low levels of VLDL, IDL, and LDL in wild-type mice and that adenovirus-encoded LDL receptors can acutely reverse the hypercholesterolemic effects of LDL receptor deficiency. Images PMID:8349823

  18. Purification, crystallization and preliminary X-ray analysis of the ligand-binding domain of human lectin-like oxidized low-density lipoprotein receptor 1 (LOX-1)

    SciTech Connect

    Ishigaki, Tomoko; Ohki, Izuru; Oyama, Takuji; Machida, Sachiko; Morikawa, Kousuke; Tate, Shin-ichi

    2005-05-01

    Two different fragments of the ligand-binding domain of LOX-1, the major receptor for oxidized low-density lipoprotein (LDL) on endothelial cells, have been crystallized in different forms. Two different fragments of the ligand-binding domain of LOX-1, the major receptor for oxidized low-density lipoprotein (LDL) on endothelial cells, have been crystallized in different forms. One crystal form contains the disulfide-linked dimer, which is the form of the molecule present on the cell surface; the other contains a monomeric form of the receptor that lacks the cysteine residue necessary to form disulfide-linked homodimers. The crystal of the monomeric ligand-binding domain belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 56.79, b = 67.57, c = 79.02 Å. The crystal of the dimeric form belongs to space group C2, with unit-cell parameters a = 70.86, b = 49.56, c = 76.73 Å, β = 98.59°. Data for the dimeric form of the LOX-1 ligand-binding domain have been collected to 2.4 Å. For the monomeric form of the ligand-binding domain, native, heavy-atom derivative and SeMet-derivative crystals have been obtained; their diffraction data have been measured to 3.0, 2.4 and 1.8 Å resolution, respectively.

  19. Lectin-like Oxidized Low-Density Lipoprotein (LDL) Receptor (LOX-1): A Chameleon Receptor for Oxidized LDL.

    PubMed

    Zeya, Bushra; Arjuman, Albina; Chandra, Nimai Chand

    2016-08-16

    LOX-1, one of the main receptors for oxLDL, is found mainly on the surface of endothelial cells. It is a multifacet 52 kDa type II transmembrane protein that structurally belongs to the C-type lectin family. It exists with short intracellular N-terminal and long extracellular C-terminal hydrophilic domains separated by a hydrophobic domain of 26 amino acids. LOX-1 acts like a bifunctional receptor either showing pro-atherogenicity by activating the NFκB-mediated down signaling cascade for gene activation of pro-inflammatory molecules or playing an atheroprotective agent by receptor-mediated uptake of oxLDL in the presence of an anti-inflammatory molecule like IL-10. Mildly, moderately, and highly oxidized LDL show their characteristic features upon LOX-1 activation and its ligand binding indenture. The polymorphic LOX-1 genes are intensively associated with increased susceptibility to myocardial diseases. The splicing variant LOX IN dimerizes with the native form of LOX-1 and protects cells from damage by oxidized LDL. In the developing field of regenerating medicine, LOX-1 is a potential target for therapeutic intervention.

  20. Dietary Fat Interacts with PCBs to Induce Changes in Lipid Metabolism in Mice Deficient in Low-Density Lipoprotein Receptor

    PubMed Central

    Hennig, Bernhard; Reiterer, Gudrun; Toborek, Michal; Matveev, Sergey V.; Daugherty, Alan; Smart, Eric; Robertson, Larry W.

    2005-01-01

    There is evidence that dietary fat can modify the cytotoxicity of polychlorinated biphenyls (PCBs) and that coplanar PCBs can induce inflammatory processes critical in the pathology of vascular diseases. To test the hypothesis that the interaction of PCBs with dietary fat is dependent on the type of fat, low-density lipoprotein receptor–deficient (LDL-R−/−) mice were fed diets enriched with either olive oil or corn oil for 4 weeks. Half of the animals from each group were injected with PCB-77. Vascular cell adhesion molecule-1 (VCAM-1) expression in aortic arches was non-detectable in the olive-oil–fed mice but was highly expressed in the presence of PCB-77. PCB treatment increased liver neutral lipids and decreased serum fatty acid levels only in mice fed the corn-oil–enriched diet. PCB treatment increased mRNA expression of genes involved in inflammation, apoptosis, and oxidative stress in all mice. Upon PCB treatment, mice in both olive- and corn-oil–diet groups showed induction of genes involved in fatty acid degradation but with up-regulation of different key enzymes. Genes involved in fatty acid synthesis were reduced only upon PCB treatment in corn-oil–fed mice, whereas lipid transport/export genes were altered in olive-oil–fed mice. These data suggest that dietary fat can modify changes in lipid metabolism induced by PCBs in serum and tissues. These findings have implications for understanding the interactions of nutrients with environmental contaminants on the pathology of inflammatory diseases such as atherosclerosis. PMID:15626652

  1. Altered hepatic lipid metabolism in mice lacking both the melanocortin type 4 receptor and low density lipoprotein receptor

    PubMed Central

    Garten, Antje; Popkova, Yulia; Penke, Melanie; Franke, Christin; Ricken, Albert; Schulz, Angela; Kiess, Wieland; Huster, Daniel; Schöneberg, Torsten; Schiller, Jürgen

    2017-01-01

    Obesity is often associated with dyslipidemia and hepatosteatosis. A number of animal models of non-alcoholic fatty liver disease (NAFLD) are established but they significantly differ in the molecular and biochemical changes depending on the genetic modification and diet used. Mice deficient for melanocortin type 4 receptor (Mc4rmut) develop hyperphagia, obesity, and subsequently NAFLD already under regular chow and resemble more closely the energy supply-driven obesity found in humans. This animal model was used to assess the molecular and biochemical consequences of hyperphagia-induced obesity on hepatic lipid metabolism. We analyzed transcriptome changes in Mc4rmut mice by RNA sequencing and used high resolution 1H magic angle spinning NMR spectroscopy and MALDI-TOF mass spectrometry to assess changes in the lipid composition. On the transcriptomic level we found significant changes in components of the triacylglycerol metabolism, unsaturated fatty acids biosynthesis, peroxisome proliferator-activated receptor signaling pathways, and lipid transport and storage compared to the wild-type. These findings were supported by increases in triacylglycerol, monounsaturated fatty acid, and arachidonic acid levels. The transcriptome signatures significantly differ from those of other NAFLD mouse models supporting the concept of hepatic subphenotypes depending on the genetic background and diet. Comparative analyses of our data with previous studies allowed for the identification of common changes and genotype-specific components and pathways involved in obesity-associated NAFLD. PMID:28207798

  2. Low density lipoproteins mediated nanoplatforms for cancer targeting

    NASA Astrophysics Data System (ADS)

    Jain, Anupriya; Jain, Keerti; Kesharwani, Prashant; Jain, Narendra K.

    2013-09-01

    Chemotherapy is a foremost remedial approach for the treatment of localized and metastasized tumors. In order to explore new treatment modalities for cancer, it is important to identify qualitative or quantitative differences in metabolic processes between normal and malignant cells. One such difference may be that of increased receptor-mediated cellular uptake of low density lipoproteins (LDLs) by cancer cells. Lipoproteins in general and specifically LDL are ideal candidates for loading and delivering cancer therapeutic and diagnostic agents due to their biocompatibility. By mimicking the endogenous shape and structure of lipoproteins, the reconstituted lipoproteins can remain in circulation for an extended period of time, while largely evading the reticuloendothelial cells in the body's defenses. In this account, we review the field of low density inspired nanoparticles in relation to the delivery of cancer imaging and therapeutic agents. LDL has instinctive cancer targeting potential and has been used to incorporate various lipophillic molecules to transport them to tumors. Nature's method of rerouting LDL provides a strategy to extend the cancer targeting potential of lipoproteins far off its constricted purview. In this review, we have discussed the various aspects of LDL including its role in cancer imaging and chemotherapy in retrospect and prospect and current efforts aimed to further improve the delivery efficacy of LDL-drug complexes with reduced chances of drug resistance leading to optimal drug delivery. This review provides a strong support for the concept of using LDL as a drug carrier.

  3. Molecular cloning and partial characterization of an ovarian receptor with seven ligand binding repeats, an orthologue of low-density lipoprotein receptor, in the cutthroat trout (Oncorhynchus clarki).

    PubMed

    Luo, Wenshu; Ito, Yuta; Mizuta, Hiroko; Massaki, Kiyohiro; Hiramatsu, Naoshi; Todo, Takashi; Reading, Benjamin J; Sullivan, Craig V; Hara, Akihiko

    2013-10-01

    Teleost fish eggs contain a substantial yolk mass consisting of lipids and proteins that provides essential nutrients for embryonic and larval development. The polar lipid and protein components of the yolk are delivered to oocytes by circulating vitellogenins, however the source(s) of the neutral lipid remains unknown. We cloned a cDNA encoding an orthologue of low-density-lipoprotein receptor (LDLR) from the ovary of cutthroat trout, Oncorhynchus clarki (ct-Ldlr). Predominant expression of ct-ldlr mRNA was observed in the ovary and moderate expression was detected in intestine, gill and brain. The relative abundance of ct-ldlr transcripts was highest in early pre-vitellogenic ovaries and significantly decreased during vitellogenesis, followed by a slight increase during final maturation and in post-ovulatory follicles. In situ hybridization revealed an intense and evenly distributed localization of ct-ldlr transcripts in the ooplasm of pre-vitellogenic oocytes and these signals disappeared in vitellogenic follicles. Collectively, these results suggest that the Ldlr is involved in deposition of yolk lipids in cutthroat trout oocytes. The ct-ldlr transcripts also were detected in theca and granulosa cells, suggesting that this receptor may be involved in cholesterol uptake for ovarian steroidogenesis. This is the first report on partial characterization of an ldlr orthologue in any fish species.

  4. Effects of High Fat Feeding and Diabetes on Regression of Atherosclerosis Induced by Low-Density Lipoprotein Receptor Gene Therapy in LDL Receptor-Deficient Mice

    PubMed Central

    Willecke, Florian; Yuan, Chujun; Oka, Kazuhiro; Chan, Lawrence; Hu, Yunying; Barnhart, Shelley; Bornfeldt, Karin E.; Goldberg, Ira J.; Fisher, Edward A.

    2015-01-01

    We tested whether a high fat diet (HFD) containing the inflammatory dietary fatty acid palmitate or insulin deficient diabetes altered the remodeling of atherosclerotic plaques in LDL receptor knockout (Ldlr-/-) mice. Cholesterol reduction was achieved by using a helper-dependent adenovirus (HDAd) carrying the gene for the low-density lipoprotein receptor (Ldlr; HDAd-LDLR). After injection of the HDAd-LDLR, mice consuming either HFD, which led to insulin resistance but not hyperglycemia, or low fat diet (LFD), showed regression compared to baseline. However there was no difference between the two groups in terms of atherosclerotic lesion size, or CD68+ cell and lipid content. Because of the lack of effects of these two diets, we then tested whether viral-mediated cholesterol reduction would lead to defective regression in mice with greater hyperglycemia. In both normoglycemic and streptozotocin (STZ)-treated hyperglycemic mice, HDAd-LDLR significantly reduced plasma cholesterol levels, decreased atherosclerotic lesion size, reduced macrophage area and lipid content, and increased collagen content of plaque in the aortic sinus. However, reductions in anti-inflammatory and ER stress-related genes were less pronounced in STZ-diabetic mice compared to non-diabetic mice. In conclusion, HDAd-mediated Ldlr gene therapy is an effective and simple method to induce atherosclerosis regression in Ldlr-/- mice in different metabolic states. PMID:26046657

  5. Distinct Functional Domains Contribute to Degradation of the Low Density Lipoprotein Receptor (LDLR) by the E3 Ubiquitin Ligase Inducible Degrader of the LDLR (IDOL)

    PubMed Central

    Sorrentino, Vincenzo; Scheer, Lilith; Santos, Ana; Reits, Eric; Bleijlevens, Boris; Zelcer, Noam

    2011-01-01

    We recently identified the liver X receptor-regulated E3 ubiquitin ligase inducible degrader of the LDL receptor (IDOL) as a modulator of lipoprotein metabolism. Acting as an E3 ubiquitin ligase, IDOL triggers ubiquitination and subsequent degradation of the low density lipoprotein receptor (LDLR). We demonstrate here that this outcome requires the conserved FERM and RING domains present in IDOL. The RING domain promotes ubiquitination in vitro and Lys-63-specific ubiquitination of the LDLR in vivo in response to IDOL or liver X receptor activation. We further identify RING residues that differentially influence ubiquitination of the LDLR or stability of IDOL. The FERM domain interacts with the LDLR and in living cells co-localizes with the receptor at the plasma membrane. Homology modeling revealed a phosphotyrosine-binding element embedded in the FERM domain. Mutating residues within this region or residues in the LDLR preceding the NPVY endocytosis motif abrogate LDLR degradation by IDOL. Collectively, our results indicate that both the FERM and RING domains are required for promoting lysosomal degradation of the LDLR by IDOL. Our findings may facilitate development of structure-based IDOL inhibitors aimed at increasing LDLR abundance in therapeutic strategies to treat cardiovascular disease. PMID:21734303

  6. Characterization of a family of gamma-ray-induced CHO mutants demonstrates that the ldlA locus is diploid and encodes the low-density lipoprotein receptor

    SciTech Connect

    Sege, R.D.; Kozarsky, K.F.; Krieger, M.

    1986-09-01

    The ldlA locus is one of four Chinese hamster ovary (CHO) cell loci which are known to be required for the synthesis of functional low-density lipoprotein (LDL) receptors. Previous studies have suggested that the ldlA locus is diploid and encodes the LDL receptor. To confirm this assignment, we have isolated a partial genomic clone of the Chinese hamster LDL receptor gene and used this and other nucleic acid and antibody probes to study a family of ldlA mutants isolated after gamma-irradiation. Our analysis suggests that there are two LDL receptor alleles in wild-type CHO cells. Each of the three mutants isolated after gamma-irradiation had detectable deletions affecting one of the two LDL receptor alleles. One of the mutants also had a disruption of the remaining allele, resulting in the synthesis of an abnormal receptor precursor which was not subject to Golgi-associated posttranslational glycoprotein processing. The correlation of changes in the expression, structure, and function of LDL receptors with deletions in the LDL receptor genes in these mutants directly demonstrated that the ldlA locus in CHO cells is diploid and encodes the LDL receptor. In addition, our analysis suggests that CHO cells in culture may contain a partial LDL receptor pseudogene.

  7. Characterization of a family of gamma-ray-induced CHO mutants demonstrates that the ldlA locus is diploid and encodes the low-density lipoprotein receptor.

    PubMed

    Sege, R D; Kozarsky, K F; Krieger, M

    1986-09-01

    The ldlA locus is one of four Chinese hamster ovary (CHO) cell loci which are known to be required for the synthesis of functional low-density lipoprotein (LDL) receptors. Previous studies have suggested that the ldlA locus is diploid and encodes the LDL receptor. To confirm this assignment, we have isolated a partial genomic clone of the Chinese hamster LDL receptor gene and used this and other nucleic acid and antibody probes to study a family of ldlA mutants isolated after gamma-irradiation. Our analysis suggests that there are two LDL receptor alleles in wild-type CHO cells. Each of the three mutants isolated after gamma-irradiation had detectable deletions affecting one of the two LDL receptor alleles. One of the mutants also had a disruption of the remaining allele, resulting in the synthesis of an abnormal receptor precursor which was not subject to Golgi-associated posttranslational glycoprotein processing. The correlation of changes in the expression, structure, and function of LDL receptors with deletions in the LDL receptor genes in these mutants directly demonstrated that the ldlA locus in CHO cells is diploid and encodes the LDL receptor. In addition, our analysis suggests that CHO cells in culture may contain a partial LDL receptor pseudogene.

  8. Essential oil of Pinus koraiensis leaves exerts antihyperlipidemic effects via up-regulation of low-density lipoprotein receptor and inhibition of acyl-coenzyme A: cholesterol acyltransferase.

    PubMed

    Kim, Ji-Hyun; Lee, Hyo-Jung; Jeong, Soo-Jin; Lee, Min-Ho; Kim, Sung-Hoon

    2012-09-01

    Hyperlipidemia is an important factor to induce metabolic syndrome such as obesity, diabetes and cardiovascular diseases. Recently, some antihyperlipidemic agents from herbal medicines have been in the spotlight in the medical science field. Thus, the present study evaluated the antihyperlipidemic activities of the essential oil from the leaves of Pinus koraiensis SIEB (EOPK) that has been used as a folk remedy for heart disease. The reverse transcription polymerase chain reaction (RT-PCR) revealed that EOPK up-regulated low density lipoprotein receptor (LDLR) at the mRNA level as well as negatively suppressed the expression of sterol regulatory element-binding protein (SREBP)-1c, SREBP-2, 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR), fatty acid synthase (FAS) and glycerol-3-phosphate acyltransferase (GPAT) involved in lipid metabolism in HepG2 cells. Also, western blotting showed that EOPK activated LDLR and attenuated the expression of FAS at the protein level in the cells. Consistently, EOPK significantly inhibited the level of human acylcoenzyme A: cholesterol acyltransferase (hACAT)1 and 2 and reduced the low-density lipoprotein (LDL) oxidation activity. Furthermore, chromatography-mass spectrometry (GC-MS) analysis showed that EOPK, an essential oil mixture, contained camphene (21.11%), d-limonene (21.01%), α-pinene (16.74%) and borneol (11.52%). Overall, the findings suggest that EOPK can be a potent pharmaceutical agent for the prevention and treatment of hyperlipidemia.

  9. The modular adaptor protein ARH is required for low density lipoprotein (LDL) binding and internalization but not for LDL receptor clustering in coated pits.

    PubMed

    Michaely, Peter; Li, Wei-Ping; Anderson, Richard G W; Cohen, Jonathan C; Hobbs, Helen H

    2004-08-06

    ARH is an adaptor protein required for efficient endocytosis of low density lipoprotein (LDL) receptors (LDLRs) in selected tissues. Individuals lacking ARH (ARH-/-) have severe hypercholesterolemia due to impaired hepatic clearance of LDL. Immortalized lymphocytes, but not fibroblasts, from ARH-deficient subjects fail to internalize LDL. To further define the role of ARH in LDLR function, we compared the subcellular distribution of the LDLR in lymphocytes from normal and ARH-/- subjects. In normal lymphocytes LDLRs were predominantly located in intracellular compartments, whereas in ARH-/- cells the receptors were almost exclusively on the plasma membrane. Biochemical assays and quantification of LDLR by electron microscopy indicated that ARH-/- lymphocytes had >20-fold more LDLR on the cell surface and a approximately 27-fold excess of LDLR outside of coated pits. The accumulation of LDLR on the cell surface was not due to failure of receptors to localize in coated pits since the number of LDLRs in coated pits was similar in ARH-/- and normal cells. Despite the dramatic increase in cell surface receptors, LDL binding was only 2-fold higher in the ARH-/- lymphocytes. These findings indicate that ARH is required not only for internalization of the LDL.LDLR complex but also for efficient binding of LDL to the receptor and suggest that ARH stabilizes the associations of the receptor with LDL and with the invaginating portion of the budding pit, thereby increasing the efficiency of LDL internalization.

  10. Low-density lipoprotein receptor gene mutation analysis and structure-function correlation in an Omani arab family with familial hypercholesterolemia.

    PubMed

    Al-Rasadi, Khalid; Al-Waili, Khalid; Al-Zidi, Ward Al-Muna; Al-Abri, Abdul Rahim; Al-Hinai, Ali T; Al-Sabti, Hilal Ali; Al-Tobi, Sheikha; Al-Zakwani, Ibrahim; Al-Zadjali, Fahad; Al-Hashmi, Khamis; Banerjee, Yajnavalka

    2014-11-01

    Familial hypercholesterolemia (FH) is an autosomal dominant disorder typified by elevated low-density lipoprotein cholesterol (LDL-C) levels caused by mutations in the LDL receptor (LDLR), apolipoprotein B (ApoB), or proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. Previously, we reported a novel mutation in the exon-3 of LDLR gene, observed in a 9-year-old Omani Arab female. Here, we investigated the mode of inheritance of this mutation and confirmed that FH in this family is due to mutation only in the LDLR and not PCSK9 and ApoB genes. Further, the effect of the mutation has been appraised in silico on the tertiary structure of LDLR. A model of the mutant LDLR has been constructed using the coordinates of the wild-type LDLR extracellular domain. Based on the model, we present a mechanistic justification behind the observed detrimental effect of the mutation on LDL-C levels.

  11. Expression of alpha 2-macroglobulin receptor/low density lipoprotein receptor-related protein and scavenger receptor in human atherosclerotic lesions.

    PubMed Central

    Luoma, J; Hiltunen, T; Särkioja, T; Moestrup, S K; Gliemann, J; Kodama, T; Nikkari, T; Ylä-Herttuala, S

    1994-01-01

    Macrophage- and smooth muscle cell (SMC)-derived foam cells are typical constituents of human atherosclerotic lesions. At least three receptor systems have been characterized that could be involved in the development of foam cells: alpha 2-macroglobulin receptor/LDL receptor-related protein (alpha 2 MR/LRP), scavenger receptor, and LDL receptor. We studied the expression of these receptors in human atherosclerotic lesions with in situ hybridization and immunocytochemistry. An abundant expression of alpha 2MR/LRP mRNA and protein was found in SMC and macrophages in both early and advanced lesions in human aortas. alpha 2MR/LRP was also present in SMC in normal aortas. Scavenger receptor mRNA and protein were expressed in lesion macrophages but no expression was found in lesion SMC. LDL receptor was absent from the lesion area but was expressed in some aortas in medial SMC located near the adventitial border. The results demonstrate that (a) alpha 2MR/LRP is, so far, the only lipoprotein receptor expressed in lesions SMC in vivo; (b) scavenger receptors are expressed only in lesion macrophages; and (c) both receptors may play important roles in the development of human atherosclerotic lesions. Images PMID:8182133

  12. Modulation of hepatic apolipoprotein B, 3-hydroxy-3-methylglutaryl-CoA reductase and low-density lipoprotein receptor mRNA and plasma lipoprotein concentrations by defined dietary fats. Comparison of trimyristin, tripalmitin, tristearin and triolein.

    PubMed Central

    Bennett, A J; Billett, M A; Salter, A M; Mangiapane, E H; Bruce, J S; Anderton, K L; Marenah, C B; Lawson, N; White, D A

    1995-01-01

    Different dietary fatty acids exert specific effects on plasma lipids but the mechanism by which this occurs is unknown. Hamsters were fed on low-cholesterol diets containing triacylglycerols enriched in specific saturated fatty acids, and effects on plasma lipids and the expression of genes involved in hepatic lipoprotein metabolism were measured. Trimyristin and tripalmitin caused significant rises in low-density lipoprotein (LDL) cholesterol which were accompanied by significant reductions in hepatic LDL receptor mRNA levels. Tripalmitin also increased hepatic expression of the apolipoprotein B gene, implying an increased production of LDL via very-low-density lipoprotein (VLDL) and decreased removal of LDL in animals fed this fat. Hepatic levels of 3-hydroxy-3-methylglutaryl-CoA reductase mRNA did not vary significantly between the groups. Compared with triolein, tristearin had little effect on hepatic gene expression or total plasma cholesterol. However, it caused a marked decrease in VLDL cholesterol and a rise in LDL cholesterol such that overall it appeared to be neutral. Lipid analysis suggested a rapid desaturation of much of the dietary stearate. The differential changes in plasma lipids and hepatic mRNA levels induced by specific dietary fats suggests a role for fatty acids or a metabolite thereof in the regulation of the expression of genes involved in lipoprotein metabolism. PMID:7575449

  13. The ATP-binding cassette transporter-2 (ABCA2) regulates cholesterol homeostasis and low-density lipoprotein receptor metabolism in N2a neuroblastoma cells.

    PubMed

    Davis, Warren

    2011-12-01

    The ATP-binding cassette transporter-2 (ABCA2) has been identified as a possible regulator of lipid metabolism. ABCA2 is most highly expressed in the brain but its effects on cholesterol homeostasis in neuronal-type cells have not been characterized. It is important to study the role of ABCA2 in regulating cholesterol homeostasis in neuronal-type cells because ABCA2 has been identified as a possible genetic risk factor for Alzheimer's disease. In this study, the effects of ABCA2 expression on cholesterol homeostasis were examined in mouse N2a neuroblastoma cells. ABCA2 reduced total, free- and esterified cholesterol levels as well as membrane cholesterol but did not perturb cholesterol distribution in organelle or lipid raft compartments. ABCA2 did not modulate de novo cholesterol biosynthesis from acetate. Cholesterol trafficking to the plasma membrane was not affected by ABCA2 but efflux to the physiological acceptor ApoE3 and mobilization of plasma membrane cholesterol to the endoplasmic reticulum for esterification were reduced by ABCA2. ABCA2 reduced esterification of serum and low-density lipoprotein-derived cholesterol but not 25-hydroxycholesterol. ABCA2 decreased low-density lipoprotein receptor (LDLR) mRNA and protein levels and increased its turnover rate. The surface expression of LDLR as well as the uptake of fluroresecent DiI-LDL was also reduced by ABCA2. Reduction of endogenous ABCA2 expression by RNAi treatment of N2a cells and rat primary cortical neurons produced the opposite effects of over-expression of ABCA2, increasing LDLR protein levels. This report identifies ABCA2 as a key regulator of cholesterol homeostasis and LDLR metabolism in neuronal cells.

  14. A novel gene silencer, pyrrole-imidazole polyamide targeting human lectin-like oxidized low-density lipoprotein receptor-1 gene improves endothelial cell function.

    PubMed

    Ueno, Takahiro; Fukuda, Noboru; Tsunemi, Akiko; Yao, En-Hui; Matsuda, Hiroyuki; Tahira, Kazunobu; Matsumoto, Taro; Matsumoto, Koichi; Matsumoto, Yoshiaki; Nagase, Hiroki; Sugiyama, Hiroshi; Sawamura, Tatsuya

    2009-03-01

    Pyrrole-imidazole polyamide can be combined in antiparallel side-by-side dimeric complexes along the minor groove of DNA in a sequence-specific manner. Pyrrole-imidazole polyamides are effective inhibitors of transcription factors as well as viral repressors and transactivators. Recently, lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) was reported to be a major factor contributing to the pathogenesis of coronary atherosclerosis. In this study, we designed a pyrrole-imidazole polyamide specific for the LOX-1 gene and evaluated its effect on LOX-1 gene transcription. A pyrrole-imidazole polyamide was designed to target the AP-1 binding site of the LOX-1 gene and synthesized by solid phase methods. This pyrrole-imidazole polyamide significantly inhibited LOX-1 promoter activity in HEK293 cells, determined by the luciferase assay. LOX-1 mRNA expression was also inhibited by the pyrrole-imidazole polyamide at a concentration of 10-9 mol/l in human umbilical vein endothelial cells (HUVEC), determined by the real-time PCR method. HUVEC were treated by pyrrole-imidazole polyamide targeting the LOX-1 gene, and apoptosis was assessed using Hoechst stain, terminal deoxy nucleotidyl transferase-mediated UTP end labeling method, and dye-uptake bioassay. Treatment of HUVEC for 72 h with LOX-1 targeted pyrrole-imidazole polyamide decreased apoptosis induced by angiotensin II and oxidized low-density lipoprotein (ox-LDL) loading in all assays. This novel therapeutic agent, pyrrole-imidazole polyamide, could specifically inhibit LOX-1 gene expression by reducing the promoter activity of the gene. Pyrrole-imidazole polyamide seems to be a powerful promising new agent that can be used to explore therapies based on inhibition of transcription. Molecular recognition of DNA by small molecules could provide insight into the development of new human medicines.

  15. [Reducing low density lipoprotein-cholesterol levels by apheresis].

    PubMed

    Reiber, I; Gógl, A

    1994-03-13

    The predominate number of homozygote familial hypercholesterolemic and approximately 20% of heterozygotes are resistant to low cholesterol diet and lipid lowering pharmacological treatment even in combination of 2 or more drugs. In such cases, the selective lipoprotein apheresis has become a promising alternative and indicated absolute (homozygotes) or relative (heterozygotes). The combination of low density lipoprotein apheresis, together with diet and drugs, should allow a maximal lowering of low density lipoprotein-cholesterol (-60-70%). Besides low density lipoprotein, various apheresis procedures may also eliminate other potentially atherogenic factors, such as lipoprotein(a) and fibrinogen and acutely improve the haemo-rheological status of the patient. The authors review several lipoprotein apheresis procedures with varying degrees of selectivity, those have and furthermore analysis the advantages and disadvantages and cost of each procedure.

  16. Human Serum Amyloid A3 (SAA3) Protein, Expressed as a Fusion Protein with SAA2, Binds the Oxidized Low Density Lipoprotein Receptor

    PubMed Central

    Tomita, Takeshi; Ieguchi, Katsuaki; Sawamura, Tatsuya; Maru, Yoshiro

    2015-01-01

    Serum amyloid A3 (SAA3) possesses characteristics distinct from the other serum amyloid A isoforms, SAA1, SAA2, and SAA4. High density lipoprotein contains the latter three isoforms, but not SAA3. The expression of mouse SAA3 (mSAA3) is known to be up-regulated extrahepatically in inflammatory responses, and acts as an endogenous ligand for the toll-like receptor 4/MD-2 complex. We previously reported that mSAA3 plays an important role in facilitating tumor metastasis by attracting circulating tumor cells and enhancing hyperpermeability in the lungs. On the other hand, human SAA3 (hSAA3) has long been regarded as a pseudogene, which is in contrast to the abundant expression levels of the other isoforms. Although the nucleotide sequence of hSAA3 is very similar to that of the other SAAs, a single oligonucleotide insertion in exon 2 causes a frame-shift to generate a unique amino acid sequence. In the present study, we identified that hSAA3 was transcribed in the hSAA2-SAA3 fusion transcripts of several human cell lines. In the fusion transcript, hSAA2 exon 3 was connected to hSAA3 exon 1 or hSAA3 exon 2, located approximately 130kb downstream from hSAA2 exon 3 in the genome, which suggested that it is produced by alternative splicing. Furthermore, we succeeded in detecting and isolating hSAA3 protein for the first time by an immunoprecipitation-enzyme linked immune assay system using monoclonal and polyclonal antibodies that recognize the hSAA3 unique amino acid sequence. We also demonstrated that hSAA3 bound oxidized low density lipoprotein receptor (oxLDL receptor, LOX-1) and elevated the phosphorylation of ERK, the intracellular MAP-kinase signaling protein. PMID:25738827

  17. Development of a conditional Mesd (mesoderm development) allele for functional analysis of the low-density lipoprotein receptor-related family in defined tissues.

    PubMed

    Taibi, Andrew V; Lighthouse, Janet K; Grady, Richard C; Shroyer, Kenneth R; Holdener, Bernadette C

    2013-01-01

    The Low-density lipoprotein receptor-Related Protein (LRP) family members are essential for diverse processes ranging from the regulation of gastrulation to the modulation of lipid homeostasis. Receptors in this family bind and internalize a diverse array of ligands in the extracellular matrix (ECM). As a consequence, LRPs regulate a wide variety of cellular functions including, but not limited to lipid metabolism, membrane composition, cell motility, and cell signaling. Not surprisingly, mutations in single human LRPs are associated with defects in cholesterol metabolism and development of atherosclerosis, abnormalities in bone density, or aberrant eye vasculature, and may be a contributing factor in development of Alzheimer's disease. Often, members of this diverse family of receptors perform overlapping roles in the same tissues, complicating the analysis of their function through conventional targeted mutagenesis. Here, we describe development of a mouse Mesd (Mesoderm Development) conditional knockout allele, and demonstrate that ubiquitous deletion of Mesd using Cre-recombinase blocks gastrulation, as observed in the traditional knockout and albino-deletion phenotypes. This conditional allele will serve as an excellent tool for future characterization of the cumulative contribution of LRP members in defined tissues.

  18. Losartan attenuates human monocyte-derived dendritic cell immune maturation via downregulation of lectin-like oxidized low-density lipoprotein receptor-1.

    PubMed

    Huang, Dong; Lu, Hao; Liu, Hongying; Yao, Kang; Sun, Aijun; Zou, Yunzeng; Ge, Junbo

    2012-08-01

    The angiotensin II receptor-1 blockers have generally been shown to have antiatherogenic effects, and dendritic cells (DCs) are the most efficient antigen presenting cells that play an active role in the development of atherosclerosis through inflammatory-immune responses. Here, we tested the hypothesis that the antiatherogenic effect of losartan, the first angiotensin II receptor-1 blockers, might partly be mediated by attenuating DCs maturation. In this study, we showed that oxidized low-density lipoprotein (oxLDL) and angiotensin II (Ang II) could induce the maturation of human monocyte-derived DCs, stimulate CD83, HLA-DR expressions and IL-12, interferon-gamma secretions and increase the capacity of DCs to stimulate T-cell proliferation, which were suppressed by losartan. OxLDL could promote the autocrine secretion of Ang II by DCs and upregulate the expressions of 3 scavenger receptors SR-A, CD36, and LOX-1. Losartan reduced oxLDL-induced LOX-1 expression but not SR-A and CD36 expressions. Ang II could only upregulate the LOX-1 expression, which was reduced by losartan. OxLDL- and Ang II-induced upregulation of CD83 and secretion of IL-12 were all attenuated by LOX-1 neutralizing antibody. In conclusion, losartan could attenuate the oxLDL- and Ang II-induced immune maturation of human monocyte-derived DCs partly through downregulation of the LOX-1 expression.

  19. Gene expression in macrophage-rich human atherosclerotic lesions. 15-lipoxygenase and acetyl low density lipoprotein receptor messenger RNA colocalize with oxidation specific lipid-protein adducts.

    PubMed Central

    Ylä-Herttuala, S; Rosenfeld, M E; Parthasarathy, S; Sigal, E; Särkioja, T; Witztum, J L; Steinberg, D

    1991-01-01

    Oxidatively modified low density lipoprotein (LDL) exhibits several potentially atherogenic properties, and inhibition of LDL oxidation in rabbits decreases the rate of the development of atherosclerotic lesions. In vitro studies have suggested that cellular lipoxygenases may be involved in LDL oxidation, and we have shown previously that 15-lipoxygenase and oxidized LDL are present in rabbit atherosclerotic lesions. We now report that epitopes of oxidized LDL are also found in macrophage-rich areas of human fatty streaks as well as in more advanced human atherosclerotic lesions. Using in situ hybridization and immunostaining techniques, we also report that 15-lipoxygenase mRNA and protein colocalize to the same macrophage-rich areas. Moreover, these same lesions express abundant mRNA for the acetyl LDL receptor but no detectable mRNA for the LDL receptor. We suggest that atherogenesis in human arteries may be linked to macrophage-induced oxidative modification of LDL mediated by 15-lipoxygenase, leading to subsequent enhanced macrophage uptake, partly by way of the acetyl LDL receptor. Images PMID:2010531

  20. The E3 Ubiquitin Ligase IDOL Induces the Degradation of the Low Density Lipoprotein Receptor Family Members VLDLR and ApoER2*

    PubMed Central

    Hong, Cynthia; Duit, Sarah; Jalonen, Pilvi; Out, Ruud; Scheer, Lilith; Sorrentino, Vincenzo; Boyadjian, Rima; Rodenburg, Kees W.; Foley, Edan; Korhonen, Laura; Lindholm, Dan; Nimpf, Johannes; van Berkel, Theo J. C.; Tontonoz, Peter; Zelcer, Noam

    2010-01-01

    We have previously identified the E3 ubiquitin ligase-inducible degrader of the low density lipoprotein receptor (LDLR) (Idol) as a post-translational modulator of LDLR levels. Idol is a direct target for regulation by liver X receptors (LXRs), and its expression is responsive to cellular sterol status independent of the sterol-response element-binding proteins. Here we demonstrate that Idol also targets two closely related LDLR family members, VLDLR and ApoE receptor 2 (ApoER2), proteins implicated in both neuronal development and lipid metabolism. Idol triggers ubiquitination of the VLDLR and ApoER2 on their cytoplasmic tails, leading to their degradation. We further show that the level of endogenous VLDLR is sensitive to cellular sterol content, Idol expression, and activation of the LXR pathway. Pharmacological activation of the LXR pathway in mice leads to increased Idol expression and to decreased Vldlr levels in vivo. Finally, we establish an unexpected functional link between LXR and Reelin signaling. We demonstrate that LXR activation results in decreased Reelin binding to VLDLR and reduced Dab1 phosphorylation. The identification of VLDLR and ApoER2 as Idol targets suggests potential roles for this LXR-inducible E3 ligase in the central nervous system in addition to lipid metabolism. PMID:20427281

  1. Acceleration of Lung Regeneration by Platelet-Rich Plasma Extract through the Low-Density Lipoprotein Receptor-Related Protein 5-Tie2 Pathway.

    PubMed

    Mammoto, Tadanori; Chen, Zhao; Jiang, Amanda; Jiang, Elisabeth; Ingber, Donald E; Mammoto, Akiko

    2016-01-01

    Angiogenesis, the growth of new blood vessels, plays a key role in organ development, homeostasis, and regeneration. The cooperation of multiple angiogenic factors, rather than a single factor, is required for physiological angiogenesis. Recently, we have reported that soluble platelet-rich plasma (PRP) extract, which contains abundant angiopoietin-1 and multiple other angiogenic factors, stimulates angiogenesis and maintains vascular integrity in vitro and in vivo. In this report, we have demonstrated that mouse PRP extract increases phosphorylation levels of the Wnt coreceptor low-density lipoprotein receptor-related protein 5 (LRP5) and thereby activates angiogenic factor receptor Tie2 in endothelial cells (ECs) and accelerates EC sprouting and lung epithelial cell budding in vitro. PRP extract also increases phosphorylation levels of Tie2 in the mouse lungs and accelerates compensatory lung growth and recovery of exercise capacity after unilateral pneumonectomy in mice, whereas soluble Tie2 receptor or Lrp5 knockdown attenuates the effects of PRP extract. Because human PRP extract is generated from autologous peripheral blood and can be stored at -80°C, our findings may lead to the development of novel therapeutic interventions for various angiogenesis-related lung diseases and to the improvement of strategies for lung regeneration.

  2. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Low-density lipoprotein immunological test system....5600 Low-density lipoprotein immunological test system. (a) Identification. A low-density lipoprotein... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  3. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Low-density lipoprotein immunological test system....5600 Low-density lipoprotein immunological test system. (a) Identification. A low-density lipoprotein... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein...

  4. Molecular cloning and partial characterization of a low-density lipoprotein receptor-related protein 13 (Lrp13) involved in vitellogenin uptake in the cutthroat trout (Oncorhynchus clarki).

    PubMed

    Mushirobira, Yuji; Mizuta, Hiroko; Luo, Wenshu; Todo, Takashi; Hara, Akihiko; Reading, Benjamin J; Sullivan, Craig V; Hiramatsu, Naoshi

    2015-12-01

    Multiple ovarian membrane proteins that bind vitellogenin (Vtg) have been detected in teleosts. One of these Vtg receptors was recently identified as low-density lipoprotein receptor-related protein 13 (lrp13/Lrp13) in perciform species, but little is known about this Vtg receptor in salmonid fish. In this study, a cDNA encoding a putative Vtg receptor with 13+1 ligand binding repeats (lr13+1) was cloned from the ovary, and identified as an lrp13 ortholog for cutthroat trout (Oncorhynchus clarki). This lrp13 was predominantly expressed in the pre-vitellogenic stage ovary, and its expression decreased during vitellogenesis. Ovarian localization of Lrp13 was observed by immunohistochemistry using specific antiserum against recombinant Lrp13. Lrp13 immunoreactivity was observed at the oolemma, throughout the zona radiata, and within the perivitelline space between the zona radiata and granulosa cells in ovarian follicles at both the lipid-droplet and vitellogenic stages of growth-an expression pattern that mimics that of a lr8/LR8-type Vtg receptor in this species and of lrp13/Lrp13 in Morone species. Six discrete Vtg-binding proteins were detected in cutthroat trout ovarian membrane proteins when probing with a digoxygenin-labeled salmonid A-type Vtg (VtgAs) followed by chemiluminescent ligand detection. Western blotting using the anti-Lrp13 serum revealed a broad signal consisting of two proteins with masses ranging from ∼190 to ∼210 kDa, which corresponded with some of the VtgA-binding proteins. These findings suggest that, in addition to lr8/LR8, lrp13/Lrp13 acts as a VtgA receptor in trout.

  5. Catalytic activity is not required for secreted PCSK9 to reduce low density lipoprotein receptors in HepG2 cells.

    PubMed

    McNutt, Markey C; Lagace, Thomas A; Horton, Jay D

    2007-07-20

    Proprotein convertase subtilisin/kexin type 9 (PCSK9), a member of the proteinase K subfamily of subtilases, promotes internalization and degradation of low density lipoprotein receptors (LDLRs) after binding the receptor on the surface of hepatocytes. PCSK9 has autocatalytic activity that releases the prodomain at the N terminus of the protein. The prodomain remains tightly associated with the catalytic domain as the complex transits the secretory pathway. It is not known whether enzymatic activity is required for the LDLR-reducing effects of PCSK9. Here we expressed the prodomain together with a catalytically inactive protease domain in cells and purified the protein from the medium. The ability of the catalytically inactive PCSK9 to bind and degrade LDLRs when added to culture medium of human hepatoma HepG2 cells at physiological concentrations was similar to that seen using wild-type protein. Similarly, a catalytic-dead version of a gain-of-function mutant, PCSK9(D374Y), showed no loss of activity compared with a catalytically active counterpart; both proteins displayed approximately 10-fold increased activity in degradation of cell surface LDLRs compared with wild-type PCSK9. We conclude that the ability of PCSK9 to degrade LDLRs is independent of catalytic activity and suggest that PCSK9 functions as a chaperone to prevent LDLR recycling and/or to target LDLRs for lysosomal degradation.

  6. The low-density lipoprotein receptor-related protein 10 is a negative regulator of the canonical Wnt/{beta}-catenin signaling pathway

    SciTech Connect

    Jeong, Young-Hee; Sekiya, Manami; Hirata, Michiko; Ye, Mingjuan; Yamagishi, Azumi; Lee, Sang-Mi; Kang, Man-Jong; Hosoda, Akemi; Fukumura, Tomoe; Kim, Dong-Ho; Saeki, Shigeru

    2010-02-19

    Wnt signaling pathways play fundamental roles in the differentiation, proliferation and functions of many cells as well as developmental, growth, and homeostatic processes in animals. Low-density lipoprotein receptor (LDLR)-related protein (LRP) 5 and LRP6 serve as coreceptors of Wnt proteins together with Frizzled receptors, triggering activation of canonical Wnt/{beta}-catenin signaling. Here, we found that LRP10, a new member of the LDLR gene family, inhibits the canonical Wnt/{beta}-catenin signaling pathway. The {beta}-catenin/T cell factor (TCF) transcriptional activity in HEK293 cells was activated by transfection with Wnt3a or LRP6, which was then inhibited by co-transfection with LRP10. Deletion of the extracellular domain of LRP10 negated its inhibitory effect. The inhibitory effect of LRP10 was consistently conserved in HEK293 cells even when GSK3{beta} phosphorylation was inhibited by incubation with lithium chloride and co-transfection with constitutively active S33Y-mutated {beta}-catenin. Nuclear {beta}-catenin accumulation was unaffected by LRP10. The present studies suggest that LRP10 may interfere with the formation of the {beta}-catenin/TCF complex and/or its binding to target DNA in the nucleus, and that the extracellular domain of LRP10 is critical for inhibition of the canonical Wnt/{beta}-catenin signaling pathway.

  7. Silent exonic mutations in the low-density lipoprotein receptor gene that cause familial hypercholesterolemia by affecting mRNA splicing.

    PubMed

    Defesche, J C; Schuurman, E J M; Klaaijsen, L N; Khoo, K L; Wiegman, A; Stalenhoef, A F H

    2008-06-01

    In a large group of patients with the clinical phenotype of familial hypercholesterolemia, such as elevated low-density lipoprotein (LDL) cholesterol and premature atherosclerosis, but without functional mutations in the genes coding for the LDL receptor and apolipoprotein B, we examined the effect of 128 seemingly neutral exonic and intronic DNA variants, discovered by routine sequencing of these genes. Two variants, G186G and R385R, were found to be associated with altered splicing. The nucleotide change leading to G186G resulted in the generation of new 3'-splice donor site in exon 4 and R385R was associated with a new 5'-splice acceptor site in exon 9 of the LDL receptor gene. Splicing of these alternate splice sites leads to an in-frame 75-base pair deletion in a stable mRNA of exon 4 in case of G186G and R385R resulted in a 31-base pair frame-shift deletion in exon 9 and non-sense-mediated mRNA decay.

  8. Identification of a small peptide that inhibits PCSK9 protein binding to the low density lipoprotein receptor.

    PubMed

    Zhang, Yingnan; Eigenbrot, Charles; Zhou, Lijuan; Shia, Steven; Li, Wei; Quan, Clifford; Tom, Jeffrey; Moran, Paul; Di Lello, Paola; Skelton, Nicholas J; Kong-Beltran, Monica; Peterson, Andrew; Kirchhofer, Daniel

    2014-01-10

    PCSK9 (proprotein convertase subtilisin/kexin type 9) is a negative regulator of the hepatic LDL receptor, and clinical studies with PCSK9-inhibiting antibodies have demonstrated strong LDL-c-lowering effects. Here we screened phage-displayed peptide libraries and identified the 13-amino acid linear peptide Pep2-8 as the smallest PCSK9 inhibitor with a clearly defined mechanism of inhibition that has been described. Pep2-8 bound to PCSK9 with a KD of 0.7 μm but did not bind to other proprotein convertases. It fully restored LDL receptor surface levels and LDL particle uptake in PCSK9-treated HepG2 cells. The crystal structure of Pep2-8 bound to C-terminally truncated PCSK9 at 1.85 Å resolution showed that the peptide adopted a strand-turn-helix conformation, which is remarkably similar to its solution structure determined by NMR. Consistent with the functional binding site identified by an Ala scan of PCSK9, the structural Pep2-8 contact region of about 400 Å(2) largely overlapped with that contacted by the EGF(A) domain of the LDL receptor, suggesting a competitive inhibition mechanism. Consistent with this, Pep2-8 inhibited LDL receptor and EGF(A) domain binding to PCSK9 with IC50 values of 0.8 and 0.4 μm, respectively. Remarkably, Pep2-8 mimicked secondary structural elements of the EGF(A) domain that interact with PCSK9, notably the β-strand and a discontinuous short α-helix, and it engaged in the same β-sheet hydrogen bonds as EGF(A) does. Although Pep2-8 itself may not be amenable to therapeutic applications, this study demonstrates the feasibility of developing peptidic inhibitors to functionally relevant sites on PCSK9.

  9. Development and application of a nonradioactive binding assay of oxidized low-density lipoprotein to macrophage scavenger receptors

    PubMed Central

    Montano, Erica N.; Boullier, Agnès; Almazan, Felicidad; Binder, Christoph J.; Witztum, Joseph L.; Hartvigsen, Karsten

    2013-01-01

    Macrophages play a key role in atherogenesis in part through excessive uptake of oxidized LDL (OxLDL) via scavenger receptors. Binding of OxLDL to macrophages has traditionally been assessed using radiolabeled OxLDL. To allow more efficient and convenient measurements, we developed a nonradioactive binding assay in which biotinylated OxLDL (Bt-OxLDL) is added to macrophages in 96-well microtiter culture plates under various conditions and the extent of binding is determined using solid phase chemiluminescent immunoassay techniques. As examples, we show that Bt-OxLDL displayed high and saturable binding to macrophages in contrast to Bt-LDL, which showed very low binding. In competition assays, unlabeled OxLDL and the anti-OxLDL monoclonal antibody E06 inhibited Bt-OxLDL binding to macrophages in a dose-dependent manner. Specific binding of Bt-OxLDL to ApoE/SR-A/CD36 triple knockout macrophages was reduced by 80% as compared with binding to macrophages from ApoE knockout mice. Binding of Bt-OxLDL to CD36 transfected COS-7 cells showed enhanced saturable binding compared with mock-transfected cells. This assay avoids the use of radioactivity and uses small amounts of materials. It can be used to study binding of OxLDL to macrophages and factors that influence this binding. The techniques described should be readily adaptable to study of other ligands, receptors, and cell types. PMID:23997238

  10. Low-density lipoprotein receptor-related protein-1 (LRP-1) expression in a rat model of oxygen-induced retinal neovascularization.

    PubMed

    Sánchez, María C; Barcelona, Pablo F; Luna, Jose D; Ortiz, Susana G; Juarez, Patricio C; Riera, Clelia M; Chiabrando, Gustavo A

    2006-12-01

    The low-density lipoprotein receptor-related protein-1 (LRP-1) is a high-molecular weight receptor of the LDL receptor gene family. Its ability to bind and internalize both proteinases and proteinase-inhibitor complexes from the extracellular space suggests that it has a major role in modulating uncontrolled retinal cell proliferation. In order to test this assumption, we investigated the expression of LRP-1 and receptor-associated ligands in a rat model of oxygen-induced retinal neovascularization. Wistar albino rats were placed into incubators at birth and exposed to an atmosphere alternating between 50% and 10% of oxygen every 24 h. After 14 days, the animals were allowed to recover in room air and sacrificed at postnatal day 20 (P20). The protein expression of LRP-1 and alpha2-macroglobulin (alpha2M) in the retina from unexposed and hyperoxia-exposed rats was investigated by Western blot. The localization of LRP-1 after neovascularization was assessed by immunohistochemical staining. The activity of metalloproteinases (MMPs) was determined by zymography. Histological analysis was done to quantitate the neovascular response in these animals. Western blot analysis showed that LRP-1 was expressed, along with alpha2M, in the retina of rats with oxygen-induced neovascularization at P20. By immunohistochemical analysis, positive staining for LRP-1 appeared in cells extending from the inner limiting membrane (ILM) to the outer limiting membrane (OLM). The cells of the retina that expressed LRP-1 were identified by immunofluorescence as Müller cells. Zymographic analysis demonstrated increased activity of MMP-2 and MMP-9 under neovascular conditions. This is the first demonstration of the involvement of LRP-1 in retinal neovascularization. In retinas of rats with oxygen-induced neovascularization, the expression of LRP-1 and alpha2M was increased along with an enhanced activity of MMPs, suggesting that LRP-1 expression may play a role in modulating retinal

  11. 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.

  12. NARC-1/PCSK9 and its natural mutants: zymogen cleavage and effects on the low density lipoprotein (LDL) receptor and LDL cholesterol.

    PubMed

    Benjannet, Suzanne; Rhainds, David; Essalmani, Rachid; Mayne, Janice; Wickham, Louise; Jin, Weijun; Asselin, Marie-Claude; Hamelin, Josée; Varret, Mathilde; Allard, Delphine; Trillard, Mélanie; Abifadel, Marianne; Tebon, Angie; Attie, Alan D; Rader, Daniel J; Boileau, Catherine; Brissette, Louise; Chrétien, Michel; Prat, Annik; Seidah, Nabil G

    2004-11-19

    The discovery of autosomal dominant hypercholesterolemic patients with mutations in the PCSK9 gene, encoding the proprotein convertase NARC-1, resulting in the missense mutations suggested a role in low density lipoprotein (LDL) metabolism. We show that the endoplasmic reticulum-localized proNARC-1 to NARC-1 zymogen conversion is Ca2+-independent and that within the zymogen autocatalytic processing site SSVFAQ [downward arrow]SIP Val at P4 and Pro at P3' are critical. The S127R and D374Y mutations result in approximately 50-60% and > or =98% decrease in zymogen processing, respectively. In contrast, the double [D374Y + N157K], F216L, and R218S natural mutants resulted in normal zymogen processing. The cell surface LDL receptor (LDLR) levels are reduced by 35% in lymphoblasts of S127R patients. The LDLR levels are also reduced in stable HepG2 cells overexpressing NARC-1 or its natural mutant S127R, and this reduction is abrogated in the presence of 5 mm ammonium chloride, suggesting that overexpression of NARC-1 increases the turnover rate of the LDLR. Adenoviral expression of wild type human NARC-1 in mice resulted in a maximal approximately 9-fold increase in circulating LDL cholesterol, while in LDLR-/- mice a delayed approximately 2-fold increase in LDL cholesterol was observed. In conclusion, NARC-1 seems to affect both the level of LDLR and that of circulating apoB-containing lipoproteins in an LDLR-dependent and -independent fashion.

  13. 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

  14. Low-density lipoprotein receptor-mediated delivery of a lipophilic daunorubicin derivative to B16 tumours in mice using apolipoprotein E-enriched liposomes.

    PubMed Central

    Versluis, A. J.; Rensen, P. C.; Rump, E. T.; Van Berkel, T. J.; Bijsterbosch, M. K.

    1998-01-01

    Many tumours express relatively high levels of low-density lipoprotein (LDL) receptors on their membranes. The LDL receptor is, therefore, an attractive target for the selective delivery of antineoplastic drugs to tumour cells. We reported previously on the synthesis of small apolipoprotein E (apoE)-containing liposomes that behave in vivo in a very similar way to native LDL. In this study, we examined the interaction of this liposomal carrier with cultured B16 melanoma cells. Binding of apoE liposomes to the cells is saturable, with a maximum binding of approximately 90000 particles per cell. Cross-competition studies indicated that apoE liposomes are bound by the LDL receptor. Association of apoE liposomes to B16 cells is strictly Ca2+ dependent, which forms additional evidence for a role of the LDL receptor. The affinity of apoE liposomes for the LDL receptor on B16 cells is 15-fold higher than that of LDL (0.77 vs 11.5 nM respectively). ApoE is essential for the LDL receptor recognition because liposomes lacking apoE were, in competition studies, 20- to 50-fold less effective than apoE-containing liposomes. We examined in B16 tumour-bearing mice the tumour-localizing properties of apoE liposomes and the disposition of an incorporated lipophilic derivative of daunorubicin (LAD). Tissue distribution studies showed that LAD-loaded apoE liposomes were taken up and processed by the major LDL receptor-expressing organs (i.e. adrenals, liver and spleen). Of all other tissues, the tumour showed the highest uptake. The distribution patterns of LAD-loaded apoE liposomes and native LDL in the tumour-bearing mice were very similar, which supports the role of the LDL receptor in the disposition of the prodrug-loaded particles. The disposition of LAD followed the pattern of the liposomal carrier. We conclude that apoE liposomes enable LDL receptor-mediated specific delivery of antineoplastic (pro)drugs to tumours, and, therefore, constitute an attractive novel option for

  15. Inflammation-induced dysfunction of the low-density lipoprotein receptor-related protein-1 at the blood-brain barrier: protection by the antioxidant N-acetylcysteine.

    PubMed

    Erickson, Michelle A; Hansen, Kim; Banks, William A

    2012-10-01

    Impairment in two blood-brain barrier (BBB) efflux transporters, p-glycoprotein (Pgp) and low-density lipoprotein receptor-related protein-1 (LRP-1) are thought to contribute to the progression of Alzheimer's disease (AD) by resulting in the brain accumulation of their substrate amyloid beta peptide (Aβ). The initial cause of impaired efflux, however, is unknown. We have shown that induction of systemic inflammation by intraperitoneal administration of lipopolysaccharide impairs the efflux of Aβ from the brain, suggesting that systemic inflammation could be one such initiator. In this study, we determined whether pre-administration of the antioxidant N-aceytlcysteine (Nac) has a protective effect against LPS-induced Aβ transporter dysfunction. Our findings were that Nac protected against LPS-induced Aβ transport dysfunction at the BBB through an LRP-1-dependent and Pgp-independent mechanism. This was associated with Nac exerting antioxidant effects in the periphery but not the brain, despite an increased rate of entry of Nac into the brain following LPS. We also found that Nac pre-administration resulted in lower blood levels of the cytokines and chemokines interferon-γ, interleukin-10, CCL2, CCL4, and CCL5, but only lowered CCL4 in the cerebral cortex and hippocampus. Finally, we observed that hippocampal cytokine responses to LPS were decreased compared to cortex. These findings demonstrate a novel mechanism by which antioxidants prevent Aβ accumulation in the brain caused by inflammation, and therefore protect against AD.

  16. Intrauterine growth restriction combined with a maternal high-fat diet increases hepatic cholesterol and low-density lipoprotein receptor activity in rats.

    PubMed

    Zinkhan, Erin K; Zalla, Jennifer M; Carpenter, Jeanette R; Yu, Baifeng; Yu, Xing; Chan, Gary; Joss-Moore, Lisa; Lane, Robert H

    2016-07-01

    Intrauterine growth restriction (IUGR) and maternal consumption of a high-saturated-fat diet (HFD) increase the risk of hypercholesterolemia, a leading cause of morbidity and mortality. Many pregnant women eat a HFD, thus exposing the fetus to a HFD in utero. The cumulative effect of in utero exposure to IUGR and a HFD on offspring cholesterol levels remains unknown. Furthermore, little is known about the mechanism through which IUGR and maternal HFD consumption increase cholesterol. We hypothesize that IUGR combined with a maternal HFD would increase offspring serum and hepatic cholesterol accumulation via alteration in levels of key proteins involved in cholesterol metabolism. To test our hypothesis we used a rat model of surgically induced IUGR and fed the dams a regular diet or a HFD HFD-fed dams consumed the same kilocalories as regular diet-fed dams, with no difference between surgical intervention groups. In the offspring, IUGR combined with a maternal HFD increased hepatic cholesterol levels, low-density lipoprotein (LDL) receptor protein levels, and Ldlr activity in female rat offspring at birth and both sexes at postnatal day 14 relative to non-IUGR offspring both from regular diet- and HFD-fed dams. These findings suggest that IUGR combined with a maternal HFD increases hepatic cholesterol accumulation via increased LDL cholesterol uptake into the liver with resulting persistent increases in hepatic cholesterol accumulation.

  17. Restraint stress up-regulates lectin-like oxidized low-density lipoprotein receptor-1 in aorta of apolipoprotein E-deficient mice.

    PubMed

    Andersson, Irene J; Sankaralingam, Sowndramalingam; Davidge, Sandra T

    2010-09-01

    Psychological stress is a risk factor for cardiovascular disease including atherosclerosis, but the mechanisms are unknown. The vascular lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in vascular pathology and early atherogenesis. We hypothesized that LOX-1 is up-regulated by psychological stress via the formation of oxygen-derived free radicals, and that treatment with EUK-8 (a superoxide dismutase and catalase mimetic) prevents production of oxygen-derived free radicals and leads to reduced expression of LOX-1 in the vascular wall. As a model for psychological stress, we exposed male apolipoprotein E-deficient mice to repeated restraint stress by placement in a conical tube for 2 h per day for 14 consecutive days. Stressed and control mice were treated with EUK-8 (n = 4-5) or vehicle (n = 4-5). Reactive oxygen species and peroxynitrite levels, as detected by oxidative fluorescence microscopy, were increased in the aortic root of mice exposed to stress compared to those of controls by 212 +/- 22% (mean +/- SEM; p < 0.001) and 110 +/- 6% (p < 0.001), respectively. LOX-1, as detected by immunohistochemistry, was increased by 443 +/- 63% in stressed mice compared to control mice (p < 0.001). EUK-8 reduced reactive oxygen species, peroxynitrite, and LOX-1 levels in stressed mice compared to vehicle-treated stressed mice. To conclude, LOX-1 induced by reactive oxygen species and/or peroxynitrite could be one mechanism by which stress promotes cardiovascular disease.

  18. Lupin Peptides Modulate the Protein-Protein Interaction of PCSK9 with the Low Density Lipoprotein Receptor in HepG2 Cells

    NASA Astrophysics Data System (ADS)

    Lammi, Carmen; Zanoni, Chiara; Aiello, Gilda; Arnoldi, Anna; Grazioso, Giovanni

    2016-07-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recently identified as a new useful target for hypercholesterolemia treatment. This work demonstrates that natural peptides, deriving from the hydrolysis of lupin protein and absorbable at intestinal level, are able to inhibit the protein-protein interaction between PCSK9 and the low density lipoprotein receptor (LDLR). In order to sort out the best potential inhibitors among these peptides, a refined in silico model of the PCSK9/LDLR interaction was developed. Docking, molecular dynamics (MD) simulations and peptide binding energy estimations, by MM-GBSA approach, permitted to select the two best candidates among tested peptides that were synthesized and evaluated for their inhibitory activity. The most active was P5 that induced a concentration dependent inhibition of the PCSK9-LDLR binding, with an IC50 value equal to 1.6 ± 0.33 μM. Tested at a 10 μM concentration, this peptide increased by 66 ± 21.4% the ability of HepG2 cells to take up LDL from the extracellular environment.

  19. Lupin Peptides Modulate the Protein-Protein Interaction of PCSK9 with the Low Density Lipoprotein Receptor in HepG2 Cells

    PubMed Central

    Lammi, Carmen; Zanoni, Chiara; Aiello, Gilda; Arnoldi, Anna; Grazioso, Giovanni

    2016-01-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) has been recently identified as a new useful target for hypercholesterolemia treatment. This work demonstrates that natural peptides, deriving from the hydrolysis of lupin protein and absorbable at intestinal level, are able to inhibit the protein-protein interaction between PCSK9 and the low density lipoprotein receptor (LDLR). In order to sort out the best potential inhibitors among these peptides, a refined in silico model of the PCSK9/LDLR interaction was developed. Docking, molecular dynamics (MD) simulations and peptide binding energy estimations, by MM-GBSA approach, permitted to select the two best candidates among tested peptides that were synthesized and evaluated for their inhibitory activity. The most active was P5 that induced a concentration dependent inhibition of the PCSK9-LDLR binding, with an IC50 value equal to 1.6 ± 0.33 μM. Tested at a 10 μM concentration, this peptide increased by 66 ± 21.4% the ability of HepG2 cells to take up LDL from the extracellular environment. PMID:27424515

  20. Expressions of the low density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase genes are stimulated by recombinant platelet-derived growth factor isomers

    SciTech Connect

    Roth, M.; Emmons, L.R.; Perruchoud, A. ); Block, L.H. )

    1991-03-01

    The plausible role that platelet-derived growth factor (PDGF) has in the localized pathophysiological changes that occur in the arterial wall during development of atherosclerotic lesions led the authors to investigate the influence of recombinant (r)PDGF isomers -AA, -AB, and -BB on the expression of low density lipoprotein receptor (LDL-R) and 3-hydroxy-3-methylglutaryl coenzyme A (HMG0CoA) reductase ((S)-mevalonate:NAD{sup +} oxidoreductase (CoA-acylating), EC 1.1.1.88) genes. In addition, they clarified the role of protein kinase C (PKC) in expression of the two genes in human skin fibroblasts and vascular smooth muscle cells. The various rPDGF isoforms are distinct in their ability to activate transcription of both genes: (i) both rPDGF-AA and -BB stimulate transcription of the LDL-R gene; in contrast, rPDGF-BB but not -AA, activates transcription of the HMG-CoA reductase gene; (ii) all recombinant isoforms of PDGF activate transcription of the c-fos gene; (iii) while rPDGF-dependent transcription of the lDL-R gene occurs independently of PKC, transcription of the HMG-CoA reductase gene appears to involve the action of that enzyme.

  1. A novel class of antihyperlipidemic agents with low density lipoprotein receptor up-regulation via the adaptor protein autosomal recessive hypercholesterolemia.

    PubMed

    Asano, Shigehiro; Ban, Hitoshi; Tsuboya, Norie; Uno, Shinsaku; Kino, Kouichi; Ioriya, Katsuhisa; Kitano, Masafumi; Ueno, Yoshihide

    2010-04-22

    We have previously reported compound 2 as a inhibitor of acyl-coenzyme A:cholesterol O-acyltransferase (ACAT) and up-regulator of the low density lipoprotein receptor (LDL-R) expression. In this study we focused on compound 2, a unique LDL-R up-regulator, and describe the discovery of a novel class of up-regulators of LDL-R. Replacement the methylene urea linker in compound 2 with an acylsulfonamide linker kept a potent LDL-R up-regulatory activity, and subsequent optimization work gave compound 39 as a highly potent LDL-R up-regulator (39; EC(25) = 0.047 microM). Compound 39 showed no ACAT inhibitory activity even at 1 microM. The sodium salts of compound 39 reduced plasma total and LDL cholesterol levels in a dose-dependent manner in an experimental animal model of hyperlipidemia. Moreover, we revealed in this study using RNA interference that autosomal recessive hypercholesterolemia (ARH), an adaptor protein of LDL-R, is essential for compound 39 up-regulation of LDL-R expression.

  2. The Trypanosoma cruzi neuraminidase contains sequences similar to bacterial neuraminidases, YWTD repeats of the low density lipoprotein receptor, and type III modules of fibronectin

    PubMed Central

    1991-01-01

    Trypanosoma cruzi expresses a developmentally regulated neuraminidase (TCNA) implicated in parasite invasion of cells. We isolated full- length DNA clones encoding TCNA. Sequence analysis demonstrated an open reading frame coding for a polypeptide of 1,162 amino acids. In the N- terminus there is a cysteine-rich domain containing a stretch of 332 amino acids nearly 30% identical to the Clostridium perfringens neuraminidase, three repeat motifs highly conserved in bacterial and viral neuraminidases, and two segments with similarity to the YWTD repeats found in the low density lipoprotein (LDL) receptor and in other vertebrate and invertebrate proteins. This domain is connected by a structure characteristic of type III modules of fibronectin to a long terminal repeat (LTR) consisting of 44 full length copies of twelve amino acids rich (75%) in serine, threonine, and proline. LTR is unusual in that it contains at least 117 potential phosphorylation sites. At the extreme C-terminus is a hydrophobic segment of 35 amino acids, which could mediate anchorage of TCNA to membranes via a glycosylphosphatidylinositol linkage. This is the first time a protozoan protein has been found to contain a YWTD repeat and a fibronectin type III module. The domain structure of TCNA suggests that the enzyme may have functions additional to its catalytic activity such as in protein-protein interaction, which could play a role in T. cruzi binding to host cells. PMID:1711561

  3. Exon organization of the mouse entactin gene corresponds to the structural domains of the polypeptide and has regional homology to the low-density lipoprotein receptor gene

    SciTech Connect

    Durkin, M.E.; Chung, A.E.; Wewer, U.M.

    1995-03-20

    Entactin is a widespread basement membrane protein of 150 kDa that binds to type IV collagen and laminin. The complete exon-intron structure of the mouse entactin gene has been determined from {lambda} genomic DNA clones. The gene spans at least 65 kb and contains 20 exons. The exon organization of the mouse entactin gene closely corresponds to the organization of the polypeptide into distinct structural and functional domains. The two amino-terminal globular domains are encoded by three exons each. Single exons encode the two protease-sensitive, O-glycosylated linking regions. The six EGF-like repeats and the single thyroglobulin-type repeat are each encoded by separate exons. The carboxyl-terminal half of entactin displays sequence homology to the growth factor-like region of the low-density lipoprotein receptor, and in both genes this region is encoded by eight exons. The positions of four introns are also conserved in the homologous region of the two genes. These observations suggest that the entactin gene has evolved via exon shuffling. Finally, several sequence polymorphisms useful for gene linkage analysis were found in the 3{prime} noncoding region of the last exon. 52 refs., 8 figs.

  4. The association of very low-density lipoprotein receptor (VLDLR) haplotypes with egg production indicates VLDLR is a candidate gene for modulating egg production

    PubMed Central

    Wang, ZhePeng; Meng, GuoHua; Li, Na; Yu, MingFen; Liang, XiaoWei; Min, YuNa; Liu, FuZhu; Gao, YuPeng

    2016-01-01

    Abstract The very low-density lipoprotein receptor (VLDLR) transports egg yolk precursors into oocytes. However, our knowledge of the distribution patterns of VLDLR variants among breeds and their relationship to egg production is still incomplete. In this study, eight single nucleotide polymorphisms (SNPs) that account for 87% of all VLDLR variants were genotyped in Nick Chick (NC, n=91), Lohmann Brown (LohB, n=50) and Lueyang (LY, n=381) chickens, the latter being an Chinese indigenous breed. Egg production by NC and LY chickens was recorded from 17 to 50 weeks. Only four similar haplotypes were found in NC and LohB, of which two accounted for 100% of all NC haplotypes and 92.5% of LohB haplotypes. In contrast, there was considerable haplotypic diversity in LY. Comparison of egg production in LY showed that hens with NC-like haplotypes had a significantly higher production (p < 0.05) than those without the haplotypes. However, VLDLR expression was not significantly different between the haplotypes. These findings indicate a divergence in the distribution of VLDLR haplotypes between selected and non-selected breeds and suggest that the near fixation of VLDLR variants in NC and LohB is compatible with signature of selection. These data also support VLDLR as a candidate gene for modulating egg production. PMID:27560838

  5. 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.

  6. Activated α2 -Macroglobulin Induces Mesenchymal Cellular Migration Of Raw264.7 Cells Through Low-Density Lipoprotein Receptor-Related Protein 1.

    PubMed

    Ferrer, Darío G; Dato, Virginia Actis; Fincati, Javier R Jaldín; Lorenc, Valeria E; Sánchez, María C; Chiabrando, Gustavo A

    2016-12-24

    Distinct modes of cell migration contribute to diverse types of cell movements. The mesenchymal mode is characterized by a multistep cycle of membrane protrusion, the formation of focal adhesion, and the stabilization at the leading edge associated with the degradation of extracellular matrix (ECM) components and with regulated extracellular proteolysis. Both α2 -Macroglobulin (α2 M) and its receptor, low density lipoprotein receptor-related protein 1 (LRP1), play important roles in inflammatory processes, by controlling the extracellular activity of several proteases. The binding of the active form of α2 M (α2 M*) to LRP1 can also activate different signaling pathways in macrophages, thus inducing extracellular matrix metalloproteinase-9 (MMP-9) activation and cellular proliferation. In the present study, we investigated whether the α2 M*/LRP1 interaction induces cellular migration of the macrophage-derived cell line, Raw264.7. By using the wound-scratch migration assay and confocal microscopy, we demonstrate that α2 M* induces LRP1-mediated mesenchymal cellular migration. This migration exhibits the production of enlarged cellular protrusions, MT1-MMP distribution to these leading edge protrusions, actin polymerization, focal adhesion formation, and increased intracellular LRP1/β1-integrin colocalization. Moreover, the presence of calphostin-C blocked the α2 M*-stimulated cellular protrusions, suggesting that the PKC activation is involved in the cellular motility of Raw264.7 cells. These findings could constitute a therapeutic target for inflammatory processes with deleterious consequences for human health, such as rheumatoid arthritis, atherosclerosis and cancer. J. Cell. Biochem. 9999: 1-9, 2017. © 2016 Wiley Periodicals, Inc.

  7. Taurine suppresses oxidative stress-potentiated expression of lectin-like oxidized low-density lipoprotein receptor and restenosis in balloon-injured rabbit iliac artery.

    PubMed

    Gokce, G; Ozsarlak-Sozer, G; Oran, I; Oktay, G; Ozkal, S; Kerry, Z

    2011-12-01

    1. In endothelial cells, the major receptor for the binding and internalization of oxidized low-density lipoprotein (LDL) is the lectin-like oxidized LDL receptor (LOX-1). The aim of the present study was to investigate the effects of taurine on intimal thickening and LOX-1 expression under normal and oxidative conditions. 2. The iliac artery of rabbits were subjected to balloon injury and oxidative stress was induced by 14 days treatment of rabbits with 75 mg/kg, s.c., buthionine sulfoximine (BSO), a specific inhibitor of glutathione synthesis. Taurine was administered in drinking water (1%, w/v) for 14 days in the presence (BSO + Taurine group) and in the absence of BSO treatment (Taurine group). In taurine and placebo groups, rabbits were injected with 4 mL, s.c., 0.9% NaCl (vehicle for BSO) for 14 days. 3. Taurine (1% in drinking water, w/v) preserved plasma levels of anti-oxidants and lowered the increased blood pressure induced by BSO. The stenosis rate of 29.92% in the placebo group increased to 72.20% in the BSO group, which was significantly reduced to 42.21% by taurine (P < 0.001; n = 5). Localization of LOX-1 to the intima and media of the iliac artery was demonstrated in the present study. Taurine treatment reduced the BSO-induced increase in LOX-1 expression at both the protein and mRNA levels (P < 0.05 and P < 0.01, respectively). 4. The results demonstrate that the stenosis rate and LOX-1 expression correlate well with oxidative status. Manipulation of LOX-1 expression by taurine may have therapeutic benefits in preventing restenosis.

  8. Adaptor protein ARH is recruited to the plasma membrane by low density lipoprotein (LDL) binding and modulates endocytosis of the LDL/LDL receptor complex in hepatocytes.

    PubMed

    Sirinian, Maria Isabella; Belleudi, Francesca; Campagna, Filomena; Ceridono, Mara; Garofalo, Tina; Quagliarini, Fabiana; Verna, Roberto; Calandra, Sebastiano; Bertolini, Stefano; Sorice, Maurizio; Torrisi, Maria Rosaria; Arca, Marcello

    2005-11-18

    ARH is a newly discovered adaptor protein required for the efficient activity of low density lipoprotein receptor (LDLR) in selected tissues. Individuals lacking ARH have severe hypercholesterolemia due to an impaired hepatic clearance of LDL. It has been demonstrated that ARH is required for the efficient internalization of the LDL-LDLR complex and to stabilize the association of the receptor with LDL in Epstein-Barr virus-immortalized B lymphocytes. However, little information is available on the role of ARH in liver cells. Here we provide evidence that ARH is codistributed with LDLR on the basolateral area in confluent HepG2-polarized cells. This distribution is not modified by the overexpression of LDLR. Conversely, the activation of the LDLR-mediated endocytosis, but not the binding of LDL to LDLR, promotes a significant colocalization of ARH with LDL-LDLR complex that peaked at 2 min at 37 degrees C. To further assess the role of ARH in LDL-LDLR complex internalization, we depleted ARH protein using the RNA interference technique. Twenty-four hours after transfection with ARH-specific RNA interference, ARH protein was depleted in HepG2 cells by more than 70%. Quantitative immunofluorescence analysis revealed that the depletion of ARH caused about 80% reduction in LDL internalization. Moreover, our findings indicate that ARH is associated with other proteins of the endocytic machinery. We suggest that ARH is an endocytic sorting adaptor that actively participates in the internalization of the LDL-LDLR complex, possibly enhancing the efficiency of its packaging into the endocytic vesicles.

  9. Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

    PubMed

    Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

    2015-07-01

    Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD.

  10. Cloning of a cDNA encoding a putative human very low density lipoprotein/Apolipoprotein E receptor and assignment of the gene to chromosome 9pter-p23[sup 6

    SciTech Connect

    Gafvels, M.E.; Strauss, J.F. III ); Caird, M.; Patterson, D. ); Britt, D.; Jackson, C.L. )

    1993-11-01

    The authors report the cloning of a 3656-bp cDNA encoding a putative human very low density lipoprotein (VLDL)/apolipoprotein E (ApoE) receptor. The gene encoding this protein was mapped to chromosome 9pter-p23. Northern analysis of human RNA identified cognate mRNAs of 6.0 and 3.8 kb with most abundant expression in heart and skeletal muscle, followed by kidney, placenta, pancreas, and brain. The pattern of expression generally paralleled that of lipoprotein lipase mRNA but differed from that of the low density lipoprotein (LDL) receptor and the low density lipoprotein receptor-related protein/[alpha][sub 2]-macroglobulin receptor (LRP), which are members of the same gene family. VLDL/ApoE receptor message was not detected in liver, whereas mRNAs for both LDL receptor and LRP were found in hepatic tissue. In mouse 3T3-L1 cells, VLDL/ApoE receptor mRNA was induced during the transformation of the cells into adipocytes. Expression was also detected in human choriocarcinoma cells, suggesting that at least part of the expression observed in placenta may be in trophoblasts, cells which would be exposed to maternal blood. Expression in brain may be related to high levels of ApoE expression in that organ, an observation of potential relevance to the recently hypothesized role for ApoE in late onset Alzheimer disease. The results suggest that the putative VLDL/ApoE receptor could play a role in the uptake of triglyceride-rich lipoprotein particles by specific organs including striated and cardiac muscle and adipose tissue and in the transport of maternal lipids across the placenta. The findings presented here, together with recent observations from other laboratories, bring up the possibility that a single gene, the VLDL/ApoE receptor, may play a role in the pathogenesis of certain forms of atherosclerosis, Alzheimer disease, and obesity.

  11. 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

  12. Generation of a Potent Low Density Lipoprotein Receptor-related Protein 1 (LRP1) Antagonist by Engineering a Stable Form of the Receptor-associated Protein (RAP) D3 Domain.

    PubMed

    Prasad, Joni M; Migliorini, Mary; Galisteo, Rebeca; Strickland, Dudley K

    2015-07-10

    The low density lipoprotein receptor-related protein 1 (LRP1) is a member of the low density lipoprotein receptor family and plays important roles in a number of physiological and pathological processes. Expression of LRP1 requires the receptor-associated protein (RAP), a molecular chaperone that binds LRP1 and other low density lipoprotein receptor family members in the endoplasmic reticulum and traffics with them to the Golgi where the acidic environment causes its dissociation. Exogenously added RAP is a potent LRP1 antagonist and binds to LRP1 on the cell surface, preventing ligands from binding. Following endocytosis, RAP dissociates in the acidic endosome, allowing LRP1 to recycle back to the cell surface. The acid-induced dissociation of RAP is mediated by its D3 domain, a relatively unstable three-helical bundle that denatures at pH <6.2 due to protonation of key histidine residues on helices 2 and 3. To develop an LRP1 inhibitor that does not dissociate at low pH, we introduced a disulfide bond between the second and third helices in the RAP D3 domain. By combining this disulfide bond with elimination of key histidine residues, we generated a stable RAP molecule that is resistant to both pH- and heat-induced denaturation. This molecule bound to LRP1 with high affinity at both neutral and acidic pH and proved to be a potent inhibitor of LRP1 function both in vitro and in vivo, suggesting that our stable RAP molecule may be useful in multiple pathological settings where LRP1 blockade has been shown to be effective.

  13. Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Single Domain Antibodies Are Potent Inhibitors of Low Density Lipoprotein Receptor Degradation.

    PubMed

    Weider, Elodie; Susan-Resiga, Delia; Essalmani, Rachid; Hamelin, Josée; Asselin, Marie-Claude; Nimesh, Surendra; Ashraf, Yahya; Wycoff, Keith L; Zhang, Jianbing; Prat, Annik; Seidah, Nabil G

    2016-08-05

    Single domain antibodies (sdAbs) correspond to the antigen-binding domains of camelid antibodies. They have the same antigen-binding properties and specificity as monoclonal antibodies (mAbs) but are easier and cheaper to produce. We report here the development of sdAbs targeting human PCSK9 (proprotein convertase subtilisin/kexin type 9) as an alternative to anti-PCSK9 mAbs. After immunizing a llama with human PCSK9, we selected four sdAbs that bind PCSK9 with a high affinity and produced them as fusion proteins with a mouse Fc. All four sdAb-Fcs recognize the C-terminal Cys-His-rich domain of PCSK9. We performed multiple cellular assays and demonstrated that the selected sdAbs efficiently blocked PCSK9-mediated low density lipoprotein receptor (LDLR) degradation in cell lines, in human hepatocytes, and in mouse primary hepatocytes. We further showed that the sdAb-Fcs do not affect binding of PCSK9 to the LDLR but rather block its induced cellular LDLR degradation. Pcsk9 knock-out mice expressing a human bacterial artificial chromosome (BAC) transgene were generated, resulting in plasma levels of ∼300 ng/ml human PCSK9. Mice were singly or doubly injected with the best sdAb-Fc and analyzed at day 4 or 11, respectively. After 4 days, mice exhibited a 32 and 44% decrease in the levels of total cholesterol and apolipoprotein B and ∼1.8-fold higher liver LDLR protein levels. At 11 days, the equivalent values were 24 and 46% and ∼2.3-fold higher LDLR proteins. These data constitute a proof-of-principle for the future usage of sdAbs as PCSK9-targeting drugs that can efficiently reduce LDL-cholesterol, and as tools to study the Cys-His-rich domain-dependent sorting the PCSK9-LDLR complex to lysosomes.

  14. Two novel susceptibility loci for non-small cell lung cancer map to low-density lipoprotein receptor-related protein 5

    PubMed Central

    Wang, Ying; Zhang, Yongjun; Fang, Meiyu; Bao, Wenglong; Deng, Dehou

    2016-01-01

    This study investigated the effect of single-nucleotide polymorphisms (SNPs) of low-density lipoprotein receptor-related protein 5 (LRP5) on the risk of developing non-small cell lung cancer (NSCLC). A total of 500 NSCLC patients and 500 healthy controls were recruited for genotyping of 11 SNPs of LRP5. The association between genotype and NSCLC risk was evaluated by computing the odds ratio (OR) and 95% confidence interval (CI) from multivariate unconditional logistic regression analyses. Eleven Tag SNPs were detected. The frequency of the LRP5 rs3736228 T allele (18.9% in male NSCLC cases and 23.9% in male controls) was statistically different between male NSCLCs and male controls (P=0.03), and the T allele was associated with a lower risk of NSCLC (OR=0.74; 95% CI, 0.56–0.67), whereas the C/C homozygous genotype and the LRP5 rs64843 T/T genotype were associated with an increased risk of NSCLC and squamous cell carcinoma (SCC), respectively (OR=1.43 and 1.77, respectively). Using Haploview software, the frequency of the haplotypes of rs312009/rs3120015/rs3120014 CCC was was significantly higher in female SCC cases compared with female controls (0.064 vs. 0.009, P=0.04). LRP5 rs3736228 and rs64843 SNPs were significantly associated with an increased risk of NSCLC and SCC, respectively. Further studies are required to investigate the functional changes in LRP5 expression and activity in NSCLC in vitro. PMID:27698794

  15. High Levels of Soluble Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Acute Stroke: An Age- and Sex-Matched Cross-Sectional Study

    PubMed Central

    Sawamura, Tatsuya; Watanabe, Makoto; Kokubo, Yoshihiro; Fujita, Yoshiko; Kakino, Akemi; Nakai, Michikazu; Toyoda, Kazunori; Miyamoto, Yoshihiro; Minematsu, Kazuo

    2016-01-01

    Aim: Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is known to be a key molecule in the pathogenesis of atherosclerosis. Although high levels of serum soluble LOX-1 (sLOX-1) were demonstrated in patients with acute coronary syndrome, there are no reports about acute stroke patients. The aim of the present study was to evaluate the levels of sLOX-1 in acute stroke patients according to different stroke subtypes. Methods: We enrolled a total of 377 patients with a stroke (men/women: 251/126; age: 40–79 years), 250 with ischemic stroke and 127 with intracerebral hemorrhage (ICH). Patients were admitted to our hospital within 3 days after the onset of stroke. As controls, we randomly selected age- and sex-matched subjects without a past history of cardiovascular disease according to stroke subtype from the community-based cohort of the Suita study. Serum LOX-1 levels were compared between stroke patients and healthy controls according to stroke subtype. Results: Median values of serum sLOX-1 in stroke patients were significantly higher than those in controls (526 vs. 486 ng/L in ischemic stroke and 720 vs. 513 ng/L in ICH, respectively). Among subtypes of ischemic stroke, median sLOX-1 levels in atherothrombotic brain infarction (641 ng/L) only were significantly higher than those in controls (496 ng/L). Ischemic stroke [odds ratio (OR), 3.80; 95% confidence interval (CI), 1.86–7.74] and ICH (OR, 5.97; 95% CI, 2.13–16.77) were independently associated with high levels of sLOX-1 by multivariate logistic regression analysis. Conclusions: Higher levels of sLOX-1 were observed in patients with acute stoke than in controls. High levels of sLOX-1 can be useful as biomarker for acute stroke. PMID:27025681

  16. Increased beta-amyloid levels in the choroid plexus following lead exposure and the involvement of low-density lipoprotein receptor protein-1.

    PubMed

    Behl, Mamta; Zhang, Yanshu; Monnot, Andrew D; Jiang, Wendy; Zheng, Wei

    2009-10-15

    The choroid plexus, a barrier between the blood and cerebrospinal fluid (CSF), is known to accumulate lead (Pb) and also possibly function to maintain brain's homeostasis of Abeta, an important peptide in the etiology of Alzheimer's disease. This study was designed to investigate if Pb exposure altered Abeta levels at the blood-CSF barrier in the choroid plexus. Rats received ip injection of 27 mg Pb/kg. Twenty-four hours later, a FAM-labeled Abeta (200 pmol) was infused into the lateral ventricle and the plexus tissues were removed to quantify Abeta accumulation. Results revealed a significant increase in intracellular Abeta accumulation in the Pb-exposed animals compared to controls (p<0.001). When choroidal epithelial Z310 cells were treated with 10 microM Pb for 24 h and 48 h, Abeta (2 microM in culture medium) accumulation was significantly increased by 1.5 fold (p<0.05) and 1.8 fold (p<0.05), respectively. To explore the mechanism, we examined the effect of Pb on low-density lipoprotein receptor protein-1 (LRP1), an intracellular Abeta transport protein. Following acute Pb exposure with the aforementioned dose regimen, levels of LRP1 mRNA and proteins in the choroid plexus were decreased by 35% (p<0.05) and 31.8% (p<0.05), respectively, in comparison to those of controls. In Z310 cells exposed to 10 microM Pb for 24 h and 48 h, a 33.1% and 33.4% decrease in the protein expression of LRP1 was observed (p<0.05), respectively. Knocking down LRP1 resulted in even more substantial increases of cellular accumulation of Abeta, from 31% in cells without knockdown to 72% in cells with LRP1 knockdown (p<0.05). Taken together, these results suggest that the acute exposure to Pb results in an increased accumulation of intracellular Abeta in the choroid plexus; the effect appears to be mediated, at least in part, via suppression of LRP1 production following Pb exposure.

  17. Increased {beta}-amyloid levels in the choroid plexus following lead exposure and the involvement of low-density lipoprotein receptor protein-1

    SciTech Connect

    Behl, Mamta; Zhang Yanshu; Monnot, Andrew D.; Jiang, Wendy; Zheng Wei

    2009-10-15

    The choroid plexus, a barrier between the blood and cerebrospinal fluid (CSF), is known to accumulate lead (Pb) and also possibly function to maintain brain's homeostasis of A{beta}, an important peptide in the etiology of Alzheimer's disease. This study was designed to investigate if Pb exposure altered A{beta} levels at the blood-CSF barrier in the choroid plexus. Rats received ip injection of 27 mg Pb/kg. Twenty-four hours later, a FAM-labeled A{beta} (200 pmol) was infused into the lateral ventricle and the plexus tissues were removed to quantify A{beta} accumulation. Results revealed a significant increase in intracellular A{beta} accumulation in the Pb-exposed animals compared to controls (p < 0.001). When choroidal epithelial Z310 cells were treated with 10 {mu}M Pb for 24 h and 48 h, A{beta} (2 {mu}M in culture medium) accumulation was significantly increased by 1.5 fold (p < 0.05) and 1.8 fold (p < 0.05), respectively. To explore the mechanism, we examined the effect of Pb on low-density lipoprotein receptor protein-1 (LRP1), an intracellular A{beta} transport protein. Following acute Pb exposure with the aforementioned dose regimen, levels of LRP1 mRNA and proteins in the choroid plexus were decreased by 35% (p < 0.05) and 31.8% (p < 0.05), respectively, in comparison to those of controls. In Z310 cells exposed to 10 {mu}M Pb for 24 h and 48 h, a 33.1% and 33.4% decrease in the protein expression of LRP1 was observed (p < 0.05), respectively. Knocking down LRP1 resulted in even more substantial increases of cellular accumulation of A{beta}, from 31% in cells without knockdown to 72% in cells with LRP1 knockdown (p < 0.05). Taken together, these results suggest that the acute exposure to Pb results in an increased accumulation of intracellular A{beta} in the choroid plexus; the effect appears to be mediated, at least in part, via suppression of LRP1 production following Pb exposure.

  18. Detection of early stage atherosclerotic plaques using PET and CT fusion imaging targeting P-selectin in low density lipoprotein receptor-deficient mice

    SciTech Connect

    Nakamura, Ikuko; Hasegawa, Koki; Wada, Yasuhiro; Hirase, Tetsuaki; Node, Koichi; Watanabe, Yasuyoshi

    2013-03-29

    Highlights: ► P-selectin regulates leukocyte recruitment as an early stage event of atherogenesis. ► We developed an antibody-based molecular imaging probe targeting P-selectin for PET. ► This is the first report on successful PET imaging for delineation of P-selectin. ► P-selectin is a candidate target for atherosclerotic plaque imaging by clinical PET. -- Abstract: Background: Sensitive detection and qualitative analysis of atherosclerotic plaques are in high demand in cardiovascular clinical settings. The leukocyte–endothelial interaction mediated by an adhesion molecule P-selectin participates in arterial wall inflammation and atherosclerosis. Methods and results: A {sup 64}Cu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid conjugated anti-P-selectin monoclonal antibody ({sup 64}Cu-DOTA-anti-P-selectin mAb) probe was prepared by conjugating an anti-P-selectin monoclonal antibody with DOTA followed by {sup 64}Cu labeling. Thirty-six hours prior to PET and CT fusion imaging, 3 MBq of {sup 64}Cu-DOTA-anti-P-selectin mAb was intravenously injected into low density lipoprotein receptor-deficient Ldlr-/- mice. After a 180 min PET scan, autoradiography and biodistribution of {sup 64}Cu-DOTA-anti-P-selectin monoclonal antibody was examined using excised aortas. In Ldlr-/- mice fed with a high cholesterol diet for promotion of atherosclerotic plaque development, PET and CT fusion imaging revealed selective and prominent accumulation of the probe in the aortic root. Autoradiography of aortas that demonstrated probe uptake into atherosclerotic plaques was confirmed by Oil red O staining for lipid droplets. In Ldlr-/- mice fed with a chow diet to develop mild atherosclerotic plaques, probe accumulation was barely detectable in the aortic root on PET and CT fusion imaging. Probe biodistribution in aortas was 6.6-fold higher in Ldlr-/- mice fed with a high cholesterol diet than in those fed with a normal chow diet. {sup 64}Cu-DOTA-anti-P-selectin m

  19. Oxidized low-density lipoprotein alters endothelial progenitor cell populations.

    PubMed

    Cui, Yuqi; Narasimhulu, Chandrakala A; Liu, Lingjuan; Li, Xin; Xiao, Yuan; Zhang, Jia; Xie, Xiaoyun; Hao, Hong; Liu, Jason Z; He, Guanglong; Cowan, Peter J; Cui, Lianqun; Zhu, Hua; Parthasarathy, Sampath; Liu, Zhenguo

    2015-06-01

    Oxidized low-density lipoprotein (ox-LDL) is critical to atherosclerosis in hyperlipidemia. Bone marrow (BM)-derived endothelial progenitor cells (EPCs) are important to preventing atherosclerosis, and significantly decreased in hyperlipidemia. This study was to demonstrate ox-LDL and hyperlipidemia could exhibit similar effect on EPC population and the role of reactive oxygen species (ROS). ROS production in BM and blood was significantly increased in male C57BL/6 mice with intravenous ox-LDL treatment, and in hyperlipidemic LDL receptor knockout mice with 4-month high-fat diet. ROS formation was effectively blocked with overexpression of antioxidant enzymes or N-acetylcysteine treatment. In hyperlipidemic and ox-LDL-treated mice, c-Kit(+)/CD31(+) cell number in BM and blood, and Sca-1(+)/Flk-1(+) cell number in blood, not in BM, were significantly decreased, which were not affected by inhibiting ROS production, while blood CD34(+)/Flk-1(+) cell number was significantly increased that was prevented with reduced ROS formation. However, blood CD34(+)/CD133(+) cell number increased in ox-LDL-treated mice, while decreased in hyperlipidemic mice. These data suggested that ox-LDL produced significant changes in BM and blood EPC populations similar (but not identical) to chronic hyperlipidemia with predominantly ROS-independent mechanism(s).

  20. Low-density lipoprotein density determination by electric conductivity.

    PubMed

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

    2011-10-15

    The predominance of small dense low-density lipoprotein (LDL) particles is associated with an increased risk of coronary heart disease. A simple but precise method has been developed, based on electrical conductivity of an isopycnic gradient of KBr, to obtain density values of human LDL fraction. The results obtained can distinguish LDL density populations and their subfractions from different patients. These data were corroborated by Fourier transform infrared spectroscopy (FTIR) (structure) and light-scattering analyses (size).

  1. Echium Oil Reduces Plasma Triglycerides by Increasing Intravascular Lipolysis in apoB100-Only Low Density Lipoprotein (LDL) Receptor Knockout Mice

    PubMed Central

    Forrest, Lolita M.; Lough, Christopher M.; Chung, Soonkyu; Boudyguina, Elena Y.; Gebre, Abraham K.; Smith, Thomas L.; Colvin, Perry L.; Parks, John S.

    2013-01-01

    Echium oil (EO), which is enriched in SDA (18:4 n-3), reduces plasma triglyceride (TG) concentrations in humans and mice. We compared mechanisms by which EO and fish oil (FO) reduce plasma TG concentrations in mildly hypertriglyceridemic male apoB100-only LDLrKO mice. Mice were fed one of three atherogenic diets containing 0.2% cholesterol and palm oil (PO; 20%), EO (10% EO + 10% PO), or FO (10% FO + 10% PO). Livers from PO- and EO-fed mice had similar TG and cholesteryl ester (CE) content, which was significantly higher than in FO-fed mice. Plasma TG secretion was reduced in FO vs. EO-fed mice. Plasma very low density lipoprotein (VLDL) particle size was ordered: PO (63 ± 4 nm) > EO (55 ± 3 nm) > FO (40 ± 2 nm). Post-heparin lipolytic activity was similar among groups, but TG hydrolysis by purified lipoprotein lipase was significantly greater for EO and FO VLDL compared to PO VLDL. Removal of VLDL tracer from plasma was marginally faster in EO vs. PO fed mice. Our results suggest that EO reduces plasma TG primarily through increased intravascular lipolysis of TG and VLDL clearance. Finally, EO may substitute for FO to reduce plasma TG concentrations, but not hepatic steatosis in this mouse model. PMID:23857172

  2. Echium oil reduces plasma triglycerides by increasing intravascular lipolysis in apoB100-only low density lipoprotein (LDL) receptor knockout mice.

    PubMed

    Forrest, Lolita M; Lough, Christopher M; Chung, Soonkyu; Boudyguina, Elena Y; Gebre, Abraham K; Smith, Thomas L; Colvin, Perry L; Parks, John S

    2013-07-12

    Echium oil (EO), which is enriched in SDA (18:4 n-3), reduces plasma triglyceride (TG) concentrations in humans and mice. We compared mechanisms by which EO and fish oil (FO) reduce plasma TG concentrations in mildly hypertriglyceridemic male apoB100-only LDLrKO mice. Mice were fed one of three atherogenic diets containing 0.2% cholesterol and palm oil (PO; 20%), EO (10% EO + 10% PO), or FO (10% FO + 10% PO). Livers from PO- and EO-fed mice had similar TG and cholesteryl ester (CE) content, which was significantly higher than in FO-fed mice. Plasma TG secretion was reduced in FO vs. EO-fed mice. Plasma very low density lipoprotein (VLDL) particle size was ordered: PO (63 ± 4 nm) > EO (55 ± 3 nm) > FO (40 ± 2 nm). Post-heparin lipolytic activity was similar among groups, but TG hydrolysis by purified lipoprotein lipase was significantly greater for EO and FO VLDL compared to PO VLDL. Removal of VLDL tracer from plasma was marginally faster in EO vs. PO fed mice. Our results suggest that EO reduces plasma TG primarily through increased intravascular lipolysis of TG and VLDL clearance. Finally, EO may substitute for FO to reduce plasma TG concentrations, but not hepatic steatosis in this mouse model.

  3. Increased serum soluble lectin-like oxidized low-density lipoprotein receptor-1 levels in patients with biopsy-proven nonalcoholic fatty liver disease

    PubMed Central

    Ozturk, Oguzhan; Colak, Yasar; Senates, Ebubekir; Yilmaz, Yusuf; Ulasoglu, Celal; Doganay, Levent; Ozkanli, Seyma; Oltulu, Yasemin Musteri; Coskunpinar, Ender; Tuncer, Ilyas

    2015-01-01

    AIM: To analyze the relationship between the serum lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) levels and clinical and histopathological features of biopsy-confirmed nonalcoholic fatty liver disease (NAFLD) patients. METHODS: Fifty-three consecutive, biopsy-proven NAFLD patients (31 males and 22 females, mean age 42.5 ± 9.6 years) and 26 age- and gender-matched, healthy controls (14 males and 12 females, mean age 39 ± 10.7 years) were included. The patients with NAFLD were consecutive patients who had been admitted to the hepatology outpatient clinic within the last year and had been diagnosed with NAFLD as the result of liver biopsy. The healthy controls were individuals who attended the outpatient clinic for routine health control and had no known chronic illnesses. The histological evaluation was conducted according to the NAFLD activity scoring system recommended by The National Institute of Diabetes and Digestive and Kidney Diseases Nonalcoholic Steatohepatitis Clinical Research Network. The serum LOX-1 levels were measured using an ELISA kit (Life Science Inc. USCN. Wuhan, Catalog No. E1859Hu) in both patients and healthy controls. A receiver operating characteristic (ROC) curve analysis was used to identify the optimal cutoff value of LOX-1 and thereby distinguish between patients with nonalcoholic steatohepatitis (NASH) and healthy controls. A P-value < 0.05 was considered statistically significant. RESULTS: NAFLD and healthy control groups were similar in terms of age and sex. NAFLD patients consisted of 8 patients with simple steatosis (15%), 27 with borderline NASH (51%) and 18 with definitive NASH (34%). Metabolic syndrome was found in 62.2% of the patients with NAFLD. The mean serum LOX-1 level in biopsy-proven NAFLD patients was 8.49 ± 6.43 ng/mL compared to 4.08 ± 4.32 ng/mL in healthy controls (P = 0.001). The LOX-1 levels were significantly different between controls, simple steatosis and NASH (borderline+definite) cases (4

  4. Up-regulation of hepatic low-density lipoprotein receptor-related protein 1: a possible novel mechanism of antiatherogenic activity of hydroxymethylglutaryl-coenzyme A reductase inhibitor Atorvastatin and hepatic LRP1 expression.

    PubMed

    Moon, Jae Hoon; Kang, Saet Byol; Park, Jong Suk; Lee, Byung Wan; Kang, Eun Seok; Ahn, Chul Woo; Lee, Hyun Chul; Cha, Bong Soo

    2011-07-01

    Low-density lipoprotein receptor-related protein 1 (LRP1) binds to apolipoprotein E and serves as a receptor for remnant lipoproteins in the liver, thus playing an important role in clearing these atherogenic particles. In this study, we investigated the effect of atorvastatin, a hydroxymethylglutaryl-coenzyme A reductase inhibitor, on hepatic LRP1 expression. We used HepG2 and Hep3B cells for in vitro study, and Otsuka Long-Evans Tokushima fatty and Sprague-Dawley rats for in vivo study. We used relatively high pharmacologic dose of atorvastatin in this study (in vitro, 0.5 μmol/L in culture media, for 48 hours; in vivo, 20 mg/[kg d], for 6 weeks). Atorvastatin increased LRP1 and low-density lipoprotein (LDL) receptor expression in HepG2 and Hep3B cells and induced hepatic LRP1 and LDL receptor expression in chow diet-fed Sprague-Dawley rats and high-fat diet-fed Otsuka Long-Evans Tokushima fatty rats. Atorvastatin decreased intracellular sterol level and increased the amount of the nuclear form of sterol response element-binding protein-2 (SREBP-2) in both HepG2 and Hep3B cells as well as in two animal models. Treatment of HepG2 cells with LDL increased intracellular sterol level and reduced LRP1, LDL receptor, and SREBP-2. When SREBP-2 in HepG2 cells was knocked down by small interfering RNA, the induction of LRP1 expression by atorvastatin did not take place. In conclusion, up-regulation of hepatic LRP1 might be a novel mechanism by which statin treatment decreases remnant lipoproteins. In addition, SREBP-2 acts as a mediator of atorvastatin-induced up-regulation of hepatic LRP1. Future studies using standard doses of atorvastatin in humans are needed to elucidate clinical relevance of these findings.

  5. Oxidized low-density lipoprotein induces hematopoietic stem cell senescence.

    PubMed

    Zhang, Xian-Ping; Zhang, Gui-Hai; Wang, Yu-Ying; Liu, Jun; Wei, Qiang; Xu, Chun-Yan; Wang, Jian-Wei; Wang, Ya-Ping

    2013-09-01

    We have investigated oxidized low-density lipoprotein (ox-LDL) induced senescence in hematopoietic stem cells (HCs). Mouse Sca-1+ HCs were separated and purified using the magnetic activated cell sorting technique. Ox-LDL induced significant senescence in HCs measured by SA-β-Gal staining, and reduced CFU-Mix colony-forming capacity, arresting cells at G0/G1 phase. In agreement with the cell cycle arrest, ox-LDL markedly reduced the expression of CDK4, cyclin D, and cyclin E. As possible contributing factors for cell senescence, ox-LDL also induced cellular oxidative stress and reduced telomerase activity.

  6. A mutation in the first ligand-binding repeat of the human very-low-density lipoprotein receptor results in high-affinity binding of the single V1 module to human rhinovirus 2.

    PubMed

    Nizet, Stephane; Wruss, Juergen; Landstetter, Nathalie; Snyers, Luc; Blaas, Dieter

    2005-12-01

    Minor group human rhinoviruses (HRVs) bind members of the low-density lipoprotein receptor family for cell entry. The ligand-binding domains of these membrane proteins are composed of various numbers of direct repeats of about 40 amino acids in length. Residues involved in binding of module 3 (V3) of the very-low-density lipoprotein receptor (VLDLR) to HRV2 have been identified by X-ray crystallography (N. Verdaguer, I. Fita, M. Reithmayer, R. Moser, and D. Blaas, Nat. Struct. Mol. Biol. 11:429-434, 2004). Sequence comparisons of the eight repeats of VLDLR with respect to the residues implicated in the interaction between V3 and HRV2 suggested that (in addition to V3) V1, V2, V5, and V6 also fulfill the requirements for interacting with the virus. Using a highly sensitive binding assay employing phage display, we demonstrate that single modules V2, V3, and V5 indeed bind HRV2. However, V1 does not. A single mutation from threonine 17 to proline converted the nonbinding wild-type form of V1 into a very strong binder. We interpret the dramatic increase in affinity by the generation of a hydrophobic patch between virus and receptor; in the presence of threonine, the contact area might be disturbed. This demonstrates that the interaction between virus and its natural receptors can be strongly enhanced by mutation.

  7. Low density lipoprotein and very low density lipoprotein are selectively bound by aggregated C-reactive protein.

    PubMed

    de Beer, F C; Soutar, A K; Baltz, M L; Trayner, I M; Feinstein, A; Pepys, M B

    1982-07-01

    C-reactive protein (CRP), the classical acute-phase protein, can bind phospholipids by virtue of its specific, calcium-dependent reactivity with phosphorylcholine residues. However, analysis of acute-phase serum by gel filtration and by density gradient ultracentrifugation showed that the CRP was in a free, uncomplexed form, despite the coexistent presence of the various classes of serum lipoproteins, all of which contain phospholipids. In contrast, when isolated CRP was aggregated by immobilization at a sufficient density on a solid phase and then exposed to normal human serum, it selectively bound low density lipoprotein (LDL) and traces of very low density lipoprotein. The reaction was calcium dependent and reversible by free phosphorylcholine but not by heparin. LDL isolated from normal plasma was also bound by aggregated CRP. CRP reacts in vitro with a wide variety of different ligands both of extrinsic and of autogenous origin, e.g., microbial products and damaged cell membranes, respectively. If CRP aggregated in vivo by complexing with these ligands than acquires the capacity to selectively bind LDL, the phenomenon may have significant implications for the function of CRP and for the metabolism, clearance, and deposition of LDL.

  8. 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.

  9. [Lipoprotein receptors. Old acquaintances and newcomers].

    PubMed

    Ducobu, J

    1997-02-01

    Lipoprotein receptors are plasma membrane proteins of high affinity which interact with circulating lipoprotein particles. The well characterized LDL receptor continues to be analysed and some new findings on its intracellular mechanisms of action have emerged. New lipoprotein receptors have recently been described: the chylomicron remnant receptor or LDL-related protein (LRP), the lipolysis stimulated receptor (LSR), the very low density lipoprotein receptor (VLDLR), the HDL receptor (HDLR) and the scavenger receptor (SR). The molecular details of the receptors will facilitate the development of new therapeutic means to improve receptor-mediated clearance of lipoproteins.

  10. A role for apolipoprotein E, apolipoprotein A-I, and low density lipoprotein receptors in cholesterol transport during regeneration and remyelination of the rat sciatic nerve.

    PubMed Central

    Boyles, J K; Zoellner, C D; Anderson, L J; Kosik, L M; Pitas, R E; Weisgraber, K H; Hui, D Y; Mahley, R W; Gebicke-Haerter, P J; Ignatius, M J

    1989-01-01

    Recent work has demonstrated that apo E secretion and accumulation increase in the regenerating peripheral nerve. The fact that apoE, in conjunction with apoA-I and LDL receptors, participates in a well-established lipid transfer system raised the possibility that apoE is also involved in lipid transport in the injured nerve. In the present study of the crushed rat sciatic nerve, a combination of techniques was used to trace the cellular associations of apoE, apoA-I, and the LDL receptor during nerve repair and to determine the distribution of lipid at each stage. After a crush injury, as axons died and Schwann cells reabsorbed myelin, resident and monocyte-derived macrophages produced large quantities of apoE distal to the injury site. As axons regenerated in the first week, their tips contained a high concentration of LDL receptors. After axon regeneration, apoE and apoA-I began to accumulate distal to the injury site and macrophages became increasingly cholesterol-loaded. As remyelination began in the second and third weeks after injury, Schwann cells exhausted their cholesterol stores, then displayed increased LDL receptors. Depletion of macrophage cholesterol stores followed over the next several weeks. During this stage of regeneration, apoE and apoA-I were present in the extracellular matrix as components of cholesterol-rich lipoproteins. Our results demonstrate that the regenerating peripheral nerve possesses the components of a cholesterol transfer mechanism, and the sequence of events suggests that this mechanism supplies the cholesterol required for rapid membrane biogenesis during axon regeneration and remyelination. Images PMID:2493483

  11. Quantitative dissection of the binding contributions of ligand lysines of the receptor-associated protein (RAP) to the low density lipoprotein receptor-related protein (LRP1).

    PubMed

    Dolmer, Klavs; Campos, Andres; Gettins, Peter G W

    2013-08-16

    Although lysines are known to be critical for ligand binding to LDL receptor family receptors, relatively small reductions in affinity have been found when such lysines have been mutated. To resolve this paradox, we have examined the specific binding contributions of four lysines, Lys-253, Lys-256, Lys-270, and Lys-289, in the third domain (D3) of receptor-associated protein (RAP), by eliminating all other lysine residues. Using D3 variants containing lysine subsets, we examined binding to the high affinity fragment CR56 from LRP1. With this simplification, we found that elimination of the lysine pairs Lys-253/Lys-256 and Lys-270/Lys-289 resulted in increases in Kd of 1240- and 100,000-fold, respectively. Each pair contributed additively to overall affinity, with 61% from Lys-270/Lys-289 and 39% from Lys-253/Lys-256. Furthermore, the Lys-270/Lys-289 pair alone could bind different single CR domains with similar affinity. Within the pairs, binding contributions of Lys-270 ≫ Lys-256 > Lys-253 ∼ Lys-289 were deduced. Importantly, however, Lys-289 could significantly compensate for the loss of Lys-270, thus explaining how previous studies have underestimated the importance of Lys-270. Calorimetry showed that favorable enthalpy, from Lys-256 and Lys-270, overwhelmingly drives binding, offset by unfavorable entropy. Our findings support a mode of ligand binding in which a proximal pair of lysines engages the negatively charged pocket of a CR domain, with two such pairs of interactions (requiring two CR domains), appropriately separated, being alone sufficient to provide the low nanomolar affinity found for most protein ligands of LDL receptor family members.

  12. Synthetic Nano-Low Density Lipoprotein as Targeted Drug DeliveryVehicle for Glioblastoma Multiforme

    SciTech Connect

    Nikanjam, Mina; Blakely, Eleanor A.; Bjornstad, Kathleen A.; Shu,Xiao; Budinger, Thomas F.; Forte, Trudy M.

    2006-06-14

    This paper discribes a synthetic low density lipoprotein(LDL) made by complexing a 29 amino acid that consists of a lipid bindingdomain and the LDL receptor binding domain with a lipid microemulsion.The nano-LDL particles were intermdiate in size between LDL and HDL andbound to LDL receptors on GBM brain tumor cells. Synthetic nano-LDLuptake by GBM cells was LDL receptor specific and dependent on cellreceptor number. It is suggested that these synthetic particles can serveas a delivery vehicle for hydophobic anti-tumor drugs by targeting theLDL receptor.

  13. Functionalizing low-density lipoprotein nanoparticles for in vivo near-infrared optical imaging of cancer

    NASA Astrophysics Data System (ADS)

    Corbin, Ian R.; Chen, Juan; Li, Hui; Cao, Weiguo; Zheng, Gang

    2007-07-01

    Low density lipoproteins (LDL) have long been recognized as a potential delivery system for exogenous agents. Imaging agents or drugs can be attached to LDL through surface loading, protein loading or core loading methods. The LDL delivery system has received considerable attention particularly among cancer biologists as it was observed that numerous cancers over-express the low density lipoprotein receptor (LDLR). In this paper we investigate the utility of LDL to transport optical imaging contrast agents for caner detection. The method of loading fluorophores into the core of LDL is attractive as it behaves like an activatable contrast agent. Surface and protein labeled methods also prove to be effective strategies for tracing LDL nanoparticle activity. The strengths and limitations of the LDL carrier system are discussed and novel approaches for imaging cancer with LDL nanoparticles are highlighted.

  14. Cholesterol transfer from normal and atherogenic low density lipoproteins to Mycoplasma membranes

    SciTech Connect

    Mitschelen, J.J.; St. Clair, R.W.; Hester, S.H.

    1981-01-01

    The purpose of this study was to determine whether the free cholesterol of hypercholesterolemic low density lipoprotein from cholesterol-fed nonhuman primates has a greater potential for surface transfer to cell membranes than does the free cholesterol of normal low density lipoprotein. The low density lipoproteins were isolated from normal and hypercholesterolemic rhesus and cynomolgus monkeys, incubated with membranes from Acholeplasma laidlawii, a mycoplasma species devoid of cholesterol in its membranes, and the mass transfer of free cholesterol determined by measuring membrane cholesterol content. Since these membranes neither synthesize nor esterify cholesterol, nor degrade the protein or cholesterol ester moieties of low density lipoprotein, they are an ideal model with which to study differences in the cholesterol transfer potential of low density lipoprotein independent of the uptake of the intact low density lipoprotein particle. These studies indicate that, even though there are marked differences in the cholesterol composition of normal and hypercholesterolemic low density lipoproteins, this does not result in a greater chemical potential for surface transfer of free cholesterol. Consequently, if a difference in the surface transfer of free cholesterol is responsible for the enhanced ability of hypercholesterolemic low density lipoprotein to promote cellular cholesterol accumulation and, perhaps, also atherosclerosis, it must be the result of differences in the interaction to the hypercholesterolemic low density lipoprotein with the more complicated mammalian cell membranes, rather than differences in the chemical potential for cholesterol transfer.

  15. Native low density lipoprotein promotes lipid raft formation in macrophages

    PubMed Central

    SONG, JIAN; PING, LING-YAN; DUONG, DUC M.; GAO, XIAO-YAN; HE, CHUN-YAN; WEI, LEI; WU, JUN-ZHU

    2016-01-01

    Oxidized low-density lipoprotein (LDL) has an important role in atherogenesis; however, the mechanisms underlying cell-mediated LDL oxidation remain to be elucidated. The present study investigated whether native-LDL induced lipid raft formation, in order to gain further insight into LDL oxidation. Confocal microscopic analysis revealed that lipid rafts were aggregated or clustered in the membrane, which were colocalized with myeloperoxidase (MPO) upon native LDL stimulation; however, in the presence of methyl-β-cyclodextrin (MβCD), LDL-stimulated aggregation, translocation, and colocalization of lipid rafts components was abolished.. In addition, lipid raft disruptors MβCD and filipin decreased malondialdehyde expression levels. Density gradient centrifugation coupled to label-free quantitative proteomic analysis identified 1,449 individual proteins, of which 203 were significantly upregulated following native-LDL stimulation. Functional classification of the proteins identified in the lipid rafts revealed that the expression levels of translocation proteins were upregulated. In conclusion, the results of the present study indicated that native-LDL induced lipid raft clustering in macrophages, and the expression levels of several proteins were altered in the stimulated macrophages, which provided novel insights into the mechanism underlying LDL oxidation. PMID:26781977

  16. Tiliroside and gnaphaliin inhibit human low density lipoprotein oxidation.

    PubMed

    Schinella, Guillermo R; Tournier, Horacio A; Máñez, Salvador; de Buschiazzo, Perla M; Del Carmen Recio, María; Ríos, José Luis

    2007-01-01

    Two flavonoids, gnaphaliin and tiliroside, isolated from Helichrysum italicum, were studied in vitro for their capacity to inhibit Cu(2+)-induced human low density lipoprotein (LDL) and diluted plasma oxidation. LDL oxidation was monitored by conjugated diene, thiobarbituric acid-reactive substances (TBARS) formation and electrophoretic mobility on agarose gel. Gnaphaliin and tiliroside increased the lag-phase for diene conjugate production in a dose-dependent manner. The reduction of TBARS production confirmed the antioxidant activity of gnaphaliin and tiliroside with 50% inhibitory concentration (IC(50)) values of 8.0+/-3.9 microM and 7.0+/-2.6 microM respectively. Furthermore, the flavonoids negated the Cu(2+)-induced increase in electrophoretic mobility of LDL. Antioxidant activity of gnaphaliin and tiliroside was significantly different when diluted plasma was oxidised by adding 1 mM CuSO(4). Although both flavonoids again reduced the TBARS production, tiliroside showed higher activity than gnaphaliin (IC(50)=10.6+/-2.5 microM vs. IC(50)>50 microM). In conclusion, tiliroside and gnaphaliin are antioxidants against in vitro Cu(2+)-induced LDL oxidation in the same order of magnitude compared to that of the reference drug, probucol.

  17. Receptor-associated protein (RAP) has two high-affinity binding sites for the low-density lipoprotein receptor-related protein (LRP): consequences for the chaperone functions of RAP.

    PubMed

    Jensen, Jan K; Dolmer, Klavs; Schar, Christine; Gettins, Peter G W

    2009-06-26

    RAP (receptor-associated protein) is a three domain 38 kDa ER (endoplasmic reticulum)-resident protein that is a chaperone for the LRP (low-density lipoprotein receptor-related protein). Whereas RAP is known to compete for binding of all known LRP ligands, neither the location, the number of binding sites on LRP, nor the domains of RAP involved in binding is known with certainty. We have systematically examined the binding of each of the three RAP domains (D1, D2 and D3) to tandem and triple CRs (complement-like repeats) that span the principal ligand-binding region, cluster II, of LRP. We found that D3 binds with low nanomolar affinity to all (CR)2 species examined. Addition of a third CR domain increases the affinity for D3 slightly. A pH change from 7.4 to 5.5 gave only a 6-fold increase in Kd for D3 at 37 degrees C, whereas temperature change from 22 degrees C to 37 degrees C has a similar small effect on affinity, raising questions about the recently proposed D3-destabilization mechanism of RAP release from LRP. Surprisingly, and in contrast to literature suggestions, D1 and D2 also bind to most (CR)2 and (CR)3 constructs with nanomolar affinity. Although this suggested that there might be three high-affinity binding sites in RAP for LRP, studies with intact RAP showed that only two binding sites are available in the intact chaperone. These findings suggest a new model for RAP to function as a folding chaperone and also for the involvement of YWTD domains in RAP release from LRP in the Golgi.

  18. 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

  19. Green tea catechins prevent low-density lipoprotein oxidation via their accumulation in low-density lipoprotein particles in humans.

    PubMed

    Suzuki-Sugihara, Norie; Kishimoto, Yoshimi; Saita, Emi; Taguchi, Chie; Kobayashi, Makoto; Ichitani, Masaki; Ukawa, Yuuichi; Sagesaka, Yuko M; Suzuki, Emiko; Kondo, Kazuo

    2016-01-01

    Green tea is rich in polyphenols, including catechins which have antioxidant activities and are considered to have beneficial effects on cardiovascular health. In the present study, we investigated the effects of green tea catechins on low-density lipoprotein (LDL) oxidation in vitro and in human studies to test the hypothesis that catechins are incorporated into LDL particles and exert antioxidant properties. In a randomized, placebo-controlled, double-blind, crossover trial, 19 healthy men ingested green tea extract (GTE) in the form of capsules at a dose of 1 g total catechin, of which most (>99%) was the gallated type. At 1 hour after ingestion, marked increases of the plasma concentrations of (-)-epigallocatechin gallate and (-)-epicatechin gallate were observed. Accordingly, the plasma total antioxidant capacity was increased, and the LDL oxidizability was significantly reduced by the ingestion of GTE. We found that gallated catechins were incorporated into LDL particles in nonconjugated forms after the incubation of GTE with plasma in vitro. Moreover, the catechin-incorporated LDL was highly resistant to radical-induced oxidation in vitro. An additional human study with 5 healthy women confirmed that GTE intake sufficiently increased the concentration of gallated catechins, mainly in nonconjugated forms in LDL particles, and reduced the oxidizability of LDL. In conclusion, green tea catechins are rapidly incorporated into LDL particles and play a role in reducing LDL oxidation in humans, which suggests that taking green tea catechins is effective in reducing atherosclerosis risk associated with oxidative stress.

  20. Cyclic tensile stretch load and oxidized low density lipoprotein synergistically induce lectin-like oxidized ldl receptor-1 in cultured bovine chondrocytes, resulting in decreased cell viability and proteoglycan synthesis.

    PubMed

    Akagi, Masao; Nishimura, Shunji; Yoshida, Kohji; Kakinuma, Takumi; Sawamura, Tatsuya; Munakata, Hiroshi; Hamanishi, Chiaki

    2006-08-01

    Mechanical stimulation is known to be an essential factor in the regulation of cartilage metabolism. We tested the hypothesis that expression of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) can be modulated by cyclic tensile stretch load in chondrocytes. Cyclic loading of repeated stretch stress at 10 cycles per minute with 10 kPa of stress for 6 h induced expression of LOX-1 to 2.6 times control in cultured bovine articular chondrocytes, equivalent to the addition of 10 microg/mL oxidized low density lipoprotein (ox-LDL) (2.4 times control). Application of the cyclic load to the chondrocytes along with 10 microg/mL ox-LDL resulted in synergistically increased LOX-1 expression to 6.3 times control. Individual application of cyclic loading and 10 microg/mL ox-LDL significantly suppressed chondrocytes viability (84.6% +/- 3.4% and 80.9% +/- 3.2% of control at 24 h, respectively; n = 3; p < 0.05) and proteoglycan synthesis [81.0% +/- 7.1% and 85.7% +/- 5.2% of control at 24 h, respectively; p < 0.05 when compared with 94.6% +/- 4.6% for native-LDL (n = 3)]. Cyclic loading and 10 microg/mL ox-LDL synergistically affected cell viability and proteoglycan synthesis, which were significantly suppressed to 45.6% +/- 4.9% and 48.7% +/- 6.7% of control at 24 h, respectively (n = 3; p < 0.01 when compared with individual application of cyclic loading or 10 microg/mL ox-LDL). In this study, we demonstrated synergistic effects of cyclic tensile stretch load and ox-LDL on cell viability and proteoglycan synthesis in chondrocytes, which may be mediated through enhanced expression of LOX-1 and which has important implications in the progression of cartilage degeneration in osteoarthritis.

  1. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the low-density lipoprotein in serum and other body fluids. Measurement of low-density lipoprotein in serum may aid in the diagnosis of disorders of lipid (fat) metabolism and help to identify young persons at risk from cardiovascular diseases. (b) Classification. Class II (performance standards)....

  2. Six new loci associated with blood low-density lipoprotein cholesterol, high-density lipoprotein cholesterol or triglycerides in humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol are risk factors for cardiovascular disease and blood triglycerides reflect key metabolic processes including sensitivity to insulin. Blood lipoprotein and lipid concentrations are heritable. To date, the identification o...

  3. Specificity of binding of the low density lipoprotein receptor-related protein to different conformational states of the clade E serpins plasminogen activator inhibitor-1 and proteinase nexin-1.

    PubMed

    Jensen, Jan K; Dolmer, Klavs; Gettins, Peter G W

    2009-07-03

    The low density lipoprotein receptor-related protein (LRP) is the principal clearance receptor for serpins and serpin-proteinase complexes. The ligand binding regions of LRP consist of clusters of cysteine-rich approximately 40-residue complement-like repeats (CR), with cluster II being the principal ligand-binding region. To better understand the specificity of binding at different sites within the cluster and the ability of LRP to discriminate in vivo between uncomplexed and proteinase-complexed serpins, we have systematically examined the affinities of plasminogen activator inhibitor-1 (PAI-1) and proteinase nexin-1 (PN-1) in their native, cleaved, and proteinase-complexed states to (CR)(2) and (CR)(3) fragments of LRP cluster II. A consistent blue shift of the CR domain tryptophan fluorescence suggested a common mode of serpin binding, involving lysines on the serpin engaging the acidic region around the calcium binding site of the CR domain. High affinity binding of non-proteinase-complexed PAI-1 and PN-1 occurred to all fragments containing three CR domains (3-59 nm) and most that contain only two CR domains, although binding energies to different (CR)(3) fragments differed by up to 18% for PAI-1 and 9% for PN-1. No detectable difference in affinity was seen between native and cleaved serpin. However, the presence of proteinase in complex with the serpin enhanced affinity modestly and presumably nonspecifically. This may be sufficient to give preferential binding of such complexes in vivo at the relevant physiological concentrations.

  4. Lectin-like oxidized low-density lipoprotein receptor-1 facilitates metastasis of gastric cancer through driving epithelial-mesenchymal transition and PI3K/Akt/GSK3β activation

    PubMed Central

    Li, Can; Zhang, Jie; Wu, Hao; Li, Lili; Yang, Caiting; Song, Shushu; Peng, Peike; Shao, Miaomiao; Zhang, Mingming; Zhao, Junjie; Zhao, Ran; Wu, Weicheng; Ruan, Yuanyuan; Wang, Lan; Gu, Jianxin

    2017-01-01

    Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a pattern recognition receptor that plays a critical role in vascular diseases and host immune response. Recently, our research discovered that LOX-1 could facilitate the uptake of dying cells and cross-presentation of cellular antigen via binding with heat shock proteins, which have a close relationship with gastric neoplasia. Therefore, we speculated that LOX-1 may serve as an oncogene in gastric cancer (GC) development and progression. In this study, through immunohistochemistry staining assay and cancer-related databases, we found that LOX-1 expression was up-regulated in GC tissues and correlated with a poor prognosis in GC patients. The expression of LOX-1 was an independent prognostic factor for OS in GC patients, and the incorporation of LOX-1 with TNM stage is more accurate for predicting prognosis. Additionally, in vitro study by transwell assay and western blot analysis confirmed that LOX-1 could promote the migration and invasion of GC cells by driving epithelial-mesenchymal transition and PI3K/Akt/GSK3β activation. Taken together, we first explored the expression profiles, clinical significance and biological function of LOX-1 in GC, and these data suggest that LOX-1 may represent a promising prognostic biomarker for GC and offer a novel molecular target for GC therapies. PMID:28345638

  5. High transcript level of fatty acid-binding protein 11 but not of very low-density lipoprotein receptor is correlated to ovarian follicle atresia in a teleost fish (Solea senegalensis).

    PubMed

    Agulleiro, Maria J; André, Michèle; Morais, Sofia; Cerdà, Joan; Babin, Patrick J

    2007-09-01

    Transcripts encoding a fatty acid-binding protein (FABP), Fabp11, and two isoforms of very low-density lipoprotein receptor (Vldlr; vitellogenin receptor) were characterized from the ovary of Senegalese sole (Solea senegalensis). Phylogenetic analyses of vertebrate FABPs demonstrated that Senegalese sole Fabp11, as zebrafish (Danio rerio) homologous sequences, is part of a newly defined teleost fish FABP subfamily that is a sister clade of tetrapod FABP4/FABP5/FABP8/FABP9. RT-PCR revealed high levels of vldlr transcript splicing variants in the ovaries and, to a lesser extent, in somatic tissues, whereas fabp11 was highly expressed in the ovaries, liver, and adipose tissue. In situ hybridization analysis showed vldlr and fabp11 mRNAs in previtellogenic oocytes, whereas no hybridization signals were detected in the larger vitellogenic oocytes. Transcript expression of fabp11 was strongly upregulated in somatic cells surrounding atretic follicles. Real-time quantitative RT-PCR demonstrated that ovarian transcript levels of vldlr and fabp11 had a significant positive correlation with the percentage of follicles in previtellogenesis and atresia, respectively. These results suggest that the expression level of vldlr transcripts may be used as a precocious functional marker to quantify the number of oocytes recruited for vitellogenesis and that fabp11 mRNA may be a very useful molecular marker for determining cellular events and environmental factors that regulate follicular atresia in fish.

  6. Furin-cleaved proprotein convertase subtilisin/kexin type 9 (PCSK9) is active and modulates low density lipoprotein receptor and serum cholesterol levels.

    PubMed

    Lipari, Michael T; Li, Wei; Moran, Paul; Kong-Beltran, Monica; Sai, Tao; Lai, Joyce; Lin, S Jack; Kolumam, Ganesh; Zavala-Solorio, Jose; Izrael-Tomasevic, Anita; Arnott, David; Wang, Jianyong; Peterson, Andrew S; Kirchhofer, Daniel

    2012-12-21

    Proprotein convertase subtilisin/kexin 9 (PCSK9) regulates plasma LDL cholesterol levels by regulating the degradation of LDL receptors. Another proprotein convertase, furin, cleaves PCSK9 at Arg(218)-Gln(219) in the surface-exposed "218 loop." This cleaved form circulates in blood along with the intact form, albeit at lower concentrations. To gain a better understanding of how cleavage affects PCSK9 function, we produced recombinant furin-cleaved PCSK9 using antibody Ab-3D5, which binds the intact but not the cleaved 218 loop. Using Ab-3D5, we also produced highly purified hepsin-cleaved PCSK9. Hepsin cleaves PCSK9 at Arg(218)-Gln(219) more efficiently than furin but also cleaves at Arg(215)-Phe(216). Further analysis by size exclusion chromatography and mass spectrometry indicated that furin and hepsin produced an internal cleavage in the 218 loop without the loss of the N-terminal segment (Ser(153)-Arg(218)), which remained attached to the catalytic domain. Both furin- and hepsin-cleaved PCSK9 bound to LDL receptor with only 2-fold reduced affinity compared with intact PCSK9. Moreover, they reduced LDL receptor levels in HepG2 cells and in mouse liver with only moderately lower activity than intact PCSK9, consistent with the binding data. Single injection into mice of furin-cleaved PCSK9 resulted in significantly increased serum cholesterol levels, approaching the increase by intact PCSK9. These findings indicate that circulating furin-cleaved PCSK9 is able to regulate LDL receptor and serum cholesterol levels, although somewhat less efficiently than intact PCSK9. Therapeutic anti-PCSK9 approaches that neutralize both forms should be the most effective in preserving LDL receptors and in lowering plasma LDL cholesterol.

  7. Antibodies against oxidized low density lipoproteins in pregnant women.

    PubMed

    Fialová, L; Mikulíková, L; Malbohan, I; Benesová, O; Stípek, S; Zima, T; Zwinger, A

    2002-01-01

    Oxidized low density lipoproteins (oxLDL) formed in vivo induce a humoral immune response. Oxidative modification of LDL renders it immunogenic and a heterogeneous population of specific anti-oxLDL antibodies is produced. These antibodies could represent a biological marker of oxidative stress and serve as markers of atherosclerosis. Autoantibodies against oxLDL (oLAb) have been detected in human subjects practically of every age. oLAb also appear in the blood of pregnant women. Some studies have shown that the levels of antibodies to oxLDL were elevated in women with established preeclampsia. The present study was aimed to estimate the oLAb IgG levels in the first and second trimester of pregnancy. Furthermore, we estimated the correlation between maternal serum (MS) levels of oLAb and alpha-1-fetoprotein (MS AFP), human chorionic gonadotrophin (MS HCG) and trophoblast-specific-beta-1-glycoprotein (MS SP1), because these proteins are determined as a part of prenatal biochemical screening for fetal congenital abnormalities. Our study deals with the oLAb changes in women with pregnancy-induced hypertension. We also investigated the correlation between oLAb IgG and anticardiolipin antibodies IgG (ACA) in the serum of pregnant women. We examined 40 pregnant women attending Institute for Mother and Child Care for their antenatal care as outpatients. Routine blood samplings between the 9-13th week of pregnancy and 16-18th week of pregnancy were performed as a part of biochemical prenatal screening for fetal congenital abnormalities (Group 1). Their mean age was 27 +/- 4.1 years. Furthermore, we examined 26 women in the second or third trimester with pregnancy-induced hypertension (Group 2). Group 2 was compared with 49 pregnant women in the second or third trimester who were normotensive (Group 3). We used commercial standardized ELISA kits for determination of oLAb IgG, ACA IgG, MS AFP and MS HCG, MS SP1 was analyzed by single radial immunodiffusion. We did not find

  8. High sensitivity of the single-strand conformation polymorphism method for detecting sequence variations in the low-density lipoprotein receptor gene validated by DNA sequencing.

    PubMed

    Jensen, H K; Jensen, L G; Hansen, P S; Faergeman, O; Gregersen, N

    1996-08-01

    We designed oligonucleotide primer pairs to amplify the promoter region, the translated exon sequences, and the flanking intron sequences of all 18 exons of the LDL receptor gene to compare the ability of the PCR single-strand conformation polymorphism (PCR-SSCP) method with semiautomated solid-phase genomic DNA sequencing to detect sequence variations. In 20 apparently unrelated Danish patients with a clinical diagnosis of heterozygous familial hypercholesterolemia (FH), we identified 13 different mutations in the LDL receptor gene: two silent (C331C, N494 N); five missense (W66G, E119K, T383P, W556S, T7051); one nonsense (W23X); three splice-site (313 + 1G-->A, 1061-8T-->C, 1846-1G-->A); and two frameshift (335del10, 1650delG) mutations. Four of these mutations, N494 N, T383P, 1061-8T-->C, and W556S, have not been reported earlier. The pathogenicity of the T383P, 1061-8T-->C, and W556S mutations remains to be established by in vitro mutagenesis and transfection studies. One patient had three mutations (335del10, 1061-8T-->C, and T705I) on the same allele. Further, nine well-known polymorphisms were detectable with this methodological setup. Direct DNA sequencing of the PCR products used for the SSCP analysis did not reveal any sequence variations not detected by the PCR-SSCP method. In two patients we did not detect any mutation by either method. We conclude that the PCR-SSCP analysis, performed as described here, is as sensitive and efficient as DNA sequencing in the ability to identify the sequence variations in the LDL receptor gene of the patients with heterozygous FH of this study.

  9. The Liver Clock Controls Cholesterol Homeostasis through Trib1 Protein-mediated Regulation of PCSK9/Low Density Lipoprotein Receptor (LDLR) Axis.

    PubMed

    Ma, Di; Liu, Tongyu; Chang, Lin; Rui, Crystal; Xiao, Yuanyuan; Li, Siming; Hogenesch, John B; Chen, Y Eugene; Lin, Jiandie D

    2015-12-25

    Disruption of the body clock has been recognized as a risk factor for cardiovascular disease. How the circadian pacemaker interacts with the genetic factors associated with plasma lipid traits remains poorly understood. Recent genome-wide association studies have identified an expanding list of genetic variants that influence plasma cholesterol and triglyceride levels. Here we analyzed circadian regulation of lipid-associated candidate genes in the liver and identified two distinct groups exhibiting rhythmic and non-rhythmic patterns of expression during light-dark cycles. Liver-specific inactivation of Bmal1 led to elevated plasma LDL/VLDL cholesterol levels as a consequence of the disruption of the PCSK9/LDL receptor regulatory axis. Ablation of the liver clock perturbed diurnal regulation of lipid-associated genes in the liver and markedly reduced the expression of the non-rhythmically expressed gene Trib1. Adenovirus-mediated rescue of Trib1 expression lowered plasma PCSK9 levels, increased LDL receptor protein expression, and restored plasma cholesterol homeostasis in mice lacking a functional liver clock. These results illustrate an unexpected mechanism through which the biological clock regulates cholesterol homeostasis through its regulation of non-rhythmic genes in the liver.

  10. Salvianolic acid B inhibits macrophage uptake of modified low density lipoprotein (mLDL) in a scavenger receptor CD36-dependent manner

    PubMed Central

    Bao, Yi; Wang, Li; Xu, Yanni; Yang, Yuan; Wang, Lifei; Si, Shuyi; Cho, Sunghee; Hong, Bin

    2012-01-01

    CD36, a class B scavenger receptor, has been implicated in the pathogenesis of a host of vascular inflammatory diseases. Through a high-throughput screening (HTS) assay for CD36 antagonist, we previously identified salvianolic acid B (SAB), a hydrophilic component derived from the herb Danshen, as a potential candidate. Danshen, the dried roots of Salvia miltiorrhiza, has been widely used in China for the prevention and treatment of atherosclerosis-related disorders. Previous studies showed that SAB acted as an anti-oxidant by preventing lipid peroxidation and oxidized LDL (oxLDL) formation. The present study was to investigate the specificity and efficacy of SAB in the inhibition of CD36-mediated lipid uptake. SAB reduced modified LDL (mLDL) uptake in a dose-dependent manner in phorbol-12-myristate-13-acetate (PMA)-stimulated THP-1 and RAW 264.7 cells. In the CD36 silenced THP-1 cells, SAB had no effect in reducing mLDL uptake, whereas its over-expression in CHO cells reinstates the effect, indicating a specific involvement of SAB in antagonizing the CD36's function. Surface plasmon resonance (SPR) analysis revealed a direct binding of SAB to CD36 with a high affinity (KD =3.74 μM), confirming physical interactions of SAB with the receptor. Additionally, SAB reduced oxLDL-induced CD36 gene expression in the cultured cell lines and primary macrophages. In ApoE KO mice fed a high fat diet, SAB reduced CD36 gene expression and lipid uptake in macrophages, showing its ability to antagonize CD36 pathways in vivo. These results demonstrate that SAB is an effective CD36 antagonist and suggest SAB as a potential anti-atherosclerotic agent. PMID:22658257

  11. Targeting PCSK9 as a promising new mechanism for lowering low-density lipoprotein cholesterol.

    PubMed

    Della Badia, Laura A; Elshourbagy, Nabil A; Mousa, Shaker A

    2016-08-01

    Statins and other lipid-lowering drugs have dominated the market for many years for achievement of recommended levels of low-density lipoprotein cholesterol (LDL-C). However, a substantial number of high-risk patients are unable to achieve the LDL-C goal. Proprotein convertase subtilisin/kexin 9 (PCSK9) has recently emerged as a new, promising key therapeutic target for hypercholesterolemia. PCSK9 is a protease involved in chaperoning the low-density lipoprotein receptor to the process of degradation. PCSK9 inhibitors and statins effectively lower LDL-C. The PCSK9 inhibitors decrease the degradation of the LDL receptors, whereas statins mainly interfere with the synthetic machinery of cholesterol by inhibiting the key rate limiting enzyme, the HMG CoA reductase. PCSK9 inhibitors are currently being developed as monoclonal antibodies for their primary use in lowering LDL-C. They may be especially useful for patients with homozygous familial hypercholesterolemia, who at present receive minimal benefit from traditional statin therapy. The monoclonal antibody PCSK9 inhibitors, recently granted FDA approval, show the most promising safety and efficacy profile compared to other, newer LDL-C lowering therapies. This review will primarily focus on the safety and efficacy of monoclonal antibody PCSK9 inhibitors in comparison to statins. The review will also address new, alternative PCSK9 targeting drug classes such as small molecules, gene silencing agents, apolipoprotein B antisense oligonucleotides, and microsomal triglyceride transfer protein inhibitors.

  12. Receptors for oxidized low-density lipoprotein on elicited mouse peritoneal macrophages can recognize both the modified lipid moieties and the modified protein moieties: Implications with respect to macrophage recognition of apoptotic cells

    PubMed Central

    Bird, David A.; Gillotte, Kristin L.; Hörkkö, Sohvi; Friedman, Peter; Dennis, Edward A.; Witztum, Joseph L.; Steinberg, Daniel

    1999-01-01

    It has been shown previously that the binding of oxidized low-density lipoprotein (OxLDL) to resident mouse peritoneal macrophages can be inhibited (up to 70%) by the apoprotein B (apoB) isolated from OxLDL, suggesting that macrophage recognition of OxLDL is primarily dependent on its modified protein moiety. However, recent experiments have demonstrated that the lipids isolated from OxLDL and reconstituted into a microemulsion can also strongly inhibit uptake of OxLDL (up to 80%). The present studies show that lipid microemulsions prepared from OxLDL bind to thioglycollate-elicited macrophages at 4°C in a saturable fashion and inhibit the binding of intact OxLDL and also of the apoB from OxLDL. Reciprocally, the binding of the OxLDL-lipid microemulsions was strongly inhibited by intact OxLDL. A conjugate of synthetic 1-palmitoyl 2(5-oxovaleroyl) phosphatidylcholine (an oxidation product of 1-palmitoyl 2-arachidonoyl phosphatidylcholine) with serum albumin, shown previously to inhibit macrophage binding of intact OxLDL, also inhibited the binding of both the apoprotein and the lipid microemulsions prepared from OxLDL. Finally, a monoclonal antibody against oxidized phospholipids, one that inhibits binding of intact OxLDL to macrophages, also inhibited the binding of both the resolubilized apoB and the lipid microemulsions prepared from OxLDL. These studies support the conclusions that: (i) at least some of the macrophage receptors for oxidized LDL can recognize both the lipid and the protein moieties; and (ii) oxidized phospholipids, in the lipid phase of the lipoprotein and/or covalently linked to the apoB of OxLDL, likely play a role in that recognition. PMID:10339590

  13. Assembly and secretion of hepatic very-low-density lipoprotein.

    PubMed Central

    Gibbons, G F

    1990-01-01

    In contrast to water-soluble fuels such as glucose or ketone bodies, the use of lipids as an energy source for tissues has required the development of complex structures for their transport through the aqueous plasma. In the case of endogenously synthesized triacylglycerol this is achieved by the assembly and secretion of hepatic VLDL which provides the necessary stability in an aqueous medium. An essential component of this assembly process is apo B. Dietary changes which require an increase in hepatic VLDL secretion appear to be accompanied by increases in the availability of functional apo B. Interesting questions relate to: (a) the intracellular site(s) of triacylglycerol association with apo B, and (b) the mechanism(s) by which the availability of functional apo B at this site responds to metabolic and hormonal signals which reflect dietary status and, thus, the need to secrete triacylglycerol. As regards the latter, although in some cases changes in apo B synthesis occur in response to VLDL secretion hepatic apo B mRNA levels appear to be quite stable in vitro. Intracellular switching of apo B between the secretory and degradative pathways may be important in controlling VLDL assembly and post-translational modifications of the apoprotein may also play a role by influencing its ability to bind to triacylglycerol. Transport is not the only problem associated with the utilization of a concentrated energy source such as triacylglycerol and the complex problems of waste product disposal and recycling have to be dealt with. In the case of triacylglycerol, potentially toxic waste products include atherogenic remnants and LDL. The overall problem, then, in the long-term, involves the development of a 'safe' means of utilizing triacylglycerol and this requirement accounts for much of the complexity of plasma lipoprotein metabolism. In this area, the rat could teach the human a few tricks. One of these appears to be the utilization of hepatic apo B48 rather than apo B

  14. Plasma Membrane Tetraspanin CD81 Complexes with Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) and Low Density Lipoprotein Receptor (LDLR), and Its Levels Are Reduced by PCSK9.

    PubMed

    Le, Quoc-Tuan; Blanchet, Matthieu; Seidah, Nabil G; Labonté, Patrick

    2015-09-18

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) is an important factor in plasma cholesterol regulation through modulation of low density lipoprotein receptor (LDLR) levels. Naturally occurring mutations can lead to hyper- or hypocholesterolemia in human. Recently, we reported that PCSK9 was also able to modulate CD81 in Huh7 cells. In the present study, several gain-of-function and loss-of-function mutants as well as engineered mutants of PCSK9 were compared for their ability to modulate the cell surface expression of LDLR and CD81. Although PCSK9 gain-of-function D374Y enhanced the degradation both receptors, D374H and D129N seemed to only reduce LDLR levels. In contrast, mutations in the C-terminal hinge-cysteine-histidine-rich domain segment primarily affected the PCSK9-induced CD81 degradation. Furthermore, when C-terminally fused to an ACE2 transmembrane anchor, the secretory N-terminal catalytic or hinge-cysteine-histidine-rich domain domains of PCSK9 were able to reduce CD81 and LDLR levels. These data confirm that PCSK9 reduces CD81 levels via an intracellular pathway as reported for LDLR. Using immunocytochemistry, a proximity ligation assay, and co-immunoprecipitation, we found that the cell surface level of PCSK9 was enhanced upon overexpression of CD81 and that both PCSK9 and LDLR interact with this tetraspanin protein. Interestingly, using CHO-A7 cells lacking LDLR expression, we revealed that LDLR was not required for the degradation of CD81 by PCSK9, but its presence strengthened the PCSK9 effect.

  15. Dietary fish oil stimulates hepatic low density lipoprotein transport in the rat.

    PubMed Central

    Ventura, M A; Woollett, L A; Spady, D K

    1989-01-01

    These studies were undertaken to examine the effect of fish oil, safflower oil, and hydrogenated coconut oil on the major processes that determine the concentration of low density lipoprotein (LDL) in plasma, i.e., the rate of LDL production and the rates of receptor-dependent and receptor-independent LDL uptake in the various organs of the body. When fed at the 20% level, fish oil reduced plasma LDL-cholesterol levels by 38% primarily by increasing LDL receptor activity in the liver. Dietary safflower oil also increased hepatic LDL receptor activity; however, since the rate of LDL production also increased, plasma LDL-cholesterol levels remained essentially unchanged. Hydrogenated coconut oil had no effect on LDL receptor activity but increased the rate of LDL-cholesterol production causing plasma LDL-cholesterol levels to increase 46%. Dietary fish oil had no effect on the receptor-dependent transport of asialofetuin by the liver, suggesting that the effect of fish oil on hepatic LDL receptor activity was specific and not due to a generalized alteration in the physical properties of hepatic membranes. Finally, dietary fish oil increased hepatic cholesteryl ester levels and suppressed hepatic cholesterol synthesis rates, suggesting that the up-regulation of hepatic LDL receptor activity in these animals was not simply a response to diminished cholesterol availability in the liver. PMID:2760200

  16. The Clathrin Adaptor Proteins ARH, Dab2, and Numb Play Distinct Roles in Niemann-Pick C1-Like 1 Versus Low Density Lipoprotein Receptor-mediated Cholesterol Uptake*

    PubMed Central

    Wei, Jian; Fu, Zhen-Yan; Li, Pei-Shan; Miao, Hong-Hua; Li, Bo-Liang; Ma, Yi-Tong; Song, Bao-Liang

    2014-01-01

    The uptake of circulating low density lipoproteins (LDL) is mediated by LDL receptor (LDLR) through clathrin-dependent endocytosis. At the early stage of this process, adaptor proteins ARH and Dab2 specifically bind the endocytic signal motif in LDLR and recruit clathrin/AP2 to initiate internalization. On the other hand, intestinal cholesterol is absorbed by Niemann-Pick C1-Like 1 (NPC1L1) through clathrin-dependent endocytosis. Another adaptor protein, Numb recognizes the endocytic motif in NPC1L1 C terminus and couples NPC1L1 to endocytic machinery. The ARH, Dab2, and Numb proteins contain a homogeneous phosphotyrosine binding (PTB) domain that directly binds endocytic motifs. Because ARH, Dab2, and Numb are all PTB domain family members, the emerging mystery is whether these adaptors act complementally in LDLR and NPC1L1 endocytosis. Here, we found that ARH and Dab2 did not bind NPC1L1 and were not required for NPC1L1 internalization. Similarly, Numb lacked the ability to interact with the LDLR C terminus and was dispensable for LDL uptake. Only the Numb isoforms with shorter PTB domain could facilitate NPC1L1 endocytosis. Besides the reported function in intestinal cholesterol absorption, Numb also mediated cholesterol reabsorption from bile in liver. We further identified a Numb variant with G595D substitution in humans of low blood LDL-cholesterol. The G595D substitution impaired NPC1L1 internalization and cholesterol reabsorption, due to attenuating affinity of Numb to clathrin/AP2. These results demonstrate that Numb specifically regulates NPC1L1-mediated cholesterol absorption both in human intestine and liver, distinct from ARH and Dab2, which selectively participate in LDLR-mediated LDL uptake. PMID:25331956

  17. The clathrin adaptor proteins ARH, Dab2, and numb play distinct roles in Niemann-Pick C1-Like 1 versus low density lipoprotein receptor-mediated cholesterol uptake.

    PubMed

    Wei, Jian; Fu, Zhen-Yan; Li, Pei-Shan; Miao, Hong-Hua; Li, Bo-Liang; Ma, Yi-Tong; Song, Bao-Liang

    2014-11-28

    The uptake of circulating low density lipoproteins (LDL) is mediated by LDL receptor (LDLR) through clathrin-dependent endocytosis. At the early stage of this process, adaptor proteins ARH and Dab2 specifically bind the endocytic signal motif in LDLR and recruit clathrin/AP2 to initiate internalization. On the other hand, intestinal cholesterol is absorbed by Niemann-Pick C1-Like 1 (NPC1L1) through clathrin-dependent endocytosis. Another adaptor protein, Numb recognizes the endocytic motif in NPC1L1 C terminus and couples NPC1L1 to endocytic machinery. The ARH, Dab2, and Numb proteins contain a homogeneous phosphotyrosine binding (PTB) domain that directly binds endocytic motifs. Because ARH, Dab2, and Numb are all PTB domain family members, the emerging mystery is whether these adaptors act complementally in LDLR and NPC1L1 endocytosis. Here, we found that ARH and Dab2 did not bind NPC1L1 and were not required for NPC1L1 internalization. Similarly, Numb lacked the ability to interact with the LDLR C terminus and was dispensable for LDL uptake. Only the Numb isoforms with shorter PTB domain could facilitate NPC1L1 endocytosis. Besides the reported function in intestinal cholesterol absorption, Numb also mediated cholesterol reabsorption from bile in liver. We further identified a Numb variant with G595D substitution in humans of low blood LDL-cholesterol. The G595D substitution impaired NPC1L1 internalization and cholesterol reabsorption, due to attenuating affinity of Numb to clathrin/AP2. These results demonstrate that Numb specifically regulates NPC1L1-mediated cholesterol absorption both in human intestine and liver, distinct from ARH and Dab2, which selectively participate in LDLR-mediated LDL uptake.

  18. The p38 mitogen-activated protein kinase signaling pathway is involved in regulating low-density lipoprotein receptor-related protein 1-mediated β-amyloid protein internalization in mouse brain.

    PubMed

    Ma, Kai-Ge; Lv, Jia; Hu, Xiao-Dan; Shi, Li-Li; Chang, Ke-Wei; Chen, Xin-Lin; Qian, Yi-Hua; Yang, Wei-Na; Qu, Qiu-Min

    2016-07-01

    Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Recently, increasing evidence suggests that intracellular β-amyloid protein (Aβ) alone plays a pivotal role in the progression of AD. Therefore, understanding the signaling pathway and proteins that control Aβ internalization may provide new insight for regulating Aβ levels. In the present study, the regulation of Aβ internalization by p38 mitogen-activated protein kinases (MAPK) through low-density lipoprotein receptor-related protein 1 (LRP1) was analyzed in vivo. The data derived from this investigation revealed that Aβ1-42 were internalized by neurons and astrocytes in mouse brain, and were largely deposited in mitochondria and lysosomes, with some also being found in the endoplasmic reticulum. Aβ1-42-LRP1 complex was formed during Aβ1-42 internalization, and the p38 MAPK signaling pathway was activated by Aβ1-42 via LRP1. Aβ1-42 and LRP1 were co- localized in the cells of parietal cortex and hippocampus. Furthermore, the level of LRP1-mRNA and LRP1 protein involved in Aβ1-42 internalization in mouse brain. The results of this investigation demonstrated that Aβ1-42 induced an LRP1-dependent pathway that related to the activation of p38 MAPK resulting in internalization of Aβ1-42. These results provide evidence supporting a key role for the p38 MAPK signaling pathway which is involved in the regulation of Aβ1-42 internalization in the parietal cortex and hippocampus of mouse through LRP1 in vivo.

  19. Binding of an antibody mimetic of the human low density lipoprotein receptor to apolipoprotein E is governed through electrostatic forces. Studies using site-directed mutagenesis and molecular modeling.

    PubMed

    Raffaï, R; Weisgraber, K H; MacKenzie, R; Rupp, B; Rassart, E; Hirama, T; Innerarity, T L; Milne, R

    2000-03-10

    Monoclonal antibody 2E8 is specific for an epitope that coincides with the binding site of the low density lipoprotein receptor (LDLR) on human apoE. Its reactivity with apoE variants resembles that of the LDLR: it binds well with apoE3 and poorly with apoE2. The heavy chain complementarity-determining region (CDRH) 2 of 2E8 shows homology to the ligand-binding domain of the LDLR. To define better the structural basis of the 2E8/apoE interaction and particularly the role of electrostatic interactions, we generated and characterized a panel of 2E8 variants. Replacement of acidic residues in the 2E8 CDRHs showed that Asp(52), Glu(53), and Asp(56) are essential for high-affinity binding. Although Asp(31) (CDRH1), Glu(58) (CDRH2), and Asp(97) (CDRH3) did not appear to be critical, the Asp(97) --> Ala variant acquired reactivity with apoE2. A Thr(57) --> Glu substitution increased affinity for both apoE3 and apoE2. The affinities of wild-type 2E8 and variants for apoE varied inversely with ionic strength, suggesting that electrostatic forces contribute to both antigen binding and isoform specificity. We propose a model of the 2E8.apoE immune complex that is based on the 2E8 and apoE crystal structures and that is consistent with the apoE-binding properties of wild-type 2E8 and its variants. Given the similarity between the LDLR and 2E8 in terms of specificity, the LDLR/ligand interaction may also have an important electrostatic component.

  20. Amphotericin B toxicity as related to the formation of oxidatively modified low-density lipoproteins.

    PubMed

    Barwicz, J; Dumont, I; Ouellet, C; Gruda, I

    1998-01-01

    The effect of amphotericin B on the oxidation and degradation of low- and high-density lipoproteins was investigated by UV-vis spectroscopy, electron microscopy, electrophoresis, and size-exclusion chromatography. Two formulations of the drug were used: the commercial Fungizone and a new, less toxic, liposomal formulation, AmBisome. It was shown that Fungizone strongly enhanced the oxidative deformation of low-density lipoprotein structure while AmBisome did not bind to this lipoprotein fraction and did not affect its oxidation. It was shown that amphotericin B contained in Fungizone extracted cholesterol from low-density lipoproteins which sensitized them to oxidation. Both formulations of amphotericin B studied here did not bind to high-density lipoprotein and did not affect the process of its oxidation.

  1. Unmodified low density lipoprotein causes cholesteryl ester accumulation in J774 macrophages.

    PubMed

    Tabas, I; Weiland, D A; Tall, A R

    1985-01-01

    Cholesteryl ester (CE)-loaded macrophages (foam cells) are a prominent feature of atherosclerotic plaques. Previous studies have shown that human monocytes or resident mouse peritoneal macrophages accumulate CE in response to low density lipoprotein (LDL) only when the LDL has been appropriately chemically modified. By contrast, we report here that J774 macrophages accumulate large amounts of CE when incubated with unmodified LDL. The CE is stored in oil red O-positive droplets, which have the typical appearance of foam cell inclusions by electron microscopy. The fatty acid moieties of the cellular CE are enriched in oleate unlike those of LDL-CE, which are enriched in linoleate, indicating that the LDL-CE undergoes hydrolysis and reesterification by acyl CoA:cholesterol acyltransferase. Studies with 125I-labeled LDL at both 4 degrees C and 37 degrees C indicate that the LDL is internalized by a specific receptor that has several characteristics in common with the apolipoprotein B/E (apo B/E) receptor. However, in comparison with fibroblasts, the LDL receptor and 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity in J774 cells are relatively resistant to down-regulation by LDL or 25-hydroxycholesterol, leading to receptor-mediated CE storage. In addition, J774 cells appear to accumulate CE from LDL internalized by nonspecific means. Thus, macrophage-like cells can accumulate CE in response to unmodified LDL by both nonspecific and receptor-mediated processes.

  2. Identification of the Functional Variant(s) that Explain the Low-Density Lipoprotein Receptor (LDLR) GWAS SNP rs6511720 Association with Lower LDL-C and Risk of CHD

    PubMed Central

    Palmen, Jutta; Kalea, Anastasia Z.

    2016-01-01

    Background The Low-Density Lipoprotein Receptor (LDLR) SNP rs6511720 (G>T), located in intron-1 of the gene, has been identified in genome-wide association studies (GWAS) as being associated with lower plasma levels of LDL-C and a lower risk of coronary heart disease (CHD). Whether or not rs6511720 is itself functional or a marker for a functional variant elsewhere in the gene is not known. Methods The association of LDLR SNP rs6511720 with incidence of CHD and levels of LDL-C was determined by reference to CARDIoGRAM, C4D and Global lipids genetics consortium (GLGC) data. SNP annotation databases were used to identify possible SNP function and prioritization. Luciferase reporter assays in the liver cell line Huh7 were used to measure the effect of variant genotype on gene expression. Electrophoretic Mobility Shift Assays (EMSAs) were used to identify the Transcription Factors (TFs) involved in gene expression regulation. Results The phenotype-genotype analysis showed that the rs6511720 minor allele is associated with lower level of LDL-C [beta = -0.2209, p = 3.85 x10-262], and lower risk of CHD [log (OR) = 0.1155, p = 1.04 x10-7]. Rs6511720 is in complete linkage. Rs6511720 is in complete linkage disequilibrium (LD) with three intron-1 SNPs (rs141787760, rs60173709, rs57217136). Luciferase reporter assays in Huh7 cells showed that the rare alleles of both rs6511720 and rs57217136 caused a significant increase in LDLR expression compared to the common alleles (+29% and +24%, respectively). Multiplex Competitor-EMSAs (MC-EMSA) identified that the transcription factor serum response element (SRE) binds to rs6511720, while retinoic acid receptor (RAR) and signal transducer and activator of transcription 1 (STAT1) bind to rs57217136. Conclusion Both LDLR rs6511720 and rs57217136 are functional variants. Both these minor alleles create enhancer-binding protein sites for TFs and may contribute to increased LDLR expression, which is consequently associated with reduced

  3. Proteome of human plasma very low-density lipoprotein and low-density lipoprotein exhibits a link with coagulation and lipid metabolism.

    PubMed

    Dashty, M; Motazacker, M M; Levels, J; de Vries, M; Mahmoudi, M; Peppelenbosch, M P; Rezaee, F

    2014-03-03

    Apart from transporting lipids through the body, the human plasma lipoproteins very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) are also thought to serve as a modality for intra-organismal protein transfer, shipping proteins with important roles in inflammation and thrombosis from the site of synthesis to effector locations. To better understand the role of VLDL and LDL in the transport of proteins, we applied a combination of LTQ ORBITRAP-XL (nLC-MS/MS) with both in-SDS-PAGE gel and in-solution tryptic digestion of pure and defined VLDL and LDL fractions. We identified the presence of 95 VLDL- and 51 LDL-associated proteins including all known apolipoproteins and lipid transport proteins, and intriguingly a set of coagulation proteins, complement system and anti- microbial proteins. Prothrombin, protein S, fibrinogen γ, PLTP, CETP, CD14 and LBP were present on VLDL but not on LDL. Prenylcysteine oxidase 1, dermcidin, cathelicidin antimicrobial peptide, TFPI-1 and fibrinogen α chain were associated with both VLDL and LDL. Apo A-V is only present on VLDL and not on LDL. Collectively, this study provides a wealth of knowledge on the protein constituents of the human plasma lipoprotein system and strongly supports the notion that protein shuttling through this system is involved in the regulation of biological processes. Human diseases related to proteins carried by VLDL and LDL can be divided in three major categories: 1 - dyslipidaemia, 2 - atherosclerosis and vascular disease, and 3 - coagulation disorders.

  4. Liver-specific inactivation of the abetalipoproteinemia gene completely abrogates very low density lipoprotein/low density lipoprotein production in a viable conditional knockout mouse.

    PubMed

    Chang, B H; Liao, W; Li, L; Nakamuta, M; Mack, D; Chan, L

    1999-03-05

    Conventional knockout of the microsomal triglyceride transfer protein large subunit (lMTP) gene is embryonic lethal in the homozygous state in mice. We have produced a conditional lMTP knockout mouse by inserting loxP sequences flanking exons 5 and 6 by gene targeting. Homozygous floxed mice were born live with normal plasma lipids. Intravenous injection of an adenovirus harboring Cre recombinase (AdCre1) produced deletion of exons 5 and 6 and disappearance of lMTP mRNA and immunoreactive protein in a liver-specific manner. There was also disappearance of plasma apolipoprotein (apo) B-100 and marked reduction in apoB-48 levels. Wild-type mice showed no response, and heterozygous mice, an intermediate response, to AdCre1. Wild-type mice doubled their plasma cholesterol level following a high cholesterol diet. This hypercholesterolemia was abolished in AdCre1-treated lMTP-/- mice, the result of a complete absence of very low/intermediate/low density lipoproteins and a slight reduction in high density lipoprotein. Heterozygous mice showed an intermediate lipoprotein phenotype. The rate of accumulation of plasma triglyceride following Triton WR1339 treatment in lMTP-/- mice was <10% that in wild-type animals, indicating a failure of triglyceride-rich lipoprotein production. Pulse-chase experiments using hepatocytes isolated from wild-type and lMTP-/- mice revealed a failure of apoB secretion in lMTP-/- animals. Therefore, the liver-specific inactivation of the lMTP gene completely abrogates apoB-100 and very low/intermediate/low density lipoprotein production. These conditional knockout mice are a useful in vivo model for studying the role of MTP in apoB biosynthesis and the biogenesis of apoB-containing lipoproteins.

  5. Overexpression of LOXIN Protects Endothelial Progenitor Cells From Apoptosis Induced by Oxidized Low Density Lipoprotein.

    PubMed

    Veas, Carlos; Jara, Casandra; Willis, Naomi D; Pérez-Contreras, Karen; Gutierrez, Nicolas; Toledo, Jorge; Fernandez, Paulina; Radojkovic, Claudia; Zuñiga, Felipe A; Escudero, Carlos; Aguayo, Claudio

    2016-04-01

    Human endothelial progenitor cells (hEPC) are adult stem cells located in the bone marrow and peripheral blood. Studies have indicated that hEPC play an important role in the recovery and repair of injured endothelium, however, their quantity and functional capacity is reduced in several diseases including hypercholesterolemia. Recently, it has been demonstrated that hEPC express lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and its activation by oxidized low-density lipoprotein (ox-LDL) induces cellular dysfunction and apoptosis. This study aimed to investigate whether overexpression of LOXIN, a truncated isoform of LOX-1 that acts as a dominant negative, plays a protective role against ox-LDL-induced apoptosis in hEPC. Human endothelial progenitor cells exposed to ox-LDL showed a significant increase in LOX-1 expression, and apoptosis began at ox-LDL concentrations above 50 μg/mL. All hEPC apoptosed at 200 μg/mL ox-LDL. High LOXIN expression was generated using adenoviral systems in hEPC and SiHa cells transduced with 100 colony-forming units per cell. Transduced LOXIN localized to the plasma membrane and blocked ox-LDL uptake mediated by LOX-1. Overexpression of LOXIN protected hEPC from ox-LDL-induced apoptosis, and therefore maybe a novel way of improving hEPC function and quantity. These results suggest that adenoviral vectors of LOXIN may provide a possible treatment for diseases related to ox-LDL and vascular endothelium dysfunction, including atherosclerosis.

  6. Increased Very Low Density Lipoprotein Secretion, Hepatic Steatosis, and Insulin Resistance

    PubMed Central

    Choi, Sung Hee; Ginsberg, Henry N

    2011-01-01

    Insulin resistance (IR) not only affects regulation of carbohydrate metabolism, but all aspects of lipid and lipoprotein metabolism. IR is associated with increased secretion of very low density lipoproteins (VLDL) and increased plasma triglycerides, as well as hepatic steatosis, despite the increased VLDL secretion. Here, we link IR with increased VLDL secretion and hepatic steatosis at both the physiologic and molecular levels. Increased VLDL secretion, together with the downstream effects on high density lipoprotein cholesterol and low density lipoprotein size is pro-atherogenic. Hepatic steatosis is a risk for steatohepatitis and cirrhosis. Understanding the complex inter-relationship between IR and these abnormalities of liver lipid homeostasis may provide insights relevant to new therapies for these increasing clinical problems. PMID:21616678

  7. Protective effect of oleanolic acid on oxidized-low density lipoprotein induced endothelial cell apoptosis.

    PubMed

    Cao, Jianhua; Li, Guanghui; Wang, Meizhi; Li, Hui; Han, Zhiwu

    2015-10-01

    Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid, OA) is a naturally-occurring triterpenoid with various promising pharmacological properties. The present study was conducted to determine the protective effects of OA against oxidized low-density lipoprotein (ox-LDL) induced endothelial cell apoptosis and the possible underlying mechanisms. Our results showed that ox-LDL significantly decreased cell viability and induced apoptosis in human umbilical vein endothelial cells (HUVECs). OA in the co-treatment showed a protective effect against ox-LDL induced loss in cell viability and an increase in apoptosis, which was associated with the modulating effect of OA on ox-LDL induced hypoxia-inducible factor 1α(HIF-1α) expression. Moreover, our results showed that the modulating effect of OA against ox-LDL induced HIF-1α expression was obtained via inhibition of lipoprotein receptor 1 (LOX-1)/reactive oxygen species (ROS) signaling. Collectively, we suggested that the protective effect of OA against ox-LDL induced HUVEC apoptosis might, at least in part, be obtained via inhibition of the LOX-1/ROS/HIF-1α signaling pathway.

  8. Metabolic imaging with gallium-68- and indium-111-labeled low-density lipoprotein

    SciTech Connect

    Moerlein, S.M.; Daugherty, A.; Sobel, B.E.; Welch, M.J. )

    1991-02-01

    Low-density lipoprotein (LDL) labeled with either gallium-68 ({sup 68}Ga) or indium-111 ({sup 111}In) was evaluated as a potential PET or SPECT radiopharmaceutical for determination of hepatic lipoprotein metabolism in rabbits. Gallium-68 or {sup 111}In was linked to LDL via diethylenetriaminepentaacetic acid (DTPA) with a 25-70% radiochemical yield. Studies in vivo that compared {sup 68}Ga- or {sup 111}In-DTPA-LDL with dilactitol-({sup 125}I)-tyramine LDL and 131I-LDL showed that both {sup 68}Ga- and {sup 111}In-labeled LDL behaved as residualizing radiotracers. Localization of radioactivity within the liver of normal rabbits was visualized clearly with ({sup 68}Ga)DTPA-LDL by PET and with ({sup 111}In)DTPA-LDL by gamma scintigraphy. Significant differences were observed in hepatic uptake of normal compared with hypercholesterolemic rabbits in which low-capacity LDL receptor-mediated catabolism was saturated. Gallium-68 and {sup 111}In-DTPA-LDL are attractive radiopharmaceuticals for noninvasive delineation of tissue LDL metabolism under normal and pathophysiologic conditions.

  9. Concerted transcriptional activation of the low density lipoprotein receptor gene by insulin and luteinizing hormone in cultured porcine granulosa-luteal cells: possible convergence of protein kinase a, phosphatidylinositol 3-kinase, and mitogen-activated protein kinase signaling pathways.

    PubMed

    Sekar, N; Veldhuis, J D

    2001-07-01

    Insulin and insulin-like growth factor I (IGF-I) can amplify gonadotropin-stimulated steroidogenesis by augmenting the expression of key sterol regulatory genes in ovarian cells, viz. low density lipoprotein (LDL) receptor, steroidogenic acute regulatory protein, and P450 cholesterol side-chain cleavage enzyme (CYP11A). The mechanisms underlying the foregoing bihormonal interactions are not known. Accordingly, in relation to the LDL receptor gene, the present study tests the hypothesis that insulin/IGF-I and LH can act via concerted transcriptional control of promoter expression. To this end, we transiently transfected primary monolayer cultures of porcine granulosa-luteal cells with a reporter vector containing the putative 5'-upstream full-length (pLDLR1076/luc) regulatory region (-1076 to +11 bp) of the homologous LDL receptor gene driving firefly luciferase in the presence or absence of insulin (or IGF-I) and/or LH (each 100 ng/ml). Combined exposure to LH and insulin (or IGF-I) stimulated LDL receptor transcriptional activity maximally at 4 h by 8- to 20-fold, as normalized by coexpression of Renilla luciferase. Further analysis of multiple 5'-nested deletional constructs of the LDL receptor gene promoter showed that deletion of -139 bp upstream of the transcriptional start site virtually abolished basal expression and promoter responsiveness to LH and insulin/IGF-I. In contrast, full basal activity and 60-80% of maximal monohormonal and bihormonal drive were retained by the -255 to +11 bp fragment. As LDL receptor gene expression in other tissues is negatively regulated by the abundance of intracellular free cholesterol, we assessed the impact of concomitant pretreatment of granulosa-luteal cells with an exogenous soluble sterol (25-hydroxycholesterol, 1 and 10 microM). Excess sterol markedly (50-70%) attenuated bihormonally and, in lesser measure, LH-stimulated and basal LDL receptor promoter expression, thus affirming a feedback-sensitive sterol

  10. Obstructive jaundice leads to accumulation of oxidized low density lipoprotein in human liver tissue.

    PubMed

    Comert, Mustafa; Ustundag, Yucel; Tekin, Ishak Ozel; Gun, Banu Dogan; Barut, Figen

    2006-08-21

    Oxidized low density lipoprotein (ox-LDL) molecule is one of the most important modified lipoproteins produced during the oxidative stress. Modified lipoproteins have been defined as being part of the immune inflammatory mechanisms in association with oxidant stress. We have reported the accumulation of ox-LDL in Balb/c mice liver after bile duct ligation previously. Here, we investigated this finding in human beings with obstructive jaundice. Our study demonstrates that obstructive jaundice results in tremendous accumulation of ox-LDL in the liver tissue of patients.

  11. Effect of proteolysis of low-density serum lipoproteins on their interaction with macrophages

    SciTech Connect

    Karmanskii, I.M.; Kovaleva, G.G.; Viktorova, L.N.; Shpikiter, V.O.

    1987-01-01

    The authors previously postulated, on the basis of changes observed in the structural stability of low-density lipoproteins during treatment with pepsin or aortic cathepsin, that enzymatic modifications may lead to potentiation of the atherogenic properties of the lipoproteins. They also reported that treatment of lipoproteins with trypsin causes an increase in their binding with aortic glycosaminoglycans and to increased degradation by fibroblasts of patients with hereditary hypercholesterolemia. Limited proteolysis of lipoproteins with pepsin facilitated their binding with fibronectin. In this paper the authors investigate the uptake and degradation of low-density lipoproteins by macrophages after their limited hydrolysis by pepsin, an analog of tissue cathepsin D. The lipoproteins were isolated from the serum of healthy blood donors by ultracentrifugation. Iodination of the proteins with I 125 was carried out by the iodine monochloride method. Uptake and retention of the labelled lipoprotein were measured with a gamma counter. The increased uptake of the proteins, partially hydrolized by pepsin, was accompanied by their more intense degradation by macrophages.

  12. Thermal transitions in the low-density lipoprotein and lipids of the egg yolk of hens.

    PubMed

    Smith, M B; Back, J F

    1975-05-22

    1. Differential sanning calorimetry and light-scattering have been used to investigate temperature-dependent transitions in low-density lipoprotein and in lipids from hens' egg yolk. Yolks of different fatty acid composition were obtained by varying the dietary lipid and by adding methyl sterculate to the hen's diet. 2. Lipoprotein solutions in 50 percent glycerol/water gave characteristic melting curves between -25 degrees C and 50 degrees C, and on cooling showed increases in light-scattering between 10 degrees C and -20 degrees C. The temperatures at which major changes occurred depended on the proportions of saturated and unsaturated fatty acids. 3. The thermal transitions in the intact lipoprotein in glycerol solution were reversible, but with marked hysteresis. Lipid extracted from the lipoprotein did not show temperature hystersis but the transition heats and melting curves similar to those of the intact lipoprotein. The results support the hypothesis of a "lipid-core" structure for low-density lipoproteins. 4. Scanning calorimetry of egg-yolk lecithins indicated a strong dependence of transition temperature on water content in the rane 3 percent-20 percent water. A rise in the mid-temperature of the liquid-crystalline to gel transition as the water content is lowered on freezing may be the primary event in the irreversible gelation of egg yolk and aggregation of lipoprotein.

  13. Lipolysis Produces Changes in the Immunoreactivity and Cell Reactivity of Very Low Density Lipoproteins

    PubMed Central

    Schonfeld, G.; Patsch, W.; Pfleger, B.; Witztum, J. L.; Weidman, S. W.

    1979-01-01

    Smaller very low density lipoprotein (VLDL) remnants interact more readily with tissues than do larger “intact” VLDL. This may be related to changes in the availability of VLDL apoproteins on the surface of the lipoproteins. To test this hypothesis VLDL were incubated at 37°C with bovine milk lipase (LPL), and the abilities of LPL-treated VLDL preparations to compete with 125I-low density lipoproteins (LDL) for interaction with cultured normal human fibroblasts were measured. At the same time, the immunologic activities of these preparations were also tested by double antibody radioimmunoassay. Triglyceride (TG) contents of VLDL fell by 30-90% during incubation with LPL and, on zonal ultracentrifugation, VLDL of faster Svedberg unit of flotation (Sf1.063) rates (>150) were gradually converted to smaller VLDL with lower Sf rates (21-60). LPL-treated VLDL competed two to five times more effectively with 125I-LDL for binding to cellular receptors than did control VLDL. Control VLDL incubated with heat-inactivated LPL at 37°C, or with active LPL at 4°C had unaltered cell reactivities and TG contents compared with VLDL incubated without any enzyme. The direct uptake and degradation of LPL-treated VLDL was also assessed by using VLDL 125I-labeled in apoprotein (Apo)B. LPL-treated VLDL-125I-ApoB were taken up and degraded by fibroblast at greater rates than were control VLDL-125I-ApoB. Thus, hydrolysis of VLDL lipids was accompanied by an increased ability of VLDL to interact with fibroblasts. The immunoreactivity of ApoB in the same VLDL preparations, expressed as the “apparent ApoB contents” of LPL-treated VLDL, increased by 10-50% (P < 0.02) in those assays that contained anti-LDL antisera, but the ApoB of control VLDL remained constant. However, assays that contained antisera directed against ApoB isolated from VLDL did not distinguish between LPL-treated and control VLDL. Thus, VLDL lipid hydrolysis was accompanied by changes in the immunoreactivity of

  14. Direct Low Density Lipoprotein Cholesterol and Glycated Albumin Levels in Type 2 Diabetes Mellitus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) have been associated with a decreased risk of these complications. The aim in this st...

  15. Glycated albumin and direct low density lipoprotein cholesterol levels in type 2 diabetes mellitus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Diabetes mellitus is a major risk factor for coronary heart disease (CHD), renal failure, retinopathy, and neuropathy. Lowering glycosylated hemoglobin (HbA1c) as well as low-density lipoprotein-cholesterol (LDL-C) has been associated with a decreased risk of these complications. We evaluated the ut...

  16. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunological Test Systems §...

  17. 21 CFR 866.5600 - Low-density lipoprotein immunological test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Low-density lipoprotein immunological test system. 866.5600 Section 866.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Immunological Test Systems §...

  18. Low Density Lipoprotein Receptor-related Protein 1 (LRP1) Modulates N-Methyl-d-aspartate (NMDA) Receptor-dependent Intracellular Signaling and NMDA-induced Regulation of Postsynaptic Protein Complexes*

    PubMed Central

    Nakajima, Chikako; Kulik, Akos; Frotscher, Michael; Herz, Joachim; Schäfer, Michael; Bock, Hans H.; May, Petra

    2013-01-01

    The lipoprotein receptor LRP1 is essential in neurons of the central nervous system, as was revealed by the analysis of conditional Lrp1-deficient mouse models. The molecular basis of its neuronal functions, however, is still incompletely understood. Here we show by immunocytochemistry, electron microscopy, and postsynaptic density preparation that LRP1 is located postsynaptically. Basal and NMDA-induced phosphorylation of the transcription factor cAMP-response element-binding protein (CREB) as well as NMDA target gene transcription are reduced in LRP1-deficient neurons. In control neurons, NMDA promotes γ-secretase-dependent release of the LRP1 intracellular domain (LRP1-ICD). However, pull-down and chromatin immunoprecipitation (ChIP) assays showed no direct interaction between the LRP1-ICD and either CREB or target gene promoters. On the other hand, NMDA-induced degradation of the postsynaptic scaffold protein PSD-95 was impaired in the absence of LRP1, whereas its ubiquitination was increased, indicating that LRP1 influences the composition of postsynaptic protein complexes. Accordingly, NMDA-induced internalization of the AMPA receptor subunit GluA1 was impaired in LRP1-deficient neurons. These results show a role of LRP1 in the regulation and turnover of synaptic proteins, which may contribute to the reduced dendritic branching and to the neurological phenotype observed in the absence of LRP1. PMID:23760271

  19. LIPOPROTEIN LIPASE RELEASES ESTERIFIED OXYLIPINS FROM VERY LOW-DENSITY LIPOPROTEINS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Defects in lipoprotein metabolism alter the lipoprotein distribution of oxidized PUFAs, and we speculate that lipoprotein lipase (LpL) is a determinant in the release of VLDL-associated oxylipins. Here, using 12 wk old normolipidemic (lean) and hyperlipidemic (obese) Zucker-rats, we measured PUFA al...

  20. Linkage of low-density lipoprotein size to the lipoprotein lipase gene in heterozygous lipoprotein lipase deficiency.

    PubMed Central

    Hokanson, J E; Brunzell, J D; Jarvik, G P; Wijsman, E M; Austin, M A

    1999-01-01

    Small low-density lipoprotein (LDL) particles are a genetically influenced coronary disease risk factor. Lipoprotein lipase (LpL) is a rate-limiting enzyme in the formation of LDL particles. The current study examined genetic linkage of LDL particle size to the LpL gene in five families with structural mutations in the LpL gene. LDL particle size was smaller among the heterozygous subjects, compared with controls. Among heterozygous subjects, 44% were classified as affected by LDL subclass phenotype B, compared with 8% of normal family members. Plasma triglyceride levels were significantly higher, and high-density lipoprotein cholesterol (HDL-C) levels were lower, in heterozygous subjects, compared with normal subjects, after age and sex adjustment. A highly significant LOD score of 6.24 at straight theta=0 was obtained for linkage of LDL particle size to the LpL gene, after adjustment of LDL particle size for within-genotype variance resulting from triglyceride and HDL-C. Failure to adjust for this variance led to only a modest positive LOD score of 1.54 at straight theta=0. Classifying small LDL particles as a qualitative trait (LDL subclass phenotype B) provided only suggestive evidence for linkage to the LpL gene (LOD=1. 65 at straight theta=0). Thus, use of the quantitative trait adjusted for within-genotype variance, resulting from physiologic covariates, was crucial for detection of significant evidence of linkage in this study. These results indicate that heterozygous LpL deficiency may be one cause of small LDL particles and may provide a potential mechanism for the increase in coronary disease seen in heterozygous LpL deficiency. This study also demonstrates a successful strategy of genotypic specific adjustment of complex traits in mapping a quantitative trait locus. PMID:9973300

  1. 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.

  2. Oxidized low-density lipoprotein decreases VEGFR2 expression in HUVECs and impairs angiogenesis

    PubMed Central

    Zhang, Min; Jiang, Li

    2016-01-01

    Atherosclerosis (AS), which is triggered by endothelial cell injury, evolves into a chronic inflammatory disease. Oxidized low-density lipoprotein (ox-LDL) is an important risk factor for the development of atherosclerosis; ox-LDL induces atherosclerotic plaque formation via scavenging receptors. The present study used ox-LDL-treated human umbilical vein endothelial cells (HUVECs) to investigate the effect of ox-LDL on angiogenesis. ox-LDL decreased HUVEC proliferation by MTT, induced apoptosis by Annexin V-fluorescein isothiocyanate (FITC) staining and markedly suppressed HUVEC tube formation by the Matrigel assay in a dose-dependent manner. Angiogenesis has been correlated with monocyte invasion, plaque instability and atherosclerotic lesion formation. In addition, ox-LDL induced the overproduction of reactive oxygen species using DCFH-DA staining and increased caspase-3 activity. Vascular endothelial growth factor receptor 2 (VEGFR2) were detected by quantitative polymerase chain reaction and western blot analysis and has previously been observed to have a key role in angiogenesis. Furthermore, the present study demonstrated that the abundance of VEGFR2 was decreased in ox-LDL-treated HUVECs. These results suggested that ox-LDL impairs angiogenesis via VEGFR2 degradation, thus suggesting that VEGFR2 may be involved in adaptation to oxidative stress and AS. PMID:28105106

  3. Antibodies against low-density lipoprotein receptor–related protein 4 induce myasthenia gravis

    PubMed Central

    Shen, Chengyong; Lu, Yisheng; Zhang, Bin; Figueiredo, Dwight; Bean, Jonathan; Jung, Jiung; Wu, Haitao; Barik, Arnab; Yin, Dong-Min; Xiong, Wen-Cheng; Mei, Lin

    2013-01-01

    Myasthenia gravis (MG) is the most common disorder affecting the neuromuscular junction (NMJ). MG is frequently caused by autoantibodies against acetylcholine receptor (AChR) and a kinase critical for NMJ formation, MuSK; however, a proportion of MG patients are double-negative for anti-AChR and anti-MuSK antibodies. Recent studies in these subjects have identified autoantibodies against low-density lipoprotein receptor–related protein 4 (LRP4), an agrin receptor also critical for NMJ formation. LRP4 autoantibodies have not previously been implicated in MG pathogenesis. Here we demonstrate that mice immunized with the extracellular domain of LRP4 generated anti-LRP4 antibodies and exhibited MG-associated symptoms, including muscle weakness, reduced compound muscle action potentials (CMAPs), and compromised neuromuscular transmission. Additionally, fragmented and distorted NMJs were evident at both the light microscopic and electron microscopic levels. We found that anti-LRP4 sera decreased cell surface LRP4 levels, inhibited agrin-induced MuSK activation and AChR clustering, and activated complements, revealing potential pathophysiological mechanisms. To further confirm the pathogenicity of LRP4 antibodies, we transferred IgGs purified from LRP4-immunized rabbits into naive mice and found that they exhibited MG-like symptoms, including reduced CMAP and impaired neuromuscular transmission. Together, these data demonstrate that LRP4 autoantibodies induce MG and that LRP4 contributes to NMJ maintenance in adulthood. PMID:24200689

  4. Oxidized low-density lipoprotein decreases VEGFR2 expression in HUVECs and impairs angiogenesis.

    PubMed

    Zhang, Min; Jiang, Li

    2016-12-01

    Atherosclerosis (AS), which is triggered by endothelial cell injury, evolves into a chronic inflammatory disease. Oxidized low-density lipoprotein (ox-LDL) is an important risk factor for the development of atherosclerosis; ox-LDL induces atherosclerotic plaque formation via scavenging receptors. The present study used ox-LDL-treated human umbilical vein endothelial cells (HUVECs) to investigate the effect of ox-LDL on angiogenesis. ox-LDL decreased HUVEC proliferation by MTT, induced apoptosis by Annexin V-fluorescein isothiocyanate (FITC) staining and markedly suppressed HUVEC tube formation by the Matrigel assay in a dose-dependent manner. Angiogenesis has been correlated with monocyte invasion, plaque instability and atherosclerotic lesion formation. In addition, ox-LDL induced the overproduction of reactive oxygen species using DCFH-DA staining and increased caspase-3 activity. Vascular endothelial growth factor receptor 2 (VEGFR2) were detected by quantitative polymerase chain reaction and western blot analysis and has previously been observed to have a key role in angiogenesis. Furthermore, the present study demonstrated that the abundance of VEGFR2 was decreased in ox-LDL-treated HUVECs. These results suggested that ox-LDL impairs angiogenesis via VEGFR2 degradation, thus suggesting that VEGFR2 may be involved in adaptation to oxidative stress and AS.

  5. Oxidized low-density lipoproteins upregulate proline oxidase to initiate ROS-dependent autophagy.

    PubMed

    Zabirnyk, Olga; Liu, Wei; Khalil, Shadi; Sharma, Anit; Phang, James M

    2010-03-01

    Epidemiological studies showed that high levels of oxidized low-density lipoproteins (oxLDLs) are associated with increased cancer risk. We examined the direct effect of physiologic concentrations oxLDL on cancer cells. OxLDLs were cytotoxic and activate both apoptosis and autophagy. OxLDLs have ligands for peroxisome proliferator-activated receptor gamma and upregulated proline oxidase (POX) through this nuclear receptor. We identified 7-ketocholesterol (7KC) as a main component responsible for the latter. To elucidate the role of POX in oxLDL-mediated cytotoxicity, we knocked down POX via small interfering RNA and found that this (i) further reduced viability of cancer cells treated with oxLDL; (ii) decreased oxLDL-associated reactive oxygen species generation; (iii) decreased autophagy measured via beclin-1 protein level and light-chain 3 protein (LC3)-I into LC3-II conversion. Using POX-expressing cell model, we established that single POX overexpression was sufficient to activate autophagy. Thus, it led to autophagosomes accumulation and increased conversion of LC3-I into LC3-II. Moreover, beclin-1 gene expression was directly dependent on POX catalytic activity, namely the generation of POX-dependent superoxide. We conclude that POX is critical in the cellular response to the noxious effects of oxLDL by activating protective autophagy.

  6. Oxidized low density lipoprotein (LDL) affects hyaluronan synthesis in human aortic smooth muscle cells.

    PubMed

    Viola, Manuela; Bartolini, Barbara; Vigetti, Davide; Karousou, Evgenia; Moretto, Paola; Deleonibus, Sara; Sawamura, Tatsuya; Wight, Thomas N; Hascall, Vincent C; De Luca, Giancarlo; Passi, Alberto

    2013-10-11

    Thickening of the vessel in response to high low density lipoprotein(s) (LDL) levels is a hallmark of atherosclerosis, characterized by increased hyaluronan (HA) deposition in the neointima. Human native LDL trapped within the arterial wall undergoes modifications such as oxidation (oxLDL). The aim of our study is to elucidate the link between internalization of oxLDL and HA production in vitro, using human aortic smooth muscle cells. LDL were used at an effective protein concentration of 20-50 μg/ml, which allowed 80% cell viability. HA content in the medium of untreated cells was 28.9 ± 3.7 nmol HA-disaccharide/cell and increased after oxLDL treatment to 53.9 ± 5.6. OxLDL treatments doubled the transcripts of HA synthase HAS2 and HAS3. Accumulated HA stimulated migration of aortic smooth muscle cells and monocyte adhesiveness to extracellular matrix. The effects induced by oxLDL were inhibited by blocking LOX-1 scavenger receptor with a specific antibody (10 μg/ml). The cholesterol moiety of LDL has an important role in HA accumulation because cholesterol-free oxLDL failed to induce HA synthesis. Nevertheless, cholesterol-free oxLDL and unmodified cholesterol (20 μg/ml) induce only HAS3 transcription, whereas 22,oxysterol affects both HAS2 and HAS3. Moreover, HA deposition was associated with higher expression of endoplasmic reticulum stress markers (CHOP and GRP78). Our data suggest that HA synthesis can be induced in response to specific oxidized sterol-related species delivered through oxLDL.

  7. Rspo2 suppresses CD36-mediated apoptosis in oxidized low density lipoprotein-induced macrophages

    PubMed Central

    Yan, Hui; Wang, Shuai; Li, Zhenwei; Sun, Zewei; Zan, Jie; Zhao, Wenting; Pan, Yanyun; Wang, Zhen; Wu, Mingjie; Zhu, Jianhua

    2016-01-01

    Oxidized low density lipoprotein (oxLDL)-induced apoptosis of macrophages contributes to the formation of atherosclerotic plaques. R-spondin 2 (Rspo2), a member of the cysteine-rich secreted proteins, has been shown to be involved in the oncogenesis of several types of cancer. It has also been found to be abundantly expressed among the four R-spondin members in macrophages. The present study was performed to determine whether Rspo2 is involved in the ox-LDL-induced apoptosis of macrophages. It was identified that Rspo2 inhibited oxLDL-induced apoptosis in the presence of endoplasmic reticulum (ER) stress activator using flow cytometry. In addition, Rspo2 was observed to suppress oxLDL-induced ER stress and reactive oxygen species production as demonstrated by western blotting. Furthermore, analysis of the role of Rspo2 in macrophage lipid uptake identified that Rspo2 negatively regulated the Dil-oxLDL uptake by inhibiting the expression of cluster of differentiation (CD)36, through the transcription factor, peroxisome proliferator-activated receptor (PPAR)-γ. The manipulation of Rspo2 had a direct effect on PPAR-γ nuclear translocation. In addition, chromatin immunoprecipitation analysis revealed that Rspo2 manipulation led to regulation of the direct binding between PPAR-γ and CD36. In conclusion, Rspo2 was found to have a negative regulatory effect during oxLDL-induced macrophage apoptosis by regulating lipid uptake. PMID:27571704

  8. Protein modification elicited by oxidized low-density lipoprotein (LDL) in endothelial cells: protection by (-)-epicatechin.

    PubMed

    Steffen, Yvonne; Jung, Tobias; Klotz, Lars-Oliver; Schewe, Tankred; Grune, Tilman; Sies, Helmut

    2007-04-01

    The action of oxidatively modified low-density lipoprotein (oxLDL) on vascular endothelial cells has been proposed to be a crucial process leading to endothelial dysfunction and atherogenesis. OxLDL was shown here to elicit oxidative stress in bovine aortic endothelial cells or human umbilical vein endothelial cells, as judged by an increase in 2',7'-dichlorofluorescein fluorescence and elevated levels of carbonylated, nitrated, and 2-hydroxynonenal-coupled proteins. These effects were sensitive to apocynin, indicating involvement of NADPH oxidase. A 170-kDa polypeptide carbonylated upon exposure of cells to oxLDL was identified by immunoprecipitation as EGF receptor. Immunocytochemical visualization by confocal microscopy revealed the highest levels of modified proteins in the perinuclear region. Exposure of endothelial cells to oxLDL led to modulation of the expression levels of *NO synthases; the endothelial isoform (eNOS) was down-regulated via proteasomal degradation, whereas the inducible isoform (iNOS) was up-regulated in an enzymatically active state. eNOS protein was found to be both carbonylated and nitrated upon exposure of cells to oxLDL. iNOS contributed to the generation of modified proteins as judged by the effects of the selective inhibitor L-NIO. These oxLDL-elicited changes in vascular endothelial cells described were suppressed by (-)-epicatechin, a dietary polyphenol, which inhibited NADPH oxidase activity in these cells.

  9. Low-Density Lipoprotein Nanoparticles as Magnetic Resonance Imaging Contrast Agents1

    PubMed Central

    Corbin, Ian R; Li, Hui; Chen, Juan; Lund-Katz, Sissel; Zhou, Rong; Glickson, Jerry D; Zheng, Gang

    2006-01-01

    Abstract Low-density lipoproteins (LDLs) are a naturally occurring endogenous nanoplatform in mammalian systems. These nanoparticles (22 nm) specifically transport cholesterol to cells expressing the LDL receptor (LDLR). Several tumors overexpress LDLRs presumably to provide cholesterol to sustain a high rate of membrane synthesis. Amphiphilic gadolinium (Gd)-diethylenetria-minepentaacetic acid chelates have been incorporated into the LDL to produce a novel LDLR-targeted magnetic resonance imaging (MRI) contrast agent. The number of Gd chelates per LDL particle ranged between 150 and 496 Gd(III). In vitro studies demonstrated that Gd-labeled LDL retained a similar diameter and surface charge as the native LDL particle. In addition, Gd-labeled LDL retained selective cellular binding and uptake through LDLR-mediated endocytosis. Finally, Gd-labeled LDLs exhibited significant contrast enhancement 24 hours after administration in nude mice with human hepatoblastoma G2 xenografts. Thus, Gd-labeled LDL demonstrates potential use as a targeted MRI contrast agent for in vivo tumor detection. PMID:16820095

  10. Terminalia bellirica Extract Inhibits Low-Density Lipoprotein Oxidation and Macrophage Inflammatory Response in Vitro

    PubMed Central

    Tanaka, Miori; Kishimoto, Yoshimi; Saita, Emi; Suzuki-Sugihara, Norie; Kamiya, Tomoyasu; Taguchi, Chie; Iida, Kaoruko; Kondo, Kazuo

    2016-01-01

    The deciduous tree Terminalia bellirica found in Southeast Asia is extensively used in traditional Indian Ayurvedic medicine for the treatment of hypertension, rheumatism, and diabetes. The anti-atherogenic effect of Terminalia bellirica fruit has not been fully elucidated. Here, we investigated the effect of Terminalia bellirica extract (TBE) on low-density lipoprotein (LDL) oxidation and inflammation in macrophages. TBE showed 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (EC50: 7.2 ± 1.2 μg/mL) and 15-lipoxygenase inhibitory activity. TBE also significantly inhibited free radical-induced LDL oxidation compared to the solvent control in vitro. In THP-1 macrophages, TBE treatment resulted in significant decreases of the mRNA expression of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and lectin-like oxidized LDL receptor-1 (LOX-1). TBE also reduced matrix metalloproteinase (MMP)-9 secretion and intracellular reactive oxygen species (ROS) production in THP-1 macrophages. These results show that TBE has the inhibitory effects on LDL oxidation and macrophage inflammatory response in vitro, suggesting that its in vivo use might inhibit atherosclerosis plaque progression. PMID:27314393

  11. 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

  12. Clinical efficacy and safety of evolocumab for low-density lipoprotein cholesterol reduction.

    PubMed

    Henry, Courtney A; Lyon, Ronald A; Ling, Hua

    2016-01-01

    Multiple categories of medications have been developed to manage lipid profiles and reduce the risk of cardiovascular events in patients with heart disease. However, currently marketed medications have not solved the problems associated with preventing and treating cardiovascular diseases completely. A substantial population of patients cannot take advantage of statin therapy due to statin intolerance, heart failure, or kidney hemodialysis, suggesting a need for additional effective agents to reduce low-density lipoprotein cholesterol (LDL-C) levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) was discovered in 2003 and subsequently emerged as a novel target for LDL-C-lowering therapy. Evolocumab is a fully human monoclonal immunoglobulin G2 (IgG2) directed against human PCSK9. By inactivating PCSK9, evolocumab upregulates LDL receptors causing increased catabolism of LDL-C and the consequent reduction of LDL-C levels in blood. Overall, evolocumab has had notable efficacy, with LDL-C reduction ranging from 53% to 75% in monotherapy and combination therapies, and is associated with minor adverse effects. However, studies regarding the ability of evolocumab to reduce mortality as well as long-term safety concerns are limited. The fact that the drug was introduced at a cost much higher than the existing medications and shows a low incremental mortality benefit suggests that many payers will consider evolocumab to have an unfavorable cost-benefit ratio.

  13. Comparison of apoprotein B of low density lipoproteins of human interstitial fluid and plasma.

    PubMed

    Hong, J L; Pflug, J; Reichl, D

    1984-08-15

    Virtually all apoprotein B (apoB)-containing lipoproteins of the peripheral interstitial fluid of subjects with primary lymphoedema float in the ultracentrifugal field in the density interval 1.019-1.063 g/ml; in this respect they are similar to plasma low-density lipoproteins (LDL). 2. Virtually all apo-B-containing lipoproteins of interstitial fluid migrate in the electrophoretic field with pre-beta mobility; in this respect they are similar to plasma very-low-density lipoproteins. 3. The apoB of lipoproteins of interstitial fluid does not differ in terms of Mr from apoB-100 of human plasma [Kane, Hardman & Paulus (1980) Proc. Natl. Acad. Sci. U.S.A. 77, 2465-2469] as determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 4. Both apoB of interstitial fluid and plasma are heterogenous in terms of their charge as determined by isoelectric focusing of their complexes with the nonionic detergent Nonidet P40. ApoB of plasma LDL focuses between pH5.9 and 6.65, and that of interstitial fluid LDL between pH 5.9 and 6.1. Thus the overall charge of apoB of interstitial fluid is more negative than that of its plasma LDL counterpart.

  14. Lipolytic degradation of human very low density lipoproteins by human milk lipoprotein lipase: the identification of lipoprotein B as the main lipoprotein degradation product.

    PubMed

    Alaupovic, P; Wang, C S; McConathy, W J; Weiser, D; Downs, D

    1986-01-01

    Although the direct conversion of very low density lipoproteins (VLDL) into low density (LDL) and high density (HDL) lipoproteins only requires lipoprotein lipase (LPL) as a catalyst and albumin as the fatty acid acceptor, the in vitro-formed LDL and HDL differ chemically from their native counterparts. To investigate the reason(s) for these differences, VLDL were treated with human milk LPL in the presence of albumin, and the LPL-generated LDL1-, LDL2-, and HDL-like particles were characterized by lipid and apolipoprotein composition. Results showed that the removal of apolipoproteins B, C, and E from VLDL was proportional to the degree of triglyceride hydrolysis with LDL2 particles as the major and LDL1 and HDL + VHDL particles as the minor products of a complete in vitro lipolysis of VLDL. In comparison with native counterparts, the in vitro-formed LDL2 and HDL + VHDL were characterized by lower levels of triglyceride and cholesterol ester and higher levels of free cholesterol and lipid phosphorus. The characterization of lipoprotein particles present in the in vitro-produced LDL2 showed that, as in plasma LDL2, lipoprotein B (LP-B) was the major apolipoprotein B-containing lipoprotein accounting for over 90% of the total apolipoprotein B. Other, minor species of apolipoprotein B-containing lipoproteins included LP-B:C-I:E and LP-B:C-I:C-II:C-III. The lipid composition of in vitro-formed LP-B closely resembled that of plasma LP-B. The major parts of apolipoproteins C and E present in VLDL were released to HDL + VHDL as simple, cholesterol/phospholipid-rich lipoproteins including LP-C-I, LP-C-II, LP-C-III, and LP-E. However, some of these same simple lipoprotein particles were present after ultracentrifugation in the LDL2 density segment because of their hydrated density and/or because they formed, in the absence of naturally occurring acceptors (LP-A-I:A-II), weak associations with LP-B. Thus, the presence of varying amounts of these cholesterol

  15. Social Inclusion Predicts Lower Blood Glucose and Low-Density Lipoproteins in Healthy Adults.

    PubMed

    Floyd, Kory; Veksler, Alice E; McEwan, Bree; Hesse, Colin; Boren, Justin P; Dinsmore, Dana R; Pavlich, Corey A

    2016-07-27

    Loneliness has been shown to have direct effects on one's personal well-being. Specifically, a greater feeling of loneliness is associated with negative mental health outcomes, negative health behaviors, and an increased likelihood of premature mortality. Using the neuroendocrine hypothesis, we expected social inclusion to predict decreases in both blood glucose levels and low-density lipoproteins (LDLs) and increases in high-density lipoproteins (HDLs). Fifty-two healthy adults provided self-report data for social inclusion and blood samples for hematological tests. Results indicated that higher social inclusion predicted lower levels of blood glucose and LDL, but had no effect on HDL. Implications for theory and practice are discussed.

  16. Enzymatic Modification of Plasma Low Density Lipoproteins in Rabbits: A Potential Treatment for Hypercholesterolemia

    NASA Astrophysics Data System (ADS)

    Labeque, Regine; Mullon, Claudy J. P.; Ferreira, Joao Paulo M.; Lees, Robert S.; Langer, Robert

    1993-04-01

    Phospholipase A_2 (EC 3.1.1.4) hydrolyzes certain phospholipids of low density lipoprotein (LDL). Plasma clearance of phospholipase A_2-modified human LDL is up to 17 times faster than that of native human LDL in hypercholesterolemic rabbits. Modification of blood lipoproteins of hypercholesterolemic rabbits was performed by using an extracorporeal circuit containing immobilized phospholipase A_2. After 90-min treatments, nearly 30% decreases in plasma cholesterol concentrations were observed. Erythrocyte, leukocyte, and platelet counts showed no net change after treatment. This technique does not require any fluid replacement or sorbent regeneration and offers a potential approach for lowering serum cholesterol and LDL levels.

  17. Increased expression of apolipoprotein E in transgenic rabbits results in reduced levels of very low density lipoproteins and an accumulation of low density lipoproteins in plasma.

    PubMed Central

    Fan, J; Ji, Z S; Huang, Y; de Silva, H; Sanan, D; Mahley, R W; Innerarity, T L; Taylor, J M

    1998-01-01

    Transgenic rabbits expressing human apo E3 were generated to investigate mechanisms by which apo E modulates plasma lipoprotein metabolism. Compared with nontransgenic littermates expressing approximately 3 mg/dl of endogenous rabbit apo E, male transgenic rabbits expressing approximately 13 mg/dl of human apo E had a 35% decrease in total plasma triglycerides that was due to a reduction in VLDL levels and an absence of large VLDL. With its greater content of apo E, transgenic VLDL had an increased binding affinity for the LDL receptor in vitro, and injected chylomicrons were cleared more rapidly by the liver in transgenic rabbits. In contrast to triglyceride changes, transgenic rabbits had a 70% increase in plasma cholesterol levels due to an accumulation of LDL and apo E-rich HDL. Transgenic and control LDL had the same binding affinity for the LDL receptor. Both transgenic and control rabbits had similar LDL receptor levels, but intravenously injected human LDL were cleared more slowly in transgenic rabbits than in controls. Changes in lipoprotein lipolysis did not contribute to the accumulation of LDL or the reduction in VLDL levels. These observations suggest that the increased content of apo E3 on triglyceride-rich remnant lipoproteins in transgenic rabbits confers a greater affinity for cell surface receptors, thereby increasing remnant clearance from plasma. The apo E-rich large remnants appear to compete more effectively than LDL for receptor-mediated binding and clearance, resulting in delayed clearance and the accumulation of LDL in plasma. PMID:9593771

  18. [Interaction of very low density lipoproteins (VLDL) with macrophages and their triboluminescence in hypercholesterolemia].

    PubMed

    Voziian, P A; Orel, V E; Baraboĭ, V A; Korniets, G V; Kholodova, Iu D

    1991-01-01

    Accumulation of cholesterol esters and triglycerides in peritoneal mice macrophages in the course of their interaction with lipoproteins of very low density (VLDL) is shown to grow considerably under conditions of hypercholesterolemia. A decrease of triboluminescence intensity characterizing the surface charge has been revealed at hypercholesterolemia both in VLDL and in the blood plasma. It is supposed that the triboluminescence method may be used for testing of the atherosclerotic process development.

  19. Chylomicron remnant cholesteryl esters as the major constituent of very low density lipoproteins in plasma of cholesterol-fed rabbits.

    PubMed

    Ross, A C; Zilversmit, D B

    1977-03-01

    Feeding rabbits 500 mg of cholesterol daily for 4 to 15 days greatly increased the concentration of esterified cholesterol in lipoproteins of d less than 1.006 g/ml. The origin of hypercholesterolemic very low density lipoproteins was investigated by monitoring the degradation of labeled lymph chyomicrons administered to normal and cholesterol-fed rabbits. Chylomicrons were labeled in vivo by feeding either 1) [3H]cholesterol and [14C]oleic acid or 2) [14C]cholesterol and [3H]retinyl acetate. After intravenous injection of labeled chylomicrons to recipient rabbits, [14C]triglyceride hydrolysis was equally rapid in normal and cholesterol-fed animals. Normal rabbits rapidly removed from plasma both labeled cholesteryl and retinyl esters, whereas cholesterol-fed rabbits retained nearly 50% of doubly labeled remnants in plasma 25 min after chylomicron injection. Ultracentrifugal separation of plasma into subfractions of very low density lipoproteins showed that chylomicron remnants in cholesterol-fed animals are found among all subclasses of very low density lipoproteins. Analysis of cholesteryl ester specific activity-time curves for the very low density lipoproteins subfraction from hypercholesterolemic plasma showed that nearly all esterified cholesterol in large very low density lipoproteins and approximately 30% of esterified cholesterol in small very low density lipoproteins was derived from chylomicron degradation. Apparently, nearly two-thirds of the esterified cholesterol in total very low density lipoproteins from moderately hypercholesterolemic rabbits is of dietary origin.

  20. Profound induction of hepatic cholesteryl ester transfer protein transgene expression in apolipoprotein E and low density lipoprotein receptor gene knockout mice. A novel mechanism signals changes in plasma cholesterol levels.

    PubMed Central

    Masucci-Magoulas, L; Plump, A; Jiang, X C; Walsh, A; Breslow, J L; Tall, A R

    1996-01-01

    The plasma cholesteryl ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to other lipoproteins and is a key regulated component of reverse cholesterol transport. Dietary hypercholesterolemia results in increased hepatic CETP gene transcription and higher plasma CETP levels. To investigate the mechanisms by which the liver senses hypercholesterolemia, mice containing a natural flanking region CETP transgene (NFR-CETP transgene) were bred with apo E or LDL receptor gene knockout mice (E0 or LDLr0 mice). Compared to NFR-CETP transgenic (Tg) mice with intact apo E genes, in NFR-CETP Tg/E0 mice there was an eightfold induction of plasma CETP levels and a parallel increase in hepatic CETP mRNA levels. Other sterol-responsive genes (LDL receptor and hydroxymethyl glutaryl CoA reductase) also showed evidence of altered regulation with decreased abundance of their mRNAs in the E0 background. A similar induction of plasma CETP and hepatic CETP mRNA levels resulted from breeding the NFR-CETP transgene into the LDL receptor gene knockout background. When placed on a high cholesterol diet, there was a further increase in CETP levels in both E0 and LDLr0 backgrounds. In CETP Tg, CETP Tg/E0, and CETP Tg/LDLr0 mice on different diets, plasma CETP and CETP mRNA levels were highly correlated with plasma cholesterol levels. The results indicate that hepatic CETP gene expression is driven by a mechanism which senses changes in plasma cholesterol levels independent of apo E and LDL receptors. Hepatic sterol-sensitive genes have mechanisms to sense hypercholesterolemia that do not require classical receptor-mediated lipoprotein uptake. PMID:8550828

  1. Direct effects of fatty meals and adiposity on oxidised low-density lipoprotein.

    PubMed

    Laguna-Camacho, Antonio; Alonso-Barreto, Arely S; Mendieta-Zerón, Hugo

    2015-01-01

    High-fat intake and high adiposity contribute to hyperlipaemia. In a hyperlipaemic state, lipoproteins infiltrate arterial wall where they are modified and cause an immune response characteristic of atherosclerosis. A small fraction of modified lipoproteins including oxidised low-density lipoprotein (ox-LDL) returns to circulation. The present study tracked high-fat meals during four weeks as to find effects of sustained frequency change on adiposity and ox-LDL. The findings indicated that changes in frequency of consumption of high-fat eating episodes correlated directly with changes in adiposity and ox-LDL. Hence the number of fatty meals consumed by people with overweight or obesity in few weeks could affect the atherogenic process.

  2. KIF6, LPA, TAS2R50, and VAMP8 genetic variation, low density lipoprotein cholesterol lowering response to pravastatin, and heart disease risk reduction in the elderly

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Single nucleotide polymorphisms (SNPs) at the KIF6 (kinesin like protein 6, rs20455 or 719Arg), LPA (lipoprotein(a), rs3798220), TAS2R50 (taste receptor type 2, member 50, rs1376251) and VAMP8 (vesicle-associated membrane protein 8, rs1010) have previously been associated with low density lipoprotei...

  3. [Very low density lipoproteins and subclasses of intermediate density lipoproteins in postmenopausal women].

    PubMed

    Berg, G; Halperín, H; Siseles, N; Wikinski, R

    1996-01-01

    Post menopausal women present an increase of cardiovascular risk associated with the atherogenic plasma lipoproteins IDL and LDL. Our purpose was to study the composition of VLDL, IDL and the subfractions IDL-1 and IDL-2, and the Lipoprotein Lipase and Hepatic Lipase activities in a group of twelve healthy post menopausal women as compared with eleven fertile controls. The mean values of total cholesterol and LDL cholesterol were significantly increased in the post menopausal group compared to the controls (p < 0.005 and p < 0.001 respectively). The contribution of the HDL-cholesterol plasma concentration to total cholesterol was lower in the postmenopausal women (p < 0.02) although no one had HDL-cholesterol lower than 35 mg/dl and the mean value was 50 mg/dl. Postmenopausal women had increased concentrations of VLDL, total IDL and IDL-2 compared to controls (p < 0.05, p < 0.005 and p < 0.001 respectively). Plasma concentrations of total IDL was increased in postmenopausal women (33.6 +/- 3.4 vs 22.6 +/- 0.8 mg/dl, p < 0.005). The increase in total IDL was due to IDL-2 (19.9 +/- 1.7 vs 11.5 +/- 0.8 mg/dl, p < 0.001, in postmenopausal women vs controls). The IDL-2 subfraction was 60 +/- 2.6% of total IDL in postmenopausal women and 51 +/- 2.0% in controls (p < 0.02). In postmenopausal women and in controls the ratio triglyceride/protein (which indicates particles size) was significantly higher in IDL-1 than in IDL-2 (p < 0.005 and p < 0.01 respectively), but this ratio did not show differences when VLDL, total IDL and IDL-2 were compared between postmenopausal and control women. Then, the increased plasma concentration of these lipoproteins would show an increased number of particles in the postmenopausal women vs controls. There were no differences in the Lipoprotein Lipase and Hepatic Lipase activities between both groups. Lipoprotein Lipase vs total IDL-triglycerides and IDL-2-triglycerides showed a significant inverse correlation in controls (p < 0.05) but not

  4. Oxidized low-density lipoprotein is associated with advanced-stage prostate cancer.

    PubMed

    Wan, Fangning; Qin, Xiaojian; Zhang, Guiming; Lu, Xiaolin; Zhu, Yao; Zhang, Hailiang; Dai, Bo; Shi, Guohai; Ye, Dingwei

    2015-05-01

    Clinical and epidemiological data suggest coronary artery disease shares etiology with prostate cancer (PCa). The aim of this work was to assess the effects of several serum markers reported in cardiovascular disease on PCa. Serum markers (oxidized low-density lipoprotein [ox-LDL], apolipoprotein [apo] B100, and apoB48) in peripheral blood samples from 50 patients from Fudan University Shanghai Cancer Center (FUSCC) with localized or lymph node metastatic PCa were investigated in this study. Twenty-five samples from normal individuals were set as controls. We first conducted enzyme-linked immunosorbent assay analysis to select candidate markers that were significantly different between these patients and controls. Then, the clinical relevance between OLR1 (the ox-LDL receptor) expression and PCa was analyzed in The Cancer Genome Atlas (TCGA) cohort. We also investigated the function of ox-LDL in PCa cell lines in vitro. Phosphorylation protein chips were used to analyze cell signaling pathways in ox-LDL-treated PC-3 cells. The ox-LDL level was found to be significantly correlated with N stage of prostate cancer. OLR1 expression was correlated with lymph node metastasis in the TCGA cohort. In vitro, ox-LDL stimulated the proliferation, migration, and invasion of LNCaP and PC-3 in a dose-dependent manner. The results of phosphoprotein microarray illustrated that ox-LDL could influence multiple signaling pathways of PC-3. Activation of proliferation promoting signaling pathways (including β-catenin, cMyc, NF-κB, STAT1, STAT3) as well as apoptosis-associating signaling pathways (including p27, caspase-3) demonstrated that ox-LDL had complicated effects on prostate cancer. Increased serum ox-LDL level and OLR1 expression may indicate advanced-stage PCa and lymph node metastasis. Moreover, ox-LDL could stimulate PCa proliferation, migration, and invasion in vitro.

  5. CD36 binds oxidized low density lipoprotein (LDL) in a mechanism dependent upon fatty acid binding.

    PubMed

    Jay, Anthony G; Chen, Alexander N; Paz, Miguel A; Hung, Justin P; Hamilton, James A

    2015-02-20

    The association of unesterified fatty acid (FA) with the scavenger receptor CD36 has been actively researched, with focuses on FA and oxidized low density lipoprotein (oxLDL) uptake. CD36 has been shown to bind FA, but this interaction has been poorly characterized to date. To gain new insights into the physiological relevance of binding of FA to CD36, we characterized FA binding to the ectodomain of CD36 by the biophysical method surface plasmon resonance. Five structurally distinct FAs (saturated, monounsaturated (cis and trans), polyunsaturated, and oxidized) were pulsed across surface plasmon resonance channels, generating association and dissociation binding curves. Except for the oxidized FA HODE, all FAs bound to CD36, with rapid association and dissociation kinetics similar to HSA. Next, to elucidate the role that each FA might play in CD36-mediated oxLDL uptake, we used a fluorescent oxLDL (Dii-oxLDL) live cell assay with confocal microscopy imaging. CD36-mediated uptake in serum-free medium was very low but greatly increased when serum was present. The addition of exogenous FA in serum-free medium increased oxLDL binding and uptake to levels found with serum and affected CD36 plasma membrane distribution. Binding/uptake of oxLDL was dependent upon the FA dose, except for docosahexaenoic acid, which exhibited binding to CD36 but did not activate the uptake of oxLDL. HODE also did not affect oxLDL uptake. High affinity FA binding to CD36 and the effects of each FA on oxLDL uptake have important implications for protein conformation, binding of other ligands, functional properties of CD36, and high plasma FA levels in obesity and type 2 diabetes.

  6. [Study on the selective removal of plasma low-density lipoprotein and fibrinogen by degraded carrageenan].

    PubMed

    Cong, Haixia; Yin, Liang; Fang, Bo; Du, Longbing; Zhao, Hui; Chen, Jingling; You, Chao

    2010-08-01

    The selective removal of low density lipoprotein (LDL) and fibrinogen (Fib) by degraded carrageenan was studied by the present authors. Degraded carrageenan was prepared by acid with carrageenan as the main material. The effects of acid conditions on the molecular weight were investigated, and the proper reaction conditions were ascertained. The results of infrared spectrometry indicated that the degraded carrageenan is a heparin-like polysaccharide. Then the selective removal of LDL/Fibrinogen by degraded carrageenan was studied. When molecular weight was about 10,000, pH was 5.10 and the concentration of degraded carrageenan was 800 mg/L, the average reduction percentages were 60.0% for total cholesterol(TC), 79.4% for LDL and very low-density lipoprotein (VLDL), and 93.8% for fibrinogen. There were no significant changes with relation to the level of high-density lipoprotein (HDL) and total protein (TP). So, degraded carrageenan was shown to be of good selectivity on plasma LDL/Fibrinogen apheresis.

  7. Practical technique to quantify small, dense low-density lipoprotein cholesterol using dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Trirongjitmoah, Suchin; Iinaga, Kazuya; Sakurai, Toshihiro; Chiba, Hitoshi; Sriyudthsak, Mana; Shimizu, Koichi

    2016-04-01

    Quantification of small, dense low-density lipoprotein (sdLDL) cholesterol is clinically significant. We propose a practical technique to estimate the amount of sdLDL cholesterol using dynamic light scattering (DLS). An analytical solution in a closed form has newly been obtained to estimate the weight fraction of one species of scatterers in the DLS measurement of two species of scatterers. Using this solution, we can quantify the sdLDL cholesterol amount from the amounts of the low-density lipoprotein cholesterol and the high-density lipoprotein (HDL) cholesterol, which are commonly obtained through clinical tests. The accuracy of the proposed technique was confirmed experimentally using latex spheres with known size distributions. The applicability of the proposed technique was examined using samples of human blood serum. The possibility of estimating the sdLDL amount using the HDL data was demonstrated. These results suggest that the quantitative estimation of sdLDL amounts using DLS is feasible for point-of-care testing in clinical practice.

  8. Severe osteoporosis with multiple spontaneous vertebral fractures in a young male carrying triple polymorphisms in the vitamin D receptor, collagen type 1, and low-density lipoprotein receptor-related peptide 5 genes.

    PubMed

    Yavropoulou, Maria P; Kollia, Panagoulia; Chatzidimitriou, Dimitris; Samara, Stavroula; Skoura, Lemonia; Yovos, John G

    2016-10-01

    Osteoporosis is a common disease with a strong genetic component. Several studies have reported the vitamin D receptor (VDR), collagen type I (COL1A1), and LDL receptor-related protein 5 (LRP5) genes as the most likely candidates. However, most of the studies have been carried out in postmenopausal women and older men and show inconsistent results.

  9. Ceruloplasmin as low-density lipoprotein oxidase: activation by ascorbate and dehydroascorbate.

    PubMed

    Feichtenhofer, S; Fabjan, J S; Abuja, P M

    2001-07-13

    The ability of ceruloplasmin (Cp) to oxidize low-density lipoproteins (LDL) in the presence of water-soluble antioxidants was investigated and a reaction mechanism proposed. Ascorbate strongly enhanced LDL oxidation, but only after its rapid consumption. Dehydroascorbate enhanced Cp-mediated LDL oxidation even more strongly. Lipid-soluble antioxidants and water-soluble peroxides did not show noticeable activation. However, loading of LDL with lipid hydroperoxides increased the initial oxidation rate. We conclude that Cp mediates a localized redox cycle, where reduction of Cp-Cu2+ is effected by water-soluble reductants and reoxidation by liposoluble hydroperoxides.

  10. Mechanisms of metal ion-dependent oxidation of human low density lipoprotein.

    PubMed

    Lynch, S M; Frei, B

    1996-04-01

    Although either copper or iron is essential for oxidation of human low density lipoprotein (LDL) by vascular cells, the mechanism is unknown. In our experiments copper- and iron-mediated LDL oxidation was found to proceed by different mechanisms. Oxidation of LDL by iron requires superoxide and proceeds by a hydroxyl radical-independent mechanism involving reduction of iron from the ferric to the ferrous form. In contrast, copper-mediated LDL oxidation involves direct reduction of copper from the cupric to the cuprous form by LDL.

  11. Umbilical Cord Blood Transplantation-associated Nephrotic Syndrome Successfully Treated by Low-density Lipoprotein Apheresis

    PubMed Central

    Sugawara, Yuka; Honda, Kenjiro; Katagiri, Daisuke; Nakamura, Motonobu; Kawakami, Takahisa; Nasu, Ryo; Hayashi, Akimasa; Shintani, Yukako; Tojo, Akihiro; Noiri, Eisei; Kurokawa, Mineo; Fukayama, Masashi; Nangaku, Masaomi

    2016-01-01

    The development of nephrotic syndrome (NS) after umbilical cord transplantation (UBT) has been reported in only four cases to date. We herein report the case of a 50-year-old woman who developed NS 94 days after UBT. She fell into oliguria and required dialysis. A kidney biopsy revealed focal and segmental glomerulosclerosis. Although glucocorticoid monotherapy did not improve her condition, the addition of low-density lipoprotein (LDL) apheresis resulted in remission of NS, a drastic improvement in her renal function, and withdrawal from dialysis. To the best of our knowledge, this is the first report of UBT-associated NS treated with LDL apheresis. PMID:27725544

  12. Ascorbic acid protects lipids in human plasma and low-density lipoprotein against oxidative damage

    SciTech Connect

    Frei, B. )

    1991-12-01

    The authors exposed human blood plasma and low-density lipoprotein (LDL) to many different oxidative challenges and followed the temporal consumption of endogenous antioxidants in relation to the initiation of oxidative damage. Under all types of oxidizing conditions, ascorbic acid completely protects lipids in plasma and LDL against detectable peroxidative damage as assessed by a specific and highly sensitive assay for lipid peroxidation. Ascorbic acid proved to be superior to the other water-soluble plasma antioxidants bilirubin, uric acid, and protein thiols as well as to the lipoprotein-associated antioxidants alpha-tocopherol, ubiquinol-10, lycopene, and beta-carotene. Although these antioxidants can lower the rate of detectable lipid peroxidation, they are not able to prevent its initiation. Only ascorbic acid is reactive enough to effectively intercept oxidants in the aqueous phase before they can attack and cause detectable oxidative damage to lipids.

  13. Monoclonal antibodies to human plasma low-density lipoproteins. I. Enhanced binding of 125I-labeled low-density lipoproteins by combined use of two monoclonal antibodies.

    PubMed

    Mao, S J; Patton, J G; Badimon, J J; Kottke, B A; Alley, M C; Cardin, A D

    1983-11-01

    Four monoclonal antibodies (IgG2b) to human plasma low-density lipoproteins (LDL) have been characterized. The binding affinities of each monoclonal antibody to 125I-labeled LDL were moderately high, ranging from 10(8) to 10(10) L/mol at 4 degrees C, but were reduced by at least 50-70% at 37 degrees C. The maximum binding of each monoclonal antibody was unique, ranging from 20 to 95% of total 125I-labeled LDL, suggesting that LDL particles were immunochemically heterogeneous. One antibody, LP-34, had both high and low binding affinities to LDL. Another, LP-47, exhibited high affinity for isolated LDL, yet reacted poorly with native LDL in plasma, indicating that the conformation of isolated LDL differs from that of native LDL in plasma. Unlike polyclonal serum antibodies, a mixture of four monoclonal antibodies failed to precipitate LDL, but did show a drastic increase in binding to LDL. We found that only two of our monoclonal antibodies were necessary for such synergistic enhancement. We propose that one of the monoclonal antibodies may serve as a catalytic reagent, and discuss the clinical significance of this finding.

  14. Activation of 15-lipoxygenase by low density lipoprotein in vascular endothelial cells. Relationship to the oxidative modification of low density lipoprotein.

    PubMed

    Derian, C K; Lewis, D F

    1992-01-01

    Oxidatively-modified low density lipoprotein (LDL) is thought to play a significant role in the formation of lipid-laden macrophages, the primary cellular component of atherosclerotic fatty lesions. Recently, lipoxygenases have been implicated as a major enzymatic pathway involved in rabbit endothelial cell-mediated LDL modification. We investigated the effect of LDL on porcine aortic endothelial cell (PAEC) and human umbilical vein (HUVEC) and aortic endothelial cell (HAEC) lipoxygenase activity. By thin layer chromatography, we observed that human LDL stimulated the metabolism of radiolabeled arachidonic acid to 12 + 15-hydroxyeicosatetraenoic acid (HETE) in indomethacin-treated PAEC. Furthermore, radiolabeled linoleic acid, a specific substrate for the 15-lipoxygenase, was metabolized to its respective product 13-hydroxyoctadecadienoic acid (13-HODE) in the presence of LDL. Increased product formation in both studies was inhibited by the lipoxygenase blockers nordihydroguaiaretic acid (NDGA) and RG 6866. 15-HETE was confirmed as the predominant HETE product in LDL-treated cells by high performance liquid chromatography. Both porcine- and human-derived LDL stimulated the CL release of 15-HETE from cells as determined by radioimmunoassay. Release of immunoreactive 15-HETE was inhibited by NDGA, RG 6866, and 5,8,11,14-eicosatetraynoic acid (ETYA) but not by the selective 5-lipoxygenase inhibitor RG 5901. These lipoxygenase inhibitors had similar effects on the modification of LDL. Our results suggest that the oxidative modification of LDL by endothelial cells may be mediated in part through activation of 15-lipoxygenase.

  15. In vitro incorporation of radiolabeled cholesteryl esters into high and low density lipoproteins

    SciTech Connect

    Terpstra, A.H.; Nicolosi, R.J.; Herbert, P.N. )

    1989-11-01

    We have developed and validated a method for in vitro incorporation of radiolabeled cholesteryl esters into low density (LDL) and high density lipoproteins (HDL). Radiolabeled cholesteryl esters dissolved in absolute ethanol were mixed with LDL or HDL in the presence of lipoprotein-deficient serum (LPDS) as a source of core lipid transfer activity. The efficiency of incorporation was dependent on: (a) the core lipid transfer activity and quantity of LPDS, (b) the mass of added radiolabeled cholesteryl esters, (c) the length of incubation, and (d) the amount of acceptor lipoprotein cholesterol. The tracer incorporation was documented by repeat density gradient ultracentrifugation, agarose gel electrophoresis, and precipitation with heparin-MnCl2. The radiolabeling conditions did not affect the following properties of the lipoproteins: (1) chemical composition, (2) electrophoretic mobility on agarose gels, (3) hydrated density, (4) distribution of apoproteins on SDS gels, (5) plasma clearance rates, and (6) immunoprecipitability of HDL apoproteins A-I and A-II. Rat HDL containing radiolabeled cholesteryl esters incorporated in vitro had plasma disappearance rates identical to HDL radiolabeled in vivo.

  16. Synthetic low-density lipoprotein (sLDL) selectively delivers paclitaxel to tumor with low systemic toxicity

    PubMed Central

    Su, Hai-Tao; Li, Xin; Liang, De-Sheng; Qi, Xian-Rong

    2016-01-01

    Low density lipoprotein (LDL), which is a principal carrier for the delivery of cholesterol, has been used as a great candidate for the delivery of drugs to tumor based on the great requirements for cholesterol of many cancer cells. Mimicking the structure and composition of LDL, we designed a synthetic low-density lipoprotein (sLDL) to encapsulate paclitaxel-alpha linolenic acid (PALA) for tumor therapy. The PALA loaded sLDL (PALA-sLDL) and PALA-loaded microemulsion (PALA-ME, without the binding domain for LDLR) displayed uniform sizes with high drug loading efficiency (> 90%). In vitro studies demonstrated PALA-sLDL exhibited enhanced cellular uptake capacity and better cytotoxicity to LDLR over-expressed U87 MG cells as compared to PALA-ME. The uptake mechanisms of PALA-sLDL were involved in a receptor mediated endocytosis and macropinocytosis. Furthermore, the in vivo biodistribution and tumor growth inhibition studies of PALA-sLDL were investigated in xenograft U87 MG tumor-bearing mice. The results showed that PALA-sLDL exhibited higher tumor accumulation than PALA-ME and superior tumor inhibition efficiency (72.1%) compared to Taxol® (51.2%) and PALA-ME (58.8%) but with lower toxicity. These studies suggested that sLDL is potential to be used as a valuable carrier for the selective delivery of anticancer drugs to tumor with low systemic toxicity. PMID:27409176

  17. Lowering low-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus

    PubMed Central

    Bays, Harold E

    2014-01-01

    Type 2 diabetes mellitus (T2DM) is characterized by hyperglycemia, insulin resistance, and/or progressive loss of β-cell function. T2DM patients are at increased risk of micro- and macrovascular disease, and are often considered as representing an atherosclerotic coronary heart disease (CHD) risk equivalent. Interventions directed at glucose and lipid level control in T2DM patients may reduce micro- and macrovascular disease. The optimal T2DM agent is one that lowers glucose levels with limited risk for hypoglycemia, and with no clinical trial evidence of worsening CHD risk. Lipid-altering drugs should preferably reduce low-density lipoprotein cholesterol and apolipoprotein B (apo B) and have evidence that the mechanism of action reduces CHD risk. Statins reduce low-density lipoprotein cholesterol and apo B and have evidence of improving CHD outcomes, and are thus first-line therapy for the treatment of hypercholesterolemia. In patients who do not achieve optimal lipid levels with statin therapy, or who are intolerant to statin therapy, add-on therapy or alternative therapies may be indicated. Additional available agents to treat hypercholesterolemic patients with T2DM include bile acid sequestrants, fibrates, niacin, and ezetimibe. This review discusses the use of these alternative agents to treat hypercholesterolemia in patients with T2DM, either as monotherapy or in combination with statin therapy. PMID:25045281

  18. Optimal Low-Density Lipoprotein Cholesterol for Cardiovascular Prevention: How Low Should We Go?

    PubMed

    Anderson, Todd J

    2017-03-01

    The treatment of dyslipidemia with lifestyle interventions and statin-based therapy has been an important defense against atherosclerotic cardiovascular disease and its complications. It has been well documented for more than 2 decades that 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors (statins) reduce the risk of events. The evolution of drug development and randomized clinical trials in cardiovascular medicine has resulted in the conclusion that lower cholesterol concentrations result in greater benefit. However, how aggressive one should be in lowering cholesterol levels and to what level has not been definitively established. In this brief review I aim to defend the hypothesis that lower is better on the basis of the evidence to date. This will include indirect evidence from randomized clinical trials with statins and novel lipid-modifying drugs. In addition, there is a wealth of epidemiology and Mendelian randomization genetic data to support this. Also, on-treatment low-density lipoprotein cholesterol concentrations show a robust relationship with cardiovascular disease events. Finally, most national guidelines groups around the world continue to advocate for a treat to target philosophy. As such, the prevailing philosophy is that lowering low-density lipoprotein cholesterol to very low levels is our best preventative strategy particularly for those at the highest risk. We eagerly await the results of ongoing clinical trials that will more firmly establish if this concept will ultimately be proven correct.

  19. Evaluation of bacteriochlorophyll-reconstituted low-density lipoprotein nanoparticles for photodynamic therapy efficacy in vivo

    PubMed Central

    Marotta, Diane E; Cao, Weiguo; Wileyto, E Paul; Li, Hui; Corbin, Ian; Rickter, Elizabeth; Glickson, Jerry D; Chance, Britton; Zheng, Gang; Busch, Theresa M

    2011-01-01

    Aim To evaluate the novel nanoparticle reconstituted bacteriochlorin e6 bisoleate low-density lipoprotein (r-Bchl-BOA-LDL) for its efficacy as a photodynamic therapy agent delivery system in xenografts of human hepatoblastoma G2 (HepG2) tumors. Materials & methods Bchl-BOA was encapsulated in the nanoparticle low-density lipoprotein (LDL), a native particle whose receptor’s overexpression is a cancer signature for a number of neoplasms. Evaluation of r-Bchl-BOA-LDL as a potential photosensitizer was performed using a tumor response and foot response assay. Results & discussion When compared with controls, tumor regrowth was significantly delayed at injected murine doses of 2 µmole/kg r-Bchl-BOA-LDL after illumination at fluences of 125, 150 or 175 J/cm2. Foot response assays showed that although normal tissue toxicity accompanied the higher fluences it was significantly reduced at the lowest fluence tested. Conclusion This research demonstrates that r-Bchl-BOA-LDL is an effective photosensitizer and a promising candidate for further investigation. PMID:21542686

  20. Protective effects of endomorphins, endogenous opioid peptides in the brain, on human low density lipoprotein oxidation.

    PubMed

    Lin, Xin; Xue, Li-Ying; Wang, Rui; Zhao, Qian-Yu; Chen, Qiang

    2006-03-01

    Neurodegenerative disorders are associated with oxidative stress. Low density lipoprotein (LDL) exists in the brain and is especially sensitive to oxidative damage. Oxidative modification of LDL has been implicated in the pathogenesis of neurodegenerative diseases. Therefore, protecting LDL from oxidation may be essential in the brain. The antioxidative effects of endomorphin 1 (EM1) and endomorphin 2 (EM2), endogenous opioid peptides in the brain, on LDL oxidation has been investigated in vitro. The peroxidation was initiated by either copper ions or a water-soluble initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). Oxidation of the LDL lipid moiety was monitored by measuring conjugated dienes, thiobarbituric acid reactive substances, and the relative electrophoretic mobility. Low density lipoprotein oxidative modifications were assessed by evaluating apoB carbonylation and fragmentation. Endomorphins markedly and in a concentration-dependent manner inhibited Cu2+ and AAPH induced the oxidation of LDL, due to the free radical scavenging effects of endomorphins. In all assay systems, EM1 was more potent than EM2 and l-glutathione, a major intracellular water-soluble antioxidant. We propose that endomorphins provide protection against free radical-induced neurodegenerative disorders.

  1. Immunoregulation by low density lipoproteins in man. Inhibition of mitogen-induced T lymphocyte proliferation by interference with transferrin metabolism.

    PubMed Central

    Cuthbert, J A; Lipsky, P E

    1984-01-01

    Human low density lipoprotein (LDL, d = 1.020-1.050 g/ml) inhibits mitogen-stimulated T lymphocyte DNA synthesis. Because both LDL and transferrin bind to specific cell surface receptors and enter cells by the similar means of receptor-mediated endocytosis, and because transferrin is necessary for lymphocyte DNA synthesis, we investigated the possibility that LDL may inhibit mitogen-stimulated lymphocyte responses by interfering with transferrin metabolism. LDL inhibited mitogen-stimulated lymphocyte [3H]thymidine incorporation in a concentration-dependent manner. The degree of inhibition was most marked in serum-free cultures, but was also observed in serum-containing cultures. The addition of transferrin not only augmented mitogen-induced lymphocyte [3H]thymidine incorporation in serum-free medium but also completely reversed the inhibitory effect of LDL in both serum-free and serum-containing media. Similar results were obtained when lymphocyte proliferation was assayed by counting the number of cells in culture. Transferrin also reversed the inhibition of lymphocyte responses caused by very low density lipoproteins and by cholesterol. The ability of transferrin to reverse the inhibitory effect of lipoproteins was specific, in that native but not denatured transferrin was effective whereas a variety of other proteins were ineffective. These results indicate that LDL inhibits mitogen-stimulated lymphocyte responses by interfering with transferrin metabolism. LDL only inhibited lymphocyte responses after a 48-h incubation if present from the initiation of the culture. By contrast, transferrin reversed inhibition when added after 24 h of the 48-h incubation. LDL did not inhibit lymphocyte responses by nonspecifically associating with transferrin. In addition, the acquisition of specific lymphocyte transferrin receptors was not blocked by LDL. Moreover, transferrin did not prevent the binding and uptake of fluorescent-labeled LDL by activated lymphocytes

  2. Low density lipoprotein apheresis in pediatric patients with homozygous familial hypercholesterolemia.

    PubMed

    Coker, Mahmut; Ucar, Sema Kalkan; Simsek, Damla Goksen; Darcan, Sukran; Bak, Mustafa; Can, Sule

    2009-04-01

    The aim of the present study is to clarify the low density lipoprotein apheresis procedure for pediatric patients with homozygous familial hypercholesterolemia (FH) in terms of efficacy, adverse effects and difficulties. The follow-up was carried out using an open, prospective uncontrolled clinical design. Data were collected from 10 patients (with an average age of 8.4 +/- 4.7 years) with FH treated with double filtration plasmapheresis. The total time span of follow-up covered five years (30.2 +/- 17.8 months [range 9-60 months]) and more than 600 sessions (62.1 +/- 35.5 sessions per patient [range 18-120 sessions]) were evaluated. The mean low density lipoprotein cholesterol (LDL-C) pre-treatment value was 375.5 +/- 127.5 mg/dL, and the post-treatment value was 147.5 +/- 73.9 mg/dL. This corresponded to a 62.8 +/- 10.3% (43-73%) acute reduction of LDL-C, while the mean high density lipoprotein cholesterol losses amounted to 41%. The chronic reduction in LDL-C ranged from 18 to 52%, with a mean level of 36.4 +/- 11.7%. The most frequently occurring technical problems were related to blood lines: puncture difficulties (4.5%), insufficient blood flow (3.5%), and obturation of the blood lines (2.4%). The main clinical adverse effects were hypotension (0.2%), chills/feeling cold (0.1%), and nausea and vomiting (0.2%). We observed that the low pediatric patient tolerance is the main problem in compliance with treatment. In conclusion, LDL apheresis, started under the age of eight years, combined with lipid-lowering drugs, provides a safe and effective lowering of the mean LDL-C levels in pediatric homozygous FH; and there are more problems with compliance for pediatric LDL apheresis than in the adult population.

  3. Anti-oxidized low-density lipoprotein antibodies in myeloperoxidase–positive vasculitis patients preferentially recognize hypochlorite-modified low density lipoproteins

    PubMed Central

    Slot, M C; Theunissen, R; van Paassen, P; Damoiseaux, J G M C; Cohen Tervaert, J W

    2007-01-01

    Many patients surviving vasculitis are prone to accelerated atherosclerosis and often have enhanced levels of antibodies to oxidized low-density lipoprotein (oxLDL). To measure anti-oxLDL antibodies, oxidation of LDL is achieved with copper (Cu) or malondialdehyde (MDA). Because, in vivo, LDL may be oxidized with myeloperoxidase (MPO) or its product hypochlorite, we measured anti-hypochlorite LDL antibodies in patients with vasculitis, haemodialysis patients and healthy controls. A newly developed enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to oxLDL as modified by hypochlorite. Results are compared with data obtained by standard LDL oxidation using MDA–LDL or Cu–LDL as substrate. Results were compared between anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients (n = 93), haemodialysis (HD) patients (n = 59) and healthy controls (HC; n = 43). Furthermore, patients with MPO–ANCA-associated vasculitis (n = 47) were compared with patients with proteinase 3 (PR3)–ANCA associated vasculitis (n = 46). Optimal cut-off points were determined by receiver operator characteristic (ROC) curve analysis. Anti-oxLDL antibodies are enhanced in AAV patients (MDA–LDL and hypochlorite–LDL) and in HD patients (hypochlorite–LDL), when compared to HC. Furthermore, patients with MPO–ANCA-associated vasculitis had higher levels of antibodies to hypochlorite–LDL than patients with PR3–ANCA-associated vasculitis. Our newly developed assay, in which hypochlorite–LDL is used as substrate, seems a more sensitive assay than traditional assays to measure oxLDL antibodies. Furthermore, our results suggest that enhanced MPO-mediated LDL oxidation occurs in patients with MPO–ANCA. PMID:17521320

  4. Correlation of Friedewald's calculated low-density lipoprotein cholesterol levels with direct low-density lipoprotein cholesterol levels in a tertiary care hospital

    PubMed Central

    Nanda, Sunil Kumar; Bharathy, M; Dinakaran, Asha; Ray, Lopamudra; Ravichandran, K

    2017-01-01

    Background: One of the risk factors for the development of coronary heart disease is high low-density lipoprotein (LDL) cholesterol levels. National Cholesterol Education Program ATP III guidelines suggest drug therapy to be considered at LDL-cholesterol levels >130 mg/dl. This makes accurate reporting of LDL cholesterol crucial in the management of Coronary heart disease. Estimation of LDL cholesterol by direct LDL method is accurate, but it is expensive. Hence, We compared Friedewald's calculated LDL values with direct LDL values. Aim: To evaluate the correlation of Friedewalds calculated LDL with direct LDL method. Materials and Methods: We compared LDL cholesterol measured by Friedewald's formula with direct LDL method in 248 samples between the age group of 20–70 years. Paired t-test was used to test the difference in LDL concentration obtained by a direct method and Friedewald's formula. The level of significance was taken as P < 0.05. Pearsons correlation formula was used to test the correlation between direct LDL values with Friedewald's formula. Results: There was no significant difference between the direct LDL values when compared to calculated LDL by Friedewalds formula (P = 0.140). Pearson correlation showed there exists good correlation between direct LDL versus Friedewalds formula (correlation coefficient = 0.98). The correlation between direct LDL versus Friedewalds calculated LDL was best at triglycerides values between 101 and 200 mg/dl. Conclusion: This study indicates calculated LDL by Friedewalds equation can be used instead of direct LDL in patients who cannot afford direct LDL method. PMID:28251110

  5. Low-density lipoprotein oxidation and its prevention by amidothionophosphate antioxidants.

    PubMed

    Tirosh, O; Katzhendler, J; Barenholz, Y; Kohen, R

    1999-01-01

    Amidothionophosphates (AMTPs) are a novel group of antioxidants that are lacking in pro-oxidant activity. In this paper, we compare two different amidothionophosphates: 2-hydroxy-ethyl amido, diethyl thionophosphate (AMTP-B), which contains a single primary amido group, and N,N',N-tripropylamidothionophosphate (AMTP-3A), which contains three primary amido groups. The lipoprotein/medium partition coefficients of AMTP-3A and AMTP-B are 74 and 38, respectively. Both protected isolated human low density lipoprotein (LDL) against oxidative damage induced by copper sulfate. Oxidative damage to polyunsaturated acyl chains was determined by gas chromatography (GC), and oxidation kinetics were monitored by following the accumulation of conjugated dienes spectrophotometrically at 234 nm. The AMTP antioxidants significantly protected the LDL against Cu2+-induced oxidation. However, if the LDLs were already partially oxidized, protection against oxidation by the AMTPs was reduced. AMTP-3A was more effective in protecting LDL than was AMTP-B. The difference in antioxidant activity was attributed to the 15-fold higher reactivity of AMTP-3A toward peroxides. Oxidizability of plasma lipoproteins from guinea pigs injected with AMTPs was strongly reduced.

  6. Enhanced detection of lipid transfer inhibitor protein activity by an assay involving only low density lipoprotein.

    PubMed

    Morton, R E; Greene, D J

    1994-11-01

    Lipid transfer inhibitor protein (LTIP) activity has been typically quantitated by its ability to suppress lipid transfer protein-mediated lipid movement between low density lipoprotein (LDL) and high density lipoprotein (HDL). In an attempt to establish an LTIP activity assay that is more sensitive, we have exploited the reported preference of the inhibitor protein to interact with LDL. A lipid transfer assay was established that involves LDL as both the donor and the acceptor; LDL in one of these two pools was biotinylated to facilitate its removal with immobilized avidin. Compared to the standard LDL to HDL assay, LTIP inhibited lipid transfer from radiolabeled LDL to biotin-LDL 7-fold more. In the absence of LTIP, lipid transfer activity was the same in both assays. An added benefit of this assay was the near linearity (up to 85%) of the inhibitory response, in contrast to the highly curvilinear response of LTIP in LDL to HDL transfer assays. The high sensitivity of the LDL to biotin-LDL transfer assay in measuring LTIP activity could not be duplicated by other transfer assays including assays containing only HDL (HDL to biotin-HDL), assays between liposomes and LDL, or assays between LDL and HDL where the concentration of lipoproteins was reduced 10-fold. Thus, LTIP activity is most effectively measured in homologous lipid transfer assays involving only LDL (and its biotin derivative). This increased sensitivity to LTIP suggests that the inhibitor binds more avidly to the LDL surface than does lipid transfer protein.

  7. Lipoprotein lipase, LDL receptors and apo-lipoproteins in human fetal membranes at term.

    PubMed

    Huter, O; Wolf, H J; Schnetzer, A; Pfaller, K

    1997-11-01

    Ultrastructurally, all cells of human fetal membranes strongly exhibit a large amount of lipid deposits throughout pregnancy. Their origin and function is still unknown. The aim of this study was to investigate the localization of key components of lipid metabolism in this tissue. Using immunohistochemical techniques, the distribution of lipoprotein lipase (LPL), low density lipoprotein receptors (LDL receptors), and apo-lipoprotein B and E was investigated in 20 human fetal membranes at term. In addition, electron microscopy was used to study the intracellular localization of lipoprotein-sized particles. Amnionic epithelium and trophoblast cells reacted strongly for LPL. LDL receptors and apo-lipoproteins were present in amnionic epithelium and fibroblasts of the amnion. In none of the investigated cells were lipoprotein-sized particles identified. Similar results were obtained in all 20 cases. The findings indicate that lipoprotein from the amniotic fluid or from the maternal circulation may serve as substrate for lipids in human fetal membranes.

  8. Very low density lipoproteins in intestinal lymph: role in triglyceride and cholesterol transport during fat absorption

    PubMed Central

    Ockner, Robert K.; Hughes, Faith B.; Isselbacher, Kurt J.

    1969-01-01

    The role of nonchylomicron very low density lipoproteins (VLDL, Sf 20-400) in the transport of triglyceride and cholesterol was studied during lipid absorption. Various long chain fatty acids were infused intraduodenally in the form of mixed fatty acid—mono-olein-taurocholate micelles; control animals received saline or taurocholate. As compared with controls, all fatty acids (palmitic, oleic, linoleic) resulted in significant increases in chylomicron (Sf > 400) triglyceride. In addition, palmitic acid resulted in a twofold increase in VLDL triglyceride, whereas with the absorption of oleic or linoleic acid VLDL triglyceride did not change significantly. Differences in triglyceride fatty acid composition between chylomicrons and VLDL were observed during lipid absorption. Although the absolute amount of endogenous cholesterol in intestinal lymph was not significantly affected by lipid absorption under these conditions, its lipoprotein distribution differed substantially among the lipid-infused groups. During palmitate absorption, VLDL cholesterol was similar to that in the taurocholate-infused controls, and was equal to chylomicron cholesterol. In contrast, during oleate and linoleate absorption the VLDL cholesterol fell markedly, and was less than half of the chylomicron cholesterol in these groups. The half-time of plasma survival of VLDL cholesterol-14C was found to be twice that of chylomicron cholesterol-14C. These studies demonstrate that dietary long chain fatty acids differ significantly in their effects upon the transport of triglyceride and cholesterol by lipoproteins of rat intestinal lymph. These findings, together with the observed differences in rates of removal of chylomicrons and VLDL from plasma, suggest that variations in lipoprotein production at the intestinal level may be reflected in differences in the subsequent metabolism of absorbed dietary and endogenous lipids. PMID:5355348

  9. Effects of flow on LOX-1 and oxidized low-density lipoprotein interactions in brain endothelial cell cultures.

    PubMed

    Mao, Xiaoou; Xie, Lin; Greenberg, David A

    2015-12-01

    Fluid shear stress and uptake of oxidized low-density lipoprotein (ox-LDL) into the vessel wall both contribute to atherosclerosis, but the relationship between shear stress and ox-LDL uptake is unclear. We examined the effects of flow, induced by orbital rotation of bEnd.3 brain endothelial cell cultures for 1 wk, on ox-LDL receptor (LOX-1) protein expression, ox-LDL uptake and ox-LDL toxicity. Orbitally rotated cultures showed no changes in LOX-1 protein expression, ox-LDL uptake or ox-LDL toxicity, compared to stationary cultures. Flow alone does not modify ox-LDL/LOX-1 signaling in bEnd.3 brain endothelial cells in vitro, suggesting that susceptibility of atheroprone vascular sites to lipid accumulation is not due solely to effects of altered flow on endothelium.

  10. Inhibition of human low-density lipoprotein oxidation in vitro by ginger extracts.

    PubMed

    Gunathilake, K D Prasanna P; Rupasinghe, H P Vasantha

    2014-04-01

    Oxidative modification of low-density lipoprotein (LDL) is thought to play a key role in atherosclerotic plaque formation. Currently, there is a renewed interest in ginger because of its antioxidants and cardioprotective properties. The effects of ethanol, methanol, ethyl acetate, and hexane solvent extracts of ginger and pure major ginger constituents on Cu(2+)-induced oxidation of human LDL in vitro were examined. The LDL oxidation inhibition by ethanol, methanol, ethyl acetate, and hexane extracts of ginger was 71%, 76%, 67%, and 67%, respectively, at their optimum extraction conditions. Inhibition of LDL oxidation by water extracts of ginger, which was prepared by ultrasonic-assisted extraction conditions of 52°C for 15 min, was about 43%. Phenolic bioactives of ginger-6-gingerols, 8-gingerols, 10-gingerols, and 6-shogaol-seem to be strong inhibitors of Cu(+2)-induced LDL oxidation. Overall, ginger extracts, including the water extract possess the antioxidant activities to inhibit human LDL oxidation in vitro.

  11. Edaravone attenuates monocyte adhesion to endothelial cells induced by oxidized low-density lipoprotein.

    PubMed

    Li, Zhijuan; Cheng, Jianxin; Wang, Liping

    2015-10-30

    Oxidized low-density lipoprotein (oxLDL) plays a vital role in recruitment of monocytes to endothelial cells, which is important during early stages of atherosclerosis development. Edaravone, a potent and novel scavenger of free radicals inhibiting hydroxyl radicals, has been clinically used to reduce the neuronal damage following ischemic stroke. In the present study, Edaravone was revealed to markedly reduce oxLDL-induced monocyte adhesion to human umbilical vein endothelial cells (HUVECs). The inhibitory mechanism of Edaravone was associated with suppression of the chemokine MCP-1 and adhesion molecule VCAM-1 and ICAM-1 expression. In addition, luciferase reporter assay results revealed that administration of Edaravone attenuated the increase in NF-κB transcriptional activity induced by oxLDL. Notably, it's also shown that Edaravone treatment blocked oxLDL induced p65 nuclear translocation in HUVECs. Results indicate that Edaravone negatively regulates endothelial inflammation.

  12. Oxidized low-density lipoprotein (Ox-LDL) impacts on erythrocyte viscoelasticity and its molecular mechanism.

    PubMed

    Wang, Xiang; Yang, Li; Liu, Yao; Gao, Wei; Peng, Weiyan; Sung, K-L Paul; Sung, Lanping Amy

    2009-10-16

    The oxidized low-density lipoprotein (Ox-LDL) plays an important role in atherosclerosis, yet it remains unclear if it damages circulating erythrocytes. In this study, erythrocyte deformability and its membrane proteins after Ox-LDL incubations are investigated by micropipette aspiration, thiol radical measurement, and sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Results show that Ox-LDL incubation reduces the erythrocyte deformability, decreases free thiol radical contents in erythrocytes, and induces the cross-linking among membrane proteins. SDS-PAGE analysis reveals a high molecular weight (HMW) complex as well as new bands between spectrins and band 3 and reduced ratios between band 3 and other major membrane skeletal proteins. Analyses indicate that Ox-LDL makes erythrocytes harder to deform through a molecular mechanism by which the oxidation of free thiol radicals forms disulfide bonds among membrane skeletal proteins.

  13. High systemic levels of low-density lipoprotein cholesterol: fuel to the flames in inflammatory osteoarthritis?

    PubMed

    de Munter, Wouter; van der Kraan, Peter M; van den Berg, Wim B; van Lent, Peter L E M

    2016-01-01

    There is increasing evidence that low-density lipoprotein (LDL) cholesterol plays a role in the pathology of OA. Specifically, oxidized LDL (oxLDL), which has been shown to play an essential role during development of atherosclerosis, could be involved in processes such as synovial inflammation, cartilage destruction and bone deformations. OxLDL can activate synovial cells such as macrophages, endothelial cells and synovial fibroblasts, resulting in release of growth factors, MMP and pro-inflammatory cytokines. In this review article, we discuss the role of LDL and oxLDL in OA joint pathology and share our viewpoint of possible mechanisms by which these proteins could influence the development and progression of OA. The proposed theory could provide insight into the aetiopathology of OA and give rise to new potential treatments.

  14. Neutrophil-oxidized low density lipoprotein: generation in and clearance from the plasma.

    PubMed Central

    Görög, P.

    1992-01-01

    The prevailing concept of an extremely rapid disappearance of 'modified' low density lipoprotein (LDL) from the circulation was reinvestigated. Rabbit LDL was 'modified' by homologous activated (phagocytosing) polymorphonuclear leucocytes (PMLN), radiolabelled with a non-degradable ligand (125I-TC-LDL) and injected into rabbits. The plasma half-lives of 'modified' and native LDL were T1/2 = 2.5 and 5.75 h, respectively. Furthermore, the possibility of LDL oxidation in plasma by stimulated PMNL was investigated. Hirudin-anticoagulated human plasma was incubated with unstimulated or stimulated autologous PMNL. Chemiluminometry (reactants with microperoxidase) of the lipid extract of plasma after incubation showed lipid peroxidation to be induced by phagocytosing, but not by quiescent, leucocytes. These findings show that in plasma, stimulated leucocytes can 'modify' LDL and the circulatory half-life of the latter enables its contribution to atherogenesis. PMID:1390195

  15. Low density lipoprotein levels linkage with the periodontal status patients of coronary heart disease

    NASA Astrophysics Data System (ADS)

    Ahmad, Nafisah Ibrahim; Masulili, Sri Lelyati C.; Lessang, Robert; Radi, Basuni

    2017-02-01

    Studies found an association between periodontitis and coronary heart disease (CHD), but relationship between periodontal status CHD patients with LDL (Low Density Lipoprotein) levels, as risk factors for atherosclerosis, has not been studied. Objective: To analyze relationship between LDL and periodontal status CHD. Methods: Periodontal status of 60 CHD, 40 controls were examined (PBI, PPD, CAL) and their blood was taken to assess levels of LDL. Result: Found significant differences LDL (p=0.005), correlation between LDL with PPD (p=0.003) and CAL CHD (p=0.013), and PPD (p=0.001), CAL (p=0.008) non-CHD, but no significant correlation between LDL with PBI CAD (p=0.689) and PBI non-CHD (p=0.320). Conclusion: There is a correlation between the LDL levels with periodontal status.

  16. Antioxidant activity of thiocholesterol on copper-induced oxidation of low-density lipoprotein.

    PubMed

    Tanaka, M; Nakagawa, M

    1995-04-01

    The effect of thiocholesterol (SH-Chol) on the copper-induced in vitro oxidation of low-density lipoprotein (LDL; 1.019 < d < 1.063) was investigated. Among the antioxidants tested, including cysteine, glutathione, 2-mercaptoethanol, dithiothreitol, probucol, thiopalmitic acid, and SH-Chol, SH-Chol was the most effective antioxidant in copper-induced LDL oxidation. Also, SH-Chol completely inhibited the formation of oxysterols, i.e., 7-hydroxycholesterol and 7-ketocholesterol, in LDL particles and reduced 1,1-diphenyl-2-picrylhydrazyl used as stable free-radical model. Moreover, SH-Chol suppressed the degradation of endogenous alpha-tocopherol in LDL particles. These findings indicate that SH-Chol acts as antioxidant in the oxidative damage of LDL in vitro and as a free-radical scavenger in lipid peroxidation.

  17. Simulation of lipid peroxidation in low-density lipoprotein by a basic "skeleton" of reactions.

    PubMed

    Abuja, P M; Esterbauer, H

    1995-01-01

    A minimal kinetic model describing lipid peroxidation in low-density lipoprotein (LDL) has been set up. Models have been calculated by numeric integration of the differential equations describing this system consisting of seven reactions and eleven reactants in a single compartment. The model describes the usually observed behavior of the reaction system, showing that the crucial intermediate is the lipid peroxyl radical (LOO.). During different stages of the reaction, depending on the presence of antioxidants (alpha-tocopherol), different pathways in the reaction scheme become active. Simulation also demonstrates that tocopherol-mediated propagation can occur under certain conditions, i.e., a low rate of initiation. This, however, does not mean that tocopherol enhances lipid peroxidation in LDL, as without tocopherol the process would be much faster. Further extension of the basic model by inclusion of a hypothetical antioxidant leads to a model which is capable of describing Cu(2+)-induced LPO over the whole lag phase up to full propagation.

  18. Minimally oxidized low-density lipoprotein induces tissue factor expression in cultured human endothelial cells.

    PubMed Central

    Drake, T. A.; Hannani, K.; Fei, H. H.; Lavi, S.; Berliner, J. A.

    1991-01-01

    Oxidatively modified low-density lipoprotein is present in atherosclerotic lesions and has been proposed to play an important role in atherogenesis through its biologic effects on vascular cells. This study examined the effects of minimally oxidized preparations of LDL (MM-LDL) on tissue factor (TF) expression by cultured human endothelial cells. Low-density lipoprotein purified from normal donors was modified by exposure to iron or by prolonged storage, resulting in levels of thiobarbituric acid-reacting substances of approximately 2.5 to 4 nmoles/mg cholesterol. Preparations had less than 2.5 pg of endotoxin per microgram LDL and had no intrinsic procoagulant activity. This form of modified but not native LDL induced TF expression in endothelial cells in a time- and dose-dependent manner. Peak TF coagulant activity in cells exposed to 40 micrograms/ml MM-LDL were observed at 4 to 6 hours, and ranged from 50 to 500 pg/10(5) cells, compared with less than 10 pg/10(5) cells exposed to native LDL. Northern blot analysis showed TF mRNA levels to increase approximately 30-fold with exposure to MM-LDL for 2 hours. Induction of TF activity was dependent on the concentration of MM-LDL from 1 microgram/ml to 80 micrograms/ml, a range in which cell viability and morphology were unaffected. The findings suggest that minimally oxidized LDL may be a local mediator promoting thrombosis in atherosclerotic lesions. Images Figure 1 PMID:2000938

  19. Long-Term Safety and Efficacy of Lowering Low-Density Lipoprotein Cholesterol With Statin Therapy

    PubMed Central

    Ford, Ian; Murray, Heather; Packard, Chris J.

    2016-01-01

    Background— Extended follow-up of statin-based low-density lipoprotein cholesterol lowering trials improves the understanding of statin safety and efficacy. Examining cumulative cardiovascular events (total burden of disease) gives a better appreciation of the clinical value of statins. This article evaluates the long-term impact of therapy on mortality and cumulative morbidity in a high-risk cohort of men. Methods and Results— The West of Scotland Coronary Prevention Study was a primary prevention trial in 45- to 64-year-old men with high low-density lipoprotein cholesterol. A total of 6595 men were randomized to receive pravastatin 40 mg once daily or placebo for an average of 4.9 years. Subsequent linkage to electronic health records permitted analysis of major incident events over 20 years. Post trial statin use was recorded for 5 years after the trial but not for the last 10 years. Men allocated to pravastatin had reduced all-cause mortality (hazard ratio, 0.87; 95% confidence interval, 0.80–0.94; P=0.0007), attributable mainly to a 21% decrease in cardiovascular death (hazard ratio, 0.79; 95% confidence interval, 0.69–0.90; P=0.0004). There was no difference in noncardiovascular or cancer death rates between groups. Cumulative hospitalization event rates were lower in the statin-treated arm: by 18% for any coronary event (P=0.002), by 24% for myocardial infarction (P=0.01), and by 35% for heart failure (P=0.002). There were no significant differences between groups in hospitalization for noncardiovascular causes. Conclusion— Statin treatment for 5 years was associated with a legacy benefit, with improved survival and a substantial reduction in cardiovascular disease outcomes over a 20-year period, supporting the wider adoption of primary prevention strategies. PMID:26864092

  20. Effect of improving glycemic control in patients with type 2 diabetes mellitus on low-density lipoprotein size, electronegative low-density lipoprotein and lipoprotein-associated phospholipase A2 distribution.

    PubMed

    Sánchez-Quesada, José L; Vinagre, Irene; de Juan-Franco, Elena; Sánchez-Hernández, Juan; Blanco-Vaca, Francisco; Ordóñez-Llanos, Jordi; Pérez, Antonio

    2012-07-01

    The aim of this study was to determine the effect of intensified hypoglycemic therapy in patients with type 2 diabetes mellitus on the distribution of lipoprotein-associated phospholipase A2 (Lp-PLA2) activity between high-density lipoprotein and low-density lipoprotein (LDL) and its relation with the lipid profile and other qualitative properties of LDL. Forty-two patients with type 2 diabetes on the basis of poor glycemic control and normal or near normal LDL cholesterol were recruited. Lifestyle counseling and pharmacologic hypoglycemic therapy were intensified to improve glycemic control, but lipid-lowering therapy was unchanged. At 4 ± 2 months, glycosylated hemoglobin had decreased by a mean of 2.1%, but the only effect on the lipid profile were statistically significant decreases in nonesterified fatty acids and apolipoprotein B concentration. LDL size increased and the proportion of electronegative LDL decreased significantly. In parallel, total Lp-PLA2 activity decreased significantly, promoting a redistribution of Lp-PLA2 activity toward a higher proportion in high-density lipoprotein. Improvements in glycemic control led to more marked changes in Lp-PLA2 activity and distribution in patients with diabetes who had not received previous lipid-lowering therapy. In conclusion, optimizing glycemic control in patients with type 2 diabetes promotes atheroprotective changes, including larger LDL size, decreased electronegative LDL, and a higher proportion of Lp-PLA2 activity in high-density lipoprotein.

  1. 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

  2. High hydrostatic pressure specifically affects molecular dynamics and shape of low-density lipoprotein particles.

    PubMed

    Golub, M; Lehofer, B; Martinez, N; Ollivier, J; Kohlbrecher, J; Prassl, R; Peters, J

    2017-04-06

    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.

  3. Optical Characterization of Europium Tetracycline Complex in the presence of Low Density Lipoprotein and its Applications

    NASA Astrophysics Data System (ADS)

    de Oliveira Silva, Flávia Rodrigues; Monteiro, Andrea Moreira; Neto, Antônio M. Figueiredo; Gidlund, Magnus A.; Gomes, Laércio; Junior, Nilson Dias Vieira; Courrol, Lilia Coronato

    2008-04-01

    Development of native Low Density Lipoprotein (LDL) biosensors is of great importance in clinical analysis because the LDL concentration, which is the main carrier of cholesterol, in the plasma, is a fundamental parameter for the prevention and diagnosis of a number of clinical disorders such as heart disease, hypertension and atherosclerosis. The optical properties of the Europium-Tetracycline Complex (EuTc) were investigated for the solutions containing LDL in their compositions. In this paper we show an enhancement in the europium luminescence of EuTc complex in the presence of LDL. The time-resolved fluorescence spectroscopy experimental results of the pure EuTc sample and samples with LDL (EuTc:LDL) reveal an increase in the europium emission lifetime in the lipoprotein-doped samples with respect to the pure EuTc sample. A calibration curve, reasonably well described by a linear function between 0 and 3 mg/mL of LDL, was obtained. The obtained limit of detection was 0.23 mg/mL. Sixteen blood plasma samples all of them contend approximately 90 mg/dL of LDL were studied and the LDL concentrations were calculated with our method. The average LDL concentration obtained was 94 mg/dL. The results show that the EuTc complex can be used as a sensor to determine LDL with fast response, compact design, and reproducible results.

  4. Effects of estrogen on very low-density lipoprotein triglyceride metabolism in fed and fasted chicks

    SciTech Connect

    Park, J.R.

    1988-01-01

    A single injection of estrogen into growing chicks resulted in a marked elevation in plasma triglyceride (TG) followed by phospholipid (PL) and cholesterol (CH) in both fed and fasted chicks. Estrogen caused a development of massive fatty liver in fed chicks. Hepatic malic enzyme and glucose-6-phosphate dehydrogenase activities also increased significantly in fed chicks and, to a small extent, in fasted chicks. Very low density lipoproteins (VLDL) were barely detectable in the fasted control plasma. However, the VLDL concentration increased markedly upon estrogen injection, becoming the most prevalent lipoprotein in the plasma. The administration of estrogen resulted in an increase in oleic acid and a decrease in linoleic acid content except in the cholesteryl ester of VLDL and LDL. VLDL of estrogenized birds had {beta}-mobility on agarose gel electrophoresis, and they eluted in two peaks on agarose gel filtration chromatography. Both peaks on gel filtration exhibited the same {beta}-mobility on agarose gel electrophoresis. Nevertheless, the apoprotein composition of these two peaks were substantially different from each other; apo B was not present in the first peak VLDL. VLDL-TG kinetic studies conducted in vivo, using {sup 14}C-TG-VLDL prepared endogenously from control and estrogenized chicks revealed that VLDL-TG produced from the former had a higher fractional catabolic rate (FCR) than VLDL-TG from the latter.

  5. Lipoprotein Receptors Redundantly Participate in Entry of Hepatitis C Virus.

    PubMed

    Yamamoto, Satomi; Fukuhara, Takasuke; Ono, Chikako; Uemura, Kentaro; Kawachi, Yukako; Shiokawa, Mai; Mori, Hiroyuki; Wada, Masami; Shima, Ryoichi; Okamoto, Toru; Hiraga, Nobuhiko; Suzuki, Ryosuke; Chayama, Kazuaki; Wakita, Takaji; Matsuura, Yoshiharu

    2016-05-01

    Scavenger receptor class B type 1 (SR-B1) and low-density lipoprotein receptor (LDLR) are known to be involved in entry of hepatitis C virus (HCV), but their precise roles and their interplay are not fully understood. In this study, deficiency of both SR-B1 and LDLR in Huh7 cells was shown to impair the entry of HCV more strongly than deficiency of either SR-B1 or LDLR alone. In addition, exogenous expression of not only SR-B1 and LDLR but also very low-density lipoprotein receptor (VLDLR) rescued HCV entry in the SR-B1 and LDLR double-knockout cells, suggesting that VLDLR has similar roles in HCV entry. VLDLR is a lipoprotein receptor, but the level of its hepatic expression was lower than those of SR-B1 and LDLR. Moreover, expression of mutant lipoprotein receptors incapable of binding to or uptake of lipid resulted in no or slight enhancement of HCV entry in the double-knockout cells, suggesting that binding and/or uptake activities of lipid by lipoprotein receptors are essential for HCV entry. In addition, rescue of infectivity in the double-knockout cells by the expression of the lipoprotein receptors was not observed following infection with pseudotype particles bearing HCV envelope proteins produced in non-hepatic cells, suggesting that lipoproteins associated with HCV particles participate in the entry through their interaction with lipoprotein receptors. Buoyant density gradient analysis revealed that HCV utilizes these lipoprotein receptors in a manner dependent on the lipoproteins associated with HCV particles. Collectively, these results suggest that lipoprotein receptors redundantly participate in the entry of HCV.

  6. [Low density lipoprotein rich in triglycerides and hepatic lipase activity in insulin-dependent diabetic patients].

    PubMed

    Rosental, S B; Schreier, L E; Halperin, H; Berg, G; Paglione, A M; Ruiz, M; Wikinski, R L

    1995-01-01

    Genetic hepatic lipase (HL) deficiency is associated with low density lipoprotein (LDL) rich in triglycerides (TG), whose affinity for B:E receptors is decreased. In rats, experimental hypoinsulinemia produces HL deficiency. However, the relation between human insulin-dependent Diabetes Mellitus (IDDM), HL activity and the characteristics of LDL have not been studied. The objective of our study is to evaluate the relation between HL activity and the chemical composition of LDL in treated IDDM patients. Subjects were 15 IDDM patients and 15 controls (C), matched for sex and body mass index (BMI). The IDDM patients were classified by the WHO criteria, were free of nephropathy and hypothyroidism, and received no medication except insulin. Controls were clinically healthy and normolipidemic with no family history of diabetes. The IDDM group was divided into two subgroups: subgroup IDDM-A (n = 9) with HL values > or = 4.3 and IDDM-B (n = 6) with HL < or = than 4.2 mumoles glycerol/ml h. the HL in IDDM was lower than in C (p < 0.001). Table 1 shows clinical data. Blood samples were drawn after 12 h fasting. Percentage of HbA1c and plasma concentrations of glucose, total cholesterol, LDL-cholesterol, HDL-cholesterol and TG were assayed. LDL was separated by sequential ultracentrifugation at densities of 1.019-1.063 g/ml and its chemical composition was analyzed. The most relevant results were: plasma TG concentration was higher in IDDM than in C (p < 0.05) (Table 2), although average values DMID not exceed the reference values of 200 mg/dl. The TG-LDL were higher in IDDM than in C: 24.8 +/- 2.7 vs 17.5 +/- 1.1 mg/dl plasma, media +/- SE, (p < 0.02). This difference reflected the values of IDDM-B, whose plasma concentrations of TG-LDL were higher than in C: 32.3 +/- 3.6 vs 17.5 +/- 1.1 mg/dl (p < 0.001), and also higher than in IDDM-A (p < 0.02). (Table 3). The chemical composition of LDL in IDDM-B contained a higher percentage of TG than C: 8.5 +/- 0.7 vs 6.8 +/- 0.3% (p

  7. High density lipoprotein level is negatively associated with the increase of oxidized low density lipoprotein lipids after a fatty meal.

    PubMed

    Tiainen, Sanna; Ahotupa, Markku; Ylinen, Petteri; Vasankari, Tommi

    2014-12-01

    Recent reports show that a fatty meal can substantially increase the concentration of oxidized lipids in low density lipoprotein (LDL). Knowing the LDL-specific antioxidant effects of high density lipoprotein (HDL), we aimed to investigate whether HDL can modify the postprandial oxidative stress after a fatty meal. Subjects of the study (n = 71) consumed a test meal (a standard hamburger meal) rich in lipid peroxides, and blood samples were taken before, 120, 240, and 360 min after the meal. The study subjects were divided into four subgroups according to the pre-meal HDL cholesterol value (HDL subgroup 1, 0.66-0.91; subgroup 2, 0.93-1.13; subgroup 3, 1.16-1.35; subgroup 4, 1.40-2.65 mmol/L). The test meal induced a marked postprandial increase in the concentration of oxidized LDL lipids in all four subgroups. The pre-meal HDL level was associated with the extent of the postprandial rise in oxidized LDL lipids. From baseline to 6 h after the meal, the concentration of ox-LDL increased by 48, 31, 24, and 16% in the HDL subgroup 1, 2, 3, and 4, respectively, and the increase was higher in subgroup 1 compared to subgroup 3 (p = 0.028) and subgroup 4 (p = 0.0081), respectively. The pre-meal HDL correlated with both the amount and the rate of increase of oxidized LDL lipids. Results of the present study show that HDL is associated with the postprandial appearance of lipid peroxides in LDL. It is therefore likely that the sequestration and transport of atherogenic lipid peroxides is another significant mechanism contributing to cardioprotection by HDL.

  8. Alpinetin enhances cholesterol efflux and inhibits lipid accumulation in oxidized low-density lipoprotein-loaded human macrophages.

    PubMed

    Jiang, Zhengming; Sang, Haiqiang; Fu, Xin; Liang, Ying; Li, Ling

    2015-01-01

    Alpinetin is a natural flavonoid abundantly present in the ginger family. Here, we investigated the effect of alpinetin on cholesterol efflux and lipid accumulation in oxidized low-density lipoprotein (ox-LDL)-treated THP-1 macrophages and human peripheral blood monocyte-derived macrophages (HMDMs). After exposing THP-1 macrophages to alpinetin, cholesterol efflux was determined by liquid scintillator. The mRNA and protein levels of peroxisome proliferator-activated receptor gamma (PPAR-γ), liver X receptor alpha (LXR-α), ATP-binding cassette transporter A1 (ABCA1), and ABCG1 and scavenger receptor class B member 1 were determined by reverse-transcriptase PCR (RT-PCR) and Western blot analysis, respectively. Alpinetin promoted apolipoprotein A-I- and high-density-lipoprotein-mediated cholesterol efflux and elevated PPAR-γ and LXR-α mRNA and protein expression in a dose-dependent fashion in ox-LDL-treated THP-1 macrophages and HMDMs. Small interfering RNA-mediated silencing of PPAR-γ or LXR-α dose dependently reversed alpinetin-increased cholesterol efflux in THP-1 macrophages, indicating the involvement of PPAR-γ and LXR-α in alpinetin-promoted cholesterol efflux. Alpinetin inhibited ox-LDL-induced lipid accumulation and enhanced the expression of ABCA1 and ABCG1 mRNA and protein, which was reversed by specific knockdown of PPAR-γ or LXR-α. Taken together, our results reveal that alpinetin exhibits positive effects on cholesterol efflux and inhibits ox-LDL-induced lipid accumulation, which might be through PPAR-γ/LXR-α/ABCA1/ABCG1 pathway.

  9. Pectin isolated from prickly pear (Opuntia sp.) modifies low density lipoprotein metabolism in cholesterol-fed guinea pigs.

    PubMed

    Fernandez, M L; Trejo, A; McNamara, D J

    1990-11-01

    The effect of prickly pear soluble fiber on low density lipoprotein (LDL) metabolism was investigated by feeding male guinea pigs either a nonpurified diet containing 0.25% cholesterol (HC diet) or the HC diet + 1% prickly pear pectin (HC-P diet). Plasma cholesterol levels were significantly decreased by the HC-P diet, with a 33% decrease in LDL levels (p less than 0.02) and an increase in LDL density. Hepatic free and esterified cholesterol levels were reduced 40 and 85%, respectively (p less than 0.002), by the HC-P diet. Hepatic microsomal 3-hydroxy-3-methylglutaryl coenzyme A reductase levels were not different. 125I-LDL binding to hepatic membranes was increased 1.7-fold by the HC-P diet (p less than 0.001), with receptor affinity (Kd) being unaltered and receptor number (Bmax) being significantly increased (p less than 0.001). These data suggest that prickly pear pectin may act by a mechanism similar to that of bile acid-binding resins in lowering plasma cholesterol levels. The observed reduction in LDL and hepatic cholesterol levels and increase in LDL density and hepatic apolipoprotein B/E receptors are responses suggesting an increased demand on hepatic cholesterol from increased excretion of bile acids and interruption of the enterohepatic circulation.

  10. Apple juice consumption reduces plasma low-density lipoprotein oxidation in healthy men and women.

    PubMed

    Hyson, D; Studebaker-Hallman, D; Davis, P A; Gershwin, M E

    2000-01-01

    ABSTRACT Epidemiological studies show that consumption of fruits and vegetables is associated with beneficial effects on human health including reduced risk of coronary artery disease (CAD). Fruits and their juices contain phytochemicals that inhibit in vitro low-density lipoprotein (LDL) oxidation and may account, in part, for their protective effect. However, reports of in vivo antioxidant effects from fruit intake are limited. We conducted a human trial to examine the in vivo effect of consumption of apples (both whole and juice) in an unblinded, randomized, crossover design. Healthy men and women added 375 ml of unsupplemented apple juice or 340 g of cored whole apple to their daily diet for 6 weeks, then crossed over to the alternate product for 6 weeks. Blood samples were obtained at baseline and after each dietary period. Compliance was monitored via biweekly 5-day food records, bodyweight checks, and meetings with study personnel. There were no significant differences between groups in intake of dietary fat, cholesterol, total carbohydrate, sugar, or calories throughout the study. Dietary fiber intake increased by 22% with whole apple consumption. Body weight, fasting serum lipid concentration, and other lipoprotein parameters were unchanged. Apple juice consumption increased ex vivo copper (Cu(++))-mediated LDL oxidation lag time by 20% compared with baseline. Apples and apple juice both reduced conjugated diene formation. Moderate apple juice consumption provides in vivo antioxidant activity. In view of the current understanding of CAD, the observed effect on LDL might be associated with reduced CAD risk and supports the inclusion of apple juice in a healthy human diet.

  11. Structure of human plasma low-density lipoproteins: molecular organization of the central core.

    PubMed Central

    Atkinson, D; Deckelbaum, R J; Small, D M; Shipley, G G

    1977-01-01

    Human plasma low density lipoprotein (LDL) exhibits a thermal transition over the temperature range 20-40 degrees. This transition is associated with a structural change within the lipoprotein particle and is reflected in the small-angle x-ray scattering profiles from LDL. The scattering profile of the quasispherical LDL particle at 10 degrees shows a relatively intense maximum at 1/36 A-1 which is absent from the scattering of LDL at 45 degrees. Theoretical calculations, using model electron density distributions, have been carried out to describe the packing of arrangement of the cholesterol esters, based on perturbations of the molecular packing of crystalline cholesteryl myristate, adequately reproduces the high relative intensity of the x-ray scattering maximum at 1/36 A-1. The perturbations of the packing in the crystal structure of cholesteryl myristate involve "melting" of the hydrocarbon chains of the esters together with translations of pairs of molecules parallel to the molecular long axis. The interaction of opposing steroid moieties, with C18 and C19 angular methyl groups interlocked, exhibited in the crystal structure is retained in the perturbed arrangement. At 45 degrees, thermally induced disorder of this arrangement averages the electron density of the central core. The x-ray scattering profiles of particles with a homogeneous electron density in the core region do not show a high relative intensity of the subsidiary maxima in the 1/36 A-1 region, in agreement with experimental observation. The results of these calculations support the concept that the thermal transition observed for LDL is due to a smectic leads to disordered transition of the cholesterol esters in the core of the LDL particle. PMID:191827

  12. Effects of exposure to carbon disulphide on low density lipoprotein cholesterol concentration and diastolic blood pressure.

    PubMed Central

    Egeland, G M; Burkhart, G A; Schnorr, T M; Hornung, R W; Fajen, J M; Lee, S T

    1992-01-01

    The relation of carbon disulphide (CS2) exposure to risk factors for ischaemic heart disease was recently examined using data from a 1979 cross sectional study of 410 male textile workers, of whom 165 were exposed and 245 were unexposed to CS2. Average eight hour CS2 exposure concentrations ranged from 0.6 to 11.8 ppm by job title category among the exposed workers. A significant and positive linear trend in low density lipoprotein cholesterol concentration (LDLc) and diastolic blood pressure with increasing CS2 exposure was found after adjustment for potential confounders. When exposure was examined as a categorical variable (none, low, moderate, and high), the high exposure group had an adjusted mean LDLc that was 0.32 mmol/l greater than the non-exposed group (p = 0.02), and an adjusted mean diastolic blood pressure that was 3.16 mm Hg greater than the non-exposed group (p = 0.09). The effect of CS2 on diastolic blood pressure was strengthened in analyses limited to exposed workers: the high exposure group had an adjusted mean diastolic blood pressure that was 5 mm Hg greater than that of the low exposed group (p = 0.03). Triglyceride, high density lipoprotein cholesterol, and fasting glucose concentration, and systolic blood pressure were not affected by exposure. Blood lead concentration was positively associated with systolic and diastolic blood pressure. The results indicate that relatively modest exposure to CS2 may raise LDLc concentration and diastolic blood pressure and suggest mechanisms by which exposure to CS2 may influence risk of ischaemic heart disease. Also the results provide further support for the hypothesis of a possible association between blood lead concentration and blood pressure. PMID:1571299

  13. Modulation of lipoprotein receptor functions by intracellular adaptor proteins.

    PubMed

    Stolt, Peggy C; Bock, Hans H

    2006-10-01

    Members of the low density lipoprotein (LDL) receptor gene family are critically involved in a wide range of physiological processes including lipid and vitamin homeostasis, cellular migration, neurodevelopment, and synaptic plasticity, to name a few. Lipoprotein receptors exert these diverse biological functions by acting as cellular uptake receptors or by inducing intracellular signaling cascades. It was discovered that a short sequence in the intracellular region of all lipoprotein receptors, Asn-Pro-X-Tyr (NPXY) is important for mediating either endocytosis or signal transduction events, and that this motif serves as a binding site for phosphotyrosine-binding (PTB) domain containing scaffold proteins. These molecular adaptors connect the transmembrane receptors with the endocytosis machinery and regulate cellular trafficking, or function as assembly sites for dynamic multi-protein signaling complexes. Whereas the LDL receptor represents the archetype of an endocytic lipoprotein receptor, the structurally closely related apolipoprotein E receptor 2 (apoER2) and very low density lipoprotein (VLDL) receptor activate a kinase-dependent intracellular signaling cascade after binding to the neuronal signaling molecule Reelin. This review focuses on two related PTB domain containing adaptor proteins that mediate these divergent lipoprotein receptor responses, ARH (autosomal recessive hypercholesterolemia protein) and Dab1 (disabled-1), and discusses the structural and molecular basis of this different behaviour.

  14. Studies on the Structure of Low Density Lipoproteins Isolated from Macaca Fascicularis Fed an Atherogenic Diet

    PubMed Central

    Tall, Alan R.; Small, Donald M.; Atkinson, David; Rudel, Lawrence L.

    1978-01-01

    Cynomolgus monkeys, Macaca fascicularis, fed cholesterol-containing saturated-fat diets develop increased levels of high molecular weight plasma low density lipoproteins (LDL), associated with accelerated atherosclerosis. To study the composition and structure of these abnormal particles, LDL from monkeys, fed atherogenic and control diets, were characterized chemically and examined by differential scanning calorimetry and low-angle X-ray scattering. LDL from animals on the experimental diet showed an increase in molecular weight (4.0 to 7.0 × 106, experimental diet compared with 3.0 to 3.7 × 106, control diet) associated with a large increase in cholesterol ester content and concomitant smaller increases in protein, phospholipid, and free cholesterol. There was a strong positive correlation between molecular weight and the number of saturated and monounsaturated cholesterol esters in the particle. In contrast, particle content of polyunsaturated cholesterol esters remained constant despite large changes in total particle cholesterol esters. When examined by calorimetry and X-ray scattering, LDL from monkeys on both diets diplayed a reversible transition of cholesterol esters from an ordered smeticlike (layered) structure to a more disordered state. For all animals on the experimental diet, the peak temperature of the cholesterol-ester transition (42-48°C) was above body temperature (39°C), but below body temperature on the control diet (34-38.5°C). In the experimental group, the transition temperature was correlated with the LDL molecular weight. However, after thermal disruption of LDL, liquid-crystalline transitions of LDL cholesterol esters were observed in the same temperature range as in the intact lipoprotein, which shows that changes in particle size had little effect on the cholesterol-ester transition temperature. Rather, the transition temperature was determined by the degree of saturation of the LDL cholesterol ester fatty acids and the LDL

  15. Genetic variation at the PCSK9 locus, low density lipoproteins, response to pravastatin and coronary heart disease: results from PROSPER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Caucasian carriers of the T allele at R46L in the proprotein convertase subtilisin/kexin type 9 (PCSK9) locus have been reported to have 15% lower low-density lipoprotein (LDL) cholesterol (C) levels and 47% lower coronary heart disease (CHD) risk. Our objective was to examine two PCSK9 single nucle...

  16. Effects of maximal doses of atorvastatin versus rosuvastatin on small dense low-density lipoprotein cholesterol levels

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maximal doses of atorvastatin and rosuvastatin are highly effective in lowering low-density lipoprotein (LDL) cholesterol and triglyceride levels; however, rosuvastatin has been shown to be significantly more effective than atorvastatin in lowering LDL cholesterol and in increasing high-density lipo...

  17. Very-low-density lipoprotein: complex particles in cardiac energy metabolism.

    PubMed

    Niu, You-Guo; Evans, Rhys D

    2011-01-01

    The heart is a major consumer of energy and is able to utilise a wide range of substrates including lipids. Nonesterified fatty acids (NEFA) were thought to be a favoured carbon source, but their quantitative contribution is limited because of their relative histotoxicity. Circulating triacylglycerols (TAGs) in the form of chylomicrons (CMs) and very-low-density lipoprotein (VLDL) are an alternative source of fatty acids and are now believed to be important in cardiac metabolism. However, few studies on cardiac utilisation of VLDL have been performed and the role of VLDL in cardiac energy metabolism remains unclear. Hearts utilise VLDL to generate ATP, but the oxidation rate of VLDL-TAG is relatively low under physiological conditions; however, in certain pathological states switching of energy substrates occurs and VLDL may become a major energy source for hearts. We review research regarding myocardial utilisation of VLDL and suggest possible roles of VLDL in cardiac energy metabolism: metabolic regulator and extracardiac energy storage for hearts.

  18. Ferritin protects endothelial cells from oxidized low density lipoprotein in vitro.

    PubMed Central

    Juckett, M. B.; Balla, J.; Balla, G.; Jessurun, J.; Jacob, H. S.; Vercellotti, G. M.

    1995-01-01

    Low density lipoprotein (LDL), if it becomes oxidized, develops several unique properties including the capacity to provoke endothelial cytotoxicity via metal-catalyzed free radical-mediated mechanisms. As were previously have shown that iron-catalyzed oxidant injury to endothelial cells can be attenuated by the addition of exogenous iron chelators such as the lazaroids and deferoxamine, we have examined whether the endogenous iron chelator, ferritin, might provide protection from oxidized LDL. LDL oxidized by iron-containing hemin and H2O2 is toxic to endothelial cells in a time- and dose-dependent fashion. Endothelial cell ferritin content is increased by pretreatment of cells with iron compounds or by the direct addition of exogenous apoferritin; ferritin-loaded cells are markedly resistant to the toxicity caused by oxidized LDL. Iron inactivation by ferritin depends on its ferroxidase activity. When a recombinant human ferritin heavy chain mutant, 222, which is devoid of ferroxidase activity, is added to endothelial cells, unlike the excellent protection afforded by the wild-type recombinant heavy chain, endothelial cells are not protected from oxidized LDL. To assess the in vivo relevance of our observation, we examined human coronary arteries of cardiac explants taken from patients with end-stage atherosclerosis. Large amounts of immunoreactive ferritin are focally detected in atherosclerotic lesions, specifically in the myofibroblasts, macrophages, and endothelium without a notable increase in Prussian blue-detectable iron. These findings suggest that ferritin may modulate vascular cell injury in vivo. Images Figure 3 Figure 4 PMID:7677189

  19. Influence of oxidized low-density lipoproteins (LDL) on the viability of osteoblastic cells.

    PubMed

    Brodeur, Mathieu R; Brissette, Louise; Falstrault, Louise; Ouellet, Pascale; Moreau, Robert

    2008-02-15

    Cardiovascular diseases have recently been noted as potential risk factors for osteoporosis development. Although it is poorly understood how these two pathologies are related, it is a known fact that oxidized low-density lipoproteins (OxLDL) constitute potential determinants for both of them. The current study investigated the metabolism of OxLDL by osteoblasts and its effect on osteoblastic viability. The results obtained show that OxLDL are internalized but not degraded by osteoblasts while they can selectively transfer their CE to these cells. It is also demonstrated that OxLDL induce proliferation at low concentrations but cell death at high concentrations. This reduction of osteoblast viability was associated with lysosomal membrane damage caused by OxLDL as demonstrated by acridine orange relocalization. Accordingly, chloroquine, an inhibitor of lysosomal activity, accentuated cell death induced by OxLDL. Finally, we demonstrate that osteoblasts have the capacity to oxidize LDL and thereby potentially increase the local concentration of OxLDL. Overall, the current study confirms the potential role of OxLDL in the development of osteoporosis given its influence on osteoblastic viability.

  20. Tumor-targeted delivery of paclitaxel using low density lipoprotein-mimetic solid lipid nanoparticles.

    PubMed

    Kim, Jin-Ho; Kim, Youngwook; Bae, Ki Hyun; Park, Tae Gwan; Lee, Jung Hee; Park, Keunchil

    2015-04-06

    Water-insoluble anticancer drugs, including paclitaxel, present severe clinical side effects when administered to patients, primarily associated with the toxicity of reagents used to solubilize the drugs. In efforts to develop alternative formulations of water-insoluble anticancer drugs suitable for intravenous administration, we developed biocompatible anticancer therapeutic solid lipid nanoparticles (SLNs), mimicking the structure and composition of natural particles, low-density lipoproteins (LDLs), for tumor-targeted delivery of paclitaxel. These therapeutic nanoparticles contained water-insoluble paclitaxel in the core with tumor-targeting ligand covalently conjugated on the polyethylene glycol (PEG)-modified surface (targeted PtSLNs). In preclinical human cancer xenograft mouse model studies, the paclitaxel-containing tumor-targeting SLNs exhibited pronounced in vivo stability and enhanced biocompatibility. Furthermore, these SLNs had superior antitumor activity to in-class nanoparticular therapeutics in clinical use (Taxol and Genexol-PM) and yielded long-term complete responses. The in vivo targeted antitumor activities of the SLN formulations in a mouse tumor model suggest that LDL-mimetic SLN formulations can be utilized as a biocompatible, tumor-targeting platform for the delivery of various anticancer therapeutics.

  1. Analysis of non-Newtonian effects on Low-Density Lipoprotein accumulation in an artery.

    PubMed

    Iasiello, Marcello; Vafai, Kambiz; Andreozzi, Assunta; Bianco, Nicola

    2016-06-14

    In this work, non-Newtonian effects on Low-Density Lipoprotein (LDL) transport across an artery are analyzed with a multi-layer model. Four rheological models (Carreau, Carreau-Yasuda, power-law and Newtonian) are used for the blood flow through the lumen. For the non-Newtonian cases, the arterial wall is modeled with a generalized momentum equation. Convection-diffusion equation is used for the LDL transport through the lumen, while Staverman-Kedem-Katchalsky, combined with porous media equations, are used for the LDL transport through the wall. Results are presented in terms of filtration velocity, Wall Shear Stresses (WSS) and concentration profiles. It is shown that non-Newtonian effects on mass transport are negligible for a healthy intramural pressure value. Non-Newtonian effects increase slightly with intramural pressure, but Newtonian assumption can still be considered reliable. Effects of arterial size are also analyzed, showing that Newtonian assumption can be considered valid for both medium and large arteries, in predicting LDL deposition. Finally, non-Newtonian effects are also analyzed for an aorta-common iliac bifurcation, showing that Newtonian assumption is valid for mass transport at low Reynolds numbers. At a high Reynolds number, it has been shown that a non-Newtonian fluid model can have more impact due to the presence of flow recirculation.

  2. Novel fluorescently labeled peptide compounds for detection of oxidized low-density lipoprotein at high specificity.

    PubMed

    Sato, Akira; Yamanaka, Hikaru; Oe, Keitaro; Yamazaki, Yoji; Ebina, Keiichi

    2014-10-01

    The probes for specific detection of oxidized low-density lipoprotein (ox-LDL) in plasma and in atherosclerotic plaques are expected to be useful for the identification, diagnosis, prevention, and treatment for atherosclerosis. In this study, to develop a fluorescent peptide probe for specific detection of ox-LDL, we investigated the interaction of fluorescein isothiocyanate (FITC)-labeled peptides with ox-LDL using polyacrylamide gel electrophoresis. Two heptapeptides (KWYKDGD and KP6) coupled through the ε-amino group of K at the N-terminus to FITC in the presence/absence of 6-amino-n-caproic acid (AC) linker to FITC--(FITC-AC)KP6 and (FITC)KP6--both bound with high specificity to ox-LDL in a dose-dependent manner. In contrast, a tetrapeptide (YKDG) labeled with FITC at the N-terminus and a pentapeptide (YKDGK) coupled through the ε-amino group of K at the C-terminus to FITC did not bind selectively to ox-LDL. Furthermore, (FITC)KP6 and (FITC-AC)KP6 bound with high specificity to the protein in mouse plasma (probably ox-LDL fraction). These findings strongly suggest that (FITC)KP6 and (FITC-AC)KP6 may be effective novel fluorescent probes for specific detection of ox-LDL.

  3. Oxidized low density lipoprotein increases acetylcholinesterase activity correlating with reactive oxygen species production.

    PubMed

    Yamchuen, Panit; Aimjongjun, Sathid; Limpeanchob, Nanteetip

    2014-12-01

    Hyperlipidemia, low density lipoproteins (LDL) and their oxidized forms, and oxidative stress are suspected to be a key combination in the onset of AD and acetylcholinesterase (AChE) plays a part in this pathology. The present study aimed to link these parameters using differentiated SH-SY5Y human neuroblastoma cells in culture. Both mildly and fully oxidized human LDL (mox- and fox-LDL), but not native (non-oxidized) LDL were cytotoxic in dose- and time-dependent patterns and this was accompanied by an increased production of intracellular reactive oxygen species (ROS). Oxidized LDL (10-200 μg/mL) augmented AChE activity after 4 and 24h treatments, respectively while the native LDL was without effect. The increased AChE with oxidized LDLs was accompanied by a proportionate increase in intracellular ROS formation (R=0.904). These findings support the notion that oxidized LDLs are cytotoxic and that their action on AChE may reduce central cholinergic transmission in AD and affirm AChE as a continued rational for anticholinesterase therapy but in conjunction with antioxidant/antihyperlipidemic cotreatments.

  4. Adrenal imaging with technetium-99m-labelled low density lipoproteins

    SciTech Connect

    Isaacsohn, J.L.; Lees, A.M.; Lees, R.S.; Strauss, H.W.; Barlai-Kovach, M.; Moore, T.J.

    1986-04-01

    Evaluation of adrenal cortical function by external imaging is currently accomplished by injection of radiolabelled analogs of cholesterol. Although the adrenals do utilized exogenous cholesterol for steroid hormone synthesis, the cholesterol is delivered to the glands not as free cholesterol but through the uptake of low density lipoproteins (LDL), which are subsequently degraded within the adrenal cortical cells to provide cholesterol. Thus, we sought to assess the use of /sup 99m/Tc-labelled LDL injected into rabbits to obtain external images of the adrenal glands. Adrenal images of all nine rabbits tested were obtained within 18 to 21 hours after injection of /sup 99m/Tc-LDL. Seven of the rabbits were subjected to adrenal cortical suppression with dexamethasone and then all nine rabbits were imaged a second time. In the untreated animals, visualization of the adrenal glands was accompanied by normal serum cortisol concentrations and accumulation of radiolabel in the adrenals, whereas in the dexamethasone-treated animals, lack of visualization of the adrenal glands was correlated with low serum cortisols, and greatly decreased accumulation of the radionuclide in the adrenals. These findings demonstrate for the first time that LDL, when labelled with /sup 99m/Tc, can be used to evaluate adrenal cortical function by external imaging.

  5. Low density lipoprotein adsorption on sol-gel derived alumina for blood purification therapy.

    PubMed

    Asano, Takuji; Tsuru, Kanji; Hayakawa, Satoshi; Osaka, Akiyoshi

    2008-01-01

    Among the clinical treatments of Familial Hyper cholesterolemia patients to reduce the concentration of low density lipoprotein (LDL), blood purification therapy is most suitable in which a blood-compatible adsorbent is employed. In the present study, alumina powders were prepared via a sol-gel route to develop a LDL-adsorbent Aluminum tri2-propoxide was hydrolyzed and subsequently calcined up to 1200 degrees C. Surface charge density and pore size distribution were measured, and the phases were identified. The alumina calcined above 400 degrees C had excellent blood compatibility in terms of endogenous clotting parameters, i.e., partial thromboplastin time: (PTT), prothrombin time: (PT), and the amount of fibrinogen: (Fib). The amount of LDL-adsorption (DeltaW(LDL)) increased with the calcining temperature, showing a good linear correlation to surface charge density. The 1200 degrees C sample consisted only of alpha-alumina, and was greatest in DeltaW(LDL). All samples involved pores smaller than 20 nm but not the pores large enough to accommodate LDL molecules (20-25 nm). From those results, it was concluded for the present alumina particles that the surface charge density was the primary factor and that the chemical activity of alpha-alumina also contributed to the excellent LDL-adsorption for the 1200 degrees C sample, while entrapping LDL in the pores was not an active mechanism.

  6. Ordering and stability in lipid droplets with applications to low-density lipoproteins

    NASA Astrophysics Data System (ADS)

    Lancaster, Jarrett L.; Antonijevic, Todor; Starobin, Joseph M.

    2014-06-01

    In this article, we present a framework for investigating the order-disorder transition in lipid droplets using the standard Ising model. While a single lipid droplet is itself a complex system whose constituent cholesteryl esters each possesses many degrees of freedom, we present justification for using this effective approach to isolate the underlying physics. It is argued that the behavior of the esters confined within lipid droplets is significantly different from that of a bulk system of similar esters, which is adequately described by continuum mean-field theory in the thermodynamic limit. When the droplet's shell is modeled as an elastic membrane, a simple picture emerges for a transition between two ordered phases within the core which is tuned by the strength of interactions between the esters. Triglyceride concentration is proposed as a variable which strongly influences the strength of interactions between cholesteryl esters within droplets. The possible relevance of this mechanism to the well known atherogenic nature of small low-density lipoprotein particles is discussed in detail.

  7. Nanostructured NiO-based reagentless biosensor for total cholesterol and low density lipoprotein detection.

    PubMed

    Kaur, Gurpreet; Tomar, Monika; Gupta, Vinay

    2017-03-01

    Nanostructured nickel oxide (NiO) thin film has been explored as a matrix to develop a reagentless biosensor for free and total cholesterol as well as low density lipoprotein (LDL) detection. The redox property of the matrix has been exploited to enhance the electron transfer between the enzyme and the electrode as well as to eliminate the toxic mediator in solution. X-ray diffraction, scanning electron microscopy, atomic force microscopy, and Fourier transform infrared spectroscopy were carried out to characterize the NiO thin film. Biosensing response studies were accomplished using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). The developed biosensors exhibited a high sensitivity of 27 and 63 μA/mM/cm(2) over a linear range of 0.12-10.23 and 1-12 mM, respectively, for free and total cholesterol. Reagentless estimation of LDL was also achieved over the wide range 0.018-0.5 μM with a sensitivity of 0.12 mA/μM/cm(2). The results are extremely promising for the realization of an integrated biosensor for complete detection of cholesterol in the serum samples. Graphical Abstract Reagentless sensing mechanism of (a) free cholesterol and (b) total cholesterol using nanostructured NiO matrix.

  8. Inhibitory effect of oolong tea on the oxidative state of low density lipoprotein (LDL).

    PubMed

    Kurihara, Hiroshi; Fukami, Harukazu; Toyoda, Yoshiko; Kageyama, Norihiko; Tsuruoka, Nobuo; Shibata, Hiroshi; Kiso, Yoshinobu; Tanaka, Takaharu

    2003-05-01

    In the present study, we investigated the anti-oxidant activity of oolong tea in an oxidation model using human low-density lipoprotein (LDL). Oolong tea suppressed the oxidation of LDL induced by 2-2'-azobis 4-methoxy-2,4-dimethyvaleronitrile (V70) in a dose-dependent manner, that is, it prolonged the lag time to 114.3%, 138% and 199.9% as compared with the control group at 0.5 microg/ml, 1.0 microg/ml, and 2.5 microg/ml, respectively. We also determined the scavenging effect of oolong tea on active oxygen radicals using the electron spin resonance (ESR) technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) as a spin trapping agent. The intensity of the ESR signals for the DMPO-OOH adduct formed by the hypoxanthine/xanthine oxidase reaction system with DMPO decreased in the presence of oolong tea. The IC(50) of oolong tea was 19.9 microg/ml. These findings suggested that oolong tea has beneficial effects on health related to its anti-oxidative action.

  9. Lower low-density lipoprotein cholesterol levels are associated with Parkinson's disease.

    PubMed

    Huang, Xuemei; Chen, Honglei; Miller, William C; Mailman, Richard B; Woodard, Jennifer L; Chen, Peter C; Xiang, Dong; Murrow, Richard W; Wang, Yi-Zhe; Poole, Charles

    2007-02-15

    The apolipoprotein E (APOE) epsilon2 allele has been associated with both Parkinson's disease (PD) and lower low-density lipoprotein cholesterol (LDL-C). We tested the hypothesis that lower LDL-C may be associated with PD. This case-control study used fasting lipid profiles obtained from 124 PD cases and 112 controls. The PD cases were recruited from consecutive cases presenting at our tertiary Movement Disorder Clinic, and the controls were recruited from the spouse populations of the same clinic. Multivariate odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from unconditional logistic regressions, adjusting for age, gender, smoking status, and use of cholesterol-lowering agents. Lower LDL-C concentrations were associated with a higher occurrence of PD. Compared with participants with the highest LDL-C (> or =138 mg/dL), the OR was 2.2 (95% CI = 0.9-5.1) for participants with LDL-C of 115 to 137, 3.5 (95% CI = 1.6-8.1) for LDL-C of 93 to 114, and 2.6 (95% CI = 1.1-5.9) for LDL-C of < or = 92. Interestingly, use of either cholesterol-lowering drugs, or statins alone, was related to lower PD occurrence. Thus, our data provide preliminary evidence that low LDL-C may be associated with higher occurrence of PD, and/or that statin use may lower PD occurrence, either of which finding warrants further investigation.

  10. Low density lipoprotein (LDL)-antioxidant flavonoids from roots of Sophora flavescens.

    PubMed

    Jeong, Tae-Sook; Ryu, Young Bae; Kim, Hoi Young; Curtis-Long, Marcus John; An, Sojin; An, So Jin; Lee, Jin Hwan; Lee, Woo Song; Park, Ki Hun

    2008-11-01

    Oxidation of low density lipoprotein (LDL) is strongly implicated as a key process in the onset of atherosclerosis. In this study, nine alkylated (C10-C5) flavonoids from Sophora flavescens were examined for their inhibitory effects on copper-induced LDL oxidation. Of the flavonoids tested, sophoraflavanone G (1), kurarinone (2), kurarinol (3), norkurarinol (4), and kuraridin (9) inhibited the generation of thiobarbituric acid reactive substances (TBARS) with IC50s of 7.9, 14.5, 22.0, 26.9, and 17.5 microM, respectively. The most potent inhibitor, compound 1, also demonstrated significant activities in complementary in vitro investigations, such as lag time (130 min at 5 microM), relative electrophoretic mobility (REM) of ox-LDL (80% inhibition at 20 microM), and fragmentation of apoB-100 (inhibition of 71% at 20 microM). Analysis of the structures of these compounds reveals that a resorcinol moiety in the B-ring is strongly correlated with protection of LDL-oxidation.

  11. Effects of antihypertensive therapy on platelet cytosolic calcium responses to low density lipoprotein cholesterol.

    PubMed

    Sowers, J R; Raman, B B; Afonso, L C; Bedford-Rice, K; Standley, P R

    1996-03-01

    This study examines the effects of antihypertensive therapy on platelet cytosolic calcium [Ca2+]i responses to low-density lipoprotein cholesterol (LDL) and vasopressin (AVP) in 15 patients (50-80 years) participating in the Hypertension Optimal Treatment International Study. All patients (diastolic blood pressure (DBP) > or = 100 mm Hg and < or = 115 mm Hg) were treated with the calcium antagonist felodipine (10 mg p.o.) with or without addition of enalapril (up to 20 mg daily as needed) to lower diastolic pressures to < 85 mm Hg. This antihypertensive therapy lowered DBP (104 +/- 0.8 to 78 +/- 1.6 mm Hg, P < 0.0001), but had no effect on basal [Ca2+]i or AVP-stimulated [Ca2+]i responses. Basal platelet [Ca2+]i following antihypertensive therapy (49 +/- 3.4 ng/ml) were not different from those prior to therapy (52 +/- 4.7 ng/ml). Additionally, [Ca2+]i responses to AVP following therapy (554 +/- 74 units) were not different from those prior to treatment (595 +/- 49 units). Following antihypertensive therapy, [Ca2+]i responses to 200 micrograms/ml of LDL were decreased fourfold (P < 0.05). These results suggest that antihypertensive therapy with a calcium channel blocker may potentially impact the atherogenic process by reducing the platelet [Ca2+]i rise, and potentially the aggregatory response, to LDL.

  12. Role of low density lipoprotein-bound cholesterol esters in acute lymphoblastic leukemia cells

    SciTech Connect

    Cutts, J.L.; Madden, E.A.; Melnykovych, G.

    1986-05-01

    The glucocorticoid sensitive CEM-C7 T-cell line was derived from human acute lymphoblastic leukemia cells by Norman and Thompson. Madden et al. have demonstrated that this growth inhibitory effect is due in part to a glucocorticoid-mediated inhibition of cholesterol synthesis and can be partially reversed by cholesterol dispersions. To further delineate the role of cholesterol in this growth inhibition, they have examined the ability of low density lipoprotein (LDL)-bound (/sup 3/H)cholesterol linoleate to reverse the growth inhibitory effect of 1 ..mu..M dexamethasone (Dex) on the CEM-C7 cells. LDL-bound cholesterol linoleate was unable to reverse the Dex-mediated growth inhibition, although incorporation of (/sup 14/C) acetate into free cholesterol was inhibited by 29%, following the Brown and Goldstein model. The presence of Dex further inhibited acetate incorporation into free cholesterol in the LDL-treated cells. Under all conditions, more than 99% of the acetate incorporated into cholesterol was present as free cholesterol, while over 87% of the LDL-bound cholesterol linoleate taken up remained in the ester compartment. These results indicate that CEM-C7 cells are unable to utilize LDL-bound cholesterol esters as a source of free cholesterol and rely on endogenous synthesis for their free cholesterol requirements.

  13. Lipopolysaccharide enhances oxidative modification of low density lipoprotein by copper ions, endothelial and smooth muscle cells.

    PubMed

    Maziere, C; Conte, M A; Dantin, F; Maziere, J C

    1999-03-01

    The effect of lipopolysaccharide (LPS, endotoxin) on low density lipoprotein (LDL) oxidative modification by copper ions, endothelial and smooth muscle cells was studied by determination of the level of lipid peroxidation products (thiobarbituric acid reactive substances or TBARS), the diene level and the electrophoretic mobility of the LDL particle. LPS 25-75 microg/ml induced a dose-dependent increase in LDL oxidation by copper ions, endothelial and smooth muscle cells. At 75 microg LPS/ml, the TBARS content was 1.9, 1.6, and 1.8-fold increased, respectively. The LDL degradation by J774 macrophage-like cells was concomitantly stimulated. Preincubation of the LDL particle with LPS induced a marked increase in the subsequent LDL oxidative modification either by copper ions or by endothelial and smooth muscle cells. In addition, pretreatment of endothelial and smooth muscle cells with LPS also induced an enhancement of LDL oxidative modification performed in the absence of LPS. This effect was accompanied by a parallel increase in superoxide anion release by the cells. These results point at one of the mechanisms involved in the described association between bacterial infection and acute myocardial infarction as well as coronary heart disease.

  14. Accumulation of 99mTc-low-density lipoprotein in human malignant glioma.

    PubMed Central

    Leppälä, J.; Kallio, M.; Nikula, T.; Nikkinen, P.; Liewendahl, K.; Jääskeläinen, J.; Savolainen, S.; Gylling, H.; Hiltunen, J.; Callaway, J.

    1995-01-01

    Low-density lipoprotein (LDL) uptake in gliomas was studied to find out if LDL has potential as a drug carrier of boron, especially for boron neutron capture therapy. Single photon emission tomography (SPET) was performed 2 h and 20 h after intravenous injection of autologous 99mTc-labelled LDL in four patients with untreated and five patients with recurrent glioma. 99mTc-LDL uptake was compared with the uptake of 99mTc-labelled human serum albumin (HSA), an established blood pool marker. The intra- and peritumoral distributions of radioactivity in the SPET images were not identical for radiolabelled LDL and HSA. The mean LDL tumour to brain ratio, determined from transversal SPET slices at 20 h post injection, was 1.5 in untreated and 2.2 in recurrent gliomas; the corresponding ratios for HSA were 1.6 and 3.4. The brain to blood ratio remained constant at 2 h and 20 h in both types of tumours. These data are not consistent with highly selective, homogeneous uptake of LDL in gliomas. However, the different tumoral distribution and rate of uptake of 99mTc-LDL, as compared with 99mTc-HSA, indicate that the uptake of LDL is different from that of HSA and that further studies on the mechanism of LDL uptake in glioma are warranted. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:7841057

  15. Macrophage uptake of low-density lipoprotein modified by 4-hydroxynonenal. An ultrastructural study

    SciTech Connect

    Hoff, H.F.; Cole, T.B. )

    1991-02-01

    We have documented the ultrastructural characteristics of the uptake and processing by mouse peritoneal macrophages (MPM) of low-density lipoprotein (LDL) modified with 4-hydroxynonenal (HNE), an intermediate of lipid peroxidation. This was performed as part of a larger biochemical study assessing the role of LDL oxidation in lipid loading of macrophages during atherogenesis. Gold-labeled LDL that was modified with HNE leading to particle aggregation represented the morphologic probe used. When incubated with MPM, the probe became associated with short segments of cell membrane, probably derived from blebs or from lysed cells. At 37 degrees C there was a time-dependent increase in uptake by MPM, and at 4 hours the increase paralleled the degradation by MPM of 125I-labeled HNE-LDL-cAu. Clathrin-coated pits on the cell surface were consistently associated with probe. Uptake of probe appeared to occur via phagocytosis, because pseudopods frequently surrounded probe, and cytochalasin D quantitatively prevented probe uptake. A time-dependent increase was found in the number of gold particles per unit area within vacuoles, some of which were secondary lysosomes, based on acid phosphatase-positive staining. Thus, HNE-induced aggregation of LDL during oxidation, binding of aggregates to clathrin-coated pits on MPM, and subsequent phagocytosis may represent one of the ways lipid-laden foam cells are formed in vivo.

  16. Evidence for the presence of oxidatively modified low density lipoprotein in atherosclerotic lesions of rabbit and man.

    PubMed Central

    Ylä-Herttuala, S; Palinski, W; Rosenfeld, M E; Parthasarathy, S; Carew, T E; Butler, S; Witztum, J L; Steinberg, D

    1989-01-01

    Three lines of evidence are presented that low density lipoproteins gently extracted from human and rabbit atherosclerotic lesions (lesion LDL) greatly resembles LDL that has been oxidatively modified in vitro. First, lesion LDL showed many of the physical and chemical properties of oxidized LDL, properties that differ from those of plasma LDL: higher electrophoretic mobility, a higher density, higher free cholesterol content, and a higher proportion of sphingomyelin and lysophosphatidylcholine in the phospholipid fraction. A number of lower molecular weight fragments of apo B were found in lesion LDL, similar to in vitro oxidized LDL. Second, both the intact apo B and some of the apo B fragments of lesion LDL reacted in Western blots with antisera that recognize malondialdehyde-conjugated lysine and 4-hydroxynonenal lysine adducts, both of which are found in oxidized LDL; plasma LDL and LDL from normal human intima showed no such reactivity. Third, lesion LDL shared biological properties with oxidized LDL: compared with plasma LDL, lesion LDL produced much greater stimulation of cholesterol esterification and was degraded more rapidly by macrophages. Degradation of radiolabeled lesion LDL was competitively inhibited by unlabeled lesion LDL, by LDL oxidized with copper, by polyinosinic acid and by malondialdehyde-LDL, but not by native LDL, indicating uptake by the scavenger receptor(s). Finally, lesion LDL (but not normal intimal LDL or plasma LDL) was chemotactic for monocytes, as is oxidized LDL. These studies provide strong evidence that atherosclerotic lesions, both in man and in rabbit, contain oxidatively modified LDL. Images PMID:2794046

  17. Biological efficacy of boronated low-density lipoprotein for boron neutron capture therapy as measured in cell culture.

    PubMed

    Laster, B H; Kahl, S B; Popenoe, E A; Pate, D W; Fairchild, R G

    1991-09-01

    Low-density lipoproteins (LDLs) are known to be internalized by the cell through receptor-mediated mechanisms. There is evidence that LDLs may be taken up avidly by tumor cells to provide cholesterol for the synthesis of cell membranes. Thus, the possibility exists that LDLs may provide an ideal vehicle for the transport of boron to tumor cells for boron neutron capture therapy. A boronated analogue of LDL has recently been synthesized for possible application in boron neutron capture therapy. The analogue was tested in cell culture for uptake and biological efficacy in the thermal neutron beam at the Brookhaven Medical Research Reactor. It was found that boron concentrations 10 times higher than that required in tumors for boron neutron capture therapy were easily obtained and that the amount of uptake was consistent with a receptor-mediated binding mechanism. The measured intracellular concentration of approximately 240 micrograms 10B/g cells is significantly higher than that obtained with any other boron compound previously evaluated for possible clinical application.

  18. Oxidized low density lipoprotein suppresses lipopolysaccharide-induced inflammatory responses in microglia: Oxidative stress acts through control of inflammation

    SciTech Connect

    Kim, Ohn Soon; Lee, Chang Seok; Joe, Eun-hye; Jou, Ilo . E-mail: jouilo@ajou.ac.kr

    2006-03-31

    Low density lipoprotein (LDL) is readily oxidized under certain conditions, resulting in the formation of oxidized LDL (oxLDL). Despite numerous in vitro reports that reveal the pathogenic role of oxidative stress, anti-oxidative strategies have underperformed in the clinic. In this study, we examine the role of oxLDL in brain inflammatory responses using cultured rat brain microglia. We demonstrate that oxLDL inhibits lipopolysaccharide (LPS)-induced inflammatory responses in these cells. It also decreases LPS-induced expression of inducible nitric oxide synthase and production of nitric oxide, and reduces LPS-induced secretion of tumor necrosis factor-{alpha} and monocyte chemoattractant protein-1. Oxysterols, known components of oxLDL and endogenous agonists of liver X receptor, can simulate the inhibitory effects of oxLDL in LPS-activated microglia. In addition, their inhibitory effects were mimicked by liver X receptor (LXR) agonists and potentiated by a retinoid X receptor agonist, suggesting these molecules heterodimerize to function as oxysterol receptors. Taken together, our results demonstrate that oxLDL inhibits LPS-induced inflammatory responses in brain microglia and that these inhibitory effects are mediated by oxysterols and, at least in part, by the nuclear receptor LXR. Our results suggest an additional mechanism of action for oxidative stress that acts indirectly via modulation of inflammatory responses. Although further studies are needed, these results answer in part the question of why anti-oxidative strategies have not been successful in clinical situations. Moreover, as brain inflammation participates in the initiation and progression of several neurodegenerative disorders, the present data provide information that should prove a useful guide for designing therapeutic strategies to combat oxidative brain diseases.

  19. Accumulation of "small dense" low density lipoproteins (LDL) in a homozygous patients with familial defective apolipoprotein B-100 results from heterogenous interaction of LDL subfractions with the LDL receptor.

    PubMed Central

    März, W; Baumstark, M W; Scharnagl, H; Ruzicka, V; Buxbaum, S; Herwig, J; Pohl, T; Russ, A; Schaaf, L; Berg, A

    1993-01-01

    The interaction of LDL and LDL subfractions from a patient homozygous for familial defective apoB-100 (FDB) has been studied. His LDL cholesterol ranged from 2.65 to 3.34 g/liter. In cultured fibroblasts, binding, internalization, and degradation of the patient's LDL was diminished, but not completely abolished. The patient's apolipoprotein E concentration was low, and the amount of apolipoprotein E associated with LDL was not elevated over normal. LDL were separated into six subfractions: LDL-1 (1.019-1.031 kg/liter), LDL-2 (1.031-1.034 kg/liter), LDL-3 (1.034-1.037 kg/liter), LDL-4 (1.037-1.040 kg/liter), LDL-5 (1.040-1.044 kg/liter), and LDL-6 (> 1.044 kg/liter). LDL-5 and LDL-6 selectively accumulated in the patient's plasma. Concentrations of LDL-1 to 3 were normal. The LDL receptor-mediated uptake of LDL-1 and LDL-2 could not be distinguished from normal LDL. LDL-3 and LDL-4 displayed reduced uptake; LDL-5 and LDL-6 were completely defective in binding. When apolipoprotein E-containing particles were removed by immunoabsorption before preparing subfractions, LDL-3 and LDL-4, but not LDL-1 and LDL-2, retained some receptor binding activity. We conclude that in FDB, LDL-1 and LDL-2 contain sufficient apolipoprotein E to warrant normal cellular uptake. In LDL-3 and LDL-4, the defective apoB-100 itself displays some receptor binding; LDL-5 and LDL-6 are inable to interact with LDL receptors and accumulate in plasma. Images PMID:8254047

  20. Role of endogenous ceruloplasmin in low density lipoprotein oxidation by human U937 monocytic cells.

    PubMed Central

    Ehrenwald, E; Fox, P L

    1996-01-01

    Oxidation of lipids and lipoproteins by macrophages is an important event during atherogenesis. Activation of monocytic cells by zymosan and other agonists results in the release of multiple oxidant species and consequent oxidation of LDL. We now show evidence that ceruloplasmin, a copper-containing acute phase reactant, is secreted by zymosan-activated U937 monocytic cells, and that the protein has an important role in LDL oxidation by these cells. In one approach, ceruloplasmin has been shown to exhibit oxidant activity under the appropriate conditions. Exogenous addition of purified human ceruloplasmin stimulates U937 cell oxidation of LDL to nearly the same extent as activation by zymosan. In contrast to previous cell-free experiments (Ehrenwald, E., G.M. Chisom, and P.L. Fox. 1994. Intact human ceruloplasmin oxidatively modifies low density lipoprotein. J. Clin. Invest. 93:1493-1501.) in which ceruloplasmin by itself (in PBS) oxidizes LDL, under the conditions of the current experiments (in RPMI 1640 medium) ceruloplasmin only oxidizes LDL in the presence of cells; the mechanism by which cells overcome the inhibition by medium components has not been ascertained. As further evidence for a role of ceruloplasmin, activation of U937 cells with zymosan induces ceruloplasmin mRNA and ceruloplasmin protein synthesis after a 5-6 h lag that is consistent with that preceding LDL oxidation. Finally, neutralization by a highly specific polyclonal antibody to human ceruloplasmin inhibits LDL oxidation by at least 65%. Moreover, multiple antisense oligodeoxynucleotides targeted to different regions of the ceruloplasmin mRNA block LDL oxidation by up to 95%. The specific action of the antisense oligonucleotides has been verified by showing inhibition of ceruloplasmin synthesis and by the ability of exogenous ceruloplasmin to overcome the inhibition. In summary, these results are consistent with a mechanism in which cell-derived ceruloplasmin participates in oxidation of LDL

  1. Cholesteryl Ester Hydroperoxides Are Biologically Active Components of Minimally Oxidized Low Density Lipoprotein*S⃞

    PubMed Central

    Harkewicz, Richard; Hartvigsen, Karsten; Almazan, Felicidad; Dennis, Edward A.; Witztum, Joseph L.; Miller, Yury I.

    2008-01-01

    Oxidation of low density lipoprotein (LDL) occurs in vivo and significantly contributes to the development of atherosclerosis. An important mechanism of LDL oxidation in vivo is its modification with 12/15-lipoxygenase (LO). We have developed a model of minimally oxidized LDL (mmLDL) in which native LDL is modified by cells expressing 12/15LO. This mmLDL activates macrophages inducing membrane ruffling and cell spreading, activation of ERK1/2 and Akt signaling, and secretion of proinflammatory cytokines. In this study, we found that many of the biological activities of mmLDL were associated with cholesteryl ester (CE) hydroperoxides and were diminished by ebselen, a reducing agent. Liquid chromatography coupled with mass spectroscopy demonstrated the presence of many mono- and polyoxygenated CE species in mmLDL but not in native LDL. Nonpolar lipid extracts of mmLDL activated macrophages, although to a lesser degree than intact mmLDL. The macrophage responses were also induced by LDL directly modified with immobilized 12/15LO, and the nonpolar lipids extracted from 12/15LO-modified LDL contained a similar set of oxidized CE. Cholesteryl arachidonate modified with 12/15LO also activated macrophages and contained a similar collection of oxidized CE molecules. Remarkably, many of these oxidized CE were found in the extracts of atherosclerotic lesions isolated from hyperlipidemic apoE–/– mice. These results suggest that CE hydroperoxides constitute a class of biologically active components of mmLDL that may be relevant to proinflammatory activation of macrophages in atherosclerotic lesions. PMID:18263582

  2. Serum low-density lipoprotein levels, statin use, and cognition in patients with coronary artery disease

    PubMed Central

    Rej, Soham; Saleem, Mahwesh; Herrmann, Nathan; Stefatos, Anthi; Rau, Allison; Lanctôt, Krista L

    2016-01-01

    Aim Statins have been associated with decreased cognition due to the effects of low concentrations of low-density lipoprotein (LDL) on brain function. This has remained controversial and is particularly relevant to patients with coronary artery disease (CAD), who have an increased risk of cognitive decline and are frequently prescribed statins. This study hypothesized that low concentration of LDL is associated with poor cognition in CAD patients using statins. It also explored the association between high-dose versus low-dose statins on cognition in this population. Patients and methods Baseline cross-sectional data from a longitudinal study of 120 statin-using CAD patients were examined (mean statin duration 25±43 months). The main outcomes were measures of global cognition and cognitive domains, with poor cognition defined as cognitive performance ≤1 standard deviation below the population age and education adjusted means. A battery of cognitive tests was used to assess verbal memory, executive function, speed of processing, visuospatial memory, and global cognition. Adjusting for age, sex, education, and other covariates, multivariable logistic regression analyses assessed associations between low LDL levels (<1.5 mmol/L), statin use, and poor cognition. Results LDL levels were not associated with global cognition or individual cognitive domains. High-dose statin use was associated with higher visuospatial memory (odds ratio, OR [95% confidence interval, CI] =0.12 [0.02–0.66], P=0.01) and executive functioning (OR =0.25 [0.06–0.99], P=0.05). This effect was independent of covariates such as LDL levels. Conclusion Low LDL levels do not appear to be associated with poor cognition in CAD patients using statins. Whether high-dose statin use may have positive effects on cognition in CAD patients could be investigated in future studies. PMID:27877045

  3. Low Density Lipoprotein and Non-Newtonian Oscillating Flow Biomechanical Parameters for Normal Human Aorta

    PubMed Central

    Soulis, Johannes V.; Fytanidis, Dimitrios K.; Lampri, Olga P.; Giannoglou, George D.

    2016-01-01

    Background The temporal variation of the hemodynamic mechanical parameters during cardiac pulse wave is considered as an important atherogenic factor. Applying non-Newtonian blood molecular viscosity simulation is crucial for hemodynamic analysis. Understanding low density lipoprotein (LDL) distribution in relation to flow parameters will possibly spot the prone to atherosclerosis aorta regions. Methods The biomechanical parameters tested were averaged wall shear stress (AWSS), oscillatory shear index (OSI) and relative residence time (RRT) in relation to the LDL concentration. Four non-Newtonian molecular viscosity models and the Newtonian one were tested for the normal human aorta under oscillating flow. The analysis was performed via computational fluid dynamic. Results Tested viscosity blood flow models for the biomechanical parameters yield a consistent aorta pattern. High OSI and low AWSS develop at the concave aorta regions. This is most noticeable in downstream flow region of the left subclavian artery and at concave ascending aorta. Concave aorta regions exhibit high RRT and elevated LDL. For the concave aorta site, the peak LDL value is 35.0% higher than its entrance value. For the convex site, it is 18.0%. High LDL endothelium regions located at the aorta concave site are well predicted with high RRT. Conclusions We are in favor of using the non-Newtonian power law model for analysis. It satisfactorily approximates the molecular viscosity, WSS, OSI, RRT and LDL distribution. Concave regions are mostly prone to atherosclerosis. The flow biomechanical factor RRT is a relatively useful tool for identifying the localization of the atheromatic plaques of the normal human aorta. PMID:28197271

  4. Utilization of ascites plasma very low density lipoprotein triglycerides by Ehrlich cells.

    PubMed

    Brenneman, D E; Spector, A A

    1974-07-01

    Much of the lipid present in the ascites plasma in which Ehrlich cells grow is contained in very low density lipoproteins (VLDL). Chemical measurements indicated that triglycerides were taken up by the cells during in vitro incubation with ascites VLDL. When tracer amounts of radioactive triolein were incorporated into the ascites VLDL, the percentage uptakes of glyceryl tri[1-(14)C]oleate and triglycerides measured chemically were similar. The cells also took up [2-(3)H]glyceryl trioleate that was added to VLDL, but the percentage of available (3)H recovered in the cell lipids was 30-40% less than that of (1 4)C from glyceryl tri[1-(1 4)C]oleate. This difference was accounted for by water-soluble (3)H that accumulated in the incubation medium, suggesting that extensive hydrolysis accompanied the uptake of VLDL triglycerides. Radioactive fatty acids derived from the VLDL triglycerides were incorporated into cell phospholipids, glycerides, and free fatty acids, and they also were oxidized to CO(2). Triglyceride utilization increased as the VLDL concentration was raised. These results suggest that one function of the ascites plasma VLDL may be to supply fatty acid to the Ehrlich cells and that the availability of fatty acid to this tumor is determined in part by the ascites plasma VLDL concentration. Although Ehrlich cells incorporate almost no free glycerol into triglycerides, considerable amounts of [2-(3)H]glyceryl trioleate radioactivity were recovered in cell triglycerides. This indicates that at least some VLDL triglycerides were taken up intact. The net uptake of VLDL protein and cholesterol was very small relative to the triglyceride uptake, suggesting that intact triglycerides are transferred from the ascites VLDL to the Ehrlich cells and that hydrolysis occurs after the triglyceride is associated with the cells.

  5. Adrenal imaging with technetium-99m-labelled low density lipoproteins

    SciTech Connect

    Isaacsohn, J.L.; Lees, A.M.; Lees, R.S.; Kovach, M.B.; Strauss, H.W.

    1984-01-01

    Plasma low density lipoproteins (LDL) are a major source of cholesterol for adrenal cortical steroid hormones synthesis. To test whether LDL labelled with Tc-99m could be used to assess adrenal cortical function, the authors prepared Tc-99m-LDL by dithionite reduction of Tc0/sub 4//sup -/ in the presence of LDL. About 80% of the Tc-LDL bonds were covalent. Purified Tc-99m-LDL was injected intravenously into 16 rabbits (4 t 8mCi/rabbit). External imaging was carried out 16 to 18 hrs later, at which time the adrenals were visualized clearly; the animals were sacrificed, the organs dissected out, weighed, and counted. The biodistribution demonstrated that 0.8l +- 0.19% of the injected radioactivity was taken up per gm of whole adrenal gland. This compared with an uptake of 0.19 +- 0.02% per gm by liver, 0.22 +- 0.04% per gm by spleen, and 0.11 +- 0.02% per gm by kidney. To verify that they were indeed imaging the adrenals, additional rabbits were tested with dexamethasone. First they were injected with Tc-99m-LDL; 28 hrs later the adrenals were again well visualized. Then the rabbits were given dexamethasone for 5 days to suppress adrenal cortical function. The adequacy of suppression was monitored by serum cortisol measurements. When Tc-99m-LDL was injected again, the adrenals could not be seen 18 hrs later. Counts of the adrenals from the suppressed rabbits were at background levels. These data indicate that Tc-99m-LDL is a useful radiopharmaceutical for evaluating adrenal cortical function.

  6. Protection of low density lipoprotein oxidation at chemical and cellular level by the antioxidant drug dipyridamole.

    PubMed Central

    Iuliano, L.; Colavita, A. R.; Camastra, C.; Bello, V.; Quintarelli, C.; Alessandroni, M.; Piovella, F.; Violi, F.

    1996-01-01

    1. The oxidative modification of low density lipoprotein (LDL) is thought to be an important factor in the initiation and development of atherosclerosis. Natural and synthetic antioxidants have been shown to protect LDL from oxidation and to inhibit atherosclerosis development in animals. Synthetic antioxidants are currently being tested, by they are not necessarily safe for human use. 2. We have previously reported that dipyridamole, currently used in clinical practice, is a potent scavenger of free radicals. Thus, we tested whether dipyridamole could affect LDL oxidation at chemical and cellular level. 3. Chemically induced LDL oxidation was made by Cu(II), Cu(II) plus hydrogen peroxide or peroxyl radicals generated by thermolysis of 2,2'-azo-bis(2-amidino propane). Dipyridamole, (1-10 microM), inhibited LDL oxidation as monitored by diene formation, evolution of hydroperoxides and thiobarbituric acid reactive substances, apoprotein modification and by the fluorescence of cis-parinaric acid. 4. The physiological relevance of the antioxidant activity was validated by experiments at the cellular level where dipyridamole inhibited endothelial cell-mediated LDL oxidation, their degradation by monocytes, and cytotoxicity. 5. In comparison with ascorbic acid, alpha-tocopherol and probucol, dipyridamole was the more efficient antioxidant with the following order of activity: dipyridamole > probucol > ascorbic acid > alpha-tocopherol. The present study shows that dipyridamole inhibits oxidation of LDL at pharmacologically relevant concentrations. The inhibition of LDL oxidation is unequivocally confirmed by use of three different methods of chemical oxidation, by several methods of oxidation monitoring, and the pharmacological relevance is demonstrated by the superiority of dipyridamole over the naturally occurring antioxidants, ascorbic acid and alpha-tocopherol and the synthetic antioxidant probucol. Images Figure 6 PMID:8968553

  7. Core lipid structure is a major determinant of the oxidative resistance of low density lipoprotein.

    PubMed Central

    Schuster, B; Prassl, R; Nigon, F; Chapman, M J; Laggner, P

    1995-01-01

    The influence of thermally induced changes in the lipid core structure on the oxidative resistance of discrete, homogeneous low density lipoprotein (LDL) subspecies (d, 1.0297-1.0327 and 1.0327-1.0358 g/ml) has been evaluated. The thermotropic transition of the LDL lipid core at temperatures between 15 degrees C and 37 degrees C, determined by differential scanning calorimetry, exerted significant effects on the kinetics of copper-mediated LDL oxidation expressed in terms of intrinsic antioxidant efficiency (lag time) and diene production rate. Thus, the temperature coefficients of oxidative resistance and maximum oxidation rate showed break points at the core transition temperature. Temperature-induced changes in copper binding were excluded as the molecular basis of such effects, as the saturation of LDL with copper was identical below and above the core transition. At temperatures below the transition, the elevation in lag time indicated a greater resistance to oxidation, reflecting a higher degree of antioxidant protection. This effect can be explained by higher motional constraints and local antioxidant concentrations, the latter resulting from the freezing out of antioxidants from crystalline domains of cholesteryl esters and triglycerides. Below the transition temperature, the conjugated diene production rate was decreased, a finding that correlated positively with the average size of the cooperative units of neutral lipids estimated from the calorimetric transition width. The reduced accessibility and structural hindrance in the cluster organization of the core lipids therefore inhibits peroxidation. Our findings provide evidence for a distinct effect of the dynamic state of the core lipids on the oxidative susceptibility of LDL and are therefore relevant to the atherogenicity of these cholesterol-rich particles. PMID:7708675

  8. Very low density lipoprotein metabolism in non-ketotic diabetes mellitus: effect of dietary restriction.

    PubMed

    Ginsberg, H; Grundy, S M

    1982-11-01

    We have measured the turnover of very low density lipoprotein (VLDL) triglyceride as well as plasma glucose, insulin and non-esterified fatty acid levels in nine mildly obese non-ketotic, insulinopenic diabetic subjects before and during an energy restricted diet. During the baseline period, subjects were hypertriglyceridaemic, hyperglycaemic and insulinopenic. During dietary restriction (mean weight loss: 2.3 +/- 0.4 kg) plasma triglyceride fell from 8.4 +/- 3.0 to 3.4 +/- 0.89 mmol/l (mean +/- SEM: p less than 0.05), and plasma glucose fell from 13.9 +/- 1.7 to 9.8 +/- 1.4 mmol/l (p less than 0.01). Neither fasting plasma insulin nor the insulin response to an oral glucose load changed. Plasma non-esterified fatty acid concentrations remained constant as well. During the baseline period, the transport rate of VLDL-triglyceride in the diabetic subjects was more than twice that in an age-weighted matched control group (27.4 +/- 2.9 versus 12.1 +/- 0.8 mg/kg ideal body weight per h). The fractional catabolic rates were similar in the two groups (0.20 +/- 0.05 versus 0.21 +/- 0.02/h). During energy restriction of the diabetic subjects, the VLDL-triglyceride transport rate fell to 17.4 +/- 2.9 mg/kg ideal body weight per h (p less than 0.05 versus baseline) while the fractional catabolic rate remained constant at 0.21 +/- 0.06/h (NS versus baseline). These data indicate that the major abnormality in triglyceride metabolism in these non-ketotic, insulinopenic diabetic patients was over-production of VLDL-triglyceride.

  9. Polyunsaturated fatty acid enrichment enhances endothelial cell-induced low-density-lipoprotein peroxidation.

    PubMed Central

    Mazière, C; Dantin, F; Conte, M A; Degonville, J; Ali, D; Dubois, F; Mazière, J C

    1998-01-01

    Oxidative modification of low-density lipoprotein (LDL) is an important feature in the initiation and progression of atherosclerosis. LDL modification by endothelial cells was studied after supplementation of the cells with oleic acid and polyunsaturated fatty acids (PUFA) of the n-6 and n-3 series. In terms of the lipid peroxidation product [thiobarbituric acid reactive substances (TBARS)] content and diene level of the LDL particle, oleic acid had no significant effect, and linoleic acid was poorly effective. Gamma linolenic acid (C18:3,n-6) and arachidonic acid (C20:4,n-6) increased by about 1.6-1.9-fold the cell-mediated LDL modification. PUFA from the n-3 series, alpha linolenic acid (C18:3,n-3), eicosapentaenoic acid (C20:5,n-3) and docosahexaenoic acid (C22:6,n-3), induced a less marked effect (1. 3-1.6-fold increase). The relative electrophoretic mobility of the LDL particle and its degradation by macrophages were enhanced in parallel. Concomitantly, PUFA stimulated superoxide anion secretion by endothelial cells. The intracellular TBARS content was also increased by PUFA. Comparison of PUFA from the two series indicates a good correlation between LDL oxidative modification, superoxide anion secretion and intracellular lipid peroxidation. The lipophilic antioxidant vitamin E decreased the basal as well as the PUFA-stimulated LDL peroxidation. These results indicate that PUFAs with a high degree of unsaturation of the n-6 and n-3 series could accelerate cell-mediated LDL peroxidation and thus aggravate the atherosclerotic process. PMID:9806884

  10. Characterization of the structure of polydisperse human low-density lipoprotein by neutron scattering.

    PubMed

    Meyer, D F; Nealis, A S; Bruckdorfer, K R; Perkins, S J

    1995-09-01

    Low-density lipoproteins (LDL) in plasma are constructed from a single molecule of apolipoprotein B-100 (M(r) 512000) in association with lipid (approximate M(r) 2-3 x 10(6)). The gross structure was studied using an updated pulsed-neutron camera LOQ with an area detector to establish the basis for the interpretation of structural changes seen during dynamic studies of LDL oxidation. Neutron-scattering data for LDL in 100% 2H2O buffers emphasize their external appearance. Guinier analysis on a continuous-flux neutron camera D17 revealed pronounced concentration-dependences in the radius of gyration, RG, and the intensity of forward scattering, I(0) (equivalent to the M(r) of LDL) between 0.5 and 11 mg of LDL protein/ml. LDL preparations from different donors gave different RG values. When extrapolated to zero concentration, RG values ranged between 8.3 and 10.6 nm and were linearly correlated with M(r), which is consistent with a spherical structure. The distance-distribution function P(r) in real space showed a single maximum at 9.1-10.9 nm, which is just under half the observed maximum dimension of 23.1 +/- 1.2 nm expected for a spherical structure. The neutron radial-density function p(r) exhibited a plateau of high and featureless density at the centre of LDL. LDL can be modelled by a polydisperse assembly of spheres with two internal densities and a mean radius close to 10.0 nm in a normal distribution of radii with a standard deviation of 2.0 nm. The data are consistent with recent electron-microscopy and ultracentrifugation data.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Carbamylated low-density lipoprotein induces oxidative stress and accelerated senescence in human endothelial progenitor cells.

    PubMed

    Carracedo, Julia; Merino, Ana; Briceño, Carolina; Soriano, Sagrario; Buendía, Paula; Calleros, Laura; Rodriguez, Mariano; Martín-Malo, Alejandro; Aljama, Pedro; Ramírez, Rafael

    2011-04-01

    Carbamylated low-density lipoprotein (cLDL) plays a role in atherosclerosis. In this study we evaluate the effect of uremia on LDL carbamylation and the effect of cLDL and oxidized LDL (oxLDL; 200 μg/ml) on number, function, and genomic stability of endothelial progenitor cells (EPCs) obtained from healthy volunteers. cLDL was generated after incubation of native LDL (nLDL) with uremic serum from patients with chronic kidney disease (CKD) stages 2-4. Oxidative stress was measured by flow cytometry and fluorescent microscopy, mitochondrial depolarization by flow cytometry, senescence by β-galactosidase activity and telomere length, and DNA damage by phosphorylated histone H2AX (γH2AX). The percentage of cLDL by uremic serum was related to the severity of CKD. Compared with nLDL, cLDL induced an increase in oxidative stress (62±5 vs. 8±3%, P<0.001) and cells with mitochondrial depolarization (73±7 vs. 9±5%, P<0.001), and a decrease in EPC proliferation and angiogenesis. cLDL also induced accelerated senescence (73±16 vs. 12±9%, P<0.001), which was associated with a decrease in the expression of γH2AX (62±9 vs. 5±3%, P<0.001). The degree of injury induced by cLDL was comparable to that observed with oxLDL. This study supports the hypothesis that cLDL triggers genomic damage in EPCs, resulting in premature senescence. We can, therefore, hypothesize that EPCs injury by cLDL contributes to an increase in atherosclerotic disease in CKD.

  12. Oxidized low-density lipoprotein as a delivery system for photosensitizers: implications for photodynamic therapy of atherosclerosis.

    PubMed

    de Vries, H E; Moor, A C; Dubbelman, T M; van Berkel, T J; Kuiper, J

    1999-04-01

    Photodynamic therapy is a promising new strategy in the treatment of cardiovascular diseases. Photodynamic therapy for vascular diseases may be improved by the specific delivery of photosensitizers to the atherosclerotic lesion. In this study, we studied whether oxidatively modified low-density lipoprotein (OxLDL) could be used as a specific carrier for photosensitizers, thereby using the scavenger receptor expressed on macrophages as a target. The photosensitizer aluminum phthalocyanine chloride (AlPc) was incorporated into OxLDL, and its photodynamic effects were studied. Macrophages (RAW 264.7) were incubated with various concentrations of OxLDL-AlPc for different periods. After illumination of the cells with red light, cytotoxicity was observed that was dependent on the time of illumination and incubation. Macrophages incubated with OxLDL-AlPc that were not illuminated revealed no cytotoxicity. The uptake of the OxLDL-AlPc complexes was mediated by scavenger receptors expressed on macrophages. In the presence of the polyanion polyinosinic acid, a specific ligand for scavenger receptors, no cytotoxicity could be observed. Serum incubations of the OxLDL-AlPc complexes revealed that these complexes stay intact after incubation. No redistribution of AlPc to other plasma (lipo-) proteins could be detected, and 80-90% of the AlPc remained associated with the OxLDL particle. These results indicate that OxLDL may function as a specific delivery system for photosensitizers to the scavenger receptors expressed on the macrophages in the atherosclerotic lesion, increasing the beneficial effects of photodynamic therapy for cardiovascular diseases.

  13. Binding of α2ML1 to the Low Density Lipoprotein Receptor-Related Protein 1 (LRP1) Reveals a New Role for LRP1 in the Human Epidermis

    PubMed Central

    Galliano, Marie-Florence; Toulza, Eve; Jonca, Nathalie; Gonias, Steven L.; Serre, Guy; Guerrin, Marina

    2008-01-01

    Background The multifunctional receptor LRP1 has been shown to bind and internalize a large number of protein ligands with biological importance such as the pan-protease inhibitor α2-macroglobulin (α2M). We recently identified Α2ML1, a new member of the α2M gene family, expressed in epidermis. α2ML1 might contribute to the regulation of desquamation through its inhibitory activity towards proteases of the chymotrypsin family, notably KLK7. The expression of LRP1 in epidermis as well as its ability to internalize α2ML1 was investigated. Methods and Principal Findings In human epidermis, LRP1 is mainly expressed within the granular layer of the epidermis, which gathers the most differentiated keratinocytes, as shown by immunohistochemistry and immunofluorescence using two different antibodies. By using various experimental approaches, we show that the receptor binding domain of α2ML1 (RBDl) is specifically internalized into the macrophage-like cell line RAW and colocalizes with LRP1 upon internalization. Coimmunoprecipitation assays demonstrate that RBDl binds LRP1 at the cell surface. Addition of RAP, a universal inhibitor of ligand binding to LRP1, prevents RBDl binding at the cell surface as well as internalization into RAW cells. Silencing Lrp1 expression with specific siRNA strongly reduces RBDl internalization. Conclusions and Significance Keratinocytes of the upper differentiated layers of epidermis express LRP1 as well as α2ML1. Our study also reveals that α2ML1 is a new ligand for LRP1. Our findings are consistent with endocytosis by LRP1 of complexes formed between α2ML1 and proteases. LRP1 may thus control desquamation by regulating the biodisponibility of extracellular proteases. PMID:18648652

  14. The internal region leucine-rich repeat 6 of decorin interacts with low density lipoprotein receptor-related protein-1, modulates transforming growth factor (TGF)-β-dependent signaling, and inhibits TGF-β-dependent fibrotic response in skeletal muscles.

    PubMed

    Cabello-Verrugio, Claudio; Santander, Cristian; Cofré, Catalina; Acuña, Maria José; Melo, Francisco; Brandan, Enrique

    2012-02-24

    Decorin is a small proteoglycan, composed of 12 leucine-rich repeats (LRRs) that modulates the activity of transforming growth factor type β (TGF-β) and other growth factors, and thereby influences proliferation and differentiation in a wide array of physiological and pathological processes, such as fibrosis, in several tissues and organs. Previously we described two novel modulators of the TGF-β-dependent signaling pathway: LDL receptor-related protein (LRP-1) and decorin. Here we have determined the regions in decorin that are responsible for interaction with LRP-1 and are involved in TGF-β-dependent binding and signaling. Specifically, we used decorin deletion mutants, as well as peptides derived from internal LRR regions, to determine the LRRs responsible for these decorin functions. Our results indicate that LRR6 and LRR5 participate in the interaction with LRP-1 and TGF-β as well as in its dependent signaling. Furthermore, the internal region (LRR6i), composed of 11 amino acids, is responsible for decorin binding to LRP-1 and subsequent TGF-β-dependent signaling. Furthermore, using an in vivo approach, we also demonstrate that the LRR6 region of decorin can inhibit TGF-β mediated action in response to skeletal muscle injury.

  15. The Internal Region Leucine-rich Repeat 6 of Decorin Interacts with Low Density Lipoprotein Receptor-related Protein-1, Modulates Transforming Growth Factor (TGF)-β-dependent Signaling, and Inhibits TGF-β-dependent Fibrotic Response in Skeletal Muscles*

    PubMed Central

    Cabello-Verrugio, Claudio; Santander, Cristian; Cofré, Catalina; Acuña, Maria José; Melo, Francisco; Brandan, Enrique

    2012-01-01

    Decorin is a small proteoglycan, composed of 12 leucine-rich repeats (LRRs) that modulates the activity of transforming growth factor type β (TGF-β) and other growth factors, and thereby influences proliferation and differentiation in a wide array of physiological and pathological processes, such as fibrosis, in several tissues and organs. Previously we described two novel modulators of the TGF-β-dependent signaling pathway: LDL receptor-related protein (LRP-1) and decorin. Here we have determined the regions in decorin that are responsible for interaction with LRP-1 and are involved in TGF-β-dependent binding and signaling. Specifically, we used decorin deletion mutants, as well as peptides derived from internal LRR regions, to determine the LRRs responsible for these decorin functions. Our results indicate that LRR6 and LRR5 participate in the interaction with LRP-1 and TGF-β as well as in its dependent signaling. Furthermore, the internal region (LRR6i), composed of 11 amino acids, is responsible for decorin binding to LRP-1 and subsequent TGF-β-dependent signaling. Furthermore, using an in vivo approach, we also demonstrate that the LRR6 region of decorin can inhibit TGF-β mediated action in response to skeletal muscle injury. PMID:22203668

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

    SciTech Connect

    Tompkins, R.G.; Schnitzer, J.J.; Yarmush, M.L.; Colton, C.K.; Smith, K.A.

    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 lower 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.

  17. Tartaric Acid-based Amphiphilic Macromolecules with Ether Linkages Exhibit Enhanced Repression of Oxidized Low Density Lipoprotein Uptake

    PubMed Central

    Abdelhamid, Dalia; Zhang, Yingue; Lewis, Daniel R.; Moghe, Prabhas V.; Welsh, William J.; Uhrich, Kathryn E.

    2015-01-01

    Cardiovascular disease initiates with the atherogenic cascade of scavenger receptor- (SR-) mediated oxidized low-density lipoprotein (oxLDL) uptake. Resulting foam cell formation leads to lipid-rich lesions within arteries. We designed amphiphilic macromolecules (AMs) to inhibit these processes by competitively blocking oxLDL uptake via SRs, potentially arresting atherosclerotic development. In this study, we investigated the impact of replacing ester linkages with ether linkages in the AM hydrophobic domain. We hypothesized that ether linkages would impart flexibility for orientation to improve binding to SR binding pockets, enhancing anti-atherogenic activity. A series of tartaric acid-based AMs with varying hydrophobic chain lengths and conjugation chemistries were synthesized, characterized, and evaluated for bioactivity. 3-D conformations of AMs in aqueous conditions may have significant effects on anti-atherogenic potency and were simulated by molecular modeling. Notably, ether-linked AMs exhibited significantly higher levels of inhibition of oxLDL uptake than their corresponding ester analogues, indicating a dominant effect of linkage flexibility on pharmacological activity. The degradation stability was also enhanced for ether-linked AMs. These studies further suggested that alkyl chain length (i.e., relative hydrophobicity), conformation (i.e., orientation), and chemical stability play a critical role in modulating oxLDL uptake, and guide the design of innovative cardiovascular therapies. PMID:25890704

  18. Nonstatin Low-Density Lipoprotein-Lowering Therapy and Cardiovascular Risk Reduction-Statement From ATVB Council.

    PubMed

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

    2015-11-01

    Pharmacological 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 nonstatin therapies that also reduce LDL cholesterol in prevention of CVD. Among conventional nonstatins, 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, whereas adding a fibrate or niacin showed no incremental benefit. Among emerging nonstatins, monoclonal antibodies against proprotein convertase subtilisin kexin type 9 added to a statin and given for ≤78 weeks showed preliminary evidence of reductions in CVD outcomes. Although these promising early findings contributed to the recent approval of these agents in Europe and in North America, much larger and longer duration outcomes studies are ongoing for definitive proof of CVD benefits. Other nonstatin agents recently approved in the United States 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 toward more assertive LDL-lowering treatment, using both statins and nonstatins initiated earlier in appropriately selected patients.

  19. The M2 module of the Cys-His-rich domain (CHRD) of PCSK9 protein is needed for the extracellular low-density lipoprotein receptor (LDLR) degradation pathway.

    PubMed

    Saavedra, Yascara Grisel Luna; Day, Robert; Seidah, Nabil G

    2012-12-21

    PCSK9 enhances the cellular degradation of the LDL receptor (LDLR), leading to increased plasma LDL cholesterol. This multidomain protein contains a prosegment, a catalytic domain, a hinge region, and a cysteine-histidine rich domain (CHRD) composed of three tightly packed modules named M1, M2, and M3. The CHRD is required for the activity of PCSK9, but the mechanism behind this remains obscure. To define the contribution of each module to the function of PCSK9, we dissected the CHRD structure. Six PCSK9 deletants were generated by mutagenesis, corresponding to the deletion of only one (ΔM1, ΔM2, ΔM3) or two (ΔM12, ΔM13, ΔM23) modules. Transfection of HEK293 cells showed that all deletants were well processed and expressed compared with the parent PCSK9 but that only those lacking the M2 module were secreted. HepG2 cells lacking endogenous PCSK9 (HepG2/shPCSK9) were used for the functional analysis of the extracellular or intracellular activity of PCSK9 and its deletants. To analyze the ability of the deletants to enhance the LDLR degradation by the intracellular pathway, cellular expressions revealed that only the ΔM2 deletant retains a comparable total LDLR-degrading activity to full-length PCSK9. To probe the extracellular pathway, HepG2/shPCSK9 cells were incubated with conditioned media from transfected HEK293 or HepG2/shPCSK9 cells, and cell surface LDLR levels were analyzed by FACS. The results showed no activity of any secreted deletant compared with PCSK9. Thus, although M2 is dispensable for secretion, its presence is required for the extracellular activity of PCSK9 on cell surface LDLR.

  20. Hyaluronic acid receptor for endocytosis (HARE)-mediated endocytosis of hyaluronan, heparin, dermatan sulfate, and acetylated low density lipoprotein (AcLDL), but not chondroitin sulfate types A, C, D, or E, activates NF-κB-regulated gene expression.

    PubMed

    Pandey, Madhu S; Weigel, Paul H

    2014-01-17

    The hyaluronan (HA) receptor for endocytosis (HARE; Stab2) clears 14 systemic ligands, including HA and heparin. Here, we used NF-κB promoter-driven luciferase reporter assays to test HARE-mediated intracellular signaling during the uptake of eight ligands, whose binding sites in the HARE ectodomain were mapped by competition studies (Harris, E. N., and Weigel, P. H. (2008) Glycobiology 18, 638-648). Unique intermediate size Select-HA(TM), heparin, dermatan sulfate, and acetylated LDL stimulated dose-dependent HARE-mediated NF-κB activation of luciferase expression, with half-maximal values of 10-25 nM. In contrast, chondroitin sulfate types A, C, D, and E did not stimulate NF-κB activation. Moreover, degradation of endogenous IkB-α (an NF-κB inhibitor) was stimulated only by the signaling ligands. The stimulatory activities of pairwise combinations of the four signaling ligands were additive. The four nonstimulatory chondroitin sulfate types, which compete for HA binding, also effectively blocked HA-stimulated signaling. Clathrin siRNA decreased clathrin expression by ∼50% and completely eliminated NF-κB-mediated signaling by all four ligands, indicating that activation of signaling complexes occurs after endocytosis. These results indicate that HARE not only binds and clears extracellular matrix degradation products (e.g. released normally or during infection, injury, tumorigenesis, or other stress situations) but that a subset of ligands also serves as signaling indicator ligands. HARE may be part of a systemic tissue-stress sensor feedback system that responds to abnormal tissue turnover or damage as a danger signal; the signaling indicator ligands would reflect the homeostatic status, whether normal or pathological, of tissue cells and biomatrix components.

  1. A phagocytosis assay for oxidized low-density lipoprotein versus immunoglobulin G-coated microbeads in human U937 macrophages.

    PubMed

    Vance, David T; Dufresne, Jaimie; Florentinus-Mefailoski, Angelique; Tucholska, Monika; Trimble, William; Grinstein, Sergio; Marshall, John G

    2016-05-01

    The human monocyte cell line U937 was differentiated into an adherent macrophage phenotype using phorbol 12-myristate 13-acetate (PMA) to assay the phagocytosis of oxidized low-density lipoprotein (oxLDL) that may play a role in atherosclerosis. Microbeads were coated with the inflammatory ligand oxLDL to create a novel phagocytosis assay that models the binding of macrophages to oxLDL in the solid phase such as found in the fatty streaks of the arteries. The oxLDL was prepared with LDL from human ethylenediaminetetraacetic acid (EDTA) plasma oxidized with an excess (5 mM) of the strong oxidizing agent CuSO4 and characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis with Western blot. The binding of the oxLDL to the beads was confirmed by DilC18-oxLDL staining and confocal microscopy in addition to trypsin digestion of the microbeads for liquid chromatography, electrospray ionization, and tandem mass spectrometry. Phagocytosis of the oxLDL versus human bulk immunoglobulin G1 (IgG1)-coated microbeads was assayed over time, in the presence and absence of serum factors, by pulse chase and with enzyme inhibitor treatments. The ligand beads were then stained with specific antibodies to oxLDL versus human IgG to differentially stain external versus engulfed ligand microbeads. The phagocytosis of oxLDL and IgG ligand microbeads was abolished by the actin polymerization inhibitors cytochalasin D and latrunculin. Pharmacological inhibitors of the receptor enzymes JAK, SRC, and PLC prevented both IgG and oxLDL receptor function. In contrast, the function of the oxLDL phagocytic receptor complex was more sensitive to inhibition of PTK2, PKC, and SYK activity.

  2. Effects of oxidized low density lipoprotein on transformation of valvular myofibroblasts to osteoblast-like phenotype.

    PubMed

    Chen, Di; Shen, Ying-Lian; Hu, Wei-Lin; Chen, Zheng-Ping; Li, Yong-Sheng

    2015-06-01

    In order to investigate the roles of Wnt signal pathway in transformation of cardiac valvular myofibroblasts to the osteoblast-like phenotype, the primary cultured porcine aortic valve myofibroblasts were incubated with oxidized low density lipoprotein (ox-LDL, 50 mg/L), and divided into four groups according to the ox-LDL treatment time: control group, ox-LDL 24-h group, ox-LDL 48-h group, and ox-LDL 72-h group. Wnt signal pathway blocker Dickkopf-1 (DDK-1, 100 μg/L) was added in ox-LDL 72-h group. The expression of a-smooth muscle actin (α-SMA), bone morphogenetic protein 2 (BMP2), alkaline phosphatase (ALP), and osteogenic transcription factor Cbfa-1 was detected by Western blotting, and that of β-catenin, a key mediator of Wnt signal pathway by immunocytochemical staining method. The Wnt/β-catenin was observed and the transformation of myofibroblasts to the osteoblast-like phenotype was examined. The expression of α-SMA, BMP2, ALP and Cbfa-1 proteins in the control group was weaker than in the ox-LDL-treated groups. In ox-LDL-treated groups, the protein expression of a-SMA, BMP2, ALP, and Cbfa-1 was significantly increased in a time-dependent manner as compared with the control group, and there was significant difference among the three ox-LDL-treated groups (P<0.05 for all); β-catenin protein was also up-regulated in the ox-LDL-treated groups in a time-dependent manner as compared with the control group (P<0.05), and its transfer from cytoplasm to nucleus and accumulation in the nucleus were increased in the same fashion (P<0.05). After addition of DKK-1, the expression of α-SMA, bone-related proteins and β-catenin protein was significantly reduced as compared with ox-LDL 72-h group (P<0.05). The Wnt/ β-catenin signaling pathway may play an important role in transformation of valvular myofibroblasts to the osteoblast-like phenotype.

  3. Low-density lipoprotein cholesterol and survival in pulmonary arterial hypertension

    PubMed Central

    Kopeć, Grzegorz; Waligóra, Marcin; Tyrka, Anna; Jonas, Kamil; Pencina, Michael J.; Zdrojewski, Tomasz; Moertl, Deddo; Stokwiszewski, Jakub; Zagożdżon, Paweł; Podolec, Piotr

    2017-01-01

    Low-density lipoprotein cholesterol(LDL-C) is a well established metabolic marker of cardiovascular risk, however, its role in pulmonary arterial hypertension (PAH) has not been determined. Therefore we assessed whether LDL-C levels are altered in PAH patients, if they are associated with survival in this group and whether pulmonary hypertension (PH) reversal can influence LDL-C levels. Consecutive 46 PAH males and 94 females were age matched with a representative sample of 1168 males and 1245 females, respectively. Cox regression models were used to assess the association between LDL-C and mortality. The effect of PH reversal on LDL-C levels was assessed in 34 patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing invasive treatment. LDL-C was lower in both PAH (2.6 ± 0.8 mmol/l) and CTEPH (2.7 ± 0.7 mmol/l) patients when compared to controls (3.2 ± 1.1 mmol/l, p < 0.001). In PAH patients lower LDL-C significantly predicted death (HR:0.44/1 mmol/l, 95%CI:0.26–0.74, p = 0.002) after a median follow-up time of 33(21–36) months. In the CTEPH group, LDL-C increased (from 2.6[2.1–3.2] to 4.0[2.8–4.9]mmol/l, p = 0.01) in patients with PH reversal but remained unchanged in other patients (2.4[2.2–2.7] vs 2.3[2.1–2.5]mmol/l, p = 0.51). We concluded that LDL-C level is low in patients with PAH and is associated with an increased risk of death. Reversal of PH increases LDL-C levels. PMID:28198422

  4. Medical and psychosocial factors and unfavourable low-density lipoprotein cholesterol control in coronary patients.

    PubMed

    Munkhaugen, John; Sverre, Elise; Otterstad, Jan E; Peersen, Kari; Gjertsen, Erik; Perk, Joep; Gullestad, Lars; Moum, Torbjørn; Dammen, Toril; Husebye, Einar

    2017-01-01

    Objective Understanding the determinants of low-density lipoprotein cholesterol (LDL-C) control constitutes the basis of modelling interventions for optimal lipid control and prognosis. We aim to identify medical and psychosocial (study) factors associated with unfavourable LDL-C control in coronary patients. Methods A cross-sectional explorative study used logistic and linear regression analysis to investigate the association between study factors and LDL-C in 1095 patients, hospitalized with myocardial infarction and/or a coronary revascularization procedure. Data were collected from hospital records, a comprehensive self-report questionnaire, clinical examination and blood samples after 2-36 months follow-up. Results Fifty-seven per cent did not reach the LDL-C target of 1.8 mmol/l at follow-up. Low socioeconomic status and psychosocial factors were not associated with failure to reach the LDL-C target. Statin specific side-effects (odds ratio 3.23), low statin adherence (odds ratio 3.07), coronary artery by-pass graft operation as index treatment (odds ratio 1.95), ≥ 1 coronary event prior to the index event (odds ratio 1.81), female gender (odds ratio 1.80), moderate- or low-intensity statin therapy (odds ratio 1.62) and eating fish < 3 times/week (odds ratio 1.56) were statistically significantly associated with failure to reach the LDL-C target, in adjusted analyses. Only side-effects (standardized β 0.180), low statin adherence ( β 0.209) and moderate- or low-intensity statin therapy ( β 0.228) were associated with LDL-C in continuous analyses. Conclusions Statin specific side-effects, low statin adherence and moderate- or low-intensity statin therapy were the major factors associated with unfavourable LDL-C control. Interventions to improve LDL-C should ensure adherence and prescription of sufficiently potent statins, and address side-effects appropriately.

  5. Effects of paroxetine and sertraline on low-density lipoprotein cholesterol: an observational cohort study.

    PubMed

    Wei, Feifei; Crain, A Lauren; Whitebird, Robin R; Godlevsky, Olga V; O'Connor, Patrick J

    2009-10-01

    Antidepressant use in US adults increased 3-fold from 2.5% in 1988-94 to 8.1% in 1999-2002, based on National Health and Nutrition Examination Surveys. As the use of antidepressants increases, a comprehensive understanding of the potential health risks that may be associated with their use becomes increasingly important. This study evaluated the effects of paroxetine and sertraline on low-density lipoprotein cholesterol (LDL-C). An observational cohort study (1997-2004) of adults who had taken paroxetine or sertraline for at least 60 continuous days and had > or =2 LDL-C values measured during the study period, one while taking and one while not taking paroxetine or sertraline. A total of 13 634 LDL-C values clustered within 2682 patients were studied. We conducted mixed model regression analyses to quantify the relationship between antidepressant use and LDL-C values. The number of days taking paroxetine (beta = 0.0045; 95% CI 0.0018, 0.0073) and sertraline (beta = 0.0074; 95% CI 0.0054, 0.0093) prior to the LDL-C test were related to higher LDL-C values, after accounting for age, sex, year LDL-C was tested, co-morbidity, depression and lipid medication. The number of days that had passed since exposure to paroxetine (beta = -0.0013; 95% CI -0.0020, -0.00061) or sertraline (beta = -0.00093; 95% CI -0.016, -0.00022) were related to lower LDL-C values. The significant interaction between exposure to an antidepressant and taking a lipid medication demonstrates that the increase in LDL-C values associated with antidepressant use is ameliorated among patients who were taking a lipid medication when LDL-C was measured. Our study showed that long-term use of paroxetine or sertraline may have a measurable adverse impact on cardiovascular risk in adults. Clinical strategies should be used to address cardiovascular risk while maintaining effective treatment of major depression. In light of these findings, attention to LDL-C values should accompany antidepressant use.

  6. Oxidative modification of low-density lipoprotein and atherogenetic risk in beta-thalassemia.

    PubMed

    Livrea, M A; Tesoriere, L; Maggio, A; D'Arpa, D; Pintaudi, A M; Pedone, E

    1998-11-15

    We investigated the oxidative state of low-density lipoprotein (LDL) in patients with beta-thalassemia to determine whether there was an association with atherogenesis. Conjugated diene lipid hydroperoxides (CD) and the level of major lipid antioxidants in LDL, as well as modified LDL protein, were evaluated in 35 beta-thalassemia intermedia patients, aged 10 to 60, and compared with age-matched healthy controls. Vitamin E and beta-carotene levels in LDL from patients were 45% and 24% of that observed in healthy controls, respectively. In contrast, the mean amount of LDL-CD was threefold higher and lysil residues of apo B-100 were decreased by 17%. LDL-CD in thalassemia patients showed a strong inverse correlation with LDL vitamin E (r = -0.784; P <.0001), while a negative trend was observed with LDL-beta-carotene (r = -0.443; P =.149). In the plasma of thalassemia patients, malondialdehyde (MDA), a byproduct of lipid peroxidation, was increased by about twofold, while vitamin E showed a 52% decrease versus healthy controls. LDL-CD were inversely correlated with plasma vitamin E (r = -0.659; P <.0001) and correlated positively with plasma MDA (r = 0.621; P <. 0001). Plasma ferritin was positively correlated with LDL-CD (r = 0.583; P =.0002). No correlation was found between the age of the patients and plasma MDA or LDL-CD. The LDL from thalassemia patients was cytotoxic to cultured human fibroblasts and cytotoxicity increased with the content of lipid peroxidation products. Clinical evidence of mild to severe vascular complications in nine of the patients was then matched with levels of LDL-CD, which were 36% to 118% higher than the mean levels of the patients. Our results could account for the incidence of atherogenic vascular diseases often reported in beta-thalassemia patients. We suggest that the level of plasma MDA in beta-thalassemia patients may represent a sensitive index of the oxidative status of LDL in vivo and of its potential atherogenicity.

  7. Oxidation of Low-Density Lipoprotein by Iron at Lysosomal pH: Implications for Atherosclerosis

    PubMed Central

    2012-01-01

    Low-density lipoprotein (LDL) has recently been shown to be oxidized by iron within the lysosomes of macrophages, and this is a novel potential mechanism for LDL oxidation in atherosclerosis. Our aim was to characterize the chemical and physical changes induced in LDL by iron at lysosomal pH and to investigate the effects of iron chelators and α-tocopherol on this process. LDL was oxidized by iron at pH 4.5 and 37 °C and its oxidation monitored by spectrophotometry and high-performance liquid chromatography. LDL was oxidized effectively by FeSO4 (5–50 μM) and became highly aggregated at pH 4.5, but not at pH 7.4. The level of cholesteryl esters decreased, and after a pronounced lag, the level of 7-ketocholesterol increased greatly. The total level of hydroperoxides (measured by the triiodide assay) increased up to 24 h and then decreased only slowly. The lipid composition after 12 h at pH 4.5 and 37 °C was similar to that of LDL oxidized by copper at pH 7.4 and 4 °C, i.e., rich in hydroperoxides but low in oxysterols. Previously oxidized LDL aggregated rapidly and spontaneously at pH 4.5, but not at pH 7.4. Ferrous iron was much more effective than ferric iron at oxidizing LDL when added after the oxidation was already underway. The iron chelators diethylenetriaminepentaacetic acid and, to a lesser extent, desferrioxamine inhibited LDL oxidation when added during its initial stages but were unable to prevent aggregation of LDL after it had been partially oxidized. Surprisingly, desferrioxamine increased the rate of LDL modification when added late in the oxidation process. α-Tocopherol enrichment of LDL initially increased the rate of oxidation of LDL but decreased it later. The presence of oxidized and highly aggregated lipid within lysosomes has the potential to perturb the function of these organelles and to promote atherosclerosis. PMID:22493939

  8. Interaction between SCO-spondin and low density lipoproteins from embryonic cerebrospinal fluid modulates their roles in early neurogenesis

    PubMed Central

    Vera, América; Recabal, Antonia; Saldivia, Natalia; Stanic, Karen; Torrejón, Marcela; Montecinos, Hernán; Caprile, Teresa

    2015-01-01

    During early stages of development, encephalic vesicles are composed by a layer of neuroepithelial cells surrounding a central cavity filled with embryonic cerebrospinal fluid (eCSF). This fluid contains several morphogens that regulate proliferation and differentiation of neuroepithelial cells. One of these neurogenic factors is SCO-spondin, a giant protein secreted to the eCSF from early stages of development. Inhibition of this protein in vivo or in vitro drastically decreases the neurodifferentiation process. Other important neurogenic factors of the eCSF are low density lipoproteins (LDL), the depletion of which generates a 60% decrease in mesencephalic explant neurodifferentiation. The presence of several LDL receptor class A (LDLrA) domains (responsible for LDL binding in other proteins) in the SCO-spondin sequence suggests a possible interaction between both molecules. This possibility was analyzed using three different experimental approaches: (1) Bioinformatics analyses of the SCO-spondin region, that contains eight LDLrA domains in tandem, and of comparisons with the LDL receptor consensus sequence; (2) Analysis of the physical interactions of both molecules through immunohistochemical colocalization in embryonic chick brains and through the immunoprecipitation of LDL with anti-SCO-spondin antibodies; and (3) Analysis of functional interactions during the neurodifferentiation process when these molecules were added to a culture medium of mesencephalic explants. The results revealed that LDL and SCO-spondin interact to form a complex that diminishes the neurogenic capacities that both molecules have separately. Our work suggests that the eCSF is an active signaling center with a complex regulation system that allows for correct brain development. PMID:26074785

  9. Red grape seed extract improves lipid profiles and decreases oxidized low-density lipoprotein in patients with mild hyperlipidemia.

    PubMed

    Razavi, Seyed-Mostafa; Gholamin, Sharareh; Eskandari, Ali; Mohsenian, Nakta; Ghorbanihaghjo, Amir; Delazar, Abbas; Rashtchizadeh, Nadereh; Keshtkar-Jahromi, Maryam; Argani, Hassan

    2013-03-01

    Hyperlipidemia can lead to atherosclerosis by lipoprotein deposition inside the vessel wall and oxidative stress induction that leads to the formation of atherosclerotic plaque. Oxidized low-density lipoprotein particles (Ox-LDL) have a key role in the pathogenesis of atherosclerosis. The lipid-lowering properties and antioxidants of the grape seed can be beneficial in atherosclerosis prevention. We conducted a randomized double-blind placebo-controlled crossover clinical trial. Fifty-two mildly hyperlipidemic individuals were divided into two groups that received either 200 mg/day of the red grape seed extract (RGSE) or placebo for 8 weeks. After an 8-week washout period, the groups were crossed over for another 8 weeks. Lipid profiles and Ox-LDL were measured at the beginning and the end of each phase. RGSE consumption reduced total cholesterol (-10.68±26.76 mg/dL, P=.015), LDL cholesterol (-9.66±23.92 mg/dL, P=.014), and Ox-LDL (-5.47±12.12 mg/dL, P=.008). While triglyceride and very low-density lipoprotein cholesterol were decreased and high-density lipoprotein cholesterol was increased by RGSE, the changes were not statistically significant. RGSE consumption decreases Ox-LDL and has beneficial effects on lipid profile-consequently decreasing the risk of atherosclerosis and cardiovascular disorders-in mild hyperlipidemic individuals.

  10. The mechanism of oxidation-induced low-density lipoprotein aggregation: an analogy to colloidal aggregation and beyond?

    PubMed Central

    Xu, S; Lin, B

    2001-01-01

    Atherosclerosis is a disease initiated by lipoprotein aggregation and deposition in artery walls. In this study, the de novo low-density lipoprotein aggregation process was examined. Nine major intermediates were identified in two stages of the aggregation process. In the aggregation stage, low-density lipoprotein molecules aggregate and form nucleation units. The nucleation units chain together and form linear aggregates. The linear aggregates branch and interact with one another, forming fractals. In the fusion stage, spatially adjacent nucleation units in the fractal fuse into curved membrane surfaces, which, in turn, fuse into multilamellar or unilamellar vesicles. Alternatively, some adjacent nucleation units in the fractals assemble in a straight line and form rods. Subsequently, the rods flatten out into rough and then into smooth ribbons. Occasionally, tubular membrane vesicles are formed from the fractals. The aggregation stage seems to be analogous to colloidal aggregation and amyloid fiber formation. The fusion stage seems to be characteristic of the lipid-rich lipoproteins and is beyond colloidal aggregation and amyloid fiber formation. PMID:11566810

  11. PFOS induced lipid metabolism disturbances in BALB/c mice through inhibition of low density lipoproteins excretion

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Wang, Yu; Liang, Yong; Li, Jia; Liu, Yuchen; Zhang, Jie; Zhang, Aiqian; Fu, Jianjie; Jiang, Guibin

    2014-04-01

    Male BALB/c mice fed with either a regular or high fat diet were exposed to 0, 5 or 20 mg/kg perfluorooctane sulfonate (PFOS) for 14 days. Increased body weight, serum glucose, cholesterol and lipoprotein levels were observed in mice given a high fat diet. However, all PFOS-treated mice got reduced levels of serum lipid and lipoprotein. Decreasing liver glycogen content was also observed, accompanied by reduced serum glucose levels. Histological and ultrastructural examination detected more lipid droplets accumulated in hepatocytes after PFOS exposure. Moreover, transcripitonal activity of lipid metabolism related genes suggests that PFOS toxicity is probably unrelevant to PPARα's transcription. The present study demonstrates a lipid disturbance caused by PFOS and thus point to its role in inhibiting the secretion and normal function of low density lipoproteins.

  12. PFOS induced lipid metabolism disturbances in BALB/c mice through inhibition of low density lipoproteins excretion

    PubMed Central

    Wang, Ling; Wang, Yu; Liang, Yong; Li, Jia; Liu, Yuchen; Zhang, Jie; Zhang, Aiqian; Fu, Jianjie; Jiang, Guibin

    2014-01-01

    Male BALB/c mice fed with either a regular or high fat diet were exposed to 0, 5 or 20 mg/kg perfluorooctane sulfonate (PFOS) for 14 days. Increased body weight, serum glucose, cholesterol and lipoprotein levels were observed in mice given a high fat diet. However, all PFOS-treated mice got reduced levels of serum lipid and lipoprotein. Decreasing liver glycogen content was also observed, accompanied by reduced serum glucose levels. Histological and ultrastructural examination detected more lipid droplets accumulated in hepatocytes after PFOS exposure. Moreover, transcripitonal activity of lipid metabolism related genes suggests that PFOS toxicity is probably unrelevant to PPARα's transcription. The present study demonstrates a lipid disturbance caused by PFOS and thus point to its role in inhibiting the secretion and normal function of low density lipoproteins. PMID:24694979

  13. Chitosan oligosaccharide decreases very-low-density lipoprotein triglyceride and increases high-density lipoprotein cholesterol in high-fat-diet-fed rats.

    PubMed

    Wang, Daxin; Han, Jiju; Yu, Yang; Li, Xueping; Wang, Yun; Tian, Hua; Guo, Shoudong; Jin, Shiguang; Luo, Tian; Qin, Shucun

    2011-09-01

    It is well known that chitosan has beneficial lipid-regulating effects, but it remains unknown whether chitosan oligosaccharide (COS), the chitosan degradation product, has the same lipid benefits. High-fat-diet-fed Wistar rats were administrated with COS by gastric gavage for three weeks. The effects of COS on lipids, lipoprotein components and lipid metabolism related protein activities were investigated. Plasma lipids level assays by an enzyme method showed that COS decreased triglyceride (TG) by 29-31%, and increased high-density lipoprotein (HDL) cholesterol by 8-11%, but did not affect low-density lipoprotein (LDL) cholesterol. Lipid distribution analysis through fast protein liquid chromatography indicated that COS significantly decreased TG content distributed in very-low-density lipoprotein (VLDL)/LDL fractions but increased cholesterol content in HDL fractions. Apolipoprotein analysis through plasma ultracentrifugation and sodium dodecyl sulfate polyacrylamide gel electrophoresis displayed that COS decreased apolipoprotein B-100 of LDL and increased apolipoprotein E of LDL and apolipoprotein B-100 of VLDL, but did not change apoA-I content of HDL particles. Lipoprotein formation associated protein determination showed that COS also increased plasma activity of lecithin cholesterol acyl transferase but not phospholipid transfer protein. The present study suggests that COS may play a beneficial role in plasma lipid regulation of rats with dyslipidemia induced by high-fat diet. The COS-decreased VLDL/LDL TG and -enhanced HDL cholesterol may be related to the upregulated activity of lecithin cholesterol acyl transferase.

  14. Z-Scan Analysis: a New Method to Determine the Oxidative State of Low-Density Lipoprotein and Its Association with Multiple Cardiometabolic Biomarkers

    NASA Astrophysics Data System (ADS)

    de Freitas, Maria Camila Pruper; Figueiredo Neto, Antonio Martins; Giampaoli, Viviane; da Conceição Quintaneiro Aubin, Elisete; de Araújo Lima Barbosa, Milena Maria; Damasceno, Nágila Raquel Teixeira

    2016-04-01

    The great atherogenic potential of oxidized low-density lipoprotein has been widely described in the literature. The objective of this study was to investigate whether the state of oxidized low-density lipoprotein in human plasma measured by the Z-scan technique has an association with different cardiometabolic biomarkers. Total cholesterol, high-density lipoprotein cholesterol, triacylglycerols, apolipoprotein A-I and apolipoprotein B, paraoxonase-1, and glucose were analyzed using standard commercial kits, and low-density lipoprotein cholesterol was estimated using the Friedewald equation. A sandwich enzyme-linked immunosorbent assay was used to detect electronegative low-density lipoprotein. Low-density lipoprotein and high-density lipoprotein sizes were determined by Lipoprint® system. The Z-scan technique was used to measure the non-linear optical response of low-density lipoprotein solution. Principal component analysis and correlations were used respectively to resize the data from the sample and test association between the θ parameter, measured with the Z-scan technique, and the principal component. A total of 63 individuals, from both sexes, with mean age 52 years (±11), being overweight and having high levels of total cholesterol and low levels of high-density lipoprotein cholesterol, were enrolled in this study. A positive correlation between the θ parameter and more anti-atherogenic pattern for cardiometabolic biomarkers together with a negative correlation for an atherogenic pattern was found. Regarding the parameters related with an atherogenic low-density lipoprotein profile, the θ parameter was negatively correlated with a more atherogenic pattern. By using Z-scan measurements, we were able to find an association between oxidized low-density lipoprotein state and multiple cardiometabolic biomarkers in samples from individuals with different cardiovascular risk factors.

  15. ApoE and the role of very low density lipoproteins in adipose tissue inflammation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our goal was too identify the role of triglyceride-rich lipoproteins and apoE, a major apolipoprotein in triglyceride-rich lipoproteins, in adipose tissue inflammation with high-fat diet induced obesity. Male apoE-/- and C57BL/6J wild-type mice fed high fat diets for 12 weeks were assessed for metab...

  16. Low-density lipoprotein, its susceptibility to oxidation and the role of lipoprotein-associated phospholipase A2 and carboxyl ester lipase lipases in atherosclerotic plaque formation.

    PubMed

    Burchardt, Paweł; Zurawski, Jakub; Zuchowski, Bartosz; Kubacki, Tomasz; Murawa, Dawid; Wiktorowicz, Krzysztof; Wysocki, Henryk

    2013-02-21

    An increased level of low-density lipoprotein (LDL) is a very well established risk factor of coronary artery disease (CAD). Unoxidized LDL is an inert transport vehicle of cholesterol and other lipids in the body and is thought to be atherogenic. Recently it has been appreciated that oxidized products of LDL are responsible for plaque formation properties previously attributed to the intact particle. The goal of this article is to review the recent understanding of the LDL oxidation pathway. The role of oxidized products and key enzymes (lipoprotein-associated phospholipase A2 and carboxyl ester lipase) are also extensively discussed in the context of clinical conditions.

  17. Relation between proprotein convertase subtilisin/kexin type 9 and directly measured low-density lipoprotein cholesterol

    PubMed Central

    Tecson, Kristen M.; Panettiere-Kennedy, Katherine S.; Won, Jane I.; Garg, Puja; Olugbode, Oluseun

    2017-01-01

    Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a regulator of low-density lipoprotein cholesterol (LDL-C) receptor (LDL-R) recycling and, thus, is a determinant of plasma LDL-C concentration. We sought to determine the relation between serum concentrations of PCSK9 and LDL-C while considering a variety of influential variables, including treatment for dyslipidemia. Using a prospective lipid clinic registry, we evaluated clinical variables, the results of advanced lipid testing, and PCSK9 concentrations determined by immunoassay. We evaluated the relationship between directly measured LDL-C and PCSK9 in serum by performing a simple linear regression. Correlation analyses were performed to examine the relationships of PCSK9 to other clinical and laboratory values and to test for differences in median PCSK9 across patient groups. Factors identified as potential predictors were considered jointly in a multivariate model. For the 26 patients in the analyses, a relationship was not detected between LDL-C and PCSK9 (r = 0.009, P = 0.97); however, PCSK9 was correlated with C-peptide (r = 0.48; P = 0.01) and heart rate (r = 0.52; P = 0.006). Median PCSK9 values differed between statin users (284.0 ng/mL [quartile 1 = 241.0, quartile 3 = 468.0]) and nonusers (219.0 ng/mL [quartile 1 = 151.0, quartile 3 = 228.0]; P = 0.02). More investigation is needed to evaluate the relationship between LDL and PCSK9, as well as the determinants of PCSK9, a major factor regulating cholesterol concentrations. PMID:28127122

  18. Reactive oxygen species mediate angiotensin II-induced transcytosis of low-density lipoprotein across endothelial cells

    PubMed Central

    Bian, Fang; Cui, Jun; Zheng, Tao; Jin, Si

    2017-01-01

    The retention of plasma low-density lipoprotein (LDL) particles to subendothelial spaces through transcytosis across the endothelium is the initial step of atherosclerosis (AS). Angiotensin II (Ang II), as the principal effector molecule of the renin-angiotensin system (RAS), is implicated in several important steps of AS development. However, whether or not Ang II can directly exert a pro-atherogenic effect by promoting LDL transcytosis across endothelial barriers, has not been defined. In the present study, we found that Ang II upregulated intracellular reactive oxygen species (ROS) levels in endothelial cells (ECs) by measuring fluorescence of 2′,7′-dichlorofluorescein (DCF-DA). Based on our transcytosis model, we observed that Ang II significantly accelerated LDL transcytosis, whereas transcytosis inhibitor methyl-β-cyclodextrin (MβCD) and ROS inhibitor dithiothreitol (DTT), markedly blocked the Ang II-stimulated increase in LDL transcytosis. Confocal imaging analysis revealed that both LDL uptake by cells and LDL retention in human umbilical venous walls were highly elevated after Ang II exposure, while MβCD and DTT significantly inhibited the effects of Ang II. What is more, proteins involved in caveolae-mediated transcytosis, including LDL receptor (LDLR), caveolin-1 and cavin-1, were associated with Ang II-induced LDL transcytosis across the ECs. Nevertheless, this process was independent of clathrin in our study. Of note, ROS inhibitor, DTT, markedly decreased the expression levels of those proteins. Consequently, ROS are critical mediators in Ang II-induced LDL transcytosis. Hopefully, these findings will provide novel insight into the crosstalk between dyslipidemia and RAS in atherogenesis. PMID:28204818

  19. Screening, expression, and characterization of an anti-human oxidized low-density lipoprotein single-chain variable fragment.

    PubMed

    Kumano-Kuramochi, Miyuki; Fujimura, Takashi; Komba, Shiro; Maeda-Yamamoto, Mari; Machida, Sachiko

    2016-09-01

    Increased levels of oxidized low-density lipoprotein (OxLDL) in the blood circulation are correlated with atherosclerosis. Monoclonal antibody-based detection systems have been reported for OxLDL. We identified novel single-chain variable fragments (scFvs) having affinity for human OxLDL and related ligands. We constructed an scFv library from nonimmunized human spleen mRNA. Two types (γ+κ and μ+λ) of scFv phage libraries were enriched by biopanning, and five scFv clones with affinity for OxLDL were identified. The γκ5 scFv, which showed the highest affinity for OxLDL, was cloned into pET-22b(+) and expressed in Escherichia coli BL21(DE3). γκ5, expressed as an inclusion body in BL21(DE3), was refolded and purified. The specificity and sensitivity of γκ5 were analyzed using enzyme-linked immunosorbent assays (ELISAs). The γκ5 scFv showed affinity for OxLDL and acetylated LDL. The sensitivity of γκ5 to low concentrations (1-2 μg/mL) of OxLDL was higher than that to AcLDL and LDL. Finally, we developed a sandwich ELISA using γκ5 and CTLD14 (a lectin-like OxLDL receptor-1 ligand recognition region), which allowed specific detection of OxLDL at a level below 0.1 μg/mL. Our results indicated that the γκ5 scFv was a promising molecule for the detection of modified LDL at very low concentrations.

  20. [Study on the selective removal of plasma low-density lipoprotein and fibrinogen by degraded guar sulfate].

    PubMed

    Zhu, Ye; Fang, Bo; Huang, Li; Guan, Chen; Yang, Guang

    2008-10-01

    Degraded guar was prepared by acid with guar as the main material, which was then brought into reaction with chlorosulfonic acid under proper conditions, the sulfonated degraded guar was obtained successfully. The effects of sulfonation conditions on the SO4(2-) content were investigated, and the proper reaction conditions were determined. The results of infrared spectrometry showed that this sulfated derivative is a novel heparin-like polysaccharide. At the same time, the selective removal of low density lipoprotein (LDL) and fibrinogen (Fib) by degraded guar gum sulfate was studied. The experimental results showed that degraded guar gum sulfate is a novel LDL/ Fib purifying agent. When pH= 5.15 and the initial concentration of the degraded guar gum sulfate is 2500 mg/L, the reduction percentages were about 60%-66% for total cholesterol, about 76%-89% for LDL and very low-density lipoproteins (VLDL), and almost 100% for fibrinogen. There were no significant changes regarding the level of high-density lipoproteins and total proteins.

  1. Adenovirus-mediated transfer of a gene encoding cholesterol 7 alpha-hydroxylase into hamsters increases hepatic enzyme activity and reduces plasma total and low density lipoprotein cholesterol.

    PubMed Central

    Spady, D K; Cuthbert, J A; Willard, M N; Meidell, R S

    1995-01-01

    Clinical interventions that accelerate conversion of cholesterol to bile acids reduce circulating low density lipoprotein (LDL) cholesterol concentrations. The initial and rate-limiting step in the bile acid biosynthetic pathway is catalyzed by hepatic cholesterol 7 alpha-hydroxylase. To examine the effects of transient primary overexpression of this enzyme on sterol metabolism and lipoprotein transport, we constructed a recombinant adenovirus in which a cDNA encoding rat 7 alpha-hydroxylase is expressed from the human cytomegalovirus immediate-early promoter (AdCMV7 alpha). Syrian hamsters administered AdCMV7 alpha intravenously accumulated transgene-specific mRNA in the liver and demonstrated a dose-dependent increase in hepatic microsomal 7 alpha-hydroxylase activity. The increased conversion of cholesterol to bile acids resulted in a compensatory increase in hepatic cholesterol synthesis. In addition, overexpression of 7 alpha-hydroxylase reduced the rate of LDL cholesterol entry into the plasma space and, in animals maintained on a Western-type diet, restored hepatic LDL receptor expression. As a consequence, plasma LDL concentrations fell by approximately 60% in animals maintained on control diet and by approximately 75% in animals consuming a Western-type diet. Plasma high density lipoprotein cholesterol levels were reduced to a lesser degree. These results demonstrate that transient upregulation of bile acid synthesis by direct transfer of a 7 alpha-hydroxylase gene favorably alters circulating lipoprotein profiles and suggest one potential molecular target for genetic strategies aimed at reducing cardiovascular risk. Images PMID:7635963

  2. Low-density lipoprotein transport through an arterial wall under hyperthermia and hypertension conditions--An analytical solution.

    PubMed

    Iasiello, Marcello; Vafai, Kambiz; Andreozzi, Assunta; Bianco, Nicola

    2016-01-25

    An analytical solution for Low-Density Lipoprotein transport through an arterial wall under hyperthermia conditions is established in this work. A four-layer model is used to characterize the arterial wall. Transport governing equations are obtained as a combination between Staverman-Kedem-Katchalsky membrane equations and volume-averaged porous media equations. Temperature and solute transport fields are coupled by means of Ludwig-Soret effect. Results are in excellent agreement with numerical and analytical literature data under isothermal conditions, and with numerical literature data for the hyperthermia case. Effects of hypertension combined with hyperthermia, are also analyzed in this work.

  3. In vitro studies of PBT Nonwoven Fabrics adsorbent for the removal of low density lipoprotein from hyperlipemia plasma

    NASA Astrophysics Data System (ADS)

    Cao, Ye; Wang, Hong; Yang, Chao; Zhong, Rui; Lei, Yu; Sun, Kang; Liu, Jiaxin

    2011-06-01

    Polyanion ligands such as acrylic acid (AA) and heparin were grafted on PBT Nonwoven Fabrics (PBTNF) to study their effect on the adsorption of low density lipoprotein (LDL). These modified PBTNFs were characterized by Horizontal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy and X-ray Photoelectron spectroscopy. The blood compatibilities of the modified PBTNFs were examined using in vitro hemolysis rate (HR), platelet adhesion, total protein (TP) and activated partial thromboplastin time. The results showed that direct immobilized heparin could improve PBTNF-PAA's blood compatibility and decrease the adsorption capability of useful high density lipoprotein, but would possess so low bioactivity that could not further improve the absorption of LDL and TC. Since the PBTNF-PAA55-Heparin adsorbent had quite good adsorption selectivity for these proteins, it can be an excellent candidate for depletion of LDL with good blood compatibility.

  4. Minimal oxidation and storage of low density lipoproteins result in an increased susceptibility to phospholipid hydrolysis by phospholipase A2.

    PubMed

    Eckey, R; Menschikowski, M; Lattke, P; Jaross, W

    1997-07-25

    In vitro-studies have shown that phospholipid hydrolysis of low density lipoproteins (LDL) by bee venom or porcine pancreatic phospholipase A2 (PLA2) leads to an increased uptake of these lipoproteins by macrophages transforming them into foam cells. Recently, a secretory phospholipase A2, group II, was detected in human atherosclerotic plaques. In order to investigate the role of this enzyme in the pathogenesis of atherosclerosis, a structurally identical human secretory PLA2 was purified from the medium of HepG2 cells stimulated with interleukin-6 and tumor necrosis factor-alpha. The activity of the purified enzyme towards the phospholipids of native and modified low density lipoproteins was compared with the activity towards Escherichia coli-membranes and other phospholipid substrates. Compared to E. coli-membranes, native LDL proved to be a poor substrate for group II PLA2. After mild oxidation induced by copper ions or by 2,2-azobis(2-amidinopropane) (AAPH), the susceptibility of LDL to phospholipid hydrolysis was found to be increased by 25 and 23%, respectively, whereas extensive copper-mediated oxidation caused a decreased hydrolysis. Aging of LDL at 6 degrees C for weeks or at 37 degrees C for hours resulted in an increase in PLA2-catalyzed phospholipid hydrolysis of up to 26-fold. LDL protected from oxidation by probucol during aging showed a lesser increase in susceptibility to phospholipid hydrolysis. Our results suggest that PLA2, group II, can increase the atherogenicity of LDL by its ability to hydrolyze the phospholipids of these lipoproteins, especially after modifications that are likely to occur in vivo.

  5. Analysis of beta-carotene absorbance for studying structural properties of human plasma low-density lipoproteins.

    PubMed

    Krisko, Anita; Piantanida, Ivo; Kveder, Marina; Pifat, Greta

    2004-08-01

    A novel spectrophotometric assay for monitoring structural rearrangements of native low-density lipoproteins (LDL) is proposed. The approach is based on the analysis of the visible light absorbance maximum of lipoproteins at approximately 461 nm assigned to beta-carotene situated in the hydrophobic parts of LDL. It offers a direct method to study the surface-interior coupling of the lipoprotein particle under physiological conditions. The detected signal is intrinsic to LDL and responsible for the most of the beta-carotene signal from the whole plasma. The negligible interference of beta-carotene absorbance due to the high-density lipoproteins is experimentally verified. Since beta-carotene absorbance belongs to the visible spectral region, no spectral overlapping/artifacts in plasma are expected. The signal sensitivity has been studied through conformational changes of LDL induced by ionic strength, by temperature, and by ligand binding. The results of caffeine binding to LDL indicate that there could be only one dominant type of binding site for caffeine on LDL particles. It can be concluded that visible spectrum characteristics of beta-carotene molecules offer advantages in LDL ligand binding studies which can possibly be extended to monitor the interactions of LDL directly in plasma.

  6. The Serum Very-Low-Density Lipoprotein Serves as a Restriction Factor against Hepatitis C Virus Infection

    PubMed Central

    Tao, Jian; Kang, Kyung-Don; Hall, Stacy D.; Laube, Audra H.; Liu, Jia; Renfrow, Matthew B.; Novak, Jan

    2015-01-01

    ABSTRACT Recent studies demonstrated that transgenic mice expressing key human hepatitis C virus (HCV) receptors are susceptible to HCV infection, albeit at very low efficiency. Robust mouse models of HCV infection and replication are needed to determine the importance of host factors in HCV replication, pathogenesis, and carcinogenesis as well as to facilitate the development of antiviral agents and vaccines. The low efficiency of HCV replication in the humanized mouse models is likely due to either the lack of essential host factors or the presence of restriction factors for HCV infection and/or replication in mouse hepatocytes. To determine whether HCV infection is affected by restriction factors present in serum, we examined the effects of mouse and human sera on HCV infectivity. Strikingly, we found that mouse and human sera potently inhibited HCV infection. Mechanistic studies demonstrated that mouse serum blocked HCV cell attachment without significant effect on HCV replication. Fractionation analysis of mouse serum in conjunction with targeted mass spectrometric analysis suggested that serum very-low-density lipoprotein (VLDL) was responsible for the blockade of HCV cell attachment, as VLDL-depleted mouse serum lost HCV-inhibitory activity. Both purified mouse and human VLDL could efficiently inhibit HCV infection. Collectively, these findings suggest that serum VLDL serves as a major restriction factor of HCV infection in vivo. The results also imply that reduction or elimination of VLDL production will likely enhance HCV infection in the humanized mouse model of HCV infection and replication. IMPORTANCE HCV is a major cause of liver diseases, such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Recently, several studies suggested that humanized mouse or transgenic mouse expressing key HCV human receptors became susceptible to HCV infection. However, HCV infection and replication in the humanized animals were very inefficient, suggesting

  7. Endothelial NOS-dependent activation of c-Jun NH(2)- terminal kinase by oxidized low-density lipoprotein

    NASA Technical Reports Server (NTRS)

    Go, Y. M.; Levonen, A. L.; Moellering, D.; Ramachandran, A.; Patel, R. P.; Jo, H.; Darley-Usmar, V. M.

    2001-01-01

    Oxidized low-density lipoprotein (oxLDL) is known to activate a number of signal transduction pathways in endothelial cells. Among these are the c-Jun NH(2)-terminal kinase (JNK), also known as stress-activated protein kinase, and extracellular signal-regulated kinase (ERK). These mitogen-activated protein kinases (MAP kinase) determine cell survival in response to environmental stress. Interestingly, JNK signaling involves redox-sensitive mechanisms and is activated by reactive oxygen and nitrogen species derived from both NADPH oxidases, nitric oxide synthases (NOS), peroxides, and oxidized low-density lipoprotein (oxLDL). The role of endothelial NOS (eNOS) in the activation of JNK in response to oxLDL has not been examined. Herein, we show that on exposure of endothelial cells to oxLDL, both ERK and JNK are activated through independent signal transduction pathways. A key role of eNOS activation through a phosphatidylinositol-3-kinase-dependent mechanism leading to phosphorylation of eNOS is demonstrated for oxLDL-dependent activation of JNK. Moreover, we show that activation of ERK by oxLDL is critical in protection against the cytotoxicity of oxLDL.

  8. Mechanisms responsible for hepatic very low density lipoprotein-apoB100 overproduction in Otsuka Long-Evans Tokushima fatty rats

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Overproduction of hepatic very low-density lipoprotein (VLDL)1 particles is a major abnormality of lipoprotein dysregulation in type 2 diabetes (T2D). We sought to examine the mechanisms linking systemic/hepatic inflammation associated with insulin resistance and apolipoprotein (apo) B100-containing...

  9. Evaluation of monoclonal antibodies to human plasma low density lipoproteins. A requirement for lipids to maintain antigenic structure.

    PubMed

    Patton, J G; Alley, M C; Mao, S J

    1982-12-17

    Human plasma low density lipoproteins (LDL) are composed of approximately 25% apoproteins and 75% lipids (w/w). Immunochemical properties of LDL were studied using monoclonal antibodies. BALB/c mice were immunized with LDL and the spleen cells from these mice were then fused with a non-immunoglobulin secreting myeloma cell line (F0). The clones producing desirable antibodies were selected to study the antigenic properties of LDL by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay. First, it was found that the maximal binding of 125I-labeled LDL to polyvinyl chloride microtiter dishes was not temperature dependent. The binding affinity was high with a Ka value of approximately 1.9 X 10(10) M-1 while the monoclonal antibodies possessed an affinity to LDL of 5 X 10(8) M-1 which was 2 orders less than the affinity of LDL to the dishes. The former binding, once established, was irreversible as judged by a subsequent incubation with an excess of unlabeled LDL. The latter binding could be displaced by unlabeled LDL. Therefore, the ELISA technique offered a satisfactory approach to study the interaction between LDL and monoclonal antibodies. Removal of lipids from bound LDL by organic extraction resulted in a 50% loss of immunoreactivity, suggesting that the lipids of LDL are important in maintaining the antigenic structure of LDL. Since the apoprotein of LDL also constitutes approximately 40% of the mass (w/w) of very low density lipoproteins (VLDL), the immunoreactivity of VLDL assessed by LDL-monoclonal antibodies was also carried out. Removal of triglycerides from VLDL by lipoprotein lipase resulted in a substantial loss of immunoreactivity as determined by radioimmunoassay. These findings are consistent with the concept that lipids play a role in maintaining the integrity of the antigenic structure of LDL.

  10. Oxidation of serum low-density lipoprotein (LDL) and antioxidant status in young and elderly humans.

    PubMed

    Nakamura, Yukiko K; Read, Marsha H; Elias, Jeffrey W; Omaye, Stanley T

    2006-01-01

    The incidence of atherosclerosis increases with age, as do various indices of free-radical mediated damage, e.g., lipid peroxidation. Because lipid peroxidation plays a prominent role in lipoprotein oxidation, likely a prelude to atherosclerosis, we compared the susceptibility of lipoproteins to oxidation in young (19-30 years) and elderly (59-86 years) groups. Although we found no significant differences in serum malondialdehyde (MDA) or oxidized LDL antibodies (OLAB) between young and elderly lipoproteins, MDA was directly related to OLAB regardless of age (r = 0.322, p = 0.005) and there was a trend for lower OLAB levels (30.5%, p = 0.079) in the elderly compared to the young population. Overall, serum antioxidant status was either similar or greater in the elderly group compared to the young group, likely reflecting antioxidant supplementation by the elderly group. OLAB was inversely related to Vitamin C (r = -0.310, p = 0.008) and Vitamin E intake (r = -0.277, p = 0.018) from foods and supplements. Serum levels of Vitamin C and Vitamin E were significantly higher (18.5%, p = 0.021 and 58.1 %, p < 0.001, respectively) in the elderly group compared to the young group and the ratio of Vitamin E to Vitamin C was significantly higher (30.4%, p = 0.042) in the serum of the elderly group. Oxidation of serum LDL and antioxidant status were not affected by age; however, the ratio of serum Vitamin E to Vitamin C was higher in the elderly group which may affect Vitamin E recycling.

  11. Low-density lipoprotein apheresis by membrane differential filtration (cascade filtration) via arteriovenous fistula performed in children with familial hypercholesterolemia.

    PubMed

    Gülle, Saniye; Bak, Mustafa; Serdaroglu, Erkin; Can, Demet; Karabay, Ozalp

    2010-02-01

    Membrane differential filtration (cascade filtration) is an apheresis technique by which atherogenic lipoproteins can be eliminated from plasma on the basis of particle size. In this study, we aim to discuss the efficacy of low-density lipoprotein (LDL) apheresis performed by providing alternative vascular routes in two siblings with familial hypercholesterolemia who did not respond to medical treatment and diet. Of the two siblings, one was nine years old and the other one was three-and-a-half years old. Of the total of 78 apheresis processes performed, 24 were done via a permanent subclavian catheter, 36 were done via a subsequently provided arteriovenous fistula, and 18 were done via an arteriovenous graft. We observed a mean reduction in the plasma levels of total cholesterol (61.6%), LDL cholesterol (65.5%), and high-density lipoprotein cholesterol (38.6%). We noted that cascade filtration apheresis was effective in decreasing the LDL cholesterol in plasma, and no serious complications were noted. The success of the apheresis program depends on well-functioning blood access. An arteriovenous fistula may be the best route for the long-term treatment of familial hypercholesterolemia, which requires complication-free apheresis treatments.

  12. Targeted deletion of hepatic CTP:phosphocholine cytidylyltransferase alpha in mice decreases plasma high density and very low density lipoproteins.

    PubMed

    Jacobs, René L; Devlin, Cecilia; Tabas, Ira; Vance, Dennis E

    2004-11-05

    CTP:phosphocholine cytidylyltransferase (CT) is the key regulatory enzyme in the CDP-choline pathway for the biosynthesis of phosphatidylcholine. Hepatic cells express both an alpha and a beta2 isoform of CT and can also synthesize phosphatidylcholine via the sequential methylation of phosphatidylethanolamine catalyzed by phosphatidylethanolamine N-methyltransferase. To ascertain the functional importance of CTalpha, we created a mouse in which the hepatic CTalpha gene was specifically inactivated by the Cre/LoxP procedure. In CTalpha knockout mice, hepatic CT activity (due to residual CTbeta2 activity as well as activity in nonhepatic cells) was 15% of normal, whereas phosphatidylethanolamine N-methyltransferase activity was elevated 2-fold compared with controls. Lipid analyses of the liver indicated that female knockout mice had reduced phosphatidylcholine levels and accumulated triacylglycerols. The plasma phosphatidylcholine concentration was reduced in the CTalpha knockout (independent of gender), as were levels of high density lipoproteins (cholesterol and apoAI) and very low density lipoproteins (triacylglycerols and apoB100). Experiments in which mice were injected with Triton WR1339 indicated that apoB secretion was decreased in hepatic-specific CTalpha knockout mice compared with controls. These results suggest an important role for hepatic CTalpha in regulating both hepatic and systemic lipid and lipoprotein metabolism.

  13. Role of lysophosphatidylcholine in the inhibition of endothelial cell motility by oxidized low density lipoprotein.

    PubMed Central

    Murugesan, G; Fox, P L

    1996-01-01

    Endothelial cell (EC) movement is required for the development and repair of blood vessels. We have previously shown that LDL oxidized by transition metals almost completely suppressed the wound-healing migratory response of vascular EC in vitro. We now report that lysophosphatidylcholine (lysoPC), a lipid component of oxidized LDL, has an important role in the antimigratory activity of the lipoprotein. Purified 1-palmitoyl lysoPC inhibited movement with a half-maximal activity at 12-15 micrometers, and near complete inhibition at 20 micrometers; the inhibitory concentration of lysoPC was consistent with its abundance in oxidized LDL. The inhibition was not due to cytotoxicity since protein synthesis was unaffected and since EC movement was restored after removal of lysoPC. Lysophospholipid activity was dependent on lipid structure. LysoPC's containing 1-position C16 or C18 saturated fatty acids were antimigratory, but those containing C < or = 14 saturated fatty acids or polyunsaturated fatty acids were not. The activity of 1-palmitoyl lysolipids with various head groups was examined. Lysophosphatidylinositol was more antimigratory than lysophosphatidylglycerol and lysophosphatidylcholine, which were more potent than lysophosphatidylserine and lysophosphatidylethanolamine. Monoglyceride was inactive while lysophosphatidate had promigratory activity. These results are consistent with head group size rather than charge as a critical determinant of activity. To show that lysophospholipids within an intact lipoprotein were active, LDL was treated with bee venom phospholipase A2 (PLA2). The modified lipoprotein inhibited EC movement to the same extent as iron-oxidized LDL and antimigratory activity correlated with the amount of lysoPC formed. To determine antimigratory activity of lysoPC present in oxidized LDL, lipid extracts from oxidized LDL were fractionated by normal phase HPLC. The fraction comigrating with lysoPC had nearly the same activity as the total extract

  14. Is the oxidation of high-density lipoprotein lipids different than the oxidation of low-density lipoprotein lipids?

    PubMed

    Thomas, M J; Chen, Q; Zabalawi, M; Anderson, R; Wilson, M; Weinberg, R; Sorci-Thomas, M G; Rudel, L L

    2001-02-13

    This article gives detailed insight into the kinetics of high-density lipoprotein (HDL) oxidation catalyzed by azobis(2-amidinopropane).dihydrochloride (ABAP) or by copper. ABAP initialized oxidation of human HDL 3-4 times faster than non-human primate HDL with a similar composition. The oxidizability of non-human primate HDL was 1000 times lower than the oxidizability calculated from rate constants derived from liposome oxidation, suggesting that there is a slow step in HDL oxidation not present in liposomes. Saturable binding of copper to HDL was a significant feature of copper-catalyzed oxidation. Binding constants (K(m)) for non-human primate HDL were 2-3-fold lower than those for human HDL. Copper-catalyzed oxidation of non-human primate HDL was slower than that of human HDL, but human HDL(2) and HDL(3) oxidized at about the same rate. Overall, the kinetics describing the oxidation of HDL were mechanistically similar to those reported for LDL, suggesting that HDL lipids were as easily oxidized as LDL lipids and that HDL will be easily oxidized in vivo when exposed to agents that oxidize LDL.

  15. Mechanobiology of low-density lipoprotein transport within an arterial wall--impact of hyperthermia and coupling effects.

    PubMed

    Chung, Stephen; Vafai, Kambiz

    2014-01-03

    The effects of hyperthermia, coupling attributes and property variations on Low-density lipoprotein (LDL) transport within a multi-layered wall while accounting for the fluid structure interaction (FSI) is analyzed in this work. To understand the potential impact of the hyperthermia process, thermo-induced attributes are incorporated, accounting for the plasma flow, mass transfer, as well as the elastic wall structure. The coupling effect of osmotic pressure, Soret and Dufour diffusion is discussed and their influence on LDL transport is examined, demonstrating that only the Soret effect needs to be accounted for. The effect of thermal expansion on changing the behavior of flow, mass transport, and elastic structure is illustrated and analyzed while incorporating the variations in the effective LDL diffusivity and consumption rate, as well as other dominating parameters. It is shown that hyperthermia results in an enhancement in LDL transport by increasing the concentration levels within the arterial wall.

  16. Protection by polyphenols of postprandial human plasma and low-density lipoprotein modification: the stomach as a bioreactor.

    PubMed

    Kanner, Joseph; Gorelik, Shlomit; Roman, Sirota; Kohen, Ron

    2012-09-12

    Recent studies dramatically showed that the removal of circulating modified low-density lipoprotein (LDL) results in complete prevention of atherosclerosis. The gastrointestinal tract is constantly exposed to food, some of it containing oxidized compounds. Lipid oxidation in the stomach was demonstrated by ingesting heated red meat in rats. Red wine polyphenols added to the rats' meat diet prevented lipid peroxidation in the stomach and absorption of malondialdehyde (MDA) in rat plasma. In humans, postprandial plasma MDA levels rose by 3-fold after a meal of red meat cutlets. MDA derived from meat consumption caused postprandial plasma LDL modification in human. The levels of plasma MDA showed a 75% reduction by consumption of red wine polyphenols during the meat meal. Locating the main biological site of action of polyphenols in the stomach led to a revision in the understanding of how antioxidants work in vivo and may help to elucidate the mechanism involved in the protective effects of polyphenols in human health.

  17. Are plant-based diets efficacious in lowering total serum cholesterol and low-density lipoprotein levels?

    PubMed

    Ware, Kathrine M

    2014-06-01

    Cardiovascular disease is a leading cause of morbidity and mortality in the U.S. and around the globe. A large body of literature accumulated over the past several decades has shown the benefit of lowering serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels to reduce cardiovascular risk. National guidelines suggest therapeutic lifestyle changes, beginning with diet, as a first step toward lowering TC and LDL-C. It has been suggested a plant-based, low fat diet can substantially reduce TC and LDL- C and thereby reduce risk of cardiovascular disease. The purpose of this review is to examine the state of the science regarding the efficacy of plant-based diets in reducing serum TC and LDL-C levels. While results of the research review indicate some benefit, strong evidence supporting the efficacy of plant-based diet in reducing atherogenic lipids is lacking.

  18. Isradipine, a calcium-entry blocker, decreases vascular (125-I)low-density lipoprotein entry in hypercholesterolemic rabbits

    SciTech Connect

    Sinzinger, H.; Lupattelli, G.; Virgolini, I.; Gerakakis, A.; Fitscha, P.; Molinari, E.; Angelberger, P. Vienna, Austria)

    1991-04-01

    In 72 male rabbits aged 6 months, the endothelium of the abdominal aorta was abraded by a Fogarthy catheter. The animals were then fed a 1% cholesterol-supplemented diet for 4 weeks. In addition, half of the animals were treated for the entire period with isradipine (0.3 mg/kg daily), a dihydropyridine calcium antagonist; the other 36 animals served as controls. One hour and 3, 6, 12, 24, and 48 hours before the animals were killed, (125-I)low-density lipoprotein (LDL 10 microCi) was administered intravenously (i.v.) to six animals in each group. The (125-I)LDL entry was quantified in the abdominal aorta according to the type and presence of endothelial lining. Isradipine significantly reduced the (125-I)LDL entry at most time intervals. In parallel, an increase in vascular prostaglandin (PGI2) synthesis was noted, which might be the underlying mechanism for the decreased LDL entry.

  19. Comparative time-courses of copper-ion-mediated protein and lipid oxidation in low-density lipoprotein.

    PubMed

    Knott, Heather M; Baoutina, Anna; Davies, Michael J; Dean, Roger T

    2002-04-15

    Free radicals damage both lipids and proteins and evidence has accumulated for the presence of both oxidised lipids and proteins in aged tissue samples as well as those from a variety of pathologies including atherosclerosis, diabetes, and Parkinson's disease. Oxidation of the protein and lipid moieties of low-density lipoprotein is of particular interest due to its potential role in the unregulated uptake of lipids and cholesterol by macrophages; this may contribute to the initial stage of foam cell formation in atherosclerosis. In the study reported here, we examined the comparative time-courses of lipid and protein oxidation during copper-ion-mediated oxidation of low-density lipoprotein. We show that there is an early, lipid-mediated loss of 40-50% of the Trp residues of the apoB100 protein. There is no comparable loss over an identical period during the copper-ion-mediated oxidation of lipid-free BSA. Concomitant with Trp loss, the antioxidant alpha-tocopherol is consumed with subsequent extensive lipid peroxidation. Further changes to the protein, including the copper-ion-dependent 3.5-fold increase in 3,4-dihydroxyphenylalanine and the copper-ion-independent 3-5-fold increase in o-tyrosine, oxidation products of Tyr and Phe, respectively, only occur after maximal lipid peroxidation. Long incubation periods result in depletion of 3,4-dihydroxyphenylalanine, presumably reflecting further oxidative changes. Overall, copper-ion-mediated oxidation of LDL appears to proceed initially by lipid radical-dependent processes, even though some of the earliest detectable changes occur on the apoB100 protein. This is followed by extensive lipid peroxidation and subsequent additional oxidation of aromatic residues on apoB100, though it is not yet clear whether this late protein oxidation is lipid-dependent or occurs as a result of direct radical attack.

  20. Low density lipoprotein subclasses and response to a low-fat diet in healthy men

    SciTech Connect

    Krauss, R.M.; Dreon, D.M.

    1994-11-01

    Lipid and lipoprotein response to reduced dietary fat intake was investigated in relation to differences in distribution of LDL subclasses among 105 healthy men consuming high-fat (46%) and low-fat (24%) diets in random order for six weeks each. On high-fat, 87 subjects had predominantly large, buoyant LDL as measured by gradient gel electrophoresis and confirmed by analytic ultracentrifugation (pattern A), while the remainder had primarily smaller, denser LDL (pattern B). On low-fat, 36 men changed from pattern A to B. Compared with the 51 men in the stable A group, men in the stable B group (n = 18) had a three-fold greater reduction in LDL cholesterol and significantly greater reductions in plasma apoB and mass of intermediate (LDL II) and small (LDL III) LDL subtractions measured by analytic ultracentrifugation. In both stable A and change groups, reductions in LDL-cholesterol were not accompanied by reduced plasma apoB, consistent with the observation of a shift in LDL particle mass from larger, lipid-enriched (LDL I and II) to smaller, lipid-depleted (LDL III and IV) subfractions, without significant change in particle number. Genetic and environmental factors influencing LDL subclass distributions thus may also contribute substantially to interindividual variation in response to a low-fat diet.

  1. Inherited susceptibility determines the distribution of dense low-density lipoprotein subfraction profiles in familial combined hyperlipidemia.

    PubMed Central

    Bredie, S. J.; Kiemeney, L. A.; de Haan, A. F.; Demacker, P. N.; Stalenhoef, A. F.

    1996-01-01

    Familial combined hyperlipidemia (FCH) is a heritable lipid disorder, in which dense low-density lipoprotein (LDL) subfraction profiles due to a predominance of small dense LDL particles are frequently observed. These small dense LDL particles are associated with cardiovascular disease. Using segregation analysis, we investigated to what extent these LDL subfraction profiles are genetically determined; also, the mode of inheritance was studied. Individual LDL subfraction profiles were determined by density gradient ultracentrifugation in 623 individuals of 40 well-defined Dutch FCH families. The individual LDL subfraction profile was defined as a quantitative trait by the continuous variable K, a reliable estimate of the relative contribution of each LDL subfraction to the overall profile. Variation in parameter K due to age, sex, and hormonal status was taken into account by introducing liability classes. Segregation analysis was performed by fitting a series of class D regressive models, implemented in the Statistical Analysis for Genetic Epidemiology (SAGE) program, after which genetic models were compared using log-likelihood ratio tests. Our data show that 60% of the variability of parameter K could be explained by lipid and lipoprotein levels and that a major autosomal locus, recessively inherited, with a population frequency of .42 +/- .07, and an additional polygenic component of .25 best explained the clustering of atherogenic dense LDL subfraction profiles in these FCH families. Therefore, dense LDL subfraction profiles, associated with elevated lipid levels, appear to have a genetic basis in FCH. PMID:8644746

  2. Steatohepatitis and liver fibrosis are predicted by the characteristics of very low density lipoprotein in nonalcoholic fatty liver disease

    PubMed Central

    Jiang, Zhenghui G.; Tapper, Elliot B.; Connelly, Margery A.; Pimentel, Carolina F. M. G.; Feldbrügge, Linda; Kim, Misung; Krawczyk, Sarah; Afdhal, Nezam; Robson, Simon C.; Herman, Mark A.; Otvos, James D.; Mukamal, Kenneth J.; Lai, Michelle

    2016-01-01

    Background & Aims A major challenge in the management of nonalcoholic fatty liver disease (NAFLD) is to identify patients with nonalcoholic steatohepatitis (NASH) and early liver fibrosis. The progression of NAFLD is accompanied by distinctive changes in very low density lipoprotein (VLDL), a lipoprotein particle produced exclusively in the liver. Herein, we sought to determine the characteristics of VLDL profiles associated with NASH and liver fibrosis. Methods We evaluated VLDL profiles of 128 patients from a single centre NAFLD registry, and examined VLDL size, total and subclass VLDL concentrations in relation to NAFLD activity score (NAS), steatohepatitis and liver fibrosis as determined by liver biopsy. Results A near linear relationship was observed between mean VLDL particle size and NAFLD activity score (NAS). In multivariate models, VLDL particle size was significantly associated with both NAS and NASH, after adjustment for BMI and diabetes. A decrease in small VLDL particle concentration was associated with more advanced liver fibrosis. In receiver operative characteristic analyses, mean VLDL size performed similarly to cytokeratin 18 in predicting NASH, whereas small VLDL particle concentration had similar performance to NAFLD fibrosis score in predicting stage 2 or above liver fibrosis. Conclusions The increase in mean VLDL size in NASH and decrease in small VLDL particle concentration in liver fibrosis likely reflect changes in the number and state of hepatocytes associated with NASH and fibrosis. In addition to its value in risk stratification of cardiovascular diseases, circulating VLDL profile may provide information for the staging of NAFLD disease severity. PMID:26815314

  3. Multiple rare variants in NPC1L1 associated with reduced sterol absorption and plasma low-density lipoprotein levels

    PubMed Central

    Cohen, Jonathan C.; Pertsemlidis, Alexander; Fahmi, Saleemah; Esmail, Sophie; Vega, Gloria L.; Grundy, Scott M.; Hobbs, Helen H.

    2006-01-01

    An approach to understand quantitative traits was recently proposed based on the finding that nonsynonymous (NS) sequence variants in certain genes are preferentially enriched at one extreme of the population distribution. The NS variants, although individually rare, are cumulatively frequent and influence quantitative traits, such as plasma lipoprotein levels. Here, we use the NS variant technique to demonstrate that genetic variation in NPC1L1 contributes to variability in cholesterol absorption and plasma levels of low-density lipoproteins (LDLs). The ratio of plasma campesterol (a plant sterol) to lathosterol (a cholesterol precursor) was used to estimate relative cholesterol absorption in a population-based study. Nonsynonymous sequence variations in NPC1L1 were five times more common in low absorbers (n = 26 of 256) than in high absorbers (n = 5 of 256) (P < 0.001). The rare variants identified in low absorbers were found in 6% of 1,832 African-Americans and were associated with lower plasma levels of LDL cholesterol (LDL-C) (96 ± 36 mg/dl vs. 105 ± 36 mg/dl; P = 0.005). These data, together with prior findings, reveal a genetic architecture for LDL-C levels that does not conform to current models for quantitative traits and indicate that a significant fraction of genetic variance in LDL-C is due to multiple alleles with modest effects that are present at low frequencies in the population. PMID:16449388

  4. Macrophage-derived foam cells freshly isolated from rabbit atherosclerotic lesions degrade modified lipoproteins, promote oxidation of low-density lipoproteins, and contain oxidation-specific lipid-protein adducts.

    PubMed Central

    Rosenfeld, M E; Khoo, J C; Miller, E; Parthasarathy, S; Palinski, W; Witztum, J L

    1991-01-01

    Pure macrophage-derived foam cells (MFC) were isolated from the aortas of rabbits made atherosclerotic by balloon deendothelialization followed by diet-induced hypercholesterolemia. The MFC were isolated under sterile conditions using an enzymatic digestion procedure and discontinuous density gradient centrifugation. The purity of the MFC preparations was verified immunocytochemically with the macrophage specific monoclonal antibody RAM-11. MFC plated in medium containing 0.5% FCS for 24 h contained approximately 600 micrograms cholesterol per mg cell protein, 80% of which was esterified cholesterol. The MFC specifically degraded low density lipoprotein (LDL), acetyl-LDL, copper oxidized LDL, and beta-very low density lipoprotein (beta-VLDL) at rates comparable to mouse peritoneal macrophages (MPM) in 5-h assays. MFC within sections of the atherosclerotic lesions from the ballooned rabbits as well as the MFC isolated from the same lesions in the presence of antioxidants, exhibited positive immunoreactivity with polyclonal guinea pig antisera and mouse monoclonal antibodies directed against malondialdehyde-LDL, and 4-hydroxynonal-LDL. The MFC also exhibited the capacity to induce the oxidation of LDL at rates comparable to those exhibited by MPM and rabbit aortic endothelial cells. These data provide direct evidence that arterial wall macrophages express modified LDL receptors in vivo, contain epitopes found in oxidized-LDL and are capable of oxidizing LDL even when maximally loaded with cholesterol. Images PMID:1985115

  5. Lipoprotein-associated phospholipase A2, platelet-activating factor acetylhydrolase, generates two bioactive products during the oxidation of low-density lipoprotein: use of a novel inhibitor.

    PubMed Central

    MacPhee, C H; Moores, K E; Boyd, H F; Dhanak, D; Ife, R J; Leach, C A; Leake, D S; Milliner, K J; Patterson, R A; Suckling, K E; Tew, D G; Hickey, D M

    1999-01-01

    A novel and potent azetidinone inhibitor of the lipoprotein-associated phospholipase A2 (Lp-PLA2), i.e. platelet-activating factor acetylhydrolase, is described for the first time. This inhibitor, SB-222657 (Ki=40+/-3 nM, kobs/[I]=6. 6x10(5) M-1.s-1), is inactive against paraoxonase, is a poor inhibitor of lecithin:cholesterol acyltransferase and has been used to investigate the role of Lp-PLA2 in the oxidative modification of lipoproteins. Although pretreatment with SB-222657 did not affect the kinetics of low-density lipoprotein (LDL) oxidation by Cu2+ or an azo free-radical generator as determined by assay of lipid hydroperoxides (LOOHs), conjugated dienes and thiobarbituric acid-reacting substances, in both cases it inhibited the elevation in lysophosphatidylcholine content. Moreover, the significantly increased monocyte chemoattractant activity found in a non-esterified fatty acid fraction from LDL oxidized by Cu2+ was also prevented by pretreatment with SB-222657, with an IC50 value of 5.0+/-0.4 nM. The less potent diastereoisomer of SB-222657, SB-223777 (Ki=6.3+/-0.5 microM, kobs/[I]=1.6x10(4) M-1.s-1), was found to be significantly less active in both assays. Thus, in addition to generating lysophosphatidylcholine, a known biologically active lipid, these results demonstrate that Lp-PLA2 is capable of generating oxidized non-esterified fatty acid moieties that are also bioactive. These findings are consistent with our proposal that Lp-PLA2 has a predominantly pro-inflammatory role in atherogenesis. Finally, similar studies have demonstrated that a different situation exists during the oxidation of high-density lipoprotein, with enzyme(s) other than Lp-PLA2 apparently being responsible for generating lysophosphatidylcholine. PMID:10024526

  6. ApoAV reduces plasma triglycerides by inhibiting very low density lipoprotein-triglyceride (VLDL-TG) production and stimulating lipoprotein lipase-mediated VLDL-TG hydrolysis.

    PubMed

    Schaap, Frank G; Rensen, Patrick C N; Voshol, Peter J; Vrins, Carlos; van der Vliet, Hendrik N; Chamuleau, Robert A F M; Havekes, Louis M; Groen, Albert K; van Dijk, Ko Willems

    2004-07-02

    ApoAV has been discovered recently as a novel modifier of triglyceride (TG) metabolism, but the pathways involved are currently unknown. To gain insight into the function of apoAV, adenovirus-mediated gene transfer of murine apoa5 to C57Bl/6 mice was employed. The injection of low doses of Ad-apoa5 (1-5 x 10(8) plaqueforming units/mouse) dose-dependently reduced plasma very low density lipoprotein (VLDL)-TG levels. First, we evaluated whether a reduced hepatic VLDL production contributed to the TG-lowering effect. Ad-apoa5 treatment dose-dependently diminished (29-37%) the VLDL-TG production rate without affecting VLDL particle production, suggesting that apoAV impairs the lipidation of apoB. Second, Ad-apoa5 treatment dose-dependently reduced (68-88%) the postprandial hypertriglyceridemia following an intragastric fat load, suggesting that apoAV also stimulates the lipoprotein lipase (LPL)-dependent clearance of TG-rich lipoproteins. Indeed, recombinant apoAV was found to dose-dependently stimulate LPL activity up to 2.3-fold in vitro. Accordingly, intravenously injected VLDL-like TG-rich emulsions were cleared at an accelerated rate concomitant with the increased uptake of emulsion TG-derived fatty acids by skeletal muscle and white adipose tissue in Ad-apoa5-treated mice. From these data, we conclude that apoAV is a potent stimulator of LPL activity. Thus, apoAV lowers plasma TG by both reducing the hepatic VLDL-TG production rate and by enhancing the lipolytic conversion of TG-rich lipoproteins.

  7. Electronegative low density lipoprotein induces renal apoptosis and fibrosis: STRA6 signaling involved[S

    PubMed Central

    Chen, Chao-Hung; Ke, Liang-Yin; Chan, Hua-Chen; Lee, An-Sheng; Lin, Kun-Der; Chu, Chih-Sheng; Lee, Mei-Yueh; Hsiao, Pi-Jung; Hsu, Chin; Chen, Chu-Huang; Shin, Shyi-Jang

    2016-01-01

    Dyslipidemia has been proven to capably develop and aggravate chronic kidney disease. We also report that electronegative LDL (L5) is the most atherogenic LDL. On the other hand, retinoic acid (RA) and RA receptor (RAR) agonist are reported to be beneficial in some kidney diseases. “Stimulated by retinoic acid 6” (STRA6), one retinol-binding protein 4 receptor, was recently identified to regulate retinoid homeostasis. Here, we observed that L5 suppressed STRA6 cascades [STRA6, cellular retinol-binding protein 1 (CRBP1), RARs, retinoid X receptor α, and retinol, RA], but L5 simultaneously induced apoptosis and fibrosis (TGFβ1, Smad2, collagen 1, hydroxyproline, and trichrome) in kidneys of L5-injected mice and L5-treated renal tubular cells. These L5-induced changes of STRA6 cascades, renal apoptosis, and fibrosis were reversed in kidneys of LOX1−/− mice. LOX1 RNA silencing and inhibitor of c-Jun N-terminal kinase and p38MAPK rescued the suppression of STRA6 cascades and apoptosis and fibrosis in L5-treated renal tubular cells. Furthermore, crbp1 gene transfection reversed downregulation of STRA6 cascades, apoptosis, and fibrosis in L5-treated renal tubular cells. For mimicking STRA6 deficiency, efficient silencing of STRA6 RNA was performed and was found to repress STRA6 cascades and caused apoptosis and fibrosis in L1-treated renal tubular cells. In summary, this study reveals that electronegative L5 can cause kidney apoptosis and fibrosis via the suppression of STRA6 cascades, and implicates that STRA6 signaling may be involved in dyslipidemia-mediated kidney disease. PMID:27256691

  8. Macrophage Differentiation from Monocytes Is Influenced by the Lipid Oxidation Degree of Low Density Lipoprotein

    PubMed Central

    Seo, Jin-Won; Yang, Eun-Jeong; Yoo, Kyung-Hwa; Choi, In-Hong

    2015-01-01

    LDL plays an important role in atherosclerotic plaque formation and macrophage differentiation. However, there is no report regarding the oxidation degree of LDL and macrophage differentiation. Our study has shown that the differentiation into M1 or M2 macrophages is related to the lipid oxidation level of LDL. Based on the level of lipid peroxidation, LDL is classified into high-oxidized LDL (hi-oxLDL) and low-oxidized LDL (low-oxLDL). The differentiation profiles of macrophages were determined by surface receptor expression and cytokine secretion profiles. Low-oxLDL induced CD86 expression and production of TNF-α and IL-12p40 in THP-1 cells, indicating an M1 macrophage phenotype. Hi-oxLDL induced mannose receptor expression and production of IL-6 and monocyte chemoattractant protein-1, which mostly match the phenotype of M2 macrophages. Further supporting evidence for an M2 polarization by hi-oxLDL was the induction of LOX-1 in THP-1 cells treated with hi-oxLDL but not with low-oxLDL. Similar results were obtained in primary human monocytes. Therefore, our results strongly suggest that the oxidation degree of LDL influences the differentiation of monocytes into M1 or M2 macrophages and determines the inflammatory fate in early stages of atherosclerosis. PMID:26294848

  9. Orange juice decreases low-density lipoprotein cholesterol in hypercholesterolemic subjects and improves lipid transfer to high-density lipoprotein in normal and hypercholesterolemic subjects.

    PubMed

    Cesar, Thais B; Aptekmann, Nancy P; Araujo, Milena P; Vinagre, Carmen C; Maranhão, Raul C

    2010-10-01

    Orange juice (OJ) is regularly consumed worldwide, but its effects on plasma lipids have rarely been explored. This study hypothesized that consumption of OJ concentrate would improve lipid levels and lipid metabolism, which are important in high-density lipoprotein (HDL) function in normolipidemic (NC) and hypercholesterolemic (HCH) subjects. Fourteen HCH and 31 NC adults consumed 750 mL/day OJ concentrate (1:6 OJ/water) for 60 days. Eight control subjects did not consume OJ for 60 days. Plasma was collected before and on the last day for biochemical analysis and an in vitro assay of transfers of radioactively labeled free-cholesterol, cholesteryl esters, phospholipids, and triglycerides from lipoprotein-like nanoemulsions to HDL. Orange juice consumption decreased low-density lipoprotein cholesterol (160 ± 17 to 141 ± 26 mg/dL, P < .01) in the HCH group but not in the NC group. HDL-cholesterol and triglycerides remained unchanged in both groups. Free-cholesterol transfer to HDL increased (HCH: 4.4 ± 2 to 5.6 ± 1%, NC: 3.2 ± 2 to 6.2 ± 1%, P< .05) whereas triglyceride (HCH 4.9 ± 1 to 3.1 ± 1%, NC 4.4 ± 1 to 3.4 ± 1%, P< .05) and phospholipid (HCH 21.6 ± 2 to 18.6 ± 3%, NC 20.2 ± 2 to 18.4 ± 2%, P < .05) transfers decreased in both groups. Cholesteryl-ester transfer decreased only in HCH (3.6 ± 1 to 3.1 ± 1%, P < .05), but not in NC. In control subjects, plasma lipids and transfers were unaltered for 60 days. Thus, by decreasing atherogenic low-density lipoprotein cholesterol in HCH and increasing HDL ability to take up free cholesterol in HCH and NC, OJ may be beneficial to both groups as free-cholesterol transfer to HDL is crucial for cholesterol esterification and reverse cholesterol transport.

  10. Puerarin protects endothelial cells from oxidized low density lipoprotein induced injuries via the suppression of LOX-1 and induction of eNOS.

    PubMed

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

    2014-04-01

    Oxidized low density lipoprotein (oxLDL) induced injury of endothelial cells is considered to be the first step in the pathogenesis of atherosclerosis. This study aimed to investigate some of the effects and mechanisms of puerarin on oxLDL-induced endothelial injuries. We measured cell viability, and the release of lactate dehydrogenase (LDH), nitric oxide (NO), and interleukin-8 (IL-8) to evaluate the protective effects of puerarin. Intracellular reactive oxygen species (ROS) were detected using 2',7'-dichlorofluorescein diacetate (DCFH-DA). The expression of lectin-like low-density lipoprotein receptor-1 (LOX-1), endothelial nitric oxide synthase (eNOS), cyclooxygenase 2 (COX-2), p38MAPK, and protein kinase B (PKB) phosphorylation, nuclear factor-κB (NF-κB) nuclear translocation, and inhibitor of κB (IκB) degradation were detected using quantitative real-time PCR or Western blot. The results showed that oxLDL significantly decreased cell viability, increased LDH and IL-8 release, inhibited NO production, and induced COX-2 expression. Pretreatment with puerarin led to a strong inhibition of these effects. OxLDL stimulated the expression of LOX-1, the overproduction of ROS, the phosphorylation of p38MAPK, the dephosphorylation of PKB, activation of NF-κB, and the degradation of IκB. These oxLDL-induced effects were suppressed after puerarin pretreatment. These results suggest that puerarin inhibits oxLDL-induced endothelial cell injuries, at least in part, via inhibition of the LOX-1-mediated p38MAPK-NF-κB inflammatory and the PKB-eNOS signaling pathways.

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

    SciTech Connect

    Mazière, Cécile; Salle, Valéry; Gomila, Cathy; Mazière, Jean-Claude

    2013-10-18

    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 in 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.

  12. On the pathogenesis of atherosclerosis: enzymatic transformation of human low density lipoprotein to an atherogenic moiety

    PubMed Central

    1995-01-01

    Combined treatment with trypsin, cholesterol esterase, and neuraminidase transforms LDL, but not HDL or VLDL, to particles with properties akin to those of lipid extracted from atherosclerotic lesions. Single or double enzyme modifications, or treatment with phospholipase C, or simple vortexing are ineffective. Triple enzyme treatment disrupts the ordered and uniform structure of LDL particles, and gives rise to the formation of inhomogeneous lipid droplets 10-200 nm in diameter with a pronounced net negative charge, but lacking significant amounts of oxidized lipid. Enzymatically modified LDL (E- LDL), but not oxidatively modified LDL (ox-LDL), is endowed with potent complement-activating capacity. As previously found for lipid isolated from atherosclerotic lesions, complement activation occurs to completion via the alternative pathway and is independent of antibody. E-LDL is rapidly taken up by human macrophages to an extent exceeding the uptake of acetylated LDL (ac-LDL) or oxidatively modified LDL. After 16 h, cholesteryl oleate ester formation induced by E-LDL (50 micrograms/ml cholesterol) was in the range of 6-10 nmol/mg protein compared with 3-6 nmol/mg induced by an equivalent amount of acetylated LDL. At this concentration, E-LDL was essentially devoid of direct cytotoxic effects. Competition experiments indicated that uptake of E- LDL was mediated in part by ox-LDL receptor(s). Thus, approximately 90% of 125I-ox-LDL degradation was inhibited by a 2-fold excess of unlabeled E-LDL. Uptake of 125I-LDL was not inhibited by E-LDL. We hypothesize that extracellular enzymatic modification may represent an important step linking subendothelial deposition of LDL to the initiation of atherosclerosis. PMID:7500042

  13. Resistance of lipoprotein(a) to lipid peroxidation induced by oxygenated free radicals produced by gamma radiolysis: a comparison with low-density lipoprotein.

    PubMed Central

    Beaudeux, J L; Gardes-Albert, M; Delattre, J; Legrand, A; Rousselet, F; Peynet, J

    1996-01-01

    Lipid peroxidation of lipoprotein(a) [Lp(a)] by defined oxygen-centred free radicals (O2-/OH, O2-, O2-/HO2) produced by gamma radiolysis was compared with that of paired samples of low-density lipoprotein (LDL). Lp(a) appeared to be more resistant to oxidation than LDL, as indicated by the kinetic study of four markers of lipid peroxidation; decrease in vitamin E, formation of conjugated dienes and aldehydic products, and modification of electrophoretic mobility. In contrast, similar kinetics of lipid peroxidation were obtained for LDL and Lp(a-), which is the lipoparticle issued following the reductive cleavage of apolipoprotein(a) from Lp(a), thus suggesting that the greater resistance of Lp(a) to lipid peroxidation was due to the presence of apolipoprotein(a). Lipid peroxidation of Lp(a) and LDL induced by peroxyl radicals, which were produced by an azo compound [2,2'-azobis-(2-amidinopropane)dihydrochloride], confirmed both the resistance of Lp(a) to lipid peroxidation and the propensity of Lp(a-) to exhibit a greater susceptibility to oxidation than intact Lp(a). Our findings also indicated that the high content of apolipoprotein(a) in N-acetylneuraminic acid residues was only partly responsible for the resistance of Lp(a) to oxidation. PMID:8660295

  14. Association between moderately oxidized low-density lipoprotein and high-density lipoprotein particle subclass distribution in hemodialyzed and post-renal transplant patients.

    PubMed

    Kimak, Elżbieta; Hałabiś, Magdalena; Baranowicz-Gąszczyk, Iwona; Solski, Janusz; Książek, Andrzej

    2011-05-01

    Disturbances in the metabolism of lipoprotein profiles and oxidative stress in hemodialyzed (HD) and post-renal transplant (Tx) patients are proatherogenic, but elevated concentrations of plasma high-density lipoprotein (HDL) reduce the risk of cardiovascular disease. We investigated the concentrations of lipid, lipoprotein, HDL particle, oxidized low-density lipoprotein (ox-LDL) and anti-ox-LDL, and paraoxonase-1 (PON-1) activity in HD (n=33) and Tx (n=71) patients who were non-smokers without active inflammatory disease, liver disease, diabetes, or malignancy. HD patients had moderate hypertriglyceridemia, normocholesterolemia, low HDL-C, apolipoprotein A-I (apoA-I) and HDL particle concentrations as well as PON-1 activity, and increased ox-LDL and anti-ox-LDL levels. Tx patients had hypertriglyceridemia, hypercholesterolemia, moderately decreased HDL-C and HDL particle concentrations and PON-1 activity, and moderately increased ox-LDL and anti-ox-LDL levels as compared to the reference, but ox-LDL and anti-ox-LDL levels and PON-1 activity were more disturbed in HD patients. However, in both patient groups, lipid and lipoprotein ratios (total cholesterol (TC)/HDL-C, LDL-C/HDL-C, triglyceride (TG)/HDL-C, HDL-C/non-HDL-C, apoA-I/apoB, HDL-C/apoA-I, TG/HDL) were atherogenic. The Spearman's rank coefficient test showed that the concentration of ox-LDL correlated positively with HDL particle level (R=0.363, P=0.004), and negatively with TC (R=-0.306, P=0.012), LDL-C (R=-0.283, P=0.020), and non-HDL-C (R=-0.263, P=0.030) levels in Tx patients. Multiple stepwise forward regression analysis in Tx patients demonstrated that ox-LDL concentration, as an independent variable, was associated significantly positively with HDL particle level. The results indicated that ox-LDL and decreased PON-1 activity in Tx patients may give rise to more mildly-oxidized HDLs, which are less stable, easily undergo metabolic remodeling, generate a greater number of smaller pre-β-HDL particles

  15. Dietary Carbohydrate Modifies the Inverse Association Between Saturated Fat Intake and Cholesterol on Very Low-Density Lipoproteins.

    PubMed

    Wood, A C; Kabagambe, E K; Borecki, I B; Tiwari, H K; Ordovas, J M; Arnett, D K

    2011-08-23

    We aimed to investigate the relationship between dietary saturated fat on fasting triglyceride (TG) and cholesterol levels, and any mediation of this relationship by dietary carbohydrate intake. Men and women in the NHLBI Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) study (n = 1036, mean age ± SD = 49 ± 16 y) were included. Mixed linear models were run with saturated fat as a predictor variable and fasting TG, very low density lipoprotein cholesterol (VLDL-C), low density cholesterol (LDL-C) and high density cholesterol (HDL-C) as separate outcome variables. Subsequent models were run which included dietary carbohydrate as a predictor variable, and an interaction term between saturated fat and carbohydrate. All models controlled for age, sex, BMI, blood pressure and dietary covariates. In models that included only saturated fat as a predictor, saturated fat did not show significant associations with fasting lipids. When carbohydrate intake and an interaction term between carbohydrates and saturated fat intake was included, carbohydrate intake did not associate with lipids, but there was an inverse relationship between saturated fat intake and VLDL-C (P = 0.01) with a significant interaction (P = 0.01) between saturated fat and carbohydrate with regard to fasting VLDL-C concentrations. Similar results were observed for fasting TG levels. We conclude that, when controlling for carbohydrate intake, higher saturated fat was associated with lower VLDL-C and TGs. This was not the case at higher intakes of carbohydrate. This has important implications for dietary advice aimed at reducing TG and VLDL-C levels.

  16. Direct adsorption of low-density lipoprotein and lipoprotein(a) from whole blood: results of the first clinical long-term multicenter study using DALI apheresis.

    PubMed

    Bosch, T; Lennertz, A; Schenzle, D; Dräger, J

    2002-01-01

    Direct adsorption of lipoproteins (DALI) is the first low-density lipoprotein (LDL)-apheresis technique by which atherogenic LDL and lipoprotein(a) (Lp(a)) can be selectively removed from whole blood without plasma separation. The present study was performed to evaluate the efficacy, selectivity and safety of long-term DALI apheresis. Sixty-three hypercholesterolemic coronary patients were treated by weekly DALI sessions. Initial LDL-cholesterol (C) plasma levels averaged 238 +/- 87 mg/dl (range 130-681 mg/dl). On average, 34 sessions (1-45) were performed processing 1.5 patient blood volumes. The primary aim was to acutely reduce LDL-C by >or=60% per session. To this end, three different adsorber sizes could be employed, i.e., DALI 500, 750, and 1000, which were used in 4, 73, and 23% of the 2156 sessions, respectively. On average, 7387 ml of blood were processed in 116 min per session. This resulted in the following mean acute changes: LDL-C 198 --> 63 mg/dl (-69%), Lp(a) 86 --> 32 mg/dl (-64%), triglycerides 185 --> 136 mg/dl (-27%). HDL-C (-11%) and fibrinogen (-15%) were not significantly influenced. The mean long-term reduction of LDL-C was 42% compared to baseline while HDL-C slightly increased in the long run (+4%). The selectivity of LDL removal was good as recoveries of albumin, immunoglobulins, and other proteins exceeded 85%. Ninety-five percent of 2156 sessions were completely uneventful. The most frequent adverse effects were hypotension (1.2% of sessions) and paresthesia (1.1%), which were probably due to citrate anticoagulation. Access problems had to be overcome in 1.5%, adsorber and hardware problems in 0.5% of the sessions. In this multicenter long-term study, DALI apheresis proved to be an efficient, safe, and easy procedure for extracorporeal LDL and Lp(a) elimination.

  17. Both poor cardiorespiratory and weak muscle fitness are related to a high concentration of oxidized low-density lipoprotein lipids.

    PubMed

    Kosola, J; Ahotupa, M; Kyröläinen, H; Santtila, M; Vasankari, T

    2012-12-01

    Good physical fitness is associated with favorable serum lipids. Oxidized low-density lipoprotein (ox-LDL) could be even more atherogenic than serum lipids. We studied the association of ox-LDL and serum lipids with physical fitness. Healthy young (mean age 25 years) men (n=846) underwent maximal oxygen uptake (VO(2max)) and muscle fitness index (MFI) tests and completed a leisure-time physical activity (LTPA) questionnaire. Age (ANCOVA1), age+waist circumference+systolic blood pressure+fasting blood glucose+smoking (ANCOVA3) were used as covariates. The groups with the lowest VO(2max), MFI and LTPA had 23%, 16% and 8% higher concentrations of ox-LDL than the groups with the highest VO(2max) (P<0.0001), MFI (P=0.022) and LTPA (P=0.039) groups, respectively. Subjects with poor fitness (low VO(2max) or low MFI) or low LTPA had elevated levels of ox-LDL/high-density lipoprotein (HDL)-cholesterol, total cholesterol, LDL-cholesterol, triglycerides and a low level of HDL-cholesterol (ANCOVA1, in all, P<0.05). Furthermore, low VO(2max) is associated with a high level of ox-LDL/HDL-cholesterol and triglycerides, and with a low level of HDL-cholesterol (ANCOVA3, in all, P<0.05). Also, subjects with low LTPA had a high ratio of ox-LDL/HDL-cholesterol (ANCOVA1, P=0.001). In conclusion, both poor fitness (both low VO(2max) and low MFI) and low LTPA are associated with a higher concentration of ox-LDL lipids and serum lipids, which may indicate a higher risk for atherosclerosis.

  18. Emerging low-density lipoprotein (LDL) therapies: Management of severely elevated LDL cholesterol--the role of LDL-apheresis.

    PubMed

    McGowan, Mary P

    2013-01-01

    Low-density lipoprotein (LDL)-apheresis is a Food and Drug Administration-approved treatment for patients with homozygous familial hypercholesterolemia (FH) or severe heterozygous FH. Based on electrochemical principles, it selectively removes apolipoprotein B-containing lipoproteins through extracorporeal precipitation with either heparin (Heparin-induced Extracorporeal LDL Precipitation, ie, HELP) or dextran sulfate (Liposorber). LDL-apheresis can lead to an acute decrease in LDL cholesterol (LDL-C) of 70%-80%, but there is a rapid rebound to baseline levels within approximately 2 weeks. LDL-apheresis is typically performed once-a-week in patients with homozygous FH and every other week in those with heterozygous FH to produce time-average LDL-C reductions of ≈ 40%. Side effects associated with LDL-apheresis include hypotension (later found to be due to concomitant use of angiotensin-converting enzyme inhibitors), nausea/vomiting, flushing, angina, and fainting. Posttreatment bleeding can occur secondary to heparin used during the procedure. Challenges associated with LDL-apheresis include vascular access often requiring an arteriovenous fistula (fistulas may clot and require revision over time), the time associated with each treatment session (2-4 hours), the frequency of treatment, and the scarcity of medical centers which perform LDL-apheresis. Given the nature of LDL-apheresis, randomized placebo controlled trials are nearly impossible, and virtually all studies of clinical benefit have been non-randomized investigations of small numbers of subjects. Nonetheless, results from those studies support the benefits of LDL-C reduction for reducing coronary atherosclerosis and cardiovascular events.

  19. Very low density lipoproteins in intestinal lymph: origin, composition, and role in lipid transport in the fasting state

    PubMed Central

    Ockner, Robert K.; Hughes, Faith B.; Isselbacher, Kurt J.

    1969-01-01

    The transport of endogenous lipids in the lipoproteins of mesenteric lymph was studied in fasting rats with mesenteric lymph fistulas. The lymph was found to contain, in addition to chylomicrons (Sf >400), a significant amount of another, more dense, triglyceride-rich fraction, the very low density lipoproteins (VLDL), which showed a peak Sf of 102. The VLDL differed from chylomicrons not only in flotation, but also in per cent lipid composition and electrophoretic mobility in agarose gel. The VLDL fraction was found to contain 47% of the triglyceride and 54% of the cholesterol of fasting lymph and, in the fasting state, was the major lipoprotein species present. When cholestyramine resin was administered intraduodenally, or bile flow was acutely diverted from the intestine, it was demonstrated that the lipids in lymph VLDL, like those in chylomicrons, were derived from the intestine and bile. These data indicate that the VLDL in intestinal lymph are not derived from the plasma but are of intestinal origin. Because certain properties of lymph VLDL were similar to those reported for plasma VLDL (per cent lipid composition, flotation coefficient, and continuing entry into plasma in the fasting state), additional comparisons between these fractions were made. Although lymph VLDL moved to the α2 region in agarose gel, when they were mixed with VLDL-free serum immediately before electrophoresis they showed the α2 mobility of rat serum VLDL. Furthermore, immunoelectrophoretic comparison of partially delipidated lymph and serum VLDL revealed that these fractions shared in common their major apoprotein, and possibly others as well. The fatty acid composition of lymph and serum triglycerides, as determined by gas-liquid chromatography, revealed that although they were generally similar, differences existed which most likely reflected the presence in serum of triglycerides of hepatic origin. These experiments demonstrate the importance of intestinal VLDL in the transport

  20. Genetic variation at the SLCO1B1 gene locus and low density lipoprotein cholesterol lowering response to pravastatin in the elderly

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our goal was to determine whether genetic variation at genes affecting statin metabolism or targets of statin therapy would influence low density lipoprotein (LDL) cholesterol lowering with pravastatin, baseline heart disease, or cardiac endpoints on trial. We examined associations of single nucleot...

  1. Tumor necrosis factor-alpha impairs hepatic insulin signaling and stimulates the overproduction of hepatic apolipoprotein B100-containing very low density lipoproteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanisms underlying hepatic overproduction of apolipoprotein B (apoB) 100-containing very low density lipoproteins (VLDL) in insulin resistance induced by tumor necrosis factor (TNF)-a were investigated. In the present study, we examined the potential role of TNF-a in insulin signaling and lipopro...

  2. Tumor necrosis factor-alpha impairs hepatic insulin signaling and stumlates the overproduction of hepatic apolipoprotein B100-containing very low density lipoproteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mechanisms underlying hepatic overproduction of apolipoprotein B (apoB) 100-containing very low density lipoproteins (VLDL) in insulin resistance induced by tumor necrosis factor (TNF)-a were investigated. In the present study, we examined the potential role of TNF-a in insulin signaling and lipopro...

  3. Plasma clearance of human low-density lipoprotein in human apolipoprotein B transgenic mice is related to particle diameter.

    PubMed

    Berneis, Kaspar; Shames, David M; Blanche, Patricia J; La Belle, Michael; Rizzo, Manfredi; Krauss, Ronald M

    2004-04-01

    To test for intrinsic differences in metabolic properties of low-density lipoprotein (LDL) as a function of particle size, we examined the kinetic behavior of 6 human LDL fractions ranging in size from 251 to 265 A injected intravenously into human apolipoprotein (apo) B transgenic mice. A multicompartmental model was formulated and fitted to the data by standard nonlinear regression using the Simulation, Analysis and Modeling (SAAM II) program. Smaller sized LDL particles (251 to 257 A) demonstrated a significantly slower fractional catabolic rate (FCR) (0.050 +/- 0.045 h(-1)) compared with particles of larger size (262 to 265 A) (0.134 +/- -0.015 h(-1), P <.03), and there was a significant correlation between FCR and the peak LDL diameter of the injected fractions (R(2) =.71, P <.034). The sum of the equilibration parameters, k(2,1) and k(1,2), for smaller LDL (0.255 h(-1) and 0.105 h(-1), respectively) was significantly smaller than that for larger LDL (0.277 h(-1) and 0.248 h(-1), respectively; P <.01), indicative of slower intravascular-extravascular exchange for smaller LDL. Therefore in this mouse model, smaller LDL particles are cleared more slowly from plasma than larger LDL and are exchanged more slowly with the extravascular space. This might be due to compositional or structural features of smaller LDL that lead to retarded clearance.

  4. Minimally modified low density lipoprotein induces monocyte chemotactic protein 1 in human endothelial cells and smooth muscle cells

    SciTech Connect

    Cushing, S.D.; Berliner, J.A.; Valente, A.J.; Territo, M.C.; Navab, M.; Parhami, F.; Gerrity, R.; Schwartz, C.J.; Fogelman, A.M.

    1990-07-01

    After exposure to low density lipoprotein (LDL) that had been minimally modified by oxidation (MM-LDL), human endothelial cells (EC) and smooth muscle cells (SMC) cultured separately or together produced 2- to 3-fold more monocyte chemotactic activity than did control cells or cells exposed to freshly isolated LDL. This increase in monocyte chemotactic activity was paralleled by increases in mRNA levels for a monocyte chemotactic protein 1 (MCP-1) that is constitutively produced by the human glioma U-105MG cell line. Antibody that had been prepared against cultured baboon smooth muscle cell chemotactic factor (anti-SMCF) did not inhibit monocyte migration induced by the potent bacterial chemotactic factor f-Met-Leu-Phe. However, anti-SMCF completely inhibited the monocyte chemotactic activity found in the media of U-105MG cells, EC, and SMC before and after exposure to MM-LDL. Moreover, monocyte migration into the subendothelial space of a coculture of EC and SMC that had been exposed to MM-LDL was completely inhibited by anti-SMCF. Anti-SMCF specifically immunoprecipitated 10-kDa and 12.5-kDa proteins from EC. Incorporation of (35S)methionine into the immunoprecipitated proteins paralleled the monocyte chemotactic activity found in the medium of MM-LDL stimulated EC and the levels of MCP-1 mRNA found in the EC. We conclude that SMCF is in fact MCP-1 and MCP-1 is induced by MM-LDL.

  5. Low density lipoprotein rich in oleic acid is protected against oxidative modification: implications for dietary prevention of atherosclerosis.

    PubMed Central

    Parthasarathy, S; Khoo, J C; Miller, E; Barnett, J; Witztum, J L; Steinberg, D

    1990-01-01

    Oxidative modification of low density lipoprotein (LDL) enhances its potential atherogenicity in several ways, notably by enhancing its uptake into macrophages. In vivo studies in the rabbit show that inhibition of LDL oxidation slows the progression of atherosclerotic lesions. In the present studies, rabbits were fed either a newly developed variant sunflower oil (Trisun 80), containing more than 80% oleic acid and only 8% linoleic acid, or conventional sunflower oil, containing only 20% oleic acid and 67% linoleic acid. LDL isolated from the plasma of animals fed the variant sunflower oil was highly enriched in oleic acid and very low in linoleic acid. These oleate-rich LDL particles were remarkably resistant to oxidative modification. Even after 16-hr exposure to copper-induced oxidation or 24-hr incubation with cultured endothelial cells, macrophage uptake of the LDL was only marginally enhanced. The results suggest that diets sufficiently enriched in oleic acid, in addition to their LDL-lowering effect, may slow the progression of atherosclerosis by generating LDL that is highly resistant to oxidative modification. PMID:2339129

  6. Molecular Imaging of Native Low-Density Lipoprotein by Near-Infrared Fluorescent Angioscopy in Human Coronary Plaques.

    PubMed

    Uchida, Yasumi; Yoshida, Tomoe; Shimoyama, Ei; Uchida, Yasuto

    2016-03-01

    Low-density lipoprotein (LDL) is an important risk factor for coronary artery disease, but its localization within the human coronary arterial wall is poorly understood. Imaging of LDL in 30 coronary arteries excised from 15 subjects who underwent autopsy was performed using near-infrared fluorescent angioscopy system and using indocyanine green dye as a biomarker of LDL. The percentage incidence of LDL in 28 normal segments, 24 white plaques (early stage of plaque growth), and 21 yellow plaques (mature stage of plaque) classified by conventional angioscopy, was 14.2, 79.1 (p <0.01 vs normal segments and p <0.05 vs yellow plaques), and 28.5, respectively. Coronary near-infrared fluorescent angioscopy showed similar results in 7 patients in vivo. Our results suggested that LDL begins to deposit in the human coronary arterial wall in the early stage of atherosclerosis, increasingly deposits with plaque growth and decreases in the mature stage; and therefore, molecular therapy targeting LDL should be started before plaque maturation.

  7. A suggested method for the prediction of the oxidation resistance of low density lipoprotein by determination of the lag time.

    PubMed

    Naghii, M R

    2002-01-01

    A simple clinical blood test, which measures the total antioxidant status of Low Density Lipoprotein (LDL) and therefore its vulnerability to oxidative stress is suggested, and as a first stage this was tried on a small sample of eight healthy adult males. The body's natural defence and repair systems try to handle all free radicals, but these systems are not hundred percent effective. Thereby, the role of antioxidants (particularly natural antioxidants) becomes evident and vitamins such as Vitamin C, Vitamin E, and compounds like beta-carotene are under especially extensive study. Vitamin C is the most abundant water-soluble antioxidant acting in extracellular fluid, while Vitamin E is the most abundant fat-soluble antioxidant, and it protects the polyunsaturated fatty acids within the LDL from oxidation and helps to prevent the process of atherogenesis. The determination of 'lag-phase' during continuous monitoring of oxidation of LDL in vitro is a convenient and objective procedure for determining the susceptibility of LDL from different donors towards oxidation as well as of pro- and anti-oxidants. The Lag-time for LDL samples, obtained from eight healthy adult males was found to be between 40-50 minutes. The measurement of this Lag-phase could be a highly promising routine method for measuring the total antioxidant status of LDL.

  8. Capsaicin protects endothelial cells and macrophage against oxidized low-density lipoprotein-induced injury by direct antioxidant action.

    PubMed

    Chen, Kuo-Shuen; Chen, Pei-Ni; Hsieh, Yih-Shou; Lin, Chin-Yin; Lee, Yi-Hsun; Chu, Shu-Chen

    2015-02-25

    Atherosclerosis is a chronic inflammatory vascular disease. It is characterized by endothelial dysfunction, lipid accumulation, leukocyte activation, and the production of inflammatory mediators and reactive oxygen species (ROS). Capsaicin, a biologically active compound of the red pepper and chili pepper, has several anti-oxidant, anti-inflammatory, anti-cancer, and hypolipidemic biological effects. However, its protective effects on foam cell formation and endothelial injury induced by oxidized low-density lipoprotein (oxLDL) remain unclear. In this study, we evaluated the anti-oxidative activity of capsaicin, and determined the mechanism by which capsaicin rescues human umbilical vein endothelial cells (HUVECs) from oxLDL-mediated dysfunction. The anti-oxidative activity of capsaicin was defined by Apo B fragmentation and conjugated diene production of the copper-mediated oxidation of LDL. Capsaicin repressed ROS generation, as well as subsequent mitochondrial membrane potential collapse, cytochrome c expression, chromosome condensation, and caspase-3 activation induced by oxLDL in HUVECs. Capsaicin also protected foam cell formation in macrophage RAW 264.7 cells. Our results suggest that capsaicin may prevent oxLDL-induced cellular dysfunction and protect RAW 264.7 cells from LDL oxidation.

  9. Protective effect of rosuvastatin treatment by regulating oxidized low-density lipoprotein expression in a rat model of liver fibrosis.

    PubMed

    Yu, Shuiping; Zhou, Xueling; Hou, Bingzong; Tang, Bo; Li, Jian; Zhang, Baimeng

    2016-09-01

    The present study aimed to evaluate the protective effect of rosuvastatin treatment on the mechanism of oxidized low-density lipoprotein (Ox-LDL) in rats with liver fibrosis. In total, 72 male Sprague-Dawley rats were divided into 3 groups: 24 in the control group (A), 24 in the obstructive jaundice models group (B) and 24 in the rosuvastatin group (C). Each group was further divided into four subgroups for assessment at different time-points. The obstructive jaundice models were established and rosuvastatin was administered by gavage. Liver fibrosis indicators, Ox-LDL, malonaldehyde (MDA) and superoxide dismutase (SOD), were measured and liver pathological changes were observed at weeks 1, 2, 3 and 4 after model induction. In groups B and C, the rat models were successfully established, and there were significant changes in the expression of Ox-LDL and the three liver fibrosis indicators when compared to group A (P<0.01). However, the expression of Ox-LDL and the three liver fibrosis indicators in group C were decreased compared with group B (P<0.05), while SOD increased (P<0.05) and MDA decreased (P<0.05). The three liver fibrosis indicators were different in comparison to group B (P<0.05). Thus, there appeared to be an association between the expression of Ox-LDL and liver fibrosis. Treatment with rosuvastatin could regulate the expression of Ox-LDL and improve liver fibrosis in rat models with obstructive jaundice.

  10. In situ delipidation of low-density lipoproteins in capillary electrochromatography yields apolipoprotein B-100-coated surfaces for interaction studies.

    PubMed

    D'Ulivo, Lucia; Chen, Jie; Meinander, Kristoffer; Oörni, Katariina; Kovanen, Petri T; Riekkola, Marja-Liisa

    2008-12-01

    An electrochromatographic method was developed for the in situ delipidation of intact low-density lipoprotein (LDL) particles immobilized on the inner wall of a 50-microm inner diameter silica capillary. In this method, the immobilized LDL particles were delipidated with nonionic surfactant Nonidet P-40 at pH 7.4 and 25 degrees C, resulting in an apolipoprotein B-100 (apoB-100)-coated capillary surface. The mobility of the electroosmotic flow marker dimethyl sulfoxide gave information about the surface charge, and the retention factors of beta-estradiol, testosterone, and progesterone were informative of the surface hydrophobicity. The calculated distribution coefficients of the steroids produced specific information about the affinity interactions of the steroids, with capillary surfaces coated either with intact LDL particles or with apoB-100. Delipidation with Nonidet P-40 resulted in a strong decrease in the hydrophobicity of the LDL coating. Atomic force microscopy images confirmed the loss of lipids from the LDL particles and the presence of apoB-100 protein coating. The in situ delipidation of LDL particles in capillaries represents a novel approach for the isolation of immobilized apoB-100 and for the determination of its pI value. The technique requires extremely low quantities of LDL particles, and it is simple and fast.

  11. Effects of low-density lipoproteins extracted from different avian yolks on boar spermatozoa quality following freezing-thawing.

    PubMed

    Wang, Peng; Wang, Yan-Feng; Wang, Chun-Wei; Bu, Shu-Hai; Hu, Jian-Hong; Li, Qing-Wang; Pang, Wei-Jun; Yang, Gong-She

    2014-05-01

    Low-density lipoproteins (LDL) is known to protect boar sperm during freezing-thawing, but little information is known about the effects of LDL extracted from different avian egg yolks on post-thaw boar semen quality. The purpose of this study was to compare and analyze the effects of LDL at various concentrations and different species on boar sperm quality after freezing-thawing. LDL extracted from the yolk of hen egg, duck egg, quail egg, pigeon egg or ostrich egg was added to the extender at the concentrations of 0.06, 0.07, 0.08, 0.09 and 0.1 g/ml, respectively, and their effects on frozen-thawed boar sperm quality were assessed. According to all measured parameters, the results showed that sperm motility, acrosome integrity and plasma membrane integrity were 43.20%, 52.57% and 48.13%, respectively, after being frozen-thawed with 0.09 g/ml LDL extracted from pigeon egg yolk. All these quality parameters were higher than that of other groups (P < 0.05). In conclusion, our results confirmed that LDL extracted from pigeon egg yolk had the best cryoprotective effects on frozen-thawed boar sperm among all of the groups supplemented with LDL from five kinds of avian egg in extender. The optimum concentration of LDL extracted from pigeon egg in boar semen freezing extender was 0.09 g/ml.

  12. Single Low-Density Lipoprotein Apheresis Does Not Improve Vascular Endothelial Function in Chronically Treated Hypercholesterolemic Patients

    PubMed Central

    Ballard, Kevin D.; Mah, Eunice; Guo, Yi; Bruno, Richard S.; Taylor, Beth A.; Beam, Jo Ellen; Polk, Donna M.; Thompson, Paul D.

    2016-01-01

    Objective. To investigate vascular endothelial function (VEF) responses to a single low-density lipoprotein (LDL) apheresis session in hypercholesterolemic patients undergoing chronic treatment. Methods. We measured brachial artery flow-mediated dilation (FMD), plasma lipids, vitamin E (α- and γ-tocopherol), markers of oxidative/nitrative stress (malondialdehyde (MDA) and nitro-γ-tocopherol (NGT)), and regulators of NO metabolism (arginine (ARG) and asymmetric dimethylarginine (ADMA)) prior to (Pre) and immediately following (Post) LDL apheresis and at 1, 3, 7, and 14 d Post in 5 hypercholesterolemic patients (52 ± 11 y). Results. Relative to Pre, total cholesterol (7.8 ± 1.5 mmol/L) and LDL-cholesterol (6.2 ± 1.2 mmol/L) were 61% and 70% lower (P < 0.01), respectively, at Post and returned to Pre levels at 14 d. Brachial FMD responses (6.9 ± 3.6%) and plasma MDA, ARG, and ADMA concentrations were unaffected by LDL apheresis. Plasma α-tocopherol, γ-tocopherol, and NGT concentrations were 52–69% lower at Post (P < 0.01), and α-tocopherol remained 36% lower at 1 d whereas NGT remained 41% lower at d 3. Conclusions. Acute cholesterol reduction by LDL apheresis does not alter VEF, oxidative stress, or NO homeostasis in patients treated chronically for hypercholesterolemia. PMID:26998360

  13. Influence of lipid profile and fatty acid composition on the oxidation behavior of rat and guinea pig low density lipoprotein.

    PubMed

    Vázquez, M; Merlos, M; Adzet, T; Laguna, J C

    1998-02-01

    Low density lipoprotein (LDL) oxidation is one of the first steps proposed for the development of atherosclerosis. Since lipid profile and fatty acid composition may affect this process, we studied the influence of these factors on the oxidation behavior of rat and guinea pig LDL. Marked compositional differences were observed. Thus, the main lipid carried by rat LDL was triglyceride (TG) (35.8 +/- 5.8%, w/w) whereas total cholesterol (TC) represented 23.8 +/- 3.0%. In contrast, guinea pig LDL contained 13.2 +/- 2% of TG and 44.8 +/- 4.5% of TC. Rat LDL contained higher 20:4(n-6) molar percentages than guinea pig LDL. Thiobarbituric acid reactive substances (TBARS) production (255 +/- 26 and 137 +/- 13 nmol malondialdehyde/mg prot. for rat and guinea pig LDL, respectively) and the maximum rate of conjugated dienes (CD) formation (485 +/- 93 and 77 +/- 11 nmol CD/min/mg protein for rat and guinea pig LDL, respectively) showed that rat LDL are less resistant to oxidation in vitro than guinea pig LDL. The higher oxidation rate of rat LDL seems to be related to its lipid profile, mainly to the high proportion of TG, and to the high content of 20:4(n-6), which is one of the fatty acids most prone to oxidation.

  14. Controllable inhibition of cellular uptake of oxidized low-density lipoprotein: structure-function relationships for nanoscale amphiphilic polymers.

    PubMed

    Iverson, Nicole M; Sparks, Sarah M; Demirdirek, Bahar; Uhrich, Kathryn E; Moghe, Prabhas V

    2010-08-01

    A family of anionic nanoscale polymers based on amphiphilic macromolecules (AMs) was developed for controlled inhibition of highly oxidized low-density lipoprotein (hoxLDL) uptake by inflammatory macrophage cells, a process that triggers the escalation of a chronic arterial disease called atherosclerosis. The basic AM structure is composed of a hydrophobic portion formed from a mucic acid sugar backbone modified at the four hydroxyls with lauroyl groups conjugated to hydrophilic poly(ethylene glycol) (PEG). The AM structure-activity relationships were probed by synthesizing AMs with six key variables: length of the PEG chain, carboxylic acid location, type of anionic charge, number of anionic charges, rotational motion of the anionic group, and PEG architecture. All AM structures were confirmed by nuclear magnetic resonance spectroscopy and their ability to inhibit hoxLDL uptake in THP-1 human macrophage cells was compared in the absence and presence of serum. We report that AMs with one, rotationally restricted carboxylic acid within the hydrophobic portion of the polymer was sufficient to yield the most effective AM for inhibiting hoxLDL internalization by THP-1 human macrophage cells under serum-containing conditions. Further, increasing the number of charges and altering the PEG architecture in an effort to increase serum stabilization did not significantly impair the ability of AMs to inhibit hoxLDL internalization, suggesting that selected modifications to the AMs could potentially promote multifunctional characteristics of these nanoscale macromolecules.

  15. Protective effects of berberine against low-density lipoprotein (LDL) oxidation and oxidized LDL-induced cytotoxicity on endothelial cells.

    PubMed

    Hsieh, Yih-Shou; Kuo, Wu-Hsien; Lin, Ta-Wei; Chang, Horng-Rong; Lin, Teseng-His; Chen, Pei-Ni; Chu, Shu-Chen

    2007-12-12

    The oxidative modification of low-density lipoprotein (LDL) is thought to have a central role in the pathogenesis of atherogenesis. Berberine, a natural constituent of plants of the genera Coptis and Berberis, has several anti-inflammation and anticancer biological effects. However, its protective effects on LDL oxidation and endothelial injury induced by oxLDL remain unclear. In this study, we evaluated the antioxidative activity of berberine and how berberine rescues human umbilical vein endothelial cells (HUVECs) from oxidized LDL (oxLDL)-mediated dysfunction. The antioxidative activity of berberine was defined by the relative electrophoretic mobility of oxLDL, fragmentation of ApoB, and malondialdehyde production via the Cu(2+)-mediated oxidation of LDL. Berberine also inhibited the generation of ROS and the subsequent mitochondrial membrane potential collapse, chromosome condensation, cytochrome C release, and caspase-3 activation induced by oxLDL in HUVECs. Our results suggest that berberine may protect LDL oxidation and prevent oxLDL-induced cellular dysfunction.

  16. Inhibition of human low-density lipoprotein oxidation in vitro by Maharishi Ayur-Veda herbal mixtures.

    PubMed

    Sharma, H M; Hanna, A N; Kauffman, E M; Newman, H A

    1992-12-01

    In this study, we examined the effect of the Maharishi Ayur-Veda herbal mixtures (MAHMs) Maharishi Amrit Kalash-4 and -5 (M-4 and M-5), MA-631, and Maharishi Coffee Substitute (MCS) on low-density lipoprotein (LDL) oxidation and compared the potency of these mixtures to ascorbic acid, alpha-tocopherol, and probucol. LDL was incubated in 95% air and 5% CO2, with or without 3 microM Cu(+2), in the presence or absence of MAHMs, for 6 or 24 h. In a separate experiment, LDL was incubated as above except MAHMs were added at 0, 1.5, and 3.5 h after incubation started to assess their effect on initiation and propagation of LDL oxidation. Our results demonstrate that MAHMs caused concentration-dependent inhibition of LDL oxidation as assessed by thiobarbituric acid-reactive substances and electrophoretic mobility. The MAHM showed more antioxidant potency in preventing LDL oxidation than ascorbic acid, alpha-tocopherol, or probucol. Also, MAHMs inhibited both initiation and propagation of cupric ion-catalyzed LDL oxidation. These results suggest the importance of further research on these herbal mixtures in the investigation of atherosclerosis and free radical-induced injury.

  17. Low density lipoprotein detection based on antibody immobilized self-assembled monolayer: investigations of kinetic and thermodynamic properties.

    PubMed

    Matharu, Zimple; Bandodkar, Amay Jairaj; Sumana, G; Solanki, Pratima R; Ekanayake, E M I Mala; Kaneto, Keiichi; Gupta, Vinay; Malhotra, B D

    2009-10-29

    Human plasma low density lipoprotein (LDL) immunosensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was fabricated by immobilizing antiapolipoprotein B (AAB) onto self-assembled monolayer (SAM) of 4-aminothiophenol (ATP). The AAB/ATP/Au immunosensor can detect LDL up to 0.252 microM (84 mg/dL) and 0.360 microM (120 mg/dL) with QCM and SPR, respectively. The SPR and QCM measurements were further utilized to study the reaction kinetics of the AAB-LDL interaction. The adsorption process involved was explored using Langmuir adsorption isotherm and Freundlich adsorption models. The thermodynamic parameters such as change in Gibb's free energy (DeltaG(ads)), change in enthalpy (DeltaH(ads)), and change in entropy (DeltaS(ads)) determined at 283, 298, and 308 K revealed that the AAB-LDL interaction is endothermic in nature and is governed by entropy. Kinetic, thermodynamic, and sticking probability studies disclosed that desorption of the water molecules from the active sites of AAB and LDL plays a key role in the interaction process and increase in temperature favors binding of LDL with the AAB/ATP/Au immunosensor. Thus, the studies were utilized to unravel the most important subprocess involved in the adsorption of LDL onto AAB-modified ATP/Au surface that may help in the fabrication of LDL immunosensors with better efficiency.

  18. Immobilization of sodium alginate sulfates on polysulfone ultrafiltration membranes for selective adsorption of low-density lipoprotein.

    PubMed

    Wang, Wei; Huang, Xiao-Jun; Cao, Jian-Da; Lan, Ping; Wu, Wen

    2014-01-01

    A novel method for the immobilization of sodium alginate sulfates (SAS) on polysulfone (PSu) ultrafiltration membranes to achieve selective adsorption of low-density lipoprotein (LDL) was developed, which involved the photoinduced graft polymerization of acrylamide on the membrane and the Hofmann rearrangement reaction of grafted acrylamide followed by chemical binding of SAS with glutaraldehyde. The surface modification processes were confirmed by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy characterization. Zeta potential and water contact angle measurements were performed to investigate the surface charge and wettability of the membranes. An enzyme-linked immunosorbent assay was used to measure the binding of LDL on plain and modified PSu membranes. It was found that the PSu membrane immobilized with sodium alginate sulfates (PSu-SAS) greatly enhanced the selective adsorption of LDL from protein solutions and the absorbed LDL could be easily eluted with sodium chloride solution, indicating a specific and reversible binding of LDL to SAS, mainly driven by electrostatic forces. Furthermore, the PSu-SAS membrane showed good blood compatibility as examined by platelet adhesion. The results suggest that the PSu-SAS membranes are promising for application in simultaneous hemodialysis and LDL apheresis therapy.

  19. Oxidised low density lipoprotein causes human macrophage cell death through oxidant generation and inhibition of key catabolic enzymes.

    PubMed

    Katouah, Hanadi; Chen, Alpha; Othman, Izani; Gieseg, Steven P

    2015-10-01

    Oxidised low density lipoprotein (oxLDL) is thought to be a significant contributor to the death of macrophage cells observed in advanced atherosclerotic plaques. Using human-derived U937 cells we have examined the effect of cytotoxic oxLDL on oxidative stress and cellular catabolism. Within 3h of the addition of oxLDL, there was a rapid, concentration dependent rise in cellular reactive oxygen species followed by the loss of cellular GSH, and the enzyme activity of both glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and aconitase. The loss of these catabolic enzymes was accompanied by the loss of cellular ATP and lower lactate generation. Addition of the macrophage antioxidant 7,8-dihydroneopterin inhibited the ROS generation, glutathione loss and catabolic inactivation. NOX was shown to be activated by oxLDL addition while apocynin inhibited the loss of GSH and cell viability. The data suggests that oxLDL triggers an excess of ROS production through NOX activation, and catabolic failure through thiol oxidation resulting in cell death.

  20. Nanoscale amphiphilic macromolecules with variable lipophilicity and stereochemistry modulate inhibition of oxidized low-density lipoprotein uptake.

    PubMed

    Poree, Dawanne E; Zablocki, Kyle; Faig, Allison; Moghe, Prabhas V; Uhrich, Kathryn E

    2013-08-12

    Amphiphilic macromolecules (AMs) based on carbohydrate domains functionalized with poly(ethylene glycol) can inhibit the uptake of oxidized low density lipoprotein (oxLDL) and counteract foam cell formation, a key characteristic of early atherogenesis. To investigate the influence of lipophilicity and stereochemistry on the AMs' physicochemical and biological properties, mucic acid-based AMs bearing four aliphatic chains (2a) and tartaric acid-based AMs bearing two (2b and 2l) and four aliphatic chains (2g and 2k) were synthesized and evaluated. Solution aggregation studies suggested that both the number of hydrophobic arms and the length of the hydrophobic domain impact AM micelle sizes, whereas stereochemistry impacts micelle stability. 2l, the meso analogue of 2b, elicited the highest reported oxLDL uptake inhibition values (89%), highlighting the crucial effect of stereochemistry on biological properties. This study suggests that stereochemistry plays a critical role in modulating oxLDL uptake and must be considered when designing biomaterials for potential cardiovascular therapies.

  1. Activation of sonic hedgehog signaling attenuates oxidized low-density lipoprotein-stimulated brain microvascular endothelial cells dysfunction in vitro.

    PubMed

    Jiang, Xiu-Long; Chen, Ting; Zhang, Xu

    2015-01-01

    The study was performed to investigate the role of sonic hedgehog (SHH) in the oxidized low-density lipoprotein (oxLDL)-induced blood-brain barrier (BBB) disruption. The primary mouse brain microvascular endothelial cells (MBMECs) were exposed to oxLDL. The results indicated that treatment of MBMECs with oxLDL decreased the cell viability, and oxidative stress was involved in oxLDL-induce MBMECs dysfunction with increasing intracellular ROS and MDA formation as well as decreasing NO release and eNOS mRNA expression. In addition, SHH signaling components, such as SHH, Smo and Gli1, mRNA and protein levels were significantly decreased after incubation with increasing concentrations of oxLDL. Treatment with oxLDL alone or SHH loss-of-function significantly increased the permeability of MBMECs, and overexpression of SHH attenuated oxLDL-induced elevation of permeability in MBMECs. Furthermore, SHH gain-of-function could reverse oxLDL-induced apoptosis through inhibition caspase3 and caspase8 levels in MBMECs. Taken together, these results demonstrated that the suppression of SHH in MBMECs might contribute to the oxLDL-induced disruption of endothelial barrier. However, the overexpression of SHH could reverse oxLDL-induced endothelial cells dysfunction in vitro.

  2. Effects of coffee consumption on oxidative susceptibility of low-density lipoproteins and serum lipid levels in humans.

    PubMed

    Yukawa, G S; Mune, M; Otani, H; Tone, Y; Liang, X-M; Iwahashi, H; Sakamoto, W

    2004-01-01

    Since little is known about how coffee intake affects low-density lipoprotein (LDL) oxidative susceptibility and serum lipid levels, we conducted an in vivo study in 11 healthy male students of Wakayama Medical University aged between 20 and 31 years fed an average Japanese diet. On days 1-7 of the study, the subjects drank mineral water. On day 7, the subjects began drinking coffee, 24 g total per day, for one week. This was followed by a one week "washout period" during which mineral water was consumed. Fasting peripheral venous blood samples were taken at the end of each one-week period. LDL oxidation lag time was approximately 8% greater (p < 0.01) after the coffee drinking period than the other periods. Serum levels of total cholesterol and LDL-cholesterol (LDL-C) and malondialdehyde (MDA) as thiobarbituric acid reactive substances (TBARS) were significantly decreased after the coffee drinking period. Finally, regular coffee ingestion may favorably affect cardiovascular risk status by modestly reducing LDL oxidation susceptibility and decreasing LDL-cholesterol and MDA levels.

  3. Low-density lipoprotein cholesterol level in patients with acute myocardial infarction having percutaneous coronary intervention (the cholesterol paradox).

    PubMed

    Cho, Kyung Hoon; Jeong, Myung Ho; Ahn, Youngkeun; Kim, Young Jo; Chae, Shung Chull; Hong, Taek Jong; Seong, In Whan; Chae, Jei Keon; Kim, Chong Jin; Cho, Myeong Chan; Seung, Ki Bae; Park, Seung Jung

    2010-10-15

    The relation between low-density lipoprotein (LDL) cholesterol levels and clinical outcomes after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) has not been described. A total of 9,571 eligible patients (mean age 62.6 ± 12.5 years, 6,967 men) who underwent PCI with a final diagnosis of AMI from the Korea Acute Myocardial Infarction Registry (KAMIR) were divided into 5 groups according to LDL cholesterol level: < 70, 70 to 99, 100 to 129, 130 to 159, and ≥ 160 mg/dl. Clinical outcomes in hospital and 1 and 12 months after PCI in patients with AMI were examined. Age and co-morbidities decreased as LDL cholesterol increased. Patients with higher LDL cholesterol levels had favorable hemodynamic status and laboratory findings. Lifesaving medications, including lipid-lowering drugs, were underused in patients with lower LDL cholesterol levels. Clinical outcomes in hospital and 1 and 12 months after PCI showed better results as LDL cholesterol increased, except for patients with LDL cholesterol levels ≥ 160 mg/dl. In a Cox proportional-hazards model, LDL cholesterol level was not an independent predictor of mortality at 12 months, after adjusting for clinical characteristics including demographics and biologic data. In conclusion, the cholesterol paradox in patients with AMI is related to confounding by baseline characteristics associated with survival. More intensive treatment including lipid-lowering therapy for AMI in patients with lower LDL cholesterol level may result in better clinical outcomes.

  4. Localized Delivery of Low-Density Lipoprotein Docosahexaenoic Acid Nanoparticles to the Rat Brain using Focused Ultrasound

    PubMed Central

    Mulik, Rohit S.; Bing, Chenchen; Ladouceur-Wodzak, Michelle; Munaweera, Imalka; Chopra, Rajiv; Corbin, Ian R.

    2016-01-01

    Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1′-Dioctadecyl-3,3,3′,3′-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2× more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain. PMID:26790145

  5. Association of Plasma Adiponectin and Oxidized Low-Density Lipoprotein with Carotid Intima-Media Thickness in Diabetic Nephropathy

    PubMed Central

    Georgoulidou, Anastasia; Roumeliotis, Athanasios; Roumeliotis, Stefanos; Giannakopoulou, Efstathia; Papanas, Nikolaos; Passadakis, Ploumis; Manolopoulos, Vangelis G.; Vargemezis, Vassilis

    2015-01-01

    Aims. We sought to determine the association between levels of adiponectin and oxidized low-density lipoprotein (ox-LDL) in patients with diabetic nephropathy as well as their effect on carotid intima-media thickness (cIMT). Methods. Adiponectin and ox-LDL were determined in 25 diabetic patients without nephropathy and 94 patients at different stages of diabetic nephropathy including subjects on hemodialysis. cIMT was measured using real-time B-mode ultrasonography. Results. Plasma adiponectin levels increased significantly with severity of diabetic nephropathy (P = 0.002), on the contrary to ox-LDL which decreased with disease severity (P < 0.001). cIMT was significantly higher at late stages of diabetic nephropathy compared with early stages (P = 0.022). Adiponectin was a significant negative predictor of ox-LDL levels (β = −5.45, P = 0.023), independently of confounding factors. There was no significant correlation between cIMT and adiponectin or ox-LDL either in the total sample population or according to disease staging. Cluster analysis showed that patients with the highest cIMT values, highest levels of adiponectin, and lowest levels of ox-LDL were included in one cluster and all assigned to stage 5 of diabetic nephropathy. Conclusions. There was no significant association between adiponectin or ox-LDL and cIMT and, therefore, other factors affecting this surrogate marker of cardiovascular disease in diabetic nephropathy should be sought. PMID:26064982

  6. Protective effects of Peganum harmala L. extract, harmine and harmaline against human low-density lipoprotein oxidation.

    PubMed

    Berrougui, Hicham; Isabelle, Maxim; Cloutier, Martin; Hmamouchi, Mohammed; Khalil, Abdelouahed

    2006-07-01

    Oxidative modification of low-density lipoprotein (LDL) particles has been implicated in the process of atherogenesis. Antioxidants that prevent LDL from oxidation may reduce atherosclerosis. We have investigated the protective effect of Peganum harmala-extract (P-extract) and the two major alkaloids (harmine and harmaline) from the seeds of P. harmala against CuSO4-induced LDL oxidation. Through determination of the formation of malondialdehyde (MDA) and conjugated diene as well as the lag phase, the extract (P-extract) and compounds were found to possess an inhibitory effect. Moreover, harmaline and harmine reduced the rate of vitamin E disappearance and exhibited a significant free radical scavenging capacity (DPPH*). However, harmaline had a markedly higher antioxidant capacity than harmine in scavenging or preventive capacity against free radicals as well as inhibiting the aggregation of the LDL protein moiety (apolipoprotein B) induced by oxidation. The results suggested that P. harmala compounds could be a major source of compounds that inhibit LDL oxidative modification induced by copper.

  7. Differential regulation of acid sphingomyelinase in macrophages stimulated with oxidized low-density lipoprotein (LDL) and oxidized LDL immune complexes: role in phagocytosis and cytokine release.

    PubMed

    Truman, Jean-Philip; Al Gadban, Mohammed M; Smith, Kent J; Jenkins, Russell W; Mayroo, Nalini; Virella, Gabriel; Lopes-Virella, Maria F; Bielawska, Alicja; Hannun, Yusuf A; Hammad, Samar M

    2012-05-01

    Oxidized low-density lipoprotein (oxLDL) and oxLDL-containing immune complexes (oxLDL-IC) contribute to the formation of lipid-laden macrophages (foam cells). Fcγ receptors mediate uptake of oxLDL-IC, whereas scavenger receptors internalize oxLDL. We have previously reported that oxLDL-IC, but not free oxLDL, activate macrophages and prolong their survival. Sphingomyelin is a major constituent of cell membranes and lipoprotein particles and acid sphingomyelinase (ASMase) hydrolyses sphingomyelin to generate the bioactive lipid ceramide. ASMase exists in two forms: lysosomal (L-ASMase) and secretory (S-ASMase). In this study we examined whether oxLDL and oxLDL-IC regulate ASMase differently, and whether ASMase mediates monocyte/macrophage activation and cytokine release. The oxLDL-IC, but not oxLDL, induced early and consistent release of catalytically active S-ASMase. The oxLDL-IC also consistently stimulated L-ASMase activity, whereas oxLDL induced a rapid transient increase in L-ASMase activity before it steadily declined below baseline. Prolonged exposure to oxLDL increased L-ASMase activity; however, activity remained significantly lower than that induced by oxLDL-IC. Further studies were aimed at defining the function of the activated ASMase. In response to oxLDL-IC, heat-shock protein 70B' (HSP70B') was up-regulated and localized with redistributed ASMase in the endosomal compartment outside the lysosome. Treatment with oxLDL-IC induced the formation and release of HSP70-containing and IL-1β-containing exosomes via an ASMase-dependent mechanism. Taken together, the results suggest that oxLDL and oxLDL-IC differentially regulate ASMase activity, and the pro-inflammatory responses to oxLDL-IC are mediated by prolonged activation of ASMase. These findings may contribute to increased understanding of mechanisms mediating macrophage involvement in atherosclerosis.

  8. High payload delivery of optical imaging and photodynamic therapy agents to tumors using phthalocyanine-reconstituted low-density lipoprotein nanoparticles.

    PubMed

    Li, Hui; Marotta, Diane E; Kim, Soungkyoo; Busch, Theresa M; Wileyto, E Paul; Zheng, Gang

    2005-01-01

    To improve the labeling efficiency of a low-density lipoprotein (LDL)-based photosensitizer (PS) for achieving high probe to protein payload, a tetra-t-butyl silicon phthalocyanine bearing two oleate moieties at its axial positions, SiPcBOA, is designed and synthesized. Using this novel strategy, SiPcBOA reconstituted LDL (r-SiPcBOA-LDL) with a very high payload (SiPcBOA to LDL molar ratio >3000 to 35001:1) is obtained. Using electron microscopy, we find reconstituted LDL (rLDL) with such a high payload essentially retains the mean particle size of native LDL. Since acetylated LDL binds to scavenger receptors of endothelial and microglial cells instead of LDLR, SiPcBOA reconstituted acetylated LDL (r-SiPcBOA-AcLDL) is also prepared to serve as a negative control to validate the LDL receptor (LDLR) targeting specificity. Confocal microscopy studies demonstrate that the internalization of r-SiPcBOA-LDL by human hepatoblastoma G2 (HepG2) tumor cells is mediated by LDLR pathway. The in vitro photodynamic therapy (PDT) response of HepG2 cells to r-SiPcBOA-LDL is compared to SiPcBOA (free drug control) using a clonogenic assay. The slopes of the linear regression fit to the logarithmic data for these two plots are significantly different from each other (p=0.0007), indicating greatly enhanced efficacy of LDLR-targeted PDT.

  9. The role of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) in comparison with whole egg yolk for sperm cryopreservation in rhesus monkeys.

    PubMed

    Dong, Qiao-Xiang; Rodenburg, Sarah E; Hill, Dana; Vandevoort, Catherine A

    2011-05-01

    Low-density lipoprotein (LDL) extracted from hen egg yolk has recently been considered to be superior to whole egg yolk in sperm cryopreservation of various animal species. Meanwhile, there was a notion that high-density lipoprotein (HDL) in egg yolk may have a negative effect on post-thaw survival. The role of LDL and HDL in sperm cryopreservation of rhesus monkeys has not been explored. The present study evaluates their effect in comparison with egg yolk with or without the addition of permeable cryoprotectant (glycerol) on sperm cryopreservation of rhesus macaques. In addition, various additives intended to change the lipid composition of LDL-sperm membrane complex have also been tested for their effectiveness in preserving post-thaw viability. Our findings indicated that LDL is the main component in egg yolk that is responsible for its protective role for sperm cryopreservation in rhesus monkeys. Regardless of the presence or absence of glycerol, the protective role of LDL is similar to that of egg yolk and we did not observe any superiority in post-thaw survival with LDL when compared to egg yolk. Modifying the lipid composition of LDL-sperm membrane complex with the addition of cholesterol, cholesterol loaded cyclodextrin and phosphatidylcholine also did not yield any improvements in post-thaw survival; while addition of methyl-β-cyclodextrin reduced post-thaw motility. HDL plays a neutral role in sperm cryopreservation of rhesus monkeys. The present study suggests that egg yolk may still hold advantages when compared with LDL as effective components in extenders for sperm cryopreservation in rhesus monkeys.

  10. Identification of the Best Anthropometric Predictors of Serum High- and Low-Density Lipoproteins Using Machine Learning.

    PubMed

    Lee, Bum Ju; Kim, Jong Yeol

    2015-09-01

    Serum high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol levels are associated with risk factors for various diseases and are related to anthropometric measures. However, controversy remains regarding the best anthropometric indicators of the HDL and LDL cholesterol levels. The objectives of this study were to identify the best predictors of HDL and LDL cholesterol using statistical analyses and two machine learning algorithms and to compare the predictive power of combined anthropometric measures in Korean adults. A total of 13,014 subjects participated in this study. The anthropometric measures were assessed with binary logistic regression (LR) to evaluate statistically significant differences between the subjects with normal and high LDL cholesterol levels and between the subjects with normal and low HDL cholesterol levels. LR and the naive Bayes algorithm (NB), which provides more reasonable and reliable results, were used in the analyses of the predictive power of individual and combined measures. The best predictor of HDL was the rib to hip ratio (p =< 0.0001; odds ratio (OR) = 1.895; area under curve (AUC) = 0.681) in women and the waist to hip ratio (WHR) (p =< 0.0001; OR = 1.624; AUC = 0.633) in men. In women, the strongest indicator of LDL was age (p =< 0.0001; OR = 1.662; AUC by NB = 0.653 ; AUC by LR = 0.636). Among the anthropometric measures, the body mass index (BMI), WHR, forehead to waist ratio, forehead to rib ratio, and forehead to chest ratio were the strongest predictors of LDL; these measures had similar predictive powers. The strongest predictor in men was BMI (p =< 0.0001; OR = 1.369; AUC by NB = 0.594; AUC by LR = 0.595 ). The predictive power of almost all individual anthropometric measures was higher for HDL than for LDL, and the predictive power for both HDL and LDL in women was higher than for men. A combination of anthropometric measures slightly improved the predictive power for both HDL and LDL cholesterol

  11. Effect of the antiestrogen ethamoxytriphetol (MER-25) on placental low density lipoprotein uptake and degradation in baboons

    SciTech Connect

    Henson, M.C.; Babischkin, J.S.; Pepe, G.J.; Albrecht, E.D.

    1988-05-01

    The present study determined if the decline in placental progesterone (P4) production that results from administration of the antiestrogen ethamoxytriphetol (MER-25) to pregnant baboons results from a change in placental low density lipoprotein (LDL) uptake and/or degradation. Pregnant baboons (Papio anubis) were untreated (n = 10) or received MER-25 (25 mg/kg BW, orally; n = 10) daily on days 140-170 of gestation (term, 184 days). Placentas were removed by cesarean section on day 170 of gestation, and villous tissue was dispersed with 0.1% collagenase at 37 C for 40 min. Placental cells (10(6)) were incubated in medium 199 (pH 7.2) for 12 h at 37 C with increasing amounts (5-100 micrograms) of (125I)LDL, with or without a 100-fold excess of unlabeled baboon LDL. Mean (+/- SE) peripheral serum P4 concentrations on days 140-170 of gestation were 51% lower (P less than 0.01) in MER-25-treated (5.7 +/- 0.3 ng/ml) than in untreated (11.6 +/- 0.5 ng/ml) baboons. The uptake of LDL was 56% lower (P less than 0.01) in placental cells from antiestrogen-treated (6.3 +/- 1.6 ng/micrograms cell protein) than in those from untreated (14.4 +/- 1.9 ng/micrograms cell protein) baboons. The dissociation constants for placental LDL uptake, as assessed by Scatchard analysis, however, were similar in untreated (0.80 microgram/ml) and MER-25-treated (0.76 microgram/ml) animals. The amount of (125I)LDL concomitantly degraded by cells from baboons that received MER-25 was 54% of that degraded by cells from untreated controls. The relative decline in LDL degradation by cells of antiestrogen-treated baboons was proportionate to the decline in overall LDL uptake. The results indicate, therefore, that antiestrogen treatment decreased the amount of placental LDL uptake, but did not change the affinity for the lipoprotein.

  12. Reciprocal induction of IL-10 and IL-12 from macrophages by low-density lipoprotein and its oxidized forms.

    PubMed

    Varadhachary, A S; Monestier, M; Salgame, P

    2001-10-10

    Atherosclerosis is a chronic inflammatory disease. Several lines of evidence indicate that altered or modified lipoproteins contribute to plaque formation and lesion progression in atherogenesis. In this study we examined if lipoproteins and their oxidized forms can exert an immunomodulatory effect, thereby potentially influencing atherogenesis. We demonstrate that LDL, upon binding to its receptor, induces interleukin (IL)-10 production from macrophages and biases naive T cells to become Th2-like. In contrast, oxLDL induces IL-12 from macrophages and accordingly favors differentiation of naive T cells along a Th1 pathway. IL-10 is a potent anti-inflammatory cytokine with a number of potential effects that could dampen inflammation at sites of vascular wall damage, including downregulation of MHC and adhesion molecules and biasing of adaptive immune responses toward the anti-inflammatory, humoral immune-promoting Th2 T cell subset. These studies assign a new immunomodulatory role to LDLs and offer a potential means to upregulate IL-10 production and prevent arterial inflammation.

  13. Effect of platelet activating factor-acetylhydrolase on the formation and action of minimally oxidized low density lipoprotein.

    PubMed Central

    Watson, A D; Navab, M; Hama, S Y; Sevanian, A; Prescott, S M; Stafforini, D M; McIntyre, T M; Du, B N; Fogelman, A M; Berliner, J A

    1995-01-01

    Mildly oxidized low density lipoprotein (MM-LDL) produced by oxidative enzymes or cocultures of human artery wall cells induces endothelial cells to produce monocyte chemotactic protein-1 and to bind monocytes. HDL prevents the formation of MM-LDL by cocultures of artery wall cells. Using albumin treatment and HPLC we have isolated and partially characterized bioactive oxidized phospholipids in MM-LDL. Platelet activating factor-acetylhydrolase (PAF-AH), a serine esterase, hydrolyzes short chain acyl groups esterified to the sn-2 position of phospholipids such as PAF and particular oxidatively fragmented phospholipids. Treatment of MM-LDL with PAF-AH (2-4 x 10(-2) U/ml) eliminated the ability of MM-LDL to induce endothelial cells to bind monocytes. When HDL protected against the formation of MM-LDL by cocultures, lysophosphatidylcholine was detected in HDL; whereas when HDL was pretreated with diisopropyl fluorophosphate, HDL was no longer protective and lysophosphatidylcholine was undetectable. HPLC analysis also revealed that the active oxidized phospholipid species in MM-LDL had been destroyed after PAF-AH treatment. In addition, treatment of MM-LDL with albumin removed polar phospholipids that, when reisolated, induced monocyte binding to endothelial cells. These polar phospholipids, when treated with PAF-AH, lost biological activity and were no longer detected by HPLC. These results suggest that PAF-AH in HDL protects against the production and activity of MM-LDL by facilitating hydrolysis of active oxidized phospholipids to lysolipids, thereby destroying the biologically active lipids in MM-LDL. PMID:7860760

  14. Trichosanatine alleviates oxidized low-density lipoprotein induced endothelial cells injury via inhibiting the LOX-1/p38 MAPK pathway.

    PubMed

    Zhang, Lei; Jia, Yu-Hua; Zhao, Xiao-Shan; Zhou, Feng-Hua; Pan, Yun-Yun; Wan, Qiang; Cui, Xiao-Bing; Sun, Xue-Gang; Chen, Yu-Yao; Zhang, Yu; Cheng, Sai-Bo

    2016-01-01

    The LOX-1/p38 mitogen-activated protein kinase (MAPK) pathway has been proved to participate in the endothelial dysfunction in atherosclerosis. Trichosanatineis is an active compound isolated from the peel of Trichosanthes kirilowii. This study aims to determine whether trichosanatine prevents the oxidized low-density lipoprotein (ox-LDL)-induced insult through inhibition of the LOX-1/p38 MAPK pathway in HUVECs. HUVECs were treated with 150 mg/ml ox-LDL for 24 h to establish an ox-LDL-induced endothelial injury model. Cell viability, mitochondrial membrane potential (MMP), apoptosis, reactive oxygen species (ROS) level, LOX-1 and p38 MAPK expression level were measured. The results indicated that HUVECs were pretreated with either 100 mM trichosanatine or LOX-1 shRNA prior to exposure to ox-LDL for 24 h. Exposure of HUVECs to 150 mg/ml ox-LDL for 24 h significantly up-regulated the expression levels of LOX-1. The increased expression levels of LOX-1 were markedly attenuated by pretreatment with 100 mM trichosanatine. In addition, the ox-LDL-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with LOX-1 shRNA. Pretreatment of HUVECs with either trichosanatine or LOX-1 shRNA before exposure to ox-LDL significantly inhibited the ox-LDL-induced injuries, as evidenced by an increase in cell viability, a decrease in apoptotic cells, a ROS generation and a loss of MMP. In conclusion, we have demonstrated for the first time that the LOX-1/p38 MAPK pathway contributes to the ox-LDL-induced injury in HUVECs. Meanwhile, the trichosanatine protects the HUVECs against ox-LDL-induced injury at least in part by inhibiting the activated of LOX-1/p38 MAPK pathway.

  15. Trichosanatine alleviates oxidized low-density lipoprotein induced endothelial cells injury via inhibiting the LOX-1/p38 MAPK pathway

    PubMed Central

    Zhang, Lei; Jia, Yu-Hua; Zhao, Xiao-Shan; Zhou, Feng-Hua; Pan, Yun-Yun; Wan, Qiang; Cui, Xiao-Bing; Sun, Xue-Gang; Chen, Yu-Yao; Zhang, Yu; Cheng, Sai-Bo

    2016-01-01

    The LOX-1/p38 mitogen-activated protein kinase (MAPK) pathway has been proved to participate in the endothelial dysfunction in atherosclerosis. Trichosanatineis is an active compound isolated from the peel of Trichosanthes kirilowii. This study aims to determine whether trichosanatine prevents the oxidized low-density lipoprotein (ox-LDL)-induced insult through inhibition of the LOX-1/p38 MAPK pathway in HUVECs. HUVECs were treated with 150 mg/ml ox-LDL for 24 h to establish an ox-LDL-induced endothelial injury model. Cell viability, mitochondrial membrane potential (MMP), apoptosis, reactive oxygen species (ROS) level, LOX-1 and p38 MAPK expression level were measured. The results indicated that HUVECs were pretreated with either 100 mM trichosanatine or LOX-1 shRNA prior to exposure to ox-LDL for 24 h. Exposure of HUVECs to 150 mg/ml ox-LDL for 24 h significantly up-regulated the expression levels of LOX-1. The increased expression levels of LOX-1 were markedly attenuated by pretreatment with 100 mM trichosanatine. In addition, the ox-LDL-induced increase in phosphorylated (p) p38 MAPK expression was ameliorated by pretreatment with LOX-1 shRNA. Pretreatment of HUVECs with either trichosanatine or LOX-1 shRNA before exposure to ox-LDL significantly inhibited the ox-LDL-induced injuries, as evidenced by an increase in cell viability, a decrease in apoptotic cells, a ROS generation and a loss of MMP. In conclusion, we have demonstrated for the first time that the LOX-1/p38 MAPK pathway contributes to the ox-LDL-induced injury in HUVECs. Meanwhile, the trichosanatine protects the HUVECs against ox-LDL-induced injury at least in part by inhibiting the activated of LOX-1/p38 MAPK pathway. PMID:28078016

  16. Rapid Increase in Serum Low-Density Lipoprotein Cholesterol Concentration during Hepatitis C Interferon-Free Treatment

    PubMed Central

    Abiru, Seigo; Komori, Atsumasa; Nagaoka, Shinya; Saeki, Akira; Uchida, Shinjiro; Bekki, Shigemune; Kugiyama, Yuki; Nagata, Kazuyoshi; Nakamura, Minoru; Migita, Kiyoshi; Nakao, Kazuhiko

    2016-01-01

    Background & Aim We performed lipid analyses at the early period of therapy in patients with chronic hepatitis C who underwent interferon (IFN)-free direct-acting antiviral (DAA) treatment, and we attempted to identify the factors that contributed to a rapid increase in the patients’ serum low-density lipoprotein cholesterol (LDL-C) concentration. Methods We retrospectively analyzed the cases of 100 consecutive patients with HCV infection treated at the National Hospital Organization Nagasaki Medical Center: 24 patients underwent daclatasvir (DCV) and asunaprevir (ASV) combination therapy (DCV/ASV) for 24 weeks, and the other 76 patients underwent ledipasvir and sofosbuvir combination therapy (LDV/SOF) for 12 weeks. ΔLDL-C was defined as the changed in LDL-C level at 28 days from the start of therapy. To determine whether ΔLDL-C was associated with several kinds of factors including viral kinetics, we performed a stepwise multiple linear regression analysis. Results The LDL-C levels in patients treated with LDV/SOF were markedly and significantly elevated (87.45 to 122.5 mg/dl; p<10−10) compared to those in the DCV/ASV-treated patients (80.15 to 87.8 mg/dl; p = 0.0056). The median levels of ΔLDL-C in the LDV/SOF and DCV/ASV groups were 33.2 and 13.1, respectively. LDV/SOF combination therapy as an IFN-free regimen (p<0.001) and ΔHCV core antigen (0–1 day drop) (p<0.044) were identified as independent factors that were closely related to the ΔLDL-C. Conclusions A rapid increase in the serum LDL-C concentration during the IFN-free treatment of hepatitis C was associated with the type of HCV therapy and a decline of HCV core protein. PMID:27680885

  17. Resistance of mitochondrial DNA-depleted cells against oxidized low-density lipoprotein-induced macrophage pyroptosis.

    PubMed

    Yan, Hai; Li, Yunyun; Peng, Xue; Huang, Dake; Gui, Li; Huang, Baojun

    2016-05-01

    Oxidized low-density lipoprotein (Ox-LDL)-induced macrophage pyroptosis is critical in atherosclerosis inflammation and plaque instability. It has been reported that mitochondrial (mt)DNA-depleted (rho0) cells demonstrate resistance to apoptosis. However, little is known about the susceptibility of rho0 cells to Ox-LDL-induced macrophage pyroptosis. Pyroptosis, a caspase-1-dependent programmed cell death, which compromises membrane integrity, cleaves pro-interleukin (IL)‑1β and pro‑IL‑18 into IL‑1β and IL‑18, respectively and releases damage‑associated molecular pattern molecules, is triggered by a variety of stimuli, including Ox‑LDL. In the present study, the expression levels of cleaved caspase‑1 and IL‑1β in Ox‑LDL‑treated J774A.1 rho0 cells were observed to be significantly decreased when compared with Ox‑LDL‑treated J774A.1 normal cells. Furthermore, J774A.1 rho0 cells exhibited a significant reduction in the ratios of dead cells and lactate dehydrogenase release following Ox‑LDL stimulation compared with the J774A.1 normal cells. In addition, the loss of mtDNA did not influence Ox‑LDL‑induced cholesterol accumulation in J774A.1 rho0 cells, which was observed by Oil Red O staining and CHOD‑PAP assay. Finally, J774A.1 rho0 cells exhibited reduced reactive oxygen species (ROS) production and were capable of maintaining the mitochondrial membrane potential following Ox‑LDL treatment. Thus, the results indicate that the loss of mtDNA potentially rendered murine macrophage J774A.1 resistant to Ox‑LDL‑induced pyroptosis by mitigating NACHT, LRR and PYD domains-containing protein 3 inflammasome activation through reducing ROS production. In addition, mtDNA depletion did not interrupt Ox-LDL-induced intracellular lipid accumulation and continued to maintain the mitochondrial membrane potential.

  18. Oxidized low-density lipoprotein inhibits THP-1-derived macrophage autophagy via TET2 down-regulation.

    PubMed

    Li, Guohua; Peng, Juan; Liu, Yanhui; Li, Xiaohong; Yang, Qin; Li, Yongqing; Tang, Zhihan; Wang, Zuo; Jiang, Zhisheng; Wei, Dangheng

    2015-02-01

    Oxidized low-density lipoprotein (ox-LDL) is an independent risk factor of atherosclerosis. However, the mechanism underlying its pro-atherosclerosis roles has not yet been well explored. DNA demethylation modification, via DNA methyltransferases or ten-eleven-translocation (TET) family, is a crisis epigenetic regulation for various biological and pathological processes. This study aimed to investigate the effects of ox-LDL on macrophage autophagy and its potential epigenetic mechanism. Results showed that after treatment with 0, 10, 20, 40 or 80 mg/L ox-LDL for 24 h, the autophagy markers Beclin 1 and LC3 expression were obviously decreased at protein levels (P < 0.05). The mRNA and protein expression of TET2 was evidently decreased (P < 0.05). After pre-treatment with TET2 siRNA, the mRNA and protein levels of Beclin 1 and LC3 decreased compared with the 80 mg/L treatment group (P < 0.01). The mRNA and protein levels of Beclin 1 and LC3-II were up-regulated (P < 0.05) in the 5-aza-2'-deoxycytidine (a DNA methyltransferase inhibitor) of pretreatment group. Consistent with the Western blot results, cell immunofluorescence showed that the protein concentration of LC3-II decreased in the TET2 siRNA group and increased in the 5-aza-2'-deoxycytidine group. Taken together, these results showed that DNA demethylation modifications regulate ox-LDL-treated THP-1 macrophages autophagy and TET2 might be a novel regulator.

  19. Cell membrane damage is involved in the impaired survival of bone marrow stem cells by oxidized low-density lipoprotein.

    PubMed

    Li, Xin; Xiao, Yuan; Cui, Yuqi; Tan, Tao; Narasimhulu, Chandrakala A; Hao, Hong; Liu, Lingjuan; Zhang, Jia; He, Guanglong; Verfaillie, Catherine M; Lei, Minxiang; Parthasarathy, Sampath; Ma, Jianjie; Zhu, Hua; Liu, Zhenguo

    2014-12-01

    Cell therapy with bone marrow stem cells (BMSCs) remains a viable option for tissue repair and regeneration. A major challenge for cell therapy is the limited cell survival after implantation. This study was to investigate the effect of oxidized low-density lipoprotein (ox-LDL, naturally present in human blood) on BMSC injury and the effect of MG53, a tissue repair protein, for the improvement of stem cell survival. Rat bone marrow multipotent adult progenitor cells (MAPCs) were treated with ox-LDL, which caused significant cell death as reflected by the increased LDH release to the media. Exposure of MAPCs to ox-LDL led to entry of fluorescent dye FM1-43 measured under confocal microscope, suggesting damage to the plasma membrane. Ox-LDL also generated reactive oxygen species (ROS) as measured with electron paramagnetic resonance spectroscopy. While antioxidant N-acetylcysteine completely blocked ROS production from ox-LDL, it failed to prevent ox-LDL-induced cell death. When MAPCs were treated with the recombinant human MG53 protein (rhMG53) ox-LDL induced LDH release and FM1-43 dye entry were significantly reduced. In the presence of rhMG53, the MAPCs showed enhanced cell survival and proliferation. Our data suggest that membrane damage induced by ox-LDL contributed to the impaired survival of MAPCs. rhMG53 treatment protected MAPCs against membrane damage and enhanced their survival which might represent a novel means for improving efficacy for stem cell-based therapy for treatment of diseases, especially in setting of hyperlipidemia.

  20. Characterization of very-low density lipoprotein particle diameter dynamics in relation to egg production in a passerine bird.

    PubMed

    Salvante, Katrina G; Lin, Gina; Walzem, Rosemary L; Williams, Tony D

    2007-03-01

    During avian egg production, oestrogen mediates marked increases in hepatic lipid production and changes in the diameter of assembled very-low density lipoprotein (VLDL). A nearly complete shift from generic VLDL ( approximately 70 nm in diameter), which transports lipids to peripheral tissues, to yolk-targeted VLDL (VLDLy) ( approximately 30 nm), which supplies the yolk with energy-rich lipid, has been observed in the plasma of laying domestic fowl. We validated an established dynamic laser scattering technique for a passerine songbird Taeniopygia guttata, the zebra finch, to characterize the dynamics of VLDL particle diameter distribution in relation to egg production. We predicted that non-gallinaceous avian species that have not been selected for maximum egg production would exhibit less dramatic shifts in lipid metabolism during egg production. As predicted, there was considerable overlap between the VLDL particle diameter distributions of laying and non-laying zebra finches. But unexpectedly, non-laying zebra finches had VLDL diameter distributions that peaked at small particles and had relatively few large VLDL particles. As a result, laying zebra finches, in comparison, had diameter distributions that were shifted towards larger VLDL particles. Nevertheless, laying zebra finches, like laying chickens, had larger proportions of particles within proposed VLDLy particle diameter ranges than non-laying zebra finches (e.g. sVLDLy: 50% vs 37%). Furthermore, zebra finches and chickens had similar modal (29.7 nm in both species) and median (32.7 nm vs 29.6 nm) VLDL particle diameters during egg production. Therefore, although zebra finches and chickens exhibited opposing directional shifts in VLDL particle diameter distribution during egg production, the modifications to VLDL particle structure in both species resulted in the realization of a common goal, i.e. to produce and maintain a large proportion of small VLDL particles of specific diameters that are capable

  1. Characteristics of Okinawan native agu pig spermatozoa after addition of low-density lipoprotein to freezing extender.

    PubMed

    Yamauchi, Shogo; Nakamura, Satoshi; Lay, Khin Mar; Azuma, Toshiyuki; Yakabi, Tatsuro; Muto, Norio; Nakada, Tadashi; Ashizawa, Koji; Tatemoto, Hideki

    2009-10-01

    Technical refinement of boar sperm cryopreservation is indispensable for effective breeding of the rare Okinawan native pig, the Agu. The objective of the present study was to determine whether addition of low-density lipoprotein (LDL) extracted from hen egg yolk to the freezing extender improves the characteristics of cryopreserved Agu spermatozoa. Ejaculated Agu sperm frozen in extender supplemented with 2, 4, 6, 8 or 10% LDL instead of egg yolk was thawed, and the post-thaw sperm characteristics were evaluated. Treatment with 4-8% LDL during cooling and freezing significantly increased the intracellular cholesterol content, as compared to that of sperm frozen in extender containing 20% egg yolk (P<0.05). Higher potential resistance to cell damage from cryoinjury was also observed in sperm frozen in extender supplemented with LDL: the integrities of plasmalemma and DNA, mitochondrial activity and proteolytic activity of the acrosomal content in the post-thaw sperm were superior to those of sperm that were not treated with LDL. Moreover, the percentages of total motile sperm and the extent of rapid progressive motility at 1 and 3 h after incubation were markedly higher in sperm treated with 4 or 6% LDL, and these sperm also had more ATP. However, LDL did not inhibit in vitro sperm penetrability, even though the cholesterol content of post-thaw sperm was higher after treatment with LDL. These findings indicate that addition of 4-6% LDL instead of egg yolk to the freezing extender improves the post-thaw characteristics of Agu sperm by protecting sperm against cold shock damage during cryopreservation.

  2. Fine Mapping of Five Loci Associated with Low-Density Lipoprotein Cholesterol Detects Variants That Double the Explained Heritability

    PubMed Central

    Sidore, Carlo; Kang, Hyun M.; Jackson, Anne U.; Piras, Maria Grazia; Usala, Gianluca; Maninchedda, Giuseppe; Sassu, Alessandro; Serra, Fabrizio; Palmas, Maria Antonietta; Wood, William H.; Njølstad, Inger; Laakso, Markku; Hveem, Kristian; Tuomilehto, Jaakko; Lakka, Timo A.; Rauramaa, Rainer; Boehnke, Michael; Cucca, Francesco; Uda, Manuela; Schlessinger, David; Nagaraja, Ramaiah; Abecasis, Gonçalo R.

    2011-01-01

    Complex trait genome-wide association studies (GWAS) provide an efficient strategy for evaluating large numbers of common variants in large numbers of individuals and for identifying trait-associated variants. Nevertheless, GWAS often leave much of the trait heritability unexplained. We hypothesized that some of this unexplained heritability might be due to common and rare variants that reside in GWAS identified loci but lack appropriate proxies in modern genotyping arrays. To assess this hypothesis, we re-examined 7 genes (APOE, APOC1, APOC2, SORT1, LDLR, APOB, and PCSK9) in 5 loci associated with low-density lipoprotein cholesterol (LDL-C) in multiple GWAS. For each gene, we first catalogued genetic variation by re-sequencing 256 Sardinian individuals with extreme LDL-C values. Next, we genotyped variants identified by us and by the 1000 Genomes Project (totaling 3,277 SNPs) in 5,524 volunteers. We found that in one locus (PCSK9) the GWAS signal could be explained by a previously described low-frequency variant and that in three loci (PCSK9, APOE, and LDLR) there were additional variants independently associated with LDL-C, including a novel and rare LDLR variant that seems specific to Sardinians. Overall, this more detailed assessment of SNP variation in these loci increased estimates of the heritability of LDL-C accounted for by these genes from 3.1% to 6.5%. All association signals and the heritability estimates were successfully confirmed in a sample of ∼10,000 Finnish and Norwegian individuals. Our results thus suggest that focusing on variants accessible via GWAS can lead to clear underestimates of the trait heritability explained by a set of loci. Further, our results suggest that, as prelude to large-scale sequencing efforts, targeted re-sequencing efforts paired with large-scale genotyping will increase estimates of complex trait heritability explained by known loci. PMID:21829380

  3. Analysis of low-density lipoprotein-associated proteins using the method of digitized native protein mapping.

    PubMed

    Jin, Ya; Chen, Jin; Wang, Ahui; Zhang, Jun; Chen, Shumin; Manabe, Takashi; Tan, Wen

    2016-07-01

    The method of digitized native protein mapping, combining nondenaturing micro 2DE, grid gel-cutting, and quantitative LC-MS/MS (in data-independent acquisition mode, or MS(E) ), was improved by using a new MS/MS mode, ion mobility separation enhanced-MS(E) (HDMS(E) ), and applied to analyze the area of human plasma low-density lipoprotein (LDL). An 18 mm × 4.8 mm rectangular area which included LDL on a nondenaturing micro 2D gel of human plasma was grid-cut into 72 square gel pieces and subjected to quantitative LC-MS/MS. Compared with MS(E) , HDMS(E) showed significantly higher performance, by assigning 50% more proteins and detecting each protein in more squares. A total of 253 proteins were assigned with LC-HDMS(E) and the quantity distribution of each was reconstructed as a native protein map. The maps showed that Apo B-100 was the most abundant protein in the grid-cut area, concentrated at pI ca. 5.4-6.1 and apparent mass ca. 1000 kDa, which corresponded to four gel pieces, squares 39-42. An Excel macro was prepared to search protein maps which showed protein quantity peaks localized within this concentrated region of Apo B-100. Twenty-two proteins out of the 252 matched this criterion, in which 19 proteins have been reported to be associated with LDL. This method only requires several microliters of a plasma sample and the principle of the protein separation is totally different from the commonly used ultracentrifugation. The results obtained by this method would provide new insights on the structure and function of LDL.

  4. Gestational diabetes and the metabolic syndrome: can obesity and small, dense low density lipoproteins be key mediators of this association?

    PubMed

    Rizvi, Ali A; Cuadra, Silvia; Nikolic, Dragana; Giglio, Rosaria V; Montalto, Giuseppe; Rizzo, Manfredi

    2014-01-01

    Gestational diabetes mellitus (GDM) represents a condition of glucose intolerance with first appearance or recognition at the time of a pregnancy, associated with an inadequate pancreatic response to the advanced insulin resistance of the later stages of pregnancy, and accompanied by enhancing β-cell mass and secretion of insulin. Women who had GDM exhibit a higher risk for later advent of type 2 diabetes mellitus (T2DM) and cardiovascular diseases (CVD). Additionally, previous GDM has been proposed as independently correlated with higher risk for development of atherosclerosis in a healthy population, similar to the metabolic syndrome (MetS) and independently of the presence of established CVD risk factors. Available data indicate multiple metabolic abnormalities common in women with GDM, including a high small dense low-density lipoprotein (sdLDL) concentration and a resultant high prevalence of CVD and the MetS. Preliminary data indicate that a measurement of sdLDL is worthwhile in women with GDM during pregnancy as well as the postpartum period. A close follow up of these women should be emphasized in clinical practice because GDM could predict not only eventual health risks for these mothers, but also their offspring. Thus, an improvement in care and risk modification of women with GDM may not only contribute towards improved CVD profile, but also potentially prevent adverse outcomes in their offspring. Lifestyle changes should be promoted in order to prevent excessive weight gain during pregnancy and decrease the risk of MetS in the postpartum and long-term.

  5. Clinical Outcomes according to the Achievement of Target Low Density Lipoprotein-Cholesterol in Patients with Acute Myocardial Infarction

    PubMed Central

    Ahn, Taehoon; Lee, Kyounghoon; Kang, Woong Chol; Han, Seung Hwan; Ahn, Youngkeun; Jeong, Myung Ho

    2017-01-01

    Background and Objectives The clinical outcome of patient with an acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI), with or without achievement of target low density lipoprotein-cholesterol (LDL-C), has little known information. This study investigated if target LDL-C level (below 70 mg/dL) achievements in patients with AMI showed better clinical outcomes or not. Subjects and Methods Between May 2008 and September 2012, this study enrolled 13473 AMI patients in a large-scale, prospective, multicenter Korean Myocardial Infarction (KorMI) registry. 12720 patients survived and 6746 patients completed a 1-year clinical follow up. Among them 3315 patients received serial lipid profile follow-ups. Propensity score matching was applied to adjust for differences in clinical baseline and angiographic characteristics, producing a total of 1292 patients (646 target LDL-C achievers vs. 646 non-achievers). The primary end point was the composite of a 1-year major adverse cardiac event (MACE) including cardiac death, recurrent myocardial infarction (MI), target lesion revascularization (TLR) and coronary artery bypass grafting. Results After propensity score matching, baseline clinical and angiographic characteristics were similar between the two groups. Clinical outcomes of the propensity score matched patients who showed no significant differences in cardiac death (0.5% vs. 0.5%, p=1.000), recurrent MI (1.1% vs. 0.8%, p=0.562), TLR (5.0% vs. 4.5%, p=0.649), MACEs (6.5% vs. 5.9%, p=0.644) and stent thrombosis (2.5% vs. 1.9%, p=0.560). Conclusion In this propensity-matched comparison, AMI patients undergoing PCI with a target LDL-C (below 70 mg/dL) achievement did not show better clinical outcomes. PMID:28154588

  6. Identification of miR-185 as a regulator of de novo cholesterol biosynthesis and low density lipoprotein uptake

    PubMed Central

    Yang, Muhua; Liu, Weidong; Pellicane, Christina; Sahyoun, Christine; Joseph, Biny K.; Gallo-Ebert, Christina; Donigan, Melissa; Pandya, Devanshi; Giordano, Caroline; Bata, Adam; Nickels, Joseph T.

    2014-01-01

    Dysregulation of cholesterol homeostasis is associated with various metabolic diseases, including atherosclerosis and type 2 diabetes. The sterol response element binding protein (SREBP)-2 transcription factor induces the expression of genes involved in de novo cholesterol biosynthesis and low density lipoprotein (LDL) uptake, thus it plays a crucial role in maintaining cholesterol homeostasis. Here, we found that overexpressing microRNA (miR)-185 in HepG2 cells repressed SREBP-2 expression and protein level. miR-185-directed inhibition caused decreased SREBP-2-dependent gene expression, LDL uptake, and HMG-CoA reductase activity. In addition, we found that miR-185 expression was tightly regulated by SREBP-1c, through its binding to a single sterol response element in the miR-185 promoter. Moreover, we found that miR-185 expression levels were elevated in mice fed a high-fat diet, and this increase correlated with an increase in total cholesterol level and a decrease in SREBP-2 expression and protein. Finally, we found that individuals with high cholesterol had a 5-fold increase in serum miR-185 expression compared with control individuals. Thus, miR-185 controls cholesterol homeostasis through regulating SREBP-2 expression and activity. In turn, SREBP-1c regulates miR-185 expression through a complex cholesterol-responsive feedback loop. Thus, a novel axis regulating cholesterol homeostasis exists that exploits miR-185-dependent regulation of SREBP-2 and requires SREBP-1c for function. PMID:24296663

  7. Ceruloplasmin enhances smooth muscle cell- and endothelial cell-mediated low density lipoprotein oxidation by a superoxide-dependent mechanism

    NASA Technical Reports Server (NTRS)

    Mukhopadhyay, C. K.; Ehrenwald, E.; Fox, P. L.

    1996-01-01

    Cultured vascular smooth muscle cells (SMC) and endothelial cells (EC) stimulate low density lipoprotein (LDL) oxidation by free radical-mediated, transition metal-dependent mechanisms. The physiological source(s) of metal ions is not known; however, purified ceruloplasmin, a plasma protein containing 7 coppers, oxidizes LDL in vitro. We now show that ceruloplasmin also increases LDL oxidation by vascular cells. In metal ion-free medium, human ceruloplasmin increased bovine aortic SMC- and EC-mediated LDL oxidation by up to 30- and 15-fold, respectively. The maximal response was at 100-300 microg ceruloplasmin/ml, a level at or below the unevoked physiological plasma concentration. Oxidant activity was dependent on protein structure as a specific proteolytic cleavage or removal of one of the seven ceruloplasmin copper atoms inhibited activity. Three lines of evidence indicated a critical role for cellular superoxide (O2.) in ceruloplasmin-stimulated oxidation. First, the rate of production of O2. by cells correlated with their rates of LDL oxidation. Second, superoxide dismutase effectively blocked ceruloplasmin-stimulated oxidation by both cell types. Finally, O2. production by SMC quantitatively accounted for the observed rate of LDL oxidation. To show this, the course of O2. production by SMC was simulated by repeated addition of xanthine and xanthine oxidase to culture medium under cell-free conditions. Neither ceruloplasmin nor O2. alone increased LDL oxidation, but together they completely reconstituted the oxidation rate of ceruloplasmin-stimulated SMC. These results are the first to show that ceruloplasmin stimulates EC- and SMC-mediated oxidation of LDL and that cell-derived O2. accounts quantitatively for metal-dependent, free radical-initiated oxidation of LDL by these cells.

  8. Proliferation of macrophages due to the inhibition of inducible nitric oxide synthesis by oxidized low-density lipoproteins

    PubMed Central

    Brunner, Monika; Gruber, Miriam; Schmid, Diethart; Baran, Halina; Moeslinger, Thomas

    2015-01-01

    Oxidized low-density lipoprotein (ox-LDL) is assumed to be a major causal agent in hypercholesteraemia-induced atherosclerosis. Because the proliferation of lipid-loaden macrophages within atherosclerotic lesions has been described, we investigated the dependence of macrophage proliferation on the inhibition of inducible nitric oxide synthase (iNOS) by hypochlorite oxidized LDL. Ox-LDL induces a dose dependent inhibition of inducible nitric oxide synthesis in lipopolysaccharide-interferon stimulated mouse macrophages (J774.A1) with concomitant macrophage proliferation as assayed by cell counting, tritiated-thymidine incorporation and measurement of cell protein. Native LDL did not influence macrophage proliferation and inducible nitric oxide synthesis. iNOS protein and mRNA was reduced by HOCl-oxidized LDL (0-40 µg/ml) as revealed by immunoblotting and competitive semiquantitative PCR. Macrophage proliferation was increased by the addition of the iNOS inhibitor L-NAME. The addition of ox-LDL to L-NAME containing incubations induced no further statistically significant increase in cell number. Nitric oxide donors decreased ox-LDL induced macrophage proliferation and nitric oxide scavengers restored macrophage proliferation to the initial values achieved by ox-LDL. The decrease of cytosolic DNA fragments in stimulated macrophages incubated with ox-LDL demonstrates that the proliferative actions of ox-LDL are associated with a decrease of NO-induced apoptosis. Our data show that inhibition of iNOS dependent nitric oxide production caused by hypochlorite oxidized LDL enhances macrophage proliferation. This might be a key event in the pathogenesis of atherosclerotic lesions. PMID:26600745

  9. Effect of Vitamin Supplementation on Serum Oxidized Low-Density Lipoprotein Levels in Male Subjects with Cardiovascular Disease Risk Factors

    PubMed Central

    Najafpour Boushehri, Saeid; Yusof, Rokiah Mohammad; Nasir Mohammad Taib, Mohammad; Mirzaei, Kamran; Yazdekhasti, Narges; Akbarzadeh, Samad

    2012-01-01

    Objective(s):Oxidized low-density lipoproteins (ox-LDLs) appear to play a significant role in atherogenesis. In fact, circulating ox-LDL concentrations have been recognized as a risk factor for cardiovascular disease (CVD). The main objectives of this study were to assess the effects of antioxidant vitamins on ox-LDL as a biomarker of CVD in male subjects with CVD risk factors. Materials and Methods:The effect of antioxidant vitamins on ox-LDL as a biomarker of CVD in male subjects with CVD in male subjects with CVD risk factors at baseline and after 12 weeks of supplementation with vitamin E (400 IU), C (500 mg), ß-carotene (15 mg), and the combined supplements (E, C, and ß-carotene) respectively defined as group E, C, B and control group was considered as group P. Results:The mean values for ox-LDL at the baseline were 86.93 ± 26.30 U/l in group C, 94.52 ± 38.40 U/l in group E, 79.73±2.07 U/l in group B, 85.97±23.07 U/l in combined group, and 84.90± 14.66 U/l in group P. After 12 weeks of intervention the percentage of changes for group C, group E, group B, COM group, and group P were (-18.32), (-2286), (-17.31), (-19.01) and (-2.0), respectively. Using Wilcoxon method, significant differences were detected in the mean ox-LDL concentrations of baseline and after intervention, values in the C, E, B and combined groups (P< 005). Conclusion:This study illustrated that diet supplemented with vitamin C (500 mg), vitamin E (400 IU), ß-carotene (15 mg), and the combination of these vitamins was associated with lower serum ox-LDL levels. PMID:23493764

  10. Oxidative susceptibility of low density lipoprotein subfractions is related to their ubiquinol-10 and alpha-tocopherol content.

    PubMed Central

    Tribble, D L; van den Berg, J J; Motchnik, P A; Ames, B N; Lewis, D M; Chait, A; Krauss, R M

    1994-01-01

    The conjugated polyene fatty acid parinaric acid (PnA) undergoes a stoichiometric loss in fluorescence upon oxidation and can be used to directly monitor peroxidative stress within lipid environments. We evaluated the course of potentially atherogenic oxidative changes in low density lipoproteins (LDL) by monitoring the oxidation of PnA following its incorporation into buoyant (p = 1.026-1.032 g/ml) and dense (p = 1.040-1.054 g/ml) LDL subfractions. Copper-induced oxidation of LDL-associated PnA exhibited an initial lag phase followed by an increased rate of loss until depletion. Increased PnA oxidation occurred immediately after the antioxidants ubiquinol-10 and alpha-tocopherol were consumed but before there were marked elevations in conjugated dienes. Despite differences in sensitivity to early oxidation events, PnA oxidation and conjugated diene lag times were correlated (r = 0.582; P = 0.03), and both indicated a greater susceptibility of dense than buoyant LDL in accordance with previous reports. The greater susceptibility of PnA in dense LDL was attributed to reduced levels of ubiquinol-10 and alpha-tocopherol, which were approximately 50% lower than in buoyant LDL (mol of antioxidant/mol of LDL) and together accounted for 80% of the variation in PnA oxidation lag times. These results suggest that PnA is a useful probe of LDL oxidative susceptibility and may be superior to conjugated dienes for monitoring the initial stages of LDL lipid peroxidation. Differences in oxidative susceptibility among LDL density subfractions are detected by the PnA assay and are due in large part to differences in their antioxidant content. PMID:8302851

  11. Validity of a Novel Method for Estimation of Low-Density Lipoprotein Cholesterol Levels in Diabetic Patients

    PubMed Central

    Chaen, Hideto; Kinchiku, Shigesumi; Kajiya, Shoko; Uenomachi, Hitoshi; Yuasa, Toshinori; Takasaki, Kunitsugu; Ohishi, Mitsuru

    2016-01-01

    Aim: Low-density lipoprotein cholesterol (LDL-C) is routinely estimated using the Friedewald equation [LDL-C(F)]. A novel method for LDL-C [LDL-C(M)] estimation recently proposed by Martin et al. was reported to be more accurate than the Friedewald formula in subjects in the United States. The validity of LDL-C(M) in different races and patients with diabetes mellitus (DM) has not been elucidated. The purpose of this study was to validate the LDL-C(M) estimates in Japanese population with type 2 DM by comparing with LDL-C(F) and directly measured LDL-C [LDL-C(D)]. Methods: Both LDL-C(M) and LDL-C(F) levels were compared against LDL-C(D) measured by selective solubilization method in 1,828 Japanese patients with type 2 DM. Results: On linear regression analysis, LDL-C(M) showed a stronger correlation than that shown by LDL-C(F) (R = 0.979 vs. R = 0.953, respectively) with LDL-C(D). We further analyzed the effect of serum triglyceride (TG) concentrations on the accuracy of LDL-C(F) and LDL-C(M). Although LDL-C levels showed a positive correlation with TG levels, the LDL-C(F) levels tended to show a greater divergence from LDL-C(D) levels than that shown by LDL-C(M) with changes in TG levels. Conclusion: We for the first time demonstrated a more useful measurement of LDL-C levels estimated by Martin's method than that estimated by the Friedewald equation in Japanese patients with DM. PMID:27592628

  12. A comparison of the kinetics of low-density lipoprotein oxidation initiated by copper or by azobis (2-amidinopropane).

    PubMed

    Thomas, M J; Chen, Q; Franklin, C; Rudel, L L

    1997-01-01

    This article describes the kinetics of low density lipoprotein (LDL) oxidation catalyzed by azobis (2-amidinopropane) dihydrochloride, ABAP, or by copper. The LDLs were isolated from nonhuman primates fed diets enriched in one of three types of fatty acids: saturated fatty acids, monounsaturated fatty acids, predominantly, oleic acid, or polyunsaturated fatty acids, predominantly linoleic acid. Oxidation was followed by monitoring the formation of conjugated diene hydroperoxides from polyunsaturated fatty acids (PUFA). For both copper and ABAP-initiated oxidation, the rate of LDL oxidation depended on the concentrations of initiator, PUFA, and LDL. Except for the dependence on PUFA concentration the rate of LDL oxidation was not directly influenced by the fatty acid composition of the LDL particle. The two initiators had very different dependence on initiator concentration. Because LDL particles are essentially small, lipid-rich droplets, the kinetic descriptions of LDL oxidation assumed: (1), that there was only one chain per particle, and (2) that the radical chain was terminated when a second radical either entered or was formed in the particle. When two LDL samples having very different lag times were mixed, the oxidation profile was bimodal. This finding demonstrated that the oxidation of native LDL particles was independent of the oxidation state of the other native LDL particles in solution, i.e., LDL particles do not rapidly exchange radicals, for example, hydroperoxyl radicals. Oxidation initiated by ABAP was proportional to [ABAP]0.5, suggesting that hydroperoxyl radical recombination between the lipid hydroperoxyl radical and the ABAP-hydroperoxyl radical was the chain-terminating step. The reciprocal of the rate of copper oxidation was linearly related to the reciprocal copper concentration, demonstrating that the binding of copper to LDL was necessary to initiate oxidation. This binding constant showed considerable variability among LDL samples. The

  13. Electrophoretic analysis of oxidative modification of apolipoprotein E in very low density lipoprotein from fresh human plasma.

    PubMed

    Kashiwagi, S; Nakamura, K; Arai, H; Yamashita, H; Ito, H

    1999-06-01

    Ferrous ion-induced oxidative modification of apoE in lipid peroxidation of human very low density lipoprotein (VLDL) and the role of the cysteinyl group, present in apoE3 but absent in apoE4, were examined. Fresh human VLDL was obtained from healthy volunteers with different apoE phenotypes as determined by