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Sample records for density lipoprotein binding

  1. Negatively Cooperative Binding of High Density Lipoprotein to the HDL Receptor SR-BI†

    PubMed Central

    Nieland, Thomas J.F.; Xu, Shangzhe; Penman, Marsha; Krieger, Monty

    2011-01-01

    Scavenger receptor class B, type I (SR-BI) is a high-density lipoprotein (HDL) receptor, which also binds low density lipoprotein (LDL), and mediates the cellular selective uptake of cholesteryl esters from lipoproteins. SR-BI also is a co-receptor for hepatitis C virus and a signaling receptor that regulates cell metabolism. Many investigators have reported that lipoproteins bind to SR-BI via a single class of independent (not interacting), high affinity binding sites (one site model). We have re-investigated the ligand concentration dependence of 125I-HDL binding to SR-BI and SR-BI-mediated specific uptake of [3H]CE from [3H]CE-HDL using an expanded range of ligand concentrations (<1 µg protein/ml, lower than previously reported). Scatchard and non-linear least squares model fitting analyses of the binding and uptake data were both inconsistent with a single class of independent binding sites binding univalent lipoprotein ligands. The data are best fit by models in which SR-BI has either two independent classes of binding sites, or one class of sites exhibiting negative cooperativity due to either classic allostery or ensemble effects (‘ lattice model’). Similar results were observed for LDL. Application of the ‘infinite dilution’ dissociation rate method established that the binding of 125I-HDL to SR-BI at 4 °C exhibits negative cooperativity. The unexpected complexity of the interactions of lipoproteins with SR-BI should be taken into account when interpreting the results of experiments that explore the mechanism(s) by which SR-BI mediates ligand binding, lipid transport and cell signaling. PMID:21254782

  2. 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.

  3. One precursor, three apolipoproteins: the relationship between two crustacean lipoproteins, the large discoidal lipoprotein and the high density lipoprotein/β-glucan binding protein.

    PubMed

    Stieb, Stefanie; Roth, Ziv; Dal Magro, Christina; Fischer, Sabine; Butz, Eric; Sagi, Amir; Khalaila, Isam; Lieb, Bernhard; Schenk, Sven; Hoeger, Ulrich

    2014-12-01

    The novel discoidal lipoprotein (dLp) recently detected in the crayfish, differs from other crustacean lipoproteins in its large size, apoprotein composition and high lipid binding capacity, We identified the dLp sequence by transcriptome analyses of the hepatopancreas and mass spectrometry. Further de novo assembly of the NGS data followed by BLAST searches using the sequence of the high density lipoprotein/1-glucan binding protein (HDL-BGBP) of Astacus leptodactylus as query revealed a putative precursor molecule with an open reading frame of 14.7 kb and a deduced primary structure of 4889 amino acids. The presence of an N-terminal lipid bind- ing domain and a DUF 1943 domain suggests the relationship with the large lipid transfer proteins. Two-putative dibasic furin cleavage sites were identified bordering the sequence of the HDL-BGBP. When subjected to mass spectroscopic analyses, tryptic peptides of the large apoprotein of dLp matched the N-terminal part of the precursor, while the peptides obtained for its small apoprotein matched the C-terminal part. Repeating the analysis in the prawn Macrobrachium rosenbergii revealed a similar protein with identical domain architecture suggesting that our findings do not represent an isolated instance. Our results indicate that the above three apolipoproteins (i.e HDL-BGBP and both the large and the small subunit of dLp) are translated as a large precursor. Cleavage at the furin type sites releases two subunits forming a heterodimeric dLP particle, while the remaining part forms an HDL-BGBP whose relationship with other lipoproteins as well as specific functions are yet to be elucidated.

  4. High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages

    PubMed Central

    Ichimura, Naoya; Sato, Megumi; Yoshimoto, Akira; Yano, Kouji; Ohkawa, Ryunosuke; Kasama, Takeshi

    2016-01-01

    High-density lipoprotein (HDL) is involved in innate immunity toward various infectious diseases. Concerning bacteria, HDL is known to bind to lipopolysaccharide (LPS) and to neutralize its physiological activity. On the other hand, cholesterol is known to play an important role in mycobacterial entry into host cells and in survival in the intracellular environment. However, the pathogenicity of Mycobacterium avium (M. avium) infection, which tends to increase worldwide, remains poorly studied. Here we report that HDL indicated a stronger interaction with M. avium than that with other Gram-negative bacteria containing abundant LPS. A binding of apolipoprotein (apo) A-I, the main protein component of HDL, with a specific lipid of M. avium might participate in this interaction. HDL did not have a direct bactericidal activity toward M. avium but attenuated the engulfment of M. avium by THP-1 macrophages. HDL also did not affect bacterial killing after ingestion of live M. avium by THP-1 macrophage. Furthermore, HDL strongly promoted the formation of lipid droplets in M. avium-infected THP-1 macrophages. These observations provide new insights into the relationship between M. avium infection and host lipoproteins, especially HDL. Thus, HDL may help M. avium to escape from host innate immunity. PMID:27516907

  5. 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.

  6. 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.

  7. Specific high-affinity binding of high density lipoproteins to cultured human skin fibroblasts and arterial smooth muscle cells.

    PubMed

    Biesbroeck, R; Oram, J F; Albers, J J; Bierman, E L

    1983-03-01

    Binding of human high density lipoproteins (HDL, d = 1.063-1.21) to cultured human fibroblasts and human arterial smooth muscle cells was studied using HDL subjected to heparin-agarose affinity chromatography to remove apoprotein (apo) E and B. Saturation curves for binding of apo E-free 125I-HDL showed at least two components: low-affinity nonsaturable binding and high-affinity binding that saturated at approximately 20 micrograms HDL protein/ml. Scatchard analysis of high-affinity binding of apo E-free 125I-HDL to normal fibroblasts yielded plots that were significantly linear, indicative of a single class of binding sites. Saturation curves for binding of both 125I-HDL3 (d = 1.125-1.21) and apo E-free 125I-HDL to low density lipoprotein (LDL) receptor-negative fibroblasts also showed high-affinity binding that yielded linear Scatchard plots. On a total protein basis, HDL2 (d = 1.063-1.10), HDL3 and very high density lipoproteins (VHDL, d = 1.21-1.25) competed as effectively as apo E-free HDL for binding of apo E-free 125I-HDL to normal fibroblasts. Also, HDL2, HDL3, and VHDL competed similarly for binding of 125I-HDL3 to LDL receptor-negative fibroblasts. In contrast, LDL was a weak competitor for HDL binding. These results indicate that both human fibroblasts and arterial smooth muscle cells possess specific high affinity HDL binding sites. As indicated by enhanced LDL binding and degradation and increased sterol synthesis, apo E-free HDL3 promoted cholesterol efflux from fibroblasts. These effects also saturated at HDL3 concentrations of 20 micrograms/ml, suggesting that promotion of cholesterol efflux by HDL is mediated by binding to the high-affinity cell surface sites.

  8. Lipoprotein binding to cultured human hepatoma cells.

    PubMed Central

    Krempler, F; Kostner, G M; Friedl, W; Paulweber, B; Bauer, H; Sandhofer, F

    1987-01-01

    Binding of various 125I-lipoproteins to hepatic receptors was studied on cultured human hepatoma cells (Hep G2). Chylomicrons, isolated from a chylothorax, chylomicron remnants, hypertriglyceridemic very low-density lipoproteins, normotriglyceridemic very low-density lipoproteins (NTG-VLDL), their remnants, low-density lipoproteins (LDL), and HDL-E (an Apo E-rich high-density lipoprotein isolated from the plasma of a patient with primary biliary cirrhosis) were bound by high-affinity receptors. Chylomicron remnants and HDL-E were bound with the highest affinity. The results, obtained from competitive binding experiments, are consistent with the existence of two distinct receptors on Hep G2 cells: (a) a remnant receptor capable of high-affinity binding of triglyceride-rich lipoproteins and HDL-E, but not of Apo E free LDL, and (b) a LDL receptor capable of high-affinity binding of LDL, NTG-VLDL, and HDL-E. Specific binding of Apo E-free LDL was completely abolished in the presence of 3 mM EDTA, indicating that binding to the LDL receptor is calcium dependent. Specific binding of chylomicron remnants was not inhibited by the presence of even 10 mM EDTA. Preincubation of the Hep G2 cells in lipoprotein-containing medium resulted in complete suppression of LDL receptors but did not affect the remnant receptors. Hep G2 cells seem to be a suitable model for the study of hepatic receptors for lipoprotein in man. Images PMID:3038957

  9. 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.

  10. 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

  11. The binding of human low-density lipoproteins to the surface of schistosomula of Schistosoma mansoni is inhibited by polyanions and reduces the binding of anti-schistosomal antibodies.

    PubMed Central

    Chiang, C. P.; Caulfield, J. P.

    1989-01-01

    Host molecules such as serum lipoproteins, blood group glycolipids, and histocompatibility antigens may bind to schistosomes and thereby prevent immune recognition of the parasite. This study examines the kinetics of lipoprotein binding, the ability of polyanions to inhibit lipoprotein binding, the binding of anti-schistosomal antibodies to worms that have previously bound low-density lipoprotein (LDL), and the distribution of lipoproteins bound to the parasites. Lipoproteins in human serum (HS) and purified LDL, very low-density lipoprotein (VLDL), and apolipoprotein B (apo B) in defined media were demonstrated on the surface of schistosomula of Schistosoma mansoni by fluorescence and immunoelectron microscopy using a polyclonal goat anti-human apolipoprotein B antibody (anti-apo B). By fluorophotometric microscopy, lipoprotein binding began within 15 minutes and was largely completed within 3 hours of exposure. Lipoprotein binding saturated at 10% HS or 20 micrograms protein/300 microliters of purified LDL. Suramin inhibited LDL binding by 59% in a dose-dependent fashion. In the absence of LDL in the medium, 2 mM suramin dissociated 41% of bound LDL from the worm surface within 15 minutes and 10 mg/ml heparin dissociated 36%. The binding of human anti-schistosomal antibodies to schistosomula was inhibited by bound LDL. By fluorescence microscopy, serum or purified lipoproteins were distributed over the entire surface of the parasite with focal areas of high intensity. Ultrastructurally, reaction product was seen on the outer leaflet of the outer tegumental membrane and in aggregates and surrounding vesicular structures varying in diameter from 13 to 83 nm. These studies demonstrate that lipoproteins bind to the surface of schistosomula. The binding of lipoproteins is partially inhibited by polyanions, reduces the binding of human anti-schistosomal antibodies, and may help the parasite escape the immune response. Images Figure 1 Figure 9 Figure 10 PMID:2719071

  12. 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.

  13. 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.

  14. Binding of anthracycline derivatives to human serum lipoproteins.

    PubMed

    Chassany, O; Urien, S; Claudepierre, P; Bastian, G; Tillement, J P

    1994-01-01

    The binding of eight anthracycline analogues (including mitoxantrone) to isolated serum lipoproteins (high, low and very low density lipoproteins) was studied in order to elucidate some determinants of their interaction with lipidic structures. Serum lipoproteins were isolated by ultracentrifugation. Drug binding experiments were run by ultrafiltration at 37 degrees C and pH 7.4. Anthracycline concentrations (total and free) were determined by HPLC with fluorometric detection. All the ligands were significantly bound to the three lipoprotein classes, and for each ligand the binding increased as the lipidic fraction of lipoprotein increased. From doxorubicin to iododoxorubicin, there was a tenfold increase in lipoprotein binding (doxorubicin < mitoxantrone < epirubicin < daunorubicin < pirarubicin < aclarubicin < zorubicin < iododoxorubicin). For all the ligands studied, the extent of lipoprotein binding appears to be related to chemical determinants of lipophilicity.

  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. 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.

  17. 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.

  18. The role of apoproteins AI and AII in binding of high-density lipoprotein3 to membranes derived from bovine aortic endothelial cells.

    PubMed Central

    Vadiveloo, P K; Fidge, N H

    1992-01-01

    Although binding of high-density lipoproteins (HDL) to a variety of cells in culture has been widely reported, the mechanism of this binding has yet to be fully elucidated. The aim of the current studies was to explore the roles of apoproteins (apo) AI and AII in HDL3 binding to membranes derived from bovine aortic endothelial cells. Binding studies showed that HDL3 (which contains both apo AI and apo AII) and AII-HDL3 (which contain only apo AII) bound to membranes with similar affinity (44 +/- 6 and 41 +/- 9 micrograms/ml respectively) and capacity (673 +/- 97 and 969 +/- 101 ng bound/mg of membrane protein respectively). In contrast with these results, HDL3 [AI w/o AII] (which contain apo AI, but not apo AII) bound to the membranes with a significantly higher capacity (2228 +/- 206 ng bound/mg of membrane protein) and lower affinity (65 +/- 3 micrograms/ml) as compared with HDL3 or AII-HDL3. Therefore, although both apo AI and apo AII appear capable of facilitating HDL3 binding, the mechanisms involved probably differ. A model which fits the data postulates that a common receptor exists which binds both apo AI and apo AII, and that a particle containing AII can occupy up to four receptors (partly owing to each AII molecule containing two binding domains), whereas an HDL3 [AI w/o AII] particle can occupy only one. Images Fig. 3. PMID:1599393

  19. Starvation and diet composition affect mRNA levels of the high density-lipoprotein-beta glucan binding protein in the shrimp Litopenaeus vannamei.

    PubMed

    Muhlia-Almazán, Adriana; Sánchez-Paz, Arturo; García-Carreño, Fernando; Peregrino-Uriarte, Alma Beatriz; Yepiz-Plascencia, Gloria

    2005-10-01

    A high density lipoprotein-beta glucan binding protein (HDL-BGBP) is synthesized in the hepatopancreas of the white shrimp Litopenaeus vannamei and secreted to the hemolymph. Recently, we reported the HDL-BGBP full length cDNA sequence and found that the predicted polypeptide is larger than the mature protein and also, that it contains a long 5'- and 3'-UTRs that may be involved in transcript level regulation. To test whether starvation and feeding may play a role in regulating HDL-BGBP mRNA levels, two different stimuli were evaluated: starvation and composition of diets. After 24 h, the steady state HDL-BGBP mRNA levels of starved shrimp decreased, suggesting that synthesis of the lipoprotein is less required in the absence of food. When shrimp were fed with diets containing different concentrations of protein and lipids, changes in HDL-BGBP mRNA levels were also detected. Shrimp fed the lower concentration of protein and lipid feed accumulated higher levels of HDL-BGBP mRNA. These results indicate that feeding influences HDL-BGBP transcript levels in the hepatopancreas.

  20. 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.

  1. Simultaneous binding of the anti-cancer IgM monoclonal antibody PAT-SM6 to low density lipoproteins and GRP78.

    PubMed

    Rosenes, Zachary; Mok, Yee-Foong; Yang, Shuo; Griffin, Michael D W; Mulhern, Terrence D; Hatters, Danny M; Hensel, Frank; Howlett, Geoffrey J

    2013-01-01

    The tumour-derived monoclonal IgM antibody PAT-SM6 specifically kills malignant cells by an apoptotic mechanism linked to the excessive uptake of plasma lipids. The mechanism is postulated to occur via the multi-point attachment of PAT-SM6 to the unfolded protein response regulator GRP78, located on the surface of tumour cells, coupled to the simultaneous binding of plasma low density lipoprotein (LDL). We prepared and characterised LDL and oxidized LDL using sedimentation velocity and small-angle X-ray scattering (SAXS) analysis. Enzyme-linked immunosorbent (ELISA) techniques indicated apparent dissociation constants of approximately 20 nM for the binding of LDL or oxidized LDL to PAT-SM6. ELISA experiments showed cross competition with LDL inhibiting PAT-SM6 binding to immobilised GRP78, while, in the reverse experiment, GRP78 inhibited PAT-SM6 binding to immobilized LDL. In contrast to the results of the ELISA experiments, sedimentation velocity experiments indicated relatively weak interactions between LDL and PAT-SM6, suggesting immunoabsorbance to the microtiter plate is driven by an avidity-based binding mechanism. The importance of avidity and the multipoint attachment of antigens to PAT-SM6 was further investigated using antigen-coated polystyrene beads. Absorption of GRP78 or LDL to polystyrene microspheres led to an increase in the inhibition of PAT-SM6 binding to microtiter plates coated with GRP78 or LDL, respectively. These results support the hypothesis that the biological action of PAT-SM6 in tumour cell apoptosis depends on the multivalent nature of PAT-SM6 and the ability to interact simultaneously with LDL and multiple GRP78 molecules clustered on the tumour cell surface.

  2. 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

  3. 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.

  4. 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.

  5. Surface plasmon resonance analysis of the mechanism of binding of apoA-I to high density lipoprotein particles

    PubMed Central

    Lund-Katz, Sissel; Nguyen, David; Dhanasekaran, Padmaja; Kono, Momoe; Nickel, Margaret; Saito, Hiroyuki; Phillips, Michael C.

    2010-01-01

    The partitioning of apolipoprotein A-I (apoA-I) molecules in plasma between HDL-bound and -unbound states is an integral part of HDL metabolism. We used the surface plasmon resonance (SPR) technique to monitor in real time the reversible binding of apoA-I to HDL. Biotinylated human HDL2 and HDL3 were immobilized on a streptavidin-coated SPR sensor chip, and apoA-I solutions at different concentrations were flowed across the surface. The wild-type (WT) human and mouse apoA-I/HDL interaction involves a two-step process; apoA-I initially binds to HDL with fast association and dissociation rates, followed by a step exhibiting slower kinetics. The isolated N-terminal helix bundle domains of human and mouse apoA-I also exhibit a two-step binding process, consistent with the second slower step involving opening of the helix bundle domain. The results of fluorescence experiments with pyrene-labeled apoA-I are consistent with the N-terminal helix bundle domain interacting with proteins resident on the HDL particle surface. Dissociation constants (Kd) measured for WT human apoA-I interactions with HDL2 and HDL3 are about 10 µM, indicating that the binding is low affinity. This Kd value does not apply to all of the apoA-I molecules on the HDL particle but only to a relatively small, labile pool. PMID:19786567

  6. Complement Factor H Binds to Human Serum Apolipoprotein E and Mediates Complement Regulation on High Density Lipoprotein Particles.

    PubMed

    Haapasalo, Karita; van Kessel, Kok; Nissilä, Eija; Metso, Jari; Johansson, Tiira; Miettinen, Sini; Varjosalo, Markku; Kirveskari, Juha; Kuusela, Pentti; Chroni, Angelika; Jauhiainen, Matti; van Strijp, Jos; Jokiranta, T Sakari

    2015-11-27

    The alternative pathway of complement is an important part of the innate immunity response against foreign particles invading the human body. To avoid damage to host cells, it needs to be efficiently down-regulated by plasma factor H (FH) as exemplified by various diseases caused by mutations in its domains 19-20 (FH19-20) and 5-7 (FH5-7). These regions are also the main interaction sites for microbial pathogens that bind host FH to evade complement attack. We previously showed that inhibition of FH binding by a recombinant FH5-7 construct impairs survival of FH binding pathogens in human blood. In this study we found that upon exposure to full blood, the addition of FH5-7 reduces survival of, surprisingly, also those microbes that are not able to bind FH. This effect was mediated by inhibition of complement regulation and subsequently enhanced neutrophil phagocytosis by FH5-7. We found that although FH5-7 does not reduce complement regulation in the actual fluid phase of plasma, it reduces regulation on HDL particles in plasma. Using affinity chromatography and mass spectrometry we revealed that FH interacts with serum apolipoprotein E (apoE) via FH5-7 domains. Furthermore, binding of FH5-7 to HDL was dependent on the concentration of apoE on the HDL particles. These findings explain why the addition of FH5-7 to plasma leads to excessive complement activation and phagocytosis of microbes in full anticoagulated blood. In conclusion, our data show how FH interacts with apoE molecules via domains 5-7 and regulates alternative pathway activation on plasma HDL particles.

  7. 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.

  8. Apolipoprotein AI tertiary structures determine stability and phospholipid-binding activity of discoidal high-density lipoprotein particles of different sizes

    SciTech Connect

    Chen, Bin; Ren, Xuefeng; Neville, Tracey; Jerome, W. Gray; Hoyt, David W.; Sparks, Daniel L.; Ren, Gang; Wang, Jianjun

    2009-05-18

    Human high-density lipoprotein (HDL) plays a key role in the reverse cholesterol transport pathway that delivers excess cholesterol back to the liver for clearance. In vivo, HDL particles vary in size, shape and biological function. The discoidal HDL is a 140-240 kDa, disk-shaped intermediate of mature HDL. During mature spherical HDL formation, discoidal HDLs play a key role in loading cholesterol ester onto the HDL particles by activating the enzyme, lecithin:cholesterol acyltransferase (LCAT). One of the major problems for high-resolution structural studies of discoidal HDL is the difficulty in obtaining pure and, foremost, homogenous sample. We demonstrate here that the commonly used cholate dialysis method for discoidal HDL preparation usually contains 5-10% lipid-poor apoAI that significantly interferes with the high-resolution structural analysis of discoidal HDL using biophysical methods. Using an ultracentrifugation method, we quickly removed lipid-poor apoAI. We also purified discoidal reconstituted HDL (rHDL) into two pure discoidal HDL species of different sizes that are amendable for high-resolution structural studies. A small rHDL has a diameter of 7.6 nm, and a large rHDL has a diameter of 9.8 nm. We show that these two different sizes of discoidal HDL particles display different stability and phospholipid-binding activity. Interestingly, these property/functional differences are independent from the apoAI -helical secondary structure, but are determined by the tertiary structural difference of apoAI on different discoidal rHDL particles, as evidenced by two-dimensional NMR and negative stain electron microscopy data. Our result further provides the first high-resolution NMR data, demonstrating a promise of structural determination of discoidal HDL at atomic resolution using a combination of NMR and other biophysical techniques.

  9. 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.

  10. Protein Phosphatase 2A (PP2A) Regulates Low Density Lipoprotein Uptake through Regulating Sterol Response Element-binding Protein-2 (SREBP-2) DNA Binding*

    PubMed Central

    Rice, Lyndi M.; Donigan, Melissa; Yang, Muhua; Liu, Weidong; Pandya, Devanshi; Joseph, Biny K.; Sodi, Valerie; Gearhart, Tricia L.; Yip, Jenny; Bouchard, Michael; Nickels, Joseph T.

    2014-01-01

    LDL-cholesterol (LDL-C) uptake by Ldlr is regulated at the transcriptional level by the cleavage-dependent activation of membrane-associated sterol response element-binding protein (SREBP-2). Activated SREBP-2 translocates to the nucleus, where it binds to an LDLR promoter sterol response element (SRE), increasing LDLR gene expression and LDL-C uptake. SREBP-2 cleavage and translocation steps are well established. Several SREBP-2 phosphorylation sites have been mapped and functionally characterized. The phosphatases dephosphorylating these sites remain elusive. The phosphatase(s) regulating SREBP-2 represents a novel pharmacological target for treating hypercholesterolemia. Here we show that protein phosphatase 2A (PP2A) promotes SREBP-2 LDLR promoter binding in response to cholesterol depletion. No binding to an LDLR SRE was observed in the presence of the HMG-CoA reductase inhibitor, lovastatin, when PP2A activity was inhibited by okadaic acid or depleted by siRNA methods. SREBP-2 cleavage and nuclear translocation were not affected by loss of PP2A. PP2A activity was required for SREBP-2 DNA binding. In response to cholesterol depletion, PP2A directly interacted with SREBP-2 and altered its phosphorylation state, causing an increase in SREBP-2 binding to an LDLR SRE site. Increased binding resulted in induced LDLR gene expression and increased LDL uptake. We conclude that PP2A activity regulates cholesterol homeostasis and LDL-C uptake. PMID:24770487

  11. Soluble CD14 acts as a shuttle in the neutralization of lipopolysaccharide (LPS) by LPS-binding protein and reconstituted high density lipoprotein

    PubMed Central

    1995-01-01

    We have recently shown that lipopolysaccharide (LPS)-binding protein (LBP) is a lipid transfer protein that catalyzes two distinct reactions: movement of bacterial LPS (endotoxin) from LPS micelles to soluble CD14 (sCD14) and movement of LPS from micelles to reconstituted high density lipoprotein (R-HDL) particles. Here we show that LBP facilitates a third lipid transfer reaction: movement of LPS from LPS- sCD14 complexes to R-HDL particles. This action of LBP is catalytic, with one molecule of LBP enabling the movement of multiple LPS molecules into R-HDL. LBP-catalyzed movement of LPS from LPS-sCD14 complexes to R-HDL neutralizes the capacity of LPS to stimulate polymorphonuclear leukocytes. Our findings show that LPS may be transferred to R-HDL either by the direct action of LBP or by a two- step reaction in which LPS is first transferred to sCD14 and subsequently to R-HDL. We have observed that the two-step pathway of LPS transfer to R-HDL is strongly favored over direct transfer. Neutralization of LPS by LBP and R-HDL was accelerated more than 30- fold by addition of sCD14. Several observations suggest that sCD14 accelerates this reaction by serving as a shuttle for LPS: addition of LBP and sCD14 to LPS micelles resulted in LPS-sCD14 complexes that could diffuse through a 100-kD cutoff filter; LPS-sCD14 complexes appeared transiently during movement of LPS to R-HDL facilitated by purified LBP; and sCD14 could facilitate transfer of LPS to R-HDL without becoming part of the final LPS-R-HDL complex. Complexes of LPS and sCD14 were formed transiently when LPS was incubated in plasma, suggesting that these complexes may play a role as intermediates in the neutralization of LPS under physiological conditions. These findings detail a new activity for sCD14 and suggest a novel mechanism for lipid transfer by LBP. PMID:7536794

  12. 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.

  13. 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).

  14. 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.

  15. Allotypy of High Density Lipoprotein of Rabbit Serum

    PubMed Central

    Berg, Kåre; Boman, Helge; Torsvik, Harald; Walker, Suzanne M.

    1971-01-01

    A common antigenic polymorphism of high density lipoprotein (HDL) in rabbit serum is described. The presence or absence of an antigen termed Hl 1 appears to be controlled by autosomal dominant inheritance. The polymorphism should be a useful tool in the study of serum lipoproteins, particularly since genetic polymorphisms within the low density lipoprotein are already known in several species. The Hl polymorphism may make the rabbit more useful for model studies of serum lipoproteins in health and disease. Images PMID:4995822

  16. 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...

  17. Regulation of high density lipoprotein levels

    SciTech Connect

    Krauss, R.M.

    1982-03-01

    An increasing awareness of the physiologic and pathologic importance of serum high density lipoproteins (HDL) has led to a large number of observations regarding factors which influence their concentrations. HDL consists of a heterogeneous collection of macromolecules with diverse physical properties and chemical constituents. While laboratory techniques have made it possible to measure HDL and their individual components, there are as yet large gaps in our knowledge of the biochemical mechanisms and clinical significance of changes in these laboratory parameters. In this review, current concepts of the structure and metabolism of HDL will be briefly summarized, and the factors influencing their levels in humans will be surveyed. 313 references.

  18. 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

  19. 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.

  20. 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.

  1. [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.

  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. 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.

  5. 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

  6. 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

  7. High-density lipoprotein cholesterol: current perspective for clinicians.

    PubMed

    Whayne, Thomas F

    2009-01-01

    High-density lipoproteins are regarded as ''good guys'' but not always. Situations involving high-density lipoproteins are discussed and medication results are considered. Clinicians usually consider high-density lipoprotein cholesterol. Nicotinic acid is the best available medication to elevate high-density lipoprotein cholesterol and this appears beneficial for cardiovascular risk. The major problem with nicotinic acid is that many patients do not tolerate the associated flushing. Laropiprant decreases this flushing and has an approval in Europe but not in the United States. The most potent medications for increasing high-density lipoprotein cholesterol are cholesteryl ester transfer protein inhibitors. The initial drug in this class, torcetrapib, was eliminated by excess cardiovascular problems. Two newer cholesteryl ester transfer protein inhibitors, R1658 and anacetrapib, initially appear promising. High-density lipoprotein cholesterol may play an important role in improving cardiovascular risk in the 60% of patients who do not receive cardiovascular mortality/morbidity benefit from low-density lipoproteins reduction by statins.

  8. 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.

  9. 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.

  10. 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.

  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. A proprotein convertase subtilisin-like/kexin type 9 (PCSK9) C-terminal domain antibody antigen-binding fragment inhibits PCSK9 internalization and restores low density lipoprotein uptake.

    PubMed

    Ni, Yan G; Condra, Jon H; Orsatti, Laura; Shen, Xun; Di Marco, Stefania; Pandit, Shilpa; Bottomley, Matthew J; Ruggeri, Lionello; Cummings, Richard T; Cubbon, Rose M; Santoro, Joseph C; Ehrhardt, Anka; Lewis, Dale; Fisher, Timothy S; Ha, Sookhee; Njimoluh, Leila; Wood, Dana D; Hammond, Holly A; Wisniewski, Douglas; Volpari, Cinzia; Noto, Alessia; Lo Surdo, Paola; Hubbard, Brian; Carfí, Andrea; Sitlani, Ayesha

    2010-04-23

    PCSK9 binds to the low density lipoprotein receptor (LDLR) and leads to LDLR degradation and inhibition of plasma LDL cholesterol clearance. Consequently, the role of PCSK9 in modulating circulating LDL makes it a promising therapeutic target for treating hypercholesterolemia and coronary heart disease. Although the C-terminal domain of PCSK9 is not involved in LDLR binding, the location of several naturally occurring mutations within this region suggests that it has an important role for PCSK9 function. Using a phage display library, we identified an anti-PCSK9 Fab (fragment antigen binding), 1G08, with subnanomolar affinity for PCSK9. In an assay measuring LDL uptake in HEK293 and HepG2 cells, 1G08 Fab reduced 50% the PCSK9-dependent inhibitory effects on LDL uptake. Importantly, we found that 1G08 did not affect the PCSK9-LDLR interaction but inhibited the internalization of PCSK9 in these cells. Furthermore, proteolysis and site-directed mutagenesis studies demonstrated that 1G08 Fab binds a region of beta-strands encompassing Arg-549, Arg-580, Arg-582, Glu-607, Lys-609, and Glu-612 in the PCSK9 C-terminal domain. Consistent with these results, 1G08 fails to bind PCSK9DeltaC, a truncated form of PCSK9 lacking the C-terminal domain. Additional studies revealed that lack of the C-terminal domain compromised the ability of PCSK9 to internalize into cells, and to inhibit LDL uptake. Together, the present study demonstrate that the PCSK9 C-terminal domain contribute to its inhibition of LDLR function mainly through its role in the cellular uptake of PCSK9 and LDLR complex. 1G08 Fab represents a useful new tool for delineating the mechanism of PCSK9 uptake and LDLR degradation.

  13. The effect of endurance training on the relationships between sex hormone binding globulin, high density lipoprotein cholesterol, apoprotein A1 and physical fitness in pre-menopausal women with mild obesity.

    PubMed

    Kumagai, S; Shono, N; Kondo, Y; Nishizumi, M

    1994-04-01

    The purpose of the present study was to investigate the relationships of change in high density lipoprotein cholesterol (HDL-C) with changes in sex hormone binding globulin (SHBG), physical fitness and spontaneous dietary intake before and after endurance training. Ten pre-menopausal obese women (32 to 49 years) who had never smoked or regularly drunk alcohol participated in this study. Physical training at an intensity of lactate threshold was performed for six months at a frequency of three times per week for 60 minutes using a cycle ergometer. Together with a reduction in body weight (-4.1 kg; P < 0.05) and with increases in maximal oxygen uptake (VO2max = +3.4 ml/kg/min or +0.09 l/min; P < 0.05), the training induced some changes in both plasma lipid and lipoprotein. Although the total cholesterol (total-C), triglyceride, HDL2-C and apoprotein A1 (Apo A1) levels did not change, significant increases in HDL-C and HDL3-C, and significant reductions in Apo B, total-C/HDL-C ratio and fasting insulin concentrations were found after training. SHBG levels tended to increase after endurance training, but the changes were not significant. No alteration was observed in spontaneous dietary intake after training. A significant correlation (r = 0.648) was observed between the change in VO2 max(l/min) and the change in SHBG. In addition, changes in both VO2 max(l/min) and SHBG were significantly associated with changes in HDL-C, HDL2-C and Apo A1. The changes in dietary intake did not correlate with the changes in SHBG, VO2max, HDL-C, HDL2-C and Apo A1.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Biominetic High Density Lipoproteins for the Delivery of Therapeutic Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Tripathy, Sushant

    Advances in nanotechnology have brought about novel inorganic and hybrid nanoparticles with unique physico-chemical properties that make them suitable for a broad range of applications---from nano-circuitry to drug delivery. A significant part of those advancements have led to ground-breaking discoveries that have changed the approaches to formulation of therapeutics against diseases, such as cancer. Now-a-days the focus does not lie solely on finding a candidate small-molecule therapeutic with minimal adverse effects, but researchers are looking up to nanoparticles to improve biodistribution and biocompatibility profile of clinically proven therapeutics. The plethora of conjugation chemistries offered by currently extant inorganic nanoparticles have, in recent years, led to great leaps in the field of biomimicry---a modality that promises high biocompatibility. Further, in the pursuit of highly specific therapeutic molecules, researchers have turned to silencing oligonucleotides and some have already brought together the strengths of nanoparticles and silencing oligonucleotides in search of an efficacious therapy for cancer with minimal adverse effects. This dissertation work focuses on such a biomimetic platform---a gold nanoparticle based high density lipoprotein biomimetic (HDL NP), for the delivery of therapeutic oligonucleotides. The first chapter of this body of work introduces the molecular target of the silencing oligonucleotides---VEGFR2, and its role in the progression of solid tumor cancers. The background information also covers important aspects of natural high density lipoproteins (HDL), especially their innate capacity to bind and deliver exogenous and endogenous silencing oligonucleotides to tissues that express their high affinity receptor SRB1. We subsequently describe the synthesis of the biomimetic HDL NP and its oligonucleotide conjugates, and establish their biocompatibility. Further on, experimental data demonstrate the efficacy of silencing

  15. 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.

  16. Ganglioside embedded in reconstituted lipoprotein binds cholera toxin with elevated affinity.

    PubMed

    Bricarello, Daniel A; Mills, Emily J; Petrlova, Jitka; Voss, John C; Parikh, Atul N

    2010-09-01

    The ability to exogenously present cell-surface receptors in high-affinity conformations in a synthetic system offers an opportunity to provide host cells with protection from pathogenic toxins. This strategy requires improvement of the synthetic receptor binding affinity against its native counterpart, particularly with polyvalent toxins where clustering of membrane receptors can hinder binding. Here we demonstrate that reconstituted lipoprotein, nanometer-sized discoidal lipid bilayers bounded by apolipoprotein and functionalized by incorporation of pathogen receptors, provides a means to enhance toxin-receptor binding through molecular-level control over the receptor microenvironment (specifically, its rigidity, composition, and heterogeneity). Using a Foerster Resonance Energy Transfer (FRET)-based assay, we found that reconstituted lipoprotein incorporating low concentrations of ganglioside monosialotetrahexosylganglioside (GM1) binds polymeric cholera toxin with significantly higher affinity than liposomes or supported lipid bilayers, most likely a result of the enhanced control over receptor clustering provided by the lipoprotein platform. Using wide-area epifluorescence, we found that this enhanced binding capacity can be effectively utilized to divert cholera toxin away from populations of healthy mammalian cells. In summary, we found that reconstitutions of high-density lipoprotein can be engineered to include specific pathogen receptors; that their pathogen binding affinity is altered, presumably due to attenuation of receptor aggregation; and that these assemblies are effective at protecting cells from biological toxins.

  17. [Intermediate-density lipoproteins and liver lipase in postmenopausal women].

    PubMed

    Halperin, H; Berg, G; Aisemberg, L; Brites, F; Siseles, N; Wikinski, R

    1992-01-01

    In order to evaluate atherogenic lipoproteins in post-menopause, we studied 73 healthy women, 49 to 65 years old (Post-menopausal Group), with 1 to 10 years of amenorrhea and body mass index below 27 Kg/m2, and 20 young women (Control Group). We have determined plasma cholesterol concentration in the lipoproteins of intermediate density in addition to the classical lipoprotein parameters: total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides and fractionation of lipoproteins by electrophoresis. In 63 women from the Post-menopausal Group and 16 from the Control Group we studied the activity of hepatic lipase. Among these patients we selected at random 25 post-menopausal women and 13 controls to add measurements of triglycerides in the lipoproteins of intermediate density. Table 1 shows that the average plasma concentration of total cholesterol in the Post-menopausal Group was higher than that of the Controls (p < 0.001). The same was found for LDL-cholesterol (p < 0.001) and for triglycerides (p < 0.001) whereas the average concentration of HDL-cholesterol did not show significant differences. The Post-menopausal Group had high values of plasma lipoproteins of intermediate density, even with normal phenotypes (Table 2). Cholesterol but also triglycerides (Fig. 1) were responsible for this increase. A triglyceride rich lipoprotein subspecies of intermediate density was predominant in 73% of Post-menopausal women vs 23% of the Controls (p < 0.01, Table 3). No differences in hepatic lipase activity were seen between the two groups (Table 4), and non statistic correlation between the enzyme activity and IDL-triglycerides or HDL-cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Emerging strategies for increasing high-density lipoprotein.

    PubMed

    Forrester, James S; Shah, Prediman K

    2006-12-01

    High-density lipoprotein cholesterol is a potent and independent epidemiologic risk factor and is a proved antiatherosclerotic agent in animal models of atherosclerosis, acting through the principal mechanisms of accelerating cholesterol efflux and inhibiting oxidation and inflammation. Lifestyle modification increases serum levels by 5% to 15%, whereas niacin, the drug most widely used to increase high-density lipoprotein cholesterol, increases it by 25% to 35% at the highest doses. This review examines the potent methods of increasing high-density lipoprotein and/or enhancing reverse cholesterol transport, including cholesterol ester transfer protein inhibitors, apolipoprotein A-I Milano, D4F, the dual peroxisome proliferator-activated receptor agonists, and rimonabant, that are now in clinical trials. In conclusion, these new agents, used alone or in combination with existing therapies, carry the potential to markedly reduce the incidence of new coronary disease and cardiac events in this decade.

  19. 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.

  20. 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.

  1. 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

  2. Membrane binding sites for plasma lipoproteins on endosomes from rat liver.

    PubMed Central

    Jaeckle, S; Brady, S E; Havel, R J

    1989-01-01

    Highly purified endosomal membranes from rat liver, enriched in receptors for a number of macromolecules taken up into hepatocytes via the coated pit/endosome/lysosome pathway [including the receptor for low density lipoproteins (LDL)], were used to characterize binding sites for lipoproteins containing apolipoprotein E. In endosomal membranes from livers of estradiol-treated rats, in which LDL receptors are induced manyfold, two high-affinity binding sites were found for two apolipoprotein E-rich lipoproteins: very low density beta-lipoproteins (beta-VLDL) from cholesterol-fed rabbits and rat chylomicron remnants. One of these sites, binding to which is inhibited by 30 mM EDTA, appears identical to the LDL receptor by ligand and immunoblotting and other characteristics. The other site, highly resistant to EDTA, does not bind LDL. Binding to the EDTA-resistant site, however, is readily inhibited by heparin (as is the LDL receptor) and also by antisera prepared against rat or bovine LDL receptor. The distribution of the EDTA-resistant site among early endosomes, late endosomes, and endosome-derived receptor-recycling membranes is similar to that of the LDL receptor and other recycling receptors. The LDL receptor was present in endosomal membranes from livers of untreated rats at about 10% of the level found in membranes from estradiol-treated rats, but the EDTA-resistant site was barely detectable. No saturable binding of beta-VLDL that could not be inhibited by antisera to the LDL receptor could be detected in endosomal membranes from livers of either untreated or estradiol-treated rats. The EDTA-resistant site may be a modified form of the LDL receptor that recognizes apolipoprotein E but not the B apolipoprotein of LDL. Alternatively, it may be a distinct receptor sharing immunological determinants with the LDL receptor, specialized for the endocytosis of certain lipoproteins containing apolipoprotein E, including chylomicron remnants. Images PMID:2538819

  3. 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.

  4. Characterization of chick serum lipoproteins isolated by density gradient ultracentrifugation.

    PubMed

    Rodriguez-Vico, F; Lopez, J M; Castillo, M; Zafra, M F; Garcia-Peregrin, E

    1992-01-01

    Serum lipoproteins from 12h fasted male chicks (15-day-old) were separated into 20 fractions by isopycnic density gradient ultracentrifugation. A new procedure was described by collecting the different fractions from the bottom of tube instead of by aspiration from the meniscus of each tube. Analyses of chemical composition of serum lipoproteins have permitted to reevaluate the density limits of major classes: VHDL, d greater than 1.132 g/ml; HDL, d 1.132-1.084 g/ml; LDL, d 1.084-1.038; IDL, d 1.038-1.022; and VLDL d less than 1.022. HDL fractions clearly predominated (approx. 77% of total lipoproteins) while IDL and VLDL were present at low percentage. LDL was the fraction richest in cholesterol; triacylglycerol content clearly increased from HDL to VLDL, while protein content decreased. All the chemical components of chick serum lipoproteins were accumulated in HDL, although triacylglycerol was relatively distributed in all the lipoprotein classes.

  5. Effect of drugs on high-density lipoprotein.

    PubMed

    McKenney, James M

    2007-03-01

    The National Cholesterol Education Program Adult Treatment Panel III found evidence for raising high-density lipoprotein cholesterol (HDL-C) to reduce coronary artery disease (CAD) events supports use of HDL-C to help modify low-density lipoprotein cholesterol (LDL-C)-lowering goals, but not to establish new HDL-C-focused treatment recommendations. However, the HDL-C-raising clinical trials provide important lessons to help guide clinical management of dyslipidemic patients. The fibrate outcome trials demonstrate that these drugs reduce CAD events, but not death. Their greatest benefit is in patients with atherogenic dyslipidemia characterized by high triglycerides, small LDL particles, and low HDL-C. Unfortunately, there is no information on whether these drugs extend risk reduction when added to a statin. The niacin outcome trials also demonstrate a reduction in CAD events, both with niacin monotherapy and in combination with a statin. Unfortunately, most of the trials are too small to address the impact of niacin on mortality. In the clinic, statins are most useful for their LDL-C-lowering efficacy, although their modest HDL-C-raising effects can be important in CAD risk reduction. In most cases, other therapies will need to be added to a statin to augment HDL-C-raising, and the most effective drug for achieving this is niacin. The greatest challenge with the use of niacin is managing the vasodilatory side effects, but this can be effectively done in the majority of patients. Fibrates can also be added to a statin for management of atherogenic dyslipidemia. These drugs are among the most effective triglyceride-lowering drugs, and they also increase HDL-C levels, but not as much as niacin. The biggest concern with combining a fibrate with a statin is the enhanced risk of severe muscle toxicity, but this appears to be a problem unique to gemfibrozil, and not fenofibrate. In the research center, new approaches are under development for enhancing the availability of

  6. Structural Stability and Functional Remodeling of High-Density Lipoproteins

    PubMed Central

    Gursky, Olga

    2015-01-01

    Lipoproteins are protein-lipid nanoparticles that transport lipids in circulation and are central in atherosclerosis and other disorders of lipid metabolism. Apolipoproteins form flexible structural scaffolds and important functional ligands on the particle surface and direct lipoprotein metabolism. Lipoproteins undergo multiple rounds of metabolic remodeling that is crucial to lipid transport. Important aspects of this remodeling, including apolipoprotein dissociation and particle fusion, are mimicked in thermal or chemical denaturation and are modulated by free energy barriers. Here we review our biophysical studies that revealed kinetic mechanism of lipoprotein stabilization and unraveled its structural basis. The main focus is on high-density lipoprotein (HDL). An inverse correlation between stability and functions of various HDLs in cholesterol transport suggests functional role of structural disorder. A mechanism for conformational adaptation of the major HDL proteins, apoA-I and apoA-II, to the increasing lipid load is proposed. Together, these studies help understand why HDL form discrete subclasses separated by kinetic barriers, which have distinct composition, conformation and functional properties. Understanding these properties may help improve HDL quality and develop novel therapies for cardiovascular disease. PMID:25749369

  7. [Residual risk: The roles of triglycerides and high density lipoproteins].

    PubMed

    Grammer, Tanja; Kleber, Marcus; Silbernagel, Günther; Scharnagl, Hubert; März, Winfried

    2016-06-01

    In clinical trials, the reduction of LDL-cholesterol (LDL-C) with statins reduces the incidence rate of cardiovascular events by approximately one third. This means, that a sizeable "residual risk" remains. Besides high lipoprotein (a), disorders in the metabolism of triglyceride-rich lipoproteins and high density liproteins have been implicated as effectors of the residual risk. Both lipoprotein parameters correlate inversely with each other. Therefore, the etiological contributions of triglycerides and / or of HDL for developing cardiovascular disease can hardly be estimated from either observational studies or from intervention studies. The largely disappointing results of intervention studies with inhibitors of the cholesteryl ester transfer protein and in particular the available set of genetically-epidemiological studies suggest that in the last decade, the importance of HDL cholesterol has been overvalued, while the importance of triglycerides has been underestimated. High triglycerides not always atherogenic, but only if they are associated with the accumulation relatively cholesterol-enriched, incompletely catabolized remnants of chylomicrons and very low density lipoproteins (familial type III hyperlipidemia, metabolic syndrome, diabetes mellitus). The normalization of the concentration of triglycerides and remnants by inhibiting the expression of apolipoprotein C3 is hence a new, promising therapeutic target.

  8. [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

  9. 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

  10. Relation Between Cigarette Smoking, Body Fat Distribution and Density of Lipoprotein Cholesterol in Women.

    DTIC Science & Technology

    1992-08-01

    Cholesterol in Women Linda R. Beson, Major AFIT Student Attending: University of Florida AFIT/CI/CIA-92-085 DTIC Wright-Patterson AFB OH 45433-6583 ELECTE 1...CIGARETTE SMOKING, BODY FAT DISTRIBUTION AND DENSITY OF LIPOPROTEIN CHOLESTEROL IN WOMEN By W: , LINDA R. BESON " Di t A THESIS PRESENTED TO THE GRADUATE...12 Cholesterol and Serum Lipoproteins ......... .. 14 Low Density Lipoprotein (LDL) Cholesterol . . . 18 High Density Lipoprotein (HDL

  11. Purification of very high density lipoproteins by differential density gradient ultracentrifugation.

    PubMed

    Haunerland, N H; Ryan, R O; Law, J H; Bowers, W S

    1987-03-01

    Differential density gradient ultracentrifugation procedures, utilizing a vertical rotor, were developed for the preparative purification of very high density lipoproteins (VHDL, density greater than 1.21 g/ml). The VHDLs of several insect species were purified as follows. An initial density gradient ultracentrifugation step removed lipoproteins of lower density from the VHDL-fraction, which partially separated from the nonlipoproteins present in the infranatant. A complete separation was achieved by a second centrifugation step employing a modified gradient system. The use of a vertical rotor and specially designed discontinuous gradients allows a relatively fast, efficient, and economical isolation of the class of very high density lipoproteins. Similar gradient systems should be useful for the detection and purification of VHDLs from other sources.

  12. SR-BI mediates high density lipoprotein (HDL)-induced anti-inflammatory effect in macrophages.

    PubMed

    Song, Gyun Jee; Kim, Seong-Min; Park, Ki-Hoon; Kim, Jihoe; Choi, Inho; Cho, Kyung-Hyun

    2015-01-30

    High density lipoprotein (HDL) receptor, scavenger receptor class B, type I (SR-BI), mediates selective cholesteryl ester uptake from lipoproteins into the liver as well as cholesterol efflux from macrophages to HDL. Recently, strong evidence has demonstrated the anti-inflammatory effect of HDL, although the mechanism of action is not fully understood. In this study, we showed that the anti-inflammatory effects of HDL are dependent on SR-BI expression in THP-1 macrophages. Consistent with earlier findings, pretreatment of macrophages with HDL abolished LPS-induced TNFα production. HDL also inhibited LPS-induced NF-κB activation. In addition, knockdown of SR-BI or inhibition of SR-BI ligand binding abolished the anti-inflammatory effect of HDL. SR-BI is a multi-ligand receptor that binds to modified lipoproteins as well as native HDL. Since modified lipoproteins have pro-inflammatory properties, it is unclear whether SR-BI activated by modified HDL has an anti- or pro-inflammatory effect. Glycated HDL induced NF-κB activation and cytokine production in macrophages in vitro, suggesting a pro-inflammatory effect for modified HDL. Moreover, inhibition of SR-BI function or expression potentiated glycated HDL-induced TNF-α production, suggesting an anti-inflammatory effect for SR-BI. In conclusion, SR-BI plays an important function in regulating HDL-mediated anti-inflammatory response in macrophages.

  13. MCP-1 binds to oxidized LDL and is carried by lipoprotein(a) in human plasma

    PubMed Central

    Wiesner, Philipp; Tafelmeier, Maria; Chittka, Dominik; Choi, Soo-Ho; Zhang, Li; Byun, Young Sup; Almazan, Felicidad; Yang, Xiaohong; Iqbal, Navaid; Chowdhury, Punam; Maisel, Alan; Witztum, Joseph L.; Handel, Tracy M.; Tsimikas, Sotirios; Miller, Yury I.

    2013-01-01

    Lipoprotein oxidation plays an important role in pathogenesis of atherosclerosis. Oxidized low density lipoprotein (OxLDL) induces profound inflammatory responses in vascular cells, such as production of monocyte chemoattractant protein-1 (MCP-1) [chemokine (C-C motif) ligand 2], a key chemokine in the initiation and progression of vascular inflammation. Here we demonstrate that OxLDL also binds MCP-1 and that the OxLDL-bound MCP-1 retains its ability to recruit monocytes. A human MCP-1 mutant in which basic amino acids Arg-18 and Lys-19 were replaced with Ala did not bind to OxLDL. The MCP-1 binding to OxLDL was inhibited by the monoclonal antibody E06, which binds oxidized phospholipids (OxPLs) in OxLDL. Because OxPLs are carried by lipoprotein(a) [Lp(a)] in human plasma, we tested to determine whether Lp(a) binds MCP-1. Recombinant wild-type but not mutant MCP-1 added to human plasma bound to Lp(a), and its binding was inhibited by E06. Lp(a) captured from human plasma contained MCP-1 and the Lp(a)-associated endogenous MCP-1 induced monocyte migration. These results demonstrate that OxLDL and Lp(a) bind MCP-1 in vitro and in vivo and that OxPLs are major determinants of the MCP-1 binding. The association of MCP-1 with OxLDL and Lp(a) may play a role in modulating monocyte trafficking during atherogenesis. PMID:23667177

  14. 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.

  15. Biomimetic high density lipoprotein nanoparticles for nucleic acid delivery.

    PubMed

    McMahon, Kaylin M; Mutharasan, R Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K; Luthi, Andrea J; Helfand, Brian T; Ardehali, Hossein; Mirkin, Chad A; Volpert, Olga; Thaxton, C Shad

    2011-03-09

    We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy that combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy, and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery.

  16. 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...

  17. High-density lipoprotein-raising strategies: update 2010.

    PubMed

    Spillmann, Frank; Schultheiss, Heinz-Peter; Tschöpe, Carsten; Van Linthout, Sophie

    2010-05-01

    Population studies have consistently shown that high-density lipoprotein (HDL) cholesterol levels are a strong, independent inverse predictor of cardiovascular disease. Every 1 mg/dl increase in HDL cholesterol is associated with a 2% to 3% decrease in coronary artery disease risk, independent of low-density lipoprotein (LDL) cholesterol and triglyceride levels. The primary mechanism for this protective effect is believed to be reverse cholesterol transport, but several other anti-inflammatory, anti-apoptotic, anti-oxidative functions for HDL have also been identified. Low HDL cholesterol is predictive of cardiovascular events in statin-treated patients with low LDL cholesterol, indicating that intensive lipid lowering strategies with statins alone are not sufficient to prevent cardiovascular events, and merging for additional effective HDL-raising therapy. This review focuses at giving an overview of current established HDL-raising pharmaca, including statins, fibrates, thiazolidinediones, and nicotinic acids, and of novel therapies including cholesterol ester transfer protein-inhibitors, liver X receptor agonists, reconstituted HDL, and apolipoprotein A-I mimetics. Working mechanisms are described and results from clinical trials of monotherapy and combination therapy are discussed.

  18. An evaluation of serum high density lipoproteins-phospholipids.

    PubMed

    Ide, H; Tsuji, M; Shimada, M; Kondo, T; Fujiya, S; Asanuma, Y; Agishi, Y

    1988-07-01

    Phospholipids in high density lipoproteins (HDL) is being used as a negative risk indicator of atherosclerosis. Phospholipids in HDL may not demonstrate the actual level of HDL-phospholipids when determined by the precipitation or ultracentrifugal methods, because HDL fractions contain very high density lipoproteins (VHDL) and albumin. In the present study, the true level of phospholipids in HDL was estimated using high performance liquid chromatography (HPLC), and it was compared with the level of phospholipids in HDL determined by the precipitation method. Sera from 18 healthy subjects were used as materials. In the HPLC method, the HDL fraction was extracted making sure that it contained no free albumin, which is albumin not bound to phospholipids. The HDL fraction was separated into subfractions. It was found that phospholipids in the VHDL fraction make a 20.2 +/- 7.3% (mean +/- S.D.) part of the total HDL-phospholipids. A large part of the VHDL fraction was constituted of albumin-bound phospholipids. A significant correlation was observed between HDL-phospholipids determined by the precipitation method, which contain albumin, and the actual HDL fraction phospholipids determined by HPLC, which do not contain VHDL (r = 0.903, p less than 0.01). These results suggest that HDL-phospholipids values determined by the precipitation method give useful clinical data.

  19. Relative atherogenicity and predictive value of non-high-density lipoprotein cholesterol for coronary heart disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although low-density lipoprotein cholesterol (LDL-C) is a well-established atherogenic factor for coronary heart disease, it does not completely represent the risk associated with atherogenic lipoproteins in the presence of high triglyceride (TG) levels. Constituent lipoproteins constituting non–hig...

  20. High-Density Lipoprotein, Lecithin: Cholesterol Acyltransferase, and Atherosclerosis

    PubMed Central

    Ossoli, Alice; Pavanello, Chiara

    2016-01-01

    Epidemiological data clearly show the existence of a strong inverse correlation between plasma high-density lipoprotein cholesterol (HDL-C) concentrations and the incidence of coronary heart disease. This relation is explained by a number of atheroprotective properties of HDL, first of all the ability to promote macrophage cholesterol transport. HDL are highly heterogeneous and are continuously remodeled in plasma thanks to the action of a number of proteins and enzymes. Among them, lecithin:cholesterol acyltransferase (LCAT) plays a crucial role, being the only enzyme able to esterify cholesterol within lipoproteins. LCAT is synthetized by the liver and it has been thought to play a major role in reverse cholesterol transport and in atheroprotection. However, data from animal studies, as well as human studies, have shown contradictory results. Increased LCAT concentrations are associated with increased HDL-C levels but not necessarily with atheroprotection. On the other side, decreased LCAT concentration and activity are associated with decreased HDL-C levels but not with increased atherosclerosis. These contradictory results confirm that HDL-C levels per se do not represent the functionality of the HDL system. PMID:27302716

  1. 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.

  2. Isolation of high density lipoproteins from rat intestinal epithelial cells.

    PubMed Central

    Magun, A M; Brasitus, T A; Glickman, R M

    1985-01-01

    Previous studies have defined forms of high density lipoproteins (HDL) in rat mesenteric lymph, suggesting that they have a secretory origin. This study describes the isolation and characterization of intestinal intracellular HDL. Two preparations were made as follows: (a) Rat enterocytes were isolated and a Golgi organelle fraction was prepared. (b) Cell homogenates were subjected to nitrogen cavitation and a cytoplasmic fraction was prepared. Lipoproteins were isolated from both preparations by sequential ultracentrifugation. When the HDL fraction (1.07-1.21 g/ml) was subjected to isopyknic density gradient ultracentrifugation, a peak of apoproteins A-I and B (apoA-I and apoB, respectively) was found at a density of 1.11-1.14 g/ml. Electron microscopy of the fraction showed spherical particles ranging in size from 6 to 13 nm. Immunoelectrophoresis revealed a precipitin arc in the alpha region against apoA-I which extended into the pre-beta region where a precipitin arc against apoB was also seen. ApoB antisera depleted the pre-beta particles whereas the alpha migrating particles remained. Lipid analysis of the whole HDL fraction revealed phospholipid, cholesteryl ester, and triglyceride as the major lipids. [3H]leucine was then administered into the duodenum and a radiolabeled intracellular HDL fraction was isolated. The newly synthesized apoproteins of the HDL fraction, as determined by gel electrophoresis, were apoB, apoA-I, and apolipoprotein A-IV (ApoA-IV). Immunoprecipitation of the apoB particles revealed apoA-I and apoA-IV in the supernatant. These data demonstrate that there are at least two intracellular intestinal forms of HDL particles, one of which contains apoB. The other particle contains apoA-I and apoA-IV, has alpha mobility, is spherical, and resembles a particle found in the lymph. Images PMID:3965504

  3. 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.

  4. 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.

  5. LDL receptor/lipoprotein recognition: endosomal weakening of ApoB and ApoE binding to the convex face of the LR5 repeat.

    PubMed

    Martínez-Oliván, Juan; Arias-Moreno, Xabier; Velazquez-Campoy, Adrián; Millet, Oscar; Sancho, Javier

    2014-03-01

    The molecular mechanism of lipoprotein binding by the low-density lipoprotein (LDL) receptor (LDLR) is poorly understood, one reason being that structures of lipoprotein-receptor complexes are not available. LDLR uses calcium-binding repeats (LRs) to interact with apolipoprotein B and apolipoprotein E (ApoB and ApoE). We have used NMR and SPR to characterize the complexes formed by LR5 and three peptides encompassing the putative binding regions of ApoB (site A and site B) and ApoE. The three peptides bind at the hydrophilic convex face of LR5, forming complexes that are weakened at low [Ca(2+) ] and low pH. Thus, endosomal conditions favour dissociation of LDLR/lipoprotein complexes regardless of whether active displacement of bound lipoproteins by the β-propeller in LDLR takes place. The multiple ApoE copies in β very low density lipoproteins (β-VLDLs), and the presence of two competent binding sites (A and B) in LDLs, suggest that LDLR chelates lipoproteins and enhances complex affinity by using more than one LR.

  6. Can phosphatidylserine enhance atheroprotective activities of high-density lipoprotein?

    PubMed

    Darabi, Maryam; Kontush, Anatol

    2016-01-01

    Although high-density lipoprotein (HDL) is well known to be protective against atherosclerotic cardiovascular disease, therapeutic interventions to raise HDL-cholesterol levels do not translate into reduction in cardiovascular risk. Due to the compositional complexity of HDL particles, molecular determinants of their atheroprotective function still remain to be clarified. Recent structural and functional data identify phospholipid as a major bioactive component of HDL. Such a role has recently been specifically evidenced for phosphatidylserine (PS); indeed, HDL content of PS displayed positive correlations with all metrics of HDL functionality assessed. This review summarizes current knowledge about HDL-associated PS; possible mechanisms for its atheroprotective role are discussed and potential applications of PS to HDL-based therapies are highlighted.

  7. High-Density Lipoprotein and Prostate Cancer: An Overview

    PubMed Central

    Kotani, Kazuhiko; Sekine, Yoshitaka; Ishikawa, Shizukiyo; Ikpot, Imoh Z.; Suzuki, Kazuhiro; Remaley, Alan T.

    2013-01-01

    Prostate cancer is a common disease in modern, developed societies and has a high incidence and mortality. High-density lipoprotein cholesterol (HDL-C) has recently received much attention as a possible risk marker of prostate cancer development and prognosis. In the present article, we summarized findings from epidemiologic studies of the association between HDL-C and prostate cancer. Low HDL-C level was found to be a risk and prognostic factor of prostate cancer in several epidemiologic studies, although the overall linkage between HDL and prostate cancer has not been definitively established. The mechanisms for this association remain uncertain; however, limited data from experimental studies imply a possible role of HDL in the pathophysiology of prostate cancer. More epidemiologic research, in combination with experimental studies, is needed in this field. PMID:23985823

  8. Distribution of High-Density Lipoprotein Subfractions and Hypertensive Status

    PubMed Central

    Zhang, Yan; Li, Sha; Xu, Rui-Xia; Guo, Yuan-Lin; Wu, Na-Qiong; Zhu, Cheng-Gang; Gao, Ying; Dong, Qian; Liu, Geng; Sun, Jing; Li, Jian-Jun

    2015-01-01

    Abstract The exact mechanisms of hypertension contributing to atherosclerosis have not been fully elucidated. Although multiple studies have clarified the association with low-density lipoprotein (LDL) subfractions, uncertainty remains about its relationship with high-density lipoprotein (HDL) subfractions. Therefore, we aimed to comprehensively determine the relationship between distribution of HDL subfractions and hypertensive status. A total of 953 consecutive subjects without previous lipid-lowering drug treatment were enrolled and were categorized based on hypertension history (with hypertension [n = 550] or without hypertension [n = 403]). Baseline clinical and laboratory data were collected. HDL separation was performed using the Lipoprint System. Plasma large HDL-cholesterol (HDL-C) and large HDL percentage were dramatically lower whereas the small HDL-C and small HDL percentage were higher in patients with hypertension (all P < 0.05). The antihypertensive drug therapy was not associated with large or small HDL subfractions (on treatment vs not on treatment, P > 0.05; combination vs single drug therapy, P > 0.05). However, the blood pressure well-controlled patients have significantly lower small HDL subfraction (P < 0.05). Moreover, large HDL-C and percentage were inversely whereas small HDL percentage was positively associated with incident hypertension after adjusting potential confounders (all P < 0.05). In the multivariate model conducted in patients with and without hypertension separately, the cardio-protective value of large HDL-C was disappeared in patients with hypertension (OR 95%CI: 1.011 [0.974–1.049]). The distribution of HDL subfractions is closely associated with hypertensive status and hypertension may potentially impact the cardio-protective value of large HDL subfraction. PMID:26512616

  9. Effects of high-density lipoproteins on storage at 4 degrees C of fowl spermatozoa.

    PubMed

    Blesbois, E; Hermier, D

    1990-11-01

    Qualitative and quantitative characterization of lipoproteins found in seminal plasma from domestic cocks was performed after isolation by density gradient ultracentrifugation. Trigyceride-rich lipoproteins (very low, intermediate- and low density lipoproteins) were not detectable in seminal plasma. High-density lipoproteins (HDL), identified on the basis of size, chemical composition and protein moiety, were present at a concentration of 66 micrograms/ml. A fraction possibly corresponding to VHDL (very high density lipoproteins, 77% protein, 23% lipid) was also detected but appeared contaminated by a protein-rich opalescent material. Since HDL contains mostly phospholipid and cholesterol, the physiological role of these lipoproteins on the storage of fowl spermatozoa was studied. Replacing seminal plasma with a solution containing chicken HDL at physiological concentration (66 micrograms/ml) had no effect on fertilizing ability of spermatozoa stored at 4 degrees C for 24 h. However, higher concentrations of HDL (560 micrograms/ml) had deleterious effects on spermatozoa stored in vitro.

  10. 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.

  11. 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.

  12. 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.

  13. Effect of obesity on high-density lipoprotein metabolism.

    PubMed

    Rashid, Shirya; Genest, Jacques

    2007-12-01

    Reduced levels of high-density lipoproteins (HDL) in non-obese and obese states are associated with increased risk for the development of coronary artery disease. Therefore, it is imperative to determine the mechanisms responsible for reduced HDL in obese states and, conversely, to examine therapies aimed at increasing HDL levels in these individuals. This paper examines the multiple causes for reduced HDL in obese states and the effect of exercise and diet--two non-pharmacologic therapies--on HDL metabolism in humans. In general, the concentration of HDL-cholesterol is adversely altered in obesity, with HDL-cholesterol levels associated with both the degree and distribution of obesity. More specifically, intra-abdominal visceral fat deposition is an important negative correlate of HDL-cholesterol. The specific subfractions of HDL that are altered in obese states include the HDL2, apolipoprotein A-I, and pre-beta1 subfractions. Decreased HDL levels in obesity have been attributed to both an enhancement in the uptake of HDL2 by adipocytes and an increase in the catabolism of apolipoprotein A-I on HDL particles. In addition, there is a decrease in the conversion of the pre-beta1 subfraction, the initial acceptor of cholesterol from peripheral cells, to pre-beta2 particles. Conversely, as a means of reversing the decrease in HDL levels in obesity, sustained weight loss is an effective method. More specifically, weight loss achieved through exercise is more effective at raising HDL levels than dieting. Exercise mediates positive effects on HDL levels at least partly through changes in enzymes of HDL metabolism. Increased lipid transfer to HDL by lipoprotein lipase and reduced HDL clearance by hepatic triglyceride lipase as a result of endurance training are two important mechanisms for increases in HDL observed from exercise.

  14. Proprotein convertases in high-density lipoprotein metabolism.

    PubMed

    Choi, Seungbum; Korstanje, Ron

    2013-09-18

    The proprotein convertase subtilisin/kexins (PCSKs) are a serine endopeptidase family. PCSK members cleave amino acid residues and modulate the activity of precursor proteins. Evidence from patients and animal models carrying genetic alterations in PCSK members show that PCSK members are involved in various metabolic processes. These studies further revealed the molecular mechanism by which genetic alteration of some PCSK members impairs normal molecular and physiological functions, which in turn lead to cardiovascular disease. High-density lipoprotein (HDL) is anti-atherogenic as it removes excessive amount of cholesterol from blood and peripheral tissues. Several PCSK members are involved in HDL metabolism. PCSK3, PCSK5, and PCSK6 process two triglyceride lipase family members, endothelial lipase and lipoprotein lipase, which are important for HDL remodeling. Recent studies in our lab found evidence that PCSK1 and PCSK9 are also involved in HDL metabolism. A mouse model carrying an amino acid substitution in PCSK1 showed an increase in serum apolipoprotein A1 (APOA1) level. Another mouse model lacking PCSK9 showed a decrease in APOE-containing HDL. In this review, we summarize the role of the five PCSK members in lipid, glucose, and bile acid (BA) metabolism, each of which can influence HDL metabolism. We propose an integrative model in which PCSK members regulate HDL metabolism through various molecular mechanisms and metabolic processes and genetic variation in some PCSK members may affect the efficiency of reverse cholesterol transport. PCSK members are considered as attractive therapeutic targets. A greater understanding of the molecular and physiological functions of PCSK members will improve therapeutic strategies and drug efficacy for cardiovascular disease where PCSK members play critical role, with fewer adverse effects.

  15. 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)....

  16. Fitness, Heart Disease, and High-Density Lipoproteins: A Look at the Relationships.

    ERIC Educational Resources Information Center

    McCunney, Robert J.

    1987-01-01

    The role of fitness in preventing coronary heart disease is explored. Research on high-density lipoprotein, which has been found to be one of the most critical determinants of risk, is reviewed. The relationship between fitness, high-density lipoprotein, and coronary heart disease is assessed, and clinical implications are spelled out. (MT)

  17. 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

  18. Identification of Critical Paraoxonase 1 Residues Involved in High Density Lipoprotein Interaction*

    PubMed Central

    Gu, Xiaodong; Huang, Ying; Levison, Bruce S.; Gerstenecker, Gary; DiDonato, Anthony J.; Hazen, Leah B.; Lee, Joonsue; Gogonea, Valentin; DiDonato, Joseph A.; Hazen, Stanley L.

    2016-01-01

    Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated protein with atherosclerosis-protective and systemic anti-oxidant functions. We recently showed that PON1, myeloperoxidase, and HDL bind to one another in vivo forming a functional ternary complex (Huang, Y., Wu, Z., Riwanto, M., Gao, S., Levison, B. S., Gu, X., Fu, X., Wagner, M. A., Besler, C., Gerstenecker, G., Zhang, R., Li, X. M., Didonato, A. J., Gogonea, V., Tang, W. H., et al. (2013) J. Clin. Invest. 123, 3815–3828). However, specific residues on PON1 involved in the HDL-PON1 interaction remain unclear. Unambiguous identification of protein residues involved in docking interactions to lipid surfaces poses considerable methodological challenges. Here we describe a new strategy that uses a novel synthetic photoactivatable and click chemistry-taggable phospholipid probe, which, when incorporated into HDL, was used to identify amino acid residues on PON1 that directly interact with the lipoprotein phospholipid surface. Several specific PON1 residues (Leu-9, Tyr-185, and Tyr-293) were identified through covalent cross-links with the lipid probes using affinity isolation coupled to liquid chromatography with on-line tandem mass spectrometry. Based upon the crystal structure for PON1, the identified residues are all localized in relatively close proximity on the surface of PON1, defining a domain that binds to the HDL lipid surface. Site-specific mutagenesis of the identified PON1 residues (Leu-9, Tyr-185, and Tyr-293), coupled with functional studies, reveals their importance in PON1 binding to HDL and both PON1 catalytic activity and stability. Specifically, the residues identified on PON1 provide important structural insights into the PON1-HDL interaction. More generally, the new photoactivatable and affinity-tagged lipid probe developed herein should prove to be a valuable tool for identifying contact sites supporting protein interactions with lipid interfaces such as found on cell membranes

  19. Identification of Critical Paraoxonase 1 Residues Involved in High Density Lipoprotein Interaction.

    PubMed

    Gu, Xiaodong; Huang, Ying; Levison, Bruce S; Gerstenecker, Gary; DiDonato, Anthony J; Hazen, Leah B; Lee, Joonsue; Gogonea, Valentin; DiDonato, Joseph A; Hazen, Stanley L

    2016-01-22

    Paraoxonase 1 (PON1) is a high density lipoprotein (HDL)-associated protein with atherosclerosis-protective and systemic anti-oxidant functions. We recently showed that PON1, myeloperoxidase, and HDL bind to one another in vivo forming a functional ternary complex (Huang, Y., Wu, Z., Riwanto, M., Gao, S., Levison, B. S., Gu, X., Fu, X., Wagner, M. A., Besler, C., Gerstenecker, G., Zhang, R., Li, X. M., Didonato, A. J., Gogonea, V., Tang, W. H., et al. (2013) J. Clin. Invest. 123, 3815-3828). However, specific residues on PON1 involved in the HDL-PON1 interaction remain unclear. Unambiguous identification of protein residues involved in docking interactions to lipid surfaces poses considerable methodological challenges. Here we describe a new strategy that uses a novel synthetic photoactivatable and click chemistry-taggable phospholipid probe, which, when incorporated into HDL, was used to identify amino acid residues on PON1 that directly interact with the lipoprotein phospholipid surface. Several specific PON1 residues (Leu-9, Tyr-185, and Tyr-293) were identified through covalent cross-links with the lipid probes using affinity isolation coupled to liquid chromatography with on-line tandem mass spectrometry. Based upon the crystal structure for PON1, the identified residues are all localized in relatively close proximity on the surface of PON1, defining a domain that binds to the HDL lipid surface. Site-specific mutagenesis of the identified PON1 residues (Leu-9, Tyr-185, and Tyr-293), coupled with functional studies, reveals their importance in PON1 binding to HDL and both PON1 catalytic activity and stability. Specifically, the residues identified on PON1 provide important structural insights into the PON1-HDL interaction. More generally, the new photoactivatable and affinity-tagged lipid probe developed herein should prove to be a valuable tool for identifying contact sites supporting protein interactions with lipid interfaces such as found on cell membranes

  20. Stability of serum high-density lipoprotein-microRNAs for preanalytical conditions.

    PubMed

    Ishikawa, Hiroaki; Yamada, Hiroya; Taromaru, Nao; Kondo, Kanako; Nagura, Ayuri; Yamazaki, Mirai; Ando, Yoshitaka; Munetsuna, Eiji; Suzuki, Koji; Ohashi, Koji; Teradaira, Ryoji

    2017-01-01

    Background Recently, several studies have shown that microRNAs are present in high-density lipoprotein, and high-density lipoprotein-microRNA may be a promising disease biomarker. We investigated the stability of high-density lipoprotein-microRNAs in different storage conditions as this is an important issue for its application to the field of clinical research. Methods microRNAs were extracted from the high-density lipoprotein fraction that was purified from the serum. miR-135 a and miR-223, which are known to be present in high-density lipoprotein, were quantified by quantitative real-time PCR. The influence of preanalytical parameters on the analysis of high-density lipoprotein-miRNAs was examined by the effect of RNase, storage conditions, and freezing and thawing. Results The concentrations of microRNA in high-density lipoprotein were not altered by RNase A treatment (0-100 U/mL). No significant change in these microRNAs was observed after storing serum at room temperature or 4℃ for 0-24 h, and there was a similar result in the cryopreservation for up to two weeks. Also, high-density lipoprotein-microRNAs were stable for, at least, up to five freeze-thaw cycles. Conclusions These results demonstrated that high-density lipoprotein-microRNAs are relatively resistant to various storage conditions. This study provides new and important information on the stability of high-density lipoprotein-microRNAs.

  1. 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).

  2. Iatrogenic severe depression of high-density lipoprotein cholesterol.

    PubMed

    Mymin, D; Dembinski, T; Friesen, M H

    2009-07-01

    The authors present 5 cases of paradoxical depression of high-density lipoprotein (HDL) cholesterol induced by fibrate drugs. In a 24-month review of all cases seen in one physician's practice at the Winnipeg Health Sciences Centre Lipid Clinic, 492 patients made a total of 1187 visits. Sixty-eight of them were given a fibrate drug (14%). Ten patients had HDL cholesterol levels that were less than 0.5 mmol/L (2%), and of these, 5 cases were due to exposure to fenofibrate (1%). These 5 cases comprised 7.4% of the 68 patients who were given any fibrate drug during that period. Mean levels were as follows: HDL cholesterol on fenofibrate 0.27, off fenofibrate 1.0 mmol/L and apo A1 on fenofibrate 0.41, off fenofibrate 1.17 g/L. A literature review revealed documented cases in 37 patients involving fibrates alone or in combination with other drugs known to cause decreased HDL cholesterol levels. In 13 patients, exposure was to fibrate therapy alone; in those exposed to combinations, the effect was clearly attributable to fibrates in 9; in 14, the nonfibrates (mostly rosiglitazone) were the attributable drugs; and in 1, it was impossible to tell. Thus, fibrate therapy should always be suspected as a cause of profoundly depressed HDL cholesterol.

  3. High-density lipoprotein exerts vasculoprotection via endothelial progenitor cells

    PubMed Central

    Petoumenos, Vasileios; Nickenig, Georg; Werner, Nikos

    2009-01-01

    Endothelial progenitor cells (EPC) enhance endothelial cell repair, improve endothelial dysfunction and are a predictor for cardiovascular mortality. High-density lipoprotein (HDL) cholesterol levels inversely correlate with cardiovascular events and have vasculoprotective effects. Here we postulate that HDL influences EPC biology. HDL and EPC were isolated according to standard procedures. Differentiation of mononuclear cells into DiLDL/lectin positive cells was enhanced after HDL treatment compared to vehicle. HDL was able to inhibit apoptosis (TUNEL assay, annexin V staining) while proliferation (BrdU incorporation) of early outgrowth colonies after extended cell cultivation (14 days) was increased. Flow chamber experiments revealed an improved adhesion of HDL pre-incubated EPC on human coronary artery endothelial cells (HCAEC) compared to vehicle while HDL treatment of HCAEC prevented adhesion of inflammatory cells. Flow cytometry demonstrated an up-regulation of β2- and α4-integrins on HDL pre-incubated EPC. Blocking experiments revealed a unique role of β2-integrin in EPC adhesion. Treatment of wild-type mice with recombinant HDL after endothelial denudation resulted in enhanced re-endothelialization compared to vehicle. Finally, in patients with coronary artery disease a correlation between circulating EPC and HDL concentrations was demonstrated. We provide evidence that HDL mediates important vasculoprotective action via the improvement of function of circulating EPC. PMID:18705697

  4. 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.

  5. Synthetic high-density lipoproteins for delivery of 10-hydroxycamptothecin

    PubMed Central

    Yuan, Yue; Wen, Jian; Tang, Jie; Kan, Qiming; Ackermann, Rose; Olsen, Karl; Schwendeman, Anna

    2016-01-01

    The purpose of this study was to develop a novel synthetic high-density lipoprotein (sHDL) nanoparticle delivery system for 10-hydroxycamptothecin (HCPT) for treatment of colon carcinoma. HDL is recognized by scavenger receptor B-I (SR-BI) over-expressed in colon carcinomas 5- to 35-fold relative to the human fibroblasts. The sHDL nanoparticles were composed of apolipoprotein A-I mimic peptide (5A) and contained 0.5%–1.5% (w/w) of HCPT. An optimized HCPT-sHDL formulation exhibited 0.7% HCPT loading with 70% efficiency with an average size of 10–12 nm. Partitioning of HCPT in the sHDL lipid membrane enhanced drug stability in its active lactone form, increased solubilization, and enabled slow release. Cytotoxicity studies in HT29 colon carcinoma cells revealed that the IC50 of HCPT-sHDL was approximately 3-fold lower than that of free HCPT. Pharmacokinetics in rats following intravenous administration showed that the area under the serum concentration-time curve (AUC0−t) and Cmax of HCPT-HDL were 2.7- and 6.5-fold higher relative to the values for the free HCPT, respectively. These results suggest that sHDL-based formulations of hydrophobic drugs are useful for future evaluation in treatment of SR-BI-positive tumors. PMID:27920529

  6. Acrolein impairs the cholesterol transport functions of high density lipoproteins.

    PubMed

    Chadwick, Alexandra C; Holme, Rebecca L; Chen, Yiliang; Thomas, Michael J; Sorci-Thomas, Mary G; Silverstein, Roy L; Pritchard, Kirkwood A; Sahoo, Daisy

    2015-01-01

    High density lipoproteins (HDL) are considered athero-protective, primarily due to their role in reverse cholesterol transport, where they transport cholesterol from peripheral tissues to the liver for excretion. The current study was designed to determine the impact of HDL modification by acrolein, a highly reactive aldehyde found in high abundance in cigarette smoke, on the cholesterol transport functions of HDL. HDL was chemically-modified with acrolein and immunoblot and mass spectrometry analyses confirmed apolipoprotein crosslinking, as well as acrolein adducts on apolipoproteins A-I and A-II. The ability of acrolein-modified HDL (acro-HDL) to serve as an acceptor of free cholesterol (FC) from COS-7 cells transiently expressing SR-BI was significantly decreased. Further, in contrast to native HDL, acro-HDL promotes higher neutral lipid accumulation in murine macrophages as judged by Oil Red O staining. The ability of acro-HDL to mediate efficient selective uptake of HDL-cholesteryl esters (CE) into SR-BI-expressing cells was reduced compared to native HDL. Together, the findings from our studies suggest that acrolein modification of HDL produces a dysfunctional particle that may ultimately promote atherogenesis by impairing functions that are critical in the reverse cholesterol transport pathway.

  7. Bidirectional flux of cholesterol between cells and lipoproteins. Effects of phospholipid depletion of high density lipoprotein

    SciTech Connect

    Johnson, W.J.; Bamberger, M.J.; Latta, R.A.; Rapp, P.E.; Phillips, M.C.; Rothblat, G.H.

    1986-05-05

    The bidirectional surface transfer of free cholesterol (FC) between Fu5AH rat hepatoma cells and human high density lipoprotein (HDL) was studied. Cells and HDL were prelabeled with (4-/sup 14/C)FC and (7-/sup 3/H)FC, respectively. Influx and efflux of FC were measured simultaneously from the appearance of /sup 3/H counts in cells and /sup 14/C counts in medium. Results were analyzed by a computerized procedure which fitted sets of kinetic data to a model assuming that cell and HDL FC populations each formed a single homogeneous pool and that together the pools formed a closed system. This analysis yielded values for the first-order rate constants of FC influx and efflux (ki and ke), from which influx and efflux of FC mass (Fi and Fe) could be calculated. With normal HDL, the uptake and release of FC tracers conformed well to the above-described model; Fi and Fe were approximately equal, suggesting an exchange of FC between cells and HDL. HDL was depleted of phospholipid (PL) by treatment with either phospholipase A2 or heparin-releasable rat hepatic lipase, followed by incubation with bovine serum albumin. PL depletion of HDL had little or no effect on ki, but reduced ke, indicating that PL-deficient HDL is a relatively poor acceptor of cell cholesterol. The reduction in ke resulted in initial Fi greater than Fe and, thus, in net uptake of FC by the cells. This result explained previous results demonstrating net uptake of FC from PL-depleted HDL. In the presence of an inhibitor of acyl coenzyme A:cholesterol acyltransferase, the steady state distribution of FC mass between cells and HDL was accurately predicted by the ratio of rate constants for FC flux. This result provided additional validation for describing FC flux in terms of first-order rate constants and homogeneous cell and HDL FC pools.

  8. 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.

  9. Novel Changes in Discoidal High Density Lipoprotein Morphology: A Molecular Dynamics Study

    PubMed Central

    Catte, Andrea; Patterson, James C.; Jones, Martin K.; Jerome, W. Gray; Bashtovyy, Denys; Su, Zhengchang; Gu, Feifei; Chen, Jianguo; Aliste, Marcela P.; Harvey, Stephen C.; Li, Ling; Weinstein, Gilbert; Segrest, Jere P.

    2006-01-01

    ApoA-I is a uniquely flexible lipid-scavenging protein capable of incorporating phospholipids into stable particles. Here we report molecular dynamics simulations on a series of progressively smaller discoidal high density lipoprotein particles produced by incremental removal of palmitoyloleoylphosphatidylcholine via four different pathways. The starting model contained 160 palmitoyloleoylphosphatidylcholines and a belt of two antiparallel amphipathic helical lipid-associating domains of apolipoprotein (apo) A-I. The results are particularly compelling. After a few nanoseconds of molecular dynamics simulation, independent of the starting particle and method of size reduction, all simulated double belts of the four lipidated apoA-I particles have helical domains that impressively approximate the x-ray crystal structure of lipid-free apoA-I, particularly between residues 88 and 186. These results provide atomic resolution models for two of the particles produced by in vitro reconstitution of nascent high density lipoprotein particles. These particles, measuring 95 Å and 78 Å by nondenaturing gradient gel electrophoresis, correspond in composition and in size/shape (by negative stain electron microscopy) to the simulated particles with molar ratios of 100:2 and 50:2, respectively. The lipids of the 100:2 particle family form minimal surfaces at their monolayer-monolayer interface, whereas the 50:2 particle family displays a lipid pocket capable of binding a dynamic range of phospholipid molecules. PMID:16581834

  10. 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.

  11. High-density lipoprotein cholesterol on a roller coaster: where will the ride end?

    PubMed

    Kronenberg, Florian

    2016-04-01

    Bowe et al. report an association between low high-density lipoprotein cholesterol concentrations and various incident chronic kidney disease end points in a cohort of almost 2 million US veterans followed for 9 years. These impressive data should be a starting point for further investigations including genetic epidemiologic investigations as well as post hoc analyses of interventional trials that target high-density lipoprotein cholesterol and, finally, studies that focus on the functionality of high-density lipoprotein particles.

  12. Biomimetic High-Density Lipoproteins from a Gold Nanoparticle Template

    NASA Astrophysics Data System (ADS)

    Luthi, Andrea Jane

    For hundreds of years the field of chemistry has looked to nature for inspiration and insight to develop novel solutions for the treatment of human diseases. The ability of chemists to identify, mimic, and modifiy small molecules found in nature has led to the discovery and development of many important therapeutics. Chemistry on the nanoscale has made it possible to mimic natural, macromolecular structures that may also be useful for understanding and treating diseases. One example of such a structure is high-density lipoprotein (HDL). The goal of this work is to use a gold nanoparticle (Au NP) as a template to synthesize functional mimics of HDL and characterize their structure and function. Chapter 1 details the structure and function of natural HDL and how chemistry on the nanoscale provides new strategies for mimicking HDL. This Chapter also describes the first examples of using nanoparticles to mimic HDL. Chapter 2 reports the synthesis and characterization of biomimetic HDL using different sizes of Au NPs and different surface chemistries and how these variables can be used to tailor the properties of biomimetic HDL. From these studies the optimal strategy for synthesizing biomimetic HDL was determined. In Chapter 3, the optimization of the synthesis of biomimetic HDL is discussed as well as a full characterization of its structure. In addition, the work in this chapter shows that biomimetic HDL can be synthesized on a large scale without alterations to its structure or function. Chapter 4 focuses on understanding the pathways by which biomimetic HDL accepts cholesterol from macrophage cells. The results of these studies demonstrate that biomimetic HDL is able to accept cholesterol by both active and passive pathways of cholesterol efflux. In Chapter 5 the preliminary results of in vivo studies to characterize the pharmacokinetics and pharmacodynamics of biomimetic HDL are presented. These studies suggest that biomimetic HDL traffics through tissues prone to

  13. Interaction of high-density and low-density lipoproteins to solid surfaces coated with cholesterol as determined by an optical fiber-based biosensor

    NASA Astrophysics Data System (ADS)

    Singh, Bal R.; Poirier, Michelle A.

    1993-05-01

    In recent years, the use of fiber optics has become an important tool in biomedicine and biotechnology. We are involved in developing and employing a new system which, through the use of fiber optics, may be capable of measuring the content of cholesterol and lipoproteins in blood samples in real time. In the optical fiber-based biosensor, a laser beam having a wavelength of 512 nm (green light) is launched into an optical fiber, which transmits the light to its distal end. An evanescent wave (travelling just outside the fiber core) is used to excite rhodamine-labelled HDL or LDL which become bound to the fiber or to fiber-bound molecules. The fluorescence (red light) is coupled back into the fiber and detected with a photodiode. Preliminary work has involved testing of high density lipoprotein (HDL) binding to a cholesterol-coated fiber and to a bare fiber and low density lipoprotein (LDL) binding to a cholesterol-coated fiber. A significant difference was observed in the binding rate of HDL (5 (mu) g/mL and lower) to a bare fiber as opposed to a cholesterol-coated fiber. The binding rate of HDL (5 (mu) g/mL) to a bare fiber was 7.5 (mu) V/sec and to a cholesterol-coated fiber was 3.5 (mu) V/sec. We have calculated the binding affinity of LDL to a cholesterol- coated fiber as 1.4 (mu) M-1. These preliminary results suggest that the optical fiber-based biosensor can provide a unique and promising approach to the analysis of lipoprotein interaction with solid surfaces and with cholesterol. More importantly, the results suggest that this technique may be used to assess the binding of blood proteins to artificial organs/tissues, and to measure the amount of cholesterol, HDL and LDL in less than a minute.

  14. 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.

  15. Purification and properties of the very high density lipoprotein from the hemolymph of adult Triatoma infestans.

    PubMed

    Rimoldi, O J; Soulages, J L; González, S M; Peluffo, R O; Brenner, R R

    1989-06-01

    The very high density lipoprotein (VHDL) of Triatoma infestans hemolymph from adult males has been isolated and purified by two-step density gradient ultracentrifugation. It appears to be homogeneous as judged by native polyacrylamide gel electrophoresis. The content of VHDL in hemolymph was estimated to be 8 mg protein/ml. The purified protein has a molecular weight (Mr) of 450,000, is composed of six subunits of Mr approximately equal to 77,000, and possesses a high content of aromatic amino acids. This protein is glycosylated and contains 3% of lipids by weight with a remarkable amount of free fatty acids (25% of total lipids). The T. infestans VHDL has a different lipid and amino acid composition from lipophorin. The lipid composition and the spectroscopic studies using cis-parinaric acid indicated a high fatty acid binding affinity. It has nine binding sites per mol of VHDL. Competence studies revealed that VHDL has its highest affinity for the binding of palmitic acid followed by stearic and arachidonic acids.

  16. Surface Plasmon Resonance Assay of Binding Properties of Antisense Oligonucleotides to Serum Albumins and Lipoproteins.

    PubMed

    Onishi, Reina; Watanabe, Ayahisa; Nakajima, Mado; Sekiguchi, Mitsuaki; Kugimiya, Akira; Kinouchi, Hiroki; Nihashi, Yoichiro; Kamimori, Hiroshi

    2015-01-01

    In the present study, we developed an assay to evaluate the kinetic binding properties of the unconjugated antisense oligonucleotide (ASO) and lipophilic and hydrophilic ligands conjugated ASOs to mouse and human serum albumin, and lipoproteins using surface plasmon resonance (SPR). The lipophilic ligands conjugated ASOs showed clear affinity to the albumins and lipoproteins, while the unconjugated and hydrophilic ligand conjugated ASOs showed no interaction. The SPR method showed reproducible immobilization of albumins and lipoproteins as ligands on the sensor chip, and reproducible affinity kinetic parameters of interaction of ASOs conjugated with the ligands could be obtained. The kinetic binding data of these ASOs to albumin and lipoproteins by SPR were related with the distributions in the whole liver in mice after administration of these conjugated ASOs. The results demonstrated that our SPR method could be a valuable tool for predicting the mechanism of the properties of delivery of conjugated ASOs to the organs.

  17. 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

  18. 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

  19. 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.

  20. Serum amyloid P component prevents high-density lipoprotein-mediated neutralization of lipopolysaccharide.

    PubMed

    de Haas, C J; Poppelier, M J; van Kessel, K P; van Strijp, J A

    2000-09-01

    Lipopolysaccharide (LPS) is an amphipathic macromolecule that is highly aggregated in aqueous preparations. LPS-binding protein (LBP) catalyzes the transfer of single LPS molecules, segregated from an LPS aggregate, to high-density lipoproteins (HDL), which results in the neutralization of LPS. When fluorescein isothiocyanate-labeled LPS (FITC-LPS) is used, this transfer of LPS monomers to HDL can be measured as an increase in fluorescence due to dequenching of FITC-LPS. Recently, serum amyloid P component (SAP) was shown to neutralize LPS in vitro, although only in the presence of low concentrations of LBP. In this study, we show that SAP prevented HDL-mediated dequenching of FITC-LPS, even in the presence of high concentrations of LBP. Human bactericidal/permeability-increasing protein (BPI), a very potent LPS-binding and -neutralizing protein, also prevented HDL-mediated dequenching of FITC-LPS. Furthermore, SAP inhibited HDL-mediated neutralization of both rough and smooth LPS in a chemiluminescence assay quantifying the LPS-induced priming of neutrophils in human blood. SAP bound both isolated HDL and HDL in serum. Using HDL-coated magnetic beads prebound with SAP, we demonstrated that HDL-bound SAP prevented the binding of LPS to HDL. We suggest that SAP, by preventing LPS binding to HDL, plays a regulatory role, balancing the amount of LPS that, via HDL, is directed to the adrenal glands.

  1. Effects of acute exercise on high density lipoprotein cholesterol and high density lipoprotein subfractions in moderately trained females

    PubMed Central

    Gordon, P. M.; Fowler, S.; Warty, V.; Danduran, M.; Visich, P.; Keteyian, S.

    1998-01-01

    Increases in high density lipoprotein cholesterol (HDL-C) levels have previously been reported after moderate exercise bouts lasting less than two hours in men. Little information exists, however, on HDL-C responses after moderate duration exercise in women. Post-exercise HDL- C modifications may appear differently in women because of higher baseline HDL-C concentrations and differences in lipolytic activity. To determine the influence of exercise on acute HDL-C responses in women, 12 trained premenopausal women (22 (4) years old; mean (SD)) who ran 24- 48 km a week exercised on a motor driven treadmill at 75% VO2MAX until 3.34 MJ (800 kcal) were expended (72 (9) min). Subjects were all tested during the early follicular phase of their menstrual cycle. Fasting blood samples were obtained before exercise (baseline), immediately after (IPE), one hour after (1 h PE), 24 hours after (24 h PE), and 48 hours after (48 h PE) exercise. Plasma was analysed for HDL-C, HDL2-C, and HDL3-C. A significant increase in HDL-C was observed 48 h PE (p<0.05). HDL3-C increased IPE (p<0.01) but returned to baseline at 1 h PE. In contrast, HDL2-C was not significantly different from baseline at any time point. The rise in HDL-C, however, was attributed to an increase in both HDL2 and HDL3. Moreover, at 48 h PE, the increase in HDL-C correlated highly with changes in HDL2-C (r = 0.92). Thus it appears that exercise of moderate duration can elicit similar post- exercise increases in HDL-C in women to those previously reported in men. However, the changes in HDL subfractions leading to the rise in HDL-C may be different in women. 


 PMID:9562167

  2. Effect of Helicobacter pylori eradication on high-density lipoprotein cholesterol.

    PubMed

    Scharnagl, Hubert; Kist, Manfred; Grawitz, Andrea Busse; Koenig, Wolfgang; Wieland, Heinrich; März, Winfried

    2004-01-15

    We examined the effect of Helicobacter pylori (H. pylori) eradication on lipids and apolipoproteins in 87 patients with duodenal ulcers. A significant increase was observed in high-density lipoprotein (HDL) cholesterol (+24.7%, p <0.001), apolipoprotein AI (+9.0%, p <0.001), and apolipoprotein AII (+11.7%, p <0.001) after eradication. Minor increases occurred in total cholesterol, triglycerides, and apolipoprotein B, whereas low-density lipoprotein cholesterol remained unchanged. Our results suggest that chronic H. pylori infection reduces plasma levels of HDL cholesterol and that eradication improves the lipoprotein pattern.

  3. Total cholesterol, high density lipoprotein cholesterol and choline esterase in overseas and Japanese university students.

    PubMed

    Nakamura, S

    1985-04-01

    Serum lipids were studied in 97 overseas and 282 Japanese university students. As compared with Japanese, serum total cholesterol levels were low and high density lipoprotein/total cholesterol ratio was high in the overseas students, especially in Chinese and Korean students. 30-39-year-old Chinese students, moreover, showed elevated high density lipoprotein levels. Choline esterase levels were significantly lower in 30-39-year-old Chinese and Korean students than in Japanese and Taiwanese.

  4. Role of high density lipoproteins in the biodistribution of two radioiodinated probes in the rat

    SciTech Connect

    Pohland, R.C.; Counsell, R.E.

    1985-01-01

    Two radioiodinated probes, /sup 125/I-cholesteryl oleate (/sup 125/I-CO), a derivative of a natural constituent of lipoproteins, and 1-(2-chlorophenyl)-1-(4(/sup 125/I)iodophenyl)-2,2-dichlorethane (/sup 125/I-DDD), an analog of the adrenolytic drug o,p'-DDD (mitotane), were selected to study the role of lipoproteins in drug disposition and to examine the ability of these vehicles to direct foreign molecules to specific tissues. In vivo and in vitro techniques were utilized to associate these probes with rat high density lipoproteins (HDL). Tissue distribution studies indicated that prior incorporation of /sup 125/I-CO into rat HDL increased the uptake of /sup 125/I-CO by rat adrenal, which was dramatically enhanced when this preparation was administered to animals made hypolipidemic with 4-aminopyrazolo(3,4-d)-pyrimidine (4-APP). Acetylation of HDL labeled with /sup 125/I-CO provided evidence that the observed uptake into the adrenal was via a receptor-mediated process. In contrast with these results, prior association of /sup 125/I-DDD with rat HDL failed to alter the ability of this compound to accumulate in adrenal tissue of normal or hypolipidemic animals. Polyacrylamide gel electrophoresis (PAGE) was utilized to examine the stability of the association of /sup 125/I-CO and /sup 125/I-DDD with rat HDL. These results suggested that /sup 125/I-CO was associated with the lipophilic core of HDL, whereas /sup 125/I-DDD appeared to be partially associated with the surface components of HDL. Saturation of surface components with stable o,p'-DDD offered data to suggest that this binding to apoproteins may disrupt the normal receptor-mediated uptake process.

  5. Characterization of Two Metal Binding Lipoproteins as Vaccine Candidates for Enterococcal Infections

    PubMed Central

    Romero-Saavedra, Felipe; Laverde, Diana; Budin-Verneuil, Aurélie; Muller, Cécile; Bernay, Benoit; Benachour, Abdellah; Hartke, Axel; Huebner, Johannes

    2015-01-01

    Background Enterococcus faecium and faecalis are Gram-positive opportunistic pathogens that have become leading causes of nosocomial infections over the last decades. Especially multidrug resistant enterococci have become a challenging clinical problem worldwide. Therefore, new treatment options are needed and the identification of alternative targets for vaccine development has emerged as a feasible alternative to fight the infections caused by these pathogens. Results We extrapolate the transcriptomic data from a mice peritonitis infection model in E. faecalis to identify putative up-regulated surface proteins under infection conditions in E. faecium. After the bionformatic analyses two metal binding lipoproteins were identified to have a high homology (>72%) between the two species, the manganese ABC transporter substrate-binding lipoprotein (PsaAfm,) and the zinc ABC transporter substrate-binding lipoprotein (AdcAfm). These candidate lipoproteins were overexpressed in Escherichia coli and purified. The recombinant proteins were used to produce rabbit polyclonal antibodies that were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Mice were passively immunized with the antibodies raised against recombinant lipoproteins, showing significant reduction of colony counts in mice livers after the bacterial challenge and demonstrating the efficacy of these metal binding lipoproteins as promising vaccine candidates to treat infections caused by these enterococcal pathogens. Conclusion Overall, our results demonstrate that these two metal binding lipoproteins elicited specific, opsonic and protective antibodies, with an extensive cross-reactivity and serotype-independent coverage among these two important nocosomial pathogens. Pointing these two protein antigens as promising immunogens, that can be used as single

  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. The effects of glibenclamide and insulin on plasma high density lipoprotein in diabetics.

    PubMed

    Tamai, T; Nakai, T; Yamada, S; Kobayashi, T; Hayashi, T; Kutsumi, Y; Oida, K; Takeda, R

    1981-01-01

    The purpose of the present study was to investigate the effects of various types of treatment such as glibenclamide and insulin on plasma lipids and lipoprotein concentration in diabetics. Treatment of diabetes mellitus was reevaluated from the standpoint of high density lipoprotein (HDL) metabolism. Twenty-one diabetic patients (6 men and 15 women) who have been admitted in the hospital and kept on Japanese standard diet for diabetes mellitus, have been studied. Changes of plasma lipoprotein in diabetic patients were followed up before and after treatment with glibenclamide or insulin. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) were decreased and HDL was increased with insulin treatment. However, glibenclamide induced a significant decrease in HDL- cholesterol (Ch). Relationship between triglyceride (TG)-rich lipoproteins and HDL metabolism was studied. A significant negative correlation was found between pretreatment VLDL-TG and changes of VLDL-TG with insulin treatment, indicating an accelerated catabolism of VLDL-TG with possible increase of triglyceride lipases. There was a significant negative correlation between VLDL-TG and HDL-Ch before insulin treatment, but not after treatment. There was no negative correlation between changes of VLDL-TG and changes of HDL-Ch with insulin therapy. These results indicate that an increment of HDL with insulin treatment can not be explained solely by increased HDL formation from TG-rich lipoprotein and that insulin might increase synthesis and secretion of HDL in liver and/or intestine.

  8. Glycosaminoglycan-lipoprotein interaction.

    PubMed

    Olsson, U; Ostergren-Lundén, G; Moses, J

    2001-10-01

    Glycosaminoglycans (GAGs) bound to various proteoglycans (PGs) present in the cardiovascular system have been proposed to perform a wide range of functions. These include conferring viscoelastic properties; interacting with and modulating growth factors and enzymes; and as receptors and co-receptors in lipoprotein metabolism. Binding of apoB-100 lipoproteins, particularly low density lipoproteins (LDL), to GAGs of extracellular matrix PGs in arteries has been proposed to be an initiating event in development of atherosclerosis. This study was initiated with the aim of getting an overview of the binding patterns of different lipoprotein subclasses with individual GAG categories. We thus evaluated the interaction of lipoproteins with GAGs commonly found in the cardiovascular system using a gel mobility-shift assay developed for this purpose. The same procedure was used to measure lipoproteins binding to metabolically [(35)S]-labeled whole PGs prepared from three cell types, arterial smooth muscle cells, THP-1 macrophages and from HepG2 cells. The effect of GAG composition on PGs on lipoprotein binding was evaluated by enzymatic degradation of the carbohydrate chains. Heparan sulfate was found to bind beta very low density lipoproteins (beta-VLDL) and a chylomicron remnant model (beta-VLDL+apoE), but not LDL. Dermatan sulfate was found to bind LDL, but not beta-VLDL or the chylomicron remnant model. Chondroitin sulfate and heparin were found to bind all lipoproteins tested (LDL, beta-VLDL and beta-VLDL+apoE) although with different affinities. We can conclude that each lipoprotein subclass tested binds a specific assortment of the GAGs tested. The observations made contribute to the understanding of new and complex mechanisms by which carbohydrate and lipid metabolism may be linked.

  9. 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.

  10. Serum amyloid A-containing human high density lipoprotein 3. Density, size, and apolipoprotein composition.

    PubMed

    Coetzee, G A; Strachan, A F; van der Westhuyzen, D R; Hoppe, H C; Jeenah, M S; de Beer, F C

    1986-07-25

    Serum amyloid A protein (apo-SAA), an acute phase reactant, is an apolipoprotein of high density lipoproteins (HDL), in particular the denser subpopulation HDL3. The structure of HDL3 isolated from humans affected by a variety of severe disease states was investigated with respect to density, size, and apolipoprotein composition, using density gradient ultracentrifugation, gradient gel electrophoresis, gel filtration, and solid phase immunoadsorption. Apo-SAA was present in HDL particles in increasing amounts as particle density increased. Apo-SAA-containing HDL3 had bigger radii than normal HDL3 of comparable density. Purified apo-SAA associated readily with normal HDL3 in vitro, giving rise to particles containing up to 80% of their apoproteins as apo-SAA. The addition of apo-SAA resulted in a displacement of apo-A-I and an increase in particle size. Acute phase HDL3 represented a mixture of particles, polydisperse with respect to apolipoprotein content; for example, some particles were isolated that contained apo-A-I, apo-A-II, and apo-SAA, whereas others contained apo-A-I and apo-SAA but no apo-A-II. We conclude that apo-SAA probably associates in the circulation of acute phase patients with existing HDL particles, causing the remodeling of the HDL shell to yield particles of bigger size and higher density that are relatively depleted of apo-A-I.

  11. 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.

  12. 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.

  13. 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

  14. Optical Properties of Europium Tetracycline Complexes in the Presence of High-Density Lipoproteins (HDL) Subfractions.

    PubMed

    Sicchieri, Letícia Bonfante; Monteiro, Andrea Moreira; Figueiredo Neto, Antônio Martins; Gomes, Laércio; Courrol, Lilia Coronato

    2016-12-12

    Standard lipoprotein measurements of triglycerides, total cholesterol, low-density lipoproteins (LDL), and high-density lipoproteins (HDL) fail to identify many lipoprotein abnormalities that contribute to cardiovascular heart diseases (CHD). Studies suggested that the presence of CHD is more strongly associated with the HDL subspecies than with total HDL cholesterol levels. The HDL particles can be collected in at least three subfractions, the HDL2b, HDL2a, and HDL3. More specifically, atherosclerosis is associated with low levels of HDL2. In this work, the optical spectroscopic properties of europium tetracycline (EuTc) complex in the presence of different HDL subspecies was studied. The results show that the europium spectroscopic properties in the EuTc complex are influenced by sizes and concentrations of subclasses. Eu(3+) emission intensity and lifetime can discriminate the subfractions HDL3 and HDL2b.

  15. Correction of Apolipoprotein A-I-mediated Lipid Efflux and High Density Lipoprotein Particle Formation in Human Niemann-Pick Type C Disease Fibroblasts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Impaired cell cholesterol trafficking in Niemann-Pick type C (NPC) disease results in the first known instance of impaired regulation of the ATP-binding cassette transporter A1 (ABCA1), a lipid transporter mediating the rate-limiting step in high density lipoprotein (HDL) formation, as a cause of lo...

  16. Rhesus positivity and low high-density lipoprotein cholesterol: a new link?

    PubMed

    Kanbay, Mehmet; Yildirir, Aylin; Ulus, Taner; Bilgi, Muhammet; Kucuk, Alparslan; Muderrisoglu, Haldun

    2006-04-01

    The aim of the study was to investigate the relationship of ABO and Rh blood groups with lipid profile in patients with established multivessel coronary artery disease in a population with low levels of high-density lipoprotein cholesterol. The records of 978 patients with multivessel coronary artery disease, in whom coronary bypass surgery was performed, were investigated. Coronary risk factors including diabetes, hypertension, smoking, and obesity were noted for each patient. Serum lipid profiles: total cholesterol, low-density and high-density lipoprotein cholesterol, and triglyceride levels, were also recorded. The mean age of the patients was 59.3 +/- 9.7 years (range, 25-84 years) and 80% were male. The risk factors and lipid profiles of ABO blood types were similar. Rh-negative patients had higher levels of high-density lipoprotein cholesterol (46.9 +/- 9.9 vs. 41.6 +/- 10.4 mg.dL(-1), p = 0.001) and a lower total/high-density lipoprotein cholesterol ratio (4.8 +/- 1.3 vs. 5.2 +/- 1.6, p = 0.029) compared to Rh-positive patients. The other lipid levels and risk factors had no association with Rh typing. These results indicate a significant association between rhesus positivity and low levels of high-density lipoprotein cholesterol in patients with multivessel coronary artery disease.

  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. 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.

  19. 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.

  20. Arachnid lipoproteins: comparative aspects.

    PubMed

    Cunningham, Mónica; Garcia, Fernando; Pollero, Ricardo J

    2007-01-01

    Findings on hemolymph lipoproteins in the class Arachnida are reviewed in relation to their lipid and protein compositions, hydrated densities, the capacity of apoproteins to bind lipids, and the influence of xenobiotics on their structures and functionality. The occurrence of hemolymphatic lipoproteins in arachnids has been reported in species belonging to the orders Araneida, Scorpionida, Solpugida and Acarina. However, lipoproteins were properly characterized in only three species, Eurypelma californicum, Polybetes pythagoricus and Latrodectus mirabilis. Like insect and crustaceans the arachnids examined contain high density lipoproteins (HDLs) as predominant circulating lipoproteins. Although in most arachnids these particles resemble those of insect HDLs called "lipophorins", in two arachnid species they differ from lipophorins in their apoproteins, total mass and lipid composition. The hemolymph of P. pythagoricus and L. mirabilis contains another HDL of higher density, while P. pythagoricus and E. californicum hemolymph contain a third lipoprotein of very high density (VHDL). Composition of arachnid lipoproteins regarding apoprotein classes as well as lipid classes differ among species. Hemocyanin, in addition to the classical role of this protein as respiratory pigment, is presented here performing the function of apolipoprotein in some arachnid species. Reports on experiments demonstrating the capacity of hemocyanin to bind neutral and polar lipid classes, including ecdysteroids, are commented. Recent works about the changes evoked by a phosphorous pesticide on the structures and functionality of spider lipoproteins are also reviewed.

  1. Action of lecithin:cholesterol acyltransferase on model lipoproteins. Preparation and characterization of model nascent high density lipoprotein.

    PubMed

    Pownall, H J; Van Winkle, W B; Pao, Q; Rohde, M; Gotto, A M

    1982-12-13

    Apolipoprotein A-I, the major protein of human plasma high density lipoprotein, is the primary activator of plasma lecithin:cholesterol acyltransferase. In vitro, the association of apolipoprotein A-I with physiological phosphatidylcholines can be catalyzed by mixing the protein and lipid with sodium cholate, which is removed by chromatography. The apolipoprotein A-I/phospholipid complex has the physical properties of an HDL, and when cholesterol is present the complex is a highly reactive substrate in the lecithin:cholesterol acyltransferase-catalyzed reaction. The relative reactivity of this complex compared with a number of other lipid-protein complexes is presented and discussed.

  2. 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

  3. Changes in the distribution and composition of plasma high density lipoproteins after ingestion of fat.

    PubMed

    Tall, A R; Blum, C B; Forester, G P; Nelson, C A

    1982-01-10

    Following ingestion of a fatty meal there is an increase in concentration of phospholipids and proteins in the plasma high density lipoproteins (HDL). To evaluate the resulting changes in HDL subclasses, the plasma HDL of six subjects were analyzed 4 to 8 h after ingestion of 100 ml of corn oil or 80 ml of corn oil with four eggs. Isopycnic density gradient ultracentrifugation of fasting plasma showed two broad components of HDL: a major peak of density (d) 1.11 to 1.17 g/ml (HDL3) and a smaller peak of d 1.07 to 1.11 g/ml (HDL2). Following ingestion of either type of fatty meal, there was an increase in lipoprotein mass in both peaks of HDL and their centers of mass were shifted to lower density (1.140 leads to 1.120 to 1.130 g/ml; 1.095 leads to 1.090 g/ml). Calculation of changes in HDL concentration (lipemic minus fasting) showed that the alterations in density gradient profile were due to a major increase in lipoproteins of d 1.102 to 1.137 g/ml, a smaller increase in a separate lipoprotein peak of 1.080 to 1.102 g/ml, and a small decrease in lipoproteins of d 1.137 to 1.165 g/ml. Redistribution of HDL mass into larger, less dense lipoproteins was also demonstrated by agarose gel chromatography or by minimal spin density gradient ultracentrifugation in a vertical rotor. The increase in mass of 1.080 to 1.102 lipoproteins was largely due to increased concentrations of phospholipid, cholesterol ester, and apoA-I, while the increase in 1.102 to 1.137 lipoproteins was due to increased concentrations of apoA-I, apoA-II, phospholipids, cholesterol, and cholesterol esters. Analytical ultracentrifugation of representative samples within these density intervals showed lipoprotein species with molecular weights and sedimentation coefficients, respectively, of 378,000, 5.8 (d 1.080 to 1.095); 248,000, 3.5 (d 1.110 to 1.120); and 173,000, 1.6 (d 1.135 to 1.150). Polyacrylamide gradient gel electrophoresis showed that the 1.080 to 1.102 lipoproteins contained a single

  4. Cigarette smoking, exercise and high density lipoprotein cholesterol.

    PubMed

    Stamford, B A; Matter, S; Fell, R D; Sady, S; Papanek, P; Cresanta, M

    1984-07-01

    Cigarette smoking is associated with depressed levels of HDL-C, whereas exercise is associated with elevated levels of HDL-C. The purpose was to determine effects of smoking and exercise on blood lipids and lipoproteins in middle-aged males. It was hypothesized that smoking may attenuate the effects of exercise to elevate HDL-C. A total of 269 males (70 smokers) met all criteria for inclusion in the study population. Age, height, weight, body fatness via hydrostatic weighing, daily caloric consumption and alcohol intake, and smoking habits and history were determined. Interviews concerning physical activity patterns were conducted and cardiovascular responses to treadmill exercise were determined. Subjects were grouped as sedentary (low activity), participants in vigorous recreational activities (moderate activity) and joggers/runners (high activity). Analysis of covariance with adjustments for factors which may affect blood lipids and lipoproteins was employed. Smokers demonstrated lower HDL-C and higher total cholesterol levels than nonsmokers. High activity subjects demonstrated significantly higher HDL-C levels than the low and moderate groups which did not differ. High activity smokers did not differ from low activity nonsmokers with respect to HDL-C. This supports the proposed hypothesis. Nonsmokers were higher in weight and body fatness than smokers even though smokers consumed 288 more calories per day on the average. This suggests that smoking may account for a significant number of calories through altered metabolism or some other means.

  5. 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.

  6. Megalin acts in concert with cubilin to mediate endocytosis of high density lipoproteins.

    PubMed

    Hammad, S M; Barth, J L; Knaak, C; Argraves, W S

    2000-04-21

    Cubilin has recently been shown to function as an endocytic receptor for high density lipoproteins (HDL). The lack of apparent transmembrane and cytoplasmic domains in cubilin raises questions as to the means by which it can mediate endocytosis. Since cubilin has been reported to bind the endocytic receptor megalin, we explored the possibility that megalin acts in conjunction with cubilin to mediate HDL endocytosis. While megalin did not bind to HDL, delipidated HDL, or apoA-I, it was found to copurify with cubilin isolated by HDL-Sepharose affinity chromatography. Cubilin and megalin exhibited coincident patterns of mRNA expression in mouse tissues including the kidney, ileum, thymus, placenta, and yolk sac endoderm. The expression of both receptors in yolk sac endoderm-like cells was inducible by retinoic acid treatment but not by conditions of sterol depletion. Suppression of megalin activity or expression by treatment with either megalin antibodies or megalin antisense oligodeoxynucleotides resulted in inhibition of cubilin-mediated endocytosis of HDL. Furthermore, megalin antisense oligodeoxynucleotide treatment resulted in reduced cell surface expression of cubilin. These data demonstrate that megalin acts together with cubilin to mediate HDL endocytosis and further suggest that megalin may play a role in the intracellular trafficking of cubilin.

  7. 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.

  8. Lipopolysaccharide (LPS)-binding protein is carried on lipoproteins and acts as a cofactor in the neutralization of LPS

    PubMed Central

    1994-01-01

    Lipoproteins isolated from normal human plasma can bind and neutralize bacterial lipopolysaccharide (LPS) and may represent an important mechanism in host defense against gram-negative septic shock. Recent studies have shown that experimentally elevating the levels of circulating high-density lipoproteins (HDL) provides protection against death in animal models of endotoxic shock. We sought to define the components of HDL that are required for neutralization of LPS. To accomplish this we have studied the functional neutralization of LPS by native and reconstituted HDL using a rapid assay that measures the CD14- dependent activation of leukocyte integrins on human neutrophils. We report here that reconstituted HDL particles (R-HDL), prepared from purified apolipoprotein A-I (apoA-I) combined with phospholipid and free cholesterol, are not sufficient to neutralize the biologic activity of LPS. However, addition of recombinant LPS binding protein (LBP), a protein known to transfer LPS to CD14 and enhance responses of cells to LPS, enabled prompt binding and neutralization of LPS by R- HDL. Thus, LBP appears capable of transferring LPS not only to CD14 but also to lipoprotein particles. In contrast with R-HDL, apoA-I containing lipoproteins (LpA-I) isolated from plasma by selected affinity immunosorption (SAIS) on an anti-apoA-I column, neutralized LPS without addition of exogenous LBP. Several lines of evidence demonstrated that LBP is a constituent of LpA-I in plasma. Passage of plasma over an anti-apoA-I column removed more than 99% of the LBP detectable by ELISA, whereas 31% of the LBP was recovered by elution of the column. Similarly, the ability of plasma to enable activation of neutrophils by LPS (LBP/Septin activity) was depleted and recovered by the same process. Furthermore, an immobilized anti-LBP monoclonal antibody coprecipitated apoA-I. The results described here suggest that in addition to its ability to transfer LPS to CD14, LBP may also transfer LPS to

  9. 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

  10. Analysis by enzyme-linked immunosorbent assay and 2-dimensional electrophoresis of haptoglobin in the high-density lipoprotein fraction in cows.

    PubMed

    Kanno, H; Katoh, N

    2001-01-01

    Haptoglobin (Hp) is a hemoglobin (Hb)-binding acute-phase protein. Besides its relevance in inflammation, Hp is involved in the regulation of lipid metabolism. In cattle, in addition to the lipoprotein-deficient fraction, Hp is distributed in high-density lipoprotein (HDL) and very high-density lipoprotein (VHDL) fractions. The purpose of this study was to determine Hp concentrations in the lipoprotein fractions using an enzyme-linked immunosorbent assay (ELISA) based on the affinity with Hb, and also to detect structural differences of HDL Hp from that in the lipoprotein-deficient fraction using 2-dimensional electrophoresis. When purified Hp was used as the antigen for the ELISA, the detection limit was 7.4 ng/ml and linearity was obtained from 14.8 to 475 ng/ml. The correlation coefficient between the ELISA and single radial immunodiffusion was 0.884. The ELISA was shown to be applicable to evaluate Hp concentrations in the lipoprotein fractions. Hp concentrations in the lipoprotein fractions were in the range of 0.94 to 8.77 microg of Hp/ml (n = 4), and concentration ratios were 0.2 to 0.3% of whole serum Hp. Of the lipoprotein fractions, Hp was most abundant in HDL, moderate in VHDL and faint in chylomicrons, the very low-density lipoprotein fraction and low-density lipoprotein fraction. By 2-dimensional electrophoresis, alpha- and beta-chains of serum Hp were each separated into 5 spots, and their isoelectric point (pI) values were from 5.05 to 6.28 in the alpha-chain and from 5.92 to 6.95 in the beta-chain. The pI values of HDL Hp were indistinguishable from those of serum Hp. These results indicate that the ELISA based on the affinity with Hb is useful for evaluating Hp concentrations in lipoprotein fractions, and also suggest that HDL Hp is structurally similar to that in the lipoprotein-deficient fraction.

  11. Pharmacogenomics of high-density lipoprotein-cholesterol-raising therapies

    PubMed Central

    Aslibekyan, Stella; Straka, Robert J.; Irvin, Marguerite R.; Claas, Steven A.; Arnett, Donna K.

    2017-01-01

    High levels of HDL cholesterol (HDL-C) have traditionally been linked to lower incidence of cardiovascular disease, prompting the search for effective and safe HDL-C raising pharmaceutical agents. Although drugs such as niacin and fibrates represent established therapeutic approaches, HDL-C response to such therapies is variable and heritable, suggesting a role for pharmacogenomic determinants. Multiple genetic polymorphisms, located primarily in genes encoding lipoproteins, cholesteryl ester transfer protein, transporters and CYP450 genes have been shown to associate with HDL-C drug response in vitro and in epidemiologic studies. However, few of the pharmacogenomic findings have been independently validated, precluding the development of clinical tools that can be used to predict HDL-C response and leaving the goal of personalized medicine to future efforts. PMID:23469915

  12. 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.

  13. 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.

  14. APOL1 nephropathy risk variants are associated with altered high-density lipoprotein profiles in African Americans

    PubMed Central

    Gutiérrez, Orlando M.; Judd, Suzanne E.; Irvin, Marguerite R.; Zhi, Degui; Limdi, Nita; Palmer, Nicholette D.; Rich, Stephen S.; Sale, Michèle M.; Freedman, Barry I.

    2016-01-01

    Background Two independent coding variants in the apolipoprotein L1 gene (APOL1), G1 and G2, strongly associate with nephropathy in African Americans; associations with cardiovascular disease are more controversial. Although APOL1 binds plasma high-density lipoproteins (HDLs), data on APOL1 risk variant associations with HDL subfractions are sparse. Methods Two APOL1 G1 single nucleotide polymorphisms and the G2 insertion/deletion polymorphism were genotyped in 2010 Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study participants with nuclear magnetic resonance spectroscopy-based lipoprotein subfraction measurements. Linear regression was used to model associations between numbers of APOL1 G1/G2 risk variants and HDL subfractions, adjusting for demographic, clinical and ancestral covariates. Results Female sex and higher percentage of African ancestry were positively associated with the number of APOL1 G1/G2 risk alleles. In the unadjusted analysis, mean (standard error) small HDL concentrations (μmol/L) for participants with zero, one and two G1/G2 risk alleles were 19.0 (0.2), 19.7 (0.2) and 19.9 (0.4), respectively (P = 0.02). Adjustment for age, sex, diabetes and African ancestry did not change the results but strengthened the statistical significance (P = 0.004). No significant differences in large or medium HDL, very low-density lipoprotein or low-density lipoprotein particle concentrations were observed by APOL1 genotype. Conclusions Greater numbers of APOL1 G1/G2 risk alleles were associated with higher small HDL particle concentrations in African Americans. These results may suggest novel areas of investigation to uncover reasons for the association between APOL1 risk variants with adverse outcomes in African Americans. PMID:26152403

  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. 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.

  17. High-density lipoprotein acts as an opsonin to enhance phagocytosis of group A streptococcus by U937 cells.

    PubMed

    Liu, Ling; Zhou, Lulei; Li, Yuxin; Bai, Wencheng; Liu, Na; Li, Wenlong; Gao, Yumin; Liu, Zhi; Han, Runlin

    2015-07-01

    We have previously demonstrated that high-density lipoprotein (HDL) can specifically bind to streptococcal collagen-like protein 1 (Scl1) of M41-type group A Streptococcus (GAS). However, the pathological or physiological significance of Scl1-HDL interaction is unknown. Here, the hypothesis that HDL acts as an opsonin to enhance phagocytosis of HDL-bound GAS by monocytes given that some scavenger receptors can mediate the endocytosis of HDL was tested by using FITC-labeled bacteria, human U937 monocytes and HDL for phagocytic assays. HDL (10 µg/mL) was found to significantly enhance internalization of M41-type (ATCC 12373) GAS by U937 cells after 60 min incubation, compared with an HDL-free group. The internalized GAS were dead after 60 min incubation with U937 cells regardless of presence and absence of HDL. Although very-low-density lipoprotein (VLDL) could specifically bind to ATCC 12373 strain, it did not promote phagocytosis of GAS. Additionally, LDL, HDL and VLDL did not enhance phagocytosis of CMCC 32198 strain because this strain did not bind to these lipoproteins. A physiological concentration of HDL (1000 µg/mL) had a similar effect. Anti-CD36 antibody completely abolished opsonic phagocytosis whereas anti-CD4 antibody did not, indicating that CD36 is the major scavenger receptor mediating the uptake of HDL-opsonized GAS by U937 cells. Furthermore, because rScl1 competitively blocked the interaction of ATCC 12373 strain with HDL recombinant Scl1 (rScl1) derived from M41-type GAS, it significantly decreased opsonophagocytosis of ATCC 12373 strain but not of CMCC 32198 strain. Therefore, our findings suggest that HDL may be an opsonin that enhances CD36-dependent opsonophagocytosis of GAS by U937 cells.

  18. Subfractions of high-density lipoprotein (HDL) and dysfunctional HDL in chronic kidney disease patients.

    PubMed

    Rysz-Górzyńska, Magdalena; Banach, Maciej

    2016-08-01

    A number of studies have shown that chronic kidney disease (CKD) is associated with increased risk for cardiovascular disease (CVD). Chronic kidney disease is characterized by significant disturbances in lipoprotein metabolism, including differences in quantitative and qualitative content of high-density lipoprotein (HDL) particles. Recent studies have revealed that serum HDL cholesterol levels do not predict CVD in CKD patients; thus CKD-induced modifications in high-density lipoprotein (HDL) may be responsible for the increase in CV risk in CKD patients. Various methods are available to separate several subclasses of HDL and confirm their atheroprotective properties. However, under pathological conditions associated with inflammation and oxidation, HDL can progressively lose normal biological activities and be converted into dysfunctional HDL. In this review, we highlight the current state of knowledge on subfractions of HDL and HDL dysfunction in CKD.

  19. Subfractions of high-density lipoprotein (HDL) and dysfunctional HDL in chronic kidney disease patients

    PubMed Central

    Banach, Maciej

    2016-01-01

    A number of studies have shown that chronic kidney disease (CKD) is associated with increased risk for cardiovascular disease (CVD). Chronic kidney disease is characterized by significant disturbances in lipoprotein metabolism, including differences in quantitative and qualitative content of high-density lipoprotein (HDL) particles. Recent studies have revealed that serum HDL cholesterol levels do not predict CVD in CKD patients; thus CKD-induced modifications in high-density lipoprotein (HDL) may be responsible for the increase in CV risk in CKD patients. Various methods are available to separate several subclasses of HDL and confirm their atheroprotective properties. However, under pathological conditions associated with inflammation and oxidation, HDL can progressively lose normal biological activities and be converted into dysfunctional HDL. In this review, we highlight the current state of knowledge on subfractions of HDL and HDL dysfunction in CKD. PMID:27478466

  20. Utility of non-high-density lipoprotein cholesterol in hemodialyzed patients.

    PubMed

    Schreier, Laura; González, Ana I; Elbert, Alicia; Berg, Gabriela; Wikinski, Regina

    2004-08-01

    Non-high-density lipoprotein-cholesterol (HDL-C) is proposed as a strong predictor of cardiovascular disease (CVD). Measuring non-HDL-C, as total cholesterol minus HDL-C, is convenient for routine practice because, among other advantages, fasting is not required. There are limited data of non-HDL-C in end-stage renal disease patients. We applied non-HDL-C calculation to 50 chronic renal patients receiving maintenance hemodialysis (HD) and 20 healthy subjects, apart from measurement of low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) HDL, intermediate-density lipoprotein-cholesterol (IDL-C), apoprotein (apo) B, and triglycerides. HD patients presented higher plasma triglycerides and IDL-C and lower HDL-C than the control group, even after adjustment for age (P < .05). VLDL-C increased in HD patients (P < .001) while differences in non-HDL-C did not reach significance (P = .08). To detect which parameter constitutes a better marker of CVD risk among HD patients, a receiver-operating characteristic (ROC) analysis was performed considering HD patients in the highest risk group for CVD. In the ROC graphic, the plots of VLDL and IDL-C exhibited the greater observed accuracy and the best performance, while non-HDL-C showed a curve close to the 45 degrees line indicating that this parameter is a poor discriminator for evaluating CVD risk among HD patients. Non-HDL-C calculation, expressing all apo B-containing lipoproteins, may miss the significant contribution of each atherogenic lipoprotein, such as increase in IDL. This observation would not be in agreement with the currently proposed application of non-HDL-C a useful tool for risk assessment among HD patients.

  1. Effect of genistein against copper-induced lipid peroxidation of human high density lipoproteins (HDL).

    PubMed

    Ferretti, G; Bacchetti, T; Menanno, F; Curatola, G

    2004-01-01

    Several studies have demonstrated that the isoflavone genistein exerts a protective effect against lipid peroxidation of low density lipoproteins (LDL). Aim of our study was to investigate whether genistein protects high density lipoproteins (HDL), isolated from normolipemic subjects, against Cu(++)-induced lipid peroxidation. Our results demonstrated that genistein exerts an inhibitory effect against Cu(++)-induced lipid peroxidation of HDL, as shown by the lower increase in the levels of conjugated dienes in lipoproteins oxidized after preincubation with different concentrations of genistein (0.5-2.5microM). Moreover the analysis of fluorescence emission spectra of tryptophan (Trp) and Laurdan (6-dodecanoyl-2-dimethyl-aminonaphthalene) demonstrated that genistein prevents the alterations of apoprotein structure and physico-chemical properties, associated with Cu(++)-triggered lipid peroxidation of lipoproteins. The protective effect exerted by genistein against oxidative damage of lipoproteins was realized at concentrations similar to those observed in plasma of human subjects consuming a traditional soy diet or receiving a soy supplement. Therefore, we suggested that antioxidant activity exerted by genistein against lipid peroxidation of HDL in vitro could be of physiological relevance.

  2. Low density lipoprotein fraction assay for cardiac disease risk

    DOEpatents

    Krauss, Ronald M.; Blanche, Patricia J.; Orr, Joseph

    1999-01-01

    A variable rate density gradient electrophoric gel is described which separate LDL subfractions with the precision of ultracentrifugation techniques. Also, an innovative bottom inlet mixing chamber particularly useful for producing these gels is described.

  3. Low density lipoprotein fraction assay for cardiac disease risk

    DOEpatents

    Krauss, R.M.; Blanche, P.J.; Orr, J.

    1999-07-20

    A variable rate density gradient electrophoric gel is described which separates LDL subfractions with the precision of ultracentrifugation techniques. Also, an innovative bottom inlet mixing chamber particularly useful for producing these gels is described. 8 figs.

  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. 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...

  6. 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...

  7. Total and High-Density Lipoprotein Cholesterol in Adults with Mental Retardation.

    ERIC Educational Resources Information Center

    Rimmer, James H.; Kelly, Luke E.

    1990-01-01

    The study evaluated the total cholesterol and high density lipoprotein cholesterol of 40 adults (mean age 37.5 years) with mental retardation residing at an intermediate care facility. Results indicated that 59 percent of the males and 68 percent of the females were at moderate to high risk for coronary heart disease. (DB)

  8. 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 §...

  9. 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 §...

  10. 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.

  11. High-density lipoprotein-mediated transcellular cholesterol transport in mouse aortic endothelial cells.

    PubMed

    Miao, LiXia; Okoro, Emmanuel U; Cao, ZhiJan; Yang, Hong; Motley-Johnson, Evangeline; Guo, Zhongmao

    2015-09-18

    Accumulation of unesterified cholesterol-rich lipid vesicles in the subendothelial space contributes to atherogenesis. Transport of cholesterol from the subendothelial intima back to the circulating blood inhibits atherosclerosis development; however, the mechanism for this process has not been fully defined. Using cultured mouse aortic endothelial cells (MAECs), we observed that unesterified cholesterol can be transported across the endothelial cell monolayer from the basolateral to the apical compartment. Administration of high-density lipoprotein (HDL) or apolipoprotein AI (apoAI) to the apical compartment enhanced transendothelial cholesterol transport in a concentration-dependent manner. Knockdown of ATP-binding cassette transporter G1 (ABCG1) or scavenger receptor class B type I (SR-B1), or inhibition of SR-B1 diminished HDL-induced transendothelial cholesterol transport; while knockdown of ABCA1 reduced apoAI-mediated cholesterol transport. HDL enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt in MAECs. However, inhibition of PI3K or Akt did not reduce HDL-induced transendothelial cholesterol transport. These results suggest that HDL enhances transendothelial cholesterol transport by activation of a mechanism involving ABCA1, ABCG1 and SR-B1 but not involving PI3K and Akt.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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.

  17. High-Density Lipoprotein-Mediated Transcellular Cholesterol Transport in Mouse Aortic Endothelial Cells

    PubMed Central

    Miao, LiXia; Okoro, Emmanuel U.; Cao, ZhiJan; Yang, Hong; Motley-Johnson, Evangeline; Guo, Zhongmao

    2015-01-01

    Accumulation of unesterified cholesterol-rich lipid vesicles in the subendothelial space contributes to atherogenesis. Transport of cholesterol from the subendothelial intima back to the circulating blood inhibits atherosclerosis development; however, the mechanism for this process has not been fully defined. Using cultured mouse aortic endothelial cells (MAECs), we observed that unesterified cholesterol can be transported across the endothelial cell monolayer from the basolateral to the apical compartment. Administration of high-density lipoprotein (HDL) or apolipoprotein AI (apoAI) to the apical compartment enhanced transendothelial cholesterol transport in a concentration-dependent manner. Knockdown of ATP-binding cassette transporter G1 (ABCG1) or scavenger receptor class B type I (SR-B1), or inhibition of SR-B1 diminished HDL-induced transendothelial cholesterol transport; while knockdown of ABCA1 reduced apoAI-mediated cholesterol transport. HDL enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt in MAECs. However, inhibition PI3K or Akt did not reduce HDL-induced transendothelial cholesterol transport. These results suggest that HDL enhances transendothelial cholesterol transport by activation of a mechanism involving ABCA1, ABCA1 and SR-B1 but not involving PI3K and Akt. PMID:26255968

  18. 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.

  19. Genome-wide association studies identified novel loci for non-high-density lipoprotein cholesterol and its postprandial lipemic response

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Non-high-density lipoprotein cholesterol (NHDL) is an independent and superior predictor of CVD risk as compared to low-density lipoprotein alone. It represents a spectrum of atherogenic lipid fractions with possibly a distinct genomic signature. We performed genome-wide association studies (GWAS) t...

  20. Inhibitory effects of in vivo oxidized high-density lipoproteins on platelet aggregation: evidence from patients with abetalipoproteinemia.

    PubMed

    Calzada, Catherine; Véricel, Evelyne; Colas, Romain; Guillot, Nicolas; El Khoury, Graziella; Drai, Jocelyne; Sassolas, Agnès; Peretti, Noël; Ponsin, Gabriel; Lagarde, Michel; Moulin, Philippe

    2013-07-01

    There is evidence that high-density lipoproteins (HDLs) may regulate platelet function, but disparate results exist regarding the effects of oxidized HDLs on platelets. The objective of our study was to determine the role of in vivo oxidized HDLs on platelet aggregation. Platelet aggregation and redox status were investigated in 5 patients with abetalipoproteinemia (ABLP) or homozygous hypobetalipoproteinemia, two rare metabolic diseases characterized by the absence of apolipoprotein B-containing lipoproteins, compared to 5 control subjects. Platelets isolated from plasma of patients with ABLP aggregated 4 to 10 times more than control platelets, depending on the agonist. By contrast, no differences in the extent of platelet aggregation were observed between ABLP platelet-rich plasma (PRP) and control PRP, suggesting the presence of a protective factor in ABLP plasma. ABLP HDLs inhibited agonist-induced platelet aggregation by binding to SR-BI, while control HDLs had no effect. On the other hand, lipoprotein-deficient plasma from patients with ABLP did not inhibit platelet aggregation. Severe oxidative stress was evidenced in patients with ABLP. Compared to control HDLs, ABLP HDLs showed a 40% decrease of α-tocopherol and an 11-fold increased malondialdehyde concentration. These results demonstrate that in vivo oxidized HDLs do not lose their antiaggregatory properties despite oxidation.

  1. 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.

  2. A very-high-density lipoprotein with clotting ability from hemolymph of sand crayfish, Ibacus ciliatus.

    PubMed

    Komatsu, M; Ando, S

    1998-03-01

    A very-high-density lipoprotein (VHDL) with a density of 1.27-1.29 g/ml was the most abundant lipoprotein in the hemolymph of the sand crayfish Ibacus ciliatus. The VHDL isolated by a density gradient ultracentrifugation consisted of 94% protein and 6% lipid reflecting its high density, and phospholipid was a predominant lipid component. The VHDL had an apolipoprotein of molecular mass 195 kDa and its N-terminal amino acid sequence was identified as follows: LQPGLEYQYRYNGRVAA. This sequence was similar to those of clotting proteins from the spiny lobster Panulirus interruptus and the freshwater crayfish Pacifastacus leniusculus. Transglutaminase and Ca2+ also induced the VHDL to clot. Considering large amounts of VHDL in the hemolymph of sand crayfish, the VHDL not only functions as lipid carrier but plays an important role in the defense process of crustacea.

  3. 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.

  4. 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.

  5. 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

  6. Unidirectional transfer in vivo of high-density lipoprotein cholesteryl esters to lower-density lipoproteins in the pig, an animal species without plasma cholesteryl ester transfer activity.

    PubMed

    Terpstra, A H; Stucchi, A F; Foxall, T L; Shwaery, G T; Vespa, D B; Nicolosi, R J

    1993-12-01

    The metabolism of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesteryl esters (CE) was studied in the pig, an animal species without plasma cholesteryl ester transfer activity (CETA). In the first series of experiments, LDL and HDL from normocholesterolemic pigs were radiolabeled with cholesteryl (1-14C)oleate and intravenously administered to two groups of four normocholesterolemic pigs. Radioactive tracer in LDL remained associated with the LDL fraction, and there was no transfer of LDL-CE to HDL. The transport rate (which represents the production and disposal rate) of LDL-CE in normocholesterolemic pigs was 39 mumol CE/h/L. However, radiolabeled HDL-CE were transferred to LDL (25%), and 36% of the LDL-CE mass was derived from the HDL. The transport rate of HDL-CE was 54 mumol CE/h/L, and the flux of HDL-CE to LDL was 14 mumol CE/h/L. There was no accumulation of radiolabeled HDL-CE in very-low-density lipoprotein (VLDL), which suggests that there was no transfer to VLDL. However, this does not rule out the possibility that either the very low levels of VLDL-CE (< 0.09 mmol/L) or the rapid turnover rate of the VLDL pool might have prevented the accumulation of substantial amounts of tracer in VLDL. Therefore, in a second set of experiments, the kinetics of HDL-CE were studied in high-fat-and high-cholesterol-fed pigs with elevated VLDL-CE concentrations (1.92 mmol/L). Hypercholesterolemia was associated with increased transport rates of LDL-CE (165 mumol/h/L) and HDL-CE (78 mumol/h/L) and with an increased flux of HDL-CE to LDL (78 mumol/h/L).(ABSTRACT TRUNCATED AT 250 WORDS)

  7. 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.

  8. Severe hypertriglyceridemia, reduced high density lipoprotein, and neonatal death in lipoprotein lipase knockout mice. Mild hypertriglyceridemia with impaired very low density lipoprotein clearance in heterozygotes.

    PubMed Central

    Weinstock, P H; Bisgaier, C L; Aalto-Setälä, K; Radner, H; Ramakrishnan, R; Levak-Frank, S; Essenburg, A D; Zechner, R; Breslow, J L

    1995-01-01

    Lipoprotein lipase (LPL)-deficient mice have been created by gene targeting in embryonic stem cells. At birth, homozygous knockout pups have threefold higher triglycerides and sevenfold higher VLDL cholesterol levels than controls. When permitted to suckle, LPL-deficient mice become pale, then cyanotic, and finally die at approximately 18 h of age. Before death, triglyceride levels are severely elevated (15,087 +/- 3,805 vs 188 +/- 71 mg/dl in controls). Capillaries in tissues of homozygous knockout mice are engorged with chylomicrons. This is especially significant in the lung where marginated chylomicrons prevent red cell contact with the endothelium, a phenomenon which is presumably the cause of cyanosis and death in these mice. Homozygous knockout mice also have diminished adipose tissue stores as well as decreased intracellular fat droplets. By crossbreeding with transgenic mice expressing human LPL driven by a muscle-specific promoter, mouse lines were generated that express LPL exclusively in muscle but not in any other tissue. This tissue-specific LPL expression rescued the LPL knockout mice and normalized their lipoprotein pattern. This supports the contention that hypertriglyceridemia caused the death of these mice and that LPL expression in a single tissue was sufficient for rescue. Heterozygous LPL knockout mice survive to adulthood and have mild hypertriglyceridemia, with 1.5-2-fold elevated triglyceride levels compared with controls in both the fed and fasted states on chow, Western-type, or 10% sucrose diets. In vivo turnover studies revealed that heterozygous knockout mice had impaired VLDL clearance (fractional catabolic rate) but no increase in transport rate. In summary, total LPL deficiency in the mouse prevents triglyceride removal from plasma, causing death in the neonatal period, and expression of LPL in a single tissue alleviates this problem. Furthermore, half-normal levels of LPL cause a decrease in VLDL fractional catabolic rate and mild

  9. Platelet high-density lipoprotein activates transferrin-derived phagocytosis activators, MAPPs, following thrombin digestion.

    PubMed

    Sakamoto, Haruhiko; Wu, Bin; Nagai, Yumiko; Tanaka, Sumiko; Onodera, Masayuki; Ogawa, Takafumi; Ueno, Masaki

    2011-01-01

    Macromolecular activators of phagocytosis from platelets (MAPPs), transferrin-derived phagocytosis activators released from platelets, activate leukocytic phagocytosis via Fcγ receptors. It has been found that MAPPs can be prepared using stored platelets or their lysate. Using this artificial MAPP production system, it has been found that they can be produced from precursors (tetrameric and dimeric transferrins) following reaction with a low-molecular-weight (LMW) activator of MAPPs, which is liberated from a high-molecular-weight activator of MAPP (HMW activator) by reaction with thrombin. In this study, the HMW activator in platelet lysate was characterized by assaying phagocytosis of washed neutrophils. In an ultracentrifugation study of the platelet lysate, HMW activator activity was observed in the fraction corresponding to the density of high-density lipoprotein (HDL). The activity was observed in the apolipoproteins obtained from the HDL fraction. Among the apolipoproteins tested only apolipoprotein CIII showed the activity to produce MAPP in vitro. Affinity chromatography of the apolipoproteins from the HDL fraction of the platelet lysate using an anti-apolipoprotein CIII column revealed that the substance that binds with the antibody showed MAPP-forming activity. In a gel filtration study of thrombin-treated apolipoprotein CIII, a peak of LMW activator activity was observed for fractions with a molecular size smaller than that of apolipoprotein CIII. Finally, MAPP-forming activity of HDL obtained from the plasma was examined. MAPP was formed only when delipidized HDL was used. In conclusion, it is suggested that platelet HDL is the HMW activator and that this activation is achieved via apolipoprotein CIII after thrombin reaction in platelets.

  10. 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.

  11. [Beta amyloid in blood and cerebrospinal fluid is associated with high density lipoproteins].

    PubMed

    Kudinova, N V; Kudinov, A R; Berezov, T T

    1996-01-01

    Cerebrovascular and parenchymal amyloid deposits found in brains of Alzheimer's disease, Down's syndrome and normal aging are mainly composed of aggregated amyloid beta protein (A beta), a unique peptide 39 to 44 amino acids long. A similar but soluble A beta (s A beta) has been identified in plasma, cerebrospinal fluid (CSF) and cell supernatants, indicating that it is a normal protein. We report here that s A beta in normal human plasma and CSF is complexed to high density lipoprotein (HDL) 3 and very high density lipoprotein (VHDL). Biotinylated synthetic peptide A beta 1-40 was traced in normal human plasma in in vitro experiments. Both tracer biotin-labeled A beta 1-40 and native s A beta were specifically recovered in HDL3 and VHDL as it was assessed in immunoprecipitation experiments of purified plasma lipoproteins and lipoprotein depleted plasma. This fact prompted us to ascertain whether the interaction of s A beta with HDL does occur in normal human CSF in vivo. For this purpose normals human CSF was fractionated by means of sequential flotation ultracentrifugation. The presence of s A beta in the resulting lipoprotein fractions as well as in the lipoprotein depleted CSF was analysed by immunoblot analysis, electron and immune-electron microscopy and native size exclusion chromatography. Immunoblot analysis with 6E10 monoclonal anti-A beta antibodies revealed s A beta association with all HDL subspecies of CSF, primarily HDL3 and VHDL and immunoelectron microscopy confirmed an association of s A beta with CSF-HDL particles of 16.8 + 3.2 nm. Native size exclusion chromatography followed by immunoblot analysis with antibodies against A beta and different apoliproproteins indicated an association of s A beta with HDL complexes of approximately 200 kDa molecular weight. Soluble A beta association with HDL3 and VHDL may be involved in maintaining the solubility of A beta in biological fluids and points to a possible role of lipoproteins and lipoprotein lipid

  12. Site-directed lipid modification of IgG-binding protein by intracellular bacterial lipoprotein process.

    PubMed

    Shigematsu, H; Ebihara, T; Yanagida, Y; Haruyama, T; Kobatake, E; Aizawa, M

    1999-09-24

    IgG-binding protein was genetically expressed and lipid-modified in a site-directed manner in Escherichia coli. The DNA sequence encoding the signal peptide and the nine N-terminal amino acid residues of the major lipoprotein of E. coli (lpp) was fused to the sequence of B-domain which was one of the IgG binding domains of Staphylococcal Protein A (SpA). The N-terminal cysteine residue of the resulting protein was enzymatically linked with lipids in the bacterial membrane. The lipid-modified protein was translocated at the bacterial membrane in a manner similar to native bacterial lipoprotein, and it was purified with IgG-Sepharose by affinity chromatography. The lipid modified proteins (lppB1 and lppB5) showed a similar IgG binding activity to unmodified proteins, which was estimated by competitive ELISA. Proteoliposomes of lipid modified proteins were prepared in an elegant fashion so that the IgG binding site should be properly oriented on the surface of an individual liposome by anchoring the lipid-tail into the hydrophobic layer of the liposome membrane. As compared with the unmodified one, the lipid modified protein incorporated into the proteoliposome exhibited higher IgG binding activity.

  13. [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.

  14. Detection of haptoglobin in the high-density lipoprotein and the very high-density lipoprotein fractions from sera of calves with experimental pneumonia and cows with naturally occurring fatty liver.

    PubMed

    Katoh, N; Nakagawa, H

    1999-02-01

    In addition to the lipoprotein-deficient d > 1.25 fraction, haptoglobin was detected in the high-density lipoprotein (HDL) and the very high-density lipoprotein (VHDL) fractions from sera of calves with experimental pneumonia and cows with naturally occurring fatty liver. It was not found in the chylomicrons, very low-density lipoprotein and low-density lipoprotein fractions. Washing of the HDL fraction did not decrease the haptoglobin concentration. Transferrin and immunoglobulin G were immunoblotted to examine the possibility of contamination of the lipoprotein fractions by the d > 1.25 fraction. The two serum proteins were detected only in the d > 1.25 fraction, not in any lipoprotein fractions. The distribution pattern of haptoglobin in the lipoprotein fractions was distinct from that of serum albumin. Concentrations of haptoglobin in the HDL fractions from pneumonic sera were largely proportional to those in whole sera. Cholesteryl ester concentrations were decreased in sera from calves with pneumonia, as in cows with fatty liver. A protein immunologically related to hemoglobin was also detected in particular in the VHDL fractions from sera of both groups. These results suggest that haptoglobin or a complex with the hemoglobin-like protein may have a role or roles related to the lipid metabolism.

  15. Patients with Rheumatoid Arthritis Show Altered Lipoprotein Profiles with Dysfunctional High-Density Lipoproteins that Can Exacerbate Inflammatory and Atherogenic Process

    PubMed Central

    Kim, Jae-Yong; Lee, Eun-Young; Park, Jin Kyun; Song, Yeong Wook; Kim, Jae-Ryong; Cho, Kyung-Hyun

    2016-01-01

    Objective In order to identify putative biomarkers in lipoprotein, we compared lipid and lipoprotein properties between rheumatoid arthritis (RA) patients and control with similar age. Methods We analyzed four classes of lipoproteins (VLDL, LDL, HDL2, HDL3) from both male (n = 8, 69±4 year-old) and female (n = 25, 53±7 year-old) rheumatoid arthritis (RA) patients as well as controls with similar age (n = 13). Results Although RA group showed normal levels of total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, and glucose, however, the RA group showed significantly reduced high-density lipoprotein (HDL)-C level and ratio of HDL-C/TC. The RA group showed significantly elevated levels of blood triglyceride (TG), uric acid, and cholesteryl ester transfer protein (CETP) activity. The RA group also showed elevated levels of advanced glycated end (AGE) products in all lipoproteins and severe aggregation of apoA-I in HDL. As CETP activity and TG contents were 2-fold increased in HDL from RA group, paraoxonase activity was reduced upto 20%. Electron microscopy revealed that RA group showed much less HDL2 particle number than control. LDL from the RA group was severely oxidized and glycated with greater fragmentation of apo-B, especially in female group, it was more atherogenic via phagocytosis. Conclusion Lipoproteins from the RA patients showed severely altered structure with impaired functionality, which is very similar to that observed in coronary heart patients. These dysfunctional properties in lipoproteins from the RA patients might be associated with high incidence of cardiovascular events in RA patients. PMID:27736980

  16. Association of High-Density Lipoprotein Subclasses with Chronic Kidney Disease Progression, Atherosclerosis, and Klotho

    PubMed Central

    2016-01-01

    Background Atherosclerosis is often a complication of chronic kidney disease (CKD) because of dyslipidemia and CKD-mineral and bone disorder. High-density lipoproteins (HDLs) are grouped into various subclasses composed of multiple proteins and lipids, and their transformation is altered in CKD. We investigated the roles of lipoprotein subclasses in CKD progression, and atherosclerosis, and the relationships with Klotho and fibroblast growth factor (FGF) 23. Methods Seventy-one CKD patients were enrolled in this prospective cohort study in Japan. The proportions of cholesterol level to total cholesterol level (cholesterol proportion) and lipoprotein particle numbers in 20 lipoprotein fractions were measured by a newly developed high-performance gel permeation chromatography. Results Diabetic nephropathy was observed in 23.9% of the patients. The mean age was 75.0 years and estimated glomerular filtration rate (eGFR) was 17.2 ml/min./1.73m2. The lipoprotein particle numbers in small HDLs were higher in Stage 4 group than in Stage 5 group (p = 0.002). Multivariate regression analysis adjusted for baseline characteristics showed that the cholesterol proportions in very small HDLs were associated with eGFR change rate [F19 β = -17.63, p = 0.036] and ABI [F19 β = 0.047, p = 0.047] in Stage 4 group, and that serum soluble α-Klotho level was associated with the lipoprotein particle numbers in very small HDLs [F19 β = 0.00026, p = 0.012; F20 β = 0.00041, p = 0.036] in Stage 5 group. Conclusions This study showed that HDL subclasses are associated with CKD progression, ABI, and Klotho level in CKD-stage-specific manner. PMID:27861640

  17. Effect of oxidation on the structure of human low- and high-density lipoproteins.

    PubMed

    Oliveira, Cristiano L P; Santos, Priscila R; Monteiro, Andrea M; Figueiredo Neto, Antonio M

    2014-06-17

    This work presents a controlled study of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) structural changes due to in vitro oxidation with copper ions. The changes were studied by small-angle x-ray scattering (SAXS) and dynamic light scattering (DLS) techniques in the case of LDL and by SAXS, DLS, and Z-scan (ZS) techniques in the case of HDL. SAXS data were analyzed with a to our knowledge new deconvolution method. This method provides the electron density profile of the samples directly from the intensity scattering of the monomers. Results show that LDL particles oxidized for 18 h show significant structural changes when compared to nonoxidized particles. Changes were observed in the electrical density profile, in size polydispersity, and in the degree of flexibility of the APO-B protein on the particle. HDL optical results obtained with the ZS technique showed a decrease of the amplitude of the nonlinear optical signal as a function of oxidation time. In contrast to LDL results reported in the literature, the HDL ZS signal does not lead to a complete loss of nonlinear optical signal after 18 h of copper oxidation. Also, the SAXS results did not indicate significant structural changes due to oxidation of HDL particles, and DLS results showed that a small number of oligomers formed in the sample oxidized for 18 h. All experimental results for the HDL samples indicate that this lipoprotein is more resistant to the oxidation process than are LDL particles.

  18. Beta very low density lipoprotein and clathrin-coated vesicles co-localize to microvilli in pigeon monocyte-derived macrophages.

    PubMed Central

    Landers, S. C.; Jones, N. L.; Williams, A. S.; Lewis, J. C.

    1993-01-01

    Macrophages derived from blood monocytes are key in the development of atherosclerosis, as monocyte migration into the intima and accumulation of cholesterol leads to foam cell formation. To investigate the relationship between lipoprotein binding and the distribution of clathrin-coated endocytic vesicles, monocyte-derived macrophages were exposed in vitro to beta very low density lipoprotein (beta VLDL), conjugated to colloidal gold, and later were processed for immuno-electron microscopy to localize clathrin-coated vesicles. The immunolocalization was done in conjunction with either cryosectioning or whole mount intermediate voltage electron microscopy. Preferential binding of beta VLDL on small membrane ruffles and microvilli was quantitatively verified. Clathrin-coated vesicles were distributed throughout the cell; however, clusters of microvilli were associated with both a high concentration of coated vesicles and lipoprotein. Small membrane ruffles were not associated with clathrin-coated vesicles. These data support our hypothesis that endocytosis of beta VLDL near microvilli involves coated vesicles, whereas endocytosis of beta VLDL near ruffles is not mediated by coated endocytic vesicles. Furthermore, the association of coated vesicles with microvilli but not membrane ruffles may be important in understanding ligand trafficking within the cell. Given the distribution of coated vesicles within the cell, it is possible that the site of lipoprotein binding may determine the mechanism of entry into the cell and the metabolic effects of the internalized ligand. Images Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:8494058

  19. Targeted mutation of plasma phospholipid transfer protein gene markedly reduces high-density lipoprotein levels

    PubMed Central

    Jiang, Xian-cheng; Bruce, Can; Mar, Jefferson; Lin, Min; Ji, Yong; Francone, Omar L.; Tall, Alan R.

    1999-01-01

    It has been proposed that the plasma phospholipid transfer protein (PLTP) facilitates the transfer of phospholipids and cholesterol from triglyceride-rich lipoproteins (TRL) into high-density lipoproteins (HDL). To evaluate the in vivo role of PLTP in lipoprotein metabolism, we used homologous recombination in embryonic stem cells and produced mice with no PLTP gene expression. Analysis of plasma of F2 homozygous PLTP–/– mice showed complete loss of phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, and partial loss of free cholesterol transfer activities. Moreover, the in vivo transfer of [3H]phosphatidylcholine ether from very-low-density proteins (VLDL) to HDL was abolished in PLTP–/– mice. On a chow diet, PLTP–/– mice showed marked decreases in HDL phospholipid (60%), cholesterol (65%), and apo AI (85%), but no significant change in non-HDL lipid or apo B levels, compared with wild-type littermates. On a high-fat diet, HDL levels were similarly decreased, but there was also an increase in VLDL and LDL phospholipids (210%), free cholesterol (60%), and cholesteryl ester (40%) without change in apo B levels, suggesting accumulation of surface components of TRL. Vesicular lipoproteins were shown by negative-stain electron microscopy of the free cholesterol– and phospholipid-enriched IDL/LDL fraction. Thus, PLTP is the major factor facilitating transfer of VLDL phospholipid into HDL. Reduced plasma PLTP activity causes markedly decreased HDL lipid and apoprotein, demonstrating the importance of transfer of surface components of TRL in the maintenance of HDL levels. Vesicular lipoproteins accumulating in PLTP–/– mice on a high-fat diet could influence the development of atherosclerosis. PMID:10079112

  20. 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

  1. Drugs targeting high-density lipoprotein cholesterol for coronary artery disease management.

    PubMed

    Katz, Pamela M; Leiter, Lawrence A

    2012-01-01

    Many patients remain at high risk for future cardiovascular events despite levels of low-density lipoprotein cholesterol (LDL-C) at, or below, target while taking statin therapy. Much effort is therefore being focused on strategies to reduce this residual risk. High-density lipoprotein cholesterol (HDL-C) is a strong, independent, inverse predictor of coronary heart disease risk and is therefore an attractive therapeutic target. Currently available agents that raise HDL-C have only modest effects and there is limited evidence of additional cardiovascular risk reduction on top of background statin therapy associated with their use. It was hoped that the use of cholesteryl ester transfer protein (CETP) inhibitors would provide additional benefit, but the results of clinical outcome studies to date have been disappointing. The results of ongoing trials with other CETP inhibitors that raise HDL-C to a greater degree and also lower LDL-C, as well as with other emerging therapies are awaited.

  2. 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.

  3. 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

  4. 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

  5. [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.

  6. 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

  7. Lipid and apolipoprotein distribution as a function of density in equine plasma lipoprotein.

    PubMed

    Le Goff, D; Pastier, D; Hannan, Y; Petit, E; Ayrault-Jarrier, M; Nouvelot, A

    1989-01-01

    1. Equine lipoproteins were isolated from plasma by density gradient ultracentrifugation and apolipoprotein composition determined by SDS-polyacrylamide gel electrophoresis. 2. VLDL and IDL were present at low concentration (0.2 mg/ml). Two apoB components of Mr corresponding to human apoB-100 and one apoB-48-like component were represented in VLDL fraction. 3. LDL-1 and LDL-2 subfractions have displayed an almost equal concentration (0.4 mg/ml). Two apoB-100-like components were the major apolipoproteins in each fraction. Small amounts of apoB-48-like component were detectable in LDL-1 and LDL-2. 4. HDL-2 represented a major class of equine lipoproteins (1.8 mg/ml). ApoA-1-like component was the dominant protein in HDL-1, HDL-2 and HDL-3. Dimeric apoA-II-like components were slightly represented in HDL subfractions. 5. HDL-3 displayed the same apolipoprotein pattern as HDL-1 and HDL-2, but two further minor proteins of Mr 20,000 and 14,000 were detected. 6. VHDL represented a minor class of lipoprotein (0.2 mg/ml). ApoA-I-like component was the major apolipoprotein of VHDL. Small amounts of apoA-IV-like, apoE-like, and Mr 55,000 protein were detectable. 7. ApoC-like of Mr lower than 10,000 was represented in all equine lipoprotein classes.

  8. 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

  9. High-density lipoproteins induce a rapid and transient release of Ca2+ in cultured fibroblasts.

    PubMed

    Pörn, M I; Akerman, K E; Slotte, J P

    1991-10-01

    Several different cell types showed increased rates of proliferation and cholesterol mobilization in response to treatment with high-density lipoprotein (HDL). This would suggest that one main function of HDL is the activation of signal pathways in cells. In the current study we have used the fluorescent indicator fura-2 to monitor the level of cytosolic Ca2+ ([Ca2+]i) in human skin fibroblasts. Exposure of subconfluent as well as confluent fibroblasts to HDL3 (20-60 micrograms/ml) resulted in a rapid and transient increase in [Ca2+]i. Sequential additions of HDL3 resulted in diminished rises in [Ca2+]i. The transient rise in [Ca2+]i was observed with HDL prepared from plasma either by conventional ultracentrifugation or by precipitation with dextran sulphate. Chelation of the extracellular Ca2+ with EGTA prior to the addition of HDL3 did not prevent the HDL3-induced rise in [Ca2+]i, suggesting that the mobilized Ca2+ was derived mainly from intracellular stores. Covalent modification of the apoproteins of HDL3 with dimethyl suberimidate or tetranitromethane did not inhibit the HDL3-induced rise in [Ca2+]i. This indicates that the binding of HDL3 to cell surface receptors may not be necessary for the mobilization of intracellular Ca2+. Moreover, the Ca(2+)-releasing effect of HDL3 was not inhibited by the presence of albumin (1%, w/v) in the extracellular medium, suggesting that non-esterified fatty acids were not the cause of the increased [Ca2+]i. The exposure of fibroblasts to lysophosphatidic acid, a potent mitogen and Ca(2+)-releasing agent, before addition of HDL3 completely inhibited the HDL3-induced rise in [Ca2+]i. Furthermore, phorbol 12-myristate 13-acetate blocked the HDL3-induced rise in [Ca2+]i. The results of this study imply that exposure of cells to HDL generates an intracellular signal which is induced by a component of the lipid fraction.

  10. Direct Measurement of the Structure of Reconstituted High-Density Lipoproteins by Cryo-EM

    PubMed Central

    Murray, Stephen C.; Gillard, Baiba K.; Ludtke, Steven J.; Pownall, Henry J.

    2016-01-01

    Early forms of high-density lipoproteins (HDL), nascent HDL, are formed by the interaction of apolipoprotein AI with macrophage and hepatic ATP-binding cassette transporter member 1. Various plasma activities convert nascent to mature HDL, comprising phosphatidylcholine (PC) and cholesterol, which are selectively removed by hepatic receptors. This process is important in reducing the cholesterol burden of arterial wall macrophages, an important cell type in all stages of atherosclerosis. Interaction of apolipoprotein AI with dimyristoyl (DM)PC forms reconstituted (r)HDL, which is a good model of nascent HDL. rHDL have been used as an antiathersclerosis therapy that enhances reverse cholesterol transport in humans and animal models. Thus, identification of the structure of rHDL would inform about that of nascent HDL and how rHDL improves reverse cholesterol transport in an atheroprotective way. Early studies of rHDL suggested a discoidal structure, which included pairs of antiparallel helices of apolipoprotein AI circumscribing a phospholipid bilayer. Another rHDL model based on small angle neutron scattering supported a double superhelical structure. Herein, we report a cryo-electron microscopy-based model of a large rHDL formed spontaneously from apolipoprotein AI, cholesterol, and excess DMPC and isolated to near homogeneity. After reconstruction we obtained an rHDL structure comprising DMPC, cholesterol, and apolipoprotein AI (423:74:1 mol/mol) forming a discoidal particle 360 Å in diameter and 45 Å thick; these dimensions are consistent with the stoichiometry of the particles. Given that cryo-electron microscopy directly observes projections of individual rHDL particles in different orientations, we can unambiguously state that rHDL particles are protein bounded discoidal bilayers. PMID:26743047

  11. 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.

  12. 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

  13. [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.

  14. 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.

  15. Alpha slow-moving high-density-lipoprotein subfraction in serum of a patient with radiation enteritis and peritoneal carcinosis

    SciTech Connect

    Peynet, J.; Legrand, A.; Messing, B.; Thuillier, F.; Rousselet, F.

    1989-04-01

    An alpha slow-moving high-density-lipoprotein (HDL) subfraction was seen in a patient presenting with radiation enteritis and peritoneal carcinosis, who was given long-term cyclic parenteral nutrition. This subfraction, observed in addition to normal HDL, was precipitated with low-density lipoproteins (LDL) and very-low-density lipoproteins (VLDL) by sodium phosphotungstate-magnesium chloride. The patient's serum lipoproteins were analyzed after fractionation by density gradient ultracentrifugation. The alpha slow-moving HDL floated in the ultracentrifugation subfractions with densities ranging from 1.028 to 1.084 kg/L, and their main apolipoproteins included apolipoprotein E in addition to apolipoprotein A-I. These HDL were larger than HDL2. The pathogenesis of this unusual HDL subfraction is hypothesized.

  16. Proposed mechanisms for binding of apo[a] kringle type 9 to apo B-100 in human lipoprotein[a].

    PubMed Central

    Guevara, J; Spurlino, J; Jan, A Y; Yang, C Y; Tulinsky, A; Prasad, B V; Gaubatz, J W; Morrisett, J D

    1993-01-01

    The protein component of human lipoprotein[a] consists primarily of two apolipoproteins, apo[a] and apo B-100, linked through a cystine disulfide(s). In the amino acid sequence of apo bd, Cys4057 located within a plasminogen kringle 4-like repeat sequence (3991-4068) is believed to form a disulfide bond with a specific cysteine residue in apo B-100. Our fluorescence-labeling experiments and molecular modeling studies have provided evidence for possible interactions between this apo[a] kringle type and apo B-100. The fluorescent probe, fluorescein-5-maleimide, was used in parallel experiments to label free sulfhydryl moieties in lipoprotein[a] and low-density lipoprotein (LDL). In apo B-100 of LDL, Cys3734 was labeled with the probe, but this site was not labeled in autologous lipoprotein[a]. The result strongly implicates Cys3734 of apo B-100 as the residue forming the disulfide linkage with Cys4057 of apo[a]. To explore possible noncovalent interactions between apo B-100 and apo[a], the crystallographic coordinates for plasminogen kringle 4 were used to generate molecular models of the apo[a] kringle-repeat sequence (3991-4068, LPaK9), the only plasminogen kringle 4 type repeat in apo[a] having an extra cysteine residue not involved in an intramolecular disulfide bond. The Cys4057 residue (henceforth designated as Cys67 in the LPaK9 sequence) is believed to form an intermolecular disulfide bond with a cysteine of apo B-100. In computer graphics molecular models of LPaK9, Cys67 is located on the surface of the kringle near the lysine ligand binding site. Selected segments of the LDL apo B-100 sequence that contain free sulfhydryl cysteines were subjected to energy minimization and docking with the ligand binding site and adjacent regions of the LPaK9 model. In the docking experiments, apo B-100 segment 3732-3745 (PSCKLDFREIQIYK) displayed the best fit and the largest number of van der Waals contacts with models of LPaK9. Other apo B-100 peptides with sulfhydryl

  17. 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.

  18. Total and High-Density Lipoprotein Cholesterol in Adults: National Health and Nutrition Examination Survey, 2011-2012

    MedlinePlus

    ... Information Service NCHS Total and High-density Lipoprotein Cholesterol in Adults: National Health and Nutrition Examination Survey, ... 2012, 12.9% of adults had high total cholesterol, 17.4% had low HDL cholesterol, and 69. ...

  19. Single Step Reconstitution of Multifunctional High-Density Lipoprotein-Derived Nanomaterials Using Microfluidics

    PubMed Central

    Kim, YongTae; Fay, Francois; Cormode, David P.; Sanchez-Gaytan, Brenda L.; Tang, Jun; Hennessy, Elizabeth J.; Ma, Mingming; Moore, Kathryn; Farokhzad, Omid C.; Fisher, Edward Allen; Mulder, Willem J. M.; Langer, Robert; Fayad, Zahi A.

    2014-01-01

    High-density lipoprotein (HDL) is a natural nanoparticle that transports peripheral cholesterol to the liver. Reconstituted high-density lipoprotein (rHDL) exhibits antiatherothrombotic properties and is being considered as a natural treatment for cardiovascular diseases. Furthermore, HDL nanoparticle platforms have been created for targeted delivery of therapeutic and diagnostic agents. The current methods for HDL reconstitution involve lengthy procedures that are challenging to scale up. A central need in the synthesis of rHDL, and multifunctional nanomaterials in general, is to establish large-scale production of reproducible and homogeneous batches in a simple and efficient fashion. Here, we present a large-scale microfluidics-based manufacturing method for single-step synthesis of HDL-mimicking nanomaterials (µHDL). µHDL is shown to have the same properties (e.g., size, morphology, bioactivity) as conventionally reconstituted HDL and native HDL. In addition, we were able to incorporate simvastatin (a hydrophobic drug) into µHDL, as well as gold, iron oxide, quantum dot nanocrystals or fluorophores to enable its detection by computed tomography (CT), magnetic resonance imaging (MRI), or fluorescence microscopy, respectively. Our approach may contribute to effective development and optimization of lipoprotein-based nanomaterials for medical imaging and drug delivery. PMID:24079940

  20. 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.

  1. Immunohistochemical detection of a very high density lipoprotein (VHDL) in ovarian follicles of Triatoma infestans.

    PubMed

    González, M S; Ronderos, J R; Rimoldi, O J; Brenner, R R

    2001-04-01

    The ability of Triatoma infestans ovarian follicles to synthesize a very high-density lipoprotein (VHDL) has been examined by immunohistochemical methods. This kind of lipoprotein can be envisaged as a storage hexameric protein present in the hemolymph of some insect species. VHDL immunoreactivity is observed in oocytes at different stages of maturation. The antigen is present in the oocyte cytoplasm as well as in the follicular epithelial cells. The immunopositive reaction in the apical surface of follicle cells suggests both a VHDL synthesis and a secretion process. Furthermore, VHDL seems to be stored into oocyte in yolk granules. On the contrary, no immunopositive reaction is observed in the intracellular spaces between follicle cells, suggesting that VHDL is not incorporated from hemolymph into the oocyte.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. Effect of Oxidation on the Structure of Human Low- and High-Density Lipoproteins

    PubMed Central

    Oliveira, Cristiano L.P.; Santos, Priscila R.; Monteiro, Andrea M.; Figueiredo Neto, Antonio M.

    2014-01-01

    This work presents a controlled study of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) structural changes due to in vitro oxidation with copper ions. The changes were studied by small-angle x-ray scattering (SAXS) and dynamic light scattering (DLS) techniques in the case of LDL and by SAXS, DLS, and Z-scan (ZS) techniques in the case of HDL. SAXS data were analyzed with a to our knowledge new deconvolution method. This method provides the electron density profile of the samples directly from the intensity scattering of the monomers. Results show that LDL particles oxidized for 18 h show significant structural changes when compared to nonoxidized particles. Changes were observed in the electrical density profile, in size polydispersity, and in the degree of flexibility of the APO-B protein on the particle. HDL optical results obtained with the ZS technique showed a decrease of the amplitude of the nonlinear optical signal as a function of oxidation time. In contrast to LDL results reported in the literature, the HDL ZS signal does not lead to a complete loss of nonlinear optical signal after 18 h of copper oxidation. Also, the SAXS results did not indicate significant structural changes due to oxidation of HDL particles, and DLS results showed that a small number of oligomers formed in the sample oxidized for 18 h. All experimental results for the HDL samples indicate that this lipoprotein is more resistant to the oxidation process than are LDL particles. PMID:24940777

  8. Folded functional lipid-poor apolipoprotein A-I obtained by heating of high-density lipoproteins: relevance to high-density lipoprotein biogenesis.

    PubMed

    Jayaraman, Shobini; Cavigiolio, Giorgio; Gursky, Olga

    2012-03-15

    HDL (high-density lipoproteins) remove cell cholesterol and protect from atherosclerosis. The major HDL protein is apoA-I (apolipoprotein A-I). Most plasma apoA-I circulates in lipoproteins, yet ~5% forms monomeric lipid-poor/free species. This metabolically active species is a primary cholesterol acceptor and is central to HDL biogenesis. Structural properties of lipid-poor apoA-I are unclear due to difficulties in isolating this transient species. We used thermal denaturation of human HDL to produce lipid-poor apoA-I. Analysis of the isolated lipid-poor fraction showed a protein/lipid weight ratio of 3:1, with apoA-I, PC (phosphatidylcholine) and CE (cholesterol ester) at approximate molar ratios of 1:8:1. Compared with lipid-free apoA-I, lipid-poor apoA-I showed slightly altered secondary structure and aromatic packing, reduced thermodynamic stability, lower self-associating propensity, increased adsorption to phospholipid surface and comparable ability to remodel phospholipids and form reconstituted HDL. Lipid-poor apoA-I can be formed by heating of either plasma or reconstituted HDL. We propose the first structural model of lipid-poor apoA-I which corroborates its distinct biophysical properties and postulates the lipid-induced ordering of the labile C-terminal region. In summary, HDL heating produces folded functional monomolecular lipid-poor apoA-I that is distinct from lipid-free apoA-I. Increased adsorption to phospholipid surface and reduced C-terminal disorder may help direct lipid-poor apoA-I towards HDL biogenesis.

  9. 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.

  10. 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

  11. High-Density Lipoprotein Prevents Endoplasmic Reticulum Stress-Induced Downregulation of Liver LOX-1 Expression.

    PubMed

    Hong, Dan; Li, Ling-Fang; Gao, Hai-Chao; Wang, Xiang; Li, Chuan-Chang; Luo, Ying; Bai, Yong-Ping; Zhang, Guo-Gang

    2015-01-01

    Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a specific cell-surface receptor for oxidized-low-density lipoprotein (ox-LDL). The impact of high-density lipoprotein (HDL) on endoplasmic reticulum (ER) stress-mediated alteration of the LOX-1 level in hepatocytes remains unclear. We aimed to investigate the impact on LOX-1 expression by tunicamycin (TM)-induced ER stress and to determine the effect of HDL on TM-affected LOX-1 expression in hepatic L02 cells. Overexpression or silencing of related cellular genes was conducted in TM-treated cells. mRNA expression was evaluated using real-time polymerase chain reaction (PCR). Protein expression was analyzed by western blot and immunocytochemistry. Lipid uptake was examined by DiI-ox-LDL, followed by flow cytometric analysis. The results showed that TM induced the upregulation of ER chaperone GRP78, downregulation of LOX-1 expression, and lipid uptake. Knock down of IRE1 or XBP-1 effectively restored LOX-1 expression and improved lipid uptake in TM-treated cells. HDL treatment prevented the negative impact on LOX-1 expression and lipid uptake induced by TM. Additionally, 1-10 μg/mL HDL significantly reduced the GRP78, IRE1, and XBP-1 expression levels in TM-treated cells. Our findings reveal that HDL could prevent the TM-induced reduction of LOX-1 expression via inhibiting the IRE1/XBP-1 pathway, suggesting a new mechanism for beneficial roles of HDL in improving lipid metabolism.

  12. High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbits.

    PubMed

    Badimon, J J; Badimon, L; Galvez, A; Dische, R; Fuster, V

    1989-03-01

    The effects of in vivo administration of high density lipoprotein-very high density lipoprotein (HDL-VHDL) on the development of aortic fatty streaks were studied in cholesterol-fed rabbits. The rabbits received a 0.5% cholesterol-rich diet for 8 weeks. During this period, the HDL-VHDL group was intravenously administered with 50 mg/week of homologous HDL-VHDL protein; the control group received normal saline (0.9% NaCl). HDL-VHDL fraction was obtained at density range 1.063 to 1.25 gm/ml by ultracentrifugation of normal rabbit plasma. Along the study, plasma lipid levels followed a similar profile in both groups. At the completion of the study, atherosclerotic-like lipid-rich lesions covered 37.9 +/- 6% (X +/- SEM) of the intimal aortic surface in the control group, and 14.9 +/- 2.1% in the treated group (p less than 0.001). The values of total and free cholesterol, esterified cholesterol, and phospholipids deposited within vessel wall were significantly lower in the aortas of the HDL-VHDL treated group than those in the control group. Cholesterol accumulation in the livers was also significantly lower (p less than 0.01) in the treated group than in the control. We concluded that administration of homologous HDL-VHDL lipoprotein fraction to cholesterol-fed rabbits, dramatically inhibited the extent of aortic fatty streaks and lowered lipid deposition in the arterial wall and liver without modification of the plasma lipid levels.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Health benefits of high-density lipoproteins in preventing cardiovascular diseases.

    PubMed

    Berrougui, Hicham; Momo, Claudia N; Khalil, Abdelouahed

    2012-01-01

    Plasma levels of high-density lipoprotein (HDL) are strongly and inversely correlated with atherosclerotic cardiovascular diseases. However, it is becoming clear that a functional HDL is a more desirable target than simply increasing HDL-cholesterol levels. The best known antiatherogenic function of HDL particles relates to their ability to promote reverse cholesterol transport from peripheral cells. However, HDL also possesses antioxidant, anti-inflammatory, and antithrombotic effects. This review focuses on the state of knowledge regarding assays of HDL heterogeneity and function and their relationship to cardiovascular diseases.

  18. Nanocrystal core high-density lipoproteins: A multimodality contrast agent platform

    PubMed Central

    Cormode, David P.; Skajaa, Torjus; van Schooneveld, Matti M.; Koole, Rolf; Jarzyna, Peter; Lobatto, Mark E.; Calcagno, Claudia; Barazza, Alessandra; Gordon, Ronald E.; Zanzonico, Pat; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.

    2009-01-01

    High density lipoprotein (HDL), is an important natural nanoparticle that may be modified for biomedical imaging purposes. Here we developed a novel technique to create unique multimodality HDL mimicking nanoparticles by inclusion of gold, iron oxide or quantum dot nanocrystals for computed tomography, magnetic resonance and fluorescence imaging, respectively. By including additional labels in the corona of the particles, they were made multi-functional. The characterization of these nanoparticles, as well as their in vitro and in vivo behavior revealed that they closely mimic native HDL. PMID:18939808

  19. Nanocrystal core high-density lipoproteins: a multimodality contrast agent platform.

    PubMed

    Cormode, David P; Skajaa, Torjus; van Schooneveld, Matti M; Koole, Rolf; Jarzyna, Peter; Lobatto, Mark E; Calcagno, Claudia; Barazza, Alessandra; Gordon, Ronald E; Zanzonico, Pat; Fisher, Edward A; Fayad, Zahi A; Mulder, Willem J M

    2008-11-01

    High density lipoprotein (HDL) is an important natural nanoparticle that may be modified for biomedical imaging purposes. Here we developed a novel technique to create unique multimodality HDL mimicking nanoparticles by incorporation of gold, iron oxide, or quantum dot nanocrystals for computed tomography, magnetic resonance, and fluorescence imaging, respectively. By including additional labels in the corona of the particles, they were made multifunctional. The characteristics of these nanoparticles, as well as their in vitro and in vivo behavior, revealed that they closely mimic native HDL.

  20. 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.

  1. Synthetic high-density lipoprotein-like nanoparticles for cancer therapy

    PubMed Central

    Foit, Linda; Giles, Francis J.; Gordon, Leo I.; Thaxton, C. Shad

    2015-01-01

    Summary High-density lipoproteins (HDLs) are a diverse group of natural nanoparticles that are most well-known for their role in cholesterol transport. However, HDLs have diverse functions that provide significant opportunities for cancer therapy. Presented is a focused review of the ways that synthetic versions of HDL have been used as targeted therapies for cancer, and as vehicles for the delivery of diverse therapeutic cargo to cancer cells. As such, synthetic HDLs are likely to play a central role in the development of next generation cancer therapies. PMID:25487833

  2. 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

  3. Sterol carrier protein-2 alters high density lipoprotein-mediated cholesterol efflux.

    PubMed

    Atshaves, B P; Starodub, O; McIntosh, A; Petrescu, A; Roths, J B; Kier, A B; Schroeder, F

    2000-11-24

    Although sterol carrier protein-2 (SCP-2) participates in the uptake and intracellular trafficking of cholesterol, its effect on "reverse cholesterol transport" has not been explored. As shown herein, SCP-2 expression inhibited high density lipoprotein (HDL)-mediated efflux of [(3)H]cholesterol and fluorescent 22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3b-ol (NBD-cholesterol) up to 61 and 157%, respectively. Confocal microscopy of living cells allowed kinetic analysis of two intracellular pools of HDL-mediated NBD-cholesterol efflux: the highly fluorescent lipid droplet pool and the less fluorescent pool outside the lipid droplets, designated the cytoplasmic compartment. Both the whole cell and the cytoplasmic compartment exhibited two similar kinetic pools, the half-times of which were consistent with protein (t(b)(12) near 1 min) and vesicular (t(d)(12) = 10-20 min) mediated sterol transfer. Although SCP-2 expression did not alter cytoplasmic sterol pool sizes, the rapid t(b)(12) decreased 36%, while the slower t(d)(12) increased 113%. Lipid droplets also exhibited two kinetic pools of NBD-cholesterol efflux but with half-times over 200% shorter than those of the cytoplasmic compartment. The lipid droplet slower effluxing pool size and t(d)(12) were increased 48% and 115%, respectively, in SCP-2-expressing cells. Concomitantly, the level of the lipid droplet-specific adipose differentiation-related protein decreased 70%. Overall, HDL-mediated sterol efflux from L-cell fibroblasts reflected that of the cytoplasmic rather than lipid droplet compartment. SCP-2 differentially modulated sterol efflux from the two cytoplasmic pools. However, net efflux was determined primarily by inhibition of the slowly effluxing pool rather than by acceleration of the rapid protein-mediated pool. Finally, SCP-2 expression also inhibited sterol efflux from lipid droplets, an effect related to decreased adipose differentiation-related protein, a lipid

  4. Free cholesterol determines reassembled high-density lipoprotein phospholipid phase structure and stability.

    PubMed

    Auton, Matthew; Bassett, G Randall; Gillard, Baiba K; Pownall, Henry J

    2013-06-25

    Reassembled high-density lipoproteins (rHDL) of various sizes and compositions containing apo A-I or apo A-II as their sole protein, dimyristoylphosphatidylcholine (DMPC), and various amounts of free cholesterol (FC) have been isolated and analyzed by differential scanning calorimetry (DSC) and by circular dichroism to determine their stability and the temperature dependence of their helical content. Our data show that the multiple rHDL species obtained at each FC mole percent usually do not have the same FC mole percent as the starting mixture and that the size of the multiple species increases in a quantized way with their respective FC mole percent. DSC studies reveal multiple phases or domains that can be classified as virtual DMPC, which contains a small amount of DMPC that slightly reduces the melting temperature (Tm), a boundary phase that is adjacent to the apo A-I or apo A-II that circumscribes the discoidal rHDL, and a mixed FC/DMPC phase that has a Tm that increases with FC mole percent. Only the large rHDL contain virtual DMPC, whereas all contain boundary phase and various amounts of the mixed FC/DMPC phase according to increasing size and FC mole percent. As reported by others, FC stabilizes the rHDL. For rHDL (apo A-II) compared to rHDL (apo A-I), this occurs in spite of the reduced number of helical regions that mediate binding to the DMPC surface. This effect is attributed to the very high lipophilicity of apo A-II and the reduction in the polarity of the interface between DMPC and the aqueous phase with an increasing FC mole percent, an effect that is expected to increase the strength of the hydrophobic associations with the nonpolar face of the amphipathic helices of apo A-II. These data are relevant to the differential effects of FC and apolipoprotein species on intracellular and plasma membrane nascent HDL assembly and subsequent remodeling by plasma proteins.

  5. Triglyceride to high density lipoprotein cholesterol ratio, total cholesterol to high density lipoprotein cholesterol ratio and low ankle brachial index in an elderly population.

    PubMed

    Zhan, Yiqiang; Yu, Jinming; Ding, Rongjing; Sun, Yihong; Hu, Dayi

    2014-05-01

    Hintergrund: Der Zusammenhang zwischen den Quotienten aus Triglycerid (TG) und High-density-lipoprotein-cholesterin (HDL‑C) sowie Gesamtcholesterin (TC) und HDL‑C und dem Knöchel-Arm-Index (ABI) wurde selten untersucht. Patienten und Methoden: Insgesamt 2.982 Teinehmer, die über 60 Jahre alt waren, wurden für die bevölkerungsbasierte Querschnittstudie rekrutiert. TG, TC, HDL‑C, und low-density Lipoprotein Cholesterol (LDL-C) wurden bei allen Teilnehmern getestet. Ein niedriger ABI wurde als ABI ≤ 0.9 definiert. Multiple Regressionsmodelle wurden für die Untersuchung der Assoziation zwischen TG/HDL‑C Ratio und TC/HDL‑C Ratio und niedrigem ABI angewendet. Ergebnisse: Die TG/HDL‑C Ratios für ABI > 0.9 und ABI ≤ 0.9 waren 1.28 ± 1.20 und 1.48 ± 1.13 (P < 0.0001), während die TC/HDL‑C Ratios 3.96 ± 1.09 bzw. 4.32 ± 1.15 (P < 0.0001) waren. Nach der Angleichung von Alter, Geschlecht, Body-Mass-Index, Fettleibigkeit, Alkoholkonsum, köperliche Aktivität, Hypertonie, Diabetes, Einnahme von lipidsenkenden Medikamenten, und Herz-Kreislauf-Erkrankungen waren die Odds Ratios (OR) mit 95 % Konfidenzintervall (KI) bei dem niedrigen ABI und TG/HDL‑C Quotient 1,10 (0,96 - 1,26) und 1,34 (1,14 - 1,59) für TC/HDL‑C in der Nichtrauchergruppe. Wenn das TC weiter angeglichen wurde, waren die ORs (95 % CIs) 1.40 (0.79, 2.52) und 1.53 (1.21, 1.93) für die TG/HDL‑C Ratio und TC/HDL‑C Ratio. Nichtlineare Zusammenhänge wurden zwischen der TG/HDL‑C Ratio und TC/HDL‑C Ratio und dem niedrigen ABI in der Raucher- und Nichtrauchergruppe entdeckt. Schlussfolgerungen: Die TC/HDL‑C Ratio war signifikant mit einem niedrigen ABI in der Nichtrauchergruppe verbunden und die Assoziation war unabhängig von TC, TG, HDL‑C und LDL-C. TC/HDL‑C könnte als potentieller Biomarker für die frühe periphere arterielle Verschlusskrankheit beim Screening berücksichtigt werden.

  6. 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.

  7. Human lipoprotein binding to schistosomula of schistosoma mansoni. Displacement by polyanions, parasite antigen masking, and persistence in young larvae.

    PubMed Central

    Chiang, C. P.; Caulfield, J. P.

    1989-01-01

    It was previously shown by the authors that the binding of human low-density lipoprotein (LDL) to the surface of schistosomula inhibits the binding of human anti-schistosomal antibodies and is inhibited by suramin. Here, three questions were considered. 1) Are LDLs bound to schistosomula displaced from the membrane by polyanions? 2) Does bound LDL mask or hide antigens recognized by human anti-schistosomal antibodies? 3) Is LDL, binding capability present when the larvae enter the blood stream? The first question was tested by measuring the percentage of the schistosomular surface membrane covered by LDL after exposure to LDL with or without dextran sulfate or suramin. The bound LDL was visualized with polyclonal goat anti-human apolipoprotein B (anti-apo B) antibodies and peroxidase-conjugated secondary antibodies. After overnight culture in 20 micrograms/300 microliters LDL, 84.0% +/- 0.3% of the parasite surface was covered by LDL reaction product. When the polyanions suramin or dextran sulfate were added to the cultures for 30 minutes, only 59.7% +/- 4.9% of the surface was covered by reaction product, demonstrating that the LDL was partially displaced from the membrane by these compounds. The second question was tested by measuring the binding of human and mouse monoclonal anti-schistosomal antibodies before and after exposure to LDL, with or without partial removal of the bound LDL by suramin. LDL partially inhibited antibody binding in a reversible fashion. The LDL clearly masked parasite antigens, most probably by steric hindrance. However, there may be competitive inhibition of antibody binding by the LDL as well, because human anti-schistosomal antibodies inhibited LDL binding to worms and both human anti-schistosomal antibody and LDL binding to schistosomula were inhibited by suramin. Finally, the third question was tested by quantitative immunofluorescence. The LDL binding capability persisted and nearly doubled by 72 hours after transformation from

  8. High-Density Lipoprotein Mimetics: a Therapeutic Tool for Atherosclerotic Diseases.

    PubMed

    Ikenaga, Masahiro; Higaki, Yasuki; Saku, Keijiro; Uehara, Yoshinari

    2016-01-01

    Clinical trials and epidemiological studies have revealed a negative correlation between serum high-density lipoprotein (HDL) cholesterol levels and the risk of cardiovascular events. Currently, statin treatment is the standard therapy for cardiovascular diseases, reducing plasma low-density lipoprotein (LDL) cholesterol levels. However, more than half of the patients have not been able to receive the beneficial effects of this treatment.The reverse cholesterol transport pathway has several potential anti-atherogenic properties. An important approach to HDL-targeted therapy is the optimization of HDL cholesterol levels and function in the blood to enhance the removal of circulating cholesterol and to prevent or mitigate inflammation that causes atherosclerosis. Cholesteryl ester transfer protein inhibitors increase HDL cholesterol levels in humans, but whether they reduce the risk of atherosclerotic diseases is unknown. HDL therapies using HDL mimetics, including reconstituted HDL, apolipoprotein (Apo) A-IMilano, ApoA-I mimetic peptides, or full-length ApoA-I, are highly effective in animal models. In particular, the Fukuoka University ApoA-I-mimetic peptide (FAMP) effectively removes cholesterol via the ABCA1 transporter and acts as an anti-atherosclerotic agent by enhancing the biological functions of HDL without elevating HDL cholesterol levels.Our literature review suggests that HDL mimetics have significant atheroprotective potential and are a therapeutic tool for atherosclerotic diseases.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  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. 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

  16. Changes in remnant and high-density lipoproteins associated with hormone therapy and progression of coronary artery disease in postmenopausal women

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of hormone therapy (HT) on the plasma concentration of remnant lipoprotein cholesterol (RLP-C) and high density lipoprotein (HDL) subpopulations and the contribution of HT-related changes in these lipoproteins to the progression of coronary heart disease (CHD) were examined in 256 postmen...

  17. Reduced adipose tissue lipoprotein lipase responses, postprandial lipemia, and low high-density lipoprotein-2 subspecies levels in older athletes with silent myocardial ischemia.

    PubMed

    Katzel, L I; Busby-Whitehead, M J; Rogus, E M; Krauss, R M; Goldberg, A P

    1994-02-01

    Healthy older (64 +/- 1 years, mean +/- SEM) athletic (maximal oxygen consumption [VO2max] > 40 mL/kg/min) normocholesterolemic men with no prior history of coronary artery disease (CAD) were recruited for cardiovascular and metabolic studies. Thirty-three percent had asymptomatic exercise-induced ST segment depression on their exercise electrocardiogram (ECG), consistent with silent myocardial ischemia (SI). We hypothesized that abnormalities in high-density lipoprotein (HDL) and postprandial triglyceride (TG) metabolism may increase their risk for CAD. Compared with 12 nonischemic controls of comparable age, percent body fat, and VO2max, the 13 men with SI had decreased fasting HDL cholesterol ([HDL-C] 41 +/- 2 v 50 +/- 2 mg/dL, P < .001) and %HDL2b subspecies levels as measured by gradient gel electrophoresis (22 +/- 2 v 34 +/- 3, P < .001). Fasting plasma TG and low-density lipoprotein cholesterol (LDL-C) levels were the same in both groups. Although plasma glucose levels during an oral glucose tolerance test (OGTT) were similar in both groups, the total insulin area was higher in men with SI (P < .05). After consumption of a standard high-fat meal (680 kcal/m2 body surface area of a formula in which 86% of the calories were derived from fat), postprandial plasma TG, chylomicron-TG, and very-low-density lipoprotein (VLDL)-TG levels and postprandial areas were higher in men with SI (P < .001).(ABSTRACT TRUNCATED AT 250 WORDS)

  18. A high-fat diet and the threonine-encoding allele (Thr54) polymorphism of fatty acid–binding protein 2 reduce plasma triglyceride–rich lipoproteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Thr54 allele of the fatty acid binding protein 2 (FABP2) DNA polymorphism is associated with increased triglyceride-rich lipoproteins and insulin resistance. We investigated whether the triglyceride-rich lipoprotein response to diets of varied fat content is affected by the fatty acid binding pr...

  19. 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

  20. 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...

  1. Should we take high-density lipoprotein cholesterol levels at face value?

    PubMed

    Leite, Jose Oyama; Fernandez, Maria Luz

    2010-01-01

    The inverse correlation between high-density lipoprotein (HDL) levels and cardiovascular disease has driven several investigators to target the increase in this lipoprotein to prevent atherosclerosis and its complications. However, many reports have demonstrated that the use of HDL cholesterol (HDL-C) levels as a means to prevent and treat atherosclerosis has mainly resulted in negative outcomes. These findings may help to increase our knowledge of HDL metabolism and its protective effect. There is evidence that the mechanism by which HDL-C levels are raised has a great impact on cardiovascular outcomes. When the increase in HDL-C levels is secondary to greater synthesis, a strong beneficial effect in the prevention of cardiovascular diseases is observed. Even small increases in HDL-C levels induce a marked reduction in cardiovascular events; this has been observed during treatment with fibrates. In contrast, when the increase in HDL-C levels is secondary to a reduction in HDL catabolism, unexpectedly, the opposite effects are usually noted. Even dramatic increases in HDL-C levels are not associated with better cardiovascular outcomes. In fact, these increases have been related to a greater number of cardiovascular-related deaths. This became clear from the results of trials that tested inhibitors of cholesteryl ester transfer protein (CETP). We suggest that increases in reverse cholesterol transport are more important than HDL-C levels. Strong evidence is provided by individuals that express apolipoprotein (apo)A-I Milano. These individuals have extremely low HDL-C levels due to greater catabolism of the lipoprotein. However, reverse cholesterol transport is increased in these individuals and, as a consequence, they have a low incidence of cardiovascular diseases. We reinforce that, in clinical practice, the currently recommended levels of HDL-C should still be a major target to be aimed for. However, in the research field, we emphasize the need to look for other

  2. Structural Insights into High Density Lipoprotein: Old Models and New Facts

    PubMed Central

    Gogonea, Valentin

    2016-01-01

    The physiological link between circulating high density lipoprotein (HDL) levels and cardiovascular disease is well-documented, albeit its intricacies are not well-understood. An improved appreciation of HDL function and overall role in vascular health and disease requires at its foundation a better understanding of the lipoprotein's molecular structure, its formation, and its process of maturation through interactions with various plasma enzymes and cell receptors that intervene along the pathway of reverse cholesterol transport. This review focuses on summarizing recent developments in the field of lipid free apoA-I and HDL structure, with emphasis on new insights revealed by newly published nascent and spherical HDL models constructed by combining low resolution structures obtained from small angle neutron scattering (SANS) with contrast variation and geometrical constraints derived from hydrogen–deuterium exchange (HDX), crosslinking mass spectrometry, electron microscopy, Förster resonance energy transfer, and electron spin resonance. Recently published low resolution structures of nascent and spherical HDL obtained from SANS with contrast variation and isotopic labeling of apolipoprotein A-I (apoA-I) will be critically reviewed and discussed in terms of how they accommodate existing biophysical structural data from alternative approaches. The new low resolution structures revealed and also provided some answers to long standing questions concerning lipid organization and particle maturation of lipoproteins. The review will discuss the merits of newly proposed SANS based all atom models for nascent and spherical HDL, and compare them with accepted models. Finally, naturally occurring and bioengineered mutations in apoA-I, and their impact on HDL phenotype, are reviewed and discuss together with new therapeutics employed for restoring HDL function. PMID:26793109

  3. 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

  4. 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.

  5. 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

  6. Superparamagnetic reconstituted high-density lipoprotein nanocarriers for magnetically guided drug delivery

    PubMed Central

    Sabnis, Sarika; Sabnis, Nirupama A; Raut, Sangram; Lacko, Andras G

    2017-01-01

    Current cancer chemotherapy is frequently associated with short- and long-term side effects, affecting the quality of life of cancer survivors. Because malignant cells are known to overexpress specific surface antigens, including receptors, targeted drug delivery is often utilized to reduce or overcome side effects. The current study involves a novel targeting approach using specifically designed nanoparticles, including encapsulation of the anti-cancer drug valrubicin into superparamagnetic iron oxide nanoparticle (SPION) containing reconstituted high-density lipoprotein (rHDL) nanoparticles. Specifically, rHDL–SPION–valrubicin hybrid nanoparticles were assembled and characterized with respect to their physical and chemical properties, drug entrapment efficiency and receptor-mediated release of the drug valrubicin from the nanoparticles to prostate cancer (PC-3) cells. Prussian blue staining was used to assess nanoparticle movement in a magnetic field. Measurements of cytotoxicity toward PC-3 cells showed that rHDL–SPION–valrubicin nanoparticles were up to 4.6 and 31 times more effective at the respective valrubicin concentrations of 42.4 µg/mL and 85 µg/mL than the drug valrubicin alone. These studies showed, for the first time, that lipoprotein drug delivery enhanced via magnetic targeting could be an effective chemotherapeutic strategy for prostate cancer. PMID:28260891

  7. 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.

  8. 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.

  9. Serum Paraoxonase 1 Activity Is Associated with Fatty Acid Composition of High Density Lipoprotein

    PubMed Central

    Boshtam, Maryam; Pourfarzam, Morteza; Ani, Mohsen; Naderi, Gholam Ali; Basati, Gholam; Mansourian, Marjan; Dinani, Narges Jafari; Asgary, Seddigheh; Abdi, Soheila

    2013-01-01

    Introduction. Cardioprotective effect of high density lipoprotein (HDL) is, in part, dependent on its related enzyme, paraoxonase 1 (PON1). Fatty acid composition of HDL could affect its size and structure. On the other hand, PON1 activity is directly related to the structure of HDL. This study was designed to investigate the association between serum PON1 activity and fatty acid composition of HDL in healthy men. Methods. One hundred and forty healthy men participated in this research. HDL was separated by sequential ultracentrifugation, and its fatty acid composition was analyzed by gas chromatography. PON1 activity was measured spectrophotometrically using paraxon as substrate. Results. Serum PON1 activity was directly correlated with the amount of stearic acid and dihomo-gamma-linolenic acid (DGLA). PON1/HDL-C was directly correlated with the amount of miristic acid, stearic acid, and DGLA and was inversely correlated with total amount of ω6 fatty acids of HDL. Conclusion. The fatty acid composition of HDL could affect the activity of its associated enzyme, PON1. As dietary fats are the major determinants of serum lipids and lipoprotein composition, consuming some special dietary fatty acids may improve the activity of PON1 and thereby have beneficial effects on health. PMID:24167374

  10. High density lipoproteins: Measurement techniques and potential biomarkers of cardiovascular risk

    PubMed Central

    Hafiane, Anouar; Genest, Jacques

    2015-01-01

    Plasma high density lipoprotein cholesterol (HDL) comprises a heterogeneous family of lipoprotein species, differing in surface charge, size and lipid and protein compositions. While HDL cholesterol (C) mass is a strong, graded and coherent biomarker of cardiovascular risk, genetic and clinical trial data suggest that the simple measurement of HDL-C may not be causal in preventing atherosclerosis nor reflect HDL functionality. Indeed, the measurement of HDL-C may be a biomarker of cardiovascular health. To assess the issue of HDL function as a potential therapeutic target, robust and simple analytical methods are required. The complex pleiotropic effects of HDL make the development of a single measurement challenging. Development of laboratory assays that accurately HDL function must be developed validated and brought to high-throughput for clinical purposes. This review discusses the limitations of current laboratory technologies for methods that separate and quantify HDL and potential application to predict CVD, with an emphasis on emergent approaches as potential biomarkers in clinical practice. PMID:26674734

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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

  17. 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

  18. A fibrinogen-binding lipoprotein contributes to the virulence of Haemophilus ducreyi in humans.

    PubMed

    Bauer, Margaret E; Townsend, Carisa A; Doster, Ryan S; Fortney, Kate R; Zwickl, Beth W; Katz, Barry P; Spinola, Stanley M; Janowicz, Diane M

    2009-03-01

    A gene expression study of Haemophilus ducreyi identified the hypothetical lipoprotein HD0192, renamed here "fibrinogen binder A" (FgbA), as being preferentially expressed in vivo. To test the role played by fgbA in virulence, an isogenic fgbA mutant (35000HPfgbA) was constructed using H. ducreyi 35000HP, and 6 volunteers were experimentally infected with 35000HP or 35000HPfgbA. The overall pustule-formation rate was 61.1% at parent sites and 22.2% at mutant sites (P = .019). Papules were significantly smaller at mutant sites than at parent sites (13.3 vs. 37.9 mm(2); P = .002) 24 h after inoculation. Thus, fgbA contributed significantly to the virulence of H. ducreyi in humans. In vitro experiments demonstrated that fgbA encodes a fibrinogen-binding protein; no other fibrinogen-binding proteins were identified in 35000HP. fgbA was conserved among clinical isolates of both class I and II H. ducreyi strains, supporting the finding that fgbA is important for H. ducreyi infection.

  19. 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.

  20. High density lipoprotein: it’s not just about lipid transport anymore

    PubMed Central

    Gordon, Scott M.; Hofmann, Susanna; Askew, David S.; Davidson, W. Sean

    2011-01-01

    Plasma levels of high density lipoprotein cholesterol (HDL-C) have long been associated with protection against cardiovascular disease (CVD) in large populations. However, HDL-C has been significantly less useful for predicting CVD risk in individual patients. This has ignited a new debate on the merits of measuring HDL quantity versus quality in terms of protective potential. In addition, numerous recent studies have begun to uncover HDL functions that vary surprisingly from traditional lipid transport roles. In this paper, we review recent findings that point to important functions for HDL that go well beyond lipid transport. These discoveries suggest that HDL might be a platform that mediates protection from a host of disease states ranging from CVD to diabetes to infectious disease. PMID:21067941

  1. High density lipoprotein and metabolic disease: Potential benefits of restoring its functional properties

    PubMed Central

    Klancic, Teja; Woodward, Lavinia; Hofmann, Susanna M.; Fisher, Edward A.

    2016-01-01

    Background High density lipoproteins (HDLs) are thought to be atheroprotective and to reduce the risk of cardiovascular disease (CVD). Besides their antioxidant, antithrombotic, anti-inflammatory, anti-apoptotic properties in the vasculature, HDLs also improve glucose metabolism in skeletal muscle. Scope of the review Herein, we review the functional role of HDLs to improve metabolic disorders, especially those involving insulin resistance and to induce regression of CVD with a particular focus on current pharmacological treatment options as well as lifestyle interventions, particularly exercise. Major conclusions Functional properties of HDLs continue to be considered important mediators to reverse metabolic dysfunction and to regress atherosclerotic cardiovascular disease. Lifestyle changes are often recommended to reduce the risk of CVD, with exercise being one of the most important of these. Understanding how exercise improves HDL function will likely lead to new approaches to battle the expanding burden of obesity and the metabolic syndrome. PMID:27110484

  2. 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.

  3. Newer therapeutic strategies to alter high-density lipoprotein level and function.

    PubMed

    Bosch, Nicholas; Frishman, William H

    2014-01-01

    Measurements of low levels of high-density lipoprotein (HDL) cholesterol have been identified as a risk factor for premature coronary artery disease, however, to date, current pharmacologic approaches for raising HDL have provided little benefit, if at all, in reducing cardiovascular outcomes. It has been shown that HDL can modify many aspects of plaque pathogenesis. Its most established role is in reverse cholesterol transportation, but HDL can also affect oxidation, inflammation, cellular adhesion, and vasodilatation. Considering these potential benefits of HDL, newer treatments have been developed to modify HDL activity, which include the use of oral cholesteryl ester transfer protein inhibitors, apolipoprotein (apo)A-I infusions, apoA-I mimetics, drugs to increase apoA-I synthesis, and agonists of the liver X receptor. These new therapies are reviewed in this article.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. High-Density Lipoprotein - A Hero, a Mirage, or a Witness?

    PubMed

    Sviridov, Dmitri

    2014-01-01

    Negative relationship between plasma high-density lipoprotein (HDL) levels and risk of cardiovascular disease (CVD) is a firmly established medical fact, but attempts to reproduce protective properties of HDL by pharmacologically elevating HDL levels were mostly unsuccessful. This conundrum presents a fundamental question: were the approaches used to raise HDL flawed or the protective effects of HDL are an epiphenomenon? Recent attempts to elevate plasma HDL were universally based on reducing HDL catabolism by blocking reverse cholesterol transport (RCT). Here, we argue that this mode of HDL elevation may be mechanistically different to natural mechanisms and thus be counterproductive. We further argue that independently of whether HDL is a driving force or a surrogate measure of the rate of RCT, approaches aimed at increasing HDL supply, rather than reducing its catabolism, would be most beneficial for speeding up RCT and improving protection against CVD.

  10. A disposable electrochemical sensor based on protein G for High-Density Lipoprotein (HDL) detection.

    PubMed

    Chammem, H; Hafaid, I; Bohli, N; Garcia, A; Meilhac, O; Abdelghani, A; Mora, L

    2015-11-01

    In this work, two biosensors were developed for the detection of High-Density Lipoproteins (HDL) particles, which are biomarkers inversely correlated with cardiovascular risk and which represent therapeutic targets for atherosclerosis. The electrochemical properties of the grafted antibody on interdigitated gold electrode were achieved by Impedance Spectroscopy (IS). The used deposition method was based on oriented antibody Anti-ApoA1 with an intermediate thin layer of protein G. The developed biosensor was able to detect both native plasma HDL and reconstituted HDL (rHDL) particles respectively with the detection limit of 50n g/mL and 1 ng/mL, respectively. Dynamic contact angle and atomic force microscopy were used. The developed biosensors are able to differentiate the HDL particles according to their differences in size and interactions with the immobilized antibody.

  11. Conformational Changes in High-Density Lipoprotein Nanoparticles Induced by High Payloads of Paramagnetic Lipids

    PubMed Central

    2016-01-01

    High-density lipoprotein (HDL) nanoparticles doped with gadolinium lipids can be used as magnetic resonance imaging diagnostic agents for atherosclerosis. In this study, HDL nanoparticles with different molar fractions of gadolinium lipids (0 < xGd-lipids < 0.33) were prepared, and the MR relaxivity values (r1 and r2) for all compositions were measured. Both r1 and r2 parameters reached a maximal value at a molar fraction of approximately xGd-lipids = 0.2. Higher payloads of gadolinium did not significantly increase relaxivity values but induced changes in the structure of HDL, increasing the size of the particles from dH = 8.2 ± 1.6 to 51.7 ± 7.3 nm. High payloads of gadolinium lipids trigger conformational changes in HDL, with potential effects on the in vivo behavior of the nanoparticles. PMID:27713933

  12. Antiatherogenic role of high-density lipoproteins: insights from genetically engineered-mice.

    PubMed

    Escola-Gil, Joan Carles; Calpe-Berdiel, Laura; Palomer, Xavier; Ribas, Vicent; Ordonez-Llanos, Jordi; Blanco-Vaca, Francisco

    2006-05-01

    Plasma levels of high-density lipoprotein (HDL) cholesterol are inversely correlated with the incidence of atherosclerotic cardiovascular disease. The cardioprotective effects of HDL have been attributed to its role in reverse cholesterol transport (RCT) and especially the macrophage-dependent RCT, and also to the antioxidant properties of HDL as well as its direct effects on endothelial function. However, few of these effects have been verified in vivo in humans. With the creation and detailed analysis of genetically-engineered mice, a solid body of new information has emerged on the mechanisms controlling these key antiatherogenic functions of HDL and their effects on atherogenesis. This article provides a review of new insights into the molecular mechanisms underlying these three most studied antiatherogenic functions of HDL in vivo with a focus on genetically-engineered mice.

  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. Antibodies toward high-density lipoprotein components inhibit paraoxonase activity in patients with systemic lupus erythematosus.

    PubMed

    Batuca, J R; Ames, P R J; Isenberg, D A; Alves, J Delgado

    2007-06-01

    Patients with systemic lupus erythematosus (SLE) have an increased incidence of vascular disease, and oxidative stress is recognized as an important feature in this condition, despite the underlying mechanisms not being fully understood. In these patients, an interaction between lipoproteins and the immune system has been suggested, but most studies have only looked at antibodies against oxidized low-density lipoproteins. This study was undertaken to determine the presence of antibodies directed against high-density lipoproteins (HDL) and to identify a possible association between these antibodies and paraoxonase (PON), an antioxidant enzyme present in HDL. Plasma from 55 patients with SLE was collected and IgG aHDL and antiapolipoprotein A-I (aApo A-I) antibodies were assessed by enzyme-linked immunosorbent assay. Standardization of the method was performed in a control population of 150 healthy subjects. Plasma levels above 5 standard deviations of the mean of the control population were considered positive. PON activity was assessed by quantification of p-nitrophenol formation (micromol/mL/min). Patients with SLE had higher titers of aHDL (P < 0.0001) and aApo A-I (P < 0.0001) antibodies, and lower PON activity (P < 0.0001) than healthy controls. There was also a direct correlation between the titers of aHDL and aApo A-I antibodies (r = 0.61; P < 0.0001). PON activity was inversely correlated with aApo A-I (P = 0.0129) antibody levels. Anti-HDL and aApo A-I antibodies from patients with high titers were isolated and subsequently incubated with human HDL. These antibodies reduced PON activity up to a maximum of 70.2% and 78.4%, respectively. This study showed the presence of aHDL and aApo A-I antibodies in patients with SLE. These antibodies were associated with reduced PON activity in plasma, and the in vitro inhibition assay confirmed a direct inhibition of the enzyme activity.

  19. The Complex Fate in Plasma of Gadolinium Incorporated into High-Density Lipoproteins Used for Magnetic Imaging of Atherosclerotic Plaques

    PubMed Central

    Barazza, Alessandra; Blachford, Courtney; Even-Or, Orli; Joaquin, Victor A.; Briley-Saebo, Karen C.; Chen, Wei; Jiang, Xian-Cheng; Mulder, Willem J. M.; Cormode, David P.; Fayad, Zahi A.; Fisher, Edward A.

    2014-01-01

    We have previously reported enhancing the imaging of atherosclerotic plaques in mice using reconstituted high density lipoproteins (HDL) as nanocarriers for the MRI contrast agent gadolinium (Gd). This study focuses on the underlying mechanisms of Gd delivery to atherosclerotic plaques. HDL, LDL, and VLDL particles containing Gd chelated to phosphatidyl ethanolamine (DTPA-DMPE) and a lipidic fluorophore were used to demonstrate the transfer of Gd-phospholipids among plasma lipoproteins in vitro and in vivo. To determine the basis of this transfer, the roles of phospholipid transfer protein (PLTP) and lipoprotein lipase (LpL) in mediating the migration of Gd-DTPA-DMPE among lipoproteins were investigated. The results indicated that neither was an important factor, suggesting that spontaneous transfer of Gd-DTPA-DMPE was the most probable mechanism. Finally, two independent mouse models were used to quantify the relative contributions of HDL and LDL reconstituted with Gd-DTPA-DMPE to plaque imaging enhancement by MR. Both sets of results suggested that Gd-DTPA-DMPE originally associated with LDL was about twice as effective as that injected in the form of Gd-HDL, and that some of Gd-HDL’s effectiveness in vivo is indirect through transfer of the imaging agent to LDL. In conclusion, the fate of Gd-DTPA-DMPE associated with a particular type of lipoprotein is complex, and includes its transfer to other lipoprotein species that are then cleared from the plasma into tissues. PMID:23617731

  20. 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

  1. Paradoxical Elevation of High Density Lipoprotein Cholesterol in Association with Lacunar-Type Cerebral Infarction

    PubMed Central

    Meng, Gui-Lin; Tan, Yan; Fang, Min; Yang, Hong-Yan; Liu, Xue-Yuan; Zhao, Yan-Xin

    2015-01-01

    Background The aim of this study was to evaluate the association between high-density lipoprotein cholesterol (HDLC) levels and the risk of lacunar infarction (LI) in a retrospective cohort study in China. Material/Methods We recruited 229 patients with obsolete brain infarctions single side (SOBI), 218 with obsolete brain infarctions bilateral sides (BOBI), 193 with both acute stroke and obsolete lacunar infarctions single side (AI&SOBI), 113 with both acute stroke and obsolete lacunar infarctions bilateral sides (AI&BOBI), and 203 without any infarctions (Control). Results 1) The plasma levels of HDLC in group BOBI, AI&SOBI, and AI&BOBI were higher than in the control group, and lower in group SOBI than in the control group (p<0.01). 2) The plasma levels of HDLC in group AI&SOBI were significantly higher than in group SOBI (p<0.01). 3) The plasma levels of HLDL were similar between group AI&SOBI and AI&BOBI. 4) There were significant relationships between HDLC and acute lacunar stroke, even after adjusting for these factors such as age, sex, triglyceride, total cholesterol, low-density lipoprotein cholesterol, and history of diabetes (p=0.001). 4) Compared with the controls, the calculation of odds ratios indicated relative risk estimates of higher HDLC for acute lacunar stroke with obsolete lacunar infarction. Conclusions Elevated HDLC may be an independent predictor of recurrent stroke with obsolete lacunar infarctions single side in Chinese people, justifying clinical trials for secondary prevention of stroke by generally increasing HLDL level. According to the difference between single and bilateral side multiple silent lacunar infarcts, it is inferred that HDLC may increase the risk of atherothrombotic infarction but reduce the risk of cardioembolic infarction in the general Chinese population. PMID:26120926

  2. Lipid traffic between high density lipoproteins and Plasmodium falciparum-infected red blood cells

    PubMed Central

    1991-01-01

    Several intraerythrocytic growth cycles of Plasmodium falciparum could be achieved in vitro using a serum free medium supplemented only with a human high density lipoprotein (HDL) fraction (d = 1.063-1.210). The parasitemia obtained was similar to that in standard culture medium containing human serum. The parasite development was incomplete with the low density lipoprotein (LDL) fraction and did not occur with the VLDL fraction. The lipid traffic from HDL to the infected erythrocytes was demonstrated by pulse labeling experiments using HDL loaded with either fluorescent NBD-phosphatidylcholine (NBD-PC) or radioactive [3H]palmitoyl-PC. At 37 degrees C, the lipid probes rapidly accumulated in the infected cells. After incubation in HDL medium containing labeled PC, a subsequent incubation in medium with either an excess of native HDL or 20% human serum induced the disappearance of the label from the erythrocyte plasma membrane but not from the intraerythrocytic parasite. Internalization of lipids did not occur at 4 degrees C. The mechanism involved a unidirectional flux of lipids but no endocytosis. The absence of labeling of P. falciparum, with HDL previously [125I]iodinated on their apolipoproteins or with antibodies against the apolipoproteins AI and AII by immunofluorescence and immunoblotting, confirmed that no endocytosis of the HDL was involved. A possible pathway of lipid transport could be a membrane flux since fluorescence videomicroscopy showed numerous organelles labeled with NBD-PC moving between the erythrocyte and the parasitophorous membranes. TLC analysis showed that a partial conversion of the PC to phosphatidylethanolamine was observed in P. falciparum-infected red cells after pulse with [3H]palmitoyl-PC-HDL. The intensity of the lipid traffic was stage dependent with a maximum at the trophozoite and young schizont stages (38th h of the erythrocyte life cycle). We conclude that the HDL fraction appears to be a major lipid source for Plasmodium

  3. 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.

  4. High-density Lipoprotein Particle Concentration and Subclinical Atherosclerosis of the Carotid Arteries in Japanese Men

    PubMed Central

    Zaid, Maryam; Fujiyoshi, Akira; Miura, Katsuyuki; Abbott, Robert D.; Okamura, Tomonori; Takashima, Naoyuki; Torii, Sayuki; Saito, Yoshino; Hisamatsu, Takashi; Miyagawa, Naoko; Ohkubo, Takayoshi; Kadota, Aya; Sekikawa, Akira; Maegawa, Hiroshi; Nakamura, Yasuyuki; Mitsunami, Kenichi; Ueshima, Hirotsugu

    Objective The association of high-density lipoprotein particle (HDL-P) with atherosclerosis may be stronger than that of HDL-cholesterol (HDL-C) and independent of conventional cardiovascular risk factors. Whether associations persist in populations at low risk of coronary heart disease (CHD) remains unclear. This study examines the associations of HDL-P and HDL-C with carotid intima-media thickness (cIMT) and plaque counts among Japanese men, who characteristically have higher HDL-C levels and a lower CHD burden than those in men of Western populations. Methods We cross-sectionally examined a community-based sample of 870 Japanese men aged 40-79 years, free of known clinical cardiovascular disease (CVD) and not on lipid-lowering medication. Participants were randomly selected among Japanese living in Kusatsu City in Shiga, Japan. Results Both HDL-P and HDL-C were inversely and independently associated with cIMT in models adjusted for conventional CHD risk factors, including low-density lipoprotein cholesterol (LDL-C) and diabetes. HDL-P maintained an association with cIMT after further adjustment for HDL-C (P<0.01), whereas the association of HDL-C with cIMT was noticeably absent after inclusion of HDL-P in the model. In plaque counts of the carotid arteries, HDL-P was significantly associated with a reduction in plaque count, whereas HDL-C was not. Conclusion HDL-P, in comparison to HDL-C, is more strongly associated with measures of carotid atherosclerosis in a cross-sectional study of Japanese men. Findings demonstrate that, HDL-P is a strong correlate of subclinical atherosclerosis even in a population at low risk for CHD. PMID:25687270

  5. 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

  6. 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

  7. Purification and properties of a very high density lipoprotein from the hemolymph of the honeybee Apis mellifera.

    PubMed

    Shipman, B A; Ryan, R O; Schmidt, J O; Law, J H

    1987-04-07

    A larval-specific very high density lipoprotein (VHDL) has been isolated from the hemolymph of the honeybee Apis mellifera. VHDL was isolated by a combination of density gradient ultracentrifugation and gel filtration. The purified protein is a dimer of Mr 160,000 apoproteins as shown by chemical cross-linking with dimethyl suberimidate. N-Terminal sequence analysis indicates that the two polypeptide chains are identical. The holoprotein contains 10% lipid by weight and 2.6% covalently bound carbohydrate. A native Mr 330,000 species was obtained by gel permeation chromatography. Antiserum directed against VHDL was used to show that VHDL is distinct from other hemolymph proteins and appears to constitute a novel lipoprotein of unknown function. However, the lipoprotein is present in high amounts in hemolymph only at the end of larval life, suggesting a potential role in lipid transport and/or storage protein metabolism during metamorphosis.

  8. Effects of an evidence-based computerized virtual clinician on low-density lipoprotein and non-high-density lipoprotein cholesterol in adults without cardiovascular disease: The Interactive Cholesterol Advisory Tool.

    PubMed

    Block, Robert C; Abdolahi, Amir; Niemiec, Christopher P; Rigby, C Scott; Williams, Geoffrey C

    2016-12-01

    There is a lack of research on the use of electronic tools that guide patients toward reducing their cardiovascular disease risk. We conducted a 9-month clinical trial in which participants who were at low (n = 100) and moderate (n = 23) cardiovascular disease risk-based on the National Cholesterol Education Program III's 10-year risk estimator-were randomized to usual care or to usual care plus use of an Interactive Cholesterol Advisory Tool during the first 8 weeks of the study. In the moderate-risk category, an interaction between treatment condition and Framingham risk estimate on low-density lipoprotein and non-high-density lipoprotein cholesterol was observed, such that participants in the virtual clinician treatment condition had a larger reduction in low-density lipoprotein and non-high-density lipoprotein cholesterol as their Framingham risk estimate increased. Perceptions of the Interactive Cholesterol Advisory Tool were positive. Evidence-based information about cardiovascular disease risk and its management was accessible to participants without major technical challenges.

  9. 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

  10. 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

  11. 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.

  12. Comparative models for human apolipoprotein A-I bound to lipid in discoidal high-density lipoprotein particles.

    PubMed

    Klon, Anthony E; Segrest, Jere P; Harvey, Stephen C

    2002-09-10

    We have constructed a series of models for apolipoprotein A-I (apo A-I) bound to discoidal high-density lipoprotein (HDL) particles, based upon the molecular belt model [Segrest, J. P., et al. (1999) J. Biol. Chem. 274, 31755-31758] and helical hairpin models [Rogers, D. P., et al. (1998) Biochemistry 37, 11714-11725], and compared these with picket fence models [Phillips, J. C., et al. (1997) Biophys. J. 73, 2337-2346]. Molecular belt models for discoidal HDL particles with differing diameters are presented, illustrating that the belt model can explain the discrete changes in HDL particle size observed experimentally. Hairpin models are discussed for the binding of apo A-I to discoidal HDL particles with diameters identical to those for the molecular belt model. Two models are presented for the binding of three monomers of apo A-I to a 150 A diameter discoidal HDL particle. In one model, two monomers of apo A-I bind to the exterior of the HDL particle in an antiparallel belt, with a third monomer of apo A-I bound to the disk in a hairpin conformation. In the second model, all three monomers of apo A-I are bound to the discoidal HDL particle in a hairpin conformation. Previously published experimental data for each model are reviewed, with FRET favoring either the belt or hairpin models over the picket fence models for HDL particles with diameters of 105 A. Naturally occurring mutations appear to favor the belt model for the 105 A particles, while the 150 A HDL particles favor the presence of at least one hairpin.

  13. 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.

  14. 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.

  15. Characterization of Lipid Composition and High-Density Lipoprotein Function in HIV-Infected Individuals on Stable Antiretroviral Regimens

    PubMed Central

    Munger, Alana M.; Chow, Dominic C.; Playford, Martin P.; Parikh, Nisha I.; Gangcuangco, Louie Mar A.; Nakamoto, Beau K.; Kallianpur, Kalpana J.; Ndhlovu, Lishomwa C.; Shikuma, Cecilia M.

    2015-01-01

    Abstract There is an increase in the cardiovascular disease (CVD) morbidity in individuals infected with HIV that may be due to inflammatory lipid modulation not captured by traditional lipid measures. The objective of this study was to perform advanced lipoprotein phenotyping inclusive of the high-density lipoprotein (HDL) cholesterol efflux capacity and lipoprotein particle concentration and size in a well-phenotyped group of 118 patients infected with HIV. We used simple and multivariable analyses to determine the associations between advanced lipoprotein parameters and known cardiometabolic risk factors. Participants were on stable antiretroviral therapy (ART) and had benign traditional lipid panels [median total cholesterol, low-density lipoprotein (LDL)-C, HDL-C, and triglycerides of 178 mg/dl, 108 mg/dl, 44 mg/dl, and 122.5 mg/dl, respectively]. However, advanced lipoprotein phenotyping demonstrated an elevation of LDL particle number (median of 1,233 nmol/liter) and a decrease in LDL size (median of 20.4 nm), along with a decrease in protective, large HDL particles (median of 3.15 μmol/liter) and reduced HDL cholesterol efflux capacity in comparison to controls of other studies. HDL cholesterol efflux capacity was associated with HDL levels (β=0.395, p<0.001), small LDL particle concentration (β=–0.198, p=0.031), insulin sensitivity by the Matsuda index (β=0.218, p=0.029), and the Framingham Risk Score (β=–0.184, p=0.046). We demonstrate an atherogenic lipoprotein profile by NMR spectroscopy and HDL efflux measurement in a group of HIV-infected patients on stable ART with normal lipid panels. PMID:25416403

  16. 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

  17. Physical inactivity interacts with an endothelial lipase polymorphism to modulate high density lipoprotein cholesterol in the GOLDN study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    BACKGROUND: Plasma high density lipoprotein (HDL) cholesterol (HDL-C) concentration is highly heritable but is also modifiable by environmental factors including physical activity. HDL-C response to exercise varies among individuals, and this variability may be associated with genetic polymorphism...

  18. 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...

  19. Comparing fluorescence-based cell-free assays for the assessment of antioxidative capacity of high-density lipoproteins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Population studies have shown an inverse association between high-density lipoprotein (HDL) cholesterol levels and risk of coronary heart disease (CHD). HDL has different functions, including the ability to protect biological molecules from oxidation. Our aim was to evaluate the performa...

  20. 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

  1. 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.

  2. Steroid hormone 20-hydroxyecdysone regulation of the very-high-density lipoprotein (VHDL) receptor phosphorylation for VHDL uptake.

    PubMed

    Dong, Du-Juan; Liu, Wen; Cai, Mei-Juan; Wang, Jin-Xing; Zhao, Xiao-Fan

    2013-04-01

    During the metamorphic stage of holometabolous insects, the biosynthetic precursors needed for the synthesis of a large number of adult proteins are acquired from the selective absorption of storage proteins. The very-high-density lipoprotein (VHDL), a non-hexameric storage protein, is consumed by the fat body from the hemolymph through VHDL receptor (VHDL-R)-mediated endocytosis. However, the mechanism of the uptake of VHDL by a VHDL-R remains unclear. In this study, a VHDL-R from Helicoverpa armigera was found to be involved in 20E-regulated VHDL uptake through the regulation of steroid hormone 20-hydroxyecdysone (20E). The transcripts of VHDL-R were detected mainly in the fat body and integument during the wandering stage. The transcription of VHDL-R was upregulated by 20E through the ecdysteroid receptor (EcRB1) and Ultraspiracle (USP1). In addition, 20E stimulates the phosphorylation of VHDL-R through protein kinase C for ligand binding. VHDL-R knockdown in larvae results the inhibition of development to adulthood. These data imply that 20E regulates VHDL-R on both transcriptional and posttranslational levels for VHDL absorption.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. High-density lipoprotein cholesterol as a predictor of poor survival in patients with nasopharyngeal carcinoma

    PubMed Central

    Liu, Li-Na; Bao, Liu-Bin; Tang, Lin-Quan; Ou, Jing-Song; Liu, Zhi-Gang; Chen, Xiao-Zhong; Xu, Yan; Ma, Jun; Chan, Anthony T.; Chen, Ming; Xia, Yun-Fei; Liu, Wan-Li; Zeng, Yi-Xin; Mai, Hai-Qiang; Zeng, Mu-Sheng; Pan, Jian-Ji; Zhang, Xing

    2016-01-01

    Purpose We aimed to assess the prognostic value of pretreatment high density lipoprotein cholesterol (HDL-C) levels in patients with nasopharyngeal carcinoma (NPC) and investigate the possible biological effects of these lipoproteins on NPC cells in vitro. Experimental Design We examined the prognostic value of pretreatment HDL-C levels in 2443 patients with non-metastatic NPC from three independent institutions. The Cox proportional hazard model and log-rank test were used to analyze the correlation between HDL-C levels and overall survival (OS). Cell growth, colony formation, and apoptotic assays were used to determine the biological functions of HDL on NPC cells in vitro. All of the statistical tests were two-sided. Results OS was decreased in patients with high pretreatment HDL-C levels compared with those with low HDL-C levels (P < 0.05). Similarly, a decreased OS was noted in advanced stage (stage III-IV), NPC patients with high pretreatment HDL-C levels (P < 0.01). Multivariate analyses indicated that HDL-C was an independent prognostic factor associated with shorter OS in training cohorts. These findings were confirmed in both independent validation cohorts (P < 0.01). In vitro experiments demonstrated that HDL could increase cell proliferation, invasion, and colony formation, which were largely dependent on the expression of its receptor SR-B1. Finally, HDL could enhance chemoresistance by protecting cancer cells from apoptosis. Conclusions Pretreatment HDL-C is a poor prognostic factor for patients with NPC. This effect may be associated with the ability of HDL to enhance proliferation, colony formation, migration, and chemoresistance in NPC cells. PMID:27304186

  9. 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.

  10. The apolipoprotein(a) component of lipoprotein(a) mediates binding to laminin: contribution to selective retention of lipoprotein(a) in atherosclerotic lesions.

    PubMed

    D'Angelo, Angela; Geroldi, Diego; Hancock, Mark A; Valtulina, Viviana; Cornaglia, Antonia I; Spencer, Craig A; Emanuele, Enzo; Calligaro, Alberto; Koschinsky, Marlys L; Speziale, Pietro; Visai, Livia

    2005-02-21

    Lipoprotein(a) [Lp(a)] entrapment by vascular extracellular matrix may be important in atherogenesis. We sought to determine whether laminin, a major component of the basal membrane, may contribute to Lp(a) retention in the arterial wall. First, immunohistochemistry experiments were performed to examine the relative distribution of Lp(a) and laminin in human carotid artery specimens. There was a high degree of co-localization of Lp(a) and laminin in atherosclerotic specimens, but not in non-atherosclerotic sections. We then studied the binding interaction between Lp(a) and laminin in vitro. ELISA experiments showed that native Lp(a) particles and 17K and 12K recombinant apolipoprotein(a) [r-apo(a)] variants interacted strongly with laminin whereas LDL, apoB-100, and the truncated KIV(6-P), KIV(8-P), and KIV(9-P) r-apo(a) variants did not. Overall, the ELISA data demonstrated that Lp(a) binding to laminin is mediated by apo(a) and a combination of the lysine analogue epsilon-aminocaproic acid and salt effectively decreases apo(a) binding to laminin. Secondary binding analyses with 125I-labeled r-apo(a) revealed equilibrium dissociation constants (K(d)) of 180 and 360 nM for the 17K and 12K variants binding to laminin, respectively. Such similar K(d) values between these two r-apo(a) variants suggest that isoform size does not appear to influence apo(a) binding to laminin. In summary, our data suggest that laminin may bind to apo(a) in the atherosclerotic intima, thus contributing to the selective retention of Lp(a) in this milieu.

  11. Lipoprotein marker for hypertriglyceridemia

    DOEpatents

    Cubicciotti, Roger S.; Karu, Alexander E.; Krauss, Ronald M.

    1986-01-01

    Methods and compositions are provided for the detection of a particular low density lipoprotein which has been found to be a marker for patients suffering from type IV hypertriglyceridemia. A monoclonal antibody capable of specifically binding to a characteristic epitopic site on this LDL subspecies can be utilized in a wide variety of immunoassays. Hybridoma cell line SPL.IVA5A1 was deposited at the American Type Culture Collection on Mar. 29, 1984, and granted accession no. HB 8535.

  12. Apolipoprotein A-I structural organization in high density lipoproteins isolated from human plasma

    PubMed Central

    Huang, Rong; Gangani D. Silva, R. A.; Jerome, W. Gray; Kontush, Anatol; Chapman, M. John; Curtiss, Linda K.; Hodges, Timothy J.; Davidson, W. Sean

    2010-01-01

    High density lipoproteins (HDL) mediate cholesterol transport and protection from cardiovascular disease. Although synthetic HDLs have been studied for 30 years, the structure of human plasma-derived HDL, and its major protein apolipoprotein (apo)A-I, is unknown. We separated normal human HDL into 5 density subfractions and then further isolated those containing predominantly apoA-I (LpA-I). Using cross-linking chemistry and mass spectrometry, we found that apoA-I adopts a structural framework in these particles that closely mirrors that in synthetic HDL. We adapted established structural models for synthetic HDL to generate the first detailed models of authentic human plasma HDL in which apoA-I adopts a symmetrical cage-like structure. The models suggest that HDL particle size is modulated via a twisting motion of the resident apoA-I molecules. This understanding offers insights into how apoA-I structure modulates HDL function and its interactions with other apolipoproteins. PMID:21399642

  13. 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

  14. Bone and high-density lipoprotein: The beginning of a beautiful friendship

    PubMed Central

    Papachristou, Dionysios J; Blair, Harry C

    2016-01-01

    There is a tight link between bone and lipid metabolic pathways. In this vein, several studies focused on the exploration of high-density lipoprotein (HDL) in the pathobiology of bone diseases, with emphasis to the osteoarthritis (OA) and osteoporosis, the most common bone pathologies. Indeed, epidemiological and in vitro data have connected reduced HDL levels or dysfunctional HDL with cartilage destruction and OA development. Recent studies uncovered functional links between HDL and OA fueling the interesting hypothesis that OA could be a chronic element of the metabolic syndrome. Other studies have linked HDL to bone mineral density. Even though at epidemiological levels the results are conflicting, studies in animals as well as in vitro experiments have shown that HDL facilitates osteoblastogensis and bone synthesis and most probably affects osteoclastogenesis and osteoclast bone resorption. Notably, reduced HDL levels result in increased bone marrow adiposity affecting bone cells function. Unveiling the mechanisms that connect HDL and bone/cartilage homeostasis may contribute to the design of novel therapeutic agents for the improvement of bone and cartilage quality and thus for the treatment of related pathological conditions. PMID:26925377

  15. 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)

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Multiple Hepatic Regulatory Variants at the GALNT2 GWAS Locus Associated with High-Density Lipoprotein Cholesterol.

    PubMed

    Roman, Tamara S; Marvelle, Amanda F; Fogarty, Marie P; Vadlamudi, Swarooparani; Gonzalez, Arlene J; Buchkovich, Martin L; Huyghe, Jeroen R; Fuchsberger, Christian; Jackson, Anne U; Wu, Ying; Civelek, Mete; Lusis, Aldons J; Gaulton, Kyle J; Sethupathy, Praveen; Kangas, Antti J; Soininen, Pasi; Ala-Korpela, Mika; Kuusisto, Johanna; Collins, Francis S; Laakso, Markku; Boehnke, Michael; Mohlke, Karen L

    2015-12-03

    Genome-wide association studies (GWASs) have identified more than 150 loci associated with blood lipid and cholesterol levels; however, the functional and molecular mechanisms for many associations are unknown. We examined the functional regulatory effects of candidate variants at the GALNT2 locus associated with high-density lipoprotein cholesterol (HDL-C). Fine-mapping and conditional analyses in the METSIM study identified a single locus harboring 25 noncoding variants (r(2) > 0.7 with the lead GWAS variants) strongly associated with total cholesterol in medium-sized HDL (e.g., rs17315646, p = 3.5 × 10(-12)). We used luciferase reporter assays in HepG2 cells to test all 25 variants for allelic differences in regulatory enhancer activity. rs2281721 showed allelic differences in transcriptional activity (75-fold [T] versus 27-fold [C] more than the empty-vector control), as did a separate 780-bp segment containing rs4846913, rs2144300, and rs6143660 (49-fold [AT(-) haplotype] versus 16-fold [CC(+) haplotype] more). Using electrophoretic mobility shift assays, we observed differential CEBPB binding to rs4846913, and we confirmed this binding in a native chromatin context by performing chromatin-immunoprecipitation (ChIP) assays in HepG2 and Huh-7 cell lines of differing genotypes. Additionally, sequence reads in HepG2 DNase-I-hypersensitivity and CEBPB ChIP-seq signals spanning rs4846913 showed significant allelic imbalance. Allelic-expression-imbalance assays performed with RNA from primary human hepatocyte samples and expression-quantitative-trait-locus (eQTL) data in human subcutaneous adipose tissue samples confirmed that alleles associated with increased HDL-C are associated with a modest increase in GALNT2 expression. Together, these data suggest that at least rs4846913 and rs2281721 play key roles in influencing GALNT2 expression at this HDL-C locus.

  2. 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

  3. 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

  4. Dietary Resistant Starch Supplementation Increases High-Density Lipoprotein Particle Number in Pigs Fed a Western Diet.

    PubMed

    Rideout, Todd C; Harding, Scott V; Raslawsky, Amy; Rempel, Curtis B

    2017-05-04

    Resistant starch (RS) has been well characterized for its glycemic control properties; however, there is little consensus regarding the influence of RS on blood lipid concentrations and lipoprotein distribution and size. Therefore, this study aimed to characterize the effect of daily RS supplementation in a controlled capsule delivery on biomarkers of cardiovascular (blood lipids, lipoproteins) and diabetes (glucose, insulin) risk in a pig model. Twelve 8-week-old male Yorkshire pigs were placed on a synthetic Western diet and randomly divided into two groups (n = 6/group) for 30 days: (1) a placebo group supplemented with capsules containing unmodified pre-gelatinized potato starch (0 g/RS/day); and (2) an RS group supplemented with capsules containing resistant potato starch (10 g/RS/day). Serum lipids including total-cholesterol (C), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides did not differ (p > 0.05) between the RS and placebo groups. Although the total numbers of very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) particles were similar (p > 0.05) between the two groups, total high-density lipoprotein (HDL) particles were higher (+28%, p < 0.05) in the RS group compared with placebo, resulting from an increase (p < 0.05) in the small HDL subclass particles (+32%). Compared with the placebo group, RS supplementation lowered (p < 0.05) fasting serum glucose (-20%) and improved (p < 0.05) insulin resistance as estimated by Homeostatic Model Assessment-Insulin Resistance (HOMA-IR) without a change in insulin. Additionally, total serum glucagon-like-peptide 1 (GLP-1) was higher (+141%, p < 0.05) following RS supplementation compared with placebo. This data suggests that in addition to the more well-characterized effect of RS intake in lowering blood glucose and improving insulin sensitivity, the consumption of RS may be beneficial in lipid management strategies by enhancing total

  5. Elevated High-Density Lipoprotein Cholesterol and Age-Related Macular Degeneration: The Alienor Study

    PubMed Central

    Cougnard-Grégoire, Audrey; Delyfer, Marie-Noëlle; Korobelnik, Jean-François; Rougier, Marie-Bénédicte; Le Goff, Mélanie; Dartigues, Jean-François; Barberger-Gateau, Pascale; Delcourt, Cécile

    2014-01-01

    Background Lipid metabolism and particularly high-density lipoprotein (HDL) may be involved in the pathogenic mechanism of age-related macular degeneration (AMD). However, conflicting results have been reported in the associations of AMD with plasma HDL and other lipids, which may be confounded by the recently reported associations of AMD with HDL-related genes. We explored the association of AMD with plasma lipid levels and lipid-lowering medication use, taking into account most of HDL-related genes associated with AMD. Methods The Alienor study is a population-based study on age-related eye diseases performed in 963 elderly residents of Bordeaux (France). AMD was graded from non mydriatic color retinal photographs in three exclusive stages: no AMD (n = 430 subjects, 938 eyes); large soft distinct drusen and/or large soft indistinct drusen and/or reticular drusen and/or pigmentary abnormalities (early AMD, n = 176, 247); late AMD (n = 40, 61). Associations of AMD with plasma lipids (HDL, total cholesterol (TC), Low-density lipoprotein (LDL), and triglycerides (TG)) were estimated using Generalized Estimating Equation logistic regressions. Statistical analyses included 646 subjects with complete data. Results After multivariate adjustment for age, sex, educational level, smoking, BMI, lipid-lowering medication use, cardiovascular disease and diabetes, and for all relevant genetic polymorphisms (ApoE2, ApoE4, CFH Y402H, ARMS2 A69S, LIPC rs10468017, LIPC rs493258, LPL rs12678919, ABCA1 rs1883025 and CETP rs3764261), higher HDL was significantly associated with an increased risk of early (OR = 2.45, 95%CI: 1.54–3.90; P = 0.0002) and any AMD (OR = 2.29, 95%CI: 1.46–3.59; P = 0.0003). Association with late AMD was far from statistical significance (OR = 1.58, 95%CI: 0.48–5.17; p = 0.45). No associations were found for any stage of AMD with TC, LDL and TG levels, statin or fibrate drug use. Conclusions This study suggests that

  6. The soluble form of Alzheimer's amyloid beta protein is complexed to high density lipoprotein 3 and very high density lipoprotein in normal human plasma.

    PubMed

    Koudinov, A; Matsubara, E; Frangione, B; Ghiso, J

    1994-12-15

    The amyloid fibrils of Alzheimer's neuritic plaques and cerebral blood vessels are mainly composed of aggregated forms of a 39 to 44 amino acids peptide, named amyloid beta (A beta). A similar although soluble form of A beta (sA beta) has been identified in plasma, cerebrospinal fluid and cell culture supernatants, indicating that it is produced under physiologic conditions. We report here that sA beta in normal human plasma is associated with lipoprotein particles, in particular to the HDL3 and VHDL fractions where it is complexed to ApoJ and, to a lesser extent, to ApoAI. This was assessed by immunoprecipitation experiments of purified plasma lipoproteins and lipoprotein-depleted plasma and confirmed by means of amino acid sequence analysis. Moreover, biotinylated synthetic peptide A beta 1-40 was traced in normal human plasma in in vitro experiments. As in the case of sA beta, biotinylated A beta 1-40 was specifically recovered in the HDL3 and VHDL fractions. This data together with the previous demonstration that A beta 1-40 is taken up into the brain via a specific mechanism and possibly as an A beta 1-40-ApoJ complex indicate a role for HDL3- and VHDL-containing ApoJ in the transport of the peptide in circulation and suggest their involvement in the delivery of sA beta across the blood-brain barrier.

  7. 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...

  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. [A history and review of cholesterol ester transfer protein inhibitors and their contribution to the understanding of the physiology and pathophysiology of high density lipoprotein].

    PubMed

    Corral, Pablo; Schreier, Laura

    2014-01-01

    There is irrefutable evidence that statins reduce the risk of cardiovascular events in a magnitude proportional to the intensity of the decrease in cholesterol transport by the low density lipoproteins. Despite this great advance there is still a residual risk of cardiovascular events. For this reason, an increase in the levels of high density lipoprotein is considered in order to boost the main action of this lipoprotein, which is reverse cholesterol transport. Distinct classes of evidence (epidemiological, genetic, and pathophysiological) show that the inhibition and/or modulation of cholesterol ester transfer protein increases plasma high density lipoprotein-cholesterol levels. The main reason for presenting this review is to look at the physiology of cholesterol ester transfer protein, its interrelationship with high density lipoproteins, and to give an update on the development of different cholesterol ester transfer protein inhibitor/modulator molecules.

  10. 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.

  11. The very-high-density lipoprotein fraction of rabbit plasma is rich in tissue-derived cholesterol.

    PubMed

    Nanjee, M N; Miller, N E

    1991-11-05

    When plasma from rabbits, which several weeks earlier had been infused with [3H]cholesterol, was subjected to equilibrium density gradient ultracentrifugation, the specific radioactivity of cholesterol in the very-high-density lipoprotein (VHDL) fraction (d 1.22-1.32 g/ml) was three to 8-fold greater (mean, 5.5-fold; P less than 0.001) than that in high-density lipoproteins (HDL; d 1.06-1.21 g/ml). On size exclusion chromatography of plasma, no increase in specific radioactivity was seen in particles smaller than HDL. These findings suggest that those apolipoprotein-lipid complexes that dissociate from HDL during ultracentrifugation to form the VHDL fraction contain proportionately more tissue-derived cholesterol than do those that are more tightly bound to HDL.

  12. 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

  13. 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.

  14. Bile acids reduce endocytosis of high-density lipoprotein (HDL) in HepG2 cells.

    PubMed

    Röhrl, Clemens; Eigner, Karin; Fruhwürth, Stefanie; Stangl, Herbert

    2014-01-01

    High-density lipoprotein (HDL) transports lipids to hepatic cells and the majority of HDL-associated cholesterol is destined for biliary excretion. Cholesterol is excreted into the bile directly or after conversion to bile acids, which are also present in the plasma as they are effectively reabsorbed through the enterohepatic cycle. Here, we provide evidence that bile acids affect HDL endocytosis. Using fluorescent and radiolabeled HDL, we show that HDL endocytosis was reduced in the presence of high concentrations of taurocholate, a natural non-cell-permeable bile acid, in human hepatic HepG2 and HuH7 cells. In contrast, selective cholesteryl-ester (CE) uptake was increased. Taurocholate exerted these effects extracellularly and independently of HDL modification, cell membrane perturbation or blocking of endocytic trafficking. Instead, this reduction of endocytosis and increase in selective uptake was dependent on SR-BI. In addition, cell-permeable bile acids reduced HDL endocytosis by farnesoid X receptor (FXR) activation: chenodeoxycholate and the non-steroidal FXR agonist GW4064 reduced HDL endocytosis, whereas selective CE uptake was unaltered. Reduced HDL endocytosis by FXR activation was independent of SR-BI and was likely mediated by impaired expression of the scavenger receptor cluster of differentiation 36 (CD36). Taken together we have shown that bile acids reduce HDL endocytosis by transcriptional and non-transcriptional mechanisms. Further, we suggest that HDL endocytosis and selective lipid uptake are not necessarily tightly linked to each other.

  15. 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

  16. 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.

  17. Covalent structure of apolipoprotein A-II from Macaca mulatta serum high-density lipoproteins.

    PubMed

    Edelstein, C; Noyes, C; Keim, P; Heinrikson, R L; Fellows, R E; Scanu, A M

    1976-03-23

    The covalent structure of apolipoprotein A-II, isolated from the serum high-density lipoprotein of a single male Rhesus monkey (Macaca mulatta), was determined. The amino acid sequence of this 77-residue polypeptide is: less than Glu-Ala-Glu-Glu-Pro5-Ser-Val-Glu-Ser-Leu10-Val-Ser-Gln-Tyr-Phe15-Gln-Thr-Val-Thr-Asp20-Tyr-Gly-Lys-Asp-Leu25-Met-Glu-Lys-Val-Lys30-Ser-Pro-Glu-Leu-Gln35-Ala-Gln-Ala-Lys-Ala40-Tyr-Phe-Glu-Lys-Ser45-Lys-Glu-Gln-Leu-Thr50-Pro-Leu-Val-Lys-Lys55-Ala-Gly-Thr-Asp-Leu60-Val-Asn-Phe-Leu-Ser65-Tyr-Phe-Val-Glu-Leu70-Arg-Thr-Gln-Pro-Ala75-Thr-Gln-COOH. A comparison of this structure to that of the monomeric form of human apolipoprotein A-II reveals a high degree of homology except for six conservative amino acid replacements (positions 3, 6, 40, 53, 59, and 71). Of particular structural significance is the replacement of cysteine by serine in position 6. This explaines why Rhesus A-II exists in monomeric form, contrary to the established dimeric nature of the human protein.

  18. 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.

  19. High-density lipoprotein and coronary risk factors in normal men.

    PubMed

    Williams, P; Robinson, D; Bailey, A

    1979-01-01

    Serum high-density-lipoprotein cholesterol (H.D.L.) was measured in 2568 men attending a screening centre and registered with a medical practitioner in Great Britain. Serum-total-cholesterol (T.C.), serum-triglyceride, serum-glucose, systolic and diastolic blood-pressures, electrocardiogram, chest X-ray, height, weight, cigarette and alcohol history, and a brief assessment of physical activity were also recorded. H.D.L. was inversely related to cigarette-smoking, relative weight, and serum-triglyceride level, and directly related to physical activity, total-cholesterol level, and alcohol consumption. The ratio of H.D.L. to T.C. (H.D.L./T.C.) showed similar significant relationships to the above variables (except that the ratio was negatively correlated with T.C.). In addition the ratio was inversely related to age. These relationships were independent of the other measured variables. Both the H.D.L. and H.D.L./T.C. were inversely related to coronary risk rating. It is suggested that, despite methodological problems, H.D.L. is a useful biochemical measurement to add to a coronary risk profile.

  20. High-Density Lipoproteins (HDL) – Nature’s Multi-Functional Nanoparticles

    PubMed Central

    Kuai, Rui; Li, Dan; Chen, Y. Eugene; Moon, James J.; Schwendeman, Anna

    2016-01-01

    High-density lipoproteins (HDL) are endogenous nanoparticles involved in the transport and metabolism of cholesterol, phospholipids, and triglycerides. HDL is well known as the ―good‖ cholesterol because it not only removes excess cholesterol from atherosclerotic plaques but also has anti-inflammatory and anti-oxidative properties, which protect the cardiovascular system. Circulating HDL also transports endogenous proteins, vitamins, hormones, and microRNA to various organs. Compared with other synthetic nanocarriers, such as liposomes, micelles, inorganic and polymeric nanoparticles, HDL has unique features that allow them to deliver cargo to specific targets more efficiently. These attributes include their ultra-small size (8-12 nm in diameter), high tolerability in humans (up to 8 g of protein per infusion), long circulating half-life (12-24 hours), and intrinsic targeting properties to different recipient cells. Various recombinant ApoA proteins and ApoA mimetic peptides have been recently developed for the preparation of reconstituted HDL that exhibits properties similar to endogenous HDL and has a potential for industrial scale-up. In this review, we will summarize: a) clinical pharmacokinetics and safety of reconstituted HDL products, b) comparison of HDL with inorganic and other organic nanoparticles, c) the rationale for using HDL as drug delivery vehicles for important therapeutic indications, d) the current state-of-the-art in HDL production, and e) HDL-based drug delivery strategies for small molecules, peptides/proteins, nucleic acids, and imaging agents targeted to various organs. PMID:26889958

  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. Intercorrelations among plasma high density lipoprotein, obesity and triglycerides in a normal population

    SciTech Connect

    Albrink, M.J.; Krauss, R.M.; Lindgren, F.T.; von der Groeben, J.; Pan, S.; Wood, P.D.

    1980-01-01

    The interrelationships among fatness measures, plasma triglycerides and high density lipoproteins (HDL) were examined in 131 normal adult subjects: 38 men aged 27 to 46, 50 men aged 47 to 66, 29 women aged 27 to 46 and 24 women aged 47 to 66. None of the women were taking estrogens or oral contraceptive medication. The HDL concentration was subdivided into HDL/sub 2b/, HDL/sub 2a/ and HDL by a computerized fitting of the total schileren pattern to reference schlieren patterns. Anthropometric measures employed included skinfolds at 3 sites, 2 weight/height indices and 2 girth measurements. A high correlation was found among the various fatness measures. These measures were negatively correlated with total HDL, reflecting the negative correlation between fatness measures and HDL/sub 2/ (as the sum of HDL/sub 2a/ and /sub 2b/). Fatness measures showed no relationship to HDL/sub 3/. There was also an inverse correlation between triglyceride concentration and HDL/sub 2/. No particular fatness measure was better than any other for demonstrating the inverse correlation with HDL but multiple correlations using all of the measures of obesity improved the correlations. Partial correlations controlling for fatness did not reduce any of the significnt correlations between triglycerides and HDL/sub 2/ to insignificance. The weak correlation between fatness and triglycerides was reduced to insigifnicance when controlled for HDL/sub 2/.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. Paraoxonase-3 is depleted from the high density lipoproteins of autoimmune disease patients with subclinical atherosclerosis

    PubMed Central

    Marsillach, Judit; Becker, Jessica O.; Vaisar, Tomas; Hahn, Bevra H.; Brunzell, John D.; Furlong, Clement E.; deBoer, Ian H.; McMahon, Maureen A.; Hoofnagle, Andrew N.

    2015-01-01

    Patients with autoimmune diseases have a significantly increased risk of developing cardiovascular disease. In disease, high density lipoprotein (HDL) particles lose their anti-inflammatory and antioxidant properties, becoming dysfunctional. The purpose of this study was to test the hypothesis that alterations in the HDL proteomic profile are associated with subclinical atherosclerosis and HDL dysfunction in patients with autoimmune diseases such as systemic lupus erythematosus (SLE) and type 1 diabetes. Targeted proteomics was used to quantify the relative abundance of 18 proteins in HDL from SLE patients with and without atherosclerotic plaque detectable by carotid ultrasound. Changes in the proteomic profile were compared against the in vitro ability of HDL to protect against lipid oxidation. The same proteins were quantified in HDL from patients with type 1 diabetes with or without coronary artery calcification as determined by computed tomography. In each population, paraoxonase-3 (PON3), a potent antioxidant protein, was depleted from the HDL of patients with subclinical atherosclerosis. PON3 expression in HDL was positively correlated with HDL antioxidant function. These results suggest that PON3 may be an important protein in preventing atherosclerosis and highlights the importance of antioxidant proteins in the prevention of atherosclerosis in vivo. PMID:25723336

  9. 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.

  10. 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.

  11. Dysfunctional high-density lipoproteins in coronary heart disease: implications for diagnostics and therapy.

    PubMed

    Annema, Wijtske; von Eckardstein, Arnold

    2016-07-01

    Low plasma levels of high-density lipoprotein (HDL) cholesterol are associated with increased risks of coronary heart disease. HDL mediates cholesterol efflux from macrophages for reverse transport to the liver and elicits many anti-inflammatory and anti-oxidative activities which are potentially anti-atherogenic. Nevertheless, HDL has not been successfully targeted by drugs for prevention or treatment of cardiovascular diseases. One potential reason is the targeting of HDL cholesterol which does not capture the structural and functional complexity of HDL particles. Hundreds of lipid species and dozens of proteins as well as several microRNAs have been identified in HDL. This physiological heterogeneity is further increased in pathologic conditions due to additional quantitative and qualitative molecular changes of HDL components which have been associated with both loss of physiological function and gain of pathologic dysfunction. This structural and functional complexity of HDL has prevented clear assignments of molecules to the functions of normal HDL and dysfunctions of pathologic HDL. Systematic analyses of structure-function relationships of HDL-associated molecules and their modifications are needed to test the different components and functions of HDL for their relative contribution in the pathogenesis of atherosclerosis. The derived biomarkers and targets may eventually help to exploit HDL for treatment and diagnostics of cardiovascular diseases.

  12. A statin-loaded reconstituted high-density lipoprotein nanoparticle inhibits atherosclerotic plaque inflammation

    NASA Astrophysics Data System (ADS)

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P.; Mieszawska, Aneta J.; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J.; Zaidi, Neeha; Lobatto, Mark E.; van Rijs, Sarian M.; Priem, Bram; Kuan, Emma L.; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J.; Stroes, Erik S. G.; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J. M.

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show that this effect is mediated through the inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show that they accumulate in atherosclerotic lesions in which they directly affect plaque macrophages. Finally, we demonstrate that a 3-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a 1-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation.

  13. 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.

  14. 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.

  15. A Statin-Loaded Reconstituted High-Density Lipoprotein Nanoparticle Inhibits Atherosclerotic Plaque Inflammation

    PubMed Central

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P.; Mieszawska, Aneta J.; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J.; Zaidi, Neeha; Lobatto, Mark E.; van Rijs, Sarian M.; Priem, Bram; Kuan, Emma L.; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J.; Stroes, Erik S.G.; Fuster, Valentin; Fisher, Edward A.; Fayad, Zahi A.; Mulder, Willem J.M.

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show this effect is mediated through inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show they accumulate in atherosclerotic lesions where they directly affect plaque macrophages. Finally we demonstrate that a three-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a one-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation. PMID:24445279

  16. A statin-loaded reconstituted high-density lipoprotein nanoparticle inhibits atherosclerotic plaque inflammation.

    PubMed

    Duivenvoorden, Raphaël; Tang, Jun; Cormode, David P; Mieszawska, Aneta J; Izquierdo-Garcia, David; Ozcan, Canturk; Otten, Maarten J; Zaidi, Neeha; Lobatto, Mark E; van Rijs, Sarian M; Priem, Bram; Kuan, Emma L; Martel, Catherine; Hewing, Bernd; Sager, Hendrik; Nahrendorf, Matthias; Randolph, Gwendalyn J; Stroes, Erik S G; Fuster, Valentin; Fisher, Edward A; Fayad, Zahi A; Mulder, Willem J M

    2014-01-01

    Inflammation is a key feature of atherosclerosis and a target for therapy. Statins have potent anti-inflammatory properties but these cannot be fully exploited with oral statin therapy due to low systemic bioavailability. Here we present an injectable reconstituted high-density lipoprotein (rHDL) nanoparticle carrier vehicle that delivers statins to atherosclerotic plaques. We demonstrate the anti-inflammatory effect of statin-rHDL in vitro and show that this effect is mediated through the inhibition of the mevalonate pathway. We also apply statin-rHDL nanoparticles in vivo in an apolipoprotein E-knockout mouse model of atherosclerosis and show that they accumulate in atherosclerotic lesions in which they directly affect plaque macrophages. Finally, we demonstrate that a 3-month low-dose statin-rHDL treatment regimen inhibits plaque inflammation progression, while a 1-week high-dose regimen markedly decreases inflammation in advanced atherosclerotic plaques. Statin-rHDL represents a novel potent atherosclerosis nanotherapy that directly affects plaque inflammation.

  17. 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.

  18. Age-related changes in total and high-density-lipoprotein cholesterol in elderly Dutch men.

    PubMed Central

    Weijenberg, M P; Feskens, E J; Kromhout, D

    1996-01-01

    OBJECTIVES: This study investigated changes in total and high-density-lipoprotein cholesterol (HDL) concentrations with age and time in elderly men. METHODS: A cohort of men born between 1900 and 1920 from the Dutch town of Zutphen was examined in 1977 and 1978 (n = 571), 1985 (n = 885), 1990 (n = 555), and 1993 (n = 345). Linear regression analysis and random-effects models were used to assess cross-sectional and longitudinal age- and time-related changes in cholesterol concentrations. RESULTS: In both cross-sectional and longitudinal analyses, total cholesterol decreased by 0.04 mmol/L a year with age. The longitudinal change was observed in the entire population as well as in men who participated in all four examinations (n = 135) and in a subgroup of men who were free of common chronic diseases, were not on cholesterol-lowering medication or a prescribed diet, and rated themselves as being "healthy" (n = 64). HDL cholesterol did not change significantly with age neither on a cross-sectional nor on a longitudinal basis. CONCLUSIONS: Among elderly men, total cholesterol diminishes with age both on a cross-sectional and on a longitudinal basis; HDL cholesterol does not vary with age in any way. PMID:8659652

  19. 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.

  20. High Density Lipoproteins Selectively Promote the Survival of Human Regulatory T-cells.

    PubMed

    Rueda, Cesar M; Rodriguez-Perea, Ana Lucia; Moreno-Fernandez, Maria; Jackson, Courtney M; Melchior, John T; Davidson, W Sean; Chougnet, Claire A

    2017-04-04

    High-density lipoproteins (HDL) appear to affect regulatory T cell (Treg) homeostasis, as suggested by the increased Treg counts in HDL-treated mice and by the positive correlation between Treg frequency and HDL-C levels in statin-treated healthy adults. However, the underlying mechanisms remain unclear. Herein, we show that HDL, not LDL, significantly decreased the apoptosis of human Treg in vitro, whereas they did not alter naive or memory CD4+ T-cell survival. Similarly, oleic acid bound to serum albumin increased Treg survival. Treg bound and internalized high amounts of HDL compared to other subsets, which might arise from the higher expression of the scavenger receptor class B-type I by Treg; accordingly, blocking this receptor hindered HDL-mediated Treg survival. Mechanistically, we showed that HDL increased Treg ATP concentration and mitochondrial activity, enhancing basal respiration, maximal respiration and spare respiratory capacity. Blockade of fatty acid oxidation by etoxomir abolished the HDL-mediated enhanced survival and mitochondrial activity. Our findings thus suggest that Treg can specifically internalize HDL from their microenvironment and use them as an energy source. Furthermore, a novel implication of our data is that enhanced Treg survival may contribute to HDL anti-inflammatory properties.

  1. Increased Antioxidant Quality Versus Lower Quantity of High Density Lipoprotein in Benign Prostatic Hyperplasia

    PubMed Central

    Aydin, Ozgur; Ellidag, Hamit Yasar; Eren, Esin; Ay, Nurullah; Yalçınkaya, Soner; Yilmaz, Necat

    2015-01-01

    Summary Background Oxidative stress may be involved in the pathogenesis of every human disease. To understand its possible role in benign prostatic hyperplasia (BPH), we measured the overall oxidative status of patients with BPH and the serum activity of the high density lipoprotein (HDL)-related antioxidant enzymes paraoxonase 1 (PON1) and arylesterase (ARE). Methods Fifty-six urology outpatient clinic patients with BPH (mean age 64±8.6 years) were prospectively included in the study. Forty volunteer healthy controls from the laboratory staff (mean age 62±10 years) were enrolled for comparison. Serum total antioxidant status (TAS), total oxidant status (TOS), PON1, ARE, and HDL levels were measured by commercially available, ready-to-use kits. Results Serum TAS and HDL levels were significantly lower in the BPH group than in the control group (P=0.004 and P=0.02, respectively). No significant between-group differences were observed for TOS levels or PON1 and ARE enzyme activities (P=0.30, P=0.89, and P=0.74, respectively). In the BPH group, the calculated parameters PON1/HDL and ARE/HDL were significantly higher (P=0.02 and P=0.04, respectively). Conclusions Our findings agree with the previous reports of impaired oxidant/antioxidant balance in BPH patients. The activities of HDL-related enzymes between groups with significantly different HDL levels may be deceptive; adjusted values may help to reach more accurate conclusions.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. Sphingomyelin in High-Density Lipoproteins: Structural Role and Biological Function

    PubMed Central

    Martínez-Beamonte, Roberto; Lou-Bonafonte, Jose M.; Martínez-Gracia, María V.; Osada, Jesús

    2013-01-01

    High-density lipoprotein (HDL) levels are an inverse risk factor for cardiovascular diseases, and sphingomyelin (SM) is the second most abundant phospholipid component and the major sphingolipid in HDL. Considering the marked presence of SM, the present review has focused on the current knowledge about this phospholipid by addressing its variable distribution among HDL lipoparticles, how they acquire this phospholipid, and the important role that SM plays in regulating their fluidity and cholesterol efflux from different cells. In addition, plasma enzymes involved in HDL metabolism such as lecithin–cholesterol acyltransferase or phospholipid transfer protein are inhibited by HDL SM content. Likewise, HDL SM levels are influenced by dietary maneuvers (source of protein or fat), drugs (statins or diuretics) and modified in diseases such as diabetes, renal failure or Niemann–Pick disease. Furthermore, increased levels of HDL SM have been shown to be an inverse risk factor for coronary heart disease. The complexity of SM species, described using new lipidomic methodologies, and their distribution in different HDL particles under many experimental conditions are promising avenues for further research in the future. PMID:23571495

  8. 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.

  9. 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

  10. Liver disease alters high-density lipoprotein composition, metabolism and function.

    PubMed

    Trieb, Markus; Horvath, Angela; Birner-Gruenberger, Ruth; Spindelboeck, Walter; Stadlbauer, Vanessa; Taschler, Ulrike; Curcic, Sanja; Stauber, Rudolf E; Holzer, Michael; Pasterk, Lisa; Heinemann, Akos; Marsche, Gunther

    2016-07-01

    High-density lipoproteins (HDL) are important endogenous inhibitors of inflammatory responses. Functional impairment of HDL might contribute to the excess mortality experienced by patients with liver disease, but the effect of cirrhosis on HDL metabolism and function remain elusive. To get an integrated measure of HDL quantity and quality, we assessed several metrics of HDL function using apolipoprotein (apo) B-depleted sera from patients with compensated cirrhosis, patients with acutely decompensated cirrhosis and healthy controls. We observed that sera of cirrhotic patients showed reduced levels of HDL-cholesterol and profoundly suppressed activities of several enzymes involved in HDL maturation and metabolism. Native gel electrophoresis analyses revealed that cirrhotic serum HDL shifts towards the larger HDL2 subclass. Proteomic assessment of isolated HDL identified several proteins, including apoA-I, apoC-III, apoE, paraoxonase 1 and acute phase serum amyloid A to be significantly altered in cirrhotic patients. With regard to function, these alterations in levels, composition and structure of HDL were strongly associated with metrics of function of apoB-depleted sera, including cholesterol efflux capability, paraoxonase activity, the ability to inhibit monocyte production of cytokines and endothelial regenerative activities. Of particular interest, cholesterol efflux capacity appeared to be strongly associated with liver disease mortality. Our findings may be clinically relevant and improve our ability to monitor cirrhotic patients at high risk.

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Education, race, and high-density lipoprotein cholesterol among US adults.

    PubMed Central

    Freedman, D S; Strogatz, D S; Williamson, D F; Aubert, R E

    1992-01-01

    OBJECTIVES. Although educational achievement is positively related to levels of high-density lipoprotein cholesterol (HDL-C) among White adults, there is an inverse association among Blacks. We assessed whether this interaction could be attributed to differences in the relation of education to correlates of HDL-C. METHODS. Cross-sectional analyses were based on data from 8391 White and 995 Black adults who participated in the Second National Health and Nutrition Examination Survey. RESULTS. Associations between education and HDL-C levels varied from negative (Black men), to nearly nonexistent (White men and Black women), to positive (White women). Mean HDL-C levels were higher among Blacks than among Whites, but differences varied according to educational achievement. Among adults with less than 9 years of education, mean levels were 6 to 10 mg/dL higher among Blacks, but the radical difference was less than 1 mg/dL among adults with at least 16 years of education. About 20% to 40% of these differences could be accounted for by obesity, alcohol consumption, and other characteristics. CONCLUSIONS. Because of the implications for coronary heart disease risk, consideration should be given to behavioral characteristics associated with the interaction between race and educational achievement. PMID:1609919

  18. 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

  19. 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

  20. Fast determination of virgin olive oil phenolic metabolites in human high-density lipoproteins.

    PubMed

    Fernández-Ávila, C; Montes, R; Castellote, A I; Chisaguano, A M; Fitó, M; Covas, M I; Muñoz-Aguallo, D; Nyyssönen, K; Zunft, H J; López-Sabater, M C

    2015-07-01

    In recent years it has been confirmed that the consumption of olive oil prevents the oxidation of biomolecules owing to its monounsaturated fatty acids (MUFA) and phenolic content. The main objective of the study was to develop an ultra-high-performance liquid chromatography (UHPLC) tandem mass spectrometry (MS/MS) method for the determination of phenolic compounds in human high-density lipoprotein (HDL) samples. At the same time, the influence of olive oil consumption on the phenolic metabolite levels was evaluated in a European population. The participants were 51 healthy men, aged 20-60. They were randomized to two consecutive intervention periods with the administration of raw olive oil with low and high polyphenolic content. The UHPLC-MS/MS analytical method has been validated for hydroxytyrosol and homovanillic acid in terms of linearity (r(2)  = 0.99 and 1.00), repeatability (5.7 and 6.5%) reproducibility (6.2 and 7%), recovery (98 to 97%), limits of detection (1.7 to 1.8 ppb) and quantification (5.8 and 6.3 ppb).The levels of the studied metabolites increased significantly after high polyphenolic content virgin olive oil ingestion (p <0.05) compared with lowpolyphenolic content olive oil. Virgin olive oil consumption increases the levels of phenolic metabolites in HDL and thus provides human HDL with more efficient antioxidant protection.

  1. Molecular dynamics on a model for nascent high-density lipoprotein: role of salt bridges.

    PubMed Central

    Sheldahl, C; Harvey, S C

    1999-01-01

    The results of an all-atom molecular dynamics simulation on a discoidal complex made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and a synthetic alpha-helical 18-mer peptide with an apolipoprotein-like charge distribution are presented. The system consists of 12 acetyl-18A-amide (Ac-18A-NH2) (. J. Biol. Chem. 260:10248-10255) molecules and 20 molecules of POPC in a bilayer, 10 in each leaflet, solvated in a sphere of water for a total of 28,522 atoms. The peptide molecules are oriented with their long axes normal to the bilayer (the "picket fence" orientation). This system is analogous to complexes formed in nascent high-density lipoprotein and to Ac-18A-NH2/phospholipid complexes observed experimentally. The simulation extended over 700 ps, with the last 493 ps used for analysis. The symmetry of this system allows for averaging over different helices to improve sampling, while maintaining explicit all-atom representation of all peptides. The complex is stable on the simulated time scale. Several possible salt bridges between and within helices were studied. A few salt bridge formations and disruptions were observed. Salt bridges provide specificity in interhelical interactions. PMID:10049304

  2. Candidate genetic analysis of plasma high-density lipoprotein-cholesterol and severity of coronary atherosclerosis

    PubMed Central

    Chen, Suet Nee; Cilingiroglu, Mehmet; Todd, Josh; Lombardi, Raffaella; Willerson, James T; Gotto, Antonio M; Ballantyne, Christie M; Marian, AJ

    2009-01-01

    Background Plasma level of high-density lipoprotein-cholesterol (HDL-C), a heritable trait, is an important determinant of susceptibility to atherosclerosis. Non-synonymous and regulatory single nucleotide polymorphisms (SNPs) in genes implicated in HDL-C synthesis and metabolism are likely to influence plasma HDL-C, apolipoprotein A-I (apo A-I) levels and severity of coronary atherosclerosis. Methods We genotyped 784 unrelated Caucasian individuals from two sets of populations (Lipoprotein and Coronary Atherosclerosis Study- LCAS, N = 333 and TexGen, N = 451) for 94 SNPs in 42 candidate genes by 5' nuclease assays. We tested the distribution of the phenotypes by the Shapiro-Wilk normality test. We used Box-Cox regression to analyze associations of the non-normally distributed phenotypes (plasma HDL-C and apo A-I levels) with the genotypes. We included sex, age, body mass index (BMI), diabetes mellitus (DM), and cigarette smoking as covariates. We calculated the q values as indicators of the false positive discovery rate (FDR). Results Plasma HDL-C levels were associated with sex (higher in females), BMI (inversely), smoking (lower in smokers), DM (lower in those with DM) and SNPs in APOA5, APOC2, CETP, LPL and LIPC (each q ≤0.01). Likewise, plasma apo A-I levels, available in the LCAS subset, were associated with SNPs in CETP, APOA5, and APOC2 as well as with BMI, sex and age (all q values ≤0.03). The APOA5 variant S19W was also associated with minimal lumen diameter (MLD) of coronary atherosclerotic lesions, a quantitative index of severity of coronary atherosclerosis (q = 0.018); mean number of coronary artery occlusions (p = 0.034) at the baseline and progression of coronary atherosclerosis, as indicated by the loss of MLD. Conclusion Putatively functional variants of APOA2, APOA5, APOC2, CETP, LPL, LIPC and SOAT2 are independent genetic determinants of plasma HDL-C levels. The non-synonymous S19W SNP in APOA5 is also an independent determinant of plasma

  3. High-Density Lipoprotein Function in Exudative Age-Related Macular Degeneration

    PubMed Central

    Pertl, Laura; Kern, Sabine; Weger, Martin; Hausberger, Silke; Trieb, Markus; Gasser-Steiner, Vanessa; Haas, Anton; Scharnagl, Hubert; Heinemann, Akos; Marsche, Gunther

    2016-01-01

    Purpose High-density lipoproteins (HDL) have long been implicated in the pathogenesis of age-related macular degeneration (AMD). However, conflicting results have been reported with regard to the associations of AMD with HDL-cholesterol levels. The present study is the first to assess HDL composition and metrics of HDL function in patients with exudative AMD and control patients. Methods Blood samples were collected from 29 patients with exudative AMD and 26 age-matched control patients. Major HDL associated apolipoproteins were determined in apoB-depleted serum by immunoturbidimetry or ELISA, HDL-associated lipids were quantified enzymatically. To get an integrated measure of HDL quantity and quality, we assessed several metrics of HDL function, including cholesterol efflux capacity, anti-oxidative and anti-inflammatory activities using apoB-depleted serum from study participants. Results In our study, we observed that the HDL associated acute phase protein serum amyloid A (SAA) was significantly increased in AMD patients (p<0.01), whereas all other assessed apolipoproteins including ApoA-I, apoA-II, apoC-II, apoC-III and apoE as well as major HDL associated lipids were not altered. HDL efflux capacity, anti-oxidative capacity and arylesterase activity were not different in AMD patients when compared with the control group. The ability of apoB-depleted serum to inhibit monocyte NF-κB expression was significantly improved in AMD patients (mean difference (MD) -5.6, p<0.01). Moreover, lipoprotein-associated phospholipase A2 activity, a marker of vascular inflammation, was decreased in AMD subjects (MD -24.1, p<0.01). Conclusions The investigated metrics of HDL composition and HDL function were not associated with exudative AMD in this study, despite an increased content of HDL associated SAA in AMD patients. Unexpectedly, anti-inflammatory activity of apoB-depleted serum was even increased in our study. Our data suggest that the investigated parameters of serum HDL

  4. 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

  5. Dysfunctional High-Density Lipoprotein and the Potential of Apolipoprotein A-1 Mimetic Peptides to Normalize the Composition and Function of Lipoproteins

    PubMed Central

    Imaizumi, Satoshi; Navab, Mohamad; Morgantini, Cecilia; Charles-Sehoeman, Christina; Su, Feng; Gao, Feng; Kwon, Murray; Ganapathy, Ekambaram; Meriwether, David; Farias-Eisner, Robin; Fogelman, Alan M.; Reddy, Srinivasa T.

    2013-01-01

    Although high-density lipoprotein-cholesterol (HDL-C) levels in large epidemiological studies are inversely related to the risk of coronary heart disease (CHD), increasing the level of circulating HDL-C does not necessarily decrease the risk of CHD events, CHD deaths, or mortality, HDL can act as an anti- or a proinflammatory molecule, depending on the context and environment. Based on a number of recent studies, it appears that the anti- or proinflammatory nature of HDL may be a more sensitive indicator of the presence or absence of atherosclerosis than HDL-C levels. The HDL proteome has been suggested to be a marker, and perhaps a mediator, of CHD. Apolipoprotein A-1 (apoA-I), the major protein in HDL is a selective target for oxidation by myeloperoxidase, which results in impaired HDL function. Improving HDL function through modification of its lipid and/or protein content maybe a therapeutic target for the treatment of CHD and many inflammatory disorders. HDL/apoA-I mimetic peptides may have the ability to modify the lipid and protein content of HDL and convert dysfunctional HDL to functional HDL. This review focuses on recent studies of dysfunctional HDL in animal models and human disease, and the potential of apoA-I mimetic peptides to normalize the composition and (function of lipoproteins. PMID:21628835

  6. 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

  7. The Correlation between the Triglyceride to High Density Lipoprotein Cholesterol Ratio and Computed Tomography-Measured Visceral Fat and Cardiovascular Disease Risk Factors in Local Adult Male Subjects

    PubMed Central

    Park, Hye-Rin; Han, A Lum; Jeong, Yong Joon

    2015-01-01

    Background We studied the association between the triglyceride to high-density lipoprotein cholesterol ratio and computed tomography-measured visceral fat as well as cardiovascular risk factors among Korean male adults. Methods We measured triglycerides, high density lipoprotein cholesterol, body mass, waist circumference, fasting plasma glucose, hemoglobin A1c, systolic blood pressure, diastolic blood pressure, visceral fat, and subcutaneous fat among 372 Korean men. The visceral fat and subcutaneous fat areas were measured by computed tomography using a single computed tomography slice at the L4-5 lumbar level. We analyzed the association between the triglyceride to high density lipoprotein cholesterol ratio and visceral fat as well as cardiovascular risk factors. Results A positive correlation was found between the triglyceride to high density lipoprotein cholesterol ratio and variables such as body mass index, waist circumference, fasting plasma glucose, hemoglobin A1c, visceral fat, and the visceral-subcutaneous fat ratio. However, there was no significant correlation between the triglyceride to high density lipoprotein cholesterol ratio and subcutaneous fat or blood pressure. Multiple logistic regression analyses revealed significant associations between a triglyceride to high density lipoprotein cholesterol ratio ≥3 and diabetes, a body mass index ≥25 kg/m2, a waist circumference ≥90 cm, and a visceral fat area ≥100 cm2. The triglyceride to high density lipoprotein cholesterol ratio was not significantly associated with hypertension. Conclusion There were significant associations between the triglyceride to high density lipoprotein cholesterol ratio and body mass, waist circumference, diabetes, and visceral fat among a clinical sample of Korean men. In the clinical setting, the triglyceride to high density lipoprotein cholesterol ratio may be a simple and useful indicator for visceral obesity and cardiovascular disease. PMID:26634102

  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. 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.

  10. Protection from Cardiovascular Disease Due to Increased High-Density Lipoprotein Cholesterol in African Black Populations: Myth or Reality?

    PubMed

    Woudberg, Nicholas J; Goedecke, Julia H; Lecour, Sandrine

    2016-10-20

    The burden of cardiovascular disease (CVD) in sub-Saharan Africa has increased over the last decade. Despite this, African Black populations present with relatively low incidences of coronary heart disease and ischemic heart disease, which may be attributed to their lower total cholesterol, triglycerides and low-density lipoprotein cholesterol concentrations, compared with White populations. Commensurate with these lower lipid levels, it was believed that high-density lipoprotein cholesterol (HDL-C) concentrations would be higher in Black populations compared with their White counterparts. This is based on data from previous studies of African and African American populations; however, recent studies conducted in Africa found similar or lower HDL-C concentrations in Black compared with White individuals. Current research, therefore, suggests that HDL-C may not be a good indicator of cardiovascular risk and future research should focus on HDL quality (vs quantity), by measuring HDL functionality and subclass.

  11. 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.

  12. Cubilin, the endocytic receptor for intrinsic factor-vitamin B(12) complex, mediates high-density lipoprotein holoparticle endocytosis.

    PubMed

    Hammad, S M; Stefansson, S; Twal, W O; Drake, C J; Fleming, P; Remaley, A; Brewer, H B; Argraves, W S

    1999-08-31

    Receptors that endocytose high-density lipoproteins (HDL) have been elusive. Here yolk-sac endoderm-like cells were used to identify an endocytic receptor for HDL. The receptor was isolated by HDL affinity chromatography and identified as cubilin, the recently described endocytic receptor for intrinsic factor-vitamin B(12). Cubilin antibodies inhibit HDL endocytosis by the endoderm-like cells and in mouse embryo yolk-sac endoderm, a prominent site of cubilin expression. Cubilin-mediated HDL endocytosis is inhibitable by HDL(2), HDL(3), apolipoprotein (apo)A-I, apoA-II, apoE, and RAP, but not by low-density lipoprotein (LDL), oxidized LDL, VLDL, apoC-I, apoC-III, or heparin. These findings, coupled with the fact that cubilin is expressed in kidney proximal tubules, suggest a role for this receptor in embryonic acquisition of maternal HDL and renal catabolism of filterable forms of HDL.

  13. Influence of dietary lipids on hepatic mRNA levels of proteins regulating plasma lipoproteins in baboons with high and low levels of large high density lipoproteins.

    PubMed

    Kushwaha, R S; McMahan, C A; Mott, G E; Carey, K D; Reardon, C A; Getz, G S; McGill, H C

    1991-12-01

    Selective breeding of baboons has produced families with increased plasma levels of large high density lipoproteins (HDL1) and very low (VLDL) and low (LDL) density lipoproteins when the animals consume a diet enriched in cholesterol and saturated fat. High HDL1 baboons have a slower cholesteryl ester transfer, which may account for the accumulation of HDL1, but not of VLDL and LDL. To investigate the mechanism of accumulation of VLDL + LDL in plasma of the high HDL1 phenotype, we selected eight half-sib pairs of baboons, one member of each pair with high HDL1, the other member with little or no HDL1 on the same high cholesterol, saturated fat diet. Baboons were fed a chow diet and four experimental diets consisting of high and low cholesterol with corn oil, and high and low cholesterol with lard, each for 6 weeks, in a crossover design. Plasma lipids and lipoproteins and hepatic mRNA levels were measured on each diet. HDL1 phenotype, type of dietary fat, and dietary cholesterol affected plasma cholesterol and apolipoprotein (apo) B concentrations, whereas dietary fat alone affected plasma triglyceride and apoA-I concentrations. HDL1 phenotype and dietary cholesterol alone did not influence hepatic mRNA levels, whereas dietary lard, compared to corn oil, significantly increased hepatic apoE mRNA levels and decreased hepatic LDL receptor and HMG-CoA synthase mRNA levels. Hepatic apoA-I message was associated with cholesterol concentration in HDL fractions as well as with apoA-I concentrations in the plasma or HDL. However, hepatic apoB message level was not associated with plasma or LDL apoB levels. Total plasma cholesterol, including HDL, was negatively associated with hepatic LDL receptor and HMG-CoA synthase mRNA levels. However, compared with low HDL1 baboons, high HDL1 baboons had higher concentrations of LDL and HDL cholesterol at the same hepatic mRNA levels. These studies suggest that neither overproduction of apoB from the liver nor decreased hepatic LDL

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. Plasma Nitration of High-Density and Low-Density Lipoproteins in Chronic Kidney Disease Patients Receiving Kidney Transplants

    PubMed Central

    Bakillah, Ahmed; Tedla, Fasika; Ayoub, Isabelle; John, Devon; Norin, Allen J.; Hussain, M. Mahmood; Brown, Clinton

    2015-01-01

    Background. Functional abnormalities of high-density lipoprotein (HDL) could contribute to cardiovascular disease in chronic kidney disease patients. We measured a validated marker of HDL dysfunction, nitrated apolipoprotein A-I, in kidney transplant recipients to test the hypothesis that a functioning kidney transplant reduces serum nitrated apoA-I concentrations. Methods. Concentrations of nitrated apoA-I and apoB were measured using indirect sandwich ELISA assays on sera collected from each transplant subject before transplantation and at 1, 3, and 12 months after transplantation. Patients were excluded if they have history of diabetes, treatment with lipid-lowering medications or HIV protease inhibitors, prednisone dose > 15 mg/day, nephrotic range proteinuria, serum creatinine > 1.5 mg/dL, or active inflammatory disease. Sera from 18 transplanted patients were analyzed. Four subjects were excluded due to insufficient data. Twelve and eight patients had creatinine < 1.5 mg/dL at 3 and 12 months after transplantation, respectively. Results. Nitrated apoA-I was significantly reduced at 12 months after transplantation (p = 0.039). The decrease in apoA-I nitration was associated with significant reduction in myeloperoxidase (MPO) activity (p = 0.047). In contrast to apoA-I, nitrated apoB was not affected after kidney transplantation. Conclusions. Patients with well-functioning grafts had significant reduction in nitrated apoA-I 12 months after kidney transplantation. Further studies are needed in a large cohort to determine if nitrated apoA-I can be used as a valuable marker for cardiovascular risk stratification in chronic kidney disease. PMID:26648662

  19. [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.

  20. 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.

  1. The putative neuraminyllactose-binding hemagglutinin HpaA of Helicobacter pylori CCUG 17874 is a lipoprotein.

    PubMed Central

    O'Toole, P W; Janzon, L; Doig, P; Huang, J; Kostrzynska, M; Trust, T J

    1995-01-01

    The ability of certain strains of Helicobacter pylori to cause sialic acid-sensitive agglutination of erythrocytes has been attributed to the HpaA protein (D.G. Evans, T.K. Karjalainen, D. J. Evans, Jr., D. Y. Graham, and C.H. Lee, J. Bacteriol. 175:674-683, 1993), the gene for which has been cloned and sequenced. On the basis of the hydropathy plot of HpaA and the presence of a potential lipoprotein signal sequence and modification site, and because of the similarities of these features with those of the cell envelope lipoprotein Lpp20 of H. pylori, we examined the possibility that HpaA was also a lipoprotein. Posttranslational processing of the HpaA protein expressed by the cloned gene was sensitive to globomycin, an inhibitor of the lipoprotein-specific signal peptidase II. Antibodies raised to the putative sialic acid-binding region of HpaA failed to bind to the surface of H. pylori cells in immunoelectron microscopy but instead were observed to have labeled the cytoplasm when thin sections were examined. This antibody recognized a 29,000-M(r) protein in Western blots (immunoblots) of cell extracts of H. pylori and Escherichia coli cells expressing the cloned hpaA gene. Determination of the sequence of hpaA from strain CCUG 17874 indicated significant differences from that determined by Evans and coworkers in the above-mentioned study, including extension of the gene into the open reading frame 3 downstream of hpaA to produce a protein with an M(r) of 26,414. Localization of HpaA indicated that it was predominantly located in the cytoplasmic fraction of the cell in both E. coli and H. pylori. HpaA was not observed in the sarkosyl-insoluble outer membrane fraction. An isogenic mutant generated by insertional inactivation of hpaA was unaffected in its ability to bind four different human cell lines as well as fixed sections of gastric tissue and had hemagglutination properties identical to those of the wild type. The data collectively suggest that HpaA is a

  2. Triglyceride to High-Density Lipoprotein Cholesterol Ratio Predicts Cardiovascular Outcomes in Prevalent Dialysis Patients

    PubMed Central

    Chen, Hung-Yuan; Tsai, Wan-Chuan; Chiu, Yen-Ling; Hsu, Shih-Ping; Pai, Mei-Fen; Yang, Ju-Yeh; Peng, Yu-Sen

    2015-01-01

    Abstract Triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio, an indicator of atherogenic dyslipidemia, is a predictor of cardiovascular (CV) outcomes in the general population and has been correlated with atherosclerotic events. Whether the TG/HDL-C ratio can predict CV outcomes and survival in dialysis patients is unknown. We performed this prospective, observational cohort study and enrolled 602 dialysis patients (539 hemodialysis and 63 peritoneal dialysis) from a single center in Taiwan followed up for a median of 3.9 years. The outcomes were the occurrence of CV events, CV death, and all-cause mortality during follow-up. The association of baseline TG/HDL-C ratio with outcomes was explored with Cox regression models, which were adjusted for demographic parameters and inflammatory/nutritional markers. Overall, 203 of the patients experienced CV events and 169 patients died, of whom 104 died due to CV events. Two hundred fifty-four patients reached the composite CV outcome. Patients with higher TG/HDL-C levels (quintile 5) had a higher incidence of CV events (adjusted hazard ratio [HR] 2.03, 95% confidence interval [CI] 1.19–3.47), CV mortality (adjusted HR 1.91, 95% CI 1.07–3.99), composite CV outcome (adjusted HR 2.2, 95% CI 1.37–3.55), and all-cause mortality (adjusted HR 1.94, 95% CI 1.1–3.39) compared with the patients in quintile 1. However, in diabetic dialysis patients, the TG/HDL-C ratio did not predict the outcomes. The TG/HDL-C ratio is a reliable and easily accessible predictor to evaluate CV outcomes and survival in prevalent nondiabetic dialysis patients. ClinicalTrials.gov: NCT01457625 PMID:25761189

  3. Is High-Density Lipoprotein Cholesterol Causally Related to Kidney Function?

    PubMed Central

    Coassin, Stefan; Friedel, Salome; Köttgen, Anna

    2016-01-01

    Objective— A recent observational study with almost 2 million men reported an association between low high-density lipoprotein (HDL) cholesterol and worse kidney function. The causality of this association would be strongly supported if genetic variants associated with HDL cholesterol were also associated with kidney function. Approach and Results— We used 68 genetic variants (single-nucleotide polymorphisms [SNPs]) associated with HDL cholesterol in genome-wide association studies including >188 000 subjects and tested their association with estimated glomerular filtration rate (eGFR) using summary statistics from another genome-wide association studies meta-analysis of kidney function including ≤133 413 subjects. Fourteen of the 68 SNPs (21%) had a P value <0.05 compared with the 5% expected by chance (Binomial test P=5.8×10−6). After Bonferroni correction, 6 SNPs were still significantly associated with eGFR. The genetic variants with the strongest associations with HDL cholesterol concentrations were not the same as those with the strongest association with kidney function and vice versa. An evaluation of pleiotropy indicated that the effects of the HDL-associated SNPs on eGFR were not mediated by HDL cholesterol. In addition, we performed a Mendelian randomization analysis. This analysis revealed a positive but nonsignificant causal effect of HDL cholesterol–increasing variants on eGFR. Conclusions— In summary, our findings indicate that HDL cholesterol does not causally influence eGFR and propose pleiotropic effects on eGFR for some HDL cholesterol–associated SNPs. This may cause the observed association by mechanisms other than the mere HDL cholesterol concentration. PMID:27687604

  4. 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

  5. Gene therapy to improve high-density lipoprotein metabolism and function.

    PubMed

    Van Craeyveld, Eline; Gordts, Stephanie; Jacobs, Frank; De Geest, Bart

    2010-05-01

    Plasma levels of high-density lipoprotein (HDL) cholesterol and its major apolipoprotein (apo), apo A-I, are inversely correlated with the incidence of ischemic cardiovascular diseases. Till now, evaluation of the hypothesis that elevation of HDL cholesterol reduces atherosclerotic burden and/or decreases ischemic cardiovascular events in humans has been hampered by the lack of drugs that selectively increase HDL cholesterol. In contrast to the lack of clinical data, evidence for a direct causal role of HDL in modulating atherogenesis in experimental models has been provided by investigations in human apo A-I transgenic mice and rabbits. The development of gene transfer technologies with a sufficiently high therapeutic index may pave the road for a selective and effective HDL raising therapeutic intervention. The goal of a therapeutic strategy that modulates HDL metabolism is not an increase of HDL cholesterol as such, but an enhancement of HDL function. The value of HDL cholesterol as a surrogate end-point to predict reduced atherosclerosis or a decrease in clinical events may be highly dependent on the mechanism leading to an increased level of HDL cholesterol. In the case of gene transfer, this implies that beneficial effects of increasing HDL cholesterol will be dependent on the transgene that is expressed. Here, we critically review HDL metabolism and HDL function in relation to the development of HDL raising gene transfer, advances and drawbacks of different gene transfer technologies, and experimental gene transfer studies evaluating the effect of raised HDL on histological and functional outcomes in animal models.

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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

  12. Modulation of adipose tissue lipolysis and body weight by high-density lipoproteins in mice

    PubMed Central

    Wei, H; Averill, M M; McMillen, T S; Dastvan, F; Mitra, P; Subramanian, S; Tang, C; Chait, A; LeBoeuf, R C

    2014-01-01

    Background: Obesity is associated with reduced levels of circulating high-density lipoproteins (HDLs) and its major protein, apolipoprotein (apo) A-I. As a result of the role of HDL and apoA-I in cellular lipid transport, low HDL and apoA-I may contribute directly to establishing or maintaining the obese condition. Methods: To test this, male C57BL/6 wild-type (WT), apoA-I deficient (apoA-I−/−) and apoA-I transgenic (apoA-Itg/tg) mice were fed obesogenic diets (ODs) and monitored for several clinical parameters. We also performed cell culture studies. Results: ApoA-I−/− mice gained significantly more body weight and body fat than WT mice over 20 weeks despite their reduced food intake. During a caloric restriction regime imposed on OD-fed mice, apoA-I deficiency significantly inhibited the loss of body fat as compared with WT mice. Reduced body fat loss with caloric restriction in apoA-I−/− mice was associated with blunted stimulated adipose tissue lipolysis as verified by decreased levels of phosphorylated hormone-sensitive lipase (p-HSL) and lipolytic enzyme mRNA. In contrast to apoA-I−/− mice, apoA-Itg/tg mice gained relatively less weight than WT mice, consistent with other reports. ApoA-Itg/tg mice showed increased adipose tissue lipolysis, verified by increased levels of p-HSL and lipolytic enzyme mRNA. In cell culture studies, HDL and apoA-I specifically increased catecholamine-induced lipolysis possibly through modulating the adipocyte plasma membrane cholesterol content. Conclusions: Thus, apoA-I and HDL contribute to modulating body fat content by controlling the extent of lipolysis. ApoA-I and HDL are key components of lipid metabolism in adipose tissue and constitute new therapeutic targets in obesity. PMID:24567123

  13. Relation between high density lipoprotein cholesterol and coronary artery disease in asymptomatic men

    SciTech Connect

    Uhl, G.S.; Troxler, R.G.; Hickman, J.R. Jr.; Clark, D.

    1981-11-01

    The well established inverse relation of high density lipoprotein cholesterol (HDL) and the risk of coronary artery disease was tested in a cross-sectional group of 572 asymptomatic aircrew members who were being screened for risk of coronary artery disease. A battery of tests was performed, including determinations of fasting serum cholesterol, HDL cholesterol and triglycerides and performance of a maximal symptom-limited exercise tolerance test. Of the 572 patients, 132 also had an abnormal S-T segment response to exercise testing or were otherwise believed to have an increased risk of organic heart disease and subsequently underwent coronary angiography. Significant coronary artery disease was found in 16 men and minimal or subcritical coronary disease in 14; coronary angiograms were normal in the remaining 102 men. The remaining 440 men, who were believed to have a 1 percent chance of having coronary artery disease by sequential testing of risk factors and treadmill testing, had a mean cholesterol level of 213 mg/100 ml, a mean HDL cholesterol of 51 mg/100 ml and a mean cholesterol/HDL ratio of 4.4. The mean values of cholesterol, HDL cholesterol and cholesterol/HDL cholesterol did not differ significantly in men with normal angiographic finding and those with subcritical coronary disease. However, 14 of 16 men with coronary artery disease had a cholesterol/HDL ratio of 6.0 or more whereas only 4 men with normal coronary arteries had a ratio of 6.0 or more. Of the classical coronary risk factors evaluated, the cholesterol/HDL ratio of 6.0 or more had the highest odds ratio (172:1). It appears that determination of HDL cholesterol level helps to identify asymptomatic persons with a greater risk of having coronary artery disease.

  14. 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.

  15. Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

    SciTech Connect

    Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun; Cho, Sang Nae; Barry, Clifton E.; Via, Laura E.; Swanson, Basil I.; Mukundan, Harshini

    2013-02-14

    Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum, and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.

  16. Association of lipoarabinomannan with high density lipoprotein in blood: Implications for diagnostics

    DOE PAGES

    Sakamuri, Rama Murthy; Price, Dominique N.; Lee, Myungsun; ...

    2013-02-14

    Understanding the pathophysiology of tuberculosis, and the bio-distribution of pathogen-associated molecules in the host is essential for the development of efficient methods of intervention. One of the key virulence factors in the pathology of tuberculosis infection is Lipoarabinomannan (LAM). Previously, we have demonstrated the reliable detection of LAM in urine from tuberculosis patients in a sandwich immunoassay format. We also applied an ultra-sensitive detection strategy developed for amphiphilic biomarkers, membrane insertion, to the detection of LAM with a limit of detection of 10 fM. Herein, we evaluate the application of membrane insertion to the detection of LAM in patient serum,more » and demonstrate that the circulating concentrations of ‘monomeric’ LAM in serum are very low, despite significantly higher concentrations in the urine. Using spiked samples, we demonstrate that this discrepancy is due to the association of LAM with high-density lipoprotein (HDL) nanodiscs in human serum. Indeed, pull-down of HDL nanodiscs from human serum allows for the recovery of HDL-associated LAM. These studies suggest that LAM is likely associated with carrier molecules such as HDL in the blood of patients infected with tuberculosis. Furthermore, this phenomenon may not be limited to LAM in that many pathogen-associated molecular patterns like LAM are amphiphilic in nature and may also be associated with host lipid carriers. Such interactions are likely to affect host–pathogen interactions, pathogen bio-distribution and clearance in the host, and must be thoroughly understood for the effective design of vaccines and diagnostics.« less

  17. 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

  18. 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.

  19. Size is a major determinant of dissociation and denaturation behaviour of reconstituted high-density lipoproteins.

    PubMed

    Gianazza, Elisabetta; Eberini, Ivano; Sirtori, Cesare R; Franceschini, Guido; Calabresi, Laura

    2002-08-15

    Lipid-free apolipoprotein A-I (apoA-I) and A-I(Milano) (A-I(M)) were compared for their denaturation behaviour by running across transverse gradients of a chaotrope, urea, and of a ionic detergent, SDS. For both apo A-I and monomeric apoA-I(M) in the presence of increasing concentrations of urea the transition from high to low mobility had a sigmoidal course, whereas for dimeric A-I(M)/A-I(M) a non-sigmoidal shape was observed. The co-operativity of the unfolding process was lower for dimeric A-I(M)/A-I(M) than for apoA-I or for monomeric apoA-I(M). A slightly higher susceptibility to denaturation was observed for dimeric A-I(M)/A-I(M) than for monomeric apoA-I(M). A similar behaviour of A-I(M)/A-IM versus apoA-I(M) was observed in CD experiments. Large- (12.7/12.5 nm) and small- (7.8 nm) sized reconstituted high-density lipoproteins (rHDL) containing either apoA-I or A-I(M)/A-I(M) were compared with respect to their protein-lipid dissociation behaviour by subjecting them to electrophoresis in the presence of urea, of SDS and of a non-ionic detergent, Nonidet P40. A higher susceptibility to dissociation of small-sized versus large-sized rHDL, regardless of the apolipoprotein component, was observed in all three instances. Our data demonstrate that the differential plasticity of the various classes of rHDL is a function of their size; the higher stability of 12.5/12.7 nm rHDL is likely connected to the higher number of protein-lipid and lipid-lipid interactions in larger as compared with smaller rHDL.

  20. High-Density and Very-Low-Density Lipoprotein Have Opposing Roles in Regulating Tumor-Initiating Cells and Sensitivity to Radiation in Inflammatory Breast Cancer

    SciTech Connect

    Wolfe, Adam R.; Atkinson, Rachel L.; Reddy, Jay P.; Debeb, Bisrat G.; Larson, Richard; Li, Li; Masuda, Hiroko; Brewer, Takae; Atkinson, Bradley J.; Brewster, Abeena; Ueno, Naoto T.; Woodward, Wendy A.

    2015-04-01

    Purpose: We previously demonstrated that cholesterol-lowering agents regulate radiation sensitivity of inflammatory breast cancer (IBC) cell lines in vitro and are associated with less radiation resistance among IBC patients who undergo postmastectomy radiation. We hypothesized that decreasing IBC cellular cholesterol induced by treatment with lipoproteins would increase radiation sensitivity. Here, we examined the impact of specific transporters of cholesterol (ie lipoproteins) on the responses of IBC cells to self-renewal and to radiation in vitro and on clinical outcomes in IBC patients. Methods and Materials: Two patient-derived IBC cell lines, SUM 149 and KPL4, were incubated with low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), or high-density lipoproteins (HDL) for 24 hours prior to irradiation (0-6 Gy) and mammosphere formation assay. Cholesterol panels were examined in a cohort of patients with primary IBC diagnosed between 1995 and 2011 at MD Anderson Cancer Center. Lipoprotein levels were then correlated to patient outcome, using the log rank statistical model, and examined in multivariate analysis using Cox regression. Results: VLDL increased and HDL decreased mammosphere formation compared to untreated SUM 149 and KPL4 cells. Survival curves showed enhancement of survival in both of the IBC cell lines when pretreated with VLDL and, conversely, radiation sensitization in all cell lines when pretreated with HDL. In IBC patients, higher VLDL values (>30 mg/dL) predicted a lower 5-year overall survival rate than normal values (hazard ratio [HR] = 1.9 [95% confidence interval [CI]: 1.05-3.45], P=.035). Lower-than-normal patient HDL values (<60 mg/dL) predicted a lower 5-year overall survival rate than values higher than 60 mg/dL (HR = 3.21 [95% CI: 1.25-8.27], P=.015). Conclusions: This study discovered a relationship among the plasma levels of lipoproteins, overall patient response, and radiation resistance in IBC patients

  1. Modifications in high-density lipoprotein lipid composition and structure alter the plasma distribution of free and liposomal annamycin.

    PubMed

    Wasan, K M; Ng, S; Cassidy, S M

    1997-07-01

    Recent studies have shown that changes in lipoprotein cholesterol and triglyceride concentration alters the plasma distribution of free (Ann.) and liposomal annamycin (LAnn) and that the majority of Ann. is associated with high-density lipoproteins (HDL) following the incubation in plasma of LAnn. To demonstrate that alterations in HDL lipid composition and HDL structure may influence the plasma distribution of Ann. and LAnn, Ann. and LAnn (20 micrograms/mL) were incubated in plasma pretreated with dithionitrobenzoate (DTNB, a compound which inhibits the conversion of free cholesterol to esterified cholesterol) 18 h prior to the experiment or in untreated plasma for 60 min at 37 degrees C. In addition, Ann. and LAnn were co-incubated with DTNB in plasma for 60 min at 37 degrees C. Following incubation the plasma was separated into its HDL, low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), and lipoprotein-deficient plasma (LPDP) fractions by ultracentrifugation and assayed for Ann. by fluorimetry. The HDL plasma cholesterol:triglyceride concentration ratio was significantly decreased following 18 h of DTNB pretreatment compared to untreated plasma controls. No significant differences in LDL/VLDL plasma cholesterol:triglyceride concentration ratio following 18 h of DTNB pretreatment was observed. An increased number of discoidal HDL particles were observed following 18 h of DTNB pretreatment. When Ann. was incubated in plasma pretreated with DTNB for 18 h the percentage of Ann. recovered in the HDL, LDL, and VLDL fractions significantly increased. However, the percentage of Ann. recovered within the LPDP fraction was significantly decreased. When LAnn was incubated in plasma pretreated with DTNB for 18 h the percentage of Ann. recovered in the HDL fraction significantly decreased. The percentage of Ann. recovered in the LPDP fraction significantly increased when LAnn was incubated in plasma pretreated with DTNB for 18 h. No significant differences

  2. The Application of a Modified d-ROMs Test for Measurement of Oxidative Stress and Oxidized High-Density Lipoprotein

    PubMed Central

    Ito, Fumiaki; Ito, Tomoyuki; Suzuki, Chinatsu; Yahata, Tomoyo; Ikeda, Kazuyuki; Hamaoka, Kenji

    2017-01-01

    Reactive oxygen species (ROS) are involved in the initiation and progression of atherosclerosis. ROS-derived hydroperoxides, as an indicator of ROS production, have been measured by using the diacron reactive oxygen metabolites (d-ROMs) test, which requires iron-containing transferrin in the reaction mixture. In this study we developed a modified d-ROMs test, termed the Fe-ROMs test, where iron ions were exogenously added to the reaction mixture. This modification is expected to exclude the assay variation that comes from different blood iron levels in individuals. In addition, this Fe-ROMs test was helpful for determining the class of plasma lipoproteins that are hydroperoxidized. Low-density lipoprotein/very low-density lipoprotein (LDL/VLDL) and high-density lipoprotein (HDL) were purified by use of an LDL/VLDL purification kit and the dextran sulfate-Mg2+ precipitation method, respectively; their hydroperoxide contents were assessed by performing the Fe-ROMs test. The majority of the hydroperoxides were detected only in the HDL fraction, not in the LDL/VLDL. Further detailed analysis of HDLs by size-exclusion high-performance liquid chromatography revealed that the hydroperoxide-containing molecules were small-sized HDLs. Because HDL was shown to be the principal vehicle for the plasma hydroperoxides, this Fe-ROMs test is a beneficial method for the assessment of oxidized-HDL levels. Indeed, Fe-ROMs levels were strongly associated with the levels of oxidized HDL, which were determined by performing the malondialdehyde-modified HDL enzyme immunoassay. In conclusion, the Fe-ROMs test using plasma itself or the HDL fraction after dextran sulfate-Mg2+ precipitation is useful to assess the functionality of HDL, because the oxidation of HDL impairs its antiatherogenic capacity. PMID:28230785

  3. The Application of a Modified d-ROMs Test for Measurement of Oxidative Stress and Oxidized High-Density Lipoprotein.

    PubMed

    Ito, Fumiaki; Ito, Tomoyuki; Suzuki, Chinatsu; Yahata, Tomoyo; Ikeda, Kazuyuki; Hamaoka, Kenji

    2017-02-21

    Reactive oxygen species (ROS) are involved in the initiation and progression of atherosclerosis. ROS-derived hydroperoxides, as an indicator of ROS production, have been measured by using the diacron reactive oxygen metabolites (d-ROMs) test, which requires iron-containing transferrin in the reaction mixture. In this study we developed a modified d-ROMs test, termed the Fe-ROMs test, where iron ions were exogenously added to the reaction mixture. This modification is expected to exclude the assay variation that comes from different blood iron levels in individuals. In addition, this Fe-ROMs test was helpful for determining the class of plasma lipoproteins that are hydroperoxidized. Low-density lipoprotein/very low-density lipoprotein (LDL/VLDL) and high-density lipoprotein (HDL) were purified by use of an LDL/VLDL purification kit and the dextran sulfate-Mg(2+) precipitation method, respectively; their hydroperoxide contents were assessed by performing the Fe-ROMs test. The majority of the hydroperoxides were detected only in the HDL fraction, not in the LDL/VLDL. Further detailed analysis of HDLs by size-exclusion high-performance liquid chromatography revealed that the hydroperoxide-containing molecules were small-sized HDLs. Because HDL was shown to be the principal vehicle for the plasma hydroperoxides, this Fe-ROMs test is a beneficial method for the assessment of oxidized-HDL levels. Indeed, Fe-ROMs levels were strongly associated with the levels of oxidized HDL, which were determined by performing the malondialdehyde-modified HDL enzyme immunoassay. In conclusion, the Fe-ROMs test using plasma itself or the HDL fraction after dextran sulfate-Mg(2+) precipitation is useful to assess the functionality of HDL, because the oxidation of HDL impairs its antiatherogenic capacity.

  4. High-density lipoprotein remains elevated despite reductions in total cholesterol in fasting adult male elephant seals (Mirounga angustirostris).

    PubMed

    Tift, Michael S; Houser, Dorian S; Crocker, Daniel E

    2011-08-01

    We examined changes in lipid profiles of 40 adult northern elephant seal bulls over the 3-month breeding fast and the 1-month molting fast to investigate impacts of fasting on serum total cholesterol (TC), triglycerides (TG) and lipoproteins. Total cholesterol and low-density lipoprotein (LDL) levels were initially high (3930 ± 190mgL(-1)and 1610 ± 170mgL(-1), respectively) and decreased significantly over the breeding season. Total cholesterol and LDL declined significantly with adipose tissue reserves (p<0.001), and LDL levels as low as 43 mgL(-1) were measured in seals late in the breeding fast. Less dramatic but similar changes in lipid metabolism were observed across the molting fast. High-density lipoproteins (HDL) remained consistently elevated (>1750 mgL(-1)) suggesting that elephant seals defend HDL concentrations, despite significant depletion of TC and LDL across the breeding fast. Triglyceride levels were significantly higher during the molt, consistent with lower rates of lipid oxidation needed to meet metabolic energy demands during this period. The maintenance of HDL during breeding is consistent with its role in delivering cholesterol from adipose tissue for steroidogenesis and spermatogenesis and potentially mitigates oxidative stress associated with fasting.

  5. 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.

  6. The intrinsic factor-vitamin B12 receptor, cubilin, is a high-affinity apolipoprotein A-I receptor facilitating endocytosis of high-density lipoprotein.

    PubMed

    Kozyraki, R; Fyfe, J; Kristiansen, M; Gerdes, C; Jacobsen, C; Cui, S; Christensen, E I; Aminoff, M; de la Chapelle, A; Krahe, R; Verroust, P J; Moestrup, S K

    1999-06-01

    Cubilin is the intestinal receptor for the endocytosis of intrinsic factor-vitamin B12. However, several lines of evidence, including a high expression in kidney and yolk sac, indicate it may have additional functions. We isolated apolipoprotein A-I (apoA-I), the main protein of high-density lipoprotein (HDL), using cubilin affinity chromatography. Surface plasmon resonance analysis demonstrated a high-affinity binding of apoA-I and HDL to cubilin, and cubilin-expressing yolk sac cells showed efficient 125I-HDL endocytosis that could be inhibited by IgG antibodies against apoA-I and cubilin. The physiological relevance of the cubilin-apoA-I interaction was further emphasized by urinary apoA-I loss in some known cases of functional cubilin deficiency. Therefore, cubilin is a receptor in epithelial apoA-I/HDL metabolism.

  7. 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

  8. Non-High-Density Lipoprotein Cholesterol in Children with Diabetes: Proposed Treatment Recommendations Based on Glycemic Control, Body Mass Index, Age, Sex, and Generally Accepted Cut Points.

    PubMed

    Schwab, K Otfried; Doerfer, Jürgen; Hungele, Andreas; Scheuing, Nicole; Krebs, Andreas; Dost, Axel; Rohrer, Tilman R; Hofer, Sabine; Holl, Reinhard W

    2015-12-01

    Percentile-based non-high-density lipoprotein cholesterol levels were analyzed by glycemic control, weight, age, and sex of children with type 1 diabetes (n = 26,358). Ten percent of all children and 25% of overweight adolescent girls require both immediate lipid-lowering medication and lifestyle changes to achieve non-high-density lipoprotein cholesterol levels <120 mg/dL and cardiovascular risk reduction.

  9. 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.

  10. 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

  11. 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.

  12. Synthesis and Characterization of Biomimetic High Density Lipoprotein Nanoparticles To Treat Lymphoma

    NASA Astrophysics Data System (ADS)

    Damiano, Marina Giacoma

    High density lipoproteins (HDLs), natural nanoparticles that function as vehicles for cholesterol transport, have enhanced uptake by several human cancers. This uptake is mediated, in part, by the high affinity HDL receptor, scavenger receptor B-1 (SR-B1). More specifically, studies show that the rate of cellular proliferation of lymphoma, a cancer of the lymphocytes, is directly proportional to the amount of HDL-cholesterol available. Thus, targeting of HDL-cholesterol uptake by these cells could be an effective therapeutic approach that may have lower toxicity to healthy cells compared to conventional therapies. Biomimetic HDL can be synthesized using a gold nanoparticle template (HDL-AuNPs), which provides control over size, shape, and surface chemistry. Like their natural counterparts, HDL-AuNPs sequester cholesterol. However, since the gold nanoparticle replaces the cholesterol core of natural HDL, HDL-AuNPs inherently deliver less cholesterol. We show that HDL-AuNPs are able to induce dose dependent apoptosis in B cell lymphoma cell lines and reduce tumor volume following systemic administration to mice bearing B cell lymphoma tumors. Furthermore, HDL-AuNPs are neither toxic to healthy human lymphocytes (SR-B1-), nor to hepatocytes and macrophages (SR-B1+), which are cells naturally encountered by HDLs. Manipulation of cholesterol flux and targeting of SR-B1 are responsible for the efficacy of HDL-AuNPs against B cell lymphoma. HDL-AuNPs could be used to treat B cell lymphomas and other diseases that involve pathologic accumulation of cholesterol. Titanium dioxide nanoparticle (TiO2 NP) core HDLs (HDL-TiO 2 NPs) have been synthesized for high resolution cellular localization studies and for future use as a therapeutic and imaging agent. In initial studies, HDL-TiO(2 NPs display maximum uptake in B cell lymphoma cell lines. X-ray fluorescence microscopy studies show interaction between HDL-TiO2 NPs and cells 10 minutes after treatment and internalization after

  13. 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

  14. 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.

  15. 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.

  16. High-density lipoproteins potentiate α1-antitrypsin therapy in elastase-induced pulmonary emphysema.

    PubMed

    Moreno, Juan-Antonio; Ortega-Gomez, Almudena; Rubio-Navarro, Alfonso; Louedec, Liliane; Ho-Tin-Noé, Benoit; Caligiuri, Giuseppina; Nicoletti, Antonino; Levoye, Angelique; Plantier, Laurent; Meilhac, Olivier

    2014-10-01

    Several studies report that high-density lipoproteins (HDLs) can carry α1-antitrypsin (AAT; an elastase inhibitor). We aimed to determine whether injection of exogenous HDL, enriched or not in AAT, may have protective effects against pulmonary emphysema. After tracheal instillation of saline or elastase, mice were randomly treated intravenously with saline, human plasma HDL (75 mg apolipoprotein A1/kg), HDL-AAT (75 mg apolipoprotein A1-3.75 mg AAT/kg), or AAT alone (3.75 mg/kg) at 2, 24, 48, and 72 hours. We have shown that HDL-AAT reached the lung and prevented the development of pulmonary emphysema by 59.3% at 3 weeks (alveoli mean chord length, 22.9 ± 2.8 μm versus 30.7 ± 4.5 μm; P < 0.001), whereas injection of HDL or AAT alone only showed a moderate, nonsignificant protective effect (28.2 ± 4.2 μm versus 30.7 ± 5 μm [P = 0.23] and 27.3 ± 5.66 μm versus 30.71 ± 4.96 μm [P = 0.18], respectively). Indeed, protection by HDL-AAT was significantly higher than that observed with HDL or AAT (P = 0.006 and P = 0.048, respectively). This protective effect was associated (at 6, 24, and 72 h) with: (1) a reduction in neutrophil and macrophage number in the bronchoalveolar lavage fluid; (2) decreased concentrations of IL-6, monocyte chemoattractant protein-1, and TNF-α in both bronchoalveolar lavage fluid and plasma; (3) a reduction in matrix metalloproteinase-2 and matrix metalloproteinase-9 activities; and (4) a reduction in the degradation of fibronectin, a marker of tissue damage. In addition, HDL-AAT reduced acute cigarette smoke-induced inflammatory response. Intravenous HDL-AAT treatment afforded a better protection against elastase-induced pulmonary emphysema than AAT alone, and may represent a significant development for the management of emphysema associated with AAT deficiency.

  17. 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.

  18. 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

  19. High-density lipoprotein-cholesterol levels and risk of cancer in HIV-infected subjects

    PubMed Central

    Squillace, Nicola; Galli, Laura; Bandera, Alessandra; Castagna, Antonella; Madeddu, Giordano; Caramello, Pietro; Antinori, Andrea; Cattelan, Annamaria; Maggiolo, Franco; Cingolani, Antonella; Gori, Andrea; Monforte, Antonella d’Arminio

    2016-01-01

    Abstract Investigation of the relationship between high-density lipoprotein-cholesterol (HDL-c) and the risk of developing cancer in a prospective cohort of human immunodeficiency virus (HIV)-infected patients. The Italian Cohort of Antiretroviral-naïve Patients Foundation Cohort is an Italian multicenter observational study recruiting HIV-positive patients while still antiretroviral treatment-naïve, regardless of the reason since 1997. Patients with at least 1 HDL-c value per year since enrollment and one such value before antiretroviral treatment initiation were included. HDL-c values were categorized as either low (<39 mg/dL in males or <49 mg/dL in females) or normal. Cancer diagnoses were classified as AIDS-defining malignancies (ADMs) or non-AIDS-defining malignancies (NADMs). Kaplan–Meier curves and Cox proportional-hazards regression models were used. Among 4897 patients (13,440 person-years of follow-up [PYFU]), 104 diagnoses of cancer were observed (56 ADMs, 48 NADMs) for an overall incidence rate of 7.7 (95% confidence interval [CI] 6.3–9.2) per 1000 PYFU. Low HDL-c values at enrollment were associated with higher risk both of cancer (crude hazard ratio [HR] 1.72, 95% CI 1.16–2.56, P = 0.007) and of NADM (crude HR 2.50, 95% CI 1.35–4.76, P = 0.003). Multivariate analysis showed that the risk of cancer diagnosis was higher in patients with low HDL-c values (adjusted HR [AHR] 1.87, 95% CI 1.18–2.95, P = 0.007) in older patients, those patients more recently enrolled, and in those with low current cluster of differentiation 4+ levels, and/or high current HIV-ribonucleic acid. The multivariate model confirmed an association between HDL-c (AHR 2.61, 95% CI 1.40–4.89, P = 0.003) and risk of NADM. Low HDL-c is an independent predictor of cancer in HIV-1-infected subjects. PMID:27603338

  20. Genetic analysis of long-lived families reveals novel variants influencing high density-lipoprotein cholesterol

    PubMed Central

    Feitosa, Mary F.; Wojczynski, Mary K.; Straka, Robert; Kammerer, Candace M.; Lee, Joseph H.; Kraja, Aldi T.; Christensen, Kaare; Newman, Anne B.; Province, Michael A.; Borecki, Ingrid B.

    2014-01-01

    The plasma levels of high-density lipoprotein cholesterol (HDL) have an inverse relationship to the risks of atherosclerosis and cardiovascular disease (CVD), and have also been associated with longevity. We sought to identify novel loci for HDL that could potentially provide new insights into biological regulation of HDL metabolism in healthy-longevous subjects. We performed a genome-wide association (GWA) scan on HDL using a mixed model approach to account for family structure using kinship coefficients. A total of 4114 subjects of European descent (480 families) were genotyped at ~2.3 million SNPs and ~38 million SNPs were imputed using the 1000 Genome Cosmopolitan reference panel in MACH. We identified novel variants near-NLRP1 (17p13) associated with an increase of HDL levels at genome-wide significant level (p < 5.0E-08). Additionally, several CETP (16q21) and ZNF259-APOA5-A4-C3-A1 (11q23.3) variants associated with HDL were found, replicating those previously reported in the literature. A possible regulatory variant upstream of NLRP1 that is associated with HDL in these elderly Long Life Family Study (LLFS) subjects may also contribute to their longevity and health. Our NLRP1 intergenic SNPs show a potential regulatory function in Encyclopedia of DNA Elements (ENCODE); however, it is not clear whether they regulate NLRP1 or other more remote gene. NLRP1 plays an important role in the induction of apoptosis, and its inflammasome is critical for mediating innate immune responses. Nlrp1a (a mouse ortholog of human NLRP1) interacts with SREBP-1a (17p11) which has a fundamental role in lipid concentration and composition, and is involved in innate immune response in macrophages. The NLRP1 region is conserved in mammals, but also has evolved adaptively showing signals of positive selection in European populations that might confer an advantage. NLRP1 intergenic SNPs have also been associated with immunity/inflammasome disorders which highlights the biological

  1. Fast and Simplified Method for High Through-put Isolation of miRNA from Highly Purified High Density Lipoprotein

    PubMed Central

    Seneshaw, Mulugeta; Mirshahi, Faridoddin; Min, Hae-Ki; Asgharpour, Amon; Mirshahi, Shervin; Daita, Kalyani; Boyett, Sherry; Santhekadur, Prasanna K.; Fuchs, Michael; Sanyal, Arun J.

    2016-01-01

    Small non-coding RNAs (miRNAs) have been implicated in a variety of human diseases including metabolic syndromes. They may be utilized as biomarkers for diagnosis and prognosis or may serve as targets for drug development, respectively. Recently it has been shown that miRNAs are carried in lipoproteins, particularly high density lipoproteins (HDL) and are delivered to recipient cells for uptake. This raises the possibility that miRNAs play a critical and pivotal role in cellular and organ function via regulation of gene expression as well as messenger for cell-cell communications and crosstalk between organs. Current methods for miRNA isolation from purified HDL are impractical when utilizing small samples on a large scale. This is largely due to the time consuming and laborious methods used for lipoprotein isolation. We have developed a simplified approach to rapidly isolate purified HDL suitable for miRNA analysis from plasma samples. This method should facilitate investigations into the role of miRNAs in health and disease and in particular provide new insights into the variety of biological functions, outside of the reverse cholesterol transport, that have been ascribed to HDL. Also, the miRNA species which are present in HDL can provide valuable information of clinical biomarkers for diagnosis of various diseases. PMID:27501005

  2. 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.

  3. Exercise attenuates the increase in plasma monounsaturated fatty acids and high-density lipoprotein cholesterol but not high-density lipoprotein 2b cholesterol caused by high-oleic ground beef in women.

    PubMed

    Gilmore, L Anne; Crouse, Stephen F; Carbuhn, Aaron; Klooster, Jennifer; Calles, José Antonio Elias; Meade, Thomas; Smith, Stephen B

    2013-12-01

    We hypothesized that dietary monounsaturated fatty acids (MUFA) and exercise increase high-density lipoprotein cholesterol (HDL-C) by independent mechanisms, so there would be additive effects between a single, intensive session of exercise and high-MUFA ground beef on HDL-C and blood risk factors for cardiovascular disease. Seventeen postmenopausal women completed a 2-way crossover design in which they consumed five 114-g ground beef patties per week for two 6-week periods separated by a 4-week washout (habitual diet) period. The ground beef patties contained 21% total fat with either 9.97 (low-MUFA) or 12.72 (high-MUFA) g total MUFA. Blood was taken at entry, at the end of each 6-week diet period, after the 4-week washout period, and 24 hours after aerobic exercise sessions (75% VO₂peak, 2.07 MJ). After the ground beef intervention, the high-MUFA ground beef increased plasma palmitoleic acid and oleic acid, low-density lipoprotein (LDL) particle density, HDL-C, and HDL2b-C (all P < .05), whereas the low-MUFA ground beef increased LDL density. After the washout (habitual diet) period, the single exercise session increased serum LDL cholesterol, HDL-C, and HDL2a and decreased TAG and oleic acid. After the low-MUFA ground beef diet, exercise increased LDL size and HDL density and decreased LDL density and very low-density lipoprotein cholesterol, but had no effect on HDL-C fractions. After the high-MUFA ground beef intervention, exercise decreased palmitioleic acid, oleic acid, HDL-C, and HDL2a-C, but not HDL2b-C. Contrary to our hypothesis, the effects of exercise and a high-MUFA diet were not additive; instead, exercise attenuated the effects of the high-MUFA ground beef on HDL-C and plasma MUFAs. The differential effects of high-MUFA ground beef and exercise on HDL2a-C and HDL2b-C indicate that diet and exercise affect HDL-C by different mechanisms.

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