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Camont L, Chapman MJ, Kontush A. Biological activities of HDL subpopulations and their relevance to cardiovascular disease. Trends Mol Med 2011; 17:594-603. [PMID: 21839683 DOI: 10.1016/j.molmed.2011.05.013] [Citation(s) in RCA: 329] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/05/2011] [Accepted: 05/27/2011] [Indexed: 01/02/2023]
Abstract
The concept of raising high-density lipoprotein (HDL) has been the focus of increasing attention as a strategy to reduce cardiovascular disease. HDL particles are, however, highly heterogeneous in structure, intravascular metabolism and biological activity. In this review, we describe major HDL subpopulations and discuss new findings on the antiatherogenic properties of HDL particles. Across the HDL subpopulation spectrum, small, dense, protein-rich HDLs display potent atheroprotective properties, which can be attributed to specific clusters of proteins and lipids; such activities can be compromised under conditions of atherogenic dyslipidemia. Comprehensive structural and compositional analyses of HDL may provide key information to identify subpopulations displaying specific biological functions and acquiring deficient functionality, with the potential to reveal novel biomarkers of cardiovascular risk and new pharmacological targets.
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Affiliation(s)
- Laurent Camont
- National Institute for Health and Medical Research (INSERM), Dyslipidemia, Inflammation and Atherosclerosis Research Unit (UMR 939), Paris F-75013, France
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102
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Brufau G, Groen AK, Kuipers F. Reverse cholesterol transport revisited: contribution of biliary versus intestinal cholesterol excretion. Arterioscler Thromb Vasc Biol 2011; 31:1726-33. [PMID: 21571685 DOI: 10.1161/atvbaha.108.181206] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Reverse cholesterol transport (RCT) is usually defined as high-density lipoprotein-mediated transport of excess cholesterol from peripheral tissues, including cholesterol-laden macrophages in vessel walls, to the liver. From the liver, cholesterol can then be removed from the body via secretion into the bile for eventual disposal via the feces. According to this paradigm, high plasma high-density lipoprotein levels accelerate RCT and hence are atheroprotective. New insights in individual steps of the RCT pathway, in part derived from innovative mouse models, indicate that the classical concept of RCT may require modification.
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Affiliation(s)
- Gemma Brufau
- Department of Pediatrics, University Medical Center Groningen, University of Groningen, The Netherlands
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103
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Effects of lecithin: Cholesterol acyltransferase genotypes, enzyme levels, and activity on high-density lipoprotein levels. J Clin Lipidol 2011; 5:152-158. [DOI: 10.1016/j.jacl.2011.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2010] [Revised: 02/15/2011] [Accepted: 02/22/2011] [Indexed: 11/21/2022]
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104
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Nijstad N, de Boer JF, Lagor WR, Toelle M, Usher D, Annema W, der Giet MV, Rader DJ, Tietge UJF. Overexpression of apolipoprotein O does not impact on plasma HDL levels or functionality in human apolipoprotein A-I transgenic mice. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:294-9. [PMID: 21296681 DOI: 10.1016/j.bbalip.2011.01.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2010] [Revised: 12/31/2010] [Accepted: 01/26/2011] [Indexed: 12/31/2022]
Abstract
Apolipoprotein (apo) O is a newly discovered apolipoprotein preferentially contained within HDL; however, currently, no data are available on the (patho)physiological effects of apoO. Therefore, the present study assessed the impact of apoO overexpression on (i) plasma lipids and lipoproteins as well as on (ii) HDL functionality. Human apoO was overexpressed by means of recombinant adenovirus (AdhapoO) in human apoA-I transgenic mice, a humanized mouse model of HDL metabolism. AdhapoO substantially increased apoO in plasma and within HDL. However, plasma triglycerides, phospholipids, total cholesterol and HDL cholesterol did not change. HDL size distribution, lipid composition and the apoA-I and the apoO distribution over the different HDL fractions separated by FPLC remained unaltered. Furthermore, enrichment of HDL with apoO did not impact on HDL functionality assessed in four independent ways, namely (i) stimulation of cholesterol efflux from macrophage foam cells, (ii) protection against LDL oxidation, (iii) anti-inflammatory activity on endothelial cells, and (iv) induction of vasodilation in isolated aortic rings ex vivo as a measure of stimulating vascular NO production. These results demonstrate that although overexpression of apoO results in a substantial enrichment of HDL particles with this novel apolipoprotein, apoO does not impact the plasma lipoprotein profile or HDL functionality.
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Affiliation(s)
- Niels Nijstad
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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105
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Crook MA. Paradoxical decrease in serum high-density lipoprotein cholesterol and lipid-lowering drugs. Ann Clin Biochem 2011; 48:3-4. [DOI: 10.1258/acb.2010.010269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- M A Crook
- Department of Clinical Biochemistry and Metabolic Medicine, University Hospital Lewisham, London SE13 6LH, UK; Department of Chemical Pathology and Metabolic Medicine, Guy's and St Thomas' Hospitals, London, UK; Department of Science, University of Greenwich, London SE10 9LS, UK
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106
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Impact of Unhealthy Lifestyle Behaviors and Obesity on Cholesteryl Ester Transfer Protein Among Adolescent Males. Arch Med Res 2011; 42:53-9. [DOI: 10.1016/j.arcmed.2010.11.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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107
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Osei-Hwedieh DO, Amar M, Sviridov D, Remaley AT. Apolipoprotein mimetic peptides: Mechanisms of action as anti-atherogenic agents. Pharmacol Ther 2010; 130:83-91. [PMID: 21172387 DOI: 10.1016/j.pharmthera.2010.12.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Accepted: 12/01/2010] [Indexed: 12/13/2022]
Abstract
Apolipoprotein mimetic peptides are short synthetic peptides that share structural, as well as biological features of native apolipoproteins. The early positive clinical trials of intravenous preparations of apoA-I, the main protein component of high density lipoproteins (HDL), have stimulated great interest in the use of apolipoprotein mimetic peptides as possible therapeutic agents. Currently, there are a wide variety of apolipoprotein mimetic peptides at various stages of drug development. These peptides typically have been designed to either promote cholesterol efflux or act as anti-oxidants, but they usually exert other biological effects, such as anti-inflammatory and anti-thrombotic effects. Uncertainty about which of these biological properties is the most important for explaining their anti-atherogenic effect is a major unresolved question in the field. Structure-function studies relating the in vitro properties of these peptides to their ability to reduce atherosclerosis in animal models may uncover the best rationale for the design of these peptides and may lead to a better understanding of the mechanisms behind the atheroprotective effect of HDL.
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Affiliation(s)
- David O Osei-Hwedieh
- Lipoprotein Metabolism Section, Cardio-pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, MD, USA
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108
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Luthi AJ, Patel PC, Ko CH, Mutharasan RK, Mirkin CA, Thaxton CS. Nanotechnology for synthetic high-density lipoproteins. Trends Mol Med 2010; 16:553-60. [PMID: 21087901 PMCID: PMC4076051 DOI: 10.1016/j.molmed.2010.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 10/12/2010] [Accepted: 10/12/2010] [Indexed: 01/04/2023]
Abstract
Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high-density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD.
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Affiliation(s)
- Andrea J. Luthi
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - Pinal C. Patel
- Interdepartmental Biological Sciences, Northwestern University, 2145 Sheridan Road, Evanston, Il 60203, USA
| | - Caroline H. Ko
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - R. Kannan Mutharasan
- Feinberg Cardiovascular Research Institute, Northwestern University, 303 E. Chicago Avenue, Chicago, IL 60611
| | - Chad A. Mirkin
- Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
| | - C. Shad Thaxton
- International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA
- Feinberg School of Medicine, Department of Urology, 303 E. Chicago Avenue, Tarry 16-703, Chicago, IL 60611, USA
- Institute for BioNanotechnology and Medicine, Northwestern University, 303 E. Superior, Suite 11-131, Chicago, IL 60611, USA
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Leança CC, Passarelli M, Nakandakare ER, Quintão ECR. HDL: o yin-yang da doença cardiovascular. ACTA ACUST UNITED AC 2010; 54:777-84. [DOI: 10.1590/s0004-27302010000900002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 10/22/2010] [Indexed: 11/22/2022]
Abstract
Estudos epidemiológicos mostram relação inversa entre níveis plasmáticos de HDL-colesterol (HDL-C) e incidência de doença cardiovascular (DCV). O papel antiaterogênico da HDL é atribuído às suas atividades anti-inflamatória, antitrombótica e antioxidante, além de sua participação no transporte reverso de colesterol (TRC), processo pelo qual a HDL remove colesterol dos tecidos periféricos, incluindo macrófagos da íntima arterial, e o transporta para o fígado para ser excretado pela bile. Com base nesses fatos, o HDL-C tornou-se alvo atrativo para a prevenção da DCV. No entanto, o fracasso do torcetrapib, droga que aumenta substancialmente os níveis de HDL-C, em prevenir DCV, além do conhecimento gerado por estudos de modelos animais e doenças monogênicas que afetam a concentração de HDL-C, tem suscitado questionamentos sobre o papel antiaterogênico da HDL. Esta revisão tem como objetivo abordar aspectos atuais do conhecimento da HDL, baseando-se nessas recentes controvérsias.
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110
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Friend Turns Foe: Transformation of Anti-Inflammatory HDL to Proinflammatory HDL during Acute-Phase Response. CHOLESTEROL 2010; 2011:274629. [PMID: 21490770 PMCID: PMC3065911 DOI: 10.1155/2011/274629] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 11/01/2010] [Indexed: 01/09/2023]
Abstract
High-density lipoprotein (HDL) is a major carrier of cholesterol in the blood. Unlike other lipoproteins, physiological functions of HDL influence the cardiovascular system in favorable ways except when HDL is modified pathologically. The cardioprotective mechanism of HDL is mainly based on reverse cholesterol transport, but there has been an emerging interest in the anti-inflammatory and antioxidant roles of HDL. These latter activities of HDL are compromised in many pathological states associated with inflammation. Further, abnormal HDL can become proinflammatory contributing to oxidative damage. In this paper, we discuss the functional heterogeneity of HDL, how alterations in these particles in inflammatory states result in loss of both antioxidant activity and reverse cholesterol transport in relation to atherosclerosis, and the need for assays to predict its functionality.
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111
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Oliveira TV, Maniero F, Santos MHH, Bydlowski SP, Maranhão RC. Impact of high cholesterol intake on tissue cholesterol content and lipid transfers to high-density lipoprotein. Nutrition 2010; 27:713-8. [PMID: 20934854 DOI: 10.1016/j.nut.2010.07.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 07/16/2010] [Accepted: 07/30/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE Esterified cholesterol is the storage form of cholesterol in the organism. High-density lipoprotein (HDL), where free cholesterol is transferred from other lipoproteins and tissues, is the main esterification site in plasma. The aim of this study was to investigate how high cholesterol intake changes free/esterified ratios of cholesterol in the plasma, aorta, liver and lipid transfers to HDL. METHODS Twenty male Golden Syrian hamsters fed 0.5% cholesterol for 15 wk and 19 controls without cholesterol feeding were sacrificed to determine serum lipids, transfer proteins (cholesteryl ester transfer protein and phospholipid transfer protein), and amount of free and esterified cholesterol in the aorta and liver. In vitro transfer of radioactive free and esterified cholesterol, phospholipids, and triacylglycerols to HDL was performed by incubating whole plasma with an artificial nanoemulsion used as a lipid donor and measuring radioactivity in the HDL fraction after chemical precipitation of non-HDL fractions and of the nanoemulsion. RESULTS Compared with controls, cholesterol-fed animals showed a 137% increase in non-HDL plasma fraction and a 61% increase in HDL (P < 0.001). The esterified/free cholesterol ratio in non-HDL and HDL fractions did not change. In the aorta, free cholesterol increased 55% and the esterified/free ratio (0.2) decreased. Cholesterol accumulation in the liver was several-fold greater and esterified/free increased (1.3). Cholesterol feeding pronouncedly increased the transfer of free and esterified cholesterol, phospholipids, and triacylglycerols to HDL and cholesteryl ester transfer protein and phospholipid transfer protein activities. CONCLUSIONS Free cholesterol is cytotoxic and less stable than esterified cholesterol, and the present data on how the organism responds to high cholesterol intake with respect to esterified/free ratios in the plasma, aorta, liver, and lipid transfers to HDL may have physiopathologic implications.
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Affiliation(s)
- Tatiane V Oliveira
- Lipid Metabolism Laboratory, Heart Institute (InCor), Medical School Hospital, University of São Paulo, São Paulo, Brazil
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112
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Agger SA, Marney LC, Hoofnagle AN. Simultaneous quantification of apolipoprotein A-I and apolipoprotein B by liquid-chromatography-multiple- reaction-monitoring mass spectrometry. Clin Chem 2010; 56:1804-13. [PMID: 20923952 DOI: 10.1373/clinchem.2010.152264] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND If liquid-chromatography-multiple-reaction-monitoring mass spectrometry (LC-MRM/MS) could be used in the large-scale preclinical verification of putative biomarkers, it would obviate the need for the development of expensive immunoassays. In addition, the translation of novel biomarkers to clinical use would be accelerated if the assays used in preclinical studies were the same as those used in the clinical laboratory. To validate this approach, we developed a multiplexed assay for the quantification of 2 clinically well-known biomarkers in human plasma, apolipoprotein A-I and apolipoprotein B (apoA-I and apoB). METHODS We used PeptideAtlas to identify candidate peptides. Human samples were denatured with urea or trifluoroethanol, reduced and alkylated, and digested with trypsin. We compared reversed-phase chromatographic separation of peptides with normal flow and microflow, and we normalized endogenous peptide peak areas to internal standard peptides. We evaluated different methods of calibration and compared the final method with a nephelometric immunoassay. RESULTS We developed a final method using trifluoroethanol denaturation, 21-h digestion, normal flow chromatography-electrospray ionization, and calibration with a single normal human plasma sample. For samples injected in duplicate, the method had intraassay CVs <6% and interassay CVs <12% for both proteins, and compared well with immunoassay (n = 47; Deming regression, LC-MRM/MS = 1.17 × immunoassay - 36.6; S(x|y) = 10.3 for apoA-I and LC-MRM/MS = 1.21 × immunoassay + 7.0; S(x|y) = 7.9 for apoB). CONCLUSIONS Multiplexed quantification of proteins in human plasma/serum by LC-MRM/MS is possible and compares well with clinically useful immunoassays. The potential application of single-point calibration to large clinical studies could simplify efforts to reduce day-to-day digestion variability.
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Affiliation(s)
- Sean A Agger
- Department of Laboratory Medicine, University of Washington, Seattle, WA 98195, USA
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113
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Zhao Y, Van Berkel TJ, Van Eck M. Relative roles of various efflux pathways in net cholesterol efflux from macrophage foam cells in atherosclerotic lesions. Curr Opin Lipidol 2010; 21:441-53. [PMID: 20683325 DOI: 10.1097/mol.0b013e32833dedaa] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Cholesterol efflux mechanisms are essential for macrophage cholesterol homeostasis. HDL, an important cholesterol efflux acceptor, comprises a class of heterogeneous particles that induce cholesterol efflux via distinct pathways. This review focuses on the understanding of the different cholesterol efflux pathways and physiological acceptors involved, and their regulation in atherosclerotic lesions. RECENT FINDINGS The synergistic interactions of ATP-binding cassette transporters A1 and G1 as well as ATP-binding cassette transporter A1 and scavenger receptor class B type I are essential for cellular cholesterol efflux and the prevention of macrophage foam cell formation. However, the importance of aqueous diffusion should also not be underestimated. Significant progress has been made in understanding the mechanisms underlying ATP-binding cassette A1-mediated cholesterol efflux and regulation of its expression and trafficking. Conditions locally in the atherosclerotic lesion, for example, lipids, cytokines, oxidative stress, and hypoxia, as well as systemic factors, including inflammation and diabetes, critically influence the expression of cholesterol transporters on macrophage foam cells. Furthermore, HDL modification and remodeling in atherosclerosis, inflammation, and diabetes impairs its function as an acceptor for cellular cholesterol. SUMMARY Recent advances in the understanding of the regulation of cholesterol transporters and their acceptors in atherosclerotic lesions indicate that HDL-based therapies should aim to enhance the activity of cholesterol transporters and improve both the quantity and quality of HDL.
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Affiliation(s)
- Ying Zhao
- Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Leiden, The Netherlands
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114
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Affiliation(s)
- Daniel S. Ory
- From the Diabetic Cardiovascular Disease Center and the Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Jean E. Schaffer
- From the Diabetic Cardiovascular Disease Center and the Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
- Corresponding author: Jean E. Schaffer,
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115
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Waterworth DM, Ricketts SL, Song K, Chen L, Zhao JH, Ripatti S, Aulchenko YS, Zhang W, Yuan X, Lim N, Luan J, Ashford S, Wheeler E, Young EH, Hadley D, Thompson JR, Braund PS, Johnson T, Struchalin M, Surakka I, Luben R, Khaw KT, Rodwell SA, Loos RJF, Boekholdt SM, Inouye M, Deloukas P, Elliott P, Schlessinger D, Sanna S, Scuteri A, Jackson A, Mohlke KL, Tuomilehto J, Roberts R, Stewart A, Kesäniemi YA, Mahley RW, Grundy SM, McArdle W, Cardon L, Waeber G, Vollenweider P, Chambers JC, Boehnke M, Abecasis GR, Salomaa V, Järvelin MR, Ruokonen A, Barroso I, Epstein SE, Hakonarson HH, Rader DJ, Reilly MP, Witteman JCM, Hall AS, Samani NJ, Strachan DP, Barter P, van Duijn CM, Kooner JS, Peltonen L, Wareham NJ, McPherson R, Mooser V, Sandhu MS. Genetic variants influencing circulating lipid levels and risk of coronary artery disease. Arterioscler Thromb Vasc Biol 2010; 30:2264-76. [PMID: 20864672 DOI: 10.1161/atvbaha.109.201020] [Citation(s) in RCA: 318] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Genetic studies might provide new insights into the biological mechanisms underlying lipid metabolism and risk of CAD. We therefore conducted a genome-wide association study to identify novel genetic determinants of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides. METHODS AND RESULTS We combined genome-wide association data from 8 studies, comprising up to 17 723 participants with information on circulating lipid concentrations. We did independent replication studies in up to 37 774 participants from 8 populations and also in a population of Indian Asian descent. We also assessed the association between single-nucleotide polymorphisms (SNPs) at lipid loci and risk of CAD in up to 9 633 cases and 38 684 controls. We identified 4 novel genetic loci that showed reproducible associations with lipids (probability values, 1.6×10(-8) to 3.1×10(-10)). These include a potentially functional SNP in the SLC39A8 gene for HDL-C, an SNP near the MYLIP/GMPR and PPP1R3B genes for LDL-C, and at the AFF1 gene for triglycerides. SNPs showing strong statistical association with 1 or more lipid traits at the CELSR2, APOB, APOE-C1-C4-C2 cluster, LPL, ZNF259-APOA5-A4-C3-A1 cluster and TRIB1 loci were also associated with CAD risk (probability values, 1.1×10(-3) to 1.2×10(-9)). CONCLUSIONS We have identified 4 novel loci associated with circulating lipids. We also show that in addition to those that are largely associated with LDL-C, genetic loci mainly associated with circulating triglycerides and HDL-C are also associated with risk of CAD. These findings potentially provide new insights into the biological mechanisms underlying lipid metabolism and CAD risk.
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116
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Abstract
Atherosclerosis is the leading cause of death in developed countries. High density lipoproteins (HDL) cholesterol level correlates inversely with the risk of cardiovascular diseases. Thus, HDL has obtained lots of interest for drug development. In this review, we summarized the mechanisms for the antiatherogenic function of HDL, current HDL-based drugs in clinical use and the future direction for HDL-based therapy development.
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Affiliation(s)
- Xuan Gao
- Departments of Physiology and Biophysics, Boston University School of Medicine, 700 Albany St. W302, Boston, MA 02118, USA
| | - Shujun Yuan
- Departments of Physiology and Biophysics, Boston University School of Medicine, 700 Albany St. W302, Boston, MA 02118, USA
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117
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Abstract
PURPOSE OF REVIEW HDL is a cardioprotective lipoprotein, at least in part, because of its ability to mediate reverse cholesterol transport (RCT). It is becoming increasingly clear that the antiatherogenic effects of HDL are not only dependent on its concentration in circulating blood but also on its biological 'quality'. This review summarizes our current understanding of how the biological activities of individual subclasses of HDL particles contribute to overall HDL performance in RCT. RECENT FINDINGS Recent work indicates that apolipoprotein A-I-containing nascent HDL particles are heterogeneous and that such particles exert different effects on the RCT pathway. RCT from macrophages has been examined in detail in mice and the roles of plasma factors (lecithin-cholesterol acyltransferase, cholesterol ester transfer protein, phospholipid transfer protein) and cell factors (ATP-binding cassette transporter A1, ATP-binding cassette transporter G1, scavenger receptor class B type 1) have been evaluated. Manipulation of such factors has consistent effects on RCT and atherosclerosis, but the level of plasma HDL does not reliably predict the degree of RCT. Furthermore, HDL cholesterol or apolipoprotein A-I levels do not necessarily correlate with the magnitude of cholesterol efflux from macrophages; more understanding of the contributions of specific HDL subspecies is required. SUMMARY The antiatherogenic quality of HDL is defined by the functionality of HDL subspecies. In the case of RCT, the rate of cholesterol movement through the pathway is critical and the contributions of particular types of HDL particles to this process are becoming better defined.
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Affiliation(s)
- George H Rothblat
- Gastroenterology, Hepatology and Nutrition Division, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4318, USA
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Viljoen A, Wierzbicki AS. Safety and efficacy of laropiprant and extended-release niacin combination in the management of mixed dyslipidemias and primary hypercholesterolemia. DRUG HEALTHCARE AND PATIENT SAFETY 2010; 2:61-71. [PMID: 21701618 PMCID: PMC3108693 DOI: 10.2147/dhps.s7302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Indexed: 01/26/2023]
Abstract
Statins form the cornerstone of pharmaceutical cardiovascular disease prevention. However, despite very effective statin intervention, the majority of events remain unpreventable. In some cases statin therapy alone is insufficient to achieve adequate lipid levels whereas other patients are unable to tolerate statins. This calls for additional treatment options. Niacin has a long history of success in reducing low-density lipoprotein cholesterol and triglycerides, and increasing high-density lipoprotein cholesterol. It was the first lipid-lowering drug to demonstrate a reduction in cardiovascular events, and remains the only one that has consistently shown benefits on surrogate outcomes when added to background therapies of other lipid-lowering drugs, including statins. Niacin’s uptake in clinical practice has been less successful due to its side-effect profile, most notable being flushing. The uncovering of the mechanism by which flushing is induced, together with the development of a prostaglandin D2 receptor inhibitor (laropiprant) which reduces this downstream flushing effect of niacin, has sparked new promise in therapeutic lipid management. It provides an additional treatment option into managing lipid abnormalities. The uptake in clinical practice of the niacin–laropiprant combination will depend on the relative improvements experienced by the patient in the side-effect profile compared to other treatment options, as well as on the the keenly-awaited outcome studies currently underway. Until these data become available guidelines and recommendations are unlikely to change and niacin’s position in therapeutic cardiovascular risk prevention will be determined by clinician opinion and experience, and patient preferences.
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Yvan-Charvet L, Kling J, Pagler T, Li H, Hubbard B, Fisher T, Sparrow CP, Taggart AK, Tall AR. Cholesterol efflux potential and antiinflammatory properties of high-density lipoprotein after treatment with niacin or anacetrapib. Arterioscler Thromb Vasc Biol 2010; 30:1430-8. [PMID: 20448206 DOI: 10.1161/atvbaha.110.207142] [Citation(s) in RCA: 199] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
OBJECTIVE To examine the effects of treatments with niacin or anacetrapib (an inhibitor of cholesteryl ester transfer protein) on the ability of high-density lipoprotein (HDL) to promote net cholesterol efflux and reduce toll-like receptor-mediated inflammation in macrophages. METHODS AND RESULTS A total of 18 patients received niacin, 2 g/d, for 4 weeks; 20 patients received anacetrapib, 300 mg/d, for 8 weeks; and 2 groups (n=4 and n=5 patients) received placebo. HDL samples were isolated by polyethylene glycol precipitation or ultracentrifugation, tested for the ability to promote cholesterol efflux in cholesterol-loaded THP-I or mouse peritoneal macrophages, or used to pretreat macrophages, followed by lipopolysaccharide exposure. HDL cholesterol levels were increased by 30% in response to niacin and by approximately 100% in response to anacetrapib. Niacin treatment increased HDL-mediated net cholesterol efflux from foam cells, primarily by increasing HDL concentration, whereas anacetrapib treatment increased cholesterol efflux by both increasing HDL concentration and causing increased efflux at matched HDL concentrations. The increased efflux potential of anacetrapib-HDL was more prominent at higher HDL cholesterol concentrations (>12 microg/mL), which was associated with an increased content of lecithin-cholesterol acyltransferase (LCAT) and apolipoprotein E and completely dependent on the expression of ATP binding cassette transporters (ABCA1 and ABCG1). Potent antiinflammatory effects of HDL were observed at low HDL concentrations (3 to 20 microg/mL) and were partly dependent on the expression of ABCA1 and ABCG1. All HDL preparations showed similar antiinflammatory effects, proportionate to the HDL cholesterol concentration. CONCLUSIONS Niacin treatment caused a moderate increase in the ability of HDL to promote net cholesterol efflux, whereas inhibition of cholesteryl ester transfer protein via anacetrapib led to a more dramatic increase in association with enhanced particle functionality at higher HDL concentrations. All HDLs exhibited potent ability to suppress macrophage toll-like receptor 4-mediated inflammatory responses, in a process partly dependent on cholesterol efflux via ABCA1 and ABCG1.
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Affiliation(s)
- Laurent Yvan-Charvet
- Division of Molecular Medicine, Department of Medicine, Columbia University, 630 W 168th St, New York, NY 10032, USA.
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Flores-Dorantes T, Arellano-Campos O, Posadas-Sánchez R, Villarreal-Molina T, Medina-Urrutia A, Romero-Hidalgo S, Yescas-Gómez P, Pérez-Méndez O, Jorge-Galarza E, Tusié-Luna T, Villalobos-Comparán M, Jacobo-Albavera L, Villamil-Ramírez H, López-Contreras BE, Aguilar-Salinas CA, Posadas-Romero C, Canizales-Quinteros S. Association of R230C ABCA1 gene variant with low HDL-C levels and abnormal HDL subclass distribution in Mexican school-aged children. Clin Chim Acta 2010; 411:1214-7. [PMID: 20427018 DOI: 10.1016/j.cca.2010.04.025] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 04/20/2010] [Accepted: 04/21/2010] [Indexed: 11/18/2022]
Abstract
BACKGROUND The effect of ABCA1 genetic variation on HDL-C levels has been widely documented, although studies in children are scarce. We recently found a frequent non-synonymous ABCA1 variant (R230C) exclusive to populations with Native American ancestry, associated with low HDL-C levels and other metabolic traits in adults. METHODS We genotyped R230C variant in 1253 healthy unrelated Mexican school-aged children aged 6-15 years (595 boys and 658 girls) to seek associations with HDL-C levels and other metabolic traits. HDL subclass distribution was analyzed in a subgroup of 81 age, gender and BMI-matched children. RESULTS Individuals carrying the C230 allele showed a significantly lower HDL-C levels (P=2.9x10(-8)), and higher TC/HDL-C ratio, BMI, BMI z-score and percent fat mass (P=0.001, 0.049, 0.032 and 0.039, respectively). HDL size was smaller in R230C heterozygotes as compared to R230R homozygotes (P<0.05). Moreover, the proportion of HDL(2b) was lower, while the proportion of HDL(3a) and HDL(3b) particles was higher in R230C heterozygous and/or C230C homozygous individuals as compared to R230R homozygotes (P<0.05). CONCLUSIONS Our data suggest that the R230C ABCA1 gene variant plays an important role in HDL-C level regulation and HDL subclass distribution in healthy Mexican school-aged children.
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Affiliation(s)
- Teresa Flores-Dorantes
- Unit of Molecular Biology and Genomic Medicine, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Shao B, Pennathur S, Pagani I, Oda MN, Witztum JL, Oram JF, Heinecke JW. Modifying apolipoprotein A-I by malondialdehyde, but not by an array of other reactive carbonyls, blocks cholesterol efflux by the ABCA1 pathway. J Biol Chem 2010; 285:18473-84. [PMID: 20378541 DOI: 10.1074/jbc.m110.118182] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Dysfunctional high density lipoprotein (HDL) is implicated in the pathogenesis of cardiovascular disease, but the underlying pathways remain poorly understood. One potential mechanism involves covalent modification by reactive carbonyls of apolipoprotein A-I (apoA-I), the major HDL protein. We therefore determined whether carbonyls resulting from lipid peroxidation (malondialdehyde (MDA) and hydroxynonenal) or carbohydrate oxidation (glycolaldehyde, glyoxal, and methylglyoxal) covalently modify lipid-free apoA-I and inhibit its ability to promote cellular cholesterol efflux by the ABCA1 pathway. MDA markedly impaired the ABCA1 activity of apoA-I. In striking contrast, none of the other four carbonyls were effective. Liquid chromatography-electrospray ionization-tandem mass spectrometry of MDA-modified apoA-I revealed that Lys residues at specific sites had been modified. The chief adducts were MDA-Lys and a Lys-MDA-Lys cross-link. Lys residues in the C terminus of apoA-I were targeted for cross-linking in high yield, and this process may hinder the interaction of apoA-I with lipids and ABCA1, two key steps in reverse cholesterol transport. Moreover, levels of MDA-protein adducts were elevated in HDL isolated from human atherosclerotic lesions, suggesting that lipid peroxidation might render HDL dysfunctional in vivo. Taken together, our observations indicate that MDA damages apoA-I by a pathway that generates lysine adducts at specific sites on the protein. Such damage may facilitate the formation of macrophage foam cells by impairing cholesterol efflux by the ABCA1 pathway.
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Affiliation(s)
- Baohai Shao
- Department of Medicine, University of Washington, Seattle, Washington 98195, USA.
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Vaisar T, Mayer P, Nilsson E, Zhao XQ, Knopp R, Prazen BJ. HDL in humans with cardiovascular disease exhibits a proteomic signature. Clin Chim Acta 2010; 411:972-9. [PMID: 20307520 DOI: 10.1016/j.cca.2010.03.023] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Revised: 03/09/2010] [Accepted: 03/15/2010] [Indexed: 02/02/2023]
Abstract
BACKGROUND Alterations in protein composition and oxidative damage of high density lipoprotein (HDL) have been proposed to impair the cardioprotective properties of HDL. We tested whether relative levels of proteins in HDL(2) could be used as biomarkers for coronary artery disease (CAD). METHODS Twenty control and eighteen CAD subjects matched for HDL-cholesterol, age, and sex were studied. HDL(2) isolated from plasma was digested with trypsin and analyzed by high-resolution matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) and pattern recognition analysis. RESULTS Partial least squares discriminant analysis (PLS-DA) of mass spectra clearly differentiated CAD from control subjects with area under the receiver operating characteristic curve (ROC(AUC)) of 0.94. Targeted tandem mass spectrometric analysis of the model's significant features revealed that HDL(2) of CAD subjects contained oxidized methionine residues of apolipoprotein A-I and elevated levels of apolipoprotein C-III. A proteomic signature composed of MALDI-MS signals from apoA-I, apoC-III, Lp(a) and apoC-I accurately classified CAD and control subjects (ROC(AUC)=0.82). CONCLUSIONS HDL(2) of CAD subjects carries a distinct protein cargo and that protein oxidation helps generate dysfunctional HDL. Moreover, models based on selected identified peptides in MALDI-TOF mass spectra of the HDL may have diagnostic potential.
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Affiliation(s)
- Tomás Vaisar
- Department of Medicine, School of Medicine, University of Washington, Seattle, Washington 98195, USA.
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Benefits and difficulties in measuring HDL subfractions and human paraoxonase-1 activity during statin treatment. Cardiovasc Drugs Ther 2010; 23:501-10. [PMID: 19859794 DOI: 10.1007/s10557-009-6205-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Dyslipidaemia including decreased high density lipoprotein cholesterol concentration is one of several factors that have been implicated in increased cardiovascular risk. Since their introduction in the 1980s, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) have emerged as the one of the best-selling class of medications to date, with numerous trials demonstrating powerful efficacy in preventing cardiovascular diseases. Although statins have been shown to modestly raise or not alter HDL-cholesterol, their effect on HDL subfractions and on HDL-associated enzymes including human paraoxonase-1 (PON1) has not yet been fully explored. This review summarizes the currently available data on the effect of statins on HDL subfractions and on PON1 activity with a particular emphasis on the clinical relevance of these effects. Moreover, methodological problems of HDL subfraction and PON1 activity determinations are also discussed.
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Gordon S, Durairaj A, Lu JL, Davidson WS. High-Density Lipoprotein Proteomics: Identifying New Drug Targets and Biomarkers by Understanding Functionality. CURRENT CARDIOVASCULAR RISK REPORTS 2010; 4:1-8. [PMID: 20625533 DOI: 10.1007/s12170-009-0069-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Recent proteomics studies on human plasma high-density lipoprotein (HDL) have discovered up to 50 individual protein constituents. Many of these have known functions that vary surprisingly from the lipid transport roles commonly thought to mediate HDL's ability to protect from coronary artery disease. Given newly discovered roles in inflammation, protease inhibition, complement regulation, and innate immunity, many have begun to view HDL as a broad collection of distinct particle subfamilies, each distinguished by unique protein compositions and functions. Herein we review recent applications of high-resolution proteomics to HDL and summarize evidence supporting the idea of HDL functional subspeciation. These studies have set the stage for a more complete understanding of the molecular basis of HDL functional heterogeneity and hold promise for the identification of new biomarkers that can predict disease or evaluate the success of clinical interventions.
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Affiliation(s)
- Scott Gordon
- Center for Lipid and Arteriosclerosis Science, University of Cincinnati, 2120 East Galbraith Road, Cincinnati, OH 45237-0507, USA
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125
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Duvillard L, Dautin G, Florentin E, Jeannin A, Pais de Barros JP, Lagrost L, Petit JM, Gambert P, Vergès B. Increased apolipoprotein AI production rate and redistribution of high-density lipoprotein size induced by estrogen plus progestin as oral contraceptive. J Clin Endocrinol Metab 2009; 94:4891-7. [PMID: 19858317 DOI: 10.1210/jc.2009-1402] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
CONTEXT The impact of estrogen plus progestin as an oral contraceptive on high density lipoprotein (HDL) apolipoprotein (apo) AI metabolism in humans is poorly understood. OBJECTIVES This study was designed to measure the in vivo effect of Moneva (30 microg ethinylestradiol, 75 microg gestodene) on HDL apoAI production rate and fractional catabolic rate. DESIGN Using (13)C-leucine, we performed two kinetic studies in the fed state in 10 normolipidemic young women, before and 3 months after beginning Moneva. RESULTS On Moneva, serum triglycerides increased by 12% (P = 0.03) in the fed state, whereas low-density lipoprotein and HDL cholesterol remained unchanged. HDL apoAI pool size and production rate were increased by 9.2% (67.3 +/- 7.1 vs. 61.6 +/- 6.7 mg x kg(-1); P = 0.05) and 26.5% (14.3 +/- 2.7 vs. 11.3 +/- 2.2 mg x kg(-1) x d(-1); P = 0.02), respectively. HDL apoAI fractional catabolic rate was not significantly modified. Three-month treatment by Moneva induced a shift of HDL size distribution from HDL2 toward HDL3 (HDL3 = 51.5 +/- 8.1 vs. 46.5 +/- 9.2% of total HDL; P = 0.02) and an increase in the proportion of apoAI among HDL components (38.8 +/- 4.3 vs. 34.4 +/- 2.8%; P = 0.01). CONCLUSION Oral contraception by estrogen plus progestin induces changes in HDL apoAI metabolism characterized by an increase in production rate and pool size, with a higher proportion of HDL3 particles. Whether or not these changes are beneficial to prevent atherosclerosis has to be explored further.
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Affiliation(s)
- Laurence Duvillard
- Institut National de la Santé et de la Recherche Médicale Unité 866-Université de Bourgogne, Faculté de Médecine, Dijon F-21000, France.
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Ohta S, Tanaka M, Sakakura K, Kawakami T, Aimoto S, Saito H. Defining lipid-binding regions of human serum amyloid A using its fragment peptides. Chem Phys Lipids 2009; 162:62-8. [DOI: 10.1016/j.chemphyslip.2009.07.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 06/30/2009] [Accepted: 07/31/2009] [Indexed: 11/30/2022]
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Yoshida H, Yanai H, Ito K, Tomono Y, Koikeda T, Tsukahara H, Tada N. Administration of natural astaxanthin increases serum HDL-cholesterol and adiponectin in subjects with mild hyperlipidemia. Atherosclerosis 2009; 209:520-3. [PMID: 19892350 DOI: 10.1016/j.atherosclerosis.2009.10.012] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 10/06/2009] [Indexed: 01/27/2023]
Abstract
BACKGROUND Astaxanthin has been reported to improve dyslipidemia and metabolic syndrome in animals, but such effects in humans are not well known. METHODS Placebo-controlled astaxanthin administration at doses of 0, 6, 12, 18 mg/day for 12 weeks was randomly allocated to 61 non-obese subjects with fasting serum triglyceride of 120-200mg/dl and without diabetes and hypertension, aged 25-60 years. RESULTS In before and after tests, body mass index (BMI) and LDL-cholesterol were unaffected at all doses, however, triglyceride decreased, while HDL-cholesterol increased significantly. Multiple comparison tests showed that 12 and 18 mg/day doses significantly reduced triglyceride, and 6 and 12 mg doses significantly increased HDL-cholesterol. Serum adiponectin was increased by astaxanthin (12 and 18 mg/day), and changes of adiponectin correlated positively with HDL-cholesterol changes independent of age and BMI. CONCLUSIONS This first-ever randomized, placebo-controlled human study suggests that astaxanthin consumption ameliorates triglyceride and HDL-cholesterol in correlation with increased adiponectin in humans.
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Affiliation(s)
- Hiroshi Yoshida
- Department of Laboratory Medicine, Jikei University Kashiwa Hospital, Chiba, Japan.
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128
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Zoppini G, Targher G, Chonchol M, Perrone F, Lippi G, Muggeo M. Higher HDL cholesterol levels are associated with a lower incidence of chronic kidney disease in patients with type 2 diabetes. Nutr Metab Cardiovasc Dis 2009; 19:580-586. [PMID: 19196499 DOI: 10.1016/j.numecd.2008.11.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 10/17/2008] [Accepted: 11/10/2008] [Indexed: 11/16/2022]
Abstract
BACKGROUND AND AIMS Type 2 diabetes is one of the most important risk factor for the development of chronic kidney disease (CKD). Recently, it has been shown that lower high-density lipoprotein cholesterol (HDL-C) levels predicted the development of microalbuminuria in type 2 diabetic individuals. We have prospectively assessed the effects of plasma HDL-C levels on the incidence of CKD in a large cohort of type 2 diabetic patients. METHODS AND RESULTS We followed 1987 type 2 diabetic outpatients with normal or near-normal kidney function at baseline for 5 years for the occurrence of incident CKD defined as glomerular filtration rate < or = 60 mL/min/1.73 m(2) (as estimated by the abbreviated Modified Diet and Renal Disease Study equation). Cox proportional hazards models were used to examine the independent relationship between plasma HDL-C levels and incident CKD. During a median follow-up of 5 years, 11.8% (n=234) of participants developed incident CKD. In multivariate regression analysis, higher HDL-C levels were associated with a lower risk of incident CKD (multiple-adjusted hazard ratio 0.76; 95% coefficient intervals 0.61-0.96; p=0.025) independently of age, gender, body mass index, hypertension, smoking history, diabetes duration, hemoglobin A1c, plasma triglycerides, LDL-cholesterol, presence of diabetic retinopathy, baseline albuminuria, and current use of medications (anti-hypertensive, anti-platelet, lipid-lowering and hypoglycemic drugs). CONCLUSIONS Higher plasma levels of HDL-C are associated with a lower risk of incident CKD in a large cohort of type 2 diabetic adults independently of numerous confounding factors.
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Affiliation(s)
- G Zoppini
- Section of Endocrinology, Department of Biomedical and Surgical Sciences, University of Verona, Ospedale Civile Maggiore, Piazzale Stefani, 1, 37126 Verona, Italy
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129
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Zhou H, Shiu SWM, Wong Y, Tan KCB. Impaired serum capacity to induce cholesterol efflux is associated with endothelial dysfunction in type 2 diabetes mellitus. Diab Vasc Dis Res 2009; 6:238-43. [PMID: 20368217 DOI: 10.1177/1479164109344934] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Reverse cholesterol transport (RCT) plays a protective role against atherosclerosis and cholesterol efflux from cells is an early step in the RCT pathway. We investigated whether the capacity of serum to induce cholesterol efflux was associated with endothelial dysfunction in type 2 diabetes. METHODS Endothelium-dependent and -independent vasodilation of the brachial artery was measured by high-resolution vascular ultrasound and serum cholesterol efflux capacity was determined by measuring the transfer of [3H]cholesterol from Fu5AH cells to serum in 137 patients with type 2 diabetes and 75 controls. RESULTS Serum cholesterol efflux capacity was lower in diabetic patients than in the controls (13.6+/-2.5% vs. 14.6+/-3.4%, respectively, p=0.02), and both endothelium-dependent vasodilation (4.9+/-2.2% vs. 8.8+/-4.1%, respectively, p<0.01) and endothelium-independent vasodilation were impaired (13.4+/-4.3% vs. 16.3+/-5.5%. respectively, p<0.01). Endothelium-dependent vasodilation correlated with serum cholesterol efflux capacity (r=0.26, p=0.003) in diabetic patients and controls (r=0.24, p=0.037). On general linear model analysis, the presence of diabetes, brachial artery diameter and serum cholesterol efflux capacity were significant independent determinants of endothelium-dependent vasodilation. CONCLUSION Impaired serum cholesterol efflux capacity was associated with endothelial dysfunction independent of other cardiovascular risk factors.
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Affiliation(s)
- Huali Zhou
- Department of Endocrinology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 310003, China
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130
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Arsenault BJ, Lemieux I, Després JP, Gagnon P, Wareham NJ, Stroes ES, Kastelein JJ, Khaw KT, Boekholdt SM. HDL particle size and the risk of coronary heart disease in apparently healthy men and women: The EPIC-Norfolk prospective population study. Atherosclerosis 2009; 206:276-81. [DOI: 10.1016/j.atherosclerosis.2009.01.044] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 01/30/2009] [Accepted: 01/31/2009] [Indexed: 11/24/2022]
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131
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Prospective studies on the relationship between high-density lipoprotein cholesterol and cardiovascular risk: a systematic review. ACTA ACUST UNITED AC 2009; 16:404-23. [DOI: 10.1097/hjr.0b013e32832c8891] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Epidemiological studies have extensively evaluated the association between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD) risk. The objective of this systematic review was to enumerate the number of original prospective studies that showed a significant association between HDL-C and CVD risk and provided evidence of the consistency of this association across other lipid risk factors. A systematic MEDLINE literature search identified 53 prospective cohort and five nested case-control studies that provided multivariate assessments of the association between HDL-C and CVD risk. Among these 58 prospective studies, 31 studies found a significant inverse association between HDL-C and CVD risk for all CVD outcomes and subpopulations studied, whereas 17 studies found a significant association for some CVD outcomes and/or subpopulations assessed. The ratio of studies that found a significant association out of the total studies identified was similar across all CVD outcomes, although there was less evidence for stroke and atherosclerotic outcomes. Only seven studies tested for the consistency of this association across other lipid risk factors, of which six studies suggested that the association was consistent across other lipid levels. In conclusion, the association between HDL-C and CVD risk is significant and strong, although further evidence may be needed to establish whether this association is consistent across other lipid risk factors. Furthermore, uncertainties remain regarding the mechanism in which HDL-C exerts its effects, suggesting a need for further research focused on new methods for reliable measurement.
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132
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Abstract
High-density lipoprotein (HDL) plays an important protective role against atherosclerosis, and the anti-atherogenic properties of HDL include the promotion of cellular cholesterol efflux and reverse cholesterol transport (RCT), as well as antioxidant, anti-inflammatory and anticoagulant effects. RCT is a complex pathway, which transports cholesterol from peripheral cells and tissues to the liver for its metabolism and biliary excretion. The major steps in the RCT pathway include the efflux of free cholesterol mediated by cholesterol transporters from cells to the main extracellular acceptor HDL, the conversion of free cholesterol to cholesteryl esters and the subsequent removal of cholesteryl ester in HDL by the liver. The efficiency of RCT is influenced by the mobilization of cellular lipids for efflux and the intravascular remodelling and kinetics of HDL metabolism. Despite the increased cardiovascular risk in people with type 2 diabetes, current knowledge on RCT in diabetes is limited. In this article, abnormalities in RCT in type 2 diabetes mellitus and therapeutic strategies targeting HDL and RCT will be reviewed.
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Affiliation(s)
- K C B Tan
- Department of Medicine, University of Hong Kong, Hong Kong.
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133
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Harangi M, Mirdamadi HZ, Seres I, Sztanek F, Molnár M, Kassai A, Derdák Z, Illyés L, Paragh G. Atorvastatin effect on the distribution of high-density lipoprotein subfractions and human paraoxonase activity. Transl Res 2009; 153:190-8. [PMID: 19304278 DOI: 10.1016/j.trsl.2009.01.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 01/22/2009] [Accepted: 01/23/2009] [Indexed: 11/26/2022]
Abstract
Human serum paraoxonase-1 (PON1) protects lipoproteins against oxidation by hydrolyzing lipid peroxides in oxidized low-density lipoprotein (LDL); therefore, it may protect against atherosclerosis. Changes in the ratio of high-density lipoprotein (HDL) subfractions may alter the stability and the antioxidant capacity of PON1. The aim of the study was to examine the effect of atorvastatin treatment on the distribution of HDL subfractions, LDL size, cholesteryl ester transfer protein (CETP), lecithin-cholesterol acyltransferase (LCAT), and PON1 activity. In all, 33 patients with type IIa and IIb hypercholesterolemia were involved in the study. LDL sizes and HDL subfractions were determined by gradient gel electrophoresis. CETP, LCAT, and PON1 activities were measured spectrophotometrically. Three months of treatment with atorvastatin 20 mg daily significantly increased the HDL3 (+8.13%) and decreased the HDL2a and HDL2b subfractions (-1.57% and -6.55%, respectively). The mean LDL size was significantly increased (+3.29%). The level of oxidized LDL was significantly decreased (-46.0%). The PON1 activity was augmented by the atorvastatin treatment (+5.0%). The CETP activity positively correlated with the HDL2b level and negatively correlated with the HDL3 and HDL2a levels. Atorvastatin alters the HDL subfractions, which may improve its antiatherogenic effect via enhancement of the PON1 activity.
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Affiliation(s)
- Mariann Harangi
- First Department of Medicine, University of Debrecen Medical and Health Science Center, Debrecen, Hungary.
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134
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Thaxton CS, Daniel WL, Giljohann DA, Thomas AD, Mirkin CA. Templated spherical high density lipoprotein nanoparticles. J Am Chem Soc 2009; 131:1384-5. [PMID: 19133723 DOI: 10.1021/ja808856z] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We report the synthesis of high density lipoprotein (HDL) biomimetic nanoparticles capable of binding cholesterol. These structures use a gold nanoparticle core to template the assembly of a mixed phospholipid layer and the adsorption of apolipoprotein A-I. These synthesized structures have the general size and surface composition of natural HDL and, importantly, bind free cholesterol (K(d) = 4 nM). The determination of the K(d) for these particles, with respect to cholesterol complexation, provides a key starting and comparison point for measuring and evaluating the properties of subsequently developed synthetic versions of HDL.
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Affiliation(s)
- C Shad Thaxton
- Northwestern University, Feinberg School of Medicine, Department of Urology, 303 East Chicago Avenue, Tarry 16-703, Chicago, Illinois 60611, USA.
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135
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Differential stability of high-density lipoprotein subclasses: effects of particle size and protein composition. J Mol Biol 2009; 387:628-38. [PMID: 19236880 DOI: 10.1016/j.jmb.2009.02.036] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2009] [Revised: 02/09/2009] [Accepted: 02/13/2009] [Indexed: 01/17/2023]
Abstract
High-density lipoproteins (HDLs) are complexes of proteins (mainly apoA-I and apoA-II) and lipids that remove cholesterol and prevent atherosclerosis. Understanding the distinct properties of the heterogeneous HDL population may aid the development of new diagnostic tools and therapies for atherosclerosis. Mature human HDLs form two major subclasses differing in particle diameter and metabolic properties, HDL(2) (large) and HDL(3) (small). These subclasses are comprised of HDL(A-I) containing only apoA-I, and HDL(A-I/A-II) containing apoA-I and apoA-II. ApoA-I is strongly cardioprotective, but the function of the smaller, more hydrophobic apoA-II is unclear. ApoA-II is thought to counteract the cardioprotective action of apoA-I by stabilizing HDL particles and inhibiting their remodeling. To test this notion, we performed the first kinetic stability study of human HDL subclasses. The results revealed that the stability of plasma spherical HDL decreases with increasing particle diameter; which may facilitate preferential cholesterol ester uptake from large lipid-loaded HDL(2). Surprisingly, size-matched plasma HDL(A-I/A-II) showed comparable or slightly lower stability than HDL(A-I); this is consistent with the destabilization of model discoidal HDL observed upon increasing the A-II to A-I ratio. These results clarify the roles of the particle size and protein composition in HDL remodeling, and help reconcile conflicting reports regarding the role of apoA-II in this remodeling.
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136
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Magkos F, Mohammed BS, Mittendorfer B. Plasma lipid transfer enzymes in non-diabetic lean and obese men and women. Lipids 2009; 44:459-64. [PMID: 19198915 DOI: 10.1007/s11745-009-3285-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 01/13/2009] [Indexed: 11/24/2022]
Abstract
There are considerable differences in the plasma lipid profile between lean and obese individuals and between men and women. Little, however, is known regarding the effects of obesity and sex on the plasma concentration of enzymes involved in intravascular lipid remodeling. Therefore, we measured the immunoreactive protein mass of lipoprotein lipase (LPL), hepatic lipase (HL), cholesterol-ester transfer protein (CETP) and lecithin-cholesterol acyl transferase (LCAT) in fasting plasma samples from 40 lean and 40 obese non-diabetic men and premenopausal women. Women, compared with men, had approximately 5% lower plasma LCAT (p < 0.041), approximately 35% greater LPL (p = 0.001) and approximately 10% greater CETP (p = 0.085) concentrations. Obese, compared with lean individuals of both sexes, had approximately 30% greater plasma LCAT (p < 0.001), approximately 20% greater CETP (p < 0.001) and approximately 20% greater LPL (p = 0.071) concentrations. Plasma HL concentration was not different in lean men and women. Obesity was associated with increased (by approximately 50%) plasma HL concentration in men (p = 0.018) but not in women; consequently, plasma HL concentration was lower in obese women than obese men (p = 0.009). In addition, there were direct correlations between plasma lipid transfer enzyme concentrations and lipoprotein particle concentrations and sizes. There are considerable differences in basal plasma lipid transfer enzyme concentrations between lean and obese subjects and between men and women, which may be partly responsible for respective differences in the plasma lipid profile.
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Affiliation(s)
- Faidon Magkos
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO 63110, USA
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137
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Is HDL function as important as HDL quantity in the coronary artery disease risk assessment? J Clin Lipidol 2009; 3:70-7. [PMID: 21291795 DOI: 10.1016/j.jacl.2009.02.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 01/28/2009] [Accepted: 02/04/2009] [Indexed: 01/09/2023]
Abstract
Over the past several decades, it has been clearly established that higher plasma concentrations of high-density lipoprotein (HDL) are related to lower risk of coronary artery disease (CAD). According to the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) guidelines, the HDL level of <40 mg/dL is considered low and is one of the CAD risk predictors. However, in the last decade, several studies have indicated the importance of the quality of HDL as another potential measure for CAD risk assessment. The loss of normal biological function of HDL particles as a result of multifactorial actions of chronic inflammation and acute phase responses has suggested a new potential pathway in the pathophysiology of atherosclerosis. The concept of "dysfunctional HDL" or "proinflammatory HDL," which exhibits chameleon-like properties of converting a positive force protecting arteries to a negative one, enhancing atherogenesis is now under active investigation. Measurements of this dysfunctional quality of HDL in cell-based or cell-free assays by analyzing anti-inflammatory functions may link these changes to in vivo assessments of vascular disease. This review provides details on functional and dysfunctional HDL and summarizes recent studies into dysfunctional HDL and its potential links to CAD.
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van Wijk DF, Stroes ESG, Monajemi H. Changing paradigm in HDL metabolism and cellular effects. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/17584299.4.1.17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Massey JB, Pownall HJ, Macha S, Morris J, Tubb MR, Silva RAGD. Mass spectrometric determination of apolipoprotein molecular stoichiometry in reconstituted high density lipoprotein particles. J Lipid Res 2009; 50:1229-36. [PMID: 19179308 DOI: 10.1194/jlr.d800044-jlr200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Plasma HDL-cholesterol and apolipoprotein A-I (apoA-I) levels are strongly inversely associated with cardiovascular disease. However, the structure and protein composition of HDL particles is complex, as native and synthetic discoidal and spherical HDL particles can have from two to five apoA-I molecules per particle. To fully understand structure-function relationships of HDL, a method is required that is capable of directly determining the number of apolipoprotein molecules in heterogeneous HDL particles. Chemical cross-linking followed by SDS polyacrylamide gradient gel electrophoresis has been previously used to determine apolipoprotein stoichiometry in HDL particles. However, this method yields ambiguous results due to effects of cross-linking on protein conformation and, subsequently, its migration pattern on the gel. Here, we describe a new method based on cross-linking chemistry followed by MALDI mass spectrometry that determines the absolute mass of the cross-linked complex, thereby correctly determining the number of apolipoprotein molecules in a given HDL particle. Using well-defined, homogeneous, reconstituted apoA-I-containing HDL, apoA-IV-containing HDL, as well as apoA-I/apoA-II-containing HDL, we have validated this method. The method has the capability to determine the molecular ratio and molecular composition of apolipoprotein molecules in complex reconstituted HDL particles.
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Affiliation(s)
- John B Massey
- Section of Atherosclerosis and Vascular Medicine, Department of Medicine, Baylor College of Medicine, Houston, TX 77030, USA
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Remaley AT, Amar M, Sviridov D. HDL-replacement therapy: mechanism of action, types of agents and potential clinical indications. Expert Rev Cardiovasc Ther 2009; 6:1203-15. [PMID: 18939908 DOI: 10.1586/14779072.6.9.1203] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
HDL-replacement therapy is a promising new treatment strategy involving the acute administration of HDL to rapidly stabilize patients at imminent risk for developing a myocardial infarction, such as those with acute coronary syndrome. This review will first focus on the anti-atherogenic mechanisms for HDL, such as the stimulation of the reverse cholesterol transport pathway, and then discuss the other potential beneficial biological effects of HDL on atherosclerosis. The various types of HDL-replacement therapies that are being investigated and developed will be reviewed and ongoing clinical trials and other possible clinical indications for HDL-replacement therapy besides the prevention of myocardial infarction will also be described. Finally, HDL-replacement therapy will be put into perspective by summarizing the current gaps in our knowledge of HDL metabolism and identifying challenges for future research in this area.
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Affiliation(s)
- Alan T Remaley
- National Institutes of Health, Lipoprotein Metabolism Section, Pulmonary and Vascular Medicine Branch, National Heart, Lung, and Blood Institute, Bethesda, MD 20892-21508, USA.
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Tsai MY, Li N, Sharrett AR, Shea S, Jacobs DR, Tracy R, Arnett D, Arends V, Post W. Associations of genetic variants in ATP-binding cassette A1 and cholesteryl ester transfer protein and differences in lipoprotein subclasses in the multi-ethnic study of atherosclerosis. Clin Chem 2009; 55:481-8. [PMID: 19131637 DOI: 10.1373/clinchem.2008.107995] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND ATP-binding cassette A1 (ABCA1) and cholesteryl ester transfer protein (CETP) play important roles in the reverse cholesterol transport pathway. The associations of ABCA1 and CETP polymorphisms with lipoprotein subclasses have not been extensively studied. METHODS We genotyped 2 ABCA1 and 5 CETP polymorphisms in 999 participants of the Multi-Ethnic Study of Atherosclerosis (MESA) and studied their associations with HDL and LDL subclass particle concentrations, measured by nuclear magnetic resonance spectroscopy. RESULTS ABCA1 and CETP polymorphisms were associated with different and distinct changes in lipoprotein subclass concentrations. The ABCA1 1051G/A AA genotype, previously found to be associated with cardioprotective effects in this cohort, was associated with a 5.5% higher concentration of small HDL particles (P = 0.024). The CETP TaqIB B2B2, -2505C/A AA, and -629C/A AA genotypes, previously demonstrated to lack cardioprotective effects, were associated with 15.2%, 15.4%, and 11.7% higher HDL cholesterol concentrations, respectively, and 36.5%, 40.7%, and 25.4% higher large HDL particle concentrations (P < 0.0001). The minor alleles of the A373P and R451Q polymorphisms were associated with lower large HDL particle concentrations. CONCLUSIONS Our study of the influence of ABCA1 and CETP genetic variants on lipoprotein subclasses demonstrates the importance of interpreting lipoprotein subclasses within the context of the biochemical processes involved in the alterations. In the case of HDL, the study of subclass particle numbers and sizes may not be sufficiently informative. Assays for HDL function may be needed to supplement quantification of HDL cholesterol and HDL particle numbers and sizes.
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Affiliation(s)
- Michael Y Tsai
- Laboratory Medicine & Pathology, University of Minnesota, Minneapolis, MN 55455-0392, USA.
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Kono M, Okumura Y, Tanaka M, Nguyen D, Dhanasekaran P, Lund-Katz S, Phillips MC, Saito H. Conformational flexibility of the N-terminal domain of apolipoprotein a-I bound to spherical lipid particles. Biochemistry 2008; 47:11340-7. [PMID: 18831538 DOI: 10.1021/bi801503r] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Lipid binding of human apolipoprotein A-I (apoA-I) occurs initially through the C-terminal alpha-helices followed by conformational reorganization of the N-terminal helix bundle. This led us to hypothesize that apoA-I has multiple lipid-bound conformations, in which the N-terminal helix bundle adopts either open or closed conformations anchored by the C-terminal domain. To investigate such possible conformations of apoA-I at the surface of a spherical lipid particle, site-specific labeling of the N- and C-terminal helices in apoA-I by N-(1-pyrene)maleimide was employed after substitution of a Cys residue for Val-53 or Phe-229. Neither mutagenesis nor the pyrene labeling caused discernible changes in the lipid-free structure and lipid interaction of apoA-I. Taking advantage of a significant increase in fluorescence when a pyrene-labeled helix is in contact with the lipid surface, we monitored the behaviors of the N- and C-terminal helices upon binding of apoA-I to egg PC small unilamellar vesicles. Comparison of the binding isotherms for pyrene-labeled apoA-I as well as a C-terminal helical peptide suggests that an increase in surface concentration of apoA-I causes dissociation of the N-terminal helix from the surface leaving the C-terminal helix attached. Consistent with this, isothermal titration calorimetry measurements showed that the enthalpy of apoA-I binding to the lipid surface under near saturated conditions is much less exothermic than that for binding at a low surface concentration, indicating the N-terminal helix bundle is out of contact with lipid at high apoA-I surface concentrations. Interestingly, the presence of cholesterol significantly induces the open conformation of the helix bundle. These results provide insight into the multiple lipid-bound conformations that the N-terminal helix bundle of apoA-I can adopt on a lipid or lipoprotein particle, depending upon the availability of space on the surface and the surface composition.
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Affiliation(s)
- Momoe Kono
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe 658-8558, Japan
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Sankaranarayanan S, Oram JF, Asztalos BF, Vaughan AM, Lund-Katz S, Adorni MP, Phillips MC, Rothblat GH. Effects of acceptor composition and mechanism of ABCG1-mediated cellular free cholesterol efflux. J Lipid Res 2008; 50:275-84. [PMID: 18827283 PMCID: PMC2636919 DOI: 10.1194/jlr.m800362-jlr200] [Citation(s) in RCA: 134] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Among the known mechanisms of reverse cholesterol transport (RCT), ATP binding cassette transporter G1 (ABCG1)-mediated free cholesterol (FC) transport is the most recent and least studied. Here, we have characterized the efficiencies of different acceptors using baby hamster kidney (BHK) cells transfected with human ABCG1 cDNA, which is inducible upon treatment with mifepristone. When normalized on particle number and particle surface area, the acceptor efficiency for FC efflux was as follows: small unilamellar vesicles (SUV)>LDL>reconstituted HDL>HDL(2) = HDL(3). Based on phospholipid content, the order was reversed. ABCG1 also mediated phospholipid efflux to human serum and HDL(3). ABCG1-mediated FC efflux correlated significantly with a number of HDL subfractions and components in serum collected from 25 normolipidemic individuals: apolipoprotein A-II (apoA-II) (r(2) = 0.7), apolipoprotein A-I (apoA-I) (r(2) = 0.5), HDL-C (r(2) = 0.4), HDL-PL (r(2) = 0.4), alpha-2 HDL (r(2) = 0.4), and prebeta HDL (r(2) = 0.2). ABCG1 did not enhance influx of FC or cholesteryl oleyl ether (COE) when cells were incubated with radiolabeled HDL(3). ABCG1 expression did not increase the association of HDL(3) with cells. Compared with control cells, ABCG1 expression significantly increased the FC pool available for efflux and the rate constant for efflux. In conclusion, composition and particle size determine the acceptor efficiency for ABCG1-mediated efflux. ABCG1 increases cell membrane FC pools and changes its rate of desorption into the aqueous phase without enhancing the association with the acceptor.
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Abstract
PURPOSE OF REVIEW To review new data concerning HDL metabolism and cardiovascular disease, the concept of HDL 'functionality', and HDL kinetics in the metabolic syndrome. RECENT FINDINGS HDL-apoA-I and apoA-II may be better predictors of cardiovascular disease than HDL-cholesterol. Cholesteryl ester transfer protein inhibition with torcetrapib does not benefit cardiovascular disease; whether this is related to 'congestion' of HDL transport or a specific off-target vasopressor effect remains unclear. Accelerated catabolism of HDL particles in metabolic syndrome could be due to increased hepatic secretion of apoB and apoC-III, hepatic steatosis, and low plasma adiponectin. The role of serum amyloid A and homocysteine is uncertain. In metabolic syndrome, therapies that could favourably alter HDL transport include weight loss, fish oils, higher dose statins, and fibrates; 'balancing feedback' may offset reduced catabolism of HDL, fenofibrate being the only agent hitherto shown to increase apoA-I production. SUMMARY Elevating HDL-apoA-I and apoA-II may be a more important therapeutic objective than increased HDL-cholesterol. Recent studies underscore the potential value of studying HDL functionality, particularly in the metabolic syndrome. Reverse cholesterol transport can only be reliably probed at present by studying the kinetics of HDL particles or apolipoproteins; new methods are needed for investigating cellular and whole body cholesterol turnover. In metabolic syndrome, HDL-raising therapies have differential impact on HDL kinetics, the optimal endpoint being to increase transport and concentration with unchanged or accelerated catabolism.
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Affiliation(s)
- Gerald F Watts
- Metabolic Research Centre, School of Medicine and Pharmacology, University of Western Australia, Perth, Australia.
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