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Darabi M, Kontush A. High-density lipoproteins (HDL): Novel function and therapeutic applications. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1867:159058. [PMID: 34624514 DOI: 10.1016/j.bbalip.2021.159058] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 08/16/2021] [Accepted: 08/25/2021] [Indexed: 12/30/2022]
Abstract
The failure of high-density lipoprotein (HDL)-raising agents to reduce cardiovascular disease (CVD) together with recent findings of increased cardiovascular mortality in subjects with extremely high HDL-cholesterol levels provide new opportunities to revisit our view of HDL. The concept of HDL function developed to explain these contradictory findings has recently been expanded by a role played by HDL in the lipolysis of triglyceride-rich lipoproteins (TGRLs) by lipoprotein lipase. According to the reverse remnant-cholesterol transport (RRT) hypothesis, HDL critically contributes to TGRL lipolysis via acquirement of surface lipids, including free cholesterol, released from TGRL. Ensuing cholesterol transport to the liver with excretion into the bile may reduce cholesterol influx in the arterial wall by accelerating removal from circulation of atherogenic, cholesterol-rich TGRL remnants. Such novel function of HDL opens wide therapeutic applications to reduce CVD in statin-treated patients, which primarily involve activation of cholesterol flux upon lipolysis.
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Affiliation(s)
- Maryam Darabi
- National Institute for Health and Medical Research (INSERM), UMRS 1166 ICAN, Faculty of Medicine Pitié-Salpêtrière, Sorbonne University, Paris, France
| | - Anatol Kontush
- National Institute for Health and Medical Research (INSERM), UMRS 1166 ICAN, Faculty of Medicine Pitié-Salpêtrière, Sorbonne University, Paris, France.
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2
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HDL and Reverse Remnant-Cholesterol Transport (RRT): Relevance to Cardiovascular Disease. Trends Mol Med 2020; 26:1086-1100. [DOI: 10.1016/j.molmed.2020.07.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/17/2022]
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Abstract
Cholesterol homeostasis is of central importance for life. Therefore, cells have developed a divergent set of pathways to meet their cholesterol needs. In this review, we focus on the direct transfer of cholesterol from lipoprotein particles to the cell membrane. More molecular details on the transfer of lipoprotein-derived lipids were gained by recent studies using phospholipid bilayers. While amphiphilic lipids are transferred right after contact of the lipoprotein particle with the membrane, the transfer of core lipids is restricted. Amphiphilic lipid transfer gains special importance in genetic diseases impairing lipoprotein metabolism like familial hypercholesterolemia. Taken together, these data indicate that there is a constant exchange of amphiphilic lipids between lipoprotein particles and the cell membrane.
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Neufeld EB, Sato M, Gordon SM, Durbhakula V, Francone N, Aponte A, Yilmaz G, Sviridov D, Sampson M, Tang J, Pryor M, Remaley AT. ApoA-I-Mediated Lipoprotein Remodeling Monitored with a Fluorescent Phospholipid. BIOLOGY 2019; 8:E53. [PMID: 31336888 PMCID: PMC6784057 DOI: 10.3390/biology8030053] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/01/2019] [Accepted: 07/08/2019] [Indexed: 01/10/2023]
Abstract
We describe simple, sensitive and robust methods to monitor lipoprotein remodeling and cholesterol and apolipoprotein exchange, using fluorescent Lissamine Rhodamine B head-group tagged phosphatidylethanolamine (*PE) as a lipoprotein reference marker. Fluorescent Bodipy cholesterol (*Chol) and *PE directly incorporated into whole plasma lipoproteins in proportion to lipoprotein cholesterol and phospholipid mass, respectively. *Chol, but not *PE, passively exchanged between isolated plasma lipoproteins. Fluorescent apoA-I (*apoA-I) specifically bound to high-density lipoprotein (HDL) and remodeled *PE- and *Chol-labeled synthetic lipoprotein-X multilamellar vesicles (MLV) into a pre-β HDL-like particle containing *PE, *Chol, and *apoA-I. Fluorescent MLV-derived *PE specifically incorporated into plasma HDL, whereas MLV-derived *Chol incorporation into plasma lipoproteins was similar to direct *Chol incorporation, consistent with apoA-I-mediated remodeling of fluorescent MLV to HDL with concomitant exchange of *Chol between lipoproteins. Based on these findings, we developed a model system to study lipid transfer by depositing fluorescent *PE and *Chol-labeled on calcium silicate hydrate crystals, forming dense lipid-coated donor particles that are readily separated from acceptor lipoprotein particles by low-speed centrifugation. Transfer of *PE from donor particles to mouse plasma lipoproteins was shown to be HDL-specific and apoA-I-dependent. Transfer of donor particle *PE and *Chol to HDL in whole human plasma was highly correlated. Taken together, these studies suggest that cell-free *PE efflux monitors apoA-I functionality.
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Affiliation(s)
- Edward B Neufeld
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Masaki Sato
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Scott M Gordon
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Vinay Durbhakula
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Nicolas Francone
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Angel Aponte
- Proteomics Core, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gizem Yilmaz
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Denis Sviridov
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Maureen Sampson
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jingrong Tang
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Milton Pryor
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alan T Remaley
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Abstract
PURPOSE OF REVIEW Cholesterol metabolism has been the object of intense investigation for decades. This review focuses on classical and novel methods assessing in vivo cholesterol metabolism in humans. Two factors have fueled cholesterol metabolism studies in the last few years: the renewed interest in the study of reverse cholesterol transport (RCT) as an atheroprotective mechanism and the importance of the gut microbiome in affecting cholesterol metabolism. RECENT FINDINGS Recent applications of these methods have spanned from the assessment of the effect on cholesterol synthesis, absorption or excretion of drugs (such as ezetimibe, PCSK9 inhibitors and plant sterols) and the gut microbiome to the more complex assessment of transintestinal cholesterol excretion (TICE) and RCT. SUMMARY These methods continue to be a valuable tool to answer novel questions and investigate the complexity of in-vivo cholesterol metabolism.
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Affiliation(s)
- John S Millar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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Abstract
Epidemiology studies have been carried out to investigate the association between alcohol consumption and the risk of gallstone disease, but the results remain controversial. We carried out a meta-analysis to quantitatively summarize the evidences from observational studies on alcohol consumption and the risk of gallstone disease. Eligible studies published in English were identified by searching PubMed, Web of Science, and Embase databases. The random-effect model was used to calculate the pooled relative risks (RRs) with 95% confidence intervals (CIs). Restricted cubic splines were used to assess the dose-response relationship. Eight cohort studies and 10 case-control studies were included in our meta-analysis. The pooled RR of gallstone disease for the highest versus the lowest alcohol consumption was 0.62 (95% CI: 0.49-0.78). Statistically significant associations were also found in stratified analysis by study design (cohort studies: RR=0.66, 95% CI: 0.48-0.91 and case-control studies: RR=0.58, 95% CI: 0.45-0.73). With respect to sex, both men (RR=0.57, 95% CI: 0.4-0.8) and women (RR=0.64, 95% CI: 0.53-0.77) showed statistically significant associations between alcohol consumption and the risk of gallstone disease. A linear dose-response relationship was found between alcohol consumption and gallstone disease risk and the risk of gallstone disease decreased by 12% (RR=0.88, 95% CI: 0.84-0.92; Pnonlinearity=0.079) for each 10 g/day increment in alcohol consumption. This meta-analysis suggests that alcohol consumption is associated with significantly decreased risk of gallstone disease.
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Cuchel M, Raper AC, Conlon DM, Pryma DA, Freifelder RH, Poria R, Cromley D, Li X, Dunbar RL, French B, Qu L, Farver W, Su CC, Lund-Katz S, Baer A, Ruotolo G, Akerblad P, Ryan CS, Xiao L, Kirchgessner TG, Millar JS, Billheimer JT, Rader DJ. A novel approach to measuring macrophage-specific reverse cholesterol transport in vivo in humans. J Lipid Res 2017; 58:752-762. [PMID: 28167703 DOI: 10.1194/jlr.m075226] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Indexed: 11/20/2022] Open
Abstract
Reverse cholesterol transport (RCT) is thought to be an atheroprotective function of HDL, and macrophage-specific RCT in mice is inversely associated with atherosclerosis. We developed a novel method using 3H-cholesterol nanoparticles to selectively trace macrophage-specific RCT in vivo in humans. Use of 3H-cholesterol nanoparticles was initially tested in mice to assess the distribution of tracer and response to interventions known to increase RCT. Thirty healthy subjects received 3H-cholesterol nanoparticles intravenously, followed by blood and stool sample collection. Tracer counts were assessed in plasma, nonHDL, HDL, and fecal fractions. Data were analyzed by using multicompartmental modeling. Administration of 3H-cholesterol nanoparticles preferentially labeled macrophages of the reticuloendothelial system in mice, and counts were increased in mice treated with a liver X receptor agonist or reconstituted HDL, as compared with controls. In humans, tracer disappeared from plasma rapidly after injection of nanoparticles, followed by reappearance in HDL and nonHDL fractions. Counts present as free cholesterol increased rapidly and linearly in the first 240 min after nadir; counts in cholesteryl ester increased steadily over time. Estimates of fractional transfer rates of key RCT steps were obtained. These results support the use of 3H-cholesterol nanoparticles as a feasible approach for the measurement of macrophage RCT in vivo in humans.
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Affiliation(s)
- Marina Cuchel
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA.
| | - Anna C Raper
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Donna M Conlon
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Daniel A Pryma
- Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | | | - Rahul Poria
- Department of Radiology, University of Pennsylvania, Philadelphia, PA
| | - Debra Cromley
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Xiaoyu Li
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Richard L Dunbar
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Benjamin French
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA
| | - Liming Qu
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - William Farver
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | | | - Sissel Lund-Katz
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Amanda Baer
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | | | | | | | - Lan Xiao
- Bristol-Myers Squibb R&D, Princeton, NJ
| | | | - John S Millar
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Jeffrey T Billheimer
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Daniel J Rader
- Division of Translational Medicine and Human Genetics, Department of Medicine, University of Pennsylvania, Philadelphia, PA
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Thacker SG, Rousset X, Esmail S, Zarzour A, Jin X, Collins HL, Sampson M, Stonik J, Demosky S, Malide DA, Freeman L, Vaisman BL, Kruth HS, Adelman SJ, Remaley AT. Increased plasma cholesterol esterification by LCAT reduces diet-induced atherosclerosis in SR-BI knockout mice. J Lipid Res 2015; 56:1282-95. [PMID: 25964513 PMCID: PMC4479333 DOI: 10.1194/jlr.m048629] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 04/27/2015] [Indexed: 12/15/2022] Open
Abstract
LCAT, a plasma enzyme that esterifies cholesterol, has been proposed to play an antiatherogenic role, but animal and epidemiologic studies have yielded conflicting results. To gain insight into LCAT and the role of free cholesterol (FC) in atherosclerosis, we examined the effect of LCAT over- and underexpression in diet-induced atherosclerosis in scavenger receptor class B member I-deficient [Scarab(-/-)] mice, which have a secondary defect in cholesterol esterification. Scarab(-/-)×LCAT-null [Lcat(-/-)] mice had a decrease in HDL-cholesterol and a high plasma ratio of FC/total cholesterol (TC) (0.88 ± 0.033) and a marked increase in VLDL-cholesterol (VLDL-C) on a high-fat diet. Scarab(-/-)×LCAT-transgenic (Tg) mice had lower levels of VLDL-C and a normal plasma FC/TC ratio (0.28 ± 0.005). Plasma from Scarab(-/-)×LCAT-Tg mice also showed an increase in cholesterol esterification during in vitro cholesterol efflux, but increased esterification did not appear to affect the overall rate of cholesterol efflux or hepatic uptake of cholesterol. Scarab(-/-)×LCAT-Tg mice also displayed a 51% decrease in aortic sinus atherosclerosis compared with Scarab(-/-) mice (P < 0.05). In summary, we demonstrate that increased cholesterol esterification by LCAT is atheroprotective, most likely through its ability to increase HDL levels and decrease pro-atherogenic apoB-containing lipoprotein particles.
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Affiliation(s)
- Seth G. Thacker
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Xavier Rousset
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Safiya Esmail
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Abdalrahman Zarzour
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Xueting Jin
- Experimental Atherosclerosis Section, Center for Molecular, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | | | - Maureen Sampson
- Department of Laboratory Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892
| | - John Stonik
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Stephen Demosky
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Daniela A. Malide
- Light Microscopy Core, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Lita Freeman
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Boris L. Vaisman
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Howard S. Kruth
- Experimental Atherosclerosis Section, Center for Molecular, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | | | - Alan T. Remaley
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
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Estronca LMBB, Filipe HAL, Salvador A, Moreno MJ, Vaz WLC. Homeostasis of free cholesterol in the blood: a preliminary evaluation and modeling of its passive transport. J Lipid Res 2014; 55:1033-43. [PMID: 24711632 DOI: 10.1194/jlr.m043067] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Indexed: 01/23/2023] Open
Abstract
The rate of noncatalyzed transfer of cholesterol (Chol) among lipoproteins and cells in the blood is of fundamental importance as a baseline to assess the role of active transport mechanisms, but remains unknown. Here we address this gap by characterizing the associa-tion of the Chol analog, ergosta-5,7,9(11),22-tetraen-3β-ol (DHE), with the lipoproteins VLDL, LDL, HDL2, and HDL3 Combining these results with data for the association of DHE with liposomes, we elaborated a kinetic model for the noncatalyzed exchange of free Chol among blood compartments. The computational results are in good agreement with experimental values. The small deviations are explained by the nonequilibrium distribution of unesterified Chol in vivo, due to esterification and entry of new unesterified Chol, and eventual effects introduced by incubations at low temperatures. The kinetic profile of the homeostasis of unesterified Chol in the blood predicted by the model developed in this work is in good agreement with the observations in vivo, highlighting the importance of passive processes.
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Affiliation(s)
- Luís M B B Estronca
- Departamento de Química, Universidade de Coimbra, Coimbra, Portugal CNC - Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Coimbra, Portugal
| | - Hugo A L Filipe
- Departamento de Química, Universidade de Coimbra, Coimbra, Portugal Centro de Química de Coimbra, Universidade de Coimbra, Coimbra, Portugal
| | - Armindo Salvador
- Departamento de Química, Universidade de Coimbra, Coimbra, Portugal CNC - Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Coimbra, Portugal
| | - Maria João Moreno
- Departamento de Química, Universidade de Coimbra, Coimbra, Portugal Centro de Química de Coimbra, Universidade de Coimbra, Coimbra, Portugal
| | - Winchil L C Vaz
- Departamento de Química, Universidade de Coimbra, Coimbra, Portugal Centro de Química de Coimbra, Universidade de Coimbra, Coimbra, Portugal
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Abstract
PURPOSE OF REVIEW Reverse cholesterol transport (RCT) is considered a significant component of the atheroprotective effects of HDL. Methods for quantifying flux through the RCT pathway have not been available until recently. There is a need to improve our understanding of HDL function, including the role of RCT in general and individual steps of RCT in particular, on atherosclerosis. This review highlights new information about cholesterol flux through the RCT pathway. RECENT FINDINGS Recent clinical studies have demonstrated several important quantitative features of cholesterol fluxes in vivo, providing insight into variability and control of specific components of the RCT pathway. The findings illustrate the independent nature of individual steps in the RCT pathway and their apparently weak relationship to plasma HDL cholesterol levels. Nonclinical studies provide some mechanistic data re-enforcing the importance of apoB particles in RCT and role roles for serum albumin and erythrocytes in free cholesterol flux. These findings suggest that the HDL-centric view of RCT may need revision. SUMMARY The constellation of known lipoproteins and other players involved in this pathway continues to increase. Further research, particularly in humans, is needed in order to understand which parts of the RCT pathway are most relevant to the pathophysiology and treatment of atherosclerosis.
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Affiliation(s)
- Marc Hellerstein
- aKineMed, Inc., Emeryville bDepartment of Nutritional Sciences and Toxicology, University of California, Berkeley cDepartment of Medicine, Division of Endocrinology and Metabolism, University of California, San Francisco, California, USA
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Davidson MH, Voogt J, Luchoomun J, Decaris J, Killion S, Boban D, Glass A, Mohammad H, Lu Y, Villegas D, Neese R, Hellerstein M, Neff D, Musliner T, Tomassini JE, Turner S. Inhibition of intestinal cholesterol absorption with ezetimibe increases components of reverse cholesterol transport in humans. Atherosclerosis 2013; 230:322-9. [DOI: 10.1016/j.atherosclerosis.2013.08.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 08/03/2013] [Accepted: 08/05/2013] [Indexed: 01/19/2023]
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Toth PP, Barter PJ, Rosenson RS, Boden WE, Chapman MJ, Cuchel M, D'Agostino RB, Davidson MH, Davidson WS, Heinecke JW, Karas RH, Kontush A, Krauss RM, Miller M, Rader DJ. High-density lipoproteins: A consensus statement from the National Lipid Association. J Clin Lipidol 2013; 7:484-525. [DOI: 10.1016/j.jacl.2013.08.001] [Citation(s) in RCA: 240] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 08/03/2013] [Indexed: 12/21/2022]
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Holleboom AG, Jakulj L, Franssen R, Decaris J, Vergeer M, Koetsveld J, Luchoomun J, Glass A, Hellerstein MK, Kastelein JJP, Hovingh GK, Kuivenhoven JA, Groen AK, Turner SM, Stroes ESG. In vivo tissue cholesterol efflux is reduced in carriers of a mutation in APOA1. J Lipid Res 2013; 54:1964-71. [PMID: 23650622 DOI: 10.1194/jlr.p028449] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Atheroprotection by high density lipoprotein (HDL) is considered to be mediated through reverse cholesterol transport (RCT) from peripheral tissues. We investigated in vivo cholesterol fluxes through the RCT pathway in patients with low plasma high density lipoprotein cholesterol (HDL-c) due to mutations in APOA1. Seven carriers of the L202P mutation in APOA1 (mean HDL-c: 20 ± 19 mg/dl) and seven unaffected controls (mean HDL-c: 54 ± 11 mg/dl, P < 0.0001) received a 20 h infusion of (13)C2-cholesterol ((13)C-C). Enrichment of plasma and erythrocyte free cholesterol and plasma cholesterol esters was measured. With a three-compartment SAAM-II model, tissue cholesterol efflux (TCE) was calculated. TCE was reduced by 19% in carriers (4.6 ± 0.8 mg/kg/h versus 5.7 ± 0.7 mg/kg/h in controls, P = 0.02). Fecal (13)C recovery and sterol excretion 7 days postinfusion did not differ significantly between carriers and controls: 21.3 ± 20% versus 13.3 ± 6.3% (P = 0.33), and 2,015 ± 1,431 mg/day versus 1456 ± 404 mg/day (P = 0.43), respectively. TCE is reduced in carriers of mutations in APOA1, suggesting that HDL contributes to efflux of tissue cholesterol in humans. The residual TCE and unaffected fecal sterol excretion in our severely affected carriers suggest, however, that non-HDL pathways contribute to RCT significantly.
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Affiliation(s)
- Adriaan G Holleboom
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
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Briand F, Thieblemont Q, Muzotte E, Sulpice T. Upregulating Reverse Cholesterol Transport With Cholesteryl Ester Transfer Protein Inhibition Requires Combination With the LDL-Lowering Drug Berberine in Dyslipidemic Hamsters. Arterioscler Thromb Vasc Biol 2013; 33:13-23. [DOI: 10.1161/atvbaha.112.252932] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Objective—
This study aimed to investigate whether cholesteryl ester transfer protein inhibition promotes in vivo reverse cholesterol transport in dyslipidemic hamsters.
Methods and Results—
In vivo reverse cholesterol transport was measured after an intravenous injection of
3
H-cholesteryl-oleate–labeled/oxidized low density lipoprotein particles (
3
H-oxLDL), which are rapidly cleared from plasma by liver-resident macrophages for further
3
H-tracer egress in plasma, high density lipoprotein (HDL), liver, and feces. A first set of hamsters made dyslipidemic with a high-fat and high-fructose diet was treated with vehicle or torcetrapib 30 mg/kg (TOR) over 2 weeks. Compared with vehicle, TOR increased apolipoprotein E–rich HDL levels and significantly increased
3
H-tracer appearance in HDL by 30% over 72 hours after
3
H-oxLDL injection. However, TOR did not change
3
H-tracer recovery in liver and feces, suggesting that uptake and excretion of cholesterol deriving from apolipoprotein E-rich HDL is not stimulated. As apoE is a potent ligand for the LDL receptor, we next evaluated the effects of TOR in combination with the LDL-lowering drug berberine, which upregulates LDL receptor expression in dyslipidemic hamsters. Compared with TOR alone, treatment with TOR+berberine 150 mg/kg resulted in lower apolipoprotein E–rich HDL levels. After
3
H-oxLDL injection, TOR+berberine significantly increased
3
H-tracer appearance in fecal cholesterol by 109%.
Conclusion—
Our data suggest that cholesteryl ester transfer protein inhibition alone does not stimulate reverse cholesterol transport in dyslipidemic hamsters and that additional effects mediated by the LDL-lowering drug berberine are required to upregulate this process.
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Turner S, Voogt J, Davidson M, Glass A, Killion S, Decaris J, Mohammed H, Minehira K, Boban D, Murphy E, Luchoomun J, Awada M, Neese R, Hellerstein M. Measurement of reverse cholesterol transport pathways in humans: in vivo rates of free cholesterol efflux, esterification, and excretion. J Am Heart Assoc 2012; 1:e001826. [PMID: 23130164 PMCID: PMC3487360 DOI: 10.1161/jaha.112.001826] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 06/19/2012] [Indexed: 12/18/2022]
Abstract
BACKGROUND Reverse cholesterol transport from peripheral tissues is considered the principal atheroprotective mechanism of high-density lipoprotein, but quantifying reverse cholesterol transport in humans in vivo remains a challenge. We describe here a method for measuring flux of cholesterol though 3 primary components of the reverse cholesterol transport pathway in vivo in humans: tissue free cholesterol (FC) efflux, esterification of FC in plasma, and fecal sterol excretion of plasma-derived FC. METHODS AND RESULTS A constant infusion of [2,3-(13)C(2)]-cholesterol was administered to healthy volunteers. Three-compartment SAAM II (Simulation, Analysis, and Modeling software; SAAM Institute, University of Washington, WA) fits were applied to plasma FC, red blood cell FC, and plasma cholesterol ester (13)C-enrichment profiles. Fecal sterol excretion of plasma-derived FC was quantified from fractional recovery of intravenous [2,3-(13)C(2)]-cholesterol in feces over 7 days. We examined the key assumptions of the method and evaluated the optimal clinical protocol and approach to data analysis and modeling. A total of 17 subjects from 2 study sites (n=12 from first site, age 21 to 75 years, 2 women; n=5 from second site, age 18 to 70 years, 2 women) were studied. Tissue FC efflux was 3.79±0.88 mg/kg per hour (mean ± standard deviation), or ≍8 g/d. Red blood cell-derived flux into plasma FC was 3.38±1.10 mg/kg per hour. Esterification of plasma FC was ≍28% of tissue FC efflux (1.10±0.38 mg/kg per hour). Recoveries were 7% and 12% of administered [2,3-(13)C(2)]-cholesterol in fecal bile acids and neutral sterols, respectively. CONCLUSIONS Three components of systemic reverse cholesterol transport can be quantified, allowing dissection of this important function of high-density lipoprotein in vivo. Effects of lipoproteins, genetic mutations, lifestyle changes, and drugs on these components can be assessed in humans. (J Am Heart Assoc. 2012;1:e001826 doi: 10.1161/JAHA.112.001826.).
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Affiliation(s)
- Scott Turner
- KineMed, Inc, Emeryville, CA (S.T., J.V., A.G., S.K., J.D., H.M., E.M., J.L., M.A.)
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Lindegaard ML, Wassif CA, Vaisman B, Amar M, Wasmuth EV, Shamburek R, Nielsen LB, Remaley AT, Porter FD. Characterization of placental cholesterol transport: ABCA1 is a potential target for in utero therapy of Smith-Lemli-Opitz syndrome. Hum Mol Genet 2008; 17:3806-13. [PMID: 18775956 DOI: 10.1093/hmg/ddn278] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Patients with Smith-Lemli-Opitz syndrome (SLOS) are born with multiple congenital abnormalities. Postnatal cholesterol supplementation is provided; however, it cannot correct developmental malformations due to in utero cholesterol deficit. Increased transport of cholesterol from maternal to fetal circulation might attenuate congenital malformations. The cholesterol transporters Abca1, Abcg1, and Sr-b1 are present in placenta; however, their potential role in placental transport remains undetermined. In mice, expression analyses showed that Abca1 and Abcg1 transcripts increased 2-3-fold between embryonic days 13.5 and 18.5 in placental tissue; whereas, Sr-b1 expression decreased. To examine the functional role of Abca1, Abcg1 and Sr-b1 we measured the maternal-fetal transfer of (14)C-cholesterol in corresponding mutant embryos. Disruption of either Abca1 or Sr-b1 decreased cholesterol transfer by approximately 30%. In contrast, disruption of the Abcg1 had no effect. Treatment of pregnant C57Bl/6 female mice with TO901317, an LXR-agonist, increased both Abca1 expression and maternal-fetal cholesterol transfer to the fetus. In an SLOS mouse model (Dhcr7(-/-)), which is incapable of de novo synthesis of cholesterol, in utero treatment with TO901317 resulted in increased cholesterol content in Dhcr7(-/-) embryos. Our data support the hypothesis that Abca1, and possibly Sr-b1, contributes to transport maternal cholesterol to the developing fetus. Furthermore, we show, as a proof of principle, that modulating maternal-fetal cholesterol transport has potential for in utero therapy of SLOS.
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Affiliation(s)
- Marie L Lindegaard
- Section on Molecular Dysmorphology, Eunice Kennedy Schriver National Institute of Child Health and Human Development, National Heart, Lung and Blood Institute, NIH, DHHS, Bethesda, MD, USA.
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17
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Salvador AM, Alonso-Damián A, Choubert G, Milicua JCG. Effect of soybean phospholipids on canthaxanthin lipoproteins transport, digestibility, and deposition in rainbow trout (Oncorhynchus mykiss) muscle. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2007; 55:9202-7. [PMID: 17850089 DOI: 10.1021/jf070145q] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
This study was designed to assess the effect of dietary soybean phospholipids on canthaxanthin transport by serum lipoproteins and canthaxanthin muscle deposition in trout. Three groups of 12 immature trout in triplicate with a mean body weight of 130 g were fed with three experimental diets containing (1) canthaxanthin plus lecithin plus fish oil, (2) canthaxanthin plus lecithin, and (3) canthaxanthin alone, for 12 days. The two major lipoprotein classes in rainbow trout are high-density lipoproteins, which transport principally carotenoids present in the serum, and low-density lipoproteins, which are responsible for the transport of cholesterol, both independently of the administered diet. In addition, very low density lipoproteins are responsible for triglyceride transport in serum. Nevertheless, the amount of canthaxanthin in the serum increased when carotenoid was associated with phospholipids plus fish oil. When canthaxanthin is transported by lecithin plus fish oil, the amount of phospholipids, cantaxanthin, and cholesterol deposited in muscle increased but not significantly. The highest apparent canthaxanthin digestibility coefficient was obtained when canthaxanthin was carried by lecithin plus fish oil. The administration of canthaxanthin carried by phospholipids improved its accumulation in the muscle of rainbow trout. This accumulation could be enhanced if the time of administration of canthaxanthin is increased.
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Affiliation(s)
- Ana M Salvador
- Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, P.O. Box 644, 48080 Bilbao, Spain
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Kee P, Caiazza D, Rye KA, Barrett PHR, Morehouse LA, Barter PJ. Effect of inhibiting cholesteryl ester transfer protein on the kinetics of high-density lipoprotein cholesteryl ester transport in plasma: in vivo studies in rabbits. Arterioscler Thromb Vasc Biol 2005; 26:884-90. [PMID: 16373610 DOI: 10.1161/01.atv.0000201064.89581.35] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Inhibitors of cholesteryl ester transfer protein (CETP) have been developed as potential anti-atherogenic agents. Theoretically, however, they may be pro-atherogenic by blocking one of the pathways for removing high-density lipoprotein (HDL) cholesteryl esters (CE) from plasma in the final step of reverse cholesterol transport. Here we describe how CETP inhibition in rabbits impacts on the kinetics of HDL CE transport in plasma. METHODS AND RESULTS Administration of a CETP inhibitor reduced CETP activity by 80% to 90% and doubled the HDL cholesteryl ester concentration. Multi-compartmental analysis was used to determine HDL CE kinetics in CETP-inhibited and control rabbits after injection of tracer amounts of both native and reconstituted HDL labeled with 3H in the CE moiety. In control rabbits, HDL CE was removed from plasma by both a direct pathway and an indirect pathway after transfer of HDL CE to the very-low-density lipoprotein/low-density lipoprotein fraction. In CETP-inhibited rabbits there was an almost complete block in removal via the indirect pathway. This did not compromise the overall removal of HDL CE from plasma, which was not different in control and inhibited animals. CONCLUSIONS Inhibiting CETP in rabbits does not compromise the removal of HDL CE from plasma.
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Affiliation(s)
- P Kee
- Royal Adelaide Hospital, Adelaide, Australia
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Santos RD, Chacra APM, Morikawa A, Vinagre CC, Maranhão RC. Plasma kinetics of free and esterified cholesterol in familial hypercholesterolemia: Effects of simvastatin. Lipids 2005; 40:737-43. [PMID: 16196425 DOI: 10.1007/s11745-005-1437-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The objective of this study was to evaluate the kinetics of both free and esterified forms of cholesterol contained in a emulsion that binds to LDL receptors (LDE) in subjects with heterozygous familial hypercholesterolemia (FH), and the same subjects under the effects of high-dose simvastatin treatment, as compared with a control normolipidemic group (NL). Twenty-one FH patients (44.0 +/- 13.0 yr, 12 females, LDL cholesterol levels 6.93 +/- 1.60 mmol/L) and 22 normolipidemic patients (44.0 +/- 15.0, 10 females, LDL cholesterol levels 3.15 +/- 0.62 mmol/L) were injected intravenously with 14C-cholesteryl ester and 3H-cholesterol. FH patients were also evaluated after 2 mon of 40 or 80 mg/d simvastatin treatment, and plasma samples were collected over 24 h to determine the residence time (RT, in h) of both LDE labels, expressed as the median (25%; 75%). The RT of both 14C-cholesteryl ester and 3H-cholesterol were greater in FH than in NL [FH: 36.0 (20.5; 1191.0), NL: 17.0 (12.0-62.5), P = 0.015; and FH: 52.0 (30.0; 1515.0); NL 20.5 (14.0-30.0) P < 0.0001]. Treatment reduced LDL cholesterol by 36% (P < 0.0001), RT of 14C-cholesteryl ester by 49% (P = 0.0029 vs. baseline), and 3H-cholesterol RT by 44% (P = 0.019 vs. baseline). After treatment, the RT values of 14C-cholesteryl ester in the FH group approached the NL values (P = 0.58), but the RT of 3H-cholesterol was still greater than those for the NL group (P = 0.01). The removal of LDE cholesteryl esters and free cholesterol was delayed in FH patients. Treatment with a high dose of simvastatin normalized the removal of cholesterol esters but not the removal of free cholesterol.
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Affiliation(s)
- Raul D Santos
- Lipid Metabolism Laboratory and Lipid Clinic, The Heart Institute (InCor), University of São Paulo, Medical School Hospital (InCor-HCFMUSP), Brazil
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20
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Demmers TA, Jones PJH, Wang Y, Krug S, Creutzinger V, Heubi JE. Effects of early cholesterol intake on cholesterol biosynthesis and plasma lipids among infants until 18 months of age. Pediatrics 2005; 115:1594-601. [PMID: 15930221 DOI: 10.1542/peds.2004-0997] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The endogenous cholesterol fractional synthesis rate (FSR) is related inversely to infant dietary cholesterol at 4 months of age; however, it remains to be established whether this effect is permanent, possibly contributing to later hypercholesterolemia. OBJECTIVE To determine whether levels of dietary cholesterol in infancy induced changes in FSR and plasma lipid levels that persisted at 18 months. METHODS A prospective clinical trial was conducted with 47 infants, from their first week of life until 18 months of age, who received human milk (HM) until weaned (n = 15) or were randomized to receive modified cow's milk formula (MCF) with added cholesterol (n = 15) or cow's milk formula (CF) (n = 17) for 12 months. Cholesterol contents of HM, MCF, and CF were 120, 80, and 40 mg/L, respectively. FSR and plasma lipid levels were measured at 4 and 18 months. RESULTS At 4 months, total cholesterol and low-density lipoprotein cholesterol levels were higher for infants fed HM and MCF, compared with CF. High-density lipoprotein cholesterol levels were higher in the MCF group than in the HM and CF groups. FSR in the HM group (0.034 +/- 0.005 pools per day) was lower than that in the CF group (0.052 +/- 0.005 pools per day). There was no difference between the HM and MCF (0.047 +/- 0.005 pools per day) groups or between the MCF and CF groups. At 18 months, there were no differences in FSRs or plasma lipid profiles between the groups. CONCLUSION Although cholesterol intake before weaning affects FSRs and plasma lipid profiles at 4 months, these differences do not persist after weaning to an unrestricted diet at 18 months. This provides additional evidence that there is no imprinting of FSR in infancy with differing dietary levels of cholesterol.
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Affiliation(s)
- Théa A Demmers
- School of Dietetics and Human Nutrition, McGill University, 21111 Lakeshore Rd, Montreal, QC, H9X 3V9, Canada
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Rader DJ. Inhibition of cholesteryl ester transfer protein activity: a new therapeutic approach to raising high-density lipoprotein. Curr Atheroscler Rep 2005; 6:398-405. [PMID: 15296707 DOI: 10.1007/s11883-004-0052-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
High-density lipoprotein (HDL) cholesterol levels are inversely associated with risk of atherosclerotic cardiovascular disease (ASCVD), leading to the concept that pharmacologic therapy to raise HDL cholesterol levels may reduce ASCVD risk. There is substantial interest in the concept of inhibition of the cholesteryl ester transfer protein (CETP) as a novel strategy for raising HDL cholesterol levels, as well as reducing levels of atherogenic lipoproteins. This article reviews the physiology of CETP in lipoprotein metabolism and the data in animals and humans that are relevant to the question of whether CETP inhibition may some day be part of the clinical armamentarium for treating dyslipidemia and atherosclerotic vascular disease.
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Affiliation(s)
- Daniel J Rader
- Center for Experimental Therapeutics and Department of Medicine, University of Pennsylvania School of Medicine, 654 BRB II/III, 421 Curie Boulevard, Philadelphia, PA 19104, USA.
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Schwartz CC, VandenBroek JM, Cooper PS. Lipoprotein cholesteryl ester production, transfer, and output in vivo in humans. J Lipid Res 2004; 45:1594-607. [PMID: 15145983 DOI: 10.1194/jlr.m300511-jlr200] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Our aim was to identify and quantify the major in vivo pathways of lipoprotein cholesteryl ester transport in humans. Normal (n = 7), bile fistula (n = 5), and familial hypercholesterolemia (FH; n = 1) subjects were studied. Each received isotopic free cholesterol in HDL, LDL, or particulate form, along with another isotope of free or esterified cholesterol or mevalonic acid. VLDL, intermediate density lipoprotein (IDL), LDL, HDL, blood cells, and bile were collected for up to 6 days for analysis of radioactivity and mass of free and esterified cholesterol. These raw data were subjected to compartmental analysis using the SAAM program. Results in all groups corroborated net transport of free cholesterol to the liver from HDL, shown previously in fistula subjects. New findings revealed that 70% of ester was produced from free cholesterol in HDL and 30% from free cholesterol in LDL, IDL, and VLDL. No evidence was found for tissue-produced ester in plasma. There was net transfer of cholesteryl ester to VLDL and IDL from HDL and considerable exchange between LDL and HDL. Irreversible ester output was from VLDL, IDL, and LDL, but very little was from HDL, suggesting that selective and holoparticle uptakes of HDL ester are minor pathways in humans. It follows that 1) they contribute little to reverse transport, 2) very high HDL would not result from defects thereof, and 3) the clinical benefit of high HDL is likely explained by other mechanisms. Reverse transport in the subjects with bile fistula and FH was facilitated by ester output to the liver from VLDL plus IDL.
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Affiliation(s)
- Charles C Schwartz
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA.
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Leitzmann MF, Tsai CJ, Stampfer MJ, Rimm EB, Colditz GA, Willett WC, Giovannucci EL. Alcohol consumption in relation to risk of cholecystectomy in women. Am J Clin Nutr 2003; 78:339-47. [PMID: 12885719 DOI: 10.1093/ajcn/78.2.339] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Alcohol consumption has been linked to a lower risk of gallstone disease. However, the magnitude of the association is uncertain, and little is known about the relation of alcohol consumption patterns and individual types of alcoholic beverages to gallstone disease risk. OBJECTIVE We prospectively examined the association between alcohol intake and cholecystectomy, a surrogate for symptomatic gallstone disease, in a large cohort of women. DESIGN Women from the Nurses' Health Study who had no history of gallstone disease in 1980 (n = 80,898) were followed for 20 y. Alcohol consumption, which was measured every 2-4 y by food-frequency questionnaires, was used to predict subsequent cholecystectomy through multivariate analysis. RESULTS We ascertained 7831 cases of cholecystectomy. Relative to subjects who had no alcohol intake, subjects who had alcohol intakes of 0.1-4.9, 5.0-14.9, 15.0-29.9, 30.0-49.9, and >/=50.0 g/d had multivariate relative risks of cholecystectomy of 0.95, 0.86, 0.80, 0.67, and 0.62 (95% CI: 0.49, 0.79), respectively. Relative to subjects who never consumed alcohol, subjects who consumed alcohol 1-2, 3-4, 5-6, and 7 d/wk had multivariate relative risks of cholecystectomy of 0.94, 0.88, 0.87, and 0.73 (0.63, 0.84), respectively. All alcoholic beverage types were inversely associated with cholecystectomy risk, independent of consumption patterns (for quantity of alcohol consumed, P = 0.04, 0.001, and 0.003 for wine, beer, and liquor, respectively; for frequency of alcohol consumption, P = 0.01, 0.07, and <0.0001 for wine, beer, and liquor, respectively). CONCLUSIONS The intake of all alcoholic beverage types is inversely associated with the risk of cholecystectomy. Recommendations regarding the benefit of consuming moderate quantities of alcohol should be weighed against the potential health hazards.
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Schwartz CC, VandenBroek JM, Cooper PS. Modeling Cholesterol in Humans: Update and Dealing with the Problem of Exchange in Vivo Using the Blood Cell-Lipoprotein Paradigm. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 537:207-19. [PMID: 14995038 DOI: 10.1007/978-1-4419-9019-8_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Affiliation(s)
- Charles C Schwartz
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond, VA 23298, USA.
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25
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Affiliation(s)
- Lucian Saucan
- From the Carl T. Hayden VA Medical Center, Phoenix, Ariz
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26
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Beaumier-Gallon G, Dubois C, Senft M, Vergnes MF, Pauli AM, Portugal H, Lairon D. Dietary cholesterol is secreted in intestinally derived chylomicrons during several subsequent postprandial phases in healthy humans. Am J Clin Nutr 2001; 73:870-7. [PMID: 11333839 DOI: 10.1093/ajcn/73.5.870] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The process of intestinal absorption and chylomicron resecretion of dietary cholesterol in humans is poorly understood. OBJECTIVE The present study aimed to test the hypothesis that dietary cholesterol ingested during a given meal is resecreted into chylomicrons (and plasma) during several subsequent postprandial periods. DESIGN Seven healthy subjects ingested 3 comparable mixed test meals (at 0, 8, and 24 h) containing a given amount of fat (49 g) and cholesterol (157 mg); blood samples were taken 3 and 6 h after each test meal and 48 and 72 h after the beginning of the experiment. Heptadeuterated dietary cholesterol was present in the first test meal only, enabling its specific determination with use of gas chromatography-mass spectrometry. Chylomicrons, LDL, and HDL were isolated and lipids were quantified. RESULTS In apolipoprotein B-48-containing chylomicrons, deuterated cholesterol concentrations were moderate after the first meal (1.3 x 10(-4) mmol/L), reached a maximum after the second meal (2.4 x 10(-4) mmol/L), and were still elevated after the third meal (1.7 x 10(-4) mmol/L). In plasma, LDL and HDL cholesterol enrichment in deuterated cholesterol was lower than in chylomicrons and plateaued after 24--48 h. Estimates of newly secreted exogenous deuterated cholesterol in chylomicrons indicate that 30.7%, 55.2%, and 14.1% of the total was secreted after the first, second, and third meals, respectively. CONCLUSION Ingested dietary cholesterol is secreted by the small intestine in chylomicrons into the circulation during > or =3 subsequent postprandial periods in healthy humans. This likely results from a complex multistep intestinal processing of cholesterol with dietary fat as a driving force.
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Matthan NR, Raeini-Sarjaz M, Lichtenstein AH, Ausman LM, Jones PJ. Deuterium uptake and plasma cholesterol precursor levels correspond as methods for measurement of endogenous cholesterol synthesis in hypercholesterolemic women. Lipids 2000; 35:1037-44. [PMID: 11026626 DOI: 10.1007/s11745-000-0616-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
To assess the validity of two techniques used to measure human cholesterol synthesis, the rate of uptake of deuterium (D) into plasma free cholesterol (FC), and plasma cholesterol precursor (squalene, lanosterol, desmosterol and lathosterol) levels were compared in 14 women [65-71 yr with low density lipoprotein-cholesterol (LDL-C) > or = 3.36 mmol x L(-1)]. Subjects consumed each of six diets for 5-wk periods according to a randomized crossover design. The experimental diets included a baseline diet (39% energy as fat, 164 mg chol x 4.2 MJ(-1)) and five reduced-fat diets (30% of energy as fat), where two-thirds of the fat was either soybean oil; squeeze, tub or stick margarines; or butter. Fractional and absolute synthesis rates (FSR and ASR) of FC were determined using the deuterium incorporation (DI) method, while cholesterol precursor levels were measured using gas-liquid chromatography. Data were pooled across diets for each variable and correlation coefficients were calculated to determine if associations were present. There was good agreement among levels of the various cholesterol precursors. In addition, FSR in pools/d (p x d(-1)) and ASR in grams/d (g x d(-1)) were strongly associated with lathosterol (r= 0.72 and 0.71, P= 0.0001), desmosterol (r= 0.75 and 0.75, P = 0.0001), lanosterol (r = 0.67 and 0.67), and squalene (r = 0.69 and 0.68) when levels of the precursors were expressed as micromol x mmol(-1) C. Significant but lower correlations were observed between the D uptake and plasma cholesterol precursor levels when the latter were expressed in absolute amounts (micromol x L(-1)). The wide range of fatty acid profiles of the experimental diets did not influence the degree of association between methods. In conclusion, the DI method and levels of some cholesterol precursors correspond as methods for shortterm measurement of cholesterol synthesis.
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Affiliation(s)
- N R Matthan
- School of Dietetics and Human Nutrition, McGill University, Macdonald Campus, Ste-Anne-de-Bellevue, Quebec, Canada
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Ikemoto M, Arai H, Feng D, Tanaka K, Aoki J, Dohmae N, Takio K, Adachi H, Tsujimoto M, Inoue K. Identification of a PDZ-domain-containing protein that interacts with the scavenger receptor class B type I. Proc Natl Acad Sci U S A 2000; 97:6538-43. [PMID: 10829064 PMCID: PMC18651 DOI: 10.1073/pnas.100114397] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The scavenger receptor class B type I (SR-BI) mediates the selective uptake of cholesteryl esters from high-density lipoprotein (HDL) and cholesterol secretion into bile in the liver. In this study, we identified an SR-BI-associated protein from rat liver membrane extracts by using an affinity chromatography technique. This protein of 523 amino acids contains four PDZ domains and associates with the C terminus of SR-BI by using its N-terminal first PDZ domain. Therefore, we denoted this protein as CLAMP (C-terminal linking and modulating protein). CLAMP was located mostly in the sinusoidal membranes, whereas SR-BI was detected in both sinusoidal and canalicular membranes. After the solubilization of the liver membranes with Triton X-100, SR-BI was immunoprecipitated with anti-CLAMP monoclonal antibody, suggesting the association of these proteins in vivo. By coexpressing SR-BI with CLAMP in Chinese hamster ovary cells, we observed (i) the increase in the expression level of SR-BI, (ii) the reduction in the deacylation rate of the cholesteryl esters taken up from HDL, and (iii) the change in the intracellular distribution of fluorescent lipid 1,1'-dioctadecyl-3,3, 3',3'-tetramethylindocarbocyanine percholate taken up from HDL. Taken together, these data suggest that CLAMP, a four-PDZ-domain-containing protein, is associated with SR-BI in the liver sinusoidal plasma membranes and may modulate the intracellular transport and metabolism of cholesteryl esters taken up from HDL.
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Affiliation(s)
- M Ikemoto
- Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
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Pakula R, Konikoff FM, Moser AM, Greif F, Tietz A, Gilat T, Rubin M. The effects of short term lipid infusion on plasma and hepatic bile lipids in humans. Gut 1999; 45:453-8. [PMID: 10446118 PMCID: PMC1727653 DOI: 10.1136/gut.45.3.453] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Patients on parenteral nutrition have an increased incidence of gall bladder sludge and gallstone disease, thought to be related to bile stasis. Intravenous lipid emulsions, especially those containing medium chain triglycerides, have also been shown to have a lithogenic effect on the composition of bile in the gall bladder. AIMS To determine whether lipid infusion influences hepatic bile composition in patients with an indwelling T tube following cholecystectomy and choledochotomy. METHODS In eight patients undergoing the above surgical procedure, the time at which effects of the interrupted enterohepatic circulation were minimal was determined. Twenty two cholesterol gallstone patients with bile fistula were then randomised to receive an infusion of a lipid emulsion containing either long chain triglycerides or a mixture of long and medium chain triglycerides. RESULTS Lipid infusion resulted in a significant increase in plasma levels of triglycerides and phospholipids. Both lipid emulsions caused an increase in hepatic biliary cholesterol level and cholesterol saturation index, but this effect was more pronounced with medium chain triglycerides. The fatty acid composition of biliary phospholipids showed a significant enrichment of linoleic acid by both lipid infusions. CONCLUSIONS Infusion of triglycerides causes lithogenic changes in hepatic bile composition in humans, the lithogenic effect of infusion of medium chain triglycerides being more pronounced than that of long chain triglycerides. This effect, coupled with gall bladder stasis, may be responsible for the increased risk of biliary sludge and gallstone formation in patients on long term lipid infusion.
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Affiliation(s)
- R Pakula
- Department of Gastroenterology, Tel Aviv Medical Centre, Tel Aviv, Israel
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Leitzmann MF, Giovannucci EL, Stampfer MJ, Spiegelman D, Colditz GA, Willett WC, Rimm EB. Prospective Study of Alcohol Consumption Patterns in Relation to Symptomatic Gallstone Disease in Men. Alcohol Clin Exp Res 1999. [DOI: 10.1111/j.1530-0277.1999.tb04191.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Beaumier-Gallon G, Dubois C, Portugal H, Lairon D. Postprandial studies on dietary cholesterol in human subjects using stable isotopes and gas chromatography-mass spectrometry analysis. Atherosclerosis 1998; 141 Suppl 1:S81-5. [PMID: 9888648 DOI: 10.1016/s0021-9150(98)00223-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
We hypothesized that intestinal absorption and postprandial re-secretion of dietary cholesterol may be a particularly complex process in humans. To test this hypothesis, we used deuterium-enriched cholesterol to specifically label meal cholesterol and developed an improved method for quantitative measurement of traces of deuterated cholesterol as well as cholesterol with reference to two different internal standards by gas chromatography-mass spectrometry (GC-MS) measurement. In the first study, a group of healthy subjects ingested a single test meal containing deuterated cholesterol with a 7 h postprandial follow-up. In the second one, a group of healthy subjects ingested a first test meal containing deuterated cholesterol and a follow-up was performed during three consecutive test meals and later until 72 h. The most striking observations were that the occurrence of dietary cholesterol in chylomicrons is not concomitant to triglycerides and is very low after a single meal while most dietary cholesterol is re-secreted in chylomicrons after a second, and even a third, fat test meal. The data obtained show that the re-secretion of dietary cholesterol from the small intestine is a slow and complex process in humans.
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Affiliation(s)
- G Beaumier-Gallon
- Unit 476, Human Nutrition and Lipids at INSERM (National Institute of Health and Medical Research, Marseille, France
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32
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Amar MJ, Dugi KA, Haudenschild CC, Shamburek RD, Foger B, Chase M, Bensadoun A, Hoyt RF, Brewer HB, Santamarina-Fojo S. Hepatic lipase facilitates the selective uptake of cholesteryl esters from remnant lipoproteins in apoE-deficient mice. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)33323-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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33
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Polichetti E, Janisson A, Iovanna C, Portugal H, Mekki N, Lorec AM, Pauli AM, Luna A, Lairon D, La Droitte P, Lafont H, Chanussot F. Stimulation of the apo AI–high density lipoprotein system by dietary soyabean lecithin in humans. J Nutr Biochem 1998. [DOI: 10.1016/s0955-2863(98)00059-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Bayley TM, Alasmi M, Thorkelson T, Krug-Wispe S, Jones PJ, Bulani JL, Tsang RC. Influence of formula versus breast milk on cholesterol synthesis rates in four-month-old infants. Pediatr Res 1998; 44:60-7. [PMID: 9667372 DOI: 10.1203/00006450-199807000-00010] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We investigated whether supplementation of regular formula (RF) with cholesterol (Ch) (RF+Ch) influenced circulating Ch levels and de novo synthesis compared with their breast-fed (BF) counterparts in 4-mo-old infants. The incorporation rate of deuterium in body water into erythrocyte membrane-free Ch over 48 h was used as an index of cholesterogenesis. Plasma total-Ch and LDL-Ch concentrations were highest (p < 0.02) in BF infants, compared with infants in the RF-fed groups. Infants in the RF+Ch groups showed an intermediate response; their plasma total-Ch and LDL-Ch concentrations were not significantly different from the BF or the RF-fed groups. Plasma total/HDL-Ch and LDL/HDL-Ch ratios were higher (p < 0.05) in BF, and higher in RF+Ch-fed infants, compared with those fed RF, whereas not different between BF and RF+Ch-fed infants. At 4 mo of age, Ch FSR was 4-fold lower (p < 0.0001) in BF versus other groups, but not significantly different between RF- and RF+Ch-fed infants. Thus, despite addition of Ch to the concentration found in breast milk, FSR remained elevated compared with that of the group fed breast milk, with an intermediate response in circulating Ch levels. It is speculated that factors other than Ch intake account for the differential Ch metabolism between formula-fed and BF infants.
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Affiliation(s)
- T M Bayley
- School of Dietetics and Human Nutrition, Macdonald Campus of McGill University, Ste-Anne-de Bellevue, Quebec, Canada
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35
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Jones P, Ausman L, Croll D, Feng J, Schaefer E, Lichtenstein A. Validation of deuterium incorporation against sterol balance for measurement of human cholesterol biosynthesis. J Lipid Res 1998. [DOI: 10.1016/s0022-2275(20)33881-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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36
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Shamburek RD, Pentchev PG, Zech LA, Blanchette-Mackie J, Carstea ED, VandenBroek JM, Cooper PS, Neufeld EB, Phair RD, Brewer HB, Brady RO, Schwartz CC. Intracellular trafficking of the free cholesterol derived from LDL cholesteryl ester is defective in vivo in Niemann-Pick C disease: insights on normal metabolism of HDL and LDL gained from the NP-C mutation. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)30027-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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37
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Cholesterol 7alpha-hydroxylase influences the expression of hepatic apoA-I in two inbred mouse strains displaying different susceptibilities to atherosclerosis and in hepatoma cells. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)37426-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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38
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Mazier MJ, Jones PJ. Diet fat saturation and feeding state modulate rates of cholesterol synthesis in normolipidemic men. J Nutr 1997; 127:332-40. [PMID: 9039836 DOI: 10.1093/jn/127.2.332] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To determine whether diets differing in fats affect cholesterol synthesis in normal individuals, nine men were randomly assigned to three groups that received three diets in a crossover design for 2 wk. Diets were either monounsaturated (MONO), polyunsaturated (POLY), or saturated (SAT). Subjects then drank a dose of deuterium oxide, and unesterified cholesterol fractional synthesis rates (FSR) were calculated during consecutive fed and unfed periods. Absolute synthesis was calculated as the product of FSR and pool size, the latter obtained from a decay curve following a [4-(14)C]cholesterol injection. Serum cholesterol concentrations varied with each diet consumed (P = 0.001); the SAT diet produced the highest and the POLY diet the lowest. Triglyceride concentrations were highest when subjects consumed the SAT diet and lowest with the POLY diet (P = 0.03); values obtained with the MONO diet did not differ significantly from those seen otherwise. HDL cholesterol concentrations were lowest when the SAT diet was consumed, highest when subjects were fed the MONO diet (P = 0.05), and midway but not significantly different with the POLY diet. Cholesterol FSR were greater when subjects consumed (P = 0.001) rather than not, and FSR during 12-h periods were greater (P = 0.045) when subjects ate the POLY diet rather than the SAT diet. Absolute synthesis was also greater (P = 0.04) when subjects were fed, but did not differ with fat type (P = 0.789). Results suggest that cholesterol synthesis is greater when men are fed than when they are not fed, and reduced synthesis is not responsible for the effect of different fats on cholesterol concentrations.
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Affiliation(s)
- M J Mazier
- Division of Human Nutrition, School of Family and Nutritional Sciences, University of British Columbia, Vancouver, Canada
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Kuipers F, Oude Elferink RP, Verkade HJ, Groen AK. Mechanisms and (patho)physiological significance of biliary cholesterol secretion. Subcell Biochem 1997; 28:295-318. [PMID: 9090299 DOI: 10.1007/978-1-4615-5901-6_11] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- F Kuipers
- Groningen Institute for Drug Studies, Laboratory of Nutrition and Metabolism, Academic Hospital Groningen, The Netherlands
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Shamburek RD, Zech LA, Cooper PS, Vandenbroek JM, Schwartz CC. Disappearance of two major phosphatidylcholines from plasma is predominantly via LCAT and hepatic lipase. THE AMERICAN JOURNAL OF PHYSIOLOGY 1996; 271:E1073-82. [PMID: 8997228 DOI: 10.1152/ajpendo.1996.271.6.e1073] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Metabolism of 1-stearoyl-2-arachidonyl-phosphatidyl-choline (SAPC), a major phosphatidylcholine (PC) species in rat plasma, was compared with 1-palmitoyl-2-linoleoyl-PC (PLPC) metabolism. High-density lipoproteins containing SAPC and PLPC tracers labeled in the sn-2 fatty acid with 3H and 14C isotopes, respectively, were administered. The rats were depleted of endogenous bile acids and infused via the ileum with individual bile acids that ranged widely in hydrophobicity. The half-lives for SAPC and PLPC in plasma were 48 and 57 min, respectively. Most of the 3H activity that disappeared from plasma at 1 h was found in the liver in 1-palmitoyl-2-arachidonyl-PC, SAPC, and 1-oleoyl-2-arachidonyl-PC, indicating phospholipase A1 hydrolysis of plasma SAPC forming 2-arachidonyl-lysophosphatidylcholine, which was reacylated in the liver. Plasma PLPC also underwent phospholipase A1 hydrolysis, as reported previously. The fraction of 3H dose that accumulated in plasma cholesteryl arachidonate was two- to threefold higher than the fraction of 14C dose in cholesteryl linoleate. Multicompartmental models for SAPC and PLPC were developed that included lysophosphatidylcholines and cholesteryl esters. Bile acids did not influence plasma PC metabolism. Lecithin-cholesterol acyltransferase and phospholipase A1 (hepatic lipase) hydrolysis accounted for > or = 90% of the SAPC and PLPC that disappeared from plasma; SAPC and PLPC are comparable as substrates for hepatic lipase, but SAPC is preferred by lecithin-cholesterol acyltransferase.
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Affiliation(s)
- R D Shamburek
- Department of Medicine, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298, USA
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42
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Jones PJ, Pappu AS, Hatcher L, Li ZC, Illingworth DR, Connor WE. Dietary cholesterol feeding suppresses human cholesterol synthesis measured by deuterium incorporation and urinary mevalonic acid levels. Arterioscler Thromb Vasc Biol 1996; 16:1222-8. [PMID: 8857917 DOI: 10.1161/01.atv.16.10.1222] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The objective of this study was to measure the response of cholesterol biosynthesis in subjects to three different amounts of dietary cholesterol: 50 (low), 350 (medium), and 650 (high) mg cholesterol per 2800 kcal. Individuals with low (n = 7), normal (n = 12), and elevated (n = 11) plasma cholesterol concentrations consumed in random order solid-food test diets (15%, 55%, and 30% of energy as protein, carbohydrate, and fat, respectively) at each dietary cholesterol level. The three diets were consumed for 4 weeks each, and each dietary phase was separated by a 4-week washout period. During the final week of each diet, 0.7 g D2O was given per kilogram of body water and deuterium incorporation into the erythrocyte cholesterol pool was measured for 24 hours. Urinary mevalonate levels were also determined in samples obtained during two consecutive 24-hour periods. Both techniques provided measurements of whole-body cholesterol biosynthesis. In all subjects the cholesterol synthesis rate as measured by deuterium incorporation was significantly lower (P < .05) after the transition from low- to medium- and low- to high-cholesterol diets. Urinary mevalonate excretion decreased after the change from the medium- to high- (P < .05) and low- to high- (P < .01) cholesterol diets. Although correspondence between the two methods was poor, they both indicated some suppression of cholesterol synthesis by dietary cholesterol. The response of cholesterogenesis to different amounts of dietary cholesterol was related to the rate of synthesis under depressed conditions of the low-cholesterol diet. These findings indicate modest downregulation of synthesis in response to dietary cholesterol in humans, independent of plasma cholesterol levels.
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Affiliation(s)
- P J Jones
- School of Dietetics and Human Nutrition, McGill University, Montreal, Canada
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Polichetti E, Diaconescu N, De La Porte PL, Malli L, Portugal H, Pauli AM, Lafont H, Tuchweber B, Yousef I, Chanussot F. Cholesterol-lowering effect of soyabean lecithin in normolipidaemic rats by stimulation of biliary lipid secretion. Br J Nutr 1996; 75:471-8. [PMID: 8785219 DOI: 10.1079/bjn19960148] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The purpose of the present study was to assess the role of the liver in the plasma-cholesterol-lowering effect of soyabean lecithin. Normolipidaemic rats were fed on lecithin-enriched or control diets with the same amount of protein. The lecithin diets contained 200 g/kg high-fat commercial semi-purified soyabean lecithin (230 g/kg total lipids as soyabean phosphatidylcholine) or 200 g/kg high-fat purified soyabean lecithin (930 g/kg total lipids as soyabean phosphatidylcholine). The control diets were a lowfat diet (40 g fat/kg) and a high-fat triacylglycerol-rich diet (200 g fat/kg). The high-fat diets were isoenergetic. The cholesterol-lowering effect of the lecithin-enriched diets was associated with significantly lower levels of plasma total- and HDL-cholesterol and significantly higher levels of bile phosphatidylcholine (PC), bile salts and cholesterol. These findings suggest that the liver plays a major role in the reduction of plasma cholesterol, the increased biliary lipid being provided by both HDL and the hepatic microsomal pools of PC and cholesterol.
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Affiliation(s)
- E Polichetti
- INSERM U130 and Laboratoire Central, Hôpital Sainte Marguerite, Marseille, France
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44
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45
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Botham KM, Bravo E. The role of lipoprotein cholesterol in biliary steroid secretion. Studies with in vivo experimental models. Prog Lipid Res 1995; 34:71-97. [PMID: 7644554 DOI: 10.1016/0163-7827(94)00007-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- K M Botham
- Department of Veterinary Basic Sciences, Royal Veterinary College, London, U.K
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46
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Jones PJ, Lichtenstein AH, Schaefer EJ. Interaction of dietary fat saturation and cholesterol level on cholesterol synthesis measured using deuterium incorporation. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)40105-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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47
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Fisher WR, Zech LA, Stacpoole PW. ApoB metabolism in familial hypercholesterolemia. Inconsistencies with the LDL receptor paradigm. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1994; 14:501-10. [PMID: 8148348 DOI: 10.1161/01.atv.14.4.501] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The biology of the low-density lipoprotein (LDL) receptor has been examined in detail, and a paradigm for LDL metabolism has evolved from comparative studies of cholesterol metabolism in a variety of cells cultured from normal individuals and subjects with familial hypercholesterolemia (FH). Cultured cells from patients with homozygous FH lack a functional LDL receptor and show diminished LDL clearance, induction of the enzyme hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, increased cholesterol synthesis, decreased cholesterol ester production, and depleted cholesterol ester stores. The observed decrease in the fractional catabolic rate (FCR) of LDL is attributed to the mutated LDL receptor gene. However, in the experimental animal model of this disease, the Watanabe heritable hyperlipidemic (WHHL) rabbit, cholesterol ester stores are increased, while hepatic cholesterol synthesis is decreased. Furthermore, in humans HMG-CoA reductase is suppressed, and the LDL apolipoprotein (apo) B production rate is increased in patients with FH. These findings raise questions about the adequacy of the paradigm in understanding hepatic cholesterol metabolism in vivo. In humans, apoB metabolism is believed to be principally determined by the liver, where apoB is both synthesized and catabolized. Assuming the neutral lipid content of the liver is the major determinant of apoB metabolism, we postulated that the changes in apoB metabolism in FH are predictable when based on the assumption of an increase in hepatic cholesterol and cholesterol ester content, as observed both in the WHHL rabbit and in humans. We examined this hypothesis in vivo in patients with heterozygous FH by using tracer kinetic methodology and have used similar data from normal and hypertriglyceridemic (HTG) subjects as controls. Whereas normal and HTG subjects secrete apoB primarily as large, triglyceride-enriched very-low-density lipoprotein (VLDL), heterozygous FH patients have an absolute decrease in apoB production and secrete almost 40% of apoB as smaller intermediate-density lipoprotein (IDL)/LDL. In normal humans, about half of secreted apoB is catabolized rather than being converted to LDL. In HTG subjects two thirds of apoB follows this same route, by which VLDL remnants remaining after triglyceride hydrolysis are largely returned to the liver. In contrast, in FH subjects secreted apoB is fully converted to LDL. Thus, although total apoB secretion is reduced in FH subjects, total LDL production is greater than in either normal or HTG subjects. Under basal conditions the elevated LDL in heterozygous FH is due to both decreased LDL receptor-mediated catabolism and increased LDL production. However, the number of LDL receptors actually expressed is suppressed below the number of potentially functional receptors.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- W R Fisher
- Department of Medicine (Endocrinology and Metabolism), University of Florida, College of Medicine, Gainesville 32610
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48
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Jones PJ, Lichtenstein AH, Schaefer EJ, Namchuk GL. Effect of dietary fat selection on plasma cholesterol synthesis in older, moderately hypercholesterolemic humans. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1994; 14:542-8. [PMID: 8148352 DOI: 10.1161/01.atv.14.4.542] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To study factors controlling plasma cholesterol levels, the effect of dietary fat type on cholesterol synthesis was examined in 15 hypercholesterolemic subjects (low-density lipoprotein [LDL] cholesterol > 130 mg.dL-1) consuming over a period of 32 days (1) a baseline diet (36% kcal as fat: 15% saturated, 15% monounsaturated, and 6% polyunsaturated fat; 180 mg cholesterol.1000 kcal-1) and diets meeting National Cholesterol Education Program step 2 criteria (30% kcal as fat, < or = 7% saturated fat, 80 to 85 mg cholesterol/Mcal), where two thirds of the fat was either (2) olive, (3) corn, or (4) canola oil. Plasma total, LDL, and high-density lipoprotein (HDL) cholesterol and triglyceride levels were determined at the end of each period. Cholesterol fractional synthesis rate (FSR) was also measured as the deuterium (D) incorporation into plasma total cholesterol relative to body D2O level (1.2 g D2O.kg-1 estimated body water) over 24 hours. Absolute synthesis rates (ASRs) were determined as the product of FSR and rapid turnover cholesterol pool size. Plasma total and LDL cholesterol levels declined significantly (P < .005) on all plant-oil diets compared with the baseline diet; however, triglyceride levels were not different. FSRs were higher (P < .05) for the corn oil (0.0665 +/- 0.0097 pool.d-1) compared with baseline (0.0412 +/- 0.0060 pool.d-1) and olive oil (0.0409 +/- 0.0052 pool.d-1) but not canola oil (0.0492 +/- 0.0072 pool.d-1) diets.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P J Jones
- Division of Human Nutrition, University of British Columbia, Vancouver, Canada
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49
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Effects of lovastatin and dietary cholesterol on bile acid kinetics and bile lipid composition in healthy male subjects. J Lipid Res 1994. [DOI: 10.1016/s0022-2275(20)41201-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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