Institut Féderatif de Recherche Claude de Preval, IFR 30, Institut National de la Santé et de la Recherche Médicale, Unité 563, Centre de Physiopathologie de Toulouse-Purpan, Département Lipoprotéines et Médiateurs Lipidiques, Toulouse cedex, France.
High-density lipoprotein (HDL) cholesterol is an independent negative risk factor for coronary artery disease and thus represents today the only protective factor against atherosclerosis. The protective effect of HDL is mostly attributed to its central function in reverse cholesterol transport (RCT), a process whereby excess cell cholesterol is taken up and processed in HDL particles, and is later delivered to the liver for further metabolism and bile excretion. This process relies on specific interactions between HDL particles and cells, both peripheral (cholesterol efflux) and hepatic (cholesterol disposal) cells, and on the maturation of HDL particles within the vascular compartment. The plasma level of HDL cholesterol will thus result also from the complex interplay with cellular partners. Among them, some contribute to HDL formation - for instance ATP binding cassette AI protein - while others are mostly involved in HDL catabolism, the scavenger receptor-class B type I or the recently described membrane-bound ATP synthase/hydrolase. The last decade has seen major breakthroughs in the identification and elucidation of the role of cellular partners of HDL metabolism, and in their transcriptional regulations, opening up new perspectives in the modulation of HDL cholesterol.
"Further catabolic remodeling of HDL is mediated by several lipases including lipoprotein lipase, hepatic lipase and endothelial lipase (Guendouzi et al., 1998). This lipid remodeling involving bidirectional lipid exchange with cells and other lipoproteins is referred to as 'HDL maturation' (Martinez et al., 2004). HDL maturation generates spherical HDLs which interact with the cellular murine SR-BI to deliver CEs intracellularly to liver and steroidogenic tissues via a process called 'selective lipid uptake', yielding small, lipid-poor HDLs that are again suited for cholesterol efflux (Fig. 1) (Glass et al., 1983; Stein et al., 1983; Reaven et al., 1984, 1995; Acton et al., 1994; Acton et al., 1996; Rigotti et al., 1997a, b). "
[Show abstract][Hide abstract] ABSTRACT: High-density lipoprotein (HDL) appears to be the dominant lipoprotein particle in human follicular fluid (FF). The reported anti-atherogenic properties of HDL have been attributed in part to reverse cholesterol transport. The discoveries of the scavenger receptor class B type I (SR-BI) and the ATP-binding cassette A1 lipid (ABCA1) transporter have generated studies aimed at unraveling the pathways of HDL biogenesis, remodeling and catabolism. The production of SR-BI and ABCA1 knockout mice as well as other lipoprotein metabolism-associated mutants has resulted in reduced or absent fertility, leading us to postulate the existence of a human hepatic-ovarian HDL-associated axis of fertility. Here, we review an evolving literature on the role of HDL metabolism on mammalian fertility and oocyte development.
An extensive online search was conducted of published articles relevant to the section topics discussed. All relevant English language articles contained in Pubmed/Medline, with no specific time frame for publication, were considered for this narrative review. Cardiovascular literature was highly cited due to the wealth of relevant knowledge on HDL metabolism, and the dearth thereof in the reproductive field.
Various vertebrate models demonstrate a role for HDL in embryo development and fertility. In our clinical studies, FF levels of HDL cholesterol and apolipoprotein AI levels were negatively associated with embryo fragmentation, but not with embryo cell cleavage rate. However, the HDL component, paraoxonase 1 arylesterase activity, was positively associated with embryo cell cleavage rate.
HDL contributes to intra-follicular cholesterol homeostasis which appears to be important for successful oocyte and embryo development.
Human Reproduction Update 09/2009; 16(1):20-38. DOI:10.1093/humupd/dmp029 · 10.17 Impact Factor
"Another risk factor for developing atherosclerosis is the reduction in HDL-C level which attributed to its central function in the reverse of cholesterol transport, a process whereby excess cell cholesterol is taken up and processed by HDL particles for further delivery to the liver for metabolism . Moreover, increased TG and decreased HDL-C levels in hypercholesterolemic rats may be attributed to decreased activity of lipoprotein lipase. "
[Show abstract][Hide abstract] ABSTRACT: To investigate the effects of atorvastatin and cinnamon on serum lipid profile, oxidative stress, antioxidant capacity, hepatic enzymes activities, nitric oxide (NO) as well as homocysteine (Hcy) in hypercholesterolemic rats, 48 male albino rats, weighing 130-190 gm were divided into 2 groups, normal group fed on basal rat chow diet (n=12) and high cholesterol group (HCD) were fed on 1% cholesterol-enriched diet for 15 day (n=36). Hypercholesterolemic rats were divided into 3 subgroups (n=12 for each) fed the same diet and treated with atorvastatine (HCD+Atorvastatin) or cinnamon extract (HCD+cinnamon) or none treated (HCD) for 3&6 weeks. Serum triglycerides (TG), Total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), ALT, AST, NO, Hcy, hepatic reduced glutathione (GSH), Malondialdehyde (MDA) and antioxidant enzymes, Superoxide dismutase (SOD) and catalase activity were measured. Results showed that HCD increased significantly TG, TC, LDL-C, ALT, AST, Hcy and hepatic MDA, while lowered significantly antioxidant enzyme activities and NO levels. Atorvastatin therapy significantly increased HDL-C, NO and antioxidant activity while decreased LDL-C, MDA and Hcy concentrations. Serum TG, TC, LDL-C, ALT, AST and hepatic MDA levels were significantly lowered meanwhile, serum HDL, NO values and hepatic antioxidant activities were significantly, higher in cinnamon-treated than untreated group. These results indicate that lipid abnormalities, oxidative injury and hyperhomocystienemia were induced by HCD and this study recommend that administration of atorvastatine or cinnamon provided protection against the lipemic-oxidative disorder and act as hypocholesterolemic, hepatoprotective agent and improve cardiovascular function through modulation of oxidative stress, NO and Hcy.
International Journal of Clinical and Experimental Medicine 01/2009; 2(3):254-65. · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Oxidized low-density lipoproteins (Ox-LDL) are key elements in atherogenesis. Apolipoprotein AI (apoAI) is an active component of the antiatherogenic high-density lipoproteins (HDL). In contrast, plasma apolipoprotein B (apoB), the main component of LDL, is highly correlated with coronary risk. Our results, obtained in HepG2 cells, show that Ox-LDL, unlike native LDL, leads to opposite effects on apoB and apoAI, namely a decrease in apoAI and an increase in apoB secretion as evaluated by [(3)H]leucine incorporation and specific immunoprecipitation. Parallel pulse-chase studies show that Ox-LDL impaired apoB degradation, whereas apoAI degradation was increased and mRNA levels were decreased. We also found that enhanced lipid biosynthesis of both triglycerides and cholesterol esters was involved in the Ox-LDL-induced increase in apoB secretion. Our data suggest that the increase in apoB and decrease in apoAI secretion may in part contribute to the known atherogenicity of Ox-LDL through an elevated LDL/HDL ratio, a strong predictor of coronary risk in patients.
Free Radical Biology and Medicine 10/2006; 41(5):786-96. DOI:10.1016/j.freeradbiomed.2006.05.028 · 5.74 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.