👤 Bela Asztalos

Decreased serum high-density-lipoprotein-cholesterol (HDL-C), HDL particles, and cell-cholesterol-efflux-capacity have all been associated with increased atherosclerotic cardiovascular disease (ASCVD) risk. Our goals are to summarize recent findings with regard to these topics. Apolipoprotein (apo) A1 containing HDL particles have been characterized by two-dimensional gel electrophoresis and apoA1 immunoblotting and range from very small preβ-1 HDL, small α-4 HDL, medium α-3 HDL to large and very large α-2 and α-1 HDL. Preβ-1 HDL are most efficient in serving as acceptors of free cholesterol and phospholipid from cells via ATP binding cassette transporter A1, while α-2 and α-1 HDL are most efficient in delivering cholesteryl-ester to the liver via scavenger receptor-B1 or to triglyceride-rich lipoproteins (TRL) in exchange for triglycerides via cholesteryl ester transfer protein (CETP). Recent research on the relationships of the lipid and protein composition, function, metabolism and levels of HDL particles to ASCVD risk will be reviewed, as will advances in potential therapeutic options. HDL particles are by far the most abundant lipoproteins in plasma and contain 110 proteins involved in lipid metabolism and immune function. ApoA1, apoA2, and all lipid classes are found in all HDL particles. Low levels of large and very large α-HDL and increased levels of very small preβ-1 HDL have been associated with increased ASCVD risk. The best therapeutic options for ASCVD risk reduction in patients with low HDL-C is optimizing other risk factors including low-density-lipoprotein (LDL)-C, small-dense LDL-C, plasma-glucose, body-mass-index, blood pressure, and the promotion of smoking cessation. Show less

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to similarly lower plasma TG concentrations but differentially regulate plasma LDL-C and HDL-C concentrations. The aim of this study was to evaluate the common and differential effects of these ω-3 fatty acids on plasma lipids and lipoproteins and to assess the metabolic mechanisms of the effects. In a randomized, double-blind, crossover study, we assessed the effect of 10-week supplementation with 3 g/d pure EPA and pure DHA (both as ethyl ester, ≥97% purity) on plasma lipid and lipoprotein concentrations and activities of lipoprotein lipase (LPL), cholesteryl ester transfer protein (CETP) and lecithin:cholesterol acyl transferase (LCAT) in 21 older (>50 y) men and postmenopausal women with some characteristics of metabolic syndrome and low-grade chronic inflammation. Both EPA and DHA lowered plasma TG concentrations and increased LDL-C/apoB and HDL-C/apoA-I ratios, but only DHA increased LDL-C concentrations. The reductions in plasma TG were inversely associated with the changes in LPL activity after both EPA and DHA supplementation. EPA lowered CETP, while DHA lowered LCAT activity. EPA and DHA worked differently in men and women, with DHA increasing LPL activity and LDL-C concentrations in women, but not in men. EPA and DHA exerted similar effects on plasma TG, but differences were observed in LDL-C concentrations and activities of some enzymes involved in lipoprotein metabolism. It was also noted that EPA and DHA worked differently in men and women, supporting sex-specific variations in lipoprotein metabolism. Show less

Diabetic kidney disease (DKD) and retinopathy (DR) develop in a considerable number of subjects with Type 2 Diabetes (T2D) despite the achievement of the recommended targets for glycaemia and blood pressure. Atherogenic dyslipidemia may play a relevant role, especially in T2DM women. We report our findings on the effect of diabetic dyslipidaemia, the HDL subclasses distribution and the common cholesteryl ester transfer protein (CETP)TaqIB variant on the incidence or the progression of DKD and DR in 97 T2D women, after a ∼9years of follow-up. At baseline, T2D women presented with low HDL-C levels and higher levels of large lipid rich α-1 (16.34mg/dl), α-2 (33.39mg/dl) and pre- α1 (4.81mg/dl) HDL subparticles. The CETP TaqIB polymorphism and baseline HbA1c, triglycerides, and HDL-C levels as well as specific HDL subpopulations were associated to the occurrence of RD after ∼9years of follow-up. At stepwise regression analysis, HbA1c, triglycerides and the less atheroprotective α-3 HDL particles were the only factors independently associated to the incidence of RD. These same variables were also associated with the progression from background to proliferative RD. BMI, LDL/HDL ratio and low levels of α-1 HDL particles were associated to the occurrence of DKD at univariate analysis, although BMI was the only significant predictor at stepwise multivariate regression analysis. In T2D women, atherogenic dyslipidemia as well as subtle modifications in lipoprotein particles profile are associated with incidence and progression of microvascular disease. Show less

Our purpose was to compare HDL subpopulations, as determined by nondenaturing two-dimensional gel electrophoresis followed by immunoblotting for apolipoprotein A-I (apoA-I), apoA-II, apoA-IV, apoCs, and apoE in heterozygous, compound heterozygous, and homozygous subjects for cholesteryl ester transfer protein (CETP) deficiency and controls. Heterozygotes, compound heterozygotes, and homozygotes had CETP masses that were 30, 63, and more than 90% lower and HDL-cholesterol values that were 64, 168, and 203% higher than those in controls, respectively. Heterozygotes had approximately 50% lower pre-beta-1 and more than 2-fold higher levels of alpha-1 and pre-alpha-1 particles than controls. Three of the five heterozygotes' alpha-1 particles also contained apoA-II, which was not seen in controls. Compound heterozygotes and homozygotes had very large particles not observed in controls and heterozygotes. These particles contained apoA-I, apoA-II, apoCs, and apoE. However, these subjects did not have decreased pre-beta-1 levels. Our data indicate that CETP deficiency results in the formation of very large HDL particles containing all of the major HDL apolipoproteins except for apoA-IV. We hypothesize that the HDL subpopulation profile of heterozygous CETP-deficient patients, especially those with high levels of alpha-1 containing apoA-I but no apoA-II, represent an improved anti-atherogenic state, although this might not be the case for compound heterozygotes and homozygotes with very large, undifferentiated HDL particles. Show less