CETP and LCAT Gene Polymorphisms Are Associated with High-Density Lipoprotein Subclasses and Acute Coronary Syndrome.

We evaluated whether CETP and LCAT gene polymorphisms are statistically associated with the high-density lipoprotein (HDL) size distribution, the cholesterol level of HDL subclasses, and the acute coronary syndrome (ACS) susceptibility. Two CETP gene polymorphisms (rs4783961 and rs708272) and one LCAT polymorphism (rs2292318) were genotyped by 5' exonuclease TaqMan assays in 619 patients with ACS and 607 control individuals. For HDL analysis, a subgroup of 100 healthy individuals was recruited; the HDL subclasses were separated via ultracentrifugation and polyacrylamide gradient gel electrophoresis under native conditions. Under a dominant model, the G allele of the rs708272 polymorphism was associated with an increased risk of ACS (odds ratios [OR] = 1.45, corrected p-value [pCDom ] = 0.036). The linkage disequilibrium analysis showed that one of the eight possible combinations was associated with the risk of developing ACS (OR = 1.52, pC = 0.02), which suggests that it may contribute to coronary atherosclerosis. The rs708272 G allele carriers had a lower concentration of cholesterol associated with the HDL2a and HDL3a subclasses when compared with subjects carrying the A allele. Carriers of LCAT rs2292318 A allele showed a lower concentration of high-density lipoprotein-cholesterol (HDL-C) in comparison to the GG genotype; the cholesterol associated with the each one of the five HDL subclasses was significantly lower in rs2292318 A than in GG subjects. In summary, this study demonstrates that the rs708272 polymorphism is associated with a heightened risk of developing ACS. In addition, we report the association of the rs708272 and rs2292318 polymorphisms with HDL-C levels and HDL subclasses.

Low concentrations of phospholipids and plasma HDL cholesterol subclasses in asymptomatic subjects with high coronary calcium scores.

OBJECTIVE: To determine whether HDL size distribution and HDL subclasses are associated with coronary calcium scores. METHODS: We screened 677 apparently healthy individuals by coronary tomography. One hundred twenty subjects were then recruited for the study and grouped by coronary artery calcification scores (CAC). Forty asymptomatic patients with atherosclerosis with CAC scores ≥75th percentile for gender and age were placed in the first group. Forty patients with CAC scores ≤25th percentile and 40 matched controls (CAC = 0) made up the two remaining groups. HDL samples were separated via sequential ultracentrifugation, followed by electrophoresis: they were then enzymatically stained and densitometrically analyzed to determine the triglycerides (Tg), phospholipids (Ph), and plasma cholesterol (C) concentrations corresponding to each HDL subclass. RESULTS: HDL size distribution, lipid and non-lipid risk factors for atherosclerosis were similar among the three groups: HDL-cholesterol and HDL-phospholipids were significantly lower in the CAC ≥75th percentile group, whereas HDL-lipids in the CAC ≤25th group were comparable to the controls. HDL2b- and HDL2a-cholesterol were decreased, whereas phospholipids were lower in patients constituting 4 of the 5 HDL subclasses. The Ph-to-Tg ratios of small HDL were higher in both experimental groups compared with the controls, suggesting that these lipoproteins had abnormal structures. In spite of the significant differences between the high-CAC score subjects and the controls, statistical analyses demonstrated no substantial relationship between CAC scores and HDL parameters: other lipid and non-lipid risk factors for atherosclerosis were not statistically linked to CAC scores. Only male gender and age contributed to CAC scores in our study population. CONCLUSIONS: Our results suggest that CAC scores and traditional lipid profiles are independent aspects of atherosclerosis and that only lipids may be biomarkers of coronary calcification during the asymptomatic stages of the disease; however, HDL subclasses do not contribute to CAC scores.

Shift of high-density lipoprotein size distribution toward large particles in patients with proteinuria.

BACKGROUND: The potential atheroprotective role of the different HDL subclasses may depend on the metabolic factors that affect their plasma concentrations. The kidney is supposed to be one of the main catabolic sites for these lipoproteins. However, little is known about the impact of proteinuria on HDL size distribution and HDL structure. The aim of this study is to establish the influence of proteinuria on HDL size distribution and cholesterol plasma concentration of HDL subclasses. METHODS: Forty patients within a range of proteinuria from 0.2 to 10.0 g/g estimated by the urinary protein-to-creatinine ratio and 40 healthy controls were enrolled in the study. HDL subclasses were separated by sequential ultracentrifugation followed by a polyacrylamide gradient electrophoresis; gels were stained enzymatically for cholesterol and with Coomasie blue for proteins. HDL size distribution and plasma concentration of the five HDL subclasses were calculated by optical densitometry. RESULTS: When determined by protein, large HDL2b and HDL2a relative proportions were higher in patients than in control subjects, whereas the contrary was observed for small HDL3b and 3c. Consistently, HDL3a, 3b, and 3c were negatively correlated with proteinuria when data were adjusted by age, gender, body mass index, and blood pressure. Size distribution followed a different pattern when determined by cholesterol, suggesting an abnormal lipid composition that was further supported by a protein-to-cholesterol ratio significantly higher in most of the HDL subclasses in proteinuric patients than in the control group. Moreover, proteinuria statistically explains the HDL2b and HDL3c cholesterol plasma concentrations. CONCLUSIONS: Proteinuria is associated with a shift of HDL size distribution towards large particles and cholesterol-poor HDL subclasses. These results support the idea of a selective loss by the kidney of small HDL in patients with proteinuria; whether these abnormalities reflect an impaired reverse cholesterol transport and an increased risk of coronary heart disease remains to be elucidated.

The Srb1+1050T allele is associated with metabolic syndrome in children but not with cholesteryl ester plasma concentrations of high-density lipoprotein subclasses.

BACKGROUND: Low cholesterol and phospholipid plasma levels of some high-density lipoprotein (HDL) subclasses have been described in children with metabolic syndrome. Scavenger receptor class B type I (SR-BI) has been proposed to be at the origin of such HDL alterations because of its key role on cholesteryl esters-HDL metabolism. However, the possible contribution of SR-BI has not been specifically explored in this kind of patients. METHODS: Plasma lipid concentrations of HDL subclasses, i.e., triglycerides (TG), phosphatidylcholine (Ph), free cholesterol (FC), and total cholesterol (TC), were determined by enzymatic staining on polyacrylamide gradient gels (PAGE) in 39 pediatric patients with metabolic syndrome and 65 children as controls. Cholesteryl esters were estimated by the difference between TC and FC. Proteins of HDL subclasses were also stained for the assessment of the relative size distribution of HDL. For statistical analysis, the study population was grouped by Srb1 +1050C-->T polymorphism (rs5888) as carriers or noncarriers of the T allele, and data were corrected by metabolic syndrome status. RESULTS: The Srb1 +1050T allele was associated with metabolic syndrome [odds ratio (OR)=2.18 (1.12-4.22), P=0.02]. Plasma TG corresponding to HDL3a, as well as the relative proportion of this HDL subclass, were slightly higher in carriers of the T allele as compared to CC homozygous subjects. Cholesteryl esters plasma concentrations of all HDL subclasses were comparable between T allele carriers and noncarriers after correction by metabolic syndrome status. CONCLUSIONS: Srb1 +1050T was associated with metabolic syndrome, but T carrier subjects did not show important differences concerning HDL subclasses as compared to noncarriers.

Lipid plasma concentrations of HDL subclasses determined by enzymatic staining on polyacrylamide electrophoresis gels in children with metabolic syndrome.

BACKGROUND: The antiatherogenic role of different HDL subclasses is still controversial. HDL particles of the same size can have different lipid contents in some physiopathological situations. However, little is known about the plasma lipid levels of HDL subclasses when they are separated by their hydrodynamic diameter. METHODS: Triglycerides (Tg), phosphatidylcholine (Ph), and cholesterol (C) plasma concentrations of HDL subclasses, were determined by enzymatic staining on polyacrylamide gradient gel (PAGE) in 50 pediatric patients with metabolic syndrome (MS), and 50 control children paired by age and gender. Proteins of HDL subclasses were also stained for the assessment of the relative size distribution of HDL. RESULTS: Relative HDL size distribution was shifted to small particles in MS pediatric patients when determined per protein. In contrast, cholesterol plasma concentrations corresponding to the HDL2b, 2a, 3a, and 3b subclasses were decreased; triglycerides of HDL3b and 3c, as well as plasma phospholipids from HDL3c, were elevated in MS patients as compared to controls. The C-to-Ph ratio, considered as indicative of HDL composition, was similar among the 5 HDL subclasses in control subjects, whereas this ratio gradually decreased from large HDL2b to small HDL3c in the MS group. Cholesterol plasma concentrations of HDL subclasses correlated with the components of the MS. CONCLUSIONS: Lipids of HDL subclasses provide more and accurate information than the relative HDL size distribution determined by protein staining, and may contribute to understand better HDL metabolism and the coronary risk associated to these lipoproteins.

Enzymatic assessment of cholesterol on electrophoresis gels for estimating HDL size distribution and plasma concentrations of HDL subclasses.

The aim of this study was to develop an enzymatic cholesterol staining method to determine HDL subclasses in a polyacrylamide gradient gel electrophoresis, which further allows staining by protein in the same electrophoresis lane. HDLs from 120 healthy individuals were separated through nondenaturing PAGE. HDLs were stained for cholesterol using an enzymatic semisolid mixture. Once the gels were unstained, they were stained again for proteins with Coomassie blue. The proportions of HDL subclasses were determined by densitometry. HDL subclasses were transformed to concentrations using as reference HDL-cholesterol plasma levels. This method is comparable in linearity and reproducibility to Coomassie blue staining, although it provides quantitative data. As expected, HDL size distribution shifted toward larger particles when determined by cholesterol as compared with protein. With this method, we observed different proportions of HDL subclasses between men and women as compared with Coomassie blue staining. We described a method to determine HDL size distribution by enzymatic cholesterol staining on polyacrylamide gels. The method allows the quantification of the cholesterol plasma concentration of each HDL subclass with the possibility to further stain the protein in the same sample. The combination of HDL staining by cholesterol and protein on electrophoresis gels provides information that may have clinical relevance.