Protective modulation of carotid atherosclerosis in hyperalphalipoproteinemic individuals

[Alcohol consumption and lipid profile in participants of the Longitudinal Study of Adult Health (ELSA-BRASIL)]

Introduction

Introduction: dyslipidemias are commonly defined by low levels of HDL-c and high levels of triglycerides and LDL-c as an alteration in the functioning of lipoproteins. Several factors are related to this pathogenesis, and one of them is the consumption of alcohol, presenting divergences between the amount and the type of alcoholic drink that must be consumed to find effects of association with the lipid parameters. Objective: to investigate the relationship between alcohol consumption and the type of alcoholic beverage with HDL-c and triglycerides in participants of the Longitudinal Study of Adult Health (ELSA-Brazil). Methods: observational, cross-sectional study, developed from baseline data from the ELSA-Brazil (2008-2010). The consumption of alcoholic beverages was estimated in doses/week and categorized in tertiles (1-7, 7-14 and > 14 doses/week) and by type of alcoholic beverage (beer, wine and distillates). Lipid parameters were used as continuous data. Linear regression models were performed for each type of alcoholic beverage. The confidence level was 5%. Results: HDL-c and triglycerides increased with the increase in the number of doses/week of beer. The consumption of wine between 1-7 and 7-14 doses/week raises HDL-c. Conversely, triglycerides tend to decrease when consumption is 1-7 doses/week. Consumption of distillates > 14 doses/week increase HDL-c. Conclusion: HDL-c increased plasma levels directly with the consumption of all types of alcoholic beverages. Conversely, triglycerides decrease with wine consumption.

Flow-mediated dilation, carotid wall thickness and HDL function in subjects with hyperalphalipoproteinemia

BACKGROUND AND AIMS

The relationships between very high plasma HDLc and subclinical atherosclerosis are still a matter of debate.

METHODS AND RESULTS

Twenty subjects with primary hyperalphalipoproteinemia (HAL, with HDLc in the highest 10th percentile and absence of overt secondary causes of this condition), aged 30-65 years, were compared with 20 age and sex-matched controls. Lipid determination, lipoprotein particle distribution (Lipoprint(®)), Cholesterol Efflux Capacity (CEC), plasma adhesion molecule, analyses of CETP, SRB1 and LIPG genes and of different markers of subclinical vascular disease (ankle-brachial index, ABI; carotid intima-media thickness, cIMT; brachial-artery flow mediated dilation, FMD) were performed. Fasting HDLc levels were 40 mg/dl higher in HAL subjects while LDLc concentration was comparable to control group. CETP gene analysis in HAL subjects identified one novel rare Single Nucleotide Polymorphism (SNP, Asp131Asn), possibly damaging, while the common SNP p.Val422Ile was highly prevalent (50% vs. 27.4% in a control population). No rare mutations associated with HAL were found in SR-B1 and LIPG genes. Polyacrylamide gel electrophoresis in HAL subjects disclosed larger and more buoyant HDL particles than in controls, while LDL profile was much more similar. ABI, cIMT and arterial plaques did not differ in cases and controls and the two groups showed comparable FMD at brachial artery examination. Similarly, ABCA1 and ABCG1 HDL-mediated CEC, the most relevant for atheroprotection, did not discriminate between the groups and only ABCG1 pathway seemed somewhat related to arterial reactivity.

CONCLUSIONS

HDL dimension, function and genetics seem scarcely related to subclinical atherosclerosis and vascular reactivity in middle-aged HAL subjects.

Low prevalence of type 2 diabetes mellitus among patients with high levels of high-density lipoprotein cholesterol

BACKGROUND

Diabetes mellitus and low levels of high-density lipoprotein cholesterol (HDL-C) are among several known risk factors for coronary artery disease. Recent research has shown potential mechanistic links between these two diseases.

OBJECTIVES

The aim of our study was to characterize, by examining particular coronary artery disease risk factors, patients with extremely high and low levels of HDL-C who were referred to a prevention clinic.

METHODS

We compared the phenotypes of 113 patients with HDL-C levels greater than the 90th percentile with 212 patients with levels less than the 10th percentile by using a retrospective chart review.

RESULTS

The cohort with high HDL-C had a remarkable difference in the incidence of type 2 diabetes (1.8% vs 21.7%). The high HDL-C cohort also had a greater age (52.1 years vs 46.7 years), more light or moderate alcohol consumption (70.8% vs 49.4%), more healthy diet (30.1% vs 22.4%), more light or moderate exercise (90.8% vs 52.2%), and a lower body mass index (25.2 kg/m² vs 28.1 kg/m²).

CONCLUSIONS

Compared with the low HDL-C group--and also the general population--the high HDL-C cohort had a remarkably low prevalence of diabetes mellitus.

A reduction of CETP activity, not an increase, is associated with modestly impaired postprandial lipemia and increased HDL-cholesterol in adult asymptomatic women

Background

The relationship between CETP and postprandial hyperlipemia is still unclear. We verified the effects of varying activities of plasma CETP on postprandial lipemia and precocious atherosclerosis in asymptomatic adult women.

Methods

Twenty-eight women, selected from a healthy population sample (n = 148) were classified according to three CETP levels, all statistically different: CETP deficiency (CETPd ≤ 4.5%, n = 8), high activity (CETPi ≥ 23.8, n = 6) and controls (CTL, CETP ≥ 4.6% and ≤ 23.7%, n = 14). After a 12 h fast they underwent an oral fat tolerance test (40 g of fat/m² of body surface area) for 8 hours. TG, TG-rich-lipoproteins (TRL), cholesterol and TRL-TG measurements (AUC, AUIC, AR, RR and late peaks) and comparisons were performed on all time points. Lipases and phospholipids transfer protein (PLTP) were determined. Correlation between carotid atherosclerosis (c-IMT) and postprandial parameters was determined. CETP TaqIB and I405V and ApoE-ε3/ε2/ε4 polymorphisms were examined. To elucidate the regulation of increased lipemia in CETPd a multiple linear regression analysis was performed.

Results

In the CETPi and CTL groups, CETP activity was respectively 9 and 5.3 higher compared to the CETPd group. Concentrations of all HDL fractions and ApoA-I were higher in the CETPd group and clearance was delayed, as demonstrated by modified lipemia parameters (AUC, AUIC, RR, AR and late peaks and meal response patterns). LPL or HL deficiencies were not observed. No genetic determinants of CETP deficiency or of postprandial lipemia were found. Correlations with c-IMT in the CETPd group indicated postprandial pro-atherogenic associations. In CETPd the regression multivariate analysis (model A) showed that CETP was largely and negatively predicted by VLDL-C lipemia (R² = 92%) and much less by TG, LDL-C, ApoAI, phospholipids and non-HDL-C. CETP (model B) influenced mainly the increment in ApoB-100 containing lipoproteins (R² = 85% negatively) and phospholipids (R² = 13%), at the 6^thh point.

Conclusion

The moderate CETP deficiency phenotype included a paradoxically high HDL-C and its sub fractions (as earlier described), positive associations with c-IMT, a postprandial VLDL-C increment predicting negatively CETP activity and CETP activity regulating inversely the increment in ApoB100-containing lipoproteins. We hypothesize that the enrichment of TG content in triglyceride-rich ApoB-containing lipoproteins and in TG rich remnants increases lipoproteins' competition to active lipolysis sites,reducing their catabolism and resulting on postprandial lipemia with atherogenic consequences.