The Differential Effects of HDL Subpopulations on Lipoprotein Lipase (LPL)-Mediated VLDL Catabolism

High-density lipoprotein (HDL) subpopulations functional assessment is more relevant for HDL anti-atherogenic activity than cholesterol level. The aim of the study was to assess the impact of HDL-2 and HDL-3 on lipoprotein lipase (LPL)-mediated very-low-density lipoprotein (VLDL) catabolism related to hypertriglyceridemia development. VLDL and HDLs were isolated from serum by ultracentrifugation. VLDL was incubated with LPL in the absence and presence of total HDL or HDL subpopulations. Next, VLDL remnants were separated, and their composition and electrophoretic mobility was assessed. Both HDL subpopulations increased the efficiency of triglyceride lipolysis and apolipoprotein CII and CIII removal from VLDL up to ~90%. HDL-3 exerted significantly greater impact than HDL-2 on apolipoprotein E (43% vs. 18%, p < 0.001), free cholesterol (26% vs. 18%, p < 0.05) and phospholipids (53% vs. 43%, p < 0.05) removal from VLDL and VLDL remnant electrophoretic mobility (0.18 vs. 0.20, p < 0.01). A greater release of these components was also observed in the presence of total HDL with a low HDL-2/HDL-3 cholesterol ratio. Both HDL subpopulations affect VLDL composition during lipolysis, but HDL-3 exhibited a greater effect on this process. Altered composition of HDL related to significant changes in the distribution between HDL-2 and HDL-3 can influence the VLDL remnant features, affecting atherosclerosis progression.

Effects of dietary components on high-density lipoprotein measures in a cohort of 1,566 participants

Background

Recent data suggest that an increased level of high-density lipoprotein cholesterol (HDL-C) is not causally protective against heart disease, shifting focus to other sub-phenotypes of HDL. Prior work on the effects of dietary intakes has focused largely on HDL-C. The goal of this study was to identify the dietary intakes that affect HDL-related measures: HDL-C, HDL-2, HDL-3, and apoA1 using data from a carotid artery disease case–control cohort.

Methods

A subset of 1,566 participants with extensive lipid phenotype data completed the Harvard Standardized Food Frequency Questionnaire to determine their daily micronutrient intake over the past year. Stepwise linear regression was used to separately evaluate the effects of dietary covariates on adjusted levels of HDL-C, HDL-2, HDL-3, and apoA1.

Results

Dietary folate intake was positively associated with HDL-C (p = 0.007), HDL-2 (p = 0.0011), HDL-3 (p = 0.0022), and apoA1 (p = 0.001). Alcohol intake and myristic acid (14:0), a saturated fat, were each significantly associated with increased levels of all HDL-related measures studied. Dietary carbohydrate and iron intake were significantly associated with decreased levels of all HDL-related measures. Magnesium intake was positively associated with HDL-C, HDL-2, and HDL-3 levels, but not apoA1 levels, while vitamin C was only associated with apoA1 levels. Dietary fiber and protein intake were both associated with HDL-3 levels alone.

Conclusions

This study is the first to report that dietary folate intake is associated with HDL-C, HDL-2, HDL-3, and apoA1 levels in humans. We further identify numerous dietary intake associations with apoA1, HDL-2, and HDL-3 levels. Given the shifting focus away from HDL-C, these data will prove valuable for future epidemiologic investigation of the role of diet and multiple HDL phenotypes in heart disease.