Apolipoprotein CIII bound to apoB-containing lipoproteins is associated with small, dense LDL independent of plasma triglyceride levels in healthy men.

Description

The objective of this study was to examine the association between apolipoprotein CIII and small, dense LDL levels. The study sample was composed of 2 subgroups of asymptomatic, middle-aged men. In the first subgroup, measurements of the mass concentrations of LDL subfractions were performed by analytical ultracentrifugation in 141 subjects. In the second subgroup (n=14), a density gradient ultracentrifugation of plasma was performed, and 3 fractions in the LDL density range were collected. The analyses revealed that increased plasma levels of apolipoprotein CIII in apolipoprotein B-containing lipoproteins (LpB:CIII) were associated with increased levels of small, dense LDL. Therefore, an inverse association was found between plasma levels of apolipoprotein CIII and LDL peak particle size. These associations were maintained after adjustment for plasma triglycerides. In a multiple linear regression analysis, LpB:CIII was an independent predictor of small, dense LDL levels. Moreover, the molar ratio of apolipoprotein CIII to apolipoprotein B was significantly higher in the LDL fraction of highest density. These results suggest that there is an enrichment of apolipoprotein CIII in small, dense LDL which could contribute to their increased atherogenic risk.