Analysis of the relationship between triglyceridemia and HDL-phospholipid concentrations: consequences on the efflux capacity of serum in the Fu5AH system

The high triglyceride/low HDL-cholesterol trait is a common finding in the general population. The aim of the present study was to analyze and interpret the relationships between triglycerides (TG), HDL-related parameters and serum cholesterol efflux potential in an asymptomatic population including both normo- and hyperlipidemic individuals. In a large sample (n=1143) of this population, there was a negative correlation between TG and HDL-cholesterol (HDL-C) (r=−0.49, P<0.0001) whereas the negative correlation between TG and HDL-phospholipid (HDL-PL) (r=−0.29, P<0.0001) was weaker, leading to a strong positive correlation between TG and HDL-PL/C ratio (r=0.58, P<0.0001). Thus, increased TG concentrations were associated with an enrichment of HDL with PL. Since we have demonstrated previously that HDL-PL is the major determinant for cholesterol efflux potential from Fu5AH rat hepatoma cells, we determined the effect of the variations in HDL lipid composition on the cholesterol efflux capacity in a subsample of 198 subjects. Compared with normolipidemic subjects (NLP) (TG≤1.7 mmol/l; LDL-C≤4.1 mmol/l, n=58), hypertriglyceridemic subjects (HTG) (TG>1.7 mmol/l, n=63) exhibited lower HDL-C levels (1.08±0.21 vs. 1.25±0.32, P=0.0003) whereas they showed similar HDL-PL concentrations (1.25±0.21 vs. 1.25±2.7) and, thus, higher HDL-PL/C ratio (1.17±0.15 vs. 1.02±0.14, P=0.0001). The relative efflux capacity of serum measured in the Fu5AH system (5% serum, 4 h incubation at 37°C) was on average identical in the HTG and NLP groups. Thus, this study provides evidence that despite decreased HDL concentrations, as determined routinely by the HDL-C assay, some HTG subjects maintained serum cholesterol efflux capacity thanks to the enrichment of HDL with PL.