The role of HDL- and non-HDL-related parameters in cell-cholesterol efflux capacity

Background and aims The regulation of cell-cholesterol efflux is not completely understood. Our aim was to assess the role of HDL- and non-HDL-related parameters in ATP-binding cassette transporter-A1 (ABCA1) and scavenger receptor class B-type-I (SRBI) cell-cholesterol efflux capacity (CEC) in coronary heart disease (CHD) cases and controls. Methods Lipids and apoA-I-containing HDL particles (by 2D gel-electrophoresis and immunodetection) were measured in 534 statin-treated CHD patients and in 1076 age-, gender-, and BMI-matched controls. ABCA1-CEC and SRBI-CEC were measured in apoB-depleted serum of 100 cases and 100 controls. Results Cases had significantly higher concentrations of preβ-1 particles (88%) and ABCA1-CEC (34%) compared to controls. ABCA1-CEC was positively correlated with the concentrations of preβ-1 particles, triglycerides, small-dense (sd) LDL-C, and LDL-C in both cases and controls. Moreover, both the concentration and the functionality of preβ-1 particles (ABCA1-CEC/mg preβ-1) were positively associated with the concentrations of sdLDL-C and triglycerides. Cases had 27% lower levels of large HDL particles but similar SRBI-CEC compared to controls. SRBI-CEC was correlated positively with HDL-C, apoA-I, and large-HDL particle levels. However, the functionality of large-HDL particles (SRBI-CEC/mg large particles) was significantly and positively correlated with the preβ-1/α-1 ratio, sdLDL-C, and triglycerides. Conclusions CHD patients have significantly higher concentration, but less functional preβ-1 particles in term of cholesterol efflux capacity compared to controls. Triglyceride-rich lipoproteins have significant influence on either the concentration or the functionality or both of HDL particles and consequently HDL-CEC.