Cholesterol efflux from J774 macrophages and Fu5AH hepatoma cells to serum is preserved in CETP-deficient patients

BackgroundThe role of CETP in the development of atherosclerosis is debatable, and few data exist regarding the total impact of CETP inhibition on cholesterol efflux.MethodsAcceptor capacities of whole serum and HDL subfractions separated by HPLC were compared using 2 different cell systems. Subjects with CETP deficiency (2 homozygous, 1 compound heterozygous, and 5 heterozygous) were analyzed along with 10 normolipidemic controls. The fractional efflux from cholesterol-labeled Fu5AH hepatoma cells was determined to be SR-BI mediated. The efflux difference between control and liver X receptor (LXR) agonist-induced ABCA1-upregulated J774 macrophages was considered as a measure of ABCA1-mediated efflux.ResultsFor the Fu5AH cell system, the total acceptor capacities of whole serum and HPLC-separated HDL fraction 2 obtained from the homozygous subjects were 38% and 116% higher than the corresponding values for the controls, respectively (p < 0.05). For the J774 cell system, the total acceptor capacities of whole serum and HPLC-separated HDL fractions were similar among the CETP-deficient subjects and controls.ConclusionsSerum from homozygous subjects with CETP-null defects exhibited enhanced acceptor capacity via an SR-BI dependent pathway, which is regulated by the middle HPLC-separated HDL fraction. Further, the cholesterol acceptor capacity of serum obtained from patients having complete and partial CETP deficiency was preserved via an ABCA1-dependent pathway.