The expression of ATP-binding cassette transporter A1 in Chinese overweight and obese patients.

Abstract

ATP-binding cassette transporters (ABCA1, ABCG1) and scavenger receptor class B type I (SR-BI) are the three most important cellular cholesterol transporters/receptor in regulating cholesterol efflux. We have investigated whether the expression of these transporters/receptor is altered in overweight and obese patients, and the potential association with the circulating adipokines. Adiponectin, leptin and resistin were assayed in two groups of healthy controls, overweight and obese patients. The expression of ABCA1, ABCG1 and SR-BI in monocytes was measured. Cholesterol efflux from monocyte-derived macrophages was also determined. Circulating adiponectin was decreased, whereas leptin and resistin were increased in overweight and obese patients compared with healthy controls. ABCA1 expression was significantly decreased in overweight and obese patients (P<0.01), whereas the levels of ABCG1 and SR-BI were comparable between the two groups. Adiponectin was correlated with ABCA1 (r=0.44, P<0.001), but not with ABCG1 and SR-BI. No associations between leptin, resistin and the expression of ABCA1, ABCG1 and SR-BI were found. Cholesterol efflux from monocyte-derived macrophages to apolipoprotein AI or to autologous serum was significantly impaired in overweight and obese patients, which were correlated with ABCA1 expression (r=0.47, P<0.001; r=0.43, P<0.001, respectively). The expression of ABCA1 in monocytes is reduced in overweight and obese patients, and the reduction in ABCA1 is associated with the impairment of cholesterol efflux from monocyte-derived macrophages.