The expression of ATP-binding cassette transporters in hypertensive patients

Cholesterol efflux is regulated by cholesterol transporters, including adenosine triphosphate-binding cassette transporters, A1, G1 (ABCA1, ABCG1), and scavenger receptor class B type I (SR-BI). We have investigated whether the expression of these transporters/receptor is altered in patients with hypertension and also studied their functional effects in cholesterol efflux. The newly diagnosed hypertensive patients, as well as age- and gender-matched healthy controls were recruited. mRNA of ABCA1, ABCG1 and SR-BI in monocytes was measured. The functional effects of the three transporters/receptor and cholesterol efflux from monocyte-derived macrophages ex vivo were also determined. The expression of ABCA1 and ABCG1 was significantly decreased in the newly diagnosed untreated hypertensive patients compared with that in healthy controls. The levels of ABCA1 and ABCG1 were negatively associated with blood pressure, and the reduction of ABCA1 and ABCG1 could be reversed by anti-hypertensive therapy. No significant associations between plasma lipids, oxidized low-density lipoprotein (LDL) and the expression of ABCA1 or ABCG1 were found. Cholesterol efflux from monocyte-derived macrophages to autologous serum, apolipoprotein AI (apoAI) or high-density lipoprotein (HDL) was impaired in hypertensive patients. Cholesterol efflux to autologous serum or apoAI was associated with the expression of ABCA1, whereas cholesterol efflux to autologous serum or HDL was associated with the expression of ABCG1. The expression of ABCA1 and ABCG1 in monocytes is reduced in hypertensive patients, which could be reversed by anti-hypertensive therapy. The reduction in ABCA1/ABCG1 is associated with the impairment of cholesterol efflux from monocyte-derived macrophages.