Advanced glycation end products affect cholesterol homeostasis by impairing ABCA1 expression on macrophages.

Abstract

Reverse cholesterol transport (RCT), which is intimately linked to high-density lipoproteins (HDLs), plays a key role in cholesterol homeostasis and the prevention of atherosclerosis. The goal of the present study was to investigate the effect of aging and advanced glycation end products (AGEs) on RCT as well as on other factors that may affect the antiatherogenic property of HDLs. The transfer of macrophage-derived cholesterol to the plasma and liver and then to the feces for elimination was significantly lower in aged mice than in young mice. Chronic injection of d -galactose (D-gal) or AGEs also significantly reduced RCT (65.3% reduction in [3H]cholesterol levels in the plasma of D-gal-treated mice after 48 h compared with control mice, P < 0.01). The injection of both D-gal and aminoguanidine hydrochloride increased [3H]cholesterol levels in the plasma, although the levels were lower than those of control mice. The in vitro incubation of HDLs with dicarbonyl compounds increased the carbonyl and conjugated diene content of HDLs and significantly reduced PON1 paraoxonase activity (87.4% lower than control HDLs, P < 0.0001). Treating J774A.1 macrophages with glycated fetal bovine serum increased carbonyl formation (39.5% increase, P < 0.003) and reduced ABCA1 protein expression and the capacity of macrophages to liberate cholesterol (69.1% decrease, P < 0.0001). Our results showed, for the first time, that RCT is altered with aging and that AGEs contribute significantly to this alteration.