Effects of advanced glycation endproducts on the generation of macrophage-mediated oxidized low-density lipoprotein

Macrophages have a receptor that recognizes advanced glycation endproducts (AGE). In this study, we evaluated the effect of AGEs on the generation of macrophage-mediated oxidized low-density lipoprotein (LDL) by measuring the electrophoretic mobilities and lipid hydroperoxide (LHPO) levels of LDL. In the absence of the macrophage monolayer, the differences of the electrophoretic mobilities or LHPO levels of native (n) LDL did not differ significantly between control (c) bovine serum albumin (BSA) and those with AGE-BSA. In the presence of the macrophage monolayer, however, the difference was significant with higher levels after the incubation with AGE-BSA than with c-BSA. In the case of cLDL and glycated (g) LDL, the electrophoretic mobilities and LHPO levels of LDL after 20 h incubation with AGE-BSA in the presence of the macrophage monolayer were significantly higher than those with c-BSA. There were no significant differences, however between the electrophoretic mobilities and LHPO levels of cLDL and of gLDL. These results suggest that AGEs stimulate the generation of macrophage-mediated oxidized LDL, but do not directly stimulate the oxidative modification of gLDL.