Effects of advanced glycation end products on expression of scavenger receptor class B type I (SR-BI) in U937 macrophages

[Objective]To learn the effects of differentiation and AGEs on expression of SR-BI in U937 macrophages. U937 cells were cultured with 100 nM PMA in order to differentiate to macrophages. U937 macrophages were cultured with AGEs at different concentration for 24 hours and at a concentration of 400 mg/L for different time. A immunocytochemical method was used to detect SR-BI protein during the PMA-induced differentiation. Western blotting analysis was used to measure SR-BI protein expression stimulated by AGEs. Immunocytochemistry showed that after exposure of U937 cells to PMA for 24, 48, 72 hours, the average integrated optical density values of SR-BI protein expression in U937 cells were (15.94±3.56), (27.86±4.39) and (9.08±2.37), with the first two groups higher than that in 0 h group (7.76±1.74, P 0.05). Western Blot showed that exposure of U937 macrophages to AGEs at different concentrations (100, 200, 400 mg/L) for 24 hours resulted in a 1.44-fold, 2.38-fold and 2.77-fold increase in the expression of SR-BI protein in U937 macrophages comparing with BSA control group (P 0.05). Meanwhile, exposure of U937 macrophages to AGEs at the concentration of 400 mg/L for 6, 12, 24, 48 hours resulted in 1.38-fold, 2.49-fold, 3.76-fold and 4.25-fold increase in the expression of SR-BI protein in U937 macrophages comparing with 0 h group(P0.05). [Conclusions] The data suggest that PMA-induced differentiation can increase the expression of SR-BI protein in U937 macrophages at 24, 48 hours, and decrease at 72 hours. U937 macrophages that were incubated in medium containing AGEs showed an increase in the expression of SR-BI protein in a time and dose dependent manner.