Effect Of Cholesterol Efflux On The Oxidized Low Density Lipoprotein-induced Apoptosis In Macrophages

AIM: To explore the effect of cholesterol efflux on the oxidized low density lipoprotein (ox-LDL)-induced apoptosis in macrophages.METHODS: The concentration of cellular cholesterol was detected by highperformance liquid chromatography; Oil Red O Dyeing experiment was used to show the cellular lipid droplets in cells; Cholesterol efflux was determined by FJ-2107P type liquid scintillator; Apoptosis cells were confirmed by Hoechst 33258 staining and flow cytometric analysis.RESULTS: After treated with 50mg/L ox-LDL for 0, 12, 24, 48, 96h, the apoptoticrate of RAW264.7 macrophages increased in a time-dependent manner. Typical morphological change of apoptosis such as condensed chromatin and shrunken nucleus markedly increased. When cells were treated with ox-LDL for 48h, many lipid droplets accumulated in cells, and the content of cellular total cholesterol and cholesterol ester also increased obviously. Foamy cells induced by ox-LDL, were then treated with various concentration of HDL3 (50,100,200mg/L) for 24h, the rate of intracellular cholesterol efflux increased obviously and the concentration of cellular cholesterol decreased in a dose-dependent manner. Meanwhile, the apoptotic rate decreased in a dose-dependent manner, typical morphological change of apoptosis also descended. However, Brefeldin(BFA), an inhibitor of cholesterol efflux, markedly attenuated the protective effect of HDL3 on ox-LDL-induced apoptosis, and increased the content of total cholesterol, lipid droplets in cells when compared with the group of HDL3 (200mg/L) alone. Meantime, 10mmol/L β-cyclodextrin (β-CD), a...