Effect Of Simvastatin On Murine Aortic SMC Lipid Accumulation And The Relation With CXCL16

Objective The purpose of the present study was to investigate the effect of oxLDL(oxidized low-density lipoprotein)-induced lipid accumulation in murine aortic smooth muscle cells, the effect of simvastatin on oxLDL-induced lipid accumulation in foam cells of murine aortic smooth muscle cells and the relation with CXCL16.MethodsⅠ. Murine Aortic smooth muscle cells were incubated with oxLDL at different concentration (0,20,40,60,80mg/L) respectively for 24h,and murine Aortic smooth muscle cells were incubated with 60mg/L oxLDL at different time (0h,6h,12h,24h,36h).Oil red O staining was used to observe the intracellular lipid droplets.Cellular total cholesterol was determined by high performance liquid chromatography(HPLC) analysis. CXCL16 protein level was determined by Western blotting.Ⅱ.Murine aortic smooth muscle cells were coincubated with 60mg/L oxLDL and simvastatin at different concentration (0uM,1uM,10uM,100uM) respectively for 24h, and murine aortic smooth muscle cells were coincubated with 60mg/L oxLDL and simvastatin of the best concentration respectively for 0h,6h,12h,24h. murine aortic smooth muscle cells were incubated without oxLDL and simvastatin as the control groups. Oil red O staining was used to observe the intracellular lipid droplets.Cellular total cholesterol was determined by high performance liquid chromatography(HPLC) analysis. CXCL16 protein level was determined by Western blotting.ResultsⅠ. The oxLDL-induced lipid accumulation was in murine aortic smooth muscle cells in a time-dependent and dose-dependent manner(P<0.05) .Oil red O staining showed the more lipid droplets were in higher concentration oxLDL(60mg/L,80mg/L) groups than lower concentration oxLDL (20mg/L,40mg/L) groups .and the more lipid droplets were in longer time (24h,36h) groups than shorter time(6h,12h) groups. HPLC analysis demonstrated the ratios of cellular CE/TC were 10.8%,24.4%,35.6%,56.2%,57.5% at different concentrations of oxLDL(0,20,40,60,80mg/L) respectively for 24h(P<0.01).HPLC analysis demonstrated the ratios of cellular CE/TC were 10.8%,23.8%,37.0%,55.4%,58.9% at different times of oxLDL(60mg/L) 0h,6h,12h,24h,respectively(P<0.05).Ⅱ.We found that simvastatin inhibited cxcl16 protein synthesis and lipid accumulation in murine aortic smooth muscle cells in a time-dependent and dose-dependent manner . Oil red O staining showed intracellular lipid droplets were minor with the presence of simvastatin. HPLC analysis demonstrated the ratios of cellular CE/TC were 57.3%,55.1%,46.2%,17.9% at different concerntrations of simvastatin and oxLDL (60mg/L) 0uM,1uM,10uM,100uM ,respectively(P<0.05). HPLC analysis demonstrated the ratios of cellular CE/TC were 57.3%,34.8%,25.9%,17.9% at different times of simvastatin (100uM) and oxLDL (60mg/L) 0h,6h,12h,24h,respectively(P<0.01).Ⅲ. Western blotting also showed ,there were no significant differences in CXCL16 protein synthesis between the control groups and the lipid-loaded cell groups (CE/TC<50%)(P>0.05).But in the foam cell groups (CE/TC>50%), the CXCL16 protein synthesis was increased . The more lipid droplets was in foam cells ,the more CXCL16 protein synthesis was upregulated.(P<0.05). Western blotting also showed that simvastatin decreased the expression of cxcl16 in a time-dependent and dose-dependent manner (P<0.05).ConclusionsⅠ.The oxLDL-induced lipid accumulation was in murine aortic smooth muscle cells in a time-dependent and dose-dependent manner.Ⅱ.Simvastatin may decrease lipid accumulation in murine aortic smooth muscle cells in a time-dependent (incubated with 100umol/L simvastatin from 6 to 24h)and dose-dependent manner(1～100umol/L) .ⅢSimvastatin may downregulate oxLDL-induced cxcl16 expression in foam cells in a time-dependent((incubated with 100umol/L simvastatin from 6 to 24h)) and dose-dependent manner (1～100umol/L).