胆固醇诱导人血管平滑肌细胞表型转化

The phenotypic switching of vascular smooth muscle cells induced by cholesterol

目的观察胆固醇对人血管平滑肌细胞(VSMC)表型转化的影响。方法体外培养人血管平滑肌细胞株,分别用(12.5、25.0、50.0)mg/L浓度的胆固醇作用细胞48 h;50.0 mg/L的胆固醇分别作用细胞24、48、72 h。采用实时定量PCR检测VSMC中α-平滑肌肌动蛋白(α-SMA)及平滑肌22α(SM22α)mRNA的表达;采用Western blot法检测胆固醇对VSMC中α-SMA、SM22α及单核细胞趋化蛋白-1诱导蛋白(MCPIP)表达的影响;CCK-8法检测VSMC增殖。结果 (12.5、25.0、50.0)mg/L胆固醇作用VSMC 48 h较对照组相比,α-SMA及SM22αmRNA水平及蛋白水平表达均降低(P<0.05),50.0 mg/L胆固醇作用后表达水平最低,存在剂量依赖效应;用50.0 mg/L胆固醇分别作用VSMC 48、72 h后,α-SMA及SM22αmRNA及蛋白表达与对照组相比均降低(P<0.05)。与对照组相比,胆固醇作用均明显促进VSMC增殖(P<0.05)。50.0 mg/L胆固醇作用VSMC48 h可诱导MCPIP蛋白表达增加。结论胆固醇作用VSMC后可降低收缩型标志蛋白α-SMA及SM22α的表达、促进VSMC增殖,提示胆固醇可诱导VSMC表型转化。

Objective To observe the effect of cholesterol on phenotypic switching of human vascular smooth muscle cells （VSMCs） in vitro. Methods VSMCs were treated with cholesterol at 12.5, 25.0 and 50.0 mg/L for 48 hours and at 50 mg/L for 24, 48 and 72 hours. Real-time quantitative PCR and Western blotting were respectively applied to detect the mRNA expressions of smooth muscle alpha-actin （α-SMA）, smooth muscle 22 alpha （SM22α） and the protein expressions of SM22α, monocyte chemotactic protein-1 induced protein （ MCPIP）. CCK-8 assay was performed to analyze the viability of VSMCs. Results Compared with control groups, cholesterol treatments resulted in a significant down-regulation of both mRNA and protein expressions of endogenous α-SMA and SM22α in VSMCs at 48 hours （ P 〈 0.05）, and the expressions were lowest when cholesterol was 50.0 mg/L. At 48 and ？2 hours, 50.0 mg/L cholesterol significantly decreased the expressions of α-SMA and SM22α （ P 〈 0.05）. The proliferation of VSMCs in cholesterol groups was promoted significantly compared with control groups （ P 〈 0.05）. Cholesterol at 50.0 mg/L was also able to induce MCPIP protein expression in VSMCs at 48 hours （P 〈0.05）. Conclusion Cholesterol can decrease the expressions of α-SMA and SM22α and enhance the proliferation of VSMCs, which suggests that cholesterol induces phenotypic switching of VSMCs.