Visfatin诱导THP-1源性泡沫细胞形成的机制研究

摘要

Objective To investigate the expression of ATP binding cassette transporter A1 ( ABCA1) and acyl-CoA : cholesterol acyltransferase 1 ( ACAT1) in macrophages induced by visfatin, and the mechanism of THP-1-derived foam cell formation. Methods THP-1 monocytes were induced into macrophages by 160 nmol/L phorbol myristate acetate(PMA)for 48 h,and the macrophages were exposed to visfatin with different concentrations and durations. Lipid droplets in cytoplasm were observed by Oil Red O staining. The expression levels of ABCA1 and ACAT1 mRNA and protein were detected by reverse transcriptase polymerase chain reaction(RT-PCR) and Western blot respectively. The contents of total cholesterol( TC) and free cholesterol (FC) were determined by enzyme fluorescence analysis. The contents of cholesterol ester(CF) were calculated by the difference between TC and FC. Results As compared with the control group,lipid droplets and the contents of FC and CF were increased in visfatin groups , and the ratio of CF to TC was significantly increased( more than 50 ％ ). The expression levels of ABCA1 mRNA and protein were down-regulated , while those of ACAT1 mRNA and protein were upregulated by visfatin in a concentration-and time-dependent manner(P＜0. 05). Conclusion The down-regulation of ABCA1 and upregulation of ACAT1 expression were induced by visfatin, which decreased the outflow of FC,increased the contents of CF, inducing THP-1-derived foam cell formation,which may provide a new evidence for visfatin-induced atherosclerosis.%目的 观察内脂素(visfatin)对人单核细胞株(THP-1)源性巨噬细胞胆固醇代谢相关基因ATP结合盒转运蛋白A1(ABCA1)和酰基辅酶A:胆固醇酰基转移酶1(ACAT1)表达的影响,探讨visfatin诱导THP-1源性泡沫细胞形成的机制.方法 THP-1单核细胞诱导分化为巨噬细胞,随机分组,给予不同浓度和不同作用时间的visfatin进行干预,分别运用油红O染色观察细胞质脂滴变化,反转录聚合酶链反应(RT-PCR)法和蛋白免疫印迹(Western blot)法检测各组细胞ABCA1及ACAT1 mRNA和蛋白表达,酶荧光学法检测细胞内总胆固醇(TC)和游离胆固醇(FC)含量,TC与FC之差为胆固醇酯(CE)含量.结果 与对照组比较,visfatin 干预组细胞质脂滴明显增多,细胞内FC和CE含量增加(均P＜0.05),CE与TC的比值明显增加(＞50%),ABCA1 mRNA和蛋白表达水平降低(均P＜0.05),ACAT1 mRNA和蛋白表达水平升高(均P＜0.05).相关分析显示,visfatin呈浓度和时间依赖性下调ABCA1 mRNA和蛋白的表达,上调ACAT1 mRNA和蛋白的表达.结论 visfatin下调巨噬细胞ABCA1的表达,上调ACAT1的表达,使细胞内FC流出减少,CE合成增加,从而诱导THP-1源性泡沫细胞的形成,这可能为visfatin致动脉粥样硬化发病机制的研究提供一个新的理论依据.