阿托伐他汀对ApoE基因敲除小鼠血管外膜成纤维细胞表型的影响

目的:观察载脂蛋白E基因敲除(ApoE~(-/-))小鼠动脉粥样硬化斑块形成过程中血管外膜α-平滑肌肌动蛋白(α-SMA)和转化生长因子-β1(TGF-β1)的表达变化,同时探讨阿托伐他汀抗动脉粥样硬化的作用机制。方法:选择40只6周龄雄性ApoE~(-/-)小鼠随机分为模型组和阿托伐他汀干预组,给予高脂饲料喂养。阿托伐他汀干预组给予阿托伐他汀(20 mg·kg~(-1)·d~(-1))灌胃,模型组给予等量生理盐水灌胃。20只同龄C57BL/6小鼠给予普通饲料喂养作为正常对照组。各组小鼠喂养至10、15周龄,在各个时点处死动物,取升主动脉制备连续切片,通过Movat染色进行形态学观察,测量并计算血管外膜厚度及斑块相对面积;天狼星红染色检测胶原的表达;免疫组织化学染色检测不同时点血管外膜α-SMA及TGF-β1的表达变化。用实时荧光定量PCR检测胸主动脉外膜中TGF-β1 mRNA的表达水平,通过Western blot法检测主动脉外膜中TGF-β1蛋白的表达。结果:与模型组相比,阿托伐他汀干预组的斑块相对面积明显减小,血管外膜厚度及胶原合成明显下降;免疫组化结果显示15周龄模型组血管外膜α-SMA及TGF-β1的表达高于10周龄模型组;与模型组相比,阿托伐他汀干预组血管外膜α-SMA及TGF-β1的表达明显下降。各时点模型组的TGF-β1 mRNA和蛋白的表达明显高于对照组,给药干预后TGF-β1 mRNA和蛋白的表达明显降低。15周龄模型组血管外膜TGF-β1 mRNA和蛋白的表达高于10周龄模型组。结论:阿托伐他汀可能通过下调TGF-β1的表达调控血管外膜成纤维细胞表型的改变,进而延缓ApoE~(-/-)小鼠动脉粥样硬化的进程。

Effect of atorvastatin on adventitial fibroblast phenotype differentiation in atherosclerosis of apolipoprotein E-knockout mice

AIM: To explore the effect of atorvastatin on the expression of α-SMA and TGF-β1 in the adventitia of ApoE^-/- mice with atherosclerosis, and to investigate the underlying mechanism of atorvastatin therapy. METHODS: Male ApoE^-/- mice (n=40) at 6-weeks of age were used to establish the atherosclerosis model by feeding with high fat diet. The mice were randomly divided into model group and atorvastatin group. In atorvastatin group, the mice were lavaged with atorvastatin at dose of 20 mg·kg^-1·d^-1. The mice in model group were given normal saline. C57BL/6 mice of the same age served as control group, feeding with ordinary food. The mice were respectively sacrificed at the time points of 10 and 15 weeks after feeding with different diets. The ascending aorta was removed for serial sectioning. Some sections were performed with Movat staining in order to observe the morphological changes of the tissues, and to measure the relative atherosclerotic plaque area and the thickness of the adventitia. Some sections were stained with Sirius red to identify the collagen synthesis. Immunohistochemistry assay was prepared to observe the expression of α-SMA and TGF-β1 in the adventitia at different time points. The expression of TGF-β1 at mRNA and protein levels in the thoracoabdominal aorta was measured by RT-qPCR and Western blot.RESULTS: Compared with model group, the formation of plaque in atorvastatin group significantly descended. Meanwhile the adventitial thickness and collagen synthesis also decreased. The results of immunohistochemical staining showed that compared with 10 weeks-model group, α-SMA and TGF-β1 in 15 weeks-model group was increased. The expression of α-SMA and TGF-β1 in atorvastatin group decreased significantly compared with model group. The expression of TGF-β1 at mRNA and protein levels in model group were higher than those in control group. They decreased in atorvastatin group compared with model group. Compared with 10 weeks-model group, the mRNA and protein of TGF-β1 in 15 weeks-model group were increased.CONCLUSION: Atorvastatin modulates adventitial fibroblast phenotype differentiation by suppressing expression of TGF-β1 and intervenes atherosclerotic development in ApoE^-/- mice.