大鼠脑缺血再灌注通过TGF-β1/Smad7通路诱发急性肾损伤的机制探究

Mechanism of acute renal injury induced by rat cerebral ischemia-reperfusion through TGF-β1/Smad7 pathway

目的:通过建立稳定、有效、符合临床的大鼠脑缺血再灌注损伤诱发急性肾损伤动物模型,探讨转化生长因子-β1(TGF-β1)/Smad7通路在其中的作用,为临床诊疗提供可能的作用靶点。方法:将20只雄性SD大鼠随机分为正常组和缺血2、4、6 h组4组各5只,采用大脑中动脉栓塞法制作缺血模型,通过检测大鼠血尿素氮(BUN)、血肌酐(Scr)判断肾脏功能,HE和Masson染色观察肾脏组织病理变化。选取大鼠肾脏损伤相对较严重的缺血时间为本研究需要的模型缺血时间点。取25只雄性SD大鼠随机分为5组,并根据得出的缺血时间点行再灌注处理,在不同的再灌注时间点处死。采用荧光定量聚合酶链反应和蛋白质印迹法检测TGF-β1、Smad7、Ⅰ型和Ⅲ型胶原蛋白的mRNA及蛋白表达水平。酶联免疫吸附试验(ELISA)检测大鼠血浆炎症因子水平变化。结果:大鼠脑组织缺血4 h血清BUN和Scr水平高于其他组(P<0.05)。缺血4 h/再灌注24 h肾脏组织胶原因子mRNA表达、TGF-β1蛋白表达水平高于其他组(P<0.05),Smad7蛋白表达水平低于其他组(P<0.05)。大鼠脑组织缺血4 h/再灌注24 h时Masson染色结果显示肾脏组织出现胶质纤维沉积,并且炎症因子表达明显高于正常组和缺血4 h组(P<0.05)。结论:大鼠脑组织缺血4 h/再灌注24 h时可通过TGF-β1/Smad7通路的激活,增加肾脏组织Ⅰ型和Ⅲ型胶原蛋白表达,导致肾功能下降和肾脏组织纤维化。

Objective:To explore the role of transforming growth factor(TGF)-β1/Smad7 pathway in acute renal injury induced by rat cerebral ischemia-reperfusion by establishing a stable,effective and clinical rat model so as to provide a possible target for clinical diagnosis and treatment.Methods:Twenty rats were randomly divided into four groups:control group,ischemia 2 h group(I 2 h),ischemia 4 h group(I 4 h)and ischemia 6 h group(I 6 h)with five rats in each group.Middle cerebral artery embolization was used to establish ischemic model.Renal function was determined by detecting blood urea nitrogen(BUN)and serum creatinine(Scr).Renal histopathological changes were observed by HE and Masson staining.The group with relatively serious renal injury was selected as the model ischemia time point for this study.Then twenty five rats were randomly divided into five groups.According to the obtained ischemia time points,the rats were treated with reperfusion and sacrificed at different time points.mRNA and protein expression levels of TGF-β1,Smad7,collagenⅠand collagenⅢwere detected by fluorescence quantitative polymerase chain reaction and Western blot.The changes of plasma inflammatory factors were detected by enzyme-linked immunosorbent assay(ELISA).Results:The levels of BUN and Scr in I 4 h were higher than those in other groups(P<0.05).Expression of collagen I mRNA and TGF-β1 protein at ischemia 4 h/reperfusion 24 h was higher than that of other groups,and the expression level of Smad7 protein was lower than that of other groups(P<0.05).Meanwhile glial fiber deposition was found in renal tissue,and the expression of inflammatory factors was more significantly increased than that in the control group(P<0.05).Conclusion:After cerebral ischemia 4 h/reperfusion 24 h,the expression of collagenⅠand collagenⅢin renal tissue is increased,which results in the decline of renal function and renal fibrosis through the activation of TGF-β1/Smad7 pathway.