CXXC5对心房颤动大鼠心肌纤维化的影响及机制

Effect of CXXC5 on myocardial fibrosis in rats with atrial fibrillation and its mechanism

目的:探讨锌指蛋白5(CXXC5)在心房颤动大鼠心肌纤维化中的表达及其对心肌纤维化的影响及可能机制。方法:将40只大鼠分为对照组(正常大鼠组)、空白对照组(心房颤动模型大鼠组)、阴性对照组(心房颤动大鼠尾静脉注射阴性对照病毒组)和过表达CXXC5组(心房颤动大鼠尾静脉注射过表达CXXC5病毒),每组10只。空白对照组、阴性对照组和过表达CXXC5组大鼠建立心房颤动心肌纤维化模型(腹部皮下注射异丙肾上腺素建立心房颤动心肌纤维化模型)。伊红-苏木素(HE)染色和Masson染色观察心肌组织形态学变化,并测定胶原容积分数(CVF);采用荧光定量聚合酶链反应(qPCR)测定心肌组织中Ⅰ型胶原、CXXC5、转化生长因子β1(TGF-β1)、Smad7 mRNA水平;采用Western blot法测定大鼠心肌组织中Ⅰ型胶原、CXXC5、TGF-β1、Smad7蛋白水平。结果:HE染色和Masson染色显示:对照组大鼠心肌组织形态学正常;空白对照组和阴性对照组大鼠心肌细胞排列紊乱,间质胶原纤维增多,心肌纤维化严重;过表达CXXC5组大鼠心肌细胞排列稍紊乱,心肌纤维化较轻;模型组大鼠CVF明显高于对照组(P<0.05)。与对照组相比,其他3组大鼠CVF升高(P<0.05),CXXC5、Smad7 mRNA和蛋白水平升高(P<0.05),Ⅰ型胶原、TGF-β1 mRNA和蛋白水平降低(P<0.05);与空白对照组和阴性对照组相比,过表达CXXC5组大鼠CVF降低(P<0.05),心肌组织中CXXC5、Smad7 mRNA和蛋白水平升高(P<0.05),Ⅰ型胶原、TGF-β1 mRNA和蛋白水平降低(P<0.05);空白对照组和阴性对照组大鼠心肌组织中Ⅰ型胶原、CXXC5、TGF-β1、Smad7 mRNA和蛋白水平差异无统计学意义(P>0.05)。结论:心房颤动心肌纤维化大鼠心肌组织CXXC5水平降低,TGF-β1/Smad7信号通路激活;过表达CXXC5可通过抑制TGF-β1/Smad7信号通路抑制心房颤动大鼠心肌纤维化。

Objective:To investigate the expression of Zinc finger protein 5(CXXC5)in myocardial fibrosis of atrial fibrillation rats and its effect and possible mechanism on myocardial fibrosis.Methods:40 rats were divided into control group(normal rat group),blank control group(Atrial fibrillation model rat group),negative control group(Atrial fibrillation rat group with tail vein injected negative control virus)and overexpressed CXXC5 group(Atrial fibrillation rat group with tail vein injected overexpressed CXXC5 virus),with 10 rats in each group.The rats of blank control group,negative control group and overexpressed CXXC5 group were established atrial fibrillation myocardial fibrosis model(subcutaneous injection of Isoproterenol to establish myocardial fibrosis of atrial fibrillation model).The morphological changes of myocardial tissue were observed by hematoxylin-eosin(HE)staining and Masson staining,and the collagen volume fraction(CVF)was determined.The levels of typeⅠcollagen,CXXC5,transforming growth factorβ1(TGF-β1)and Smad7 mRNA in myocardial tissues were determined by quantitative polymerase chain reaction(qPCR).The levels of typeⅠcollagen,CXXC5,TGF-β1 and Smad7 proteins in myocardial tissue were determined by Western blot.Results:HE staining and Masson staining showed that:in control group,the morphology of myocardial tissue was normal;in blank control group and negative control group,the myocardial cells were disordered,interstitial collagen fibers were increased,and myocardial fibrosis was severe;in overexpressed CXXC5 group,the cardiac cells were slightly disordered,and myocardial fibrosis was lighter.Compared with control group,the CVF was increased(P<0.05),the CXXC5,Smad7 mRNA and protein levels were increased(P<0.05),and the typeⅠcollagen and TGF-β1 mRNA and protein levels were decreased(P<0.05)of the other three groups.Compared with blank control group and negative control group,the CVF was decreased(P<0.05),the mRNA and protein levels of CXXC5 and Smad7 in myocardial tissue of overexpressed CXXC5 group were increased(P<0.05),and the mRNA and protein levels of typeⅠcollagen and TGF-β1 were decreased(P<0.05).There were no significant differences in the mRNA and protein levels of typeⅠcollagen,CXXC5,TGF-β1 and Smad7 between blank control group and negative control group(P>0.05).Conclusion:The level of CXXC5 in myocardial tissue of rats with myocardial fibrosis of atrial fibrillation is decreased,and the TGF-β1/Smad7 signaling pathway is activated.Overexpression of CXXC5 can inhibit myocardial fibrosis in rats with atrial fibrillation by inhibiting TGF-β1/Smad7 signaling pathway.