内皮间充质转化与急性病毒性心肌炎早期心肌纤维化的关系

目的:探讨心脏内皮间充质转化(EndMT)与急性病毒性心肌炎心肌纤维化形成的关系。方法:28只Balb/c小鼠随机分为对照组(n=8)、心肌炎组(n=10)和心肌炎+重组人骨形成蛋白7(rh-BMP7)干预组(干预组,n=10)。心肌炎组和干预组小鼠1次性腹腔接种柯萨奇病毒B3(CVB3),对照组小鼠腹腔注射等量病毒培养液,对照组和心肌炎组小鼠次日一次性腹腔注射生理盐水0.1 ml,干预组小鼠腹腔注射等量rh-BMP7(300μg/kg)以抑制转化生长因子(TGF-β1);7 d后处死小鼠取心脏,以苦味酸天狼星红染色后计算心脏胶原容积积分(CVF),实时RT-PCR法和Western blot方法检测小鼠心脏中TGF-β1、内皮细胞标志物(CD31和VE-cadherin)、成纤维细胞特异蛋白(FSP-1)、α-平滑肌肌动蛋白(α-SMA)和I型胶原(Col1α1)的基因和蛋白表达情况。结果:与对照组比较,心肌炎组小鼠心肌坏死区出现明显心肌纤维化,也出现了以内皮细胞表型(CD31、VE-cadherin)丢失、间充质细胞表型蛋白(FSP-1、α-SMA)和胶原Col1α1增多为特征的EndMT现象;同时,TGF-β1表达明显增高;抑制TGF-β1可以同时逆转EndMT和心肌纤维化。结论:EndMT参与急性病毒性心肌炎心肌纤维化的形成,TGF-β1是重要介导因子。

Relationship between endothelial-to-mesenchymal transition and cardiac fibrosis in acute viral myocarditis

Objective: To investigate the relationship between endothelial-to-mesenchymal transition(EndMT) and myocardial fibrosis in acute viral myocarditis(VMC).Methods: Twenty-eight Balb/c mice were randomized into 3 groups:control group(n=8),VMC group(n=10) and intervention group(n=10).Mice in VMC and intervention groups were injected intraperitoneally(i.p) with single dose of coxsackievirus B3,mice in control group were injected with equal amount of viral-free vehicle.In the following day,mice in control and VMC groups were injected i.p with 0.1 ml of saline and intervention group with 0.1 ml of recombinant human bone morphogenetic protein 7(rh-BMP7) at a concentration of 300 μg/kg.The mice hearts were harvested after 7 d,cardiac collagen volume fraction(CVF) was calculated on picrosirius red-stained sections.mRNA and protein expression of TGF-β1,CD31,VE-cadherin,fibroblast special protein 1(FSP-1) and α-smooth muscle actin(α-SMA) and collagen 1α1 in myocardiac tissues were detected by real-time RT-PCR and Western blot analysis,respectively.Results: Compared to controls,overt fibrosis was presented in necrotic area of myocardium in VMC group.Meanwhile,marked increase of TGF-β1 expression accompanied with EndMT characterized by loss of endothelial phenotype(decreased expression of CD31 and VE-cadherin),gain of mesenchymal proteins(overexpression of FSP-1 and α-SMA) and increased synthesis of collagen was also demonstrated.Both EndMT and cardiac fibrosis were simultaneously reversed by TGF-β1 inhibition.Conclusion: EndMT is involved in cardiac fibrosis in acute viral myocarditis,TGF-β1 might be a main mediator.