病毒性心肌炎向扩张型心肌病演变过程中Th22细胞对心肌纤维化的作用研究

Viral myocarditis(VMC) and dilated cardiomyopathy (DCM) are common cardiac diseases. About 20% individuals with VMC will evolve into DCM. Researchers have suggested that VMC and DCM may represent the different pathological stages of a same disease. But the possible mechanism by which VMC progressing to DCM has not been postulated.Myocardial fibrosis is considered as a major determinant that contributes to the development from VMC to DCM. However mechanisms of which are not well addressed.Emerging data have show that Th22 cells participate in in?ammatory responses and fibrosis of autoimmune disease. Our data show that cardiac IL-22 mRNA increased siganificantly in mice VMC,but whether Th22 cell involve in myocardial fibrosis which in the progressing from VMC to DCM remain to be determined.In this study, mice are used to induced VMC and DCM model.The expression of Th22 cells and its major cytokine were assessed in different stage from VMC to DCM; anti-IL-22 antibody and IL-22-/- mice were used to block the pathogenic role of IL-22,whose major function is STAT3-dependent, myocardial fibrosis and Th22 major cytokine were assessed;the effect of IL-22 and STAT3 to myocardial fibroblasts were measured by cultruing in vitro,and major cytokine about myocardial firosis were detected in protein and mRNA level.This study aims to investigate the dynamic alterations of Th22 cells in the course from VMC to DCM, explore the role of Th22 cells and STAT3 in myocardial fibrosis，thus elucidate the pathogenesis of myocardial fibrosis in the progressing from VMC to DCM, and provide new evidence for potential therapeutic target.

病毒性心肌炎（VMC）和扩张型心肌病（DCM）临床常见，约20% DCM由VMC演变，被视为同一疾病的不同病理阶段，心肌纤维化是VMC发展为DCM的病理基础。Th22细胞参与多种自身免疫疾病纤维化形成。本课题组发现VMC小鼠心肌IL-22 mRNA显著升高，而Th22是否参与VMC向DCM进展过程心肌纤维化尚不清楚。本项目建立小鼠VMC及DCM模型，用流式细胞术等方法检测不同时期Th22及其相关因子改变；用抗IL-22抗体、IL-22-/-小鼠阻断IL-22作用，观察心肌纤维化及相关因子变化；用体外培养方式检测IL-22及其作用信号通路分子STAT3对心脏成纤维细胞增殖及分泌相关纤维化因子的影响。观察小鼠VMC进展至DCM过程Th22细胞的变化规律、探讨Th22及其作用信号通路分子STAT3对心肌纤维化的作用。本项目对阐明VMC向DCM演变过程中心肌纤维化机制和寻求新的防治靶点有重要意义。

病毒性心脏病(VHD)是与病毒感染有关的一组心血管疾病，包括病毒性心肌炎(VMC)和扩张型心肌病(DCM)。研究表明过度的心肌纤维化是VMC进展至DCM的重要原因，但确切的机制至今尚未阐明。本课题以雄性BALB/c小鼠CVB3病毒腹腔注射建立VHD模型，成功建立小鼠急性VMC、慢性病毒性心肌炎及DCM模型，并观察到随病情进展，心肌炎症逐渐减轻，心肌纤维化进行性加重。Th22细胞及其相关因子IL-22、IL-22R在急性VMC组、慢性病毒性心肌炎组及DCM组均较同时点对照组增高，且Th22细胞与IL-22、IL-22R表达呈正相关，提示Th22细胞及其相关因子参与VHD的演变过程。且DCM患者外周血中Th22细胞水平明显升高，提示其可能参与DCM发病机制。我们进一步利用抗IL-22抗体拮抗VMC小鼠体内的IL-22（有IL-17A共表达的背景下），结果证明，IL-22在VMC中促进心肌组织保护，其机制可能与抑制病毒复制，抑制炎性因子IL-6、IL-17及TNF-α的表达水平，促进IFN-γ表达有关。利用IL-17A-/-小鼠，结果证明在缺乏IL-17A的背景下，IL-22虽能抑制病毒复制，但加重VMC心肌炎症。其机制可能与激活下游信号分子STAT3，促进炎性因子TNF-ɑ、IL-6、IFN-γ的表达有关。提示在VMC小鼠中，IL-17A不能调节IL-22的抗病毒功能，但IL-17A可调节IL-22促炎/抑炎作用。此外，通过Anti-IL-22 Ab的拮抗作用，我们观察到随着Th22细胞百分比、IL-22及IL-22R的降低，AVMC及慢性病毒性心肌炎小鼠生存率明显降低，心肌纤维化进程加快，而且抗体干预后的小鼠在慢性病毒性心肌炎期的心肌纤维化程度已与未干预时的DCM期相当，与之相伴的是纤维化相关因子COL1-A1、COL3-A1、MMP9的增加及TIMP-1的降低。该结果提示分泌IL-22的Th22细胞通过对纤维化相关因子的干预，在VHD进程中起到延缓心肌纤维化和保护心肌的作用。而体外研究成纤维细胞培养的结果提示，IL-22刺激VMC小鼠心肌I型和III型胶原蛋白合成，且该作用可被STAT3信号通路阻断。这些结果提示Th22细胞因子IL-22可能是通过抑制心肌纤维化达到延缓或阻止AVMC向慢性病毒性心肌炎甚至DCM发展的重要靶标，而其信号通路分子STAT3可能是重要途径