IL-9-CFs-STIM1在病毒性心肌炎心肌纤维化中的作用与机制研究

A variety of cytokines are involved in cardiac fibrosis in viral myocarditis. Although a newly discovered cytokine IL-9 has proved to play an important role in many diseases characterized fibrosis, its relationship with cardiac fibrosis in VMC has not been elucidated yet. Our preliminary study has revealed that the infiltration of Th9 cells in myocardial lesions increased significantly in VMC mice. IL-9 directly inhibited viral replication and indirectly improved the prognosis of VMC by promoting cardiomyocyte autocrine TGF-β. As a result, we hypothesize that locally increased IL-9 may also contribute to the later process of fibrosis. STIM1 is an important target protein of IL-9, which mediates fibrosis by initiating calcium influx and signal pathway downstream. In this study, after establishing VMC model by CVB3 both in IL-9 KO and WT mice, IL-9 and its neutralizing antibody were applied in mice to clarify its effects on cardiac fibrosis in vivo. At the same time, cardiac fibroblasts(CFs) were directly stimulated with IL-9 to verify its effects on fibrosis in vitro. Furthermore, after respectively silencing and inhibiting STIM1 in cardiac fibroblast in vitro, we would detect the differentiation of fibroblasts and signaling pathway involved. In this way, the effcet and mechanism of IL-9-CFs-STIM1 in cardiac fibrosis in VMC were investigated , which provides a new therapeutic target for VMC.

研究表明多种细胞因子可以促进VMC心肌纤维化过程。新的细胞因子IL-9虽被证实参与多种纤维化疾病，但与VMC心肌纤维化的关系还未阐明。我们前期研究证实VMC小鼠心肌炎症部位浸润的Th9细胞明显增多，其通过分泌IL-9直接抑制病毒复制，还间接促进心肌细胞分泌TGF-β，缓解VMC炎症。由此，我们推测局部增多的IL-9在VMC后期纤维化中也起到重要作用。STIM1是IL-9下游重要蛋白，它所调控的下游通路是激活纤维化的重要途径。因此，本研究拟采用CVB3建立VMC模型，向IL-9KO及野生型小鼠注射IL-9及IL-9单抗，研究IL-9在体内对VMC心肌纤维化的作用；用IL-9及单抗刺激成纤维细胞，验证它在体外对纤维化的影响；体外沉默或抑制STIM1功能，检测成纤维细胞分化以及信号通路分子的表达。据此探究IL-9-CFs-STIM1对VMC心肌纤维化的作用与机制，为VMC的治疗提供新思路。

研究表明多种细胞因子促进心肌炎心肌纤维化过程。新的细胞因子IL-9虽被证实参与多种纤维化疾病，但与心肌炎心肌纤维化的关系还未阐明。我们前期研究证实心肌炎小鼠心肌炎症部位浸润的Th9细胞明显增多，其通过分泌IL-9直接抑制病毒复制，还间接通过促进心肌细胞分泌TGF-β，缓解心肌炎炎症进展。由此，我们推测局部增多的IL-9在心肌炎后期纤维化中也起到重要作用。STIM1是IL-9下游重要蛋白，它所调控的下游通路是激活纤维化的重要途径。因此，本研究采用MyHC-α建立EAM模型，向野生型小鼠注射IL-9及IL-9单抗，研究IL-9在体内对心肌炎心肌纤维化的作用。研究结果提示IL-9促进心肌炎小鼠心肌纤维化过程，在此过程中STIM1变化无统计学差异。用IL-9刺激成纤维细胞,提示IL-9能够刺激心脏成纤维细胞向肌肌成纤维细胞分化。此研究阐明IL-9在心肌炎心肌纤维化中作用，为心肌炎的治疗提供新思路。