钙调神经磷酸酶在心梗后心肌纤维化中的调控机制研究

Myocardial remodeling initiates instantly after myocardial infarction (MI), and myocardial fibrosis, which mainly involved cardiac fibroblasts, is the main characteristic of myocardial remodeling. Being the principal pathological process into cardiac dysfunction, there is currently no effective treatment measures for myocardial fibrosis. Others and our previous studies demonstrated that calcineurin played important roles in pathological myocardial hypertrophy, our pilot experiments showed calcineurin activity was up-regulated at border zone in a MI rat model, further at cardiac fibroblasts level, we confirmed calcineurin protein expression increased time- and dose-dependently with transforming growth factor-β1, the most important profibrotic cytokine, thus indicating a pivotal role of calcineurin in myocardial fibrosis. However, the pathological effects of calcineurin in cardiac fibroblasts post myocardial infarction and the underlying regulatory network are not fully clarified. Hence in the present study, by the way of transfecting cardiac fibroblasts with calcineurin lenti-virus and constructing calcineurin Aβ deficient transgenic mice, we aim to 1) explore the roles of calcineurin in cardiac fibroblasts proliferation, apoptosis, transdifferentiation and collagen synthesis post myocardial infarction; 2) elucidate the interaction signal network following transforming growth factor-β1; and 3) verify the feasibility of blocking calcineurin as a therapeutic target to alleviate myocardial fibrosis. This study, delivering a comprehensive insights to calcineurin in the research of myocardial fibrosis post myocardial infarction, is expected to deepen the understanding of the molecular mechanisms of myocardial fibrosis and provide experimental evidence for prevention and treatment of myocardial fibrosis.

心肌梗死发生后即启动了心肌重构过程，而心脏成纤维细胞参与的心肌纤维化是心肌重构的主要表现之一，也是导致心功能不全进展的主要病理机制，目前尚无有效的治疗措施。既往研究表明钙调神经磷酸酶（CaN）在病理性心肌肥厚中发挥重要作用，申请人前期研究发现心梗后大鼠梗死边缘区CaN表达上调，并进一步证实心脏成纤维细胞内CaN蛋白表达随促心肌纤维化因子TGF-β1干预时间和浓度依赖性升高，提示CaN参与了TGF-β1介导的心肌纤维化病理过程，但对CaN介导的心肌纤维化的调控网络仍未完全阐明。本课题拟通过CaN慢病毒转染心脏成纤维细胞以及构建CaN基因敲除小鼠，采用分子生物学、细胞学方法及在动物水平探讨CaN在心梗后心脏成纤维细胞生物学行为改变中的作用，阐明以CaN核心的信号调控网络，并验证CaN作为干预靶点的可行性，从而深化对心肌纤维化分子机制的认识，为心肌纤维化的防治提供思路和实验依据。

本项目拟通过动物水平和细胞水平研究探讨钙调神经磷酸酶（CaN）在心梗后心肌纤维化中的调控机制。初步结果显示：（1）TGF-β1能够通过活化CaN/NFAT通路促进心脏成纤维细胞(CFs)凋亡和分泌促纤维化因子，抑制CaN活性能够部分减轻其促凋亡和促纤维化作用，该作用独立于TGF-β1/Smads通路，是对经典TGF-β1信号通路的补充；（2）血浆CaN水平与左室功能不全具有相关性，动物水平应用ARB类药物（奥美沙坦）干预后左室舒张功能改善的同时伴随CaN浓度降低，提示血浆CaN水平或可作为左室舒张功能不全的评估指标；（3）CaN与微血管内皮细胞（MVEC）结构完整性具有相关性，具体调控有待进一步研究。