NLRC5通过调控内皮间质转化促进糖尿病心肌病心肌纤维化的机制研究

Diabetic cardiomyopathy is a heart disease characterized by cardiomyocyte hypertrophy and myocardial fibrosis, which eventually leads to heart failure. There is still no specific treatment. In recent years, studies have shown that high glucose-induced endothelial mesenchymal transition is one of the key factors of myocardial fibrosis in diabetes. NLRC5 is a member of the NOD-like receptor family and its role in diabetic cardiomyopathy remains unclear. In the early stage of this project, it was found that myocardial fibrosis was significantly improved after the NLRC5 gene was knocked in diabetic mice, and the overexpression of NLRC5 could induce endothelial cell injury and change the shape of endothelial cells into the shape featured by fibroblasts. Therefore, we hypothesized that NLRC5 deficiency affects diabetic myocardial fibrosis by regulating endothelial interstitial transformation. In this project firstly the NLRC5 knockout mouse and diabetic mouse model were constructecd to observe the phenotype of NLRC5 deletion in the regulation of diabetic myocardial fibrosis and cardiac function. Then, at the level of primary cardiac microcirculation endothelial cells and animals, the regulation of NLRC5 on endothelial mesenchymal transition in diabetic cardiomyopathy was investigated respectively. Secondly, we will further verify the TGF-beta/Snail1 signaling pathways. And by the method of mass spectrometry and co-immunoprecipitation, NLRC5 was used to identify key target proteins and the specific structure domain of NLRC5 for the regulation of diabetic cardiomyopathy. Finally, the phenotypic changes about fibroblasts of endothelial origin were further tracked by lineage tracing technology, which fully explained the regulation and mechanism of NLRC5 regulating diabetic myocardial fibrosis. The treatment of diabetic cardiomyopathy will provide new targets in the future.

心肌纤维化是糖尿病心肌病重要的病理生理过程，目前仍无特效治疗。研究认为高糖诱导内皮间质转化是糖尿病发生心肌纤维化的关键因素之一。NLRC5是NOD样受体（NLRs）家族最重要的成员之一，能引起炎症和细胞死亡的细胞内模式识别受体。本项目前期发现NLRC5基因敲除可以显著改善糖尿病小鼠的心肌纤维化，体外过表达NLRC5可以诱导内皮细胞损伤，促使内皮细胞形状转变成成纤维细胞特征的形状。因此，我们推测NLRC5缺失通过调控内皮间质转化影响糖尿病心肌纤维化。本项目拟通过构建NLRC5基因敲除小鼠和糖尿病小鼠模型，培养小鼠原代心脏微循环内皮细胞，探究NLRC5调控内皮间质转化继而影响糖尿病心肌纤维化的作用。其次验证TGF-β/Snail1信号通路及寻找NLRC5作用的关键靶蛋白和具体结构域，最后利用谱系追踪技术进一步追踪内皮源性的成纤维细胞的表型改变，从而全面阐述NLRC5调控糖尿病心肌纤维化的机制。

本项目揭示了天然免疫蛋白NLRC5在心肌重构中的作用及机制，对未来肥厚性心肌病患者的诊疗提供了新的理论基础。此外，还开展左心疾病所致肺动脉高压的研究，探究天然免疫蛋白在其中的潜在作用机制。重要的研究结果包括：1）发现了NLRC5在糖尿病心肌病小鼠中表达上调以及对心脏微循环内皮细胞损伤的作用。2）NLRC5在肥厚性心肌病患者外周血单核巨噬细胞中表达上调，并揭示了NLRC5与巨噬细胞中HSPA8相互作用，调节巨噬细胞中IL6的分泌，从而影响心肌细胞肥大和成纤维细胞的活性，从而对心肌重构产生影响。3）进行3型肺动脉高压患者影像学资料的分析，结合影像学和病理学数据预测患者肺动脉平均压，有望成为有创评估的替代手段之一。4）发现Treg细胞在左心疾病所致的肺动脉高压中肺静脉和肺动脉周募集，以及证实Treg对其肺血管重构发挥改善作用，并揭示内皮间质转化可能在其中发挥关键调节作用。以上的部分研究成果已被JACC Basic to Translational Science杂志接收和JACC Asia杂志上发表。