组蛋白去甲基化酶KDM2B在心肌缺血后心脏成纤维细胞炎症和功能转化中的作用及表观机制研究

The dysregulated levels of aseptic inflammation and fibrosis repair, two key pathological processes post myocardial ischemia, can lead to adverse cardiac remodeling and even heart failure. Cardiac fibroblasts play important roles in the early, middle and later stage of ischemic heart diseases by both mediating aseptic inflammation and fibrosis transformation. The function of cardiac fibroblasts in the long stage of ischemic heart diseases will be regulated by epigenetic modification enzymes. Our data from microarray analysis and the preliminary experiments showed that the expression level of histone demethylase KDM2B in cardiac tissue was significantly up-regulated post myocardial ischemia injury, and this up-regulation of KDM2B was also especially observed in cardiac fibroblasts but not in cardiomyocytes and macrophages. Compared with wide type mice, KDM2B knock-out mice had less level of aseptic inflammation and fibrosis as well as better heart function. KDM2B deficiency inhibited the production of inflammation cytokines triggered by DAMPs, and also decreased the expression levels of molecules involved in fibrosis induce by TGF-b in cardiac fibroblasts. Thus, we suppose that KDM2B promotes aseptic inflammation and fibrosis transformation mediated by cardiac fibroblasts post myocardial ischemia injury, which results in adverse cardiac remodeling. In this research project, based on the characteristic of KDM2B which regulates the methylation modification of H3, we will aim to further investigate the target molecule and epigenetic mechanisms underlying the regulation of cardiac fibroblast function by KDM2B, which may shed a new light on theoretical basis and potential target for the clinical intervention of ischemic heart diseases.

心肌缺血后无菌性炎症和纤维化修复是两个重要的病理过程，其水平失调会导致不良心脏重构乃至心衰。心脏成纤维细胞可同时介导无菌性炎症及纤维化转化，在缺血性心脏病的早中晚期均发挥重要功能，在其发挥作用的长时间过程中，可能受到表观修饰酶调控。我们前期芯片及预实验结果发现心肌缺血损伤诱导心肌组织特别是心脏成纤维细胞中组蛋白去甲基化酶KDM2B表达升高；KDM2B基因敲除小鼠心肌缺血损伤后炎症和纤维化显著降低，心功能明显改善；KDM2B基因缺陷下调原代心脏成纤维细胞中DAMPs激发的炎症因子产生和TGF-b诱导的纤维化分子表达。据此我们科学假设KDM2B能促进心肌缺血后心脏成纤维细胞介导的无菌性炎症以及TGF-b通路诱导的纤维化功能转化，导致不良心脏重构。我们将依据KDM2B对H3组蛋白修饰的特点，寻找其调控心脏成纤维细胞功能的靶分子并研究其表观调控机制，为缺血性心脏疾病临床干预提供理论依据和潜在靶点。

心肌遭遇缺血及压力负荷等应激性损伤后继发无菌性炎症和纤维化是两个重要的病理过程，其水平失调会导致不良心室重构乃至心衰。心脏成纤维细胞在这两者的平衡中发挥重要调节作用，并且可能受到表观修饰酶调控。本项目发现心肌缺血及压力负荷损伤诱导心肌组织及心脏成纤维细胞中组蛋白去甲基化酶KDM2B表达升高。KDM2B基因敲除小鼠心肌梗死及压力负荷损伤后心功能明显改善、心肌组织的炎症和纤维化水平显著降低。KDM2B缺陷或干扰后可下调原代心脏成纤维细胞中TGF-b诱导的纤维化相关分子表达。另外，KDM2B缺陷或干扰后能降低心肌巨噬细胞中IL-6的产生，并通过旁分泌作用于成纤维细胞，降低成纤维细胞中STAT3与CAMKⅡ的活化，从而下调成纤维细胞中纤维化相关分子的表达，表明KDM2B通过调控巨噬细胞中IL-6的产生及旁分泌作用去影响成纤维细胞的表型与功能转变，从而实现应激状态下心脏巨噬细胞与成纤维细胞的互作调节。本项目执行期内我们的研究成果证实KDM2B通过促进IL-6启动子区染色质开放而选择性促进炎症及感染情况下巨噬细胞中IL-6产生（Cellular and Molecular Immunology, 2020），在此基础上我们进一步阐明了KDM2B在心脏应激性损伤后炎症、心肌纤维化中的调控作用，为心脏应激性损伤后的不良心脏重构及心衰的发生机制提供了新的表观遗传学解说，同时为心衰的干预提供了潜在的新靶点。综上，本项目发表标注本项目资助的SCI论文4篇，申请国家发明专利3项，已顺利完成所有研究内容和目标。