Reg3β/N2-HMGB1调控巨噬细胞再编程参与心肌炎症损伤修复的机制研究

Myocarditis is an inflammatoy disease charaterized by monocytes/macrophages infiltration and progressive myocardial injury. Our preliminay data showed that, in experimental autoimmune myocarditis (EAM) mice, Reg3β released by cardiomyocytes could promote the reprogramming of macrophages into tissue repaire type, and N2-HMGB1 secreted by macrophages could promote the dedifferentiation of cardiomyocytes. Therefore, we hypothesize that dedifferentiated cardiomyocytes of EAM mice regulate the reprogramming of infiltrating macrophages by releasing Reg3β; and then reprogammed macrophages promote the dedifferentiation and proliferation of cardiomyocytes and the further release of Reg3β by secreting N2-HMGB1; Reg3β and N2-HMGB1 form a positive feedback regulation loop contribute to the repair of injured myocardium. We intend to verify above hypothesis from three aspects: ①In vitro, to clarify the molecular mechanism of Reg3β regulating marophage reprogramming and N2-HMGB1 secreting; ②In vitro, to clarify the molecular mechanism of N2-HMGB1 regulating the dedifferentiation and proliferation of cardiomyocytes and Reg3β releasing; ③In vivo, to confirm the role of Reg3β/N2-HMGB1 loop regulating macrophage reprogramming involved in the repair of injured myocardial tissue in EAM by the application of Reg3β-/-, HMGB-/-, and monocytes/microphages-/-mice. Following the project, we will expect to reveal the regulating mechanism of myocardial microenviroment on macrophage reprogramming and cardiac repair, and provide new ideas and targets for the intervention therapy of myocarditis.

心肌炎是以单核/Mφ浸润、进行性心肌损伤为特征的炎性疾病。预实验发现EAM小鼠心肌细胞释放的Reg3β可诱导Mφ向组织修复型转变，而Mφ分泌的N2-HMGB1可促进心肌细胞去分化。因此推论：EAM时去分化心肌细胞释放Reg3β调控浸润Mφ再编程；后者分泌N2-HMGB1促进心肌细胞去分化和增殖，进一步释放Reg3β，形成正反馈环路，参与损伤心肌修复。本课题拟从三方面验证上述假说：①体外阐明Reg3β调控心肌浸润Mφ再编程及分泌N2-HMGB1的分子机制；②体外阐明N2-HMGB1调控心肌细胞去分化、增殖及Reg3β释放的机制；③体内利用Reg3β-/-、HMGB1-/-、单核/Mφ-/-小鼠等，证实Reg3β/N2-HMGB1环路调控Mφ再编程参与EAM小鼠受损心肌修复的作用。课题研究结果将揭示心肌局部微环境对Mφ再编程及心肌修复的调控机制，为心肌炎的干预治疗提供新的思路和靶点。

心肌炎是以单核/巨噬细胞浸润、进行性心肌损伤为主要特征的炎性疾病，心肌浸润巨噬细胞通过在局部微环境下的再编程参与心肌损伤、心肌细胞再生与心肌功能重塑三个阶段。阐明巨噬细胞在心肌炎局部微环境下的再编程机制是有效控制和延缓心肌损伤的重要途径。本项目在前期研究的基础上，明确巨噬细胞再编程在EAM小鼠受损心肌组织修复中的作用，分析心肌细胞释放的Reg3β对EAM小鼠心肌浸润巨噬细胞再编程及分泌HMGB1的影响和机制，并探讨再编程巨噬细胞分泌的HMGB1对心肌细胞去分化、增殖及Reg3β释放的影响和机制。研究结果表明在心肌炎症损伤期，巨噬细胞在炎症因子刺激下分化为 M1 型巨噬细胞，活化的 M1 型巨噬细胞通过分泌DS-HMGB1促进损伤心肌细胞释放Reg3β；Reg3β通过激活STAT6信号通路，促进巨噬细胞由M1型向M2型再编程；M2型巨噬细胞分泌FR-HMGB1，通过激活AKT、ERK等信号通路，促进心肌细胞增殖和去分化，从而形成Reg3β-HMGB1正反馈环路，调控巨噬细胞再编程，参与受损心肌修复。本项目研究结果为全面了解巨噬细胞在心肌炎发生和转归过程中的作用奠定基础，也为临床治疗心血管疾病提供新的思路和靶点。