α7尼古丁乙酰胆碱受体抗炎通路在高血压心脏重塑中保护作用及机制

Hypertension leads to cardiac remodeling, including hypertrophy and fibrosis. Our previous studies demonstrated that inflammation play a pivotal role in development of hypertensive cardiac remodeling. Our preliminary results revealed that α7nAchR dominantly expressed on infiltrated macrophages; α7nAchR knockout aggravated hypertensive cardiac remodeling; α7nAchR deficiency promote MHC II gene expression and antigen-presenting function in macrophage utilizing RNA-sequencing technology. However, the underlying mechanism is unclear. The goal of this study is to determine how α7nAchR modulates MHC II gene expression in macrophage and how macrophage-derived α7nAchR regulates activation of cardiac fibroblasts and hypertrophy of cardiomyocytes. Our specific aims are: 1) to determine the effect of α7nAchR on the hypertension-induced cardiac injury and remodeling and target cell; 2) to explore the molecular mechanisms by which α7nAchR affects MHC II gene transcription; 3) to elucidate the biological properties of α7nAchR-deficient macrophages; 4) to determine how α7nAchR affects cell-cell interaction between macrophages and fibroblasts, and between macrophages and cardiomyocytes. Finally, the present study will demonstrate the important role of macrophage-derived α7nAchR and provide novel molecular insights into the pathogenesis of hypertensive cardiac remodeling and a potential therapeutic target.

炎症失衡是高血压心脏重塑的重要环节，α7尼古丁乙酰胆碱受体(α7nAchR)介导内源性抗炎通路。我们前期发现α7nAchR缺失加剧高血压心脏重塑，分选高血压刺激下WT和α7nAchR-/-小鼠心脏巨噬细胞，mRNA转录组测序发现α7nAchR缺失促进MHCII类分子表达和抗原递呈功能，提示α7nAchR可能通过调控巨噬细胞抗原递呈影响高血压心脏重塑。本课题将利用高血压动物模型、α7nAchR敲除鼠、α7nAchR拮抗剂/激动剂、骨髓交互移植、巨噬细胞回输\敲除、细胞共培养等技术，拟阐明在高血压环境下：（1）α7nAchR抗炎通路如何抵抗心脏损伤\重塑发生；（2）α7nAchR如何调控巨噬细胞MHCII类分子表达和抗原递呈功能，影响CD4 T细胞活化；（4）α7nAchR如何调节巨噬细胞分化、分泌，影响成纤维细胞活化和心肌细胞肥厚。明确高血压心脏重塑中α7nAchR抗炎通路的保护作用及机制。

炎症反应在高血压形成及心脏重塑中有重要作用，高血压心脏重塑的发生伴随大量炎性细胞浸润和炎症因子表达，其中巨噬细胞在高血压心脏炎症反应中起到非常重要作用。神经-内分泌-免疫调节网络是重要的免疫调节方式之一，其中由副交感神经调节的“胆碱能抗炎通路”能够抑制多种炎症疾病，并且已有研究证明α7nAchR是“胆碱能抗炎通路”的核心分子。我们研究发现α7nAChR在高血压模型小鼠心脏内巨噬细胞表达最高，α7nAChR基因敲除加剧Ang II（灌注）和压力过负荷（主动脉弓缩窄）介导的心脏炎症，心肌肥厚和心脏纤维化。通过分析α7nAChR-/-和野生小鼠高血压心脏中浸润巨噬细胞的基因表达谱，发现α7nAChR-/-巨噬细胞中上调差异显著基因为主要组织相容性复合物（MHC）II类分子。巨噬细胞的α7nACh受体激活能促进KLF4入核，入核的KLF4与多个MHCII分子的启动子结合，抑制其转录表达，从而抑制炎症反应。使用巨噬细胞特异性敲除klf4小鼠（klf4flox/flox-lysm-cre）进行AngII灌注，实验结果与α7nAChR-/-小鼠相同，特异性敲除klf4小鼠加重AngII灌注介导心脏炎症反应，纤维化和心衰。通过光遗传学方式，使用特异性感染胆碱能神经元的光病毒（rAAV-CHAT-cre-WPRE-PA）感染迷走神经背侧运动核（DMNV）。调制刺激参数（10HZ,20min,15mV），与SHAM组相比，光刺激组外周血清和心脏组织中乙酰胆碱（ACH）含量增多，并且显著减轻TAC介导的心脏炎症反应，纤维化和心衰。