α7-nAChR调节心脏c-Kit+干细胞的内皮-间质转化作用及机制

Cardiac c-Kit+ stem cells (CSC) has the main potential to differentiate into endothelial cells. The numbers of CSC were increased in process of heart failure attributed to heart pressure overload and myocardial infarction in animal and human, however, the progressive cardiac fibrosis resulting in heart failure increased continuously, which could be associated with the decreased expression of ChAT and α7-nAChR in CSC, and myofibroblast differentiation of CSC as indicated in our preliminary study. Thus, it is proposed that "ACh/α7-nAChR regulates CSC endothelial-mesenchymal transition (EndMT) to couple structure and function in heart". The study will focus on the relationship between endogenous ACh-mediated α7-nAChR activation and differentiation of CSC into endothelial cells to explore whether the changes of EndMT in CSC are related to cardiovascular disease under physiological and pathological conditions, uncover the interaction among PI3K-AKT-Stat3 and Smad2/3-SP1/FOXO1 activated by ACh/α7-nAChR in the regulation of EndMT changes of CSC with HGF/c-Met, establish a new mechanism of the occurrence and development of heart failure resulting from the involvement of CSC in abnormal EndMT, and using α7-nAChR agonist to evaluate the relationship between the reversed EndMT of CSC and the improvement of heart failure based on the view.

心脏c-Kit+干细胞(CSC)呈现内皮细胞特性，病理条件下其数目增多，但为何心脏进行性纤维化，心脏走向衰竭，发现与CSC向肌成纤维细胞转化及其ChAT及α7-nAChR表达降低有关。为此,提出“ACh/α7-nAChR调节CSC内皮-间质转化作用（EndMT）而影响心脏的结构与功能”科学假说。本工作拟以CSC内源性的ACh对α7-nAChR激活作用及其与分化特性的关联为切入点，探索其在生理及病理条件下心脏c-Kit+干细胞EndMT变化与心血管疾病的关联，阐明ACh/α7-nAChR激活的PI3K-AKT-Stat3与Smad2/3-SP1/FOXO1在调节EndMT变化时与HGF/c-Met的关联机制，试图建立一种心衰发生发展的新机制即：CSC通过EndMT而参与心衰的发生发展，并以此评价α7-nAChR激动剂在逆转心脏c-Kit+干细胞EndMT的作用及对心衰的治疗价值。

心脏c-Kit+干细胞(CSC)呈现内皮细胞特性，病理条件下其数目增多，但为何心脏进行性纤维化，心脏走向衰竭，发现与CSC向肌成纤维细胞转化及其ChAT及α7-nAChR表达降低有关。为此,提出“ACh/α7-nAChR调节CSC内皮-间质转化作用（EndMT）而影响心脏的结构与功能”科学假说。本工作发现：1)血管外膜干细胞、肌干细胞表达c-Kit，且表达α7-nAChR。压力超负荷或心梗模型心脏c-kit阳性细胞分化为肌成纤维细胞，利用血管紧张素-II复制纤维化模型，发现敲低c-kit细胞乙酰胆碱转移酶（ChAT）及α7nAChR后，纤维化显著加重，且心脏功能衰竭更明显。该过程与FoxO1等信号通路有关。2）筛选出新的靶点：RGC32、S100B、Meox1、KPC1等。RGC32通过调节血管平滑肌细胞α1-AdR而调节血管收缩性影响血压稳态，S100B通过NF-KB调节血管外模干细胞中间态而影响血管狭窄，KPC1通过影响心肌细胞缺血再灌注时Bax稳定性而调节其凋亡；3) 建立独特体外模型即：连续给予去甲肾上腺素、肾上腺素、异丙肾上腺素刺激，抑制了肌干细胞分化、融合，显著减少了慢肌纤维比例。该过程与ERK1/2-FoxO1等信号通路有关。尤其发现乙酰胆碱能取消去甲肾上腺素等介导的抑制效应；4)电刺激迷走神经（VNS）通过释放的乙酰胆碱(ACh)通过/nACh-R/PI3K/Akt/Sp1途径诱导VEGF-A /B表达促进血管新生和动脉生成，同时通过FoxO3a优化了心肌细胞类型、肌节结构及其糖脂代谢功能，从而修复梗死心脏。总之，这些研究为临床基于为基于Ach-α7nAChR靶标防治心衰提供新的理论依据和临床策略。