脑缺血后星形胶质细胞分泌的外泌体介导miR-132对新生血管重构的调控机制实验研究

In recent years, the research of ischemic stroke mainly focuses on neuron protection and regeneration, while little attention has been paid to vascular remodeling during the repair of ischemic brain tissue. In our previous work, we found that although there was neovascularization after cerebral ischemia, it was in a disordered and hypoperfusion state. We also found that the level of microRNA-132 in the supernatant exosome of mouse astrocytes increased after oxygen-glucose deprivation test. As a basic mechanism of nervous system communication, exosomes maintain homeostasis and plasticity in the brain, and microRNA-132 is closely related to cerebrovascular integrity. Previous work has also found that microRNA-132 can promote the formation of vascular network in brain endothelial cells and correct the loss of tight junction protein caused by oxygen and glucose deprivation. This suggests whether astrocytes can regulate the remodeling of neovascularization through secreted exosomes mediated by microRNA-132 after cerebral ischemia. Does increasing the expression of microRNA-132 in its exosome play a therapeutic role? No relevant reports have been reported all around the world. Whether astrocytes act as neurovascular pathways through exosomes after cerebral ischemia, the optimal concentration of astrocytes and whether microRNA-132 is the key role are the scientific issues to be solved urgently. To elucidate this mechanism will certainly provide important theoretical basis for clinical treatment of cerebral ischemia.

近年来缺血性卒中的研究主要集中在神经元保护、再生等方面，而对缺血脑组织修复期血管重构关注极少。前期工作中我们发现尽管脑缺血后有新生血管生成，但却处于无序且低灌注状态。我们还发现氧糖剥夺实验后小鼠星形胶质细胞上清外泌体中miR-132升高。外泌体作为神经系统沟通的一种基本机制维持大脑内稳态和可塑性，且miR-132与脑血管完整性密切相关。前期工作我们还发现miR-132能促进脑内皮细胞形成血管网，能纠正由氧糖剥夺引起的紧密连接蛋白缺失。这提示我们脑缺血后星形胶质细胞是否能通过分泌的外泌体介导miR-132对新生血管重构发挥调控作用？增加其外泌体miR-132的表达是否能起治疗作用？国内外未见相关报道。那么①脑缺血后星形胶质细胞是否通过外泌体作为神经血管的作用途径，②其最适作用浓度，③miR-132是否为作用关键是我们亟待解决的相关科学问题。阐明这一机制，必将为临床治疗脑缺血提供重要理论依据。

距今为止人类对脑卒中的认识已经从仅仅是血管病变扩展到脑内神经胶质、神经元、内皮细胞和基质间有害成分的相互作用。脑缺血后，星形胶质细胞可在数分钟内被激活，产生促炎介质和细胞因子，导致多种炎症细胞浸润到缺血区，加重脑损伤。MiR-132可以参与细胞生物学过程，包括神经发育及炎症。TRAF6在不同信号的刺激下，协调多种信号分子介导并激活NF-κB信号通路，从而在包括免疫应答在内的众多生命活动中发挥了重要的功能。本课题中，运用OGD和pMCAL，在星胶细胞与小鼠脑内，通过转染过表达miR-132，分析了miR-132与TRAF6之间的作用关系及对缺血后炎性损伤的影响。通过三年的研究我们证实了小鼠脑缺血后星形胶质细胞中miR-132表达上调；发现了MiR-132能够在3’UTR端负向调节TRAF6；证明了MiR-132能够通过负向调控TRAF6改善OGD诱导的小鼠星形胶质细胞炎症反应; 证明了MiR-132能够通过负向调控TRAF6改善OGD诱导的小鼠星形胶质细胞凋亡情况；阐明了miR-132通过作用TRAF6下调OGD后的星型胶质细胞炎性通路NF-kB的机制。项目研究过程中，发表SCI收录文章3篇，核心期刊文章1篇，培养研究生3人。