小胶质细胞通过NF-κB/MFG-E8通路介导吞噬脑缺血后应激神经元的机制研究

It is very important to reduce the loss of neurons after cerebral ischemia for the recovery of brain function in patients with cerebral infarction. Activated microglia can engulf stressed viable neurons and result in delayed neuronal death. However, the mechanisms of delayed neuronal loss are poorly understood in the infarction surrounding area after cerebral ischemia. Our previous study found that NF-κB inhibitor can significantly reduce the loss of neurons by inhibiting the activation of microglia. Further experiments suggested that inhibition of NF-κB may regulate microglial phagocytosis through MFG-E8. Accordingly, we suppose that delayed neuronal loss may be associated with microglial phagocytosis function regulated by NF-κB after cerebral ischemia. To observe the changes of microglial phagocytosis and secretion functions by the regulation of NF-κB after ischemia and hypoxia, this project intends to further explore the mechanisms with several experimental techniques, such as cell-specific gene knockout, gene transfection, RNA interference, immunofluorescent labeling, two-photon laser confocal microscope, flow cytometry, and so on. The project aims to clarify the role of NF-κB/MFG-E8 in microglia phagocytosis and its mechanism of regulation after cerebral ischemia and provide new avenues for the treatment of ischemic stroke.

减少脑缺血后神经元的丢失，对脑梗死患者脑功能恢复非常重要。目前认为活化的小胶质细胞可以吞噬处于应激状态的活神经元，导致神经元延迟性死亡。梗死灶周围区，处于应激状态神经元的延迟性丢失的具体作用机理还不清楚。我们前期研究发现：采用NF-κB阻断剂可明显抑制小胶质细胞的激活，显著减少延迟性神经元的丢失。进一步实验提示，抑制NF-κB可能通过MFG-E8调节小胶质细胞吞噬发挥作用。据此我们推测：脑缺血后，延迟性神经元丢失可能与NF-κB调控的小胶质细胞吞噬功能有关。本研究拟进一步采用细胞特异性基因敲除、基因转染、RNA干扰、免疫荧光标记、双光子激光共聚焦显微镜和流式细胞仪等技术；调控NF-κB观察缺血缺氧后小胶质细胞的吞噬和分泌功能的改变；明确NF-κB/MFG-E8在缺血缺氧后小胶质细胞吞噬处于应激状态的活神经元的调节作用及其机制，为缺血性脑卒中的治疗提供新途径。

小胶质细胞炎症反应是神经炎症的源头，吸入麻醉药导致神经元损伤，受损的神经元释放SAP130激活小胶质细胞Mincle受体及下游syk/CARD9信号通路，从而导致小胶质细胞炎症反应，从而加重神经元损伤，该环节可能是治疗神经炎症相关损伤的关键靶点。我们进一步通过研究吸入麻醉药在小胶质细胞NLRP3炎性小体通路中的调控机制，首次发现异氟醚仅参与NLRP3炎性小体通路的激活步骤，对NLRP3炎性小体未预先启动表达的情况无促进炎症因子IL-1β表达的作用，可为进一步探索预防和治疗全麻药物引起的认知功能障碍提供新线索。