消退素D1激活小胶质细胞自噬减轻神经元缺血炎性损伤的机制研究

Inflammatory response after the cerebral ischemia accelerates the neuronal injury，which could induce neuronal apoptosis and develop into inflammatory cascade, leading to secondary damage to neurons. A large number of studies indicate that activation of microglial autophagy could ameliorate inflammatory response. Resolvin D1 could induce the secretion of microglial anti-inflammatories as well as the pro-resolution function of microglia. Our preliminary research confirmed that resolvin D1 could activate microglial autophagy. Therefore, we hypothesize that by activating microglial autophagy, resolvin D1 ameliorate inflammatory response, through which it ameliorates neuronal injury following cerebral ischemia. Firstly, this project would focus on the activation of microglial autophagy by resolvin D1 and its related pathway. Secondly, we would investigate the signal crosstalk between inflammatory response pathway and autophagy pathway of microglia during ischemic injury. Lastly, we will explore the effects on the amelioration of cerebral ischemic inflammatory injuries induced by activation of microglial autophagy by resolvin D1 following knocking out the key gene of autophagy. The accomplishment of our project would clarify the effects and mechanisms of resolvin D1 on ameliorating cerebral ischemic inflammatory injuries by activating microglial autophagy, which lays the experimental and theoretical foundation for the application of resolvin D1 on the therapy for cerebral ischemic stroke.

脑缺血后的炎症反应加重了脑缺血所致的神经元损伤，可诱发神经元凋亡，形成炎症级联反应，造成对神经元的二次打击。大量研究显示小胶质细胞自噬激活可减轻炎症反应。消退素D1具有诱导小胶质细胞分泌抗炎物质及促进炎症消退的作用。我们的前期工作证实，消退素D1可激活小胶质细胞自噬。因此，提出研究假设：消退素D1通过激活小胶质细胞自噬，减轻脑缺血后的炎症反应，进而减轻脑缺血所致神经元损伤。本课题首先拟研究消退素D1对小胶质细胞自噬的激活作用及其通路。其次，拟探究缺血缺氧性损伤中小胶质细胞炎症反应通路及自噬通路的信号交叉对话。最后，拟探讨敲除小胶质细胞自噬关键基因对消退素D1激活小胶质细胞自噬改善脑缺血炎性损伤的影响。本课题的完成将明确消退素D1激活小胶质细胞自噬减轻脑缺血炎性损伤的作用及其机制，为消退素D1在缺血性脑卒中治疗中的应用奠定实验和理论基础。

小胶质细胞激活引发的神经炎症是焦虑抑郁行为的重要发病机制。消退素D1（Resolvin D1, RvD1）是具有强大抗炎效应的内源性脂质介质。近年的研究显示，自噬在神经炎症的调控方面有重要作用。然而，RvD1抑制炎症反应的效应是否受到小胶质细胞自噬的调控仍不明确。本研究探索了RvD1对小胶质细胞自噬的激发效应及相应通路，并探讨了RvD1诱导的小胶质细胞自噬在神经炎症中的作用。研究结果显示，RvD1通过促进自噬小体成熟及与溶酶体的融合激发小胶质细胞自噬。重要的是，RvD1对mTOR信号通路无明显作用。RvD1可抑制钙内流及钙离子-钙调蛋白激酶激活（CaMKII）更进一步验证了RvD1激发的自噬为非mTOR依赖型。通过下调ATG5，我们证实RvD1对自噬和吞噬的激活受到ATG5的调控。本研究同时也揭示了RvD1可激活被LPS刺激所抑制的小胶质细胞自噬。RvD1处理可通过阻遏小胶质细胞NF-κB核转位有效抑制炎症反应。RvD1在离体与在体实验中均表现出减轻神经毒性的效应。RvD1给药后可显著减轻LPS刺激小鼠的抑郁行为。值得注意的是，RvD1的上述效应可被3-MA消除，提示小胶质细胞自噬的调控。总之，我们的研究为小胶质细胞自噬在神经炎症中所扮演的角色提供了全新的视角，并突出了RvD1作为一种有潜力的试剂，在神经炎症所诱发的抑郁治疗方面所具有的的潜在优势。