消退素D1对脑缺血损伤后小胶质细胞激活的调节作用及机制研究

Inflammation has been increasingly recognized as a key contributor to the pathophysiology of cerebral ischemic injury, and increasing evidence suggests that microglial activation is a key causative factor in this process. It is becoming more widely accepted that although microglial activation is necessary and crucial for host defence and neuron survival, the overactivation of microglia results in deleterious and neurotoxic consequences. Therefore, the ideal therapeutic approach would involve early attenuation of the microglial response to levels that are no longer deleterious, rather than the elimination of the microglial response altogether. Inflammation is a double-edged sword. Most therapeutic interventions of neuroinflammation have traditionally targeted primarily mediator pathways that are engaged at the onset of inflammation. Counteracting the inflammatory response to ischemic injury may ameliorate the tissue damage in the acute phase, but it may compromise repair mechanisms, worsen the long-term outcome of the injury and drive the progressive nature of neurodegenerative disease.Increasing evidence suggests that resolution of inflammation is not a passive process, but is an active process controlled by endogenous anti-inflammatory and pro-resolution mediators. The factors governing resolution of inflammation and the re-establishment of tissue homeostasis are still poorly understood, particularly in brain. Resolvins(Rvs) are recently identified molecules that are generated from ω-3 PUFA precursors and can orchestrate the timely resolution of inflammation in model systems. In our previous study, we found that ALXs, the receptors of RvD1, were expressed in BV-2 microglial cells and the mRNA expression levels of ALXs were significantly enhanced when the cells were exposed to LPS. We also found that RvD1 inhibited LPS-induced protein expression of iNOS and the DNA binding activity of NF-κB. Therefore, this study is to investigate the effects of RvD1 on the neurologic impairment, the dynamic change of inflammatory response in the pathologic processes of cerebral ischemia-reperfusion and microglial activation induced by cerebral ischemia-reperfusion injury in vivo and in vitro, as well as the signaling pathways involved in these processes. It will provide theoretical basis for further research on Rvs for prevention and treatment of cerebralvascular disease.

脑缺血性疾病严重威胁人类的健康和生命。以小胶质细胞激活为特征的神经炎症在脑缺血损伤的发生发展中起关键作用。探索小胶质细胞激活的调节机制有重要意义。当前针对神经炎症的治疗策略主要是抑制炎症启动与发生，虽可延缓炎症发展，但也削弱了炎症的保护作用，甚至使炎症慢性化、导致慢性神经退行性疾病。炎症在发生的同时即启动了自身的消退，适时促进炎症消退是更为合理的治疗策略。消退素（resolvins，Rvs）是由ω-3不饱和脂肪酸衍生的内源性抗炎、促炎症消退介质。我们初步发现，小胶质细胞表达消退素D1（RvD1）受体ALX；RvD1可抑制激活小胶质细胞iNOS表达及NF-κB转录活性。因此本项目拟从"促炎症消退"角度，采用脑缺血再灌注在体和离体模型，探讨RvD1对脑缺血后神经功能损伤及炎症动态演变规律的影响；对小胶质细胞激活后生物学功能的调节及其可能的信号机制，为进一步探索Rvs防治脑血管疾病提供理论依据。

以小胶质细胞激活为特征的神经炎症在各种神经退行性疾病的发生发展中起关键作用。当前针对神经炎症的治疗策略主要是抑制炎症启动与发生。消退素（resolvins，Rvs）是由ω-3不饱和脂肪酸衍生的内源性抗炎、促炎症消退介质。促进炎症消退为防治急慢性神经退行性疾病提供了一种新策略。因此本项目从“促炎症消退”角度，采用脑缺血再灌注在体和离体模型，探讨RvD1对脑缺血后神经功能损伤及炎症反应影响；对小胶质细胞不同激活状态的调控及其可能的信号机制；采用烧伤模型探讨RvD1对大鼠烧伤后机械缩足反应阈值、脊髓背角胶质细胞活化、p38 MAPK磷酸化的影响。本课题研究发现RvD1可降低大鼠脑缺血再灌注后神经功能缺陷评分、减少脑梗死体积，减轻脑水肿和血脑屏障功能损伤，可能与其抑制小胶质细胞的激活、减轻脑组织炎症反应有关。离体研究发现RvD1可促进IL-4诱导的小胶质细胞M2极化，其机制可能与增强STAT6磷酸化、细胞核内PPARγ表达以及STAT6和PPARγ的DNA结合活性有关。本研究还发现RvD1可降低烧伤后大鼠机械缩足反应阈值，其机制可能与RvD1抑制脊髓背角胶质细胞活化、降低p38 MAPK磷酸化有关。本课题证实RvD1减轻脑缺血再灌注及烧伤后的神经炎症，为进一步探索Rvs防治神经炎症性疾病提供理论依据。