Microglial Interferon Signaling and Ischemic Preconditioning

描述（由申请人提供）：脑中的缺血预处理（IPC）是一种强大的神经保护现象，其中短暂的缺血暴露增加了对随后长时间缺血损伤作用的抵抗力。描述IPC的细胞和分子机制是卒中研究的一个活跃领域。小胶质细胞是大脑中的特化组织巨噬细胞，在神经炎症反应和包括中风在内的许多神经系统疾病中发挥重要作用。几条证据支持小胶质细胞在IPC中的作用。小胶质细胞表达Toll样受体（TLR），其介导对外源性和内源性激动剂的强大免疫应答。TLR 4是IPC诱导的神经保护所必需的。为了阐明小胶质细胞TLR 4参与IPC的机制，我们对暴露于体外缺血条件或体内IPC的小胶质细胞进行了细胞靶向基因组分析。来自两个数据集的结果鉴定了1型和/或3型干扰素（IFN）刺激的基因（ISG）的稳健表达作为缺血暴露的WT的主要转录组特征，而不是TLR 4-/-小胶质细胞。细胞因子的IFN家族被认为是对感染的先天免疫应答的关键组分。最近的研究表明，小胶质细胞IFN信号是非感染性机制诱导的损伤反应的重要调节因子。本提案的重点是使用体外（缺氧/低血糖治疗原发性小胶质细胞）和体内（大脑中动脉闭塞/再灌注）实验模型来表征1型和3型IFN在介导IPC现象和小胶质细胞对缺血的反应中的作用。

DESCRIPTION (provided by applicant): Ischemic preconditioning (IPC) in the brain is a robust neuroprotective phenomenon in which a brief ischemic exposure increases resistance to the injurious effects of subsequent prolonged ischemia. Characterizing the cellular and molecular mechanisms of IPC is an active area of investigation in stroke research. Microglia, the brain's specialized tissue macrophages, play a major role in the neuroinflammatory response and in many neurological diseases including stroke. Several lines of evidence support a role for microglia in IPC. Microglia express Toll-like receptors (TLRs) that mediate powerful immune responses to exogenous and endogenous agonists. TLR4 is required for IPC-induced neuroprotection. In order to elucidate the mechanisms by which microglial TLR4 contributes to IPC, we carried out cell-targeted genomic analyses specifically on microglia exposed to either ischemic conditions in vitro or IPC in vivo. Results from both datasets identified robust expression of type 1 and/or type 3 interferon (IFN)-stimulated genes (ISGs) as the predominant transcriptomal feature of ischemia-exposed WT, but not TLR4-/-, microglia. The IFN family of cytokines is recognized as a key component of the innate immune response to infection. Recent work has implicated microglial IFN signaling as an important regulator of the injury response induced by non-infectious mechanisms. The focus of this proposal is to characterize the role of type 1 & 3 IFNs in mediating the IPC phenomenon and the microglial response to ischemia using both in vitro (hypoxia/hypoglycemia treatment of primary microglia) and in vivo (middle cerebral artery occlusion/reperfusion) experimental models.