Microglia/macrophage polarization after intracerebral hemorrhage

项目概要： 脑出血后小胶质细胞/巨噬细胞极化 自发性脑出血（ICH）是一种高死亡率和高致残率的疾病，但目前对其研究尚不充分 与缺血性中风相比，缺乏有效的治疗。更大的血肿体积和扩张是 与不良患者结局独立相关;因此，快速清除有毒血液可限制ICH- 导致脑损伤。此外，小胶质细胞和巨噬细胞（M/MΦ）在ICH后改变活性状态， 有毒的血液，可以保护大脑。然而，过度激活的M/MΦ通过以下方式引起继发性脑损伤： 释放细胞毒性物质。这些相反的作用可能是由不同的M/MΦ亚群引起的， 分为经典活化的促炎（M1）和交替活化的抗炎（M2） 细胞另外，活化的M2巨噬细胞表现出对凋亡细胞的吞噬作用增加，这可能 涉及清道夫受体CD 36的激活及其负调节因子Toll样受体（TLR）的抑制 4.重要的是，白细胞介素-10（IL-10），一种抗炎细胞因子，抑制炎症，极化 巨噬细胞转化为M2 c亚型，并增强吞噬作用。ICH患者IL-10水平升高 在血液和脑组织中然而，M/MΦ极化的程度和时间以及IL-10的确切作用尚不清楚。 ICH之后M2极化中的信令是未知的。我们研究的长期目标是限制脑出血损伤， 改善功能结果。本R 01的总体目标是研究M/MΦ的调节是否 表型和功能的IL-10减少ICH损伤，并改善组织学和功能的结果。我们 初步研究表明，暴露于血红蛋白的脑切片培养物中IL-10表达增加， 在ICH体内模型中，IL-10增加脑切片中小胶质细胞吞噬作用和CD 36表达 IL-10缺陷小鼠血肿消退受损，CD 36和TLR 4表达改变 与C57 BL/6野生型小鼠相比，外源性IL-10成功地减少了血肿体积。这些 这些发现提示了IL-10将M/MΦ极化为M2表型可减少ICH损伤， 脑出血后组织学和功能恢复。在三个具体目标中，我们将确定M2小胶质细胞是否 IL-10的极化负责暴露于血液成分的离体脑切片培养物中的吞噬作用 (Aim 1）; IL-10引起的M2 M/MΦ极化是否改善了体内ICH后的组织学和功能结局 (Aim IL-10诱导M/MΦ M2极化是否需要激活CD 36和抑制TLR 4 (Aim 3）。从这项研究中获得的信息将为我们提供新的见解M/MΦ极化后， 脑出血与IL-10信号诱导M/MΦ M2极化的细胞和分子机制 减少ICH损伤。基于多学科的方法，我们的研究结果可能会导致一种新的治疗方法， 这不仅适用于ICH，也适用于其他脑部疾病。这一新颖的概念验证工作，研究调制 M/MΦ极化的最新进展是由NINDS-SPRG确定的关键优先事项。

PROJECT SUMMARY: Microglia/macrophage polarization after intracerebral hemorrhage Spontaneous intracerebral hemorrhage (ICH) causes high mortality and morbidity, but it is understudied compared to ischemic stroke and lacks effective treatment. Greater hematoma volume and expansion are independently associated with poor patient outcomes; therefore, rapid removal of toxic blood could limit ICH- induced brain injury. Additionally, microglia and macrophages (M/MΦ) shift activity states after ICH to remove toxic blood and may protect the brain. However, over-activated M/MΦ cause secondary brain damage by releasing cytotoxic substances. These opposing effects may result from distinct M/MΦ subsets, which are categorized into classically activated proinflammatory (M1) and alternatively activated anti-inflammatory (M2) cells. Alternatively activated M2 macrophages exhibit increased phagocytosis of apoptotic cells, which could involve activation of the scavenger receptor CD36 and inhibition of its negative regulator, toll-like receptor (TLR) 4. Importantly, interleukin-10 (IL-10), an anti-inflammatory cytokine, represses inflammation, polarizes macrophages to an M2c subtype, and enhances phagocytosis. Patients with ICH have elevated levels of IL-10 in blood and brain tissue. However, the extent and timing of M/MΦ polarization and the exact role of IL-10 signaling in M2 polarization after ICH are unknown. The long-term goal of our research is to limit ICH injury and improve functional outcomes. The overall objective of this R01 is to investigate whether modulation of M/MΦ phenotype and function by IL-10 reduces ICH injury and improves histologic and functional outcomes. Our preliminary studies showed that IL-10 expression increases in brain slice cultures exposed to hemoglobin and in an in vivo model of ICH; that IL-10 increases microglial phagocytosis and CD36 expression in brain slice cultures; that IL-10-deficient mice have impaired hematoma resolution and altered CD36 and TLR4 expression compared to C57BL/6 wild-type mice; and that exogenous IL-10 successfully reduces hematoma volume. These findings prompt the hypothesis that polarizing M/MΦ to M2 phenotype by IL-10 reduces ICH injury and improves histologic and functional recovery after ICH. In three specific aims, we will determine whether M2 microglial polarization by IL-10 is responsible for phagocytosis in ex vivo brain slice cultures exposed to blood components (Aim 1); whether M2 M/MΦ polarization by IL-10 improves histologic and functional outcomes after ICH in vivo (Aim 2); and whether IL-10 induction of M/MΦ M2 polarization requires activation of CD36 and inhibition of TLR4 (Aim 3). The information gained from this study will provide us with novel insight into the M/MΦ polarization after ICH and the cellular and molecular mechanisms by which IL-10 signaling–induced M/MΦ M2 polarization reduces ICH injury. Based on multidisciplinary approaches, our findings will potentially lead to a new therapeutic strategy not only for ICH but also for other brain disorders. This novel proof-of-concept work to study modulation of M/MΦ polarization is a critical priority identified by the recent NINDS-SPRG.