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) 导致高死亡率和发病率，但对此的研究尚未充分 与缺血性中风相比，缺乏有效的治疗方法。血肿体积和扩张更大 与不良的患者预后独立相关；因此，快速清除有毒血液可以限制ICH- 诱发脑损伤。此外，小胶质细胞和巨噬细胞 (M/MΦ) 在 ICH 后改变活动状态以消除 有毒的血液，可能会保护大脑。然而，过度激活的 M/MΦ 会导致继发性脑损伤 释放细胞毒性物质。这些相反的影响可能是由不同的 M/MΦ 子集造成的，这些子集是 分为经典激活的促炎剂（M1）和替代激活的抗炎剂（M2） 细胞。另一种激活的 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 CD36 的激活和其负调节因子 Toll 样受体 (TLR) 的抑制 4. 重要的是，白细胞介素 10 (IL-10) 是一种抗炎细胞因子，可抑制炎症、极化 巨噬细胞转变为 M2c 亚型，并增强吞噬作用。 ICH 患者的 IL-10 水平升高 存在于血液和脑组织中。然而，M/MΦ 极化的程度和时间以及 IL-10 的确切作用 ICH 后 M2 极化中的信号传导尚不清楚。我们研究的长期目标是限制 ICH 损伤并 改善功能结果。该 R01 的总体目标是研究 M/MΦ 的调制是否 IL-10 的表型和功能可减少 ICH 损伤并改善组织学和功能结果。我们的 初步研究表明，暴露于血红蛋白和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的吞噬作用和 CD36 表达 文化； IL-10 缺陷小鼠血肿消退受损，CD36 和 TLR4 表达发生改变 与C57BL/6野生型小鼠相比；外源性 IL-10 成功减少了血肿体积。这些 研究结果提出了这样的假设：IL-10 将 M/MΦ 极化为 M2 表型可减少 ICH 损伤并改善 ICH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的吞噬作用 （目标 1）； IL-10 引起的 M2 M/MΦ 极化是否可以改善体内 ICH 后的组织学和功能结果 （目标 2）； IL-10 诱导 M/MΦ M2 极化是否需要激活 CD36 并抑制 TLR4 （目标 3）。从这项研究中获得的信息将为我们提供对 M/MΦ 极化后的新见解 ICH 以及 IL-10 信号诱导 M/MΦ M2 极化的细胞和分子机制 减少 ICH 损伤。基于多学科方法，我们的研究结果将有可能带来一种新的治疗方法 不仅针对 ICH，还针对其他脑部疾病。这项新颖的概念验证工作旨在研究调制 M/MΦ 极化的研究是最近的 NINDS-SPRG 确定的一个关键优先事项。

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.