NOX2 drives microglia-dependent neurodegeneration after traumatic brain injury

项目概述：创伤性脑损伤触发延迟性分子继发性损伤级联反应，包括 慢性神经炎，导致进行性组织丢失和神经损伤，包括 认知缺陷。重型颅脑损伤后伴有持续小胶质细胞激活的慢性神经炎 并被认为会导致随后的神经退行性变和神经损伤。因此，目标是 小胶质细胞的激活可能为脑外伤患者提供新的治疗靶点。我们之前的研究已经探索了 颅脑损伤后功能障碍的小胶质细胞的发展：1)慢性炎性小胶质细胞 在实验性脑损伤后激活长达一年，导致神经退化和认知能力下降；2) NADPH氧化酶(NOX2)在慢性小胶质细胞介导的神经毒性中起关键作用；3)暂时性衰竭 使用CSF1R抑制剂(PLX5622)引起脑小胶质细胞重编程和表型转变 慢性促炎症状到表达减少的炎症标志物的更具恢复性的表型， 包括NOX2，并减弱长期的运动和认知障碍。在本提案中，我们的目标是利用 突破性的单细胞rna-seq分析研究了以下独特的小胶质细胞亚群 有针对性地删除NOX2。此外，我们还将研究这些基因的转录签名 在慢性损伤的大脑中调节神经修复特性的小胶质细胞亚群。重要的是，这 提案将研究NOX2在非小胶质细胞巨噬细胞样细胞中的作用，包括边界相关细胞 巨噬细胞(BAMS)和循环单核细胞在介导神经炎性反应和神经系统中的作用 下降，跟随着TBI。具体目标包括：1)阐明再种群诱导小胶质细胞的机制 与脑外伤后减轻的促炎、神经毒性表型相关的重编程；2)确定 小胶质细胞NOX2在颅脑损伤后神经炎症/神经退行性变中的作用；3)探讨BAM的作用 NOX2在颅脑损伤后神经炎症/神经变性中的作用；4)评估循环单核细胞的作用 NOX2在颅脑损伤后神经炎症/神经变性中的作用理解驱动的分子机制 小胶质细胞和非小胶质细胞巨噬细胞样细胞极化向神经修复状态将是至关重要的 解锁小胶质细胞/巨噬细胞在慢性期促进修复的内源性潜力 颅脑损伤后恢复。

Project Summary: Traumatic brain injury (TBI) triggers delayed molecular secondary injury cascades, including chronic neuroinflammation, that contribute to progressive tissue loss and neurological impairments, including cognitive deficits. Chronic neuroinflammation with sustained microglial activation occurs following severe TBI and is believed to contribute to subsequent neurodegeneration and neurological impairments. Thus, targeting microglial activation may offer novel therapeutic targets for TBI patients. Our previous studies have probed the development of dysfunctional microglia after TBI and shown that: 1) pro-inflammatory microglia are chronically activated up to one year following experimental TBI, contributing to neurodegeneration and cognitive decline; 2) NADPH oxidase (NOX2) plays a critical role for chronic microglial-mediated neurotoxicity; 3) temporary depletion of brain microglia using a CSF1R inhibitor (PLX5622) causes microglial reprograming and phenotypic shift from a chronic pro-inflammatory profile to more restorative phenotypes that express reduced inflammatory markers, including NOX2 , and attenuate long-term motor and cognitive deficits. In the present proposal, we aim to utilize the groundbreaking single-cell RNA-seq analyses to investigate the unique microglial subsets present following specific targeted deletion of NOX2. Furthermore, we will investigate the transcriptional signatures of the microglial subsets that modulate neurorestorative properties in the chronically injured brain. Importantly, this proposal will investigate the role of NOX2 in non-microglia macrophage-like cells, including border-associated macrophages (BAMs) and circulating monocytes, in mediating neuroinflammatory responses and neurological decline, following TBI. Specific aims include: 1) To elucidate the mechanisms of repopulation-induced microglial reprograming associated with attenuated pro-inflammatory, neurotoxic phenotypes after TBI; 2) To determine the role of microglial NOX2 in neuroinflammation/neurodegeneration after TBI; 3) To address the role of BAM NOX2 in in neuroinflammation/neurodegeneration after TBI; and 4) To evaluate the role of circulating monocytes NOX2 in neuroinflammation/neurodegeneration after TBI. Understanding the molecular mechanisms that drive microglia and non-microglia macrophage-like cells to polarize towards a neurorestorative state will be crucial to unlock the endogenous potential of microglia/macrophages to promote repair during the chronic phase of recovery after TBI.