NOX2 drives microglia-dependent neurodegeneration after traumatic brain injury

项目摘要：创伤性脑损伤（TBI）触发延迟的分子继发性损伤级联反应，包括 慢性神经炎症，导致进行性组织损失和神经损伤，包括 认知缺陷严重TBI后发生慢性神经炎症伴持续小胶质细胞活化 并被认为有助于随后的神经变性和神经损伤。因此， 小胶质细胞活化可能为TBI患者提供新的治疗靶点。我们以前的研究已经探索了 TBI后功能失调的小胶质细胞的发展，并显示：1）促炎性小胶质细胞是慢性的， 在实验性TBI后长达一年激活，导致神经变性和认知能力下降; 2） NADPH氧化酶（NOX 2）在慢性小胶质细胞介导的神经毒性中起关键作用; 3）暂时性耗竭 使用CSF 1 R抑制剂（PLX 5622）的脑小胶质细胞引起小胶质细胞重编程和表型转变， 慢性促炎性特征转变为表达减少的炎性标志物的更具恢复性的表型， 包括NOX 2，并减轻长期运动和认知缺陷。在本提案中，我们的目标是利用 开创性的单细胞RNA-seq分析，以研究以下独特的小胶质细胞亚群 NOX 2的特异性靶向缺失。此外，我们将研究转录签名的 调节慢性损伤脑中神经恢复特性的小胶质细胞亚群。重要的是这 这项提案将研究NOX 2在非小胶质细胞巨噬细胞样细胞中的作用，包括与边缘相关的细胞。 巨噬细胞（BAM）和循环单核细胞，在介导神经炎症反应和神经 在TBI之后下降。具体目的包括：1）阐明再生诱导小胶质细胞增殖的机制， 与TBI后减弱的促炎性、神经毒性表型相关的重编程; 2）确定 小胶质细胞NOX 2在TBI后神经炎症/神经变性中的作用; 3）探讨BAM的作用 NOX 2在TBI后神经炎症/神经变性中的作用;以及4）评估循环单核细胞的作用 TBI后神经炎症/神经变性中的NOX 2。了解驱动生物进化的分子机制 小胶质细胞和非小胶质细胞巨噬细胞样细胞向神经恢复状态转化将是至关重要的， 释放小胶质细胞/巨噬细胞的内源性潜力，以促进慢性期的修复， TBI后的康复

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.