Impact of T cells on the CNS during aging and Alzheimer’s disease

项目总结/摘要 阿尔茨海默病（AD）是一种导致β淀粉样蛋白斑块沉积的神经退行性疾病， 神经系统缠结（NFT）形成和改变生活的认知缺陷。许多人类遗传性AD风险因素， 包括APOE、CLU和TREM 2，调节神经炎症和/或小胶质细胞的功能，中枢神经系统 神经系统（CNS）固有免疫细胞。删除所有外周适应性免疫细胞（即CD 4 + T细胞、CD 8 + T细胞和B细胞）或T细胞耗竭（即CD 4 +T细胞、CD 8 +T细胞）增加认知能力 分别在淀粉样变性和tau蛋白病模型中，并且与改变的小胶质细胞功能相关。 有趣的是，衰老，另一个主要的AD风险因素，与炎症有关，我们发现， 随着年龄的增长，CNS CD 8 + T细胞的增加会因淀粉样变性而进一步加剧。此外，增强 在tau蛋白病期间也发现CNS CD 8 + T细胞数量。我们假设CD 8 + T细胞影响 tau蛋白病和年龄相关性淀粉样变性期间的认知和CNS后遗症。我们预测CD 8 + T细胞 改变小胶质细胞功能和转录组作为疾病调节的机制。为了解决这个 假设，我们将利用老年野生型（WT）对照小鼠，老年APPNL-F/NL-F小鼠，其表达人 淀粉样前体蛋白（APP）或我们的Tau病变的AAV 1模型，分别在正常WT或CD 8-/- 背景，以消除CD 8 + T细胞。我们亦会就OT-I背景进行类似的研究， 含有不通过其T细胞受体（TCR）刺激的CD 8 + T细胞。我们将评估多个 包括行为/认知表现的参数（使用旷场试验，高架十字迷宫， 背景恐惧条件反射和Morris水迷宫），免疫荧光/免疫组织学检查斑块 沉积，tau磷酸化，CD 8 + T细胞定位和小胶质细胞/星形胶质细胞反应性，流式细胞术 CNS CD 8 + T细胞功能分析，总tau和磷酸化tau的蛋白质印迹分析，离体小胶质细胞 培养物和RT-qPCR检测皮质和海马促炎和抗炎基因表达。 炎症因子此外，我们将使用单细胞转录组学来检查整个RNA 在每个细胞的基础上，使用转录组来评估CNS CD 8 +T细胞转录组和CD 8 +T细胞对 在正常衰老、年龄相关性淀粉样变性或tau蛋白病期间，小胶质细胞转录组和亚群。 我们提出的工作将是第一个定义CNS CD 8 + T细胞在年龄背景下的转录组。 相关的淀粉样变性或tau蛋白病。此外，我们将首次讨论CD 8 +T细胞如何影响 行为/认知、神经炎症、神经胶质增生、小胶质细胞转录组和年龄相关性 淀粉样变性或tau蛋白病。这项工作将提供高度新颖的见解，如何外周和中央免疫 在衰老和疾病过程中相互作用，并可能为研究新的治疗措施提供动力， 管理/缓解AD相关CNS后遗症。

PROJECT SUMMARY/ABSTRACT Alzheimer’s disease (AD) is a neurodegenerative disease that results in amyloid β plaque deposition, neurofibrillary tangle (NFT) formation, and life-altering cognitive defects. Many human genetic AD risk factors, including APOE, CLU, and TREM2, modulate neuroinflammation and/or the function of microglia, the central nervous system (CNS) resident innate immune cell. Deletion of all peripheral adaptive immune cells (i.e. CD4+ T cells, CD8+ T cells and B cells) or T cell depletion (i.e. CD4+T cells, CD8+T cells) increased cognitive abilities in amyloidosis and tauopathy models, respectively, and were associated with altered microglial function. Interestingly, aging, another major AD risk factor, is associated with inflammation and we have found that increases in CNS CD8+ T cells found with aging is further exacerbated by amyloidosis. Additionally, enhanced CNS CD8+ T cells numbers are also found during tauopathy. We hypothesize that CD8+ T cells impact cognition and CNS sequelae during tauopathy and age-associated amyloidosis. We predict that CD8+ T cells alter microglia function and transcriptomes as a mechanism for disease modulation. To address this hypothesis, we will utilize aged wild type (WT) control mice, aged APPNL-F/NL-F mice, which express human amyloid precursor protein (APP) or our AAV1 model of tauopathy, respectively, on a normal WT or CD8-/- background, to eliminate CD8+ T cells. We will also conduct similar studies on an OT-I background which contains CD8+ T cells that are not stimulated through their T cell receptor (TCR). We will assess multiple parameters including behavioral/ cognitive performance (using open field assay, elevated plus maze, contextual fear conditioning and morris water maze), immunofluorescence/immunohistology examining plaque deposition, tau phosphorylation, CD8+ T cell localization and microglial/ astrocyte reactivity, flow cytometric analysis of CNS CD8+ T cell function, western blot analysis for total and phosphorylated tau, ex vivo microglial cultures and RT-qPCR to examine cortical and hippocampal gene expression of proinflammatory and anti- inflammatory factors. Furthermore, we will be using single cell transcriptomics to examine the entire RNA transcriptome on a per cell basis to assess CNS CD8+T cell transcriptomes and the impact of CD8+T cells on microglial transcriptomes and subpopulations during normal aging, age-associated amyloidosis or tauopathy. Our proposed work will be the first to define the transcriptomes of CNS CD8+ T cells in the context of age- associated amyloidosis or tauopathy. Additionally, we will address for the first time how CD8+T cells impact behavior/cognition, neuroinflammation, gliosis, microglial transcriptomes and pathology during age-associated amyloidosis or tauopathy. This work will provide highly novel insights into how peripheral and central immunity interact during aging and disease, and could provide the impetus to examine new therapeutic measures for management/alleviation of AD associated CNS sequelae.