Influence of APOE genotype on cerebrovascular cell pathobiology in AD, and the contribution of microglia inflammation

阿尔茨海默病是一种与年龄相关的神经退行性疾病，是阿尔茨海默病的主要类型 痴呆症，以脑内淀粉样斑块和神经原纤维缠结沉积为特征。一个经常被忽视的 阿尔茨海默病的病因学损害为脑血管变性。脑血流异常是一种 阿尔茨海默病的临床前特征，在症状出现前许多年就表现出来。血管损伤也是例行公事 在阿尔茨海默病不同阶段的大脑中观察到。脑血管完整性的破坏可能会影响 然而，阿尔茨海默病这些血管变化的主要驱动因素神经功能仍然难以捉摸。 载脂蛋白E4(APOE4)等位基因是AD的最强危险因素之一，已被证明 显著影响脑血管健康，导致脑灌注不足、血管病变和 血脑屏障受损。然而，还需要更多的纵向研究来更好地理解载脂蛋白4是如何 能显著影响AD后遗症脑血管细胞病理生物学的发病机制。 在大脑中，载脂蛋白E主要由神经胶质细胞产生，而在阿尔茨海默病中，疾病相关的小胶质细胞(DAM) 已知可上调APOE的表达，APOE介导转录的促炎表型 这些细胞。DAM已被证明推动了APOE介导的神经元功能障碍的结果和速度， 但目前对它们在AD脑血管改变中所起的作用知之甚少， 特别是载脂蛋白E基因对此的影响。 为了解决这些问题，我们计划使用表达人类形式的apoE和A𝛽的小鼠模型来 阐明载脂蛋白4作为脑血管细胞病理生物学的分子驱动因素所起的作用，以及这是如何发生的 受DAM的影响。我们将在各个时间点探索纵向脑血管细胞的病理生物学 代表发病前、发作期间和发病后 一个 𝛽病理采用组织病理学和超微结构分析。我们 还将利用小胶质细胞消融证实DAMS对脑血管病理生物学的贡献 在我们的小鼠模型中，减少水坝人口并重新填充新生小胶质细胞的技术。到目前为止，没有 研究已经表征了这些反应性脑血管细胞表型的分子转录本 组合模型。因此，我们将使用脑血管细胞的单细胞基因分析来结束我们的研究。 (内皮细胞、周细胞、平滑肌细胞)，以揭示其独特和详细的反应时间进程。 我们将在AD分期病例的尸检脑血管组织中确认差异表达基因 验证我们的发现的翻译相关性，并对照小鼠AD相关的致病时间线进行映射。 根据这一建议，我们的目标是在早期阶段识别新的(脑血管)细胞特异性靶点。 载脂蛋白4等位基因导致神经风险的疾病。我们未来的目标将是探索 这些靶点的功能效应，并为促进脑血管疾病提供新的治疗机会 阿尔茨海默病患者认知功能的健康与恢复。

Alzheimer’s disease (AD) is an age-related neurodegenerative disorder and the predominant type of dementia, marked by brain deposits of amyloid plaques and neurofibrillary tangles. An often overlooked pathognomonic lesion of AD is cerebrovascular degeneration. Abnormalities in cerebral blood flow are a preclinical feature of AD that manifest many years before symptom onset. Vascular lesions are also routinely observed in AD brains at different stages of the disease. Disruptions to cerebrovascular integrity can impact on neuronal function, however, the main driver of these vascular changes in AD remains elusive. The Apolipoprotein E4 (APOE4) allele is one of the strongest risk factors for AD, and has been shown to significantly impact on cerebrovascular health, precipitating deficits in cerebral perfusion, vascular lesions and damage to the blood brain barrier. Yet, more longitudinal studies are needed to better understand how APOE4 can significantly impact on cerebrovascular cell pathobiology in the sequelae of AD pathogenesis. In the brain, APOE is produced primarily by glial cells, and in AD, disease associated microglia (DAM’s) are known to upregulate APOE expression, which mediates the transcriptional proinflammatory phenotype of these cells. DAM’s have been shown to drive the outcome and pace of APOE-mediated neuronal dysfunction, but very little is currently known about the role they play in contributing to cerebrovascular changes in AD, particularly, how this is influenced by APOE genotype. To address these questions, we plan to use mouse models expressing human forms of APOE and A𝛽 to clarify the role played by APOE4 as a molecular driver of cerebrovascular cell pathobiology, and how this is influenced by DAM’s. We will explore longitudinal cerebrovascular cell pathobiology at timepoints representing pre, peri and post onset of A 𝛽 pathology using histopathological and ultrastructural analyses. We will also confirm the contribution of DAMs on cerebrovascular pathobiology by utilizing microglia ablation techniques to depopulate DAMs and also repopulate newborn microglia in our mouse models. To date, no studies have characterized the molecular transcripts of reactive cerebrovascular cell phenotypes in these combined models. Thus, we will conclude our studies using single cell gene analyses of cerebrovascular cells (endothelial cells, pericytes, smooth muscle cells) to reveal their unique and detailed time-course of responses. We will confirm differentially expressed genes in autopsied cerebrovascular tissue from staged AD cases to validate the translational relevance of our findings and map against mouse AD-related pathogenic timelines. From this proposal, we aim to identify novel (cerebrovascular) cell specific targets in the early stages of disease through which the APOE4 allele confers neurological risk. Our future goal will be to explore the functional effects of these targets, and to provide new therapeutic opportunities to promote cerebrovascular health and restoration of cognitive function in AD.