Understanding how human brain vascular cells mediate genetic risk for Alzheimer's disease

项目摘要/摘要 阿尔茨海默病(AD)是世界上最常见的神经退行性疾病，约有600万人患病 美国人。由于没有治疗疾病的方法可用，预计到2050年，这一数字将翻一番。 了解阿尔茨海默病的遗传病因对于指导有效的治疗至关重要，但仍然是一个挑战。 晚发性阿尔茨海默病的遗传遗传率为~60%-80%，全基因组关联研究(GWAS)有 发现了数十个影响AD风险的单核苷酸多态(SNPs)。面临的两个关键挑战 对阿尔茨海默病遗传风险的功能解释是：(1)确定SNP所在的相关细胞类型 操作和(2)确定它们失调的基因，以驱动AD的发病。单核测序 对人类神经元、小胶质细胞和其他脑细胞类型的研究已经开始解决这些挑战。然而， 许多AD风险SNP仍未被映射。一种可能性是它们在其他类型的脑细胞中表达 被目前的方法遗漏。事实上，尽管大多数AD患者都表现出血管病理--和血管细胞 密度接近总胶质细胞密度--测序研究由于未知原因丢失了这些细胞。至 针对这一挑战，我们发明了一种新的血管分离和核提取测序方法 (VINE-SEQ)有效地从死后脑中捕获人脑血管细胞类型用于单核 RNA测序。令人惊讶的是，我们发现前45个被提名的AD GWAS基因中有30个是富集型的 在人类的脑血管系统中。因此，我们假设AD风险SNPs在人类脑血管中是活跃的 细胞类型，并通过功能失调参与炎症性和 蛋白质的运输途径。将Vine-seq与标准单核工作流相结合，我们建议 系统地确定每个AD SNP的宿主细胞类型和靶基因。我们将从确定 高质量额叶皮质脑血管和实质细胞类型携带的AD GWASSNPs 跨疾病阶段的组织(目标1)。然后我们将确定每个AD风险SNP在每个基因中中断的基因 脑细胞类型和定义它们与AD进展和病理的关系(目标2)。在完成后 这项研究，我们希望了解阿尔茨海默病遗传风险变异是如何在人脑中起作用和失调的 血管细胞。我们将提供权威的单核转录和表观遗传学资源来破译 不同疾病阶段血管脆弱性和调节失调的分子基础，以及它们与 神经元和神经胶质功能障碍。鉴于血管功能对大脑健康的重要性，我们的见解 揭示可能是关键的AD和混合病理性痴呆的认识和治疗。

Project Summary/Abstract Alzheimer’s disease (AD) is the most prevalent neurodegenerative disease in the world and afflicts ~6 million Americans. With no disease-modifying treatments available, this number is expected to double by 2050. Understanding the genetic etiology of AD is critical to inform effective therapies but remains a challenge. Genetic heritability of late-onset AD is ~60–80%, and genome-wide association studies (GWAS) have uncovered dozens of single nucleotide polymorphisms (SNPs) that influence AD risk. Two key challenges for the functional interpretation of AD genetic risk are (1) determining the relevant cell types in which SNPs operate and (2) identifying the genes they dysregulate to drive AD pathogenesis. Single-nucleus sequencing studies of human neurons, microglia, and other brain cell types have begun addressing these challenges. Yet, many AD risk SNPs remain unmapped. One possibility is that they are expressed in other brain cell types missed by current methods. Indeed, though most AD patients exhibit vascular pathology—and vascular cell density approaches total glia density—sequencing studies have lost these cells for unknown reasons. To address this challenge, we invented a new Vessel Isolation and Nuclei Extraction for Sequencing method (VINE-seq) to efficiently capture human brain vascular cell types from postmortem brains for single-nucleus RNA sequencing. Surprisingly, we discovered that 30 of the top 45 nominated AD GWAS genes are enriched in the human brain vasculature. Thus, we hypothesize that AD risk SNPs are active in human brain vascular cell types and that they drive AD genetic risk by functionally dysregulating genes involved in inflammatory and protein transport pathways. Combining VINE-seq with standard single nucleus workflows, we propose to systematically determine the host cell type and target genes for each AD SNP. We will begin by determining the AD GWAS SNPs harbored by brain vascular and parenchymal cell types from high-quality frontal cortical tissue across disease stages (Aim 1). We will then identify the genes disrupted by each AD risk SNP in each brain cell type and define their relationship to AD progression and pathology (Aim 2). Upon the completion of this study, we expect to understand how AD genetic risk variants operate in and dysregulate human brain vascular cells. We will provide an authoritative single nuclei transcriptomic and epigenetic resource to decipher the molecular basis of vascular vulnerability and dysregulation across disease stages, and how they relate to neuronal and glial dysfunction. Given the importance of vascular function for brain health, the insights we reveal here may be critical to understanding and treating AD and mixed pathology dementias.