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

项目总结/摘要 阿尔茨海默病（Alzheimer's disease，AD）是世界上最常见的神经退行性疾病，约有600万人患有AD 美国人由于没有改善疾病的治疗方法，预计到2050年这一数字将翻一番。 了解AD的遗传病因对于提供有效治疗至关重要，但仍然是一个挑战。 晚发性AD的遗传率约为60- 80%，全基因组关联研究（GWAS） 发现了几十个影响AD风险的单核苷酸多态性（SNPs）。两大挑战， AD遗传风险的功能性解释是（1）确定SNP在其中的相关细胞类型， 操作和（2）确定他们失调的基因，以驱动AD发病机制。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仍然未定位。一种可能是它们在其他脑细胞类型中表达 用目前的方法。事实上，尽管大多数AD患者表现出血管病变， 密度接近总神经胶质密度-测序研究由于未知的原因丢失了这些细胞。到 针对这一挑战，我们发明了一种新的用于测序的血管分离和细胞核提取方法 （VINE-seq）从死后大脑中有效捕获人脑血管细胞类型，用于单核细胞 RNA测序。令人惊讶的是，我们发现前45名提名的AD GWAS基因中有30个是富集的， 在人脑血管系统中。因此，我们假设AD风险SNP在人脑血管中是活跃的， 细胞类型，它们通过功能失调参与炎症和 蛋白质转运途径。将VINE-seq与标准单核工作流程相结合，我们建议 系统地确定每个AD SNP的宿主细胞类型和靶基因。我们将开始确定 AD GWAS SNPs由来自高质量额叶皮质的脑血管和实质细胞类型携带， 组织跨越疾病阶段（目标1）。然后，我们将确定每个AD风险SNP破坏的基因， 脑细胞类型，并确定它们与AD进展和病理学的关系（目的2）。完成后 这项研究，我们希望了解AD遗传风险变异如何在人类大脑中运作和失调 血管细胞我们将提供一个权威的单核转录组和表观遗传资源来破译 血管脆弱性和疾病阶段失调的分子基础，以及它们如何与 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 揭示这里可能是至关重要的了解和治疗AD和混合病理痴呆症。

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.