Interrogating and Targeting Microglia Phagocytosis in Alzheimer’s Disease

阿尔茨海默病（AD）是一种难治性神经退行性疾病，在全国范围内约有620万美国人。新出现的证据现在确立了小胶质细胞在AD发病机制中的核心作用，并揭示了这些细胞中的转录和表观遗传水平变化与疾病进展密切相关。因此，靶向小胶质细胞与选择性药物，以控制其细胞活性代表了一个强大的治疗途径。然而，精确的小胶质细胞靶向需要广泛了解细胞表面蛋白质组或表面蛋白质组如何在疾病环境中重塑，并且这种生物学尚未被系统地探索。我对暴露于Aβ纤维后的小胶质细胞进行了基于质谱的表面组分析。我的数据显示硫酸乙酰肝素蛋白聚糖和促进吞噬作用的蛋白质的强烈上调。在本提案的目标1中，我将直接测试Aβ诱导的硫酸乙酰肝素蛋白聚糖是否导致tau吞噬作用增加和人类iPSC小胶质细胞中的接种。这一假说代表了一个独特的框架，通过小胶质细胞吞噬作用将Aβ和tau病理学机制联系起来。目的2：研究硫酸乙酰肝素蛋白聚糖在AD患者脑组织中的表达模式。最后，在目标3中，我将设计新型细胞表面降解抗体，称为KineTAC，以特异性降解细胞表面的疾病相关小胶质细胞靶点。本提案中概述的工作是创新的，将大大增加我们对AD中小胶质细胞吞噬作用的理解，并提供新的重组工具来调节这一过程。在我在加州大学旧金山分校弗朗西斯科的科学导师和顾问的大力支持下，这个K 08培训计划将使我能够培养对iPSC细胞培养模型，人类免疫组织化学和重组抗体工程的掌握。这一轨迹构成了迈向更广泛的职业目标的第一步，即成为一名独立的医生-科学家，研究神经变性的细胞和分子机制。

Alzheimer's disease (AD) is an intractable neurodegenerative disorder that devastates approximately 6.2 million Americans nationwide. Emerging evidence now establishes a central role for microglia in AD pathogenesis and reveals that transcriptional and epigenetic level changes in these cells tightly correlate with disease progression. Thus, targeting microglia with selective pharmacologic agents to control their cellular activity represents a powerful therapeutic avenue. However, precise microglia targeting requires broad knowledge of how the cell-surface proteome, or surfaceome, remodels in the disease environment, and this biology has not been systematically explored. I performed mass spectrometry-based surfaceome profiling of microglia after exposure to Aβ fibrils. My data revealed a robust upregulation of heparan sulfate proteoglycans and proteins that promote phagocytosis. In Aim 1 of this proposal, I will directly test if Aβ-induced heparan sulfate proteoglycans result in increased tau phagocytosis and seeding in human iPSC microglia. This hypothesis represents a unique framework that mechanistically links Aβ and tau pathology through microglia phagocytosis. In Aim 2, I will determine the tissue expression patterns of heparan sulfate proteoglycan in human AD brain. Finally, in Aim 3, I will engineer novel cell-surface degrading antibodies, called KineTACs, to specifically degrade disease-associated microglia targets from the cell-surface. The work outlined within this proposal is innovative and will greatly increase our understanding of microglia phagocytosis in AD and provide new recombinant tools to modulate this process. With the strong support of my scientific mentors and advisors at the University of California San Francisco, this K08 training proposal will enable me to cultivate mastery in iPSC cell culture models, human immunohistochemistry, and recombinant antibody engineering. This trajectory constitutes the first steps toward a broader career goal of becoming an independent physician-scientist studying the cellular and molecular mechanisms of neurodegeneration.