Targeting TFEB To Microglia and Monocytes to Enhance Amyloid Degradation

项目摘要/摘要 阿尔茨海默病(AD)是导致痴呆症的最常见原因，其发病机制具有以下特点 A-β在间质液中的积聚及其聚集成可溶低聚物和不溶低聚物 淀粉样斑块。这触发了一系列事件，包括神经原纤维缠结的形成，神经元 功能障碍和变性，最终导致临床痴呆。在散发性AD中，年龄相关 不同脑细胞类型的溶酶体功能受损与Aβ代谢受损有关， 从而加速发病。小胶质细胞是脑内吞噬细胞Aβ和 淀粉样斑块；但观察到充斥着残留的淀粉样物质，表明 溶酶体降解能力。小胶质细胞是大脑中孤立的自我更新群体， 在正常生理条件下，外周血单核细胞不会越过血脑屏障。是否 单核细胞进入阿尔茨海默病大脑是目前争议的一个来源。我们的初步数据和命运图 策略证明外周血单核细胞在老年APP/PS1小鼠的淀粉样斑块中居家，这是一种 AD的发病机制和摄取淀粉样物质。外周血单核细胞更容易通过基因打靶 治疗或药物治疗方法优于常驻小胶质细胞，因此提供了一种刺激 溶酶体在细胞中发挥作用，以脑实质内的斑块为靶标。我们已经证明了 外源表达转录因子EB(TFEB)，溶酶体降解途径的主要诱导者， 刺激星形胶质细胞溶酶体的生物合成和功能，通过巨噬细胞吞噬上调Aβ摄取和 加速其溶酶体的降解，导致淀粉样斑块减弱。是否以TFEB为目标 滞留的小胶质细胞或循环单核细胞促进淀粉样蛋白吞噬和溶酶体降解 减轻斑块发病机制，改善神经功能，有待进一步探索。 假设：基于个体发育的外源性TFEB靶向小胶质细胞和外周血单核细胞是足够的 刺激淀粉样蛋白的摄取和降解；并减轻AD患者的淀粉样斑块和神经元病理。 为了验证这一假设，我们提出了三个具体目标：SA1：确定是否可以增强溶酶体功能 TFEB在小胶质细胞中的表达可减轻AD模型小鼠斑块的发病。SA2：研究 外周血单核细胞募集在淀粉样斑块发病中的作用。SA3：确定是否增强TFEB表达 循环单核细胞特异性影响AD小鼠单核细胞募集和斑块发病 模特们。

PROJECT SUMMARY / ABSTRACT The pathogenesis of Alzheimer’s disease (AD), the most common cause of dementia, is characterized by the accumulation of Aβ in the interstitial fluid (ISF) and its aggregation into soluble oligomers and insoluble amyloid plaques. This triggers a cascade of events including the formation of neurofibrillary tangles, neuronal dysfunction and degeneration, ultimately resulting in clinical dementia. In sporadic AD, age-dependent compromise of lysosome function in various brain cell types has been implicated in impaired Aβ metabolism, resulting in accelerated pathogenesis. Microglia, the primary immune cell in the brain phagocytose Aβ and amyloid plaques; but are observed to be engorged with residual amyloid material, suggesting impairment of lysosomal degradative capacity. Microglia are an isolated self-renewing population within the brain and peripheral monocytes do not cross the blood brain barrier under normal physiological conditions. Whether monocytes enter the AD brain is a current source of controversy. Our preliminary data with a fate-mapping strategy demonstrate that peripheral monocytes home in to amyloid plaques in aged APP/PS1 mice, a model of AD pathogenesis and take up amyloid material. Peripheral monocytes are more amenable to targeting via gene therapy or pharmacologic approaches than resident microglia and thus offer an opportunity to stimulate lysosomal function in cells that will target plaques within the brain parenchyma. We have demonstrated that exogenous expression of transcription factor EB (TFEB), a master inducer of lysosomal degradative pathways, stimulates lysosome biogenesis and function in astrocytes, to upregulate Aβ uptake via macropinocytosis and accelerate its lysosomal degradation resulting in attenuated amyloid plaques. Whether targeting TFEB to resident microglia or circulating monocytes facilitates amyloid phagocytosis and lysosomal degradation to attenuate plaque pathogenesis and improve neuronal function, needs to be explored. Hypothesis: Ontogeny-based targeting of exogenous TFEB to microglia and peripheral monocytes is sufficient to stimulate amyloid uptake and degradation; and attenuate amyloid plaques and neuronal pathology in AD. To test this hypothesis, we propose three specific aims: SA1: Determine if enhancing lysosomal function with TFEB expression in microglia attenuates plaque pathogenesis in AD mouse models. SA2: Examine the role of peripheral monocyte recruitment in amyloid plaque pathogenesis. SA3: Determine if enhancing TFEB expression specifically in circulating monocytes affects monocyte recruitment and plaque pathogenesis in AD mouse models.