Imaging Mass Spectrometry-Based Metabolomic Analysis of the Alzheimer's Brain

基于成像质谱的阿尔茨海默病脑代谢分析 项目摘要 阿尔茨海默病（Alzheimer's disease，AD）是最常见的神经退行性疾病。虽然多个基因及其 尽管已经报道了与AD发病机制相关的突变，但AD的致病机制仍然存在 难以捉摸大多数AD研究的焦点已经针对特异性蛋白质的选择性丢失。 神经元群体。尽管如此，较少的努力已经花在了解反应性星形胶质细胞，一个共同的特点， 老年大脑的损伤和疾病。最近，我们描述了一种反应性星形胶质细胞亚型， 在各种人类神经退行性疾病中观察到，包括AD和帕金森病（PD）。 小胶质细胞的激活导致星形胶质细胞通过分泌神经毒素转化为神经毒性反应性星形胶质细胞 IL-1 β、TNF α和C1q。用药物阻断小胶质细胞活化，NLY 01阻止星形胶质细胞转化为 反应性星形胶质细胞提供神经保护。静息小胶质细胞和星形胶质细胞向反应性 与细胞内能量代谢和脂质组成的变化密切相关。静息小胶质细胞 主要依靠氧化磷酸化来产生能量。当小胶质细胞的新陈代谢从 氧化磷酸化到糖酵解，小胶质细胞被激活。这一变化随后转化为休息 星形胶质细胞转化为反应性星形胶质细胞，增加葡萄糖消耗。APOE中的长链饱和脂质， 据报道，星形胶质细胞分泌的APOJ也显示出神经毒性。因此了解 在神经变性过程中，小胶质细胞、星形胶质细胞和神经元的代谢组学变化很可能 提供对AD发病机制的更深入了解。成像质谱代谢组学分析 将提供大脑中细胞类型和区域特异性代谢组学变化的视图。研究代谢组学 在细胞类型特异性方式的变化，我们提出了三个具体的目标。(Aim 1）我们将研究区域-和 小鼠脑内小胶质细胞-星形胶质细胞-神经元轴的细胞类型特异性代谢组学变化 过表达淀粉样蛋白β和响应病理性tau蛋白。(AIM 2）我们将检查区域和细胞类型- 在对照组和AD人类死后脑中的特定代谢组学变化。(Aim（3）比较区域- 过表达淀粉样蛋白β的小鼠的细胞类型特异性脑代谢组学变化， 病理性tau与通过用PLX 3397或NLY 01处理缺乏小胶质细胞活化的tau。的 这些目标的完成将提供对衰老过程中细胞类型代谢组动力学的更好理解 以及由过表达的淀粉样蛋白β和病理性tau蛋白注射介导的神经变性。小说 本研究获得的信息将为研究细胞类型特异性AD致病性提供不可或缺的见解， 这为开发针对小胶质细胞和星形胶质细胞的新AD治疗提供了新的机会。 此外，这种策略可以扩展到研究其他脑部疾病的发病机制。 1

IMAGING MASS SPECTROMETRY-BASED METABOLOMIC ANALYSIS OF THE ALZHEIMER'S BRAIN PROJECT SUMMARY Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder. Although multiple genes and their mutations linked to AD pathogenesis have been reported, the pathogenic mechanisms of AD still remain elusive. The focus of the majority of AD research has been targeted towards the selective loss of specific neuronal populations. Still, less effort has been spent in understanding reactive astrocytes, a feature common to injury and disease in the aged brain. Recently, we described a subtype of reactive astrocytes that are observed in various human neurodegenerative diseases, including AD and Parkinson's disease (PD). Activation of microglia leads to the conversion of astrocytes into neurotoxic reactive astrocytes via secretion of IL-1, TNF, and C1q. Blocking microglia activation with the drug, NLY01 prevented astrocyte conversion to reactive astrocytes providing neuroprotection. The conversion of resting microglia and astrocytes to reactive ones is deeply related to changes in energy metabolism and lipid composition in the cell. Resting microglia mainly rely on oxidative phosphorylation for energy production. When microglia metabolism converts from oxidative phosphorylation to glycolysis, microglia are activated. This change subsequently converts resting astrocytes to reactive ones ramping up their glucose consumption. Long-chain saturated lipids in APOE and APOJ secreted by astrocytes also have been reported to show neurotoxicity. Therefore, understanding metabolomic changes in microglia, astrocytes, and neurons during the course of neurodegeneration is likely to provide a deeper understanding of AD pathogenesis. Imaging mass spectrometry-based metabolomic analysis will provide a view of cell-type and region-specific metabolomic changes in the brain. To study metabolomic changes in a cell-type-specific manner, we propose three specific aims. (Aim 1) We will examine region- and cell-type-specific metabolomic changes in the microglia-astrocyte-neuron axis in the brain of mice overexpressing amyloid β and in response to pathologic tau. (AIM 2) We will examine region- and cell-type- specific metabolomic changes in control and AD human post-mortem brains. (Aim 3) We will compare region- and cell-type-specific brain metabolomic changes of mice overexpressing amyloid β and in response to pathologic tau with the ones lacking microglial activation by the treatment with PLX3397 or NLY01. The completion of these aims will provide a better understanding of cell-type metabolome dynamics during aging and neurodegeneration mediated by overexpressed amyloid β and pathologic-tau injection. The novel information acquired in this study will provide indispensable insights into cell-type-specific AD pathogenic mechanisms and offer new opportunities to develop new AD treatments targeting microglia and astrocytes. Furthermore, this strategy can be expanded to study the pathogenesis of other brain diseases. 1