Dissect regulation of glial nets surrounding amyloid plaques in Alzheimer's disease

项目摘要 阿尔茨海默病（AD）的病理生理机制尚不清楚。淀粉样斑块周围有反应性 星形胶质细胞和小胶质细胞，形成影响淀粉样蛋白扩散和炎症环境的胶质细胞网。但 神经胶质网络中神经胶质间通讯的机制知之甚少。我们最近的综合网络 对晚发性AD患者的组学数据的分析表明，轴突导向受体丛蛋白B1是一个枢纽， 基因在星形胶质细胞特定的子网络。我们已经证实丛状蛋白-B1主要表达于 星形胶质细胞，并且其在AD患者的胶质细胞网中上调。值得注意的是，我们的试点研究， AD的淀粉样蛋白生成小鼠模型显示，丛蛋白-B1缺失显著改变斑块周围的结构 神经胶质网丛蛋白-B1缺失导致星形胶质细胞反应性减弱，神经胶质细胞网的细胞间距减小， 以及小胶质细胞对斑块的更高覆盖率，导致斑块向致密核心型转变。这些变化 神经胶质网与斑块负荷和神经炎性营养不良的总体减少有关。这里我们将 扩大我们的初步研究，以进一步测试的核心假设，胶质细胞活化和细胞相互作用 在神经胶质网络中，由丛蛋白B1调节，影响AD中的淀粉样蛋白聚集和神经毒性。阻断丛蛋白-B1 因此可能提供了一个新的机会，以减弱胶质细胞网中星形胶质细胞的反应性，减少淀粉样蛋白的负担， 神经炎症，从而减缓AD进展。在目标1中，我们的目标是构建细胞类型特异性胶质细胞， 信号网络，并确定神经胶质细胞网丛蛋白B1介导的基因模块。我们将分析单个 来自AD患者和AD小鼠（有和没有丛蛋白-B1缺失）的细胞转录组学数据，以定义 与丛蛋白B1相关的反应性星形胶质细胞和活化小胶质细胞中的共调节基因网络 发信号。在目标2中，我们将在神经胶质细胞培养物中进行一系列功能测定，以研究丛蛋白-B1的作用。 在淀粉样蛋白激发后介导星形胶质细胞活化。具有丛蛋白-B1的人iPSC衍生的星形胶质细胞 将通过CRISPR-Cas缺失的原代星形胶质细胞与来自丛蛋白-B1突变小鼠的原代星形胶质细胞进行比较。然后我们将模型 在星形胶质细胞/小胶质细胞共培养物中，依赖丛状蛋白的响应淀粉样蛋白攻击的胶质细胞相互作用- B1.在目标3中，我们将使用小鼠AD模型进行体内研究，以详细研究丛状蛋白对AD的影响。 胶质细胞网B1缺失、斑块沉积、神经元功能和认知能力。淀粉样变 并且AD的tau蛋白病模型将在早期和晚期进行评估。我们希望证明， 丛蛋白B1缺失导致胶质细胞网中星形胶质细胞反应性减弱，细胞间距减小， 淀粉样斑块的小胶质细胞覆盖，以及向致密核心斑块的转变，从而减少神经毒性， 由飞行员数据指示。总而言之，我们的研究将为神经胶质网络和丛状蛋白的贡献提供新的见解， B1对AD的神经退行性变过程的作用，从而提供了新的治疗角度。

PROJECT SUMMARY The pathophysiology of Alzheimer’s disease (AD) remains unclear. Amyloid plaques are surrounded by reactive astrocytes and microglia, forming glial nets that affect amyloid spreading and inflammatory milieu. However, the mechanisms of inter-glial communication in glial nets are poorly understood. Our recent integrated network analysis of -omics data from late-onset AD patients identified the axon guidance receptor Plexin-B1 as a hub gene in an astrocyte-specific subnetwork. We have confirmed that Plexin-B1 is predominantly expressed in astrocytes and that it is upregulated in glial nets of AD patients. Remarkably, our pilot study with an amyloidogenic mouse model of AD showed that Plexin-B1 deletion markedly altered the structure of peri-plaque glial nets. Plexin-B1 deletion resulted in attenuated astrocyte reactivity, reduced cellular spacing of glial nets, and a higher coverage of plaques by microglia, leading to a shift of plaques to a dense core type. These changes of glial nets were associated with an overall reduction in plaque burden and neuritic dystrophy. Here we will expand our preliminary studies to further test the central hypothesis that glial activation and cellular interactions in glial nets, as regulated by Plexin-B1, affect amyloid aggregates and neurotoxicity in AD. Blocking Plexin-B1 may thus present a new opportunity to attenuate astrocyte reactivity in glial nets, reducing amyloid burden and neuroinflammation, thereby slowing down AD progression. In Aim 1, we aim to build cell type-specific glial signaling networks in AD, and to identify Plexin-B1-mediated gene modules in glial nets. We will analyze single cell transcriptomic data from both AD patients and AD mice (with and without Plexin-B1 deletion) to define coregulated gene networks in reactive astrocytes and activated microglia that are associated with Plexin-B1 signaling. In Aim 2, we will carry out a series of functional assays in glial cultures to study the role of Plexin-B1 in mediating astrocyte activation upon amyloid challenge. Human iPSC-derived astrocytes with Plexin-B1 deletion by CRISPR-Cas will be compared to primary astrocytes from Plexin-B1 mutant mice. We will then model in astrocyte/microglia co-cultures glial interactions in response to amyloid challenge in dependence of Plexin- B1. In Aim 3, we will conduct in vivo studies using mouse AD models to investigate in detail the impact of Plexin- B1 deletion on glial nets, plaque deposition, neuronal function and cognitive performance. Both an amyloidogenic and a tauopathy model of AD will be evaluated at early and advanced stages. We expect to demonstrate that Plexin-B1 deletion leads to attenuated astrocyte reactivity in glial nets, reduced cellular spacing, increased microglial coverage of amyloid plaques, and a shift to dense-core plaques and thus less neurotoxicity, as indicated by pilot data. Altogether, our study will provide new insights into the contribution of glial nets and Plexin- B1 to the neurodegenerative processes in AD, thus providing new therapeutic angles.