Microglia as Mediators of Dendritic Spine Loss and Plaque Formation in the AD Brain

项目2：小胶质细胞作为AD脑中树突棘缺失和斑块形成的介导者 项目总结/摘要 树突棘缺失与阿尔茨海默病（AD）和其他疾病的认知能力下降密切相关。 紊乱确定导致疾病中脊柱损失的机制和刺激对于发展 逆转或防止这些损失的策略，希望能导致认知的改善。的同时 在脊椎缺失的情况下，在AD脑和其他疾病中发现慢性小胶质细胞活化。作为我们 为了研究炎症在AD发病机制中的作用，我们以集落刺激因子1受体为靶点， （CSF 1 R），因为它调节小胶质细胞的增殖。我们发现小胶质细胞在生理上 依赖于CSF 1 R信号传导，并且CSF 1 R拮抗剂的施用导致快速和 持续消除CNS中几乎所有的小胶质细胞。我们使用这种方法来确定， 小胶质细胞在调节成年人大脑中树突棘的数量方面确实起着非常重要的作用， 的小胶质细胞8周导致CA 1和V层皮质神经元的棘密度增加约35%。 此外，电生理学揭示了对神经元的兴奋性突触输入的强烈增加，显示了直接的 增加活跃突触的证据正如我们已经证明的那样，小胶质细胞在调节脊柱和 突触在成人大脑中，我们现在提出，这一正常功能在AD中出错，导致过度修剪 导致脊椎密度降低和随后的认知能力下降。我们的项目建议 4个相关目标将利用人体组织探索小胶质细胞和树突棘之间的关系 损失，以及斑块形成，在AD。首先，我们将进行小胶质细胞之间的彻底相关性， 密度和形态与对照，MCI和AD受试者的死后组织的脊柱损失。我们将 然后用高病理对照组的组织检验我们的假设我们将利用人类成纤维细胞 来自MCI受试者，具有高数量的AD小胶质细胞风险SNP或低数量的AD小胶质细胞风险SNP， 通过iPS细胞技术分化为多能干细胞，然后分化为小胶质细胞。我们将探索 来自这些MCI患者的小胶质细胞在1）修剪树突棘和2） 吞噬细胞和明确的A β，将这些发现与我们的MCI受试者转化为AD相关联。 对我们的方法至关重要的是，我们现在有了消除小鼠所有内源性小胶质细胞的技术。 通过给予CSF 1 R抑制剂，然后通过输注人IPS-1， 衍生的小胶质细胞。使用这种方法，我们可以探索这些细胞在体内环境中的作用， 确定这些人源性小胶质细胞对树突棘和清除/形成的影响， A� plaques.通过这些实验，我们将能够充分研究人类之间的关系， 小胶质细胞和AD病理/脊柱损失的方式，以前还没有可能的。这些结果将 可能导致抑制剂的发展，可以消除AD大脑中的小胶质细胞，从而防止AD的发生。 脊柱缺失。

Project 2: Microglia as Mediators of Dendritic Spine Loss and Plaque Formation in the AD Brain Project Summary/Abstract Dendritic spine loss is closely associated with cognitive decline in Alzheimer's disease (AD) and other disorders. Identifying the mechanisms and stimuli that lead to spine loss in disease is crucial to developing strategies to reverse or prevent these losses, hopefully leading to improvements in cognition. Concurrent with spine loss, chronic microglial-activation is found in the AD brain and in other disorders. As part of our investigations into inflammation in the pathogenesis of AD, we targeted the colony-stimulating factor 1 receptor (CSF1R), as this regulates the proliferation of microglia. We discovered that microglia are physiologically dependent upon CSF1R signaling and that administration of CSF1R antagonists results in the rapid and continued elimination of virtually all microglia from the CNS. We have used this approach to determine that microglia do play a highly significant role in regulating dendritic spine numbers in the adult brain elimination of microglia for 8 weeks results in a ~35% increase in spine densities in CA1 and layer V cortical neurons. Additionally, electrophysiology reveals robustly increased excitatory synaptic inputs to neurons, showing direct evidence of increased active synapses. As we have shown that microglia play a role in modulating spine and synapses in the adult brain, we now propose that this normal function goes awry in AD, leading to overpruning of synapses and resulting in reduced spine densities and subsequent cognitive decline. Our project proposes 4 linked aims that will utilize human tissue to explore the relationship between microglia and dendritic spine loss, as well as plaque formation, in AD. Firstly, we will conduct thorough correlations between microglial densities and morphologies with spine loss from post-mortem tissues in control, MCI and AD subjects. We will then test our hypothesis using tissue from high-pathology control subjects. We will utilize human fibroblasts from MCI subjects, with either a high number of AD microglial-risk SNPs or a low number, which are converted to pluripotent stem cells via iPS cell technology, and then differentiated into microglia. We will then explore how microglia derived from these MCI patients differ in their abilities to 1) prune dendritic spines and 2) phagocytose and clear A�, correlating these findings with the conversion into AD from our MCI subjects. Critical to our approach, we now have the technology to eliminate all endogenous microglia from the mouse CNS via administration of CSF1R inhibitors and then repopulate the mouse brain by infusing in human IPS- derived microglia. Using this method, we can explore the effects of these cells in an in vivo setting and thus determine the effects of these human-derived microglia on both dendritic spines and on clearance/formation of A� plaques. Through these experiments we will be able to fully study the relationship between human microglia and AD pathology/spine loss in a fashion that has not been previously possible. These results will potentially lead to the development of inhibitors that can eliminate microglia in the AD brain and hence prevent spine loss.