Investigating And Targeting Microglial Senescence In Alzheimer's Disease

我们的免疫反应通常是一种防御机制，以防止感染的传播及其相关的组织损伤。在大脑中，炎症是一把双刃剑，由主要驻留的巨噬细胞群--小胶质细胞介导。我们知道，在阿尔茨海默氏症(AD)或帕金森氏症等与年龄相关的神经系统疾病中，小胶质细胞最典型的反应之一是数量增加。来自我们研究小组的最新数据表明，当随着时间的推移重复这种扩张过程时，会导致小胶质细胞耗尽，这一过程被称为复制性衰老。这反过来在阿尔茨海默氏症等慢性神经退行性疾病的发展过程中会产生有害的影响。然而，我们并不完全了解这个过程是如何发展的，以及小胶质细胞通常在大脑中扮演的角色的后果是什么。最重要的是，到目前为止，关于这些机制的大部分知识都来自对啮齿动物的研究，而我们缺乏了解与人类相关的生物学的模型。在这项提议中，我们将开发新的模型，通过利用诱导多能干细胞(IPSCs)的培养来研究人类小胶质细胞的衰老，IPSCs可以转化为任何特定类型的感兴趣细胞。多亏了米德博士和牛津药物发现研究所的专业知识，我们将使用经过验证的模型将人类IPSCs转化为人类小胶质细胞。一旦我们在培养皿中获得了这些人类小胶质细胞，我们就会让它们发条，导致它们的数量增加，期望细胞会增加复制能力，变得衰老。我们将使用替代模型来诱导衰老，例如使用已知在其他药物中起作用的药理学试剂。一旦我们确定了诱导小胶质细胞衰老的条件，我们将探索小胶质细胞为了维持正常的大脑健康而承担的关键看家功能的影响。这些包括小胶质细胞清除(吞噬)异物和感染性物质的能力，即吞噬作用，以及小胶质细胞参与疾病炎症反应的能力。我们将检查在培养细胞中观察到的变化是否与AD患者大脑中观察到的小胶质细胞变化相关，这要归功于马修斯教授的贡献，他是在单细胞水平上分析人类小胶质细胞的领导者。一旦我们找到了诱导人小胶质细胞衰老的有效方法，并探索了衰老会导致哪些功能改变，我们就会筛选能够消除或逆转衰老小胶质细胞的药物。这将归功于吉尔教授的专业知识，他是了解和防治衰老领域的领军人物。我们将筛选大量化合物，并确定那些能够选择性地移除衰老的小胶质细胞，或将它们恢复到健康状态，而不改变非衰老细胞的化合物。为了满足我们的实验计划，我们将使用最先进的技术，充分使我们的方法对学术界产生影响。通过提出的方法，我们将在理解与年龄相关的大脑病理的初始事件方面开辟新的天地。我们计划将拟议的研究成果转化为药物发现阶段，并雄心勃勃地改善未来慢性神经变性患者的生活质量。

Our immune response is usually a defensive mechanism to prevent the spread of infections and their associated tissue damage. In the brain, inflammation is a double-edge sword mediated by the main resident macrophage population, the microglia. We know that one of the most characteristic responses of microglia in age-related neurological diseases, such as Alzheimer's (AD) or Parkinson's, is the increase in their numbers. Recent data from our research group indicates that this process of expansion, when repeated over time, drives microglial burn-out, in a process known as replicative senescence. This, in turn, has detrimental effects during the progression of chronic neurodegenerative disease like Alzheimer's. However, we do not fully understand how this process develops, and what are the consequence to the roles that microglia usually undertake in the brain. Most importantly, so far most of the knowledge about these mechanisms derives from the study of rodents, and we lack models that would inform about human-relevant biology. In this proposal we will develop new models in which to study senescence in human microglia, by taking advantage of the culture of induced pluripotent stem cells (iPSCs), which can be turned into any specific cell type of interest. We will convert human iPSCs into human microglia, using validated models thanks to the expertise of Dr Mead and the Oxford Drug Discovery Institute. Once we have obtained these human microglia in a culture dish, we will "wind them up", inducing their increase in numbers, with the expectation that cells will increased replications will become senescent. We will use alternative models to induce senescence, for example using pharmacological agents known to work in others. Once we identify the conditions to induce microglial senescence, we will explore the impact on key house-keeping functions that microglia undertake in order to maintain a normal brain health. These include the ability of microglia to remove (eat) foreign bodies and infectious agents, called phagocytosis, as well as the ability of microglia to engage an inflammatory response to disease. We will check if the changes observed in cultured cells correlate with changes observed in microglia in the brains of patients with AD, thanks to contribution from Prof. Matthews, a leader in the analysis of human microglia at the single-cell level. Once we have identified effective methods to induce senescence in human microglia, and have also explored what functions are modified as a consequence of senescence, we will screen for drugs able to eliminate or revert senescence microglia. This will be achieved thanks to expertise from Prof. Gil, a leader in the field of understanding and targeting senescence. We will screen a large library of compounds, and identify those able to selectively remove senescent microglia, or revert them to their healthy state, without altering non-senescent cells.To address our experimental plan, we will use state-of-the-art techniques, fully enabling our approach to have an impact on the academic community. With the proposed approach, we will break new ground into the understanding of the initial events of age-related brain pathology. We have a plan for translating outcomes of the proposed research into the drug discovery phase, with an ambition to improve the quality of life of patients with chronic neurodegeneration in the future.