T cells in the aging brain

总结 该项目的首要目标是了解免疫细胞如何在衰老过程中影响大脑， 目的是恢复老年大脑功能。长期以来，大脑一直被认为是“免疫特权器官”。 然而，最近的研究表明，免疫细胞在神经退行性疾病中浸润大脑， 老年痴呆症和衰老的过程中。剩下的一个关键挑战是了解免疫细胞如何影响 大脑在衰老过程中的作用，以及这些知识是否可以用于恢复老年大脑的功能和治疗 神经退行性疾病 成人大脑的脑室下区（SVZ）为解决这个问题提供了一个很好的范例，因为 脑的再生区域包含许多不同的细胞类型-神经干细胞（NSC），内皮细胞， 小胶质细胞-并在衰老过程中表现出明显的功能衰退。为了获得对变化的单细胞理解， 我们最近对年轻人和老年人进行了单细胞RNA测序， 神经原性小生境。这项分析显示，只有在老年人中，细胞毒性T细胞的浸润才是惊人的。 神经原性生态位，这是由免疫荧光证实。令人惊讶的是，我们发现老年人的T细胞 SVZ克隆扩增并分泌干扰素g（IFNg），表明它们遇到了特异性的 抗原我们还表明，T细胞可以在共培养物和体内损害NSC增殖。基于 根据这些数据，我们的具体假设是，老年人大脑中的T细胞克隆扩增导致了大脑功能的恶化。 随着年龄的增长，神经原性的小生境，并阻止这种T细胞的扩张恢复功能，旧的神经原性区域。 探索这一想法对于对抗衰老和神经退行性疾病期间大脑功能的下降至关重要。 疾病，如阿尔茨海默病。为了验证我们的假设，我们提出了以下实验： 1.确定T细胞如何渗入老年人的神经原性龛; 2.了解T细胞对老年神经原性小生境的功能影响; 3.研究免疫细胞和神经原性小生境之间的相互作用， 个体 这些目标的完成将为T细胞和其他细胞因子的调节提供独特的机制见解。 免疫细胞在老化过程中在大脑的再生龛。这项工作还应提供一个基本的 了解干扰素应答和T细胞细胞毒性对不同细胞类型的机制影响 在大脑中。我们研究中的知识应该为制定变革战略铺平道路，包括 新的免疫疗法，用于恢复原始组织，这将是改善大脑的关键一步。 在衰老和与年龄有关的疾病，如阿尔茨海默氏病。

SUMMARY The overarching goal of this project is to understand how immune cells impact the brain during aging, with the objective of restoring old brain function. The brain has long been considered an ‘immuno-privileged organ’. However, recent studies have shown that immune cells infiltrate the brain in neurodegenerative diseases such as Alzheimer’s disease and during aging. A key remaining challenge is to understand how immune cells impact the brain during aging, and could this knowledge be used to restore functionality of old brain and treat neurodegenerative diseases? The subventricular zone (SVZ) of the adult brain provides a great paradigm to address this question, as this regenerative region of the brain contains many different cell types – neural stem cells (NSCs), endothelial cells, microglia – and exhibits clear functional decline during aging. To gain a single cell understanding of the changes that occur with age in neurogenic niches, we recently performed single cell RNA-sequencing of young and old neurogenic niches in mice. This analysis revealed a striking infiltration of cytotoxic T cells only in the old neurogenic niche, which was confirmed by immunofluorescence. Surprisingly, we found that T cells from old SVZs are clonally expanded and secrete interferon g (IFNg), suggesting that they have encountered specific antigens. We also showed that T cells can impair NSC proliferation both in co-cultures and in vivo. Based on these data, our specific hypothesis is that T cell clonal expansion in old brains drives the deterioration of the neurogenic niche with age, and that preventing this T cell expansion restores function to old neurogenic regions. Probing this idea would be critical to counter the decline in brain function during aging and neurodegenerative diseases, such as Alzheimer’s disease. To test our hypothesis, we propose the following experiments: 1. To determine how T cells infiltrate neurogenic niches in old individuals; 2. To understand the functional impact of T cells on old neurogenic niches; 3. To examine the interaction between immune cells and neurogenic niches in young, old, and rejuvenated individuals. Completion of these aims will provide unique mechanistic insights into the regulation of T cell and other immune cells during aging in regenerative niches of the brain. This work should also give a fundamental understanding of the mechanistic impact of the interferon response and T cell cytotoxicity on different cell types in the brain. Knowledge from our study should pave the way for building transformative strategies, including new immunotherapies, for the restoration of a pristine tissue, which will be a critical step for improving brain function during aging and age-related diseases such as Alzheimer’s disease.