Opposing Roles for Microglia in the Young and Aged Neurogenic Niche

项目摘要 神经干细胞/祖细胞可分化为成熟神经元、星形胶质细胞和少突胶质细胞 在一生中。然而，神经发生在衰老过程中迅速下降，其机制 年龄依赖性神经干细胞功能障碍尚不清楚。室-室下区(V- (SVZ)是小鼠中最大的神经干细胞库的所在地 大脑。我们已经发现，小胶质细胞，大脑的先天免疫细胞，显著地 定位于年轻和老年的V-SVZ利基市场。在衰老过程中，小胶质细胞经历了 形态和表型从静息状态转变为促炎状态。 初步数据表明，年轻小胶质细胞分泌的分子支持增殖和 神经细胞的体外分化。相反，从衰老小鼠分离的小胶质细胞似乎丢失了 这对体外增殖有影响。总而言之，这些数据表明，小胶质细胞在关键年龄发挥作用- 在调节神经发生中的依赖作用。尽管已知小胶质细胞在 神经母细胞的吞噬作用及其对B型神经干细胞、C型转运的影响 放大细胞和利基细胞结构基本上是未知的。使用三维图像 分析利基细胞结构和流式细胞分选(FACS)，我们将测试 小胶质细胞在年轻人和老年人的神经源性小生境中扮演相反角色的假说。 在目标1中，我们将从药物和基因上耗尽年轻神经源性细胞中的小胶质细胞 利基和讯问对神经发生、B、C型和神经母细胞存活的影响 以及血管间隔附近的数量、增殖和位置。在目标2中，我们将使用 异时输注年轻和老年小胶质细胞的分泌分子直接检测 这些分子在神经发生中扮演着相反的角色。在目标3中，我们将测试是否缓解 老年小胶质细胞的炎性表型可恢复神经干/祖细胞的功能。我们会 也探索小胶质细胞来源的分泌分子的新候选分子，这些分子支持 或阻碍神经发生。了解小胶质细胞激活状态是如何调节的 神经发生将产生深远的后果。人们普遍认为，V-SVZ神经 干细胞及其后代有助于大脑修复。因此，理解小胶质细胞是如何 在组织动态平衡和衰老过程中促进神经发生不仅会促进我们的基本 了解神经发生，但将有助于实现使用神经干细胞/祖细胞的最终目标 脑部治疗中的细胞。

Project Summary Neural stem cell/progenitors cells give rise to mature neurons, astrocytes and oligodendrocytes throughout life. However, neurogenesis rapidly declines during aging and the mechanism for age-dependent neural stem cell dysfunction is not clear. The ventricular-subventricular zone (V- SVZ), lining the lateral ventricle, is home to the largest pool of neural stem cells in the murine brain. We have found that microglia, the innate immune cells of the brain, are prominently positioned throughout the young and aged V-SVZ niche. During aging, microglia undergo a morphological and phenotypical shift from a resting state to a pro-inflammatory state. Preliminary data suggest that secreted molecules from young microglia support proliferation and neuronal differentiation in vitro. In contrast, microglia isolated from aged mice appear to lose this influence on proliferation in vitro. Together, these data suggest microglia play a critical age- dependent role in regulating neurogenesis. Although microglia are known to be important in phagocytosis of neuroblasts, their influence on type B neural stem cells, type C transit amplifying cells and niche cytoarchitecture is essentially unknown. Using 3-dimensional image analysis of niche cytoarchitecture and flow activated cell sorting (FACS), we will test the hypothesis that microglia have opposing roles in the young and aged neurogenic niche. In aim 1, we will pharmacologically and genetically deplete microglia from the young neurogenic niche and interrogate the impact on neurogenesis, Type B, C and neuroblast cell survival as well as number, proliferation and position near the vascular compartment. In aim 2, we will use heterochronic infusion of secreted molecules from young and aged microglia to directly test if these molecules have opposing roles in neurogenesis. In aim 3, we will test if mitigating the inflammatory phenotype of aged microglia restores neural stem/progenitor cell function. We will also explore novel molecular candidates for microglia derived secreted molecules that support or hinder neurogenesis. Understanding how the microglia activation state regulates neurogenesis will have far-reaching consequences. It is widely accepted that V-SVZ neural stem cells and their progeny contribute to brain repair. Thus, understanding how microglia contribute to neurogenesis during tissue homeostasis and aging will not only further our basic understanding of neurogenesis but will help in the eventual goal of using neural stem/progenitor cells in brain therapeutics.