Mechanisms of capillary-associated microglial interactions

项目摘要 与其他器官相比，大脑需要大量的能量。这种高能量需求得到满足 通过密集的血管网络输送氧气和营养物质， 产品.因此，神经血管和脑细胞之间的相互作用是重要的。而 已经做了大量的工作来阐明星形胶质细胞和周细胞对血管完整性的贡献， 已经做了工作来理解小胶质细胞与脉管系统的相互作用。 多种证据表明，小胶质细胞促进生命早期血管系统的发育， 受伤或患病后。然而，小胶质细胞与血管系统相互作用的程度在 体内平衡尚未得到充分阐明。作为常驻免疫细胞，小胶质细胞是大脑的第一道防线， 防御，它们可能有助于检测循环中的病原体或异常，但这 可能需要与脉管系统稳定的物理相互作用。在我们的初步研究中， 项目，我们使用体内双光子和电子显微镜的方法来记录强大的物理 小胶质细胞胞体亚群与脑内微血管（毛细血管）之间的相互作用 区域和大脑年龄。值得注意的是，即使用药物消除和随后的再增殖， 小胶质细胞，这些毛细血管相关的小胶质细胞（CAM）的密度保持，表明毛细血管 关联是小胶质细胞在脑中驻留的关键特征。在我们建议的研究中，我们将：（1） 试图通过形态学，功能和 转录的方法;和（2）测试的假设，即CAM的相互作用，促进嘌呤释放 来自通过P2 Y12受体感应募集小胶质细胞的内皮泛连接蛋白。该项目是第一个 彻底表征毛细血管相关的小胶质细胞，并阐明显著的分子机制， 这些相互作用，以了解小胶质细胞血管的相互作用，在稳态。

Project Summary The brain requires a significant amount of energy compared to other organs. This high energy demand is met by a dense network of blood vessel that deliver oxygen and nutrients and facilitates the removal of waste products. Therefore, the interactions between the neurovasculature and brain cells are important. While extensive work has been done to elucidate contributions by astrocytes and pericytes to vascular integrity, less work has been done to understand microglial interactions with the vasculature. Multiple lines of evidence suggest that microglia facilitate the development of the vasculature early in life and following injury or in disease. However, the extent of microglial interactions with the vasculature in homeostasis has not been adequately clarified. As resident immune cells, microglia are the brain’s first line of defense and it is possible that they could help detect pathogens or abnormalities in the circulation, but this would perhaps require stable physical interactions with the vasculature. In our preliminary studies for this project, we used in vivo two photon and electron microscopy approaches to document robust physical interactions between a subpopulation of microglial somata and the microvasculature (capillaries) across brain regions and brain age. Remarkably, even with pharmacological elimination and subsequent repopulation of microglia, the density of these capillary-associated microglia (CAM) was maintained suggesting that capillary association is a critical feature of microglial residence in the brain. In our proposed studies, we will: (1) attempt to differentiate CAMs from parenchymal microglia by using morphological, functional and transcriptional approaches; and (2) test the hypothesis that CAM interactions are facilitated by purine release from endothelial pannexins that recruit microglia through P2Y12 receptor sensing. This project is a first to thoroughly characterize capillary associated microglia and elucidate salient molecular mechanisms governing these interactions to understand microglia-vascular interactions in homeostasis.