Trafficking and Function of Central Nervous System Resident Regulatory T Cells

描述（由申请人提供）：中枢神经系统（CNS）代表免疫特权的部位。限制免疫介导病理的可能性被认为是维持这种敏感组织的功能和寿命的关键，特别是考虑到其有限的再生能力。然而，免疫系统的细胞是在稳态条件下在中枢神经系统内发现的。调节性T （Treg）细胞是一种抑制性免疫细胞群，通过阻止潜在致病性免疫反应的激活而起作用。这些细胞在许多组织中的稳态条件下发挥关键作用，以预防人类和小鼠的自身免疫性疾病和死亡。我们在稳态条件下观察了中枢神经系统组织中的Treg细胞，并在此提出评估其在稳定状态和西尼罗病毒（WNV）神经致病性感染期间在该组织中的功能。为此，我们将利用我们实验室开发的几种遗传小鼠模型，这些模型允许在体内鉴定、分离和特异性消融Treg细胞，以及设计模型来阻止它们进入中枢神经系统。中枢神经系统内的Treg细胞将通过表型标记和流式细胞术的免疫荧光标记进行表征，并评估其归巢到该组织所必需的分子表达。使用在Treg细胞中表达人类白喉毒素（DT）受体的小鼠，我将使用白喉毒素来消耗Treg细胞，并通过评估效应免疫细胞的表型和活性来检查CNS病理组织学。此外，Treg细胞在CNS归巢分子中特异性缺失的小鼠，以及将缺乏CNS归巢分子的小鼠的Treg细胞转移到T细胞缺陷的小鼠中，通过特异性地阻止Treg细胞进入该组织，来检测Treg细胞在CNS中的功能。最后，我们观察到西尼罗河病毒感染小鼠的中枢神经系统中有Treg细胞的积累，并且知道这种病毒从中枢神经系统的清除是一个T细胞依赖的过程。因此，我们将评估感染WNV小鼠中枢神经系统内Treg细胞进入的动力学及其表型，并通过感染携带缺乏中枢神经系统归巢分子的Treg细胞的小鼠来探究这种进入的机制。总之，这些实验将描述在稳态条件下Treg细胞进入中枢神经系统的功能和机制，以及这些细胞在中枢神经系统病毒免疫中的作用。

DESCRIPTION (provided by applicant): The central nervous system (CNS) represents a site of immune privilege. Limiting the potential for immune mediated pathology is thought to be critical for maintained function and longevity of this sensitive tissue especially given its limited regenerative capacity. However, cells of the immune system are found within the CNS under homeostatic conditions. Regulatory T (Treg) cells are a suppressive population of immune cells that act by preventing activation of potentially pathogenic immune responses. These cells function critically under homeostatic conditions in a number of tissues to prevent autoimmune disease and death in humans and mice. We have observed Treg cells within the CNS tissue under homeostatic conditions and herein propose to evaluate their function in this tissue in the steady state and during neuropathogenic infection with West Nile virus (WNV). For this purpose, we will utilize several genetic mouse models developed in our laboratory, which allow for identification, isolation and specific ablation of Treg cells in vivo, as well as models designed to prevent their entry into the CNS. Treg cells within the CNS will be characterized by immunofluorescent labeling of phenotypic markers and flow cytometery and evaluated for expression of molecules essential for their homing to this tissue. Using mice that express the human diphtheria toxin (DT) receptor exclusively in Treg cells, I will use diphtheria toxin to deplete Treg cells and examine CNS pathology histological and via evaluation of effector immune cell phenotype and activity. In addition, the function of Treg cells in the CNS will be examined by specifically precluding their entry into this tissue using mice with Treg cell specific deficiency in CNS homing molecules and transfer of Treg cells from mice lacking CNS homing molecules into T cell deficient mice. Lastly, we have observed accumulation of Treg cells within the CNS of WNV infected mice and it is know that clearance of this virus from the CNS is a T cell dependent process. Thus, the dynamics of Treg cell entry and their phenotype within the CNS of mice infected with WNV will be evaluated and the mechanism of this entry will be interrogated through infection of mice harboring Treg cells lacking in CNS homing molecules. Together, these experiments will characterize the function and mechanism of entry of Treg cells within the CNS under homeostatic conditions and the role for these cells in CNS viral immunity.