Regulation of CD8+ T Cell Homeostatis by IL-4

描述（由申请人提供）： 本研究拟探讨IL-4对T细胞稳态和免疫的调节作用。本研究将探讨IL-4刺激CD 8 + T细胞增殖、IL-4也刺激非T细胞分化为抑制活化的CD 8 + T细胞的调节性细胞、IL-4在这两个过程中的动力学差异导致IL-4先增强后抑制CD 8 + T细胞应答的四部分假说。以及4）这些现象在健康和疾病中的CD 8 + T细胞稳态中是重要的。该假设基于体内小鼠研究，其证明：1）IL-4对于正常的CD 8 + T细胞稳态，特别是记忆性CD 8 + T细胞稳态是必需的;和2）生理浓度的IL-4通过部分Stat 6依赖性过程急性诱导CD 8 + T细胞增殖，但通过完全Stat 6依赖性过程更缓慢地降低CD 8 + T细胞应答和细胞数量。抑制与CD 11b + Ly 6 Ghi中性粒细胞的扩大、活化群体的出现相关，其他研究者认为这与活化的CD 8 + T细胞的失活和杀伤有关。我们的假设在3个具体目标中得到解决。第一个评估IL-4刺激T细胞活化和存活的信号传导要求。它将确定IL-4激活Stat 6、Stat 5和PI-3 K对于IL-4的促有丝分裂和抗凋亡作用的重要性。它还将研究为什么IL-4和IL-15都需要维持记忆CD 8 + T细胞。第二个目的是解决调节细胞的IL-4活化。它将识别和表征由IL-4激活的脾细胞以抑制和杀死活化的CD 8 + T细胞;确定激活这些调节细胞所需的IL-4剂量;识别对其激活重要的信号通路;鉴定它们杀死活化T细胞的机制，并评估它们在IL-4抑制细胞毒性移植物抗宿主病（GVHD）的小鼠模型中的重要性。第三个目标将评估内源性产生的IL-4和相关细胞因子IL-13对健康和疾病中CD 8 + T细胞稳态的影响。为了评估我们的研究结果的普遍性，本研究将研究IL-4和IL-13对两种炎症性疾病小鼠模型T细胞稳态的影响：过敏性气道炎症（哮喘）和Omann综合征;和三种感染性疾病小鼠模型：血吸虫病，疟疾和淋巴细胞性脉络丛脑膜炎病毒（LCMV）感染。选择这些模型中的每一个是因为它可以提供关于IL-4调节T细胞稳态和免疫的一些独特信息，并且因为它还可以阐明IL-4调节的疾病相关性。将在体内进行拟议的实验，并使用转基因小鼠，重组细胞因子，单克隆抗体，细胞转移系统，CFSE标记，BrdU掺入，体内细胞因子产生和流式细胞术的测定来检验我们的假设。这些研究的结果应该确定IL-4促进或调节CD 8 + T细胞应答的情况，并为IL-4和IL-4拮抗剂用于扩增或抑制人类适应性或适应不良的CD 8 + T细胞应答的潜在用途提供指导。T细胞介导的免疫力是保护人们免受感染因子（包括大多数细菌、病毒、真菌、原生动物和蠕虫）侵害所必需的。而且还导致免疫介导的疾病，例如哮喘。该项目将研究IL-4，一种由免疫系统产生的蛋白质，如何调节T细胞的数量和功能，特别是在健康和疾病中记忆CD 8 + T细胞的数量和功能。这些研究的结果应确定IL-4促进或下调CD 8 + T细胞应答的情况，并为IL-4和IL-4拮抗剂用于增加或减少人类适应性或适应不良的CD 8 + T细胞应答的潜在用途提供指导。

DESCRIPTION (provided by applicant): This proposal will study IL-4 regulation of T cell homeostasis and immunity. It will investigate the four part hypothesis that: 1) IL-4 stimulates CD8+ T cells to proliferate; 2) IL-4 also stimulates non-T cells to differentiate into regulatory cells that suppress activated CD8+ T cells; 3) differences in the kinetics of these two processes cause IL-4 to first enhance, then suppress CD8+ T cell responses; and 4) these phenomena are important in CD8+ T cell homeostasis in health and disease. This hypothesis is based on in vivo mouse studies that demonstrate that: 1) IL-4 is essential for normal CD8+ T cell homeostasis, especially memory CD8+ T cell homeostasis; and 2) physiological concentrations of IL-4 acutely induce CD8+ T cells to proliferate through a partially Stat6-dependent process but more slowly decrease CD8+ T cell responses and cell number through an entirely Stat6-dependent process. Suppression is associated with the appearance of an enlarged, activated population of CD11b+Ly6Ghi neutrophils, which have been implicated by other investigators in the inactivation and killing of activated CD8+ T cells. Our hypothesis is addressed in 3 specific aims. The first evaluates signaling requirements for IL-4 stimulation of T cell activation and survival. It will determine the importance of IL-4 activation of Stat6, Stat5, and PI-3K for the mitogenic and anti-apoptotic effects of IL-4. It will also investigate why both IL-4 and IL-15 are required to maintain memory CD8+ T cells. The second aim addresses IL-4-activation of regulatory cells. It will identify and characterize the spleen cells activated by IL-4 to suppress and kill activated CD8+ T cells; determine the dose of IL-4 required to activate these regulatory cells; identify the signaling pathways important for their activation; identify the mechanism(s) by which they kill activated T cells, and evaluate their importance in a mouse model in which IL-4 suppresses cytotoxic graft vs. host disease (GVHD). The third aim will evaluate the effects of endogenously-produced IL-4 and a related cytokine, IL-13, on CD8+ T cell homeostasis in health and disease. To allow evaluation of the generalizability of our results, this aim will examine the effects of IL-4 and IL-13 on T cell homeostasis in mouse models of two inflammatory disorders: allergic airway inflammation (asthma) and Omann's syndrome; and mouse models of three infectious diseases: schistosomiasis, malaria, and lymphocytic choriomeningitis virus (LCMV) infection. Each of these models has been chosen because it can provide some unique information about IL-4 regulation of T cell homeostasis and immunity and because it also can shed light on the disease-relevance of IL-4 regulation. Proposed experiments will be performed in vivo and use transgenic mice, recombinant cytokines, monoclonal antibodies, cell transfer systems, CFSE labeling, BrdU incorporation, assays of in vivo cytokine production and flow cytometry to test our hypothesis. Results of these studies should identify the circumstances in which IL-4 promotes or regulates CD8+ T cell responses and provide a guide to the potential uses of IL-4 and IL-4 antagonists for amplifying or suppressing adaptive or maladaptive CD8+ T cell responses in humans.T cell-mediated immunity is required to protect people against infectious agents, including most bacteria, viruses, fungi, protozoa, and worms, but also contributes to immune-mediated disorders, such as asthma. This project will study how IL-4, a protein produced by the immune system, regulates T cell numbers and function, especially the numbers and function of memory CD8+ T cells, in health and disease. The results of these studies should identify the circumstances in which IL-4 promotes or downregulates CD8+ T cell responses and provide a guide to the potential use of IL-4 and IL-4 antagonists for increasing or decreasing adaptive or maladaptive CD8+ T cell responses in humans.