Regulation of CD8+ T Cell Homeostatis by IL-4

这项建议将研究IL-4对T细胞稳态和免疫的调节。它将对四个部分进行调查 假设：1)IL-4刺激CD8+T细胞增殖；2)IL-4也刺激非T细胞分化 转化为抑制激活的CD8+T细胞的调节细胞；3)这两个过程的动力学差异 导致IL-4首先增强，然后抑制CD8+T细胞反应；4)这些现象在 CD8+T细胞在健康和疾病中的动态平衡这一假设是基于对小鼠的活体研究 提示：1)IL-4对正常的CD8+T细胞，尤其是记忆性CD8+T细胞的稳态是必不可少的 2)生理浓度的IL-4可显著诱导CD8+T细胞通过 部分依赖Stat6的过程，但更缓慢地降低CD8+T细胞反应和细胞数量 这是一个完全依赖于Stat6的过程。抑制与放大的、激活的 CD11b+Ly6Ghi中性粒细胞群体，已被其他研究人员发现与失活有关 并杀伤活化的CD8+T细胞。我们的假设有三个具体目标。第一个评估 IL-4刺激T细胞活化和存活所需的信号。它将决定 IL-4激活STAT6、STAT5和PI-3K对IL-4促有丝分裂和抗凋亡作用的影响它还将 研究为什么需要IL-4和IL-15来维持记忆中的CD8+T细胞。第二个目标是解决 IL-4-调节细胞的激活。它将鉴定和鉴定由IL-4激活的脾细胞以抑制 并杀死激活的CD8+T细胞；确定激活这些调节细胞所需的IL-4剂量；识别 对它们的激活至关重要的信号通路；确定它们杀死活化T细胞的机制(S) 细胞，并在IL-4抑制细胞毒性移植物对宿主疾病的小鼠模型中评估它们的重要性 (GVHD)。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的效果， 健康与疾病对CD8+T细胞动态平衡的影响为了能够评估我们结果的概括性，这 目的探讨IL-4和IL-13对两种炎症模型小鼠T细胞稳态的影响。 疾病：过敏性呼吸道炎症(哮喘)和Omann综合征；以及三种疾病的小鼠模型 传染病：血吸虫病、疟疾和淋巴细胞性脉络膜脑膜炎病毒感染。每个人 这些模型之所以被选中，是因为它可以提供一些关于IL-4调节T细胞的独特信息 细胞动态平衡和免疫，因为它还可以阐明IL-4调节与疾病的相关性。 拟议的实验将在体内进行，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检测 用流式细胞仪来验证我们的假设。这些研究的结果应该确定IL-4在什么情况下 促进或调节CD8+T细胞反应，并为IL-4和IL-4的潜在用途提供指南 增强或抑制人类适应性或非适应性CD8+T细胞反应的拮抗剂。

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 homeostatsis 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.