Exploring Regulatory T Cell Dysfunction in a Murine Model of Colitis

描述（由申请人提供）：该项目的总体目标是进一步了解粘膜免疫系统和导致人类炎症性肠病（IBD）发病的缺陷。许多IBD小鼠模型的产生促进了对IBD发病的基本机制的研究。尽管许多小鼠IBD模型是由已知影响白细胞功能的单一蛋白质缺陷引起的，但在这些模型中，负责疾病发病的特定自身反应性和/或调节性细胞群仍然未知。我们最近建立了一个IBD小鼠模型，该模型是通过靶向破坏Wiskott-Aldrich综合征蛋白（WASP）而产生的。WASP仅在造血细胞中表达，是一种调节细胞表面受体向细胞骨架传递信号的信号分子。这种蛋白质的异常导致罕见的x连锁原发性免疫缺陷，并以其命名。自身免疫通常与这种免疫缺陷有关，高达10%的患者发展为ibd样疾病。我们的实验室最近表明，100%的WASP KO （WKO）小鼠也会发生结肠炎。遗传和过继性转移研究表明，淋巴细胞是结肠炎发展的必要条件，CD4+淋巴细胞是足够的。与大多数具有Th1偏倚的IBD小鼠模型相反，我们已经证明在固有层（LP）淋巴细胞和组织中存在Th2细胞因子偏倚（与IL-4和IL-13升高）。事实上，至少在结肠炎的发展过程中，IL-4是必需的。也许，最有趣的是，我们最近表明，在WKO动物中，调节性T细胞的发育和功能显着减少。我们的总体假设是，WKO小鼠的结肠炎是由固有的Treg功能障碍和CD4+ T细胞/APC群体中导致Treg功能障碍的外源性信号/细胞因子异常引起的。在这个提议中，我们试图确定WKO小鼠结肠炎发展和自身免疫的细胞和分子基础。目的1旨在揭示WKO小鼠异常Treg发育和功能障碍的机制（发育、迁移和细胞-细胞接触）。目的2旨在评估先天免疫细胞中WASP缺乏对Tregs产生和功能的影响。目的3旨在确定wasp依赖性T细胞受体（TCR）信号传导和异常细胞因子分泌在Treg功能障碍中的作用。该建议的总体目标是进一步了解WKO小鼠结肠炎的机制，该机制与深度调节性T细胞缺陷和Th2细胞因子偏斜具有独特的相关性，并利用具有独特的人类相关性的小鼠结肠炎模型。我们的驱动前提是，这些知识不仅有助于理解和治疗以人类免疫缺陷为特征的衰弱性自身免疫（和ibd样疾病），还有助于我们理解粘膜免疫调节和炎症性肠病的分子基础。

DESCRIPTION (provided by applicant): The overall goal of this project is to gain further understanding of the mucosal immune system and the defects that contribute to the pathogenesis of human inflammatory bowel disease (IBD). The generation of a number of murine models of IBD has facilitated investigation into the basic mechanisms underlying IBD pathogenesis. Despite the fact that many murine models of IBD result from a defect in a single protein known to affect leukocyte function, the specific auto-reactive and/or regulatory cell population responsible for disease pathogenesis in these models remains unknown. We recently generated a mouse model of IBD that results from the targeted disruption of the Wiskott-Aldrich syndrome protein (WASP). WASP is expressed solely in hematopoietic cells and is a signaling molecule that regulates cell surface receptor signals to the cytoskeleton. Abnormalities in this protein lead to the rare X-linked primary immunodeficiency that carries its name. Autoimmunity is commonly associated with this immunodeficiency, and up to 10 percent of patients develop an IBD-like illness. Our lab has recently shown that 100% of WASP KO (WKO) mice also develop colitis. Genetic and adoptive transfer studies have shown that lymphocytes are essential and CD4+ lymphocytes are sufficient for colitis development. In contrast with most murine models of IBD that have a Th1 bias, we have demonstrated a Th2 cytokine skewing (with elevated IL-4 and IL-13) in lamina propria (LP) lymphocytes and in tissues. Indeed, IL-4 is required, at least in part, for colitis development. Perhaps, most interestingly, we have recently shown that there is marked reduction in the development and function of regulatory T cells in WKO animals. Our overall hypothesis is that the colitis in WKO mice results from both intrinsic Treg dysfunction as well as extrinsic signaling/cytokine abnormalities within the CD4+ T cell/APC population that results in Treg dysfunction. In this proposal we seek to determine the cellular and molecular basis for colitis development and autoimmunity in WKO mice. Aim 1 seeks to uncover the mechanism(s) (development, migration, and cell-cell contacts) that are responsible for the aberrant Treg development and dysfunction in WKO mice. Aim 2 seeks to assess the impact of WASP deficiency in innate immune cells on the generation and function of Tregs. Aim 3 seeks to determine the role of WASP-dependant T cell receptor (TCR) signaling and aberrant cytokine secretion on Treg dysfunction. The overall goal of this proposal is to further our understanding of the mechanism of colitis in WKO mice that is uniquely associated with both profound regulatory T cell defects and Th2 cytokine skewing and to take advantage of a murine model of colitis that uniquely has a human correlate. Our driving premise is that such knowledge will not only aid in the understanding and treatment of the debilitating autoimmunity (and IBD-like illness) that characterizes the human immunodeficiency but will also aid in our understanding of mucosal immune regulation in general and the molecular underpinnings of inflammatory bowel disease.