Exploring Regulatory T Cell Dysfunction in a Murine Model of Colitis

摘要 本项目的总体目标是进一步了解粘膜免疫系统及其缺陷 导致人类炎症性肠病（IBD）的发病机制。产生了一些 IBD的鼠模型促进了对IBD发病机理的基本机制的研究。 尽管事实上许多IBD的鼠模型是由已知影响IBD的单个蛋白质的缺陷引起的， 白细胞功能，负责疾病的特定自身反应和/或调节细胞群 这些模型中的发病机制仍然未知。我们最近建立了一个IBD的小鼠模型， Wiskott-Aldrich综合征蛋白（WASP）的靶向破坏。WASP仅在 在造血细胞中，它是一种信号分子，调节细胞表面受体向细胞骨架的信号。 这种蛋白质的缺失导致罕见的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%的患者会出现 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 过继转移研究表明，淋巴细胞是必需的，CD4+淋巴细胞就足够了。 结肠炎的发展。与大多数具有Th1偏好的IBD小鼠模型相比，我们 在固有层（LP）淋巴细胞和淋巴细胞中证实了Th2细胞因子偏斜（IL-4和IL-13升高）。 组织中事实上，IL-4是结肠炎发展所必需的，至少是部分必需的。也许，最有趣的是，我们有 最近表明，在WKO中调节性T细胞的发育和功能明显减少， 动物 我们的总体假设是，WKO小鼠中的结肠炎是由内源性nTreg功能障碍引起的， 以及CD4 + T细胞群内的内在T细胞信号传导异常，导致Th2 细胞因子偏移 在这项建议中，我们试图确定结肠炎发展的细胞和分子基础， WKO小鼠的自身免疫性。我们的第一个目的是检验WT nT3的过继转移或 残余突变体WKO nT细胞的扩增将治愈WKO小鼠的慢性结肠炎。我们的第二个目标是 负责WKO小鼠中异常nTreg发育和功能障碍的机制。我们 第三个目的是评估WKO CD4+效应T细胞中细胞因子偏移的分子基础及其在WKO CD4+效应T细胞中的作用。 疾病发展。 这项建议的总体目标是进一步了解WKO小鼠结肠炎的机制， 与严重的调节性T细胞缺陷和Th2细胞因子偏斜唯一相关， 这是唯一具有人类相关性的结肠炎鼠模型的优点。我们的驱动前提是， 知识将不仅有助于理解和治疗衰弱性自身免疫（和IBD样 疾病），这是人类免疫缺陷的特征，但也将有助于我们了解粘膜免疫缺陷。 免疫调节和炎症性肠病的分子基础。

ABSTRACT 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 intrinisic nTreg dysfunction as well as intrinsic T cell signaling abnormalities within the CD4+ T cell population that leads to Th2 cytokine skewing. In this proposal we seek to determine the cellular and molecular basis for colitis development and autoimmunity in WKO mice. Our first aim is to test the hypothesis that adoptive transfer of WT nTregs or expansion of residual mutant WKO nTregs will cure chronic colitis of WKO mice. Our second aim is to dissect the mechanism(s) that are responsible for the aberrant nTreg development and dysfunction in WKO mice. Our third aim is to evaluate the molecular basis for cytokine skewing in WKO CD4+ effector T cells and its role in disease development. 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.