IMMUNOMODULATORY STRATEGIES IN AUTOIMMUNE GASTRITIS

许多自身免疫性疾病似乎是由抗原特异性T细胞介导的，这些T细胞产生促炎细胞因子IFNGamma和TNFpha。开发一种策略，在不干扰其他免疫功能的情况下，专门下调或消除这些自身反应性T细胞，将是非常有价值的。这项拨款提案的目的是研究两种策略所涉及的机制，这两种策略旨在特定地下调抗原特异性T细胞的活性，并在具有良好特征的自身免疫性疾病的小鼠模型中测试这些策略。先前的研究表明，在TGFbeta2存在的情况下，抗原提呈细胞(APC)在TGFbeta2存在的情况下，通过静脉注射到幼小鼠体内，向外周免疫系统传递强大的耐受诱导信号。越来越多的证据表明，在这个系统中，CD4和CD8调节性T细胞被诱导并介导抗原特异性耐受。第一个特定目标的目标是了解转化生长因子β处理的APC诱导耐受的机制。为此，调节性T细胞在这一耐受系统中所起的作用以及它们的一般作用机制(S)将在体内研究中进行，使用的是基因敲除小鼠、中和抗体和TCRT细胞转移系统。进一步的研究将涉及对调节性T细胞用来下调效应器T细胞功能的精确机制的体外分析。第二个特定目标的目标是利用小鼠自身免疫性胃炎模型来研究转化生长因子β治疗APC的治疗潜力。BALB/c小鼠的新生胸腺切除(TX-3)诱导了一种明显类似于人类恶性贫血的自身免疫性胃炎。在这个模型中，T细胞的反应被很好地描述，并且是Th1型细胞因子介导的，并且靶向于壁细胞H/K-ATPase的α和β亚基。这个目的是为了确定用ATPase脉冲的TGFbeta处理的APC治疗TX-3小鼠是否可以“治愈”或改善自身免疫性胃炎，并表征与这种治疗相关的T细胞反应。第三个特定目标的目标是探索表达FasL的APC独立治疗自身免疫性疾病的能力，或作为TGFbeta治疗APC治疗的补充。这一目的旨在表征活化的T细胞通过基因工程表达FasL的抗原冲击的APC在体内被靶向消除后的T细胞反应。这一策略可与经转化生长因子β治疗的APC联合使用，成功治疗已建立的自身免疫性疾病。

Many autoimmune diseases appear to be mediated by antigen-specific T cells that produce the pro-inflammatory cytokines, IFNgamma and TNFalpha. It would be of great value to develop a strategy to specifically downregulate or eliminate these autoreactive T cells without interfering with other immune functions. The goal of this grant proposal is to study the mechanisms that are involved in two strategies designed to specifically downregulate the activity of antigen-specific T cells and to test these strategies in a well-characterized murine model of autoimmune disease. Previous studies have demonstrated that antigen presenting cells (APCs) pulsed with antigen in the presence of TGFbeta2 transmit a potent tolerance-inducing signal to the peripheral immune system when injected intravenously into naive mice. Accumulating evidence suggests that CD4 and CD8 regulatory T cells are induced and mediate antigen-specific tolerance in this system. The goal of the first specific aim is to understand the mechanisms involved in tolerance induced by TGFbeta-treated APCs. In this aim, the role that regulatory T cells play in this system of tolerance as well as their general mechanism(s) of action will be examined in in vivo studies using knock-out mice, neutralizing antibodies and a TCR transgenic T cell transfer system. Further studies will involve in vitro analyses of the precise mechanisms utilized by regulatory T cells to downregulate effector T cell function. The goal of the second specific aim is to investigate the therapeutic potential of TGFbeta-treated APCs using a murine model of autoimmune gastritis. Neonatal thymectomy (Tx-3) in BALB/c mice induces an autoimmune gastritis that markedly resembles human pernicious anemia. Tile T cell response has been well characterized in this model and is Th1-type cytokine-mediated and targeted to the alpha and beta subunits of H/K ATPase of parietal cells. This aim is designed to determine whether treatment of Tx-3 mice with ATPase-pulsed TGFbeta-treated APCs can "cure" or ameliorate autoimmune gastritis and to characterize the T cell response that is associated with this treatment. The goal of the third specific aim is to explore the ability of FasL-expressing APCs to treat autoimmune disease either independently or as a supplement to treatment with TGFbeta-treated APCs. This aim is designed to characterize the T cell response after activated T cells have been targeted for elimination in vivo by treatment with antigen-pulsed APCs genetically engineered to express FasL. This strategy may be used in conjunction with TGFbeta-treated APCs to successfully treat established autoimmune disease.