PKCtheta-CD28 interaction: A novel drug target for autoimmunity and inflammation

描述(申请人提供)：大约5000万美国人患有大约100种已知的自身免疫性疾病(例如，I型糖尿病、克罗恩病和类风湿性关节炎)。这些研究集中在蛋白激酶C-θ和CD28之间的相互作用对免疫应答的不同方面的影响及其在治疗自身免疫性和炎症性疾病方面的意义。蛋白激酶Cθ是一种钙依赖性蛋白激酶C家族成员，在T细胞中表达最丰富，其在T细胞激活和存活中的关键作用已被充分证实。体内研究揭示了PKCθ在不同免疫类型中的选择性作用。特别是最近的一项研究表明，与T效应细胞形成鲜明对比的是，PKCθ被排除在诱导的调节性T细胞的免疫突触(IS)之外，而且它抑制了它们的抑制功能。这些发现表明，PKCθ作为T细胞介导的自身免疫和炎症的免疫抑制的选择性药物靶点前景看好。我的初步数据显示，通过不同的策略阻断蛋白激酶Cθ-CD28的结合促进了Treg细胞的分化和抑制功能。在这里，我将验证一种假设，即阻断PKCθ-CD28相互作用抑制致病T细胞的分化和活性，促进Treg细胞的功能，从而实现有益的协同作用，对抗T细胞介导的自身免疫和炎症反应。我将使用两个新颖且高度特异的辅助工具，即i)通过一个显性的负PKCθV3突变体来阻断可诱导的PKCθ-CD28相互作用；以及ii)由我们的合作者产生的小分子变构化合物，我发现它们可以抑制这种相互作用。在目标1中，我将分析这些策略在体外对T细胞和T细胞分化和功能的影响，在目标2中，我将评估阻断PKCθ-CD28相互作用对实验性慢性结肠炎疾病模型的影响。本项目的结果将揭示从CD2 8和IS中分离PKCθ对Treg和Tef分化和功能的影响，并揭示一种有前景的治疗T细胞介导的实验性炎症性疾病的新方法，即Th17介导的结肠炎。总而言之，这项研究很可能为开发新的、高度选择性的治疗策略来治疗T细胞介导的自身免疫和炎症铺平道路。该项目与NIAID的使命完美契合，该使命旨在开展和支持研究过敏、免疫和传染病的原因，并开发更好的预防、诊断和治疗这些疾病的方法。同时，该项目也与NIDDK的任务密切相关，因为它将研究阻断PKCθ-CD28相互作用对实验性慢性结肠炎模型的影响。

DESCRIPTION (provided by applicant): Approximately 50 million Americans suffer from ~100 known autoimmune diseases (e.g., type I diabetes, Crohn's disease, and rheumatoid arthritis). The proposed studies focus on the impact of a novel TCR-induced interaction between protein kinase C-theta (PKCθ) and CD28 on different aspects of immune responses and its implication for treating autoimmune and inflammatory diseases. PKCθ is a Ca2+-independent PKC family member that is most abundantly expressed in T cells, and its critical role in conventional T cell activation and survival has been well documented. In vivo studies revealed the selective role of PKCθ in different types of immunity. In particular, a recent study showed that in sharp contrast to T effector (Teff) cells, PKCθ is excluded from the immunological synapse (IS) of induced regulatory T (iTreg) cells and, moreover, it inhibits their suppressive function. These findings point to the high promise of PKCθ as a selective drug target for immunosuppression of T cell-mediated autoimmunity and inflammation. My preliminary data demonstrated that blocking the PKCθ-CD28 association by different strategies promoted the differentiation and suppressive function of Treg cells. Here, I will test the hypothesis that blockade of the PKCθ-CD28 interaction inhibits the differentiation and activity of pathogenic T cells and promotes the functin of Treg cells, thereby achieving a beneficial synergetic effect against T cell-mediated autoimmune and inflammatory responses. I will use two novel and highly specific complementary tools, i.e., i) blockade of the inducible PKCθ-CD28 interaction by a dominant negative PKCθ V3-based mutant; and ii) small molecule allosteric compounds generated by our collaborators that I found to inhibit this interaction. In Aim 1, I will analyze the effect of thes strategies on Teff and Treg differentiation and function in vitro, and in Aim 2, I will evaluate th impact of blocking the PKCθ-CD28 interaction on an experimental disease model of chronic colitis in mice. The results of this project will reveal the effects of sequestering PKCθ from CD28 and the IS on Treg and Teff differentiation and function and uncover a promising novel approach for treating T cell-mediated experimental inflammatory disease, i.e., Th17-mediated colitis. Collectively, this study is likely to pave the way for the development of new, highly selective therapeutic strategies to treat T cell-mediated autoimmunity and inflammation. This project fits seamlessly with the NIAID mission to conduct and support research to study the causes of allergic, immunologic, and infectious diseases, and to develop better means of preventing, diagnosing, and treating these illnesses. Meanwhile, this project also has close relevance to the mission of the NIDDK as it will study the effects of blocking the PKCθ-CD28 interaction on an experimental chronic colitis model.