Mechanisms of T cell inhibitory pathways

描述（由申请人提供）：本次K08奖的主要目标是研究B7:CD28共刺激分子家族中调节T细胞激活和耐受性的新的T细胞抑制途径。该PI将在哈佛医学院接受T细胞共刺激领域专家阿琳·夏普博士的指导。我们发现T细胞上的程序性死亡-1配体1 （PD-L1）可以与B7-1相互作用，并且这种相互作用可以抑制T细胞的反应。我们将验证T细胞上的PD-L1在控制T细胞活化、效应反应和自身免疫中起重要作用的假设。我们有许多独特的工具，包括基因缺陷小鼠和PD-L1抗体，使我们能够解剖PD-L1信号传导到T细胞的分子机制，并研究其在控制体内反应中的作用。我们的具体目标是：1。建立PD-L1对小鼠和人T细胞抑制作用的机制。在这个目标中，我们将测试PD-L1对T细胞是否通过1)修改TCR信号通路和/或2)利用信号伙伴或第二链来发挥抑制作用。我们还将测试PD-L1在人类T细胞上的连接是否具有抑制性。这些子目标将深入了解T细胞上的PD-L1抑制反应的机制，以及PD-L1对人类T细胞的治疗性操作的潜力。2. 确定PD-L1在免疫突触（IS）上对T细胞及其伙伴的作用。T细胞通过与IS部位的apc接触而被激活和调节。apc上的B7-1可以与T细胞上的CD28、CTLA-4或PD-L1相互作用，这就提出了一个问题：PD-L1如何与CD28和CTLA-4竞争B7-1相互作用？我们将重点关注T细胞上的PD-L1如何在早期突触（微簇）和晚期突触（T细胞- dc突触）中与CD28竞争结合B7-1。这些研究将补充Aim 1中的研究，以探索PD-L1对T细胞可能发挥其抑制作用的另一种途径。3. 描述PD-L1对T细胞的体内作用：激活和自身免疫。我将研究PD-L1在CD4和CD8 T细胞激活和效应反应中的体内作用。本研究旨在通过糖尿病自身免疫模型，验证PD-L1通路在体内自身免疫反应过程中可能控制自身反应性T细胞的假设。在这个提案中，我计划在T细胞生物学领域获得新的技能，包括显微镜和自身免疫的体内研究。我的长期目标是结合我在基础科学和临床医学方面的背景，成为一名学术医师科学家和独立研究者，研究抑制性T细胞途径在调节自身免疫和传染病时的基本作用。

DESCRIPTION (provided by applicant): The main goal of this K08 Award is to study a new T cell inhibitory pathway in the B7:CD28 family of costimulatory molecules that regulates T cell activation and tolerance. The PI will be mentored at Harvard Medical School by Dr. Arlene Sharpe, an expert in the area of T cell costimulation. We have found that Programmed Death-1 Ligand 1 (PD-L1) on T cells can interact with B7-1, and that this interaction can inhibit T cell responses. We will test the hypothesis that PD-L1 on T cells plays an important role in controlling T cell activation, effector responses, and autoimmunity. We have a number of unique tools, including gene-deficient mice and PD-L1 antibodies that enable us to dissect the molecular mechanisms of PD-L1 signaling on T cells and investigate its roles in controlling in vivo responses. Our specific aims are: 1. Establish the mechanisms by which PD-L1 on T cells exerts inhibitory effects in mice and humans. In this Aim, we will test whether PD-L1 on T cells exerts an inhibitory effect by 1) modifying TCR signaling pathways, and/or by 2) utilizing a signaling partner or second chain to enact inhibitory effects. We will also test if ligation of PD-L1 on human T cells is inhibitory. These subaims will provide insight into the mechanisms by which PD-L1 on T cells inhibits responses and the potential for therapeutic manipulation of PD-L1 on human T cells. 2. Determine the roles of PD-L1 on T cells and its partners at the immunological synapse (IS). T cells are activated and regulated by contact with APCs at the IS. B7-1 on APCs can interact with CD28, CTLA-4, or PD-L1 on the T cell, raising the question: how does PD-L1 compete with CD28 and CTLA-4 for B7-1 interactions? We will focus on how PD-L1 on T cells competes with CD28 for binding to B7-1 in the early synapse (microclusters) and the late synapse (T cell-DC synapse). These studies will complement those in Aim 1 to investigate another means by which PD-L1 on T cells may exert its inhibitory effects. 3. Characterize in vivo effects of PD-L1 on T cells: activation and autoimmunity. I will examine the in vivo role of PD-L1 on CD4 and CD8 T cells during activation and effector responses. This aim will test the hypothesis that the PD-L1 pathway may control self-reactive T cells during autoimmune responses in vivo, using an autoimmune model of diabetes. In this proposal, I plan to acquire new skills in areas of T cell biology, including microscopy and in vivo studies of autoimmunity. My long-term goal is to combine my background in basic science and clinical medicine to be an academic physician-scientist and independent investigator, examining the fundamental roles of inhibitory T cell pathways as they regulate autoimmunity and infectious diseases. RELEVANCE: Blockade of PD-L1 has become an important therapeutic target. These studies will provide insights into new mechanisms to control T cell responses in microbial immunity, tumor immunity, and autoimmunity, and will provide fundamental insights into mechanisms of inhibition of T cells.