CD40-Induced TCR Revision: A Mechanism for Autoimmunity

描述（由申请人提供）：本申请的目标是研究CD40+ T细胞的发育，CD40在T细胞受体（TCR）修订中的作用以及诱导的TCR修订如何影响自身免疫。CD40在包括1型糖尿病（T1D）在内的自身免疫性疾病中具有直接作用。我们发现一种独特的效应T细胞亚群CD4loCD40+在T1 d中具有高致病性，CD40存在于糖尿病性T细胞克隆中，并且原发性CD4loCD40+ T细胞在NOD小鼠中与胰岛素同时扩增。重要的是，CD4loCD40+ T细胞很容易将T1D转移到NOD。scid接受者。在机制上，CD40诱导T细胞中的RAG1/RAG2重组机制。在这种诱导之后，发生TCR修正，即诱导TCR表达的改变。一些修饰的原代T细胞被发现具有高致病性。然而，CD40诱导的TCR修正可以作为已建立的糖尿病性T细胞克隆的功能耐受机制。具体来说，CD40参与致糖尿病性T细胞克隆BDC2.5严重削弱了克隆的疾病转移能力。我们发现，在3周龄的NOD小鼠中阻断CD40 - CD154 （CD40的配体）相互作用不仅可以防止T1D的发生，还可以阻止CD4loCD40+自身侵袭性细胞的扩张。在这个应用中，我们将探讨CD40如何影响独特的T细胞群。我们的假设是TCR修正直接影响T细胞耐受性。特异性目标#1:CD4loCD40+ T细胞是一个独特的T细胞亚群还是代表T细胞内的一种瞬时激活状态？如果CD40在T细胞上被诱导，这些T细胞与固有的CD40 T细胞亚群相比是否存在差异？我们计划通过实验来解决这个中心问题。特异性目标#2:CD40接合如何影响CD4loCD40+ T细胞的TCR修正？自身免疫性和非自身免疫性疾病对CD40参与的反应是否存在差异？我们将探讨RAG1和RAG2的诱导、TCR修正的动力学以及自身免疫和非自身免疫小鼠中不同来源的CD154如何影响这一过程。特异性目标#3:CD40接合如何影响T细胞抗原特异性？我们将在体外和体内模型中探讨诱导TCR修正如何影响T细胞抗原特异性。这些拟议的研究不仅涉及潜在的自身侵袭性T细胞的发展，而且将提供关于诱导TCR修正是致病性还是耐受性的重要信息。

DESCRIPTION (provided by applicant): The goals of this application are to address the development of CD40+ T cells, the role that CD40 plays in T cell receptor (TCR) revision and how induced TCR revision impacts autoimmunity. CD40 has a direct role in autoimmune diseases including type 1 diabetes (T1D). We discovered that a unique subset of effector T cells, described as CD4loCD40+, are highly pathogenic in T1 D. CD40 is present on diabetogenic T cell clones and primary CD4loCD40+ T cells expand concurrently with insulitis in NOD mice. Importantly, CD4loCD40+ T cells readily transfer T1D to NOD.scid recipients. Mechanistically, CD40 induces the RAG1/RAG2 recombination machinery in T cells. Following that induction, TCR revision, induced alteration of TCR expression, occurs. Some revised primary T cells were found to be highly pathogenic. However, CD40 induced TCR revision could serve as a functional tolerance mechanism of established diabetogenic T cell clones. Specifically, CD40 engaging the diabetogenic T cell clone BDC2.5 severely ablated disease transfer ability of the clone. We showed that blocking CD40 - CD154 (the ligand for CD40) interaction in NOD mice at 3-weeks of age prevents not only T1D onset, but prevents expansion of CD4loCD40+, autoaggressive cells. In this application we will explore how CD40 affects the unique T cell population. Our hypothesis is that TCR revision directly impacts T cell tolerance. Specific Aim #1: Do CD4loCD40+ T cells comprise a unique T cell subset or represent a transient activation state within T cells? If CD40 is induced on T cells are there differences in those T cells compared to the intrinsic CD40 T cell subset? We plan experiments to address this central concern. Specific Aim #2: How does CD40 engagement affect TCR revision in CD4loCD40+ T cells? Are there differences in response to CD40 engagement between autoimmune and non-autoimmune conditions? We will explore RAG1 and RAG2 induction, kinetics of TCR revision and how different sources of CD154 in autoimmune versus non-autoimmune mice affect this process. Specific Aim #3: How does CD40 engagement affect T cell antigen specificity? We will explore how induced TCR revision affects T cell antigen specificity using in vitro and in vivo models. These proposed studies address not only the development of potential autoaggressive T cells but will provide important information as to whether induced TCR revision is pathogenic or tolerogenic.