Autoreactive CD4 T cells in healthy mice

在胸腺中，中枢耐受应该消除大多数未成熟的T细胞， 表达自身反应性致病性抗原受体（αβ TCR）。然而，数量不详的 自身反应性细胞逃避缺失或进入免疫抑制性调节谱系（Tlymphocyte）。 T细胞调节外周耐受性并维持潜在自身反应性T细胞的休眠。 然而，患有失能性T细胞的小鼠和人类迅速发展多器官自身免疫并死亡。 年轻，表现出几乎所有CD4+克隆的多克隆活化。因此，我们假设， 包埋在外周库中的自身反应性克隆的数目可以高得多（即， 超过所有CD4+细胞的三分之一）。具体目标1、 我们将研究胸腺内不同自身肽的表达是如何支持或阻止免疫应答的。 自身反应性T细胞逃避中枢耐受。这种方法将记录潜在的 自身反应性CD4+克隆通常作为静止细胞侵入B6小鼠的淋巴器官。 接下来，我们将测试这些细胞对一组已知的天然存在的自身肽的体外反应 通过小鼠抗体分子，以确定这些克隆是由普遍存在的还是特异性的 自身抗原在特定目标2中，我们将研究为什么表达单一自身抗原的小鼠 在全身有主要的自身免疫表现，在特定器官有检查作用 非经典的CD4+ T细胞在该模型中的自身免疫性。在目标3中，我们将使用一种新的单细胞 来自10X Genomics的RNA seq系统，用于在单个CD4+细胞中检查其转录组 和天然αβ TCR，以鉴定潜在自身反应性细胞中TCR4靶向的基因， 它们处于休眠状态，防止自身免疫。总的来说，这个应用程序将重新访问相对于 各种耐受机制在维持自我平衡中的重要性， 抗原，并可以揭示新的机制，如何控制TCRs自身反应性。

In the thymus, central tolerance should eliminate the majority of immature T cells that express autoreactive, pathogenic antigen receptors (αβTCRs). However, an unknown number of autoreactive cells escape deletion or commit to immunosuppressive, regulatory linage (Tregs). Tregs control peripheral tolerance and sustain dormancy of potentially autoreactive T cells. However, mice and humans with disabled Tregs rapidly develop multiorgan autoimmunity and die young, manifesting polyclonal activation of almost all CD4+ clones. Thus, we hypothesized that the number of autoreactive clones embedded in the peripheral repertoire can be much higher (i.e. over one-third of all CD4+ cells) as compared to what is currently anticipated. In Specific Aim 1, we will examine how the intrathymic expression of different self-peptides supports or prevents an escape of autoreactive T cells from central tolerance. This approach will document that potentially self-reactive CD4+ clones commonly trespass to lymphoid organs of B6 mice as quiescent cells. Next, we will test these cells ex vivo responses to a known set of self-peptides naturally presented by mouse Ab molecules to determine if these clones are triggered by ubiquitous or specific autoantigens. In Specific Aim 2, we will investigate why mice expressing single autoantigen across the body have main autoimmunity manifestation in specific organs and examine the role of non-classical CD4+ T cells in autoimmunity in this model. In Aim 3 we will use a new single-cell RNA seq system from 10X Genomics, to examine in individual CD4+ cells their transcriptomes and native αβTCRs to identify genes targeted by Tregs in potentially autoreactive cells to keep them dormant and prevent autoimmunity. Overall, this application will revisit the relative importance of various mechanisms of tolerance in the maintenance of homeostasis to self- antigens and can reveal new mechanisms of how Tregs control self-reactivity.