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抗原受体(αβTCR)。然而，数量不详的 自身反应细胞逃脱缺失或致力于免疫抑制，调节性连接(Tregs)。 Treg控制外周耐受，维持潜在自身反应性T细胞的休眠。 然而，患有残废Tregs的小鼠和人类迅速发展为多器官自身免疫并死亡。 年轻，表现出几乎所有CD4+克隆的多克隆激活。因此，我们假设 嵌入在外围曲目中的自动反应克隆的数量可能要高得多(即 所有CD4+细胞的三分之一以上)，而不是目前预期的水平。在具体目标1中， 我们将研究不同自体肽在胸腺内的表达是如何支持或阻止 自身反应性T细胞逃避中枢耐受。此方法将潜在地记录 自身反应性的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自然呈现的自体多肽的体外反应。 通过小鼠抗体分子来确定这些克隆是由无处不在的还是特定的 自身抗原。在特定目标2中，我们将调查为什么表达单一自身抗原的小鼠 全身自体免疫的主要表现在特定的器官和检查作用 在这个模型中非经典的CD4+T细胞在自身免疫中的作用。在目标3中，我们将使用一个新的单细胞 来自10X基因组公司的RNA序列系统，用于检测单个CD4+细胞的转录 和本地αβTCR以识别潜在自身反应细胞中Treg靶向的基因以保持 它们处于休眠状态，并阻止自身免疫。总的来说，此应用程序将重新访问相对的 多种耐受机制在维持自我稳态中的重要性 并可以揭示Treg如何控制自身反应性的新机制。

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.