TCR signaling control of thymic Treg selection and immune homeostasis

摘要 新生儿胸腺来源的Foxp 3 + T调节细胞（tTcells）是免疫系统发育所必需的。 体内平衡和限制性器官特异性自身免疫性疾病。TCR-pMHC的分子细节 相互作用和特定的下游信号通路，使新生儿tTHBE的发展，种子 外周组织和调节急性炎症的机制尚不清楚。我们假设， 新生儿tTcR通过表达对自身配体具有特异性的TCR来区分健康与疾病， 在炎性条件下被上调。这种tTreg TCR识别特性表现为分级 免疫抑制水平基于炎症环境的背景和程度。初步 数据进一步表明，这些tTreg克隆在新生儿选择窗口内的发育是 在时间上受阴性选择的限制，并基于动力学校正，使用TCR-自身-pMHC 常规结合模式内的停留时间作为指定tTreg发育的关键。来测试我们 假设，我们将首先鉴定由Foxp 3 + CD 4 tTreg细胞亚群识别的内源性自身配体。我们 这种方法是基于我们已经证明的识别T细胞识别的自身配体的能力， 从不同解剖位置分离的APC上呈递的MHC-II结合的自身肽的光谱分析， 以及用于确定单个T细胞克隆型的识别特性的高通量管道。使用 我们的第二个目标是直接检查新生儿tTreg是否 选择是基于相互作用的停留时间，并评估“非常规”TCR/自身免疫的影响。 选择新生儿tTreg库中的pMHC结合模式。目标3将确定自我- 胸腺APCs的pMHC呈递和胸腺细胞产生的TCR信号的质量， 新生儿tTreg选择窗口。建议Tec家族激酶Itk的信号传导调节信号传导。 通过扩增促存活TCR信号将Foxp 3 Treg选择与晚期缺失分开的阈值 通过NFAT和NF-κB信号通路从中等停留时间配体衍生。最后，在成熟期， 我们认为Itk的功能是放大弱TCR应答，从而使成熟的TCR能够识别 显示自身抗原的梯度。这些研究将为T细胞的微调提供重要的见解。 反应和区分效应细胞和调节细胞的信号通路，导致合理的 在设计治疗剂以操纵用于治疗癌症的免疫应答方面的方法， 自身免疫性疾病

Abstract    Neonatal thymic-derived Foxp3+ T regulatory cells (tTregs) are required for the development of immune homeostasis and limiting organ specific autoimmune disease. The molecular details of TCR-pMHC interactions, and the specific downstream signaling pathways that allow neonatal tTregs to develop, seed peripheral tissues and regulate acute inflammation are not well understood. We hypothesize that a subset of neonatal tTregs distinguishes health from disease via the expression of TCR with specificity for self-ligands that are upregulated during inflammatory conditions. This tTreg TCR recognition property manifests as graded levels of immune suppression based on the context and magnitude of the inflammatory setting. Preliminary data further suggest that the development of these tTreg clones within the neonatal selection window is temporally constrained by negative selection, and is predicated on kinetic proofreading, with TCR-self-pMHC dwell times within a conventional binding mode as a key to specifying tTreg development. To test our hypothesis, we will first identify endogenous self-ligands recognized by Foxp3+ CD4 tTreg cell subsets. Our approach is based on our proven ability to identify self-ligands recognized by T cells, paired with mass spectrometry of MHC-II bound self-peptides presented on APC isolated from different anatomical locations, as well as high-throughput pipelines for determining recognition properties of individual T cell clonotypes. Using paired sets of TCR-self-pMHC combinations our second aim will directly examine whether neonatal tTreg selection is based the dwell time of the interaction, and assess the influence of “unconventional” TCR/self- pMHC binding modes in selecting the neonatal tTreg repertoire. Aim 3 will identify synergies between self- pMHC presentation by thymic APCs and the quality of TCR signals generated by thymocytes that define the neonatal tTreg selection window. Signaling by the Tec family kinase, Itk, is proposed to regulate a signaling threshold that separates Foxp3 Treg selection from late stage deletion by amplifying pro-survival TCR signals derived from moderate dwell-time ligands via NFAT and NF-κB signaling pathways. Finally, in mature tTregs, we propose that Itk functions to amplify weak TCR responses, thereby allowing mature Tregs to recognize gradients in self-antigen displayed. These studies will provide important insights into the fine-tuning of T cell responses and the signaling pathways that discriminate effector cells from regulatory cells, leading to rational approaches in the design of therapeutics to manipulate immune responses for treatments of cancer and autoimmune diseases.