Control of Regulatory T Cell Function by Toll-Like Receptor 7

摘要 调节性T细胞（Tcells）对于维持免疫耐受性至关重要，但最近它们的免疫耐受性降低。 在调节组织稳态的其它方面中的重要性已经成为人们强烈关注的领域。最 与该应用相关的是在损伤时积累的组织驻留TdR群体， 组织修复通过产生因子，如EGF家族成员双调蛋白（Areg）。这些修复功能 与传统上归因于TdR的抑制功能不同，但是指示TdR 采用这些不同的职能模式尚未得到很好的界定。IL-1家族细胞因子IL-18和IL-33 至少在某些组织中，这些细胞因子在某种程度上参与其中，但目前尚不清楚这些细胞因子是否作为 Treg功能的关键初始决定因素。 这项提议将检验Toll样受体7（TLR 7）信号转导是Toll样受体表达的关键决定因素这一假设。 Treg组织修复功能。我们提出TLR 7使TcR能够感测病原体衍生的核酸， 以及从受损的宿主组织中释放的自身RNA。我们的假设是基于我们对一组 TLR报告小鼠，其揭示了只有TLR 7在TcB上表达，以及强有力的初步数据 这表明TLR 7可以在小鼠和小鼠中诱导标志性组织修复基因Areg的表达， 人的舌头。使用新产生的Treg特异性TLR 7缺失的小鼠，我们将检查 TLR 7信号传导在肺损伤过程中的重要性（目的1）。单细胞RNA测序将确定 肺TCLs的哪些亚群受TLR 7控制并将定义TCLs中的TLR 7依赖性基因。我们将 我还使用Treg特异性缺失的小鼠研究了IL 18 R和IL 33 R信号在Treg中的重要性 这些受体，并将确定TLR 7，IL 18 R和IL 33 R调节这些受体的不同方面的程度。 响应于不同肺损伤剂的Treg扩增和/或分化（目的2）。最后我们将 基于我们最近的工作，确定了TLR伴侣蛋白Unc 93 b1特异性地 抑制TLR 7信号传导。使用来自具有增强的TLR 7信号传导的突变体Unc 93 b1的小鼠的Tclase， 我们将测试对病毒和自身RNA具有增强的TLR 7应答的TcR的过继治疗是否可以 介导更有效的肺损伤修复（目的3）。 总之，这些研究将定义控制Treg组织修复功能的信号，并测试治疗性免疫缺陷的方法。 在肺损伤的背景下放大这些信号的潜力，这是治疗的关键第一步。 操纵Treg功能以获得临床益处。

ABSTRACT Regulatory T cells (Tregs) are critical for the maintenance of immunological tolerance but more recently their importance in regulating other aspects of tissue homeostasis has been an area of intense interest. Most relevant to this application are populations of tissue-resident Tregs that accumulate upon injury and facilitate tissue repair by producing factors such as the EGF family member amphiregulin (Areg). These repair functions are distinct from the suppressive function classically attributed to Tregs, but the signals that instruct Tregs to adopt these distinct functional modalities have not been well defined. The IL-1 family cytokines IL-18 and IL-33 are involved at some level, at least in certain tissues, but it remains unclear whether these cytokines act as the key initial determinants of Treg function. This proposal will test the hypothesis that Toll-like receptor 7 (TLR7) signaling in Tregs is a key determinant of Treg tissue repair function. We propose that TLR7 enables Tregs to sense pathogen-derived nucleic acids as well as self RNA released from damaged host tissues. Our hypothesis is based on our analysis of a panel of TLR reporter mice, which revealed that only TLR7 is expressed on Tregs, as well as strong preliminary data demonstrating that TLR7 can induce expression of the signature tissue repair gene, Areg, in both murine and human Tregs. Using newly generated mice with Treg-specific deletion of TLR7, we will examine the importance of TLR7 signaling in Tregs during lung damage (Aim 1). Single-cell RNA sequencing will identify which subsets of lung Tregs are controlled by TLR7 and will define TLR7-dependent genes in Tregs. We will also investigate the importance of IL18R and IL33R signaling in Tregs, using mice with Treg-specific deletion of these receptors, and will determine the extent to which TLR7, IL18R, and IL33R regulate distinct aspects of Treg expansion and/or differentiation in response to diverse lung damaging agents (Aim 2). Finally, we will build on our recent work that identified a mechanism by which the TLR chaperone Unc93b1 specifically dampens TLR7 signaling. Using Tregs from mice with mutant Unc93b1 that have enhanced TLR7 signaling, we will test whether adoptive therapy of Tregs with enhanced TLR7 responses to viral and self RNA can mediate more effective repair of lung damage (Aim 3). Altogether, these studies will define the signals that control Treg tissue repair functions and test the therapeutic potential of amplifying these signals in the context of lung damage, a key first step toward therapeutic manipulation of Treg function for clinical benefit.