T regulatory cell subsets at the microbial interface: determinism and function

与哺乳动物肠道中的基本微生物和平共处需要谨慎的 在容忍共生关系、维持屏障功能和避免损害之间取得平衡 发炎。FoxP3+T调节(Treg)细胞起着关键作用，它有助于维持免疫力 在许多生物环境中耐受和控制炎症。我们最近描述了通过 人类肠道中的几个共生体也表达和表达FoxP3+Treg细胞 在功能上需要转录因子RORg。这是矛盾的，因为RORG是PRO-2的主要调节者。 炎性Th17细胞。Rorg+Treg细胞对肠道共生菌的响应，可能是通过局部 分化，并在功能上参与控制肠道炎症。它们同时存在于结肠中 更典型的Helios+Gata3hi Tregs，可能来自胸腺。我们建议解决几个重要的问题 通过这些观察打开的问题，探索Rorg+Tregs的控制、起源和功能。 1.FoxP3和RORg在分子水平上是如何协同作用的，RORg又是如何发挥作用的 Th17细胞与Rorg+Tregs的不同？这将通过分析转录和染色质来解决 仔细控制FoxP3和RORg在CD4+T细胞中的表达引起的变化 在Th17和Tregs中有差异表达的其他转录因子，或与 RORG.这些推论将在活体条件基因敲除小鼠身上得到验证，以及它们与人类的相关性 生理学将通过并行转换人类CD4+T细胞和低输入RNAseq分析进行评估 我们在人类结肠中发现的Rorg+Tregs。 2.Rorg+Tregs的细胞起源和分化途径是什么？它的起源和相互关系 结肠Treg亚群之间的关系将通过移植实验和谱系来分析 在Treg特定标记之后进行跟踪，并使用TCR序列作为条形码来评估 单一微生物在小鼠体内的Treg和Tconv种群 3.通过诱导Treg特异性基因敲除来评估RORg+和Helios+结肠Tregs的相对作用 在相互控制结肠Treg群体(RORC、GATA3、Ikzf2)的关键转录中。的影响 这些扰动将在基线时评估结肠炎、化学或细菌控制- 诱导炎症、肠道屏障完整性、微生物特异性IgA谱系以及Treg是否发生变化 种群影响微生物门和物种的平衡。 这些相互关联的探索将提供对这些问题的独特的机械和功能理解 基本的Treg种群，并将对我们理解控制 宿主/共生体界面的炎症。

Peaceful coexistence with the essential microbes that populate the mammalian gut requires a careful balance between tolerance of commensals, maintenance of barrier function, and avoidance of damaging inflammation. A key role is played by FoxP3+ T regulatory (Treg) cells, which help maintain immunologic tolerance and control inflammation in many organismal contexts. We have recently described the induction by several symbionts from the human gut of a unique population of FoxP3+ Treg cells that also express and require functionally the transcription factor RORg. This is paradoxal, as RORg is the master regulator of pro- inflammatory Th17 cells. Rorg+ Treg cells expand in response to gut symbionts, perhaps through local differentiation, and are functionally involved in the control of intestinal inflammation. They co-exist in the colon with more typical Helios+Gata3hi Tregs, likely of thymic origin. We propose to address several important questions opened by these observations, to explore the control, origin and function of Rorg+ Tregs. 1. How do FoxP3 and RORg synergize at the molecular level, and how does RORg function so differently in Th17 cells vs Rorg+ Tregs? This will be addressed by analyzing transcription and chromatin changes resulting from carefully controlled expression of FoxP3 and RORg in CD4+ T cells, modulated with other transcription factors that are differentially represented in Th17 and Tregs, or with oxysterol ligands of RORg. These inferences will be validated in vivo with conditional knockout mice, and their relevance to human physiology will be assessed by transducing human CD4+ T cells in parallel, and by low-input RNAseq analysis of Rorg+ Tregs we found in the human colon. 2. What are the cellular origin and differentiation pathways of Rorg+ Tregs? The origin and inter- relationships between colonic Treg subsets in the colon will be analyzed by transfer experiments, by lineage tracing after Treg-specific tagging, and by using TCR sequences as barcodes to assess relationships between Treg and Tconv populations in mice colonized by a single microbe 3. Relative roles of RORg+ and Helios+ colonic Tregs assessed by inducing Treg-specific knockouts in the key transcription that reciprocally control colonic Treg populations (Rorc, Gata3, Ikzf2). The effects of these perturbations will be assessed on colon inflammation at baseline, the control of chemical or bacterially- induced inflammation, intestinal barrier integrity, microbe-specific IgA repertoire and whether changes in Treg populations influence the balance of microbial phyla and species. These connected explorations will provide a unique mechanistic and functional understanding of these essential Treg populations, and will have profound implications on our understanding of the control of inflammation at the host/symbiont interface.