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仔细的 在屏障耐受性、屏障功能维持和避免损伤之间取得平衡 炎症FoxP 3 + T调节（Treg）细胞发挥着关键作用，有助于维持免疫系统。 耐受性和控制炎症。我们最近描述了感应， 来自人类肠道的FoxP 3 + Treg细胞的独特群体的几种共生体也表达， 在功能上需要转录因子RORg。这是自相矛盾的，因为RORg是前- 炎症性Th 17细胞Rorg+ Treg细胞响应肠道共生体而扩增，可能通过局部 分化，并在功能上参与肠道炎症的控制。它们在结肠中共存 与更典型的太阳神+Gata 3 hi Tibet，可能是胸腺起源。我们建议解决几个重要问题， 这些观察结果所提出的问题，探索Rorg+ TdR的控制，起源和功能。 1. FoxP 3和RORg如何在分子水平上协同作用，以及RORg如何发挥作用， 不同的Th 17细胞与Rorg+ T细胞？这将通过分析转录和染色质 由仔细控制CD 4 + T细胞中FoxP 3和RORg的表达引起的变化， 在Th 17和Tcl 3中差异表达的其他转录因子，或与 RORg.这些推论将在条件性基因敲除小鼠体内进行验证， 将通过平行转导人CD 4 + T细胞和通过低输入RNAseq分析来评估生理学 我们在人类结肠中发现的Rorg+ T细胞。 2. Rorg+ Tcb的细胞起源和分化途径是什么？起源和内部- 结肠中结肠Treg亚群之间的关系将通过转移实验、谱系分析和免疫调节来分析。 在Treg特异性标记后进行追踪，并通过使用TCR序列作为条形码来评估Treg特异性标记与TCR序列之间的关系。 由单一微生物定殖的小鼠中的Treg和Tconv群体 3.通过诱导Treg特异性基因敲除评估RORg+和Helios+结肠TlR的相对作用 在调控结肠Treg群体的关键转录中（Rorc、Gata 3、Ikzf 2）。的影响 这些扰动将根据基线时的结肠炎症、化学或细菌- 诱导的炎症、肠屏障完整性、微生物特异性伊加库以及Treg 种群影响微生物门和物种的平衡。 这些连接的探索将提供一个独特的机制和功能的理解，这些 重要的Treg群体，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.