Project description:Using Foxp3.RFP Rag.GFP reporter mice, mature Tregs in the thymus were characterized by performing RNA sequencing on Rag.GFP– and Rag.GFP+ Tregs that were isolated from the thymus and Tregs isolated from the spleen
Project description:Using Foxp3.RFP Rag.GFP reporter mice, we characterized differences between the IL18R- and the IL18R+ mature Treg populations in the thymus
Project description:The mechanism of egress of mature regulatory T cells (Tregs) from the thymus to the periphery remains enigmatic, as does the nature of those factors expressed in the thymic environment. Here, we examined the fate of thymic Tregs in TNFα/RelA double-knockout (TA-KO) mice, because TA-KO mice retain a Treg population in the thymus but have only a small Treg population at the periphery. Transplantation of whole TA-KO thymus to under the kidney capsule of Rag1 null mice failed to induce the production of donor-derived splenic Tregs expressing neuropilin-1 (Nrp1), which was reported to be a marker of naturally occurring Tregs, indicating that TA-KO thymic Tregs either do not leave the thymus or are lost at the periphery. We next transplanted enriched TA-KO thymic Tregs to the peripheries of TA-KO mice and traced mouse survival. Transplantation of TA-KO thymic Tregs rescued the lethality in TA-KO mice, demonstrating that TA-KO thymic Tregs remain functional at the periphery. The TA-KO thymic Treg population had highly demethylated CpG motifs in the foxp3 locus, indicating that the cells were arrested at a late-mature stage. Also, the population included a large subpopulation of Tregs expressing IL-7Rα, which is a possible marker of late-mature Tregs. Finally, TA-KO fetal liver chimeric mice developed an Nrp1+ splenic Treg population from TA-KO cells, suggesting that Treg arrest is caused by a lack of RelA in the thymic environment. Together, these results suggest that egress of mature Tregs from the thymus depends on RelA in the thymic environment. For the isolation of thymic Tregs, CD4+CD8α-CD25hi thymocytes were isolated from five 1.5- to 2-week-old TNFα-KO or TA-KO mice by using a FACSAria cell sorter. For the isolation of thymic stromal cells, 10 thymi from 1.5- to 2-week-old TNFα-KO or TA-KO mice were minced with scissors and treated with RPMI 1640 supplemented with 2% FCS, 0.2 mg/ml collagenase (Roche, Basel, Switzerland), 0.2 mg/ml dispase I (Roche), and 100 U/ml DNase I (Life Technologies) for 30 min with stirring. Digested thymi were centrifuged in a Percoll (GE Healthcare Bio-Sciences, Piscataway, NJ, USA) gradient (density, 1.115, 1.065, and PBS) at 1400g for 30 min. Cells in the upper layer were collected, and the CD45-EpCAM+ (thymic epithelial cells) and CD45+EpCAM- populations (enriched thymic stromal cells containing macrophages or dendritic cells) were sorted.
Project description:The mechanism of egress of mature regulatory T cells (Tregs) from the thymus to the periphery remains enigmatic, as does the nature of those factors expressed in the thymic environment. Here, we examined the fate of thymic Tregs in TNFα/RelA double-knockout (TA-KO) mice, because TA-KO mice retain a Treg population in the thymus but have only a small Treg population at the periphery. Transplantation of whole TA-KO thymus to under the kidney capsule of Rag1 null mice failed to induce the production of donor-derived splenic Tregs expressing neuropilin-1 (Nrp1), which was reported to be a marker of naturally occurring Tregs, indicating that TA-KO thymic Tregs either do not leave the thymus or are lost at the periphery. We next transplanted enriched TA-KO thymic Tregs to the peripheries of TA-KO mice and traced mouse survival. Transplantation of TA-KO thymic Tregs rescued the lethality in TA-KO mice, demonstrating that TA-KO thymic Tregs remain functional at the periphery. The TA-KO thymic Treg population had highly demethylated CpG motifs in the foxp3 locus, indicating that the cells were arrested at a late-mature stage. Also, the population included a large subpopulation of Tregs expressing IL-7Rα, which is a possible marker of late-mature Tregs. Finally, TA-KO fetal liver chimeric mice developed an Nrp1+ splenic Treg population from TA-KO cells, suggesting that Treg arrest is caused by a lack of RelA in the thymic environment. Together, these results suggest that egress of mature Tregs from the thymus depends on RelA in the thymic environment.
Project description:cRel is a transcription factor critical for the development of Tregs in the thymus. We examined the impact the lack of cRel has on Tregs at different stages of ontogeny (thymic pre-Tregs, thymic 'de novo' Tregs and mature spenic Tregs).
Project description:Tregs from spleen and thymus of naive Wild-type mice and mice lacking Dendritic Cells (deltaDC) were analyzed. Thymus derived Tregs of both strains show similar expression patterns, peripheral splenic Tregs from deltaDC mice differ from Tregs of WT mice.
Project description:Recent studies have demonstrated that mature regulatory T cells ( Tregs) develop in the thymus via two pathways involving distinct Treg progenitors (TregP) - CD25+FOXP3- (CD25+ TregP) and CD25-FOXP3lo (FOXP3lo TregP) Treg progenitors. To examine this process in more detail we carried out single-cell RNA-Seq and TCR-Seq on sorted CD4+CD8+ double-positive (DP) thymocytes, CD4+ Ssingle -positive (CD4SP)P thymocytes, CD25+ TregP, FOXP3lo TregP, mature CD25+FOXP3+ Tregs and recirculating/long-term resident Tregs (RT-Tregs). Sorted populations were individually hashtagged and then combined into one scRNA-Seq/TCR-Seq library before sequencing and subsequent analysis. We found that both CD25+ TregP and FOXP3lo TregP arise via an initial agonist activated state that gives rise to a second transitional stage before differentiating into mature Tregs. Using both scRNA-Seq and bulk RNA-Seq on sorted thymocyte subsets we demonstrate that CD25+Foxp3- TregP are significantly enriched for Il2 production, suggesting that they are the major source of IL-2 needed to convert TregP into mature Tregs. Using TCR-Seq we found that several TCRs were clearly biased in favor of the conventional or Treg lineages, but that a large fraction of TCRs were found in both these lineages. Finally, we found that recirculating/resident Tregs in the thymus are not monomorphic, but are composed of multiple distinct subsets and that these RT-Tregs express the most diverse TCR repertoire of all CD4SP thymcocytes. Thus, our studies define multiple stages of Treg differentiation within the thymus, and serve as a resource for future studies on CD4+ thymocyte development and Treg differentiation.