Interleukin-2 receptor signaling acts as a checkpoint that shapes the distribution of regulatory T cell subsets (scRNA-Seq)

Regulatory T cells (Tregs) require IL-2 for survival in the periphery, yet how IL-2 shapes Treg heterogeneity remains poorly defined. Here we found that inhibition of IL-2R signaling in post-thymic Tregs leads to a preferential early loss of central Tregs (cTregs). Gene expression of cTregs was more dependent on IL-2R signaling than effector Tregs (eTregs). Unexpectedly, ablation of IL-2R signaling in cTregs resulted in increased proliferation, expression of eTreg genes, and enhanced capacity to develop into eTregs. These findings indicate that physiological amounts of IL-2 act as a checkpoint to maintain cTreg homeostasis and tolerance while restraining their development into eTregs. Nevertheless, direct evaluation of eTregs revealed that loss of IL-2R signaling alters the distribution of eTreg subsets, with increased IFNgR1+ eTregs and CXCR5+ PD-1+ T follicular regulatory (TFR) cells but decreased intestinal RORgt+ TR17 cells. Thus, IL-2R signaling also shapes the development of specialized eTregs subsets. Treg-specific CD25 knockout was induced with tamoxifen and splenocytes were harvested 10 days later. Tregs were FACS purified from the spleen using viability, CD4, GFP and tdTtomato reporters. CD25iKO Tregs were gated on CD25lo cells. Purified cells were submittied for scRNAseq. Two pooled spleens were used for each sample.