Soluble stimulation–2 (ST2) is increased during graft-versus-host disease (GVHD), while Tregs that express ST2 prevent GVHD through unknown mechanisms. Transplantation of Foxp3– T cells and Tregs that were collected and sorted from different Foxp3 reporter mice indicated that in mice that developed GVHD, ST2+ Tregs were thymus derived and predominantly localized to the intestine. ST2–/– Treg transplantation was associated with reduced total intestinal Treg frequency and activation. ST2–/– versus WT intestinal Treg transcriptomes showed decreased Treg functional markers and, reciprocally, increased Rorc expression. Rorc–/– T cells transplantation enhanced the frequency and function of intestinal ST2+ Tregs and reduced GVHD through decreased gut-infiltrating soluble ST2–producing type 1 and increased IL-4/IL-10–producing type 2 T cells. Cotransfer of ST2+ Tregs sorted from Rorc–/– mice with WT CD25-depleted T cells decreased GVHD severity and mortality, increased intestinal ST2+KLRG1+ Tregs, and decreased type 1 T cells after transplantation, indicating an intrinsic mechanism. Ex vivo IL-33–stimulated Tregs (TregIL-33) expressed higher amphiregulin and displayed better immunosuppression, and adoptive transfer prevented GVHD better than control Tregs or TregIL-33 cultured with IL-23/IL-17. Amphiregulin blockade by neutralizing antibody in vivo abolished the protective effect of TregIL-33. Our data show that inverse expression of ST2 and RORγt in intestinal Tregs determines GVHD and that TregIL-33 has potential as a cellular therapy avenue for preventing GVHD.
Jinfeng Yang, Abdulraouf Ramadan, Dawn K. Reichenbach, Michael Loschi, Jilu Zhang, Brad Griesenauer, Hong Liu, Keli L. Hippen, Bruce R Blazar, Sophie Paczesny