6A). To determine whether TREG cells are able to directly inhibit γδ T-cell responses in vivo independently of CD4+ TEFF cells, we first adoptively transferred CD4+CD25+ TREG cells alone in TCR-β−/− recipient mice, and assessed γδ T-cell responses. Administration of TREG cells significantly

reduced the accumulation of γδ T cells in both mesLN and LP of recipient mice (Fig. 6B). Moreover, 14 days post TREG-cell transfer, recipient mice showed a significant decrease in the proportion of resident IFN-γ- and IL-17-producing γδ T cells compared with control non-reconstituted mice (Fig. 6C and D). Furthermore, we also adoptively transferred RAG2−/− recipient mice with γδ T cells in the presence or absence of TREG cells. Our results show that although the expansion of donor γδ T cells was unchanged by TREG cell co-administration (Fig. 6E), the secretion of IFN-γ and IL-17 AZD0530 by γδ T cells was significantly inhibited (Fig. 6F and G). We observed a two- and four-fold decrease Protein Tyrosine Kinase inhibitor in the frequency of IFN-γ- and IL-17-secreting γδ T cells in the presence of TREG cells (Fig. 6G). Overall, we show that TREG cells, in addition to controlling donor CD4+ TEFF cell functions, are also

able to directly suppress γδ T cells in vitro as well as significantly dampen the inflammatory response of resident γδ T cells in our in vivo model of T-cell-induced colitis. While TREG cells readily suppressed CD4+ TEFF cells, we make the novel observation that TREG cells are particularly capable of restraining the expansion and effector differentiation of resident pro-inflammatory selleck chemical γδ T cells in the mesLN and intestinal tissue. In our study, we investigated the dynamics of TREG and pathogenic T-cell responses in a T-cell-adoptive transfer model of intestinal inflammation in an attempt

to gain insights into the mechanisms and cellular targets of TREG cell-mediated suppression in vivo. We show that CD4+CD25+Foxp3+ TREG cells suppress the mucosal inflammation induced by colitogenic CD4+CD25−Foxp3− TEFF cells and reduce the pathogenic potential of donor αβ and resident γδ TEFF cells in the intestinal microenvironment of αβ T-cell-deficient TCR-β−/− mice. We show that γδ T cells are active contributors to the global inflammatory environment in T-cell-induced colitis. Resident γδ T cells actively proliferate, differentiate into Th1- or Th17-like cells and migrate to the mucosal tissue, where they continue to expand and secrete IFN-γ and IL-17. Previous reports have shown that γδ T cells, among other mucosa-residing innate and memory cells, produce a basal level of IL-17 and IL-22, which play an important role in maintenance of a constitutive level of antimicrobial proteins implicated in mucosa surveillance 52, 53 as well as the tonus of endothelial junctions 54. Our results demonstrate that within the first days post CD4+ TEFF cell transfer, γδ T cells produce the majority of IL-17 and IFN-γ.