Tuftsin prevents the negative immunoregulation of neuropilin-1highCD4+CD25+Regulatory T cells and improves survival rate in septic mice

Our previous research showed that neuropilin (Nrp) -1(high)CD4(+)CD25(+)Regulatory T cells (Tregs) exhibited primary negative immunoregulation in sepsis induced immune dysfunction. Tuftsin is the typical ligand of Nrp-1. Herein, we investigated the potential therapeutic value and mechanisms of tuftsin in sepsis. Sepsis per se markedly decreased the serum concentration of tuftsin, administration of tuftsin improved the survival rate of septic mice with cecal ligation and puncture (CLP). In vitro study, tuftsin prevented the negative immunoregulation of Nrp-1(high)CD4(+)CD25(+)Tregs, including weakening the expression of forkhead/winged helix transcription factor (Foxp)-3/cytotoxic T lymphocyte associated antigen (CTLA)-4, inhibiting the secretion of transforming growth factor (TGF)-beta, and weakening the immunosuppressive function of Nrp-1(high)CD4(+)CD25(+)Tregs to conventional CD4(+)CD25(-)T cells. Tuftsin markedly inhibited the demethylation of Foxp3-Tregs specific demethylated region (TSDR) of Nrp-1(high)CD4(+)CD25(+)Tregs. Tuftsin could represent a new potential therapeutic agentia to improve the outcome of septic mice, and associate with preventing the negative immunoregulation of Tregs via Nrp-1.