G-CSF-treated donor CD4+ T cells attenuate acute GVHD through a reduction in Th17 cell differentiation

Abstract

The immunoregulatory effects of granulocyte colony-stimulating factor (G-CSF) on allogeneic peripheral blood cell transplantation (PBCT) have been demonstrated to reduce acute graft-versus-host disease (GVHD). However, the underlying mechanism is still not clear. In this study, we focused on the direct effects of G-CSF on donor CD4+ T cell responses after transplantation. We observed that lethally irradiated B6D2F1 recipient mice that are transplanted with CD4+ T cells from G-CSF-treated B6 donors showed mild attenuations in severity and mortality compared with recipients transplanted with PBS-treated CD4+ T cells. Notably, skin GVHD was significantly reduced, but no such reduction was observed in other organs. Although there was no difference with respect to alloreactive expansion or Foxp3+ Treg induction, the use of G-CSF-treated CD4+ T cells significantly reduced the numbers of IL-17-producing and RORγt-expressing cells in the secondary lymphoid organs of allogeneic recipients after transplantation compared with the use of the control cells. Finally, we found that the suppressor of cytokine signaling-3 (SOCS3) expression in G-CSF-treated donor CD4+ T cells was much higher than that in control CD4+ T cells. Our results demonstrate that the inhibition of Th17 cell differentiation by SOCS3 induction is associated with the immunoregulatory role of G-CSF in CD4+ T cell-mediated acute GVHD.