Dendritic cell-derived IL-27 p28 regulates T cell program in pathogenicity and alleviates acute graft-versus-host disease

Interleukin 27(IL-27),a heterodimeric cytokine composed of Epstein-Barr virus-induced 3 and p28,is a pleiotropic cytokine with both pro-and anti-inflammatory properties.However,the precise role of IL-27 in acute graft-versus-host disease is not yet fully understood.In this study,utilizing mice with IL-27 p28 deficiency in dendritic cells(DCs),we demonstrated that IL-27 p28 deficiency resulted in impaired Treg cell function and enhanced effector T cell responses,corresponding to aggravated aGVHD in mice.In addition,using single-cell RNA sequencing,we found that loss of IL-27 p28 impaired Treg cell generation and promoted IL1R2^(+)TIGIT^(+)pathogenic CD4+T cells in the thymus at a steady state.Mechanistically,IL-27 p28 deficiency promoted STAT1 phosphorylation and Th1 cell responses,leading to the inhibition of Treg cell differentiation and function.Finally,patients with high levels of IL-27 p28 in serum showed a substantially decreased occurrence of grade II-IV aGVHD and more favorable overall survival than those with low levels of IL-27 p28.Thus,our results suggest a protective role of DC-derived IL-27 p28 in the pathogenesis of aGVHD through modulation of the Treg/Teff cell balance during thymic development.IL-27 p28 may be a valuable marker for predicting aGVHD development after transplantation in humans.