IL-22-dependent dysbiosis and mononuclear phagocyte depletion contribute to steroid-resistant gut graft-versus-host disease in mice II

CD4+ and CD8+ T cells can reciprocally differentiate into Th/Tc1, Th/Tc17 and Th/Tc22. Although alloreactive Th/Tc1 cells play a critical role in initiating pathogenesis of gut acute graft-versus-host disease (Gut-aGVHD), the pathogenic T cells in steroid-resistant Gut-aGVHD (SR-Gut-aGVHD) remains unclear. Here, we show that in murine models of SR-Gut-aGVHD, the pathogenesis is associated with reduction of IFN-g+ Th/Tc1 and IL-17A+IL-22- Th/Tc17 cells but expansion of IL-17-IL-22+ Th/Tc22, particularly Tc22 cells. The IL-22 from Th/Tc22 cells causes dysbiosis. Overall design: Examination of gut microbiome difference in the mouse model of acute gut GVHD