Ide, N.; Sato, k.; Hayashi, K.; Almeida, M. S.; Abe, F.; Kim, T.; Nakahashi-Oda, C.; Shibuya, K.; Shibuya, A.

Innate and adaptive immune responses play critical roles in the pathogenesis of inflammatory bowel disease (IBD), yet the molecular pathways integrating these responses remain elusive. Here, we identify DNAM-1 immunoreceptor as a central driver of colitis through distinct, cell type-specific mechanisms. Transcriptomic analyses of human and murine group 3 innate lymphoid cells (ILC3s) revealed DNAM-1 as a conserved IL-23-responsive surface molecule associated with inflammatory cytokine production. In an innate immune-driven anti-CD40 monoclonal antibody (mAb)-induced colitis model, DNAM-1 expressed on ILC3s promoted intestinal inflammation by enhancing IL-22 and GM-CSF production via the integration of the Akt-mTORC1-HIF-1 signaling pathway. Genetic ablation or antibody-mediated blockade of DNAM-1 attenuated inflammatory cytokine production and disease severity. Paradoxically, in T cell-dependent colitis, DNAM-1 expression on dendritic cells, but not on ILC3s or CD4 T cells, exacerbated disease by promoting dendritic cell activation and pathogenic Th1 and Th17 differentiation. Notably, therapeutic blockade of DNAM-1 ameliorated disease in both colitis models and exerted complementary effects when combined with anti-TNF therapy, accompanied by modulation of immune activation programs distinct from those regulated by TNF inhibition. Collectively, these findings establish DNAM-1 as a pivotal regulator of intestinal inflammation bridging innate and adaptive immunity and identify DNAM-1 blockade as a next-generation therapeutic strategy for IBD.