DR3 antibody ligation aggravates colitis by stimulating ILC3 granulocyte–macrophage colony-stimulating factor production via the p38 MAPK (mitogen-activated protein kinase) pathway, resulting in the accumulation of CD11b+ CD11c+ myeloid cells and the facilitation of ILC3 loss from the intestine via an IL-23-dependent mechanism. The gene discussed is TNFRSF25; the disease is colitis.