Dock2 Deficiency Exacerbates Colitis by Impairing Akkermansia muciniphila Colonization via the IL-22–Reg3 Antimicrobial Axis Suppressed by Type 1 T Cell Responses

While Dock2 is predominantly expressed in intestinal T cells and is significantly upregulated in patients with inflammatory bowel diseases (IBD), its precise role in intestinal inflammation remains obscure. In this study, we demonstrate that systemic Dock2-deficient mice and T cell-specific Dock2 conditional knockout (Dock2-cKO) mice exhibit exacerbated chemically induced colitis compared to wild-type (WT) controls.

Dock2 deficiency led to a substantial reduction in both total and IFN-γ-producing CD8+ T cells, accompanied by elevated colonic IL-22 levels, increased expression of Reg3γ and Reg3β antimicrobial peptides (AMPs), and diminished colonization by Verrucomicrobia, particularly Akkermansia muciniphila (A. muciniphila), at steady state. The expression of Reg3γ&β was suppressed in IL-22- and RORγt-deficient mice, and these AMPs exhibited antimicrobial activity against the expansion and intestinal colonization of A. muciniphila.