A role for CD47 in the development of experimental colitis mediated by SIRPα+CD103− dendritic cells

Abstract

Mesenteric lymph node (mLN) CD103 (αE integrin)⁺ dendritic cells (DCs) induce regulatory T cells and gut tolerance. However, the function of intestinal CD103⁻ DCs remains to be clarified. CD47 is the ligand of signal regulatory protein α (SIRPα) and promotes SIRPα⁺ myeloid cell migration. We first show that mucosal CD103⁻ DCs selectively express SIRPα and that their frequency was augmented in the lamina propria and mLNs of mice that developed Th17-biased colitis in response to trinitrobenzene sulfonic acid. In contrast, the percentage of SIRPα⁺CD103⁻ DCs and Th17 responses were decreased in CD47-deficient (CD47 knockout [KO]) mice, which remained protected from colitis. We next demonstrate that transferring wild-type (WT), but not CD47 KO, SIRPα⁺CD103⁻ DCs in CD47 KO mice elicited severe Th17-associated wasting disease. CD47 expression was required on the SIRPα⁺CD103⁻ DCs for efficient trafficking to mLNs in vivo, whereas it was dispensable on both DCs and T cells for Th17 polarization in vitro. Finally, administration of a CD47-Fc molecule resulted in reduced SIRPα⁺CD103⁻ DC–mediated Th17 responses and the protection of WT mice from colitis. We thus propose SIRPα⁺CD103⁻ DCs as a pathogenic DC subset that drives Th17-biased responses and colitis, and the CD47–SIRPα axis as a potential therapeutic target for inflammatory bowel disease.