IL-22 contributes to barrier protection by eliciting the production of mucus and antimicrobial peptides and assisting in wound healing. However, excessive IL-22 signaling can be deleterious. In the Journal of Experimental Medicine, Jinnohara et al. show that IL-22BP, a soluble IL-22 receptor and inhibitor of IL-22, is expressed exclusively by CD11b+CD8α− dendritic cells in the subepithelial dome of Peyer's patches. Loss of IL-22BP leads to increased IL-22–STAT3 signaling and subsequent increased mucus production and fucosylation of intestinal epithelial cells, as well as increased production of antimicrobial peptides. This leads to diminished uptake of luminal antigens and decreased antigen presentation within the Peyer's patches. However, IL-22BP-deficient mice do not show substantial changes in the production of immunoglobulin A or alterations in microbial composition. Whether loss of IL-22BP results in altered immune responses to gut pathogens remains unclear.

J. Exp. Med. (16 May 2017) doi:10.1084/jem.20160770