Interleukin-17C is a 15-20 kDa disulfide-linked dimeric cytokine that plays an important role in mucosal immunity and chronic inflammation. IL-17C binds to IL-17 RE with high affinity and to IL-17 RA with low affinity. These two receptor chains can associate into a heterodimeric receptor for IL-17C. IL-17C expression is induced by inflammatory stimulation in colon and airway epithelial cells, keratinocytes, CD4+ T cells, macrophages, and dendritic cells. It is upregulated in various chronic inflammatory diseases including psoriasis, cystic fibrosis, and chronic obstructive pulmonary disease (COPD). The interaction of IL-17C with IL-17 RE promotes mucosal immunity through the induction of anti-bacterial peptides and pro-inflammatory cytokines and chemokines. IL-17C action supports the integrity of the colon epithelium following infection induced damage but also contributes to psoriatic skin thickening and the progression of arthritis.
