Cytokine that plays a crucial role in innate immunity of the epithelium, including to intestinal bacterial pathogens, in an autocrine manner. Stimulates the production of antibacterial peptides and pro-inflammatory molecules for host defense by signaling through the NF-kappa-B and MAPK pathways. Acts synergically with IL22 in inducing the expression of antibacterial peptides, including S100A8, S100A9, REG3A and REG3G. Synergy is also observed with TNF and IL1B in inducing DEFB2 from keratinocytes. Depending on the type of insult, may have both protective and pathogenic properties, either by maintaining epithelial homeostasis after an inflammatory challenge or by promoting inflammatory phenotype. Enhanced IL17C/IL17RE signaling may also lead to greater susceptibility to autoimmune diseases. Binds to a heterodimer formed by IL17RA and IL17RE. Up-regulated by bacterial stimuli, including by lipopolysaccharides (LPS) in gut epithelial cell lines. This up-regulation may be mediated by Toll-like receptors TLR2 and TLR5. Up-regulated by various pro-inflammatory cytokines, including TNF, IL1B and IL17F. Up-regulation by IL17A in colon epithelial cells has been observed in some cases (PubMed:21993849), but not in others (PubMed:21993848). Belongs to the IL-17 family. Interleukin-17 entry