Interleukin-25 (IL-25) – also known as interleukin-17E (IL-17E) – is a protein that in humans is encoded by the IL25 gene.
IL-25 is a cytokine that shares the sequence similarity with IL-17. This cytokine can induce NF-κB activation, and stimulate the production of IL-8. Both this cytokine and IL17B are ligands for the cytokine receptor IL17RB. Studies of the similar gene in mice suggested that this cytokine may be a proinflammatory cytokine favoring Th2-type immune response. Two alternatively spliced transcript variants of this gene encoding distinct isoforms have been reported.