Role of IL-25 in Immunity.

IL-25 a 2o KDa protein mostly known as IL-17E, encoded by chromosome 14, and containing 117 amino acids. Cytokine IL-17 family consists of 6 members; IL-17A to IL-17F, among which IL-25 has a unique structure and function. The receptor of IL-25 (IL-17BR) is highly expressed in the main Th2 cells. IL-25 regulates the internal safety of adaptive immune responses which leads to begin allergic diseases and plays a role in stimulation of pulmonary mucosal cells and fibroblasts. IL-25 can also have some effects on production of other cytokines. For instance, production of IL-25 in human and mice or injection of IL-25 to animals has resulted in production of high concentrations of Th2 cytokines, including IL-4, IL-5, and IL-13. Pilot studies have shown that mRNA of IL-25 has a high expression in Th2 cells. However, the mechanism through which IL-25 leads to Th2 immune response is still unknown. Reaction between IL-25 and IL-17BR leads to activation of transcription factors, such as NF-KB, STAT6, GATA3, NF-ATC1, JUNNB, MAPK, and JNK. IL-25 has been used against the kidney damage in mice. A large number of researchers in various countries, including the U.S. and Taiwan, have stated that IL-25 is a strong inflammatory cytokine protein which is involved in allergic inflammations.