Interleukin-17 expression in the human placenta.

Interleukin (IL)-17 is a proinflammatory cytokine with pleiotropic activities including inducing neovascularization and production of proangiogenic molecules. As pregnancy outcome depends on the balance of Th1-like/Th2-like cytokines and an increased blood supply to the fetoplacental unit, the expression of IL-17 mRNA and protein in human placental tissues was investigated. IL-17 mRNA was expressed by purified cytokeratin-positive term placental trophoblast cells, HLA-G+ extravillous trophoblast cells and placental macrophages (Hofbauer cells). IL-17 localized in both cyto- and syncytiotrophoblasts of normal term pregnancy, spontaneous miscarriage and in molar pregnancy. In spontaneous miscarriage and molar pregnancy extravillous trophoblast cells were consistently immunoreactive for IL-17. IL-17 expression in human placenta may play a key role in angiogenesis and/or immunoregulation in the establishment of pregnancy.