Polarized secreted IL-17C is a mediator of respiratory epithelial innate immune response

The IL-17 family of cytokines consists of at least six members (IL-17A to -F). IL-17 directly activates epithelial cells leading to the expression of inflammatory mediators and antimicrobial factors. In this study, our aim was to examine the expression and function of IL-17C in respiratory epithelial cells during bacterial infection. In vitro studies showed that common bacterial pathogens, such as Pseudomonas aeruginosa and Haemophilus influenzae, and ligands of Toll-like receptors 3 and 5 (flagellin, polyI:C) induced the expression and release of IL-17C in cultured human bronchial epithelial cells. Differentiat…