IL-17 disrupts corneal barrier following desiccating stress

T helper (Th)-17 is a recently identified subtype of Th response that has been implicated in host defense and autoimmunity. We investigated whether there is evidence for a Th-17 response in human and experimental murine dry eye (DE). Gene expression in the human DE conjunctiva showed increased levels of the Th-17 inducers, interleukin (IL)-23, IL-17A, and interferon-gamma (IFN-gamma). In the murine model, we found that desiccating stress increased matrix metalloproteinase-9, Th-17-associated genes (IL-6, IL-23, transforming growth factor-beta1 and -2, IL-23R, IL-17R, IL-17A, retinoid-related orphan receptor-gammat, and CC chemokine attractant ligand-20) and IFN-gamma in cornea and conjunctiva. Furthermore, we found a significantly increased concentration of IL-17 in tears and number of IL-17-producing cells on the ocular surface. Antibody neutralization of IL-17 ameliorated experimental DE-induced corneal epithelial barrier dysfunction and decreased the expression of matrix metalloproteinases 3 and 9. Taken together, these findings suggest that IL-17 has a role in corneal epithelial barrier disruption in DE.