IL-17C expression in nasal epithelial cells of chronic rhinosinusitis with nasal polyposis.

Interleukin 17C (IL-17C) is a functionally distinct member of the IL-17 family that is selectively induced in epithelia by bacterial challenge and inflammatory stimuli. The goal of this study was to explore the expression of IL-17C in nasal epithelial cells and their role in the pathogenesis of chronic rhinosinusitis with nasal polyposis (CRSwNPs). IL-17C expression was detected using immunohistochemistry (IHC) of the epithelial cell layers and using the western blot assay on whole tissue homogenates from control subjects (n = 10) and CRSwNP patients [10 non-eosinophilic polyps and 10 eosinophilic polyps (EPs)]. Expression of IL-17C and P47-phox were evaluated in the human nasal epithelial cells (RPMI-2650 cells) after treatment with staphylococcal enterotoxin B (SEB) and pretreatment with reactive oxygen species (ROS) scavenger, N-acetyl L-cysteine (NAC). Finally, IL-17C expression was demonstrated in eosinophilic rhinosinusitis murine model using IHC. Epithelial expression of IL-17C was higher in nasal polyps (especially in EPs) compared to control mucosa. SEB increased the expression of IL-17C and P47-phox in RPMI-2650 cells. SEB-induced expressions of both IL-17C and P47-phox were significantly decreased in NAC-pretreated cells. Epithelial expression of IL-17C was significantly higher in experimental mice compared to control mice. SEB-induced IL-17C expression in nasal epithelial cells is mediated by ROS production. This pathway may be associated with the pathogenesis of CRSwNP, especially eosinophilic nasal polyps.