Interleukin (IL) 36 gamma induces mucin 5AC, oligomeric mucus/gel-forming expression via IL-36 receptor–extracellular signal regulated kinase 1 and 2, and p38–nuclear factor kappa-light-chain-enhancer of activated B cells in human airway epithelial cells

Background: Mucin 5AC, oligomeric mucus/gel-forming (MUC5AC) expression is significantly increased in allergic and inflammatory airway diseases. Interleukin (IL) 36 gamma is predominantly expressed in airway epithelial cells and plays an important role in innate and adaptive immune responses. IL-36 gamma is induced by many inflammatory mediators, including cytokines and bacterial and viral infections. However, the association between IL-36 gamma and mucin secretion in human airway epithelial cells has not yet been fully investigated. Objective: The objective of this study was to determine whether IL-36 gamma might play a role in the regulation of mucin secretion in airway epithelial cells. We investigated the effect and brief signaling pathway of IL-36 gamma on MUC5AC expression in human airway epithelial cells. Methods: Enzyme immunoassay, immunoblot analysis, immunofluorescence staining, reverse transcriptase–polymerase chain reaction (PCR), and real-time PCR were performed in mucin-producing human airway epithelial NCI-H292 cells and in human nasal epithelial cells after pretreatment with IL-36 gamma, several specific inhibitors, or small interfering RNAs (siRNA). Results: IL-36 gamma induced MUC5AC expression and activated the phosphorylation of extracellular signal regulated kinase (ERK) 1 and 2, p38, and nuclear factor-kappa-light-chain-enhancer of activated B cells (NF–kappa B). IL-36 receptor antagonist significantly attenuated these effects. The specific inhibitor and siRNA of ERK1, ERK2, p38, and NF–kappa B significantly attenuated IL-36 gamma induced MUC5AC expression. Conclusion: These results indicated that IL-36 gamma induced MUC5AC expression via the IL-36 receptor–mediated ERK1/2 and p38/NF–kappa B pathway in human airway epithelial cells.