IL-13 suppresses MUC5AC gene expression and mucin secretion in nasal epithelial cells.

Recently, it was found that IL-13 is involved in allergic inflammation and mucus hypersecretion in in vivo animal models. However, the role of IL-13 in in vitro cellular models has yet to be determined. This study aimed to investigate the direct effect of IL-13 on mucin gene expression and mucin secretion in cultured normal human nasal epithelial cells. After treatment with IL-13, total mucin and MUC5AC mucin levels were measured using an immunoblotting assay. MUC2, MUC5AC and MUC8 mRNA expression were determined using reverse transcription-polymerase chain reaction. Also, immunostaining was performed using a MUC5AC antibody on histologic and cytospin slides. After treatment with > or = 5 ng/ml IL-13, the level of total mucin and MUC5AC mucin secretion decreased substantially. The expression of MUC2 and MUC8 mRNA increased with higher concentrations of IL-13, but the expression of MUC5AC mRNA decreased. On the 7th day after IL-13 treatment, a significant decrease in the number of MUC5AC-positive cells was confirmed by immunostaining. These findings indicate that IL-13 suppresses MUC5AC mucin gene expression and mucin secretion in cultured normal human nasal epithelial cells in vitro.