Interleukin-13 Suppresses MUC5AC Gene Expression and Mucin Secretion in Cultured Normal Human Nasal Epithelial Cells

Background and Objectives：It is not clear which mucins are responsible for the mucus hypersecretion in allergic rhinitis and allergic asthma. Recently, it was found that IL-13 is closely related to 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. Materials and Method：Cells were cultured with passage-2 normal human nasal epithelial cells using the air-liquid interface culture method. After treatment with IL-13, the total mucin and MUC5AC mucin levels were measured using the immuno-blotting assay. The MUC2, MUC5AC, and MUC8 mRNA expressions were measured using RT-PCR. Immunostaining was also performed using a MUC5AC antibody on histologic and cytospin slides. Results：After treatment with 5 ng/ml or more of 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 with immunostaining. Conclusion：These findings indicate that IL-13 suppresses MUC5AC mucin gene expression and mucin secretion in cultured normal human nasal epithelial cells in vitro.ope