Distribution of respiratory mucin proteins in human nasal mucosa

Objectives/Hypothesis: The upper respiratory tract is involved in many acute and chronic respiratory tract diseases that present with the symptom of mucus hypersecretion. Mucin genes that encode for the backbone of glycoproteins contribute to the viscoelastic property of airway mucus. We examined the cellular expression and distribution of two major respiratory mucus-forming glycoproteins, MUC5AC and MUC5B, in normal human nasal tissues. Methods: Immunohistochemical analysis using polyclonal antibodies against the mucins MUC5AC and MUC5B was performed in normal human nasal tissues. Results: An abundant staining of submucosal mucus gland and epithelial goblet cells for MUC5B was found. hnmunohistochemical analysis of MUC5AC showed staining of surface epithelium goblet cells, whereas there was no staining of glandular cells. Comparison of the expression to lower airways revealed a similar pattern of expression of both mucins. Conclusions: The data in the present study demonstrated the localization of the two major respiratory mucin proteins in human nasal mucosa with a similar distribution of expression of MUC5AC and MUC5B in normal upper and lower airways. Mucin protein expression parallels that of mucin messenger RNA expression.