Expression of MUC5AC mRNA in the goblet cells of human nasal mucosa.
Mucus hypersecretion is a common feature in chronic sinusitis with polyps. Because mucus hypersecretion is commonly accompanied by goblet cell hyperplasia, it is important to identify which mucin gene mRNAs are expressed in the goblet cells of the surface epithelium in the human airway. This study aims to investigate the pattern of expression of MUC5AC messenger RNA (mRNA) in the goblet cells of human nasal mucosa. Six nasal polyps, five inferior turbinate mucosa specimens, and three normal-appearing mucosa specimens of the posterior ethmoid sinus were obtained. Each of the specimens was cut into 10-microm-thick serial frozen sections, and in situ hybridization of MUC5AC mRNA was performed with an oligonucleotide probe. Alcian blue (pH 2.5)-periodic acid-Schiff (AB-PAS) staining was performed on the serial sections. In human nasal polyps, MUC5AC mRNA was expressed in the cytoplasm of most of the goblet cells. However, in the inferior turbinate, MUC5AC mRNA was expressed in only some of the goblet cells. On the contrary, in the normal-appearing mucosa of the posterior ethmoid sinus, MUC5AC mRNA was barely expressed in the goblet cells. Furthermore, MUC5AC mRNA was mainly expressed in some of the PAS-positive goblet cells. Only a portion of the goblet cells in the human nasal mucosa expressed MUC5AC mRNA. This result suggests that surface goblet cells might have other mucin genes, in addition to MUC2 and MUC5AC.