MUC8 mucin gene up-regulation in chronic rhinosinusitis

The primary mechanisms leading to mucus hypersecretion in chronic sinus inflammation are not well understood. This study aims to investigate the expression of MUC8 messenger RNA (mRNA) and protein and to compare between normal and chronically inflamed sinus mucosae in terms of the expression of MUC8 mRNA. Ten patients with chronic rhinosinusitis who were undergoing functional endoscopic sinus surgery were recruited for the study. Ten patients with no evidence of sinus disease were used as control subjects. RNAs were extracted from sinus mucosa, and semiquantitative reverse transcription-polymerase chain reaction was performed for MUC8. Localization of MUC8 protein was sought by immunohistochemical analysis. Messenger RNA encoding MUC8 was detected in human sinus mucosa. The level of MUC8 mRNA in chronic rhinosinusitis was significantly increased compared with that in normal maxillary sinus mucosa. We found more intense expression of MUC8 protein in the sinuses with chronic rhinosinusitis than in normal sinus mucosa. These results suggest that MUC8 may play an important role in the pathogenesis of sinus hypersecretion in chronic rhinosinusitis.