MUCIN GENE-EXPRESSION (MUC1, MUC2, AND MUC5 5AC) IN NASAL EPITHELIAL-CELLS OF CYSTIC-FIBROSIS, ALLERGIC RHINITIS, AND NORMAL INDIVIDUALS/

The early pathogenic events in cystic fibrosis (CF) include colonizati on of Pseudomonas in the lung, airway inflammation, and mucus hypersec retion with airway obstruction. The primary mechanisms leading to chro nic infection and inflammation are not well understood. One possible e xplanation for this cascade of events is increased or altered expressi on of one or more mucin (MUC) genes by CF cells in the respiratory tra ct. We compared expression levels of three mucin genes, MUC1, MUC2, an d MUC5/5AC, known to be expressed in the respiratory tract of CF, alle rgic rhinitis, and normal individuals. Mucin transcript levels in nasa l epithelial cells free from inflammation were quantitated by an MUC m RNA slot-blot method, This study revealed three major findings: (1) MU C5/5AC mRNA was expressed at five- to tenfold greater levels than MUC2 or MUC1 for all subjects. (2) MUC2 mRNA levels were similar among all subject groups. (3) In CF subjects, there was a trend toward reduced MUC5/5AC expression. When normalized to the levels of MUC2 expression in individual specimens, MUC5/5AC expression was reduced significantly in CF cells compared with normal cells. These data suggest that mucin gene expression is altered in noninflamed CF nasal cells.