Upregulation of Prostasin in Nasal Polyps

ABSTRACT

OBJECTIVES/HYPOTHESIS: Prostasin is a protease that activates epithelial sodium channels (ENaC), which mediate Na+ absorption across epithelial surfaces. Human nasal polyps absorb more ENaC-mediated Na+ than normal mucosa. We investigated the expression and distribution of prostasin in normal mucosa and nasal polyp. STUDY DESIGN: This was a controlled, prospective study. METHODS: The distribution patterns and levels of expression of prostasin in normal sinus mucosa and nasal polyps were evaluated using real-time polymerase chain reaction (PCR), immunohistochemical staining and western blotting. RESULTS: Real-time PCR revealed that the mRNA expression of prostasin was higher in nasal polyps than in normal sinus mucosa. The expression of prostasin was faint in immunohistochemical staining of superficial epithelial cells and submucosal glandular epithelial cells of normal sinus mucosa, but was intense in superficial epithelial cells and submucosal glandular epithelial cells in nasal polyps. Inflammatory cells infiltrating into the nasal mucosa also showed prostasin immunoreactivity in nasal polyps. Western blot analysis with prostasin antiserum detected prostasin protein in normal sinus mucosa and nasal polyps. The expression levels of prostasin were increased in nasal polyps compared with normal sinus mucosa. CONCLUSIONS: The levels of expression of prostasin were upregulated in nasal polyps compared to normal sinus mucosa, suggesting a role in the pathogenesis of nasal polyps. However, the exact pathophysiologic function of prostasin in nasal epithelium warrants further investigation.