Background: Only dynamic studies can elucidate the discrepancies concerning the expression of the inducible COX-2 gene in inflammatory airway diseases.
Objectives: To quantify the expression and spontaneous regulation of COX-1 and COX-2 mRNAs in nasal polyps and nasal mucosa by real-time PCR.
Methods: Nasal polyps were obtained from 16 aspirin-tolerant patients with asthma/rhinitis (ATAR) and 18 aspirin-intolerant patients with asthma/rhinitis (AIAR) undergoing nasal polypectomy. Nasal mucosa was obtained from 12 subjects undergoing nasal corrective surgery. All specimens were cut into 3 pieces. One was immediately snap-frozen in liquid nitrogen, and the remaining 2 were left at room temperature for 30 or 60 minutes before freezing. Data are presented as medians and 25th to 75th percentiles of 10 6 cDNA molecules/microg total RNA.
Results: Baseline COX-2 mRNA levels were significantly lower in both ATAR (0.45; 0.13-1.20; P <.05) and AIAR (0.24; 0.12-0.41; P <.001) nasal polyps than in nasal mucosa (1.35; 0.52-3.90). COX-2 mRNA expression did not change over time in nasal mucosa but increased significantly in ATAR nasal polyps ( P <.05), reaching similar levels to nasal mucosa after 60 minutes. In contrast, COX-2 mRNA showed no significant change over time in AIAR nasal polyps. COX-1 mRNA was higher in nasal polyps than in nasal mucosa, and its expression was not modified over time in any group of patients.
Conclusion: These results suggest differential kinetics of COX-2 mRNA between nasal mucosa and nasal polyps. AIAR nasal polyps appear to have a greater abnormality of the COX-2 pathway than ATAR.