Upregulation of COX-1 and COX-2 in nasal polyps in cystic fibrosis

Background: Since abnormalities in prostanoid metabolism occur in the lower airway of patients with cystic fibrosis (CF), it is likely that they could also be detected in the nose. Methods: The degree of mRNA and protein expression of cyclo-oxygenase (COX) enzymes 1 (COX-1) and 2 (COX-2) was examined using quantitative reverse competitive polymerase chain reaction (RT-PCR) and Western blot analysis in the nasal polyps from 10 patients with CF, nasal polyps from 10 non-CF patients and 11 nasal mucosa specimens. The results are presented as 106 cDNA molecules/μg total RNA and the densitometric ratio between protein and β-actin. Results: COX-1 mRNA levels were significantly higher in CF nasal polyps (median 2.34, 25–75th percentiles 1.6–3.2) than in the nasal mucosa (0.78, 0.11–1.21), while there was no difference with non-CF nasal polyps (1.11, 0.80–3.15). COX-1 protein levels were significantly higher in CF nasal polyps (3.63, 2.71–4.27) than in nasal mucosa (1.55, 0.66–2.33) and non-CF nasal polyps (2.19, 1.72–3.68). COX-2 mRNA was significantly higher in CF nasal polyps (3.34, 2.42–7.05) than in nasal mucosa (1.69, 0.19–3.50). No differences were found in COX-2 mRNA expression between CF and non-CF polyps (1.38, 0.12–6.07). COX-2 protein levels were also significantly higher in CF nasal polyps (0.23, 0.04–0.34) than in non-CF nasal polyps (0.011, 0.009–0.016) or nasal mucosa (0.014, 0.014–0.016). Conclusions: Upregulation in the expression of COX-1 and COX-2 could explain the high production of prostanoids reported in CF. These findings raise questions regarding the potential use of selective or non-selective COX-2 non-steroidal anti-inflammatory treatment in CF.