Reduced expression of COXs and production of prostaglandin E(2) in patients with nasal polyps with or without aspirin-intolerant asthma

Abstract

Background: Researchers have debated whether regulation of the COX enzymes (COX-1 and COX-2), which mediate production of prostaglandins (PGs), affects the pathogenesis of nasal polyps (NPs) and aspirin-intolerant asthma (AIA).

Objective: We investigated the roles of PGE(2), COX-1 and COX-2, and PGE(2) receptors in the development of NPs and AIA by measuring their expression in fibroblasts derived from nasal mucosa (NM) and NPs.

Methods: Fibroblasts were isolated from the NM of subjects without asthma who had septal deviation, turbinate hypertrophy, or both (control subjects, n = 7); NPs of aspirin-tolerant nonasthmatic patients (n = 7); and NPs of patients with asthma who were intolerant of aspirin (n = 7). Polyp samples were collected during endoscopic surgery. Cultures were stimulated with IL-1β (10 ng/mL) for 72 hours. We used ELISA, immunoblotting, and immunofluorescence analyses to measure secretion of PGE(2), expression of COX-1 and COX-2, and expression of the PGE(2) receptors EP1 to EP4.

Results: Compared with NM from control subjects, PGE(2) concentrations were significantly lower in IL-1β-stimulated fibroblasts from patients with NPs who were tolerant to aspirin and even lower in polyps from patients with AIA. Similarly, IL-1β exposure induced the expression of COX-1 and COX-2 in fibroblasts from NM of control subjects, had only moderate effects on fibroblasts from NPs of aspirin-tolerant nonasthmatic patients, and almost no effect on fibroblasts from NPs of patients with AIA. IL-1β also induced expression of EP2 in fibroblasts from control NM but not in fibroblasts from NPs of aspirin-tolerant nonasthmatic patients or those with AIA.

Conclusion: Alterations in the COX pathway (ie, reduced production of PGE(2) and lack of upregulation of COX-1, COX-2, and EP2 under conditions of inflammation) are associated with NPs in patients with or without AIA.