Cyclooxygenase and lipoxygenase metabolite generation in nasal polyps

Abstract

A role of prostaglandins (PGs) and leukotrienes (LTs) in the pathogenesis of nasal polyps has been recently suggested. Cyclooxygenase (CO) products (thromboxane B 2, PGE 2 and 6-keto PGF 1 alpha) and lipoxygenase (LO) products (LTB 4 and LTC 4) were investigated by radioimmunoassay in polyps, hypertrophic turbinates and nasal mucosa from 14 patients with non-allergic ( n = 6), allergic chronic rhinitis ( n = 6) and aspirin-sensitive asthma (ASA) ( n = 2), who underwent polypectomy. In all tissues CO metabolite levels were found higher than LO products ( P < 0.01). Nasal polyps showed a significantly lower ( P < 0.05) arachidonic acid (AA) metabolism in comparison to nasal mucosa. In polyps of allergic patients significantly higher LTB 4 levels ( P < 0.001) and a tendency to produce higher amounts of CO products in comparison to non-allergic subjects were observed, whereas in turbinates of non-allergic patients LT levels were significantly higher in comparison to those of allergic ones ( P < 0.01). In ASA patients a decreased CO LO ratio was found supporting the hypothesis of an imbalance of AA metabolism in this syndrome. These findings seem to indicate that the occurrence of nasal polyps may represent the result of different chronic inflammatory stimuli, regulated in part by AA metabolites.