Eicosanoids and eosinophilic inflammation of airways in stable COPD.

Background: Eosinophilic airway inflammation has been demonstrated in 20%–40% of induced sputum samples from patients with stable COPD. Lipid mediators, like eicosanoids are associated with airway inflammation especially with the eosinophilic pattern. Objectives: To investigate the inflammatory cell patterns and eicosanoids in induced sputum in stable COPD. Methods: Induced sputum was collected in COPD and healthy control subjects. Sputum differential cell count and sputum supernatant concentrations of: 5-HETE, 12-HETE, 15-HETE, 5-oxo-ETE, 12-oxo-ETE, 15-oxo-ETE, LTD4, LTE4, LTB4, PGE2, 8-izo-PGE2, PGD2, PGA2, tetranor-PGE-M, tetranor-PGD-M, PGF2a, 8-izo-PGF2a, TBX2, 11-dehydro-TXB2 were measured. Results: In COPD subjects increased eosinophilia in induced sputum (>2%) was found in 42% of subjects (including 34% eosinophilic and 8% mixed eosinophilic and neutrophilic patterns). There was a statistically significant correlation between sputum eosinophilia and induced sputum concentrations of LTE4, LTD4, PGE2, 8-izo-PGE2, 15-HETE,15-oxo-ETE, PGD2, TBX2 and 11-dehydro-TBX2. Induced sputum concentrations of LTE4, LTD4, PGD2, PGE2, 8-izo-PGE2 were significantly higher in COPD subjects compared to healthy controls, whereas concentrations of tetranor-PGE-M and tetranor-PGD-M were lower. Frequent exacerbator COPD subjects had lower sputum but not blood eosinophilia. Conclusions: Stable COPD is often associated with eosinophil influx in the lower airways and elevated concentrations of eicosanoids. Increased sputum eosinophilia is not associated with frequent exacerbations of COPD.