Inhibition of reactive nitrogen species production in COPD airways: comparison of inhaled corticosteroid and oral theophylline

Background: Reactive nitrogen species (RNS) are thought to be one of the important factors in the pathogenesis of chronic obstructive pulmonary disease (COPD). A study was undertaken to examine the effects of theophylline and fluticasone propionate (FP) on RNS production in subjects with COPD. Methods: Sixteen COPD subjects participated in the study. Theophylline (400 mg/day orally) or FP (400 mg/day inhalation) were administered for 4 weeks in a randomised crossover manner with a washout period of 4 weeks. Induced sputum was collected at the beginning and end of each treatment period. 3-nitrotyrosine (3-NT), which is a footprint of RNS, was quantified by high performance liquid chromatography with an electrochemical detection method as well as by immunohistochemical staining. Results: Theophylline significantly reduced the level of 3-NT in the sputum supernatant as well as the number of 3-NT positive cells (both p < 0.01). FP also reduced 3-NT formation, but the effect was smaller than that of theophylline. Theophylline also significantly reduced the neutrophil cell counts in the sputum (p < 0.01), while FP treatment had no effect on the number of inflammatory cells in the sputum, except eosinophils. Conclusions: Theophylline reduces nitrative stress and neutrophil infiltration in COPD airways to a larger extent than inhaled corticosteroid.