Budesonide Reduces Superoxide and Peroxynitrite Anion Chemiluminescence during Human Neutrophil Bursts

Abstract

Many lung disorders are characterized by airway inflammation involving the recruitment of inflammatory cells, and leading to the release of oxidant and inflammatory mediators. The overproduction of superoxide anion (O₂^–DELETE) and nitric oxide (NO) during the respiratory bursts of neutrophils leads to production of peroxynitrite, a highly damaging oxidant with an important role in the inflammatory loop causing airway hyper-reactivity in respiratory diseases like asthma. The aim of this study was to investigate in vitro the effects of a 1-hour incubation with budesonide at 2.5 × 10^–7, 5 × 10^–7, 1 × 10^–6, 2 × 10^–6 and 4 × 10^–6 mol/l on O₂^–DELETE, NO, and peroxynitrite production during the respiratory burst of human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (fMLP, 5 × 10^–7 mol/l) or phorbol 12-myristate 13-acetate (PMA, 2 × 10^–6 mol/l), as documented by luminol-amplified chemiluminescence (LACL). In absence of L-arginine, budesonide (5 × 10^–7 to 4 × 10^–6 mol/l) dose-dependently reduced both fMLP- and PMA-induced LACL (18.3–50.6%). In the presence of L-arginine (100 µg/ml), a NO donor increasing peroxynitrite production, LACL increased 3–5 times compared with baseline, but budesonide dose-dependently reduced LACL (25.5–59.6%). Mifepristone (4 × 10^–6 mol/l), a glucocorticoid receptor antagonist, inhibited the effect of budesonide on LACL, thus confirming that budesonide reacts with glucocorticoid receptors to exert an antioxidant activity. These results suggest that budesonide target rapidly human neutrophils leading to a fast reduction in both NO and peroxynitrite production, and are consistent with decrease in exhaled NO levels after treatment with budesonide in patients with asthma.