Increased oxidation of extracellular glutathione by bronchoalveolar inflammatory cells in diffuse fibrosing alveolitis

Abstract

An unbalanced oxidative stress is thought to be an important element in the pathogenesis of diffuse fibrosing alveolitis (DFA). The purpose of our study was to investigate the role of reactive oxygen metabolites (ROMs) released from cultured bronchoalveolar inflammatory cells (BA-cells) on glutathione oxidation. We studied bronchoalveolar lavage samples from 10 healthy controls and from 20 patients with diffuse fibrosing alveolitis (all were nonsmokers). BA-cells obtained by bronchoalveolar lavage (BAL) were incubated with 50 microM of reduced glutathione (GSH). Oxidation of GSH to glutathione disulphide (GSSG) by BA-cell derived oxidants was detected as a decline of GSH in the supernatants. Total glutathione (GSHtot = GSH + 2 GSSG) and GSSG in the epithelial lining fluid (ELF), and methionine sulphoxide (Met(O)) content of BAL proteins were determined. In diffuse fibrosing alveolitis the oxidative activity of BA-cells was enhanced, GSHtot and GSH were decreased, whereas the GSSG:GSH ratio was increased. The oxidative activity of BA-cells correlated positively with the GSSG:GSH ratio, but not with the methionine sulphoxide content. The methionine sulphoxide content was elevated in diffuse fibrosing alveolitis and inversely correlated with GSHtot. The methionine sulphoxide content also correlated positively with the percentage of BAL neutrophils. We conclude that BA-cell-derived reactive oxygen species are capable of oxidizing extracellular GSH in vitro. The positive correlation between the BA-cell oxidative activity in vitro and GSSG:GSH ratio in ELF suggests that a similar oxidative effect on extracellular GSH may also occur in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)