Elevated exhalation of hydrogen peroxide in patients with systemic sclerosis

Background Systemic sclerosis is accompanied by an influx of activated phagocytes into distal airways. These cells release H-2 O-2 , which may evaporate from the airways surface and be detected in expired breath condensate. We tested whether patients with systemic sclerosis exhale more H-2 O-2 than healthy subjects and whether breath condensate H-2 O-2 levels correlate with some clinical parameters. Materials and methods H-2 O-2 was measured fluorimetrically in the expired breath condensate of 27 patients (22 women, five men, mean age 49 +/- 13.1 years) with systemic sclerosis and 27 age- and sex- matched healthy controls. Results Exhaled H-2 O-2 levels were 3.5-fold higher (0.88 +/- 0.62 muM vs. 0.25 +/- 0.17 muM, P < 0.001) in the patients with systemic sclerosis than in the controls. Treatment with cyclophosphamide and/or prednisone (29 +/- 50 months, range 3-168 months) did not significantly decrease H-2 O-2 exhalation (0.78 +/- 0.50 muM, n = 10 vs. 0.94 +/- 0.67 muM, n = 17, P > 0.05). No significant difference was found between patients with limited and diffuse scleroderma (1.03 +/- 0.69 muM, n = 17 vs. 0.63 +/- 0.41 muM, n = 10, P > 0.05). H-2 O-2 levels correlated with disease duration (r = 0.38, P < 0.05) and time from the first Raynaud's episode (r = 0.44, P < 0.05). Conclusions Patients with systemic sclerosis exhale more H-2 O-2 than healthy controls, suggesting involvement of reactive oxygen species in disease processes. Lack of significant intergroups differences in H-2 O-2 levels may have resulted from the small number of patients analyzed.