Hydrogen Peroxide Content and pH of Expired Breath Condensate from Patients with Asthma and COPD

Abstract

Background: Oxidative stress is implicated in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Analysis of the expired breath condensate (EBC) has been suggested to provide non-invasive inflammatory markers that reflect oxidative stress in the airways. Objective: The present study attempts to elucidate whether the hydrogen peroxide (H₂O₂) levels and pH values in EBC may be useful as biomarkers of the activity or severity of asthma and COPD. Methods: We measured the H₂O₂ levels and pH values using a derivatives of reactive oxygen metabolites exhalation test kit (Diacron) and a pH analyser, respectively, in EBC obtained using an EcoScreen from 29 patients with asthma, 33 with COPD, and 33 healthy individuals (all non-smokers). We then examined the relationships among oxidative stress and the asthma control test (ACT) or COPD assessment test (CAT) scores, pulmonary function, fractional exhaled nitric oxide (FeNO), and the extent of low attenuation areas on HRCT. Results: The H₂O₂ levels were elevated and pH was lower in both asthma (H₂O₂; 8.75 ± 0.88 μM, p < 0.01, pH; 7.14 ± 0.07, p < 0.05) and COPD (H₂O₂; 7.44 ± 0.89 μM, p < 0.01, pH; 6.87 ± 0.10, p < 0.01) compared with control subjects (H₂O₂; 3.42 ± 0.66 μM, pH; 7.35 ± 0.04). Neither the H₂O₂ levels nor pH correlated with the ACT scores and FeNO in asthma patients. Neither the H₂O₂ levels nor pH significantly correlated with the pulmonary function in asthma and COPD. However, the CAT scores significantly correlated with the H₂O₂ levels in patients with COPD (r = 0.52, p < 0.01). Conclusions: These findings suggest that oxidative stress is involved in the pathogenesis of asthma and COPD and that the H₂O₂ levels in EBC might reflect the health status in COPD.

Keywords :

• asthma
• biomarkers
• clinical respiratory medicine
• COPD
• inflammation