Inflammatory markers in exhaled breath condensate from patients with asthma

Background and objective:   Evaluation of airway inflammation is important for the diagnosis and treatment of asthma. Exhaled breath condensate (EBC) is a minimally invasive method for assessing inflammation and may be useful for monitoring airway inflammation in asthma. The aims of this study were to establish an EBC collection method, to assess biomarkers reflecting asthmatic airway inflammation, and to determine the relationship of these biomarkers with asthma severity and lung function.
Methods:   Fifty-eight non-smoking healthy subjects, seven asymptomatic smokers, nine subjects with common cold and 55 asthmatics with disease severity ranging from mild intermittent to severe persistent were studied. The efficacy of a pipette method was compared with that of a commercial collecting device. pH, CRP, albumin, hydrogen peroxide (H₂O₂) and nitrite/nitrate levels were measured in EBC.
Results:   Except for the quantity of EBC collected and albumin levels, there were no differences between the commercial method and the pipette method in levels of biomarkers measured. Levels of CRP, H₂O₂ and nitrite/nitrate were significantly higher in the asthma group than that in the control group. In terms of asthma severity, pH and levels of CRP, H₂O₂ and nitrate were significantly higher in the mild persistent group than that in the other groups. In addition, H₂O₂ levels in EBC correlated significantly with the level of nitrite/nitrate. FEV₁ and PEF showed significant negative correlations with H₂O₂ and nitrite/nitrate levels.
Conclusion:   Measurement of EBC biomarkers is a non-invasive and useful way to evaluate airway inflammation in patients with asthma.