Inflammation, oxidative stress and systemic effects in mild chronic obstructive pulmonary disease

Chronic obstructive pulmonary diseases (COPD) is a pulmonary disease characterized by systemic abnormalities. The aim of this study is to investigate inflammation and systemic effects in mild COPD. Twenty-seven mild stable smoking related COPD patients and 15 age-matched healthy subjects were enrolled in the study. IL-6, TNF-alpha and IL-4 in plasma, sputum and exhaled breath condensate were measured. We also measured exhaled nitric oxide (NO) and pH in sputum and in breath condensate. Moreover, fat-free mass, body mass index (BMI), respiratory muscle strength, plasma oxidative stress and C-reactive protein (CRP) were measured. Higher concentrations were found of CRP, of diacron reactive oxygen metabolites (DROMs) and of IL-6, TNF-alpha and IL-4 either in plasma or in supernatant of induced sputum or in exhaled breath condensate of COPD subjects compared to healthy controls. Furthermore, higher concentrations were observed of exhaled NO and lower exhaled pH in breath condensate of COPD when compared with healthy subjects. In the group of COPD patients, the subjects with airway reversibility showed an increase of sputum eosinophils and exhaled NO, whereas the subjects without airway obstruction reversibility showed an increase in sputum neutrophils, TNF-alpha and IL-6. We also found a trend towards a decrease in fat-free mass and respiratory muscle strength in COPD compared to healthy subjects and a negative correlation between these systemic indices (fat-free mass, maximal inspiratory pressure, maximal expiratory pressure) and TNF-alpha concentrations in the blood, sputum and breath condensate. We conclude that mild COPD subjects present an increase in inflammatory markers in blood and in airways of similar pattern and furthermore, the neutrophilic pattern of airway inflammation observed in the group of COPD subjects without an airway obstruction reversibility makes it more likely that systemic features are present.