Comparison of biomarkers in serum and induced sputum of patients with occupational asthma and chronic obstructive pulmonary disease

Objectives: Occupational asthma and chronic obstructive pulmonary disease (COPD) are associated with the airway inflammatory process. The aim of this study was to compare the sputum and serum markers of inflammation in patients with occupational asthma and COPD. Methods: The study group included 20 patients with stable COPD, 24 patients with asthma, and 22 healthy subjects. Interleukin (IL)-6, IL-1 beta, tumor necrosis factor (TNF)-alpha, matrix metalloproteinase (MMP)-9 levels in serum and induced sputum as well as fibrinogen and CRP in serum were determined in all the subjects. Results: Higher concentrations of IL-1 beta, IL-6, TNF-alpha, and MMP-9 in induced sputum and an increased concentration of acute-phase proteins in serum were observed in COPD patients compared with healthy subjects. Higher concentrations of IL-1 beta and MMP-9 in induced sputum and a higher concentration of C-reactive protein (CRP) were detected in COPD patients than in asthmatic subjects. Never smokers with COPD had significantly higher levels of IL-1 beta and MMP-9 in induced sputum than never smoker controls. There was no significant difference between the serum and sputum levels of cytokines and MMP-9 of never smokers and smokers with COPD. Conclusions: Higher concentrations of IL-1 beta and MMP-9 in induced sputum and a higher concentration of CRP in serum allow distinguishing between biomarker profiles of COPD patients and asthmatic patients. Occupational exposure induces a systemic proinflammatory state with increased levels of acute-phase proteins in stable COPD patients. MMP-9 and IL-1 beta concentrations are increased in induced sputum of never smokers with COPD, which is associated with occupational exposure.