Transient elevation of neutrophil proteinases in induced sputum during COPD exacerbation.

OBJECTIVE: Patients with chronic obstructive pulmonary disease (COPD) are prone to acute exacerbations associated with increased morbidity and mortality. One potential group of enzymes causing tissue destruction in this disease includes neutrophil proteinase elastase (NE), collagenase-2 (matrix metalloproteinase-8 (MMP-8)) and gelatinase B (MMP-9). We investigated the activity of NE and the levels of MMP-8 and MMP-9 in a longitudinal setting at and after COPD exacerbation using a non-invasive technique, i.e., induced sputum, to ascertain whether these proteinases play a role in COPD exacerbation. MATERIAL AND METHODS: The study included healthy non-smokers (n=32), healthy smokers (n=28), patients with stable COPD (n=15), COPD patients with acute exacerbations (exa) (n=10) and their recovery (n=8) after 4 weeks. NE activity by synthetic peptide substrate and spectrophotometry, MMP-8 levels by immunofluorometry and MMP-9 levels by ELISA were analysed from induced sputum supernatants. RESULTS: NE activity and the level of MMP-8 increased highly significantly in patients with COPD exacerbation compared to stable COPD and controls (NE: p = 0.001 and p < 0.0001; MMP-8: p < 0.001 and p < 0.0001). Paired samples showed a decrease of these proteinases during the recovery period after exacerbation (p = 0.03, p = 0.04). The proteinase levels correlated not only with the percentage and number of neutrophils but also with the lung function parameters (FEV1/FVC and diffusion capacity). CONCLUSIONS: COPD exacerbations are associated with neutrophil recruitment into the airways but also transient activation and/or elevation of tissue destruction proteinases, such as NE and MMP-8, which can be detected from the induced sputum supernatants of these COPD patients.

Glutathione S-transferase omega in the lung and sputum supernatants of COPD patients.

BACKGROUND: The major contribution to oxidant related lung damage in COPD is from the oxidant/antioxidant imbalance and possibly impaired antioxidant defence. Glutathione (GSH) is one of the most important antioxidants in human lung and lung secretions, but the mechanisms participating in its homeostasis are partly unclear. Glutathione-S-transferase omega (GSTO) is a recently characterized cysteine containing enzyme with the capability to bind and release GSH in vitro. GSTO has not been investigated in human lung or lung diseases. METHODS: GSTO1-1 was investigated by immunohistochemistry and Western blot analysis in 72 lung tissue specimens and 40 sputum specimens from non-smokers, smokers and COPD, in bronchoalveolar lavage fluid and in plasma from healthy non-smokers and smokers. It was also examined in human monocytes and bronchial epithelial cells and their culture mediums in vitro. RESULTS: GSTO1-1 was mainly expressed in alveolar macrophages, but it was also found in airway and alveolar epithelium and in extracellular fluids including sputum supernatants, bronchoalveolar lavage fluid, plasma and cell culture mediums. The levels of GSTO1-1 were significantly lower in the sputum supernatants (p = 0.023) and lung homogenates (p = 0.003) of COPD patients than in non-smokers. CONCLUSION: GSTO1-1 is abundant in the alveolar macrophages, but it is also present in extracellular fluids and in airway secretions, the levels being decreased in COPD. The clinical significance of GSTO1-1 and its role in regulating GSH homeostasis in airway secretions, however, needs further investigations.

Modulation of glutaredoxin in the lung and sputum of cigarette smokers and chronic obstructive pulmonary disease.

BACKGROUND: One typical feature in chronic obstructive pulmonary disease (COPD) is the disturbance of the oxidant/antioxidant balance. Glutaredoxins (Grx) are thiol disulfide oxido-reductases with antioxidant capacity and catalytic functions closely associated with glutathione, the major small molecular weight antioxidant of human lung. However, the role of Grxs in smoking related diseases is unclear. METHODS: Immunohistochemical and Western blot analyses were conducted with lung specimens (n = 45 and n = 32, respectively) and induced sputum (n = 50) of healthy non-smokers and smokers without COPD and at different stages of COPD. RESULTS: Grx1 was expressed mainly in alveolar macrophages. The percentage of Grx1 positive macrophages was significantly lower in GOLD stage IV COPD than in healthy smokers (p = 0.021) and the level of Grx1 in total lung homogenate decreased both in stage I-II (p = 0.045) and stage IV COPD (p = 0.022). The percentage of Grx1 positive macrophages correlated with the lung function parameters (FEV1, r = 0.45, p = 0.008; FEV1%, r = 0.46, p = 0.007, FEV/FVC%, r = 0.55, p = 0.001). Grx1 could also be detected in sputum supernatants, the levels being increased in the supernatants from acute exacerbations of COPD compared to non-smokers (p = 0.013) and smokers (p = 0.051). CONCLUSION: The present cross-sectional study showed that Grx1 was expressed mainly in alveolar macrophages, the levels being decreased in COPD patients. In addition, the results also demonstrated the presence of Grx1 in extracellular fluids including sputum supernatants. Overall, the present study suggests that Grx1 is a potential redox modulatory protein regulating the intracellular as well as extracellular homeostasis of glutathionylated proteins and GSH in human lung.