Inflammatory Mediators in Exhaled Breath Condensate and Peripheral Blood of Healthy Donors and Stable COPD Patients

The aim of this work was to compare matrix metalloproteinase-9 and -12, tissue inhibitor of metalloproteinase-1 and -4, and neutrophil elastase in exhaled breath condensate (EBC) and peripheral blood of patients with COPD. Peripheral blood and EBC samples from COPD patients and healthy donors were collected. In serum and EBC, MMP-9, MMP-12, NE, TIMP-1, and TIMP-4 proteins were detected by ELISA. The mRNA expression levels of MMP-9, MMP-12, NE, TIMP-1, and TIMP-4 in peripheral blood mononuclear cells (PBMCs) were analyzed by qRT-PCR. The protein levels of MMP-9 (=.034) and MMP-12 (=.041) in the EBC of COPD smokers were higher than those of COPD never-smokers. The concentrations of TIMP-1 (=.072) and TIMP-4 (=.084) in the EBC of COPD smokers were higher than those of COPD never-smokers; however, the difference was not statistically significant. MMP-9 (=-0.78, <.0001) and TIMP-1 (=-0.71, <.0001) levels in EBC were significantly negatively correlated with pulmonary function FEV%pred. The protein levels of MMP-12 (=-0.37, =.034) and TIMP-4 (=-0.34, =.041) were also negatively correlated with FEV1%pred. The expression of MMP-9, MMP-12, NE, TIMP-1, and TIMP-4 in PBMCs and serum of COPD smokers were significantly higher than those of control never-smokers (<.05). Exhaled MMP-9, MMP-12, TIMP-1, and TIMP-4 levels increased in stable COPD patients and were negatively correlated with FEV1%pred, which suggests the usefulness of their measurement in EBC for the monitoring of airway inflammation. However, to better assess their diagnostic or prognostic value, larger studies are necessary.