Background. Inflammation, oxidative stress, and an imbalance between proteases and protease inhibitors are recognized pathophysiological features of chronic obstructive pulmonary disease (COPD).
Objective. Determination of the serum levels of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in patients with COPD and evaluation of their association with the severity of COPD symptoms.
Methods. In a cohort study, serum MMP-9 and TIMP-1 levels, the ratio of MMP-9/TIMP-1 in the peripheral blood of COPD patients and in the control group, as well as their relationship with pulmonary function were determined. Spirometry, symptom severity scale (mMRC and CAT), and history of exacerbations were assessed.
Results. COPD patients (n=96) had significantly higher serum MMP-9 and TIMP-1 levels, higher MMP-9/TIMP-1 ratio than controls (n=40) (P ≤0.001). MMP-9 and MMP-9/TIMP-1 ratio were negatively correlated with FVC, FEV1, FEV1/FVC (P<0.05). COPD GOLD-3-4 patients had higher MMP-9 levels and a greater MMP-9/TIMP-1 ratio compared to COPD GOLD-1-2 patients (P≤0.001).
Conclusion. In patients with COPD, serum MMP-9 and TIMP-1 levels and the MMP-9/TIMP-1 ratio were elevated. In patients with COPD, there was an imbalance between MMP-9 and TIMP-1 in favor of fibrosis, which generally indicates the importance of the MMP-9/TIMP-1 ratio as a potential biomarker for the diagnosis and severity of COPD.

Keywords: tissue inhibitor of metalloproteinase-1, matrix metalloproteinase-9, chronic obstructive pulmonary disease