Matrix metalloproteinase 9 is involved in airway inflammation in cough variant asthma

Previous studies have revealed the role of matrix metalloproteinase 9 (MMP9) in asthma and chronic obstructive pulmonary disease (COPD). However, its role in airway inflammation in cough variant asthma (CVA) remains unknown. In the present study, variations in the levels of MMP9 and interleukin (IL)-5 in the induced sputum of patients with CVA prior to and following therapy with inhaled corticosteroid and long-acting β2-agonist (ICS/LABA), were detected. The levels of IL-5 and percentage of eosinophils (EOS) in the induced sputum from patients with CVA were significantly higher than those in the control group of healthy individuals. The levels of MMP9 in the induced sputum from patients with CVA were also significantly higher than those in the control group. Following treatment with ICS/LABA for 6–9 months, the levels of MMP9 and IL-5, as well as the percentage of EOS, in the induced sputum from patients with CVA had significantly decreased. Thus, MMP9 may be an important biomarker in the airway inflammation of CVA.