Asthma remodeling: The pathogenic role of matrix metalloproteinase-9

BackgroundAsthma is an airway inflammatory disease with functional and structural changes, leading to bronchial hyperresponsiveness and airflow obstruction. Pathological repair of the airways leads to these structural changes referred as airway remodeling. Matrix metalloproteinases (MMPs) are extracellular degrading enzymes that play a critical role in the remodeling process.Aim of the studyIs to study matrix metalloproteinase-9 in asthmatic patients, detecting its pathogenic role in airway remodeling.Subjects and methodsSamples of broncho-alveolar lavage (BAL) fluid and bronchoscopic biopsies from 30 asthmatic patients (10 mild, 10 moderate and 10 severe) and 10 healthy volunteers were assessed for the levels of matrix metalloproteinase-9 (MMP-9) total and differential cell count (in BAL fluid), histological airway remodeling changes and immunohistochemical expression of MMP-9 (in mucosal biopsies).ResultsBAL and tissue MMP-9 (going hand in hand with airway remodeling changes) were higher in asthmatic patients and it was significantly increased with increased severity. BAL total cell count is higher in asthmatic patients. BAL eosinophils, neutrophils, lymphocytes as well as MMP-9 positive cell count were higher in asthmatic patients and increased with severity. MMP-9 tissue expression was also strongly inversely correlated with the spirometric parameters in asthmatic patients.ConclusionsMMP-9 plays a role in airway inflammation and airway remodeling in asthma. MMP-9 is an important player in airway remodeling in bronchial asthma and may be the link between inflammation and remodeling processes.