Evaluation of matrix metalloproteinase-9 and tissue inhibitor metalloproteinase-1 levels in bronchoalveolar lavage of apparently healthy smokers

Cigarette smoking has a destructive effect on the extracellular matrix (ECM), so it is considered the most important risk factor for the development of emphysema as it leads to recruitment of activated macrophages and neutrophils in the lung leading to release of proteolytic enzymes as matrix metalloproteinases (MMPs) or an imbalance between MMPs and the tissue inhibitors of MMP (TIMPs), playing a role in the pathogenesis of emphysema.Aim of the workThe aim of this work was to evaluate the level of MMP-9 and tissue TIMP-1 in bronchoalveolar lavage of apparently healthy smokers.Methods and resultsMMP-9 and TIMP-1 levels were measured by ELISA in BAL in 10 healthy controls, 15 apparently healthy smokers and 15 emphysematous patients. Smokers and COPD patients had a higher concentration of MMP-9 and TIMP-1 compared with controls. The ratio of MMP-9 to TIMP-1 was significantly higher in the emphysema group than the two other groups. Also the smoker group was higher than the control group but without statistic significant difference.ConclusionsHealthy smokers had a higher concentration of total MMP-9 and that concentration was correlated with their exposure to tobacco smoke. Maintenance of normal MMP-9/TIMP-1 ratio in healthy smokers may explain the absence of progressive airway obstruction. Measurement of active MMP-9 concentration could be useful for assessment of airway remodeling.