Matrix metalloproteinase levels of bronchial mucosa and the correlation with clinical parameters in clinically stable bronchiectasis

Abstract

Background: Relations between matrix metalloproteinases (MMPs) and inflammatory markers and lung function remain unclear. Objective: To determine the correlation between bronchial MMPs and bacterial infection, inflammatory markers and lung function in bronchiectasis, and to compare the levels of MMPs in patients harbouring Pseudomonas aeruginosa (PA), miscellaneous PPMs and commensals. Methods: Bronchial mucosa was sampled from the most and least significant bronchiectatic lobes in patients with steady-state bronchiectasis and right main bronchus from those with suspected pulmonary lesions, for immunohistochemistry assay, to determine the density of MMP-8, MMP-9 and tissue inhibitor metalloproteinase-1 (TIMP-1) positive cells in laminar propria (cells*mm-2). Peripheral blood and sputum were collected. Spirometry was performed. Results: We recruited 29 bronchiectasis patients and 9 controls. The MMP-8 and MMP-9 positive cell densities were markedly higher in most significant bronchiectatic lobes (all P<0.05). The most significant bronchiectatic lobes harbouring PA were associated with higher densities of MMP-8, MMP-9 and TIMP-1 positive cells (all P<0.05). The densities of MMP-8 and MMP-9 positive cells and MMP-9/TIMP-1 ratio were not correlated with bacterial loads, airway and serum inflammatory markers and lung function. Conclusion: The most significant bronchiectatic lobes are characterized by remarkably higher levels of MMPs, which are not correlated with bacterial loads, inflammatory markers or lung function. Higher densities of MMP-8, MMP-9 and TIMP-1 positive cells are associated with airways harbouring PA.