Increased matrix metalloproteinase-9 to tissue inhibitor of metalloproteinase-1 ratio in smokers with airway hyperresponsiveness and accelerated lung function decline
Authors Lo CY, Huang HY, He JR, Huang TT, Heh CC, Sheng TF, Chung KF, Kuo HP, Wang CH
Received 1 January 2018
Accepted for publication 23 February 2018
Published 11 April 2018 Volume 2018:13 Pages 1135—1144
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Charles Downs
Peer reviewer comments 2
Editor who approved publication: Professor Chunxue Bai
Chun-Yu Lo,1 Hung-Yu Huang,1 Jung-Ru He,1 Tzu-Ting Huang,1 Chih-Chen Heh,1 Te-Fang Sheng,1 Kian Fan Chung,2 Han-Pin Kuo,1 Chun-Hua Wang1
1Department of Thoracic Medicine, Chang Gung Medical Foundation, College of Medicine, Chang Gung University, Taipei, Taiwan; 2Airways Disease Section, National Heart and Lung Institute, Imperial College London, London, UK
Background: Airway hyperresponsiveness (AHR) is associated with airway inflammation and a rapid decline in lung function and is a predictor of future risk of COPD among smokers. Alveolar macrophages (AMs) from patients with COPD release a greater amount of matrix metalloproteinase (MMP)-9. We hypothesized that the imbalance between MMP-9 and tissue inhibitor of metalloproteinase-1 (TIMP-1) is related to AHR in smokers.
Patients and methods: Healthy smokers with AHR (AHR + S) or smokers without AHR (AHR - S; divided according to a methacholine challenge test) and nonsmokers without AHR (AHR - NS) were enrolled. Spirometry was performed during enrollment and repeated after 5 years. Initially, AMs recovered from bronchoalveolar lavage (BAL) fluid were cultured in the presence of p38 mitogen-activated protein kinase (MAPK) inhibitor (SB203580), MAPK kinase (MEK) 1/2 (the MEK of extracellular signal-regulated kinase [ERK] inhibitor, PD98059), or medium alone for 24 h. The release of MMP-9 and TIMP-1 in culture supernatants was measured by enzyme-linked immunosorbent assay.
Results: A greater reduction in forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC), FEV1 (as a percentage of the predicted value [%pred]), and maximal mid-expiratory flow (MMEF) was observed among AHR + S in the 5-year period. There was a higher proportion of neutrophils and a lower proportion of AMs in BAL fluid recovered from AHR + S. Compared to AMs from AHR - NS and AHR - S, AMs from nonsmokers with AHR (AHR + NS) released more MMP-9 and less TIMP-1, with an increase in MMP-9/TIMP-1 ratios. The MMP-9/TIMP-1 ratio in smokers was positively correlated with the annual decline in FEV1%pred, FVC%pred, and MMEF%pred. Both SB203580 and PD98059 significantly reduced MMP-9, but not TIMP-1, from AMs of smokers.
Conclusion: AMs of AHR + NS produce excessive MMP-9 over TIMP-1, which may be a predictor of the development of airway obstruction. Inhibition of p38 MAPK and ERK suppresses the generation of MMP-9 by AMs from smokers.
Keywords: smoking, airway hyperresponsiveness, alveolar macrophage, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, p38 mitogen-activated protein kinase, extracellular signal-regulated kinase
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