BACKGROUND: Animal and human studies have implicated an imbalance of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in the pathogenesis of chronic obstructive pulmonary disease (COPD). MMP-9 protein is increased in COPD and we hypothesized that total MMP activity would be raised although this has not previously been measured. METHODS: Using fluorescence and biotin labelled MMP assays, RT-PCR, western blotting and enzyme-linked immunosorbent assay we examined total MMP activity, specific gelatinase, elastase, collagenase activity, TIMP-1 and TIMP-2 in induced sputum from smokers with COPD and smokers without COPD. RESULTS: Induced sputum was obtained from 15 smokers with COPD and 14 smokers without COPD. MMP-9 levels were higher in those with COPD compared with controls (p<0.05). Total MMP activity, specific gelatinase, collagenase and elastase activities were not higher in COPD patients. In addition, reduced MMP activity was correlated with increasing airflow obstruction in COPD (p=0.016). CONCLUSION: MMP-9 protein but not MMP activity was higher in sputum of COPD patients compared with controls. These results suggest that MMP-9 levels may not reflect the overall MMP activity in the airways of patients with COPD suggesting a complex relationship between MMP-9 protein and activity. Further studies of MMPs in COPD should comprise activity measures in addition to protein levels.
BACKGROUND: Animal and human studies have implicated an imbalance of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in the pathogenesis of chronic obstructive pulmonary disease (COPD). MMP-9 protein is increased in COPD and we hypothesized that total MMP activity would be raised although this has not previously been measured. METHODS: Using fluorescence and biotin labelled MMP assays, RT-PCR, western blotting and enzyme-linked immunosorbent assay we examined total MMP activity, specific gelatinase, elastase, collagenase activity, TIMP-1 and TIMP-2 in induced sputum from smokers with COPD and smokers without COPD. RESULTS: Induced sputum was obtained from 15 smokers with COPD and 14 smokers without COPD. MMP-9 levels were higher in those with COPD compared with controls (p<0.05). Total MMP activity, specific gelatinase, collagenase and elastase activities were not higher in COPDpatients. In addition, reduced MMP activity was correlated with increasing airflow obstruction in COPD (p=0.016). CONCLUSION:MMP-9 protein but not MMP activity was higher in sputum of COPDpatients compared with controls. These results suggest that MMP-9 levels may not reflect the overall MMP activity in the airways of patients with COPD suggesting a complex relationship between MMP-9 protein and activity. Further studies of MMPs in COPD should comprise activity measures in addition to protein levels.
Authors: Michelle E John; John R Cockcroft; Tricia M McKeever; William R Coward; Dennis J Shale; Simon R Johnson; Jim G Thornton; Timothy W Harrison; Alan J Knox; Charlotte E Bolton Journal: Int J Chron Obstruct Pulmon Dis Date: 2015-01-29