Abstract

Tissue inhibitor of metalloproteinases (TIMP) and collagenase inhibitory activity were measured in the sputum from nine subjects with chronic bronchitis before and five days after treatment with corticosteroid (oral prednisolone, 40 mg daily). The mean sputum TIMP concentrations for eight of the nine subjects increased from 3.1 (SD 0.87) micrograms/ml to 5.8 (1.9) micrograms/ml (2p less than 0.005). Similarly, the mean collagenase inhibitory activity in the sputum of eight of the nine subjects increased from 1.53 (1.1) U/ml to 2.69 (0.92) U/ml (2p less than 0.05). The TIMP concentrations in sputum exceeded the collagenase inhibitory activity, suggesting that a proportion of the TIMP was inactive. TIMP inactivity was not due to prior complexing with enzyme since the molecular weight of sputum TIMP (27,500) was similar to that described for the purified protein (28,000-28,500). Preliminary studies showed the presence of TIMP in bronchoalveolar lavage samples (range of six specimens 0.45 ng/ml-2.1 micrograms/ml, median 53 ng/ml). Collagenase inhibitory activity was detected in only two of these six lavage samples, suggesting that the TIMP was totally inactive in the other four samples. The significance of the metalloproteinase-inhibitor balance in the pathogenesis of chronic lung disease requires further study.