Evaluation of collagenase activity, matrix metalloproteinase-8, and matrixmetalloproteinase-13 in horses with chronic obstructive pulmonary disease

Objectives-To determine collagenase activity and evaluate matrix metallopro teinase (MMP)-8 and MMP-13 in horses with chronic obstructive pulmonary dis ease (COPD). Animals-12 horses with COPD and 12 healthy control horses. Procedure-Collagenase activity was determined by use of an assay for degrad ation of type-I collagen. Western immunoblot analysis was used to identify interstitial collagenases MMP-8 and MMP-13 in tracheal epithelial lining fl uid (TELF). Immunocytochemistry and in situ hybridization were used to dete rmine cellular expression of these 2 collagenases in cells in bronchoalveol ar lavage fluid (BALF). Results-Collagenase activity was approximately 7 times higher in samples ob tained from horses with COPD, compared with control horses. During stabling , horses with COPD had significantly higher collagenase activity than after being maintained on summer pasture, when activity was similar to that of c ontrol horses. Immunoreactivity of MMP-8 and MMP-13 was significantly incre ased in TELF of horses with COPD, compared with healthy horses. In TELF, a positive correlation was detected between immunoreactivity of MMP-8 and MMP -13 and the amount of degradation of type-I collagen. Macrophages and epith elial cells were the major cellular sources of MMP-8 and MMP-13. Conclusions and Clinical Relevance-Increased collagenase activity in TELF i ndicates active ongoing disease and, thus, may reflect lung tissue changes in horses with COPD. Measurements of collagenase activity and MMP immunorea ctivity may provide additional diagnostic tools to identify the active phas e of chronic lung disease.