Concentrations of elastinolytic metalloproteinases in respiratory tract secretions of healthy horses and horses with chronic obstructive pulmonary disease

Objectives-To determine whether samples of tracheal epithelial lining fluid (TELF) obtained from horses have elastinolytic activity characteristic of metalloproteinases, to compare elastinolytic activity in TELF obtained from healthy horses and horses with chronic obstructive pulmonary disease (COPD ), and to determine whether chemically modified tetracycline-3 (CMT-3) inhi bits elastinolytic activity in TELF. Animals-10 horses with COPD and 10 healthy control horses. Procedure-Zymography and fluorometry were used to measure elastinolytic act ivity, and EDTA was used to inhibit elastinolytic activity and verify that the activity was attributable to metalloproteinases. Possible inhibition of elastinolytic activity with CMT-3 was studied in vitro. Results-Elastinolytic activity was found in TELF obtained from all horses, and this activity was significantly higher in TELF obtained from horses wit h COPD than in TELF obtained from healthy horses. For all samples, EDTA and CMT-3 inhibited elastinolytic activity. Conclusions and Clinical Relevance-Elastinolytic activity is detectable in TELF obtained from horses and seems to be attributable to metalloproteinase s. Elastinolytic activity in TELF is significantly inhibited by CMT-3. Elas tinolytic activity in TELF can be detected by means of zymography or fluoro metry. Increased elastinolytic activity may reflect destruction of pulmonar y tissue in horses with COPD. Chemically modified tetracyclines such as CMT -3 may provide an additional treatment possibility for horses with COPD.