INHIBITION OF THE PROTEASE ACTIVITY IN TRACHEOBRONCHIAL ASPIRATES OF HORSES WITH CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

Objectives--To clarify the role of proteolytic enzymes in the pathogen esis of chronic obstructive pulmonary disease (COPD) in horses, and to investigate new possibilities for treatment of this disease by interf ering in the proteolytic process. Design--Effect of antiproteolytic ac tivity of selected protease inhibitors on tracheal aspirates was studi ed in vitro, and the inhibition profiles were compared with those of p urified proteases. Sample Population-Respiratory tract secretions with antiproteolytic activity from 9 horses with COPD. Procedure-Caseinoly tic agar-diffusion assay. Results-The protease-inhibition profile of t racheal aspirates differed from horse to horse. The profiles did not r esemble that of any of the pure proteases. Acetylcysteine, pentamidine , and diminazene were most effective in inhibiting proteolytic activit y in tracheal aspirates in vitro. Conclusions-A mixed type of proteoly tic activity is present in the respiratory tract secretions of horses with COPD. Clinical Relevance-Acetylcysteine, pentamidine, and diminaz ene seem to have potential to be used in vivo to protect the lungs of horses with COPD from proteolytic damage.