Gelatinolytic activity in tracheal epithelial lining fluid and in blood from horses with chronic obstructive pulmonary disease.

This research investigates the presence and activity level of metalloprotease (a type of enzyme) in the tracheal lining fluid and blood cells in horses. The study found that horses suffering from chronic obstructive pulmonary disease (COPD) had higher metalloprotease activity in the tracheal lining fluid compared to healthy horses, but the difference in blood cells was insignificant.

Methods

• The study used 7 horses with chronic obstructive pulmonary disease (COPD) and 4 healthy horses for control.
• Blood neutrophils and lymphocytes (types of white blood cells) were obtained using a method called Percoll separation to examine the presence of metalloproteases.
• Zymography, a technique for studying enzymatic activity, was used to detect gelatinolytic activity — the process by which the enzymes break down gelatin. This essentially detects the activity of metalloproteases.
• To confirm that the detected gelatinolytic activity was indeed due to metalloproteases, EDTA (a molecule that binds and inhibits metal ions) was used to inhibit, and 4-aminophenyl mercuric acetate (APMA) was used to activate the activity. EDTA and APMA thus served to verify the presence of metalloproteases.

Results

• The research found a significantly higher gelatinolytic activity (indicating more metalloproteases) in the tracheal epithelial lining fluid (TELF) from horses with COPD compared to healthy horses.
• EDTA indeed inhibited, and APMA enhanced the gelatinolytic activity for all samples, confirming that the activity was due to metalloproteases.
• However, there was no significant difference in the gelatinolytic activity in neutrophils, lymphocytes, and serum between healthy and COPD horses.

Conclusions

• The results of the research suggested that gelatinolytic activity in TELF from horses is metalloprotease activity.
• It is elevated in horses with COPD but not in serum, neutrophils, or lymphocytes, indicating that COPD horses have a higher level of these enzymes in their TELF.
• The research also suggested that neutrophils and lymphocytes might be potential sources of this increased gelatinolytic activity in TELF.
• Lastly, the data indicated that measuring gelatinolytic activity in serum, blood neutrophil, or blood lymphocyte was not a valuable method to distinguish horses with COPD from healthy horses.