A study on the possible role of chymotrypsin in the aetiology of equine chronic obstructive pulmonary disease (COPD).

This research investigates the potential relationship between chymotrypsin (a protein-digesting enzyme) and chronic obstructive pulmonary disease (COPD) in horses. Despite initial evidence suggesting that chymotrypsin might cause respiratory hypersensitivity, it does not appear to significantly contribute to the symptoms of equine COPD.

Research Methodology and Key Findings

• The researchers evaluated chymotrypsin activity in seven batches of Micropolyspora faeni and five batches of Aspergillus fumigatus extracts. These are common environmental fungi that horses could inhale and potentially provoke a COPD response.
• They found a varied range of chymotrypsin activity in these extracts. However, when they challenged horses suffering from COPD with two batches of each antigen (different in chymotrypsin activities), they found no significant correlation between the chymotrypsin activity and the degree of response to the challenge.
• This implies that the level of chymotrypsin in these antigens does not directly affect the severity or onset of COPD symptoms in horses.
• In an additional experiment, COPD-affected horses inhaled two doses of purified chymotrypsin over a span of four days. Even this direct exposure to chymotrypsin did not induce signs of respiratory disease in the horses.
• However, when the procedure was repeated after three weeks, one horse showed exacerbated COPD symptoms, suggesting that repeated exposure to chymotrypsin might heighten sensitivity and symptom severity, but generally chymotrypsin doesn’t seem to directly initiate COPD.

Conclusions and Implications

• The study concludes that, despite possible evidence of chymotrypsin inducing respiratory hypersensitivity in horses upon repeated exposure, the chymotrypsin-like enzymes present in M. faeni and A. fumigatus do not play a significant role in accelerating the clinical symptoms of equine COPD.
• This challenges the hypothesis of chymotrypsin’s major role in causing equine COPD and implies that other factors may be more important in the development and progression of this disease.
• Further investigations are required to better understand the role of various enzymes and antigens in equine COPD to aid in its treatment and prevention.