Evaluation of local endobronchial antigen challenges in the investigation of equine chronic obstructive pulmonary disease.

The research was conducted to evaluate the effectiveness of using local endobronchial antigen challenges in investigating equine chronic obstructive pulmonary disease (COPD). However, the study concluded the technique is of no value for such investigations due to insignificant differences in bronchoalveolar lavage fluid (BALF) neutrophilia among control and asymptomatic COPD-affected horses.

Methodology of the Study

• The study utilized a technique called the local transendoscopic endobronchial antigen challenge, effective in human pulmonary hypersensitivity studies.
• The experiment included both control and asymptomatic COPD-affected horses.
• The horses underwent different challenges including phosphate-buffered saline (PBS), Micropolyspora faeni extract at two concentrations (60 and 600 micrograms/ml), and mouldy hay extract.
• The horses neutrophilic airway inflammatory responses were monitored through cytological examinations of BALF harvested from the challenged lung sections.

Results of the Study

• Endobronchial challenges elicited airway inflammatory responses in both control and asymptomatic COPD-affected horses, with a significant BALF neutrophilia observed only in horses with asymptomatic COPD when challenged with 600 micrograms M. faeni extract/ml, compared with PBS challenges.
• Although the BALF neutrophil ratios of COPD-affected horses after the M. faeni challenge did not significantly differ from those of control horses, undermining the clinical diagnostic value of this finding.
• The BALF neutrophilia induced by 60 micrograms M. faeni extract/ml and mouldy hay extract challenges was not significantly different from that induced by PBS.
• Bronchial changes were visible in some control and COPD-affected horses within 5 minutes and at 5 hours after the challenges, yet, these did not substantively contribute to the diagnostics of equine COPD.

Conclusion of the Study

• The researchers concluded that, despite the method’s applicability to human pulmonary hypersensitivity studies, the endobronchial antigen challenge method is not valuable in investigating equine COPD due to a lack of significant differential responses between control and COPD-affected horses.