Horses With Pasture Asthma Have Airway Remodeling That Is Characteristic of Human Asthma.

The research article explores the similarities in the airway remodeling observed in horses suffering from equine pasture asthma and human asthma. Having studied the lung lobes of affected and healthy horses, the study concludes that equine pasture asthma replicates the airway remodeling found in human asthma in ways not achieved in induced animal asthma models, thus highlighting its importance in human asthma research.

Study Methodology

• The researchers collected lung lobes from 15 horses suffering from equine pasture asthma (previously known as summer pasture recurrent airway obstruction) and 9 control horses of various breeds.
• Non-cartilaginous airways in these lung lobes were assessed and scored based on standardised grading (0-3) using hematoxylin and eosin (HE) and Movat’s pentachrome-stained sections. About 15 airways from each lobe were randomly chosen for this analysis.
• A logistic regression model was then used to identify the effects of disease, age, and lobe attributes on the probability of observing various histologic outcomes.

Results

• The study found significant increases in airway smooth muscle, goblet cell hyperplasia/metaplasia, peribronchiolar elastic system fibers, peribronchiolar fibrosis, and airway occlusion due to mucus/inflammation in diseased airways compared to healthy ones.
• Something they term “terminal bronchiolar remodeling”, or complex tissue disorganisation, was found to be significantly overrepresented in diseased airways.
• The distribution of this terminal bronchiolar remodeling pattern was observed to coincide with the succedaneous locations of air trapping commonly noted in human asthma cases.
• The experiment also found age to be a significant independent risk factor for increased peribronchiolar fibrosis, elastic system fibers, and terminal bronchiolar remodeling. Horses aged over 15 years were more susceptible.
• Interestingly, the study observed significant differences in remodeling across different lung lobes, aligning with the heterogeneous remodeling observed in human asthma.

Conclusion

• Ultimately, the study concluded that equine pasture asthma demonstrates a recapitulation of the airway remodeling patterns observed in human asthma that are not seen in animal models of induced asthma.
• This correlation reinforces the translational relevance of equine pasture asthma for research into human asthma, providing further insight into the disease and potentially informing future therapeutic strategies.