Bronchial vessel density is correlated with airway smooth muscle cell proliferation in horses with mild and moderate asthma.

The research investigates the link between bronchial vessel density and the proliferation of smooth muscle cells in the airway, in horses experiencing mild and moderate asthma. The study reveals that, unlike severe equine asthma, these milder cases do not present significant changes in bronchial vascularization, but an association might exist between the blood vessel density and smooth muscle changes.

Study Purpose and Methodology

• The study aimed to understand if an increase in bronchial vascularization, a characteristic of severe equine asthma, also contributes to bronchial restructuring in milder forms of the disease.
• Using a retrospective case-control study design, the researchers analyzed endobronchial biopsies from 9 horses with mild and moderate equine asthma (MEA) and 7 healthy controls. The samples were part of the Equine Respiratory Tissue Biobank and were collected over a nearly five-year period.
• The team identified the vascular basement membrane for each sample using immunohistochemistry and then measured the number of bronchial vessels, the vascular area, and the average vessel size using histomorphometry.
• The connections between angiogenic characteristics, remodeling features of airway smooth muscle (ASM), and airway neutrophilia were then observed and studied.

Results

• No significant differences were found in the angiogenic parameters between the groups of horses.
• A correlation was noted between the number of vessels and ASM cell proliferation in horses with MEA, although this was not found in the control group.
• A negative correlation was discovered between airway neutrophilia and average vessel size in the MEA group, again, this was not present in the control group.

Conclusions

• The data collected shows significant changes in bronchial vascularization were not present in horses with MEA.
• The findings contradict previous research on severe equine asthma, showing that angiogenesis is not a significant characteristic of MEA. However, it may still play a role in ASM remodeling.