Immunohistochemical Expression of Neurokinin-A and Interleukin-8 in the Bronchial Epithelium of Horses with Severe Equine Asthma Syndrome during Asymptomatic, Exacerbation, and Remission Phase.
Authors: Morini Maria, Peli Angelo, Rinnovati Riccardo, Magazzù Giuseppe, Romagnoli Noemi, Spadari Alessandro, Pietra Marco
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Severe equine asthma remains a significant clinical challenge, yet the relationship between specific inflammatory markers and disease severity across different disease phases—asymptomatic, exacerbation, and remission—remains poorly characterised. Morini and colleagues conducted a bronchoscopic biopsy study on six asthmatic horses, collecting samples during controlled environmental challenge and subsequent pharmacological treatment, then analysed histological changes and immunohistochemical expression of neurokinin-A (NKA) and interleukin-8 (IL-8) across all disease phases. Histological scoring revealed significant differences between healthy controls and affected horses throughout all experimental phases, with notably worse scores at remission compared to the asymptomatic phase; however, NKA and IL-8 expression showed no significant variation between phases, though NKA did increase significantly at late exacerbation and remission compared to controls. The counterintuitive finding that NKA immunopositivity increased rather than decreased following successful clinical treatment warrants further investigation and challenges current assumptions about neurogenic inflammation in equine asthma resolution. For practitioners, these results suggest that clinical improvement and histological normalisation may not be temporally aligned, and that endoscopic biopsies provide reliable sampling; however, additional inflammatory markers and larger sample sizes are needed before these biomarkers can be reliably incorporated into diagnostic protocols or used to guide therapeutic decisions in individual cases.
Read the full abstract on PubMed
Practical Takeaways
- •Endoscopic bronchial biopsies provide reliable diagnostic samples for evaluating severe equine asthma, but histological improvement does not correlate with clinical recovery
- •NKA immunohistochemistry may be a useful marker for severe EA, as it increases during exacerbation and persists through treatment, suggesting it warrants investigation as a diagnostic tool
- •Clinical signs of improvement should not be assumed to represent resolution of airway inflammation; additional inflammatory markers beyond IL-8 may be needed to assess true disease resolution
Key Findings
- •Histological biopsy scoring revealed significant differences between control and EA-affected horses across all experimental phases (asymptomatic, early exacerbation, late exacerbation, and remission)
- •Neurokinin-A (NKA) immunopositivity intensity increased significantly in EA horses at late exacerbation and remission phases compared to controls, contrary to expected decrease after treatment
- •IL-8 expression showed no significant differences between experimental phases in EA-affected horses
- •Clinical improvement following pharmacological treatment was paradoxically associated with worsening histological findings