**5. Conclusions**

The results of the present study demonstrate homogeneity in the bronchial endoscopic samples regardless of the sampling site, demonstrating a lack of influence of bronchial sampling position on histological and immunohistochemical evaluation. The application of the histological score of Bullone et al., 2016 to endoscopic biopsies [17], however, fails to first differentiate between the exacerbation and the remission phase, which, contrarily to what we found, should have a return to histological conditions significantly similar to those of normality.

By immunohistochemical analysis, the comparison between clinically healthy horses and EA-affected ones suggested new insights on the cytokine expression in equine health and disease status. On the one hand, investigations on endoscopic biopsy samples allowed detecting relevant differences in immunoreactivity between control horses and horses with severe equine asthma syndrome, demonstrating a dysregulation of their expression in the latter. On the other hand, the clinical improvement at different times of the disease seems to have no immunohistochemical bases for IL-8 and NKA expression. The explanations behind these results are still being studied and require more data and subjects examined.

**Supplementary Materials:** The following are available online at https://www.mdpi.com/article/10 .3390/ani11051376/s1, Table S1: Excel file reporting all the histological data collected for this study.

**Author Contributions:** Conception and design of the work: M.M., M.P., A.P., N.R., and A.S.; acquisition, analysis, and interpretation of data: M.M., M.P., R.R., and G.M.; drafted the work: M.M. and M.P.; substantively revised the manuscript: M.M., M.P., A.P., G.M., N.R., and R.R. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research has no external funding.

**Institutional Review Board Statement:** The study was approved by the Ethics and Scientific Committee of the Alma Mater Studiorum University of Bologna in the plenary session on 3 March 2009 (protocol n◦ 04/55/09) and submitted to the Italian Ministry of Health. All experimental procedures were carried out in accordance with European legislation regarding the protection of animals used for experimental and other scientific purposes (Council Directive 86/609/EEC).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Data Availability Statement:** All data generated or analyzed during this study are included in this published article. The raw datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

**Acknowledgments:** Authors thank Laura Joanna Luczak, English translator and interpreter, for the English revision of the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
