Expression microarray as a tool to identify differentially expressed genes in horses suffering from inflammatory airway disease.

This research investigates the use of equine gene expression microarrays to identify differential gene expression in the blood of horses with Inflammatory Airway Disease (IAD) to potentially provide less invasive diagnostic methods.

Objective

The goal of the study was to find particular genes in horses’ peripheral blood that showed differences in expression levels related to IAD. The research was aimed to advance the diagnostic process for IAD, which currently relies on an invasive process involving bronchoalveolar lavage (BAL) cytology, necessitating sedation.

Methods

• The team utilized equine gene expression microarrays to observe mRNA expression on a global scale in circulating leukocytes in healthy horses, those affected by IAD, and low-performing Standardbred and endurance horses.
• Differentially expressed genes were identified by comparing the gene expression levels between these groups.

Results

• Nine significantly differentially regulated genes were identified in Standardbred horses and 61 in endurance horses.
• These identified genes were linked to inflammation (ALOX15B, PLA2G12B, and PENK), oxidant/antioxidant balance (DUOXA2 and GSTO1-1), and stress (V1aR, GRLF1, Homer-2, and MAOB). Most of these genes were up-regulated, except for Homer-2 and MAOB, which were down-regulated.
• Further validation was done by RT-qPCR on the expression of DUOXA2, ALOX15B, PLA2G12B, MAOB, and GRLF1 genes.
• An increase in glutathione peroxidase (GPx) activity was also observed in the whole blood of both IAD-affected Standardbred and endurance horses, which suggests an imbalance in the oxidant/antioxidant levels.
• A good correlation was found between BAL neutrophil percentage and whole blood GPx activity across all horses.

Conclusions

• The study’s findings reveal that the gene expression in circulating blood cells can mirror inflammatory responses in tissues.
• The genes identified as involved in IAD may have potential future use in diagnostics, a point which needs further investigation.
• While not specific to IAD, the study noted a correlation between whole blood GPx activity and BAL neutrophil percentage, thus suggesting further investigation with a larger sample size.