Effect of hay dust extract and cyathostomin antigen stimulation on cytokine expression by PBMC in horses with recurrent airway obstruction.

The research article presents a study exploring the immunological response, specifically involving IL-4R expression, to hay dust and cyathostomin antigens in horses suffering from equine recurrent airway obstruction (RAO) as compared to healthy horses. The results showcase varying responses based on genetic background, indicating potential immuno-genetic aspects of RAO.

Objective and Hypothesis

• The objective of the research was to explore the immunological process underlying equine recurrent airway obstruction (RAO), an inflammatory airway disease in horses that is induced by exposure to inhaled organic dust particles.
• The researchers hypothesized that T helper (h)1/Th2/regulatory (Treg) cytokine profiles would differ between RAO-afflicted and healthy horses on exposure to RAO-associated antigens and parasite antigens, and that this difference would be dependent on the horse’s genetic background.

Methodology

• The researchers obtained peripheral blood mononuclear cells (PBMC) from 17 RAO-affected and 14 healthy horses.
• These PBMC were stimulated for 24 hours with antigens relevant to RAO — hay dust extract (HDE), Aspergillus fumigatus extract (AFE), lipopolysaccharids (LPS), cyathostomin extract (CE), and recombinant cyathostomin antigen (RCA) — as well as concanavalin A (ConA).
• Using qRT-PCR, the researchers examined the total mRNA levels of various immunological markers: IL-4, IL-4R, IL-13, interferon (INF)-γ, and IL-10.

Findings

• RAO-affected and control horses from Warmblood family F1 showed significant differences in IL-4R mRNA levels post stimulation with HDE or RCA. These differences, however, did not emerge in the horses from Warmblood family F2.
• On stimulation with HDE, IL-10 mRNA expression varied significantly between RAO-affected and control horses in F1, but not F2.
• When stimulated with CE, the IL-10 mRNA expression levels were significantly different between RAO-affected horses of F2 and healthy horses of F1.
• No significant differences were identified when the researchers stimulated the PBMC with any of the other antigens they tested.

Conclusions

• The study demonstrated variations in immunological response, particularly of IL-4R expression, to hay dust and cyathostomin antigens between RAO-affected and healthy horses, suggesting a genetic influencing aspect to immunological responses in RAO.
• The utilization of PBMC in tests revealed systemic changes linked to RAO and provided insights into the specific pathways related to this disease on an immunological level.