Molecular and Cellular Evaluation of Horses With Summer Pasture Associated Asthma Syndrome.

The research focused on understanding the nature of inflammation in the lower airways of horses suffering from equine asthma – a condition associated with seasonal pastures. They analyzed cell counts and gene expressions linked to the immune response in both healthy and asthma-inflicted horses.

Objective and Methodology

• The primary goal of this study was to further understand the molecular and cellular characteristics of inflammation caused by equine asthma in horses maintained on pasture during summer in tropical climates.
• To do this, the researchers measured the gene expression of certain immune markers, specifically Th1 cytokines (IFN- λ, IL-8), Th2 cytokines (IL-4 and IL-5), and pro-inflammatory cytokines (IL-1, TNF-α) in the bronchoalveolar lavage (BAL) fluid of both healthy and asthmatic horses.

Study Participants and Experimental Procedure

• The study involved 39 clinically healthy horses that were kept on native pasture lands and were supplemented with a concentrate for nutrient requirements.
• These horses were subjected to a bronchoalveolar lavage (BAL), a technique that involves washing out the bronchi and their terminal parts, or alveoli, to collect cells and other components.
• The collected BAL fluid was analyzed for its differential cellular count and was grouped into control (healthy) and asthma groups.
• Further, gene expression levels of certain cytokines were analyzed using reverse time PCR (RT-PCR). These included IL-1α (alpha), IL-4, IL-5, IL-8, TNF-α alpha, and IFN-λ. These cytokines are involved in various immune responses, including inflammation.

Key Findings

• The researchers found higher gene expression levels of IL-1, IL-4, IL-5, IL-8, IFN-λ in the BAL fluid of horses with asthma as compared to healthy horses, indicating increased inflammation.
• The results suggested that there was a significant increase in the Th2 response, characterized by an increased IL-5 level. This finding indicated an allergic inflammatory reaction in horses with asthma.
• The only inflammatory marker that was found to be lower in asthmatic horses as compared to the normal horses was TNF-α. This suggested that the inflammation in asthmatic horses might be due to a chronic antigenic reaction rather than an acute inflammatory immune response.