Differential association of MUC5AC and CLCA1 expression in small cartilaginous airways of RAO-affected and control horses.

This research study focuses on exploring the impact of indoor irritant and allergen exposure in horses with recurrent airway obstruction (RAO). It hypothesizes that such exposure increases expression of a particular gene called eqMUC5AC, which results in increased stored mucus in the airways of affected horses. This research further suggests that this process could be associated with increased neutrophils and two key signaling molecules, CLCA1 and EGFR.

Research Methodology

• The research utilized quantitative reverse transcription polymerase chain reaction (RT-PCR) to measure the levels of eqMUC5AC, CLCA1 and EGFR.
• The scientists carried out volume density measurements of mucosubstances present within the epithelial cells of the airways.
• Additionally, they performed cytological differentiation of inflammatory cells within the lumen of small cartilaginous airways.
• The samples for these investigations were collected from cranial left and right and caudal left and right lung lobes of both clinically healthy and RAO-affected horses. These horses had been exposed to an indoor stable environment for 5 days prior to euthanasia.

Research Findings

• New data suggest that the number of neutrophils, a type of inflammatory cell, increased in RAO-affected horses compared to clinically healthy controls.
• The levels of eqMUC5AC mRNA, the product of the mucin gene, showed positive correlation with both CLCA1 and EGFR mRNA levels in RAO-affected horses. However, in healthy controls, eqMUC5AC mRNA levels correlated only with CLCA1.
• The relationship between eqMUC5AC and CLCA1 differed between the two groups of horses. Horses with RAO demonstrated overexpression of CLCA1 in relation to eqMUC5AC.

Conclusions

• The research concludes that CLCA1 plays an essential role in eqMUC5AC gene expression in horses. However, it also suggests a differential regulation by CLCA1 and EGFR between horses suffering from RAO and those with milder forms of airway inflammation.
• This research contributes to our understanding of the molecular mechanisms underlying RAO and could aid in developing effective treatment strategies for affected horses.