Indices of oxidative stress in blood and pulmonary epithelium lining fluid in horses suffering from recurrent airway obstruction.

The research investigates the possible connection between reactive oxygen species and lower airway disorders in horses experiencing recurrent airway obstruction (RAO). Through blood and fluid samples from the lining of the lung’s epithelium, the researchers identified significant oxidative stress in horses during an RAO-induced crisis, potentially corroborating the hypothesis.

Hypothesis and Purpose

• The study sought to test the hypothesis that lower airway disorders in horses suffering from Recurrent Airway Obstruction (RAO) can be linked to reactive oxygen species. Reactive oxygen species are chemically reactive molecules containing oxygen, which can inflict significant damage to cell structures. They are usually produced as a byproduct of metabolic processes.
• To measure this, the researchers decided to analyze indices of oxidative stress in blood samples and samples from the lining fluid in the lung’s epithelium.

Methodology

• The team used five horses with RAO, either in their remission stage or 24 hours after the beginning of a bronchospasm crisis—a sudden constriction of the lung airways. They also took samples from five healthy horses to compare results.
• Blood samples and bronchoalveolar lavage fluid (BALF) from each horse were collected for analysis. The elements being analyzed included reduced glutathione (GSH), oxidized glutathione (GSSG), total glutathione (TGSH), and the glutathione redox ratio (GRR)—all markers of oxidative stress.

Findings

• The results showed that the concentrations of GSH, GSSG, TGSH, and GRR in the hemolysate (a substance derived from the dissolution of red blood cells) were similar across all three groups.
• However, the glutathione status of the pulmonary epithelium lining fluid (PELF) in RAO horses during an acute crisis was significantly different compared to healthy horses. This suggested the occurrence of oxidative stress during a crisis.
• Interestingly, when RAO horses were in crisis, their GSH and TGSH levels remained stable, but the GSSG and GRR showed a significant increase, indicating a significant increase in oxidative stress compared to remission.

Conclusion

• The changes observed in the PELF glutathione state of horses with RAO during critical episodes support the initial hypothesis that oxidative stress is linked with the lower airway disorders occurring in horses suffering from RAO.
• This study provides a potential pathway to seek treatments to manage and prevent RAO in horses, by mitigating this oxidative stress.