Changes in airway inflammatory cell populations in standardbred racehorses after interferon-alpha administration.

The study examines the impact of natural human interferon-alpha (nHuIFN alpha) on Standardbred racehorses experiencing inflammatory airway disease. The findings indicate that nHuIFN alpha, administered orally, significantly reduced inflammation in the horses’ respiratory tract.

Study Overview

• The research was conducted on Standardbred racehorses actively undergoing training, all of whom were suffering from inflammatory airway disease (IAD). IAD is marked by poor exercise performance along with inflammation and exudate in the upper and lower airway.
• The test was performed as a double-blind, randomized block design where the horses were given either a placebo or doses of 50 units (U), 150 U, or 450 U of nHuIFN alpha. The doses were given orally for five consecutive days with eight horses in each treatment group.

Observation and Evaluation

• The reaction to nHuIFN alpha was monitored by performing a semiquantitative endoscopic examination score and cytologic examination of bronchoalveolar lavage fluid (BALF), which was used to measure changes in inflammation. These were conducted at three stages: at baseline (Day 1), then on Day 8 and Day 15 after starting the nHuIFN alpha treatment.
• In comparison to the placebo, the BALF cell counts were lower eight days after administering 50 U and 150 U nHuIFN alpha, and 15 days after administering 50 U nHuIFN alpha. Specifically, there were fewer neutrophils, macrophages, lymphocytes, and nucleated cells (all components of the immune system involved in inflammation).
• The number of neutrophils, lymphocytes, and nucleated cells also showed a decrease eight days after administrating 450 U nHuIFN alpha.
• The treatments however, did not affect the proportion of CD4-, CD5-, and CD8-positive lymphocytes in the BALF.

Conclusion

• The main find from this study is that oral administration of low-dose nHuIFN alpha significantly reduced inflammation in the lowest respiratory tract of Standardbred racehorses experiencing IAD. This suggests that nHuIFN alpha may be a potential therapeutic agent for managing IAD in racehorses.