Effects of continuous or intermittent lipopolysaccharide administration for 48 hours on the systemic inflammatory response in horses.

The research is about the impacts of administering lipopolysaccharide (LPS), either intermittently or continuously for 48 hours, on the systemic inflammatory response in horses. It found that repetitive LPS exposure led to the development of tolerance within 24 hours, irrespective of the mode of administration, and did not induce laminitis.

Objective of the Study

• The primary aim of this study was to investigate how the two modes of lipopolysaccharide (LPS) administration (continuous vs intermittent) affect the intensity and duration of the systemic inflammatory response in horses.
• The study had a secondary goal to test whether prolonged endotoxemia (endotoxic shock) for 48 hours could trigger the development of laminitis, a painful and potentially crippling hoof disorder, in horses.

Methodology

• The study involved twelve healthy adult horses (10 mares and 2 geldings).
• The horses were randomly assigned to receive either an LPS (a total dose of 80 μg) or a saline solution as constant rate infusions or eight bolus IV injections over a 48-hour period.
• Every four hours, horses underwent physical examinations, while inflammatory cytokine gene expression tests were carried out through blood samples collected every eight hours.
• Additionally, Intravenous Glucose Tolerance Tests (IV GTT) were performed to check glucose and insulin dynamics.

Results

• All LPS-treated horses exhibited signs of depression and mild colic, though these symptoms subsided as the study continued.
• The administration of LPS resulted in increased expression of immune response proteins interleukin-1β, interleukin-6, and interleukin-8. However, the mode of LPS administration did not significantly influence these results.
• The expression of cytokines was significantly higher on the first day of LPS application than the second day, indicative of the development of LPS tolerance.
• No significant deviation was found in glucose and insulin dynamics between both LPS groups and the saline solution group.
• No signs of laminitis were observed in any of the horses.

Conclusion

• The study revealed that horses developed LPS tolerance within approximately 24 hours of administration, irrespective of the mode of LPS delivery.
• Furthermore, the method of LPS delivery did not significantly affect the duration or intensity of systemic inflammation.
• Laminitis was not observed in horses as a result of prolonged endotoxemia.