Disparate effects of LPS infusion and carbohydrate overload on inflammatory gene expression in equine laminae.

The research investigates the difference in inflammatory responses in horses caused by both carbohydrate overload and Lipopolysaccharides (LPS) infusion to better understand their role in the development of acute laminitis, a common and debilitating disease in horses.

Objective and Approach

• The main purpose of this study was to determine the involvement of endotoxins, such as Lipopolysaccharides (LPS), in the development of acute laminitis and their influence on the genes associated with inflammation.
• The researchers administrated either mixed carbohydrates (CHO) or LPS endotoxin directly to the horses and then compared the variations in clinical signs of laminitis, levels of plasma TNF-α (Tumor necrosis factor alpha) and IL-10 (Interleukin 10), and the impact on laminar tissue genes linked with inflammation.

Experiment and Findings

• The horses were classified into four groups: The control group received a water placebo, one group received the LPS endotoxin, and the remaining two groups were given CHO. One of the CHO group’s venous pressure was lowered by 30%, while the other was made to develop Obel grade I laminitis.
• The results showed that horses given LPS developed symptoms consistent with systemic inflammation— they displayed rapid increments in the levels of TNF-α and IL-10 and leukopenia (reduction in white blood cells). However, there were no changes observed in the laminar tissue genes involved with inflammation.
• On the other hand, the CHO-administered horses also showed signs of systemic inflammation but at a much slower pace, including increased TNF-α, IL-10, and total white blood cell counts. More importantly, these horses showed a significant increase in the expression of genes associated with inflammation in the laminar tissues and also displayed clinical signs of laminitis.

Conclusion

• These findings suggest that factors other than endotoxins might be responsible for the onset of acute equine laminitis. Inflammation changes in laminar tissue genes appear to be more associated with carbohydrates than LPS.
• Thus, the study provides additional validation to the idea that in the pathogenesis of acute laminitis, excessive carbohydrate consumption plays a more crucial role than endotoxins like LPS.