Inflammatory Cytokine Blood Messenger RNA Expression During the Development of Oligofructose-Induced Laminitis in Horses

Article Outline

• Take Home Message
• Introduction
• Materials & Methods
• Results
• Discussion
• Clinical Relevance
• Conclusion
• Copyright

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Take Home Message 

Alimentary carbohydrate overload induces systemic inflammation in horses.

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Introduction 

Clinical signs of systemic inflammation have been detected after carbohydrate overload, but inflammatory cytokine responses have not been characterized.

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Materials & Methods 

Blood was obtained from 14 adult horses that received 10g/kg body weight oligofructose (OF) to induce laminitis at another institution. Total RNA was extracted from whole blood samples collected at 0, 8, 12, 16, 20, and 24 hours. Real-time PCR analysis was performed to detect mRNA expression of the target cytokines IL-1β, IL-6, IL-8, IL-10, TNF_α, and the housekeeping gene β-glucuronidase (β-Gus). The comparative CT (ΔΔCT) method was used to calculate relative mRNA expression. Mixed model analysis of variance for repeated measures was performed on log₁₀ transformed data. Back-transformed least squares means ± SEM are reported.

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Results 

All animals developed clinically detectable laminitis within 24 hours. Interleukin-1β, IL-6, IL-8, and IL-10 mRNA expression in blood significantly increased (P < 0.010) over time. Interleukin-1β expression peaked at 16 hours (8.1 ± 1.4-fold increase), IL-8 expression showed peaks at 8 (13.0 ± 4.1 fold increase) and 20 hours (20.8 ± 5.5 fold increase), IL-10 expression peaked at 16 hours (7.3 ± 1.7-fold increase), and IL-6 expression peaked at 16 hours (7.5 ± 3.3-fold increase). No significant change in TNFα mRNA expression was detected.

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Discussion 

Systemic inflammation develops in response to alimentary carbohydrate overload and this problem may occur when horses are grazing on pasture.

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Clinical Relevance 

Alimentary carbohydrate overload is an inflammatory event and should be treated accordingly.

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Conclusion 

Systemic inflammation may be an important component of pasture-associated laminitis in equids.