Effect of lipopolysaccharide infusion on gene expression of inflammatory cytokines in normal horses in vivo

Horses are exquisitely sensitive to bacterial endotoxin and endotoxaemia is common in colic cases. In this study, gene expression of inflammatory cytokines was characterised in the blood of healthy horses following i.v. administration of lipopolysaccharide (LPS). Six horses received an LPS infusion and 6 controls received an equivalent volume of saline. Gene expression of genes encoding interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, and tumour necrosis factor-alpha (TNF-alpha) was quantified by real-time PCR. Gene expression of all inflammatory cytokines was upregulated following administration of LPS. Interleukin-1 alpha, IL-1 beta, IL-8 and TNF-alpha gene expression peaked at 60 min, while IL-6 expression peaked at 90 min post LPS infusion. Interleukin-1 beta and IL-6 messenger RNA expression levels were above the baseline values 3 h post LPS infusion, whereas IL-1 alpha, IL-8 and TNF-alpha expression levels returned to baseline values by 3 h after LPS infusion. It was concluded that LPS infusion upregulated gene expression of inflammatory cytokines in the blood of healthy horses.