Ru-hui Song

Kinetics of IL-6 and TNF-α changes in a canine model of sepsis induced by endotoxin.

Sepsis is a major cause of death in veterinary medicine, although a better prognosis can result from an early diagnosis. To speed the diagnosis, the biomarkers TNF-α and IL-6 can provide valuable information regarding systemic inflammatory response. The purpose of this study was to investigate the changes in cytokine levels in an experimental model of sepsis using ELISA and real-time PCR. Ten adult Beagles were studied; seven received an IV bolus of high dose lipopolysaccharide solution (1mg/kg) to induce sepsis. The remaining three beagles were the control group. Blood samples were collected before and 1, 3, 6, 12, 24 and 48 h after administering LPS. Serum IL-6 level peaked at 3h (1.89 ± 0.10 ng/ml) and serum TNF-α peaked at 1h (1.11 ± 0.01 ng/ml). The expression of IL-6 mRNA in peripheral blood mononuclear cells (PBMC) increased 62-fold compared to the control group at 1h; TNF-α mRNA increased by 4.5-fold at 1h. The expressions of IL-6 and TNF-α mRNA in PBMCs changed more rapidly than serum IL-6 and TNF-α concentrations. In addition, TNF-α mRNA levels in PBMCs remained elevated longer than serum TNF-α. Our study establishes the basis for future work aimed at a better understanding of the systemic inflammatory response to infection and sepsis in canine patients.

Valproic acid attenuates the expression of pro-inflammatory cytokines lipopolysaccharide-treated canine peripheral blood mononuclear cells (in vitro) and in a canine endotoxemia model (in vivo)

Valproic acid (VPA), a known histone deacetylase inhibitor, has been used as an anticonvulsant in dogs. VPA also has anti-inflammatory properties, but there are no reports on the immunomodulatory effects of VPA in canine endotoxemia. In the present study, we demonstrate that the use of VPA significantly reduces the production of early-phase pro-inflammatory cytokines (TNF-α, IL-6) caused by lipopolysaccharide (LPS) stimulation both in vitro and in vivo. For the in vitro study, VPA was evaluated for 24h on LPS (100 ng/ml)-treated canine peripheral blood mononuclear cells (PBMCs) which isolated from 5 healthy Beagle dogs. VPA significantly decreased the mRNA expression of TNF-α and IL-6 in a dose-dependent manner (p<0.05 for IL-6; p<0.01 for TNF-α). Fourteen adult Beagles were studied for in vivo study; nine dogs received a low dose of LPS (10 μg/kg/h) via continuous IV infusion for 12h to induce endotoxemia whereas 5 dogs received normal saline as controls. Four out of 9 endotoxemic dogs were administered VPA (50mg/kg, IV) at 1h and 12h along with the LPS infusion. Three hours after the first administration of VPA, IL-6 mRNA expressions in PBMCs significantly decreased (p=0.033 vs. LPS group). VPA also significantly decreased the circulating TNF-α (p=0.044 vs. LPS group at 3h) and IL-6 protein at 3h (p=0.034 vs. LPS group) and 6h (p=0.026 vs. LPS group) post-treatment. Our study suggests that VPA attenuates the expression of pro-inflammatory cytokines in a canine endotoxemia model in vitro and in vivo. We speculate that valproic acid may be useful for reducing inflammatory cytokine levels in dogs with sepsis.