ABSTRACT
Recent in vitro studies have shown that isohelenin, a sesquiterpene lactone, inhibits the NF-kappaB pathway. This study examines the effect of isohelenin in endotoxic shock induced by administration of Escherichia coli endotoxin in male Wistar rats. A group of rats received isohelenin (2 mg/kg intraperitoneally) 15 min before endotoxin. In vehicle-treated rats, administration of endotoxin caused severe hypotension, which was associated with a marked hyporeactivity to norepinephrine and acetylcholine in ex vivo aortas. Elevated levels of plasma nitrate/nitrite, metabolites of nitric oxide (NO), were also found. These inflammatory events were preceded by cytosolic degradation of inhibitor-kappaBalpha (IkappaBalpha) and activation of nuclear factor-kappaB (NF-kappaB) in the lung within 15 min of endotoxin administration. Treatment with isohelenin resulted in hemodynamic improvement and reduced plasma levels of NO metabolites. Nuclear translocation of NF-kappaB was inhibited by isohelenin treatment in the lung, whereas degradation of IkappaBalpha was unchanged. In a separate set of experiments, treatment with isohelenin significantly improved survival in mice challenged with endotoxin. We conclude that isohelenin exerts beneficial therapeutic effects during endotoxic shock through inhibition of NF-kappaB.
Subject(s)
Endotoxins/toxicity , Lipopolysaccharides/toxicity , NF-kappa B/antagonists & inhibitors , Sesquiterpenes/therapeutic use , Shock, Septic/prevention & control , Acetylcholine/metabolism , Animals , Blotting, Western , Electrophoresis , Hemodynamics/drug effects , Lung/metabolism , Mice , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/drug effects , Nitrates/metabolism , Nitrites/metabolism , Norepinephrine/metabolism , Proteins/metabolism , Rats , Shock, Septic/physiopathologyABSTRACT
BACKGROUND: Interleukin 10 (IL-10) exerts a wide spectrum of regulatory activities in immune and inflammatory responses. AIMS: The aim of this study was to investigate the role of endogenous IL-10 on modulation of the early inflammatory response after splanchnic ischaemia and reperfusion. METHODS: Intestinal damage was induced by clamping the superior mesenteric artery and the coeliac trunk for 45 minutes followed by reperfusion in IL-10 deficient mice (IL-10(-/-)) and wild-type controls. RESULTS: IL-10(-/-) mice experienced a higher rate of mortality and more severe tissue injury compared with wild-type mice subjected to ischaemia and reperfusion. Splanchnic injury was characterised by massive epithelial haemorrhagic necrosis, upregulation of P-selectin and intercellular adhesion molecule 1, and neutrophil infiltration. The degree of oxidative and nitrosative damage was significantly higher in IL-10(-/-) mice than in wild-type littermates, as indicated by elevated malondialdehyde levels and formation of nitrotyrosine. Plasma levels of the proinflammatory cytokines tumour necrosis factor alpha and interleukin 6 were also greatly enhanced in comparison with wild-type mice. These events were preceded by increased immunostaining and activity of the stress regulated c-Jun NH(2) terminal kinase and activation of the transcription factor activator protein 1 in the cellular nuclei of damaged tissue. CONCLUSIONS: These data demonstrate that endogenous IL-10 exerts an anti-inflammatory role during reperfusion injury, possibly by regulating early stress related genetic response, adhesion molecule expression, neutrophil recruitment, and subsequent cytokine and oxidant generation.
