Previous studies suggest that production of interleukin-6 (IL-6) is increased in the intestinal mucosa during sepsis and endotoxaemia. We tested the hypothesis that mucosal IL-6 production during endotoxaemia is increased further by the heat-shock (stress) response. The stress response was induced in mice by hyperthermia (rectal temperature of 42 °C for 3 min) or by intraperitoneal injection of sodium arsenite (10 mg/kg). At 2 h after induction of the stress response, groups of mice were injected subcutaneously with endotoxin (10 mg/kg) or sterile saline. IL-6 mRNA and protein levels in the jejunal mucosa were determined by an RNase protection assay and an ELISA respectively, and levels of hsp72 (heat-shock protein of 72 kDa) were determined by Western blot analysis. Hyperthermia and sodium arsenite increased hsp72 levels in the intestinal mucosa. IL-6 concentrations were increased in the jejunal mucosa of endotoxaemic mice, and this effect of endotoxaemia was potentiated by the stress response. Mucosal IL-6 mRNA levels were increased in endotoxaemic mice, and were increased further by the stress response. Thus it is concluded that mucosal IL-6 production during endotoxaemia may be further stimulated by the stress response. Increased IL-6 levels in the intestinal mucosa may be a potential mechanism by which the stress response exerts a protective effect during sepsis and endotoxaemia.

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