Exogenous S-nitrosoglutathione Atte-Nuates Inflammatory Response And Intestinal Epithelial Barrier Injury In Endotoxemic Rats

Part I GSNO attenuates the systemic and intestinal inflammation in endotoxemic ratsBACKGROUND Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection and remains the leading reason for high morbidity and mortality in critical ill patiens. Gut barrier injury caused by gut inflammation in sepsis is a major contributor to aggravated system inflammation and distant organ dysfunction. S-nitrosoglutathione (GSNO) has shown anti-inflammatory effects in many inflammatory diseases. In this part, we tested the potential therapeutic effect of exogenous GSNO on endotoxin-induced inflammatory response and intestinal histofogical injury in a rat model of endotoxemia.METHODS Male Sprague-Dawley rats were randomly assigned to four groups: Control (saline only), GSNO, lipopolysaccharide (LPS) and LPS+GSNO. Femoral venous injection of LPS (10mg/kg) or saline was followed by GSNO (1mg/kg) or saline injection 15 min later. Distal ileum tissues and blood were harvested after 3h of LPS/saline injection. The intestinal histologic injury was measured by HE sections and grades. Systemic and intestinal inflammation was measured by analyzing the TNF and EL-1? levels in plasma and distal ileum tissue, respectively.RESULTS Compared to the Control rats, higer plasma and intestinal TNF and IL-1? levels was shown in the endotoxemic rats. Addition of GSNO attenuated the intestinal injury observed in histological sections, reduced plasma and intestinal TNF and EL-1? levels in the endotoxemic rats.CONCLUSION The data indicate that GSNO protects against the LPS-induced systemic inflammatory response and attenuated intestinal inflammation and histological injury in the endotoxemic rats.Part II GSNO attenuates intestinal epithelial barrier injury in endotoxemic ratsBACKGROUND Gut barrier injury in sepsis is a major contributor to distant organ dysfunction and bad clinical outcomes. Enteric glia-derived S-nitrosoglutathione (GSNO) has been recognized as a novel modulator of gut barrier integrity. In this part, we tested the potential therapeutic effect of exogenous GSNO on intestinal barrier injury in a rat model of endotoxemia.METHODS Male Sprague-Dawley rats were randomly assigned to four groups: Control (saline only), GSNO, lipopolysaccharide (LPS) and LPS+GSNO. Femoral venous injection of LPS (10mg/kg) or saline was followed by GSNO (1mg/kg) or saline injection 15 min later. Distal ileum tissues were harvested after 3h of LPS/saline injection. According to the permeability assay, FITC-dextran was injected into the ligated intestinal lumen after 3h of LPS/saline injection, then blood was harvested at 30 min later. The intestinal barrier function was measured by intestinal permeability to FITC-dextran. The ultrastructural change of the epithelial tight junctions was observed using transmission electron microscope and analyzing the expression level of tight junction protein ZO-1 using immunofluorescence and western blot.RESULTS Compared to the Control rats, higher plasma FITC-dextran level and the disruption of epithelial tight junctions were shown in the endotoxemic rats, as well as the decreased stain and expression of ZO-1. Addition of GSNO decreased the intestinal permeability to FITC-dextran, attenuated the damage of the junctions between epithelia and protected against the LPS-induced expression decrease of ZO-1.CONCLUSION The data indicate that GSNO protects against the LPS-induced intestinal epithelial barrier injury and improve the intestinal barrier function in rats, protects the structure of epithelial tight junctions and the expression of the tight junction protein ZO-1.Part ? The potential mechanism of the protective effect of GSNO on the intestinal epithelial barrier in endotoxemic ratsBACKGROUND Intestinal epithelial barrier tignt juctions injury in sepsis is closely associated with inteatinal inflammation, the activity of NF-?B in intestinal tissue and the expression of MLCK in intestinal epithelia. GSNO has been recognized as a novel modulator of gut inflammation and barrier integrity. In this study, we tested the potential mechanism of exogenous GSNO on endotoxin-induced intestinal inflammatory response and intestinal barrier injury in a rat model of endotoxemia.METHODS Male Sprague-Dawley rats were randomly assigned to four groups: Control (saline only), GSNO, lipopolysaccharide (LPS) and LPS+GSNO. Femoral venous injection of LPS (10mg/kg) or saline was followed by GSNO (1mg/kg) or saline injection 15 min later. Distal ileum tissues were harvested after 3h of LPS/saline injection. The cytoplasmprotein and nuclear protein of the diatal ileum tissues were extracted, the levels of nuclear NF-?B p 65 and cytoplasm MLCK were measured by western-blot.RESULTS Compared to the Control rats, higher MLCK expression and nuclear NF-?B p65 level were shown in the intestine of the endotoxemic rats, addition of GSNO inhibited the LPS-induced upregulation of MLCK expression and nuclear NF-?B p65 level in the intestine.CONCLUSION The data indicate that the protective effects of GSNO on intestinal inflammation and epithelial barrier injury in rats are possibly through inhibition of the NF-?B pathway and GSNO protects against the disruption of intestinal epithelial tight inuctions through inhibiting NF-?B activation and MLCK expression.