endothelin-1 and Hepatitis

Small-for-size liver grafts are a serious obstacle for partial orthotopic liver transplantation. Activated protein C (APC), a potent anticoagulant serine protease, is known to have cell-protective properties due to its anti-inflammatory and antiapoptotic activities. This study was designed to examine the cytoprotective effects of a preservation solution containing APC on small-for-size liver grafts, with special attention paid to ischemia-reperfusion injury and shear stress in rats. APC exerted cytoprotective effects, as evidenced by (1) increased 7-day graft survival; (2) decreased initial portal pressure and improved hepatic microcirculation; (3) decreased levels of aminotransferase and improved histological features of hepatic ischemia-reperfusion injury; (4) suppressed infiltration of neutrophils and monocytes/macrophages; (5) reduced hepatic expression of tumor necrosis factor alpha and interleukin 6; (6) decreased serum levels of hyaluronic acid, which indicated attenuation of sinusoidal endothelial cell injury; (7) increased hepatic levels of nitric oxide via up-regulated hepatic endothelial nitric oxide synthesis expression together with down-regulated hepatic inducible nitric oxide synthase expression; (8) decreased hepatic levels of endothelin 1; and (9) reduced hepatocellular apoptosis by down-regulated caspase-8 and caspase-3 activities. These results suggest that a preservation solution containing APC is a potential novel and safe product for small-for-size liver transplantation, alleviating graft injury via anti-inflammatory and antiapoptotic effects and vasorelaxing conditions.

Topics: Animals; Anticoagulants; Apoptosis; Endothelin-1; Graft Survival; Hepatitis; Interleukin-6; Liver; Liver Function Tests; Liver Transplantation; Macrophages; Male; Microcirculation; Neutrophil Infiltration; Nitric Oxide; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Organ Preservation Solutions; Portal Pressure; Primary Graft Dysfunction; Protein C; Rats; Rats, Wistar; Tumor Necrosis Factor-alpha

In vivo studies have shown that chronic alcohol consumption sensitizes the liver to endotoxemic shock, leading to liver microcirculation disruption. In the present study, we investigated the molecular mechanisms involved, focusing on endothelial nitric oxide synthase (eNOS) activity and regulation, which represents one of the major vasodilatory pathways. Male Sprague-Dawley rats were fed an alcohol liquid diet or a control isocaloric diet for 5 weeks. Priming effects of ethanol were studied in a model with or without a 24-h LPS treatment (1 mg/kg body weight). At the end of the diet, liver tissue was harvested for western blot, reverse transcriptase-PCR, histological analysis, and immunostaining and blood for serum alanine aminotransferase analysis. Chronic ethanol and LPS alone induced a mild hepatitis and infiltration, respectively. Combined, LPS and chronic ethanol feeding showed a synergistic effect on the liver, leading to extensive steatohepatitis with extensive focal necrosis associated with significantly higher levels of serum ALT. Chronic ethanol and LPS significantly inhibited eNOS activity, but exerted their effects through different mechanisms. Caveolin-1, an eNOS inhibitory protein, was upregulated after LPS and chronic alcohol consumption. Additionally, chronic alcohol consumption down-regulated endothelin B receptor, eNOS protein levels, and eNOS phosphorylation. In conclusion, chronic ethanol consumption and LPS share a similar pathophysiology and both lead to the impairment of eNOS activity, but through distinct molecular mechanisms. The presence of focal necrosis in a mild stress model could provide a good animal study to investigate the advanced stages of alcoholic liver diseases.

Topics: Alanine Transaminase; Alcohol Drinking; Animals; Blotting, Western; Body Weight; Down-Regulation; Drug Synergism; Endothelin-1; Endotoxins; Ethanol; Gene Expression Regulation, Enzymologic; Hepatitis; Immunohistochemistry; Lipopolysaccharides; Liver; Male; Necrosis; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Phosphorylation; Rats; Rats, Sprague-Dawley; Receptor, Endothelin B; Reverse Transcriptase Polymerase Chain Reaction; RNA; RNA, Messenger