OBJECTIVETo investigate the protective effects of hepatic fibrosis against a lethal dose of acetaminophen (APAP) and its underlying mechanisms using a carbon tetrachloride (CCl4)-induced mouse model of fibrosis.

METHODSThe experimental model of hepatic fibrosis was established by intraperitoneal injection of CC14 (in mineral oil), twice a week for 6 weeks; mice given a 6-week course of mineral oil injections served as normal controls. At the end of fibrosis induction, the expmimental (Fib group) and control (Norm group) mice were challenged with APAP (1 g/kg). Sera and liver tissues were harvested for analyses.To assess tolerance of the normal and fibrotic mice to the lethal dose of APAP, the survival rate,serum alanine aminotransferase (sALT) levels and hepatic histopathological changes were compared before and after the acute APAP challenge.HMGB 1 expression was analyzed by immunohistochemistry.One-way ANOVA test and Newman-Keuls test were used in statistical analysis.

RESULTSThe fibrotic liver was tolerant to the lethal dose of APAP,as evidenced by:(1) significantly higher survival rate in the Fib ± APAP group (80% vs. Norm+APAP group: 0%); (2) markedly lower sALT levels in the Fib+APAP group (6 437 ± 1 913 U/L vs. 12 456 ± 3 441 U/L), P=0.022; (3) remarkably well-preserved liver architecture in the Fib+APAP group.Immunohistochemical analysis showed high HMGB1 expression and cytoplasmic translocation in the Norm+APAP group,which was absent in the Fib+APAP group.

CONCLUSIONSCCl4-induced liver fibrosis protects mice against lethal dose of APAP, Possibly by a mechanism involving inhibition of the cytoplasmic translocation of HMGB1.

Acetaminophen ; Alanine Transaminase ; Animals ; Carbon Tetrachloride ; Chemical and Drug Induced Liver Injury ; Disease Models, Animal ; Liver Cirrhosis ; Mice ; Protective Agents

OBJECTIVETo investigate whether inhibition of phosphatase and tensin homologue deleted on chromosome ten (PTEN) is protective against liver ischemia-reperfusion injury (IRI) in mice and to explore its possible mechanism.

METHODSLiver IRI was established in C57BL6/J mice by inducing 90 minutes of ischemia in the left/middle liver lobe followed by 6 hours of reperfusion. To investigate the role of PTEN in hepatic IRI, a subset of these mice received pre-treatment with the specific PTEN inhibitor bpv(HOpic), which was injected intraperitoneally at 2 hours prior to the ischemia insult. Serum alanine aminotransferase (sALT) levels were measured and liver histology was assessed in all mice. The levels of pro-inflammatory cytokines IL-12p40 and TNFa were detected by real-time PCR. The expression of p-AKT and p-ERK in liver tissues was analyzed by Western blotting.

RESULTSThe IRI group pre-treated with bpv(HOpic) showed significantly lower sALT values (3 075.0 +/- 807.4 U/L vs. IRI without pre-treatment: 11 460.0 +/- 1 783.0 U/L, P less than 0.01) and more well-preserved liver architecture. The expression of pro-inflammatory cytokines was inhibited markedly by the administration of bpv(HOpic); for IRI without pre-treatment vs.IRI pre-treated with bpv(HOpic), the IL-12 levels were 1.12 +/- 0.11 vs .0.55 +/- 0.13 ( P less than 0.01) and the TNFa levels were 1.62 +/- 0.20 vs. 0.35 +/- 0.07 ( P less than 0.01). Western blot analysis showed that the hepatic expression of both p-AKT and p-ERK was enhanced obviously in mice pretreated with the PTEN inhibitor.

CONCLUSIONPTEN inhibition alleviates hepatic ischemia-reperfusion injury via the up-regulation of pro-survival signaling mediated by p-AKT and p-ERK as well as the inhibition of hepatic inflammation. PTEN may represent a useful target for the treatment of liver IRI.

Animals ; Disease Models, Animal ; Liver ; blood supply ; Mice ; Mice, Inbred C57BL ; PTEN Phosphohydrolase ; antagonists & inhibitors ; metabolism ; Reperfusion Injury ; metabolism ; Signal Transduction

OBJECTIVETo study the role of endoplasmic reticulum stress (ERS) in acute liver failure (ALF) using a mouse model of D-Galactosamine/lipopolysaccharide (D-GalN/LPS)-induced ALF.

METHODSThe ALF model was established by administering intraperitoneal (i.p.) injections of D-Ga1N (700 mg/kg) and LPS (10 mug/kg) to six C57BL/6 mice. Three of the modeled mice were also administered 4-phenylbutyrate (4-PBA; 100 mg/kg i.p.) at 6 hours before the onset of ALF and served as the intervention group. Non-modeled mice served as controls. All mice were analyzed by western blotting and qRT-PCR to determine the expression levels of ERS-related proteins in liver tissue. Liver function was assessed by measuring levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in serum. Extent of injury to the liver tissue was assessed by hematoxylin-eosin staining and histological analysis. qRT-PCR was also used to detect differences in expression of inflammation-related genes, and western blotting was also used to detect differences in expression of the apoptosis related protein Caspase-3.The extent of apoptosis in liver tissue was assessed by TUNEL assay.

RESULTSThe ERS markers GRP78 and GRP94 showed increased expression at both the gene and protein levels which followed progression of ALF. The ERS effector proteins XBP-1, ATF-6 and IRE 1 a involved in the unfolded protein response were activated in the early stages of ALF, and the ERS-induced apoptosis regulators Caspase-12 and CHOP were activated in the late stage of ALF. Inhibition of ERS by 4-PBA intervention protected against injury to liver tissue and function, as evidenced by significantly lower levels of serum ALT and AST and a remarkably decreased extent of histological alterations. Furthermore, the inhibition of ERS suppressed expression of the proinflammatory cytokines TNFa, IL-6 and IL-1 β, and reduced the extent of hepatocyte apoptosis.

CONCLUSIONERS is activated in the mouse model of D-GalN/LPS-induced ALF. Inhibition of ERS may be protective against liver injury and the mechanism of action may involve reductions in inflammatory and apoptotic factors and/or signaling. Therefore, inhibiting ERS may represent a novel therapeutic approach for treating ALF.

Animals ; Apoptosis ; Disease Models, Animal ; Endoplasmic Reticulum Stress ; Galactosamine ; adverse effects ; Lipopolysaccharides ; adverse effects ; Liver Failure, Acute ; chemically induced ; metabolism ; pathology ; Male ; Mice ; Mice, Inbred C57BL