Li-Yan Chen

Inhibition of glycogen synthase kinase 3β ameliorates D-GalN/LPS-induced liver injury by reducing endoplasmic reticulum stress-triggered apoptosis.

Background Glycogen synthase kinase 3β(GSK3β) is a ubiquitous serine-threonine protein kinase that participates in numerous cellular processes and disease pathophysiology. We aimed to determine therapeutic potential of GSK3β inhibition and its mechanism in a well-characterized model of lipopolysaccharide (LPS)-induced model of acute liver failure (ALF). Methodology In a murine ALF model induced by D-GalN(700 mg/kg)/LPS(10 µg/kg), we analyzed GSK3β mechanisms using a specific chemical inhibitor, SB216763, and detected the role of endoplasmic reticulum stress (ERS). Mice were administered SB216763 at 2 h before or after D-GalN/LPS injection, respectively, and then sacrificed 6 h after D-GalN/LPS treatment to evaluate its prophylactic and therapeutic function. The lethality rate, liver damage, ERS, cytokine expression, MAP kinase, hepatocyte apoptosis and expression of TLR 4 were evaluated, respectively. Whether the inhibition of GSK3β activation protected hepatocyte from ERS-induced apoptosis was investigated in vitro. Principal Findings GSK3β became quickly activated (dephosphorylated) upon D-GalN/LPS exposure. Administration of SB216763 not only ameliorated liver injury, as evidenced by reduced transaminase levels, and well-preserved liver architecture, but also decreased lethality. Moreover, GSK3β inhibition resulted in down-regulation of pro-apoptotic proteins C/EBP–homologous protein(CHOP) and caspase-12, which are related to ERS. To further demonstrate the role of ERS, we found that GSK3β inhibition protected hepatocyte from ERS-induced cell death. GSK3β inhibition down-regulated the MAPK pathways, reduced expression of inflammatory cytokines and decreased expression of TLR4. Conclusions Our findings demonstrate the key function of GSK3β signaling in the pathophysiology of ALF, especially in regulating the ERS, and provide a rationale for targeting GSK3β as a potential therapeutic strategy to ameliorate ALF.

Hepatoprotective effects of cathepsin B inhibitor on acute hepatic failure induced by lipopolysaccharide/D-galactosamine in mice.

BACKGROUND Increasing evidence suggests that the inactivation of cathepsin B attenuates hepatocyte apoptosis and liver damage. This study aimed to investigate the protective effects of a cathepsin B inhibitor (CA-074me) on lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute hepatic failure (AHF) in mice. METHODS Mice were intraperitoneally injected with a combination of LPS/D-GalN to induce AHF with or without CA-074me pretreatment. The cumulative survival rates were calculated 48 hours after the induction of AHF. As well as changes in biochemical indicators and liver histology, hepatocyte apoptosis was assessed using a TUNEL method. Serum tumor necrosis factor-alpha (TNF-alpha) production, caspase-3, caspase-8, and caspase-9 activity was evaluated. Cytosolic cytochrome c and Bcl-2 expression were measured by Western blotting. RESULTS The marked elevation in serum aminotransferase activity and prothrombin time found in LPS/D-GalN-treated mice was significantly improved by pretreatment with CA-074me. The efficacy of CA-074me was also confirmed by histological analysis and TUNEL assay. The survival rate significantly improved in LPS/D-GalN-induced mice given CA-074me compared with untreated mice. LPS/D-GalN-induced caspase-3 and caspase-9 activation was remarkably suppressed by CA-074me. However, the increased levels of serum TNF-alpha and elevated caspase-8 activity in AHF mice were not significantly reduced by CA-074me. Moreover, CA-074me sharply reduced the increased expression of cytosolic cytochrome c and markedly augmented Bcl-2 expression. CONCLUSION These results suggest that CA-074me has a protective effect in acute hepatic failure induced by LPS/D-GalN.

Effect of SNMC on inhibiting hepatocyte apoptosis induced by Fas/FasL in mice with fulminant hepatic failure

AIM: To study the effect of Stronger Neo-Minophagen C (SNMC) on inhibiting hepatocyte apoptosis in mice with fulminant hepatic failure (FHF) and its mechanism. METHODS: Seventy mice were divided randomly into three groups: A (normal control group, n = 5), B (model group, n = 5) and C (SNMC-protecting group, n = 60). Mice in groups A and B were killed 6 h after treated with SNMC. Mice in group C were killed 6 h, 1, 3, 5 and 7 d after treated with SNMC respectively, five mice for each time. The hepatocyte apoptosis in situ was detected by TUNEL. The ultrastructure of hepatocytes was examined by electron microscopy. The expression of Fas, FasL and caspase-3 was detected by immunohistochemistry. RESULTS: The hepatocyte apoptosis index was 32.3% 6 h after treated with SNMC in group C, which was decreased to 5% after 7 d. The apoptosis index was significantly lower 1, 3, 5 and 7 d after treated with SNMC in group C than that in group B (P <0.01). Small amount of Fas and caspase-3 were expressed in group A, while no FasL was expressed. The cells with Fas, FasL and Caspase-3 expression were increased significantly. However, Fas, FasL and Caspase-3 expression was decreased with the increasing of time in group C, and their levels were significantly lower 1, 3, 5 and 7 d after treated with SNMC than those in group B (P<0.01). CONCLUSION: SNMC can effectively protect hepatocytes from apoptosis in mice with FHF, and the mechanism may be related to its effect on the inhibition of Fas/FasL.