Activated T cells and soluble molecules in the portal venous blood of patients with cholestatic and hepatitis C virus-positive liver cirrhosis. Possible promotion of Fas/FasL-mediated apoptosis in the bile-duct cells and hepatocyte injury

Hepatocyte Turnover in Chronic HCV-Induced Liver Injury and Cirrhosis

Chronic hepatitis C virus (HCV) infection may eventually lead to progressive liver fibrosis and cirrhosis through a complex, multistep process involving hepatocyte death and regeneration. Despite common pathogenetic pathways present in all forms of liver cirrhosis irrespective of etiology, hepatocyte turnover and related molecular events in HCV-induced cirrhosis are increasingly being distinguished from even “similar” causes, such as hepatitis B virus- (HBV-) related cirrhosis. New insights in HCV-induced hepatocellular injury, differential gene expression, and regenerative pathways have recently revealed a different pattern of progression to irreversible parenchymal liver damage. A shift to the significant role of the host immune response rather than the direct effect of HCV on hepatocytes and the imbalance between antiapoptotic and proapoptotic signals have been investigated in several studies but need to be further elucidated. The present review aims to comprehensively summarize the current evidence on HCV-induced hepatocellular turnover with a view to outline the significant trends of ongoing research.

Zinc finger protein A20 protects rats against chronic liver allograft dysfunction

AIM: To investigate the effect of zinc finger protein A20 on chronic liver allograft dysfunction in rats.

METHODS: Allogeneic liver transplantation from DA rats to Lewis rats was performed. Chronic liver allograft dysfunction was induced in the rats by administering low-dose tacrolimus at postoperative day (POD) 5. Hepatic overexpression of A20 was achieved by recombinant adenovirus (rAd.)-mediated gene transfer administered intravenously every 10 d starting from POD 10. The recipient rats were injected with physiological saline, rAdEasy-A20 (1 × 10⁹ pfu/30 g weight) or rAdEasy (1 × 10⁹ pfu/30 g weight) every 10 d through the tail vein for 3 mo starting from POD 10. Liver tissue samples were harvested on POD 30 and POD 60.

RESULTS: Liver-transplanted rats treated with only tacrolimus showed chronic allograft dysfunction with severe hepatic fibrosis. A20 overexpression ameliorated the effects on liver function, attenuated liver allograft fibrosis and prolonged the survival of the recipient rats. Treatment with A20 suppressed hepatic protein production of tumor growth factor (TGF)-β1, interleukin-1β, caspase-8, CD40, CD40L, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and E-selectin. A20 treatment suppressed liver cell apoptosis and inhibited nuclear factor-κB activation of Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs) and hepatic stellate cells (HSCs), and it subsequently decreased cytokine mRNA expression in KCs and LSECs and reduced the production of TGF-β1 in HSCs.

CONCLUSION: A20 might prevent chronic liver allograft dysfunction by re-establishing functional homeostasis of KCs, LSECs and HSCs.

Imbalance of interleukin-18 and interleukin-18 binding protein in children with Henoch-Schönlein purpura

The balance between interleukin-18 (IL-18) and its endogenous antagonist, IL-18 binding protein (IL-18BP), was evaluated in children with Henoch-Schönlein purpura (HSP). Plasma IL-18 and IL-18BP levels and peripheral blood mononuclear cell IL-18 mRNA expression were significantly higher in patients with active HSP (n = 30) than in healthy controls (n = 20); IL-18BP mRNA expression was similar in active HSP and controls. Plasma levels and mRNA expression of IL-18 and IL-18BP in patients in remission (n = 19) were similar to those in controls. The ratios of IL-18 / IL-18BP plasma levels and IL-18 / IL-18BP mRNA levels in active HSP were significantly higher than in patients in remission and healthy controls. Thus, adequate IL-18BP to block the proinflammatory activity of IL-18 may not be present in active HSP and regulation of the IL-18 / IL-18BP balance might provide a potential therapeutic strategy.

Reduction of hepatocellular injury after common bile duct ligation using omega-3 fatty acids

PURPOSE

Bile duct obstruction and subsequent cholestasis produces hepatocellular injury and an inflammatory response. Fatty acid constitution of cell membranes plays a major role in the inflammatory cascade. Omega-3 fatty acids are antiinflammatory. We proposed that omega-3 fatty acid supplementation would reduce hepatocellular damage and cell death in a model of murine common bile duct ligation.

METHODS

Mice underwent bile duct ligation and were administered either control soy diet (omega-6) or Menhaden diet (omega-3), and parameters of liver injury were measured at postoperative days 1, 4, and 8. Serum was analyzed for liver function tests. Liver tissue was scored for histologic necrosis and inflammation, and apoptosis was qualitatively measured.

RESULTS

At day 8, comparing control and Menhaden, liver function tests were not significantly different. The H&E slides were analyzed and scored. At day 4, the mean necrosis scores for the Menhaden-fed group was 0.01 +/- 0.028 and 0.46 +/- 0.108 for the soy-fed group (P = .001) and at day 8, 0.420 +/- 0.107 and 1.22 +/- 0.132 (P < .001). The mean portal inflammation score for day 4 Menhaden-fed and soy-fed mice was 1.40 +/- 0.245 for both groups (P = 1.00) and for day 8, 1.80 +/- 0.200 and 2.80 +/- 0.200 (P = .008). At day 1, the median terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling scores of the Menhaden vs soy group were 6.0 and 0.0 (P < .001); day 4, 24.0 and 3.0 (P < .001); and day 8, 0.0 and 3.0 (P < .001), respectively.

CONCLUSION

Although there appears to be a trend toward biochemical protection and a marked reduction of necrosis and inflammation, there was no significant liver function test difference between control and Menhaden groups. Considering our data of blunted histologic hepatotoxicity with omega-3 fatty acid supplementation, we hypothesize that this may be a method of reducing long-term complications of liver injury secondary to diseases of cholestasis such as biliary atresia, namely fibrosis and cirrhosis.

Zinc finger protein A20 promotes regeneration of small-for-size liver allograft and suppresses rejection and results in a longer survival in recipient rats

BACKGROUND

Small-for-size liver allografts without immunosuppression have decreased survival compared with full-for-size grafts for the concomitant regeneration-induced accelerated rejection. This study was designed to examine the effect of zinc finger protein A20 on liver allograft regeneration and acute rejection using a high responder rat model (DA-->Lewis) of 30% partial liver transplantation.

MATERIALS AND METHODS

Adenovirus carrying the full length of A20 was introduced into liver grafts by ex vivo perfusion via the portal vein during preservation, physiological saline (PS), and empty Ad vector rAdEasy served as controls; then small-sized liver transplants were performed. Liver graft regeneration was assessed, as well as graft rejection, hepatocyte apoptosis, nuclear factor kappa B activation, and intercellular adhesion molecule-1 mRNA expression in liver graft sinusoidal endothelial cells (LSECs), infiltration of liver graft infiltrating mononuclear cells (LIMCs), and the subproportion of NK and NKT cells, activity of liver graft NK-like cells, interferon gamma (IFN-gamma) production, and animal survival.

RESULTS

Ex vivo transfer of the A20 gene resulted in overexpression of A20 protein in LSECs and hepatocytes 24 h after partial liver transplantation. Regeneration of the small-sized liver allograft was augmented by A20 overexpression, the DNA synthesis of hepatocytes on d 4 post-transplant was increased in A20 group compared with PS and rAdEasy groups (P < 0.01). Hepatocyte apoptosis was inhibited by A20 (P < 0.001). On d 4 after transplantation, histological examination revealed a more exiguous cellular infiltration and mild rejection in A20 group but a more vigorous cellular infiltration in the sinusoidal area and more severe rejection in PS and rAdEasy group. Nuclear factor kappa B activation and intercellular adhesion molecule-1 mRNA expression in LSECs were suppressed by A20 overexpression. Flow cytometry analysis showed a marked down-regulation of LIMCs number by A20, including more prominent decrease in the subproportion of NK and NKT cells. Activity of liver graft NK-like cells, IFN-gamma mRNA expression in LIMCs, and serum IFN-gamma protein level were also suppressed by A20 overexpression (P < 0.05), respectively. Survival days of A20 rats were longer than those of PS rats and rAdEasy rats (P < 0.01), whereas survival days of rAdEasy rats were shorter than those of PS rats (P < 0.01).

CONCLUSIONS

These data suggest that A20 overexpression could effectively promote small-sized liver allograft regeneration, suppress rejection, and prolong survival of recipient rat. These effects of A20 could be related to an inhibition of LSECs activation, suppression of infiltration of LIMCs, and the subpopulations such as NK and NKT cells into liver graft, and inhibition of hepatocyte apoptosis.

Augmented regeneration of partial liver allograft induced by nuclear factor-kappaB decoy oligodeoxynucleotides-modified dendritic cells

AIM

To investigate the effect of NF-kappaB decoy oligodeoxynuleotides (ODNs) - modified dendritic cells (DCs) on regeneration of partial liver allograft.

METHODS

Bone marrow (BM)- derived DCs from SD rats were propagated in the presence of GM-CSF or GM-CSF+IL-4 to obtain immature DCs or mature DCs, respectively. GM-CSF-propagated DCs were treated with double-strand NF-kappaB decoy ODNs containing two NF-kappaB binding sites or scrambled ODNs. Allogeneic (SD rat to LEW rat) 50% partial liver transplantation was performed. Normal saline (group A), GM-CSF -propagated DCs (group B), GM-CSF+IL-4 - propagated DCs (group C), and GM-CSF+NF-kappaB decoy ODNs (group D) or scrambled ODNs -propagated DCs (group E) were injected intravenously into recipient LEW rats 7 days prior to liver transplantation and immediately after transplantation. DNA synthesis (BrdU labeling) and apoptosis of hepatocytes were detected with immunostaining and TUNEL staining postoperative 24 h, 48 h, 72 h and 84 h, respectively. Liver graft-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma level at the time of the maximal liver allograft regeneration were measured with (51)Cr release assay, semiquantitative RT-PCR and ELISA, respectively.

RESULTS

Regeneration of liver allograft was markedly promoted by NF-kappaB decoy ODNs-modified immature DCs but was significantly suppressed by mature DCs, the DNA synthesis of hepatocytes peaked at postoperative 72 h in group A, group B and group E rats, whereas the DNA synthesis of hepatocytes peaked at postoperative 84 h in group C rats and 48 h in group D rats, respectively. The maximal BrdU labeling index of hepatocytes in group D rats was significantly higher than that in the other groups rats. NF-kappaB decoy ODNs-modified immature DCs markedly suppressed but mature DCs markedly promoted apoptosis of hepatocytes, liver-resident NK cell activity, hepatic IFN-gamma mRNA expression and recipient serum IFN-gamma production. At the time of the maximal regeneration of liver allograft, the minimal apoptosis of hepatocytes, the minimal activity of liver-resident NK cells, the minimal hepatic IFN-gamma mRNA expression and serum IFN-gamma production were detected in group D rats. The apoptotic index of hepatocytes, the activity of liver- resident NK cells, the hepatic IFN-gamma mRNA expression level and the serum IFN-gamma level in group D rats were significantly lower than that in the other groups rats at the time of the maximal regeneration of liver allograft.

CONCLUSION

The data suggest that the augmented regeneration of partial liver allograft induced by NF-kappaB decoy ODNs-modified DCs may be attributable to the reduced apoptotic hepatocytes, the suppressed activity of liver-resident NK cells and the reduced IFN-gamma production.