transforming-growth-factor-alpha and Liver-Failure--Acute

Efficient repopulation by transplanted hepatocytes in the severely injured liver is essential for their clinical application in the treatment of acute hepatic failure. We studied here whether and how the transplanted hepatocytes are able to efficiently repopulate the toxin-induced acute injured liver. Male dipeptidyl peptidase IV-deficient F344 rats were randomized to receive retrorsine plus D-galactosamine (R+D-gal) treatment or D-galactosamine-alone (D-gal) to induce acute hepatic injury, and retrorsine-alone. In these models, retrorsine was used to inhibit the proliferation of endogenous hepatocytes while D-galactosamine induced acute hepatocyte damage. Wild-type hepatocytes (1 x 10(7)/ml) were transplanted intraportally 24 h after D-galactosamine or saline injection. The kinetics of proliferation and repopulation of transplanted cells and the kinetics of cytokine response, hepatic stellate cell (HSC) activation, and matrix metalloproteinase (MMP2) expression were analyzed. We observed that early entry of transplanted hepatocytes into the hepatic plates and massive repopulation of the liver by transplanted hepatocytes occurred in acute hepatic injury induced by R+D-gal treatment but not by D-gal-alone or retrorsine-alone. The expressions of transforming growth factor-alpha and hepatocyte growth factor genes in the R+D-gal injured liver were significantly upregulated and prolonged up to 4 weeks after hepatocyte transplantation. The expression kinetics were parallel with the efficient proliferation and repopulation of transplanted hepatocytes. HSC was activated rapidly, markedly, and prolongedly up to 4 weeks after hepatocyte transplantation, when the expression of HGF gene and repopulation of transplanted hepatocytes were reduced afterward. Furthermore, the expression kinetics of MMP2 and its specific distribution in the host areas surrounding the expanding clusters of transplanted hepatocytes are consistent with those of activated HSC. Impaired hepatocyte regeneration after acute severe hepatic injury may initiate serial compensatory repair mechanisms that facilitate the extensive repopulation by transplanted hepatocytes that enter early the hepatic plates.

Topics: Animals; Chemical and Drug Induced Liver Injury; Galactosamine; Hepatic Stellate Cells; Hepatocyte Growth Factor; Hepatocytes; Liver Failure, Acute; Liver Regeneration; Male; Matrix Metalloproteinase 2; Pyrrolizidine Alkaloids; Rats; Rats, Inbred F344; Transforming Growth Factor alpha; Up-Regulation

The mortality rate of fulminant hepatic failure (FHF) is high because of retarded liver regeneration. Recombinant human granulocyte colony-stimulating factor (rHuG-CSF) and tacrolimus are known to be immunosuppressive and supportive to liver regeneration. We investigated the effects of their combination therapy in a rat FHF model with a 68% partial hepatectomy and 24% liver necrosis. All rats without drug pretreatment died within 55 h. The median time was prolonged from 37 to 52 h by rHuG-CSF (250 microg/kg/day s.c. on days -5 to 0) and to 46 h by tacrolimus (0.5 mg/kg/day i.m. on days -2 to 0). Notably, the combination therapy facilitated DNA biosynthesis and survival prolongation, with a median of 77 h. The interferon-gamma (IFN-gamma) protein levels and natural killer cell (NK) activity in the liver were low at 12 h, and no further inhibition was detected by any treatment. Tacrolimus significantly upregulated the mRNA levels of insulin receptors and transforming growth factor-alpha (TGF-alpha), whereas rHuG-CSF did not. Regarding tissue remodeling-related factors, rHuG-CSF upregulated mRNA levels of vascular endothelial growth factor (VEGF) and matrix metalloproteinase- 9 (MMP-9), whereas tacrolimus did not. The combination treatment upregulated protein levels of both insulin receptors and VEGF. These results suggest that tacrolimus improves the hepatocyte replication and rHuG-CSF contributes to tissue reconstitution, and this combination therapy directly facilitates liver regeneration in the FHF model.

Topics: Animals; Disease Models, Animal; DNA Replication; Drug Therapy, Combination; Granulocyte Colony-Stimulating Factor; Hepatocytes; Immunosuppressive Agents; Interferon-gamma; Killer Cells, Natural; Liver; Liver Failure, Acute; Liver Regeneration; Male; Matrix Metalloproteinase 9; Rats; Rats, Sprague-Dawley; Receptor, Insulin; Recombinant Proteins; RNA, Messenger; Tacrolimus; Transforming Growth Factor alpha; Treatment Outcome; Up-Regulation; Vascular Endothelial Growth Factor A

In this study we sought to determine whether molecular mechanisms involved in the pathogenesis of fulminant hepatic failure are present in rabbits experimentally infected with rabbit hemorrhagic disease virus (RHDV). The activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase, as well as bilirubin concentration, were found to be significantly increased 36 hours after infection. Infected animals also demonstrated significant decreases in factor VII activity, in the Fischer index, and in the deterioration of prothrombin time. The concentration of reduced glutathione was significantly decreased 36 hours after infection, and we noted a marked increase in the ratio of oxidized to reduced glutathione. Infected animals showed progressive decreases in liver activity of the antioxidant enzyme superoxide dismutase. Expression of hepatocyte growth factor and c-met was found to be progressively reduced from 24 hours after infection, during which time we detected no modification in messenger RNA (mRNA) levels of transforming growth factor (TGF)-alpha. TFG-beta 1 was overexpressed 24 and 36 hours after infection, and 36 hours after infection we detected a significant increase in TNF-alpha mRNA levels. Experimental RHDV infection also induced marked activation of nuclear factor-kappaB and a significant increase in inducible nitric oxide synthase mRNA levels from 24 hours after infection. Data obtained from this animal model support its usefulness in the investigation of potential novel therapeutical modalities aimed at neutralizing reactive oxygen species and hepatocyte growth inhibitors or enhancing hepatocyte responsiveness to mitogens.

Topics: Alanine Transaminase; Animals; Aspartate Aminotransferases; Bilirubin; Caliciviridae Infections; Disease Models, Animal; Gene Expression; Glutathione; Hemorrhagic Disease Virus, Rabbit; Hepatocyte Growth Factor; Humans; L-Lactate Dehydrogenase; Liver; Liver Failure, Acute; Proto-Oncogene Proteins c-met; Rabbits; RNA, Messenger; Superoxide Dismutase; Transforming Growth Factor alpha