Tumor necrosis factor alpha in the pathogenesis of human and murine fulminant hepatic failure.
OBJECTIVE
The tumor necrosis factor (TNF)-alpha/TNF receptor system is critical for liver development because hepatocytes undergo apoptosis if the antiapoptotic cascades resulting in RelA NF-kappaB activation are not effective. Therefore, we studied the role of TNF-alpha in fulminant hepatic failure (FHF) and developed a new therapeutic strategy.


METHODS
Serum levels and hepatic expression of TNF-alpha and both TNF receptors were determined by enzyme-linked immunosorbent assay and immunohistochemistry. Adenoviral vectors were constructed expressing dominant-negative proteins interfering with intracellular TNF-alpha-dependent pathways. The relevance of these constructs was studied in primary mouse hepatocytes and in a murine model of FHF.


RESULTS
Serum levels of TNF-alpha and TNF receptors are significantly increased in FHF; this increase correlates with patient prognosis. In livers of patients with FHF, infiltrating mononuclear cells express high amounts of TNF-alpha and hepatocytes overexpress TNF receptor 1 (TNF-R1). Apoptotic hepatocytes are significantly increased in FHF, and there is a strong correlation with TNF-alpha expression, which is even more pronounced in areas of mononuclear infiltrates. In an in vivo FHF model, the Fas-associated death domain (FADD), adenovirus selectively blocked the intracellular pathway, leading to mitochondrial cytochrome c release, caspase-3 activation, and, thus, apoptosis of hepatocytes.


CONCLUSIONS
The results show that the TNF-alpha/TNF-R1 system is involved in the pathogenesis of FHF in humans. Studies in this animal model indicate that FADD may serve as a molecular target to prevent liver cell death in vivo.
Streetz
K
K
Department of Gastroenterology and Hepatology, Medizinische Hochschule Hannover, Hannover, Germany.
Leifeld
L
L
Grundmann
D
D
Ramakers
J
J
Eckert
K
K
Spengler
U
U
Brenner
D
D
Manns
M
M
Trautwein
C
C
D048868:Adaptor Proteins, Signal Transducing; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002352:Carrier Proteins / Q000235:genetics; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D003574:Cytochrome c Group / Q000378:metabolism; D004195:Disease Models, Animal; D053200:Fas-Associated Death Domain Protein; D015316:Genetic Therapy; D006801:Humans; D020287:In Situ Nick-End Labeling; D008099:Liver / Q000737:chemistry / Q000473:pathology; D017093:Liver Failure / Q000209:etiology* / Q000473:pathology / Q000628:therapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008928:Mitochondria / Q000201:enzymology; D018124:Receptors, Tumor Necrosis Factor / Q000097:blood; D011994:Recombinant Proteins / Q000235:genetics; D013047:Specific Pathogen-Free Organisms; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000378:metabolism*; D019014:fas Receptor / Q000494:pharmacology
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D003574:Cytochrome c Group; C505533:FADD protein, human; C505534:Fadd protein, mouse; D053200:Fas-Associated Death Domain Protein; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; D014409:Tumor Necrosis Factor-alpha; D019014:fas Receptor; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases