title: TNF tolerance and cytotoxicity in the liver: the role of interleukin-1beta, inducible nitric oxide-synthase and heme oxygenase-1 in D-galactosamine-sensitized mice.
abstract: OBJECTIVE
  Pretreatment with tumor necrosis factor (TNF)-alpha induces tolerance towards itself in experimental liver injury.
  
  
  METHODS
  To study mechanisms of TNF tolerance we used knockout mice for either TNF-receptor-2 (TNFR-2), inducible nitric oxide (NO)-synthase (iNOS) or caspase-1 (ICE) or inhibited heme oxygenase-1 (HO-1) by treatment with zinc-protoporphyrin 9. Liver damage was induced by administration of TNF to mice sensitized with D-galactosamine (GalN). Tolerance was induced by pretreatment with low doses of TNF.
  
  
  METHODS
  Severity of liver injury was assessed by determination of plasma transaminases and apoptosis. Time courses of intra-hepatic iNOS, interleukin-1beta (IL-1beta) and HO-1 expression after TNF treatment were measured by reverse transcription polymerase chain reaction (RT-PCR). TNF-receptor-1 (TNFR-1) expression was determined by immunofluorescent staining.
  
  
  RESULTS
  TNF-pretreatment did not affect TNFR-1 expression in the liver and resulted in time dependent up-regulation of iNOS, IL-1beta and HO-1. TNF- pretreated TNFR-2, iNOS or ICE knockout mice were as sensitive towards GalN/TNF as the wild type, while mice with impaired HO-1 activity were even more sensitive, but tolerance was inducible in all TNF-pretreated mice.
  
  
  CONCLUSIONS
  TNF tolerance towards GalN/TNF treatment is mediated by TNFR-1. IL-1beta, iNOS and HO-1 neither mediated TNF-tolerance nor TNF cytotoxicity.
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, University of Erlangen-Nuremberg, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Sass
authors.forename: K
authors.initials: K
authors.lastname: Koerber
authors.forename: G
authors.initials: G
authors.lastname: Tiegs
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000187:drug effects; D000970:Antineoplastic Agents / Q000494:pharmacology* / Q000633:toxicity; D056486:Chemical and Drug Induced Liver Injury / Q000473:pathology*; D053938:DNA Fragmentation / Q000187:drug effects; D004361:Drug Tolerance; D005688:Galactosamine / Q000633:toxicity*; D006419:Heme Oxygenase (Decyclizing) / Q000502:physiology*; D051547:Heme Oxygenase-1; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000502:physiology*; D008099:Liver / Q000187:drug effects / Q000473:pathology*; D008297:Male; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D019001:Nitric Oxide Synthase / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000096:biosynthesis; D018124:Receptors, Tumor Necrosis Factor / Q000187:drug effects; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology* / Q000633:toxicity
chemical_list: D015703:Antigens, CD; D000970:Antineoplastic Agents; D007375:Interleukin-1; D008565:Membrane Proteins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; D014409:Tumor Necrosis Factor-alpha; D005688:Galactosamine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse