title: Dual role of tumor necrosis factor-alpha in hepatic ischemia-reperfusion injury: studies in tumor necrosis factor-alpha gene knockout mice.
abstract: Although hepatic ischemia-reperfusion (IR) injury is partially mediated by tumor necrosis factor-alpha (TNF), we recently found that low-dose TNF before IR is hepatoprotective. We examined the seemingly conflicting roles of TNF in mediating liver injury in a partial hepatic IR model using TNF gene knockout (TNF ko) mice to allow TNF replacement at specified times. Compared with wild-type mice, TNF ko mice exhibit minimal alanine aminotransferase release and few hepatonecrotic lesions during the early (time, 2 hours) and late (time, 24 hours) phases of IR. TNF ko mice differed from wild-type mice in that TNF ko mice exhibited no activation or induction of nuclear factor-kappa B, p38, cyclin D1, or proliferating cell nuclear antigen after IR. A single low-dose TNF injection 1 minute before the onset of hepatic ischemia restored hepatic IR injury in TNF ko mice. To clarify the importance of TNF for hepatoprotection, preconditioning (10 minutes of ischemia and 10 minutes of reperfusion) was performed before the onset of IR for TNF ko mice whose capacity to undergo IR injury had been restored by TNF replacement. Ischemic preconditioning failed to protect these mice from TNF-augmented IR injury; however, following the administration of intravenous TNF (1 microg per kg body weight, which mimics the early increase in hepatic and plasma TNF levels that is mobilized by ischemic preconditioning), significant hepatoprotection against both the early and late phases of TNF-augmented IR injury was observed. In conclusion, TNF appears to mediate both the early and late phases of liver injury in hepatic IR, but it also is an essential mediator of hepatoprotective effects brought about by ischemic preconditioning.
authors.affiliation: Storr Liver Unit, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, Australia.
authors.forename: Narci
authors.initials: N
authors.lastname: Teoh
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Field
authors.forename: Jaim
authors.initials: J
authors.lastname: Sutton
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Farrell
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism* / Q000494:pharmacology; D002455:Cell Division; D004195:Disease Models, Animal; D005260:Female; D019194:Ischemic Preconditioning; D008107:Liver Diseases / Q000473:pathology / Q000503:physiopathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D015427:Reperfusion Injury / Q000473:pathology / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics* / Q000378:metabolism* / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D000970:Antineoplastic Agents; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases