title: Endogenous danger signals trigger hepatic ischemia/reperfusion injury through toll-like receptor 4/nuclear factor-kappa B pathway.
abstract: BACKGROUND
  Restoration of blood flow to the ischemic liver lobes may paradoxically exacerbate tissue injury, which is called hepatic ischemia/reperfusion injury (IRI). Toll-like receptor 4 (TLR4), expressed on several liver cell types, and the nuclear factor-kappa B (NF-kappaB) signaling pathway are crucial to mediating hepatic inflammatory response. Because IRI is essentially a kind of profound acute inflammatory reaction evoked by many kinds of danger signals, we investigated TLR4/NF-kappaB signaling pathway activation in a murine model of partial hepatic IRI.
  
  
  METHODS
  Wild-type mice (WT, C3H/HeN) or TLR4 mutant mice (C3H/HeJ) were subjected to 45 minutes of partial hepatic ischemia followed by 1 hour, 3 hours of reperfusion. Sham group accepted the same procedure without the obstruction of blood supply. At the end of reperfusion, the compromise of liver function and the histological change of liver sections were measured as the severity of liver injury. The level of endotoxin in the portal vein was measured by limulus assay. NF-kappaB activation was determined by electrophoretic mobility shift assay (EMSA). The levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in systemic blood after hepatic IRI were assessed by enzyme-linked immunosorbent assay (ELISA).
  
  
  RESULTS
  The compromise of liver function and the morphological injuries in mutant mice were relieved more markedly than those in WT mice after partial hepatic IRI. NF-kappaB activation in WT mice was stronger than that in TLR4 mutant mice, and both were stronger than those in the sham operated mice (P < 0.01). Endotoxin in each group was undetectable. The levels of TNF-alpha and IL-1beta in systemic blood were elevated in both strains, but lower in the sham operated group. These mediators were significantly decreased in TLR4 mutant mice compared with those in WT mice (P < 0.01).
  
  
  CONCLUSIONS
  The TLR4/NF-kappaB signaling pathway may mediate hepatic IRI triggered by endogenous danger signals. Inhibition of the TLR4/NF-kappaB pathway may be a potential therapeutic target for attenuating ischemia/reperfusion-induced tissue damage in some clinical settings.
authors: Department of Medical Biology, Tongji Medical College Affiliated to Huazhong University of Science and Technology, Wuhan 430030, China.
authors: Hui
authors: H
authors: Wang
authors: Zhuo-ya
authors: ZY
authors: Li
authors: He-shui
authors: HS
authors: Wu
authors: Yang
authors: Y
authors: Wang
authors: Chun-fang
authors: CF
authors: Jiang
authors: Qi-chang
authors: QC
authors: Zheng
authors: Jin-xiang
authors: JX
authors: Zhang
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D053583:Interleukin-1beta / Q000096:biosynthesis; D008099:Liver / Q000098:blood supply*; D051379:Mice; D008809:Mice, Inbred C3H; D016328:NF-kappa B / Q000502:physiology*; D015427:Reperfusion Injury / Q000209:etiology*; D015398:Signal Transduction / Q000502:physiology*; D051197:Toll-Like Receptor 4 / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D053583:Interleukin-1beta; D016328:NF-kappa B; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D000410:Alanine Transaminase