title: Therapeutic approach to regulate innate immune response by Toll-like receptor 4 antagonist E5564 in rats with D-galactosamine-induced acute severe liver injury.
abstract: OBJECTIVE
  Toll-like receptor 4 (TLR4) is a transmembrane protein, existing mainly in macrophages, such as Kupffer cells of the liver. It plays an important role in recognizing and mediating macrophage activation and pro-inflammatory cytokine release. Activation of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-alpha is pivotal in the progression of liver injury. Gut-derived endotoxin has been considered to play an important role in the development and progression of a D-galactosamine (GalN)-induced acute severe liver injury (ALI) model. E5564, a synthetic analog of the lipid A component of endotoxin, inhibits endotoxin-stimulated inflammation and is under study for patients with sepsis. In this study, we seek to explore the effect of TLR4 antagonist E5564 on GalN-induced ALI in rats.
  
  
  METHODS
  ALI was induced in male Wistar rats by the i.p. injection of 1 g/kg bodyweight of GalN and immediately after GalN injection they were treated with an i.v. injection of 3 mg/kg bodyweight of E5564. At 24 h after GalN injection with or without E5564, serum levels of total bilirubin (T.Bil), alanine aminotransferase (ALT) and TNF-alpha were analyzed. Expression levels of TNF-alpha, TLR4 and CD14 mRNA in the whole liver of rats was detected by reverse transcription polymerase chain reaction analysis.
  
  
  RESULTS
  The i.v. injection of E5564 reduced the elevation of serum T.Bil, ALT and TNF-alpha levels in rats treated with GalN. The expression level of TNF-alpha mRNA in the whole liver, which was increased at 24 h after GalN injection, was also reduced by i.v. injection of E5564.
  
  
  CONCLUSIONS
  TLR4 antagonist E5564 reduced GalN-induced ALI in rats. It may contribute to the treatment of acute liver failure through blocking endotoxin-induced TNF-alpha overproduction of macrophages.
authors.affiliation: Third Department of Internal Medicine, Nara Medical University, Kashihara, Nara, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kitazawa
authors.forename: Tatsuhiro
authors.initials: T
authors.lastname: Tsujimoto
authors.forename: Hideto
authors.initials: H
authors.lastname: Kawaratani
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Fukui
mesh_terms: D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D001219:Aspartate Aminotransferases / Q000378:metabolism; D001663:Bilirubin / Q000378:metabolism; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D005688:Galactosamine; D008050:Lipid A / Q000031:analogs & derivatives* / Q000494:pharmacology; D017114:Liver Failure, Acute / Q000139:chemically induced / Q000188:drug therapy*; D008297:Male; D012313:RNA / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051197:Toll-Like Receptor 4 / Q000037:antagonists & inhibitors*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: C404742:E5564; D008050:Lipid A; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; D012313:RNA; D005688:Galactosamine; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase; D001663:Bilirubin