title: Lipopolysaccharide precipitates hepatic encephalopathy and increases blood-brain barrier permeability in mice with acute liver failure.
abstract: OBJECTIVE
  Acute liver failure (ALF) is frequently complicated by infection leading to precipitation of central nervous system complications such as hepatic encephalopathy (HE) and increased mortality. There is evidence to suggest that when infection occurs in ALF patients, the resulting pro-inflammatory mechanisms may be amplified that could, in turn, have a major impact on blood-brain barrier (BBB) function. The aim of this study was to investigate the role of endotoxemia on the progression of encephalopathy in relation to BBB permeability during ALF.
  
  
  METHODS
  Adult male C57-BL6 mice with ALF resulting from azoxymethane-induced toxic liver injury were administered trace amounts of the endotoxin component lipopolysaccharide (LPS). Effects on the magnitude of the systemic inflammatory response, liver pathology and BBB integrity were measured as a function of progression of HE, defined as time to loss of corneal reflex (coma).
  
  
  RESULTS
  Lipopolysaccharide caused additional two- to seven-fold (P < 0.001) increases in circulating pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), worsening liver pathology and associated increases of circulating transaminases as well as increased hyperammonaemia consistent with a further loss of viable hepatocytes. LPS treatment of ALF mice led to a rapid precipitation of hepatic coma and the BBB became permeable to the 25-kDa protein immunoglobulin G (IgG). This extravasation of IgG was accompanied by ignificant up-regulation of matrix metalloproteinase-9 (MMP-9), an endopeptidase known to modulate opening of the BBB in a wide range of neurological disorders.
  
  
  CONCLUSIONS
  These findings represent the first direct evidence of inflammation-related BBB permeability changes in ALF.
authors.affiliation: Neuroscience Research Unit, Saint-Luc Hospital, CRCHUM, Montreal, QC, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Chastre
authors.forename: Mireille
authors.initials: M
authors.lastname: Bélanger
authors.forename: Bich N
authors.initials: BN
authors.lastname: Nguyen
authors.forename: Roger F
authors.initials: RF
authors.lastname: Butterworth
mesh_terms: D000641:Ammonia / Q000097:blood; D000818:Animals; D001397:Azoxymethane / Q000633:toxicity; D001812:Blood-Brain Barrier / Q000187:drug effects*; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D006501:Hepatic Encephalopathy / Q000503:physiopathology*; D007249:Inflammation / Q000473:pathology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008099:Liver / Q000473:pathology*; D017114:Liver Failure, Acute / Q000473:pathology*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010539:Permeability; D000637:Transaminases / Q000097:blood
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D000641:Ammonia; D000637:Transaminases; D020780:Matrix Metalloproteinase 9; C501830:Mmp9 protein, mouse; D001397:Azoxymethane
keywords: acute liver failure; azoxymethane; blood-brain barrier; endotoxemia; immunoglobulin G extravasation; lipopolysaccharide; matrix metalloproteinase-9; pro-inflammatory cytokines; systemic inflammatory response