Rodent nutritional model of steatohepatitis: effects of endotoxin (lipopolysaccharide) and tumor necrosis factor alpha deficiency.
OBJECTIVE
Intestinal endotoxin (lipopolysaccharide) is thought to contribute to liver injury in both alcoholic and nonalcoholic steatohepatitis (NASH). Tumor necrosis factor alpha (TNFalpha) is an important mediator of this process and is considered central to the inflammatory response in NASH. This study aimed to investigate the effects of lipopolysaccharide on liver injury in the methionine choline deficient (MCD) nutritional model of NASH, and to determine if TNFalpha is required for the development of steatohepatitis in this model.


METHODS
Male C57/BL6 mice received a MCD diet for 4 weeks, whilst a control group received an identical diet supplemented with 0.2% choline bitartrate and 0.3% methionine. At 4 weeks, mice received either an intraperitoneal injection of lipopolysaccharide (0.5 microg/g body mass) or sterile saline, and were killed 24 h thereafter. In a separate study, TNFalpha knockout and wild type C57BL/6 mice received either MCD or control diets for 4 weeks. Serum transaminase levels, liver histology (steatosis, inflammation and apoptosis), hepatic triglyceride concentration and hepatic lipid peroxidation products (conjugated dienes, lipid hydroperoxides and thiobarbituric reactive substances, free and total) were evaluated.


RESULTS
Intraperitoneal administration of lipopolysaccharide augmented serum alanine aminotransferase (ALT) levels (P<0.02), hepatic inflammation (P<0.025), apoptosis (P<0.01) and free thiobarbituric acid reactive substances (P<0.025) in MCD mice. TNFalpha knockout mice fed the MCD diet developed steatohepatitis with histological and biochemical changes similar to those seen in wild type counterparts.


CONCLUSIONS
Lipopolysaccharide augments liver injury in MCD mice, and TNFalpha is not required for the development of steatohepatitis in MCD mice.
Kirsch
Richard
R
Department of Anatomical Pathology, Cape Heart Center and Medical Research Council, Cape Town, South Africa. rich@chempath.uct.ac.za
Clarkson
Vivian
V
Verdonk
Robert C
RC
Marais
Adrian D
AD
Shephard
Enid G
EG
Ryffel
Bernard
B
de la M Hall
Pauline
P
D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001835:Body Weight; D002796:Choline Deficiency / Q000097:blood / Q000150:complications / Q000473:pathology*; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000097:blood / Q000139:chemically induced / Q000473:pathology*; D015227:Lipid Peroxidation; D008070:Lipopolysaccharides / Q000008:administration & dosage*; D008099:Liver / Q000201:enzymology / Q000473:pathology; D008297:Male; D008715:Methionine / Q000172:deficiency; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D051381:Rats; D014280:Triglycerides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000172:deficiency* / Q000235:genetics
D008070:Lipopolysaccharides; D014280:Triglycerides; D014409:Tumor Necrosis Factor-alpha; D008715:Methionine; D000410:Alanine Transaminase