Lipopolysaccharide triggered TNF-alpha-induced hepatocyte apoptosis in a murine non-alcoholic steatohepatitis model.
OBJECTIVE
Endogenous gut-derived bacterial endotoxins have been implicated as an important cofactor in the pathogenesis of liver injury, although their contribution to the progression of non-alcoholic steatohepatitis (NASH) remains unclear.


METHODS
Male C57BL/6 mice were fed a methionine-choline-deficient (MCD) diet or a standard diet for 17 days, following which they were injected with lipopolysaccharide (LPS) intraperitoneally and sacrificed after 6h. In an in vitro experiment, RAW264.7 cells, a mouse macrophage cell line, and primary mouse hepatocytes were co-treated with hydrogen peroxide (H(2)O(2)) and LPS or tumour necrosis factor (TNF)-alpha.


RESULTS
Compared to the control mice, LPS treatment significantly increased hepatic TNF-alpha production in MCD mice. LPS also significantly increased TUNEL-positive cells, which were especially observed in the perivenular area. The apoptotic change was inhibited by co-treatment with a neutralizing anti-mouse TNF receptor antibody or pentoxifylline. In an in vitro experiment, treatment with H(2)O(2) synergistically enhanced LPS-induced TNF-alpha production in RAW264.7 cells, accompanied by an up-regulation of CD14 mRNA. Moreover, co-treatment with TNF-alpha- and H(2)O(2)-induced apoptosis in primary hepatocytes, although neither TNF-alpha nor H(2)O(2) could do so independently.


CONCLUSIONS
LPS up-regulated TNF-alpha production, which induced hepatocyte apoptosis in a murine NASH model. LPS may play a key role in the pathogenesis of NASH.
Kudo
Hiroshi
H
Third Department of Internal Medicine, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
Takahara
Terumi
T
Yata
Yutaka
Y
Kawai
Kengo
K
Zhang
Wei
W
Sugiyama
Toshiro
T
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000209:etiology / Q000473:pathology*; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology; D006861:Hydrogen Peroxide / Q000633:toxicity; D048031:JNK Mitogen-Activated Protein Kinases / Q000502:physiology; D018950:Lipopolysaccharide Receptors / Q000235:genetics; D008070:Lipopolysaccharides / Q000633:toxicity*; D048848:MAP Kinase Kinase Kinase 5 / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017382:Reactive Oxygen Species / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology*
D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D017382:Reactive Oxygen Species; D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D048848:MAP Kinase Kinase Kinase 5; C482859:Map3k5 protein, mouse; D053148:Caspase 3