Oxidative stress, KLF6 and transforming growth factor-beta up-regulation differentiate non-alcoholic steatohepatitis progressing to fibrosis from uncomplicated steatosis in rats.
OBJECTIVE
Pathogenesis of non-alcoholic steatohepatitis (NASH) remains poorly understood. Cytochrome P450 2E1 (CYP 2E1), cytokines, oxidative stress and activation of hepatic stellate cells seem to play a role in this process. The aim was to determine the potential implication of these factors in the progression from uncomplicated steatosis to steatohepatitis with progressive fibrosis.


METHODS
Animals were fed a standard diet, a 5% orotic acid-diet (OA) developing hepatic steatosis, or the methionine-choline deficient (MCD) diet inducing steatohepatitis for 2 and 6 weeks. Lipid peroxidation, CYP 2E1 expression and activity, expression of UCP-2, interleukin (IL)-6, transforming growth factor (TGF)beta1, KLF6 mRNAs, and activation of hepatic stellate cells were examined by gas chromatography, high-performance liquid chromatography, Western blotting, quantitative polymerase chain reaction and immunohistochemistry.


RESULTS
Lipid peroxidation increased in the MCD model whereas only minor changes occurred in the OA model. KLF6 and TGFbeta1 mRNAs were selectively up-regulated in MCD animals. Stellate cell activation, inflammation and collagen deposition only occurred in the MCD group. CYP 2E1 expression and activity increased in the OA group while both decreased in MCD animals. UCP-2 and IL-6 mRNA increased in both groups.


CONCLUSIONS
In the context of steatosis, lipid peroxidation is associated with inflammation and stellate cell activation with concomitant increase in TGFbeta1 production, possibly through up-regulation of KLF6.
Stärkel
Peter
P
Laboratory of Gastroenterology, St. Luc University Hospital, Université Catholique de Louvain, Avenue Hippocrate 10, 1200 Brussels, Belgium.
Sempoux
Christine
C
Leclercq
Isabelle
I
Herin
Michel
M
Deby
C
C
Desager
Jean-Pierre
JP
Horsmans
Yves
Y
D000199:Actins / Q000378:metabolism; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D003937:Diagnosis, Differential; D018450:Disease Progression; D005234:Fatty Liver / Q000150:complications* / Q000175:diagnosis* / Q000473:pathology; D007150:Immunohistochemistry; D015850:Interleukin-6 / Q000235:genetics; D007473:Ion Channels; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D050356:Lipid Metabolism; D015227:Lipid Peroxidation; D008099:Liver / Q000378:metabolism; D008103:Liver Cirrhosis / Q000209:etiology*; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics; D008862:Microsomes, Liver / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics; D009130:Muscle, Smooth / Q000378:metabolism; D018384:Oxidative Stress; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*; D053773:Transforming Growth Factor beta1; D000071246:Uncoupling Protein 2; D015854:Up-Regulation
D000199:Actins; D015850:Interleukin-6; D007473:Ion Channels; C491357:Klf6 protein, rat; D000075723:Kruppel-Like Factor 6; D051741:Kruppel-Like Transcription Factors; D026901:Membrane Transport Proteins; D024101:Mitochondrial Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; C508962:Tgfb1 protein, rat; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; C000604391:Ucp2 protein, rat; D000071246:Uncoupling Protein 2; D003577:Cytochrome P-450 Enzyme System