Inhibition of inhibitor of kappaB kinases stimulates hepatic stellate cell apoptosis and accelerated recovery from rat liver fibrosis.
OBJECTIVE
Resolution of liver fibrosis is associated with clearance of hepatic myofibroblasts by apoptosis; development of strategies that promote this process in a selective way is therefore important. The aim of this study was to determine whether the inhibitor of kappaB kinase suppressor sulfasalazine stimulates hepatic myofibroblast apoptosis and recovery from fibrosis.


METHODS
Hepatic myofibroblasts were generated by culture activation of rat and human hepatic stellate cells. Fibrosis was established in rat livers by chronic injury with carbon tetrachloride followed by recovery with or without sulfasalazine (150 mg/kg) treatment.


RESULTS
Treatment of hepatic stellate cells with sulfasalazine (0.5-2.0 mmol/L) induced apoptosis of activated rat and human hepatic stellate cells. A single in vivo administration of sulfasalazine promoted accelerated recovery from fibrosis as assessed by improved fibrosis score, selective clearance of smooth muscle alpha-actin-positive myofibroblasts, reduced hepatic procollagen I and tissue inhibitor of metalloproteinase 1 messenger RNA expression, and increased matrix metalloproteinase 2 activity. Mechanistic studies showed that sulfasalazine selectively blocks nuclear factor-kappaB-dependent gene transcription, inhibits hepatic stellate cell expression of Gadd45beta, stimulates phosphorylation of Jun N-terminal kinase 2, and promotes apoptosis by a mechanism that is prevented by the Jun N-terminal kinase inhibitor SP600125. As further evidence for a survival role for the inhibitor of kappaB kinase/nuclear factor-kappaB pathway in activated hepatic stellate cells, a highly selective cell-permeable peptide inhibitor of kappaB kinase activation also stimulated hepatic stellate cell apoptosis via a Jun N-terminal kinase-dependent mechanism.


CONCLUSIONS
Inhibition of the inhibitor of kappaB kinase/nuclear factor-kappaB pathway is sufficient to increase the rate at which activated hepatic stellate cells undergo apoptosis both in vitro and in vivo, and drugs that selectively target inhibitor of kappaB kinase have potential as antifibrotics.
Oakley
Fiona
F
Liver Group, Division of Infection, Inflammation and Repair, University of Southampton School of Medicine, General Hospital, Southampton SO16 6YD, England, UK.
Meso
Muriel
M
Iredale
John P
JP
Green
Karen
K
Marek
Carylyn J
CJ
Zhou
Xiaoying
X
May
Michael J
MJ
Millward-Sadler
Harry
H
Wright
Matthew C
MC
Mann
Derek A
DA
D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D018929:Cell Culture Techniques; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005765:Gastrointestinal Agents / Q000494:pharmacology*; D006801:Humans; D008099:Liver / Q000166:cytology / Q000187:drug effects; D008103:Liver Cirrhosis / Q000188:drug therapy*; D008297:Male; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects; D012460:Sulfasalazine / Q000494:pharmacology*; D000097782:NF-kappaB-Inducing Kinase
D000873:Anthracenes; D004791:Enzyme Inhibitors; D005765:Gastrointestinal Agents; D017346:Protein Serine-Threonine Kinases; D012460:Sulfasalazine; D000097782:NF-kappaB-Inducing Kinase; C432165:pyrazolanthrone