NF-kappaB is a critical regulator of the survival of rodent and human hepatic myofibroblasts.
OBJECTIVE
Hepatic myofibroblast activation during injury causes deposition of extracellular matrix within the liver and promotes development of fibrosis. Hepatic myofibroblast apoptosis is associated with remodelling of fibrotic extracellular matrix and regression of fibrosis. Previous work showed that inhibition of constitutive NF-kappaB signaling promotes hepatic myofibroblast apoptosis and resolution of fibrosis in rodent models. However, to date agents used to target constitutive NF-kappaB transcriptional activity in hepatic myofibroblasts have been relatively non-specific with potential for off-target effects that may complicate data interpretation. Likewise, rat chronic liver disease models may not accurately recapitulate the activation of human hepatic myofibroblasts.


METHODS
We used a mutant recombinant IkappaBalpha super-repressor fused to the HIV-TAT domain to specifically target NF-kappaB signaling in hepatic myofibroblasts. Inhibition of NF-kappaB activity was measured using reporter assay. Apoptosis of hepatic myofibroblasts was assessed by morphological changes, cleavage of the PARP-1 protein and Caspase 3 activation.


RESULTS
TAT-IkappaBalphaSR reduced NF-kappaB dependent transcription, Bcl-2 expression and promoted Jun-N-terminal kinase-dependent apoptosis in human and rat hepatic myofibroblasts.


CONCLUSIONS
These data highlight the conserved role of NF-kappaB during fibrogenesis. Our data validate the use of rodent models for pre-clinical testing of NF-kappaB inhibitors as anti-fibrotics and stimulators of fibrotic extracellular matrix remodelling.
Watson
Martha R
MR
Liver Research Group, Institute of Cellular Medicine, Newcastle University, Newcastle NE2 4HH, UK.
Wallace
Karen
K
Gieling
Roben G
RG
Manas
Derek M
DM
Jaffray
Ellis
E
Hay
Ronald T
RT
Mann
Derek A
DA
Oakley
Fiona
F
D000328:Adult; D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002470:Cell Survival / Q000235:genetics; D004195:Disease Models, Animal; D018450:Disease Progression; D004591:Electrophoresis, Polyacrylamide Gel; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D019254:Genes, bcl-2 / Q000235:genetics; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D008103:Liver Cirrhosis / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008106:Liver Cirrhosis, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D016328:NF-kappa B / Q000235:genetics* / Q000378:metabolism; D012313:RNA / Q000235:genetics*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation
D016328:NF-kappa B; D012313:RNA; D048031:JNK Mitogen-Activated Protein Kinases