NFkappaB inhibition decreases hepatocyte proliferation but does not alter apoptosis in obstructive jaundice

Cholestasis activates nuclear factor kappa B (NFkappaB), which is involved in both hepatocyte proliferation and apoptosis, depending on the cellular microenvironment. We hypothesized that NFkappaB inhibition would decrease hepatocyte proliferation and potentiate hepatocyte apoptosis in a rat model of extrahepatic biliary obstruction.

To determine if NFkappaB inhibition concomitantly decreases hepatocyte proliferation and increases apoptosis in obstructive jaundice.

Male Sprague-Dawley rats underwent either sham operation or bile-duct ligation (BDL) combined with portal vein injection of vehicle or 6 x 10(9) particles of an adenovirus carrying either the control luciferase or the IkappaB super-repressor (AdIkappaBSR) transgenes. Liver was harvested 3, 5, and 7 days after sham operation or BDL, and immunohistochemistry for proliferating cell nuclear antigen and terminal dUTP nick end-labeling was performed for detection of DNA synthesis and apoptosis, respectively.

Increased serum total bilirubin and hematoxylin and eosin-stained liver sections confirmed cholestasis in BDL animals. Western blot analysis demonstrated IkappaBSR protein expression in AdIkappaBSR-infected animals only. At day 7, NFkappaB inhibition decreased hepatocyte DNA synthesis in BDL rats compared to both adenovirus carrying the control luciferase and vehicle-treated controls. Apoptosis was increased in BDL vehicle-treated animals compared to sham-operation animals, but NFkappaB inhibition did not alter hepatocyte apoptosis in the BDL group.

In obstructive cholestasis, NFkappaB is required for hepatocyte proliferation, but does not augment apoptosis.