Increased susceptibility of fat-laden Zucker-rat hepatocytes to bile acid-induced oncotic necrosis: an in vitro model of steatocholestasis.
Metabolic liver disorders cause chronic liver disease and liver failure in childhood. Many of these disorders share the histologic features of steatosis and cholestasis, or steatocholestasis. In this study we sought to (1) develop an in vitro model of steatocholestasis, (2) determine the mechanisms of cell death in this model, and (3) determine the role of mitochondrial disturbances in this model.


METHODS
Hepatocytes were isolated from 8-week-old obese (fa/fa) and lean Zucker rats. Cell suspensions were treated with glycochenodeoxycholic acid (GCDC), after which reactive oxygen species (ROS) generation, oncotic necrosis, apoptosis, and ATP content were assessed. Isolated liver mitochondria were exposed to GCDC and analyzed for ROS generation, mitochondrial membrane-permeability transition (MPT), and cytochrome c release. Oncotic necrosis was significantly increased and apoptosis reduced in fa/fa hepatocytes exposed to GCDC compared with that in lean hepatocytes. Necrosis occurred by way of an ROS- and MPT-dependent pathway. Basal and dynamic ATP content did not differ between fa/fa and lean hepatocytes. GCDC stimulated ROS generation, MPT, and cytochrome c release to a similar extent in purified mitochondria from both fa/fa and lean rats. These findings suggest that fat-laden hepatocytes favor a necrotic rather than an apoptotic cell death when exposed to low concentrations of bile acids. The protective effects of antioxidants and MPT blockers suggest novel therapeutic strategies for the treatment of steatocholestatic metabolic liver diseases.
Kobak
Gregory E
GE
Pediatric Liver Center and Liver Transplantation Program, Section of Pediatric Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, University of Colorado School of Medicine, Denver, USA.
Dahl
Rolf
R
Devereaux
Michael W
MW
Gumpricht
Eric
E
Traber
Maret
M
Doctor
R Brian
RB
Sokol
Ronald J
RJ
D000255:Adenosine Triphosphate / Q000032:analysis; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis; D001647:Bile Acids and Salts / Q000494:pharmacology*; D061945:Caspase Inhibitors; D002463:Cell Membrane Permeability / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005234:Fatty Liver; D005999:Glycochenodeoxycholic Acid / Q000494:pharmacology; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D009336:Necrosis; D009752:Nutritional Status; D009765:Obesity; D051381:Rats; D011924:Rats, Zucker; D017382:Reactive Oxygen Species / Q000378:metabolism
D000975:Antioxidants; D001647:Bile Acids and Salts; D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D017382:Reactive Oxygen Species; D005999:Glycochenodeoxycholic Acid; D000255:Adenosine Triphosphate; D045304:Cytochromes c