The endocannabinoid 2-arachidonoyl glycerol induces death of hepatic stellate cells via mitochondrial reactive oxygen species.
The endocannabinoid system is an important regulator of hepatic fibrogenesis. In this study, we determined the effects of 2-arachidonoyl glycerol (2-AG) on hepatic stellate cells (HSCs), the main fibrogenic cell type in the liver. Culture-activated HSCs were highly susceptible to 2-AG-induced cell death with >50% cell death at 10 microM after 18 h of treatment. 2-AG-induced HSC death showed typical features of apoptosis such as PARP- and caspase 3-cleavage and depended on reactive oxygen species (ROS) formation. Confocal microscopy revealed mitochondria as primary site of ROS production and demonstrated mitochondrial depolarization and increased mitochondrial permeability after 2-AG treatment. 2-AG-induced cell death was independent of cannabinoid receptors but required the presence of membrane cholesterol. Primary hepatocytes were resistant to 2-AG-induced ROS induction and cell death but became susceptible after GSH depletion suggesting antioxidant defenses as a critical determinant of 2-AG sensitivity. Hepatic levels of 2-AG were significantly elevated in two models of experimental fibrogenesis and reached concentrations that are sufficient to induce death in HSCs. These findings suggest that 2-AG may act as an antifibrogenic mediator in the liver by inducing cell death in activated HSCs but not hepatocytes.
Siegmund
Sören V
SV
Department of Medicine, Columbia University, College of Physicians and Surgeons, New York, New York, USA.
Qian
Ting
T
de Minicis
Samuele
S
Harvey-White
Judith
J
Kunos
George
G
Vinod
K Y
KY
Hungund
Basalingappa
B
Schwabe
Robert F
RF
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001095:Arachidonic Acids / Q000494:pharmacology*; D015153:Blotting, Western; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D063388:Endocannabinoids; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005355:Fibrosis; D005989:Glycerides / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D008099:Liver / Q000187:drug effects / Q000293:injuries / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D043884:Receptor, Cannabinoid, CB1 / Q000235:genetics / Q000502:physiology; D043885:Receptor, Cannabinoid, CB2 / Q000235:genetics / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D063388:Endocannabinoids; D005989:Glycerides; D017382:Reactive Oxygen Species; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; C094503:glyceryl 2-arachidonate; D011065:Poly(ADP-ribose) Polymerases; D020169:Caspases