title: Anandamide induces necrosis in primary hepatic stellate cells.
abstract: The endogenous cannabinoid anandamide (AEA) is a lipid mediator that blocks proliferation and induces apoptosis in many cell types. Although AEA levels are elevated in liver fibrosis, its role in fibrogenesis remains unclear. This study investigated effects of AEA in primary hepatic stellate cells (HSCs). Anandamide blocked HSC proliferation at concentrations of 1 to 10 micromol/L but did not affect HSC proliferation or activation at nanomolar concentrations. At higher concentrations (25-100 micromol/L), AEA rapidly and dose-dependently induced cell death in primary culture-activated and in vivo-activated HSCs, with over 70% cell death after 4 hours at 25 micromol/L. In contrast to treatment with Fas ligand or gliotoxin, AEA-mediated death was caspase independent and showed typical features of necrosis such as rapid adenosine triphosphate depletion and propidium iodide uptake. Anandamide-induced reactive oxygen species (ROS) formation, and an increase in intracellular Ca(2+). Pretreatment with the antioxidant glutathione or Ca(2+)-chelation attenuated AEA-induced cell death. Although the putative endocannabinoid receptors CB1, CB2, and VR1 were expressed in HSCs, specific receptor blockade failed to block cell death. Depletion of membrane cholesterol by methyl-beta-cyclodextrin inhibited AEA binding, blocked ROS formation and intracellular Ca(2+)-increase, and prevented cell death. In primary hepatocytes, AEA showed significantly lower binding and failed to induce cell death even after prolonged treatment. In conclusion, AEA efficiently induces necrosis in activated HSCs, an effect that depends on membrane cholesterol and a subsequent increase in intracellular Ca(2+) and ROS. The anti-proliferative effects and the selective killing of HSCs, but not hepatocytes, indicate that AEA may be used as a potential anti-fibrogenic tool.
authors.affiliation: Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, NY 10032, USA.
authors.forename: Sören V
authors.initials: SV
authors.lastname: Siegmund
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uchinami
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Osawa
authors.forename: David A
authors.initials: DA
authors.lastname: Brenner
authors.forename: Robert F
authors.initials: RF
authors.lastname: Schwabe
mesh_terms: D000818:Animals; D017209:Apoptosis; D001095:Arachidonic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology*; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D063388:Endocannabinoids; D022781:Hepatocytes / Q000187:drug effects* / Q000473:pathology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology; D008297:Male; D016328:NF-kappa B / Q000378:metabolism; D009336:Necrosis; D053284:Polyunsaturated Alkamides; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D011955:Receptors, Drug / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; C469526:Cnr2 protein, rat; D063388:Endocannabinoids; D016328:NF-kappa B; D053284:Polyunsaturated Alkamides; D017382:Reactive Oxygen Species; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; D011955:Receptors, Drug; D014409:Tumor Necrosis Factor-alpha; D002784:Cholesterol; D048031:JNK Mitogen-Activated Protein Kinases; D002118:Calcium; C078814:anandamide