title: Lopimune-induced mitochondrial toxicity is attenuated by increased uncoupling protein-2 level in treated mouse hepatocytes.
abstract: Although the protease inhibitor (PI) Lopimune has proven to be effective, no studies have examined the side effects of Lopimune on mitochondrial bioenergetics in hepatocytes. The objective of the present study is to evaluate mitochondrial respiration, production of reactive oxygen species (ROS) and expression of uncoupling protein-2 (UCP2) in mouse hepatocytes following Lopimune administration. Mitochondria were extracted from mouse liver using differential centrifugation and hepatocytes were isolated by the collagenase perfusion procedure. Mitochondrial respiration was measured using a Rank Brothers oxygen electrode. ROS production in hepatocytes was monitored by flow cytometry using a 2',7'-dichlorofluorescin diacetate probe and UCP2 protein expression was detected by Western blotting. We found that Lopimune induced a significant decrease of approximately 30% in the respiratory control ratio (RCR) starting from day 4 until day 9 of treatment. This decrease was due to an increase in state 4 respiration, reflecting an increase in mitochondrial proton leak. State 2 and state 3 respirations were not affected. Moreover, ROS production significantly increased by about 2-fold after day 1 of treatment and decreased after day 3, returning to the resting level on day 5. Interestingly, UCP2 which is absent from control hepatocytes, was expressed starting from day 4 of treatment. Our findings indicate that Lopimune-induced proton leak, mediated by UCP2, may represent a response to inhibit the production of ROS as a negative feedback regulatory mechanism. These results imply a potential involvement of UCP2 in the regulation of oxidative stress and add new insights into the understanding of mitochondrial toxicity induced by PIs.
authors.affiliation: Faculty of Medicine and Medical Sciences, University of Balamand, P.O. Box 100, Tripoli, Lebanon.
authors.forename: Sara
authors.initials: S
authors.lastname: El Hoss
authors.affiliation: Faculty of Medicine and Medical Sciences, University of Balamand, P.O. Box 100, Tripoli, Lebanon.
authors.forename: Georges M
authors.initials: GM
authors.lastname: Bahr
authors.affiliation: Faculty of Medicine and Medical Sciences, University of Balamand, P.O. Box 100, Tripoli, Lebanon karim.echtay@balamand.edu.lb.
authors.forename: Karim S
authors.initials: KS
authors.lastname: Echtay
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D004338:Drug Combinations; D006153:Guanosine Diphosphate / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000009:adverse effects / Q000494:pharmacology*; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007473:Ion Channels / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D007700:Kinetics; D061466:Lopinavir / Q000009:adverse effects / Q000494:pharmacology*; D008807:Mice, Inbred BALB C; D008930:Mitochondria, Liver / Q000187:drug effects* / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000819:agonists* / Q000037:antagonists & inhibitors / Q000378:metabolism; D010085:Oxidative Phosphorylation / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D019438:Ritonavir / Q000009:adverse effects / Q000494:pharmacology*; D000071246:Uncoupling Protein 2
chemical_list: D004338:Drug Combinations; D017320:HIV Protease Inhibitors; D007473:Ion Channels; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; C000604390:Ucp2 protein, mouse; D000071246:Uncoupling Protein 2; C558899:lopinavir-ritonavir drug combination; D006153:Guanosine Diphosphate; D061466:Lopinavir; D019438:Ritonavir
keywords: Lopimune; mitochondria; respiratory control ratio; superoxide anion; uncoupling protein 2 (UCP2)