bongkrekic-acid and Chemical-and-Drug-Induced-Liver-Injury

Leflunomide, an anti-inflammatory drug used for the treatment of rheumatoid arthritis, has been marked with a black box warning regarding an increased risk of liver injury. The active metabolite of leflunomide, A771726, which also carries a boxed warning about potential hepatotoxicity, has been marketed as teriflunomide for the treatment of relapsing multiple sclerosis. Thus far, however, the mechanism of liver injury associated with the two drugs has remained elusive. In this study, cytotoxicity assays showed that ATP depletion and subsequent LDH release were induced in a time- and concentration-dependent manner by leflunomide in HepG2 cells, and to a lesser extent, by A77 1726. The decline of cellular ATP levels caused by leflunomide was dramatically exacerbated when galactose was substituted for glucose as the sugar source, indicating a potential mitochondrial liability of leflunomide. By measuring the activities of immuno-captured mitochondrial oxidative phosphorylation (OXPHOS) complexes, we found that leflunomide and A77 1726 preferentially targeted complex V (F

Topics: Adenosine Triphosphate; Anti-Inflammatory Agents, Non-Steroidal; Bongkrekic Acid; Chemical and Drug Induced Liver Injury; Endoplasmic Reticulum Stress; Galactose; Glucose; Hep G2 Cells; Humans; Isoxazoles; L-Lactate Dehydrogenase; Leflunomide; Membrane Potential, Mitochondrial; Mitochondria, Liver; Mitochondrial Diseases; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Oxidative Phosphorylation

Sertraline, a selective serotonin reuptake inhibitor, has been used for the treatment of depression. Although it is generally considered safe, cases of sertraline-associated liver injury have been documented; however, the possible mechanism of sertraline-associated hepatotoxicity is entirely unknown. Here, we report that mitochondrial impairment may play an important role in liver injury induced by sertraline. In mitochondria isolated from rat liver, sertraline uncoupled mitochondrial oxidative phosphorylation and inhibited the activities of oxidative phosphorylation complexes I and V. Additionally, sertraline induced Ca(2+)-mediated mitochondrial permeability transition (MPT), and the induction was prevented by bongkrekic acid (BA), a specific MPT inhibitor targeting adenine nucleotide translocator (ANT), implying that the MPT induction is mediated by ANT. In freshly isolated rat primary hepatocytes, sertraline rapidly depleted cellular adenosine triphosphate (ATP) and subsequently induced lactate dehydrogenase leakage; both were attenuated by BA. Our results, including ATP depletion, induction of MPT, inhibition of mitochondrial respiration complexes, and uncoupling oxidative phosphorylation, indicate that sertraline-associated liver toxicity is possibly via mitochondrial dysfunction.

Topics: Adenosine Triphosphate; Animals; Antidepressive Agents; Bongkrekic Acid; Cells, Cultured; Chemical and Drug Induced Liver Injury; Cyclosporine; Dose-Response Relationship, Drug; Electron Transport Chain Complex Proteins; Energy Metabolism; Hepatocytes; L-Lactate Dehydrogenase; Male; Mitochondria, Liver; Mitochondrial ADP, ATP Translocases; Mitochondrial Diseases; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Oxidative Phosphorylation; Rats; Rats, Sprague-Dawley; Risk Assessment; Selective Serotonin Reuptake Inhibitors; Sertraline; Time Factors

Liver cirrhosis is often preceded by overt signs of hepatitis, including parenchymal cell inflammation and infiltration of polymorphonuclear (PMN) leukocytes. Activated PMNs release both reactive oxygen species and reactive halogen species, including hypochlorous acid (HOCl), which are known to be significantly cytotoxic due to their oxidizing potential. Because the role of mitochondria in the hepatotoxicity attributed to HOCl has not been elucidated, we investigated the effects of HOCl on mitochondrial function in the human hepatoma HepG2 cell line, human fetal liver cells, and isolated rat liver mitochondria. We show here that HOCl induced mitochondrial dysfunction, and apoptosis was dependent on the induction of the mitochondrial permeability transition (MPT), because HOCl induced mitochondrial swelling and collapse of the mitochondrial membrane potential with the concomitant release of cytochrome c. These biochemical events were inhibited by the classical MPT inhibitor cyclosporin A (CSA). Cell death induced by HOCl exhibited several classical hallmarks of apoptosis, including annexin V labeling, caspase activation, chromatin condensation, and cell body shrinkage. The induction of apoptosis by HOCl was further supported by the finding that CSA and caspase inhibitors prevented cell death. For the first time, these results show that HOCl activates the MPT, which leads to the induction of apoptosis and provides a novel insight into the mechanisms of HOCl-mediated cell death at sites of chronic inflammation.

Topics: Animals; Apoptosis; Bongkrekic Acid; Carcinoma, Hepatocellular; Caspase 3; Caspase 7; Caspases; Cell Line; Cell Line, Tumor; Cell Survival; Chemical and Drug Induced Liver Injury; Cyclosporine; Cytochromes c; Humans; Hypochlorous Acid; Liver; Membrane Potentials; Mitochondria, Liver; Mitochondrial Swelling; Permeability; Rats