Lee Kang Kwang, Boelsterli Urs A
Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States of America.
Department of Pharmaceutical Sciences, University of Connecticut, Storrs, CT 06269, United States of America.
Redox Biol. 2014;2:599-609. doi: 10.1016/j.redox.2014.03.003. Epub 2014 Mar 13.
Efavirenz (EFV) is an anti-retroviral drug frequently combined with isoniazid (INH) to treat HIV-1/tuberculosis co-infected patients. Both drugs have been associated with idiosyncratic liver injury (DILI), but combined anti-retroviral and anti-tubercular therapy can increase the risk for DILI as compared to either drug class alone. Because both EFV and INH have been implicated in targeting mitochondria, we aimed at exploring whether the two drugs might cause synergistic effects on the electron transport chain. We found that EFV inhibited complex I activity in isolated mouse liver mitochondria (IC50 ˜30 μM), whereas hydrazine, a major metabolite of INH generated by acylamidase-mediated hydrolytic cleavage, inhibited complex II activity (IC50 ˜30 μM). Neither INH alone (≤1000 μM) nor EFV alone (≤30 μM) was able to induce cell injury in cultured mouse hepatocytes. However, combined EFV/INH exposure resulted in increased superoxide formation and peroxynitrite stress, leading to the opening of the cyclosporine A-insensitive mode of the mitochondrial permeability transition (mPT), and necrotic cell death. The peroxynitrite scavengers, CBA or Fe-TMPyP, protected against mPT induction and alleviated cell injury. The acylamidase inhibitor bis-p-nitrophenyl phosphate prevented cell injury, suggesting that hydrazine greatly contributed to the toxicity. Methylene blue, a redox-active alternative electron acceptor/donor that bypasses complex I/II, effectively protected against EFV/INH-induced toxicity. These data demonstrate that, in murine hepatocytes, the mitochondrial electron transport chain is a critical target of combined EFV/INH exposure, and that this drug combination can lead to peroxynitrite stress-induced mPT and hepatocellular necrosis. These results are compatible with the concept that underlying silent mitochondrial dysfunction may be a key susceptibility factor contributing to idiosyncratic drug-induced liver injury.
依非韦伦（EFV）是一种抗逆转录病毒药物，常与异烟肼（INH）联合用于治疗HIV-1/结核合并感染患者。两种药物均与特异质性肝损伤（DILI）有关，但与单独使用任何一类药物相比，联合抗逆转录病毒和抗结核治疗会增加DILI的风险。由于EFV和INH都与靶向线粒体有关，我们旨在探讨这两种药物是否可能对电子传递链产生协同作用。我们发现，EFV抑制分离的小鼠肝线粒体中的复合体I活性（IC50约为30μM），而肼（由酰胺酶介导的水解裂解产生的INH的主要代谢产物）抑制复合体II活性（IC50约为30μM）。单独的INH（≤1000μM）或单独的EFV（≤30μM）均不能在培养的小鼠肝细胞中诱导细胞损伤。然而，EFV/INH联合暴露导致超氧化物生成增加和过氧亚硝酸盐应激，导致线粒体通透性转换（mPT）的环孢素A不敏感模式开放，并导致坏死性细胞死亡。过氧亚硝酸盐清除剂CBA或Fe-TMPyP可防止mPT诱导并减轻细胞损伤。酰胺酶抑制剂双对硝基苯磷酸可防止细胞损伤，表明肼对毒性有很大影响。亚甲蓝是一种绕过复合体I/II的氧化还原活性替代电子受体/供体，可有效防止EFV/INH诱导的毒性。这些数据表明，在小鼠肝细胞中，线粒体电子传递链是EFV/INH联合暴露的关键靶点，并且这种药物组合可导致过氧亚硝酸盐应激诱导的mPT和肝细胞坏死。这些结果与潜在的沉默线粒体功能障碍可能是导致特异质性药物性肝损伤的关键易感因素这一概念相符。
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