Evaluating the utility of hepatic in vitro models for the assessment of the multi-mechanistic toxicity of drug-induced liver injury

药物不良反应（adr）是国民保健服务（NHS）的一个主要负担，占2004年住院人数的6.5%。据估计，由于不良反应是第七大死因，NHS每年要花费4.66亿英镑。然而，不良反应不仅仅是医院的问题；它们代表了一个主要的制药问题。据估计，2015年，一种药物从实验室到市场的成本为26亿美元。1975年至1999年期间，在批准的548种新药中，10.2%获得黑盒警告或因不良反应退出市场。由于这个原因，有一个巨大的制药关注，因为数百万英镑和时间可能被浪费。虽然不良反应可以影响身体的不同器官，但肝脏是两个报告最多的病例之一。药物性肝损伤（DILI）表现为多种病理状态，有20 - 40%的报告病例引起胆汁淤积。据报道，药物诱导的线粒体毒性（DIMT）是DILI的决定因素，50%带有DILI黑框警告的药物也有线粒体负担。DILI与多种毒性机制有关。由于这个原因，不能使用“一种测试适合所有”的方法，这导致了临床前检测DILI的困难。然而，线粒体毒性和胆道转运蛋白的影响被认为是肝毒性的主要机制。线粒体具有丰富的结构和功能特征，可以被化合物靶向并导致毒性。这些可能包括电子传递链抑制，氧化磷酸化解偶联，线粒体通透性转变（MPT）孔的打开，线粒体动力学的改变和线粒体基因组的消耗。由于线粒体有自己的基因组，线粒体DNA （mtDNA）变异对DILI易感性的影响是另一个需要研究的潜在因素。该项目的目的是开发和验证筛选模型，以评估DILI的线粒体毒性和转运蛋白功能障碍。HepaRG细胞是源自人肝祖细胞系的终末分化的肝细胞，它保留了原代人肝细胞（PHH）的许多特征，包括外源代谢酶、药物转运体和功能性胆道结构。可以操纵HepaRG细胞来规避Crabtree效应，从而允许对线粒体毒性进行研究。因此，HepaRG细胞连接线粒体和转运体功能障碍之间相互作用的能力将被评估。此外，第一个个性化的肝脏特异性线粒体遗传变异体外模型的开发，创造了线粒体HepG2 cybrids，将允许对个体对DILI易感性的影响进行新的研究。DILI更具预测性和敏感性的模型及其与线粒体毒性和转运体改变的联系将在预防晚期药物损耗和开发更安全的药物方面证明是无价的。

Adverse drug reactions (ADRs) are a major burden to the National Health Services (NHS), accounting for 6.5 % of hospital admissions in 2004. It is estimated that ADRs cost the NHS £466 million annually due to them being the 7th leading cause of death. However, ADRs are not just a hospital problem; they represent a major pharmaceutical concern. In 2015, it was estimated that the cost of getting a drug from bench to market cost $2.6 billion. During 1975 - 1999, of the 548 new drugs that were approved, 10.2 % acquired black box warnings or were withdrawn from the market due to ADRs. For this reason, there is a great pharmaceutical concern as millions of pounds and time could be wasted. Whilst ADRs can affect different organs in the body, the liver is one of the two most reported cases. Drug-induced liver injury (DILI) presents itself as a variety of pathological conditions, with 20 - 40 % of reported cases causing cholestasis. Drug-induced mitochondrial toxicity (DIMT) has been reported as a determinant of DILI with 50 % of drugs with black box warnings for DILI also having mitochondrial burdens. DILI is associated with multiple mechanisms of toxicity. For this reason, a 'one test fits all' approach cannot be used, which has contributed to the difficulty in detecting DILI preclinically. Nevertheless, mitochondrial toxicity and biliary transporter implications are recognised as major mechanisms of hepatotoxicity. The mitochondria have a wealth of structural and functional features which can be targeted by a compound and lead to toxicity. These can include electron transport chain inhibition, oxidative phosphorylation uncoupling, opening of the mitochondrial permeability transition (MPT) pore, alterations in mitochondrial dynamics and the depletion of the mitochondrial genome. Due to the mitochondria having their own genome, the effects of mitochondrial DNA (mtDNA) variation upon susceptibility to DILI is another potential factor requiring investigation. The aim of the project is to develop and validate screening models for the assessment of mitochondrial toxicity and transporter dysfunction in DILI. HepaRG cells are terminally differentiated hepatic cells derived from a human hepatic progenitor cell line that retains many characteristics of primary human hepatocytes (PHH), including xenobiotic metabolism enzymes, drug transporters and functional biliary structures. HepaRG cells can be manipulated to circumvent the Crabtree effect, allowing investigations of mitochondrial toxicity. Therefore, the ability of HepaRG cells to connect the interplay between mitochondria and transporter dysfunction will be evaluated. Additionally, the development of the first personalised, liver-specific in vitro model for mitochondrial genetic variation, coined transmitochondrial HepG2 cybrids will allow novel investigations of the effects of individual susceptibility to DILI. More predictive and sensitive models for DILI and their links with mitochondrial toxicity and transporter alterations would prove invaluable in the prevention of late-stage drug attrition and the development of safer drugs.