Idiosyncratic drug-induced liver injury (IDILI) has been the top reason for withdrawing drugs from the market or for black box warnings. IDILI may arise from the interaction of a drug's reactive metabolite with a mild inflammation that renders the liver more sensitive to injury resulting in increased toxicity (inflammatory stress hypothesis). Aiming to develop a robust ex vivo screening method to study inflammatory stress-related IDILI mechanisms and to find biomarkers that can detect or predict IDILI, mouse precision-cut liver slices (mPCLS) were coincubated for 24 h with IDILI-related drugs and lipopolysaccharide. Lipopolysaccharide exacerbated ketoconazole (15 μM) and clozapine (45 μM) toxicity but not their non-IDILI-related comparators, voriconazole (1500 μM) and olanzapine (45 μM). However, the other IDILI-related drugs tested [diclofenac (200 μM), carbamazepine (400 μM), and troglitazone (30 μM)] did not cause synergistic toxicity with lipopolysaccharide after 24 h of incubation. Lipopolysaccharide further decreased the reduced glutathione levels caused by ketoconazole or clozapine in mPCLS after 24 h of incubation, which was not the case for the other drugs. Lipopolysaccharide significantly increased nitric oxide (NO), cytokine, and chemokine release into the mPCLS media, while the treatment with the drugs alone did not cause any substantial change. All seven drugs drastically reduced lipopolysaccharide-induced NO production. Interestingly, only ketoconazole and clozapine increased the lipopolysaccharide-induced granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) release. Pilot experiments showed that diclofenac and troglitazone, but not carbamazepine, demonstrated synergistic toxicity with lipopolysaccharide after a longer incubation of 48 h in mPCLS. In conclusion, we have developed an ex vivo model to detect inflammatory stress-related liver toxicity and identified ketoconazole, clozapine, troglitazone, and diclofenac as drugs that showed synergistic toxicity with lipopolysaccharide. Reduced glutathione, G-CSF, and GM-CSF were identified to be potential biomarkers for IDILI-inducing drugs mediated by inflammatory stress, and mPCLS appear to be a promising screening tool to further unravel the mechanism of IDILI.

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Drug-induced cholestasis (DIC) is one of the leading manifestations of drug-induced liver injury (DILI). As the underlying mechanisms for DIC are not fully known and specific and predictive biomarkers and pre-clinical models are lacking, the occurrence of DIC is often only reported when the drug has been approved for registration. Therefore, appropriate models that predict the cholestatic potential of drug candidates and/or provide insight into the mechanism of DIC are highly needed. We investigated the application of rat precision-cut liver slices (PCLS) to predict DIC, using several biomarkers of cholestasis: hepatocyte viability, intracellular accumulation of total as well as individual bile acids and changes in the expression of genes known to play a role in cholestasis. Rat PCLS exposed to the cholestatic drugs chlorpromazine, cyclosporine A and glibenclamide for 48 h in the presence of a 60 μM physiological bile acid (BA) mix reflected various changes associated with cholestasis, such as decrease in hepatocyte viability, accumulation and changes in the composition of BA and changes in the gene expression of Fxr, Bsep and Ntcp. The toxicity of the drugs was correlated with the accumulation of BA, and especially DCA and CDCA and their conjugates, but to a different extent for different drugs, indicating that BA toxicity is not the only cause for the toxicity of cholestatic drugs. Moreover, our study supports the use of several biomarkers to test drugs for DIC. In conclusion, our results indicate that PCLS may represent a physiological and valuable model to identify cholestatic drugs and provide insight into the mechanisms underlying DIC.

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Idiosyncratic drug-induced liver injury (IDILI) is a major problem during drug development and has caused drug withdrawal and black-box warnings. Because of the low concordance of the hepatotoxicity of drugs in animals and humans, robust screening methods using human tissue are needed to predict IDILI in humans. According to the inflammatory stress hypothesis, the effects of inflammation interact with the effects of a drug or its reactive metabolite, precipitating toxic reactions in the liver. As a follow-up to our recently published mouse precision-cut liver slices model, an ex vivo model involving human precision-cut liver slices (hPCLS), co-incubated for 24 h with IDILI-related drugs and lipopolysaccharide (LPS), was developed to study IDILI mechanisms related to inflammatory stress in humans and to detect potential biomarkers. LPS exacerbated the effects of ketoconazole and clozapine toxicity but not those of their non-IDILI-related comparators, voriconazole and olanzapine. However, the IDILI-related drugs diclofenac, carbamazepine, and troglitazone did not show synergistic toxicity with LPS after incubation for 24 h. Co-incubation of ketoconazole and clozapine with LPS decreased the levels of glutathione in hPCLS, but this was not seen for the other drugs. All drugs affected LPS-induced cytokine release, but interestingly, only ketoconazole and clozapine increased the level of LPS-induced TNF release. Decreased levels of glutathione and cysteine conjugates of clozapine were detected in IDILI-responding livers following cotreatment with LPS. In conclusion, we identified ketoconazole and clozapine as drugs that exhibited synergistic toxicity with LPS, while glutathione and TNF were found to be potential biomarkers for IDILI-inducing drugs mediated by inflammatory stress. hPCLS appear to be suitable for further unraveling the mechanisms of inflammatory stress-associated IDILI.

Human precision-cut liver slices (hPCLS) are a valuable ex vivo model that can be used in acute toxicity studies. However, a rapid decline in metabolic enzyme activity limits their use in studies that require a prolonged xenobiotic exposure. The aim of the study was to extend the viability and function of hPCLS to 5 days of incubation. hPCLS were incubated in two media developed for long-term culture of hepatocytes, RegeneMed®, and Cellartis®, and in the standard medium WME. Maintenance of phase I and II metabolism was studied both on gene expression as well as functional level using a mixture of CYP isoform-specific substrates. Albumin synthesis, morphological integrity, and glycogen storage was assessed, and gene expression was studied by transcriptomic analysis using microarrays with a focus on genes involved in drug metabolism, transport and toxicity. The data show that hPCLS retain their viability and functionality during 5 days of incubation in Cellartis® medium. Albumin synthesis as well as the activity and gene expression of phase I and II metabolic enzymes did not decline during 120-h incubation in Cellartis® medium, with CYP2C9 activity as the only exception. Glycogen storage and morphological integrity were maintained. Moreover, gene expression changes in hPCLS during incubation were limited and mostly related to cytoskeleton remodeling, fibrosis, and moderate oxidative stress. The expression of genes involved in drug transport, which is an important factor in determining the intracellular xenobiotic exposure, was also unchanged. Therefore, we conclude that hPCLS cultured in Cellartis® medium are a valuable human ex vivo model for toxicological and pharmacological studies that require prolonged xenobiotic exposure.Electronic supplementary materialThe online version of this article (doi:10.1007/s00204-016-1865-x) contains supplementary material, which is available to authorized users.

Hepatic differentiation of human‐induced pluripotent stem cells (hiPSCs) under flow conditions in a 3D scaffold is expected to be a major step forward for construction of bioartificial livers. The aims of this study were to induce hepatic differentiation of hiPSCs under perfusion conditions and to perform functional comparisons with fresh human precision‐cut liver slices (hPCLS), an excellent benchmark for the human liver in vivo. The majority of the mRNA expression of CYP isoenzymes and transporters and the tested CYP activities, Phase II metabolism, and albumin, urea, and bile acid synthesis in the hiPSC‐derived cells reached values that overlap those of hPCLS, which indicates a higher degree of hepatic differentiation than observed until now. Differentiation under flow compared with static conditions had a strong inducing effect on Phase II metabolism and suppressed AFP expression but resulted in slightly lower activity of some of the Phase I metabolism enzymes. Gene expression data indicate that hiPSCs differentiated into both hepatic and biliary directions. In conclusion, the hiPSC differentiated under flow conditions towards hepatocytes express a wide spectrum of liver functions at levels comparable with hPCLS indicating excellent future perspectives for the development of a bioartificial liver system for toxicity testing or as liver support device for patients.