Drug-Induced Inhibition of Mitochondrial Fatty Acid Oxidation and Steatosis

Mitochondrial Dysfunction and Diseases (H Jaeschke, Section Editor)International audienceDrug-induced inhibition of mitochondrial fatty acid β-oxidation (mtFAO) is a key mechanism whereby drugs can induce steatosis. The type and severity of this liver lesion is dependent on the residual mtFAO flux. Indeed, a severe inhibition of mtFAO leads to microvesicular steatosis, hypoglycemia and liver failure, which can be favored by genetic predispositions. In contrast, moderate impairment of mtFAO can cause macrovacuolar steatosis, which is by itself a benign lesion. In the long-term, however, macrovacuolar steatosis can progress with some drugs to steatohepatitis. Interestingly, drugs that are more likely to cause steatohepatitis are those impairing the mitochondrial respiratory chain (MRC) activity. Indeed, MRC impairment favors not only hepatic fat accretion but also oxidative stress and lipid peroxidation. Drugs inhibiting mtFAO could be more toxic in obese patients with preexisting nonalcoholic fatty liver disease (NAFLD) since higher mtFAO is a key metabolic adaptation to curb fat accretion during NAFLD

A cellular model to study drug-induced liver injury in nonalcoholic fatty liver disease: application to acetaminophen

International audienceObesity and nonalcoholic fatty liver disease (NAFLD) can increase susceptibility to hepatotoxicity induced by some xenobiotics including drugs, but the involved mechanisms are poorly understood. For acetaminophen (APAP), a role of hepatic cytochrome P450 2E1 (CYP2E1) is suspected since the activity of this enzyme is consistently enhanced during NAFLD. The first aim of our study was to set up a cellular model of NAFLD characterized not only by triglyceride accumulation but also by higher CYP2E1 activity. To this end, human HepaRG cells were incubated for one week with stearic acid or oleic acid, in the presence of different concentrations of insulin. Although cellular triglycerides and the expression of lipid-responsive genes were similar with both fatty acids, CYP2E1 activity was significantly increased only by stearic acid. CYP2E1 activity was reduced by insulin and this effect was reproduced in cultured primary human hepatocytes. Next, APAP cytotoxicity was assessed in HepaRG cells with or without lipid accretion and CYP2E1 induction. Experiments with a large range of APAP concentrations showed that the loss of ATP and glutathione was almost always greater in the presence of stearic acid. In cells pretreated with the CYP2E1 inhibitor chlormethiazole, recovery of ATP was significantly higher in the presence of stearate with low (2.5 mM) or high (20 mM) concentrations of APAP. Levels of APAP-glucuronide were significantly enhanced by insulin. Hence, HepaRG cells can be used as a valuable model of NAFLD to unveil important metabolic and hormonal factors which can increase susceptibility to drug-induced hepatotoxicit

Physiochemical properties of rat liver mitochondrial ribosomes

In the present study, the physiochemical properties of rat liver mitochondrial ribosomes were examined and compared with Escherichia coli ribosomes. The sedimentation and translational diffusion coefficients as well as the molecular weight and buoyant density of rat mitochondrial ribosomes were determined. Sedimentation coefficients were established using the time-derivative algorithm (Philo, J. S. (2000) Anal. Biochem. 279, 151-163). The sedimentation coefficients of the intact monosome, large subunit, and small subunit were 55, 39, and 28 S, respectively. Mitochondrial ribosomes had a particle composition of 75% protein and 25% RNA. The partial specific volume was 0.688 ml/g, as determined from the protein and RNA composition. The buoyant density of formaldehyde-fixed ribosomes in cesium chloride was 1.41 g/cm3. The molecular masses of mitochondrial and E. coli ribosomes determined by static lightscattering experiments were 3.57 +/- 0.14 MDa and 2.49 +/- 0.06 MDa, respectively. The diffusion coefficient obtained from dynamic light-scattering measurements was 1.10 +/- 0.01 x 10 -7 cm2 s-1 for mitochondrial ribosomes and 1.72 +/- 0.03 x 10 -7 cm2 s-1 for the 70 S E. coli monosome. The hydration factor determined from these hydrodynamic parameters were 4.6 g of water/g of ribosome and 1.3 g/g for mitochondrial and E. coli ribosomes, respectively. A calculated hydration factor of 3.3 g/g for mitochondrial ribosomes was also obtained utilizing a calculated molecular mass and the Svedberg equation. These measurements of solvation suggest that ribosomes are highly hydrated structures. They are also in agreement with current models depicting ribosomes as porous structures containing numerous gaps and tunnels

Weight of evidence evaluation of the metabolism disrupting effects of triphenyl phosphate using an expert knowledge elicitation approach

All partners acknowledge the contribution of their institutes for additional financial support. We would also like to acknowledge the scientific contributions from François Pouzaud, Sakina Mhaouty-Kodja and René Habert for the development of the EKE methodology within the frame of the Anses ED Expert group. Contributions from additional members of the GOLIATH consortium: Pierre-Etienne Toulemonde and Romane Multon from Anses are also acknowledged.Peer reviewe

Advanced preclinical models for evaluation of drug-induced liver injury - consensus statement by the European Drug-Induced Liver Injury Network [PRO-EURO-DILI-NET]

Funding: This work is supported by COST Action CA17112, www.cost.eu. LJN is supported by AMMF 2018/117; with support from grants - BBSRC (Grant BB/L023687/1), EPSRC (IAA Grant PIII013). MK and JM were partly funded by the Fundação para a Ciencia e a Tecnologia (FCT, Portugal), through grants UID/BIM/0009/2020 for the Research Center for Toxicogenomics and Human Health-(ToxOmics) and PTDC/MED-TOX/29183/2017 and UIDB/04138/2020 for the iMed.ULisboa, respectively. OK is supported by the Scientific and Technological Research Council of Turkey (TUBITAK 116Z388) and COST Action CA17112. PSB is supported by the Fondo de Investigación Sanitaria Carlos III, cofinanced by the Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea, “Una manera de hacer Europa” (FIS PI20/00765, PI17/00673), DTS18/00088 and Miguel Servet (CPII16/00041); AGAUR 2019_PROD_00055; NIHAAA 1U01AA026972-01. OL is supported by the Czech Ministry of Education, Youth and Sports (Project No. LTC19040). FJC is supported by the MINECO Retos SAF2016-78711 EXOHEP-CM S2017/BMD-3727, NanoLiver-CM Y2018/NMT-4949, ERAB Ref. EA 18/14, AMMF 2018/117, UCM-25-2019 and COST Action CA17112, RYC-2014-15242 and Gilead Liver Research 2018. JCFC and CGR are supported from grants and SAF2017-85877R, PID2019-111669RB-100 the CIBEREHD; the center grant P50AA011999 Southern California Research Center for ALPD and Cirrhosis funded by NIAAA/NIH; as well as support from AGAUR of the Generalitat de Catalunya SGR-2017-1112, the “ER stress-mitochondrial cholesterol axis in obesity-associated insulin resistance and comorbidities”-Ayudas FUNDACION BBVA and the Red Nacional 2018-102799-T de Enfermedades Metabólicas y Cáncer, Project 201916/31 from Fundació Marato TV3, and European Cooperation in Science & Technology (COST) ACTION CA17112 Prospective European Drug-Induced Liver Injury Network, www.cost.eu. GJS was partially supported by the Research Council of Norway through its Centres of Excellence funding scheme (Project number 262613).Drug-induced liver injury (DILI) is a major cause of acute liver failure (ALF) and one of the leading indications for liver transplantation in Western societies. Given the wide use of both prescribed and over the counter drugs, DILI has become a major health issue for which there is a pressing need to find novel and effective therapies. Although significant progress has been made in understanding the molecular mechanisms underlying DILI, our incomplete knowledge of its pathogenesis and inability to predict DILI is largely due to both discordance between human and animal DILI in preclinical drug development and a lack of models that faithfully recapitulate complex pathophysiological features of human DILI. This is exemplified by the hepatotoxicity of acetaminophen (APAP) overdose, a major cause of ALF because of its extensive worldwide use as an analgesic. Despite intensive efforts utilising current animal and in vitro models, the mechanisms involved in the hepatotoxicity of APAP are still not fully understood. In this expert Consensus Statement, which is endorsed by the European Drug-Induced Liver Injury Network, we aim to facilitate and outline clinically impactful discoveries by detailing the requirements for more realistic human-based systems to assess hepatotoxicity and guide future drug safety testing. We present novel insights and discuss major players in APAP pathophysiology, and describe emerging in vitro and in vivo pre-clinical models, as well as advanced imaging and in silico technologies, which may improve prediction of clinical outcomes of DILI.Peer reviewe

Roadmap to DILI research in Europe. A proposal from COST action ProEuroDILINet

In the current article the aims for a constructive way forward in Drug-Induced Liver Injury (DILI) are to highlight the most important priorities in research and clinical science, therefore supporting a more informed, focused, and better funded future for European DILI research. This Roadmap aims to identify key challenges, define a shared vision across all stakeholders for the opportunities to overcome these challenges and propose a high-quality research program to achieve progress on the prediction, prevention, diagnosis and management of this condition and impact on healthcare practice in the field of DILI. This will involve 1. Creation of a database encompassing optimised case report form for prospectively identified DILI cases with well-characterised controls with competing diagnoses, biological samples, and imaging data; 2. Establishing of preclinical models to improve the assessment and prediction of hepatotoxicity in humans to guide future drug safety testing; 3. Emphasis on implementation science and 4. Enhanced collaboration between drug-developers, clinicians and regulatory scientists. This proposed operational framework will advance DILI research and may bring together basic, applied, translational and clinical research in DILI.Funding for open access charge: Universidad de Malaga/CBUA. The present study has been supported by grants from Instituto de Salud Carlos III (ISCIII) (contract numbers: PID2022–140169OB-C21; PI21/01248; PI19/00883) and from Consejería de Salud de Andalucía (contract number: PEMP-0127–2020, Spain), cofounded by the European Union. This research was funded by HORIZON-HLTH-2022-STAYHLTH-02, grant number 101095679. Funded by the European Union. Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them. MK was partially supported by Grant UID/BIM/0009/2020 of the Portuguese Fundação para a Ciência e a Tecnologia (FCT). MVP and IAA hold Sara Borrell research contracts from ISCIII (CD21/00198 and CD20/00083, respectively). This research was supported by CIBERehd – Consorcio Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas, Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea – European Regional Development Fund. JIG and GPA are supported by NIHR Nottingham Biomedical Research Centre [NIHR203310]. The views expressed are those of the authors and not necessarily those of the National Health Service (NHS), the NIHR or the Department of Health. This publication is based upon work from COST Action “CA17112—Prospective European Drug-Induced Liver Injury Network” supported by COST (European Cooperation in Science and Technology); www.cost.eu

Roadmap to DILI research in Europe. A proposal from COST action ProEuroDILINet

\ua9 2024 The AuthorsIn the current article the aims for a constructive way forward in Drug-Induced Liver Injury (DILI) are to highlight the most important priorities in research and clinical science, therefore supporting a more informed, focused, and better funded future for European DILI research. This Roadmap aims to identify key challenges, define a shared vision across all stakeholders for the opportunities to overcome these challenges and propose a high-quality research program to achieve progress on the prediction, prevention, diagnosis and management of this condition and impact on healthcare practice in the field of DILI. This will involve 1. Creation of a database encompassing optimised case report form for prospectively identified DILI cases with well-characterised controls with competing diagnoses, biological samples, and imaging data; 2. Establishing of preclinical models to improve the assessment and prediction of hepatotoxicity in humans to guide future drug safety testing; 3. Emphasis on implementation science and 4. Enhanced collaboration between drug-developers, clinicians and regulatory scientists. This proposed operational framework will advance DILI research and may bring together basic, applied, translational and clinical research in DILI

Acute liver failure associated with prolonged use of bromfenac leading to liver transplantation

Bromfenac, a nonnarcotic analgesic nonsteroidal anti-inflammatory drug, was associated with reversible, minor elevations in serum aminotransferase levels during clinical trials. The aim of this study is to describe the clinical, laboratory, and histological features of 4 patients with severe bromfenac hepatotoxicity identified at 3 tertiary care centers participating in the US Acute Liver Failure Study Group. Bromfenac was administered for chronic musculoskeletal disorders to 4 women in therapeutic doses of 25 to 100 mg/d for a minimum of 90 days. All patients reported a prodrome of malaise and fatigue and presented with severe, symptomatic hepatocellular injury with associated hypoprothrombinemia. None of the subjects had underlying liver or kidney disease, and there was no evidence of a hypersensitivity reaction. Other identifiable causes of acute liver failure were uniformly excluded. Despite supportive measures, all the subjects developed progressive liver failure over 5 to 37 days, leading to emergency liver transplantation in 3 patients and death in 1 patient while awaiting transplantation. Extensive confluent parenchymal necrosis that appeared to begin in the central zones and was accompanied by a predominantly lymphocytic infiltrate was noted in all the livers examined. Nodular regeneration was seen in the 2 patients with a more protracted clinical course. Administration of therapeutic doses of bromfenac for greater than 90 days was associated with the development of acute liver failure leading to liver transplantation or death in 4 adult women. The poor outcomes observed in this series, coupled with the inability to identify individuals at risk for severe, idiosyncratic bromfenac hepatotoxicity, preclude further use of bromfenac in the medical community.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35273/1/500050607_ftp.pd

Involvement of Hepatic Innate Immunity in Alcoholic Liver Disease

Excessive alcohol consumption is one of the critical causative factors leading to alcoholic liver disease (ALD). ALD is characterized by a wide spectrum of liver damage, ranging from simple uncomplicated liver steatosis (fatty liver) to steatohepatitis and liver fibrosis/cirrhosis. It has been believed that the obvious underlying cause for ALD is due to hepatocyte death induced by alcohol itself. However, recent sparkling studies have shown that diverse immune responses contribute to ALD because liver is enriched with numerous immune cells. Especially, a line of evidence has suggested that innate immune cells such as Kupffer cells and natural killer (NK)/NKT cells are significantly involved in the pathogenesis of ALD via production of pro-inflammatory cytokines and other mediators. Indeed, more interestingly, hepatic stellate cells (HSCs), known as a major cell inducing liver steatosis and fibrosis, can be killed by liver NK cells, which could be suppressed by chronic alcohol consumption. In this review, with the view of liver as predominant innate immune organ, we describe the pathogenesis of ALD in which what roles of innate immune cells are and how they are interacting with HSCs

Long-term effects of high-fat or high-carbohydrate diets on glucose tolerance in mice with heterozygous carnitine palmitoyltransferase-1a deficiency

Background: Abnormal fatty acid metabolism is an important feature in the mechanisms of insulin resistance and β-cell dysfunction. Carnitine palmitoyltransferase-1a (CPT-1a, liver isoform) has a pivotal role in the regulation of mitochondrial fatty acid oxidation. We investigated the role of CPT-1a in the development of impaired glucose tolerance using a mouse model for CPT-1a deficiency when challenged by either a high-carbohydrate (HCD) or a high-fat diet (HFD) for a total duration of up to 46 weeks