Co-exposure to benzo[a]pyrene and ethanol induces a pathological progression of liver steatosis in vitro and in vivo

Curcumin attenuates smoking and drinking activated NF-κB/IL-6 inflammatory signaling axis in cervical cancer

BACKGROUND

High-risk strains of HPV are known to cause cervical cancer. Multiple clinical studies have emphasized that smoking and drinking are critical risk factors for cervical cancer and its high-grade precursors. In this study, we investigated if smoking and/or drinking augment the molecular mechanisms of cervical carcinogenesis and defined a potential therapeutic approach for their attenuation.

METHODS

The impact of benzo[a]pyrene (B[a]P) and/or ethanol (EtOH) exposure on cervical cancer cells was assessed by measuring changes in their cell migration and invasion characteristics. Expression of HPV16 E6/E7, NF-κB, cytokines, and inflammation mediators was determined using qRT-PCR, immunoblotting, ELISA, luciferase reporter assay, and confocal microscopy. Herein, we used curcumin (Cur), and PLGA nanoparticle formulation of curcumin (PLGA-Cur) and determined effectiveness of free Cur and PLGA-Cur formulation on smoking and drinking activated NF-κB/IL-6 mediated inflammatory signaling pathways using in vitro cervical cancer models.

RESULTS

Treatments with B[a]P and/or EtOH altered the expression of HPV16 E6/E7 oncogenes and EMT markers in cervical cancer cells; it also enhanced migration and invasion. In addition, B[a]P and/or EtOH exposure promoted inflammation pathways through TNF-α and NF-κB signaling, leading to IL-6 upregulation and activation of VEGF. The molecular effects caused by B[a]P and/or EtOH exposure were effectively attenuated by curcumin (Cur)/PLGA-Cur treatment.

CONCLUSIONS

These data suggest a molecular link between smoking, drinking, and HPV infectivity in cervical carcinogenesis. In addition, attenuation of these effects by treatment with Cur/PLGA-Cur treatment, implies the role of curcumin in cervical cancer prevention and treatment.

3D multi-cell-type liver organoids: A new model of non-alcoholic fatty liver disease for drug safety assessments

The development of in vitro models that recapitulate critical liver functions is essential for accurate assessments of drug toxicity. Although liver organoids can be used for drug discovery and toxicology, they are limited by (i) the lack of expression and activity of xenobiotic-metabolizing enzymes, and (ii) the difficulty of mimicking non-alcoholic fatty liver disease (NAFLD, which influences the expression of these enzymes) in vitro. Here, we generated three-dimensional multi-cell-type liver organoids (hereafter "HML organoids") from HepaRG cells, primary human macrophages, and hepatic-stellate-cell-derived LX-2 cells. We also developed an NAFLD model by culturing HML organoids for 9 days with a mixture of stearic and oleic acids. The exposed organoids showed typical features of steatosis and expressed fibrosis markers. We subsequently used HML and NAFLD-HML organoids to model drug-induced liver injury. By estimating the IC50 and benchmark doses, we were able to improve the in vitro detection of drugs likely to be toxic in fatty livers. Thus, HML and NAFLD-HML organoids exhibited most of the liver's functions and are relevant in vitro models of drug metabolism, drug toxicity, and adverse drug event in NAFLD.

Hepatoprotective Effects of Flavonoids against Benzo[a]Pyrene-Induced Oxidative Liver Damage along Its Metabolic Pathways

Benzo[a]pyrene (B[a]P), a highly carcinogenic polycyclic aromatic hydrocarbon primarily formed during incomplete organic matter combustion, undergoes a series of hepatic metabolic reactions once absorbed into the body. B[a]P contributes to liver damage, ranging from molecular DNA damage to the onset and progression of various diseases, including cancer. Specifically, B[a]P induces oxidative stress via reactive oxygen species generation within cells. Consequently, more research has focused on exploring the underlying mechanisms of B[a]P-induced oxidative stress and potential strategies to counter its hepatic toxicity. Flavonoids, natural compounds abundant in plants and renowned for their antioxidant properties, possess the ability to neutralize the adverse effects of free radicals effectively. Although extensive research has investigated the antioxidant effects of flavonoids, limited research has delved into their potential in regulating B[a]P metabolism to alleviate oxidative stress. This review aims to consolidate current knowledge on B[a]P-induced liver oxidative stress and examines the role of flavonoids in mitigating its toxicity.

Toxicity mechanisms of biomass burning aerosols in in vitro hepatic steatosis models

Nonalcoholic fatty liver disease (NAFLD) is a common chronic liver disease that contributes to the global rise in liver-related morbidity and mortality. Wood tar (WT) aerosols are a significant fraction of carbonaceous aerosol originating from biomass smoldering, contributing to air pollution particles smaller than 2.5 mm (PM2.5). Mechanistic biological associations exist between exposure to PM2.5 and increased NAFLD phenotypes in both cell and animal models. Therefore, this study examines whether an existing NAFLD-like condition can enhance the biological susceptibility of liver cells exposed to air pollution in the form of WT material. Liver cells were incubated with lauric or oleic acid (LA, OA, respectively) for 24 h to accumulate lipids and served as an in vitro hepatic steatosis model. When exposed to 0.02 or 0.2 g/L water-soluble WT aerosols, both steatosis model cells showed increased cell death compared to the control cells (blank-treated cells with or without pre-incubation with LA or OA) or compared to WT-treated cells without pre-incubation with LA or OA. Furthermore, alterations in oxidative status included variations in reactive oxygen species (ROS) levels, elevated levels of lipid peroxidation adducts, and decreased expression of antioxidant genes associated with the NRF2 transcription factor. In addition, steatosis model cells exposed to WT had a higher degree of DNA damage than the control cells (blank-treated cells with or without pre-incubation with LA or OA). These results support a possible systemic effect through the direct inflammatory and oxidative stress response following exposure to water-soluble WT on liver cells, especially those predisposed to fatty liver. Furthermore, the liver steatosis model can be influenced by the type of fatty acid used; increased adverse effects of WT on metabolic dysregulation were observed in the LA model to a higher extent compared to the OA model.

Azadirachtin Attenuates Carcinogen Benzo(a) Pyrene-Induced DNA Damage, Cell Cycle Arrest, Apoptosis, Inflammatory, Metabolic, and Oxidative Stress in HepG2 Cells

Azadirachtin (AZD), a limonoid from the versatile, tropical neem tree (Azadirachta indica), is well known for its many medicinal, and pharmacological effects. Its effects as an anti-oxidant, anti-inflammatory, and anti-cancer agent are well known. However, not many studies have explored the effects of AZD on toxicities induced by benzo(a)pyrene (B(a)P), a toxic component of cigarette smoke known to cause DNA damage and cell cycle arrest, leading to different kinds of cancer. In the present study, using HepG2 cells, we investigated the protective effects of Azadirachtin (AZD) against B(a)P-induced oxidative/nitrosative and metabolic stress and mitochondrial dysfunction. Treatment with 25 µM B(a)P for 24 h demonstrated an increased production of reactive oxygen species (ROS), followed by increased lipid peroxidation and DNA damage presumably, due to the increased metabolic activation of B(a)P by CYP 450 1A1/1A2 enzymes. We also observed intrinsic and extrinsic apoptosis, alterations in glutathione-dependent redox homeostasis, cell cycle arrest, and inflammation after B(a)P treatment. Cells treated with 25 µM AZD for 24 h showed decreased oxidative stress and apoptosis, partial protection from DNA damage, and an improvement in mitochondrial functions and bioenergetics. The improvement in antioxidant status, anti-inflammatory potential, and alterations in cell cycle regulatory markers qualify AZD as a potential therapeutic in combination with anti-cancer drugs.

In vitro to in vivo extrapolation and high-content imaging for simultaneous characterization of chemically induced liver steatosis and markers of hepatotoxicity

Chemically induced steatosis is characterized by lipid accumulation associated with mitochondrial dysfunction, oxidative stress and nucleus distortion. New approach methods integrating in vitro and in silico models are needed to identify chemicals that may induce these cellular events as potential risk factors for steatosis and associated hepatotoxicity. In this study we used high-content imaging for the simultaneous quantification of four cellular markers as sentinels for hepatotoxicity and steatosis in chemically exposed human liver cells in vitro. Furthermore, we evaluated the results with a computational model for the extrapolation of human oral equivalent doses (OED). First, we tested 16 reference chemicals with known capacities to induce cellular alterations in nuclear morphology, lipid accumulation, mitochondrial membrane potential and oxidative stress. Then, using physiologically based pharmacokinetic modeling and reverse dosimetry, OEDs were extrapolated from data of any stimulated individual sentinel response. The extrapolated OEDs were confirmed to be within biologically relevant exposure ranges for the reference chemicals. Next, we tested 14 chemicals found in food, selected from thousands of putative chemicals on the basis of structure-based prediction for nuclear receptor activation. Amongst these, orotic acid had an extrapolated OED overlapping with realistic exposure ranges. Thus, we were able to characterize known steatosis-inducing chemicals as well as data-scarce food-related chemicals, amongst which we confirmed orotic acid to induce hepatotoxicity. This strategy addresses needs of next generation risk assessment and can be used as a first chemical prioritization hazard screening step in a tiered approach to identify chemical risk factors for steatosis and hepatotoxicity-associated events.

A New In Vivo Zebrafish Bioassay Evaluating Liver Steatosis Identifies DDE as a Steatogenic Endocrine Disruptor, Partly through SCD1 Regulation

Non-alcoholic fatty liver disease (NAFLD), which starts with liver steatosis, is a growing worldwide epidemic responsible for chronic liver diseases. Among its risk factors, exposure to environmental contaminants, such as endocrine disrupting compounds (EDC), has been recently emphasized. Given this important public health concern, regulation agencies need novel simple and fast biological tests to evaluate chemical risks. In this context, we developed a new in vivo bioassay called StAZ (Steatogenic Assay on Zebrafish) using an alternative model to animal experimentation, the zebrafish larva, to screen EDCs for their steatogenic properties. Taking advantage of the transparency of zebrafish larvae, we established a method based on fluorescent staining with Nile red to estimate liver lipid content. Following testing of known steatogenic molecules, 10 EDCs suspected to induce metabolic disorders were screened and DDE, the main metabolite of the insecticide DDT, was identified as a potent inducer of steatosis. To confirm this and optimize the assay, we used it in a transgenic zebrafish line expressing a blue fluorescent liver protein reporter. To obtain insight into DDE's effect, the expression of several genes related to steatosis was analyzed; an up-regulation of scd1 expression, probably relying on PXR activation, was found, partly responsible for both membrane remodeling and steatosis.

Mitochondrial alterations in fatty liver diseases

Fatty liver diseases can result from common metabolic diseases, as well as from xenobiotic exposure and excessive alcohol use, all of which have been shown to exert toxic effects on hepatic mitochondrial functionality and dynamics. Invasive or complex methodology limits large-scale investigations of mitochondria in human livers. Nevertheless, abnormal mitochondrial function, such as impaired fatty acid oxidation and oxidative phosphorylation, drives oxidative stress and has been identified as an important feature of human steatohepatitis. On the other hand, hepatic mitochondria can be flexible and adapt to the ambient metabolic condition to prevent triglyceride and lipotoxin accumulation in obesity. Experience from studies on xenobiotics has provided important insights into the regulation of hepatic mitochondria. Increasing awareness of the joint presence of metabolic disease-related (lipotoxic) and alcohol-related liver diseases further highlights the need to better understand their mutual interaction and potentiation in disease progression. Recent clinical studies have assessed the effects of diets or bariatric surgery on hepatic mitochondria, which are also evolving as an interesting therapeutic target in non-alcoholic fatty liver disease. This review summarises the current knowledge on hepatic mitochondria with a focus on fatty liver diseases linked to obesity, type 2 diabetes and xenobiotics.

Metabolism-Disrupting Chemicals Affecting the Liver: Screening, Testing, and Molecular Pathway Identification

The liver is the central metabolic organ of the body. The plethora of anabolic and catabolic pathways in the liver is tightly regulated by physiological signaling but may become imbalanced as a consequence of malnutrition or exposure to certain chemicals, so-called metabolic endocrine disrupters, or metabolism-disrupting chemicals (MDCs). Among different metabolism-related diseases, obesity and non-alcoholic fatty liver disease (NAFLD) constitute a growing health problem, which has been associated with a western lifestyle combining excessive caloric intake and reduced physical activity. In the past years, awareness of chemical exposure as an underlying cause of metabolic endocrine effects has continuously increased. Within this review, we have collected and summarized evidence that certain environmental MDCs are capable of contributing to metabolic diseases such as liver steatosis and cholestasis by different molecular mechanisms, thereby contributing to the metabolic syndrome. Despite the high relevance of metabolism-related diseases, standardized mechanistic assays for the identification and characterization of MDCs are missing. Therefore, the current state of candidate test systems to identify MDCs is presented, and their possible implementation into a testing strategy for MDCs is discussed.

Biomedical Research on Substances of Abuse: The Italian Case Study

Substances of abuse have the potential to cause addiction, habituation or altered consciousness. Most of the research on these substances focuses on addiction, and is carried out through observational and clinical studies on humans, or experimental studies on animals. The transposition of the EU Directive 2010/63 into Italian law in 2014 (IT Law 2014/26) includes a ban on the use of animals for research on substances of abuse. Since then, in Italy, public debate has continued on the topic, while the application of the Article prohibiting animal research in this area has been postponed every couple of years. In the light of this debate, we briefly review a range of methodologies - including animal and non-animal, as well as patient or population-based studies - that have been employed to address the biochemical, neurobiological, toxicological, clinical and behavioural effects of substances of abuse and their dependency. We then discuss the implications of the Italian ban on the use of animals for such research, proposing concrete and evidence-based solutions to allow scientists to pursue high-quality basic and translational studies within the boundaries of the regulatory and legislative framework.

Impact of benzo[a]pyrene with other pollutants induce the molecular alternation in the biological system: Existence, detection, and remediation methods

The exposure of benzo [a]pyrene (BaP) in recent times is rather unavoidable than ever before. BaP emissions are sourced majorly from anthropogenic rather than natural provenance from wildfires and volcanic eruptions. A major under-looked source is via the consumption of foods that are deep-fried, grilled, and charcoal smoked foods (meats in particular). BaP being a component of poly aromatic hydrocarbons has been classified as a Group I carcinogenic agent, which has been shown to cause both systemic and localized effects in animal models as well as in humans; has been known to cause various forms of cancer, accelerate neurological disorders, invoke DNA and cellular damage due to the generation of reactive oxygen species and involve in multi-generational phenotypic and genotypic defects. BaP's short and accumulated exposure has been shown in disrupting the fertility of gamete cells. In this review, we have discussed an in-depth and capacious run-through of the various origins of BaP, its economic distribution and its impact as well as toxicological effects on the environment and human health. It also deals with a mechanism as a single compound and its ability to synergize with other chemicals/materials, novel sensitive detection methods, and remediation approaches held in the environment.

Combinatory Exposure to Urolithin A, Alternariol, and Deoxynivalenol Affects Colon Cancer Metabolism and Epithelial Barrier Integrity in vitro

The human gastrointestinal tract is an important site of nutrient absorption and a crucial barrier against xenobiotics. It regularly faces “chemical cocktails” composed of food constituents, their human and microbial metabolites, and foodborne contaminants, such as mycotoxins. Hence, the colonic epithelium adapts to dietary molecules tuning its immune response, structural integrity, and metabolism to maintain intestinal homeostasis. While gut microbiota metabolites of berry ellagitannins, such as urolithin A (Uro A) might contribute to physiological epithelial barrier integrity, foodborne co-contaminating mycotoxins like alternariol (AOH) and deoxynivalenol (DON) could hamper epithelial function. Hence, we investigated the response of differentiated Caco-2 cells (clone C2BBe1) in vitro to the three compounds alone or in binary mixtures. In virtue of the possible interactions of Uro A, AOH, and DON with the aryl hydrocarbon receptor (AhR) pathway, potential effects on phase-I-metabolism enzymes and epithelial structural integrity were taken as endpoints for the evaluation. Finally, Liquid chromatography tandem mass spectrometry measurements elucidated the absorption, secretion, and metabolic capacity of the cells under single and combinatory exposure scenarios. Uro A and AOH as single compounds, and as a binary mixture, were capable to induce CYP1A1/1A2/1B1 enzymes triggered by the AhR pathway. In light of its ribosome inhibiting capacity, the trichothecene suppressed the effects of both dibenzo-α-pyrones. In turn, cellular responsiveness to Uro A and AOH could be sustained when co-exposed to DON-3-sulfate, instead of DON. Colonic epithelial structural integrity was rather maintained after incubation with Uro A and AOH: this was reinforced in the combinatory exposure scenario and disrupted by DON, an effect, opposed in combination. Passage through the cells as well as the metabolism of Uro A and AOH were rather influenced by co-exposure to DON, than by interaction with each other. Therefore, we conclude that although single foodborne bioactive substances individually could either support or disrupt the epithelial structure and metabolic capacity of colon cancer, exposure to chemical mixtures changes the experimental outcome and calls for the need of combinatory investigations for proper risk assessment.

Obesity II: Establishing causal links between chemical exposures and obesity

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Obesity III: Obesogen assays: Limitations, strengths, and new directions

There is increasing evidence of a role for environmental contaminants in disrupting metabolic health in both humans and animals. Despite a growing need for well-understood models for evaluating adipogenic and potential obesogenic contaminants, there has been a reliance on decades-old in vitro models that have not been appropriately managed by cell line providers. There has been a quick rise in available in vitro models in the last ten years, including commercial availability of human mesenchymal stem cell and preadipocyte models; these models require more comprehensive validation but demonstrate real promise in improved translation to human metabolic health. There is also progress in developing three-dimensional and co-culture techniques that allow for the interrogation of a more physiologically relevant state. While diverse rodent models exist for evaluating putative obesogenic and/or adipogenic chemicals in a physiologically relevant context, increasing capabilities have been identified for alternative model organisms such as Drosophila, C. elegans, zebrafish, and medaka in metabolic health testing. These models have several appreciable advantages, including most notably their size, rapid development, large brood sizes, and ease of high-resolution lipid accumulation imaging throughout the organisms. They are anticipated to expand the capabilities of metabolic health research, particularly when coupled with emerging obesogen evaluation techniques as described herein.

Transcriptomic analysis in zebrafish larvae identifies iron-dependent mitochondrial dysfunction as a possible key event of NAFLD progression induced by benzo[a]pyrene/ethanol co-exposure

Non-alcoholic fatty liver disease (NAFLD) is a worldwide epidemic for which environmental contaminants are increasingly recognized as important etiological factors. Among them, the combination of benzo[a]pyrene (B[a]P), a potent environmental carcinogen, with ethanol, was shown to induce the transition of steatosis toward steatohepatitis. However, the underlying mechanisms involved remain to be deciphered. In this context, we used high-fat diet fed zebrafish model, in which we previously observed progression of steatosis to a steatohepatitis-like state following a 7-day-co-exposure to 43 mM ethanol and 25 nM B[a]P. Transcriptomic analysis highlighted the potent role of mitochondrial dysfunction, alterations in heme and iron homeostasis, involvement of aryl hydrocarbon receptor (AhR) signaling, and oxidative stress. Most of these mRNA dysregulations were validated by RT-qPCR. Moreover, similar changes were observed using a human in vitro hepatocyte model, HepaRG cells. The mitochondria structural and functional alterations were confirmed by transmission electronic microscopy and Seahorse technology, respectively. Involvement of AhR signaling was evidenced by using in vivo an AhR antagonist, CH223191, and in vitro in AhR-knock-out HepaRG cells. Furthermore, as co-exposure was found to increase the levels of both heme and hemin, we investigated if mitochondrial iron could induce oxidative stress. We found that mitochondrial labile iron content was raised in toxicant-exposed larvae. This increase was prevented by the iron chelator, deferoxamine, which also inhibited liver co-exposure toxicity. Overall, these results suggest that the increase in mitochondrial iron content induced by B[a]P/ethanol co-exposure causes mitochondrial dysfunction that contributes to the pathological progression of NAFLD.

A new approach for reducing pollutants level: a longitudinal cohort study of physical exercises in young people

BACKGROUND

The present study aimed to evaluate the elimination of three common pollutants (dimethoate, benzo(a)pyrene (BaP) and bisphenol A (BPA) by different physical exercises and to assess the possible factors which could affect the pollutants elimination.

METHODS

A total of 200 individuals who chose different kinds of exercises in accordance to their own wish were recruited. The levels of urinary pollutants were measured using β-glucuronidase hydrolysis followed by a high-performance liquid chromatography tandem mass spectrometry-based method.

RESULTS

Totally, the levels of dimethoate, BaP and BPA were reduced after physical exercises. However, the elimination of BaP in male was higher than that in female but the elimination of BPA in female was higher than that in male. Multivariate logistic regression showed that the degree of heart rate (HR) change was a protective factor affecting the improvement effect of dimethoate, BaP and BPA while BMI (body mass index) was a risk factor. Nevertheless, sex was a risk factor affecting the improvement of dimethoate and BaP but had a lower efficacy on BPA improvement.

CONCLUSION

The present findings indicate that physical exercises can be considered as a novel approach to eliminate pollutants level in human body and can also give suggestions for choosing specific physical exercises to male and female individuals. Moreover, those who are with higher BMI need to lose weight before eliminating pollutant level through physical exercises.

Xenobiotic-Induced Aggravation of Metabolic-Associated Fatty Liver Disease

Metabolic-associated fatty liver disease (MAFLD), which is often linked to obesity, encompasses a large spectrum of hepatic lesions, including simple fatty liver, steatohepatitis, cirrhosis and hepatocellular carcinoma. Besides nutritional and genetic factors, different xenobiotics such as pharmaceuticals and environmental toxicants are suspected to aggravate MAFLD in obese individuals. More specifically, pre-existing fatty liver or steatohepatitis may worsen, or fatty liver may progress faster to steatohepatitis in treated patients, or exposed individuals. The mechanisms whereby xenobiotics can aggravate MAFLD are still poorly understood and are currently under deep investigations. Nevertheless, previous studies pointed to the role of different metabolic pathways and cellular events such as activation of de novo lipogenesis and mitochondrial dysfunction, mostly associated with reactive oxygen species overproduction. This review presents the available data gathered with some prototypic compounds with a focus on corticosteroids and rosiglitazone for pharmaceuticals as well as bisphenol A and perfluorooctanoic acid for endocrine disruptors. Although not typically considered as a xenobiotic, ethanol is also discussed because its abuse has dire consequences on obese liver.

DMSO-free highly differentiated HepaRG spheroids for chronic toxicity, liver functions and genotoxicity studies

The liver is essential in the elimination of environmental and food contaminants. Given the interspecies differences between rodents and humans, the development of relevant in vitro human models is crucial to investigate liver functions and toxicity in cells that better reflect pathophysiological processes. Classically, the differentiation of the hepatic HepaRG cell line requires high concentration of dimethyl sulfoxide (DMSO), which restricts its usefulness for drug-metabolism studies. Herein, we describe undifferentiated HepaRG cells embedded in a collagen matrix in DMSO-free conditions that rapidly organize into polarized hollow spheroids of differentiated hepatocyte-like cells (Hepoid-HepaRG). Our conditions allow concomitant proliferation with high levels of liver-specific functions and xenobiotic metabolism enzymes expression and activities after a few days of culture and for at least 4 weeks. By studying the toxicity of well-known injury-inducing drugs by treating cells with 1- to 100-fold of their plasmatic concentrations, we showed appropriate responses and demonstrate the sensitivity to drugs known to induce various degrees of liver injury. Our results also demonstrated that the model is well suited to estimate cholestasis and steatosis effects of drugs following chronic treatment. Additionally, DNA alterations caused by four genotoxic compounds (Aflatoxin B₁ (AFB₁), Benzo[a]Pyrene (B[a]P), Cyclophosphamide (CPA) and Methyl methanesulfonate (MMS)) were quantified in a dose-dependent manner by the comet and micronucleus assays. Their genotoxic effects were significantly increased after either an acute 24 h treatment (AFB₁: 1.5-6 μM, CPA: 2.5-10 μM, B[a]P: 12.5-50 μM, MMS: 90-450 μM) or after a 14-day treatment at much lower concentrations (AFB₁: 0.05-0.2 μM, CPA: 0.125-0.5 μM, B[a]P: 0.125-0.5 μM) representative to human exposure. Altogether, the DMSO-free 3D culture of Hepoid-HepaRG provides highly differentiated and proliferating cells relevant for various toxicological in vitro assays, especially for drug-preclinical studies and environmental chemicals risk assessment.

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

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.

Bioengineered Liver Models for Investigating Disease Pathogenesis and Regenerative Medicine

Owing to species-specific differences in liver pathways, in vitro human liver models are utilized for elucidating mechanisms underlying disease pathogenesis, drug development, and regenerative medicine. To mitigate limitations with de-differentiated cultures, bioengineers have developed advanced techniques/platforms, including micropatterned cocultures, spheroids/organoids, bioprinting, and microfluidic devices, for perfusing cell cultures and liver slices. Such techniques improve mature functions and culture lifetime of primary and stem-cell human liver cells. Furthermore, bioengineered liver models display several features of liver diseases including infections with pathogens (e.g., malaria, hepatitis C/B viruses, Zika, dengue, yellow fever), alcoholic/nonalcoholic fatty liver disease, and cancer. Here, we discuss features of bioengineered human liver models, their uses for modeling aforementioned diseases, and how such models are being augmented/adapted for fabricating implantable human liver tissues for clinical therapy. Ultimately, continued advances in bioengineered human liver models have the potential to aid the development of novel, safe, and efficacious therapies for liver disease.

Endocrine disrupting chemicals and metabolic disorders in the liver: What if we also looked at the female side?

Endocrine disrupting chemicals (EDCs) are linked to the worldwide epidemic incidence of metabolic disorders and fatty liver diseases, which affects quality of life and represents a high economic cost to society. Energy homeostasis exhibits strong sexual dimorphic traits, and metabolic organs respond to EDCs depending on sex, such as the liver, which orchestrates both drug elimination and glucose and lipid metabolism. In addition, fatty liver diseases show a strong sexual bias, which in part could also originate from sex differences observed in gut microbiota. The aim of this review is to highlight significant differences in endocrine and metabolic aspects of the liver, between males and females throughout development and into adulthood. It is also to illustrate how the male and female liver differently cope with exposure to various EDCs such as bisphenols, phthalates and persistent organic chemicals in order to draw attention to the need to include both sexes in experimental studies. Interesting data come from analyses of the composition and diversity of the gut microbiota in males exposed to the mentioned EDCs showing significant correlations with hepatic lipid accumulation and metabolic disorders but information on females is lacking or incomplete. As industrialization increases, the list of anthropogenic chemicals to which humans will be exposed will also likely increase. In addition to strengthening existing regulations, encouraging populations to protect themselves and promoting the substitution of harmful chemicals with safe products, innovative strategies based on sex differences in the gut microbiota and in the gut-liver axis could be optimistic outlook.

Assessment of fibrotic pathways induced by environmental chemicals using 3D-human liver microtissue model

Exposure to environmental chemicals, particularly those with persistent and bioaccumulative properties have been linked to liver diseases. Induction of fibrotic pathways is considered as a pre-requirement of chemical induced liver fibrosis. Here, we applied 3D in vitro human liver microtissues (MTs) composed of HepaRG, THP-1 and hTERT-HSC that express relevant hepatic pathways (bile acid, sterol, and xenobiotic metabolism) and can recapitulate key events of liver fibrosis (e.g. extracellular matrix-deposition). The liver MTs were exposed to a known profibrotic chemical, thioacetamide (TAA) and three representative environmental chemicals (TCDD, benzo [a] pyrene (BaP) and PCB126). Both TAA and BaP triggered fibrotic pathway related events such as hepatocellular damage (cytotoxicity and decreased albumin release), hepatic stellate cell activation (transcriptional upregulation of α-SMA and Col1α1) and extracellular matrix remodelling. TCDD or PCB126 at measured concentrations did not elicit these responses in the 3D liver MTs system, though they caused cytotoxicity in HepaRG monoculture at high concentrations. Reduced human transcriptome (RHT) analysis captured molecular responses involved in liver fibrosis when MTs were treated with TAA and BaP. The results suggest that 3D, multicellular, human liver microtissues represent an alternative, human-relevant, in vitro liver model for assessing fibrotic pathways induced by environmental chemicals.

Extracellular vesicles released by polycyclic aromatic hydrocarbons-treated hepatocytes trigger oxidative stress in recipient hepatocytes by delivering iron

A growing body of evidences indicate the major role of extracellular vesicles (EVs) as players of cell communication in the pathogenesis of liver diseases. EVs are membrane-enclosed vesicles released by cells into the extracellular environment. Oxidative stress is also a key component of liver disease pathogenesis, but no role for hepatocyte-derived EVs has yet been described in the development of this process. Recently, some polycyclic aromatic hydrocarbons (PAHs), widespread environmental contaminants, were demonstrated to induce EV release from hepatocytes. They are also well-known to trigger oxidative stress leading to cell death. Therefore, the aim of this work was to investigate the involvement of EVs derived from PAHs-treated hepatocytes (PAH-EVs) in possible oxidative damages of healthy recipient hepatocytes, using both WIF-B9 and primary rat hepatocytes. We first showed that the release of EVs from PAHs -treated hepatocytes depended on oxidative stress. PAH-EVs were enriched in proteins related to oxidative stress such as NADPH oxidase and ferritin. They were also demonstrated to contain more iron. PAH-EVs could then induce oxidative stress in recipient hepatocytes, thereby leading to apoptosis. Mitochondria and lysosomes of recipient hepatocytes exhibited significant structural alterations. All those damages were dependent on internalization of EVs that reached lysosomes with their cargoes. Lysosomes thus appeared as critical organelles for EVs to induce apoptosis. In addition, pro-oxidant components of PAH-EVs, e.g. NADPH oxidase and iron, were revealed to be necessary for this cell death.

In utero exposure to phenanthrene induces hepatic steatosis in F1 adult female mice

Environmental pollutants are thought to be a risk factor for the prevalence of hepatic steatosis. Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, and human exposure is inevitable. In the present study, phenanthrene (Phe) was used as a representative PAH to investigate the effects of in utero exposure to PAH on hepatic lipid metabolism and the toxicological mechanism involved. Pregnant mice (C57BL/6J) were orally administered Phe (0, 60, 600 and 6000 μg kg-1 body weight) once every 3 days with 6 doses in total. F1 female mice aged 125 days showed significantly elevated hepatic lipid levels in the liver. The protein expression of hepatic peroxisome proliferator-activated receptors (PPARβ and PPARγ) and retinoid X receptors (RXRs) was upregulated; the transcription of genes related to lipogenesis, such as srebp1 (encoding sterol regulatory element binding proteins), acca (acetyl-CoA carboxylase), fasn (fatty acid synthase) and pcsk9 (proprotein convertase subtilisin/kexin type 9), showed an upregulation, while the mRNA levels of the lipolysis gene lcat (encoding lecithin cholesterol acyl transferase) were downregulated. These results could be responsible for lipid accumulation. The promoter methylation levels of pparγ were reduced and were the lowest in the 600 μg kg-1 group, and the promoter methylation levels of lcat were significantly increased in all the Phe treatments. These changes were matched with the alterations in their mRNA levels, suggesting that prenatal Phe exposure could induce abnormal lipid metabolism in later life via epigenetic modification.

MEHP/ethanol co-exposure favors the death of steatotic hepatocytes, possibly through CYP4A and ADH involvement

Liver steatosis has been associated with various etiological factors (obesity, alcohol, environmental contaminants). How those factors work together to induce steatosis progression is still scarcely evaluated. Here, we tested whether phthalates could potentiate death of steatotic hepatocytes when combined with ethanol. Pre-steatotic WIF-B9 hepatocytes were co-exposed to mono (2-ethylhexyl) (MEHP, 500 nM; main metabolite of di (2-ethylhexyl) phthalate or DEHP) and ethanol (5 mM) for 5 days. An increased apoptotic death was detected, involving a DNA damage response. Using 4-Methypyrazole to inhibit ethanol metabolism, and CH-223191 to antagonize the AhR receptor, we found that an AhR-dependent increase in alcohol dehydrogenase (ADH) activity was essential for cell death upon MEHP/ethanol co-exposure. Toxicity was also prevented by HET0016 to inhibit the cytochrome P450 4A (CYP4A). Using the antioxidant thiourea, a role for oxidative stress was uncovered, notably triggering DNA damage. Finally, co-exposing the in vivo steatosis model of high fat diet (HFD)-zebrafish larvae to DEHP (2.56 nM)/ethanol (43 mM), induced the pathological progression of liver steatosis alongside an increased Cyp4t8 (human CYP4A homolog) mRNA expression. Altogether, these results further emphasized the deleterious impact of co-exposures to ethanol/environmental pollutant towards steatosis pathological progression, and unraveled a key role for ADH and CYP4A in such effects.

Treatments in Covid-19 patients with pre-existing metabolic dysfunction-associated fatty liver disease: A potential threat for drug-induced liver injury?

Obese patients who often present metabolic dysfunction-associated fatty liver disease (MAFLD) are at risk of severe presentation of coronavirus disease 2019 (COVID-19). These patients are more likely to be hospitalized and receive antiviral agents and other drugs required to treat acute respiratory distress syndrome and systemic inflammation, combat bacterial and fungal superinfections and reverse multi-organ failure. Among these pharmaceuticals, antiretrovirals such as lopinavir/ritonavir and remdesivir, antibiotics and antifungal agents can induce drug-induced liver injury (DILI), whose mechanisms are not always understood. In the present article, we hypothesize that obese COVID-19 patients with MAFLD might be at higher risk for DILI than non-infected healthy individuals or MAFLD patients. These patients present several concomitant factors, which individually can favour DILI: polypharmacy, systemic inflammation at risk of cytokine storm, fatty liver and sometimes nonalcoholic steatohepatitis (NASH) as well as insulin resistance and other diseases linked to obesity. Hence, in obese COVID-19 patients, some drugs might cause more severe (and/or more frequent) DILI, while others might trigger the transition of fatty liver to NASH, or worsen pre-existing steatosis, necroinflammation and fibrosis. We also present the main mechanisms whereby drugs can be more hepatotoxic in MAFLD including impaired activity of xenobiotic-metabolizing enzymes, mitochondrial dysfunction, altered lipid homeostasis and oxidative stress. Although comprehensive investigations are needed to confirm our hypothesis, we believe that the current epidemic of obesity and related metabolic diseases has extensively contributed to increase the number of cases of DILI in COVID-19 patients, which may have participated in presentation severity and death.

Integrative Strategy of Testing Systems for Identification of Endocrine Disruptors Inducing Metabolic Disorders-An Introduction to the OBERON Project

Exposure to chemical substances that can produce endocrine disrupting effects represents one of the most critical public health threats nowadays. In line with the regulatory framework implemented within the European Union (EU) to reduce the levels of endocrine disruptors (EDs) for consumers, new and effective methods for ED testing are needed. The OBERON project will build an integrated testing strategy (ITS) to detect ED-related metabolic disorders by developing, improving and validating a battery of test systems. It will be based on the concept of an integrated approach for testing and assessment (IATA). OBERON will combine (1) experimental methods (in vitro, e.g., using 2D and 3D human-derived cells and tissues, and in vivo, i.e., using zebrafish at different stages), (2) high throughput omics technologies, (3) epidemiology and human biomonitoring studies and (4) advanced computational models (in silico and systems biology) on functional endpoints related to metabolism. Such interdisciplinary framework will help in deciphering EDs based on a mechanistic understanding of toxicity by providing and making available more effective alternative test methods relevant for human health that are in line with regulatory needs. Data generated in OBERON will also allow the development of novel adverse outcome pathways (AOPs). The assays will be pre-validated in order to select the test systems that will show acceptable performance in terms of relevance for the second step of the validation process, i.e., the inter-laboratory validation as ring tests. Therefore, the aim of the OBERON project is to support the organization for economic co-operation and development (OECD) conceptual framework for testing and assessment of single and/or mixture of EDs by developing specific assays not covered by the current tests, and to propose an IATA for ED-related metabolic disorder detection, which will be submitted to the Joint Research Center (JRC) and OECD community.

Polycyclic aromatic hydrocarbons can trigger hepatocyte release of extracellular vesicles by various mechanisms of action depending on their affinity for the aryl hydrocarbon receptor

Extracellular vesicles (EVs) are membrane enclosed nanostructures released by cells into the extracellular environment. As major actors of physiological intercellular communication, they have been shown to be pathogenic mediators of several liver diseases. EVs also appear to be potential actors of drug-induced liver injury, but nothing is known concerning environmental pollutants. We aimed to study the impact of polycyclic aromatic hydrocarbons (PAHs), major contaminants, on hepatocyte-derived EV production, with a special focus on hepatocyte death. Three PAHs were selected, based on their presence in food and their affinity for the aryl hydrocarbon receptor (AhR): benzo(a)pyrene (BP), dibenzo(a,h)anthracene (DBA), and pyrene (PYR). Treatment of primary rat and WIF-B9 hepatocytes by all three PAHs increased the release of EVs, mainly comprised of exosomes, in parallel with modifying exosome protein marker expression and inducing apoptosis. Moreover, PAH treatment of rodents for three months also led to increased EV levels in plasma. The EV release involved CYP metabolism and the activation of the transcription factor, the AhR, for BP and DBA and another transcription factor, the constitutive androstane receptor (CAR), for PYR. Furthermore, all PAHs increased cholesterol levels in EVs but only BP and DBA were able to reduce the cholesterol content of total cell membranes. All cholesterol changes very likely participated in the increase in EV release and cell death. Finally, we studied changes in cell membrane fluidity caused by BP and DBA due to cholesterol depletion. Our data showed increased cell membrane fluidity, which contributed to hepatocyte EV release and cell death.

Moderate chronic ethanol consumption exerts beneficial effects on nonalcoholic fatty liver in mice fed a high-fat diet: possible role of higher formation of triglycerides enriched in monounsaturated fatty acids

PURPOSE

Several clinical studies suggested that light-to-moderate alcohol intake could alleviate nonalcoholic fatty liver disease (NAFLD), but the underlying mechanism is still poorly understood.

METHODS

Mice fed a high-fat diet (HFD) were submitted or not to moderate ethanol intake for 3 months (ca. 10 g/kg/day) via drinking water. Biochemical, analytical and transcriptomic analyses were performed in serum and liver.

RESULTS

Serum ethanol concentrations in ethanol-treated HFD mice comprised between 0.5 and 0.7 g/l throughout the experiment. NAFLD improvement was observed in ethanol-treated HFD mice as assessed by reduced serum transaminase activity. This was associated with less microvesicular and more macrovacuolar steatosis, the absence of apoptotic hepatocytes and a trend towards less fibrosis. Liver lipid analysis showed increased amounts of fatty acids incorporated in triglycerides and phospholipids, reduced proportion of palmitic acid in total lipids and higher desaturation index, thus suggesting enhanced stearoyl-coenzyme A desaturase activity. mRNA expression of several glycolytic and lipogenic enzymes was upregulated. Genome-wide expression profiling and gene set enrichment analysis revealed an overall downregulation of the expression of genes involved in collagen fibril organization and leukocyte chemotaxis and an overall upregulation of the expression of genes involved in oxidative phosphorylation and mitochondrial respiratory chain complex assembly. In addition, mRNA expression of several proteasome subunits was upregulated in ethanol-treated HFD mice.

CONCLUSIONS

Moderate chronic ethanol consumption may alleviate NAFLD by several mechanisms including the generation of non-toxic lipid species, reduced expression of profibrotic and proinflammatory genes, restoration of mitochondrial function and possible stimulation of proteasome activity.

Plasma exosomes exacerbate alcohol- and acetaminophen-induced toxicity via CYP2E1 pathway

Cellular CYP2E1 is well-known to mediate alcohol- (ALC) and acetaminophen- (APAP) induced toxicity in hepatic and extra-hepatic cells. Although exosomes have been gaining importance in understanding mechanism of intra- and inter-cellular communication, the functional role of drug metabolizing cytochrome P450 (CYP) enzymes in human plasma exosomes are yet to be explored. In our previous study, we reported that human plasma-derived exosomes contain substantial level of functional CYP2E1. In the current project, we investigated the potential role of plasma exosomal CYP2E1 in mediating ALC- and APAP-induced toxicity. We treated hepatic and extra-hepatic (monocytic) cells with exosomes ± ALC/APAP. We observed that the plasma exosomes containing CYP2E1 cargo further exacerbate ALC- and APAP-induced toxicity in both hepatic and monocytic cells. Further, both exosomes- and ALC/APAP-induced toxicity was reduced/abolished by a selective inhibitor of CYP2E1 enzyme activity (diallyl ether). However, only ALC-, but not exosome-induced toxicity was reduced/abolished by CYP2E1 siRNA. These findings suggest that ALC/APAP-induced toxicity in the presence of exosomes are mediated, at least in part, by CYP2E1 enzyme. To validate these in vitro findings, we characterized plasma exosomal contents in a binge-drinking animal model and their effect on ALC/APAP-induced toxicity in monocytic cells. Our results showed that ALC exposure caused a significant induction of the plasma exosomal CYP2E1 level in a binge drinking murine model. These exosomes containing increased levels of CYP2E1 caused significant toxicity in monocytic cells compared to exosomes derived from control mice. Overall, our results showed an important role of exosomal CYP2E1 in exacerbating ALC- and APAP-induced toxicity. The study is significant in terms of understanding the role of exosomal CYP2E1 in cell-cell interactions, and their effects on drug-induced toxicity.

Drug-induced liver injury in obesity and nonalcoholic fatty liver disease

Obesity is commonly associated with nonalcoholic fatty liver (NAFL), a benign condition characterized by hepatic lipid accumulation. However, NAFL can progress in some patients to nonalcoholic steatohepatitis (NASH) and then to severe liver lesions including extensive fibrosis, cirrhosis and hepatocellular carcinoma. The entire spectrum of these hepatic lesions is referred to as nonalcoholic fatty liver disease (NAFLD). The transition of simple fatty liver to NASH seems to be favored by several genetic and environmental factors. Different experimental and clinical investigations showed or suggested that obesity and NAFLD are able to increase the risk of hepatotoxicity of different drugs. Some of these drugs may cause more severe and/or more frequent acute liver injury in obese individuals whereas others may trigger the transition of simple fatty liver to NASH or may worsen hepatic lipid accumulation, necroinflammation and fibrosis. This review presents the available information regarding drugs that may cause a specific risk in the context of obesity and NAFLD. These drugs, which belong to different pharmacological classes, include acetaminophen, halothane, methotrexate, rosiglitazone and tamoxifen. For some of these drugs, experimental investigations confirmed the clinical observations and unveiled different pathophysiological mechanisms which may explain why these pharmaceuticals are particularly hepatotoxic in obesity and NAFLD. Because obese people often take several drugs for the treatment of different obesity-related diseases, there is an urgent need to identify the main pharmaceuticals that may cause acute liver injury on a fatty liver background or that may enhance the risk of severe chronic liver disease.

Pathogenesis of Alcoholic Liver Disease: An Update

Apart from the classic knowledge that ethanol mediates its hepatotoxicity through its metabolism to acetaldehyde, a well-known hepatotoxic molecule, recent research has elucidated several key mechanisms that potentiate ethanol's damage to the liver parenchyma, such as generation of free radicals, activation of Kupffer cells, and alterations to the human bacterial and fungal microbiome. Genetic studies have suggested the role of PNPLA3 and TM6SF2 gene mutations in the progression of alcoholic liver disease.

Mechanisms involved in the death of steatotic WIF-B9 hepatocytes co-exposed to benzo[a]pyrene and ethanol: a possible key role for xenobiotic metabolism and nitric oxide

We previously demonstrated that co-exposing pre-steatotic hepatocytes to benzo[a]pyrene (B[a]P), a carcinogenic environmental pollutant, and ethanol, favored cell death. Here, the intracellular mechanisms underlying this toxicity were studied. Steatotic WIF-B9 hepatocytes, obtained by a 48h-supplementation with fatty acids, were then exposed to B[a]P/ethanol (10 nM/5 mM, respectively) for 5 days. Nitric oxide (NO) was demonstrated to be a pivotal player in the cell death caused by the co-exposure in steatotic hepatocytes. Indeed, by scavenging NO, CPTIO treatment of co-exposed steatotic cells prevented not only the increase in DNA damage and cell death, but also the decrease in the activity of CYP1, major cytochrome P450s of B[a]P metabolism. This would then lead to an elevation of B[a]P levels, thus possibly suggesting a long-lasting stimulation of the transcription factor AhR. Besides, as NO can react with superoxide anion to produce peroxynitrite, a highly oxidative compound, the use of FeTPPS to inhibit its formation indicated its participation in DNA damage and cell death, further highlighting the important role of NO. Finally, a possible key role for AhR was pointed out by using its antagonist, CH-223191. Indeed it prevented the elevation of ADH activity, known to participate to the ethanol production of ROS, notably superoxide anion. The transcription factor, NFκB, known to be activated by ROS, was shown to be involved in the increase in iNOS expression. Altogether, these data strongly suggested cooperative mechanistic interactions between B[a]P via AhR and ethanol via ROS production, to favor cell death in the context of prior steatosis.

Possible Involvement of Mitochondrial Dysfunction and Oxidative Stress in a Cellular Model of NAFLD Progression Induced by Benzo[a]pyrene/Ethanol CoExposure

Exposure to xenobiotics could favor the transition of nonalcoholic fatty liver (NAFL) to nonalcoholic steatohepatitis in obese patients. Recently, we showed in different models of NAFL that benzo[a]pyrene (B[a]P) and ethanol coexposure induced a steatohepatitis-like state. One model was HepaRG cells incubated with stearate and oleate for 2 weeks. In the present study, we wished to determine in this model whether mitochondrial dysfunction and reactive oxygen species (ROS) overproduction could be involved in the occurrence of this steatohepatitis-like state. CRISPR/Cas9-modified cells were also used to specify the role of aryl hydrocarbon receptor (AhR), which is potently activated by B[a]P. Thus, nonsteatotic and steatotic HepaRG cells were treated with B[a]P, ethanol, or both molecules for 2 weeks. B[a]P/ethanol coexposure reduced mitochondrial respiratory chain activity, mitochondrial respiration, and mitochondrial DNA levels and induced ROS overproduction in steatotic HepaRG cells. These deleterious effects were less marked or absent in steatotic cells treated with B[a]P alone or ethanol alone and in nonsteatotic cells treated with B[a]P/ethanol. Our study also disclosed that B[a]P/ethanol-induced impairment of mitochondrial respiration was dependent on AhR activation. Hence, mitochondrial dysfunction and ROS generation could explain the occurrence of a steatohepatitis-like state in steatotic HepaRG cells exposed to B[a]P and ethanol.

Membrane Remodeling as a Key Player of the Hepatotoxicity Induced by Co-Exposure to Benzo[a]pyrene and Ethanol of Obese Zebrafish Larvae

The rise in prevalence of non-alcoholic fatty liver disease (NAFLD) constitutes an important public health concern worldwide. Including obesity, numerous risk factors of NAFLD such as benzo[a]pyrene (B[a]P) and ethanol have been identified as modifying the physicochemical properties of the plasma membrane in vitro thus causing membrane remodeling—changes in membrane fluidity and lipid-raft characteristics. In this study, the possible involvement of membrane remodeling in the in vivo progression of steatosis to a steatohepatitis-like state upon co-exposure to B[a]P and ethanol was tested in obese zebrafish larvae. Larvae bearing steatosis as the result of a high-fat diet were exposed to ethanol and/or B[a]P for seven days at low concentrations coherent with human exposure in order to elicit hepatotoxicity. In this condition, the toxicant co-exposure raised global membrane order with higher lipid-raft clustering in the plasma membrane of liver cells, as evaluated by staining with the fluoroprobe di-4-ANEPPDHQ. Involvement of this membrane’s remodeling was finally explored by using the lipid-raft disruptor pravastatin that counteracted the effects of toxicant co-exposure both on membrane remodeling and toxicity. Overall, it can be concluded that B[a]P/ethanol co-exposure can induce in vivo hepatotoxicity via membrane remodeling which could be considered as a good target mechanism for developing combination therapy to deal with steatohepatitis.