International Journal of Molecular Sciences

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4 pages, 205 KiB

Open AccessEditorial

Molecular Mechanisms of Hepatotoxicity

by Antonietta Messina and Jean-Charles Duclos-Vallée

Int. J. Mol. Sci. 2023, 24(4), 3791; https://doi.org/10.3390/ijms24043791 - 14 Feb 2023

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Abstract

Drug-induced liver injury, also known as drug-induced hepatotoxicity (DILI), is a major cause of medicine withdrawal (prescription or over-the-counter) from the market [...] Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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14 pages, 2299 KiB

Open AccessArticle

Plasma Sphingoid Base Profiles of Patients Diagnosed with Intrinsic or Idiosyncratic Drug-induced Liver Injury

by Zhibo Gai, Sophia L. Samodelov, Irina Alecu, Thorsten Hornemann, Jane I. Grove, Guruprasad P. Aithal, Michele Visentin and Gerd A. Kullak-Ublick

Int. J. Mol. Sci. 2023, 24(3), 3013; https://doi.org/10.3390/ijms24033013 - 3 Feb 2023

Cited by 3 | Viewed by 2739

Abstract

Sphingolipids are exceptionally diverse, comprising hundreds of unique species. The bulk of circulating sphingolipids are synthesized in the liver, thereby plasma sphingolipid profiles represent reliable surrogates of hepatic sphingolipid metabolism and content. As changes in plasma sphingolipid content have been associated to exposure [...] Read more.

Sphingolipids are exceptionally diverse, comprising hundreds of unique species. The bulk of circulating sphingolipids are synthesized in the liver, thereby plasma sphingolipid profiles represent reliable surrogates of hepatic sphingolipid metabolism and content. As changes in plasma sphingolipid content have been associated to exposure to drugs inducing hepatotoxicity both in vitro and in rodents, in the present study the translatability of the preclinical data was assessed by analyzing the plasma of patients with suspected drug-induced liver injury (DILI) and control subjects. DILI patients, whether intrinsic or idiosyncratic cases, had no alterations in total sphingoid base levels and profile composition compared to controls, whereby cardiovascular disease (CVD) was a confounding factor. Upon exclusion of CVD individuals, elevation of 1-deoxysphingosine (1-deoxySO) in the DILI group emerged. Notably, 1-deoxySO values did not correlate with ALT values. While 1-deoxySO was elevated in all DILI cases, only intrinsic DILI cases concomitantly displayed reduction of select shorter chain sphingoid bases. Significant perturbation of the sphingolipid metabolism observed in this small exploratory clinical study is discussed and put into context, in the consideration that sphingolipids might contribute to the onset and progression of DILI, and that circulating sphingoid bases may function as mechanistic markers to study DILI pathophysiology. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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17 pages, 2488 KiB

Open AccessArticle

Methotrexate-Induced Liver Injury Is Associated with Oxidative Stress, Impaired Mitochondrial Respiration, and Endoplasmic Reticulum Stress In Vitro

by Saskia Schmidt, Catherine Jane Messner, Carine Gaiser, Carina Hämmerli and Laura Suter-Dick

Int. J. Mol. Sci. 2022, 23(23), 15116; https://doi.org/10.3390/ijms232315116 - 1 Dec 2022

Cited by 12 | Viewed by 4753

Abstract

Low-dose methotrexate (MTX) is a standard therapy for rheumatoid arthritis due to its low cost and efficacy. Despite these benefits, MTX has been reported to cause chronic drug-induced liver injury, namely liver fibrosis. The hallmark of liver fibrosis is excessive scarring of liver [...] Read more.

Low-dose methotrexate (MTX) is a standard therapy for rheumatoid arthritis due to its low cost and efficacy. Despite these benefits, MTX has been reported to cause chronic drug-induced liver injury, namely liver fibrosis. The hallmark of liver fibrosis is excessive scarring of liver tissue, triggered by hepatocellular injury and subsequent activation of hepatic stellate cells (HSCs). However, little is known about the precise mechanisms through which MTX causes hepatocellular damage and activates HSCs. Here, we investigated the mechanisms leading to hepatocyte injury in HepaRG and used immortalized stellate cells (hTERT-HSC) to elucidate the mechanisms leading to HSC activation by exposing mono- and co-cultures of HepaRG and hTERT-HSC to MTX. The results showed that at least two mechanisms are involved in MTX-induced toxicity in HepaRG: (i) oxidative stress through depletion of glutathione (GSH) and (ii) impairment of cellular respiration in a GSH-independent manner. Furthermore, we measured increased levels of endoplasmic reticulum (ER) stress in activated HSC following MTX treatment. In conclusion, we established a human-relevant in vitro model to gain mechanistical insights into MTX-induced hepatotoxicity, linked oxidative stress in HepaRG to a GSH-dependent and -independent pathway, and hypothesize that not only oxidative stress in hepatocytes but also ER stress in HSCs contribute to MTX-induced activation of HSCs. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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13 pages, 1407 KiB

Open AccessArticle

Characterization of the RAS/RAF/ERK Signal Cascade as a Novel Regulating Factor in Alpha-Amanitin-Induced Cytotoxicity in Huh-7 Cells

by Doeun Kim, Min Seo Lee, Eunji Sung, Sangkyu Lee and Hye Suk Lee

Int. J. Mol. Sci. 2022, 23(20), 12294; https://doi.org/10.3390/ijms232012294 - 14 Oct 2022

Cited by 4 | Viewed by 2043

Abstract

The well-known hepatotoxicity mechanism resulting from alpha-amanitin (α-AMA) exposure arises from RNA polymerase II (RNAP II) inhibition. RNAP Ⅱ inhibition occurs through the dysregulation of mRNA synthesis. However, the signaling pathways in hepatocytes that arise from α-AMA have not yet been fully elucidated. [...] Read more.

The well-known hepatotoxicity mechanism resulting from alpha-amanitin (α-AMA) exposure arises from RNA polymerase II (RNAP II) inhibition. RNAP Ⅱ inhibition occurs through the dysregulation of mRNA synthesis. However, the signaling pathways in hepatocytes that arise from α-AMA have not yet been fully elucidated. Here, we identified that the RAS/RAF/ERK signaling pathway was activated through quantitative phosphoproteomic and molecular biological analyses in Huh-7 cells. Bioinformatics analysis showed that α-AMA exposure increased protein phosphorylation in a time-dependent α-AMA exposure. In addition, phosphorylation increased not only the components of the ERK signaling pathway but also U2AF65 and SPF45, known splicing factors. Therefore, we propose a novel mechanism of α-AMA as follows. The RAS/RAF/ERK signaling pathway involved in aberrant splicing events is activated by α-AMA exposure followed by aberrant splicing events leading to cell death in Huh-7 cells. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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20 pages, 2812 KiB

Open AccessArticle

Possible Role of Extracellular Vesicles in Hepatotoxicity of Acetaminophen

by Martina Šrajer Gajdošik, Anamarija Kovač Peić, Marija Begić, Petra Grbčić, Kate E. Brilliant, Douglas C. Hixson and Djuro Josić

Int. J. Mol. Sci. 2022, 23(16), 8870; https://doi.org/10.3390/ijms23168870 - 9 Aug 2022

Cited by 3 | Viewed by 2417

Abstract

We examined proteomic profiles of rat liver extracellular vesicles (EVs) shed following treatment with a sub-toxic dose (500 mg/kg) of the pain reliever drug, acetaminophen (APAP). EVs representing the entire complement of hepatic cells were isolated after perfusion of the intact liver and [...] Read more.

We examined proteomic profiles of rat liver extracellular vesicles (EVs) shed following treatment with a sub-toxic dose (500 mg/kg) of the pain reliever drug, acetaminophen (APAP). EVs representing the entire complement of hepatic cells were isolated after perfusion of the intact liver and analyzed with LC-MS/MS. The investigation was focused on revealing the function and cellular origin of identified EVs proteins shed by different parenchymal and non-parenchymal liver cells and their possible role in an early response of this organ to a toxic environment. Comparison of EV proteomic profiles from control and APAP-treated animals revealed significant differences. Alpha-1-macroglobulin and members of the cytochrome P450 superfamily were highly abundant proteins in EVs shed by the normal liver. In contrast, proteins like aminopeptidase N, metalloreductase STEAP4, different surface antigens like CD14 and CD45, and most members of the annexin family were detected only in EVs that were shed by livers of APAP-treated animals. In EVs from treated livers, there was almost a complete disappearance of members of the cytochrome P450 superfamily and a major decrease in other enzymes involved in the detoxification of xenobiotics. Additionally, there were proteins that predominated in non-parenchymal liver cells and in the extracellular matrix, like fibronectin, receptor-type tyrosine-protein phosphatase C, and endothelial type gp91. These differences indicate that even treatment with a sub-toxic concentration of APAP initiates dramatic perturbation in the function of this vital organ. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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16 pages, 4146 KiB

Open AccessArticle

Hepatocyte Specific gp130 Signalling Underlies APAP Induced Liver Injury

by Jinrui Dong, Wei-Wen Lim, Shamini G. Shekeran, Jessie Tan, Sze Yun Lim, Joyce Wei Ting Goh, Benjamin L. George, Sebastian Schafer, Stuart A. Cook and Anissa A. Widjaja

Int. J. Mol. Sci. 2022, 23(13), 7089; https://doi.org/10.3390/ijms23137089 - 25 Jun 2022

Cited by 6 | Viewed by 3128

Abstract

N-acetyl-p-aminophenol (APAP)-induced liver damage is associated with upregulation of Interleukin-11 (IL11), which is thought to stimulate IL6ST (gp130)-mediated STAT3 activity in hepatocytes, as a compensatory response. However, recent studies have found IL11/IL11RA/gp130 signaling to be hepatotoxic. To investigate further the role of IL11 [...] Read more.

N-acetyl-p-aminophenol (APAP)-induced liver damage is associated with upregulation of Interleukin-11 (IL11), which is thought to stimulate IL6ST (gp130)-mediated STAT3 activity in hepatocytes, as a compensatory response. However, recent studies have found IL11/IL11RA/gp130 signaling to be hepatotoxic. To investigate further the role of IL11 and gp130 in APAP liver injury, we generated two new mouse strains with conditional knockout (CKO) of either Il11 (CKO^Il11) or gp130 (CKO^gp130) in adult hepatocytes. Following APAP, as compared to controls, CKO^gp130 mice had lesser liver damage with lower serum Alanine Transaminase (ALT) and Aspartate Aminotransferase (AST), greatly reduced serum IL11 levels (90% lower), and lesser centrilobular necrosis. Livers from APAP-injured CKO^gp130 mice had lesser ERK, JNK, NOX4 activation and increased markers of regeneration (PCNA, Cyclin D1, Ki67). Experiments were repeated in CKO^Il11 mice that, as compared to wild-type mice, had lower APAP-induced ALT/AST, reduced centrilobular necrosis and undetectable IL11 in serum. As seen with CKO^gp130 mice, APAP-treated CKO^Il11 mice had lesser ERK/JNK/NOX4 activation and greater features of regeneration. Both CKO^gp130 and CKO^Il11 mice had normal APAP metabolism. After APAP, CKO^gp130 and CKO^Il11 mice had reduced Il6, Ccl2, Ccl5, Il1β, and Tnfα expression. These studies exclude IL11 upregulation as compensatory and establish autocrine, self-amplifying, gp130-dependent IL11 secretion from damaged hepatocytes as toxic and anti-regenerative. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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14 pages, 7264 KiB

Open AccessArticle

Silencing the Tlr4 Gene Alleviates Methamphetamine-Induced Hepatotoxicity by Inhibiting Lipopolysaccharide-Mediated Inflammation in Mice

by Li-Bin Wang, Li-Jian Chen, Qi Wang and Xiao-Li Xie

Int. J. Mol. Sci. 2022, 23(12), 6810; https://doi.org/10.3390/ijms23126810 - 18 Jun 2022

Cited by 9 | Viewed by 2479

Abstract

Methamphetamine (METH) is a stimulant drug. METH abuse induces hepatotoxicity, although the mechanisms are not well understood. METH-induced hepatotoxicity was regulated by TLR4-mediated inflammation in BALB/c mice in our previous study. To further investigate the underlying mechanisms, the wild-type (C57BL/6) and Tlr4^−/− [...] Read more.

Methamphetamine (METH) is a stimulant drug. METH abuse induces hepatotoxicity, although the mechanisms are not well understood. METH-induced hepatotoxicity was regulated by TLR4-mediated inflammation in BALB/c mice in our previous study. To further investigate the underlying mechanisms, the wild-type (C57BL/6) and Tlr4^−/− mice were treated with METH. Transcriptomics of the mouse liver was performed via RNA-sequencing. Histopathological changes, serum levels of metabolic enzymes and lipopolysaccharide (LPS), and expression of TLR4-mediated proinflammatory cytokines were assessed. Compared to the control, METH treatment induced obvious histopathological changes and significantly increased the levels of metabolic enzymes in wild-type mice. Furthermore, inflammatory pathways were enriched in the liver of METH-treated mice, as demonstrated by expression analysis of RNA-sequencing data. Consistently, the expression of TLR4 pathway members was significantly increased by METH treatment. In addition, increased serum LPS levels in METH-treated mice indicated overproduction of LPS and gut microbiota dysbiosis. However, antibiotic pretreatment or silencing Tlr4 significantly decreased METH-induced hepatic injury, serum LPS levels, and inflammation. In addition, the dampening effects of silencing Tlr4 on inflammatory pathways were verified by the enrichment analysis of RNA-sequencing data in METH-treated Tlr4^−/− mice compared to METH-treated wild-type mice. Taken together, these findings implied that Tlr4 silencing, comparable to antibiotic pretreatment, effectively alleviated METH-induced hepatotoxicity by inhibiting LPS-TLR4-mediated inflammation in the liver. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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Review

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19 pages, 1511 KiB

Open AccessReview

The Farnesoid X Receptor as a Master Regulator of Hepatotoxicity

by Magdalena Rausch, Sophia L. Samodelov, Michele Visentin and Gerd A. Kullak-Ublick

Int. J. Mol. Sci. 2022, 23(22), 13967; https://doi.org/10.3390/ijms232213967 - 12 Nov 2022

Cited by 11 | Viewed by 3416

Abstract

The nuclear receptor farnesoid X receptor (FXR, NR1H4) is a bile acid (BA) sensor that links the enterohepatic circuit that regulates BA metabolism and elimination to systemic lipid homeostasis. Furthermore, FXR represents a real guardian of the hepatic function, preserving, in a multifactorial [...] Read more.

The nuclear receptor farnesoid X receptor (FXR, NR1H4) is a bile acid (BA) sensor that links the enterohepatic circuit that regulates BA metabolism and elimination to systemic lipid homeostasis. Furthermore, FXR represents a real guardian of the hepatic function, preserving, in a multifactorial fashion, the integrity and function of hepatocytes from chronic and acute insults. This review summarizes how FXR modulates the expression of pathway-specific as well as polyspecific transporters and enzymes, thereby acting at the interface of BA, lipid and drug metabolism, and influencing the onset and progression of hepatotoxicity of varying etiopathogeneses. Furthermore, this review article provides an overview of the advances and the clinical development of FXR agonists in the treatment of liver diseases. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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30 pages, 1401 KiB

Open AccessReview

In Vitro Models for Studying Chronic Drug-Induced Liver Injury

by M. Teresa Donato, Gloria Gallego-Ferrer and Laia Tolosa

Int. J. Mol. Sci. 2022, 23(19), 11428; https://doi.org/10.3390/ijms231911428 - 28 Sep 2022

Cited by 15 | Viewed by 5370

Abstract

Drug-induced liver injury (DILI) is a major clinical problem in terms of patient morbidity and mortality, cost to healthcare systems and failure of the development of new drugs. The need for consistent safety strategies capable of identifying a potential toxicity risk early in [...] Read more.

Drug-induced liver injury (DILI) is a major clinical problem in terms of patient morbidity and mortality, cost to healthcare systems and failure of the development of new drugs. The need for consistent safety strategies capable of identifying a potential toxicity risk early in the drug discovery pipeline is key. Human DILI is poorly predicted in animals, probably due to the well-known interspecies differences in drug metabolism, pharmacokinetics, and toxicity targets. For this reason, distinct cellular models from primary human hepatocytes or hepatoma cell lines cultured as 2D monolayers to emerging 3D culture systems or the use of multi-cellular systems have been proposed for hepatotoxicity studies. In order to mimic long-term hepatotoxicity in vitro, cell models, which maintain hepatic phenotype for a suitably long period, should be used. On the other hand, repeated-dose administration is a more relevant scenario for therapeutics, providing information not only about toxicity, but also about cumulative effects and/or delayed responses. In this review, we evaluate the existing cell models for DILI prediction focusing on chronic hepatotoxicity, highlighting how better characterization and mechanistic studies could lead to advance DILI prediction. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Hepatotoxicity)

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