Drug-induced liver injury through mitochondrial dysfunction: mechanisms and detection during preclinical safety studies

NIR-excited imaging of drug-induced liver injury using a superoxide-activated ratiometric upconversion luminescence nanoprobe

Drug-induced liver injury (DILI) poses a significant risk to human health. Increasing evidence indicates that the superoxide anion (O2•-), as the precursor of the other reactive oxygen species, is key in the pathological processes associated with DILI. Nonetheless, understanding of the mechanisms of DILI is difficult due to the lack of an imaging tool for monitoring the fluctuation of O2•- levels during the progression of DILI. Herein, we developed an upconversion nanoprobe (Rbh-UCNs) for in vivo ratiometric tracking of endogenous O2•- in DILI. In this design, the addition of O2•- triggers the luminescent resonance energy transfer between Rbh and UCNs, which significantly enhances absorption centered at 534 nm and translates into a distinct decrease of the UCL emission at 543 nm, while the UCL emission peak at 654 nm and 800 nm are not significantly affected, offering a ratiometric UCL signal for the quantitative detection of O2•-. In addition, Rbh-UCNs could effectively visualize endogenous O2•- in living cells, zebrafish, and liver tissues upon stimulation with PMA or cisplatin. More importantly, tissue imaging of the liver region of mice revealed that the fluctuation of O2•- levels is associated with DILI and the protective effect of L-carnitine against DILI. Altogether, this study provides an available method for a deeper comprehension of the mechanisms underlying DILI and accelerating the development process of hepatoprotective medicines.

An evaluation model of hepatic steatosis based on CT value and serum uric acid/HDL cholesterol ratio can predict intrahepatic recurrence of colorectal cancer liver metastasis

BACKGROUND

Intrahepatic recurrence is one of the main causes of treatment failure in patients with colorectal cancer liver metastasis (CRLM). Hepatic steatosis was reported to provide fertile soil for metastasis. The effect of irinotecan-inducted hepatic steatosis on the progression of liver metastasis remains to be verified. Therefore, we aim to clarify the effect of hepatic steatosis on postoperative intrahepatic recurrence in CRLM and whether it is relevant to irinotecan-based chemotherapy.

METHODS

Data for a total of 284 patients undergoing curative surgical treatment for CRLMs were retrospectively reviewed between March 2007 and June 2018. Hepatic steatosis score (HSS) was established by combining Liver to Spleen CT ratio (LSR) and Uric acid to HDL-cholesterol ratio (UHR) to detect the presence of hepatic steatosis.

RESULTS

The evaluation model is consistent with pathological results and has high prediction ability and clinical application value. Patients with HSS high risk (HSS-HR) had significantly worse prognosis than those with HSS low risk (HSS-LR) (3-year intrahepatic RFS: 42.7% vs. 29.4%, P = 0.003; 5-year OS: 45.7% vs. 26.5%, P = 0.002). Univariate and multivariate analysis confirmed its essential role in the prediction of intrahepatic RFS. Besides, patients treated with preoperative irinotecan chemotherapy were more likely to end up with HSS-HR than those with non-irinotecan chemotherapy (63.3% vs. 21.8%, P < 0.001). Furthermore, irinotecan chemotherapy is relevant to worse prognosis in baseline HSS-HR patients.

CONCLUSION

In summary, patients with HSS-HR had significantly worse 5-year OS and 3-year intrahepatic RFS. Irinotecan chemotherapy is more likely to lead to HSS-HR and pre-existing hepatic steatosis may be a worse prognostic factor limiting patients underwent IRI-based chemotherapy.

Steatotic liver disease in the context of hematological malignancies and anti-neoplastic chemotherapy

The rising prevalence of obesity-related illnesses, such as metabolic steatotic liver disease (MASLD), represents a significant global public health concern. This disease affects approximately 30 % of the adult population and is the result of metabolic abnormalities rather than alcohol consumption. Additionally, MASLD is associated with an increased risk of cardiovascular disease (CVD), chronic liver disease, and a variety of cancers, particularly gastrointestinal cancers. Clonal hematopoiesis (CH) is a biological state characterized by the expansion of a population of blood cells derived from a single mutated hematopoietic stem cell. The presence of CH in the absence of a diagnosed blood disorder or cytopenia is known as clonal hematopoiesis of indeterminate potential (CHIP), which itself increases the risk of hematological malignancies and CVD. Steatotic liver disease may also complicate the clinical course of cancer patients receiving antineoplastic agents, a condition referred to as chemotherapy induced steatohepatitis (CASH). This review will present an outline of the various aspects of MASLD, including complications. Furthermore, it will summarize the existing knowledge on the emerging association between CHIP and MASLD and present the available data on patient cases with concurrent MASLD and hematological neoplasms. Finally, it will provide a brief overview of the chemotherapeutic drugs associated with CASH, the underlying pathophysiologic mechanisms and their clinical implications.

MICOS Complex Loss Governs Age-Associated Murine Mitochondrial Architecture and Metabolism in the Liver, While Sam50 Dictates Diet Changes

The liver, the largest internal organ and a metabolic hub, undergoes significant declines due to aging, affecting mitochondrial function and increasing the risk of systemic liver diseases. How the mitochondrial three-dimensional (3D) structure changes in the liver across aging, and the biological mechanisms regulating such changes confers remain unclear. In this study, we employed Serial Block Face-Scanning Electron Microscopy (SBF-SEM) to achieve high-resolution 3D reconstructions of murine liver mitochondria to observe diverse phenotypes and structural alterations that occur with age, marked by a reduction in size and complexity. We also show concomitant metabolomic and lipidomic changes in aged samples. Aged human samples reflected altered disease risk. To find potential regulators of this change, we examined the Mitochondrial Contact Site and Cristae Organizing System (MICOS) complex, which plays a crucial role in maintaining mitochondrial architecture. We observe that the MICOS complex is lost during aging, but not Sam50. Sam50 is a component of the sorting and assembly machinery (SAM) complex that acts in tandem with the MICOS complex to modulate cristae morphology. In murine models subjected to a high-fat diet, there is a marked depletion of the mitochondrial protein SAM50. This reduction in Sam50 expression may heighten the susceptibility to liver disease, as our human biobank studies corroborate that Sam50 plays a genetically regulated role in the predisposition to multiple liver diseases. We further show that changes in mitochondrial calcium dysregulation and oxidative stress accompany the disruption of the MICOS complex. Together, we establish that a decrease in mitochondrial complexity and dysregulated metabolism occur with murine liver aging. While these changes are partially be regulated by age-related loss of the MICOS complex, the confluence of a murine high-fat diet can also cause loss of Sam50, which contributes to liver diseases. In summary, our study reveals potential regulators that affect age-related changes in mitochondrial structure and metabolism, which can be targeted in future therapeutic techniques.

Hybrid non-animal modeling: A mechanistic approach to predict chemical hepatotoxicity

Developing mechanistic non-animal testing methods based on the adverse outcome pathway (AOP) framework must incorporate molecular and cellular key events associated with target toxicity. Using data from an in vitro assay and chemical structures, we aimed to create a hybrid model to predict hepatotoxicants. We first curated a reference dataset of 869 compounds for hepatotoxicity modeling. Then, we profiled them against PubChem for existing in vitro toxicity data. Of the 2560 resulting assays, we selected the mitochondrial membrane potential (MMP) assay, a high-throughput screening (HTS) tool that can test chemical disruptors for mitochondrial function. Machine learning was applied to develop quantitative structure-activity relationship (QSAR) models with 2536 compounds tested in the MMP assay for screening new compounds. The MMP assay results, including QSAR model outputs, yielded hepatotoxicity predictions for reference set compounds with a Correct Classification Ratio (CCR) of 0.59. The predictivity improved by including 37 structural alerts (CCR = 0.8). We validated our model by testing 37 reference set compounds in human HepG2 hepatoma cells, and reliably predicting them for hepatotoxicity (CCR = 0.79). This study introduces a novel AOP modeling strategy that combines public HTS data, computational modeling, and experimental testing to predict chemical hepatotoxicity.

Drug-Induced Fatty Liver Disease (DIFLD): A Comprehensive Analysis of Clinical, Biochemical, and Histopathological Data for Mechanisms Identification and Consistency with Current Adverse Outcome Pathways

Drug induced fatty liver disease (DIFLD) is a form of drug-induced liver injury (DILI), which can also be included in the more general metabolic dysfunction-associated steatotic liver disease (MASLD), which specifically refers to the accumulation of fat in the liver unrelated to alcohol intake. A bi-directional relationship between DILI and MASLD is likely to exist: while certain drugs can cause MASLD by acting as pro-steatogenic factors, MASLD may make hepatocytes more vulnerable to drugs. Having a pre-existing MASLD significantly heightens the likelihood of experiencing DILI from certain medications. Thus, the prevalence of steatosis within DILI may be biased by pre-existing MASLD, and it can be concluded that the genuine true incidence of DIFLD in the general population remains unknown. In certain individuals, drug-induced steatosis is often accompanied by concomitant injury mechanisms such as oxidative stress, cell death, and inflammation, which leads to the development of drug-induced steatohepatitis (DISH). DISH is much more severe from the clinical point of view, has worse prognosis and outcome, and resembles MASH (metabolic-associated steatohepatitis), as it is associated with inflammation and sometimes with fibrosis. A literature review of clinical case reports allowed us to examine and evaluate the clinical features of DIFLD and their association with specific drugs, enabling us to propose a classification of DIFLD drugs based on clinical outcomes and pathological severity: Group 1, drugs with low intrinsic toxicity (e.g., ibuprofen, naproxen, acetaminophen, irinotecan, methotrexate, and tamoxifen), but expected to promote/aggravate steatosis in patients with pre-existing MASLD; Group 2, drugs associated with steatosis and only occasionally with steatohepatitis (e.g., amiodarone, valproic acid, and tetracycline); and Group 3, drugs with a great tendency to transit to steatohepatitis and further to fibrosis. Different mechanisms may be in play when identifying drug mode of action: (1) inhibition of mitochondrial fatty acid β-oxidation; (2) inhibition of fatty acid transport across mitochondrial membranes; (3) increased de novo lipid synthesis; (4) reduction in lipid export by the inhibition of microsomal triglyceride transfer protein; (5) induction of mitochondrial permeability transition pore opening; (6) dissipation of the mitochondrial transmembrane potential; (7) impairment of the mitochondrial respiratory chain/oxidative phosphorylation; (8) mitochondrial DNA damage, degradation and depletion; and (9) nuclear receptors (NRs)/transcriptomic alterations. Currently, the majority of, if not all, adverse outcome pathways (AOPs) for steatosis in AOP-Wiki highlight the interaction with NRs or transcription factors as the key molecular initiating event (MIE). This perspective suggests that chemical-induced steatosis typically results from the interplay between a chemical and a NR or transcription factors, implying that this interaction represents the primary and pivotal MIE. However, upon conducting this exhaustive literature review, it became evident that the current AOPs tend to overly emphasize this interaction as the sole MIE. Some studies indeed support the involvement of NRs in steatosis, but others demonstrate that such NR interactions alone do not necessarily lead to steatosis. This view, ignoring other mitochondrial-related injury mechanisms, falls short in encapsulating the intricate biological mechanisms involved in chemically induced liver steatosis, necessitating their consideration as part of the AOP's map road as well.

Effects of toxicants on endoplasmic reticulum stress and hepatic cell fate determination

Toxicant-induced injury is a significant global health issue. However, the mechanisms through which toxicants such as carbon tetrachloride, acetaminophen, dimethylformamide, cocaine, and morphine induce the death of multiple cell types and contribute to liver toxicity are highly complex. This phenomenon involves intricate signaling pathways in association with oxidative stress, inflammation, and activation of death receptors, which are closely linked to endoplasmic reticulum (ER) stress. ER stress initially triggers the unfolded protein response, which either promotes cell survival or causes cell death at later times, depending on the severity and duration of the stress. Thus, comprehending the molecular basis governing cell fate determination in the context of ER stress may provide key insights into the prevention and treatment of toxicant-induced injury. This review summarizes our current understanding of agents that trigger different forms of ER stress-mediated cell death, necroptosis, ferroptosis, pyroptosis, and apoptosis, and covers the underlying molecular basis of toxicant-induced ER stress, as well as potential target molecules.

Elucidation of the relationship between evodiamine-induced liver injury and CYP3A4-mediated metabolic activation by UPLC-MS/MS analysis

Evodiamine (EVD), which has been reported to cause liver damage, is the main constituent of Evodia rutaecarpa (Juss.) Benth and may be bioactivated into reactive metabolites mediated by cytochrome P450. However, the relationships between bioactivation and EVD-induced hepatotoxicity remain unknown. In this study, comprehensive hepatotoxicity evaluation was explored, which demonstrated that EVD caused hepatotoxicity in both time- and dose-dependent manners in mice. By application of UPLC-Q/TOF-MS/MS, two GSH conjugates (GM1 and GM2) derived from reactive metabolites of EVD were identified, in microsomal incubation systems exposed to EVD with glutathione (GSH) as trapping agents. CYP3A4 was proved to be the main metabolic enzyme. Correspondingly, the N-acetyl-L-cysteine conjugate derived from the degradation of GM2 was detected in the urine of mice after exposure to EVD. For the first time, the iminoquinone intermediate was found in EVD-pretreated rat bile by the high-resolution MS platform. Pretreatment with ketoconazole protected the animals from hepatotoxicity, decreased the protein expression of cleaved caspase-1 and -3, but increased the area under the serum-concentration-time curve of EVD in blood determined by UPLC-QQQ-MS/MS. Depletion of GSH by buthionine sulfoximine exacerbated EVD-induced hepatotoxicity. These results implicated that the CYP3A4-mediated metabolic activation was responsible for the observed hepatotoxicity induced by EVD.

Microphysiological Models for Mechanistic-Based Prediction of Idiosyncratic DILI

Drug-induced liver injury (DILI) is a major contributor to high attrition rates among candidate and market drugs and a key regulatory, industry, and global health concern. While acute and dose-dependent DILI, namely, intrinsic DILI, is predictable and often reproducible in preclinical models, the nature of idiosyncratic DILI (iDILI) limits its mechanistic understanding due to the complex disease pathogenesis, and recapitulation using in vitro and in vivo models is extremely challenging. However, hepatic inflammation is a key feature of iDILI primarily orchestrated by the innate and adaptive immune system. This review summarizes the in vitro co-culture models that exploit the role of the immune system to investigate iDILI. Particularly, this review focuses on advancements in human-based 3D multicellular models attempting to supplement in vivo models that often lack predictability and display interspecies variations. Exploiting the immune-mediated mechanisms of iDILI, the inclusion of non-parenchymal cells in these hepatoxicity models, namely, Kupffer cells, stellate cells, dendritic cells, and liver sinusoidal endothelial cells, introduces heterotypic cell-cell interactions and mimics the hepatic microenvironment. Additionally, drugs recalled from the market in the US between 1996-2010 that were studies in these various models highlight the necessity for further harmonization and comparison of model characteristics. Challenges regarding disease-related endpoints, mimicking 3D architecture with different cell-cell contact, cell source, and the underlying multi-cellular and multi-stage mechanisms are described. It is our belief that progressing our understanding of the underlying pathogenesis of iDILI will provide mechanistic clues and a method for drug safety screening to better predict liver injury in clinical trials and post-marketing.

Development and Recovery of Liver Injury in Piglets by Incremental Injection of LPS

This study aimed to explore the effects of the incremental injection of lipopolysaccharide (LPS) on liver histopathology, inflammation, oxidative status, and mitochondrial function in piglets. Forty healthy Duroc × Landrace × Yorkshire castrated boars (21 ± 2 days old, weight 6.84 ± 0.11 kg) were randomly assigned to five groups (n = 8) and then slaughtered on days 0 (group 0, without LPS injection), 1 (group 1), 5 (group 5), 9 (group 9), and 15 (group 15) of LPS injection, respectively. The results showed that, compared to the piglets without LPS injection, LPS injection caused liver injury in the early phase, as manifested by the increased activities of serum liver injury-related parameters (aspartate amino transferase, alanine aminotransferase, alkaline phosphatase, cholinesterase, and total bile acid) on day 1, and impaired liver morphology (disordered hepatic cell cord arrangement, dissolved and vacuolized hepatocytes, karyopycnosis, and inflammatory cell infiltration and congestion) on days 1 and 5. Meanwhile, LPS injection caused liver inflammation, oxidative stress, and mitochondrial dysfunction on days 1 and 5, as reflected by the upregulated mRNA expression of TNF-α, IL-6, IL-1β, TLR4, MyD88, and NF-κB; increased MPO and MDA content; and impaired mitochondrial morphology. However, these parameters were ameliorated in the later phase (days 9~15). Taken together, our data indicate that the incremental injection of the LPS-induced liver injury of piglets could be self-repaired.

Metabolomics-based strategy to assess drug hepatotoxicity and uncover the mechanisms of hepatotoxicity involved

Toxicity studies, among them hepatotoxicity, are key throughout preclinical stages of drug development to minimise undesired toxic effects that might eventually appear in the course of the clinical use of the new drug. Understanding the mechanism of injury of hepatotoxins is essential to efficiently anticipate their potential risk of toxicity in humans. The use of in vitro models and particularly cultured hepatocytes represents an easy and robust alternative to animal drug hepatotoxicity testing for predicting human risk. Here, we envisage an innovative strategy to identify potential hepatotoxic drugs, quantify the magnitude of the alterations caused, and uncover the mechanisms of toxicity. This strategy is based on the comparative analysis of metabolome changes induced by hepatotoxic and non-hepatotoxic compounds on HepG2 cells, assessed by untargeted mass spectrometry. As a training set, we used 25 hepatotoxic and 4 non-hepatotoxic compounds and incubated HepG2 cells for 24 h at a low and a high concentration (IC10 and IC50) to identify mechanism-related and cytotoxicity related metabolomic biomarkers and to elaborate prediction models accounting for global hepatotoxicity and mechanisms-related toxicity. Thereafter, a second set of 69 chemicals with known predominant mechanisms of toxicity and 18 non-hepatotoxic compounds were analysed at 1, 10, 100 and 1000 µM concentrations from which and based on the magnitude of the alterations caused as compared with non-toxic compounds, we defined a "toxicity index" for each compound. In addition, we extracted from the metabolome data the characteristic signatures for each mechanism of hepatotoxicity. The integration of all this information allowed us to identify specific metabolic patterns and, based on the occurrence of that specific metabolome changes, the models predicted the likeliness of a compound to behave as hepatotoxic and to act through a given toxicity mechanism (i.e., oxidative stress, mitochondrial disruption, apoptosis and steatosis) for each compound and concentration.

Lipopolysaccharide administration increases the susceptibility of mitochondrial permeability transition pore opening via altering adenine nucleotide translocase conformation in the mouse liver

Lipopolysaccharide (LPS), a component of the outer membrane of gram-negative bacteria, induces various biological reactions in vivo. Our previous study suggested that LPS administration disrupts respiratory chain complex activities, enhances reactive oxygen species production, especially in the liver mitochondria, and sensitizes mitochondrial permeability transition (MPT) pore opening in rats. However, it is unknown whether LPS-induced MPT pore opening in rats is similarly observed in mice and whether the mechanism is the same. LPS administration to mice increased not only cyclosporin A-sensitive swelling (MPT pore opening) susceptibility, but also induced cyclosporin A-insensitive basal swelling, unlike in rats. In addition, respiratory activity observed after adding ADP was significantly decreased. Based on these results, we further investigated the role of adenine nucleotide translocase (ANT). Carboxyatractyloside (CATR; an ANT inhibitor) treatment decreased respiratory activity after ADP was added in vehicle-treated mitochondria similarly to LPS administration. Additionally, CATR treatment increased MPT pore opening susceptibility in LPS-treated mitochondria compared to that of vehicle-treated mitochondria. Our study shows that ANT maintained a c-state conformation upon LPS administration, which increased MPT pore opening susceptibility in mice. These results suggest that LPS enhances MPT pore opening susceptibility across species, but the mechanism may differ between rat and mouse.

Using chemical and biological data to predict drug toxicity

Various sources of information can be used to better understand and predict compound activity and safety-related endpoints, including biological data such as gene expression and cell morphology. In this review, we first introduce types of chemical, in vitro and in vivo information that can be used to describe compounds and adverse effects. We then explore how compound descriptors based on chemical structure or biological perturbation response can be used to predict safety-related endpoints, and how especially biological data can help us to better understand adverse effects mechanistically. Overall, the described applications demonstrate how large-scale biological information presents new opportunities to anticipate and understand the biological effects of compounds, and how this can support predictive toxicology and drug discovery projects.

Psoraleae Fructus Ethanol Extract Induced Hepatotoxicity via Impaired Lipid Metabolism Caused by Disruption of Fatty Acid β-Oxidation

Herb-induced liver injury (HILI) is gradually increasing, and Psoraleae Fructus (PF) has been reported to induce hepatotoxicity. However, its underlying toxicity mechanism has been only poorly revealed. In this paper, we attempted to explore the liver injury and mechanism caused by Psoraleae Fructus ethanol extract (PFE). First, we administered PFE to mice for 4 weeks and evaluated their serum liver function indices. H&E staining was performed to observe the pathological changes of the livers. Oil red O staining was used to visualize hepatic lipids. Serum-untargeted metabolomics and liver proteomics were used to explore the mechanism of PF hepatotoxicity, and transmission electron microscopy was determined to assess mitochondria and western blot to determine potential target proteins expression. The results showed that PFE caused abnormal liver biochemical indicators and liver tissue injury in mice, and there was substantial fat accumulation in liver tissue in this group. Furthermore, metabolomic analysis showed that PFE changed bile acid synthesis, lipid metabolism, etc., and eight metabolites, including linoleic acid, which could be used as potential biomarkers of PFE hepatotoxicity. Proteomic analysis revealed that differential proteins were clustered in the mitochondrial transmembrane transport, the long-chain fatty acid metabolic process and purine ribonucleotide metabolic process. Multiomics analysis showed that eight pathways were enriched in both metabolomics and proteomics, such as bile secretion, unsaturated fatty acid biosynthesis, and linoleic acid metabolism. The downregulation of SLC27A5, CPT1A, NDUFB5, and COX6A1 and upregulation of cytochrome C and ABCC3 expressions also confirmed the impaired fatty acid oxidative catabolism. Altogether, this study revealed that PFE induced hepatotoxicity by damaging mitochondria, reducing fatty acid β-oxidation levels, and inhibiting fatty acids ingested by bile acids.

Standardization and validation of novel ex-vivo method for mitochondrial bioenergetics using mitochondrial modulators

Mitochondria is an essential organelle; it produces 95% of the adenine triphosphate (ATP) of cells, their dysfunction is related to the pathogenesis of multiple diseases, such as diabetes mellitus, cardiovascular and neurological disorders. Various pharmacologic agents are known to target mitochondrial function. Moreover, the toxic side effects of multiple drugs used to treat diseases are related to the impairment of mitochondrial function. Thus, there is a need to develop a method to evaluate the effect of pharmacologic agents for their potential and side effects to identify effective mitochondrial-modulating agents. Therefore, the objective of this study was to develop and validate an ex-vivo method for studying the effect of pharmacologic agents on mitochondrial function and rescue of dysfunction. Dimethyl sulfoxide (DMSO) concentrations that drugs were soluble in and maintained mitochondrial function were determined. Metformin (MET) is a known mitochondrial complex-1 inhibitor tested for its ability to compromise mitochondrion function. Coenzyme Q10 (Q10) and Resveratrol (RSV), which are known to enhance mitochondrial function, were added alone and dose-dependent, tested for the ability to rescue metformin-induced mitochondrial dysfunction. Ex-vivo liver and brain mitochondrial function was assessed using an oxytherm Clark-type oxygen electrode. DMSO was found to be toxic above 10% and drugs insoluble below 5%. The addition of 0.5 mg/ml MET decreased liver and brain mitochondrial respiratory control rate (RCR). At the same time, Q10 improved RCR in normal mitochondria and a concentration-dependent manner in MET-induced dysfunctional mitochondria. RSV was added in the last step of the experiment to confirm that compromised function is due to MET. Hence this method can be used to screen pharmacological agents for their potential therapeutics or toxic effect on mitochondria.

Glycyrrhizic Acid Mitigates Tripterygium-Glycoside-Tablet-Induced Acute Liver Injury via PKM2 Regulated Oxidative Stress

Tripterygium glycoside tablet (TGT), as a common clinical drug, can easily cause liver damage due to the narrow therapeutic window. Glycyrrhizic acid (GA) has a hepatoprotective effect, but the characteristics and mechanism of GA's impact on TGT-induced acute liver injury by regulating oxidative stress remain unelucidated. In this study, TGT-induced acute liver injury models were established in vitro and in vivo. The levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AKP), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), catalase (CAT), lactate dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) were quantified. The anti-apoptotic effect of GA was tested using flow cytometry. Potential target proteins of GA were profiled via activity-based protein profiling (ABPP) using a cysteine-specific (IAA-yne) probe. The results demonstrate that GA markedly decreased the concentrations of ALT, AST, AKP, MDA, LDH, TNF-α, IL-1β and IL-6, whereas those of SOD, GSH and CAT increased. GA could inhibit TGT-induced apoptosis in BRL-3A cells. GA bound directly to the cysteine residue of PKM2. The CETSA and enzyme activity results validate the specific targets identified. GA could mitigate TGT-induced acute liver injury by mediating PKM2, reducing oxidative stress and inflammation and reducing hepatocyte apoptosis.

Inhibition of mitochondrial function: An alternative explanation for the antipyretic and hypothermic actions of acetaminophen

AIMS

Acetaminophen is the medication of choice when treating fever because of its limited anti-inflammatory effects. However at overdose it can cause mitochondrial dysfunction and damage, often associated with metabolism to N-acetyl-p-benzoquinone imine (NAPQI). What has never been investigated is whether the inhibition of mitochondrial function, particularly fatty acid uptake and oxidation could be the key to its antipyretic and hypothermic properties.

METHODS

Mitochondrial function and fatty acid oxidation (FAO) was determined by measuring oxygen consumption rate (OCR) in isolated mitochondria and in 3T3-L1 adipocytes using the XFp Analyser. Basal fatty acids and adrenergic stimulated OCR of mitochondria and 3T3-L1 adipocytes were assessed with acetaminophen and compared to NAPQI, etomoxir, and various mitochondrial stress compounds.

KEY FINDINGS

Using the XFp Analyser, acetaminophen (10 mM) decreased FAO by 31 % and 29 % in basal and palmitate stimulated adipocytes. NAPQI (50 μM) caused a 63 % decrease in both basal and palmitate stimulated FAO. Acetaminophen (10 mM) caused a 34 % reduction in basal and adrenergic stimulated OCR. In addition acetaminophen also inhibited complex I and II activity at 5 mM. NAPQI was far more potent at reducing mitochondrial respiratory capacity, maximum respiratory rates and ATP production than acetaminophen.

SIGNIFICANCE

These studies demonstrate the direct inhibition of mitochondrial function by acetaminophen at concentrations which have been shown to reduce fever and hypothermia in mammals. Understanding how antipyretics directly affect mitochondrial function and heat generation could lead to the development of new antipyretics which are not compromised by the anti-inflammatory and toxicity of the current medications.

Transplantation of adipose-derived mesenchymal stem cells ameliorates acute hepatic injury caused by nonsteroidal anti-inflammatory drug diclofenac sodium in female rats

BACKGROUND

Although the beneficial role of adipose-derived mesenchymal stem cells (AD-MSCs) in acute liver injury has been addressed by numerous studies employing different liver injury inducers, the role of rat AD-MSCs (rAD-MSCs) in diclofenac sodium (DIC) - induced acute liver injury has not yet been clarified.

OBJECTIVE

This study aimed to investigate whether rat adipose- rAD-MSCs injected intraperitoneal could restore the DIC-induced hepatoxicity.

METHODS

Hepatotoxicity was induced by DIC in a dose-based manner, after which intraperitoneal injection of rAD-MSCs was performed.

RESULTS

Here, the transplanted cells migrated to the injured liver, and this was evidenced by detecting the specific SRY in the liver samples. After administering DIC, a significant decrease in body weight, survival rate, serum proteins, antioxidants, anti-apoptotic gene expression, and certain growth factors, whereas hepatic-specific markers, pro-inflammatory mediators, and oxidative, pro-apoptotic, and ER-stress markers were elevated. These adverse effects were significantly recovered after engraftment with rAD-MSCs. This was evidenced by enhanced survival and body weight, improved globulin and albumin values, increased expression of SOD, GPx, BCL-2, VEGF, and FGF-basic expression, and decreased serum ALT, AST, ALP, and total bilirubin. rAD-MSCs also reduced liver cell damage by suppressing the expression of MDA, IL-1B, IL-6, BAX, JNK, GRP78/BiP, CHOP, XBP-1, and cleaved caspase 3/7. Degenerative hepatic changes and multifocal areas of fatty change within liver cells were observed in DIC-received groups. These changes were improved with the transplantation of rAD-MSCs.

CONCLUSIONS

We could conclude that targeted AD-MSCs could be applied to reduce hepatic toxicity caused by NSAIDs (DIC).

Role and Regulation of Hepatobiliary ATP-Binding Cassette Transporters during Chemical-Induced Liver Injury

Severity of drug-induced liver injury (DILI) ranges from mild, asymptomatic, and transient elevations in liver function tests to irreversible liver damage, often needing transplantation. Traditionally, DILI is classified mechanistically as high-frequency intrinsic DILI, commonly dose dependent or DILI that rarely occurs and is idiosyncratic in nature. This latter form is not dose dependent and has a pattern of histopathological manifestation that is not always uniform. Currently, a third type of DILI called indirect hepatotoxicity has been described that is associated with the pharmacological action of the drug. Historically, DILI was primarily linked to drug metabolism events; however, the impact of transporter-mediated rates of drug uptake and excretion has gained greater prominence in DILI research. This review provides a comprehensive view of the major findings from studies examining the contribution of hepatic ATP-binding cassette transporters as key contributors to DILI and how changes in their expression and function influence the development, severity, and overall toxicity outcome. SIGNIFICANCE STATEMENT: Drug-induced liver injury (DILI) continues to be a focal point in drug development research. ATP-binding cassette (ABC) transporters have emerged as important determinants of drug detoxification, disposition, and safety. This review article provides a comprehensive analysis of the literature addressing: (a) the role of hepatic ABC transporters in DILI, (b) the influence of genetic mutations in ABC transporters on DILI, and (c) new areas of research emphasis, such as the influence of the gut microbiota and epigenetic regulation, on ABC transporters.

In Vitro Models for Studying Chronic Drug-Induced Liver Injury

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.

Antifibrotic preventive effect of polyethylene glycol (PEG) 3350 in methotrexateinduced hepatoxicity model

PURPOSE

Liver damage caused by drugs and other chemicals accounts for about 5% of all cases. Methotrexate (MTX), a folic acid analogue, is a first-line synthetic antimetabolite agent routinely used in the treatment of rheumatoid arthritis and other autoimmune and chronic inflammatory diseases. Polyethylene glycol (PEG) has antioxidant activity. In this study, we evaluated biochemically and histopathologically the antifibrotic effect of PEG 3350 administered intraperitoneally to prevent methotrexate-induced liver damage in rats.

METHODS

A total of 30 male rats including 10 rats was given no drugs (normal group), and 20 rats received single-dose 20 mg/kg MTXfor induced liver injury in this study. MTX was given to 20 rats, which were divided in two groups. Group 1 rats was given PEG30 mg/kg/day (Merck) intraperitoneally, and Group 2 rats % 0.9 NaCl saline 1 mL/kg/day intraperitoneally daily for two weeks.

RESULTS

Transforming growth factor beta (TGF-β), plasma malondialdehyde (MDA), liver MDA, serum tumour necrosis factor alpha (TNF-α), alanine aminotransferase and plasma pentraxin-3 levels and, according to tissue histopathology, hepatocyte necrosis, fibrosis and cellular infiltration were significantly better in MTX+PEG group than in MTX+saline group.

CONCLUSIONS

PEG 3350 is a hope for toxic hepatitis due to other causes, since liver damage occurs through oxidative stress and cell damage, similar to all toxic drugs.

Challenges and Future of Drug-Induced Liver Injury Research-Laboratory Tests

Drug-induced liver injury (DILI) is a rare but potentially severe adverse drug event, which is also a major cause of study cessation and market withdrawal during drug development. Since no acknowledged diagnostic tests are available, DILI diagnosis poses a major challenge both in clinical practice as well as in pharmacovigilance. Differentiation from other liver diseases and the identification of the causative agent in the case of polymedication are the main issues that clinicians and drug developers face in this regard. Thus, efforts have been made to establish diagnostic testing methods and biomarkers in order to safely diagnose DILI and ensure a distinguishment from alternative liver pathologies. This review provides an overview of the diagnostic methods used in differential diagnosis, especially with regards to autoimmune hepatitis (AIH) and drug-induced autoimmune hepatitis (DI-AIH), in vitro causality methods using individual blood samples, biomarkers for diagnosis and severity prediction, as well as experimental predictive models utilized in pre-clinical settings during drug development regimes.

Targeted Mitochondrial Delivery to Hepatocytes: A Review

Defects in mitochondria are responsible for various genetic and acquired diseases. Mitochondrial transplantation, a method that involves introduction of healthy donor mitochondria into cells with dysfunctional mitochondria, could offer a novel approach to treat such diseases. Some studies have demonstrated the therapeutic benefit of mitochondrial transplantation and targeted delivery in vivo and in vitro within hepatocytes and the liver. This review discusses the issues regarding isolation and delivery of mitochondria to hepatocytes and the liver, and examines the existing literature in order to elucidate the utility and practicality of mitochondrial transplantation in the treatment of liver disease. Studies reviewed demonstrate that mitochondrial uptake could specifically target hepatocytes, address the challenge of non-specific localization of donor mitochondria, and provide evidence of changes in liver function following injection of mitochondria into mouse and rat disease models. While potential benefits and advantages of mitochondrial transplantation are evident, more research is needed to determine the practicality of mitochondrial transplantation for the treatment of genetic and acquired liver diseases.

Chemotherapy-associated steatohepatitis was concomitant with epicardial adipose tissue volume increasing in breast cancer patients who received neoadjuvant chemotherapy

OBJECTIVES

To investigate the prevalence of chemotherapy-associated steatohepatitis, quantitate the epicardial adipose tissue (EAT) volume in breast cancer patients, and explore the mediating effect of liver fat content on EAT volume in breast cancer patients who received neoadjuvant chemotherapy (NAC).

METHODS

From October 2018 to April 2020, patients were retrospectively reviewed and divided into breast cancer non-NAC and NAC groups. The prevalence of chemotherapy-associated steatohepatitis was evaluated through quantitative MRI mDIXON-Quant examinations by using defined proton density fat fraction cutoffs of liver fat. The EAT volume was quantified on chest CT by semi-automatic volume analysis software. Bootstrap analysis was used in the breast cancer NAC group to test the significance of the mediating effect of liver fat content on EAT volume.

RESULTS

A total of 662 breast cancer patients (non-NAC group: 445 patients; NAC group: 217 patients) were included. The prevalence of chemotherapy-associated steatohepatitis in the NAC group was significantly higher than the prevalence of hepatic steatosis in the non-NAC group (42.8% vs. 33.3%, p < 0.001). EAT volume was measured in 561 of 662 breast cancer patients, and was significantly higher in the NAC group than in the non-NAC group (137.26 ± 53.48 mL vs. 125.14 ± 58.77 mL, p = 0.020). In the breast cancer NAC group, the indirect effect of liver fat content on EAT volume was 2.545 (p < 0.001), and the contribution rate to the effect was 69.1%.

CONCLUSIONS

EAT volume was significantly higher in the BC-NAC group than in the BC-non-NAC group.

KEY POINTS

• The prevalence of CASH was as high as 42.8% in BC patients. • NAC significantly increased the EAT volume in BC patients. • The liver fat content caused the change of EAT volume through mediating effect.

Mitochondria as the Target of Hepatotoxicity and Drug-Induced Liver Injury: Molecular Mechanisms and Detection Methods

One of the major mechanisms of drug-induced liver injury includes mitochondrial perturbation and dysfunction. This is not a surprise, given that mitochondria are essential organelles in most cells, which are responsible for energy homeostasis and the regulation of cellular metabolism. Drug-induced mitochondrial dysfunction can be influenced by various factors and conditions, such as genetic predisposition, the presence of metabolic disorders and obesity, viral infections, as well as drugs. Despite the fact that many methods have been developed for studying mitochondrial function, there is still a need for advanced and integrative models and approaches more closely resembling liver physiology, which would take into account predisposing factors. This could reduce the costs of drug development by the early prediction of potential mitochondrial toxicity during pre-clinical tests and, especially, prevent serious complications observed in clinical settings.

Preclinical models of idiosyncratic drug-induced liver injury (iDILI): Moving towards prediction

Idiosyncratic drug-induced liver injury (iDILI) encompasses the unexpected harms that prescription and non-prescription drugs, herbal and dietary supplements can cause to the liver. iDILI remains a major public health problem and a major cause of drug attrition. Given the lack of biomarkers for iDILI prediction, diagnosis and prognosis, searching new models to predict and study mechanisms of iDILI is necessary. One of the major limitations of iDILI preclinical assessment has been the lack of correlation between the markers of hepatotoxicity in animal toxicological studies and clinically significant iDILI. Thus, major advances in the understanding of iDILI susceptibility and pathogenesis have come from the study of well-phenotyped iDILI patients. However, there are many gaps for explaining all the complexity of iDILI susceptibility and mechanisms. Therefore, there is a need to optimize preclinical human in vitro models to reduce the risk of iDILI during drug development. Here, the current experimental models and the future directions in iDILI modelling are thoroughly discussed, focusing on the human cellular models available to study the pathophysiological mechanisms of the disease and the most used in vivo animal iDILI models. We also comment about in silico approaches and the increasing relevance of patient-derived cellular models.

Irinotecan-Induced Steatohepatitis: Current Insights

The hepatotoxicity of irinotecan is drawing wide concern nowadays due to the widespread use of this chemotherapeutic against various solid tumors, particularly metastatic colorectal cancer. Irinotecan-induced hepatotoxicity mainly manifests as transaminase increase and steatosis with or without transaminase increase, and is accompanied by vacuolization, and lobular inflammation. Irinotecan-induced steatohepatitis (IIS) increases the risk of morbidity and mortality in patients with colorectal cancer liver metastasis (CRCLM). The major risks and predisposing factors for IIS include high body mass index (BMI) or obesity, diabetes, and high-fat diet. Mitochondrial dysfunction and autophagy impairment may be involved in the pathogenesis of IIS. However, there is currently no effective preventive or therapeutic treatment for this condition. Thus, the precise mechanisms underlying the pathogenesis of IIS should be deciphered for the development of therapeutic drugs. This review summarizes the current knowledge and research progress on IIS.

Drug-induced Fatty Liver Disease: Pathogenesis and Treatment

Metabolic dysfunction-associated fatty liver disease (commonly known as MAFLD) impacts global health in epidemic proportions, and the resulting morbidity, mortality and economic burden is enormous. While much attention has been given to metabolic syndrome and obesity as offending factors, a growing incidence of polypharmacy, especially in the elderly, has greatly increased the risk of drug-induced liver injury (DILI) in general, and drug-induced fatty liver disease (DIFLD) in particular. This review focuses on the contribution of DIFLD to DILI in terms of epidemiology, pathophysiology, the most common drugs associated with DIFLD, and treatment strategies.

Mycophenolate Mofetil Hepatotoxicity Associated With Mitochondrial Abnormality in Liver Transplant Recipients and Mice

OBJECTIVES

Mycophenolate mofetil (MMF) is a widely used immunosuppressive agent. MMF hepatotoxicity has been reported in non-transplant and renal transplant patients with minimal histologic description. This is the first study describing detailed histology and ultrastructure of MMF hepatotoxicity.

METHODS

Four liver-transplant recipients (Cases 1-4) were suspected to have MMF hepatotoxicity. Cases 1-3 (two females and one male; 4-17 years) had multiple biopsies for liver function test (LFT) abnormalities. Case 4 (female; 16 years) had a surveillance biopsy. Electron-microscopic examination (EM) was requested on Cases 1-3 for unexplained, persistent LFT elevation and histologic abnormalities despite therapy and Case 4 for unexplained histologic abnormalities despite a stable clinical course. To confirm the pathologic changes in the human allografts, livers from MMF-treated and untreated mice were also reviewed.

RESULTS

While the allograft biopsies showed nonspecific histologic changes, EM revealed unequivocal mitochondrial abnormalities similar to those seen in primary and secondary mitochondrial disorders. In Cases 1 and 2, LFTs improved after stopping and reducing MMF, respectively. In Case 3, pre- and post-MMF treatment biopsies were performed and only the post-MMF biopsy demonstrated mitochondrial abnormalities. Mitochondrial abnormality in Case 4 was subclinical. The mouse study confirmed that MMF caused various stress changes in the mitochondria; number of mitochondria/cell (mean ± standard deviation; untreated group: 58.25 ± 8.426; MMF-treated group: 76.37 ± 18.66), number of lipid droplets/cell (untreated: 0.9691 ± 1.150; MMF-treated: 3.649 ± 4.143) and sizes of mitochondria (μm, untreated: 0.8550 ± 0.3409; MMF-treated: 0.9598 ± 0.5312) were significantly increased in hepatocytes in the MMF-treated mice compared with the untreated mice (P < 0.0001).

CONCLUSIONS

Although MMF is safe for the majority of patients, MMF can cause mitochondrial stress, which may trigger more severe mitochondrial abnormalities in a small subset. MMF hepatotoxicity should be considered for MMF-treated patients with unexplained, persistent LFT abnormalities and nonspecific histologic findings. EM should be requested for these cases.

Chemotherapy-associated steatohepatitis

Some drugs may induce hepatotoxic lesions, such as steatosis or steatohepatitis found in Non-Alcoholic Fatty Liver Disease (NAFLD). Among these drugs there are some anti-tumoral molecules, such as methotrexate, 5-fluorouracil, irinotecan, tamoxifen and l-asparaginase. The hepatotoxic phenotype developed from treatment with such drugs is known as "CASH" for "Chemotherapy-induced Acute Steatohepatitis". The mechanism of toxicity is essentially based on mitochondrial toxicity. These lesions are chronic and often reversible when the treatment is stopped. Contributing factors related to the patient, the disease or the treatment play a major role in the emergence of CASH. It is important to identify chemotherapies with steatosis or steatohepatitis as risk factors in order to improve control of the metabolic risk factors associated with the patient and to reinforce monitoring during treatment. In the particular context of neo-adjuvant chemotherapy for metastatic colorectal cancer, a short duration of chemotherapy and a few-weeks delay between chemotherapy and surgery could reduce postoperative morbidity and mortality.

SOHO State of the Art Updates and Next Questions: Management of Asparaginase Toxicity in Adolescents and Young Adults with Acute Lymphoblastic Leukemia

A wider use of L-asparaginase in the treatment of children with acute lymphoblastic leukemia has improved cure rates during recent decades and hence led to introduction of pediatric-inspired treatment protocols for adolescents and young adults. In parallel, a range of burdensome, often severe and occasionally life-threatening toxicities have become frequent, including hypersensitivity, hepatotoxicity, hypertriglyceridemia, thromboembolism, pancreatitis, and osteonecrosis. This often leads to truncation of asparaginase therapy, which at least in the pediatric population has been clearly associated with a higher risk of leukemic relapse. Many of the asparaginase induced toxicities are far more common in older patients, but since their relapse rate is still unsatisfactory, the decision to discontinue asparaginase therapy should balance the risk of toxicity with continued asparaginase therapy against the risk of relapse in the individual patient. The underlying mechanisms of most of the asparaginase induced side effects are still unclear. In this review we address the individual toxicities, known risk factors, and their clinical management.

A mouse model of short-term, diet-induced fatty liver with abnormal cardiolipin remodeling via downregulated Tafazzin gene expression

BACKGROUND

Cardiolipin (CL) helps maintain mitochondrial structure and function. Here we investigated whether a high carbohydrate diet (HCD) fed to mice for a short period (5 days) could modulate the CL level, including that of monolysoCL (MLCL) in the liver.

RESULTS

Total CL in the HCD group was 22% lower than that in the normal chow diet (NCD) group (P < 0.05). The CL72:8 level strikingly decreased by 93% (P < 0.0001), whereas total nascent CLs (CLs other than CL72:8) increased (P < 0.01) in the HCD group. The total MLCL in the HCD group increased by 2.4-fold compared with that in the NCD group (P < 0.05). Tafazzin expression in the HCD group was significantly downregulated compared with that in the NCD group (P < 0.05). A strong positive correlation between nascent CL and total MLCL (r = 0.955, P < 0.0001), and a negative correlation between MLCL and Tafazzin expression (r = -0.593, P = 0.0883) were observed.

CONCLUSION

A HCD modulated the fatty acid composition of CL and MLCL via Tafazzin in the liver, which could lead to mitochondrial dysfunction. This model may be useful for elucidating the relationship between fatty liver and mitochondrial dysfunction. © 2021 Society of Chemical Industry.

Role of respiratory uncoupling in drug-induced mitochondrial permeability transition

Mitochondrial injury contributes to severe drug-induced liver injury. Particularly, mitochondrial permeability transition (MPT) is thought to be relevant to cytolytic hepatitis. However, the mechanism of drug-induced MPT is unclear and prediction of MPT is not adequately evaluated in the preclinical stage. In a previous study, we found that troglitazone, a drug withdrawn due to liver injury, induced MPT via mild depolarization probably resulting from uncoupling. Herein, we investigated whether other drugs that induce MPT share similar properties as troglitazone, using isolated mitochondria from rat liver. Of the 22 test drugs examined, six drugs, including troglitazone, induced MPT and showed an uncoupling effect. Additionally, receiver operating characteristic analysis was conducted to predict the MPT potential from the respiratory control ratio, an indicator of uncoupling intensity. Results showed that 2.5 was the best threshold that exhibited high sensitivity (1.00) and high specificity (0.81), indicating that uncoupling was correlated with MPT potential. Activation of calcium-independent phospholipase A2 appeared to be involved in uncoupling-induced MPT. Furthermore, a strong relationship between MPT intensity and the uncoupling effect among similar compounds was confirmed. These results may help in predicting MPT potential using cultured cells and modifying the chemical structures of the drugs to reduce MPT risk.

Mitochondrial Transplantation as a Novel Therapeutic Strategy for Mitochondrial Diseases

Mitochondria are the major source of intercellular bioenergy in the form of ATP. They are necessary for cell survival and play many essential roles such as maintaining calcium homeostasis, body temperature, regulation of metabolism and apoptosis. Mitochondrial dysfunction has been observed in variety of diseases such as cardiovascular disease, aging, type 2 diabetes, cancer and degenerative brain disease. In other words, the interpretation and regulation of mitochondrial signals has the potential to be applied as a treatment for various diseases caused by mitochondrial disorders. In recent years, mitochondrial transplantation has increasingly been a topic of interest as an innovative strategy for the treatment of mitochondrial diseases by augmentation and replacement of mitochondria. In this review, we focus on diseases that are associated with mitochondrial dysfunction and highlight studies related to the rescue of tissue-specific mitochondrial disorders. We firmly believe that mitochondrial transplantation is an optimistic therapeutic approach in finding a potentially valuable treatment for a variety of mitochondrial diseases.

Hepatoprotective effects of silymarin against diclofenac-induced liver toxicity in male rats based on biochemical parameters and histological study

Diclofenac (DIC) is a phenyl acetic acid derivative which is well known for its analgesic and anti-inflammatory. In our study, the rats were divided into four groups. Group 1, control group; Group 2 received DIC-only; Groups 3 and 4 received DIC plus silymarin. The results showed that levels of CAT, SOD, GPx and GSH significantly reduced and levels of ALT, AST, ALP, total bilirubin, nitrite content, MDA, serum TNF-α and TNF-α gene expression were significantly elevated in second group compared to control group. In other hand, treatment with silymarin resulted in a significant elevation in CAT, SOD, GPx, GSH and a significant reduction in MDA, ALT, AST, ALP, total bilirubin, nitrite content, serum TNF-α, and gene expression of TNF-α in comparison with second group. Histopathological injuries were also improved by silymarin administration. The results confirm that silymarin has a protective effect on DIC-induced liver toxicity and oxidative stress in male rats.

Antioxidant, antinociceptive, anti-inflammatory, and hepatoprotective activities of pentacyclic triterpenes isolated from Ziziphus oxyphylla Edgew

Ziziphus oxyphylla Edgew is in folk use in Pakistan as an analgesic, anti-inflammatory, and liver ailments. Therefore, we have investigated antioxidant, antinociceptive, anti-inflammatory, and hepatoprotective activities of the isolated compounds (ceanothic acid and zizybrenalic acid) from the chloroform fraction of Z. oxyphylla. Ceanothic acid and zizybrenalic acid showed significant DPPH and H₂O₂ scavenging activity as compared to control. In the acute toxicity study, ceanothic acid and zizybrenalic acid showed no toxic effects upto 200 mg/kg. The antinociceptive activity shown by ceanothic acid and zizybrenalic acid at 50 mg/kg was 64.28% and 65.35% compared to diclofenac sodium (72.3%) at 50 mg/kg. The percent inhibition of xylene-induced ear edema exhibited by ceanothic acid and zizybrenalic acid at 50 mg/kg was 51.33% and 58.66%, respectively, as compared to diclofenac sodium (72.66%). Both the isolated compounds exhibited inhibition of carrageenan-induced paw edema as compared to control. Hepatoprotection exhibited by zizybrenalic acid was more pronounced than ceanothic acid as observed from the decrease in carbon tetrachloride (CCl₄)-induced elevation of serum biomarkers, antioxidant enzymes and lipid peroxidation. Furthermore, zizybrenalic acid produced a marked decline in CCl₄-induced prolongation of phenobarbital-induced sleeping duration. Zizybrenalic acid exhibited 55.4 ± 1.37% inhibition of hypotonic solution-induced hemolysis compared to sodium salicylate (75.6 ± 2.15%). The histopathological damage caused by CCl₄ was also countered by the administration of ceanothic acid and zizybrenalic acid. Ceanothic acid and zizybrenalic acid exhibited antioxidant, antinociceptive, anti-inflammatory, and hepatoprotective activities. Zizybrenalic acid exhibited better antioxidant, antinociceptive, anti-inflammatory, and hepatoprotective activity than ceanothic acid.

High-Content Screening for the Detection of Drug-Induced Oxidative Stress in Liver Cells

Drug-induced liver injury (DILI) remains a major cause of drug development failure, post-marketing warnings and restriction of use. An improved understanding of the mechanisms underlying DILI is required for better drug design and development. Enhanced reactive oxygen species (ROS) levels may cause a wide spectrum of oxidative damage, which has been described as a major mechanism implicated in DILI. Several cell-based assays have been developed as in vitro tools for early safety risk assessments. Among them, high-content screening technology has been used for the identification of modes of action, the determination of the level of injury and the discovery of predictive biomarkers for the safety assessment of compounds. In this paper, we review the value of in vitro high-content screening studies and evaluate how to assess oxidative stress induced by drugs in hepatic cells, demonstrating the detection of pre-lethal mechanisms of DILI as a powerful tool in human toxicology.

Artificial intelligence in the early stages of drug discovery

Although the use of computational methods within the pharmaceutical industry is well established, there is an urgent need for new approaches that can improve and optimize the pipeline of drug discovery and development. In spite of the fact that there is no unique solution for this need for innovation, there has recently been a strong interest in the use of Artificial Intelligence for this purpose. As a matter of fact, not only there have been major contributions from the scientific community in this respect, but there has also been a growing partnership between the pharmaceutical industry and Artificial Intelligence companies. Beyond these contributions and efforts there is an underlying question, which we intend to discuss in this review: can the intrinsic difficulties within the drug discovery process be overcome with the implementation of Artificial Intelligence? While this is an open question, in this work we will focus on the advantages that these algorithms provide over the traditional methods in the context of early drug discovery.

Sphingolipid metabolism as a marker of hepatotoxicity in drug-induced liver injury

Drug-induced liver injury (DILI) has a substantial impact on human health and is a major monetary burden on the drug development process. Presently, there is a lack of robust and analytically validated markers for predicting and early diagnosis of DILI. Sphingolipid metabolism and subsequent disruption of sphingolipid homeostasis has been documented to play a key role contributing to hepatocellular death and subsequent liver injury. A more comprehensive understanding of sphingolipid metabolism in response to liver toxicity has great potential to gain mechanistic insight into hepatotoxicity and define molecular markers that are responsible for hepatocyte dysfunction. Here, we present an analytical platform that provides multidimensional mass spectrometry-based datasets for comprehensive structure characterization of sphingolipids extracted from human primary hepatocytes (HPH) exposed to toxic levels of acetaminophen (APAP). Sphingolipid metabolism as measured by characterization of individual sphingolipid structure was sensitive to APAP toxicity displaying a concentration-dependent response. A number of sphingolipid structures were differentially expressed across varying APAP exposures highlighting the unique role sphingolipid metabolism has in response to hepatotoxicity and its potential use as a molecular marker in DILI.

Superoxide dismutase: a review and a modified protocol for activities measurements in rat livers

Superoxide dismutase (SOD) enzymes are considered the first line of Defence against reactive oxygen species. Among the intracellular isoforms of SOD, Cu,ZnSOD is widely distributed, and the MnSOD is localised in the mitochondria. The SOD activities have been measured indirectly by inhibiting oxidation reactions. Most techniques assessing the hepatic SOD activity are adaptations of classical methods and differ significantly from each other. This work assessed the hepatic Cu,ZnSOD activity in the supernatants of two different centrifugations, using two isotonic medium and the pyrogallol method. In most studies conducted in rat liver, only the Cu,Zn or total SOD activities were assessed and sometimes the Cu,ZnSOD activity was calculated based on the inhibition by cyanide. But, as demonstrated here, this inhibition is not complete. Besides, the novelty of this work is that we presented a method for the evaluating the Cu,ZnSOD and MnSOD activities separately and from the same liver.

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.

Mitochondrial dysfunction and apoptosis underlie the hepatotoxicity of perhexiline

Perhexiline is an anti-anginal drug developed in the late 1960s. Despite its therapeutic success, it caused severe hepatoxicity in selective patients, which resulted in its withdrawal from the market. In the current study we explored the molecular mechanisms underlying the cytotoxicity of perhexiline. In primary human hepatocytes, HepaRG cells, and HepG2 cells, perhexiline induced cell death in a concentration- and time-dependent manner. Perhexiline treatment also caused a significant increase in caspase 3/7 activity at 2 h and 4 h. Pretreatment with specific caspase inhibitors suggested that both intrinsic and extrinsic apoptotic pathways contributed to perhexiline-induced cytotoxicity, which was confirmed by increased expression of TNF-α, cleavage of caspase 3 and 9 upon perhexiline treatment. Moreover, perhexiline caused mitochondrial dysfunction, demonstrated by the classic glucose-galactose assay at 4 h and 24 h. Results from JC-1 staining suggested perhexiline caused loss of mitochondrial potential. Blocking mitochondrial permeability transition pore using inhibitor bongkrekic acid attenuated the cytotoxicity of perhexiline. Western blotting analysis also showed decreased expression level of pro-survival proteins Bcl-2 and Mcl-1, and increased expression of pro-apoptotic protein Bad. Direct measurement of the activity of individual components of the mitochondrial respiratory complex demonstrated that perhexiline strongly inhibited Complex IV and Complex V and moderately inhibited Complex II and Complex II + III. Overall, our data demonstrated that both mitochondrial dysfunction and apoptosis underlies perhexiline-induced hepatotoxicity.

Novel advances in biotransformation and bioactivation research-2019 year in review

Biotransformation is one of the main mechanisms used by the body to eliminate drugs. As drug molecules become more complicated, the involvement of drug metabolizing enzymes increases beyond those that are typically studied, such as the cytochrome P450 enzymes. In this review, we try to capture the many outstanding articles that were published in the past year in the field of biotransformation (see Table 1). We have divided the articles into two categories of (1) metabolites and drug metabolizing enzymes, and (2) bioactivation and safety.  This annual review is the fifth of its kind since 2016 (Baillie et al. 2016; Khojasteh et al. 2017, 2018, 2019). This effort in itself also continues to evolve. We have followed the same format we used in previous years in terms of the selection of articles and the authoring of each section. I am pleased of the continued support of Rietjens, Miller, Zhang, Driscoll and Mitra to this review. We would like to welcome Klarissa D. Jackson as a new author for this year's issue. We strive to maintain a balance of authors from academic and industry settings.  We would be pleased to hear your opinions of our commentary, and we extend an invitation to anyone who would like to contribute to a future edition of this review. Cyrus Khojasteh, on behalf of the authors.

High Doses of Δ9-Tetrahydrocannabinol Might Impair Irinotecan Chemotherapy: A Review of Potentially Harmful Interactions

This review proposes the hypothesis that the effectiveness of irinotecan chemotherapy might be impaired by high doses of concomitantly administered Δ⁹-tetrahydrocannabinol (THC). The most important features shared by irinotecan and THC, which might represent sources of potentially harmful interactions are: first-pass hepatic metabolism mediated by cytochrome P450 (CYP) enzyme CYP3A4; glucuronidation mediated by uridine diphosphate glycosyltransferase (UGT) enzymes, isoforms 1A1 and 1A9; transport of parent compounds and their metabolites via canalicular ATP-binding cassette (ABC) transporters ABCB1 and ABCG2; enterohepatic recirculation of both parent compounds, which leads to an extended duration of their pharmacological effects; possible competition for binding to albumin; butyrylcholinesterase (BChE) inhibition by THC, which might impair the conversion of parent irinotecan into the SN-38 metabolite; mutual effects on mitochondrial dysfunction and induction of oxidative stress; potentiation of hepatotoxicity; potentiation of genotoxicity and cytogenetic effects leading to genome instability; possible neurotoxicity; and effects on bilirubin. The controversies associated with the use of highly concentrated THC preparations with irinotecan chemotherapy are also discussed. Despite all of the limitations, the body of evidence provided here could be considered relevant for human-risk assessments and calls for concern in cases when irinotecan chemotherapy is accompanied by preparations rich in THC.

PiTMaP: A New Analytical Platform for High-Throughput Direct Metabolome Analysis by Probe Electrospray Ionization/Tandem Mass Spectrometry Using an R Software-Based Data Pipeline

A new analytical platform called PiTMaP was developed for high-throughput direct metabolome analysis by probe electrospray ionization/tandem mass spectrometry (PESI/MS/MS) using an R software-based data pipeline. PESI/MS/MS was used as the data acquisition technique, applying a scheduled-selected reaction monitoring method to expand the targeted metabolites. Seventy-two metabolites mainly related to the central energy metabolism were selected; data acquisition time was optimized using mouse liver and brain samples, indicating that the 2.4 min data acquisition method had a higher repeatability than the 1.2 and 4.8 min methods. A data pipeline was constructed using the R software, and it was proven that it can (i) automatically generate box-and-whisker plots for all metabolites, (ii) perform multivariate analyses such as principal component analysis (PCA) and projection to latent structures-discriminant analysis (PLS-DA), (iii) generate score and loading plots of PCA and PLS-DA, (iv) calculate variable importance of projection (VIP) values, (v) determine a statistical family by VIP value criterion, (vi) perform tests of significance with the false discovery rate (FDR) correction method, and (vii) draw box-and-whisker plots only for significantly changed metabolites. These tasks could be completed within ca. 1 min. Finally, PiTMaP was applied to two cases: (1) an acetaminophen-induced acute liver injury model and control mice and (2) human meningioma samples with different grades (G1-G3), demonstrating the feasibility of PiTMaP. PiTMaP was found to perform data acquisition without tedious sample preparation and a posthoc data analysis within ca. 1 min. Thus, it would be a universal platform to perform rapid metabolic profiling of biological samples.

Alhagi maurorum aqueous extract protects against norfloxacin-induced hepato-nephrotoxicity in rats

Objectives

While the protective effects of Alhagi maurorum have been shown against various ailments, its role against norfloxacin-induced adverse effects has not been studied. The current study was conducted to determine the effect of A. maurorum aqueous extract against norfloxacin-induced side effects in rats.

Methods

Twenty-four male albino rats were randomly assigned into four groups, which received normal saline, norfloxacin (50 mg/kg b.wt orally once a day), A. maurorum aqueous extract (300 mg/kg b.wt orally once a day), and norfloxacin with A. maurorum aqueous extract by the same previous mentioned dosages. Blood samples were collected for hematological examination to evaluate liver and kidney function tests. Hepatic and renal tissue samples were obtained to assess antioxidant activity and histopathological examination.

Results

A. maurorum aqueous extract significantly ameliorated norfloxacin-induced elevation in tissue malondialdehyde, and reduction in tissue antioxidant enzymes such as catalase, glutathione peroxidase, and superoxide dismutase activities as well as reduced glutathione concentration. Concurrent administration of A. maurorum aqueous extract with norfloxacin significantly reduced serum alkaline phosphatase, aminotransferases, urea, creatinine, and uric acid and increased RBCs count, Hb concentration, PCV, leucocyte, and monocyte counts compared with the norfloxacin-treated group. Co-administration of A. maurorum aqueous extract with norfloxacin prevented the degenerative changes induced by norfloxacin alone in liver and kidney tissues. The phytochemical profile of the extract showed the presence of carbohydrates, alkaloids, saponins, tannins, phenolics, and flavonoids.

Conclusion

These findings indicated that A. maurorum possesses potent antioxidant activities and could be used to attenuate norfloxacin-induced side effects.

Fatal acetaminophen poisoning with hepatic microvesicular steatosis in a child after repeated administration of therapeutic doses

Acetaminophen is the leading cause of acute liver failure worldwide following massive ingestion. We present here a fatal acute liver failure after repeated administration of four therapeutic doses of acetaminophen at 4-h intervals in a previously healthy 9-year-old female who presented dental pain after a facial trauma during sport practice. A diagnosis of paracetamol-induced hepatitis was deduced from the clinical picture of fulminant hepatitis and tubular necrosis, the encephalopathy with oedema and without signs of trauma. Liver biopsy showed typical acetaminophen-induced necrosis and a microvesicular steatosis in periportal hepatocytes. These injuries might have been favored by pre-existing mitochondrial dysfunction related, for instance, to a deficiency in an enzyme of the mitochondrial β-oxidation pathway, or the respiratory chain. The observation of microvesicular steatosis in the periportal areas suggests an increased vulnerability via pre-existing mitochondrial dysfunction. As the liver status of patients is mostly unknown, the frequency of administration (every six hours) must be respected and the use of pharmaceutical forms allowing to adjust the dose as closely as possible to the child's weight should be promoted.

Role of Kupffer cells in liver injury induced by CpG oligodeoxynucleotide and flucloxacillin in mice

CpG oligodeoxynucleotide (CpG-ODN) is a Toll-like receptor 9 (TLR9) agonist that can induce innate immune responses. In a previous study, flucloxacillin (FLUX; 100 mg/kg, gavage)-induced liver injury in mice was enhanced by co-administration of CpG-ODN (40 μg/mouse, intraperitoneally). In this study, the mechanism of CpG-ODN sensitization to FLUX-induced liver injury was further investigated in mice inhibited of Kupffer cells (KCs) function by gadolinium chloride (GdCl3; 10 mg/kg, intravenously). GdCl3-treated mice administrated with CpG-ODN and FLUX showed lower liver injury than wild-type (WT) mice treated with CpG-ODN and FLUX. Upregulation of Fas and FasL by CpG-ODN was also inhibited in GdCl3-treated mice and mitochondrial swelling in response to FLUX failed to occur regardless of pre-treatment with CpG-ODN. When FasL-mutant gld/gld mice were treated with CpG-ODN, mitochondrial swelling in response to FLUX was also inhibited. These results suggest that KCs play an essential role in liver injury induced by CpG-ODN and FLUX. CpG-ODN may activate KCs, resulting in induction of Fas/FasL-mediated apoptosis of hepatocytes. The Fas/FasL pathway may also be an upstream regulator of CpG-ODN- and FLUX-induced changes in mitochondrial permeability transition. These results enhance our understanding of the mechanism of the adjuvant effect of CpG-ODN in this mouse model of liver injury.