The development and hepatotoxicity of acetaminophen: reviewing over a century of progress

Isorhapontigenin alleviates acetaminophen-induced liver injury by promoting fatty acid oxidation

Acetaminophen (APAP) is a widely used analgesic and antipyretic medicine. It is frequently employed to alleviate pain and mitigate fever-related symptoms, but it can cause liver injury or even liver failure when overdosed. Isorhapontigenin, a compound derived from Chinese herbs and grapes, has been demonstrated to exhibit antioxidant and anti-inflammatory effects. This study focused on evaluating the effect of isorhapontigenin in alleviating APAP-induced liver injury. In the study, a single intraperitoneal administration of APAP was employed to induce liver injury, and isorhapontigenin was given orally 3 days before or 1 h after APAP administration. The results revealed that isorhapontigenin significantly mitigated liver injury by effectively inhibiting APAP-induced apoptosis, oxidative stress, and inflammation. Furthermore, transcriptomic RNA sequencing of liver tissues indicated that isorhapontigenin probably protected against APAP-induced liver injury by promoting fatty acid oxidation. Pharmacological experiments also demonstrated that isorhapontigenin treatment led to a significant reduction in triglyceride accumulation, increased ATP levels and direct fatty acid oxidation activity, as well as enhanced expression of proteins associated with fatty acid oxidation, including PPAR-α, PGC-1α, and CPT-1A. Moreover, the protective effects of isorhapontigenin against APAP-induced liver injury were abolished by a CPT-1A inhibitor, etomoxir. Notably, we found that combining isorhapontigenin with NAC (N-acetyl-L-cysteine) resulted in a more significant alleviation of APAP-induced liver injury compared to NAC alone. In conclusion, our study indicates that isorhapontigenin is a potential therapeutic strategy that works by regulating fatty acid oxidation to alleviate APAP-induced liver injury.

Metabolic Activation and Cytotoxicity of Donepezil Induced by CYP3A4

Donepezil (DNP) is a selective cholinesterase inhibitor widely used for the therapy of Alzheimer's disease. Instances of liver injury correlated with DNP treatment have been reported, yet the underlying hepatotoxic mechanism remains to be elucidated. This study aimed to explore the contribution of metabolic activation to the hepatotoxicity of DNP. The structure of 6-O-desmethyl DNP (M1), the oxidative metabolite of DNP, was characterized by chemical synthesis, LC-MS/MS, and nuclear magnetic resonance. A reactive quinone methide resulting from the metabolism of DNP was captured by glutathione (GSH) fortified in liver microsomal incubations after exposure to DNP, and the resulting GSH conjugate (M2) was detected in the bile of rats receiving DNP. Recombinant human P450 enzyme incubation studies demonstrated that CYP3A4 was the principal enzyme responsible for the production of M1 and M2. The generation of M2 declined in rat primary hepatocytes pretreated with ketoconazole, an inhibitor of CYP3A4, which also decreased the vulnerability of rat primary hepatocytes to DNP-caused cytotoxicity. These findings suggest that the quinone methide metabolite may contribute to the cytotoxicity and hepatotoxicity caused by the DNP.

Piperine as an Herbal Alternative for the Prevention of Drug-Induced Liver Damage Caused by Paracetamol

Background/Objective: Hepatic drug intoxication is becoming increasingly common with the increasing use of chronic medications. Piperine has emerged as a promising alternative for protecting the liver against drug-induced injury. We evaluated the prophylactic effects of piperine in C57BL/6 mice with an acute liver injury induced by a paracetamol (APAP) overdose. Methods: Piperine was administered at a dose of 20 mg/kg (P20) or 40 mg/kg (P40) for eight consecutive days before the animals were exposed to a hepatotoxic dose of paracetamol (500 mg/kg). The animals were euthanized 3 h after the paracetamol overdose. Results: The prophylactic treatment with piperine (P20 and P40) maintained the levels of alanine aminotransferase (ALT) and the biomarkers of oxidative damage (TBARS and carbonylated proteins), which were statistically similar to those for the control group. The extent of hepatocyte necrosis and TNF-α (tumor necrosis factor-alpha) levels were lower than those in the group exposed to liver injury (APAP group). Piperine modulated the gene expression of CYP2E1 (cytochrome P4502E1) and the inflammasome pathway (NLRP3, CASP-1, IL-1β, and IL-18), which play a crucial role in the inflammatory response. In the P40 group, the degree of hepatic hyperemia was similar to that in the control group, as was the increase in metalloproteinase 9 (MMP-9) activity. Conclusion: Piperine has demonstrated beneficial and promising effects for the prevention of liver injury resulting from paracetamol-induced drug intoxication.

Therapeutic liver cell transplantation to treat murine PKU

For gene therapy of the liver, in vivo applications based on adeno-associated virus are the most advanced vectors despite limitations, including low efficacy and episomal loss, potential integration and safety issues, and high production costs. Alternative vectors and/or delivery routes are of high interest. The regenerative ability of the liver bears the potential for ex vivo therapy using liver cell transplantation for disease correction if provided with a selective advantage to expand and replace the existing cell mass. Here we present such treatment of a mouse model of human phenylketonuria (PKU). Primary hepatocytes from wild-type mice were gene modified in vitro (with a lentiviral vector) that carries a gene editing system (CRISPR) to inhibit Cypor. Cypor inactivation confers paracetamol (or acetaminophen) resistance to hepatocytes and thus a growth advantage to eliminate the pre-existing liver cells upon grafting (via the spleen) and exposure to repeated treatment with paracetamol. Grafting Cypor-inactivated wild-type hepatocytes into inbred young adult enu2 (PKU) mice, followed by selective expansion by paracetamol dosing, resulted in replacing up to 5% of cell mass, normalization of blood phenylalanine, and permanent correction of PKU. Hepatocyte transplantation offers thus an armamentarium of novel therapy options for genetic liver defects.

Wogonin mitigates acetaminophen-induced liver injury in mice through inhibition of the PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellaria baicalensis Georgi (SBG), a widely used traditional Chinese medicine, exhibits anti-inflammatory and antioxidant properties. Wogonin is one of the primary bioactive components of SBG. Acetaminophen (APAP)-induced liver injury (AILI) represents a prevalent form of drug-induced liver damage and is primarily driven by inflammatory responses and oxidative stress.

AIM OF STUDY

To investigate the therapeutic effects of Wogonin on AILI and the underlying mechanisms.

MATERIALS AND METHODS

C57BL/6 J mice were pre-treated with Wogonin (1, 2.5, and 5 mg/kg bodyweight) for 3 days, followed by treatment with APAP (300 mg/kg bodyweight). The serum and liver tissue samples were collected at 24 h post-APAP treatment. Bone marrow-derived macrophages and RAW264.7 cells were cultured and pre-treated with Wogonin (5, 10, and 20 μM) for 30 min, followed by stimulation with lipopolysaccharide (LPS; 100 ng/mL) for 3 h. To examine the role of the PI3K/AKT signaling pathway in the therapeutic effect of Wogonin on AILI, mice and cells were treated with LY294002 (a PI3K inhibitor) and MK2206 (an AKT inhibitor).

RESULTS

Wogonin pre-treatment dose-dependently alleviated AILI in mice. Additionally, Wogonin suppressed oxidative stress and inflammatory responses. Liver transcriptome analysis indicated that Wogonin primarily regulates immune function and cytokines in AILI. Wogonin suppressed inflammatory responses of macrophages by inhibiting the PI3K/AKT signaling pathway. Consistently, Wogonin exerted therapeutic effects on AILI in mice through the PI3K/AKT signaling pathway.

CONCLUSIONS

Wogonin alleviated AILI and APAP-induced hepatotoxicity in mice through the PI3K/AKT signaling pathway.

Artemether ameliorates acetaminophen-induced liver injury through Nrf2 pathway

Acetaminophen (APAP) overdose is a prevalent cause of clinical pharmacological liver injury worldwide. Artemether (ART), a first-line antimalarial drug, has demonstrated hepatoprotective activity. However, its effect on APAP-induced acute liver injury (AILI) remains unclear. In this study, we investigated whether ART can protect against AILI and examined its underlying mechanisms. In vivo, ART mitigated APAP-induced liver histological changes, including mitochondrial damage, hepatocyte necrosis, hepatocyte apoptosis, and inflammatory infiltration. Additionally, ART reduced serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in APAP-induced mice. ART also activated the Nrf2-HO-1/GPX4 signaling pathway, exerting antioxidant effects in both in vitro and in vivo models of AILI. To confirm Nrf2 as a target of ART in vivo, we pretreated C57BL/6 mice with the Nrf2 inhibitor, ML385. The results indicated that inhibiting Nrf2 diminishes the protective effect of ART against AILI. Overall, our findings suggest that ART's protective effect against AILI is mediated through the Nrf2-related antioxidant pathway.

Mifepristone protects acetaminophen induced liver injury through NRF2/GSH/GST mediated ferroptosis suppression

Ferroptosis is a form of iron-dependent cell death that has attracted significant attention for its potential role in numerous diseases. Targeted inhibition of ferroptosis could be of potential use in treating diseases: such as drug induced liver injury (DILI). Ferroptosis can be antagonized by the xCT/GSH/GPX4, FSP1/CoQ10, DHODH/CoQ10, GCH1/BH4, and NRF2 pathways. Identifying novel anti-ferroptosis pathways will further promote our understanding of the biological nature of ferroptosis and help discover new drugs targeting ferroptosis related human diseases. In this study, we identified the clinically used drug mifepristone (RU486) as a novel ferroptosis inhibitor. Mechanistically, RU486 inhibits ferroptosis by inducing GSH synthesis pathway, which supplies GSH for glutathione-S-transferase (GST) mediated 4-HNE detoxification. Furthermore, RU486 induced RLIP76 and MRP1 export 4-HNE conjugate contributes to its anti-ferroptosis activity. Interestingly, RU486 induced GSH/GSTs/RLIP76&MRP1 anti-ferroptosis pathway acts independent of classic anti-ferroptosis systems: including xCT/GSH/GPX4, FSP1, DHODH, GCH1, SCD1 and FTH1. Moreover, NRF2 was identified to be important for RU486's anti-ferroptosis activity by inducing downstream gene expression. Importantly, in mouse model, RU486 showed strong protection effect on acetaminophen (APAP)-induced acute liver injury, evidenced by decreased ALT, AST level and histological recovery after APAP treatment. Interestingly, RU486 also decreased oxidative markers, including 4-HNE and MDA, and induced NRF2 activation as well as GSTs, MRP1 expression. Together, these data suggest NRF2/GSH/GST/RLIP76&MRP1 mediated detoxification pathway as an important independent anti-ferroptosis pathway act both in vitro and in vivo.

Effects of jujube (Ziziphus jujuba mill.) fruit extracts on oxidative stress: A systematic review and meta-analysis of rodent studies

This study aimed to evaluate the effects of jujube (Ziziphus jujuba Mill.) fruit extracts on oxidative stress levels in rodent models. Animal studies meeting the inclusion criteria were retrieved from PubMed, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), Wanfang Data Knowledge Service Platform, and VIP Periodical Service Platform. The Systematic Review Center for Laboratory Animal Experimentation (SYRCLE) risk-of-bias tool was used to evaluate the risk of bias in the included studies. A meta-analysis was performed based on the guidelines provided in the Cochrane Handbook for Systematic Reviews of Interventions (CHSRI) by using Stata 17.0 software. Nineteen studies were included in the meta-analysis. Jujube fruit extracts significantly decreased the level of malonaldehyde (MDA) and increased the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Meanwhile, there was no significant improvement in the catalase (CAT) levels. In addition, there was considerable heterogeneity in the results of the meta-analysis. The results of the subgroup analysis indicated that the animal model, type of extracts, and source of target parameters may have contributed to the heterogeneity. Jujube fruit extracts are healthy and effective antioxidant dietary supplements that may be an effective adjunctive therapy for diseases in which oxidative stress is a major pathological factor. However, the overall methodological quality of the included studies was low, and additional research is warranted.

Neutrophil extracellular traps promote acetaminophen-induced acute liver injury in mice via AIM2

Excessive acetaminophen (APAP) can induce neutrophil activation and hepatocyte death. Along with hepatocyte dysfunction and death, NETosis (a form of neutrophil-associated inflammation) plays a vital role in the progression of acute liver injury (ALI) induced by APAP overdose. It has been shown that activated neutrophils tend to migrate towards the site of injury and participate in inflammatory processes via formation of neutrophil extracellular traps (NETs). In this study we investigated whether NETs were involved in hepatocyte injury and contributed to APAP-induced ALI progression. ALI mouse model was established by injecting overdose (350 mg/kg) of APAP. After 24 h, blood and livers were harvested for analyses. We showed that excessive APAP induced multiple programmed cell deaths of hepatocytes including pyroptosis, apoptosis and necroptosis, accompanied by significantly increased NETs markers (MPO, citH3) in the liver tissue and serum. Preinjection of DNase1 (10 U, i.p.) for two consecutive days significantly inhibited NETs formation, reduced PANoptosis and consequently alleviated excessive APAP-induced ALI. In order to clarify the communication between hepatocytes and neutrophils, we induced NETs formation in isolated neutrophils, and treated HepaRG cells with NETs. We found that NETs treatment markedly increased the activation of GSDMD, caspase-3 and MLKL, while pre-treatment with DNase1 down-regulated the expression of these proteins. Knockdown of AIM2 (a cytosolic innate immune receptor) abolished NETs-induced PANoptosis in HepaRG cells. Furthermore, excessive APAP-associated ALI was significantly attenuated in AIM2KO mice, and PANoptosis occurred less frequently. Upon restoring AIM2 expression in AIM2KO mice using AAV9 virus, both hepatic injury and PANoptosis was aggravated. In addition, we demonstrated that excessive APAP stimulated mtROS production and mitochondrial DNA (mtDNA) leakage, and mtDNA activated the TLR9 pathway to promote NETs formation. Our results uncover a novel mechanism of NETs and PANoptosis in APAP-associated ALI, which might serve as a therapeutic target.

Direct targeting of S100A9 with Icariin counteracted acetaminophen‑induced hepatotoxicity

Acetaminophen (APAP) is a widely used antipyretic and analgesic medication, but its overdose can induce acute liver failure with lack of effective therapies. Icariin is a bioactive compound derived from the herb Epimedium that displays hepatoprotective activities. Here, we explored the protective effects and mechanism of icariin on APAP-induced hepatotoxicity. Icariin (25/50 mg/kg) or N-Acetylcysteine (NAC, 300 mg/kg) were orally administered in wild-type C57BL/6 mice for 7 consecutive days before the APAP administration. Icariin attenuated APAP-induced acute liver injury in mice, as measured by alleviated serum enzymes activities and hepatic apoptosis. In vitro, icariin pretreatment significantly inhibited hepatocellular damage and apoptosis by reducing the BAX/Bcl-2 ratio as well as the expression of cleaved-caspase 3 and cleaved-PARP depended on the p53 pathway. Moreover, icariin attenuated APAP-mediated inflammatory response and oxidative stress via the Nrf2 and NF-κB pathways. Importantly, icariin reduced the expression of S100A9, icariin interacts with S100A9 as a direct cellular target, which was supported by molecular dynamics simulation and surface plasmon resonance assay (equilibrium dissociation constant, KD = 1.14 μM). In addition, the genetic deletion and inhibition of S100A9 not only alleviated APAP-induced injury but also reduced the icariin's protective activity in APAP-mediated liver injury. These data indicated that icariin targeted S100A9 to alleviate APAP-induced liver damage via the following signaling pathways NF-κB, p53, and Nrf2.

The Role of Mechanistic Biomarkers in Understanding Acetaminophen Hepatotoxicity in Humans

Our understanding of the fundamental molecular mechanisms of acetaminophen (APAP) hepatotoxicity began in 1973 to 1974, when investigators at the US National Institutes of Health published seminal studies demonstrating conversion of APAP to a reactive metabolite that depletes glutathione and binds to proteins in the liver in mice after overdose. Since then, additional groundbreaking experiments have demonstrated critical roles for mitochondrial damage, oxidative stress, nuclear DNA fragmentation, and necrotic cell death as well. Over the years, some investigators have also attempted to translate these mechanisms to humans using human specimens from APAP overdose patients. This review presents those studies and summarizes what we have learned about APAP hepatotoxicity in humans so far. Overall, the mechanisms of APAP hepatotoxicity in humans strongly resemble those discovered in experimental mouse and cultured hepatocyte models, and emerging biomarkers also suggest similarities in liver repair. The data not only validate the first mechanistic studies of APAP-induced liver injury performed 50 years ago but also demonstrate the human relevance of numerous studies conducted since then. SIGNIFICANCE STATEMENT: Human studies using novel translational, mechanistic biomarkers have confirmed that the fundamental mechanisms of acetaminophen (APAP) hepatotoxicity discovered in rodent models since 1973 are the same in humans. Importantly, these findings have guided the development and understanding of treatments such as N-acetyl-l-cysteine and 4-methylpyrazole over the years. Additional research may improve not only our understanding of APAP overdose pathophysiology in humans but also our ability to predict and treat serious liver injury in patients.

Identification and validation of cuproptosis-related genes in acetaminophen-induced liver injury using bioinformatics analysis and machine learning

Background

Acetaminophen (APAP) is commonly used as an antipyretic analgesic. However, acetaminophen overdose may contribute to liver injury and even liver failure. Acetaminophen-induced liver injury (AILI) is closely related to mitochondrial oxidative stress and dysfunction, which play critical roles in cuproptosis. Here, we explored the potential role of cuproptosis-related genes (CRGs) in AILI.

Methods

The gene expression profiles were obtained from the Gene Expression Omnibus database. The differential expression of CRGs was determined between the AILI and control samples. Protein protein interaction, correlation, and functional enrichment analyses were performed. Machine learning was used to identify hub genes. Immune infiltration was evaluated. The AILI mouse model was established by intraperitoneal injection of APAP solution. Quantitative real-time PCR and western blotting were used to validate hub gene expression in the AILI mouse model. The copper content in the mouse liver samples and AML12 cells were quantified using a colorimetric assay kit. Ammonium tetrathiomolybdate (ATTM), was administered to mouse models and AML12 cells in order to investigate the effects of copper chelator on AILI.

Results

The analysis identified 7,809 differentially expressed genes, 4,245 of which were downregulated and 3,564 of which were upregulated. Four optimal feature genes (OFGs; SDHB, PDHA1, NDUFB2, and NDUFB6) were identified through the intersection of two machine learning algorithms. Further nomogram, decision curve, and calibration curve analyses confirmed the diagnostic predictive efficacy of the four OFGs. Enrichment analysis indicated that the OFGs were involved in multiple pathways, such as IL-17 pathway and chemokine signaling pathway, that are related to AILI progression. Immune infiltration analysis revealed that macrophages were more abundant in AILI than in control samples, whereas eosinophils and endothelial cells were less abundant. Subsequently, the AILI mouse model was successfully established, and histopathological analysis using hematoxylin-eosin staining along with liver function tests revealed a significant induction of liver injury in the APAP group. Consistent with expectations, both mRNA and protein levels of the four OFGs exhibited a substantial decrease. The administration of ATTAM effectively mitigates copper elevation induced by APAP in both mouse model and AML12 cells. However, systemic administration of ATTM did not significantly alleviate AILI in the mouse model.

Conclusion

This study first revealed the potential role of CRGs in the pathological process of AILI and offered novel insights into its underlying pathogenesis.

Dose-dependent effects of acetaminophen and ibuprofen on mitochondrial respiration of human platelets

Acetaminophen and ibuprofen are widely used over-the-counter medications to reduce fever, pain, and inflammation. Although both drugs are safe in therapeutic concentrations, self-medication is practiced by millions of aged patients with comorbidities that decrease drug metabolism and/or excretion, thus raising the risk of overdosage. Mitochondrial dysfunction has emerged as an important pathomechanism underlying the organ toxicity of both drugs. Assessment of mitochondrial oxygen consumption in peripheral blood cells is a novel research field Cu several applications, including characterization of drug toxicity. The present study, conducted in human platelets isolated from blood donor-derived buffy coat, was aimed at assessing the acute, concentration-dependent effects of each drug on mitochondrial respiration. Using the high-resolution respirometry technique, a concentration-dependent decrease of oxygen consumption in both intact and permeabilized platelets was found for either drug, mainly by inhibiting complex I-supported active respiration. Moreover, ibuprofen significantly decreased the maximal capacity of the electron transport system already from the lowest concentration. In conclusion, platelets from healthy donors represents a population of cells easily available, which can be routinely used in studies assessing mitochondrial drug toxicity. Whether these results can be recapitulated in patients treated with these medications is worth further investigation as potential peripheral biomarker of drug overdose.

Dabrafenib alleviates hepatotoxicity caused by lenvatinib via inhibiting the death receptor signaling pathway

Lenvatinib is a multi-target inhibitor that exerts anti-tumor effects by inhibiting angiogenesis and is now commonly used as a first-line treatment for hepatocellular carcinoma. However, with the widespread use of lenvatinib, the problem of serious and fatal hepatotoxicity has become increasingly prominent. Currently, the mechanism behind this toxicity is not yet understood, and as a result, there is a lack of safe and effective intervention strategies with minimal side effects. Here, we established the model of lenvatinib-induced liver injury in vivo and in vitro and found that lenvatinib caused hepatotoxicity by inducing apoptosis. Further mechanistic studies in cellular models revealed that lenvatinib upregulated death receptor signaling pathway, which activated the downstream effector Caspase-8, and ultimately led to apoptosis. Meanwhile, lenvatinib-induced apoptosis was associated with ROS generation and DNA damage. In addition, after screening marketed drugs and natural products in combination with cellular modeling, we identified a potential co-administered drug, dabrafenib, which could alleviate lenvatinib-induced hepatotoxicity. Further mechanistic studies revealed that dabrafenib attenuated lenvatinib-induced hepatotoxicity by inhibiting the activation of the death receptor signaling pathway. Subsequently, cancer cell proliferation assays confirmed that dabrafenib did not antagonize the antitumor effects of lenvatinib. In conclusion, our results validate that apoptosis caused by the death receptor signaling pathway is the key cause of lenvatinib-induced hepatotoxicity, and dabrafenib alleviates lenvatinib-induced hepatotoxicity by inhibiting this pathway.

Opioid use and risks in candidates and recipients of liver transplant

Opioid use is extremely prevalent among patients with cirrhosis and those who received liver transplant (LT), despite concerns regarding opioid-related risks in this population. While there are many theoretical risks of opioids in patients with hepatic dysfunction, there is limited evidence on the effect of opioid use on clinical outcomes in cirrhosis and patients before and after LT specifically. As a result, there is significant center-level variability in opioid-related practices and policies. The existing data-largely based on retrospective observational studies-do suggest that opioids are associated with increased health resource utilization pre-LT and post-LT and that they may precipitate HE in patients with cirrhosis and increase the risk of graft loss and death after LT. The strongest predictor of opioid use after LT is opioid use before transplant; thus, a focus on safe opioid use in the pretransplant and peritransplant periods is essential for minimizing opioid-related harms. We describe 3 strategies to guide LT providers including (1) improved characterization of pain, mental health symptoms, and opioid and polysubstance use; (2) minimization of opioid prescriptions for those at highest risk of adverse events; and (3) safe prescribing strategies for those who do use opioids and for the management of opioid use disorder. Ultimately, our goal is to improve the quality of life and transplant outcomes among patients with cirrhosis and those who received LT, particularly those living with concurrent pain, mental health, and substance use disorders.

Hepatic Sirt6 activation abrogates acute liver failure

Acute liver failure (ALF) is a deadly illness due to insufficient detoxification in liver induced by drugs, toxins, and other etiologies, and the effective treatment for ALF is very limited. Among the drug-induced ALF, acetaminophen (APAP) overdose is the most common cause. However, the molecular mechanisms underlying APAP hepatoxicity remain incompletely understood. Sirtuin 6 (Sirt6) is a stress responsive protein deacetylase and plays an important role in regulation of DNA repair, genomic stability, oxidative stress, and inflammation. Here, we report that genetic and pharmacological activation of Sirt6 protects against ALF in mice. We first observed that Sirt6 expression was significantly reduced in the liver tissues of human patients with ALF and mice treated with an overdose of APAP. Then we developed an inducible Sirt6 transgenic mice for Cre-mediated overexpression of the human Sirt6 gene in systemic (Sirt6-Tg) and hepatic-specific (Sirt6-HepTg) manners. Both Sirt6-Tg mice and Sirt6-HepTg mice exhibited the significant protection against APAP hepatoxicity. In contrast, hepatic-specific Sirt6 knockout mice exaggerated APAP-induced liver damages. Mechanistically, Sirt6 attenuated APAP-induced hepatocyte necrosis and apoptosis through downregulation of oxidative stress, inflammation, the stress-activated kinase JNK activation, and apoptotic caspase activation. Moreover, Sirt6 negatively modulated the level and activity of poly (ADP-ribose) polymerase 1 (PARP1) in APAP-treated mouse liver tissues. Importantly, the specific Sirt6 activator MDL-800 exhibited better therapeutic potential for APAP hepatoxicity than the current drug acetylcysteine. Furthermore, in the model of bile duct ligation induced ALF, hepatic Sirt6-KO exacerbated, but Sirt6-HepTg mitigated liver damage. Collectively, our results demonstrate that Sirt6 protects against ALF and suggest that targeting Sirt6 activation could be a new therapeutic strategy to alleviate ALF.

Natural Products That Protect Against Acetaminophen Hepatotoxicity: A Call for Increased Rigor in Preclinical Studies of Dietary Supplements

Acetaminophen (APAP) overdose is one of the most common causes of acute liver injury. The current standard-of-care treatment for APAP hepatotoxicity, N-acetyl-l-cysteine, is highly effective when administered early after overdose, but loses efficacy in later-presenting patients. As a result, there is interest in the identification of new treatments for APAP overdose patients. Natural products are a promising source of new treatments because many are purported to have hepatoprotective effects. In fact, a great deal of research has been done to identify natural products that can protect against APAP-induced liver injury. However, serious concerns have been raised about the rigor and human relevance of these studies. Here, we systematically reviewed the APAP-natural product literature from 2013 to 2023 to determine the veracity of these concerns and the scope of the potential problem. The results substantiate the concerns that have been previously raised and point to concrete steps that can be taken to improve APAP-natural product research.

Regulatory mechanism and therapeutic potentials of naringin against inflammatory disorders

Naringin is a natural flavonoid with therapeutic properties found in citrus fruits and an active natural product from herbal plants. Naringin has become a focus of attention in recent years because of its ability to actively participate in the body's immune response and maintain the integrity of the immune barrier. This review aims to elucidate the mechanism of action and therapeutic efficacy of naringin in various inflammatory diseases and to provide a valuable reference for further research in this field. The review provided the chemical structure, bioavailability, pharmacological properties, and pharmacokinetics of naringin and found that naringin has good therapeutic potential for inflammatory diseases, exerting anti-inflammatory, anti-apoptotic, anti-oxidative stress, anti-ulcerative and detoxifying effects in the disease. Moreover, we found that the great advantage of naringin treatment is that it is safe and can even alleviate the toxic side effects associated with some of the other drugs, which may become a highlight of naringin research. Naringin, an active natural product, plays a significant role in systemic diseases' anti-inflammatory and antioxidant regulation through various signaling pathways and molecular mechanisms.

Association between acetaminophen administration and clinical outcomes in patients with sepsis admitted to the ICU: a retrospective cohort study

Background

Sepsis, affecting over 30 million people worldwide each year, is a key mortality risk factor in critically ill patients. There are significant regional discrepancies in its impact. Acetaminophen, a common over-the-counter drug, is often administered to control fever in suspected infection cases in intensive care units (ICUs). It is considered generally safe when used at therapeutic levels. Despite its widespread use, there's inconsistent research regarding its efficacy in sepsis management, which creates uncertainties for ICU doctors about its possible advantages or harm. To address this, we undertook a retrospective cohort study utilizing the MIMIC-IV database to examine the correlation between acetaminophen use and clinical outcomes in septic patients admitted to the ICU.

Methods

We gathered pertinent data on sepsis patients from the MIMIC-IV database. We used propensity score matching (PSM) to pair acetaminophen-treated patients with those who were not treated. We then used Cox Proportional Hazards models to examine the relationships between acetaminophen use and factors such as in-hospital mortality, 30-day mortality, hospital stay duration, and ICU stay length.

Results

The data analysis involved 22,633 sepsis patients. Post PSM, a total of 15,843 patients were matched; each patient not receiving acetaminophen treatment was paired with two patients who received it. There was a correlation between acetaminophen and a lower in-hospital mortality rate (HR 0.443; 95% CI 0.371-0.530; p < 0.001) along with 30-day mortality rate (HR 0.497; 95% CI 0.424-0.583; p < 0.001). Additionally, it correlated with a decrease in the duration of hospitalization [8.4 (5.0, 14.8) vs. 9.0 (5.1, 16.0), p < 0.001] and a shorter ICU stay [2.8 (1.5, 6.0) vs. 3.1 (1.7, 6.5); p < 0.05].

Conclusion

The use of acetaminophen may lower short-term mortality in critically ill patients with sepsis. To confirm this correlation, future research should involve multicenter randomized controlled trials.

Exploring Bacterial Cellulose and a Biosurfactant as Eco-Friendly Strategies for Addressing Pharmaceutical Contaminants

Aquatic environments face contamination by pharmaceuticals, prompting concerns due to their toxicity even at low concentrations. To combat this, we developed an ecologically sustainable biosurfactant derived from a microorganism and integrated it into bacterial cellulose (BC). This study aimed to evaluate BC's efficacy, with and without the biosurfactant, as a sorbent for paracetamol and 17α-ethinylestradiol (EE2) in water. We cultivated BC membranes using Gluconacetobacter xylinus ATCC 53582 and synthesized the biosurfactant through pre-inoculation of Bacillus subtilis in a synthetic medium. Subsequently, BC membranes were immersed in the biosurfactant solution for incorporation. Experiments were conducted using contaminated water, analyzing paracetamol concentrations via spectrophotometry and EE2 levels through high-performance liquid chromatography. Results indicated BC's superior adsorption for EE2 over paracetamol. Incorporating the biosurfactant reduced hormone adsorption but enhanced paracetamol sorption. Notably, original and freeze-dried BC exhibited better adsorption efficacy than biosurfactant-infused BC. In conclusion, BC showed promise in mitigating EE2 contamination, suggesting its potential for environmental remediation. Future research could focus on optimizing biosurfactant concentrations to enhance sorption capabilities without compromising BC's inherent effectiveness.

Mechanistic insights into aniline-induced liver injury: Role of the mmu_circ_26984/Myh9/NLRP3 axis and modulation by N-acetylcysteine

Aniline is a widely used chemical. Chronic or high-dose exposure to aniline can lead to hepatocellular damage. Although the hepatic pathogenicity of aniline has been established in previous studies, studies involving pathogenic genes during aniline-induced liver injury are limited. Our study first discovered and identified the role and mechanism underlying a new circRNA mmu_circ_26984 in aniline-induced chemical liver injury. Further, we discuss the protective effect of N-acetylcysteine (NAC) in this pathway. After constructing in vitro and in vivo models of aniline treatment, we screened the circRNA with significant differences in expression in AML12 cells from control and aniline-treated groups by circRNA microarray analysis. Next, using RNA pulldown, liquid chromatography-mass spectrometry (LC-MS), and RNA immunoprecipitation, we analyzed the relationship between mmu_circ_26984 and myosin heavy chain 9 (Myh9). Subsequently, we determined the specific mechanism of action of mmu_circ_26984 and Myh9 in aniline-induced liver injury and the protective effect of NAC against aniline-induced liver injury process using Cell Counting Kit-8, Western blot, RNA extraction, a reverse transcription quantitative polymerase chain reaction (RT-qPCR), fluorescence in situ hybridization, immunohistochemistry, and immunofluorescence. The expression of mmu_circ_26984 was significantly increased in liver tissues and AML12 cells of aniline-treated mice compared with the control group. This high expression of mmu_circ_26984 increased the expression of injury-related inflammatory factors, such as NLRP3, Caspase-1, IL-18, and IL-1β in vivo and ex vivo, which exacerbated the level of liver injury. The interaction of mmu_circ_26984 with Myh9 also affected the course of liver injury. Mmu_circ_26984 overexpression and reduced treatment affected the levels of Myh9 expression in AML12 cells, as well as downstream inflammatory factors associated with injury, such as NLRP3. In addition, NAC reduced the process of liver injury mediated by the mmu_circ_26984/Myh9/NLRP3 axis. In conclusion, mmu_circ_26984 is a potential molecular marker and therapeutic target in the process of aniline-induced liver injury that can mediate aniline-exposure-induced liver injury via modulation of the mmu_circ_26984/Myh9/NLRP3 axis, and NAC can effectively attenuate the effect of this liver injury.

The Evolution of Circulating Biomarkers for Use in Acetaminophen/Paracetamol-Induced Liver Injury in Humans: A Scoping Review

Acetaminophen (APAP) is a widely used drug, but overdose can cause severe acute liver injury. The first reports of APAP hepatotoxicity in humans were published in 1966, shortly after the development of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as the first biomarkers of liver injury as opposed to liver function. Thus, the field of liver injury biomarkers has evolved alongside the growth in APAP hepatotoxicity incidence. Numerous biomarkers have been proposed for use in the management of APAP overdose patients in the intervening years. Here, we comprehensively review the development of these markers from the 1960s to the present day and briefly discuss possible future directions.

Hepatic pyruvate and alanine metabolism are critical and complementary for maintenance of antioxidant capacity and resistance to oxidative insult

OBJECTIVE

Mitochondrial pyruvate is a critical intermediary metabolite in gluconeogenesis, lipogenesis, and NADH production. As a result, the mitochondrial pyruvate carrier (MPC) complex has emerged as a promising therapeutic target in metabolic diseases. Clinical trials are currently underway. However, recent in vitro data indicate that MPC inhibition diverts glutamine/glutamate away from glutathione synthesis and toward glutaminolysis to compensate for loss of pyruvate oxidation, possibly sensitizing cells to oxidative insult. Here, we explored this in vivo using the clinically relevant acetaminophen (APAP) overdose model of acute liver injury, which is driven by oxidative stress.

METHODS

We used pharmacological and genetic approaches to inhibit MPC2 and alanine aminotransferase 2 (ALT2), individually and concomitantly, in mice and cell culture models and determined the effects on APAP hepatotoxicity.

RESULTS

We found that MPC inhibition sensitizes the liver to APAP-induced injury in vivo only with concomitant loss of alanine aminotransferase 2 (ALT2). Pharmacological and genetic manipulation of neither MPC2 nor ALT2 alone affected APAP toxicity, but liver-specific double knockout (DKO) significantly worsened APAP-induced liver damage. Further investigation indicated that DKO impaired glutathione synthesis and increased urea cycle flux, consistent with increased glutaminolysis, and these results were reproducible in vitro. Finally, induction of ALT2 and post-treatment with dichloroacetate both reduced APAP-induced liver injury, suggesting new therapeutic avenues.

CONCLUSIONS

Increased susceptibility to APAP toxicity requires loss of both the MPC and ALT2 in vivo, indicating that MPC inhibition alone is insufficient to disrupt redox balance. Furthermore, the results from ALT2 induction and dichloroacetate in the APAP model suggest new metabolic approaches to the treatment of liver damage.

The Role of Carbamoyl Phosphate Synthetase 1 as a Prognostic Biomarker in Patients With Acetaminophen-induced Acute Liver Failure

BACKGROUND & AIMS

Carbamoyl phosphate synthetase 1 (CPS1) is a highly abundant mitochondrial urea cycle enzyme that is expressed primarily in hepatocytes. CPS1 is constitutively and physiologically secreted into bile but is released into the bloodstream upon acute liver injury (ALI). Given its abundance and known short half-life, we tested the hypothesis that it may serve as a prognostic serum biomarker in the setting of acute liver failure (ALF).

METHODS

CPS1 levels were determined using enzyme-linked immunosorbent assay and immunoblotting of sera collected by the ALF Study Group (ALFSG) from patients with ALI and ALF (103 patients with acetaminophen and 167 non-acetaminophen ALF etiologies). A total of 764 serum samples were examined. The inclusion of CPS1 was compared with the original ALFSG Prognostic Index by area under the receiver operating characteristic curve analysis.

RESULTS

CPS1 values for acetaminophen-related patients were significantly higher than for non-acetaminophen patients (P < .0001). Acetaminophen-related patients who received a liver transplant or died within 21 days of hospitalization exhibited higher CPS1 levels than patients who spontaneously survived (P = .01). Logistic regression and area under the receiver operating characteristic analysis of CPS1 enzyme-linked immunosorbent assay values improved the accuracy of the ALFSG Prognostic Index, which performed better than the Model for End-Stage Liver Disease, in predicting 21-day transplant-free survival for acetaminophen- but not non-acetaminophen-related ALF. An increase of CPS1 but not alanine transaminase or aspartate transaminase, when comparing day 3 with day 1 levels was found in a higher percentage of acetaminophen transplanted/dead patients (P < .05).

CONCLUSION

Serum CPS1 determination provides a new potential prognostic biomarker to assess patients with acetaminophen-induced ALF.

6-Hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline Demonstrates Anti-Inflammatory Properties and Reduces Oxidative Stress in Acetaminophen-Induced Liver Injury in Rats

We examined the effects of 6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline on markers of liver injury, oxidative status, and the extent of inflammatory and apoptotic processes in rats with acetaminophen-induced liver damage. The administration of acetaminophen caused the accumulation of 8-hydroxy-2-deoxyguanosine and 8-isoprostane in the liver and serum, as well as an increase in biochemiluminescence indicators. Oxidative stress resulted in the activation of pro-inflammatory cytokine and NF-κB factor mRNA synthesis and increased levels of immunoglobulin G, along with higher activities of caspase-3, caspase-8, and caspase-9. The administration of acetaminophen also resulted in the development of oxidative stress, leading to a decrease in the level of reduced glutathione and an imbalance in the function of antioxidant enzymes. This study discovered that 6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline reduced oxidative stress by its antioxidant activity, hence reducing the level of pro-inflammatory cytokine and NF-κB mRNA, as well as decreasing the concentration of immunoglobulin G. These changes resulted in a reduction in the activity of caspase-8 and caspase-9, which are involved in the activation of ligand-induced and mitochondrial pathways of apoptosis and inhibited the effector caspase-3. In addition, 6-hydroxy-2,2,4-trimethyl-1,2-dihydroquinoline promoted the normalization of antioxidant system function in animals treated with acetaminophen. As a result, the compound being tested alleviated inflammation and apoptosis by decreasing oxidative stress, which led to improved liver marker indices and ameliorated histopathological alterations.

Methodological considerations of the acetaminophen Detection Kit®: Involvement of molecular oxygen (O2) in an indophenol reaction

The Acetaminophen Detection Kit® (Kanto Chemical Company Co. Inc., Tokyo, Japan) is a colorimetric test based on an indophenol reaction. The test involves three reactions: deproteination of the sample, hydrolysis of acetaminophen to yield p-aminophenol, and coupling p-aminophenol with a derivative of phenol in alkali conditions to form a blue-colored indophenol dye. The kit was devised to accomplish these three reactions with only two reagents, allowing the prompt diagnosis of acetaminophen overdose in emergency medicine. In the user instructions included with the kit and in reports introducing the kit, the chemical composition of the two reagents was not disclosed. Details about the composition can be found in the Safety Data Sheet from the manufacturer; however, there is little explanation about the principle (mechanism) of the coupling reaction. This lack of information appears to have hampered the use of this kit in forensic medicine. In this report, we conducted the coupling reaction by successively adding the two reagents to a p-aminophenol (intermediate molecule) solution with the reaction vessel open to the air and under an anaerobic condition. Development of the blue color was inhibited in the absence of air but gradually developed when the reaction vessel was opened to air. Thus, the coupling reaction is an oxidation-reduction (redox) reaction that requires molecular oxygen (O₂) dissolved from the air to act as an oxidant. This finding corroborates statements in previous reports and will hopefully facilitate the use of the kit for forensic purposes.

Review: Organophosphorus toxicants, in addition to inhibiting acetylcholinesterase activity, make covalent adducts on multiple proteins and promote protein crosslinking into high molecular weight aggregates

The acute effects of exposure to organophosphorus toxicants are explained by inhibition of acetylcholinesterase activity. However, the mechanisms that explain long term illness associated with organophosphorus exposure are still under investigation. We find that organophosphorus nerve agents and organophosphorus pesticides make covalent adducts not only on the serine from acetylcholinesterase, but also on tyrosine, lysine, glutamate, serine and threonine from a variety of proteins. Almost any protein can be modified by a high dose of organophosphorus toxicant. A low dose of 10 μM chlorpyrifos oxon added to the serum-free culture medium of human neuroblastoma SH-SY5Y cells resulted in tyrosine adducts on 48 proteins immunopurified from the cell lysate. We identified the adducted proteins by mass spectrometry after immunopurifying modified proteins with a rabbit anti-diethoxyphospho-tyrosine monoclonal antibody which biased this study for tyrosine adducts. In cultured cells, the primary organophosphate targets are abundant proteins. Organophosphate-modified proteins may disrupt physiological processes. In separate experiments we identified organophosphate adducts on lysine. Organophosphylation activates the lysine for protein crosslinking. The activated lysine reacts with glutamic acid or aspartic acid protein side chains to form an isopeptide bond between proteins, resulting in high molecular weight crosslinked proteins. Crosslinked proteins form insoluble aggregates that may lead to neurogenerative disease.

8-methoxypsoralen protects against acetaminophen-induced liver injury by antagonising Cyp2e1 in mice

This study aimed to investigate the effect and mechanism of 8-methoxypsoralen (8-MOP) on acetaminophen (APAP)-induced hepatotoxicity in mice. The study found that one hour after intraperitoneal injection of 300 mg/kg APAP, treatment with 40 mg/kg,80 mg/kg and 120 mg/kg 8-MOP could reduce serum transaminase level and histopathological liver necrosis area. Elevated mRNA expression of liver inflammatory mediators caused by excessive APAP was also reversed. 8-MOP significantly reduced APAP-induced hepatotoxicity dose-dependently, and the highest therapeutic dose of 8-MOP (120 mg/kg) had no harmful effects on the liver. Cocktail probe assay revealed that 8-MOP can inhibit Cyp2e1 enzymatic activities of mice, thereby reducing the production of acetaminophen-cysteine (APAP-CYS), a toxic metabolite of APAP. 8-MOP had no significant effect on the protein and gene expression of Cyp2e1. The three-dimensional structures of mouse Cyp2e1 were constructed by homologous modeling. Molecular docking showed that 8-MOP had a good binding effect on the enzyme activity site of Cyp2e1. In summary, 8-MOP dose-dependently attenuated APAP-induced hepatotoxicity by binding to Cyp2e1 and occupying the active center of the enzyme, thus competitively inhibiting the oxidative metabolism of APAP, and reducing the generation of toxic product APAP-CYS.

Mitoquinone protects against acetaminophen-induced liver injury in an FSP1-dependent and GPX4-independent manner

Mitochondrial oxidative stress has been a crucial mediator in acetaminophen (APAP)-induced hepatotoxicity. MitoQ, an analog of coenzyme Q10, is targeted towards mitochondria and acts as a potent antioxidant. This study aimed to explore the effect of MitoQ on APAP-induced liver injury and its possible mechanisms. To investigate this, CD-1 mice and AML-12 cells were treated with APAP. Hepatic MDA and 4-HNE, two markers of lipid peroxidation (LPO), were elevated as early as 2 h after APAP. Oxidized lipids were rapidly upregulated in APAP-exposed AML-12 cells. Hepatocyte death and mitochondrial ultrastructure alterations were observed in APAP-induced acute liver injury. The in vitro experiments showed that mitochondrial membrane potentials and OXPHOS subunits were downregulated in APAP-exposed hepatocytes. MtROS and oxidized lipids were elevated in APAP-exposed hepatocytes. We discovered that APAP-induced hepatocyte death and liver injury were ameliorated by attenuation of protein nitration and LPO in MitoQ-pretreated mice. Mechanistically, knockdown of GPX4, a key enzyme for LPO defense systems, exacerbated APAP-induced oxidized lipids, but did not influence the protective effect of MitoQ on APAP-induced LPO and hepatocyte death. Whereas knockdown of FSP1, another key enzyme for LPO defense systems, had little effect on APAP-induced lipid oxidation but partially weakened the protection of MitoQ on APAP-induced LPO and hepatocyte death. These results suggest that MitoQ may alleviate APAP-evoked hepatotoxicity by eliminating protein nitration and suppressing hepatic LPO. MitoQ prevents APAP-induced liver injury partially dependent of FSP1 and independent of GPX4.

Acetaminophen-Induced Hepatotoxicity in Obesity and Nonalcoholic Fatty Liver Disease: A Critical Review

The epidemic of obesity, type 2 diabetes and nonalcoholic liver disease (NAFLD) favors drug consumption, which augments the risk of adverse events including liver injury. For more than 30 years, a series of experimental and clinical investigations reported or suggested that the common pain reliever acetaminophen (APAP) could be more hepatotoxic in obesity and related metabolic diseases, at least after an overdose. Nonetheless, several investigations did not reproduce these data. This discrepancy might come from the extent of obesity and steatosis, accumulation of specific lipid species, mitochondrial dysfunction and diabetes-related parameters such as ketonemia and hyperglycemia. Among these factors, some of them seem pivotal for the induction of cytochrome P450 2E1 (CYP2E1), which favors the conversion of APAP to the toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). In contrast, other factors might explain why obesity and NAFLD are not always associated with more frequent or more severe APAP-induced acute hepatotoxicity, such as increased volume of distribution in the body, higher hepatic glucuronidation and reduced CYP3A4 activity. Accordingly, the occurrence and outcome of APAP-induced liver injury in an obese individual with NAFLD would depend on a delicate balance between metabolic factors that augment the generation of NAPQI and others that can mitigate hepatotoxicity.

Curcuma aromatica Salisb. Protects from Acetaminophen-Induced Hepatotoxicity by Regulating the Sirt1/HO-1 Signaling Pathway

Acetaminophen (APAP) overdose-induced hepatotoxicity reduces the activity of sirtuin-1 (Sirt1) along with heme oxygenase 1 (HO-1) and promotes inflammatory responses and oxidative stress. Although the extract of Curcuma aromatica Salisb. (CAS) possesses hepatoprotective properties, scientific evidence on whether CAS prevents hepatotoxicity and the underlying molecular mechanisms are lacking. Here, we hypothesized that CAS ameliorates hepatotoxicity by inhibiting inflammation and oxidative stress via Sirt1/HO-1 signaling. CAS pretreatment at doses of 200 and 400 μg/mL significantly increased cell viability in APAP-treated primary hepatocytes. The expression of inducible nitric oxide synthase (iNOS) substantially increased after APAP treatment; however, this expression significantly decreased in cells pretreated with 100, 200, and 400 µg/mL CAS. CAS increased Sirt1 and HO-1 levels in APAP-treated hepatocytes in a dose-dependent manner. When CAS was orally administered to mice at doses of 20 or 100 mg/kg for 7 days, the APAP-induced increase in serum aspartate aminotransferase and alanine aminotransferase levels was inhibited. Moreover, CAS decreased IL-6, TNF-α, and IL-1β, increased IL-10, suppressed ROS generation, increased glutathione levels, inhibited iNOS and cyclooxygenase-2, and enhanced Sirt1 and HO-1 in the mouse model of APAP-induced hepatotoxicity. These findings suggest that CAS could be used as a natural hepatoprotective drug to treat APAP-induced injury.

Overview of Adductomics in Toxicology

Adductomics is epidemiology at the molecular level. Untargeted adductomics compares levels of chemical adducts on albumin, hemoglobin, and DNA between healthy and exposed individuals. The goal is to determine a cause-and-effect relationship between chemical exposure and illness. Chemical exposures are not necessarily due to synthetic chemicals but are often due to oxidation products of naturally occurring lipids, for example, 4-hydroxynonenal and acrolein produced by lipid peroxidation of arachidonic and linoleic acids. The preferred method used in adductomics is ultra-high pressure liquid chromatography coupled to with nanoelectrospray tandem mass spectrometry. The mass of the adduct indicates its structure and identifies the chemical. The advantages of molecular epidemiology include information about the many toxicants to which a person is exposed over a period of weeks or months and the relative exposure levels. The disadvantage is the absence of information about the mechanism of toxicity. Untargeted adductomics examines albumin and hemoglobin adducts, which serve as biomarkers of exposure but do not identify the proteins and genes responsible for the toxicity. Targeted adductomics is used when the origin of the toxicity is known. This can be either an adducted protein, such as the butyrylcholinesterase protein modified by nerve agents, or a toxicant, such as acetaminophen. Untargeted adductomics methods have identified potential protein adduct biomarkers of breast cancer, colorectal cancer, childhood leukemia, and lung cancer. Adductomics is a new research area that offers structural insights into chemical exposures and a platform for the discovery of disease biomarkers. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.

Cirrhosis Inpatients Receive More Opioids and Fewer Nonopioid Analgesics Than Patients Without Cirrhosis

GOALS/BACKGROUND

Pain is common among cirrhosis patients, particularly those hospitalized with acute illness. Managing pain in this population is challenging due to concern for adverse events and lack of guidelines for analgesic use. We sought to characterize analgesic use among inpatients with cirrhosis compared with matched noncirrhosis controls, as well as hospital-level variation in prescribing patterns.

METHODS

We utilized the Vizient Clinical Database, which includes clinical and billing data from hospitalizations at >500 US academic medical centers. We identified cirrhosis patients hospitalized in 2017-2018, and a matched cohort of noncirrhosis patients. Types of analgesic given-acetaminophen (APAP), nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and adjuvants (eg, gabapentinoids, antidepressants) were defined from inpatient prescription records. Conditional logistic regression was used to associate cirrhosis diagnosis with analgesic use.

RESULTS

Of 116,363 cirrhosis inpatients, 83% received at least 1 dose of an analgesic and 58% had regular inpatient analgesic use, rates that were clinically similar to noncirrhosis controls. Cirrhosis inpatients were half as likely to receive APAP (26% vs. 42%, P <0.01) or NSAIDs (3% vs. 7%, P <0.01), but were more likely to receive opioids (59% vs. 54%, P <0.01), particularly decompensated patients (60%). There was notable variation in analgesic prescribing patterns between hospitals, especially among cirrhosis patients.

CONCLUSIONS

Analgesic use was common among inpatients, with similar rates among patients with and without cirrhosis. Cirrhosis patients-particularly decompensated patients-were less likely to receive APAP and NSAIDs and more likely to receive opioid analgesics. Because of lack of evidence-based guidance for management of cirrhosis patients with pain, providers may avoid nonopioid analgesics due to perceived risks and consequently may overutilize opioids in this high-risk population.

Analysis of the contribution of locally derived wastewater to the occurrence of Pharmaceuticals and Personal Care Products in Antarctic coastal waters

Pharmaceuticals and Personal Care Products (PPCPs) are emerging pollutants detected in many locations of the world including Antarctica. The main objective of this review is to discuss the influence of the human population on the concentration, distribution and biological effects of PPCPs across the Antarctic coastal marine ecosystem. We carried out a review of the scientific articles published for PPCPs in Antarctic, supported by the information of the Antarctic stations reported by Council of Managers of National Antarctic Programs (CONMAP), Scientific Committee on Antarctic Research (SCAR) and Secretariat of the Antarctic Treaty (ATS). In addition, spatial data regarding the Antarctic continent was obtained from Quantarctica. Antarctic concentrations of PPCPs were more reflective of the treatment system used by research stations as opposed to the infrastructure built or the annual occupancy by station. The main problem is that most of the research stations lack tertiary treatment, resulting in elevated concentrations of PPCPs in effluents. Furthermore, the geographic distribution of Antarctic field stations in coastal areas allows for the release of PPCPs, directly into the sea, a practice that remains in compliance with the current Protocol. After their release, PPCPs can become incorporated into sea ice, which can then act as a chemical reservoir. In addition, there is no clarity on the effects on the local biota. Finally, we recommend regulating the entry and use of PPCPs in Antarctica given the difficulties of operating, and in some cases the complete absence of appropriate treatment systems. Further studies are needed on the fate, transport and biological effects of PPCPs on the Antarctic biota. It is recommended that research efforts be carried out in areas inhabited by humans to generate mitigation measures relative to potential adverse impacts. Tourism should be also considered in further studies due the temporal release of PPCPs.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

Polysaccharide from Echinacea purpurea plant ameliorates oxidative stress-induced liver injury by promoting Parkin-dependent autophagy

BACKGROUND

Acetaminophen (APAP) overdose represents one of the most common drug-induced liver injuries (DILI) worldwide. Oxidative damage to the hepatocytes and their resultant autophagy are the key components in the APAP-induced DILI. Echinacea purpurea polysaccharide (EPPS), the component extracted from the root of Echinacea purpurea (L.) Moench, shows various biological functions including immunoregulation and antioxidant activity.

PURPOSE

This study aimed to elucidate the protective effect of EPPS against APAP-induced DILI and the underlying mechanisms.

RESULTS

EPPS attenuates APAP overdose induced DILI in mice and ameliorates inflammation and oxidative stress in mice with APAP overdose-induced DILI. Furthermore, EPPS protected the hepatocytes against APAP-induced liver injury by suppressing apoptosis. EPPS ameliorates APAP-induced DILI via an autophagy-dependent mechanism in vivo and increases autophagy with a reduction in oxidative stress and inflammation in vitro. Parkin knockdown prevents the autophagic-dependent manner of EPPS effects in APAP-treated hepatocytes.

CONCLUSIONS

EPPS exhibited a strong hepatoprotective effect against APAP-induced DILI and was correlated with reduction of autophagy-dependent oxidant response, inflammation, and apoptosis. Moreover, the findings indicated that EPPS exerts its hepatoprotective effect against APAP mainly via Parkin-dependent autophagy, and the use of EPPS can serve as a promising novel therapeutic strategy for APAP-induced DILI.

Delivery of therapeutic carbon monoxide by gas-entrapping materials

Carbon monoxide (CO) has long been considered a toxic gas but is now a recognized bioactive gasotransmitter with potent immunomodulatory effects. Although inhaled CO is currently under investigation for use in patients with lung disease, this mode of administration can present clinical challenges. The capacity to deliver CO directly and safely to the gastrointestinal (GI) tract could transform the management of diseases affecting the GI mucosa such as inflammatory bowel disease or radiation injury. To address this unmet need, inspired by molecular gastronomy techniques, we have developed a family of gas-entrapping materials (GEMs) for delivery of CO to the GI tract. We show highly tunable and potent delivery of CO, achieving clinically relevant CO concentrations in vivo in rodent and swine models. To support the potential range of applications of foam GEMs, we evaluated the system in three distinct disease models. We show that a GEM containing CO dose-dependently reduced acetaminophen-induced hepatocellular injury, dampened colitis-associated inflammation and oxidative tissue injury, and mitigated radiation-induced gut epithelial damage in rodents. Collectively, foam GEMs have potential paradigm-shifting implications for the safe therapeutic use of CO across a range of indications.

Naringin alleviates acetaminophen-induced acute liver injury by activating Nrf2 via CHAC2 upregulation

Severe acetaminophen (APAP)-induced hepatic damage is the second most common cause for hepatic transplantation. Clinically, hepatic damage caused by APAP is treated using N-acetyl-L-cysteine, which can induce numerous side effects. Naringin, a bioflavonoid abundant in grapefruit and other citrus fruits, displays marked antiinflammatory and antioxidant activities. Herein, we aimed to investigate the potential mechanism underlying naringin-mediated protection against APAP-induced acute hepatotoxicity. We observed that naringin afforded protection against APAP-induced acute liver failure in mice. Importantly, pretreatment with naringin before APAP administration further increased antioxidant enzyme expression, inhibited the production of proinflammatory cytokines, and activated apoptotic pathways. Furthermore, we observed that the protective effect was associated with the upregulation of cation transport regulator-like protein 2 (CHAC2) and nuclear factor erythroid derived-2-related factor 2 (Nrf2). Notably, CHAC2 knockdown inhibited Nrf2 activation and naringin-mediated antioxidant, antiinflammatory, and antiapoptotic effects in APAP-induced liver injury. Likewise, si-Nrf2 blocked the protective effect of naringin against APAP-induced liver injury. Collectively, our results indicate that naringin may be a potent CHAC2 activator, alleviating APAP-induced hepatitis via CHAC2-mediated activation of the Nrf2 pathway. These data provide new insights into mechanisms through which CHAC2 regulates APAP-induced liver injury by targeting Nrf2, which should be considered a novel therapeutic target.

Acetaminophen treatment evokes anticontractile effects in rat aorta by blocking L-type calcium channels

BACKGROUND

Acetaminophen (APAP) is the most widely used analgesic and antipyretic in the world. However, in high or continuous doses, it can cause serious side effects including blood pressure variability and cardiovascular injuries, which are barely explored. This study aimed to evaluate the acute effect of APAP treatment on vascular tone focused on the blocking of Ca²⁺ channels.

METHODS

Rats were treated with APAP orally by gavage (500 mg/kg/single dose). After 12 h, the aorta was isolated for vascular reactivity studies in an isolated organ bath. Vascular contraction and relaxation were measured after different stimuli. Moreover, molecular docking studies were performed to evaluate the action of NAPQI (APAP metabolite) on L-type calcium channels.

RESULTS

Phenylephrine-induced maximal vascular contraction was reduced in the APAP group (138.4 ± 9.2%) compared to the control group (172.2 ± 11.1%). APAP treatment significantly reduced contraction induced by Ca²⁺ influx stimulated with phenylephrine or KCl and reduced contraction mediated by Ca²⁺ released from the sarcoplasmic reticulum induced by caffeine. There was no difference in vascular relaxation induced by acetylcholine or sodium nitroprusside. Computational molecular docking demonstrated that NAPQI is capable of blocking L-type Ca²⁺ channels (Ca_v1.2), which would limit the influx of Ca²⁺.

CONCLUSION

These results suggest that APAP treatment causes an anticontractile effect in rat aorta, possibly by blocking the influx of Ca²⁺ through L-type channels (Ca_v1.2).

Male Infertility and Oxidative Stress: A Focus on the Underlying Mechanisms

Reactive oxygen species (ROS) play a critical role in defining the functional competence of human spermatozoa. When generated in moderate amounts, ROS promote sperm capacitation by facilitating cholesterol efflux from the plasma membrane, enhancing cAMP generation, inducing cytoplasmic alkalinization, increasing intracellular calcium levels, and stimulating the protein phosphorylation events that drive the attainment of a capacitated state. However, when ROS generation is excessive and/or the antioxidant defences of the reproductive system are compromised, a state of oxidative stress may be induced that disrupts the fertilizing capacity of the spermatozoa and the structural integrity of their DNA. This article focusses on the sources of ROS within this system and examines the circumstances under which the adequacy of antioxidant protection might become a limiting factor. Seminal leukocyte contamination can contribute to oxidative stress in the ejaculate while, in the germ line, the dysregulation of electron transport in the sperm mitochondria, elevated NADPH oxidase activity, or the excessive stimulation of amino acid oxidase action are all potential contributors to oxidative stress. A knowledge of the mechanisms responsible for creating such stress within the human ejaculate is essential in order to develop better antioxidant strategies that avoid the unintentional creation of its reductive counterpart.

Exogenous phosphatidic acid reduces acetaminophen-induced liver injury in mice by activating hepatic interleukin-6 signaling through inter-organ crosstalk

We previously demonstrated that endogenous phosphatidic acid (PA) promotes liver regeneration after acetaminophen (APAP) hepatotoxicity. Here, we hypothesized that exogenous PA is also beneficial. To test that, we treated mice with a toxic APAP dose at 0 h, followed by PA or vehicle (Veh) post-treatment. We then collected blood and liver at 6, 24, and 52 h. Post-treatment with PA 2 h after APAP protected against liver injury at 6 h, and the combination of PA and N-acetyl-l-cysteine (NAC) reduced injury more than NAC alone. Interestingly, PA did not affect canonical mechanisms of APAP toxicity. Instead, transcriptomics revealed that PA activated interleukin-6 (IL-6) signaling in the liver. Consistent with that, serum IL-6 and hepatic signal transducer and activator of transcription 3 (Stat3) phosphorylation increased in PA-treated mice. Furthermore, PA failed to protect against APAP in IL-6-deficient animals. Interestingly, IL-6 expression increased 18-fold in adipose tissue after PA, indicating that adipose is a source of PA-induced circulating IL-6. Surprisingly, however, exogenous PA did not alter regeneration, despite the importance of endogenous PA in liver repair, possibly due to its short half-life. These data demonstrate that exogenous PA is also beneficial in APAP toxicity and reinforce the protective effects of IL-6 in this model.

Paracetamol (Acetaminophen) and the Developing Brain

Paracetamol is commonly used to treat fever and pain in pregnant women, but there are growing concerns that this may cause attention deficit hyperactivity disorder and autism spectrum disorder in the offspring. A growing number of epidemiological studies suggests that relative risks for these disorders increase by an average of about 25% following intrauterine paracetamol exposure. The data analyzed point to a dose-effect relationship but cannot fully account for unmeasured confounders, notably indication and genetic transmission. Only few experimental investigations have addressed this issue. Altered behavior has been demonstrated in offspring of paracetamol-gavaged pregnant rats, and paracetamol given at or prior to day 10 of life to newborn mice resulted in altered locomotor activity in response to a novel home environment in adulthood and blunted the analgesic effect of paracetamol given to adult animals. The molecular mechanisms that might mediate these effects are unknown. Paracetamol has diverse pharmacologic actions. It reduces prostaglandin formation via competitive inhibition of the peroxidase moiety of prostaglandin H2 synthase, while its metabolite N-arachidonoyl-phenolamine activates transient vanilloid-subtype 1 receptors and interferes with cannabinoid receptor signaling. The metabolite N-acetyl-p-benzo-quinone-imine, which is pivotal for liver damage after overdosing, exerts oxidative stress and depletes glutathione in the brain already at dosages below the hepatic toxicity threshold. Given the widespread use of paracetamol during pregnancy and the lack of safe alternatives, its impact on the developing brain deserves further investigation.

Short-Term Safety of Repeated Acetaminophen Use in Patients With Compensated Cirrhosis

Current guidelines recommend restricting acetaminophen (APAP) use in patients with cirrhosis, but evidence to support that recommendation is lacking. Prior studies focused on pharmacokinetics (PK) of APAP in cirrhosis but did not rigorously examine clinical outcomes, sensitive biomarkers of liver damage, or serum APAP‐protein adducts, which are a specific marker of toxic bioactivation. Hence, the goal of this pilot study was to test the effects of regularly scheduled APAP dosing in a well‐defined compensated cirrhosis group compared to control subjects without cirrhosis, using the abovementioned outcomes. After a 2‐week washout, 12 subjects with and 12 subjects without cirrhosis received 650 mg APAP twice per day (1.3 g/day) for 4 days, followed by 650 mg on the morning of day 5. Patients were assessed in‐person at study initiation (day 1) and on days 3 and 5. APAP‐protein adducts and both conventional (alanine aminotransferase) and sensitive (glutamate dehydrogenase [GLDH], full‐length keratin 18 [K18], and total high‐mobility group box 1 protein) biomarkers of liver injury were measured in serum on the mornings of days 1, 3, and 5, with detailed PK analysis of APAP, metabolites, and APAP‐protein adducts throughout day 5. No subject experienced adverse clinical outcomes. GLDH and K18 were significantly different at baseline but did not change in either group during APAP administration. In contrast, clearance of APAP‐protein adducts was dramatically delayed in the cirrhosis group. Minor differences for other APAP metabolites were also detected. Conclusion: Short‐term administration of low‐dose APAP (650 mg twice per day, <1 week) is likely safe in patients with compensated cirrhosis. These data provide a foundation for future studies to test higher doses, longer treatment, and subjects who are decompensated, especially in light of the remarkably delayed adduct clearance in subjects with cirrhosis.

Paracetamol: A Review of Guideline Recommendations

Musculoskeletal pain conditions are age-related, leading contributors to chronic pain and pain-related disability, which are expected to rise with the rapid global population aging. Current medical treatments provide only partial relief. Furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are effective in young and otherwise healthy individuals but are often contraindicated in elderly and frail patients. As a result of its favorable safety and tolerability record, paracetamol has long been the most common drug for treating pain. Strikingly, recent reports questioned its therapeutic value and safety. This review aims to present guideline recommendations. Paracetamol has been assessed in different conditions and demonstrated therapeutic efficacy on both acute and chronic pain. It is active as a single agent and is additive or synergistic with NSAIDs and opioids, improving their efficacy and safety. However, a lack of significant efficacy and hepatic toxicity have also been reported. Fast dissolving formulations of paracetamol provide superior and more extended pain relief that is similar to intravenous paracetamol. A dose reduction is recommended in patients with liver disease or malnourished. Genotyping may improve efficacy and safety. Within the current trend toward the minimization of opioid analgesia, it is consistently included in multimodal, non-opioid, or opioid-sparing therapies. Paracetamol is being recommended by guidelines as a first or second-line drug for acute pain and chronic pain, especially for patients with limited therapeutic options and for the elderly.

Biomarkers of mitotoxicity after acute liver injury: Further insights into the interpretation of glutamate dehydrogenase

BACKGROUND

Acetaminophen (APAP) is a popular analgesic, but overdose causes acute liver injury and sometimes death. Decades of research have revealed that mitochondrial damage is central in the mechanisms of toxicity in rodents, but we know much less about the role of mitochondria in humans. Due to the challenge of procuring liver tissue from APAP overdose patients, non-invasive mechanistic biomarkers are necessary to translate the mechanisms of APAP hepatotoxicity from rodents to patients. It was recently proposed that the mitochondrial matrix enzyme glutamate dehydrogenase (GLDH) can be measured in circulation as a biomarker of mitochondrial damage. Early observations revealed that damaged mitochondria release their contents into the cytosol. It follows that those mitochondrial molecules become freely detectable in blood after cell death. On the other hand, intact mitochondria would not release their matrix contents and can be removed from serum or plasma by high-speed centrifugation. However, a recent study cast doubt on the interpretation of GLDH as a mitotoxicity biomarker by demonstrating that neither high-speed centrifugation nor repeated freezing and thawing to lyse mitochondria alter GLDH activity in serum from mice with drug-induced liver injury.

AIM

Here, we briefly review the evidence for mitochondrial damage in APAP hepatotoxicity and demonstrate that removal of intact mitochondria by centrifugation does not alter measured GLDH activity simply because GLDH within the mitochondrial matrix is not accessible for measurement. In addition, we show that freezing and thawing is insufficient for complete lysis of mitochondria.

RELEVANCE FOR PATIENTS

Our literature review and data support the interpretation that circulating GLDH is a biomarker of mitochondrial damage. Such mechanistic biomarkers are important to translate preclinical research to patients.