Recommendations for the use of the acetaminophen hepatotoxicity model for mechanistic studies and how to avoid common pitfalls

4-Hydroxyestrogen metabolites strongly prevent chemically-induced ferroptotic hepatocyte injury in vitro and in vivo

Ferroptosis is a regulated cell death characterized by excessive accumulation of toxic lipid reactive oxygen species (ROS). Ferroptosis is an underlying cause in some human diseases, including the drug-induced liver injury. The present study aims to determine whether 4-hydroxyestrone (4-OH-E1) and 4-hydroxyestradiol (4-OH-E2), two endogenous catechol estrogens, can prevent chemically-induced ferroptotic hepatocyte injury in vitro and in vivo. The induction of ferroptotic cell death by erastin and RSL3 in rat H-4-II-E and human HuH-7 hepatoma cells is used as in vitro models. 4-OH-E1 and 4-OH-E2 each exhibit a strong protection against erastin/RSL3-induced ferroptosis in H-4-II-E hepatoma cells, and they also strongly abrogate erastin/RSL3-induced accumulation of cellular NO, ROS and lipid-ROS. A similar protective effect is observed with 4-OH-E1 and 4-OH-E2 in RSL3-induced ferroptosis in HuH-7 cells. Mechanistically, these two catechol estrogens protect hepatoma cells against chemically-induced ferroptosis mainly through binding to cellular PDI protein with a high affinity, which leads to inhibition of PDI-catalyzed NOS dimerization (activation), thereby preventing the accumulation of cellular NO, ROS and lipid-ROS. In addition, the direct antioxidant activity of these two estrogens may also partially contribute to their cytoprotective effect. In vivo animal studies show that 4-OH-E1 and 4-OH-E2 also have a strong protective effect against acetaminophen-induced liver injury in a mouse model. Together, the results of this study demonstrate that 4-OH-E1 and 4-OH-E2 are endogenous factors with a strong protective activity against chemically-induced hepatocyte injury both in vitro and in vivo.

Underlying mechanisms and treatment of acetaminophen‑induced liver injury (Review)

Acetaminophen (APAP) is safe at therapeutic doses; however, when ingested in excess, it accumulates in the liver and leads to severe hepatotoxicity, which in turn may trigger acute liver failure (ALF). This is known as APAP poisoning and is a major type of drug‑related liver injury. In the United States, APAP poisoning accounts for ≥50% of the total number of ALF cases, making it one of the most common triggers of ALF. According to the American Association for the Study of Liver Diseases, the incidence of APAP‑associated hepatotoxicity has increased over the past few decades; however, the mechanism underlying liver injury due to APAP poisoning has remained inconclusive. The present study aims to comprehensively review and summarize the latest research progress on the mechanism of APAP‑induced liver injury, and to provide scientific and effective guidance for the clinical treatment of APAP poisoning through in‑depth analysis of the metabolic pathways, toxicity‑producing mechanisms and possible protective mechanisms of APAP in the liver.

Enhanced antibiotic release and biocompatibility with simultaneous addition of N-acetylcysteine and vancomycin to bone cement: a potential replacement for high-dose antibiotic-loaded bone cement

BACKGROUND

Antibiotic-loaded bone cement (ALBC) is crucial for treating orthopedic infections, but its use is limited by suboptimal antibiotic release patterns and potential toxicity. This study explores the dual addition of N-acetylcysteine (NAC) and vancomycin to polymethylmethacrylate (PMMA) as a strategy to enhance the antibacterial efficacy and reduce toxicity.

METHODS

PMMA cement cylinders were loaded with varying combinations of NAC and vancomycin and tested for antibiotic release, cytotoxicity, and antibacterial activity over a 35-day period. Porosity of the cements was also evaluated as a measure of potential antibiotic release enhancement.

RESULTS

The addition of NAC improved vancomycin release, particularly after the initial burst release phase, and reduced cytotoxicity compared to high-dose vancomycin alone. The optimal combination was found to be 2 gm vancomycin with either 2 gm or 4 gm of NAC, which maintained effective antibacterial activity over 35 days without the toxicity seen with higher doses of vancomycin alone. Moreover, NAC alone did not demonstrate antibacterial properties, indicating its role primarily as a bioenhancer in this context.

CONCLUSION

Simultaneous inclusion of NAC and vancomycin in PMMA bone cement provides a more favorable release profile and biocompatibility than high-dose vancomycin alone, suggesting a potential strategy for enhancing the therapeutic efficacy of ALBC in treating prosthetic joint infections. This approach allows for lower doses of antibiotics, reducing potential cytotoxicity, systemic toxicity and enhancing the duration of antibacterial activity.

LEVEL OF EVIDENCE

Laboratory study.

Enzyme-Responsive Nanoparachute for Targeted miRNA Delivery: A Protective Strategy Against Acute Liver and Kidney Injury

MicroRNA (miRNA)-based therapy holds significant potential; however, its structural limitations pose a challenge to the full exploitation of its biomedical functionality. Framework nucleic acids are promising owing to their transportability, biocompatibility, and functional editability. MiRNA-125 is embedded into a nucleic acid framework to create an enzyme-responsive nanoparachute (NP), enhancing the miRNA loading capacity while preserving the attributes of small-scale framework nucleic acids and circumventing the uncertainty related to RNA exposure in conventional loading methods. An enzyme-sensitive sequence is designed in NP as a bioswitchable apparatus for cargo miRNAs release. NP is compared with conventional delivery modes and delivery vehicles, confirming its excellent transportability and sustained release properties. Moreover, NP confers good enzyme and serum resistance to the cargo miRNAs. Simultaneously, it can easily deliver miRNA-125 to liver and kidney lesions owing to its passive targeting properties. This allows for Keap1/Nrf2 pathway regulation and p53 protein targeting in the affected tissues. Additionally, NP negatively regulates the expression of Bax and Caspase-3. These combined actions help to inhibit oxidation, prevent cell cycle arrest, and reduce the apoptosis of liver and kidney cells. Consequently, this strategy offers a potential treatment for acute liver and kidney injury.

Liver-specific Bcl3 Knockout Alleviates Acetaminophen-induced Liver Injury by Activating Nrf2 Pathway in Male Mice

BACKGROUND & AIMS

Acetaminophen (APAP) overdose is the leading cause of acute liver failure, with oxidative stress being a critical factor in this process. Glutathione (GSH) plays a vital defensive role. Activation of nuclear factor erythroid 2 like 2 (Nrf2) pathway mitigates APAP-induced liver damage by promoting GSH biosynthesis and enhancing drug detoxification. Although the role of B cell leukemia/lymphoma 3 (Bcl3) in regulating inflammatory responses, cellular oncogenesis, and immune balance is well-documented, its function in APAP-induced liver injury remains unclear.

METHODS

We employed liver-specific Bcl3 knockout (Bcl3hep-/-) mice and adeno-associated virus (AAV)-8-mediated Bcl3 overexpression (AAV-Bcl3) mice to model APAP-induced liver injury. Liver damage was assessed through hematoxylin and eosin staining and serum alanine aminotransferase and aspartate aminotransferase measurements. The interaction between Bcl3 and Nrf2 was examined using immunofluorescence and co-immunoprecipitation assays.

RESULTS

Our study reveals a significant upregulation of Bcl3 expression in the livers of male mice following APAP administration, suggesting Bcl3's potential involvement in this pathological process. In Bcl3hep-/- mice, a reduced severity of liver damage was observed at both 6 and 24 hours post-APAP treatment compared with controls. Notably, Bcl3-deficient mice exhibited accelerated GSH replenishment due to the rapid induction of Gclc and Gclm genes following 6 hours of APAP exposure. Through immunofluorescence and co-immunoprecipitation analyses, we identified an interaction between Bcl3 and Nrf2. The loss of Bcl3 enhanced Nrf2 translocation upon APAP challenge, leading to the upregulation of antioxidant gene expression. These findings suggest that Bcl3 knockout alleviates oxidative stress resulting from APAP overdose.

CONCLUSION

We uncovered a previously uncharacterized role of Bcl3 in APAP-induced liver injury, emphasizing the role of the Bcl3-Nrf2 axis in oxidative stress-related liver damage.

Quinic acid alleviates liver toxicity induced by acetaminophen in mice via anti-oxidative and anti-inflammatory effects

Acetaminophen (N-acetyl-para-aminophenol: APAP)-induced hepatotoxicity is a common toxicity that is associated with oxidative stress and inflammation. Quinic acid (QA) is a naturally occurring metabolite that exhibits antioxidant and anti-inflammatory properties. In this research, the effect of QA on hepatotoxicity caused by APAP was investigated. The mice were divided into six groups: control, APAP (300 mg/kg, i.p.), QA (100 mg/kg, i.p.), N-acetylcysteine (NAC) (100 mg/kg, i.p.), and treatment groups, which pretreated with QA at two doses of 50 and 100 mg/kg. NAC and QA were injected for 7 days, and APAP was injected on the seventh day. On day 8, mice were euthanized, and serum factors, markers of oxidative stress, tumor necrosis factor-α (TNF-α), and expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and cytochrome P450 2E1 (CYP2E1) proteins were measured. The results showed that the APAP-treated group significantly increased the activity of serum enzymes (alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase). APAP decreased hepatic total thiol content, as well as catalase, superoxide dismutase, and glutathione peroxidase activities, and increased thiobarbituric acid reactive substances and TNF-α levels. In addition, Nrf2 and CYP2E1 protein expression was upregulated in APAP-induced injury. Moreover, histopathological findings confirmed APAP hepatotoxicity. However, QA protected mice against the detrimental effects resulting from an imbalance in the oxidant/antioxidant system. QA ameliorated APAP-induced inflammation and histopathological changes and was able to upregulate the protein expression of Nrf2, while also reversing the increase in protein expression of CYP2E1 in APAP-intoxicated mice. These findings demonstrate the potential of QA in preventing APAP-induced hepatotoxicity, which is comparable to the effects of NAC.

Thonningianin A ameliorates acetaminophen-induced liver injury by activating GPX4 and modulating endoplasmic reticulum stress

Introduction

Acetaminophen (APAP) is widely used as an analgesic and antipyretic. However overdose APAP can lead to acute liver injury (ALI), representing a significant challenge for public health due to limited treatment options. Current research highlights the need for safer and more effective therapies for APAP-induced liver injury, especially those that target oxidative and endoplasmic reticulum (ER) stress pathways. This study investigates the protective effects of Thonningianin A (TA), a flavonoid compound derived from Penthorum chinense Pursh, in mitigating APAP-induced hepatotoxicity.

Methods

The experimental design involved administering TA at doses of 20 mg/kg and 40 mg/kg to C57BL/6 mice prior to inducing hepatotoxicity with APAP.

Results and discussion

TA treatment significantly lowered plasma ALT and AST levels, inhibited the production of inflammatory cytokines, and reduced oxidative stress markers in liver tissues. Furthermore, TA modulated apoptosis-related proteins by increasing BCL-2 expression while decreasing CHOP and BAX levels. It alleviated endoplasmic reticulum (ER) stress by downregulating GRP78, p-PERK, and ATF4. Notably, liver-specific GPX4 knockdown, achieved through AAV-8-mediated shRNA delivery, abolished the hepatoprotective effects of TA, underscoring GPX4's essential role in mediating TA-induced hepatoprotection. These findings suggest TA as a promising therapeutic agent in managing APAP-induced liver injury, with its unique action on both oxidative and ER stress pathways contributing to its hepatoprotective efficacy.

Scopoletin alleviates acetaminophen-induced hepatotoxicity through modulation of NLRP3 inflammasome activation and Nrf2/HMGB1/TLR4/NF-κB signaling pathway

Scopoleitin (SP), a bioactive compound from many edible plants and fruits, exerts a wide range of biological activities, however the role and mechanism of SP in acetaminophen (APAP)-induced hepatotoxicity remains unclear. In this study, we verified the protective effect of SP on APAP-induced liver injury (AILI) hepatotoxicity and explore the underlying molecular mechanisms. Here, we showed that SP alleviated AILI by reducing serum alanine transaminase (ALT) and aspartate aminotransferase (AST) levels, hepatic histopathological damage, inflammation, and liver cell apoptosis. In addition, SP attenuated the accumulation of malondialdehyde (MDA) and exhaustion of glutathione (GSH) levels and increased the superoxide dismutase (SOD) levels induced by APAP. Consistently, SP significantly reduced the gene transcription of cytochrome P450 (CYP)2E1, CYP1A2, and CYP3A11 in the livers of mice induced by APAP. Moreover, SP pretreatment effectively promoted the expression of Nrf2, Keap1, and its signal downstream HO-1, NQO1, GCLc, and GCLm, suggesting the activation of the Nrf2 signaling pathway. SP inhibited APAP-induced hepatocyte apoptosis by regulating the protein levels of apoptosis-related proteins (cytochrome C, Bax, Caspase-3, Bcl2, and PARP). SP suppressed APAP-induced expression of NLRP3 and reduced the levels of proinflammatory factors, including tumor necrosis factor-alpha (TNF-α), F4/80, Caspase-1, and interleukin (IL)-1 beta (IL-1β). Moreover, SP downregulated APAP-induced high-mobility group box 1 (HMGB1) and toll-like receptor 4 (TLR4) expression, inhibited nuclear factor kappa-B (NF-κB) and MAPK activation. Taken together, our study reveals the protective roles of SP against AILI through the downregulation of NLRP3 expression, and the inhibition of the Nrf2/HMGB1/TLR4/NF-κB signaling pathways.

SW033291 promotes liver regeneration after acetaminophen-induced liver injury in mice

Acetaminophen (APAP) is a commonly utilized antipyretic and analgesic drug. Overdose of APAP is a primary contributor to drug-induced liver injury and acute liver failure (ALF). SW033291 has been shown to play a role in tissue regeneration in various diseases; however, its potential to facilitate liver regeneration following APAP-induced hepatic injury remains unexamined. Thus, this study focused on exploring the therapeutic impacts and mechanisms of SW033291 on liver damage by establishing models of APAP-induced acute liver injury in mice. The results showed that treatment with SW033291 reduces serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, decreases the area of hepatic necrosis, increases glutathione (GSH) levels, and decreases tissue malondialdehyde (MDA) content, as well as the expression levels of tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in mice with liver injury. It could also promote hepatocyte proliferation and inhibit apoptosis by increasing tissue prostaglandin E2 (PGE2) levels. In conclusion, SW033291 demonstrates the capacity to ameliorate APAP-induced hepatic injury in mice by fostering liver regeneration, attenuating oxidative stress, and modulating inflammatory responses, thereby presenting itself as a promising candidate for the development of therapeutic interventions targeting acute liver failure.

Oral administration of astilbin mitigates acetaminophen-induced acute liver injury in mice by modulating the gut microbiota

Acetaminophen (APAP) overdose-induced acute liver injury (ALI) is characterized by extensive oxidative stress, and the clinical interventions for this adverse effect remain limited. Astilbin is an active compound found in the rhizome of Smilax glabra Roxb. with anti-inflammatory and antioxidant activities. Due to its low oral bioavailability, astilbin can accumulate in the intestine, which provides a basis for the interaction between astilbin and gut microbiota (GM). In the present study we investigated the protective effects of astilbin against APAP-induced ALI by focusing on the interaction between astilbin and GM. Mice were treated with astilbin (50 mg·kg-1·d-1, i.g.) for 7 days. After the last administration of astilbin for 2 h, the mice received APAP (300 mg/kg, i.g.) to induce ALI. We showed that oral administration of astilbin significantly alleviated APAP-induced ALI by altering the composition of GM and enriching beneficial metabolites including hydroxytyrosol (HT). GM depletion using an "antibiotics cocktail" or paraoral administration of astilbin abolished the hepatoprotective effects of astilbin. On the other hand, administration of HT (10 mg/kg, i.g.) caused similar protective effects in APAP-induced ALI mice. Transcriptomic analysis of the liver tissue revealed that HT inhibited reactive oxygen species and inflammation-related signaling in APAP-induced ALI; HT promoted activation of the Nrf2 signaling pathway to combat oxidative stress following APAP challenge in a sirtuin-6-dependent manner. These results highlight that oral astilbin ameliorates APAP-induced ALI by manipulating the GM and metabolites towards a more favorable profile, and provide an alternative therapeutic strategy for alleviating APAP-induced ALI.

A quantitative weight-of-evidence review of preclinical studies examining the potential developmental and reproductive toxicity of acetaminophen

We previously developed a quantitative weight-of-evidence (QWoE) framework using prespecified scoring criteria for preclinical acetaminophen data to characterize potential developmental neurotoxicity outcomes with considerations for biological relevance of the response to adverse outcomes and the strength of methods and study design. The current analysis uses this framework to characterize potential developmental and reproductive toxicity (DART) outcomes following exposure to acetaminophen. Two-hundred forty-two QWoE entries were documented from in vivo rodent studies identified in 110 publications across five categories: DART endpoints in the context of (1) periadolescent/adulthood (nonpregnancy) exposures; (2) pregnant female exposures; and, for in utero or other developmental exposures, (3) anatomical abnormalities, (4) reproductive development, and (5) other physical development. A mean outcome score and methods score were calculated for 242 QWoE entries. Data analyzed in our framework were of moderate quality showing no consistent evidence of DART in male and female rodents following exposure to acetaminophen at therapeutic and/or non-systemically toxic doses. Similar results were found for the individual context- and outcome-related endpoint analyses and as segregated by sex. Overall, this QWoE analysis on the in vivo rodent data demonstrated no consistent evidence of adverse effects following exposure to therapeutic and/or non-systemically toxic acetaminophen on development or on the structure and function of the reproductive system.

Protective effect of 2-hydroxyestrone and 2-hydroxyestradiol against chemically induced hepatotoxicity in vitro and in vivo

Ferroptosis is a form of regulated cell death closely associated with glutathione depletion and accumulation of reactive lipid peroxides. In this study, we seek to determine whether 2-hydroxyestrone (2-OH-E1) and 2-hydroxyestradiol (2-OH-E2), 2 major metabolites of endogenous estrone (E1) and 17β-estradiol (E2) formed by cytochrome P450 in the liver, can protect against erastin- and RSL3-induced ferroptosis in hepatoma cells (H-4-II-E and HuH-7) in vitro and acetaminophen-induced mouse liver injury in vivo. We find that 2-OH-E1 and 2-OH-E2 can protect, in a dose-dependent manner, H-4-II-E hepatoma cells against erastin/RSL3-induced ferroptosis. A similar protective effect of 2-OH-E1 and 2-OH-E2 against erastin- and RSL3-induced ferroptosis is also observed in HuH-7 hepatoma cells. These 2 estrogen metabolites can strongly abrogate erastin- and RSL3-induced accumulation of cellular NO, reactive oxygen species (ROS), and lipid-ROS. Mechanistically, 2-OH-E1 and 2-OH-E2 protect cells against chemically induced ferroptosis by binding to cellular protein disulfide isomerase and then inhibiting its catalytic activity and reducing protein disulfide isomerase-mediated activation (dimerization) of inducible nitric oxide synthase, abrogating cellular NO, ROS, and lipid-ROS accumulation. Animal studies show that 2-OH-E1 and 2-OH-E2 also exhibit strong protection against acetaminophen-induced liver injury in mice. Interestingly, although E1 and E2 have a very weak protective effect in cultured hepatoma cells, they exhibit a similarly strong protective effect as 2-OH-E1 and 2-OH-E2 in vivo, suggesting that the metabolic conversion of E1 and E2 to 2-OH-E1 and 2-OH-E2 contributes importantly to their hepatoprotective effect. This study reveals that 2-OH-E1 and 2-OH-E2 are important endogenous factors for protection against chemically induced liver injury in vivo. SIGNIFICANCE STATEMENT: Ferroptosis is an iron-dependent and lipid reactive oxygen species-dependent form of regulated cell death. Recent evidence has shown that protein disulfide isomerase (PDI) is an important mediator of chemically induced ferroptosis and also a new target for ferroptosis protection. This study shows that 2-hydroxyestrone and 2-hydroxyestradiol are 2 inhibitors of PDI that can strongly protect against chemically induced ferroptotic hepatocyte death in vitro and in vivo. This work supports a PDI-mediated, estrogen receptor-independent mechanism of hepatocyte protection by 2-hydroxyestrone and 2-hydroxyestradiol.

A quantitative weight-of-evidence review of preclinical studies examining the potential developmental neurotoxicity of acetaminophen

Acetaminophen [paracetamol; N-acetyl-para-aminophenol (APAP)] is an antipyretic/analgesic commonly used in the treatment of fever and mild to moderate pain, headache, myalgia, and dysmenorrhea. Recent literature has questioned the safety of acetaminophen use during pregnancy, with an emphasis on whether exposure to the developing nervous system results in behavioral changes consistent with autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and/or other cognitive deficits in the offspring. No previous review has used a fully detailed, quantitative weight-of-evidence (QWoE) approach to critically examine the preclinical acetaminophen data with regards to potential developmental neurotoxicity (DNT). Following regulatory guidance, a QWoE framework using prespecified scoring criteria was developed consistent with previous approaches to characterize potential adverse DNT outcomes with considerations for biological relevance of the response to adverse outcomes (outcome score) and the strength of methods and study design (methods score). Considerations for the methods score included (1) experimental design, (2) details/reliability of measurement(s), (3) data transparency, and (4) translational/methodological relevance. Considerations for the outcome score included response-related (1) statistical significance, (2) dose-response, (3) relevance/reliability/magnitude, (4) plausibility, and (5) translational relevance, including consideration of systemic toxicity/hepatotoxicity and therapeutic and/or non-systemically toxic doses and durations of use. Application of this QWoE framework to the 34 in vivo studies identified that assess the potential DNT of acetaminophen resulted in 188 QWoE entries documented across 11 DNT endpoints: social behavior, stereotypic behavior, behavioral rigidity, attention/impulsivity, hyperactivity, anxiety-like behavior, sensorimotor function, spatial learning/memory, nonspatial learning/memory, neuroanatomy, and neurotransmission. For each endpoint, the mean outcome score and methods score were calculated for total entries and for entries segregated by sex to assist in determining data quality and potential adversity. Informed by all 188 entries, the QWoE analysis demonstrated data of moderate quality showing no consistent evidence of DNT in male and female rodents following exposure to acetaminophen at therapeutic and/or nonsystemically toxic doses. Although some of the DNT endpoints (behavioral rigidity, attention/impulsivity, spatial learning/memory, neuroanatomy, and neurotransmission) generally displayed a more limited dataset and/or relatively lower data quality, similar conclusions were drawn based on results indicating a lack of biological relevance and reliability of reported adverse effects. Overall, this QWoE analysis on the preclinical in vivo data demonstrates no consistent evidence of adverse effects following developmental exposure to acetaminophen at therapeutic and/or non-systemically toxic doses on the structure and function of the nervous system, including neuroanatomical, neurotransmission, and behavioral endpoints.

Loss of Urat1 exacerbates APAP-induced liver injury in mice

Acetaminophen (APAP) overdose stands as the paramount contributor to drug-elicited liver damage in clinical settings. Despite this, the intricate interplay between uric acid (UA) levels, its metabolism-linked regulatory genes, and their effects on APAP metabolism and hepatic functions remains elusive. Our study sheds light on this nexus, uncovering that uric acid concentrations and urate transporter-1 (URAT1) expression are intricately intertwined in APAP-induced hepatotoxicity. Notably, elevated serum uric acid levels concomitant with a marked downregulation of hepatic URAT1 expression were discernible in APAP-mediated liver injury models. We also found that high UA exacerbated APAP-induced liver injury in vitro and in vivo. To delve deeper, we devised genetic knockout mice models, specifically targeting URAT1, to unravel its pivotal role in this pathological process. Strikingly, Urat1 knockout (Urat1-/-) mice exhibited exacerbated APAP-triggered hepatotoxicity when juxtaposed against their genetically intact wild-type (Urat1+/+) counterparts, accompanied by increased serum and hepatic UA contents. However, the changes in UA levels might not be the only factor exacerbating APAP liver injury in Urat1-/- mice, as Urat1 knockout has also been proved to affect many other metabolites associated with the redox homeostasis. Mechanistically, we found that the ablation of Urat1 not only intensified triglyceride accumulation instigated by APAP via inhibiting PPAR-α pathway but also ignited the NLRP3/NF-κB and JNK/ERK signaling cascades, and disrupted oxidative stress homeostasis via downregulating KEAP1/NRF2 pathway. Collectively, our findings underscore that URAT1 acts as a multifaceted facilitator of APAP-induced liver injury in mice, thereby positioning it as a genetic vulnerability factor in APAP overdose scenarios.

The IDH1-R132H mutation aggravates cisplatin-induced acute kidney injury by promoting ferroptosis through disrupting NDUFA1 and FSP1 interaction

The IDH1-R132H mutation is implicated in the development of various tumors. Whether cisplatin, a common chemotherapeutic agent, induces more significant renal toxicity in individuals with the IDH1-R132H mutation remains unclear. In this study, we observed that the IDH1-R132H mutation exacerbates mitochondrial lipid peroxidation and dysfunction in renal tubules, rendering the kidneys more susceptible to cisplatin-induced ferroptosis. The IDH1-R132H mutation increases methylation of the Ndufa1 promoter, thereby suppressing NDUFA1 transcription and translation. This suppression disrupts NDUFA1's interaction with FSP1, reducing its resistance to cisplatin-induced tubular epithelial cell death. As a consequence, ROS accumulates, lipid peroxidation occurs, and ferroptosis is triggered, thereby promoting acute kidney injury. In summary, this study elucidates a novel mechanism underlying cisplatin-induced nephrotoxicity and provides valuable insights for the development of personalized treatment strategies for tumor patients carrying the IDH1-R132H mutation.

Preclinical liver toxicity models: Advantages, limitations and recommendations

Experimental animal models are crucial for elucidating the pathophysiology of liver injuries and for assessing new hepatoprotective agents. Drugs and chemicals such as acetaminophen, isoniazid, valproic acid, ethanol, carbon tetrachloride (CCl4), dimethylnitrosamine (DMN), and thioacetamide (TAA) are metabolized by the CYP2E1 enzyme, producing hepatotoxic metabolites that lead to both acute and chronic liver injuries. In experimental settings, acetaminophen (centrilobular necrosis), carbamazepine (centrilobular necrosis and inflammation), sodium valproate (necrosis, hydropic degeneration and mild inflammation), methotrexate (sinusoidal congestion and inflammation), and TAA (centrilobular necrosis and inflammation) are commonly used to induce various types of acute liver injuries. Repeated and intermittent low-dose administration of CCl4, TAA, and DMN activates quiescent hepatic stellate cells, transdifferentiating them into myofibroblasts, which results in abnormal extracellular matrix production and fibrosis induction, more rapidly with DMN and CCL4 than TAA (DMN > CCl4 > TAA). Regarding toxicity and mortality, CCl4 is more toxic than DMN and TAA (CCl4 > DMN > TAA). Models used to induce metabolic dysfunction-associated liver disease (MAFLD) vary, but MAFLD's multifactorial nature driven by factors like obesity, fatty liver, dyslipidaemia, type II diabetes, hypertension, and cardiovascular disease makes it challenging to replicate human metabolic dysfunction-associated steatohepatitis accurately. From an experimental point of view, the degree and pattern of liver injury are influenced by various factors, including the type of hepatotoxic agent, exposure duration, route of exposure, dosage, frequency of administration, and the animal model utilized. Therefore, there is a pressing need for standardized protocols and regulatory guidelines to streamline the selection of animal models in preclinical studies.

Novel reduced heteropolyacid nanoparticles for effective treatment of drug-induced liver injury by manipulating reactive oxygen and nitrogen species and inflammatory signals

With the rapid advancements in biomedicine, the use of clinical drugs has surged sharply. However, potential hepatotoxicity limits drug exploitation and widespread usage, posing serious threats to patient health. Hepatotoxic drugs disrupt liver enzyme levels and cause refractory pathological damage, creating a challenge in the application of diverse first-line drugs. The activation and deterioration of reactive oxygen and nitrogen species (RONS) and inflammatory signals are key pathological mechanisms of drug-induced liver injury (DILI). Herein, a novel reduced heteropolyacid nanoparticle (RNP) has been developed, possessing high RONS-scavenging ability, strong anti-inflammatory activity, and excellent biosafety. These features enable it to swiftly restore the redox and immune balance of the liver. Intravenous administration of RNP effectively scavenged RONS storm, reversing liver oxidative stress and restoring normal mitochondrial membrane potential and function. Furthermore, by inhibiting c-Jun-N-terminal kinase phosphorylation, RNP facilitated the restoration of nuclear factor erythroid 2-related factor 2-mediated endogenous antioxidant signaling, ultimately rescuing the liver function and tissue morphology in acetaminophen-induced DILI mice. Crucially, the high biocompatible RNP exhibited superior efficacy in the DILI mouse model compared to the clinical antioxidant N-acetylcysteine. This targeted therapeutic approach, tailored to address the onset and progression of DILI, offers valuable new insights into controlling the condition and restoring liver structure and function.

Mitochondrial dysfunction in drug-induced hepatic steatosis: Recent findings and current concept

Mitochondrial activity is necessary for the maintenance of many liver functions. In particular, mitochondrial fatty acid oxidation (FAO) is required for energy production and lipid homeostasis. This key metabolic pathway is finely tuned by the mitochondrial respiratory chain (MRC) activity and different transcription factors such as peroxisome proliferator-activated receptor α (PPARα). Many drugs have been shown to cause mitochondrial dysfunction, which can lead to acute and chronic liver lesions. While severe inhibition of mitochondrial FAO would eventually cause microvesicular steatosis, hypoglycemia, and liver failure, moderate impairment of this metabolic pathway can induce macrovacuolar steatosis, which can progress in the long term to steatohepatitis and cirrhosis. Drugs can impair mitochondrial FAO through several mechanisms including direct inhibition of FAO enzymes, sequestration of coenzyme A and l-carnitine, impairment of the activity of one or several MRC complexes and reduced PPARα expression. In drug-induced macrovacuolar steatosis, non-mitochondrial mechanisms can also be involved in lipid accumulation including increased de novo lipogenesis and reduced very-low-density lipoprotein secretion. Nonetheless, mitochondrial dysfunction and subsequent oxidative stress appear to be key events in the progression of steatosis to steatohepatitis. Patients suffering from metabolic dysfunction-associated steatotic liver disease (MASLD) and treated with mitochondriotoxic drugs should be closely monitored to reduce the risk of acute liver injury or a faster transition of steatosis to steatohepatitis. Therapies based on the mitochondrial cofactor l-carnitine, the antioxidant N-acetylcysteine, or thyromimetics might be useful to prevent or treat drug-induced mitochondrial dysfunction, steatosis, and steatohepatitis.

The emerging role of alternatively activated macrophages to treat acute liver injury

Acute liver injury (ALI) has a clear requirement for novel therapies. One emerging option is the use of alternatively activated macrophages (AAMs); a distinct subtype of macrophage with a role in liver injury control and repair. In this comprehensive review, we provide an overview of the current limited options for ALI, and the potential advantages offered by AAMs. We describe the evidence supporting their use from in vitro studies, pre-clinical animal studies, and human clinical trials. We suggest why the first evidence for the clinical use of AAMs is likely to be found in acetaminophen toxicity, and discuss the specific evidence for AAM use in this population, as well as potential applications for AAMs in other patient populations. The key domains by which the performance of AAMs for the treatment of ALI will be assessed are identified, and remaining challenges to the successful delivery of AAMs to clinic are explored.

Ehretia laevis mitigates paracetamol- induced hepatotoxicity by attenuating oxidative stress and inflammation in rats

Hepatotoxicity is caused due to intake of drug or any chemical above the therapeutic range or as overdose. Current therapies for the management of hepatotoxicity are associated with several side effects. The present study was envisaged to explore the hepatoprotective potential of Ehretia laevis (E. laevis) in paracetamol (PCM) induced hepatotoxicity. All the plant extracts and fractions were evaluated for antioxidant and antiproliferative potential using various in vitro assays. Hepatotoxicity was induced in rats using a standardized single oral dose of PCM (3 g/kg). The aqueous fraction of E. laevis (AFEL) exhibited significant antioxidant and antiproliferative activity as compared to methanol extract of E. laevis (MEEL) in vitro. Moreover, treatment with AFEL (25, 50 and 100 mg/kg) decreased serum hepatic markers, attenuate the oxidative stress, inflammation and histopathological changes. LC-MS analysis of AFEL showed the presence of rutin, quercetin and kaempferol. Rutin was found to be in higher concentration, therefore it was docked on TNF-α. Its overall binding mode supports its capability to make complex with TNF-α. The finding of the study suggested significant antioxidant, antiproliferative, and hepatoprotective potential of E. laevis in paracetamol induced hepatotoxicity which could be attributed to the presence of various polyphenols.

Shenqi Pill alleviates acetaminophen-induced liver injury: a comprehensive strategy of network pharmacology and spectrum-effect relationship reveals mechanisms and active components

BACKGROUND

Acetaminophen (APAP), commonly used for its antipyretic and analgesic properties, can cause severe liver injury or even acute liver failure when overdosed. However, the options for treating APAP-induced liver toxicity are limited. Shenqi Pill (SQP), a traditional Chinese herbal formula, has shown effectiveness in treating various liver ailments. SQP consists of cinnamon, aconite, rehmannia, cornus, peony bark, Chinese yam, poria, and alisma in a ratio of 1:1:8:4:3:4:3:3. However, the mechanisms and active components of SQP that counteract drug-induced liver injury (DILI) are not well understood.

PURPOSE

This study aimed to explore the protective effects of SQP against APAP-induced liver injury in both laboratory and animal settings. It seeks to identify the active components and potential mechanisms by which SQP targets mitochondria to alleviate liver damage.

METHODS

A mouse model with APAP-induced liver injury was established to assess SQP's therapeutic impact. This study then analyzed the components of SQP using UPLC-Q-TOF-MS in both in vivo and in vitro environments. Network pharmacology and the GEO database helped predict potential pathways and targets. Potential active components were identified through spectrum-effect relationship analysis and validated their efficacy using Seahorse assays and molecular docking.

RESULTS

Treatment with SQP significantly reduced liver dysfunction, tissue damage, lipid metabolic disruptions, and inflammation caused by APAP in mice. In cellular tests, SQP-treated serum notably enhanced mitochondrial function, maintained membrane potential, decreased ROS levels, and prevented mitochondrial permeability transition pore opening. Biochemically, SQP reversed the suppression of p-AMPK, p-ACC, CPT1, and ACADM expression caused by APAP overdose. This study identified 97 in vitro and 24 in vivo components of SQP, with eight showing significant mitochondrial benefits. Molecular docking studies suggest that fuziline and paeoniflorin could activate AMPK.

CONCLUSION

SQP effectively mitigates APAP-induced liver injury by enhancing mitochondrial function via the AMPK-ACC-CPT1-ACADM pathway. Moreover, this study introduces a novel strategy for analyzing the relationship between the chemical and pharmacological properties of drug-containing serum, successfully identifying compounds with mitochondrial activity. Fuziline and paeoniflorin, in particular, emerge as promising mitochondrial protectants and warrant further investigation. This research underpins the development of innovative treatments for DILI using SQP and its components.

FAK inhibition delays liver repair after acetaminophen-induced acute liver injury by suppressing hepatocyte proliferation and macrophage recruitment

BACKGROUND

Overdose of acetaminophen (APAP), a commonly used antipyretic analgesic, can lead to severe liver injury and failure. Current treatments are only effective in the early stages of APAP-induced acute liver injury (ALI). Therefore, a detailed examination of the mechanisms involved in liver repair following APAP-induced ALI could provide valuable insights for clinical interventions.

METHODS

4D-label-free proteomics analysis was used to identify dysregulated proteins in the liver of APAP-treated mice. RNA-Seq, hematoxylin-eosin staining, immunohistochemical staining, immunofluorescence staining, quantitative PCR, western blotting, transwell were used to explore the underlying mechanisms.

RESULTS

Utilizing high throughput 4D-label-free proteomics analysis, we observed a notable increase in proteins related to the "focal adhesion" pathway in the livers of APAP-treated mice. Inhibiting focal adhesion kinase (FAK) activation with a specific inhibitor, 1,2,4,5-Benzenetetraamine tetrahydrochloride (also called Y15), resulted in reduced macrophage numbers, delayed necrotic cell clearance, and inhibited liver cell proliferation in the necrotic regions of APAP-treated mice. RNA-Seq analysis demonstrated that Y15 downregulated genes associated with "cell cycle" and "phagosome" pathways in the livers of APAP-treated mice. Furthermore, blocking extracellular matrix (ECM)-integrin activation with a competitive peptide inhibitor, Gly-Arg-Gly-Asp-Ser (GRGDS), suppressed FAK activation and liver cell proliferation without affecting macrophage recruitment to necrotic areas. Mechanistically, ECM-induced FAK activation upregulated growth-promoting cell cycle genes, leading to hepatocyte proliferation, while CCL2 enhanced FAK activation and subsequent macrophage recruitment via F-actin rearrangement.

CONCLUSIONS

Overall, these findings underscore the pivotal role of FAK activation in liver repair post-APAP overdose by promoting liver cell proliferation and macrophage recruitment.

Clinically relevant therapeutic approaches against acetaminophen hepatotoxicity and acute liver failure

Liver injury and acute liver failure caused by an acetaminophen (APAP) overdose is a significant clinical problem in western countries. With the introduction of the mouse model of APAP hepatotoxicity in the 1970 s, fundamental mechanisms of cell death were discovered. This included the recognition that part of the APAP dose is metabolized by cytochrome P450 generating a reactive metabolite that is detoxified by glutathione. After the partial depletion of glutathione, the reactive metabolite will covalently bind to sulfhydryl groups of proteins, which is the initiating event of the toxicity. This insight led to the introduction of N-acetyl-L-cysteine, a glutathione precursor, as antidote against APAP overdose in the clinic. Despite substantial progress in our understanding of the pathomechanisms over the last decades viable new antidotes only emerged recently. This review will discuss the background, mechanisms of action, and the clinical prospects of the existing FDA-approved antidote N-acetylcysteine, of several new drug candidates under clinical development [4-methylpyrazole (fomepizole), calmangafodipir] and examples of additional therapeutic targets (Nrf2 activators) and regeneration promoting agents (thrombopoietin mimetics, adenosine A2B receptor agonists, Wharton's Jelly mesenchymal stem cells). Although there are clear limitations of certain therapeutic approaches, there is reason to be optimistic. The substantial progress in the understanding of the pathophysiology of APAP hepatotoxicity led to the consideration of several drugs for development as clinical antidotes against APAP overdose in recent years. Based on the currently available information, it is likely that this will result in additional drugs that could be used as adjunct treatment for N-acetylcysteine.

Formononetin triggers ferroptosis in triple-negative breast cancer cells by regulating the mTORC1/SREBP1/SCD1 pathway

Introduction

Triple-negative breast cancer (TNBC) is the most malignant type of breast cancer, and its prognosis is still the worst. It is necessary to constantly explore the pathogenesis and effective therapeutic targets of TNBC. Formononetin is an active ingredient with anti-tumor effects that we screened earlier. The main purpose of this study is to elucidate mechanism of the inhibitory effect of Formononetin on TNBC.

Methods

We conducted experiments through both in vivo and in vitro methodologies. The in vivo experiments utilized a nude mice xenotransplantation model, while the in vitro investigations employed two breast cancer cell lines, MDA-MB-231 and MDA-MB-468. Concurrently, ferroptosis associated proteins, lipid peroxide levels, and proteins related to the rapamycin complex 1 were analyzed in both experimental settings.

Results

In our study, Formononetin exhibits significant inhibitory effects on the proliferation of triple TNBC, both in vivo and in vitro. Moreover, it elicits an increase in lipid peroxide levels, downregulates the expression of ferroptosis-associated proteins GPX4 and xCT, and induces ferroptosis in breast cancer cells. Concurrently, Formononetin impedes the formation of the mammalian target of rapamycin complex 1 (mTORC1) and suppresses the expression of downstream Sterol regulatory element-binding protein 1(SREBP1). The utilization of breast cancer cells with SREBP1 overexpression or knockout demonstrates that Formononetin induces ferroptosis by modulating the mTORC1-SREBP1 signaling axis.

Discussion

In conclusion, this study provides evidence that Formononetin exerts an anti-proliferative effect on triple-negative breast cancer by inducing ferroptosis. Moreover, the mTORC1-SREBP1 signal axis is identified as the primary mechanism through which formononetin exerts its therapeutic effects. These findings suggest that formononetin holds promise as a potential targeted drug for clinical treatment of TNBC.

Paeoniflorin protects hepatocytes from APAP-induced damage through launching autophagy via the MAPK/mTOR signaling pathway

BACKGROUND

Drug-induced liver injury (DILI) is gradually becoming a common global problem that causes acute liver failure, especially in acute hepatic damage caused by acetaminophen (APAP). Paeoniflorin (PF) has a wide range of therapeutic effects to alleviate a variety of hepatic diseases. However, the relationship between them is still poorly investigated in current studies.

PURPOSE

This work aimed to explore the protective effects of PF on APAP-induced hepatic damage and researched the potential molecular mechanisms.

METHODS

C57BL/6J male mice were injected with APAP to establish DILI model and were given PF for five consecutive days for treatment. Aiming to clarify the pharmacological effects, the molecular mechanisms of PF in APAP-induced DILI was elucidated by high-throughput and other techniques.

RESULTS

The results demonstrated that serum levels of ALP, γ-GT, AST, TBIL, and ALT were decreased in APAP mice by the preventive effects of PF. Moreover, PF notably alleviated hepatic tissue inflammation and edema. Meanwhile, the results of TUNEL staining and related apoptotic factors coincided with the results of transcriptomics, suggesting that PF inhibited hepatocyte apoptosis by regulated MAPK signaling. Besides, PF also acted on reactive oxygen species (ROS) to regulate the oxidative stress for recovery the damaged mitochondria. More importantly, transmission electron microscopy showed the generation of autophagosomes after PF treatment, and PF was also downregulated mTOR and upregulated the expression of autophagy markers such as ATG5, ATG7, and BECN1 at the mRNA level and LC3, p62, ATG5, and ATG7 at the protein level, implying that the process by which PF exerted its effects was accompanied by the occurrence of autophagy. In addition, combinined with molecular dynamics simulations and western blotting of MAPK, the results suggested p38 as a direct target for PF on APAP. Specifically, PF-activated autophagy through the downregulation of MAPK/mTOR signaling, which in turn reduced APAP injury.

CONCLUSIONS

Paeoniflorin mitigated liver injury by activating autophagy to suppress oxidative stress and apoptosis via the MAPK/mTOR signaling pathway. Taken together, our findings elucidate the role and mechanism of paeoniflorin in DILI, which is expected to provide a new therapeutic strategy for the development of paeoniflorin.

Protein disulfide isomerase plays a crucial role in mediating chemically-induced, glutathione depletion-associated hepatocyte injury in vitro and in vivo

Recently we have shown that protein disulfide isomerase (PDI or PDIA1) is involved in mediating chemically-induced, glutathione (GSH) depletion-associated ferroptotic cell death through NOS activation (dimerization) and NO accumulation. The present study aims to determine the role of PDI in mediating chemically-induced hepatocyte injury in vitro and in vivo and whether PDI inhibitors can effectively protect against chemically-induced hepatocyte injury. We show that during the development of erastin-induced ferroptotic cell death, accumulation of cellular NO, ROS and lipid-ROS follows a sequential order, i.e., cellular NO accumulation first, followed by accumulation of cellular ROS, and lastly cellular lipid-ROS. Cellular NO, ROS and lipid-ROS each play a crucial role in mediating erastin-induced ferroptosis in cultured hepatocytes. In addition, it is shown that PDI is an important upstream mediator of erastin-induced ferroptosis through PDI-mediated conversion of NOS monomer to its dimer, which then leads to accumulation of cellular NO, ROS and lipid-ROS, and ultimately ferroptotic cell death. Genetic manipulation of PDI expression or pharmacological inhibition of PDI function each can effectively abrogate erastin-induced ferroptosis. Lastly, evidence is presented to show that PDI is also involved in mediating acetaminophen-induced liver injury in vivo using both wild-type C57BL/6J mice and hepatocyte-specific PDI conditional knockout (PDIfl/fl Alb-cre) mice. Together, our work demonstrates that PDI is an important upstream mediator of chemically-induced, GSH depletion-associated hepatocyte ferroptosis, and inhibition of PDI can effectively prevent this injury.

Isolation and characterization of a hepatoprotective polysaccharide from Lonicera caerulea L. var. edulis Turcz. ex Herd. fruit against APAP-induced acute liver injury mice

The structure and bioactivities of a novel polysaccharide from Lonicera caerulea L. var. edulis Turcz. ex Herd. fruit (THP-3) were investigated. The crude polysaccharides of Turcz. ex Herd. (THP) were extracted by hot water extraction. After purification, the chemical structure of polysaccharides was identified. Then, a mouse model of acute drug-induced liver injury was constructed using 4-acetamidophenol (APAP) and pretreated with THP. The number-average molecular weight of THP-3 was 48.89 kDa and the mass average molar mass was 97.87 kDa. THP-3 was mainly composed of arabinose (42.54 %), glucose (27.62 %), galacturonic acid and galactose (29.84 %). The main linkage types of THP-3 were 1-linked Araf, 1,4-linked Glcp, and 1,3,6-linked Galp. In addition, after THP treatment, serum Alanine aminotransferase (ALT), Aspartate aminotransferase (AST) and γ-glutamyl transpeptidase (γGT) in AILI mice were successfully down-regulated. The results showed that THP could prevent the characteristic morphological changes of hepatic lobular injury and lipid depletion caused by APAP, reduced the level of oxidative damage in mice, increased the expression of APAP-induced hypolipidemia and related inflammatory indicators, and improved the detoxification function of liver. In general, the newly extracted THP polysaccharide has a good liver protection effect and is an ideal natural medicine for the treatment of liver diseases.

HMGB1 as an extracellular pro-inflammatory cytokine: Implications for drug-induced organic damage

Drug-induced organic damage encompasses various intricate mechanisms, wherein HMGB1, a non-histone chromosome-binding protein, assumes a significant role as a pivotal hub gene. The regulatory functions of HMGB1 within the nucleus and extracellular milieu are interlinked. HMGB1 exerts a crucial regulatory influence on key biological processes including cell survival, inflammatory regulation, and immune response. HMGB1 can be released extracellularly from the cell during these processes, where it functions as a pro-inflammation cytokine. HMGB1 interacts with multiple cell membrane receptors, primarily Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE), to stimulate immune cells and trigger inflammatory response. The excessive or uncontrolled HMGB1 release leads to heightened inflammatory responses and cellular demise, instigating inflammatory damage or exacerbating inflammation and cellular demise in different diseases. Therefore, a thorough review on the significance of HMGB1 in drug-induced organic damage is highly important for the advancement of pharmaceuticals, ensuring their effectiveness and safety in treating inflammation as well as immune-related diseases. In this review, we initially outline the characteristics and functions of HMGB1, emphasizing their relevance in disease pathology. Then, we comprehensively summarize the prospect of HMGB1 as a promising therapeutic target for treating drug-induced toxicity. Lastly, we discuss major challenges and propose potential avenues for advancing the development of HMGB1-based therapeutics.

Cellular Senescence in Acute Liver Injury: What Happens to the Young Liver?

Cellular senescence, characterized by irreversible cell cycle arrest, not only exists in age-related physiological states, but has been found to exist in various diseases. It plays a crucial role in both physiological and pathological processes and has become a trending topic in global research in recent years. Acute liver injury (ALI) has a high incidence worldwide, and recent studies have shown that hepatic senescence can be induced following ALI. Therefore, we reviewed the significance of cellular senescence in ALI. To minimize the potential confounding effects of aging on cellular senescence and ALI outcomes, we selected studies involving young individuals to identify the characteristics of senescent cells, the value of cellular senescence in liver repair, its regulation mechanisms in ALI, its potential as a biomarker for ALI, the prospect of treatment, and future research directions.

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.

The thrombopoietin mimetic JNJ-26366821 reduces the late injury and accelerates the onset of liver recovery after acetaminophen-induced liver injury in mice

Acetaminophen (APAP)-induced hepatotoxicity is comprised of an injury and recovery phase. While pharmacological interventions, such as N-acetylcysteine (NAC) and 4-methylpyrazole (4-MP), prevent injury there are no therapeutics that promote recovery. JNJ-26366821 (TPOm) is a novel thrombopoietin mimetic peptide with no sequence homology to endogenous thrombopoietin (TPO). Endogenous thrombopoietin is produced by hepatocytes and the TPO receptor is present on liver sinusoidal endothelial cells in addition to megakaryocytes and platelets, and we hypothesize that TPOm activity at the TPO receptor in the liver provides a beneficial effect following liver injury. Therefore, we evaluated the extent to which TPOm, NAC or 4-MP can provide a protective and regenerative effect in the liver when administered 2 h after an APAP overdose of 300 mg/kg in fasted male C57BL/6J mice. TPOm did not affect protein adducts, oxidant stress, DNA fragmentation and hepatic necrosis up to 12 h after APAP. In contrast, TPOm treatment was beneficial at 24 h, i.e., all injury parameters were reduced by 42-48%. Importantly, TPOm enhanced proliferation by 100% as indicated by PCNA-positive hepatocytes around the area of necrosis. When TPOm treatment was delayed by 6 h, there was no effect on the injury, but a proliferative effect was still evident. In contrast, 4MP and NAC treated at 2 h after APAP significantly attenuated all injury parameters at 24 h but failed to enhance hepatocyte proliferation. Thus, TPOm arrests the progression of liver injury by 24 h after APAP and accelerates the onset of the proliferative response which is essential for liver recovery.

Transcriptomic signature, bioactivity and safety of a non-hepatotoxic analgesic generating AM404 in the midbrain PAG region

Safe and effective pain management is a critical healthcare and societal need. The potential for acute liver injury from paracetamol (ApAP) overdose; nephrotoxicity and gastrointestinal damage from chronic non-steroidal anti-inflammatory drug (NSAID) use; and opioids' addiction are unresolved challenges. We developed SRP-001, a non-opioid and non-hepatotoxic small molecule that, unlike ApAP, does not produce the hepatotoxic metabolite N-acetyl-p-benzoquinone-imine (NAPQI) and preserves hepatic tight junction integrity at high doses. CD-1 mice exposed to SRP-001 showed no mortality, unlike a 70% mortality observed with increasing equimolar doses of ApAP within 72 h. SRP-001 and ApAP have comparable antinociceptive effects, including the complete Freund's adjuvant-induced inflammatory von Frey model. Both induce analgesia via N-arachidonoylphenolamine (AM404) formation in the midbrain periaqueductal grey (PAG) nociception region, with SRP-001 generating higher amounts of AM404 than ApAP. Single-cell transcriptomics of PAG uncovered that SRP-001 and ApAP also share modulation of pain-related gene expression and cell signaling pathways/networks, including endocannabinoid signaling, genes pertaining to mechanical nociception, and fatty acid amide hydrolase (FAAH). Both regulate the expression of key genes encoding FAAH, 2-arachidonoylglycerol (2-AG), cannabinoid receptor 1 (CNR1), CNR2, transient receptor potential vanilloid type 4 (TRPV4), and voltage-gated Ca2+ channel. Phase 1 trial (NCT05484414) (02/08/2022) demonstrates SRP-001's safety, tolerability, and favorable pharmacokinetics, including a half-life from 4.9 to 9.8 h. Given its non-hepatotoxicity and clinically validated analgesic mechanisms, SRP-001 offers a promising alternative to ApAP, NSAIDs, and opioids for safer pain treatment.

Targeting cathepsin C ameliorates murine acetaminophen-induced liver injury

Acetaminophen (APAP) overdosing is a major cause of acute liver failure worldwide and an established model for drug-induced acute liver injury (ALI). While studying gene expression during murine APAP-induced ALI by 3'mRNA sequencing (massive analysis of cDNA ends, MACE), we observed splenic mRNA accumulation encoding for the neutrophil serine proteases cathepsin G, neutrophil elastase, and proteinase-3 - all are hierarchically activated by cathepsin C (CtsC). This, along with increased serum levels of these proteases in diseased mice, concurs with the established phenomenon of myeloid cell mobilization during APAP intoxication. Objective: In order to functionally characterize CtsC in murine APAP-induced ALI, effects of its genetic or pharmacological inhibition were investigated. Methods and Results: We report on substantially reduced APAP toxicity in CtsC deficient mice. Alleviation of disease was likewise observed by treating mice with the CtsC inhibitor AZD7986, both in short-term prophylactic and therapeutic protocols. This latter observation indicates a mode of action beyond inhibition of granule-associated serine proteases. Protection in CtsC knockout or AZD7986-treated wildtype mice was unrelated to APAP metabolization but, as revealed by MACE, realtime PCR, or ELISA, associated with impaired expression of inflammatory genes with proven pathogenic roles in ALI. Genes consistently downregulated in protocols tested herein included cxcl2, mmp9, and angpt2. Moreover, ptpn22, a positive regulator of the toll-like receptor/interferon-axis, was reduced by targeting CtsC. Conclusions: This work suggests CtsC as promising therapeutic target for the treatment of ALI, among others paradigmatic APAP-induced ALI. Being also currently evaluated in phase III clinical trials for bronchiectasis, successful application of AZD7986 in experimental APAP intoxication emphasizes the translational potential of this latter therapeutic approach.

Cynarin alleviates acetaminophen-induced acute liver injury through the activation of Keap1/Nrf2-mediated lipid peroxidation defense via the AMPK/SIRT3 signaling pathway

Overdose of Acetaminophen (APAP) is a major contributor to acute liver injury (ALI), a complex pathological process with limited effective treatments. Emerging evidence links lipid peroxidation to APAP-induced ALI. Cynarin (Cyn), a hydroxycinnamic acid derivative, exhibits liver protective effects, but whether it mitigates APAP-induced ALI is unclear. Our aim was to verify the protective impact of Cyn on APAP-induced ALI and elucidate the molecular mechanisms governing this process. Herein, the regulation of the Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) interaction was determined to be a novel mechanism underlying this protective impact of Cyn against APAP-induced ALI. Nrf2 deficiency increased the severity of APAP-induced ALI and lipid peroxidation and counteracted the protective effect of Cyn against this pathology. Additionally, Cyn promoted the dissociation of Nrf2 from Keap1, enhancing the nuclear translocation of Nrf2 and the transcription of downstream antioxidant proteins, thereby inhibiting lipid peroxidation. Molecular docking demonstrated that Cyn bound competitively to Keap1, and overexpression of Keap1 reversed Nrf2-activated anti-lipid peroxidation. Additionally, Cyn activated the adenosine monophosphate-activated protein kinase (AMPK)/sirtuin (SIRT)3 signaling pathway, which exhibits a protective effect on APAP-induced ALI. These findings propose that Cyn alleviates APAP-induced ALI by enhancing the Keap1/Nrf2-mediated lipid peroxidation defense via activation of the AMPK/SIRT3 signaling pathway.

Acetaminophen overdose causes a breach of the blood-bile barrier in mice but not in rats

Acetaminophen (APAP) is known to cause a breach of the blood-bile barrier in mice that, via a mechanism called futile bile acid (BA) cycling, increases BA concentrations in hepatocytes above cytotoxic thresholds. Here, we compared this mechanism in mice and rats, because both species differ massively in their susceptibility to APAP and compared the results to available human data. Dose and time-dependent APAP experiments were performed in male C57BL6/N mice and Wistar rats. The time course of BA concentrations in liver tissue and in blood was analyzed by MALDI-MSI and LC-MS/MS. APAP and its derivatives were measured in the blood by LC-MS. APAP-induced liver damage was analyzed by histopathology, immunohistochemistry, and by clinical chemistry. In mice, a transient increase of BA in blood and in peri-central hepatocytes preceded hepatocyte death. The BA increase coincided with oxidative stress in liver tissue and a compromised morphology of bile canaliculi and immunohistochemically visualized tight junction proteins. Rats showed a reduced metabolic activation of APAP compared to mice. However, even at very high doses that caused cell death of hepatocytes, no increase of BA concentrations was observed neither in liver tissue nor in the blood. Correspondingly, no oxidative stress was detectable, and the morphology of bile canaliculi and tight junction proteins remained unaltered. In conclusion, different mechanisms cause cell death in rats and mice, whereby oxidative stress and a breach of the blood-bile barrier are seen only in mice. Since transient cholestasis also occurs in human patients with APAP overdose, mice are a clinically relevant species to study APAP hepatotoxicity but not rats.

NLRP3 deficiency protects against acetaminophen‑induced liver injury by inhibiting hepatocyte pyroptosis

Acetaminophen (APAP) overdose is the primary cause of drug‑induced acute liver failure in numerous Western countries. NLR family pyrin domain containing 3 (NLRP3) inflammasome activation serves a pivotal role in the pathogenesis of various forms of acute liver injury. However, the cellular source for NLRP3 induction and its involvement during APAP‑induced hepatotoxicity have not been thoroughly investigated. In the present study, hematoxylin and eosin staining was performed to assess histopathological changes of liver tissue. Immunohistochemistry staining(NLRP3, Caspase‑1, IL‑1β, GSDMD and Caspase‑3), western blotting (NLRP3, Caspase‑1, IL‑1β, GSDMD and Caspase‑3) and RT‑qPCR (NLRP3, Caspase‑1 and IL‑1β) were performed to assess the expression of NLRP3/GSDMD signaling pathway. TUNEL staining was performed to assess apoptosis of liver tissue. The serum expression levels of inflammatory factors (IL‑6, IL‑18, IL‑1β and TNF‑α) were assessed using ELISA and inflammation of liver tissue was assessed using immunohistochemistry (Ly6G and CD68) and RT‑qPCR (TNF‑α, Il‑6, Mcp‑1, Cxcl‑1, Cxcl‑2). A Cell Counting Kit‑8 was performed to assess cell viability and apoptosis. Protein and gene expression were analyzed by western blotting (PCNA, CCND1) and RT‑qPCR (CyclinA2, CyclinD1 and CyclinE1). Through investigation of an APAP‑induced acute liver injury model (AILI), the present study demonstrated that APAP overdose induced activation of NLRP3 and cleavage of gasdermin D (GSDMD) in hepatocytes, both in vivo and in vitro. Additionally, mice with hepatocyte‑specific knockout of Nlrp3 exhibited reduced liver injury and lower mortality following APAP intervention, accompanied by decreased infiltration of inflammatory cells and attenuated inflammatory response. Furthermore, pharmacological blockade of NLRP3/GSDMD signaling using MCC950 or disulfiram significantly ameliorated liver injury and reduced hepatocyte death. Notably, hepatocyte Nlrp3 deficiency promoted liver recovery by enhancing hepatocyte proliferation. Collectively, the present study demonstrated that inhibition of the NLRP3 inflammasome protects against APAP‑induced acute liver injury by reducing hepatocyte pyroptosis and suggests that targeting NLRP3 may hold therapeutic potential for treating AILI.

Microphysiological systems for human aging research

Recent advances in microphysiological systems (MPS), also known as organs-on-a-chip (OoC), enable the recapitulation of more complex organ and tissue functions on a smaller scale in vitro. MPS therefore provide the potential to better understand human diseases and physiology. To date, numerous MPS platforms have been developed for various tissues and organs, including the heart, liver, kidney, blood vessels, muscle, and adipose tissue. However, only a few studies have explored using MPS platforms to unravel the effects of aging on human physiology and the pathogenesis of age-related diseases. Age is one of the risk factors for many diseases, and enormous interest has been devoted to aging research. As such, a human MPS aging model could provide a more predictive tool to understand the molecular and cellular mechanisms underlying human aging and age-related diseases. These models can also be used to evaluate preclinical drugs for age-related diseases and translate them into clinical settings. Here, we provide a review on the application of MPS in aging research. First, we offer an overview of the molecular, cellular, and physiological changes with age in several tissues or organs. Next, we discuss previous aging models and the current state of MPS for studying human aging and age-related conditions. Lastly, we address the limitations of current MPS and present future directions on the potential of MPS platforms for human aging research.

NEDD4 lactylation promotes APAP induced liver injury through Caspase11 dependent non-canonical pyroptosis

Caspase-11 detection of intracellular lipopolysaccharide mediates non-canonical pyroptosis, which could result in inflammatory damage and organ lesions in various diseases such as sepsis. Our research found that lactate from the microenvironment of acetaminophen-induced acute liver injury increased Caspase-11 levels, enhanced gasdermin D activation and accelerated macrophage pyroptosis, which lead to exacerbation of liver injury. Further experiments unveiled that lactate inhibits Caspase-11 ubiquitination by reducing its binding to NEDD4, a negative regulator of Caspase-11. We also identified that lactates regulated NEDD4 K33 lactylation, which inhibits protein interactions between Caspase-11 and NEDD4. Moreover, restraining lactylation reduces non-canonical pyroptosis in macrophages and ameliorates liver injury. Our work links lactate to the exquisite regulation of the non-canonical inflammasome, and provides a basis for targeting lactylation signaling to combat Caspase-11-mediated non-canonical pyroptosis and acetaminophen-induced liver injury.

High-throughput screening of novel TFEB agonists in protecting against acetaminophen-induced liver injury in mice

Macroautophagy (referred to as autophagy hereafter) is a major intracellular lysosomal degradation pathway that is responsible for the degradation of misfolded/damaged proteins and organelles. Previous studies showed that autophagy protects against acetaminophen (APAP)-induced injury (AILI) via selective removal of damaged mitochondria and APAP protein adducts. The lysosome is a critical organelle sitting at the end stage of autophagy for autophagic degradation via fusion with autophagosomes. In the present study, we showed that transcription factor EB (TFEB), a master transcription factor for lysosomal biogenesis, was impaired by APAP resulting in decreased lysosomal biogenesis in mouse livers. Genetic loss-of and gain-of function of hepatic TFEB exacerbated or protected against AILI, respectively. Mechanistically, overexpression of TFEB increased clearance of APAP protein adducts and mitochondria biogenesis as well as SQSTM1/p62-dependent non-canonical nuclear factor erythroid 2-related factor 2 (NRF2) activation to protect against AILI. We also performed an unbiased cell-based imaging high-throughput chemical screening on TFEB and identified a group of TFEB agonists. Among these agonists, salinomycin, an anticoccidial and antibacterial agent, activated TFEB and protected against AILI in mice. In conclusion, genetic and pharmacological activating TFEB may be a promising approach for protecting against AILI.

LncRNA-mediated Modulation of Endothelial Cells: Novel Progress in the Pathogenesis of Coronary Atherosclerotic Disease

Coronary atherosclerotic disease (CAD) is a common cardiovascular disease and an important cause of death. Moreover, endothelial cells (ECs) injury is an early pathophysiological feature of CAD, and long noncoding RNAs (lncRNAs) can modulate gene expression. Recent studies have shown that lncRNAs are involved in the pathogenesis of CAD, especially by regulating ECs. In this review, we summarize the novel progress of lncRNA-modulated ECs in the pathogenesis of CAD, including ECs proliferation, migration, adhesion, angiogenesis, inflammation, apoptosis, autophagy, and pyroptosis. Thus, as lncRNAs regulate ECs in CAD, lncRNAs will provide ideal and novel targets for the diagnosis and drug therapy of CAD.

Construction, Features and Regulatory Aspects of Organ-chip for Drug Delivery Applications: Advances and Prospective

Organ-on-chip is an innovative technique that emerged from tissue engineering and microfluidic technologies. Organ-on-chip devices (OoCs) are anticipated to provide efficient explanations for dealing with challenges in pharmaceutical advancement and individualized illness therapies. Organ-on-chip is an advanced method that can replicate human organs' physiological conditions and functions on a small chip. It possesses the capacity to greatly transform the drug development process by enabling the simulation of diseases and the testing of drugs. Effective integration of this advanced technical platform with common pharmaceutical and medical contexts is still a challenge. Microfluidic technology, a micro-level technique, has become a potent tool for biomedical engineering research. As a result, it has revolutionized disciplines, including physiological material interpreting, compound detection, cell-based assay, tissue engineering, biological diagnostics, and pharmaceutical identification. This article aims to offer an overview of newly developed organ-on-a-chip systems. It includes single-organ platforms, emphasizing the most researched organs, including the heart, liver, blood arteries, and lungs. Subsequently, it provides a concise overview of tumor-on-a-chip systems and emphasizes their use in evaluating anti-cancer medications.

Targeting ferroptosis with natural products in liver injury: new insights from molecular mechanisms to targeted therapies

BACKGROUND

Ferroptosis is a brand-new type of controlled cell death that is distinguished by its reliance on iron and the production of lipid peroxidation. The role of ferroptosis in damaging liver disorders has attracted a lot of attention in recent years. One effective strategy to reduce liver damage is to target ferroptosis.

PURPOSE

The purpose of this review is to clarify the connection between ferroptosis and liver damage and to look into the potential contribution of natural products to the clinical management of liver damage and the discovery of novel medications.

METHODS

To study the methods by which natural products operate on ferroptosis to cure liver damage and their main signaling pathways, we searched databases from the time of initial publication to August 2023 in PubMed, EMBASE, Web of Science, Ovid, ScienceDirect, and China National Knowledge Infrastructure. The liver illness that each natural product treats is categorized and summarized. It's interesting to note that several natural compounds, such Artemether, Fucoidan sulfate, Curcumin, etc., have the benefit of having many targets and multiple pathways of action.

RESULTS

We saw that in human samples or animal models of liver injury, ferroptosis indicators were activated, lipid peroxidation levels were elevated, and iron inhibitors had the ability to reduce liver damage. Liver damage can be treated with natural products by regulating ferroptosis. This is mostly accomplished through the modulation of Nrf2-related pathways (e.g., Conclusions and Astaxanthin), biological enzymes like GPX4 and the SIRT family (e.g., Chrysophanol and Decursin), and transcription factors like P53 (e.g., Artemether and Zeaxanthin).

CONCLUSIONS

This review proposes a promising path for the therapeutic therapy of liver damage by providing a theoretical foundation for the management of ferroptosis utilizing natural ingredients.

Development of Efficient Sodium Alginate/Polysuccinimide-Based Hydrogels as Biodegradable Acetaminophen Delivery Systems

Efficient drug delivery systems are essential for improving patient outcomes. Acetaminophen (AP), which is a kind of oral administration, is a commonly used pain reliever and fever reducer. However, oral administration carries various health risks, especially overdose and frequent use; for instance, AP is administered approximately 4 times per day. Therefore, the aim of this study is to develop an efficient delivery system for once-daily administration by combining sodium alginate and polysuccinimide (PSI) hydrogels to delay the release of analgesic AP. PSI is a biodegradable polymer that can be used safely and effectively in drug delivery systems because it is eliminated by hydrolysis in the intestine. The use of PSI also improves the mechanical properties of hydrogels and prolongs drug release. In this study, hydrogel characterizations such as mechanical properties, drug dissolution ability, and biodegradability were measured to evaluate the hydrolysis of PSI in the intestine. Based on the results, hydrogels could be designed to improve the structural mechanical properties and to allow the drug to be completely dissolved, and eliminated from the body through PSI hydrolysis in the intestines. In addition, the release profiles of AP in the hydrogels were evaluated, and the hydrogels provided continuous release of AP for 24 h. Our research suggests that sodium alginate/PSI hydrogels can potentially serve as biodegradable delivery systems for AP. These findings may have significant implications for developing efficient drug delivery systems for other classes of drugs.

P2rx1 deficiency alleviates acetaminophen-induced acute liver failure by regulating the STING signaling pathway

AIMS

Purinergic signaling-mediated mitochondria dysfunction and innate immune-mediated inflammation act as triggers during acetaminophen (APAP)-induced liver injury (AILI). However, the underlying mechanisms by which purinoceptor regulates mitochondria function and inflammation response in the progression of AILI remains unclear.

METHODS

First, the hepatic level of purinergic receptor P2X 1 (P2RX1) was identified in the DILI patients and APAP-induced WT mice. P2rx1 knockout (KO) mice (P2rx1-/-) with 300 mg/kg APAP challenge were used for the analysis of the potential role of P2RX1 in the progression of AILI. Administration of DMX, the activator of stimulator of interferon genes (STING), was performed to investigate the effects of the STING-related pathway on APAP-treated P2rx1-/- mice.

RESULTS

The elevated hepatic P2RX1 levels were found in DILI patients and the AILI mice. P2rx1 depletion offered protection against the initial stages of AILI, mainly by inhibiting cell death and promoting inflammation resolution, which was associated with alleviating mitochondria dysfunction. Mechanistically, P2rx1 depletion could inhibit STING-TANK-binding kinase 1 (TBK1)-P65 signaling pathways in vivo. We then showed that DMX-mediated STING activation could greatly aggravate the liver injury of P2rx1-/- mice treated with APAP.

CONCLUSION

Our data confirmed that P2RX1 was inducted during AILI, identified P2RX1 as a novel regulator in mitochondria dysfunction and STING pathways, and suggested a promising therapeutic approach for AILI involving the blockade of P2RX1. 1. It first demonstrated the protective effects of P2rx1 deficiency on acetaminophen-induced liver injury (AILI). 2. P2rx1 knockout alleviates mitochondria function and promotes inflammation resolution after APAP treatment. 3. It first reported the regulation of P2RX1 on the STING signaling pathway in the progress of AILI. 4. P2RX1 blockade is a promising therapeutic strategy for AILI.

EGR1 is crucial for the chlorogenic acid-provided promotion on liver regeneration and repair after APAP-induced liver injury

Improper use of acetaminophen (APAP) will induce acute liver failure. This study is designed to investigate whether early growth response-1 (EGR1) participated in the promotion on liver repair and regeneration after APAP-induced hepatotoxicity provided by natural compound chlorogenic acid (CGA). APAP induced the nuclear accumulation of EGR1 in hepatocytes regulated by extracellular-regulated protein kinase (ERK)1/2. In Egr1 knockout (KO) mice, the liver damage caused by APAP (300 mg/kg) was more severe than in wild-type (WT) mice. Results of chromatin immunoprecipitation and sequencing (ChIP-Seq) manifested that EGR1 could bind to the promoter region in Becn1, Ccnd1, and Sqstm1 (p62) or the catalytic/modify subunit of glutamate-cysteine ligase (Gclc/Gclm). Autophagy formation and APAP-cysteine adduct (APAP-CYS) clearance were decreased in Egr1 KO mice administered with APAP. The EGR1 deletion reduced hepatic cyclin D1 expression at 6, 12, or 18 h post APAP administration. Meanwhile, the EGR1 deletion also decreased hepatic p62, Gclc and Gclm expression, GCL enzymatic activity, and glutathione (GSH) content and decreased nuclear factor erythroid 2-related factor 2 (Nrf2) activation and thus aggravated oxidative liver injury induced by APAP. CGA increased EGR1 nuclear accumulation; enhanced hepatic Ccnd1, p62, Gclc, and Gclm expression; and accelerated the liver regeneration and repair in APAP-intoxicated mice. In conclusion, EGR1 deficiency aggravated liver injury and obviously delayed liver regeneration post APAP-induced hepatotoxicity through inhibiting autophagy, enhancing liver oxidative injury, and retarding cell cycle progression, but CGA promoted the liver regeneration and repair in APAP-intoxicated mice via inducing EGR1 transcriptional activation.

Cysteine conjugates of acetaminophen and p-aminophenol are potent inducers of cellular impairment in human proximal tubular kidney HK-2 cells

Acetaminophen (APAP) belong among the most used analgesics and antipyretics. It is structurally derived from p-aminophenol (PAP), a potent inducer of kidney toxicity. Both compounds can be metabolized to oxidation products and conjugated with glutathione. The glutathione-conjugates can be cleaved to provide cysteine conjugates considered as generally nontoxic. The aim of the present report was to synthesize and to purify both APAP- and PAP-cysteine conjugates and, as the first study at all, to evaluate their biological effects in human kidney HK-2 cells in comparison to parent compounds. HK-2 cells were treated with tested compounds (0-1000 µM) for up to 24 h. Cell viability, glutathione levels, ROS production and mitochondrial function were determined. After 24 h, we found that both APAP- and PAP-cysteine conjugates (1 mM) were capable to induce harmful cellular damage observed as a decrease of glutathione levels to 10% and 0%, respectively, compared to control cells. In addition, we detected the disappearance of mitochondrial membrane potential in these cells. In the case of PAP-cysteine, the extent of cellular impairment was comparable to that induced by PAP at similar doses. On the other hand, 1 mM APAP-cysteine induced even larger damage of HK-2 cells compared to 1 mM APAP after 6 or 24 h. We conclude that cysteine conjugates with aminophenol are potent inducers of oxidative stress causing significant injury in kidney cells. Thus, the harmful effects cysteine-aminophenolic conjugates ought to be considered in the description of APAP or PAP toxicity.

Excessive N-acetylcysteine exaggerates glutathione redox homeostasis and apoptosis during acetaminophen exposure in Huh-7 human hepatoma cells

Acetaminophen (APAP) hepatotoxicity is one of the biggest drawbacks of this relatively safe and widely used drug. In addition to its hepatotoxicity, APAP also cause comparable levels of toxicity on human hepatoma cells. Here we show activation of the intrinsic caspase-9/3 pathway of apoptosis followed by gasdermin E (GSDME) cleavage and subsequent ballooning in APAP (10 mM, 72 h)-treated Huh-7 human hepatocarcinoma cells. N-acetylcysteine (NAC), an antioxidant currently used as an antidote for APAP overdose, does not alleviate APAP toxicity in Huh-7 cells; NAC overdose (10 mM) rather aggravates APAP toxicity. NAC overdose not only aggravates cell death, but also decreases the cellular GSH/GSSG ratio, an indicator of redox homeostasis of glutathione. These results show for the first time that APAP-induced apoptosis in hepatoma cells is followed by secondary necrosis via the caspase-3/GSDME pathway. NAC overdose (10 mM) not only worsens the glutathione redox status, but also accelerates this pathway.

Robust coagulation activation and coagulopathy in mice with experimental acetaminophen-induced liver failure

BACKGROUND

Patients with acetaminophen (APAP)-induced acute liver failure (ALF) display both hyper- and hypocoagulable changes not necessarily recapitulated by standard hepatotoxic doses of APAP used in mice (eg, 300 mg/kg).

OBJECTIVES

We sought to examine coagulation activation in vivo and plasma coagulation potential ex vivo in experimental settings of APAP-induced hepatotoxicity and repair (300-450 mg/kg) and APAP-induced ALF (600 mg/kg) in mice.

RESULTS

APAP-induced ALF was associated with increased plasma thrombin-antithrombin complexes, decreased plasma prothrombin, and a dramatic reduction in plasma fibrinogen compared with lower APAP doses. Hepatic fibrin(ogen) deposits increased independent of APAP dose, whereas plasma fibrin(ogen) degradation products markedly increased in mice with experimental ALF. Early pharmacologic anticoagulation (+2 hours after 600 mg/kg APAP) limited coagulation activation and reduced hepatic necrosis. The marked coagulation activation evident in mice with APAP-induced ALF was associated with a coagulopathy detectable ex vivo in plasma. Specifically, prolongation of the prothrombin time and inhibition of tissue factor-initiated clot formation were evident even after restoration of physiological fibrinogen concentrations. Plasma endogenous thrombin potential was similarly reduced at all APAP doses. Interestingly, in the presence of ample fibrinogen, ∼10 times more thrombin was required to clot plasma from mice with APAP-induced ALF compared with plasma from mice with simple hepatotoxicity.

CONCLUSION

The results indicate that robust pathologic coagulation cascade activation in vivo and suppressed coagulation ex vivo are evident in mice with APAP-induced ALF. This unique experimental setting may fill an unmet need as a model to uncover mechanistic aspects of the complex coagulopathy of ALF.