The role of apoptosis in acetaminophen hepatotoxicity

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.

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.

BTF3L4 Overexpression Mediates APAP-induced Liver Injury in Mouse and Cellular Models

Background and Aims

Acetaminophen (APAP)-induced liver injury (AILI) has an increasing incidence worldwide. However, the mechanisms contributing to such liver injury are largely unknown and no targeted therapy is currently available. The study aimed to investigate the effect of BTF3L4 overexpression on apoptosis and inflammation regulation in vitro and in vivo.

Methods

We performed a proteomic analysis of the AILI model and found basic transcription factor 3 like 4 (BTF3L4) was the only outlier transcription factor overexpressed in the AILI model in mice. BTF3L4 overexpression increased the degree of liver injury in the AILI model.

Results

BTF3L4 exerts its pathogenic effect by inducing an inflammatory response and damaging mitochondrial function. Increased BTF3L4 expression increases the degree of apoptosis, reactive oxygen species generation, and oxidative stress, which induces cell death and liver injury. The damage of mitochondrial function by BTF3L4 triggers a cascade of events, including reactive oxygen species accumulation and oxidative stress. According to the available AILI data, BTF3L4 expression is positively associated with inflammation and may be a potential biomarker of AILI.

Conclusions

Our results suggest that BTF3L4 is a pathogenic factor in AILI and may be a potential diagnostic maker for AILI.

Bioengineered MSCGFPCxcr2-Mmp13 Transplantation Alleviates Hepatic Fibrosis by Regulating Mammalian Target of Rapamycin Signaling

Aims: Hepatic fibrosis is the pathological change during chronic liver diseases (CLD) that turns into cirrhosis if not reversed timely. Allogenic mesenchymal stem cell (MSC) therapy is an alternative to liver transplantation for CLD. However, poor engraftment of the transplanted MSCs limits their therapeutic efficacy. MSCs express chemokine receptors that regulate their physiology. We observed several-fold increased expressions of Cxcl3 and decreased expression of Mmp13 in the fibrotic liver. Therefore, we bioengineered MSCs with stable overexpression of Cxcr2 (CXCL3-cognate receptor) and Mmp13, collagenase (MSCGFPCxcr2-Mmp13). Results: The CXCL3/CXCR2 axis significantly increased migration through the activation of AKT/ERK/mTOR signaling. These bioengineered MSCs transdifferentiated into hepatocyte-like cells (MSCGFPCxcr2-Mmp13-HLCs) that endured the drug-/hepatotoxicant-induced toxicity by significantly increasing the antioxidants-Nrf2 and Sod2, while decreasing the apoptosis-Cyt C, Casp3, Casp9, and drug-metabolizing enzyme-Cyp1A1, Cyp1A2, Cyp2E1 markers. Therapeutic transplantation of MSCGFPCxcr2-Mmp13 abrogated AAP-/CCl4-induced hepatic fibrosis in mice by CXCR2-mediated targeted engraftment and MMP-13-mediated reduction in collagen. Mechanistically, induction of CXCL3/CXCR2 axis-activated mTOR-p70S6K signaling led to increased targeted engraftment and modulation of the oxidative stress by increasing the expression and activity of nuclear Nrf2 and SOD2 expression in the regenerated hepatic tissues. A marked change in the fate of transplanted MSCGFPCxcr2-Mmp13 toward hepatocyte lineage demonstrated by co-immunostaining of GFP/HNF4α along with reduced COL1α1 facilitated the regeneration of the fibrotic liver. Innovation and Conclusions: Our study suggests the therapeutic role of allogenic Cxcr2/Mmp13-bioengineered MSC transplantation decreases the hepatic oxidative stress as an effective translational therapy for hepatic fibrosis mitigation-mediated liver regeneration.

Genista cephalantha Spach. protects against acetaminophen-induced liver failure via preserving the glutathione redox system, reducing inflammatory response, and inhibiting hepatocyte death in rats

Objectives

The current study was conducted to assess the protective mechanisms of n-BuOH fraction from the aerial part of Genista cephontala (BEGC) on APAP-induced liver injury compared to necrostatine-1 (Nec-1).

Materials and Methods

A model of APAP-induced hepatotoxicity was created in male rats by injecting a single dose; 1000 mg/kg APAP, the protective effect was performed with (200 mg/kg; 10 days) BEGC compared to Nec-1, (1.8 mg/kg).

Results

BEGC or NeC-1 pretreatment significantly abolished impaired effects in APAP-rats, by decreasing the generation of TBARS and ROS in mitochondrial and cytosolic fractions and maintaining liver function activities. A marked response was observed in the levels of both GSH and GSH-system enzymes in liver homogenates and mitochondrial fractions to BEGC. BEGC/ Nec-1 successfully regulated the inflammatory mediators (IL-β, TNF-α, HMGB1, and acHMGB1) and MPO levels. During APAP treatment, no caspase-3 or -8 activity was detected, and the level of fk18; M30 was higher than the levels of cck18; M65. Moreover, RIPK3 and MLKL levels were increased in the APAP group. These results suggested that necroptosis predominates during the APAP liver injury model. Interestingly, these necroptotic factors were significantly down-regulated by BEGC treatment. Both biochemical and histopathological findings were consistent with each other.

Conclusion

From all these findings, the hepatoprotective effect of BEGC could be due to the abundance of polyphenols identified by LC-MS/MS analysis, as well as the synergistic interactions of all contents.

Sting mutation attenuates acetaminophen-induced acute liver injury by limiting NLRP3 activation

Acetaminophen (N-acetyl-p-aminophenol; APAP), a widely used effective nonsteroidal anti-inflammatory drug, leads to acute liver injury at overdose worldwide. Evidence showed that the severity of liver injury associated with the subsequent involvement of inflammatory mediators and immune cells. The innate immune stimulator of interferon genes protein (STING) pathway was critical in modulating inflammation. Here, we show that STING was activated and inflammation was enhanced in the liver in APAP-overdosed C57BL/6J mice, and Sting mutation (Stinggt/gt) mice exhibited less liver damage. Multiplexing flow cytometry displayed that Sting mutation changed hepatic recruitment and replacement of macrophages/monocytes in APAP-overdosed mice, which was inclined to anti-inflammation. In addition, Sting mutation limited NLRP3 activation in the liver in APAP-overdosed mice, and inhibited the expression of inflammatory cytokines. Finally, MCC950, a potent and selective NLRP3 inhibitor, significantly ameliorated APAP-induced liver injury and inflammation. Besides, pretreatment of MCC950 in C57 mice resulted in changes of immune cells infiltration in the liver similar to Stinggt/gt mice. Our study revealed that STING played a crucial role in APAP-induced acute liver injury, possibly by maintaining liver immune cells homeostasis and inhibiting NLRP3 inflammasome activation, suggesting that inhibiting STING-NLRP3 pathway might be a potential therapeutic strategy for acute liver injury.

Lack of mitochondrial Cyp2E1 drives acetaminophen-induced ER stress-mediated apoptosis in mouse and human kidneys: Inhibition by 4-methylpyrazole but not N-acetylcysteine

Acetaminophen (APAP) overdose causes liver injury and acute liver failure, as well as acute kidney injury, which is not prevented by the clinical antidote N-acetyl-L-cysteine (NAC). The absence of therapeutics targeting APAP-induced nephrotoxicity is due to gaps in understanding the mechanisms of renal injury. APAP metabolism through Cyp2E1 drives cell death in both the liver and kidney. We demonstrate that Cyp2E1 is localized to the proximal tubular cells in mouse and human kidneys. Virtually all the Cyp2E1 in kidney cells is in the endoplasmic reticulum (ER), not in mitochondria. By contrast, hepatic Cyp2E1 is in both the ER and mitochondria of hepatocytes. Consistent with this subcellular localization, a dose of 600 mg/kg APAP in fasted C57BL/6J mice induced the formation of APAP protein adducts predominantly in mitochondria of hepatocytes, but the ER of the proximal tubular cells of the kidney. We found that reactive metabolite formation triggered ER stress-mediated activation of caspase-12 and apoptotic cell death in the kidney. While co-treatment with 4-methylpyrazole (4MP; fomepizole) or the caspase inhibitor Ac-DEVD-CHO prevented APAP-induced cleavage of procaspase-12 and apoptosis in the kidney, treatment with NAC had no effect. These mechanisms are clinically relevant because 4MP but not NAC also significantly attenuated APAP-induced apoptotic cell death in primary human kidney cells. We conclude that reactive metabolite formation by Cyp2E1 in the ER results in sustained ER stress that causes activation of procaspase-12, triggering apoptosis of proximal tubular cells, and that 4MP but not NAC may be an effective antidote against APAP-induced kidney injury.

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.

G-Quadruplex-Filtered Selective Ion-to-Ion Current Amplification for Non-Invasive Ion Monitoring in Real Time

Living cells efflux intracellular ions for maintaining cellular life, so intravital measurements of specific ion signals are of significant importance for studying cellular functions and pharmacokinetics. In this work, de novo synthesis of artificial K+ -selective membrane and its integration with polyelectrolyte hydrogel-based open-junction ionic diode (OJID) is demonstrated, achieving a real-time K+ -selective ion-to-ion current amplification in complex bioenvironments. By mimicking biological K+ channels and nerve impulse transmitters, in-line K+ -binding G-quartets are introduced across freestanding lipid bilayers by G-specific hexylation of monolithic G-quadruplex, and the pre-filtered K+ flow is directly converted to amplified ionic currents by the OJID with a fast response time at 100 ms intervals. By the synergistic combination of charge repulsion, sieving, and ion recognition, the synthetic membrane allows K+ transport exclusively without water leakage; it is 250× and 17× more permeable toward K+ than monovalent anion, Cl- , and polyatomic cation, N-methyl-d-glucamine+ , respectively. The molecular recognition-mediated ion channeling provides a 500% larger signal for K+ as compared to Li+ (0.6× smaller than K+ ) despite the same valence. Using the miniaturized device, non-invasive, direct, and real-time K+ efflux monitoring from living cell spheroids is achieved with minimal crosstalk, specifically in identifying osmotic shock-induced necrosis and drug-antidote dynamics.

Design and characterization of Lactotransferrin peptide-loaded dextran-docosahexaenoic acid nanoparticles: an immune modulator for hepatic damage

The primary objective of this research was to create injectable delivery formulations using Lactotransferrin (LTF) peptide-loaded dextran nanoparticles coated with docosahexaenoic acid. These nanoparticles, designated as LLDDNP, underwent a lyophilization process. The study encompassed a comprehensive investigation, including physicochemical characterization, in vivo assessment of biomarkers, and an examination of immune response through cytokine modulation. The zeta potential of LLDDNP was - 24.5 ± 12 mV, while their average particle size was 334.9 z.d.nm. The particles exhibited a conductivity of 2.10 mS/cm, while their mobility in the injectable dosage form was measured at - 3.65 µm cm/Vs. The scanning electron microscopy investigation, the lyophilization processes resulted in discrete particles forming particle aggregations. However, transmission electron microscopy analysis revealed that LLDDNP is spherical and smooth. The thermogram showed that about 95% of LLDDNP's weight was lost at 270 °C, indicating that the particles are extremely thermal stable. The XRD analysis of LLDDNP exhibited clear and distinctive peaks at 2θ angles, specifically at 9.6°, 20.3°, 21.1°, 22°, 24.6°, 25.2°, 36°, and 44.08°, providing compelling evidence of the crystalline nature of the particles. According to proton NMR studies, the proton dimension fingerprint region of LLDDNP ranges from 1.00 to 1.03 ppm. The in vitro release of LTF from LLDDNP was found to follow zero-order kinetics, with a commendable R2 value of 0.942, indicating a consistent and predictable release pattern over time. The in vivo investigation revealed a significant impact of hepatotoxicity on the elevation of various cytokines, including IL-1β, IL-6, IL-8R, TNF-α, IL-2, IL-4, IL-10, and IFN-γ. Additionally, the presence of hepatotoxicity led to an increase in apoptosis markers, namely caspase 3 and caspase 9, as well as elevated levels of liver biomarkers such as CRP, ALP, ALT, and AST. In contrast, the treatment with LLDDNP modulated the levels of all biomarkers, including cytokines level in the treatment group extremely high significant at p < 0.001.

Swertiamarin or heat-transformed products alleviated APAP-induced hepatotoxicity via modulation of apoptotic and Nrf-2/NF-κB pathways

OBJECTIVE

Swertiamarin (STM) belongs to iridoid class of compounds, and the heat-transformed products (HTPS) are produced by STM in the process of drug processing. The purpose of this study was to explore the protective effect and mechanism of STM or HTPS on acetaminophen (APAP)-induced hepatotoxicity.

METHODS

Mice and L-O2 cells were given APAP to establish the hepatotoxicity model in vivo and in vitro. The effects of STM or HTPS on oxidative stress, inflammation, and apoptosis induced by APAP were evaluated, with N-acetylcysteine (NAC) as a positive control.

RESULTS

STM or HTPS reduced the APAP-induced apoptosis of L-O2 cells and significantly alleviated the liver injury index induced by APAP (p < 0.01, 0.005) Interestingly, HTPS had better protective effect against APAP-induced hepatotoxicity than STM (p < 0.05). In addition STM or HTPS improved the histological abnormalities; inhibited lipid peroxidation and reduced the level of inflammatory mediators. They also activated the defense system of nuclear factor erythroid 2 related factor 2 (Nrf-2) and inhibited nuclear factor-κ B (NF-κB).

Loss of microRNA-21 protects against acetaminophen-induced hepatotoxicity in mice

Acetaminophen (APAP)-induced Acute Liver Failure (ALF) is recognized as the most common cause of ALF in Western societies. APAP-induced ALF is characterized by coagulopathy, hepatic encephalopathy, multi-organ failure, and death. MicroRNAs are small, non-coding RNAs that regulate gene expression at the post-transcriptional level. MicroRNA-21 (miR-21) is dynamically expressed in the liver and is involved in the pathophysiology of both acute and chronic liver injury models. We hypothesize that miR-21genetic ablation attenuates hepatotoxicity following acetaminophen intoxication. Eight-week old miR-21knockout (miR21KO) or wild-type (WT) C57BL/6N male mice were injected with acetaminophen (APAP, 300 mg/kg BW) or saline. Mice were sacrificed 6 or 24 h post-injection. MiR21KO mice presented attenuation of liver enzymes ALT, AST, LDH compared with WT mice 24 h post-APAP treatment. Moreover, miR21KO mice had decreased hepatic DNA fragmentation and necrosis than WT mice after 24 h of APAP treatment. APAP-treated miR21KO mice showed increased levels of cell cycle regulators CYCLIN D1 and PCNA, increased autophagy markers expression (Map1LC3a, Sqstm1) and protein (LC3AB II/I, p62), and an attenuation of the APAP-induced hypofibrinolytic state via (PAI-1) compared with WT mice 24 post-APAP treatment. MiR-21 inhibition could be a novel therapeutic approach to mitigate APAP-induced hepatotoxicity and enhance survival during the regenerative phase, particularly to alter regeneration, autophagy, and fibrinolysis. Specifically, miR-21 inhibition could be particularly useful when APAP intoxication is detected at its late stages and the only available therapy is minimally effective.

Confusoside, a dihydrochalcone glucoside, prevents acetaminophen-induced liver injury by modulating the Nrf2/NF-κB/caspase signaling pathway

Dihydrochalcones are important bioactive ingredients in plants. Anneslea fragrans is an edible and medicinal plant, and its leaves are rich in dihydrochalcones. Confusoside (CF) is the most abundant dihydrochalcone in A. fragrans leaves, which is traditionally used in the treatment of liver diseases. The aim of this study was to investigate the hepatoprotective effect of CF on acetaminophen (APAP)-induced hepatic injury in mice. CF could reduce the levels of AST, ALT, and LDH in the serum and enhance the antioxidant activity by activating the Nrf2 signaling pathway to increase the activities of antioxidant enzymes (SOD and CAT), and the GSH content but decrease the MDA accumulation in liver tissues. Immunofluorescence assay and western blotting analysis showed that CF can regulate Nrf2 into the cell nucleus, thereby promoting the expression of downstream antioxidant-related proteins, including NQO1 and HO-1. In addition, CF could inhibit the liver inflammatory response by suppressing the activation of the NF-κB signaling pathway to reduce the expressions of TNF-α, IL-1β, IL-6, and NO. Molecular docking results showed that there was good binding between the CF and Keap1-Nrf2 protein. Western blotting and TUNEL analysis also revealed CF-inhibited cell apoptosis-related protein expression (Bcl2 and caspase-3/9 proteins). Thus, the CF from A. fragrans leaves could be served as an alternative hepaprotective agent for the treatment and prevention of APAP-induced liver injury.

Molecular mechanism for the involvement of CYP2E1/NF-κB axis in bedaquiline-induced hepatotoxicity

Bedaquiline (BDQ) is a new class of anti-tubercular (anti-TB) drugs and is currently reserved for multiple drug resistance (MDR-TB). However, after receiving fast-track approval, its clinical studies demonstrate that its treatment is associated with hepatotoxicity and labeled as 'boxed warning' by the USFDA. No data is available on BDQ to understand the mechanism for drug-induced liver injury (DILI), a severe concern for therapeutic failure/unbearable tolerated toxicities leading to drug resistance. Therefore, we performed mechanistic studies to decipher the potential of BDQ at three dose levels (80 to 320 mg/kg) upon the repeated dose administration orally using a widely used mice model for TB. Results of BDQ treatment at the highest dose level showed that substantial increase of hepatic marker enzymes (SGPT and SGOT) in serum, oxidative stress marker levels (MDA and GSH) in hepatic tissue, and pro-inflammatory cytokine levels (TNF-α, IL-6, and IL-1β) in serum compared to control animals. Induction of liver injury situation was further evaluated by Western blotting for various protein expressions linked to oxidative stress (SOD, Nrf2, and Keap1), inflammation (NF-ĸB and IKKβ), apoptosis (BAX, Bcl-2, and Caspase-3) and drug metabolism enzymes (CYP3A4 and CYP2E1). The elevated plasma level of BDQ and its metabolite (N-desmethyl BDQ) were observed, corresponding to BDQ doses. Histopathological examination and SEM analysis of the liver tissue corroborate the above-mentioned findings. Overall results suggest that BDQ treatment-associated generation of its cytotoxic metabolite could act on CYP2E1/NF-kB pathway to aggravate the condition of oxidative stress, inflammation, and apoptosis in the liver and precipitating hepatotoxicity.

The Role of the NLRP3 Inflammasome and Programmed Cell Death in Acute Liver Injury

Acute liver injury (ALI) is a globally important public health issue that, when severe, rapidly progresses to acute liver failure, seriously compromising the life safety of patients. The pathogenesis of ALI is defined by massive cell death in the liver, which triggers a cascade of immune responses. Studies have shown that the aberrant activation of the nod-like receptor protein 3 (NLRP3) inflammasome plays an important role in various types of ALI and that the activation of the NLRP3 inflammasome causes various types of programmed cell death (PCD), and these cell death effectors can in turn regulate NLRP3 inflammasome activation. This indicates that NLRP3 inflammasome activation is inextricably linked to PCD. In this review, we summarize the role of NLRP3 inflammasome activation and PCD in various types of ALI (APAP, liver ischemia reperfusion, CCl₄, alcohol, Con A, and LPS/D-GalN induced ALI) and analyze the underlying mechanisms to provide references for future relevant studies.

Schinus terebinthifolia leaf lectin has central and peripheral antinociceptive action mediated by its carbohydrate-recognition domain and delta-opioid receptors

ETHNOPHARMACOLOGICAL RELEVANCE

Preparations from the bark and leaves of Schinus terebinthifolia Raddi are commonly used to treat toothaches and sore throats. The use of medications based on leaves of this plant has also been reported for pain of arthritis, toothache, and sore throat. Some evidence indicated that the lectin SteLL is an antinociceptive agent from leaves.

AIM OF THE STUDY

This study evaluated the antinociceptive activity of S. terebinthifolia leaf lectin (SteLL) using mouse models of peripheral and central nociception.

MATERIALS AND METHODS

Animals were treated intraperitoneally with SteLL at 1, 5, and 10 mg/kg. An acetic acid-induced abdominal writhing test was performed to screen for the antinociceptive effect of the lectin. Next, the formalin test was used to assess the effects of SteLL on neurogenic (first phase) and inflammatory (second phase) pain, as well as to investigate the involvement of the carbohydrate-recognition domain (CRD) of SteLL and opioid receptors in the antinociceptive effect. The tail immersion test was performed to assess the central antinociception. Additionally, a rotarod test was performed to evaluate the effects of lectin on motor coordination in mice.

RESULTS

SteLL reduced the number of acetic acid-induced writhes by 83.5-100.0%. In the first phase of the formalin test, SteLL reduced paw licking time by 49.4-50.5%, while in the second phase, SteLL reduced paw licking time by 80.5-82.6%. This antinociceptive effect was reversed by the previous incubation of the lectin with ovalbumin (indicating the possible involvement of the CRD) and by the administration of naloxone, a nonselective opioid receptor antagonist. When testing selective antagonists of opioid receptors (μ, δ, and κ), only naltrindole, a selective δ receptor antagonist, blocked the antinociceptive action of SteLL during the second phase of the formalin test. In the tail immersion test, SteLL (1, 5, and 10 mg/kg) administration reduced sensitivity to thermal stimulus, which was observed even after 2 h. SteLL (10 mg/kg) did not affect animal motor coordination in rotarod test when compared to the control group.

CONCLUSION

SteLL has peripheral and central analgesic action involving opioid receptor modulation without affecting the motor coordination of animals. These results provide new perspectives for developing analgesic agents using lectins.

Crosstalk between autophagy and the Keap1-Nrf2-ARE pathway regulates realgar-induced neurotoxicity

ETHNOPHARMACOLOGICAL RELEVANCE

Realgar, the main component of which is As₂S₂ or As₄S₄ (≥90%), is a traditional Chinese natural medicine that has been used to treat carbuncles, furuncles, snake and insect bites, abdominal pain caused by parasitic worms, and epilepsy in China for many years. Because realgar contains arsenic, chronic or excessive use of single-flavor realgar and realgar-containing Chinese patent medicine can lead to drug-induced arsenic poisoning, but the exact mechanism underlying its toxicity to the central nervous system is unclear.

AIM OF THE STUDY

The aim of this study was to clarify the mechanism of realgar-induced neurotoxicity and to investigate the effects of realgar on autophagy and the Keap1-Nrf2-ARE pathway.

MATERIALS AND METHODS

We used rats treated with the autophagy inhibitor 3-methyladenine (3-MA) or adeno-associated virus (AAV2/9-r-shRNA-Sqstm1, sh-p62) to investigate realgar-induced neurotoxicity and explore the specific relationship between autophagy and the Keap1-Nrf2-ARE pathway (the Nrf2 pathway) in the cerebral cortex. Molecular docking analysis was used to assess the interactions among the Nrf2, p62 and Keap1 proteins.

RESULTS

Our results showed that arsenic from realgar accumulated in the brain and blood to cause neuronal and synaptic damage, decrease exploratory behavior and spontaneous movement, and impair memory ability in rats. The mechanism may have involved realgar-mediated autophagy impairment and continuous activation of the Nrf2 pathway via the LC3-p62-Keap1-Nrf2 axis. However, because this activation of the Nrf2 pathway was not sufficient to counteract oxidative damage, apoptosis was aggravated in the cerebral cortex.

CONCLUSIONS

This study revealed that autophagy, the Nrf2 pathway, and apoptosis are involved in realgar-induced central nervous system toxicity and identified p62 as the hub of the LC3-p62-Keap1-Nrf2 axis in the regulation of autophagy, the Nrf2 pathway, and apoptosis.

Paeoniflorin Protects against Acetaminophen-Induced Liver Injury in Mice via JNK Signaling Pathway

BACKGROUND

Drug-induced liver injury (DILI), represented by acetaminophen (APAP), is a common cause of acute liver failure in clinics. Paeoniflorin (PF) has been proven to demonstrate a significant hepatoprotective effect. However, it is still unclear whether it can be a potential agent against hepatotoxicity induced by APAP. This study aimed to explore the preventive and therapeutic effects and mechanisms of PF on APAP-induced liver injury.

METHODS

Different doses of PF (50, 100, and 200 mg/kg) were given to C57BL/6 male mice for five consecutive days. After 12 h of APAP (250 mg/kg i.p.) treatment, blood and liver tissues were collected and isolated for detection.

RESULTS

The results showed that the therapeutic effects of PF on APAP mice were presented in the downregulation of the content of serum indices and significantly improved hepatic tissue edema and inflammatory infiltration. Meanwhile, PF reduces the level of the mitochondrial metabolic enzyme. Ulteriorly, it was found that PF has a downregulating effect on the apoptotic reaction and could inhibit the protein expression of CYP2E1/JNK signaling, which in turn reduces the damage of APAP.

CONCLUSION

Our findings showed that PF acted as a protective agent against APAP-induced hepatotoxicity by inhibiting JNK-related signals, suggesting a novel insight into treating APAP-induced liver injury.

Role of Pyroptosis in Acetaminophen-Induced Hepatotoxicity

Acetaminophen (APAP) is a widely used pain reliever that can cause liver injury or liver failure in response to an overdose. Understanding the mechanisms of APAP-induced cell death is critical for identifying new therapeutic targets. In this respect it was hypothesized that hepatocytes die by oncotic necrosis, apoptosis, necroptosis, ferroptosis and more recently pyroptosis. The latter cell death is characterized by caspase-dependent gasdermin cleavage into a C-terminal and an N-terminal fragment, which forms pores in the plasma membrane. The gasdermin pores can release potassium, interleukin-1β (IL-1β), IL-18, and other small molecules in a sublytic phase, which can be the main function of the pores in certain cell types such as inflammatory cells. Alternatively, the process can progress to full lysis of the cell (pyroptosis) with extensive cell contents release. This review discusses the experimental evidence for the involvement of pyroptosis in APAP hepatotoxicity as well as the arguments against pyroptosis as a relevant mechanism of APAP-induced cell death in hepatocytes. Based on the critical evaluation of the currently available literature and understanding of the pathophysiology, it can be concluded that pyroptotic cell death is unlikely to be a relevant contributor to APAP-induced liver injury.

Aronia melanocarpa polysaccharide ameliorates liver fibrosis through TGF-β1-mediated the activation of PI3K/AKT pathway and modulating gut microbiota

The purpose of this experiment was to investigate the anti-hepatic fibrosis effect of Aronia melanocarpa polysaccharide (AMP) on TAA-induced liver fibrosis mice and its mechanism, as well as the changes in intestinal flora in vivo. This was established with a dose of 200 mg/kg TAA (i.p) once every three days, lasting for eight weeks. Colchicine with 0.4 mg/kg, and AMP (200 and 400 mg/kg) were given by intragastric administration (i.g) after 28 days of intraperitoneal injection of TAA. AMP treatment significantly inhibited the activities of liver injury markers ALT and AST in serum. Histopathological staining demonstrated that AMP significantly reversed TAA-induced hepatocyte necrosis and collagen deposition. In addition, AMP treatment block TGF- β1/Smads pathway inhibited the production of ECM and alleviates liver fibrosis. Furthermore, AMP treatment enhanced the phosphorylation of PI3K/AKT and decreased the expression of its downstream apoptosis-related proteins in liver, thus effectively alleviating TAA-induced liver fibrosis. In addition, 16S rDNA gene sequencing analysis showed that AMP treatment helped restore the imbalanced ecosystem of gut microbes, increased the proportion of Bacteroidetes and Proteobacteria, and increased species richness. Above findings clearly show that AMP is an effective method for treating liver fibrosis, possibly by improving the gut microbiota.

Selenium-Modified Chitosan Induces HepG2 Cell Apoptosis and Differential Protein Analysis

INTRODUCTION

Chitosan is the product of the natural polysaccharide chitin removing part of the acetyl group, and exhibits various physiological and bioactive functions. Selenium modification has been proved to further enhance the chitosan bioactivities, and has been a hot topic recently.

METHODS

The present study aimed to investigate the potential inhibitory mechanism of selenium-modified chitosan (SMC) on HepG2 cells through MTT assays, morphological observation, annexin V-FITC/PI double staining, mitochondrial membrane potential determination, cell-cycle detection, Western blotting, and two-dimensional gel electrophoresis (2-DE).

RESULTS

The results indicated that SMC can induce HepG2 cell apoptosis with the cell cycle arrested in the S and G2/M phases and gradual disruption of mitochondrial membrane potential, reduce the expression of Bcl2, and improve the expression of Bax, cytochrome C, cleaved caspase 9, and cleaved caspase 3. Also, 2-DE results showed that tubulin α1 B chain, myosin regulatory light chain 12A, calmodulin, UPF0568 protein chromosome 14 open reading frame 166, and the cytochrome C oxidase subunit 5B of HepG2 cells were downregulated in HepG2 cells after SMC treatment.

DISCUSSION

These data suggested that HepG2 cells induced apoptosis after SMC treatment via blocking the cell cycle in the S and G2/M phases, which might be mediated through the mitochondrial apoptotic pathway. These results could be of benefit to future practical applications of SMC in the food and drug fields.

Long-Term Consumption of Food-Derived Chlorogenic Acid Protects Mice against Acetaminophen-Induced Hepatotoxicity via Promoting PINK1-Dependent Mitophagy and Inhibiting Apoptosis

Hepatotoxicity brought on by acetaminophen (APAP) is significantly impacted by mitochondrial dysfunction. Mitophagy, particularly PINK1-mediated mitophagy, maintains the stability of cell function by eliminating damaged mitochondria. One of the most prevalent dietary polyphenols, chlorogenic acid (CGA), has been shown to have hepatoprotective properties. It is yet unknown, nevertheless, whether its defense against hepatocyte apoptosis involves triggering PINK1-mediated mitophagy. In vitro and in vivo models of APAP-induced hepatotoxicity were established to observe CGA's effect and mechanism in preventing hepatotoxicity in the present study. Serum aminotransferase levels, mouse liver histology, and the survival rate of HepG2 cells and mice were also assessed. The outcomes showed that CGA could reduce the activities of serum enzymes such as alanine transaminase (ALT), aspartate transaminase (AST), and lactate dehydrogenase (LDH), and alleviate liver injury in mice. It could also significantly increase the cell viability of HepG2 cells and the 24-h survival rate of mice. TUNEL labeling and Western blotting were used to identify the hepatocyte apoptosis level. According to data, CGA could significantly reduce liver cell apoptosis in vivo. Additionally, Tom20 and LC3II colocalization in mitochondria may be facilitated by CGA. CGA considerably increased the levels of genes and proteins associated with mitophagy (PINK1, Parkin, LC3II/LC3I), while considerably decreasing the levels of p62 and Tom20, suggesting that it might activate PINK1/Parkin-mediated mitophagy in APAP-induced liver damage. Additionally, the protection of CGA was reduced when PINK1 was knocked down by siPINK1 in HepG2 cells, and it did not upregulate mitophagy-related proteins (PINK1, Parkin, LC3II/LC3I). In conclusion, our findings revealed that long-term consumption of food-derived CGA could prevent APAP hepatotoxicity via increasing PINK1-dependent mitophagy and inhibiting hepatocyte apoptosis.

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.

Probiotics: Evolving as a Potential Therapeutic Option against Acetaminophen-Induced Hepatotoxicity

Acetaminophen (APAP) is the most common prescription medicine around the world for the treatment of pain and fever and is considered to be a safe drug at its therapeutic dose. However, a single overdose or frequent use of APAP can cause severe acute liver injury. APAP hepatotoxicity is a prevalent cause of acute liver disease around the world and the lack of suitable treatment makes it a serious problem. In recent years, there has been a surge in interest in using probiotics and probiotic-derived products, known as postbiotics, as health and disease negotiators. A growing body of evidence revealed that they can be equally effective against APAP hepatotoxicity. Different probiotic bacteria were found to be pre-clinically effective against APAP hepatotoxicity. Different postbiotics have also shown exciting results in preclinical models of APAP hepatotoxicity. This review summarized the protective roles and mechanisms of the different probiotic bacteria and postbiotics against APAP hepatotoxicity, with critical discussion. A brief discussion on potential novel probiotics and postbiotics for oxidative liver injury was also included. This review was written in an attempt to pique the interest of researchers in developing a safe therapeutic option against oxidative liver damage using probiotics and/or postbiotics as dietary supplements.

Hepatoprotective Activity of Nelumbo nucifera Gaertn. Seedpod Extract Attenuated Acetaminophen-Induced Hepatotoxicity

The aim is to investigate the effect of lotus (Nelumbo nucifera Gaertn.) seedpod extract (LSE) on acetaminophen (APAP)-induced hepatotoxicity. LSE is rich in polyphenols and has potent antioxidant capacity. APAP is a commonly used analgesic, while APAP overdose is the main reason for drug toxicity in the liver. Until now, there has been no in vitro test of LSE in drug-induced hepatotoxicity responses. LSEs were used to evaluate the effect on APAP-induced cytotoxicity, ROS level, apoptotic rate, and molecule mechanisms. The co-treatment of APAP and LSEs elevated the survival rate and decreased intracellular ROS levels on HepG2 cells. LSEs treatment could significantly reduce APAP-induced HepG2 apoptosis assessed by DAPI and Annexin V/PI. The further molecule mechanisms indicated that LSEs decreased Fas/FasL binding and reduced Bax and tBid to restore mitochondrial structure and subsequently suppress downstream apoptosis cascade activation. These declines in COX-2, NF-κB, and iNOS levels were observed in co-treatment APAP and LSEs, which indicated that LSEs could ameliorate APAP-induced inflammation. LSE protected APAP-induced apoptosis by preventing extrinsic, intrinsic, and JNK-mediated pathways. In addition, the restoration of mitochondria and inflammatory suppression in LSEs treatments indicated that LSEs could decrease oxidative stress induced by toxic APAP. Therefore, LSE could be a novel therapeutic option for an antidote against overdose of APAP.

Cell-penetrating peptide-mediated delivery of therapeutic peptides/proteins to manage the diseases involving oxidative stress, inflammatory response and apoptosis

OBJECTIVES

Peptides and proteins represent great potential for modulating various cellular processes including oxidative stress, inflammatory response, apoptosis and consequently the treatment of related diseases. However, their therapeutic effects are limited by their inability to cross cellular barriers. Cell-penetrating peptides (CPPs), which can transport cargoes into the cell, could resolve this issue, as would be discussed in this review.

KEY FINDINGS

CPPs have been successfully exploited in vitro and in vivo for peptide/protein delivery to treat a wide range of diseases involving oxidative stress, inflammatory processes and apoptosis. Their in vivo applications are still limited due to some fundamental issues of CPPs, including nonspecificity, proteolytic instability, potential toxicity and immunogenicity.

SUMMARY

Totally, CPPs could potentially help to manage the diseases involving oxidative stress, inflammatory response and apoptosis by delivering peptides/proteins that could selectively reach proper intracellular targets. More studies to overcome related CPP limitations and confirm the efficacy and safety of this strategy are needed before their clinical usage.

The role of Iron in lipid peroxidation and protein nitration during acetaminophen-induced liver injury in mice

Acetaminophen (APAP) hepatotoxicity, a leading cause of acute liver failure in western countries, is characterized by mitochondrial superoxide and peroxynitrite formation. However, the role of iron, especially as facilitator of lipid peroxidation (LPO), has been controversial. Our aim was to determine the mechanism by which iron promotes cell death in this context. Fasted male C57BL/6J mice were treated with the iron chelator deferoxamine, minocycline (inhibitor of the mitochondrial calcium uniporter) or vehicle 1 h before 300 mg/kg APAP. Deferoxamine and minocycline significantly attenuated APAP-induced elevations in serum alanine amino transferase levels and hepatic necrosis at 6 h. This protection correlated with reduced 3-nitro-tyrosine protein adducts; LPO (malondialdehyde, 4-hydroxynonenal) was not detected. Activation of c-jun N-terminal kinase (JNK) was not affected but mitochondrial release of intermembrane proteins was reduced suggesting that the effect of iron was at the level of mitochondria. Co-treatment of APAP with FeSO4 exacerbated liver injury and protein nitration and triggered significant LPO; all effects were reversed by deferoxamine. Thus, after APAP overdose, iron imported into mitochondria facilitates protein nitration by peroxynitrite triggering mitochondrial dysfunction and cell death. Under these conditions, endogenous defense mechanisms largely prevent LPO. However, after iron overload, protein nitration and LPO contribute to APAP hepatotoxicity.

Methionine Cycle Rewiring by Targeting miR-873-5p Modulates Ammonia Metabolism to Protect the Liver from Acetaminophen

Drug-induced liver injury (DILI) development is commonly associated with acetaminophen (APAP) overdose, where glutathione scavenging leads to mitochondrial dysfunction and hepatocyte death. DILI is a severe disorder without effective late-stage treatment, since N-acetyl cysteine must be administered 8 h after overdose to be efficient. Ammonia homeostasis is altered during liver diseases and, during DILI, it is accompanied by decreased glycine N-methyltransferase (GNMT) expression and S-adenosylmethionine (AdoMet) levels that suggest a reduced methionine cycle. Anti-miR-873-5p treatment prevents cell death in primary hepatocytes and the appearance of necrotic areas in liver from APAP-administered mice. In our study, we demonstrate a GNMT and methionine cycle activity restoration by the anti-miR-873-5p that reduces mitochondrial dysfunction and oxidative stress. The lack of hyperammoniemia caused by the therapy results in a decreased urea cycle, enhancing the synthesis of polyamines from ornithine and AdoMet and thus impacting the observed recovery of mitochondria and hepatocyte proliferation for regeneration. In summary, anti-miR-873-5p appears to be an effective therapy against APAP-induced liver injury, where the restoration of GNMT and the methionine cycle may prevent mitochondrial dysfunction while activating hepatocyte proliferative response.

Diacerein counteracts acetaminophen-induced hepatotoxicity in mice via targeting NLRP3/caspase-1/IL-1β and IL-4/MCP-1 signaling pathways

The current study aims at repurposing the anti-arthritic drug diacerein (DCN) for the treatment of acetaminophen hepatotoxicity and investigating the potential underlying mechanisms. Mice were randomly divided into six groups receiving either no treatment (control group), 20 mg/kg DCN i.p, 400 mg/kg acetaminophen i.p, DCN 4 h before acetaminophen, DCN 2 h after acetaminophen, or 400 mg/kg N-acetylcysteine (NAC) i.p, 2 h after acetaminophen. Biomarkers of liver dysfunction, oxidative stress, and apoptosis were assessed. Hepatic necroinflammatory changes were evaluated along with hepatic expression of NF-κB and caspase-1. The levels of NLRP3, IL-1β, IL-4, MCP-1, and TNF-α in the liver, as well as CYP2E1 mRNA expression, were measured. Diacerein significantly reduced biomarkers of liver dysfunction, oxidative stress, hepatocyte necrosis, and infiltration of neutrophils and macrophages whether administered 4 h before or 2 h after acetaminophen. Further, the effects were comparable to those of NAC. Diacerein also counteracted acetaminophen-induced hepatocellular apoptosis by increasing Bcl-2 and decreasing Bax and caspase-3 expression levels. Moreover, DCN normalized hepatic TNF-α and significantly decreased NF-κB p65 expression. Accordingly, DCN can prevent or reverse acetaminophen hepatotoxicity in mice, suggesting potential utility as a repurposed drug for clinical treatment.

Pirfenidone attenuates acetaminophen-induced liver injury via suppressing c-Jun N-terminal kinase phosphorylation

Acetaminophen (APAP)-induced liver injury is the most frequent cause of acute liver failure in Western countries. Pirfenidone (PFD), an orally bioavailable pyridone derivative, is clinically used for idiopathic pulmonary fibrosis treatment and has antifibrotic, anti-inflammatory, and antioxidant effects. Here we examined the PFD effect on APAP-induced liver injury. In a murine model, APAP caused serum alanine aminotransferase elevation attenuated by PFD treatment. We performed terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling (TUNEL) and vital propidium iodide (PI) stainings simultaneously. APAP induced TUNEL-positive/PI-negative necrosis around the central vein and subsequent TUNEL-negative/PI-positive oncotic necrosis with hemorrhage and caused the upregulation of hypercoagulation- and hypoxia-associated gene expressions. PFD treatment suppressed these findings. Western blotting revealed PFD suppressed APAP-induced c-Jun N-terminal kinase (JNK) phosphorylation despite no effect on JNK phosphatase expressions. In conclusion, simultaneous TUNEL and vital PI staining is useful for discriminating APAP-induced necrosis from typical oncotic necrosis. Our results indicated that PFD attenuated APAP-induced liver injury by suppressing TUNEL-positive necrosis by directly blocking JNK phosphorylation. PFD is promising as a new option to prevent APAP-induced liver injury.

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

Acetaminophen (APAP) is a widely used analgesic and antipyretic drug, which is safe at therapeutic doses but can cause severe liver injury and even liver failure after overdoses. The mouse model of APAP hepatotoxicity recapitulates closely the human pathophysiology. As a result, this clinically relevant model is frequently used to study mechanisms of drug-induced liver injury and even more so to test potential therapeutic interventions. However, the complexity of the model requires a thorough understanding of the pathophysiology to obtain valid results and mechanistic information that is translatable to the clinic. However, many studies using this model are flawed, which jeopardizes the scientific and clinical relevance. The purpose of this review is to provide a framework of the model where mechanistically sound and clinically relevant data can be obtained. The discussion provides insight into the injury mechanisms and how to study it including the critical roles of drug metabolism, mitochondrial dysfunction, necrotic cell death, autophagy and the sterile inflammatory response. In addition, the most frequently made mistakes when using this model are discussed. Thus, considering these recommendations when studying APAP hepatotoxicity will facilitate the discovery of more clinically relevant interventions.

Evaluation of toxicological effects of organophosphorus pesticide metabolites on human HepG2 cells

Trichloropyridinol (TCP); 3, 5, 6-trichloro-2-pyridinol is the primary metabolites of the organophosphorus pesticide chlorpyrifos. It is more highly persistent than parent compounds in the environment and might represent serious risks to human health. In this study, we investigated the toxicological effects and mechanism of TCP on HepG2 cells. The results revealed that TCP induced DNA damage and apoptosis on HepG2 cells. Besides, up-regulating the expression level of Bax /Bcl-2, a reduction in mitochondrial membrane potential, caspase-9/-3 activation and the release of cytochrome-c are contributed to the toxicological effects of TCP on HepG2 cells. These data indicated that the cytotoxic effects of TCP might be associated with the activity of mitochondrial apoptotic pathways. In conclusion, the results demonstrated that TCP poses a potential threat to human health by inducing toxicological effects in the liver.

Niujiaodihuang Detoxify Decoction inhibits ferroptosis by enhancing glutathione synthesis in acute liver failure models

ETHNOPHARMACOLOGICAL RELEVANCE

Niujiaodihuang Detoxify Decoction (NDD) is an integrated traditional Chinese medicine prescription that has been used as a therapeutic agent for the treatment of acute liver failure (ALF). However, the mechanisms underlying its action remain unclear.

AIM OF THE STUDY

To determine the protective effect of NDD on D-galactosamine/lipopolysaccharide (D-GalN/LPS)-induced ALF and explore the underlying mechanisms.

MATERIALS AND METHODS

We characterized the NDD fingerprint by HPLC and established D-GalN/LPS-induced ALF models in Sprague-Dawley rats and LO2 cells. Next, we measured the protective and antiferroptotic effects of NDD in vivo and in vitro. To further investigate the molecular mechanisms underlying the effects of NDD, we performed metabolomic analysis of the liver tissue using LC-MS/MS.

RESULTS

Results of serum biochemical analysis, liver histopathology, and cell viability showed that NDD effectively relieved the liver injury. It reduced the accumulation of labile iron and alleviated lipid peroxidation by enhancing GPX4 activity. The mitochondrial morphology indicated that NDD exerted its hepatoprotective effect through an antiferroptotic activity. Metabolomic analysis showed that NDD treatment increased the levels of cysteine, decreased those of glutamate, and ameliorated the D-GalN/LPS-induced reduction in the levels of glutathione (GSH). The results for intracellular levels of reduced (GSH) and oxidized (GSSG) glutathione were consistent with those of metabolomic analysis.

CONCLUSION

Our findings indicate that NDD exerts hepatoprotective activity by evoking the reprogramming of GSH metabolism, and thereby, inhibiting ferroptosis.

Camellia japonica diminishes acetaminophen-induced acute liver failure by attenuating oxidative stress in mice

This experiment was to explore the possible defensive properties and potential molecular mechanisms of Camellia japonica (CJ) against APAP-stimulated acute liver failure (ALF) in mice. In this study, we investigated the effects of CJ on APAP-induced hepatotoxicity. Mice were orally treated with CJ before or after challenge with APAP. Both pretreatment and post-treatment with CJ attenuated APAP-induced hepatotoxicity, as confirmed by significantly reduced serum toxicity biomarkers and improved hepatic pathological damage. Pretreatment with CJ drastically decreased the rise of hepatic inflammatory cytokines levels and weakened neutrophil infiltration. Furthermore, pretreatment with CJ dramatically decreased the levels of hepatic oxidative stress markers such as hepatic malondialdehyde (MDA) and 4-Hydroxynonenal (4-HNE) expression and rescued the reduced hepatic level of GSH caused by APAP overdose. Additionally, CJ pretreatment markedly attenuated cyclooxygenase-2 (COX-2) activation, transcription factor nuclear factor-kappa B (NF-κB) phosphorylation, c-Jun-N-terminal kinase (JNK) phosphorylation, and activated AMP-activated protein kinase (AMPK) signaling pathway in the liver. The present study thus reveals that CJ attenuated APAP-induced ALF by inhibiting COX-2 activation, NF-κB, and JNK phosphorylation and activating the AMPK signaling pathway.

Redefining IL11 as a regeneration-limiting hepatotoxin and therapeutic target in acetaminophen-induced liver injury

Acetaminophen (N-acetyl-p-aminophenol; APAP) toxicity is a common cause of liver damage. In the mouse model of APAP-induced liver injury (AILI), interleukin 11 (IL11) is highly up-regulated and administration of recombinant human IL11 (rhIL11) has been shown to be protective. Here, we demonstrate that the beneficial effect of rhIL11 in the mouse model of AILI is due to its inhibition of endogenous mouse IL11 activity. Our results show that species-matched IL11 behaves like a hepatotoxin. IL11 secreted from APAP-damaged human and mouse hepatocytes triggered an autocrine loop of NADPH oxidase 4 (NOX4)-dependent cell death, which occurred downstream of APAP-initiated mitochondrial dysfunction. Hepatocyte-specific deletion of Il11 receptor subunit alpha chain 1 (Il11ra1) in adult mice protected against AILI despite normal APAP metabolism and glutathione (GSH) depletion. Mice with germline deletion of Il11 were also protected from AILI, and deletion of Il1ra1 or Il11 was associated with reduced c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) activation and quickly restored GSH concentrations. Administration of a neutralizing IL11RA antibody reduced AILI in mice across genetic backgrounds and promoted survival when administered up to 10 hours after APAP. Inhibition of IL11 signaling was associated with the up-regulation of markers of liver regenerations: cyclins and proliferating cell nuclear antigen (PCNA) as well as with phosphorylation of retinoblastoma protein (RB) 24 hours after AILI. Our data suggest that species-matched IL11 is a hepatotoxin and that IL11 signaling might be an effective therapeutic target for APAP-induced liver damage.

Ferroptosis and Acetaminophen Hepatotoxicity: Are We Going Down Another Rabbit Hole?

Acetaminophen (APAP) hepatotoxicity is the most frequent cause of acute liver failure in the US. The mechanisms of APAP-induced liver injury have been under extensive investigations for decades, and many key events of this necrotic cell death are known today. Initially, two opposing hypotheses for cell death were proposed: reactive metabolite and protein adduct formation versus reactive oxygen and lipid peroxidation (LPO). In the end, both mechanisms were reconciled, and it is now generally accepted that the toxicity starts with formation of reactive metabolites that, after glutathione depletion, bind to cellular proteins, especially on mitochondria. This results in a mitochondrial oxidant stress, which requires amplification through a mitogen-activated protein kinase cascade, leading ultimately to enough reactive oxygen and peroxynitrite formation to trigger the mitochondrial membrane permeability transition and cell death. However, the earlier rejected LPO hypothesis seems to make a comeback recently under a different name: ferroptosis. Therefore, the objective of this review was to critically evaluate the available information about intracellular signaling mechanisms of APAP-induced cell death and those of ferroptosis. Under pathophysiologically relevant conditions, there is no evidence for quantitatively enough LPO to cause cell death, and thus APAP hepatotoxicity is not caused by ferroptosis. However, the role of mitochondria-localized minor LPO remains to be further investigated.

A mouse monoclonal antibody against influenza C virus attenuates acetaminophen-induced liver injury in mice

Molecular mimicry is one of the main processes for producing autoantibodies during infections. Although some autoantibodies are associated with autoimmune diseases, the functions of many autoantibodies remain unknown. Previously, we reported that S16, a mouse (BALB/c) monoclonal antibody against the hemagglutinin-esterase fusion glycoprotein of influenza C virus, recognizes host proteins in some species of animals, but we could not succeed in identifying the proteins. In the present study, we found that S16 cross-reacted with acetyl-CoA acyltransferase 2 (ACAA2), which is expressed in the livers of BALB/c mice. ACAA2 was released into the serum after acetaminophen (APAP) administration, and its serum level correlated with serum alanine aminotransferase (ALT) activity. Furthermore, we observed that S16 injected into mice with APAP-induced hepatic injury prompted the formation of an immune complex between S16 and ACAA2 in the serum. The levels of serum ALT (p < 0.01) and necrotic areas in the liver (p < 0.01) were reduced in the S16-injected mice. These results suggest that S16 may have a mitigation function in response to APAP-induced hepatotoxicity. This study shows the therapeutic function of an autoantibody and suggests that an antibody against extracellular ACAA2 might be a candidate for treating APAP-induced hepatic injury.

Survival and malformations rates, oxidative status in early life stages of Cyprinus carpio due to exposure to environmentally realistic concentrations of paracetamol

Paracetamol (PCM) is among the most consumed analgesic and antipyretic drugs worldwide. Due to its high consumption, this drug has been reported ubiquitously on different water bodies, posing a real threat to aquatic organisms. Until now, several studies have pointed out that PCM may induce oxidative stress, histological damage and developmental disorders on different aquatic species. Nonetheless, there is still a huge knowledge gap about the toxic effects that PCM may induce in species of commercial interest such as the common carp Cyprinus carpio. The aim of this study was to evaluate survival and malformation rates induced by PCM (0.5 μg/L - 3.5 μg/L) in early life stages of common carp. Furthermore, oxidative stress biomarkers were evaluated at 72 and 96 h post fecundation. PCM reduced the survival rate of the embryos of up to 90%, as concentration increased. LC₅₀ and EC_50m were 1.29 μg/L and 2.84 μg/L, respectively. Biomarkers of cellular oxidation and antioxidant enzymes were modified in a concentration-dependent way with respect to the control group (p < 0.05). The main developmental alterations observed were lordosis, scoliosis, craniofacial malformations, hypopigmentation, growth retardation, pericardial edema and rachyschisis. These data indicate that environmentally realistic concentrations of PCM could be hazardous and affects the development in early stages of C. carpio. Moreover, our findings also indicate that C. carpio embryos may be a useful in vivo model to evaluate embryonic and teratogenic effects of drugs such as PCM.

Hepatoprotective effect of forsythiaside a against acetaminophen-induced liver injury in zebrafish: Coupling network pharmacology with biochemical pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Forsythiae Fructus, the dried fruit of Forsythia suspensa (Thunb.) Vahl, is a commonly used traditional Chinese medicine and possesses various pharmacological activities, including anti-inflammation, anti-oxidant and liver protection.

AIM OF THE STUDY

Although acetaminophen (APAP) has been frequently used for its antipyretic and analgesic effects, it leads to liver injury at an overdose or long-term medication. Forsythiaside A (FA), the principal active component of Forsythiae Fructus, exerts prominent antioxidant, anti-inflammatory and hepatoprotective effects. However, the protective property and underlying mechanism of FA against APAP challenge have not yet been elucidated. Therefore, we aimed to explore the hepatoprotective effect and action mechanism of FA against APAP-induced liver injury in zebrafish.

MATERIALS AND METHODS

In this study, liver-specific transgenic zebrafish larvae (lfabp: EGFP) were used to investigate the protective effect of FA against overdose APAP exposure. The liver phenotype, morphological and biochemical assessments were carried out to evaluate the hepatoprotective effect of FA. Network pharmacology and molecular docking study were conducted to analyze the potential targets of FA in the treatment of APAP-induced liver injury. Finally, the mechanism of action was verified by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR).

RESULTS

The liver phenotype, morphological and biochemical assessments indicated that FA could mitigate APAP-triggered liver injury. Network pharmacology and molecular docking analysis indicated that the protective effect of FA might be related to the regulation of targets tumor necrosis factor (TNF), matrix metallopeptidase 9 (MMP9), matrix metallopeptidase 2 (MMP2), and phosphatidylinositol 3-kinase (PI3K). PCR results confirmed that FA could reverse the progressive alterations of genes involving in extracellular matrix remolding and PI3K/AKT-mediated apoptosis signaling pathway.

CONCLUSIONS

Our results indicated that FA could mitigate APAP-induced liver injury through modulating the remolding of extracellular matrix and PI3K/AKT-mediated apoptosis.

Kaempferol from Penthorum chinense Pursh suppresses HMGB1/TLR4/NF-κB signaling and NLRP3 inflammasome activation in acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) is one of the safest and most effective over-the-counter (OTC) analgesics and antipyretics, but excessive doses of APAP will induce hepatotoxicity with high morbidity and mortality worldwide. Kaempferol (KA), a flavonoid compound derived from the medicinal and edible plant of Penthorum chinense Pursh, has been reported to exert a profound anti-inflammatory and antioxidant activity. In this study, we explored the protective effect and novel mechanism of KA against APAP-induced hepatotoxicity. The results revealed that KA pretreatment significantly reduced the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), relieved hepatocellular damage and apoptosis, attenuated the exhaustion of glutathione (GSH) and accumulation of malondialdehyde (MDA), increased the expression of antioxidative enzymes (e.g., heme oxygenase 1 (HO-1) and NADPH quinone oxidoreductase 1 (NQO1)), and thus restrained APAP-induced oxidative damage in the liver. KA suppressed the expression of NLRP3 and reduced the levels of pro-inflammatory factors, including interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). Moreover, KA remarkably inhibited high-mobility group box 1 (HMGB1) and toll-like receptor 4 (TLR4) expression as well as nuclear factor kappa-B (NF-κB) activation for liver protection against APAP-induced inflammatory responses and apoptosis. Taken together, our findings suggested that KA could effectively protect hepatocytes from APAP hepatotoxicity through the up-regulation of HO-1 and NQO1 expression, the down-regulation of NLRP3 expression, and the inhibition of the HMGB1/TLR4/NF-κB signaling pathway.

Biomarkers of drug-induced liver injury: a mechanistic perspective through acetaminophen hepatotoxicity

Introduction: Liver injury induced by drugs is a serious clinical problem. Many circulating biomarkers for identifying and predicting drug-induced liver injury (DILI) have been proposed.Areas covered: Biomarkers are mainly predicated on the mechanistic understanding of the underlying DILI, often in the context of acetaminophen overdose. New panels of biomarkers have emerged that are related to recovery/regeneration rather than injury following DILI. We explore the clinical relevance and limitations of these new biomarkers including recent controversies. Extracellular vesicles have also emerged as a promising vector of biomarkers, although the biological role for EVs may limit their clinical usefulness. New technological approaches for biomarker discovery are also explored.Expert opinion: Recent clinical studies have validated the efficacy of some of these new biomarkers, cytokeratin-18, macrophage colony-stimulating factor receptor, and osteopontin for DILI prognosis. Low prevalence of DILI is an inherent limitation to DILI biomarker development. Furthering mechanistic understanding of DILI and leveraging technological advances (e.g. machine learning/omics) is necessary to improve upon the newest generation of biomarkers. The integration of omics approaches with machine learning has led to novel insights in cancer research and DILI research is poised to leverage these technologies for biomarker discovery and development.

Mitochondria-Mediated Apoptosis Induced Testicular Dysfunction in Diabetic Rats: Ameliorative Effect of Resveratrol

The molecular mechanism underlying diabetes-induced testicular damage has not been thoroughly elucidated. The present study was conducted to elucidate the role of mitochondria-mediated apoptosis in diabetes-induced testicular dysfunction in rats and to explore the ameliorative effect of resveratrol. Diabetes suppressed sperm count, motility, and viability and increased sperm abnormalities. It decreased serum testosterone level and testicular mitochondrial membrane potential. The level of Bax and caspase-3 and -9 activities were increased in the testicular cytosol, while the level of Bcl-2 was decreased. Diabetes increased the Bax/Bcl-2 ratio. The cytochrome C level was decreased in the mitochondrial fraction, while its level was increased in the cytosol, a result that was supported by the immunohistochemistry of cytochrome C. Diabetes resulted in deleterious alterations in the architecture of testicular tissue, suppressed antioxidant enzymes, and increased H2O2 production, protein carbonyl content, and lipid peroxidation. However, administration of resveratrol at a dose of 50 mg kg/day for 4 successive weeks post diabetic induction, successfully ameliorated the testicular dysfunction. In conclusion, these findings strongly reveal that diabetes induces testicular damage, at least in part, by inducing mitochondrial-mediated apoptosis and oxidative stress. Administration of resveratrol to diabetic rats improves the diabetes-induced testicular damage. These impacts could be mediated through resveratrol antioxidant and anti-apoptotic effects.

Chemical Characterization and Hepatoprotective Effects of a Standardized Triterpenoid-Enriched Guava Leaf Extract

Nutraceutical/pharmaceutical agents capable of maintaining redox and inflammation homeostasis are considered as candidates for the prevention and/or treatment of liver diseases. Psidium guajava (commonly known as guava) leaf is a commercially available functional food that has been reported to possess hepatoprotective property. However, the hepatoprotective constituents in guava leaf are not known. In the current study, a standardized triterpenoid-enriched extract of guava leaves (TGL) was developed. A new ursolic acid derivative, namely 2α,3β,6β,23,30-pentahydroxyurs-11,13(18)-dien-28,20β-olide (1), and 23 known triterpenoids were isolated and identified from TGL. The hepatoprotective effects of TGL were evaluated through a model using acetaminophen (APAP)-exposed C57BL/6 male mice. Pretreatment of TGL (75 and 150 mg/kg) restored the mice hepatic architecture, improved the serum ALT and AST levels, and reduced the hepatic ROS and MDA contents. Further molecular mechanistic study revealed that TGL modulated Nrf2 and MAPK signaling pathways to alleviate APAP-induced oxidative and inflammatory stress in liver. In addition, the new compound 1 from TGL showed protective effects against APAP-induced cytotoxicity via activation of the Nrf2 pathway in HepG2 cells. Overall, this is the first report on the hepatoprotective effects of a standardized triterpenoid-enriched extract of guava leaves, which supports its potential nutraceutical application in liver disease management.

Pyroptosis: mechanisms and diseases

Currently, pyroptosis has received more and more attention because of its association with innate immunity and disease. The research scope of pyroptosis has expanded with the discovery of the gasdermin family. A great deal of evidence shows that pyroptosis can affect the development of tumors. The relationship between pyroptosis and tumors is diverse in different tissues and genetic backgrounds. In this review, we provide basic knowledge of pyroptosis, explain the relationship between pyroptosis and tumors, and focus on the significance of pyroptosis in tumor treatment. In addition, we further summarize the possibility of pyroptosis as a potential tumor treatment strategy and describe the side effects of radiotherapy and chemotherapy caused by pyroptosis. In brief, pyroptosis is a double-edged sword for tumors. The rational use of this dual effect will help us further explore the formation and development of tumors, and provide ideas for patients to develop new drugs based on pyroptosis.

Loss of BOK Has a Minor Impact on Acetaminophen Overdose-Induced Liver Damage in Mice

Acetaminophen (APAP) is one of the most commonly used analgesic and anti-pyretic drugs, and APAP intoxication is one of the main reasons for liver transplantation following liver failure in the Western world. While APAP poisoning ultimately leads to liver necrosis, various programmed cell death modalities have been implicated, including ER stress-triggered apoptosis. The BCL-2 family member BOK (BCL-2-related ovarian killer) has been described to modulate the unfolded protein response and to promote chemical-induced liver injury. We therefore investigated the impact of the loss of BOK following APAP overdosing in mice. Surprisingly, we observed sex-dependent differences in the activation of the unfolded protein response (UPR) in both wildtype (WT) and Bok^-/- mice, with increased activation of JNK in females compared with males. Loss of BOK led to a decrease in JNK activation and a reduced percentage of centrilobular necrosis in both sexes after APAP treatment; however, this protection was more pronounced in Bok^-/- females. Nevertheless, serum ALT and AST levels of Bok^-/- and WT mice were comparable, indicating that there was no major difference in the overall outcome of liver injury. We conclude that after APAP overdosing, loss of BOK affects initiating signaling steps linked to ER stress, but has a more minor impact on the outcome of liver necrosis. Furthermore, we observed sex-dependent differences that might be worthwhile to investigate.

A review on the protective effects of naringenin against natural and chemical toxic agents

Naringenin (NRG), as a flavanone from flavonoids family, is widely found in grapefruit, lemon tomato, and Citrus fruits. NRG has shown strong anti-inflammatory and antioxidant activities in body organs via mechanisms such as enhancement of glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity, but reduction of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malondialdehyde (MDA). Furthermore, NRG anti-apoptotic potential was indicated to be mediated by regulating B-cell lymphoma (Bcl-2), Bcl-2-associated X protein (Bax) and caspase3/9. Overall, these properties make NRG a highly fascinating compound with beneficial pharmacological effects. Based on the literature, NRG-induced protective effects against toxicities produced by natural toxins, pharmaceuticals, heavy metals, and environmental chemicals, were mainly mediated via suppression of lipid peroxidation, oxidative stress (through boosting the antioxidant arsenal), and inflammatory factors (e.g., TNF-α, interleukin [IL]-6, IL-10, and IL-12), and activation of PI3K/Akt and MAPK survival signaling pathways. Despite considerable body of evidence on protective properties of NRG against a variety of toxic compounds, more well-designed experimental studies and particularly, clinical trials are required before reaching a concrete conclusion. The present review discusses how NRG protects against the above-noted toxic compounds.

Assessment of the biochemical pathways for acetaminophen toxicity: Implications for its carcinogenic hazard potential

In 2019 California's Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. In parallel with this review, herein we evaluated the mechanistic data related to the steps and timing of cellular events following therapeutic recommended (≤4 g/day) and higher doses of acetaminophen that may cause hepatotoxicity to evaluate whether these changes indicate that acetaminophen is a carcinogenic hazard. At therapeutic recommended doses, acetaminophen forms limited amounts of N-acetyl-p-benzoquinone-imine (NAPQI) without adverse cellular effects. Following overdoses of acetaminophen, there is potential for more extensive formation of NAPQI and depletion of glutathione, which may result in mitochondrial dysfunction and DNA damage, but only at doses that result in cell death - thus making it implausible for acetaminophen to induce the kind of stable, genetic damage in the nucleus indicative of a genotoxic or carcinogenic hazard in humans. The collective data demonstrate a lack of a plausible mechanism related to carcinogenicity and are consistent with rodent cancer bioassays, epidemiological results reviewed in companion manuscripts in this issue, as well as conclusions of multiple international health authorities.

Antioxidant and Anti-Inflammatory Effects of Anacardium occidentale L. and Anacardium microcarpum D. Extracts on the Liver of IL-10 Knockout Mice

Background

The Anacardium occidentale L. (cashew) and Anacardium microcarpum D. (cajuí) are plants commonly found in Brazil. They present phytochemical compounds with antioxidant and anti-inflammatory action. Therefore, the objective of this study was to analyze the antioxidant and anti-inflammatory activities of ethanolic extracts from leaves of A. occidentale and A. microcarpum and its effect on the hepatic tissue in experimental knockout models after they received Paracetamol®.

Methods

Ethanol extracts from A. occidentale and A. microcarpum leaves were prepared. Total phenolics were determined by Folin–Ciocalteau reagent, and flavonoids are based on the complexation reaction with the aluminum metal, forming a colored complex. Fingerprint HPLC was performed to detect phenolic compounds. Knockout IL-10 mice randomly divided into six groups were used and received the following treatments: G1, only water; G2, A. occidentale extract; G3, A. microcarpum extract; G4, Paracetamol®; G5, Paracetamol® + A. occidentale extract (400 mg/kg); G6, Paracetamol® + A. microcarpum extract (400 mg/kg). Biochemical parameters of the blood and differential count of leukocytes were done. Oxidative markers and histopathological analyses were performed on their liver tissue.

Results

Phenolic compounds and total flavonoids were detected in both two extracts analyzed. The HPLC fingerprint detected phenolic acid, gallic acid, and catechin flavonoid in the two extracts. Histopathological analyses of the hepatic tissue permitted evaluation of nuclear increase, sinusoid congestion, and inflammatory infiltrate. A. microcarpum presented more antioxidant activity increasing antioxidant enzyme levels and reducing TBARS and carbonyl protein when compared to the other treatments after exposure to Paracetamol®. Histopathological analyses showed a decrease in the inflammatory infiltrate after treatment with extracts.

Conclusion

Our findings indicate that both extracts, especially A. microcarpum, can reduce hepatic damage in knockout mice exposed to paracetamol, indicating the curative power of these extracts reducing lipid peroxidation and in the morphofunctional damage to the liver parenchyma.