Mechanisms of acetaminophen-induced liver injury and its implications for therapeutic interventions

Absence of IκBβ/NFκB signaling does not attenuate acetaminophen-induced hepatic injury

Acetaminophen (N-acetyl-p-aminophenol [APAP]) toxicity is a common cause of acute liver failure. Innate immune signaling and specifically NFκB activation play a complex role in mediating the hepatic response to toxic APAP exposures. While inflammatory innate immune responses contribute to APAP-induced injury, these same pathways play a role in regeneration and repair. Previous studies have shown that attenuating IκBβ/NFκB signaling downstream of TLR4 activation can limit injury, but whether this pathway contributes to APAP-induced hepatic injury is unknown. We hypothesized that the absence of IκBβ/NFκB signaling in the setting of toxic APAP exposure would attenuate APAP-induced hepatic injury. To test this, we exposed adult male WT and IκBβ-/- mice to APAP (280 mg/kg, IP) and evaluated liver histology at early (2-24 hr) and late (48-72 hr) time points. Furthermore, we interrogated the hepatic expression of NFκB inflammatory (Cxcl1, Tnf, Il1b, Il6, Ptgs2, and Ccl2), anti-inflammatory (Il10, Tnfaip3, and Nfkbia), and Nrf2/antioxidant (Gclc, Hmox, and Nqo1) target genes previously demonstrated to play a role in APAP-induced injury. Conflicting with our hypothesis, we found that hepatic injury was similar in WT and IκBβ-/- mice. Acutely, the induced expression of some target genes was similar in WT and IκBβ-/- mice (Tnfaip3, Nfkbia, and Gclc), while others were either not induced (Cxcl1, Tnf, Ptgs2, and Il10) or significantly attenuated (Ccl2) in IκBβ-/- mice. At later time points, APAP-induced hepatic expression of Il1b, Il6, and Gclc was significantly attenuated in IκBβ-/- mice. Based on these findings, the therapeutic potential of targeting IκBβ/NFκB signaling to treat toxic APAP-induced hepatic injury is likely limited.

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

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

Nanozymes for Regenerative Medicine

Nanozymes refer to nanomaterials that catalyze enzyme substrates into products under relevant physiological conditions following enzyme kinetics. Compared to natural enzymes, nanozymes possess the characteristics of higher stability, easier preparation, and lower cost. Importantly, nanozymes possess the magnetic, fluorescent, and electrical properties of nanomaterials, making them promising replacements for natural enzymes in industrial, biological, and medical fields. On account of the rapid development of nanozymes recently, their application potentials in regeneration medicine are gradually being explored. To highlight the achievements in the regeneration medicine field, this review summarizes the catalytic mechanism of four types of representative nanozymes. Then, the strategies to improve the biocompatibility of nanozymes are discussed. Importantly, this review covers the recent advances in nanozymes in tissue regeneration medicine including wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment. In addition, challenges and prospects of nanozyme researches in regeneration medicine are summarized.

Loss of Sam50 in hepatocytes induces cardiolipin-dependent mitochondrial membrane remodeling to trigger mtDNA release and liver injury

BACKGROUND AND AIMS

Sam50, a key component of the sorting and assembly machinery (SAM) complex, is also involved in bridging mitochondrial outer-membrane and inner-membrane contacts. However, the physiological and pathological functions of Sam50 remain largely unknown.

APPROACH AND RESULTS

Here we show that Sam50 interacts with MICOS (mitochondrial contact site and cristae organizing system) and ATAD3 (ATPase family AAA domain-containing protein 3) to form the Sam50-MICOS-ATAD3-mtDNA axis, which maintains mtDNA stability. Loss of Sam50 causes mitochondrial DNA (mtDNA) aggregation. Furthermore, Sam50 cooperates with Mic60 to bind to cardiolipin, maintaining the integrity of mitochondrial membranes. Sam50 depletion leads to cardiolipin externalization, which causes mitochondrial outer-membrane and inner-membrane (including crista membrane) remodeling, triggering Bax mitochondrial recruitment, mtDNA aggregation, and release. Physiologically, acetaminophen (an effective antipyretic and analgesic)-caused Sam50 reduction or Sam50 liver-specific knockout induces mtDNA release, leading to activation of the cGAS-STING pathway and liver inflammation in mice. Moreover, exogenous expression of Sam50 remarkably attenuates APAP-induced liver hepatoxicity.

CONCLUSIONS

Our findings uncover the critical role of Sam50 in maintaining mitochondrial membrane integrity and mtDNA stability in hepatocytes and reveal that Sam50 depletion-induced cardiolipin externalization is a signal of mtDNA release and controls mtDNA-dependent innate immunity.

Targeting PARK7 Improves Acetaminophen-Induced Acute Liver Injury by Orchestrating Mitochondrial Quality Control and Metabolic Reprogramming

Mitochondrial dysfunction and oxidative stress are considered to be key events in acetaminophen (APAP)-induced acute liver injury. Mitochondrial quality control, including mitophagy and mitochondrial synthesis, can restore mitochondrial homeostasis and thus protect the liver. The role of PARK7, a mitochondrial stress protein, in regulating mitochondrial quality control in APAP-induced hepatotoxicity is unclear. In this study, L02 cells, AML12 cells and C57/BL6 mice were each used to establish models of APAP-induced acute liver injury. PARK7 was silenced in vitro by lentiviral transfection and knocked down in vivo by AAV adeno-associated virus. Changes in cell viability, apoptosis, reactive oxygen species (ROS) level, serum enzyme activity and pathological features were evaluated after APAP treatment. Western blotting, real-time PCR, immunofluorescence, electron microscopy and Seahorse assays were used to detect changes in key indicators of mitochondrial quality control. The results showed that APAP treatment decreased cell viability and increased the apoptosis rate, ROS levels, serum enzyme activity, pathological damage and PARK7 expression. PARK7 silencing or knockdown ameliorated APAP-induced damage to the cells and liver. Furthermore, PARK7 silencing enhanced mitophagy, increased mitochondrial synthesis, and led to a switch from oxidative phosphorylation to glycolysis. Taken together, these results suggest that PARK7 is involved in APAP-induced acute liver injury by regulating mitochondrial quality control and metabolic reprogramming. Therefore, PARK7 may be a promising therapeutic target for APAP-induced liver injury.

Naringin regulates mitochondrial dynamics to protect against acetaminophen-induced hepatotoxicity by activating the AMPK/Nrf2 signaling pathway in vitro

Naringin (Nar) has been reported to exert potential hepatoprotective effects against acetaminophen (APAP)-induced injury. Mitochondrial dysfunction plays an important role in APAP-induced liver injury. However, the protective mechanism of Nar against mitochondrial damage has not been elucidated. Therefore, the aim of this study was to investigate the hepatoprotective effects of Nar against APAP and the possible mechanisms of actions. Primary rat hepatocytes and HepG2 cells were utilized to establish an in vitro model of APAP-induced hepatotoxicity. The effect of APAP and Nar on cell viability was evaluated by a CCK8 assay and detection of the concentrations of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase. The cellular concentrations of biomarkers of oxidative stress were measured by ELISA. The mRNA expression levels of APAP-related phase II enzymes were determined by real-time PCR. The protein levels of Nrf2, phospho (p)-AMPK/AMPK, and biomarkers of mitochondrial dynamics were determined by western blot analysis. The mitochondrial membrane potential (MMP) was measured by high-content analysis and confocal microscopy. JC-1 staining was performed to evaluate mitochondrial depolarization. Nar pretreatment notably prevented the marked APAP-induced hepatocyte injury, increases in oxidative stress marker expression, reductions in the expression of phase II enzymes, significant loss of MMP, mitochondrial depolarization, and mitochondrial fission in vitro. In conclusion, Nar alleviated APAP-induced hepatocyte and mitochondrial injury by activating the AMPK/Nrf2 pathway to reduce oxidative stress in vitro. Applying Nar for the treatment of APAP-induced liver injury might be promising.

Epigallocatechin-3-gallate Mo nanoparticles (EGM NPs) efficiently treat liver injury by strongly reducing oxidative stress, inflammation and endoplasmic reticulum stress

Drug-induced liver injury (DILI) is a serious clinical disease associated with reactive oxygen species (ROS) burst and subsequent inflammatory responses. However, traditional treatments were limited by low efficacy and serious side effects due to the special liver structure. Here, we developed a molybdenum (Mo)-based nanoparticles, EGM NPs, after overall consideration of the pathophysiology of DILI and the advantages of nanodrugs. It demonstrated that EGM NPs treated acetaminophen (APAP)-induced DILI by scavenging ROS and inhibiting inflammation. EGM NPs effectively scavenged various ROS and reduced cell apoptosis at the cellular level. More importantly, EGM NPs can treat APAP-induced DILI in vivo, reducing the levels of liver function indicators in mice with liver injury, scaling down the area of hepatocyte necrosis and successfully inhibiting endoplasmic reticulum (ER) stress in the liver. EGM NPs also showed a certain anti-inflammatory effect by reducing infiltration of macrophages, decreasing pro-inflammatory factors and inhibiting the expression levels of inducible nitric oxide synthase (NOS2) and myeloperoxidase (MPO). Collectively, our findings suggest that EGM NPs-based nanotherapeutic is a novel strategy for the treatment of DILI.

Astaxanthin Activated the Nrf2/HO-1 Pathway to Enhance Autophagy and Inhibit Ferroptosis, Ameliorating Acetaminophen-Induced Liver Injury

Acetaminophen (APAP)-induced liver injury (AILI) is a common liver disease in clinical practice. Only one clinically approved drug, N-acetylcysteine (NAC), for the treatment of AILI is available in clinics, but novel treatment strategies are still needed due to the complicated pathological changes of AILI and the side effects of NAC. Here, we found that astaxanthin (ASX) can prevent AILI through the Nrf2/HO-1 pathway. After treatment with ASX, there was a positive activation of the Nrf2/HO-1 pathway in AILI models both in vivo and in vitro accompanied by enhanced autophagy and reduced ferroptosis. In APAP-challenged L02 liver cells, ASX reduced autophagy and enhanced apoptosis of the cells. Furthermore, we developed ASX-loaded hollow mesoporous silica nanoparticles (HMSN@ASX) to improve the aqueous solubility of ASX and targeted delivery of ASX to the liver and then significantly improve the therapeutic effects. Taken together, we found that ASX can protect against AILI by activating the Nrf2/HO-1 pathway, which mainly affects oxidative stress, autophagy, and ferroptosis processes, and the HMSN@ASX nanosystem can target the liver to enhance the treatment efficiency of AILI.

St. John's Wort exacerbates acetaminophen-induced liver injury by activation of PXR and CYP-mediated bioactivation

St. John's wort (SJW) is a medicinal herb remedy for mild depression. However, long-term use of SJW has raised safety concerns in clinical practice because of drug-drug interactions. Excessive use of acetaminophen (APAP) causes severe hepatotoxicity, but whether SJW modulates APAP-induced liver injury remains unclear. In this study, the effect of long-term SJW administration on APAP-induced acute hepatotoxicity and the involved mechanisms were investigated. Morphological and biochemical assessments clearly demonstrated that SJW exacerbates APAP-induced toxicity in vivo and in vitro. Moreover, SJW markedly promoted glutathione depletion and increased the levels of the APAP-cysteine and APAP-N-acetylcysteinyl adducts in mice, which enhanced APAP metabolic activation and aggravated APAP-induced liver injury. To further elucidate APAP metabolic activation in liver injury induced by SJW, the activities and expression levels of CYP2E1 and CYP3A were measured. The results showed that the activities and expression levels of CYP2E1 and CYP3A were increased after SJW treatment. Furthermore, the PXR-CYP signaling pathway was activated by SJW, and its downstream target genes were upregulated. Collectively, this study demonstrated that the long-term administration of SJW extract led to the metabolic activation of APAP and significantly exacerbated APAP-induced liver injury, which may suggest caution for the clinical use of SJW and APAP.

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.

Phellinus linteus polysaccharides mediates acetaminophen-induced hepatotoxicity via activating AMPK/Nrf2 signaling pathways

Overdose of acetaminophen (APAP) is currently one of the main causes of hepatoxicity and acute liver injury, which is often linked to oxidative stress. Phellinus linteus polysaccharides (Phps) have shown many hepatoprotective effects, however, the mechanism of Phps on APAP-induced acute liver injury has not been further elucidated. The aim of this study is to investigate the underlying mechanism of Phps to acute liver injury. The expression of AMPK/Nrf2 and autophagy were detected using western blot. The results indicated that Phps treatment effectively alleviated APAP-induced acute liver injury by reducing alanine transaminase (ALT) and aspartate aminotransferase (AST) levels in serum. Phps significantly attenuated myeloperoxidase (MPO) activity and glutathione (GSH) depletion. Meanwhile, Phps remarkably alleviated histopathological changes. Further research found that Phps promoted AMPK pathway and up-regulated nuclear factor erythroid-2-related factor (Nrf2) transported into nucleus, and elevated heme oxygenase 1(HO-1), glutamate-cysteine ligase catalytic (GCLC), glutamate cysteine ligase modifier (GCLM) and quinone oxidoreductase (NQO1). Additionally, Phps apparently facilitated the expression of autophagy proteins (ATG3, ATG5, ATG7, and ATG12). However, the protection of pathologic changes was nearly absent in Nrf2^-/- mice. Phps have potential in preventing oxidative stress in APAP-induced acute liver injury.

Inhibition of fucosylation by 2-fluorofucose attenuated acetaminophen-induced liver injury via its anti-inflammation and anti-oxidative stress effects

Fucosylation is a common glycan terminal modification, which has been reported to be inhibited by 2-fluorofucose (2FF) both in vivo and in vitro. The present study aimed to investigate the effect of 2FF on acetaminophen (APAP)-induced acute liver injury, and further clarified the possible mechanisms. In the present study, inhibition of fucosylation by 2FF relieved APAP-induced acute liver injury in vivo. Pretreatment with 2FF remarkably suppressed APAP-induced oxidative stress and mitochondria damage. 2FF markedly enhanced the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and simultaneously promoted the expression of downstream proteins including HO-1 and NQO1. Furthermore, pretreatment with 2FF significantly suppressed the expression of inflammation-associated proteins, such as COX2 and iNOS. The data from lectin blot assay revealed that the alteration of α1,6-fucosylation was involved in APAP-induced acute liver injury. The second part of this study further confirmed that the enhancements to antioxidant capacity of 2FF pretreatment and α1,6-fucose deficiency were related to Nrf2/keap1 and NF-κB signaling pathways in HepG2 cells. Taken together, the current study suggested that 2FF might have a potential therapeutic effect for APAP-induced acute liver injury.

Piperine as Therapeutic Agent in Paracetamol-Induced Hepatotoxicity in Mice

High doses of paracetamol (APAP) can cause irreversible liver damage. Piperine (P) inhibits cytochrome P450, which is involved in the metabolism of various xenobiotics, including paracetamol. We evaluated the hepatoprotective effects of piperine with or without N-acetylcysteine (NAC) in APAP-induced hepatotoxicity. The mice were treated with two doses of piperine (P20 or P40) and/or NAC at 2 h after administration of APAP. The NAC+P20 and NAC+P40 groups showed a reduced area of necrosis, MMP-9 activity, and Casp-1 expression. Furthermore, the NAC+P20 group was the only treatment that reduced alanine aminotransferase (ALT) and increased the levels of sulfhydryl groups (-SH). In the NAC+P40 group, NLRP-3 expression was reduced. Aspartate aminotransferase (AST), thiobarbituric acid-reactive substances (TBARS), and IL-1β expression decreased in the NAC, NAC+P20, and NAC+P40 groups compared to the APAP group. The liver necrosis area, TNF levels, carbonylated protein, and IL-18 expression decreased in the P40, NAC, NAC+P20, and NAC+P40 groups compared to the APAP group. The cytokine IL-6 was reduced in all treatments. Piperine can be used in combination with NAC to treat APAP-induced hepatotoxicity.

Mitochondrial Glrx2 Knockout Augments Acetaminophen-Induced Hepatotoxicity in Mice

Acetaminophen (APAP) is one of the most widely used drugs with antipyretic and analgesic effects, and thus hepatotoxicity from the overdose of APAP becomes one of the most common forms of drug-induced liver injury. The reaction towards thiol molecules, such as GSH by APAP metabolite, N-acetyl-p-benzo-quinonimine (NAPQI), is the main cause of APAP-induced hepatotoxicity. However, the role of many other thiol-related regulators in toxicity caused by APAP is still unclear. Here we have found that knockout of the Glrx2 gene, which encodes mitochondrial glutaredoxin2 (Grx2), sensitized mice to APAP-caused hepatotoxicity. Glrx2 deletion hindered Nrf2-mediated compensatory recovery of thiol-dependent redox systems after acetaminophen challenge, resulting in a more oxidized cellular state with a further decrease in GSH level, thioredoxin reductase activity, and GSH/GSSG ratio. The weakened feedback regulation capacity of the liver led to higher levels of protein glutathionylation and thioredoxin (both Trx1 and Trx2) oxidation in Glrx2^−/− mice. Following the cellular environment oxidation, nuclear translocation of apoptosis-inducing factor (AIF) was elevated in the liver of Glrx2^−/− mice. Taken together, these results demonstrated that mitochondrial Grx2 deficiency deteriorated APAP-induced hepatotoxicity by interrupting thiol-redox compensatory response, enhancing the AIF pathway-mediated oxidative damage.

Creatinine accelerates APAP-induced liver damage by increasing oxidative stress through ROS/JNK signaling pathway

Serum creatinine is an endogenous biomarker to estimate glomerular filtration rate (GFR) and is commonly used to assess renal function in clinical practice. Acetaminophen (APAP), the most available analgesic and antipyretic medication, is recommended as the drug of choice for pain control in patients with renal diseases. However, an overdose of APAP can lead to severe acute liver injury, which is also the most common cause of acute liver failure in western countries. The role of creatinine in APAP-induced liver injury is unclear and should be further explored. Herein, clinical data on patients with drug-induced liver injury revealed that the creatinine concentration between 82-442 μmol/L for female and 98–442 μmol/L for male is positively correlated with alanine aminotransferase (ALT), aspartate aminotransferase (AST). While there was no correlation between creatinine and ALT and AST when creatinine concentration is over 442 μmol/L. In addition, mice were administrated with creatinine intraperitoneally for 1 week before APAP injection to investigated the pathophysiological role of creatinine in APAP-induced acute liver injury. The results showed that creatinine administration aggravated hepatic necrosis and elevated serum lactate dehydrogenase (LDH) and ALT levels in mice upon APAP injection. The mechanism study demonstrated that creatinine could increase the production of reactive oxygen activation (ROS) and the activation of c-Jun N-terminal kinase (JNK). Furthermore, the liver injury was alleviated and the difference between APAP-treated mice and APAP combined with creatinine-treated mice was blunted after using specific ROS and JNK inhibitors. Significantly, creatinine stimulation aggravates APAP-induced cell death in HepaRG cells with the same mechanism. In summary, this study proposed that creatinine is closely related with liver function of drug-induced liver injury and exacerbates APAP-induced hepatocyte death by promoting ROS production and JNK activation, thus providing new insight into the usage of APAP in patients with kidney problems.

Mitochondria-Targeted Ratiometric Chemdosimeter to Detect Hypochlorite Acid for Monitoring the Drug-Damaged Liver and Kidney

Liver and kidney injury caused by drug toxicity is a serious threat to human health. Acetaminophenol (APAP), as a common antipyretic and analgesic drug, inevitably causes injury. When it is overused, hypochlorous acid (HClO) is excessively generated due to metabolic abnormalities, resulting in the accumulation of HClO in the mitochondria of liver and kidney tissues and causing damage. In this study, we designed a series of HClO responsive ratiometric chemdosimeter NRH-X (NRH-O, NRH-S, and NRH-C) to evaluate liver and kidney injury, and found that NRH-O has a specific sensitive response to HClO. NRH-O can not only monitor the variations of endogenous HClO content of living cells by fluorescence ratio changes in the mitochondria but also detect the upregulation of HClO induced by APAP. In addition, NRH-O can also be used for anatomic diagnosis of liver and kidney injury by fluorescence ratio imaging of HClO in the tissues of inflammatory mice.

Novel luteolin@pro-phytomicelles: In vitro characterization and in vivo evaluation of protection against drug-induced hepatotoxicity

A novel nanoformulation with the small molecule phytochemical dipotassium glycyrrhizinate as a nanomaterial was developed for the oral delivery of luteolin (Lut), a widely used phytochemical, but it suffered from poor water solubility and low oral bioavailability. This novel nanoformulation, named Lut@pro-phytomicelles, can be fabricated with a simple process. Lut@pro-phytomicelles can instantly dissolve into aqueous mediums and formulate through self-assembly a clear phytomicelle solution with a Lut encapsulation efficiency of 99.16 ± 0.90%, a small micelle size of 30.32 ± 0.12 nm, and a narrow polydispersity index of 0.138 ± 0.024. The optimized formulation demonstrated that Lut had solubility in up to 50 mg/ml of water as a result of its encapsulation within DG phytomicelles. Lut@pro-phytomicelles exhibited excellent characteristics, including good storage stability, a fast in vitro release profile, improvement in in vitro antioxidant activity, and high safety potential. In the oral bioavailability evaluation, a shorter Tmax, increased Cmax, and improved AUC0-t were obtained with Lut@pro-phytomicelles when compared to bare Lut. The distribution evaluation further showed that Lut@pro-phytomicelles could effectively increase the concentrations of Lut in all the tested organs and gastrointestinal segments. In the protection efficacy evaluation, 100 mg/kg Lut@pro-phytomicelles demonstrated strong effects against acetaminophen-induced hepatotoxicity. The mechanisms of inhibiting high-mobility group box 1 signaling and suppressing oxidative stress were involved in this strong treatment effect. These results showed that simple but novel Lut@pro-phytomicelles provided a new, promising nano-delivery system for Lut with a significantly improved in vivo profile.

Connexin-Based Channels in the Liver

Connexin proteins oligomerize in hexameric structures called connexin hemichannels, which then dock to form gap junctions. Gap junctions direct cell-cell communication by allowing the exchange of small molecules and ions between neighboring cells. In this way, hepatic gap junctions support liver homeostasis. Besides serving as building blocks for gap junctions, connexin hemichannels provide a pathway between the intracellular and the extracellular environment. The activation of connexin hemichannels is associated with acute and chronic liver pathologies. This article discusses the role of gap junctions and connexin hemichannels in the liver. © 2022 American Physiological Society. Compr Physiol 12:1-17, 2022.

FGL2-MCOLN3-Autophagy Axis-Triggered Neutrophil Extracellular Traps Exacerbate Liver Injury in Fulminant Viral Hepatitis

BACKGROUND & AIMS

Fulminant viral hepatitis (FVH) is a life-threatening disease, but its pathogenesis is not fully understood. Neutrophil extracellular traps (NETs) were an unrecognized link between inflammation and coagulation, which are 2 main features of FVH. Here, we investigated the role and mechanism of NETs in the pathogenesis of FVH.

METHODS

A mouse model of FVH was established by murine hepatitis virus strain-3 infection. Liver leukocytes of infected or uninfected mice were used for single-cell RNA sequencing and whole-transcriptome sequencing. NETs depletion was achieved using DNase 1. Acetaminophen was used to establish a mouse model of non-virus-caused acute liver failure. Clinically, NETs-related markers in liver, plasma, and peripheral neutrophils were assessed in patients with hepatitis B virus (HBV)-related acute liver injury.

RESULTS

Increased hepatic NETs formation was observed in murine hepatitis virus strain-3-infected mice, but not in acetaminophen-treated mice. NETs depletion improved the liver damage and survival rate in FVH by inhibiting hepatic fibrin deposition and inflammation. An adoptive transfer experiment showed that neutrophil-specific fibrinogen-like protein 2 (FGL2) promoted NETs formation. FGL2 was found to directly interact with mucolipin 3, which regulated calcium influx and initiated autophagy, leading to NETs formation. Clinically, increased plasma NETs level was associated with coagulation dysfunction in patients with HBV acute liver injury. Colocalization of FGL2, NETs, and fibrin in liver was observed in these patients.

CONCLUSIONS

NETs aggravated liver injury in FVH by promoting fibrin deposition and inflammation. NETs formation was regulated by the FGL2-mucolipin 3-autophagy axis. Targeting NETs may provide a new strategy for the treatment of FVH.

Sapidolide A alleviates acetaminophen-induced acute liver injury by inhibiting NLRP3 inflammasome activation in macrophages

Macrophages play a critical role in the pathogenesis of acetaminophen (APAP)-induced liver injury (AILI), a major cause of acute liver failure or even death. Sapidolide A (SA) is a sesquiterpene lactone extracted from Baccaurea ramiflora Lour., a folk medicine used in China to treat inflammatory diseases. In this study, we investigated whether SA exerted protective effects on macrophages, thus alleviated the secondary hepatocyte damage in an AILI. We showed that SA (5-20 μM) suppressed the phosphorylated activation of NF-κB in a dose-dependent manner, thereby inhibiting the expression and activation of the NOD-like receptor protein 3 (NLRP3) inflammasome and pyroptosis in LPS/ATP-treated mouse bone marrow-derived primary macrophages (BMDMs). In human hepatic cell line L02 co-cultured with BMDMs, SA (10 μM) protected macrophages from the pyroptosis induced by APAP-damaged L02 cells. Moreover, SA treatment reduced the secondary liver cell damage aggravated by the conditioned medium (CM) taken from LPS/ATP-treated macrophages. The in vivo assessments conducted on mice pretreated with SA (25, 50 mg/kg, ip) then with a single dose of APAP (400 mg/kg, ip) showed that SA significantly alleviated inflammatory responses of AILI by inhibiting the expression and activation of the NLRP3 inflammasome. In general, the results reported herein revealed that SA exerts anti-inflammatory effects by regulating NLRP3 inflammasome activation in macrophages, which suggests that SA has great a potential for use in the treatment of AILI patients.

Rosmarinic acid alleviates acetaminophen-induced hepatotoxicity by targeting Nrf2 and NEK7-NLRP3 signaling pathway

Rosmarinic acid (RA) is a natural polyphenol with various biological activities, such as anti-oxidative, anti-fibrotic, and hepatoprotective properties. The objective of this study was to investigate the protective effect of RA against acetaminophen (APAP)-induced hepatotoxicity (AILI) and explore the underlying mechanisms. Kunming mice were treated with RA (20, 40, or 80 mg/kg, i.g) for 7d, followed by an intraperitoneal injection of APAP (500 mg/kg). The liver injury was evaluated by serum biochemical and liver histopathological examinations. Human HepG2 cells were pre-treated with RA (20, 40, or 80 μmol/L) and then incubated with APAP (25 mmol/L) for 24 h. The MTT assay, wound healing assay, transwell migration assay, flow cytometry, and western blotting were employed to further evaluate RA's protective effects on AILI and explore the mechanisms. The results indicated that RA pre-treatment lowered the serum ALT and AST levels, ameliorated the histological damage to the liver, and reduced ROS generation and the production of IL-1β and IL-18 in the liver tissues in APAP-treated mice. Moreover, pre-treatment with RA could promote the cell viability and migration ability and inhibit apoptosis in APAP-treated HepG2 cells. Mechanistically, RA could significantly suppress the APAP-induced activation of the NEK7-NLRP3 signaling pathway. Notably, depletion of Nrf2 by short hairpin RNA (shRNA) partly eliminated the protective effects of RA on AILI and the suppression of NEK7-NLRP3 signaling by RA. In summary, these results indicate that RA has a protective role against AILI through Nrf2-mediated inhibition of ROS production and suppression of the NEK7-NLRP3 pathway.

Drug-Induced Hepatitis in Children: The Experience of a Single Center in Romania

Drug-induced liver injury (DILI) is uncommon but potentially lethal. Over 6 years, 2533 children with acute liver disease were identified in our center, 48 of which suffered from toxic hepatitis, and 40 exhibited DILI (22 paracetamol-related, 14 albendazole-related). The most affected children were in the 13–17-year-old age group. The mean time between drug ingestion and disease diagnosis was 25.4 h for paracetamol-related DILI and 21.6 days for the albendazole-related group. Clinical features were mostly gastrointestinal, jaundice being reported in 30% of the cases. Regarding the type of liver injury, for 70% of the patients it was hepatocellular (mostly paracetamol toxicity), for 11% cholestatic, and for 19% mixed (albendazole-related). The mean initial ALT value was 1020 U/L for all DILIs. Coagulopathy was only identified for the acetaminophen-related group. The median number of hospitalization days was 6.9 for DILI related to acetaminophen ingestion, compared with 7 for the idiosyncratic pattern. When applying the DILI severity index, 81% of the patients were categorized as having a mild hepatic ailment, while 19% had a moderate–severe or severe disease. No deaths were reported in the study group. The diagnosis of DILI involves the exclusion of other causes of liver injury; therefore, it is considered one of the most challenging diagnoses in hepatology.

N-acetyl cysteine prevents arecoline-inhibited C2C12 myoblast differentiation through ERK1/2 phosphorylation

Arecoline is known to induce reactive oxygen species (ROS). Our previous studies showed that arecoline inhibited myogenic differentiation and acetylcholine receptor cluster formation of C2C12 myoblasts. N-acetyl-cysteine (NAC) is a known ROS scavenger. We hypothesize that NAC scavenges the excess ROS caused by arecoline. In this article we examined the effect of NAC on the inhibited myoblast differentiation by arecoline and related mechanisms. We found that NAC less than 2 mM is non-cytotoxic to C2C12 by viability analysis. We further demonstrated that NAC attenuated the decreased number of myotubes and nuclei in each myotube compared to arecoline treatment by H & E staining. We also showed that NAC prevented the decreased expression level of the myogenic markers, myogenin and MYH caused by arecoline, using immunocytochemistry and western blotting. Finally, we found that NAC restored the decreased expression level of p-ERK1/2 by arecoline. In conclusion, our results indicate that NAC attenuates the damage of the arecoline-inhibited C2C12 myoblast differentiation by the activation/phosphorylation of ERK. This is the first report to demonstrate that NAC has beneficial effects on skeletal muscle myogenesis through ERK1/2 upon arecoline treatment. Since defects of skeletal muscle associates with several diseases, NAC can be a potent drug candidate in diseases related to defects in skeletal muscle myogenesis.

Progress in the treatment of drug-induced liver injury with natural products

There are numerous prescription drugs and non-prescription drugs that cause drug-induced liver injury (DILI), which is the main cause of liver disease in humans around the globe. Its mechanism becomes clearer as the disease is studied further. For an instance, when acetaminophen (APAP) is taken in excess, it produces N-acetyl-p-benzoquinone imine (NAPQI) that binds to biomacromolecules in the liver causing liver injury. Treatment of DILI with traditional Chinese medicine (TCM) has shown to be effective. For example, activation of the Nrf2 signaling pathway as well as regulation of glutathione (GSH) synthesis, coupling, and excretion are the mechanisms by which ginsenoside Rg1 (Rg1) treats APAP-induced acute liver injury. Nevertheless, reducing the toxicity of TCM in treating DILI is still a problem to be overcome at present and in the future. Accumulated evidences show that hydrogel-based nanocomposite may be an excellent carrier for TCM. Therefore, we reviewed TCM with potential anti-DILI, focusing on the signaling pathway of these drugs' anti-DILI effect, as well as the possibility and prospect of treating DILI by TCM based on hydrogel materials in the future. In conclusion, this review provides new insights to further explore TCM in the treatment of DILI.

SIRT3 inhibitor 3-TYP exacerbates thioacetamide-induced hepatic injury in mice

The purpose of the study was to explore the effects of SIRT3 inhibitor 3-TYP on acute liver failure (ALF) in mice and its underlying mechanism. The mice were treated with thioacetamide (TAA, 300 mg/kg) for inducing ALF model. 3-TYP (50 mg/kg) was administered 2 h prior to TAA. The liver histological changes were measured by HE staining. Blood samples were collected for analysis of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). MDA and GSH were used to evaluate the oxidative stress of liver. The expression levels of inflammatory cytokines (TNF-α and IL-1β) were measured by ELISA and Western blotting. The cell type expression of IL-1β in liver tissue was detected by immunofluorescent staining. The expression of SIRT3, MnSOD, ALDH2, MAPK, NF-κB, Nrf2/HO-1, p-elF2α/CHOP, and cleaved caspase 3 was determined by Western blotting. TUNEL staining was performed to detect the apoptosis cells of liver tissues. 3-TYP exacerbated the liver injury of ALF mice. 3-TYP increased the inflammatory responses and activation of MAPK and NF-κB pathways. In addition, 3-TYP administration enhanced the damage of oxidative stress, endoplasmic reticulum stress, and promoted hepatocyte apoptosis in ALF mice. 3-TYP exacerbates thioacetamide-induced hepatic injury in mice. Activation of SIRT3 could be a promising target for the treatment of ALF.

Inhibition of BTK improved APAP-induced liver injury via suppressing proinflammatory macrophages activation by restoring mitochondrion function

BACKGROUND

Acetaminophen (APAP) overdose can cause severe liver injury and APAP-induced liver injury (AILI) is one of the leading causes of acute liver failure (ALF). Bruton's tyrosine kinase (BTK) is a key tyrosine kinase in immune responses, which plays an important role in many inflammatory diseases. However, its effect on AILI is still not clear. Here, we aimed to assess the effect of BTK on AILI and explore its underlying mechanism.

METHODS

In our study, western blot and immunohistochemistry were used to detect the expression of BTK in AILI. The C57BL/6 mice were used to check the protective effect of BTK inhibition on AILI and the activation of BTK was confirmed in mice macrophages treated with APAP. Immunofluorescence, immunohistochemistry, oxygen consumption rate (OCR) detection, polymerase chain reaction (PCR), flow cytometry and western blot were used to determine the role of BTK in mitochondrial dynamics and function of macrophages and the underlying mechanisms in AILI.

RESULTS

Our results showed that BTK upregulated in AILI. BTK inhibition protected mice from AILI and BTK was activated in mice macrophages in response to APAP. Mechanically, BTK inhibition promoted mitochondrial fusion and restored mitochondrial function through phospholipase C gamma 2 (PLCγ2)-reactive oxygen species (ROS)-Optic Atrophy 1(OPA1) pathway in macrophages and finally suppressed the release of proinflammatory cytokines.

CONCLUSIONS

In conclusion, we found that BTK inhibition protected mice from AILI by restoring the mitochondrial function of macrophages through the improvement of the mitochondrial dynamic imbalance via PLCγ2-ROS-OPA1 signaling pathway, which indicated that BTK might be a potential therapeutic target of AILI.

Mitochondrial Dysfunction and Chronic Liver Disease

Mitochondria are generally considered the powerhouse of the cell, a small subcellular organelle that produces most of the cellular energy in the form of adenosine triphosphate (ATP). In addition, mitochondria are involved in various biological functions, such as biosynthesis, lipid metabolism, oxidative phosphorylation, cell signal transduction, and apoptosis. Mitochondrial dysfunction is manifested in different aspects, like increased mitochondrial reactive oxygen species (ROS), mitochondrial DNA (mtDNA) damage, adenosine triphosphate (ATP) synthesis disorder, abnormal mitophagy, as well as changes in mitochondrial morphology and structure. Mitochondrial dysfunction is related to the occurrence and development of various chronic liver diseases, including hepatocellular carcinoma (HCC), viral hepatitis, drug-induced liver injury (DILI), alcoholic fatty liver (AFL), and non-alcoholic fatty liver (NAFL). In this review, we summarize and discuss the role and mechanisms of mitochondrial dysfunction in chronic liver disease, focusing on and discussing some of the latest studies on mitochondria and chronic liver disease.

Progress and Setbacks in Translating a Decade of Ferroptosis Research into Clinical Practice

Ten years after its initial description, ferroptosis has emerged as the most intensely studied entity among the non-apoptotic forms of regulated cell death. The molecular features of ferroptotic cell death and its functional role have been characterized in vitro and in an ever-growing number of animal studies, demonstrating that it exerts either highly detrimental or, depending on the context, occasionally beneficial effects on the organism. Consequently, two contrary therapeutic approaches are being explored to exploit our detailed understanding of this cell death pathway: the inhibition of ferroptosis to limit organ damage in disorders such as drug-induced toxicity or ischemia-reperfusion injury, and the induction of ferroptosis in cancer cells to ameliorate anti-tumor strategies. However, the path from basic science to clinical utility is rocky. Emphasizing ferroptosis inhibition, we review the success and failures thus far in the translational process from basic research in the laboratory to the treatment of patients.

Acetaminophen-induced reduction of NIMA related kinase 7 expression exacerbates acute liver injury

Background & Aims

Acetaminophen (APAP)-induced acute liver injury (ALI) is a global health issue characterised by an incomplete understanding of its pathogenesis and unsatisfactory therapies. NEK7 plays critical roles in both cell cycle regulation and inflammation. In the present study, we investigated the role and mechanism of NEK7 in APAP-induced ALI.

Methods

In mice with NEK7 overexpression (hydrodynamic tail vein injection of NEK7 plasmids), hepatocyte-specific NEK7 knockout (cKO), and inducible NEK7 knockout (iKO), an overdose of APAP was administered to induce ALI. Liver injury was determined by an analysis of serum liver enzymes, pathological changes, inflammatory cytokines, and metabonomic profiles. In vitro, hepatocyte damage was evaluated by an analysis of cell viability, the reactive oxygen species levels, and mitochondrial function in different cell lines. Hepatocyte proliferation and the cell cycle status were determined by Ki-67 staining, EdU staining, and the cyclin levels.

Results

NEK7 was markedly downregulated in APAP-induced injured liver and damaged hepatocytes. NEK7 overexpression in the liver significantly alleviated APAP-induced liver injury, as shown by the restored liver function, reduced pathological injury, and decreased inflammation and oxidative stress, which was confirmed in a hepatocyte cell line. Moreover, both NEK7 cKO and iKO mice exhibited exacerbation of APAP-induced ALI. Finally, we determined that cyclin B1-mediated cell cycle progression could mediate the protective effect of NEK7 against APAP-induced ALI.

Conclusions

Reduced NEK7 contributes to APAP-induced ALI, possibly by dysregulating cyclins and disturbing cell cycle progression.

Lay summary

Acetaminophen-induced acute liver injury is one of the major global health issues, owing to its high incidence, potential severity, and limited therapeutic options. Our current understanding of its pathogenesis is incomplete. Herein, we have shown that reduced NEK7 (a protein with a key role in the cell cycle) exacerbates acetaminophen-induced acute liver injury. Hence, NEK7 could be a possible therapeutic target for the prevention or treatment of this condition.

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NEK7 was downregulated in livers following APAP overdose challenge.

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Reduced NEK7 worsened APAP-induced acute liver injury.

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Reduced NEK7 dysregulated cyclins and cell cycle progression.

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Cyclin B1 overexpression attenuated NEK7 reduction-related worsening of APAP-induced acute liver injury.

Racing against time: leveraging preclinical models to understand pulmonary susceptibility to perinatal acetaminophen exposures

Over the past decade, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce postoperative opiate burden, and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). Despite these potential benefits, APAP exposures have spread to increasingly less mature infants, a highly vulnerable population for whom robust pharmacokinetic and pharmacodynamic data for APAP are lacking. Concerningly, preclinical studies suggest that perinatal APAP exposures may result in unanticipated adverse effects that are unique to the developing lung. In this review, we discuss the clinical observations linking APAP exposures to adverse respiratory outcomes and the preclinical data demonstrating a developmental susceptibility to APAP-induced lung injury. We show how clinical observations linking perinatal APAP exposures to pulmonary injury have been taken to the bench to produce important insights into the potential mechanisms underlying these findings. We argue that the available data support a more cautious approach to APAP use in the NICU until large randomized controlled trials provide appropriate safety and efficacy data.

Gut Microbiota Mediates the Therapeutic Effect of Monoclonal Anti-TLR4 Antibody on Acetaminophen-Induced Acute Liver Injury in Mice

Acetaminophen (APAP) overdose is one of the most common causes of acute liver injury (ALI) in Western countries. Many studies show that the gut microbiota plays an important role in liver injury. Currently, the only approved treatment for APAP-induced ALI is N-acetylcysteine; therefore, it is essential to develop new therapeutic agents and explore the underlying mechanisms. We developed a novel monoclonal anti-Toll-like receptor 4 (TLR4) antibody (ATAB) and hypothesized that it has therapeutic effects on APAP-induced ALI and that gut microbiota may be involved in the underlying mechanism of ATAB treatment. Male C57BL/6 mice were treated with APAP and ATAB, which produced a therapeutic effect on ALI and altered the gut microbiota and their metabolic pathway, such as Roseburia, Lactobacillus, Akkermansia, and the fatty acid pathway, etc. Furthermore, we verified that purified short-chain fatty acids (SCFAs) could alleviate ALI. Moreover, a separate group of mice that received feces from the ATAB group showed less severe liver injury compared with the mice receiving feces from the APAP group. ATAB therapy also improved the gut barrier functions in mice and reduced the expression of protein zonulin. Our results revealed that gut microbiota plays an important role in the therapeutic effect of ATAB on APAP-induced ALI. IMPORTANCE In this study, we found the monoclonal anti-Toll-like receptor 4 antibody can alleviate APAP-induced acute liver injury through the change of the gut microbiota, metabolic pathways, and gut barrier function. This work suggested the gut microbiota can be the therapeutic target of the APAP-induced acute liver injury, and we performed the fundamental research for further research.

Delivery of therapeutic carbon monoxide by gas-entrapping materials

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

Ethnopharmacological impact of Melaleuca rugulosa (Link) Craven leaves extract on liver inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Melaleuca species have been used by many ethnic communities for the management and treatment of several ailments as hemorrhoids, cough, skin infections, rheumatism, sore throat, pain, inflammation, and digestive system malfunctions. However, the detailed mechanistic pharmacological effect of Melaleuca rugulosa (Link) Craven leaves in the management of liver inflammation has not been yet addressed.

AIM OF THE STUDY

The present study aimed to evaluate the anti-inflammatory, antioxidant, and antiapoptotic capacities of the aqueous methanol extract of M. rugulosa leaves in relevance to their flavonoid content using an appropriate in vivo model.

MATERIALS AND METHODS

The aqueous methanol extract of M. rugulosa leaves was administered to the rats at three non-toxic doses (250, 500, and 1000 mg/kg) for seven days prior to the initiation of liver-injury induced by paracetamol (3 g/kg). Liver enzymes including alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were evaluated in serum samples. The oxidative stress markers including reduced glutathione (GSH), malondialdehyde (MDA), and nitric oxide (NO) levels as well as the inflammatory markers such as tumour necrosis factor-alpha (TNF-α) and nuclear factor-kappa B (NF-κB), were assessed in liver homogenate. The results were supported by histopathological and immuno-histochemical studies. The phytochemical investigation of the flavonoid-rich fraction of the aqueous methanol extract was accomplished using different chromatographic and spectroscopic techniques.

RESULTS

The aqueous methanol extract of M. rugulosa leaves showed a powerful hepatoprotective activity evidenced by the significant reduction of MDA and NO levels, as well as increasing GSH and catalase activity. Moreover, the extract exhibited anti-inflammatory and antiapoptotic activities witnessed by decreasing TNF-α, NF-κB, iNOS, p-JNK, caspase-3, BAX, and increasing Bcl-2 levels. Moreover, the pretreatment of rats with all doses of M. rugulosa leaves extract showed a significant decrease in liver weight/body weight (LW/BW) ratio, and total bilirubin induced by paracetamol. On the other hand, the chromatographic separation of the flavonoid-rich fraction afforded twenty known flavonoids namely; iso-orientin (1), orientin (2), isovitexin (3), vitexin (4), quercetin-3-O-β-D-glucuronid methyl ether (5), quercetin-3-O-β-D-mannuronpyranoside (6), isoquercetin (7), quercitrin (8), kaempferol-3-O-β-D-mannuronopyranoside (9), kaempferol-7-O-methyl ether-3-O-β-D-glucopyranoside (10), guaijaverin (11), avicularin (12), kaempferide-3-O-β-D-glucopyranoside (13), astragalin (14), afzelin (15), luteolin (16), apigenin (17), quercetin (18), kaempferol (19), and catechin (20).

CONCLUSION

The aqueous methanol extract of M. rugulosa leaves showed potential hepatoprotective, antioxidant, and anti-inflammatory activities against paracetamol-induced liver inflammation which is correlated at least in part to its considerable phenolic content.

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.

IL6 Induces mtDNA Leakage to Affect the Immune Escape of Endometrial Carcinoma via cGAS-STING

Endometrial carcinoma (EC) is a commonly diagnosed gynecological malignancy. Interleukin-6 (IL6) plays a critical role in modulating the progression of several types of tumors, including EC. However, the specific mechanism of IL6 in regulating EC progression has not been clearly elucidated. In this study, we performed a series of functional experiments to explore the potential mechanisms involved in IL6 function in the progression of EC. Here, we found that IL6 increased reactive oxygen species (ROS) generation by enhancing the NADPH oxidase (NOX) level and induced mtDNA leakage in EC cells, which further caused the activation of the downstream cGAS-STING signaling and increased production of extracellular vesicle (EV) production from EC cells. Besides, the activation of cGAS-STING signaling enhanced the expression of type I IFN and its downstream molecule PD-L1 through the TBK1-IRF3 pathway. Importantly, a high level mtDNA and PD-L1 were present in EVs derived from IL6-induced EC cells; these vesicles were shown to be able to induce T cell apoptosis. Finally, anti-PD-L1 treatment in mice showed that blockade of PD-L1 significantly reversed tumor immune escape mediated by IL6-induced EVs. Together, we provide evidence that IL6 induced mtDNA leakage to regulate the immune escape of EC cells. Our findings may provide a novel clue for the development of therapeutic targets for EC.

Acute Liver Failure in Children

Acute liver failure (ALF) in children, irrespective of cause, is a rapidly evolving catastrophic clinical condition that results in high mortality and morbidity without prompt identification and intervention. Massive hepatocyte necrosis impairs the synthetic, excretory, and detoxification abilities of the liver, with resultant coagulopathy, jaundice, metabolic disturbance, and encephalopathy. Extrahepatic organ damage, multiorgan failure, and death result from circulating inflammatory mediators released by the hepatocytes undergoing necrosis. There are yet no treatment options available for reversing or halting hepatocellular necrosis, thus current therapy focuses on supporting failing organs and preventing life threatening complications pending either spontaneous liver recovery or transplantation. The aims of this review are to define pediatric acute liver failure (PALF), understand the pathophysiologic processes that lead to multiorgan failure, to describe the consequences of a failing liver on extrahepatic organs, to enumerate the critical care challenges encountered during PALF management, and to describe pharmacologic and extracorporeal options available to support a critically ill child with ALF in the intensive care unit.

Protective Effects of Polydatin from Grapes and Reynoutria japonica Houtt. on Damaged Macrophages Treated with Acetaminophen

The unregulated use of acetaminophen (APAP), an antipyretic and analgesic drug, harms hepatocytes and kidney cells, leading to liver failure and acute kidney injury. Herein, we investigate whether APAP damages macrophages in the immune system by observing its effects on macrophage proliferation and apoptosis. Using proteomics, we analyzed the effects of APAP on macrophage protein expression profiles and evaluated whether polydatin, the active ingredient in grapes and wine, can repair the damaged cells. The results showed that APAP alters the morphology and physiological processes of macrophages, inhibits macrophage proliferation, and promotes apoptosis. We observed 528 differentially expressed proteins when 500 µg/mL APAP was administered to the cells. These proteins are involved in biological processes including cell division, apoptosis, and acute phase response. Overall, our findings demonstrate that APAP harms the immune system by damaging macrophages and that polydatin can repair this damage.

Methyl 6-O-cinnamoyl-α-d-glucopyranoside Ameliorates Acute Liver Injury by Inhibiting Oxidative Stress Through the Activation of Nrf2 Signaling Pathway

Excessive stimulation of hepatotoxins and drugs often lead to acute liver injury, while treatment strategies for acute liver injury have been limited. Methyl 6-O-cinnamoyl-α-d-glucopyranoside (MCGP) is a structure modified compound from cinnamic acid, a key chemical found in plants with significant antioxidant, anti-inflammatory, and antidiabetic effects. In this study, we investigated the effects and underlying mechanisms of MCGP on acetaminophen (APAP)- or carbon tetrachloride (CCl₄)-induced acute liver injury. As a result, MCGP inhibited cell death and apoptosis induced by APAP or CCl₄, and suppressed the reactive oxygen species (ROS) generation stimulated by H₂O₂ in liver AML12 cells. In vivo, MCGP alleviated APAP/CCl₄-induced hepatic necrosis and resumed abnormal aminotransferase activities and liver antioxidase activities. In addition, MCGP depressed APAP- or CCl₄-induced oxidative stress through the suppression of CYP2E1 and activation of nuclear factor erythroid 2-related factor 2 (Nrf2) signaling pathway. MCGP also enhanced the number of PCNA-positive hepatocytes, increased hepatic PCNA and Bcl-XL, and decreased BAX expression in APAP-/CCl₄-intoxicated mice. Furthermore, MCGP activated the GSDMD-N/cleaved caspase 1 pathway. In summary, MCGP might act as a potential therapeutic drug against drug-induced and chemical-induced acute liver injuries, and its underlying mechanisms might engage on the pressing of oxidative stress, refraining of hepatocyte apoptosis, and facilitating of liver regeneration.

Hepatic SIRT6 Modulates Transcriptional Activities of FXR to Alleviate Acetaminophen-induced Hepatotoxicity

BACKGROUND & AIMS

Excessive acetaminophen (APAP) intake causes oxidative stress and inflammation, leading to fatal hepatotoxicity; however, the mechanism remains unclear. This study aims to explore the protective effects and detailed mechanisms of sirtuin 6 (SIRT6) in the defense against APAP-induced hepatotoxicity.

METHODS

Hepatocyte-specific SIRT6 knockout mice, farnesoid X receptor (FXR) knockout mice, and mice with genetic or pharmacological activation of SIRT6 were subjected to APAP to evaluate the critical role of SIRT6 in the pathogenesis of acute liver injury. RNA sequences were used to investigate molecular mechanisms underlying this process.

RESULTS

Hepatic SIRT6 expression was substantially reduced in the patients and mice with acute liver injury. The deletion of SIRT6 in mice and mice primary hepatocytes led to high N-acetyl-p-benzo-quinoneimine and low glutathione levels in the liver, thereby enhancing APAP overdose-induced liver injury, manifested as increased hepatic centrilobular necrosis, oxidative stress, and inflammation. Conversely, overexpression or pharmacological activation of SIRT6 enhanced glutathione and decreased N-acetyl-p-benzo-quinoneimine, thus alleviating APAP-induced hepatotoxicity via normalization of liver damage, inflammatory infiltration, and oxidative stress. Our molecular analysis revealed that FXR is regulated by SIRT6, which is associated with the pathological progression of ALI. Mechanistically, SIRT6 deacetylates FXR and elevates FXR transcriptional activity. FXR ablation in mice and mice primary hepatocytes prominently blunted SIRT6 overexpression and activation-mediated ameliorative effects. Conversely, pharmacological activation of FXR mitigated APAP-induced hepatotoxicity in SIRT6 knockout mice.

CONCLUSIONS

Our current study suggests that SIRT6 plays a crucial role in APAP-induced hepatotoxicity, and pharmacological activation of SIRT6 may represent a novel therapeutic strategy for APAP overdose-induced liver injury.

NIRII-HDs: A Versatile Platform for Developing Activatable NIR-II Fluorogenic Probes for Reliable In Vivo Analyte Sensing

Small-molecule-based second near-infrared (NIR-II) activatable fluorescent probes can potentially provide a high target-to-background ratio and deep tissue penetration. However, most of the reported NIR-II activatable small-molecule probes exhibit poor versatility owing to the lack of a general and stable optically tunable group. In this study, we designed NIRII-HDs, a novel dye scaffold optimized for NIR-II probe development. In particular, dye NIRII-HD5 showed the best optical properties such as proper pK_a value, excellent stability, and high NIR-II brightness, which can be beneficial for in vivo imaging with high contrast. To demonstrate the applicability of the NIRII-HD5 dye, we designed three target-activatable NIR-II probes for ROS, thiols, and enzymes. Using these novel probes, we not only realized reliable NIR-II imaging of different diseases in mouse models but also evaluated the redox potential of liver tissue during a liver injury in vivo with high fidelity.

Mesencephalic astrocyte-derived neurotrophic factor protects against paracetamol -induced liver injury by inhibiting PERK-ATF4-CHOP signaling pathway

Paracetamol (APAP), an over-the-counter drug, is normally safe within the therapeutic dose range but can cause irreversible liver damage after an overdose. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an endoplasmic reticulum (ER) stress protein and plays a crucial role in metabolic disease. However, the role of MANF in APAP-induced acute hepatotoxicity is still unknown. We used hepatocyte-specific MANF-knockout mice and hepatocyte-specific MANF transgenic mice to investigate the role of hepatocyte-derived MANF in APAP-induced acute liver injury. MANF deficiency was associated with a decreased expression of detoxification enzymes, aggravated glutathione depletion and apoptosis in hepatocytes. Mechanistically, MANF knockout significantly increased PERK-eIF2α-ATF4-CHOP signaling pathway. Blockade of PERK abolished MANF deficiency-over-induced hepatotoxicity after APAP administration. Conversely, hepatocyte-specific MANF overexpression attenuated APAP-induced hepatotoxicity by downregulating the PERK-eIF2α-ATF4-CHOP signaling pathway. Thus, hepatocyte-derived MANF may play a protective role in APAP-induced hepatotoxicity.

DDAH1 Protects against Acetaminophen-Induced Liver Hepatoxicity in Mice

In many developed countries, acetaminophen (APAP) overdose-induced acute liver injury is a significant therapeutic problem. Dimethylarginine dimethylaminohydrolase 1 (DDAH1) is a critical enzyme for asymmetric dimethylarginine (ADMA) metabolism. Growing evidence suggests that liver dysfunction is associated with increased plasma ADMA levels and reduced hepatic DDAH1 activity/expression. The purpose of this study was to investigate the involvement of DDAH1 in APAP-mediated hepatotoxicity using Ddah1-/- and DDAH1 transgenic mice. After APAP challenge, Ddah1-/- mice developed more severe liver injury than wild type (WT) mice, which was associated with a greater induction of fibrosis, oxidative stress, inflammation, cell apoptosis and phosphorylation of JNK. In contrast, overexpression of DDAH1 attenuated APAP-induced liver injury. RNA-seq analysis showed that DDAH1 affects xenobiotic metabolism and glutathione metabolism pathways in APAP-treated livers. Furthermore, we found that DDAH1 knockdown aggravated APAP-induced cell death, oxidative stress, phosphorylation of JNK and p65, upregulation of CYP2E1 and downregulation of GSTA1 in HepG2 cells. Collectively, our data suggested that DDAH1 has a marked protective effect against APAP-induced liver oxidative stress, inflammation and injury. Strategies to increase hepatic DDAH1 expression/activity may be novel approaches for drug-induced acute liver injury therapy.