Acetaminophen-induced liver injury: Implications for temporal homeostasis of lipid metabolism and eicosanoid signaling pathway

The regulation of GSH/GPX4-mediated lipid accumulation confirms that schisandra polysaccharides should be valued equally as lignans

ETHNOPHARMACOLOGICAL RELEVANCE

Acetaminophen (APAP) induced liver injury (AILI) is a common cause of clinical hepatic damage and even acute liver failure. Our previous research has shown that Schisandra chinensis lignan extract (SLE) can exert a hepatoprotective effect by regulating lipid metabolism. Although polysaccharides from Schisandra chinensis (S. chinensis), like lignans, are important components of S. chinensis, their pharmacological activity and target effects on AILI have not yet been explored.

AIM OF THE STUDY

This study aims to quantitatively reveal the role of SCP in the pharmacological activity of S. chinensis, and further explore the pharmacological components, potential action targets and mechanisms of S. chinensis in treating AILI.

MATERIALS AND METHODS

The therapeutic effect of SCP on AILI was systematically determined via comparing the efficacy of SCP and SLE on in vitro and in vivo models. Network pharmacology, molecular docking and multi-omics techniques were then used to screen and verify the action targets of S. chinensis against AILI.

RESULTS

SCP intervention could significantly improve AILI, and the therapeutic effect was comparable to that of SLE. Notably, the combination of SCP and SLE did not produce mutual antagonistic effects. Subsequently, we found that both SCP and SLE could significantly reverse the down-regulation of GPX4 caused by the APAP modeling, and then further improving lipid metabolism abnormalities.

CONCLUSIONS

Hepatoprotective effects of SCP and SLE is most correlated with their regulation of GSH/GPX4-mediated lipid accumulation. This is the first exploration of the hepatoprotective effect and potential mechanism of SCP in treating AILI, which is crucial for fully utilizing S. chinensis and developing promising AILI therapeutic agents.

A Review of the Role of Caveolin-1 in Acetaminophen-Induced Liver Injury

BACKGROUND

Acetaminophen (APAP) is commonly used as an antipyretic and analgesic agent. Excessive APAP can induce liver toxicity, known as APAP-induced liver injury (ALI). The metabolism and pathogenesis of APAP have been extensively studied in recent years, and many cellular processes such as autophagy, mitochondrial oxidative stress, mitochondrial dysfunction, and liver regeneration have been identified to be involved in the pathogenesis of ALI. Caveolin-1 (CAV-1) as a scaffold protein has also been shown to be involved in the development of various diseases, especially liver disease and tumorigenesis. The role of CAV-1 in the development of liver disease and the association between them remains a challenging and uncharted territory.

SUMMARY

In this review, we briefly explore the potential therapeutic effects of CAV-1 on ALI through autophagy, oxidative stress, and lipid metabolism. Further research to better understand the mechanisms by which CAV-1 regulates liver injury will not only enhance our understanding of this important cellular process, but also help develop new therapies for human disease by targeting CAV-1 targets.

KEY MESSAGES

This review briefly summarizes the potential protective mechanisms of CAV-1 against liver injury caused by APAP.

Increased TG to HDL-C ratio is associated with severity of drug-induced liver injury

We investigated the relationship between dyslipidemia and drug-induced liver injury (DILI), especially the level of triglyceride to high-density lipoprotein cholesterol ratio (TG/HDL-C) in severe DILI. In this single-centered retrospective study, of 326 patients with DILI, 221 patients were analyzed. Control groups include medication using group and acute hepatitis B group. The relationship between dyslipidemia and DILI was estimated. Demographic and clinical features were analyzed. Dyslipidemia and TG/HDL-C ratios were compared between DILI and control groups, DILI mild group and severe group. The area under the receiver-operating characteristic curve (AUC) was used to evaluate the credibility of the relationship and to find cut-off points. Dyslipidemia is related to DILI when compared with medication using control group (AOR 4.60; 95% CI 2.81-7.54; P < 0.01) and compared with acute hepatitis B group (AOR 2.12; 95% CI 1.37-3.29; P < 0.01). Dyslipidemia is associated with the severity of DILI (AOR 25.78; 95% CI 7.63-87.1; P < 0.01). TG/HDL-C ratio is higher in DILI group than that of medication using control group, also higher in severe DILI group than that of mild DILI group. AUCs for TG/HDL-C ratio to indicate the severity of DILI was 0.89 (P < 0.05), the cut-off point was 2.35. Dyslipidemia and TG/HDL-C ratio were related to DILI occurrence. Severe liver injury in DILI was associated with dyslipidemia and elevated TG/HDL-C ratio.

Lipids in Liver Failure Syndromes: A Focus on Eicosanoids, Specialized Pro-Resolving Lipid Mediators and Lysophospholipids

Lipids are organic compounds insoluble in water with a variety of metabolic and non-metabolic functions. They not only represent an efficient energy substrate but can also act as key inflammatory and anti-inflammatory molecules as part of a network of soluble mediators at the interface of metabolism and the immune system. The role of endogenous bioactive lipid mediators has been demonstrated in several inflammatory diseases (rheumatoid arthritis, inflammatory bowel disease, atherosclerosis, cancer). The liver is unique in providing balanced immunotolerance to the exposure of bacterial components from the gut transiting through the portal vein and the lymphatic system. This balance is abruptly deranged in liver failure syndromes such as acute liver failure and acute-on-chronic liver failure. In these syndromes, researchers have recently focused on bioactive lipid mediators by global metabonomic profiling and uncovered the pivotal role of these mediators in the immune dysfunction observed in liver failure syndromes explaining the high occurrence of sepsis and subsequent organ failure. Among endogenous bioactive lipids, the mechanistic actions of three classes (eicosanoids, pro-resolving lipid mediators and lysophospholipids) in the pathophysiological modulation of liver failure syndromes will be the topic of this narrative review. Furthermore, the therapeutic potential of lipid-immune pathways will be described.

Prediction and mechanistic analysis of drug-induced liver injury (DILI) based on chemical structure

BACKGROUND

Drug-induced liver injury (DILI) is a major safety concern characterized by a complex and diverse pathogenesis. In order to identify DILI early in drug development, a better understanding of the injury and models with better predictivity are urgently needed. One approach in this regard are in silico models which aim at predicting the risk of DILI based on the compound structure. However, these models do not yet show sufficient predictive performance or interpretability to be useful for decision making by themselves, the former partially stemming from the underlying problem of labeling the in vivo DILI risk of compounds in a meaningful way for generating machine learning models.

RESULTS

As part of the Critical Assessment of Massive Data Analysis (CAMDA) "CMap Drug Safety Challenge" 2019 ( http://camda2019.bioinf.jku.at ), chemical structure-based models were generated using the binarized DILIrank annotations. Support Vector Machine (SVM) and Random Forest (RF) classifiers showed comparable performance to previously published models with a mean balanced accuracy over models generated using 5-fold LOCO-CV inside a 10-fold training scheme of 0.759 ± 0.027 when predicting an external test set. In the models which used predicted protein targets as compound descriptors, we identified the most information-rich proteins which agreed with the mechanisms of action and toxicity of nonsteroidal anti-inflammatory drugs (NSAIDs), one of the most important drug classes causing DILI, stress response via TP53 and biotransformation. In addition, we identified multiple proteins involved in xenobiotic metabolism which could be novel DILI-related off-targets, such as CLK1 and DYRK2. Moreover, we derived potential structural alerts for DILI with high precision, including furan and hydrazine derivatives; however, all derived alerts were present in approved drugs and were over specific indicating the need to consider quantitative variables such as dose.

CONCLUSION

Using chemical structure-based descriptors such as structural fingerprints and predicted protein targets, DILI prediction models were built with a predictive performance comparable to previous literature. In addition, we derived insights on proteins and pathways statistically (and potentially causally) linked to DILI from these models and inferred new structural alerts related to this adverse endpoint.

Gene Expression Signatures in AML-12 Hepatocyte Cells upon Dengue virus Infection and Acetaminophen Treatment

Dengue is an acute viral disease caused by Dengue virus (DENV) and is considered to be the most common arbovirus worldwide. The clinical characteristics of dengue may vary from asymptomatic to severe complications and severe organ impairment, particularly affecting the liver. Dengue treatment is palliative with acetaminophen (APAP), usually known as Paracetamol, being the most used drug aiming to relieve the mild symptoms of dengue. APAP is a safe and effective drug but, like dengue, can trigger the development of liver disorders. Given this scenario, it is necessary to investigate the effects of combining these two factors on hepatocyte homeostasis. Therefore, this study aimed to evaluate the molecular changes in hepatocytes resulting from the association between DENV infection and treatment with sub-toxic APAP concentrations. Using an in vitro experimental model of DENV-2 infected hepatocytes (AML-12 cells) treated with APAP, we evaluated the influence of the virus and drug association on the transcriptome of these hepatocytes by RNA sequencing (RNAseq). The virus-drug association was able to induce changes in the gene expression profile of AML-12 cells and here we highlight and explore these changes and its putative influence on biological processes for cellular homeostasis.

Evaluation of non-clinical toxicity of extract and vouacapans from fruits of Pterodon pubescens Benth

Pterodon pubescens Benth. is widely used in folk medicine for the treatment of inflammatory conditions, with the activity attributed to the compounds with a vouacapan moiety, however, few studies report the toxicological evaluation of the extract and safety issues related to the species. Herein the non-clinical toxicity, in in vivo and in vitro tests, of dichloromethane crude extract of Pterodon pubescens fruits (PPE) and vouacapan diterpene furan isomer´s mixture (1:1) 6α-hydroxy-7β-acetoxy-vouacapan-17β-oate methyl ester and 6α-acetoxy-7β-hydroxy-vouacapan-17β-oate methyl ester isomers (VDFI mixture) is reported. Toxicological evaluation of 110-day repeated dose oral toxicity study, as hematological, biochemical, and histopathological parameters demonstrated that animals (male and female Wistar rats) treated with PPE presented no signs of toxicity, nevertheless daily high dose administration (500 mg/Kg) altered the metabolic homeostasis of animals that manifested microgoticular hepatic steatosis. Biochemical and histopathological results of animals (female Swiss mice) treated daily with VDFI mixture, at the highest dose (300 mg/Kg), indicated liver toxicity in one animal causing acute hepatotoxicity. Alkaline Comet assay demonstrated that PPE and VDFI mixture increased the percentage of DNA fragmentation without interfering with the tail moment parameter, but only VDFI mixture (30 µg/mL) presented statistical difference. In the micronucleus induction test, PPE and VDFI mixture did not demonstrate mutagenic potential. Our data provide evidence for the safety use of PPE and VDFI mixture in lower doses enabling further clinical studies and the development of herbal medicine.

Divergent effects of glutathione depletion on isocitrate dehydrogenase 1 and the pentose phosphate pathway in hamster liver

The liver regenerates NADPH via multiple pathways to maintain redox balance and reductive biosynthesis. The pentose phosphate pathway (PPP) contributes to hepatic lipogenesis by supplying NADPH, and it is thought to play a major role in response to oxidative stress. This study determined the significance of the PPP and related NADPH-regenerating enzymes in the liver under oxidative stress. Fasted hamsters received acetaminophen (400 mg/kg) to deplete glutathione in the liver and [U-13 C3 ]glycerol to measure the PPP activity by analysis of 13 C distribution in plasma glucose. Blood and liver were harvested to assess NADPH-producing enzymes, antioxidant defense, PPP, and other relevant biochemical processes. Acetaminophen caused glutathione depletion and decreased activities of glutathione peroxidase and catalase in the liver, but it did not change triglyceride synthesis. Although the PPP is potentially an abundant source of NADPH, its activity was decreased and the expression of glucose 6-phosphate dehydrogenase remained unchanged after acetaminophen treatment. The effects of acetaminophen on other NADPH-producing enzymes were complex. Isocitrate dehydrogenase 1 was overexpressed, both isocitrate dehydrogenase 2 and malic enzyme 1 were underexpressed, and methylenetetrahydrofolate dehydrogenase 1 remained unchanged. In summary, isocitrate dehydrogenase 1 was most sensitive to glutathione depletion caused by acetaminophen, but glucose 6-phosphate dehydrogenase, the regulatory enzyme of PPP, was not.

Activation of Farnesoid X Receptor by Schaftoside Ameliorates Acetaminophen-Induced Hepatotoxicity by Modulating Oxidative Stress and Inflammation

Aims: Acetaminophen (APAP) overdose leads to acute liver injury by inducing hepatic mitochondrial oxidative stress and inflammation. However, the molecular mechanisms involved are still unclear. Farnesoid X receptor (FXR) serves as a therapeutic target for the treatment of liver disorders, whose activation has been proved to protect APAP-induced hepatotoxicity. In this study, we examined whether FXR activation by schaftoside (SS), a naturally occurring flavonoid from Desmodium styracifolium, could protect mice against APAP-induced hepatotoxicity via regulation of oxidative stress and inflammation. Results: We first found that SS exhibited potent protective effects against APAP-induced hepatotoxicity in mice. The study reveals that SS is a potential agonist of FXR, which protects mice from hepatotoxicity mostly via regulation of oxidative stress and inflammation. Mechanistically, the hepatoprotective SS is associated with the induction of the genes of phase II detoxifying enzymes (e.g., UGT1A1, GSTα1), phase III drug efflux transporters (e.g., bile salt export pump, organic solvent transporter protein β), and glutathione metabolism-related enzymes (e.g., glutamate-cysteine ligase modifier subunit [Gclm], glutamate-cysteine ligase catalytic subunit [Gclc]). More importantly, SS-mediated FXR activation could fine-tune the pro- and anti-inflammatory eicosanoids generation via altering eicosanoids metabolic pathway, thereby resulting in decrease of hepatic inflammation. In contrast, FXR deficiency can abrogate the above effects. Innovation and Conclusion: Our results provided the direct evidence that FXR activation by SS could attenuate APAP-induced hepatotoxicity via inhibition of nuclear factor kappa-B signaling and fine-tuning the generation of proinflammatory mediators' eicosanoids. Our findings indicate that strategies to activate FXR signaling in hepatocytes may provide a promising therapeutic approach to alleviate liver injury induced by APAP overdose.

Hepatoprotective Effect of Citrus aurantium L. Against APAP-induced Liver Injury by Regulating Liver Lipid Metabolism and Apoptosis

Acetaminophen (APAP) refers to a medication used to manage pain and fever symptoms, but it always causes liver injury when overdosed. Zhishi, dried young fruit of Citrus aurantium L., is a famous Citrus herbal medicine in Asian countries which is rich in dietary phenolic substances. In this study, the mechanism of Zhishi protected against APAP-induced liver injury was studied more deeply by metabolomic strategy and pharmacological study. The metabolomics results demonstrated that Zhishi can prevent the APAP-induced liver injury model by regulating liver metabolic disorders in glycerophospholipid metabolism, fatty acid biosynthesis and glycerolipid metabolism. Moreover, it is confirmed that Zhishi blocked apoptosis of APAP-induced BRL-3A cell by simultaneously regulating p53 up-regulated apoptosis regulator (PUMA), AMPK-SIRT1 and JNK1 signaling pathways. Our findings indicated that Zhishi exhibited a hepaprotective effect against APAP-induced liver necrosis by inhibiting the PUMA and reversing disorder of liver lipid metabolism which could assist in improving the clinical outcomes of chemical-induced liver injury.

Aqueous Partition of Methanolic Extract of Dicranopteris linearis Leaves Protects against Liver Damage Induced by Paracetamol

This study aimed to determine the antioxidant and hepatoprotective activities of semi-purified aqueous partition obtained from the methanol extract of Dicranopteris linearis (AQDL) leaves against paracetamol (PCM)-induced liver intoxication in rats. The test solutions, AQDL (50, 250, and 500 mg/kg), were administered orally to rats (n = 6) once daily for seven consecutive days followed by the hepatotoxicity induction using 3 g/kg PCM (p.o.). Blood was collected for serum biochemical parameters analysis while the liver was collected for histopathological examination and endogenous antioxidant enzymes analysis. AQDL was also subjected to antioxidant determination and phytochemical analysis. Results obtained show that AQDL possessed high total phenolic content (TPC) value and remarkable radical scavenging activities. AQDL also significantly (p < 0.05) reduced the liver weight/body weight (LW/BW) ratio or serum level of ALT, AST, and total bilirubin while significantly (p < 0.05) increase the level of superoxide dismutase (SOD) and catalase (CAT) without affecting the malondialdehyde (MDA) in the liver indicating its hepatoprotective effect. Phytoconstituents analyses showed only the presence of saponins and triterpenes, but lack of flavonoids. In conclusion, AQDL exerts hepatoprotective activity via its high antioxidant potential and ability to modulate the endogenous enzymatic antioxidant defense system possibly via the synergistic action of saponins and triterpenes.

Elevated metabolites of acetaminophen in cord blood of children with obesity

BACKGROUND

High-throughput metabolomics has been used cross-sectionally to evaluate differential metabolic profiles associated with human obesity.

OBJECTIVES

This study longitudinally assessed the cord blood metabolome to explore if metabolic signatures of obesity at age 3-5 are apparent at birth.

METHODS

In a nested case-control design, metabolomics analysis was performed on umbilical cord blood of 25 children who developed obesity by age 3-5 years, compared with 25 sex-matched non-obese children enrolled as part of an ongoing birth cohort. Logistic regression models were used to identify significant metabolites, adjusting for maternal pre-pregnancy obesity.

RESULTS

Children who had obesity by age 3-5 years had elevated levels of medium and long chain fatty acids including stearate, oleate and palmitate at birth. Children with obesity were also more likely to have elevated levels of acetaminophen metabolites at birth, specifically: 3-(N-acetyl-L-cystein-S-yl) acetaminophen, 2-hydroxyacetaminophen sulfate, 2-methoxyacetaminophen glucuronide and p-acetamidophenyl glucuronide.

CONCLUSION

Although the observed increases in lipids are consistent with previous metabolomic studies of obesity, this study is the first to report associations between acetaminophen metabolites and obesity in children; however, we lack mechanistic insights for this link. Larger human studies with longer follow-up and laboratory-controlled animal experiments are needed to clarify associations.

Development and application of a comprehensive lipidomic analysis to investigate Tripterygium wilfordii-induced liver injury

Lipid metabolic pathways play pivotal roles in liver function, and disturbances of these pathways are associated with various diseases. Thus, comprehensive characterization and measurement of lipid metabolites are essential to deciphering the contributions of lipid network metabolism to diseases or its responses to drug intervention. Here, we report an integrated lipidomic analysis for the comprehensive detection of lipid metabolites. To facilitate the characterization of untargeted lipids through fragmentation analysis, nine formulas were proposed to identify the fatty acid composition of lipids from complex MS (n) spectrum information. By these formulas, the co-eluted isomeric compounds could be distinguished. In total, 250 lipids were detected and characterized, including diacylglycerols, triacylglycerols, glycerophosphoethanolamines, glycerophosphocholines, glycerophosphoserines, glycerophosphoglycerols, glycerophosphoinositols, cardiolipins, ceramides, and sphingomyelins. Integrated with the targeted lipidomics, a total of 27 inflammatory oxylipins were also measured. To evaluate the aberrant lipid metabolism involved in liver injury induced by Tripterygium wilfordii, lipid network metabolism was further investigated. Results indicated that energy lipid modification, membrane remodeling, potential signaling lipid alterations, and abnormal inflammation response were associated with injury. Because of the important roles of lipids in liver metabolism, this new method is expected to be useful in analyzing other lipid metabolism diseases.

Data on expression of lipoxygenases-5 and -12 in the normal and acetaminophen-damaged liver

Here we present additional data on the expression of lipoxygenases -5 and -12 in the normal and acetaminophen-damaged liver, which are associated with our manuscript recently published in Chemico-Biological Interactions on lipid metabolism and eicosanoid signaling pathways involved in acetaminophen-induced liver damage in a mouse model (http://dx.doi.org/10.1016/j.cbi.2015.10.019 [1]). It has been demonstrated that the expression of lipoxygenase-5 and leukotriene formation are increased in the livers of rats with carbon tetrachloride (CCl4)-induced cirrhosis (http://dx.doi.org/10.1053/gast.2000.17831 [2]). In addition, the lipoxygenase-12 is known to be expressed in the resident macrophage population of the liver (http://dx.doi.org/10.1016/S0014-5793(99)00396-8 [3]). Mice were injected with acetaminophen, and at 48 h their livers were processed for immunohistochemistry with anti-mouse lipoxygenase-5 and -12 antibodies. At the same time point, the RNA was also extracted from the liver to assess the expression of lipoxygenase-5 and -12 genes via qPCR analysis. Our results show that lipoxygenase-5 expression, but not that of lipoxygenase-12, changes significantly in the acetominophen-damaged liver.