APAP-induced Hepatotoxicity Research Articles

RIP1 kinase inactivation protects against acetaminophen-induced acute liver injury in mice

Many studies have investigated the role of receptor-interacting protein 1 (RIP1) kinase in acetaminophen (APAP) overdose-induced acute liver injury. However, the results were not consistent and there still remain controversies. Importantly, in these previous studies, the usage of DMSO to dissolve the RIP1 kinase inhibitor Nec-1, resulted in misleading conclusion. Our study aimed to determine the role of RIP1 kinase in APAP-induced liver injury, via genetically or pharmaceutically inhibition of RIP1 kinase activity. Our results indicated that APAP-induced liver injury was significantly attenuated in RIP1 kinase-dead (Rip1K45A/K45A) mice compared to WT control. High dosage of APAP-induced mortality was also rescued by RIP1 kinase inactivation. In agreement, RIP1 kinase inhibitor, Nec-1 which was formulated with PEG400, could efficiently alleviate APAP-induced hepatotoxicity. For the underlying mechanism, our results suggested that RIP1 kinase inactivation did not influence the hepatic GSH depletion, but significantly reduced the hepatic cell death and inflammation induced by APAP treatment. Using bone marrow transplantation model, we also demonstrated that it was RIP1 kinase activity in tissue-resident hepatic cells other than hematopoietic-derived cells mainly responsible for APAP-induced liver injury. Our study confirmed the important role of RIP1 kinase activity in APAP-induced acute liver failure.

Caveolin-1 Alleviates Acetaminophen-Induced Fat Accumulation in Non-Alcoholic Fatty Liver Disease by Enhancing Hepatic Antioxidant Ability via Activating AMPK Pathway.

Non-alcoholic fatty liver disease (NAFLD) is an independent risk factor for acute liver injury caused by overuse of acetaminophen (APAP). Caveolin-1 (CAV1), a regulator of hepatic energy metabolism and oxidative stress, was found to have a protective effect against NAFLD in our previous study. However, it remains unclear whether CAV1 has a protective effect against APAP-induced hepatotoxicity in NAFLD. The aim of this study was to determine whether CAV1 inhibits oxidative stress through the AMPK/Nrf2/HO-1 pathway to protect the liver from fat accumulation exacerbated by APAP in NAFLD. In this study, seven-week-old C57BL/6 male mice (18–20 g) were raised under similar conditions for in vivo experiment. In vitro, L02 cells were treated with A/O (alcohol and oleic acid mixture) for 48 h, and APAP was added at 24 h for further incubation. The results showed that the protein expression of the AMPK/Nrf2 pathway was enhanced after CAV1 upregulation. The effects of CAV1 on fat accumulation, ROS, and the AMPK/Nrf2 anti-oxidative pathway were reduced after the application of CAV1-siRNA. Finally, treatment with compound C (an AMPK inhibitor) prevented CAV1 plasmid-mediated alleviation of oxidative stress and fat accumulation and reduced the protein level of Nrf2 in the nucleus, demonstrating that the AMPK/Nrf2/HO-1 pathway was involved in the protective effect of CAV1. These results indicate that CAV1 exerted a protective effect against APAP-aggravated lipid deposition and hepatic injury in NAFLD by inhibiting oxidative stress. Therefore, the upregulation of CAV1 might have clinical benefits in reducing APAP-aggravated hepatotoxicity in NAFLD.

Effect of betulinic acid administration on TLR-9/NF-κB /IL-18 levels in experimental liver injury

Background/aim Acetaminophen (APAP), used in the composition of thousands of preparations, is the most commonly used analgesic and antipyretic drug. The present study aimed to investigate the potential protective effects of the betulinic acid (BA) treatment through an APAP-induced hepatotoxicity rat model, using inflammatory, biochemical, and histopathological parameters. Materials and methodsThe study consisted of four groups: control group, APAP group, BA group, and APAP+BA group. Experimental studies continued for fifteen days. Serum samples were analysed for glucose, total cholesterol (TChol), triglyceride (TG), low density lipoprotein (LDL), high density lipoprotein (HDL), aspartate amino transferase (AST), malondialdehyde (MDA), toll-like receptor-9 (TLR-9), nuclear factor kappa B (NF-κB), and interleukin-18 (IL-18).ResultsTLR9, IL-18, NF-κB, and MDA levels increased significantly in liver injury groups. These increases considerably decreased by the BA treatment. All groups showed immunopositivity for 8-hydroxy-2’–deoxyguanosine (8-OHdG) and interleukin (IL-1β) in the hepatocytes, inflammatory cells, and epithelial cells of bile ducts. Conclusion BA can be used as an effective agent in the prevention and treatment of acute liver diseases due to its inhibitory properties in multiple pathways and its potent antioxidant effects.

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.

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.

Thrombospondin‐1 Inhibition Reduces Nrf2 Activity and Increases Liver Injury during Acetaminophen‐Induced Hepatotoxicity

Introduction Acetaminophen (N-Acetyl-p-Aminophenol or APAP)-induced hepatotoxicity is the most common cause of acute liver failure in the United States and Western Europe. Toxicity from APAP results from the accumulation of the toxic metabolite NAPQI, a consequence of hepatic glutathione (GSH) depletion. Therefore, pathways regulating GSH and antioxidant pathways can play a pivotal role in APAP-induced hepatotoxicity. Thrombospondin-1 (TSP1) is a homotrimeric protein that can modulate antioxidant signaling pathways and other signaling pathways involved in cell death and inflammation. Therefore, the hypothesis of this study was that TSP1 was upregulated in the liver during APAP-induced hepatotoxicity and inhibition of TSP1 can contribute to liver injury by increasing oxidative damage and hepatic cell death. Methods C57Bl/6 mice or TSP1 null mice (TSP1-/-) were administered 300 mg/kg or 600 mg/kg of APAP and were euthanized either 2-hours or 6-hours after injection. Liver injury was assessed by measuring serum ALT and AST levels as well as liver H&E and TUNEL staining. TSP1, CYP2E1, Nrf2, and SOD1 expression were assessed by real-time PCR, immunoblotting, ELISA or immunohistochemistry analyses. Liver GSH levels were measured by colorimetric assay. The GSH synthesis enzymes GCLC, GCLM and GSR were assessed by RTPCR. All data were analyzed using Graphpad Prism software with differences between two groups compared using the Student's t-test and differences between three or more groups were determined by ANOVA. Results C57Bl/6 mice administered 300 mg/kg or 600 mg/kg had a significant increase of TSP1 mRNA and protein in their livers 6-hours after injection with this effect being dose-dependent. TSP1-/- mice had a similar degree of hepatic necrosis at 2-hours and 6-hours following APAP injection compared to C57Bl/6 mice. However, TSP1-/- mice had a significant increase of serum ALT and AST levels as well as increased TUNEL staining 6-hours following APAP administration. Nrf2 and SOD1 protein expression were significantly decreased in TSP1-/-mice but not C57Bl/6 mice 6-hours after APAP injection. This was associated with decreased GSH, GCLC, GCLM and GSR in APAP-treated TSP1-/- mice compared to C57Bl/6 mice administered APAP. Conclusions Together, these data demonstrate that elimination of TSP1 protein in APAP-treated mice reduced hepatic Nrf2 expression and GSH activity leading to worse liver injury. Treatment strategies aimed at inducing Nrf2 activity or increasing TSP1 expression may be beneficial to improve outcomes during APAP-induced liver injury.

Differential expression of gut bacterial phenylalanine reductive pathway potentially modulates the host susceptibility to acetaminophen‐induced liver injury

Acetaminophen (APAP) overdose causes acute liver injury. Our previous study showed that gut microbiota modulates host susceptibility to APAP hepatotoxicity and identified a gut bacterial metabolite phenylpropionic acid (PPA) that alleviates APAP hepatotoxicity in mice. PPA levels in mouse cecum contents exhibit an excellent correlation to those in cardiac serum; inoculation of a PPA-producing gut bacterium Clostridium sporogenes into the mice with minimal cecal and systemic PPA levels significantly increased systemic PPA levels. These results strongly support the notion that gut bacterial PPA production governs PPA systemic exposure in mice. The current study aims to characterize the genetic/biochemical determinants responsible for differential PPA levels in the mouse gut. Our hypothesis is that PPA production in gut bacteria is governed via two previously reported pathways for PPA production from L-phenylalanine (L-Phe): (1) L-Phe reductive pathway catalyzed by enzymes encoded by the fld gene cluster (called Fld pathway; reported in only four different gut bacterial species) and (2) L-Phe ammonia-lyase (PAL) pathway (never reported in gut bacteria to date). LC-MS/MS analysis of mouse cecal samples revealed that L-Phe levels were not correlated with PPA levels, ruling out the role of substrate availability in differential cecal PPA levels. To examine the relative contribution of Fld and PAL pathways to PPA production in the mouse cecum, d8-L-Phe was incubated with mouse cecal bacteria, and the levels of d6- and d7-PPA (products of Fld and PAL pathways, respectively) was measured using LC-MS/MS. As a control, C. sporogenes wild-type and a mutant strain of fldC (encoding an essential subunit within the Fld pathway) were included. Significantly impaired production of d6-labeled PPA was observed in C. sporogenes fldC mutant as expected. The majority of PPA produced from mouse cecal bacteria corresponded to d6-PPA, indicating that Fld pathway is mainly responsible for PPA production under our test conditions. Interestingly, none of the previously reported fldC genes was detected in the mouse cecum by semi-quantitative PCR, suggesting the presence of gut bacteria harboring as-yet-unidentified Fld pathway in mouse cecum. Altogether, we demonstrated the Fld pathway as the major gut bacterial pathway that metabolizes L-Phe to PPA, a gut bacterial metabolite that confers protection against APAP-induced hepatotoxicity. Gut bacteria harboring unknown Fld pathways for PPA production and the role of Fld pathway in PPA cecal levels in vivo remain to be investigated.

Lavender (Lavandula officinalis) essential oil prevents acetaminophen-induced hepatotoxicity by decreasing oxidative stress and inflammatory response

Acetaminophen (N-acetyl-p-aminophenol, APAP) is the most popular drug recommended and consumed for relieving mild and moderate pain and fever. Although effective in therapeutic doses, APAP overdose induces hepatotoxicity, causing acute liver failure. In this study, the hepatoprotective effects and the underlying mechanisms of Lavandula officinalis essential oil (LEO) were investigated in APAP-induced hepatotoxicity. To evaluate the hepatoprotective effect, Balb /c mice were pretreated with LEO at doses of 200 and 400 mg/kg, once daily for seven days. On the seventh day, mice were treated with APAP (250 mg/kg) to induce hepatotoxicity. LEO significantly decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and gamma-glutamyl transferase (γ-GT) compared to the APAP group. Besides, a decrease in myeloperoxidase (MPO) activity, nitric oxide (NO), and pro-inflammatory cytokines levels were observed in liver samples of the LEO treated mice. Moreover, pretreatment with LEO showed significant antioxidant activity by decreasing the levels of malondialdehyde (MDA), carbonylated proteins, reactive oxygen species (ROS), and glutathione (GSH), in addition to increasing levels of the hepatic superoxide dismutase (SOD), catalase (CAT), and oxidized glutathione (GSSG). Our results showed that LEO improved liver functions altered by APAP by inhibiting oxidative stress and inflammatory induced by APAP and other oxidative stress-mediated toxicities.

Kushenol C Prevents Tert-Butyl Hydroperoxide and Acetaminophen-Induced Liver Injury.

Sophora flavescens, also known as Kushen, has traditionally been used as a herbal medicine. In the present study we evaluated the ameliorative effects of kushenol C (KC) from S. flavescens against tBHP (tert-Butyl hydroperoxide)-induced oxidative stress in hepatocellular carcinoma (HEPG2) cells and acetaminophen (APAP)-induced hepatotoxicity in mice. KC pretreatment protected the HEPG2 cells against oxidative stress by reducing cell death, apoptosis and reactive oxygen species (ROS) generation. KC pretreatment also upregulated pro-caspase 3 and GSH (glutathione) as well as expression of 8-Oxoguanine DNA Glycosylase (OGG1) in the HEPG2 cells. The mechanism of action was partly related by KC’s activation of Akt (Protein kinase B (PKB)) and Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) in the HepG2 cells. In in vivo investigations, coadministration of mice with KC and APAP significantly attenuated APAP-induced hepatotoxicity and liver damage, as the serum enzymatic activity of aspartate aminotransferase and alanine aminotransferase, as well as liver lipid peroxidation and cleaved caspase 3 expression, were reduced in APAP-treated mice. Coadministration with KC also up-regulated antioxidant enzyme expression and prevented the production of proinflammatory mediators in APAP-treated mice. Taken together, these results showed that KC treatment has potential as a therapeutic agent against liver injury through the suppression of oxidative stress.

A/J mice are more susceptible than C57BL/6 to acetaminophen-induced hepatotoxicity

Acetaminophen (APAP) is commonly used to treat fever and pain. However, when in overdose is the predominant cause of hepatotoxicity. Despite advances in understanding the mechanisms of APAP-induced hepatotoxicity, the management of acute liver failure remains a challenge. Thus, more relevant experimental models are crucial to provide a better understanding of this condition. The aim of this study is to evaluate the effect of APAP-induced hepatotoxicity on A/J mice using C57BL/6 as reference experimental model. Eight- to ten-week-old male A/J and C57BL/6 mice were treated with APAP (300 or 500 mg/kg) by intraperitoneal injection. After 24 h total blood leukocyte counting, plasma levels of alanine amino transferase (ALT) and aspartate amino transferase (AST), histopathological analysis of liver, lung and kidney were evaluated. A/J mice presented reduction in circulating leukocytes concomitant with the increase in plasma levels of ALT and AST, and liver necrosis when treated with 300 and 500 mg/kg of APAP. C57BL/6 mice presented similar results only with 500 mg/kg of APAP. Our results show that A/J mice have a marked susceptibility to the effects of APAP and could be considered as an experimental model to study APAP-induced toxicity.

Ginsenoside Rg3 ameliorates acetaminophen-induced hepatotoxicity by suppressing inflammation and oxidative stress.

Improper usage of acetaminophen (APAP) leads to morbidity and also mortality secondary to liver damage. Ginseng could suppress APAP-induced hepatotoxicity and ginsenoside Rg3 is a kind of major component in ginseng against liver damage. Herein, we intended to estimate the beneficial function and molecular mechanism of Rg3 on APAP-caused hepatotoxicity and identified hepatoprotection. A total of 50 C57BL/6J mice were divided into five random groups, and each contains 10 mice as the control, acetaminophen (350 mg/kg) and Rg3 (5, 10 and 20 mg/kg) + acetaminophen (350 mg/kg) groups. These mice were intragastric administration a single dose of acetaminophen by oral treatment behind pre-administered with several doses of ginsenoside Rg3 for six hours. According to our data, the injection of APAP (350 mg/kg) enhanced the basal levels of alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase and lactic dehydrogenase. However, these abnormal added were alleviated by Rg3. Moreover, Rg3 treatment obviously relieved APAP-caused inflammation and oxidant in liver tissues. The depletion of glutathione, glutathione peroxidase, total antioxidant capacity and generation of malondialdehyde induced by APAP treatment were reduced by Rg3. By H&E staining, Rg3 effectively reduced APAP-caused apoptosis and inflammatory infiltration. Moreover, Rg3 attenuated APAP-caused hepatic damage in part by regulating the pro-inflammatory and anti-inflammatory cytokines. Moreover, we found that Rg3 could bind to NLRP3 suggesting the anti-inflammatory effects of Rg3 by molecular docking study. In summary, Rg3 showed hepatic protective function in APAP-induced hepatotoxicity as evidenced by a reduction of the oxidant and the inflammatory reply, relieve of hepatocellular damage, showing potential in Rg3 as a potential therapeutic medicine to prevent hepatic injury.

Role of gambogenic acid in regulating PI3K/Akt/NF-kβ signaling pathways in rat model of acute hepatotoxicity.

The purpose of this study is to investigate the protective effect of gambogenic acid (GA) in acetaminophen (APAP)-induced hepatotoxicity in rat models. GA (10 mg/kg) was administered intraperitoneal (i.p.) to rats for 7 consecutive days followed by APAP (500 mg/kg) single dose (i.p.) on the final day after GA administration. The levels of MDA, GSH, SOD, CAT, GPx, GST, ALP, AST, ALT, proinflammatory cytokines (TNF-α, IL-1β, IL-6), apoptosis markers (caspase-3 and -9, Bax, Bcl-2), 4-hydroxynonenal (4-HNE), and prostaglandin E2 (PGE2) were evaluated. Results exhibited protective effects of GA by inhibiting inflammation, preventing oxidative stress and apoptosis in APAP-induced liver. Histopathological changes caused by APAP were attenuated, protein expressions of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) were upregulated, and nuclear factor-kappa β (NF-kβ) was downregulated by GA. In summary, GA significantly exerted anti-inflammatory and antiapoptotic effects against APAP-induced hepatotoxicity potentially through regulation of PI3K/Akt and NF-kβ signaling pathways.

A Potential Role for SerpinA3N in Acetaminophen-Induced Hepatotoxicity

Acetaminophen (APAP) is a commonly used pain and fever reliever but is also the most frequent cause of drug-induced liver injury. The mechanism pertaining acetaminophen toxicity has been well documented, whereas mechanisms of hepatotoxicity are not well established. Serine (or cysteine) peptidase inhibitor, clade A, member 3N (SerpinA3N), a serine protease inhibitor, is synthesized in the liver but the role of SerpinA3N in relation to APAP-induced liver injury is not known. Wild-type and hepatocyte-specific SerpinA3N knockout (HKO) mice were injected intraperitoneally with a single dose of PBS or APAP (400 mg/kg) for 12 hours, and markers of liver injury, cell death, and inflammation were assessed. SerpinA3N expression was highly induced in mice with APAP overdose. SerpinA3N HKO mice had diminished liver injury and necrosis as shown by lower alanine aminotransferase and interleukin-6 levels, accompanied by suppressed inflammatory cytokines and reduced neutrophil infiltration. The reduced oxidative stress was associated with enhanced antioxidant enzyme capabilities. Taken together, hepatocyte SerpinA3N deficiency reduced APAP-induced liver injury by ameliorating inflammation and modulating the 5' AMP-activated protein kinase-unc-51-like autophagy activating kinase 1 signaling pathway. Our study provides novel insights into a potential role for SerpinA3N in APAP-induced liver injury. SIGNIFICANCE STATEMENT: Our studies indicate that serine (or cysteine) peptidase inhibitor, clade A, member 3N (SerpinA3N) may have a pathophysiological role in modulating acetaminophen (APAP)-induced liver injury. More specifically, mice with hepatic deletion of SerpinA3N suppressed inflammation and liver injury to reduce APAP-induced hepatotoxicity. Controlling the inflammatory response offers possible approaches for novel therapeutics; therefore, understanding the pathophysiological role of SerpinA3N in inducing liver injury may add to the development of more efficacious treatments.

The combination of N-acetylcysteine and cyclosporin A reduces acetaminophen-induced hepatotoxicity in mice

ABSTRACT Acetaminophen (APAP)-induced hepatotoxicity is the most common cause of acute liver failure in worldwide. N-acetyl cysteine (NAC) is used as the APAP antidote. Cyclosporin A (CsA) is suppressed mitochondrial damage by binding cyclophilin, a mitochondrial pore transport component. The study aimed to evaluate the effects of NAC, CsA, and NAC+CsA treatments on APAP-induced hepatotoxicity in mice. Mice were randomly divided into five groups (n = 6). 400 mg/kg/ip/single dose APAP, 1200 mg/kg/i.p/single dose NAC and 50 mg/kg/i.p/single dose CsA were performed. Light and electron microscopic alterations were investigated in liver samples. Levels of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and liver glutathione (GSH) were analyzed. 3-nitrotyrosine and cytochrome c immunoreactivities were evaluated in liver tissue. Here, we found that APAP leads to histopathological and ultrastructural changes in mice liver. Also, APAP increased cytochrome c and 3-nitrotyrosine immunopositive staining. Besides, a significant decrease in liver GSH and an increase in serum AST and ALT levels were detected in the APAP group. Interestingly, NAC+CsA treatment improved histological alterations, cytochrome c, and 3-nitrotyrosine immunoreactivities and liver GSH, serum AST/ALT levels caused by APAP. We suggest that the combination of NAC and CsA reduces acetaminophen-induced hepatotoxicity in mice.

Comparative Studies on the Hepatoprotective Effect of White and Coloured Rice Bran Oil against Acetaminophen-Induced Oxidative Stress in Mice through Antioxidant- and Xenobiotic-Metabolizing Systems.

Rice bran oil (RBO) comprises various nutrients and phytochemicals which exhibit several health benefits. There are no studies regarding the functional effects of different colours of RBO. This study was aimed to compare the constituents and antioxidant activities of white rice bran oil (WRBO) and coloured rice bran oil (CRBO). Each RBO showed similar free fatty acid profiles. However, greater amounts of vitamin E, phytosterols, carotenoids, and chlorophylls were found in CRBO, which had lower γ-oryzanol content than WRBO. Oxidative stress was induced in male mice by an overdose of acetaminophen (APAP) at 300 mg/kg body weight. The mice were then fed with RBO at the equivalent dose to 100 mg/kg body weight of γ-oryzanol three hours later and sacrificed six hours after APAP treatment. The administration of 100 mg γ-oryzanol equivalent in CRBO ameliorated APAP-induced hepatotoxicity in mice more strongly than 100 mg γ-oryzanol equivalent in WRBO, as evidenced by the significant reduction of serum ALT, hepatocellular necrosis, and hepatic lipid peroxidation. CRBO could improve xenobiotic-metabolizing and antioxidant enzyme activities, including glutathione S-transferase, superoxide dismutase, glutathione peroxidase, and glutathione reductase, and also increase mRNA expression of various antioxidant-responsive genes. Vitamin E, phytosterols, carotenoids, and chlorophyll might be the protective compounds in CRBO that alleviate APAP-induced hepatotoxicity through the interruption of APAP metabolism and the activation of antioxidant systems at both transcriptional and enzymatic levels. These findings might provide a protective role of CRBO on oxidative stress associated with several degenerative diseases.

Vanillylacetone modulates acetaminophen induced hepatotoxicity in rats

Background: Acetaminophen (APAP) overdose is the most common type of drug-induced liver toxicity in humans. In this study, we investigated the protective mechanism of Vanillylacetone, which is the active ingredient of Ginger against APAP. Methodology: Rats were classified into four groups, and each was having six rats. Group-I was controlling, and the vehicle was given orally. Group II was toxic, and APAP was administered 2 g/kg p.o for 7 days. Group III was treating Vanillylacetone 60 mg/kg body weight given every day p.o. for 7 days. Group IV was parse and only given Vanillylacetone (60 mg/kg body weight) for 7 days. On day 8, the blood was collected, and rats were sacrificed immediately. Results: The levels of hepatic enzymes were monitored, and the result was significantly increased in Group-II (Toxic) as compared to Group-I (control). The level of these enzymes was decreased in Group-III (Toxic drug), and no changes in serum marker were observed in Group-IV compared to Group-I. The oxidative stress parameter like left posterior oblique (LPO) was also measured, and results indicated a significant increment in the content of thiobarbituric acid reactive substances (TBARS) in Group-II compared to Group-I. At the same time, the glutathione was reduced in Group-II as compared to Group-I. Still, after the treatment with Vanillylacetone, it was significantly recovered in Group-III as compared to Group-II. Thus, the outcome provides a clear picture of the protective mechanism of Vanillylacetone against APAP-induced hepatotoxicity. Conclusion: This result showed that the Vanillylacetone effectively suppresses the harmful effect of APAP on the liver due to its antioxidant properties, which had a major role in preventing the induction of hepatotoxicity.

Potential benefits of using hydrogen sulfide, vitamin E and necrostatin-1 to counteract acetaminophen‑induced hepatotoxicity in rats.

The use of acetaminophen (APAP) is increasing recently, especially with COVID-19 outbreaks. APAP is safe at therapeutic levels, however, an overdose can cause severe liver injury. This study aims to explore possible mechanisms involved in APAP‑induced hepatotoxicity and compare different hepatoprotective agents, namely vitamin E, hydrogen sulfide (H2S) and necrostatin-1 (NEC-1). Adult male albino rats were divided into groups: Control group, APAP‑induced hepatotoxicity group, Vitamin E‑treated group, H2S‑treated group and NEC-1‑treated group. Serum levels for aspartate aminotransferase (AST), alanine aminotransferase (ALT), interleukin-33 (IL-33), tumor necrosis factor alpha (TNF-α), reduced glutathione (GSH) and lipid profile were measured. Histopathological examinations of liver tissue with H(et)E stain and immunohistochemistry for activated caspase-3 were also done. APAP‑treated group showed elevated liver transaminases, hyperlipidemia, and deficient liver anti-oxidative response together with disturbed hepatic architecture and increased immune-expression of activated caspase-3 in hepatic tissue. Pretreatment with vitamin E, H2S or NEC-1 reversed the affected parameters. Vitamin E and H2S showed greater improvement when compared to NEC-1. Vitamin E, H2S and NEC-1 showed protective effects against APAP-induced hepatotoxicity, thus they may be used as an adjuvant therapy when APAP is indicated for long periods as is the case in COVID-19 patients (Tab. 2, Fig. 2, Ref. 45). Text in PDF www.elis.sk Keywords: acetaminophen, hepatotoxicity, apoptosis, necrostatin-1, vitamin E, H2S.

Oridonin Alters Hepatic Urea Cycle via Gut Microbiota and Protects against Acetaminophen-Induced Liver Injury.

Acetaminophen (APAP) hepatotoxicity is the leading cause of acute liver failure in the western world. Oridonin (OD), which is the major active ingredient of the traditional Chinese medicine Rabdosia rubescens, reportedly exerts anti-inflammatory and antioxidative effects. Here, we first find that OD protects against APAP-induced hepatotoxicity. The results of hepatic tissue-associated RNA-seq and metabolomics showed that the protective effects of OD were dependent upon urea cycle regulation. And such regulation of OD is gut microbiota partly dependent, as demonstrated by fecal microbiota transplantation (FMT). Furthermore, using 16S rRNA sequencing, we determined that OD significantly enriched intestinal Bacteroides vulgatus, which activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway to regulate redox homeostasis against APAP by urea cycle. In conclusion, our study suggests that the Bacteroides vulgatus-urea cycle-Nrf2 axis may be a potential target for reducing APAP-induced liver injury, which is altered by OD.

Protective Role of microRNA-31 in Acetaminophen-Induced Liver Injury: A Negative Regulator of c-Jun N-Terminal Kinase (JNK) Signaling Pathway

Background & AimsSustained c-Jun N-terminal kinase (JNK) activation plays a major role in drug-induced liver injury (DILI). Stress-responsive microRNA-31 (miR-31) has been implicated in regulating different cellular damage, and JNK activation could induce miR-31 expression. However, the regulatory role of miR-31 in DILI has not been studied previously. We aimed to investigate whether miR-31 could ameliorate DILI and ascertain potential molecular mechanism.MethodsmiR-31 gene knockout (31-KO) and wild-type C57BL/6J mice were used to construct an acetaminophen (APAP)-induced DILI model. Primary mouse hepatocytes, as well as alpha mouse liver 12 (AML-12) cell lines, were used for in vitro experiments. Argonaute 2–associated RNA immunoprecipitation combined with high-throughput sequencing were performed to identify specific targets of miR-31.Results31-KO mice showed a higher mortality rate, liver transaminase levels, and hepatic necrosis compared with those in wild-type mice after APAP-induced hepatotoxicity. The protective role of miR-31 on hepatocytes has been analyzed via constructing bone marrow chimeric mice. Mechanistically, we found that hepatic JNK phosphorylation increased significantly in 31-KO mice. This caused mitochondrial phosphorylated Src (p-Src) inactivation and more reactive oxygen species production, which directly amplifies hepatocyte necrotic cell death, while administration of JNK-specific inhibitor SP600125 could abrogate the differences. Moreover, bioinformatics analysis of RNA immunoprecipitation combined with high-throughput sequencing identified that guanosine triphosphatase, cell division cycle protein 42 (Cdc42), the upstream molecule of JNK signaling, was the specific target of miR-31 and could form a miR-31/Cdc42/phosphorylated mixed-lineage kinase 3 (p-MLK3) negative feedback loop to restrict JNK overactivation. Clinically, both miR-31 and phosphorylated JNK (p-JNK) were highly increased in liver tissues of DILI patients with different etiologies.ConclusionsmiR-31 can down-regulate Cdc42 to restrict overactivation of reactive oxygen species/JNK/mitochondria necrotic death loop in hepatocytes of APAP-induced DILI, which might provide a new therapeutic target for alleviating JNK overactivation–based liver injury.

Kaempferol suppresses acetaminophen-induced liver damage by upregulation/activation of SIRT1

Context Kaempferol, a flavonoid glycoside, has many hepatoprotective effects in several animals due to its antioxidant potential. Objective This study evaluated the hepatoprotective effect of kaempferol against acetaminophen (APAP)-induced liver damage and examined whether the protection involved modulation of silent information regulator 1 (SIRT1) signalling. Materials and methods Adult male Wistar rats were classified into four groups (n = 8) and treated as follows: control + normal saline (vehicle), control + kaempferol (250 mg/kg), APAP (800 mg/kg, a single dose) and APAP + kaempferol. Kaempferol was administered for the first seven days followed by administration of APAP. The study was ended 24 h after APAP administration. Results At the histological level, kaempferol reduced liver damage in APAP-treated rats. It also reduced the hepatic levels of TNF-α (66.3%), IL-6 (38.6%) and protein levels of caspase-3 (88.2%), and attenuated the increase in circulatory serum levels of ALT (47.6%), AST (55.8%) and γ-GT (35.2%) in APAP-treated rats. In both the controls and APAP-treated rats, kaempferol significantly increased the hepatic levels of glutathione (GSH) and superoxide dismutase, suppressed MDA and reactive oxygen species (ROS) levels, increased protein levels of Bcl-2 and downregulated protein levels of Bax and cleaved Bax. Concomitantly, it reduced the expression of CYP2E1, and the activity and protein levels of SIRT1. Consequently, it decreased the acetylation of all SIRT1 targets including PARP1, p53, NF-κB, FOXO-1 and p53 that mediate antioxidant, anti-inflammatory and anti-apoptotic effects. Discussion and conclusions This study encourages the use of kaempferol in further clinical trials to treat APAP-induced hepatotoxicity.