Mechanisms of drug-induced liver disease

Dibenzocyclooctadiene lignans from the family Schisandraceae: A review of phytochemistry, structure-activity relationship, and hepatoprotective effects

Liver injury is a common pathological process characterized by massive degeneration and abnormal death of liver cells. With increase in dead cells and necrosis, liver injury eventually leads to nonalcoholic fatty liver disease (NAFLD), hepatic fibrosis, and even hepatocellular carcinoma (HCC). Consequently, it is necessary to treat liver injury and to prevent its progression. The drug Bicylol is widely employed in China to treat chronic hepatitis B virus (HBV) and has therapeutic potential for liver injury. It is the derivative of dibenzocyclooctadiene lignans extracted from Schisandra chinensis (SC). The Schisandraceae family is a rich source of dibenzocyclooctadiene lignans, which possesses potential liver protective activity. This study aimed to comprehensively summarize the phytochemistry, structure-activity relationship and molecular mechanisms underlying the liver protective activities of dibenzocyclooctadiene lignans from the Schisandraceae family. Here, we had discussed the analysis of absorption or permeation properties of 358 compounds based on Lipinski's rule of five. So far, 358 dibenzocyclooctadiene lignans have been reported, with 37 of them exhibited hepatoprotective effects. The molecular mechanism of the active compounds mainly involves antioxidative stress, anti-inflammation and autophagy through Kelch-like ECH-associating protein 1/nuclear factor erythroid 2 related factor 2/antioxidant response element (Keap1/Nrf2/ARE), nuclear factor kappa B (NF-кB), and transforming growth factor β (TGF-β)/Smad 2/3 signaling pathways. This review is expected to provide scientific ideas for future research related to developing and utilizing the dibenzocyclooctadiene lignans from Schisandraceae family.

The Role of Endoplasmic Reticulum Stress Response in Liver Regeneration

Exposure to hepatotoxic chemicals is involved in liver disease-related morbidity and mortality worldwide. The liver responds to damage by triggering compensatory hepatic regeneration. Physical agent or chemical-induced liver damage disrupts hepatocyte proteostasis, including endoplasmic reticulum (ER) homeostasis. Post-liver injury ER experiences a homeostatic imbalance, followed by active ER stress response signaling. Activated ER stress response causes selective upregulation of stress response genes and downregulation of many hepatocyte genes. Acetaminophen overdose, carbon tetrachloride, acute and chronic alcohol exposure, and physical injury activate the ER stress response, but details about the cellular consequences of the ER stress response on liver regeneration remain unclear. The current data indicate that inhibiting the ER stress response after partial hepatectomy-induced liver damage promotes liver regeneration, whereas inhibiting the ER stress response after chemical-induced hepatotoxicity impairs liver regeneration. This review summarizes key findings and emphasizes the knowledge gaps in the role of ER stress in injury and regeneration.

Stellate cell in hepatic inflammation and acute injury

The perisinusoidal hepatic stellate cells (HSCs) have been investigated extensively for their role as the major fibrogenic cells during chronic liver injury. HSCs also produce numerous cytokines, chemokines, and growth mediators, and express cell adhesion molecules constitutively and in response to stimulants such as endotoxin (lipopolysaccharide). With this property and by interacting with resident and recruited immune and inflammatory cells, HSCs regulate hepatic immune homeostasis, inflammation, and acute injury. Indeed, experiments with HSC-depleted animal models and cocultures have provided evidence for the prominent role of HSCs in the initiation and progression of inflammation and acute liver damage due to various toxic agents. Thus HSCs and/or mediators derived thereof during acute liver damage may be considered as potential therapeutic targets.

In Vitro and In Vivo Metabolic Activation of Tolterodine Mediated by CYP3A

Tolterodine (TOL) is an antimuscarinic drug used for the treatment of patients with overactive bladder presenting urinary frequency, urgency, and urge incontinence. During the clinical use of TOL, adverse events such as liver injury took place. The present study aimed at the investigation of the metabolic activation of TOL possibly associated with its hepatotoxicity. One GSH conjugate, two NAC conjugates, and two cysteine conjugates were found in both mouse and human liver microsomal incubations supplemented with TOL, GSH/NAC/cysteine, and NADPH. The detected conjugates suggest the production of a quinone methide intermediate. The same GSH conjugate was also observed in mouse primary hepatocytes and in the bile of rats receiving TOL. One of the urinary NAC conjugates was observed in rats administered TOL. One of the cysteine conjugates was found in a digestion mixture containing hepatic proteins from animals administered TOL. The observed protein modification was dose-dependent. CYP3A primarily catalyzes the metabolic activation of TOL. Ketoconazole (KTC) pretreatment reduced the generation of the GSH conjugate in mouse liver and cultured primary hepatocytes after TOL treatment. In addition, KTC reduced the susceptibility of primary hepatocytes to TOL cytotoxicity. The quinone methide metabolite may be involved in TOL-induced hepatotoxicity and cytotoxicity.

Procyanidins Ameliorate Acetaminophen-induced Acute Liver Injury via Activating the Nrf-2/SOD-1 Signal Pathway

Background and Objectives

An overdose of acetaminophen (APAP) usually leads to acute liver injury, and oxidative stress is one of the fundamental mechanisms used to characterize it. Procyanidins (PCs) can reduce the oxidative stress in the liver of mice. This study aimed to investigate the potential protective role of PCs against APAP-induced acute liver injury.

Materials and Methods

Experiments were performed on male Kunming mice in six groups: phosphate-buffered saline, PCs, APAP, and PCs pretreated with 10, 50, and 100 mg/kg. The mice were peritoneally injected with PCs 30 min before the administration of APAP. First, survival rates of mice were scored every 12 hr for three days in succession. Furthermore, serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (T-Bil), total cholesterol (TC), triglyceride (TG), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-1 (IL-6) were determined. Additionally, histological analysis and hepatic oxidative stress including the levels of superoxide dismutase (SOD), malondialdehyde (MDA), and glutathione (GSH) were assessed. Finally, the protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and SOD-1 was detected by Western blotting.

Results

The data indicated that PCs improved survival rates of APAP-induced liver injury in mice models. Moreover, PCs could reduce the elevated serum levels of ALT, AST, T-Bil, TC, TG, TNF-α, IL-1β, and IL-6 due to APAP exposure with a dose-dependent manner. Besides, PCs pretreatment attenuated hepatic histopathological damage and oxidative stress which manifested the increases of SOD and GSH, whereas the decrease of MDA. Furthermore, PCs enhanced the protein expression of Nrf2 and SOD-1 in the PCs pretreatment groups compared with the APAP group.

Conclusion

PCs ameliorated APAP-induced acute liver injury, and Nrf2 signaling pathway modulating antioxidative stress might be involved in it.

Endotoxin-Stimulated Hepatic Stellate Cells Augment Acetaminophen-Induced Hepatocyte Injury

Acetaminophen (APAP)-induced liver injury is influenced by inflammatory Gram-negative bacterial endotoxin [lipopolysaccharide (LPS)], mechanisms of which are not completely understood. Because LPS-stimulated perisinusoidal hepatic stellate cells (HSCs) produce cytokines that affect survival of hepatocytes, this study investigated their role in APAP-induced liver injury. Fed (nonstarved) rats were administered 5 mg/kg LPS or phosphate-buffered saline (PBS) vehicle, followed by 200 mg/kg APAP or PBS an hour later, and euthanized at 6 hours. Control rats received PBS at both time points. Both LPS and APAP caused mild hepatocyte injury (apoptosis), as assessed by histopathology, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining, and caspase-3 activation. The liver injury was augmented in rats administered LPS + APAP, in association with increased nuclear translocation of interferon-regulatory factor-1 (IRF1). In vitro, APAP augmented LPS/HSC-conditioned medium-induced inhibition of DNA and protein synthesis, apoptosis, and nuclear IRF1 in hepatocytes. LPS-stimulated HSCs produced interferon-β (IFN-β), and LPS/HSC + APAP-induced hepatocyte apoptosis was inhibited by anti-IFN-β antibody. Finally, HSC-depleted mice produced significantly lower IFN-β and tumor necrosis factor-α, exhibited less oxidative stress, and were protected from excessive injury due to high APAP dose (600 mg/kg), as well as LPS (5 mg/kg overnight) followed by APAP. In co-culture with or without LPS, HSCs increased expression of proinflammatory cytokines by Kupffer cells. These results suggest that HSCs play a critical role in APAP-induced liver injury without or with LPS preconditioning, and it involves INF-β-IRF1 signaling.

Metabolic Activation of Perampanel Mediated by CYP1A2

Perampanel (PRP), a noncompetitive α-amino-3-hydroxy-5-methyl-4-isoxazolepropanoic acid (AMPA) receptor antagonist with high selectivity, has been used as a new adjuvant for the treatment of fractional seizures with or without primary generalized tonic-clonic seizures and secondary generalized seizures in epilepsy patients over the age of 12. Adverse events such as liver injury have been reported during the clinical application of PRP. The purpose of the study is to explore the in vitro and in vivo metabolic activation of PRP. Two GSH conjugates were detected in rat liver microsomal incubations containing PRP, GSH, and NADPH. The two GSH conjugates were both obtained from the bile of rats and rat primary hepatocytes after exposure to PRP. Similar microsomal incubations complemented with N-acetylcysteine (NAC) in place of GSH offered two NAC conjugates. As expected, the NAC conjugates were detected in the urine of PRP-treated rats. One of the two NAC conjugates was identified as NAC conjugate 12 verified by chemical synthesis. The individual human recombinant P450 enzyme incubation assay demonstrated that CYP1A2 dominated the catalysis for the metabolic activation of PRP. Pretreatment with α-naphthoflavone (NTF) decreased the formation of PRP-derived GSH conjugates in both livers of rats and cultured primary hepatocytes after being treated with PRP. Additionally, NTF was found to decrease the susceptibility of primary hepatocytes to the cytotoxicity of PRP. The findings indicate that PRP was metabolized to the corresponding epoxide, which could participate in PRP-induced cytotoxicity.

Metabolic Activation and Cytotoxicity of Labetalol Hydrochloride Mediated by Sulfotransferases

Labetalol hydrochloride (LHCl), an α- and β-adrenoreceptor blocker, is widely used for the treatment of hypertension as well as angina pectoris. Previous reports have demonstrated the adverse events during clinical application of LHCl, such as liver injury and acute renal failure. The present study aimed to investigate metabolic activation of LHCl to initiate the elucidation of the mechanisms of its liver toxicity. One glutathione (GSH) conjugate was detected in rat and human primary hepatocytes as well as bile of rats after exposure to LHCl. The GSH conjugate was chemically synthesized and characterized by Q-TOF and ¹H NMR. Pretreatment of 2,6-dichloro-4-nitrophenol (DCNP), a broad-spectrum sulfotransferase (SULT) inhibitor, significantly attenuated the formation of the GSH conjugate in LHCl-treated hepatocytes and animals, indicating the participation of SULTs in metabolic activation of LHCl. Moreover, pretreatment with DCNP displayed significant protection against the observed cytotoxicity in rat primary hepatocytes, which suggests a correlation of the bioactivation of LHCl mediated by SULTs with LHCl-induced hepatotoxicity.

[Once upon a time the hepatotoxicity…]

The liver ensures a large part of xenobiotics metabolism thanks to its sizeable enzymatic equipment, its anatomical localization and its abundant vascularization. However, these various characteristics also make it a privileged target for toxic compounds, particularly in the case of a toxic metabolism. Xenobiotics-induced hepatotoxicity is a major cause of liver damage and a real challenge for clinicians, pharmaceutical industry, and health agencies. Intrinsic, i.e. predictable and reproducible hepatotoxicities occurring at threshold doses are distinguished from idiosyncratic hepatotoxicities, occurring in an unpredictable manner in people with individual susceptibilities. Among them, idiosyncratic immune-mediated hepatotoxicity pathophysiology is still unclear. However, the development of tools to improve the prediction and understanding of these disorders may open avenues to the identification of risk factors and new mechanisms of toxicity.

Exogenous activation of toll-like receptor 5 signaling mitigates acetaminophen-induced hepatotoxicity in mice

Acetaminophen (APAP) poisoning is the most common cause of drug-induced acute liver injury (ALI). Our results showed that toll-like receptor 5 (TLR5) was abundantly expressed in hepatocytes and dramatically downregulated in the toxic mouse livers. Hence, we herein investigated the role of TLR5 signaling after APAP overdose. Mice were intraperitoneally (i.p.) injected with APAP to induce ALI, and then injected with flagellin at one hour after APAP administration. Flagellin attenuated APAP-induced ALI based on decreased histopathologic lesions, serum biochemical, oxidative stress, and inflammation. Furthermore, the protective effects of flagellin were abolished by TH1020 (a TLR5 antagonist) treatment. These results suggest that flagellin exerted protective effects on ALI via TLR5 activation. Mechanistically, flagellin injection promoted the translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) to the nucleus in hepatocytes. Consistent with the in vivo results, flagellin increased the activation of Nrf2 in hepatocytes, resulting in decreased APAP toxicity. ML385, a selective inhibitor of Nrf2, abolished the flagellin-mediated hepatoprotective effects in damaged livers and hepatocytes. Additionally, the flagellin-induced Nrf2 translocation was dependent upon the activation of TLR5-JNK/p38 pathways. These findings suggest that TLR5 signaling-induced Nrf2 activation, at least partially, contributed to the protection against APAP-induced ALI by flagellin treatment.

Cardamonin Reduces Acetaminophen-Induced Acute Liver Injury in Mice via Activating Autophagy and NFE2L2 Signaling

Cardamonin (CD), a naturally occurring chalcone derived from the Alpinia species, has been shown to exert antioxidant and anti-inflammatory activity, but its role in the prevention of acetaminophen- (APAP-) induced hepatotoxicity remains elusive. The objective of this study was to determine the protective effects of CD against APAP-induced acute liver injury (ALI) and the underlying mechanisms. Wild-type or transcription factor nuclear factor erythroid 2-related factor 2- (NFE2L2-) deficient mice were treated with CD (50 or 100 mg/kg, i.p.) or vehicle for 24 h. Subsequently, these mice were challenged with APAP (400 mg/kg, i.p.) for 6 h. Liver and blood samples were collected to evaluate liver injury and protein abundance. Treatment with CD significantly reduced APAP-induced hepatotoxicity. Furthermore, CD effectively reduced APAP-induced inflammation by inhibiting high mobility group box 1 (HMGB1), toll-like receptor 4 (TLR4), and NOD-like receptor protein 3 (NLRP3) signaling. In addition, CD induced activation of sequestosome 1 (p62) and NFE2L2 signaling and facilitated autophagy. By applying autophagy inhibitor 3-methyladenine (3-MA; 20 mg/kg, i.p.), further mechanistic exploration revealed that NFE2L2 deficiency promoted autophagic activity induced by CD treatment, which was conducive to the hepatoprotective effect of CD against APAP-induced hepatoxicity in NFE2L2^−/− mice. Overall, data suggest that CD has hepatoprotective effect against APAP-induced ALI, which might contribute to the activation of NFE2L2 and autophagy.

Metabolic profiling of norepinephrine reuptake inhibitor atomoxetine

Atomoxetine (ATX), a selective and potent inhibitor of the presynaptic norepinephrine transporter, is used mainly to treat attention-deficit hyperactivity disorder. Although multiple adverse effects associated with ATX have been reported including severe liver injuries, the mechanisms of ATX-related toxicity remain largely unknown. Metabolism frequently contributes to adverse effects of a drug through reactive metabolites, and the bioactivation status of ATX is still not investigated yet. Here, we systematically investigated ATX metabolism, bioactivation, species difference in human, mouse, and rat liver microsomes (HLM, MLM, and RLM) and in mice using metabolomic approaches as mice and rats are commonly used animal models for the studies of drug toxicity. We identified thirty one ATX metabolites and adducts in LMs and mice, 16 of which are novel. In LMs, we uncovered two methoxyamine-trapped aldehydes, two cyclization metabolites, detoluene-ATX, and ATX-N-hydroxylation for the first time. Detoluene-ATX and one cyclization metabolite were also observed in mice. Using chemical inhibitors and recombinant CYP enzymes, we demonstrated that CYP2C8 and CYP2B6 mainly contribute to the formation of aldehyde; CYP2D6 is the dominant enzyme for the formation of ATX cyclization and detoluene-ATX; CYP3A4 is major enzyme responsible for the hydroxylamine formation. The findings concerning aldehydes should be very useful to further elucidate the mechanistic aspects of adverse effects associated with ATX from metabolic angles. Additionally, the species differences for each metabolite should be helpful to investigate the contribution of specific metabolites to ATX toxicity and possible drug-drug interactions in suitable models.

Hepatoprotective effects of Gamisoyo-san against acetaminophen-induced liver injuries

Background

Acetaminophen (N-acetyl-p-aminophenol, APAP) is a safe and effective analgesic at therapeutic dosage. However, APAP overdose is a major cause of acute liver injury. Gamisoyo-san (GMSYS; Jiaweixiaoyao-san in Chinese, Kamishoyo-san in Japanese), a traditional herbal formula, is used to treat phlegm and cough in Korea. The purpose of this study was to investigate the hepatoprotective effect of GMSYS against APAP-induced liver injury in vitro and in vivo.

Methods

We evaluated the effect of GMSYS on APAP-induced hepatotoxicity by measuring cell viability in murine BNL CL.2 liver cells. Additionally, BALB/c mice were orally administered with GMSYS once daily for 7 days. Eighteen hours after the last administration, mice were intraperitoneally injected with 200 mg/kg APAP. Plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, hepatic antioxidants, and histological changes were examined.

Results

Pretreatment with GMSYS attenuated the decrease in cell viability induced by APAP in BNL CL.2 cells. In mice, pre-administration with GMSYS alleviated APAP-induced hepatotoxicity by decreasing plasma ALT and AST activities and hepatic malondialdehyde, and by increasing the total glutathione (GSH)/reduced GSH ratio and the activities of several antioxidants such as superoxide dismutase, catalase, GSH peroxidase, GSH reductase, GSH-S-transferase, and heme oxygenase-1.

Conclusion

GMSYS has a protective effect against APAP-induced acute liver injury by decreasing plasma transaminases and increasing antioxidants. GMSYS may be an effective candidate for the prevention of acute liver injury.

Computational Models Using Multiple Machine Learning Algorithms for Predicting Drug Hepatotoxicity with the DILIrank Dataset

Drug-induced liver injury (DILI) remains one of the challenges in the safety profile of both authorized and candidate drugs, and predicting hepatotoxicity from the chemical structure of a substance remains a task worth pursuing. Such an approach is coherent with the current tendency for replacing non-clinical tests with in vitro or in silico alternatives. In 2016, a group of researchers from the FDA published an improved annotated list of drugs with respect to their DILI risk, constituting “the largest reference drug list ranked by the risk for developing drug-induced liver injury in humans” (DILIrank). This paper is one of the few attempting to predict liver toxicity using the DILIrank dataset. Molecular descriptors were computed with the Dragon 7.0 software, and a variety of feature selection and machine learning algorithms were implemented in the R computing environment. Nested (double) cross-validation was used to externally validate the models selected. A total of 78 models with reasonable performance were selected and stacked through several approaches, including the building of multiple meta-models. The performance of the stacked models was slightly superior to other models published. The models were applied in a virtual screening exercise on over 100,000 compounds from the ZINC database and about 20% of them were predicted to be non-hepatotoxic.

Fisetin Prevents Acetaminophen-Induced Liver Injury by Promoting Autophagy

Acetaminophen (APAP) overdose is a leading cause of drug-induced acute liver failure in clinical and hospital settings. Fisetin (FST) is a phenolic compound derived from natural products such as fruit and vegetables. Our research investigated the protective mechanisms of FST in APAP-induced hepatic injury in vitro and vivo. Assessment of mouse serum levels of alanine/aspartate aminotransferases (ALT/AST), liver myeloperoxidase (MPO) activity, malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species (ROS) demonstrated the protective effects of FST toward APAP-induced liver injury. FST also reversed an APAP-induced decrease in mouse L-02 cell line viability. Our results also showed that FST significantly promoted APAP-induced autophagy and inhibited inflammasome activation both in vivo and in vitro. We also found that silencing ATG5, using si-ATG5, reduced the protective effects of FST against APAP-induced hepatotoxicity and reversed the effects on autophagy. Finally, we used the autophagy inhibitor, 3-methyladenine (3-MA) to validate the involvement of autophagy in FST against APAP-induced hepatotoxicity in vitro. We demonstrated that FST prevented APAP-induced hepatotoxicity by increasing ATG5 expression, thereby promoting autophagy and inhibiting inflammasome activation.

Acute Liver Injury in a Patient Treated With Rosuvastatin: A Rare Adverse Effect

Drug-induced liver injury (DILI) is among the challenging liver conditions encountered by clinicians today. It has a low incidence in the general population with an approximated annual incidence of 10 - 15 cases per 10,000 - 100,000 persons who have taken prescription medications. Nevertheless, DILI remains the most frequent cause of acute liver injury in the United States. Rosuvastatin is a commonly prescribed medication that, similar to other statins, is associated with serum aminotransferase elevations that are mild, asymptomatic and usually self-limited. Here, we report a case of a man who developed acute liver injury after taking rosuvastatin for hypercholesterolemia treatment. Moreover, DILI with autoimmune features represents a key subgroup of hepatotoxicity attributable to medication exposure. Similar to idiopathic autoimmune hepatitis, circulating autoantibodies and a hypergammaglobulinemia are often present in the serum of such individuals. However, such findings are not invariable. In the case reported here, these laboratory features were absent, but a liver biopsy demonstrated interface hepatitis with a prominent plasma cell infiltrate, histologic components consistent with an immune-mediated drug reaction. After withdrawal of the offending medication did not result in complete resolution, corticosteroid therapy was administered with a subsequent clinical response, confirming the diagnosis.

Liver involvement in the drug reaction, eosinophilia, and systemic symptoms syndrome

First described in 1996, the drug reaction, eosinophilia, and systemic symptoms syndrome (DReSS) is considered, along with Stevens-Johnson syndrome and toxic epidermal necrolysis, a severe cutaneous drug reaction. It is characterized by the presence of a maculopapular erythematous skin eruption, fever, lymphadenopathy, influenza-like symptoms, eosinophilia, and visceral involvement such as hepatitis, pneumonitis, myocarditis, pericarditis, nephritis, and colitis. The prognosis of patients with DReSS is related to the severity of visceral involvement. The mortality ranges from approximately 5% to 10%, and death is mainly due to liver failure, which is also the organ most commonly involved in this syndrome. Although it was previously hypothesized in 1994, DReSS syndrome can lead to reactivation of one or more human herpesvirus family members. Now being included as diagnostic criteria in a proposed diagnostic score system, this reactivation can be detected up to 2-3 wk after DReSS syndrome onset. Other causes of mortality in DReSS syndrome include myocardial or pulmonary lesions and hemophagocytosis. We reviewed the literature of previously reported case-series of DReSS and liver involvement, highlighting the pattern of liver damage, the treatment used, and the outcome.

Platycodin D protects acetaminophen-induced hepatotoxicity by inhibiting hepatocyte MAPK pathway and apoptosis in C57BL/6J mice

The root of Platycodon grandiflorus (Jacq.) A. DC. (P. grandiflorus), Platycodonis Radix, has been commonly applied to prevent and treat human diseases including bronchitis, asthma and excessive phlegm. Platycodin D (PD), one of the most important therapeutic components of P. grandiflorus, has been reported to possess protective effect against alcohol and carbon tetrachloride induced hepatotoxicity. In this study, we examined the protective efficacy of PD on acetaminophen (APAP)-induced liver injury and possible underlying mechanisms in C57BL/6J mice. Administration of PD prior to APAP intoxication significantly ameliorated the increase in serum transferases, interleukin 1β (IL-1β), IL-6, tumor necrosis factor alpha (TNF-α), and hepatic malondialdehyde (MDA) and the depletion of glutathione (GSH) in mice. PD pretreatment decreased the expression of heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NF-κB) in presence of APAP. Moreover, PD treatment noticeably reduced APAP-induced hepatocyte necrosis and apoptosis evidenced by evaluating physiological and histological hepatocyte changes in mice. Finally, PD pretreatment significantly diminished c-Jun NH₂-terminal kinase (JNK), extracellular signal-regulated kinases 1 and 2 (ERK1/2), and p38 phosphorylation induced by APAP. Collectively, PD pretreatment effectively protects hepatocytes against APAP-induced hepatotoxicity in mice through ameliorating oxidative stress, inflammatory response, and hepatocyte apoptosis.

A case of acute liver failure due to carfilzomib in multiple myeloma

WHAT IS KNOWN AND STUDY OBJECTIVE

Carfilzomib is a newer drug approved for the treatment of relapsing and refractory multiple myeloma. It has been rarely associated with acute liver failure (ALF).

CASE SUMMARY

We present a case of 58-year-old man presenting with abnormal liver function tests and subsequently diagnosed with ALF due to carfilzomib. Liver enzymes improved significantly after discontinuation of the drug.

WHAT IS NEW AND CONCLUSION

Even though ALF due to carfilzomib has been documented rarely in clinical studies, no detailed case report has been published so far. Patients on carfilzomib should be monitored for ALF, and prompt discontinuation of drug is necessary in such cases.

Evaluation of multikinase inhibitor LDN193189 induced hepatotoxicity in teleost fish Poecilia latipinna

Currently, scientists show keen interest in the drugs that inhibit multiple kinases, LDN193189, being an example. It combats certain cancers in vitro as well as in vivo, making it a prerequisite for researchers to study the toxic potential of this drug in animal models. As most of the drugs metabolized by liver cause hepatic injury, LDN193189-induced hepatotoxicity was examined using a teleost fish, Poecilia latipinna. As a prelude, calculation of LD₅₀ showed a value of 95.22 mg/kg body weight and three doses were decided based on it for further evaluations. All these groups were tested for antioxidant enzyme levels and were significantly raised for mid- and high-dose group. Similar trend was recorded for ALP, AST, and ALT levels. Furthermore, some key indicators of drug metabolism in liver were tested for their expression in response to LDN193189 treatment. Among these, Cyt-C, CYP3A4, CYP1B1 and CYP1A1 were elevated in mid- and high dose, except CYP21A1, which declined remarkably. Moreover, histological profile of the liver reflected high degree of inflammation due to drug treatment, but this was found only at high dose. In summary, LDN193189, at 2.5 mg/kg body weight, did not cause any adverse hepatotoxicity, rendering it safe for use as an anti-proliferative agent - an activity for which it has already shown promising results in the same animal model. The low-dose group previously studied for its anti-proliferative property showed no adverse effect in liver, whereas the mid- and high dose induced moderate or severe hepatotoxicity in P. latipinna.

Influence of Methylprednisolone Pulse Therapy on Liver Function in Patients with Graves' Orbitopathy

PURPOSE

Intravenous methylprednisolone (IVMP) pulse therapy is the first-line treatment in active moderate-to-severe Graves' orbitopathy (GO) and dysthyroid optic neuropathy (DON). One of the adverse effects of this therapy is liver dysfunction that can be mild (ALT < 100 U/L), moderate (ALT: 100-300 U/L), and severe defined as acute liver injury (ALI) (ALT > 300 U/L). ALI can be irreversible and fatal. The aim of the study was to evaluate the influence of two different schemes of therapy with IVMP in moderate-to-severe GO and DON on biochemical liver parameters.

MATERIALS AND METHODS

49 patients with moderate-to-severe GO were treated with IVMP in every week schedule (cumulative dose 4.5 g), and 19 patients with DON received 3.0 g IVMP (1.0 g/day for 3 consecutive days). AST, ALT, and total bilirubin were measured before treatment and after IVMP in the following selected pulses: after 0.5 g (A1), 3.0 g (A2), and 4.5 g (A3) in the group with moderate-to-severe GO and after 3.0 g IVMP in the group with DON (B1).

RESULTS

We observed a statistically higher level of AST and ALT after therapy with 3.0 g of IVMP (B1) than after 0.5 g (A1), 3.0 g (A2), and 4.5 g of IVMP (A3). Mild elevation of ALT was found in 4% and 11% of patients with moderate-to-severe GO and DON, respectively. Moderate elevation of ALT was found in 0% and 21% of patients with moderate-to-severe GO and DON, respectively. There were no cases of ALI.

CONCLUSION

Therapy of GO with higher doses (1.0 g) of IVMP in consecutive days is associated with higher risk of liver damage than treatment with moderate doses (≤0.5 g) in every week schedule. This trial is registered with NCT03667157.

Establishment of a novel hepatocyte model that expresses four cytochrome P450 genes stably via mammalian-derived artificial chromosome for pharmacokinetics and toxicity studies

The utility of HepG2 cells to assess drug metabolism and toxicity induced by chemical compounds is hampered by their low cytochrome P450 (CYP) activities. To overcome this limitation, we established HepG2 cell lines expressing major CYP enzymes involved in drug metabolism (CYP2C9, CYP2C19, CYP2D6, and CYP3A4) and CYP oxidoreductase (POR) using the mammalian-derived artificial chromosome vector. Transchromosomic HepG2 (TC-HepG2) cells expressing four CYPs and POR were used to determine time- and concentration-dependent inhibition and toxicity of several compounds by luminescence detection of CYP-specific substrates and cell viability assays. Gene expression levels of all four CYPs and POR, as well as the CYP activities, were higher in TC-HepG2 clones than in parental HepG2 cells. Additionally, the activity levels of all CYPs were reduced in a concentration-dependent manner by specific CYP inhibitors. Furthermore, preincubation of TC-HepG2 cells with CYP inhibitors known as time-dependent inhibitors (TDI) prior to the addition of CYP-specific substrates determined that CYP inhibition was enhanced in the TDI group than in the non-TDI group. Finally, the IC50 of bioactivable compound aflatoxin B1 was lower in TC-HepG2 cells than in HepG2 cells. In conclusion, the TC-HepG2 cells characterized in the current study are a highly versatile model to evaluate drug-drug interactions and hepatotoxicity in initial screening of candidate drug compounds, which require a high degree of processing capacity and reliability.

miRNA-122 Protects Mice and Human Hepatocytes from Acetaminophen Toxicity by Regulating Cytochrome P450 Family 1 Subfamily A Member 2 and Family 2 Subfamily E Member 1 Expression

Acetaminophen toxicity is a leading cause of acute liver failure (ALF). We found that miRNA-122 (miR-122) is down-regulated in liver biopsy specimens of patients with ALF and in acetaminophen-treated mice. A marked decrease in the primary miR-122 expression occurs in mice on acetaminophen overdose because of suppression of its key transactivators, hepatocyte nuclear factor (HNF)-4α and HNF6. More importantly, the mortality rates of male and female liver-specific miR-122 knockout (LKO) mice were significantly higher than control mice when injected i.p. with an acetaminophen dose not lethal to the control. LKO livers exhibited higher basal expression of cytochrome P450 family 2 subfamily E member 1 (CYP2E1) and cytochrome P450 family 1 subfamily A member 2 (CYP1A2) that convert acetaminophen to highly reactive N-acetyl-p-benzoquinone imine. Upregulation of Cyp1a2 primary transcript and mRNA in LKO mice correlated with the elevation of aryl hydrocarbon receptor (AHR) and mediator 1 (MED1), two transactivators of Cyp1a2. Analysis of ChIP-seq data in the ENCODE (Encyclopedia of DNA Element) database identified association of CCCTC-binding factor (CTCF) with Ahr promoter in mouse livers. Both MED1 and CTCF are validated conserved miR-122 targets. Furthermore, depletion of Ahr, Med1, or Ctcf in Mir122^-/- hepatocytes reduced Cyp1a2 expression. Pulse-chase studies found that CYP2E1 protein level is upregulated in LKO hepatocytes. Notably, miR-122 depletion sensitized differentiated human HepaRG cells to acetaminophen toxicity that correlated with upregulation of AHR, MED1, and CYP1A2 expression. Collectively, these results reveal a critical role of miR-122 in acetaminophen detoxification and implicate its therapeutic potential in patients with ALF.

Integrative analysis of hepatic microRNA and mRNA to identify potential biological pathways associated with monocrotaline-induced liver injury in mice

Pyrrolizidine alkaloids (PAs) are a type of natural hepatotoxic compounds. Monocrotaline (MCT), belongs to PAs, is a main compound distributed in medicinal herb Crotalaria ferruginea Grah. ex Benth. This study aims to identify the potential biological signaling pathway associated with MCT-induced liver injury by analyzing the integrative altered hepatic microRNA (miRNA) and mRNA expression profile. C57BL/6 mice were orally given with MCT (270, 330mg/kg). Serum alanine/aspartate aminotransferase (ALT/AST) activity, total bilirubin (TBil) amount and liver histological evaluation showed the liver injury induced by MCT. Results of miRNA chip analysis showed that the hepatic expression of 15 miRNAs (whose signal intensity>200) was significantly altered in MCT-treated mice, and among them total 11 miRNAs passed further validation by using Real-time PCR assay. Results of mRNA chip analysis demonstrated that the hepatic expression of 569 genes was up-regulated and of other 417 genes was down-regulated in MCT-treated mice. There are total 426 predicted target genes of those above altered 11 miRNAs, and among them total 10 genes were also altered in mice treated with both MCT (270mg/kg) and MCT (330mg/kg) from the results of mRNA chip. Among these above 10 genes, total 8 genes passed further validation by using Real-time PCR assay. Only 1 biological signaling pathway was annotated by using those above 8 genes, which is phagosome. In conclusion, this study demonstrated the integrative altered expression profile of liver miRNA and mRNA, and identified that innate immunity may be critically involved in MCT-induced liver injury in mice.

Drug metabolism and liver disease: a drug-gene-environment interaction

Despite the central role of the liver in drug metabolism, surprisingly there is lack of certainty in anticipating the extent of modification of the clearance of a given drug in a given patient. The intent of this review is to provide a conceptual framework in considering the impact of liver disease on drug disposition and reciprocally the impact of drug disposition on liver disease. It is proposed that improved understanding of the situation is gained by considering the issue as a special example of a drug-gene-environment interaction. This requires an integration of knowledge of the drug's properties, knowledge of the gene products involved in its metabolism, and knowledge of the pathophysiology of its disposition. This will enhance the level of predictability of drug disposition and toxicity for a drug of interest in an individual patient. It is our contention that advances in pharmacology, pharmacogenomics, and hepatology, together with concerted interests in the academic, regulatory, and pharmaceutical industry communities provide an ideal immediate environment to move from a qualitative reactive approach to quantitative proactive approach in individualizing patient therapy in liver disease.

Idiosyncratic Drug-Induced Liver Injury: Is Drug-Cytokine Interaction the Linchpin?

Idiosyncratic drug-induced liver injury continues to be a human health problem in part because drugs that cause these reactions are not identified in current preclinical testing and because progress in prevention is hampered by incomplete knowledge of mechanisms that underlie these adverse responses. Several hypotheses involving adaptive immune responses, inflammatory stress, inability to adapt to stress, and multiple, concurrent factors have been proposed. Yet much remains unknown about how drugs interact with the liver to effect death of hepatocytes. Evidence supporting hypotheses implicating adaptive or innate immune responses in afflicted patients has begun to emerge and is bolstered by results obtained in experimental animal models and in vitro systems. A commonality in adaptive and innate immunity is the production of cytokines, including interferon-γ (IFNγ). IFNγ initiates cell signaling pathways that culminate in cell death or inhibition of proliferative repair. Tumor necrosis factor-α, another cytokine prominent in immune responses, can also promote cell death. Furthermore, tumor necrosis factor-α interacts with IFNγ, leading to enhanced cellular responses to each cytokine. In this short review, we propose that the interaction of drugs with these cytokines contributes to idiosyncratic drug-induced liver injury, and mechanisms by which this could occur are discussed.

Tyrosine kinase inhibitors: friends or foe in treatment of hepatic fibrosis?

Aberrant activity of tyrosine kinases has been proved to be associated with multiple diseases including fibrotic diseases. Tyrosine kinases inhibitors (TKIs) might be a novel approach to transform the anti-fibrotic treatment. However, both beneficial and adverse effects are observed by researchers when using these TKIs in either preclinical animal models or patients with hepatic fibrosis. Since hepatotoxicity of TKIs is the leading cause for drug withdrawals thus limits its application in anti-fibrosis, not only efficacy but also safety of TKIs should be paid great concerns. It has been observed in a few studies that TKIs could induce relatively high rate of hepatic biochemical markers elevations and even result in liver failure. Fortunately, several strategies have been adopt to handle with the hepatotoxicity. Accumulating evidences suggest that hepatic stellate cells (HSC) play a pivotal role in hepatic fibrogenesis, so it might be a good option to develop selective TKIs specifically targeting HSCs. The present review will briefly summarize the anti-fibrotic mechanism of TKIs, adverse effects of TKIs as well as the novel developed selective delivery of TKIs.

Acute liver damage following intravenous glucocorticoid treatment for Graves' ophthalmopathy

PURPOSE

Over the last years, there have been several reports on the occurrence of acute liver damage (ALD) in patients affected with Graves' ophthalmopathy (GO) receiving intravenous glucocorticoids (ivGCs). This article is aimed at reviewing the literature on this specific topic and reporting two new cases of ALD occurring in GO patients while on ivGCs.

METHODS

The terms "glucocorticoid therapy" and "Graves' Ophthalmopathy"/"Graves' Orbitopathy"/"Thyroid eye disease" were used both separately and in conjunction with the terms "liver disease," "liver damage," "hepatotoxicity," "liver failure," to search MEDLINE for articles published since the first report of ALD in 2000 and up to 2015.

RESULTS

ALD [defined as an increase in alanine aminotransferase (ALT) >300 U/L] during or after completion of ivGCs has been so far reported in 17 fully documented cases. Overall, one-half of those patients were diagnosed as having autoimmune hepatitis (AIH) and in the vast majority of the remaining cases a diagnosis of methylprednisolone(MP)-induced hepatotoxicity was suspected. The clinical course of liver injury varied from asymptomatic hypertransaminasemia in the vast majority of patients to fatal hepatic failure in four patients receiving higher (>8 g) cumulative doses of MP.

CONCLUSIONS

The overall risk of ALD is relatively low (~1 %), and seems higher using a single dose >0.5 g and a cumulative dose >8.5 g MP. Whenever ivGC treatment is required, serum liver enzymes, viral hepatitis markers, and autoantibodies related to AIH should be obtained prior to ivGC administration. Liver function should be monitored during ivGC and up to 6 months after the end of treatment. Prolonging observation after 6 months is likely unnecessary, since all cases of ALD so far reported always occurred well within this term.

Acetylcholinesterase Inhibitors for Alzheimer's Disease Treatment Ameliorate Acetaminophen-Induced Liver Injury in Mice via Central Cholinergic System Regulation

Acetaminophen (APAP) is widely used as an analgesic and antipyretic agent, but it may induce acute liver injury at high doses. Alzheimer's disease patients, while treated with acetylcholinesterase inhibitor (AChEI), may take APAP when they suffer from cold or pain. It is generally recognized that inhibiting acetylcholinesterase activity may also result in liver injury. To clarify whether AChEI could deteriorate or attenuate APAP hepatotoxicity, the effects of AChEI on APAP hepatotoxicity were investigated. Male C57BL/6J mice were administrated with the muscarinic acetylcholine receptor (mAChR) blocker atropine (Atr), or classic α7 nicotine acetylcholine receptor (α7nAChR) antagonist methyllycaconitine (MLA) 1 hour before administration of AChEIs-donepezil (4 mg/kg), rivastigmine (2 mg/kg), huperzine A (0.2 mg/kg), or neostigmine (0.15 mg/kg)-followed by APAP (300 mg/kg). Eight hours later, the mice were euthanized for histopathologic examination and biochemical assay. The results demonstrated that the tested AChEIs, excluding neostigmine, could attenuate APAP-induced liver injury, accompanied by reduced reactive oxygen species formation, adenosine triphosphate and cytochrome C loss, c-Jun N-terminal kinase 2 (JNK2) phosphorylation, and cytokines. However, Atr or MLA significantly weakened the protective effect of AChEI by affecting mitochondrial function or JNK2 phosphorylation and inflammation response. These results suggest that central mAChR and α7nAChR, which are activated by accumulated acetylcholine resulting from AChEI, were responsible for the protective effect of AChEIs on APAP-induced liver injury. This indicates that Alzheimer's patients treated with AChEI could take APAP, as AChEI is unlikely to deteriorate the hepatotoxicity of APAP.

Chemical and in vitro biological information to predict mouse liver toxicity using recursive random forests

In this study, recursive random forests were used to build classification models for mouse liver toxicity. The mouse liver toxicity endpoint (67 toxic and 166 non-toxic) was a composition of four in vivo chronic systemic and carcinogenic toxicity endpoints (non-proliferative, neoplastic, proliferative and gross pathology). A multiple under-sampling approach and a shifted classification threshold of 0.288 (non-toxic < 0.288 and toxic ≥ 0.288) were used to cope with the unbalanced data. Our study showed that recursive random forests are very efficient in variable selection and for the development of predictive in silico models. Generally, over 95% redundant descriptors could be reduced from modelling for all the chemical, biological and hybrid models in this study. The predictive performance of chemical models (CCR of 0.73) is comparable with hybrid model performance (CCR of 0.74). Descriptors related to the octanol-water partition coefficient are vital for model performance. The in vitro endpoint of CYP2A2 played a key role in the development and interpretation of hybrid models. Identifying high-throughput screening assays relevant to liver toxicity would be key for improving in silico models of liver toxicity.

Hepatotoxicity of targeted therapy for cancer

INTRODUCTION

Understanding the mechanism of DILI with MTA, and how to avoid and manage these toxicities is essential for minimising inferior cancer treatment outcomes. An organised and comprehensive overview of MTA-associated hepatotoxicity is lacking; this review aims to fill the gap.

AREAS COVERED

A literature review was performed based on published case reports and relevant studies or articles pertaining to the topics on PubMed. Food and Drug Administration drug information documents and search on the US National Library of Medicine LiverTox database was performed for all relevant MTA.

EXPERT OPINION

MTA-associated hepatotoxicity is common but rarely fatal. The pattern of hepatotoxicity is predominantly idiosyncratic. Pharmacogenomics show potential in predicting patients at risk of poorly metabolising or developing immunoallergic responses to MTA, but prospective data is scant. Preventing reactivation of viral hepatitis using anti-viral drugs, and avoidance of drug combinations at high risk of negative interactions are the most readily preventable measures for DILI.

Curcumin prevents paracetamol-induced liver mitochondrial alterations

OBJECTIVE

In the present study was evaluated if curcumin is able to attenuate paracetamol (PCM)-induced mitochondrial alterations in liver of mice.

METHODS

Mice (n = 5-6/group) received curcumin (35, 50 or 100 mg/kg bw) 90 min before PCM injection (350 mg/kg bw). Plasma activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) was measured; histological analyses were done; and measurement of mitochondrial oxygen consumption, mitochondrial membrane potential, ATP synthesis, aconitase activity and activity of respiratory complexes was carried out.

KEY FINDINGS

Curcumin prevented in a dose-dependent manner PCM-induced liver damage. Curcumin (100 mg/kg) attenuated PCM-induced liver histological damage (damaged hepatocytes from 28.3 ± 7.7 to 8.3 ± 0.7%) and increment in plasma ALT (from 2300 ± 150 to 690 ± 28 U/l) and AST (from 1603 ± 43 to 379 ± 22 U/l) activity. Moreover, curcumin attenuated the decrease in oxygen consumption using either succinate or malate/glutamate as substrates (evaluated by state 3, respiratory control ratio, uncoupled respiration and adenosine diphosphate/oxygen ratio), in membrane potential, in ATP synthesis, in aconitase activity and in the activity of respiratory complexes I, III and IV.

CONCLUSIONS

These results indicate that the protective effect of curcumin in PCM-induced hepatotoxicity is associated with attenuation of mitochondrial dysfunction.

Development of HepG2-derived cells expressing cytochrome P450s for assessing metabolism-associated drug-induced liver toxicity

The generation of reactive metabolites from therapeutic agents is one of the major mechanisms of drug-induced liver injury (DILI). In order to evaluate metabolism-related toxicity and improve drug efficacy and safety, we generated a battery of HepG2-derived cell lines that express 14 cytochrome P450s (CYPs) (1A1, 1A2, 1B1, 2A6, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 3A4, 3A5 and 3A7) individually using a lentiviral expression system. The expression/production of a specific CYP in each cell line was confirmed by an increased abundance of the CYP at both mRNA and protein levels. Moreover, the enzymatic activities of representative CYPs in the corresponding cell lines were also measured. Using our CYP-expressed HepG2 cells, the toxicity of three drugs that could induce DILI (amiodarone, chlorpromazine and primaquine) was assessed, and all of them showed altered (increased or decreased) toxicity compared to the toxicity in drug-treated wild-type HepG2 cells. CYP-mediated drug toxicity examined in our cell system is consistent with previous reports, demonstrating the potential of these cells for assessing metabolism-related drug toxicity. This cell system provides a practical in vitro approach for drug metabolism screening and for early detection of drug toxicity. It is also a surrogate enzyme source for the enzymatic characterization of a particular CYP that contributes to drug-induced liver toxicity.

Liver injury in patients with DRESS: A clinical study of 72 cases

BACKGROUND

Drug reaction with eosinophilia and systemic symptoms (DRESS) is a syndrome involving multiple systems. Liver injury is the most common visceral manifestation.

OBJECTIVE

The purpose of this study was to investigate the types of liver injury and factors associated with DRESS.

METHODS

A retrospective cohort study was conducted in Taiwan using a DRESS database compiled from December 2000 to March 2013.

RESULTS

Seventy-two cases were included in this study. Among them, 62 (86.1%) cases involved liver injury, 6 of which (9.7%) were liver injury before skin presentation. The distribution of liver injury patterns at initial presentation was 23 cholestatic type (37.1%), 17 mixed type (27.4%), and 12 hepatocellular type (19.4%). Patients with hepatocellular-type injuries were younger, with a median age of 31.5 (P = .044). Individuals with liver function results more than 10 times the upper limit were more likely to have fever (P = .026), took more time to recover, and had fewer eosinophils in the dermis (P = .002).

LIMITATIONS

The study was a retrospective cohort study with limited cases.

CONCLUSIONS

Liver injury is common in DRESS and frequently associated with atypical lymphocytosis. The cholestatic type is the most common type. Patients with cholestatic-type injuries were older and more frequently had interface changes in skin pathology.

A challenge for diagnosing acute liver injury with concomitant/sequential exposure to multiple drugs: can causality assessment scales be utilized to identify the offending drug?

Drug-induced hepatotoxicity most commonly manifests as an acute hepatitis syndrome and remains the leading cause of drug-induced death/mortality and the primary reason for withdrawal of drugs from the pharmaceutical market. We report a case of acute liver injury in a 12-year-old Hispanic boy, who received a series of five antibiotics (amoxicillin, ceftriaxone, vancomycin, ampicillin/sulbactam, and clindamycin) for cervical lymphadenitis/retropharyngeal cellulitis. Histopathology of the liver biopsy specimen revealed acute cholestatic hepatitis. All known causes of acute liver injury were appropriately excluded and (only) drug-induced liver injury was left as a cause of his cholestasis. Liver-specific causality assessment scales such as Council for the International Organization of Medical Sciences/Roussel Uclaf Causality Assessment Method scoring system (CIOMS/RUCAM), Maria and Victorino scale, and Digestive Disease Week-Japan were applied to seek the most likely offending drug. Although clindamycin is the most likely cause by clinical diagnosis, none of causality assessment scales aid in the diagnosis.

Profiling cumulative proportional reporting ratios of drug-induced liver injury in the FDA Adverse Event Reporting System (FAERS) database

BACKGROUND

Early prediction and accurate characterization of risk for serious liver injury associated with newly marketed drugs remains an important challenge for clinicians, the pharmaceutical industry, and regulators. To date, a biomarker that specifically indicates exposure to a drug as the etiologic cause of liver injury has not been identified.

OBJECTIVES

Using cumulative proportional reporting ratios (PRRs), we investigated 'real-time' profiles of a set of pharmaceuticals, over the first 3 years of US marketing, for the signaling of clinically serious drug-induced liver injury (DILI) in a large spontaneous-reporting database.

METHODS

Using report counts of hepatic failure or clinically serious liver injury obtained from the FDA Adverse Events Reporting System (FAERS) database, PRRs of adverse drug event terms were calculated by division of counts of domestic reports of these events by counts of all serious adverse events for each of 13 selected drugs associated with a broad range of hepatotoxic risk (including three linked to only rare instances of clinically apparent liver injury) with reference to all other drugs in the database. Drug-specific cumulative PRRs were measured at successive intervals (calendar quarters) using cumulative tallies of FAERS reports to generate time-based profiles over the initial 3 years of US marketing.

RESULTS

In the set of drugs analyzed, those with no known hepatotoxic risk demonstrated time-based cumulative PRR profiles that approximate the background rates of hepatic failure and serious liver injury reported in the entire FAERS database. In contrast, those that were removed from marketing or subjected to marketing restrictions due to their potential to cause liver injury were associated with profiles of rapidly rising cumulative PRRs that were greater than 5 within the first 10 million domestic prescriptions or the first four quarters of US marketing. The systematic tracking and identification of rising PRRs for DILI associated with newly marketed pharmaceutical and biological agents is a valuable tool for identification of safety signals within the FAERS database.

LIMITATIONS

Disproportionality profiling of spontaneous reports in FAERS (e.g., cumulative PRR measurements), which signals an association between a recently marketed drug and liver injury, is not a method to quantitatively measure drug-related risk. Regulatory actions in response to emerging drug safety concerns often depend on an accurate assessment of risks using multiple sources of data and the consideration of overall benefits and risks of the agent. Causality must be determined through analysis of individual cases to exclude other etiologies of liver injury.

CONCLUSION

The FAERS database can be used to advance empiric hepatotoxicity time-trending reporting levels for newly marketed agents in order to rapidly identify recently launched potential hepatotoxic agents and initiate further evaluation.

Roles of lipoxin A4 in preventing paracetamol-induced acute hepatic injury in a rabbit model

The objective of this research is to investigate the potential role of lipoxin A4 in preventing paracetamol (PCM)-induced hepatic injury. One hundred male New Zealand white rabbits were randomly divided into control group, PCM group, N-acetylcysteine (NAC) group, lipoxin A4 (LXA4) group, and LXA4 + NAC group. The rabbits were assigned to receive 300 mg/kg weight PCM in 0.9 % saline or equivalent volume of saline via gastric lavage. LXA4 (1.5 μg/kg) and equivalent volume of 2 % ethanol were separately given to the rabbits in LXA4-treated and PCM groups 24 h after PCM administration. Meanwhile, the rabbits in the NAC-treated groups received a loading dose of 140 mg/kg of N-acetylcysteine. The blood samples and liver tissue were collected for biochemical and histological evaluation 36 h after paracetamol administration. The administration of LXA4 24 h after paracetamol poisoning resulted in significant improvement in hepatic injury as represented by decrease of hepatocellular enzyme release and attenuation of hepatocyte apoptosis and necrosis. In LXA4-treated groups, the expression of TNF-α was significantly lower than those in PCM and NAC groups (p < 0.05). In contrast, the level of IL-10 was significantly higher than PCM and NAC groups (p < 0.05). Moreover, the expressions of NF-κB p65 in PCM and NAC groups were significantly increased compared with those of LXA4-treated groups and control group (respectively, p < 0.05 and p < 0.01). LXA4-treated groups also showed significantly higher survival rates. Lipoxin A4 significantly mitigates paracetamol-induced hepatic injury, in which anti-inflammation effect may play an important role, leading to hepatic apoptosis and necrosis.

Two xanthones from Swertia punicea with hepatoprotective activities in vitro and in vivo

ETHNOPHARMACOLOGICAL RELEVANCE

Swertia punicea Hemsl. (Gentianaceae) is more commonly known as "Ganyan-cao" and used mainly as a traditional Chinese folk medicine for the treatment of acute bilious hepatitis, cholecystitis, fever, intoxification and jaundice.

MATERIALS AND METHODS

The active hepatoprotective constituents of Swertia punicea were purified using various column chromatography techniques. The structures of two isolated compounds were determined on the basis of spectroscopic data interpretation such as NMR analysis. The hepatoprotective activities of isolated compounds were evaluated by using hepatotoxicity in vitro and dimethylnitrosamine-induced rat hepatic fibrosis in vivo, respectively.

RESULTS

Two xanthones, 1, 7-dihydroxy-3, 4, 8-trimethoxyxanthone (1) and bellidifolin (2) were isolated from the stems of Swertia punicea. The compounds 1 and 2 exhibited notable hepatoprotective activities against carbon tetrachloride (CCl4) -induced HepG2 cell damage, and effectively alleviated the levels of aspartate transaminase (AST), lactate dehydrogenase (LDH), superoxide dismutase (SOD) and malonic dialdehyde (MDA) induced by CCl₄ in a concentration-dependent manner. Co-treatment with compound 2 significantly increased the cell viability compared with N-acetyl-p-aminophenol (APAP) treatment. Compound 2 also alleviated APAP-induced hepatotoxicity by increasing glutathione (GSH) content and decreasing hydroxyl free radical (·OH) levels and reactive oxygen specises (ROS) production. In addition, the protective effect of compound 1 significantly alleviated DMN-induced liver inflammation and fibrosis. Oral administration of compound 1 recovered the reduction of albumin (ALB) and reversed the elevation of serum alanine transaminase (ALT), AST and total bilirubin (TBIL) in dimethylnitrosamine (DMN)-induced fibrotic rats. Severe oxidative stress induced in fibrotic rats was evidenced by a 1.5-fold elevation in MDA and a fall in the SOD activity, and treatment with compound 1 protected against these adverse effects. Recovery of rat liver tissue against DMN-induced hepatocellular necrosis, inflammatory changes and hepatic fibrosis by compound 1 is also confirmed by H&E and Masson stained histopathological evaluation of liver tissue.

CONCLUSION

Two xanthones from Swertia punicea exhibited hepatoprotective activities in vitro (compounds 1 and 2) and in vivo (compound 1), respectively.

Autophagy in drug-induced liver toxicity

Liver injury resulting from exposure to drugs and chemicals is a major health problem. Autophagy is an important factor in a wide range of diseases, such as cancer, liver disease, muscular disorder, neurodegeneration, pathogen infection, and aging, and emerging evidence indicates that autophagy makes a substantial contribution to the pathogenesis of drug- and chemical-induced liver toxicity. In this review, we summarize current knowledge on autophagy triggered by toxicants/toxins, the protective role of autophagy in liver toxicity, and the underlying molecular mechanisms. We also highlight experimental approaches for studying autophagy.

Hypothermia and protection from acetaminophen-induced liver injury

Acetaminophen-induced liver failure is the most common cause of acute liver failure in the United States. The exact mechanism of acute liver failure secondary to acetaminophen toxicity is unknown, although a presumed mechanism of hepatocellular necrosis involving the accumulation of a toxic metabolite (N-acetyl-p-benzoquinoneimine) has been postulated. A 62-year-old woman with a history of a suicide attempt was brought to the emergency department at ∼12 hours post acetaminophen overdose. The patient presented with an acetaminophen level of 284 mcg/mL and with profound hypothermia (31°C). Liver function tests and coagulation studies were normal. Within 24 hours of presentation, the patient was normothermic, had received seven oral doses of N-acetylcysteine, and had an acetaminophen level of <5 mcg/mL. The patient was discharged from the intensive care unit at 96 hours post admission in stable condition with no evidence of hepatic injury. No further treatment with N-acetylcysteine was required. Despite a toxic acetaminophen level, this patient did not suffer any hepatic injury. Hypothermia may have attenuated the production of N-acetyl-p-benzoquinoneimine by depressing the cytochrome P450 system, allowing accumulation of the parent drug rather than toxic metabolites. This case report suggests that hypothermia may have protected the liver of a patient presenting with acetaminophen toxicity and supports further investigation into the potential therapeutic role of induced hypothermia during acetaminophen toxicity.