Th1/Th2 cytokine balance as a determinant of acetaminophen-induced liver injury

Natural Products for Acetaminophen-Induced Acute Liver Injury: A Review

The liver plays a vital role in metabolism, synthesis, and detoxification, but it is susceptible to damage from various factors such as viral infections, drug reactions, excessive alcohol consumption, and autoimmune diseases. This susceptibility is particularly problematic for patients requiring medication, as drug-induced liver injury often leads to underestimation, misdiagnosis, and difficulties in treatment. Acetaminophen (APAP) is a widely used and safe drug in therapeutic doses but can cause liver toxicity when taken in excessive amounts. This study aimed to investigate the hepatotoxicity of APAP and explore potential treatment strategies using a mouse model of APAP-induced liver injury. The study involved the evaluation of various natural products for their therapeutic potential. The findings revealed that natural products demonstrated promising hepatoprotective effects, potentially alleviating liver damage and improving liver function through various mechanisms such as oxidative stress and inflammation, which cause changes in signaling pathways. These results underscore the importance of exploring novel treatment options for drug-induced liver injury, suggesting that further research in this area could lead to the development of effective preventive and therapeutic interventions, ultimately benefiting patients with liver injury caused by medicine.

Effects of Acetaminophen Exposure on Outcomes of Patients Receiving Immune Checkpoint Inhibitors for Advanced Non-Small-Cell Lung Cancer: A Propensity Score-Matched Analysis

(1) Background: Several studies have investigated potential interactions between immune checkpoint inhibitors (ICIs) and commonly prescribed medications. Although acetaminophen (APAP) has not been considered susceptible to interaction with ICIs, recent research has shown that detectable plasma levels of this drug can hinder the efficacy of PD-1/PD-L1 blockade therapies. A reliable assessment of the potential interaction between APAP and ICIs in advanced non-small cell lung cancer (NSCLC) patients would be worthwhile since it is often prescribed in this condition. We sought to evaluate the impact of the concomitant use of APAP in patients with advanced NSCLC on PD-1/PD-L1 blockade using real-world evidence. (2) Methods: This study included consecutive patients with histologically proven stage IV NSCLC who underwent first-line therapy with pembrolizumab as a single agent or in combination with platinum-based chemotherapy, or second-line therapy with pembrolizumab, nivolumab, or atezolizumab. The intensity of APAP exposure was classified as low (therapeutic intake lasting less than 24 h or a cumulative intake lower than 60 doses of 1000 mg) or high (therapeutic intake lasting more than 24 h or a total intake exceeding 60 doses of 1000 mg). The favorable outcome of anti-PD-1/PD-L1 therapies was defined by durable clinical benefit (DCB). Progression-free survival (PFS) and overall survival (OS) were relevant to our efficacy analysis. Propensity score matching (PSM) methods were applied to adjust for differences between the APAP exposure subgroups. (3) Results: Over the course of April 2018 to October 2022, 80 patients were treated with first-line pembrolizumab either as single-agent therapy or in combination with platinum-based chemotherapy. During the period from June 2015 to November 2022, 145 patients were given anti-PD-1/PD-L1 blockade therapy as second-line treatment. Subsequent efficacy analyses relied on adjusted PSM populations in both treatment settings. Multivariate testing revealed that only the level of APAP and corticosteroid intake had an independent effect on DCB in both treatment lines. Multivariate Cox regression analysis confirmed high exposure to APAP and immunosuppressive corticosteroid therapy as independent predictors of shorter PFS and OS in both treatment settings. (4) Conclusions: Our findings would strengthen the available evidence that concomitant intake of APAP blunts the efficacy of ICIs in patients with advanced NSCLC. The detrimental effects appear to depend on the cumulative dose and duration of exposure to APAP. The inherent shortcomings of the current research warrant confirmation in larger independent series.

Essential Involvement of Neutrophil Elastase in Acute Acetaminophen Hepatotoxicity Using BALB/c Mice

Intense neutrophil infiltration into the liver is a characteristic of acetaminophen-induced acute liver injury. Neutrophil elastase is released by neutrophils during inflammation. To elucidate the involvement of neutrophil elastase in acetaminophen-induced liver injury, we investigated the efficacy of a potent and specific neutrophil elastase inhibitor, sivelestat, in mice with acetaminophen-induced acute liver injury. Intraperitoneal administration of 750 mg/kg of acetaminophen caused severe liver damage, such as elevated serum transaminase levels, centrilobular hepatic necrosis, and neutrophil infiltration, with approximately 50% mortality in BALB/c mice within 48 h of administration. However, in mice treated with sivelestat 30 min after the acetaminophen challenge, all mice survived, with reduced serum transaminase elevation and diminished hepatic necrosis. In addition, mice treated with sivelestat had reduced NOS-II expression and hepatic neutrophil infiltration after the acetaminophen challenge. Furthermore, treatment with sivelestat at 3 h after the acetaminophen challenge significantly improved survival. These findings indicate a new clinical application for sivelestat in the treatment of acetaminophen-induced liver failure through mechanisms involving the regulation of neutrophil migration and NO production.

The immunological mechanisms and therapeutic potential in drug-induced liver injury: lessons learned from acetaminophen hepatotoxicity

Acute liver failure caused by drug overdose is a significant clinical problem in developed countries. Acetaminophen (APAP), a widely used analgesic and antipyretic drug, but its overdose can cause acute liver failure. In addition to APAP-induced direct hepatotoxicity, the intracellular signaling mechanisms of APAP-induced liver injury (AILI) including metabolic activation, mitochondrial oxidant stress and proinflammatory response further affect progression and severity of AILI. Liver inflammation is a result of multiple interactions of cell death molecules, immune cell-derived cytokines and chemokines, as well as damaged cell-released signals which orchestrate hepatic immune cell infiltration. The immunoregulatory interplay of these inflammatory mediators and switching of immune responses during AILI lead to different fate of liver pathology. Thus, better understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression are essential to identify novel therapeutic targets for the treatment of AILI. Here, this present review aims to systematically elaborate on the underlying immunological mechanisms of AILI, its relevance to immune cells and their effector molecules, and briefly discuss great therapeutic potential based on inflammatory mediators.

Foreign body response to synthetic polymer biomaterials and the role of adaptive immunity

Implanted biomaterials elicit a series of distinct immune and repair-like responses that are collectively known as the foreign body reaction (FBR). These include processes involving innate immune inflammatory cells and wound repair cells that contribute to the encapsulation of biomaterials with a dense collagenous and largely avascular capsule. Numerous studies have shown that the early phase is dominated by macrophages that fuse to form foreign body giant cells that are considered a hallmark of the FBR. With the advent of more precise cell characterization techniques, specific macrophage subsets have been identified and linked to more or less favorable outcomes. Moreover, studies comparing synthetic- and natural-based polymer biomaterials have allowed the identification of macrophage subtypes that distinguish between fibrotic and regenerative responses. More recently, cells associated with adaptive immunity have been shown to participate in the FBR to synthetic polymers. This suggests the existence of cross-talk between innate and adaptive immune cells that depends on the nature of the implants. However, the exact participation of adaptive immune cells, such as T and B cells, remains unclear. In fact, contradictory studies suggest either the independence or dependence of the FBR on these cells. Here, we review the evidence for the involvement of adaptive immunity in the FBR to synthetic polymers with a focus on cellular and molecular components. In addition, we examine the possibility that such biomaterials induce specific antibody responses resulting in the engagement of adaptive immune cells.

The dual role of immune response in acetaminophen hepatotoxicity: Implication for immune pharmacological targets

Acetaminophen (APAP), one of the most widely used antipyretic and analgesic drugs, principally contributes to drug-induced liver injury when taken at a high dose. APAP-induced liver injury (AILI) results in extensive necrosis of hepatocytes along with the occurrence of multiple intracellular events such as metabolic activation, cell injury, and signaling pathway activation. However, the specific role of the immune response in AILI remains controversial for its complicated regulatory mechanisms. A variety of inflammasomes, immune cells, inflammatory mediators, and signaling transduction pathways are activated in AILI. These immune components play antagonistic roles in aggravating the liver injury or promoting regeneration. Recent experimental studies indicated that natural products showed remarkable therapeutic effects against APAP hepatotoxicity due to their favorable efficacy. Therefore, this study aimed to review the present understanding of the immune response in AILI and attempted to establish ties among a series of inflammatory cascade reactions. Also, the immune molecular mechanisms of natural products in the treatment of AILI were extensively reviewed, thus providing a fundamental basis for exploring the potential pharmacological targets associated with immune interventions.

KDR polymorphism (1192G/A, 1719A/T) and modulation of ARV drug-induced hepatotoxicity

Kinase insert Domain containing Receptor (KDR)/Vascular Endothelial Growth Factor Receptor (VEGFR-2) participate in endothelial dysfunction, which can lead to chronic liver disease. KDR reflects naturally against the toxicants from the damaged liver cells. Association of KDR polymorphism has been reported with many diseases including liver disease, but its role has not been described in ARV induced hepatotoxicity. Hence, we examined the exonic regions KDR (1192G/A, 1719A/T) polymorphism from 165 HIV-infected individuals (34/165 had ARV induced hepatotoxicity, 131/165 were with no hepatotoxicity) and 160 normal uninfected individuals by PCR-RFLP. In univariate analysis, KDR 1719 TT genotype presented at greater frequency from all HIV positive individuals in contrast with normal uninfected individuals (7.87% vs. 4.4%, OR = 1.72, P = 0.38). Individuals with KDR 1719 TT genotype had a risk for increasing hepatotoxicity and its severity (OR = 1.91, P = 0.38). Individuals with haplotype AT had risk for increasing hepatotoxicity and its severity (OR = 1.60, P = 0.50; OR = 2.35, P = 0.27). Whereas haplotype AA was associated with reduced risk of developing hepatotoxicity (OR = 0.40, P = 0.04). Individuals with KDR 1719 TT genotype were at greater risk of advancement of HIV disease (OR = 2.31, P = 0.23). Individuals with KDR 1719 TT genotype had more vulnerability for developing hepatotoxicity among alcohol users (OR = 2.57, P = 0.23). Individuals with KDR 1719 TT genotype were at higher risk of developing hepatotoxicity and its severity among nevirapine and alcohol consumers (OR = 2.47, P = 0.24; OR = 5.42, P = 0.42). In multivariate analysis, hepatotoxicity patients taking ART inclusive of nevirapine was associated with the severity of hepatotoxicity (OR = 4.82, P = 0.002). In conclusion, KDR 1719 TT genotype and haplotype AT may have a risk for development of hepatotoxicity and its severity. Haplotype AA may have influence to reduce the risk of developing hepatotoxicity.

T lymphocytes as critical mediators in tissue regeneration, fibrosis, and the foreign body response

Research on the foreign body response (FBR) to biomaterial implants has been focused on the roles that the innate immune system has on mediating tolerance or rejection of implants. However, the immune system also involves the adaptive immune response and it must be included in order to form a complete picture of the response to biomaterials and medical implants. In this review, we explore recent understanding about the roles of adaptive immune cells, specifically T cells, in modulating the immune response to biomaterial implants. The immune response to implants elicits a delicate balance between tissue repair and fibrosis that is mainly regulated by three types of T helper cell responses -T helper type 1, T helper type 2, and T helper type 17- and their crosstalk with innate immune cells. Interestingly, many T cell response mechanisms to implants overlap with the process of fibrosis or repair in different tissues. This review explores the fibrotic and regenerative T cell biology and draws parallels to T cell responses to biomaterials. Additionally, we also explore the biomedical engineering advancements in biomaterial applications in designing particle and scaffold systems to modulate T cell activity for therapeutics and devices. Not only do the deliberate engineering design of physical and chemical material properties and the direct genetic modulation of T cells not only offer insights to T cell biology, but they also present different platforms to develop immunomodulatory biomaterials. Thus, an in-depth understanding of T cells' roles can help to navigate the biomaterial-immune interactions and reconsider the long-lasting adaptive immune response to implants, which, in the end, contribute to the design of immunomodulatory medical implants that can advance the next generation of regenerative therapy. STATEMENT OF SIGNIFICANCE: This review article integrates knowledge of adaptive immune responses in tissue damage, wound healing, and medical device implantation. These three fields, often not discussed in conjunction, are important to consider when evaluating and designing biomaterials. Through incorporation of basic biological research alongside engineering research, we provide an important lens through which to evaluate adaptive immune contributions to regenerative medicine and medical device development.

The Role of Resveratrol in Liver Disease: A Comprehensive Review from In Vitro to Clinical Trials

Many studies have shown that resveratrol has a lot of therapeutic effects on liver disorders. Its administration can significantly increase the survival rate after liver transplantation, reduce fat deposition and ischemia-induced necrosis and apoptosis in Wistar rats. Resveratrol can provide Liver protection against chemical, cholestatic, and alcohol-mediated damage. It can improve glucose metabolism and lipid profile, reduce liver fibrosis, and steatosis. Additionally, it is capable of altering the fatty acid composition of the liver cells. Resveratrol may be a potential treatment option for the management of non-alcoholic fatty liver disease (NAFLD) due to its anti-inflammatory, antioxidant, and calorie-restricting effects. There are also studies that have evaluated the effect of resveratrol on lipid and liver enzyme profiles among patients with metabolic syndrome (MetS) and related disorders. Based on the extent of liver disease worldwide and the need to find new treatment possibilities, this review critically examines current in vitro and in vivo preclinical studies and human clinical studies related to liver protection.

The Late-Stage Protective Effect of Mito-TEMPO against Acetaminophen-Induced Hepatotoxicity in Mouse and Three-Dimensional Cell Culture Models

An overdose of acetaminophen (APAP), the most common cause of acute liver injury, induces oxidative stress that subsequently causes mitochondrial impairment and hepatic necroptosis. N-acetyl-L-cysteine (NAC), the only recognized drug against APAP hepatotoxicity, is less effective the later it is administered. This study evaluated the protective effect of mitochondria-specific Mito-TEMPO (Mito-T) on APAP-induced acute liver injury in C57BL/6J male mice, and a three dimensional (3D)-cell culture model containing the human hepatoblastoma cell line HepG2. The administration of Mito-T (20 mg/kg, i.p.) 1 h after APAP (400 mg/kg, i.p.) injection markedly attenuated the APAP-induced elevated serum transaminase activity and hepatic necrosis. However, Mito-T treatment did not affect key factors in the development of APAP liver injury including the activation of c-jun N-terminal kinases (JNK), and expression of the transcription factor C/EBP homologous protein (CHOP) in the liver. However, Mito-T significantly reduced the APAP-induced increase in the hepatic oxidative stress marker, nitrotyrosine, and DNA fragmentation. Mito-T markedly attenuated cytotoxicity induced by APAP in the HepG2 3D-cell culture model. Moreover, liver regeneration after APAP hepatotoxicity was not affected by Mito-T, demonstrated by no changes in proliferating cell nuclear antigen formation. Therefore, Mito-T was hepatoprotective at the late-stage of APAP overdose in mice.

Possible Pathways of Hepatotoxicity Caused by Chemical Agents

BACKGROUND

Liver injury induced by drugs has become a primary reason for acute liver disease and therefore posed a potential regulatory and clinical challenge over the past few decades and has gained much attention. It also remains the most common cause of failure of drugs during clinical trials. In 50% of all acute liver failure cases, drug-induced hepatoxicity is the primary factor and 5% of all hospital admissions.

METHODS

The various hepatotoxins used to induce hepatotoxicity in experimental animals include paracetamol, CCl4, isoniazid, thioacetamide, erythromycin, diclofenac, alcohol, etc. Among the various models used to induce hepatotoxicity in rats, every hepatotoxin causes toxicity by different mechanisms.

RESULTS

The drug-induced hepatotoxicity caused by paracetamol accounts for 39% of the cases and 13% hepatotoxicity is triggered by other hepatotoxic inducing agents.

CONCLUSION

Research carried out and the published papers revealed that hepatotoxins such as paracetamol and carbon- tetrachloride are widely used for experimental induction of hepatotoxicity in rats.

Interleukin-10 polymorphisms and susceptibility to ARV associated hepatotoxicity

Interleukin-10 (IL-10) is an anti-inflammatory cytokine associated with the inhibition of HIV replication. IL-10 polymorphisms were found to be linked to drug-induced hepatotoxicity. Hence we examined the prevalence of IL-10 (-819C/T,-1082A/G) polymorphisms in a total of 165 HIV patients which included 34 patients with hepatotoxicity, 131 without hepatotoxicity and 155 healthy controls by the PCR-RFLP method. In HIV patients with hepatotoxicity, the IL-10-819TT genotype increased the risk of ARV associated hepatotoxicity severity (OR = 1.61, P = 0.35). IL-10-819TT genotype was overrepresented in patients with hepatotoxicity as compared to healthy controls (26.5% vs. 13.5%, OR = 1.61, P = 0.46). IL-10 -819CT genotype was associated with advance HIV disease stage (OR = 0.49, P = 0.045). In HIV patients without hepatotoxicity, the IL-10-819TT genotype was more prevalent in patients consuming tobacco as compared to non-users (OR = 1.60, P = 0.41). In HIV patients without hepatotoxicity using both alcohol + efavirenz along with IL-10 -819CT genotype resulted in increased risk for the acquisition of ARV associated hepatotoxicity (OR = 4.00, P = 0.36). In multivariate logistic regression, taking nevirapine was associated with the risk hepatotoxicity severity (OR = 0.23, P = 0.005). In conclusion, an insignificant association between IL-10 polymorphisms and susceptibility to ARV associated hepatotoxicity.

Therapeutic Potential of Plants and Plant Derived Phytochemicals against Acetaminophen-Induced Liver Injury

Acetaminophen (APAP), which is also known as paracetamol or N-acetyl-p-aminophenol is a safe and potent drug for fever, pain and inflammation when used at its normal therapeutic doses. It is available as over-the-counter drug and used by all the age groups. The overdose results in acute liver failure that often requires liver transplantation. Current clinical therapy for APAP-induced liver toxicity is the administration of N-acetyl-cysteine (NAC), a sulphydryl compound an approved drug which acts by replenishing cellular glutathione (GSH) stores in the liver. Over the past five decades, several studies indicate that the safety and efficacy of herbal extracts or plant derived compounds that are used either as monotherapy or as an adjunct therapy along with conventional medicines for hepatotoxicity have shown favorable responses. Phytochemicals mitigate necrotic cell death and protect against APAP-induced liver toxicityby restoring cellular antioxidant defense system, limiting oxidative stress and subsequently protecting mitochondrial dysfunction and inflammation. Recent experimental evidences indicat that these phytochemicals also regulate differential gene expression to modulate various cellular pathways that are implicated in cellular protection. Therefore, in this review, we highlight the role of the phytochemicals, which are shown to be efficacious in clinically relevant APAP-induced hepatotoxicity experimental models. In this review, we have made comprehensive attempt to delineate the molecular mechanism and the cellular targets that are modulated by the phytochemicals to mediate the cytoprotective effect against APAP-induced hepatotoxicity. In this review, we have also defined the challenges and scope of phytochemicals to be developed as drugs to target APAP-induced hepatotoxicity.

Strain and interindividual differences in lamotrigine-induced liver injury in mice

Lamotrigine (LTG) has been widely prescribed as an antipsychotic drug, although it causes idiosyncratic drug-induced liver injury in humans. LTG is mainly metabolized by UDP-glucuronosyltransferase, while LTG undergoes bioactivation by cytochrome P450 to a reactive metabolite; it is subsequently conjugated with glutathione, suggesting that reactive metabolite would be one of the causes for LTG-induced liver injury. However, there is little information regarding the mechanism of LTG-induced liver injury in both humans and rodents. In this study, we established an LTG-induced liver injury mouse model through co-administration with LTG and a glutathione synthesis inhibitor, l-buthionine-(S,R)-sulfoximine. We found an increase in alanine aminotransferase (ALT) levels (>10 000 U/L) in C57BL/6J mice, with apparent interindividual differences. On the other hand, a drastic increase in ALT was not noted in BALB/c mice, suggesting that the initiation mechanism would be different between the two strains. To examine the cause of interindividual differences, C57BL/6J mice that were co-administered LTG and l-buthionine-(S,R)-sulfoximine were categorized into three groups based on ALT values: no-responder (ALT <100 U/L), low-responder (100 U/L < ALT < 1000 U/L) and high-responder (ALT >1000 U/L). In the high-responder group, induction of hepatic oxidative stress, inflammation and damage-associated molecular pattern molecules in mRNA was associated with vacuolation and karyorrhexis in hepatocytes. In conclusion, we demonstrated that LTG showed apparent strain and interindividual differences in liver injuries from the aspects of initiation and exacerbation mechanisms. These results would support interpretation of the mechanism of LTG-induced liver injury observed in humans.

The -3279C>A and -924A>G polymorphisms in the FOXP3 Gene Are Associated With Viral Load and Liver Enzyme Levels in Patients With Chronic Viral Liver Diseases

The transcription factor FOXP3 is an essential marker of the development and activation of regulatory T cells (Tregs), which are cells specialized in the regulation and normal tolerance of the immune response. In the context of chronic viral liver diseases, Tregs participate in the maintenance of infections by promoting histopathological control and favor the immune escape of viral agents by suppressing the antiviral response. Single nucleotide polymorphisms (SNPs) may influence the function of FOXP3 in a number of pathological conditions. The present study sought to evaluate the influence of SNPs in the FOXP3 gene promoter region in patients with chronic viral liver diseases. Three SNPs (−3279C>A, −2383C>T, and −924A>G) were analyzed in groups of patients with chronic hepatitis C (CHC), active chronic hepatitis B (CHB-A), inactive chronic hepatitis B (CHB-I), and a healthy control group (CG) using real-time PCR. The frequencies of the polymorphic variants were compared between groups and correlated with liver histopathological characteristics and enzyme levels [i.e., alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGT)] obtained via biopsy and from the clinical records of the participating patients, respectively. For the −2338C>T SNP, no significant differences were found in the frequencies of variants between groups or in the histological findings. Significant associations between the polymorphisms and the CHB-I group were not established. The −3279C>A SNP was associated with altered viral loads (log₁₀) and GGT levels in CHC patients with advanced stages of inflammatory activity and liver fibrosis. The −924A>G SNP was associated with altered viral loads (log₁₀) and liver enzyme levels among CHB-A patients with milder inflammation and fibrosis. However, the frequencies of the −3279C>A and −924A>G polymorphisms were not directly associated with the histopathological profiles of the analyzed patients. These polymorphic variants may influence hepatic function in patients with chronic viral liver diseases but are not directly associated with the establishment of the degree of inflammatory activity and liver fibrosis.

IL-1RN and IL-1β Polymorphism and ARV-Associated Hepatotoxicity

The severity of hepatic injury depends upon cytokines. Previous studies associated IL-1RN allele 2 with IL-1β production. Hence, we examined the association of IL-1 RN and IL-1β polymorphisms with ARV-associated hepatotoxicity. Genotyping of IL-1RN (VNTR), IL-1β (-511C/T) polymorphisms was done in 162 HIV-infected patients, 34 with ARV hepatotoxicity, 128 without hepatotoxicity, and 152 healthy controls using PCR and PCR-RFLP method. The haplotypes 1T and 2C enhanced the risk for severe hepatotoxicity (OR = 1.41, P = 0.25; OR = 1.67, P = 0.31). IL-1β-511TT genotype significantly represented among tobacco using HIV-infected individuals compared to nonusers (OR = 3.74, P = 0.05). IL-1β-511TT genotype among alcohol users increased the risk for hepatotoxicity (OR = 1.80, P = 0.90). IL-1β-511CT and -511TT genotypes overrepresented in alcohol using HIV-infected individuals (OR = 2.29, P = 0.27; OR = 2.64, P = 0.19). IL-RN 2/2 and 1/3 genotypes represented higher in nevirapine using hepatotoxicity patients (OR = 1.42, P = 0.64, OR = 8.79, P = 0.09). IL-1β-511CT and -511 TT genotypes among nevirapine users enhanced the risk for severe hepatotoxicity (OR = 4.29, P = 0.20; OR = 1.95, P = 0.56). IL-1β-511CT and -511TT genotypes were overrepresented in combined nevirapine and alcohol using HIV-infected individuals as compared to nevirapine users and alcohol nonusers (OR = 2.56, P = 0.26; OR = 2.84, P = 0.24). IL-1β-511TT genotype with tobacco, alcohol, and nevirapine usage revealed a trend of risk for the development of ARV-associated hepatotoxicity and its severity.

Polyphenols reported to shift APAP-induced changes in MAPK signaling and toxicity outcomes

Due to its widespread availability, acetaminophen (APAP) is the leading cause for drug-induced liver injury in many countries including United States and United Kingdom. When used as recommended, APAP is relatively safe. However, in overdose cases, increased metabolism of APAP to N-acetyl-para-benzoquinoneimine (NAPQI), a reactive metabolite, leads to glutathione (GSH) depletion, oxidative stress, and cellular injury. Throughout this process, a variety of factors play important roles in propagating toxicity, including c-Jun N-terminal kinase (JNK), a member of the mitogen-activated protein kinase (MAPK) family. Because of its involvement in multiple cellular processes, biomarkers associated with MAPK signaling have generated interest as a mechanistic target for protecting against APAP-induced liver injury and hepatocellular injury, in general. This review summarizes mechanistic details by which natural products, specifically those containing polyphenolic moieties, are capable of attenuating APAP-induced toxicity, at least in part through an ability to modulate MAPKs. These compounds include carnosic acid, chlorogenic acid, davallialactone, extracts from Hibiscus sabdariffa, quercetin-based compounds, and resveratrol. Despite variations in the experimental designs across these studies, common pathways and biomarkers were implicated in cytoprotection when polyphenolic compounds were given with APAP, such as enhanced antioxidant gene expression and reversal of APAP-induced changes in oxidative stress markers and MAPK signaling. Overall, an emphasis should be placed on method standardization for future studies if we are to gain a more in-depth understanding of how polyphenolic moieties contribute to cytoprotection during an APAP overdose event.

Changes in cellular proliferation and plasma products are associated with liver failure

AIM

To study the differences in immune response and cytokine profile between acute liver failure and self-limited acute hepatitis.

METHODS

Forty-six patients with self-limited acute hepatitis (AH), sixteen patients with acute liver failure (ALF), and twenty-two healthy subjects were involved in this study. The inflammatory and anti-inflammatory products in plasma samples were quantified using commercial enzyme-linked immunoassays and quantitative real-time PCR. The cellular immune responses were measured by proliferation assay using flow cytometry. The groups were divided into viral- and non-viral-induced self-limited AH and ALF. Thus, we worked with five groups: Hepatitis A virus (HAV)-induced self-limited acute hepatitis (HAV-AH), HAV-induced ALF (HAV-ALF), non-viral-induced self-limited acute hepatitis (non-viral AH), non-viral-induced acute liver failure (non-viral ALF), and healthy subjects (HC). Comparisons among HAV and non-viral-induced AH and ALF were performed.

RESULTS

The levels of mitochondrial DNA (mtDNA) and the cytokines investigated [interleukin (IL)-6, IL-8, IL-10, interferon gamma, and tumor necrosis factor] were significantly increased in ALF patients, independently of etiology (P < 0.05). High plasma mtDNA and IL-10 were the best markers associated with ALF [mtDNA: OR = 320.5 (95%CI: 14.42-7123.33), P < 0.0001; and IL-10: OR = 18.8 (95%CI: 1.38-257.94), P = 0.028] and death [mtDNA: OR = 12.1 (95%CI: 2.57-57.07), P = 0.002; and IL-10: OR = 8.01 (95%CI: 1.26-50.97), P = 0.027]. In the cellular proliferation assay, NK^bright, NKT and regulatory T cells (TReg) predominated in virus-specific stimulation in HAV-induced ALF patients with an anergic behavior in the cellular response to mitotic stimulation. Therefore, in non-viral-induced ALF, anergic behavior of activated T cells was not observed after mitotic stimulation, as expected and as described by the literature.

CONCLUSION

mtDNA and IL-10 may be predictors of ALF and death. TReg cells are involved in immunological disturbance in HAV-induced ALF.

Role of food-derived antioxidant agents against acetaminophen-induced hepatotoxicity

Context Acetaminophen (APAP), also known as paracetamol and N-acetyl p-aminophenol, is one of the most frequently used drugs for analgesic and antipyretic purposes on a worldwide basis. It is safe and effective at recommended doses but has the potential for causing hepatotoxicity and acute liver failure (ALF) with overdose. To solve this problem, different strategies have been developed, including the use of compounds isolated from food, which have been studied to characterize their efficacy as natural dietary antioxidants. Objective The objective of this study is to show the beneficial effects of a variety of natural compounds and their use against acetaminophen-induced hepatotoxicity. Methods PubMed database was reviewed to compile data about natural compounds with hepatoprotective effects against APAP toxicity. Results and conclusion As a result, the health-promoting properties of 13 different food-derived compounds with protective effect against APAP-induced hepatotoxicity were described as well as the mechanisms involved in hepatoprotection.

Phase II Multicenter, Randomized, Double-Blind Controlled Study of Efficacy and Safety of Umbilical Cord-Derived Mesenchymal Stromal Cells in the Prophylaxis of Chronic Graft-Versus-Host Disease After HLA-Haploidentical Stem-Cell Transplantation

PURPOSE

Although mesenchymal stromal cells (MSCs) possess immunomodulatory properties and exhibit promising efficacy against chronic graft-versus-host disease (cGVHD), little is known about the efficacy of MSCs in the prophylaxis of cGVHD after HLA-haploidentical hematopoietic stem-cell transplantation (HLA-haplo HSCT).

PATIENTS AND METHODS

In this multicenter, double-blind, randomized controlled trial, we investigated the incidence and severity of cGVHD among patients, and the changes in T, B, and natural killer (NK) cells after the repeated infusion of MSCs.

RESULTS

The 2-year cumulative incidence of cGVHD in the MSCs group was 27.4% (95% CI, 16.2% to 38.6%), compared with 49.0% (95% CI, 36.5% to 61.5%) in the non-MSCs control group (P = .021). Seven patients in the non-MSCs control group had severe lung cGVHD, but no patients in the MSCs group developed typical lung cGVHD (P = .047). After the MSC infusions, increasing memory B lymphocytes and regulatory T cells, as well as the ratio of type 1 T helper to type 2 T helper cells, were observed, whereas the number of NK cells decreased.

CONCLUSION

Our findings suggest that the repeated infusion of MSCs might inhibit cGVHD symptoms in patients after HLA-haplo HSCT, accompanied by changes in the numbers and subtypes of T, B, and NK cells, leading to the acquisition of immune tolerance.

The Dynamic Role of the IL-33/ST2 Axis in Chronic Viral-infections: Alarming and Adjuvanting the Immune Response

Interleukin 33 (IL-33), a member of the IL-1 family, is constitutively expressed in epithelial and in endothelial cells at barrier sites, acting as a danger signal and adjuvanting the immune response following tissue damage and infection. Originally implicated in allergy, IL-33 is also known to be involved in innate and adaptive immune responses by enhancing natural killer, Th1, and CD4 and CD8 T-cell functions. The nature of the antiviral immune response orchestrated by IL-33 depends on the site of infection, the duration of the disease and the cytokine milieu. In this review, we focus on the distinctive contribution of IL-33 as an anti-infective and proinflammatory cytokine in response to cell death and viral infections. The dynamic role of IL-33 in the acute and chronic phases of infection with HIV, hepatitis B and C viruses, and with CMV is highlighted. This review will also discuss the potential immunotherapeutic and adjuvant roles of IL-33.

Search Strategy and Selection Criteria

English language, indexed publications in PubMed were searched using combinations of following key words: “interleukin-33”, “IL-33”, “suppression of tumorigenicity 2”, ST2”, “sST2”, “HIV”, “HBV”, “HCV”, “CMV”, “HPV”, “immunotherapy” and “vaccine”. Except for seminal studies, only articles published between 2010 and 2016 were included.

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IL-33, a guardian of barriers, acts as an alarmin and as an enhancer of immune responses following injury or infection.

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sST2, the IL-33 decoy receptor, is considered as a biomarker for allergies, cardiac conditions and infections.

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IL-33 has immunotherapeutic and/or adjuvant potential.

Redox-Dependent HMGB1 Isoforms as Pivotal Co-Ordinators of Drug-Induced Liver Injury: Mechanistic Biomarkers and Therapeutic Targets

SIGNIFICANCE

High-mobility group box 1 (HMGB1) is a critical protein in the coordination of the inflammatory response in drug-induced liver injury (DILI). HMGB1 is released from necrotic hepatocytes and activated immune cells. The extracellular function of HMGB1 is dependent upon redox modification of cysteine residues that control chemoattractant and cytokine-inducing properties. Existing biomarkers of DILI such as alanine aminotransferase (ALT) have limitations such as lack of sensitivity and tissue specificity that can adversely affect clinical intervention.

RECENT ADVANCES

HMGB1 isoforms have been shown to be more sensitive biomarkers than ALT for predicting DILI development and the requirement for liver transplant following acetaminophen (APAP) overdose. Hepatocyte-specific conditional knockout of HMGB1 has demonstrated the pivotal role of HMGB1 in DILI and liver disease. Tandem mass spectrometry (MS/MS) enables the characterization and quantification of different mechanism-dependent post-translationally modified isoforms of HMGB1.

CRITICAL ISSUES

HMGB1 shows great promise as a biomarker of DILI. However, current diagnostic assays are either too time-consuming to be clinically applicable (MS/MS) or are unable to distinguish between different redox and acetyl isoforms of HMGB1 (ELISA). Additionally, HMGB1 is not liver specific, so while it outperforms ALT (also not liver specific) as a biomarker for the prediction of DILI development, it should be used in a biomarker panel along with liver-specific markers such as miR-122.

FUTURE DIRECTIONS

A point-of-care test for HMGB1 and the development of redox and acetyl isoform-targeting antibodies will advance clinical utility. Work is ongoing to validate baseline levels of circulating HMGB1 in healthy volunteers.

Critical review of resveratrol in xenobiotic-induced hepatotoxicity

Use of natural products is increasingly popular. In fact, many patients with liver diseases self-medicate with herbal supplements. Resveratrol (RSV), in particular, is a common natural product that can reduce injury in experimental models of liver disease. Xenobiotic hepatotoxicity is a particularly important area-of-need for therapeutics. Drug-induced liver injury, for example, is the most common cause of acute liver failure (ALF) and ALF-induced deaths in many countries. Importantly, RSV protects against hepatotoxicity in animal models in vivo caused by several drugs and chemicals and may be an effective intervention. Although many mechanisms have been proposed to explain the protection, not all are consistent with other data. Furthermore, RSV suffers from other issues, including limited bioavailability due to extensive hepatic metabolism. The purpose of this article is to summarize recent findings on the protective effects of RSV in xenobiotic-induced liver injury and other forms of liver injury and to provide a critical review of the underlying mechanisms. New mechanisms that are more consistent with data emerging from the toxicology field are suggested. Efforts to move RSV into clinical use are also considered. Overall, RSV is a promising candidate for therapeutic use, but additional studies are needed to better understand its effects.

Altered distribution of regulatory lymphocytes by oral administration of soy-extracts exerts a hepatoprotective effect alleviating immune mediated liver injury, non-alcoholic steatohepatitis and insulin resistance

AIM

To determine the immune-modulatory and the hepatoprotective effects of oral administration of two soy extracts in immune mediated liver injury and non-alcoholic steatohepatitis (NASH).

METHODS

Two soy extracts, M1 and OS, were orally administered to mice with concanavalin A (ConA) immune-mediated hepatitis, to high-fat diet (HFD) mice and to methionine and choline reduced diet combined with HFD mice. Animals were followed for disease and immune biomarkers.

RESULTS

Oral administration of OS and M1 had an additive effect in alleviating ConA hepatitis manifested by a decrease in alanine aminotransferase and aspartate aminotransferase serum levels. Oral administration of the OS and M1 soy derived fractions, ameliorated liver injury in the high fat diet model of NASH, manifested by a decrease in hepatic triglyceride levels, improvement in liver histology, decreased serum cholesterol and triglycerides and improved insulin resistance. In the methionine and choline reduced diet combined with the high fat diet model, we noted a decrease in hepatic triglycerides and improvement in blood glucose levels and liver histology. The effects were associated with reduced serum tumor necrosis factor alpha and alteration of regulatory T cell distribution.

CONCLUSION

Oral administration of the combination of OS and M1 soy derived extracts exerted an adjuvant effect in the gut-immune system, altering the distribution of regulatory T cells, and alleviating immune mediated liver injury, hyperlipidemia and insulin resistance.

Hepato-protective effect of resveratrol against acetaminophen-induced liver injury is associated with inhibition of CYP-mediated bioactivation and regulation of SIRT1-p53 signaling pathways

Resveratrol (RES) has been shown to possess many pharmacological activities including protective effect against liver damage induced by hepatotoxins. In the present study, the hepato-protective effect of RES against acetaminophen (APAP)-induced liver injury in mice and the involved mechanisms was investigated. This study clearly demonstrated that administration of RES three days before APAP treatment significantly alleviated APAP-induced hepatotoxicity, as evidenced by morphological, histopathological, and biochemical assessments such as GSH content and serum ALT/AST activity. Treatment with RES resulted in significant inhibition of CYP2E1, CYP3A11, and CYP1A2 activities, and then caused significant inhibition of the bioactivation of APAP into toxic metabolite NAPQI. Pretreatment with RES significantly reduced APAP-induced JNK activation to protect against mitochondrial injury. Additionally, RES treatment significantly induced SIRT1 and then negatively regulated p53 signaling to induce cell proliferation-associated proteins including cyclin D1, CDK4, and PCNA to promote hepatocyte proliferation. This study demonstrated that RES prevents APAP-induced hepatotoxicity by inhibition of CYP-mediated APAP bioactivation and regulation of SIRT1, p53, cyclin D1 and PCNA to facilitate liver regeneration following APAP-induced liver injury.

Resveratrol prevents protein nitration and release of endonucleases from mitochondria during acetaminophen hepatotoxicity

Overdose of acetaminophen (APAP) is a common cause of acute liver injury and liver failure. The mechanism involves formation of a reactive metabolite, protein binding, oxidative stress and activation of c-Jun N-terminal kinase (JNK), mitochondrial dysfunction, and nuclear DNA fragmentation caused by endonucleases released from damaged mitochondria. Previous work has shown that the natural product resveratrol (RSV) can protect against APAP hepatotoxicity in mice through prevention of lipid peroxidation and anti-inflammatory effects. However, these earlier studies did not take into consideration several fundamental aspects of the pathophysiology. To address this, we treated C57Bl/6 mice with 300 mg/kg APAP followed by 50 mg/kg RSV 1.5 h later. Our results confirmed that RSV reduced liver injury after APAP overdose in mice. Importantly, RSV did not inhibit reactive metabolite formation and protein bindings, nor did it reduce activation of JNK. However, RSV decreased protein nitration after APAP treatment, possibly through direct scavenging of peroxynitrite. Interestingly, RSV also inhibited release of apoptosis-inducing factor and endonuclease G from mitochondria independent of Bax pore formation and prevented the downstream nuclear DNA fragmentation. Our data show that RSV protects against APAP hepatotoxicity both through antioxidant effects and by preventing mitochondrial release of endonucleases and nuclear DNA damage.

Acetaminophen-induced acute liver injury in mice

The induction of acute hepatic damage by acetaminophen (N-acetyl- p-aminophenol [APAP]), also termed paracetamol, is one of the most commonly used experimental models of acute liver injury in mice. The specific values of this model are the highly reproducible, dose-dependent hepatotoxicity of APAP and its outstanding translational importance, because acetaminophen overdose is one of the most frequent reasons for acute liver failure (ALF) in humans. However, preparation of concentrated APAP working solutions, application routes, fasting period and variability due to sex, genetic background or barrier environment represent important considerations to be taken into account before implementing this model. This standard operating procedure (SOP) provides a detailed protocol for APAP preparation and application in mice, aimed at facilitating comparability between research groups as well as minimizing animal numbers and distress. The mouse model of acetaminophen poisoning therefore helps to unravel the pathogenesis of APAP-induced toxicity or subsequent immune responses in order to explore new therapeutic interventions for improving the prognosis of ALF in patients.

T-helper cell-mediated factors in drug-induced liver injury

Drug-induced liver injury (DILI) leads to a large burden on the healthcare system due to its potential morbidity and mortality. The key for predicting and preventing DILI is to understand the underlying mechanisms. Hepatic inflammation is one of the most common features of DILI. The inflammation can be attributed to the innate immune response. The adaptive immune system is also affected by the innate immune response resulting in liver damage. T-helper cells are important regulators of acquired immunity. T-helper cell-mediated immune responses play pivotal roles in the pathogenesis of a variety of liver disorders. This review summarizes recent advances in the T-helper cell-mediated factors in DILI and potential mechanisms, which may lead to a better understanding of DILI.

Regulatory T cells ameliorate acetaminophen-induced immune-mediated liver injury

The contribution of innate immune cells to acetaminophen (APAP)-induced liver injury has been extensively investigated. However, the roles of T cell populations among adaptive immune cells in APAP-induced liver injury remain to be elucidated. Herein, we found that distinct CD4(+) T cell subsets but not CD8(+) T cells modulated APAP-induced liver injury in mice. After APAP challenge, more CD62L(low)CD44(hi)CD4(+) T cells appeared in the liver, accompanied by increased IFN-γ. The removal of CD4(+) T cells by either antibody depletion or genetic deficiency markedly compromised pro-inflammatory cytokine levels and ameliorated liver injury. Meanwhile, we also found that the frequency and absolute number of Treg cells also increased. Treg cell depletion increased hepatic CD62L(low)CD44(hi)CD4(+) T cells, augmented pro-inflammatory cytokines, and exacerbated liver injury, while adoptive transfer of Treg cells ameliorated APAP-induced liver injury. Furthermore, the recruitment of Treg cells into the liver through specific expression of CXCL10 in the liver could ameliorate APAP-induced liver injury. Our investigation suggests that Th1 and Treg subsets are involved in regulating APAP-induced liver injury. Thus, modulating the Th1/Treg balance may be an effective strategy to prevent and/or treat APAP-induced liver injury.

Immune mechanisms in acetaminophen-induced acute liver failure

An overdose of acetaminophen (N-acetyl-p-aminophenol, APAP), also termed paracetamol, can cause severe liver damage, ultimately leading to acute liver failure (ALF) with the need of liver transplantation. APAP is rapidly taken up from the intestine and metabolized in hepatocytes. A small fraction of the metabolized APAP forms cytotoxic mitochondrial protein adducts, leading to hepatocyte necrosis. The course of disease is not only critically influenced by dose of APAP and the initial hepatocyte damage, but also by the inflammatory response following acetaminophen-induced liver injury (AILI). As revealed by mouse models of AILI and corresponding translational studies in ALF patients, necrotic hepatocytes release danger-associated-molecular patterns (DAMPs), which are recognized by resident hepatic macrophages, Kupffer cell (KC), and neutrophils, leading to the activation of these cells. Activated hepatic macrophages release various proinflammatory cytokines, such as TNF-α or IL-1β, as well as chemokines (e.g., CCL2) thereby further enhancing inflammation and increasing the influx of immune cells, like bone-marrow derived monocytes and neutrophils. Monocytes are mainly recruited via their receptor CCR2 and aggravate inflammation. Infiltrating monocytes, however, can mature into monocyte-derived macrophages (MoMF), which are, in cooperation with neutrophils, also involved in the resolution of inflammation. Besides macrophages and neutrophils, distinct lymphocyte populations, especially γδ T cells, are also linked to the inflammatory response following an APAP overdose. Natural killer (NK), natural killer T (NKT) and T cells possibly further perpetuate inflammation in AILI. Understanding the complex interplay of immune cell subsets in experimental models and defining their functional involvement in disease progression is essential to identify novel therapeutic targets for human disease.

Advantages and Limitations of Commonly Used Nonhuman Primate Species in Research and Development of Biopharmaceuticals

Nonhuman primates (NHPs) have been used extensively during the past four decades for research and nonclinical development because they are close to humans in terms of genetics, anatomy, physiology, and immunology. They have been widely used in the development of infection models, leading to the generation of vaccines and drugs, as well as in the nonclinical pharmacologic and toxicologic assessment of biopharmaceuticals, especially in the fields of immunotherapy and oncology, despite the constant pressure to move to lower species. In many cases, NHPs are the only species that allows a correct risk assessment for humans. Nevertheless, limitations inherent to each species have to be considered before an investigation. This chapter shines some light on the respective interests and limitations of using cynomolgus monkeys, rhesus monkeys, and marmosets in medical research and nonclinical development, with a specific focus on reproduction and immunology.

Soluble ST2 plasma concentrations predict mortality in HBV-related acute-on-chronic liver failure

Hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) is a rapidly progressing and frequently fatal condition. The aim of this study was to determine whether interleukin- (IL-) 33 and soluble ST2 (sST2) were associated with disease severity and mortality in HBV-ACLF. We found that plasma levels of sST2 but not IL-33 were higher in HBV-ACLF patients compared with chronic hepatitis B (CHB) patients and healthy controls. However, plasma levels of IL-33, TNF-α, IFN-γ, and IL-10 did not correlate with sST2 levels. Similarly, immunohistochemistry revealed low IL-33 expression and high ST2 expression in liver sections of patients with HBV-ACLF. Evaluation of dynamic changes of sST2 in HBV-ACLF showed that plasma sST2 levels increased over time in patients who died during the 180-day follow-up but decreased in those who survived. In addition, plasma sST2 level after week 1 correlated with disease severity, as assessed by total bilirubin, prothrombin time, and model for end-stage liver disease score. Results of Kaplan-Meier survival analysis showed that higher sST2 concentration (≥87 ng/mL) at week 3 was associated with poor survival. These findings indicate the potential usefulness of sST2 as a predictor of disease severity and in making treatment decisions for patients with HBV-ACLF.

Protective effects of resveratrol on hepatotoxicity induced by isoniazid and rifampicin via SIRT1 modulation

Acute liver injury was induced in male BALB/c mice by coadministering isoniazid and rifampicin. In this work, the effects of resveratrol (1) were investigated in the hepatotoxicity caused by isoniazid-rifampicin in mice. Compound 1 was administered 30 min prior to isoniazid-rifampicin. Serum biochemical tests, liver histopathological examination, oxidative stress, myeloperoxidase activity, cytokine production (TNF-α, IL-12p70, and IL-10), and mRNA expression of SIRT1-7 and PPAR-γ/PGC1-α were evaluated. The administration of 1 significantly decreased aspartate transaminase and alanine aminotransferase levels, myeloperoxidase activity, and cytokine levels. Furthermore, 1 reverted the decrease of catalase and glutathione activities and ameliorated the histopathological alterations associated with antituberculosis drugs. Modulation of SIRT1 and PPAR-γ/PGC1-α expression is likely involved in the protective effects of 1. The results presented herein show that 1 was able to largely prevent the hepatotoxicity induced by isoniazid and rifampicin in mice, mainly by modulating SIRT1 mRNA expression.

Effect of dietary supplementation with resveratrol on nutrient digestibility, methanogenesis and ruminal microbial flora in sheep

Two experiments were conducted to evaluate the effect of resveratrol on methanogenesis and microbial flora in Dorper × thin-tailed Han cross-bred ewes. In experiment 1, ten ewes (67.2 ± 2.24 kg BW) were assigned to two dietary treatments, a basal diet and a basal diet supplemented with resveratrol (0.25 g/head·day), to investigate the effect of resveratrol on nutrient digestibility and nitrogen balance. In experiment 2, six ewes (64.0 ± 1.85 kg BW) with ruminal cannulae were assigned to the identical dietary treatments used in experiment 1 to investigate supplementary resveratrol on ruminal fermentation and microbial flora using qPCR. The results showed that supplementary resveratrol improved the digestibility of organic matter (OM; p < 0.001), nitrogen (N; p = 0.007), neutral detergent fibre (NDF; p < 0.001) and acid detergent fibre (ADF; p < 0.001). The excretion of faecal N was reduced (p = 0.007), whereas that of urinary N increased (p = 0.002), which led to an unchanged N retention (p = 0.157). Both CO2 and CH4 output scaled to digestible dry matter (DM) intake decreased from 602.5 to 518.7 (p = 0.039) and 68.2 to 56.6 (p < 0.001) respectively. Ruminal pH (p = 0.341), ammonia (p = 0.512) and total volatile fatty acid (VFA) (p = 0.249) were unaffected by resveratrol. The molar proportion of propionate increased from 13.1 to 17.5% (p < 0.001) while that of butyrate decreased from 11.0 to 9.55% (p < 0.001). The ratio of acetate to propionate (A/P) decreased from 5.44 to 3.96 (p < 0.001). Supplementary resveratrol increased ruminal population of Fibrobacter succinogenes, Ruminococcus albus and Butyrivibrio fibrisolvens (p < 0.001) while decreased protozoa and methanogens. In conclusion, dietary resveratrol inhibited methanogenesis without adversely affecting ruminal fermentation.

Effects and mechanisms of resveratrol on the amelioration of oxidative stress and hepatic steatosis in KKAy mice

Background

The exact mechanism of the protective role of Resveratrol (Res) in lipid metabolism and oxidative stress is not well elucidated. The present study aimed to investigate the potential benefits and possible mechanisms of Res on the amelioration of oxidative stress and hepatic steatosis in a KKAy mouse model.

Methods

A total of 30 KKAy male mice were randomly divided into three groups: a normal chow group, a low resveratrol group and a high resveratrol group. After a 12-wk study period, serum levels of TG, TC, LDL-C and HDL-C, the liver content of TG and TC, ROS, GSH, GPx, SOD and MDA levels were measured. Ectopic lipid deposition was observed in sectioned frozen liver tissues. The mRNA levels of ATGL and HSL in the liver tissues were determined via real-time PCR. Furthermore, the protein expression of p47phox, gp91phox, ATGL, HSL, Sirt1, AMPK and FOXO1 were analyzed using western blotting.

Results

Following Res supplementation, serum levels of TG and MDA were decreased, while the HDL-C and SOD levels were increased in KKAy mice. Furthermore, Res treatment increased GSH and GPx in liver tissues, while it decreased ROS. In addition, Res significantly reduced hepatic steatosis. After Res treatment, concentrations of p47phox (membrane) and gp91phox proteins were reduced, while p-HSL, HSL and ATGL protein expression levels were increased. Mechanistically, the levels of Sirt1, p-AMPK and p-FOXO1 expression in the liver tissues were up-regulated following supplementation with Res, and FOXO1 protein was released from the nucleus into the cytoplasm.

Conclusions

Res is able to attenuate hepatic steatosis and lipid metabolic disorder and enhance the antioxidant ability in KKAy mice, possibly by up-regulating Sirt1 expression and the phosphorylation of AMPK.

Drug-induced hepatotoxicity: metabolic, genetic and immunological basis

Drug-induced hepatotoxicity is a significant cause of acute liver failure and is usually the primary reason that therapeutic drugs are removed from the commercial market. Multiple mechanisms can culminate in drug hepatotoxicity. Metabolism, genetics and immunology separately and in concert play distinct and overlapping roles in this process. This review will cover papers we feel have addressed these mechanisms of drug-induced hepatotoxicity in adults following the consumption of commonly used medications. The aim is to generate discussion around "trigger point" papers where the investigators generated new science or provided additional contribution to existing science. Hopefully these discussions will assist in uncovering key areas that need further attention.

Nuclear receptors in the cross-talk of drug metabolism and inflammation

Inflammation and infection have long been known to affect the activity and expression of enzymes involved in hepatic and extrahepatic drug clearance. Significant advances have been made to elucidate the molecular mechanisms underlying the complex cross-talk between inflammation and drug-metabolism alterations. The emergent role of ligand-activated transcriptional regulators, belonging to the nuclear receptor (NR) superfamily, is now well established. The NRs, pregnane X receptor, constitutive androstane receptor, retinoic X receptor, glucocorticoid receptor, and hepatocyte nuclear factor 4, and the basic helix-loop-helix/Per-ARNT-Sim family member, aryl hydrocarbon receptor, are the main regulators of the detoxification function. According to the panel of mediators secreted during inflammation, a cascade of numerous signaling pathways is activated, including nuclear factor kappa B, mitogen-activated protein kinase, and the Janus kinase/signal transducer and activator of transcription pathways. Complex cross-talk is established between these signaling pathways regulating either constitutive or induced gene expression. In most cases, a mutual antagonism between xenosensor and inflammation signaling occurs. This review focuses on the molecular and cellular mechanisms implicated in this cross-talk.

Hepatoprotective effect of DT56a is associated with changes in natural killer T cells and regulatory T cells

OBJECTIVE

To determine the metabolic and immunological effects of the oral administration of DT56a, an enzymatic isolate of soybeans.

METHODS

DT56a was orally administered to mice in three animal models: leptin deficiency, high-fat diet (HFD) supplementation and immune-mediated hepatitis. Liver damage and immunological status were assessed.

RESULTS

Oral administration of DT56a to leptin-deficient (ob/ob) and HFD mice led to a significant reduction in serum triglyceride (TG) and total cholesterol (TC) levels. DT56a-treated mice in both models exhibited a significant reduction in hepatic levels of TG and marked alleviation of glycemic control as indicated by significant decreases in fasting blood glucose levels and glucose tolerance tests. The levels of liver enzymes were reduced. These metabolic effects were associated with altered distributions of regulatory T (Tregs) and natural killer T (NKT) cells. DT56a suppressed the immune-mediated liver damage induced by concanavalin A indicated by decreased liver enzymes and serum interferon-γ levels and by improved histology and decreased hepatic apoptosis. Oral administration of DT56a also alleviated immune-mediated hepatitis and affected Tregs and NKT cells.

CONCLUSIONS

Oral administration of DT56a promotes a hepatoprotective effect associated with an alteration in the distribution of Tregs and NKT cells.

Ozagrel hydrochloride, a selective thromboxane A₂ synthase inhibitor, alleviates liver injury induced by acetaminophen overdose in mice

Background

Overdosed acetaminophen (paracetamol, N-acetyl-p-aminophenol; APAP) causes severe liver injury. We examined the effects of ozagrel, a selective thromboxane A₂ (TXA₂) synthase inhibitor, on liver injury induced by APAP overdose in mice.

Methods

Hepatotoxicity was induced to ICR male mice by an intraperitoneal injection with APAP (330 mg/kg). The effects of ozagrel (200 mg/kg) treatment 30 min after the APAP injection were evaluated with mortality, serum alanine aminotransferase (ALT) levels and hepatic changes, including histopathology, DNA fragmentation, mRNA expression and total glutathione contents. The impact of ozagrel (0.001-1 mg/mL) on cytochrome P450 2E1 (CYP2E1) activity in mouse hepatic microsome was examined. RLC-16 cells, a rat hepatocytes cell line, were exposed to 0.25 mM N-acetyl-p-benzoquinone imine (NAPQI), a hepatotoxic metabolite of APAP. In this model, the cytoprotective effects of ozagrel (1–100 muM) were evaluated by the WST-1 cell viability assay.

Results

Ozagel treatment significantly attenuated higher mortality, elevated serum alanine aminotransferase levels, excessive hepatic centrilobular necrosis, hemorrhaging and DNA fragmentation, as well as increase in plasma 2,3-dinor thromboxane B₂ levels induced by APAP injection. Ozagrel also inhibited the hepatic expression of cell death-related mRNAs induced by APAP, such as jun oncogene, FBJ osteosarcoma oncogene (fos) and C/EBP homologous protein (chop), but did not suppress B-cell lymphoma 2-like protein11 (bim) expression and hepatic total glutathione depletion. These results show ozagrel can inhibit not all hepatic changes but can reduce the hepatic necrosis. Ozagrel had little impact on CYP2E1 activity involving the NAPQI production. In addition, ozagrel significantly attenuated cell injury induced by NAPQI in RLC-16.

Conclusions

We demonstrate that the TXA₂ synthase inhibitor, ozagrel, dramatically alleviates liver injury induced by APAP in mice, and suggest that it is a promising therapeutic candidate for the treatment of APAP-induced liver injury.

Protective effects of goldenseal (Hydrastis canadensis L.) on acetaminophen-induced hepatotoxicity through inhibition of CYP2E1 in rats

Background:

Goldenseal (Hydrastis canadensis L.) inhibits various cytochrome P450 (CYP) isoforms such as CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A in vitro. High doses of acetaminophen (APAP) generate the highly reactive intermediate, N-acetyl-p-benzoquinone imine (NAPQI), catalyzed mainly by CYP2E1. The aim of this study was to investigate the hepatoprotective effects of orally administrated goldenseal against APAP-induced acute liver failure (ALF) via inhibition of CYP2E1.

Materials and Methods:

Male Wistar rats were treated orally with goldenseal (300 and 1000 mg/kg) 2, 18, and 26 h before and 6 h after oral APAP (400 mg/kg) administration. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities as well as serum APAP concentration were evaluated.

Results:

Goldenseal extract inhibited CYP1A2, CYP2D6, CYP2E1, and CYP3A activity, and the inhibitory effect on CYP2E1 was the strongest (IC₅₀ 4.32 μg/mL). Treatment with goldenseal (300 mg/kg) significantly attenuated the APAP-induced increase in serum AST and ALT, and the hepatoprotective effect of goldenseal was stronger than that of silymarin (200 mg/kg). Moreover, serum APAP concentration was increased by goldenseal treatment, presumably as a result of the inhibitory effect of goldenseal on the metabolism of APAP to NAPQI.

Conclusion:

These results suggest that goldenseal ameliorates APAP-induced ALF and that this protection can likely be attributed to the inhibition of CYP2E1 activity, which generates the highly reactive intermediate of APAP.

N. V, Umapathy S, Nandi D. Identification of early biomarkers during acetaminophen-induced hepatotoxicity by fourier transform infrared microspectroscopy

Acetaminophen is a widely prescribed drug used to relieve pain and fever; however, it is a leading cause of drug-induced liver injury and a burden on public healthcare. In this study, hepatotoxicity in mice post oral dosing of acetaminophen was investigated using liver and sera samples with Fourier Transform Infrared microspectroscopy. The infrared spectra of acetaminophen treated livers in BALB/c mice show decrease in glycogen, increase in amounts of cholesteryl esters and DNA respectively. Rescue experiments using L-methionine demonstrate that depletion in glycogen and increase in DNA are abrogated with pre-treatment, but not post-treatment, with L-methionine. This indicates that changes in glycogen and DNA are more sensitive to the rapid depletion of glutathione. Importantly, analysis of sera identified lowering of glycogen and increase in DNA and chlolesteryl esters earlier than increase in alanine aminotransferase, which is routinely used to diagnose liver damage. In addition, these changes are also observed in C57BL/6 and Nos2^−/− mice. There is no difference in the kinetics of expression of these three molecules in both strains of mice, the extent of damage is similar and corroborated with ALT and histological analysis. Quantification of cytokines in sera showed increase upon APAP treatment. Although the levels of Tnfα and Ifnγ in sera are not significantly affected, Nos2^−/− mice display lower Il6 but higher Il10 levels during this acute model of hepatotoxicity. Overall, this study reinforces the growing potential of Fourier Transform Infrared microspectroscopy as a fast, highly sensitive and label-free technique for non-invasive diagnosis of liver damage. The combination of Fourier Transform Infrared microspectroscopy and cytokine analysis is a powerful tool to identify multiple biomarkers, understand differential host responses and evaluate therapeutic regimens during liver damage and, possibly, other diseases.

Protective effects of exogenous glutathione and related thiol compounds against drug-induced liver injury

An overdose of acetaminophen (APAP) causes liver injury both in experimental animals and humans. N-acetylcysteine (NAC) is clinically used as an antidote for APAP intoxication, and it is thought to act by providing cysteine as a precursor of glutathione, which traps a reactive metabolite of APAP. Other hepatoprotective mechanisms of NAC have also been suggested. Here, we examined the effects of thiol compounds with different abilities to restore hepatic glutathione, on hepatotoxicity of APAP and furosemide in mice. Overnight-fasted male CD-1 mice were given APAP or furosemide intraperitoneally. NAC, cysteine, glutathione, or glutathione-monoethyl ester was administered concomitantly with APAP or furosemide. All thiol compounds used in this study effectively protected mice against APAP-induced liver injury. Only glutathione-monoethyl ester completely prevented APAP-induced early hepatic glutathione depletion. Cysteine also significantly restored hepatic glutathione levels. NAC partially restored glutathione levels. Exogenous glutathione had no effect on hepatic glutathione loss. NAC and glutathione highly stimulated the hepatic expression of cytokines, particularly interleukin-6, which might be involved in the alleviation of APAP hepatotoxicity. Furosemide-induced liver injury, which does not accompany hepatic glutathione depletion, was also attenuated by NAC and exogenous glutathione, supporting their protective mechanisms other than replenishment of glutathione. In conclusion, exogenous thiols could alleviate drug-induced liver injury. NAC and glutathione might exert their effects, at least partially, via mechanisms that are independent of increasing hepatic glutathione, but probably act through cytokine-mediated and anti-inflammatory mechanisms.