A Missense Variant in PTPN22 is a Risk Factor for Drug-induced Liver Injury

Pharmacogenomic Considerations in Antibiotic Therapy: A Pathway to Personalized Medicines with Antibiotic Use

Antibiotics have revolutionized medicine, but their use is not without challenges. The efficacy and safety of antibiotics can vary significantly among individuals due to genetic differences. Genetic variation can influence the risk of antibiotic-related adverse effects, and understanding genetics can improve our ability to identify and manage these risks. Pharmacogenomics, the study of how genes affect a person's response to drugs, is emerging as a crucial field in optimizing antibiotic therapy. Pharmacogenomic elements may have a potential role in optimizing drug therapy and reducing adverse drug reactions.

DILI prediction in drug development: present and future

INTRODUCTION

Idiosyncratic drug-induced liver injury (iDILI) results in significant patient morbidity and significantly increases the risk of drug development. The current methods to screen for iDILI risk are inadequate.

AREAS COVERED

The general mechanism of iDILI and the current methods to screen for iDILI are reviewed. Then the potential for new biomarkers is explored.

EXPERT OPINION

Better biomarkers of iDILI risk should be based on the mechanism of iDILI. In general, it is an adaptive immune response, specifically CD8+ cytotoxic T cells, that is responsible for hepatocyte cell death, not direct toxicity of the drug. Therefore, in vitro cytotoxicity assays represent an artifact not the mechanism of iDILI. Activation of the adaptive immune response leading to iDILI requires an innate immune response, in particular activation of antigen presenting cells. The innate immune response is immediate and unlikely to be idiosyncratic. For example, studies have found that incubation of hepatocytes with drugs causes the release of molecules that activate THP-1-derived macrophages. The response of hepatocytes, the release of damage-associated molecular pattern molecules (DAMPs), especially in extracellular vesicles, and the response of antigen presenting cells (APCs) are likely to provide better biomarkers of iDILI risk.

Mechanisms of drug induced liver injury

Drug induced liver injury (DILI) is a serious and potentially life-threatening condition resulting from an adverse drug reaction. Both the clinical manifestations and pathological mechanisms of DILI vary depending on drug characteristics, dose, duration of exposure as well as host specific factors. Disease onset can occur within days or months after the introduction of a drug. This has challenged identification of disease specific biomarkers and resulted in delayed and even erroneous diagnosis of patients. Apart from discontinuation of current pharmacotherapy, options for DILI patients are scarce and the condition can sometimes continue or worsen after drugs are discontinued or result in irreversible liver damage such as cirrhosis. This illustrates the need to uncover relevant pathological pathways that will pave the road for targeted interventions. In an effort to accommodate these needs, novel insights from preclinical and cellular disease modeling have allowed coupling of specific drugs to potential mechanisms of toxicity. This review outlines three signaling pathways of DILI: organelle stress, cholestasis, and immune responses, discusses their interplay with oxidative stress, and provides examples of drugs specifically targeting one or more steps in these pathways. A systematic approach identifying specific mechanisms of DILI could allow for the assembly of large databases, in turn enabling advanced computational modelling to provide accurate predictions of the DILI potential of both known drugs and future drug candidates.

Risk factors and prediction for DILI in clinical practice

INTRODUCTION

Drug-induced liver injury is an important adverse effect and can be caused by various medications, including novel therapeutic agents. The risk stratification of patients susceptible to DILI is a growing field.

AREAS COVERED

The current article highlights new studies on risk stratification regarding risk factors of DILI, prediction of liver injury, and predictors of severe outcomes. Studies on patient demographic and genetic risk factors are discussed, in addition to the potential role of concomitant medications that may affect the risk of DILI.

EXPERT OPINION

Although much is known about patient risk factors for DILI, a better combination of these factors into risk scores is needed to predict which patients are particularly susceptible. Knowledge of these risk factors might determine drug treatment in the near future, as well as the need for routine monitoring of liver tests.

Drug-Induced Liver Injury

Drug-induced liver injury (DILI) is an underrecognized cause of hepatic disease in dogs and cats. Successful identification of cases requires an initial suspicion by the practitioner, a thorough drug exposure history, and knowledge of the toxic potential for common veterinary drugs. This article reviews the pathogenesis, classification, and diagnosis of DILI in small animals. It also discusses the clinical presentation, prevalence, and outcomes of DILI for several drugs important in veterinary medicine including azathioprine, azole antifungals, carprofen, diazepam, doxycycline, lomustine, methimazole, phenobarbital, rifampin, sulfonamide antibiotics, and zonisamide, as well as the toxic potential for nutraceuticals and herbal preparations.

Identification of key immune genes of drug-induced liver injury induced by tolvaptan based on bioinformatics

Drug-induced liver injury (DILI) poses critical challenges in preclinical drug development and is a primary reason for candidate drug attrition. The incidence of DILI has risen in recent years. While immune-related genes (IRGs) are crucial in immune infiltration, their expression and regulatory mechanisms in tolvaptan-induced DILI remain largely uncharacterized. RNA sequencing data related to DILI and associated clinical data were sourced from the Gene Expression Omnibus (GEO), and IRGs were obtained from the ImmPort database. Differentially expressed genes (DEGs) from DILI and IRGs were intersected to identify differentially expressed immune-related genes (DEIRGs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were used to elucidate the biological functions of DEIRGs. In addition, a protein-protein interaction (PPI) network of DEIRGs was constructed. Immunocytes and immune regulation analyses were conducted using the CIBERSORT tool. Receiver operating characteristic (ROC) curves were constructed to assess the diagnostic accuracy of individual DEIRGs. Networks of transcription factor and microRNA co-regulation were constructed using the NetworkAnalyst database. The expression of DEIRGs in DILI samples was quantified with RT-qPCR. From GSE99878, 204 DEGs were identified, with 23 matching IRGs exhibiting significant expression differences in 17 DEIRGs. The ROC curve analysis suggested satisfactory diagnostic values for six DEIRGs. The potential gene regulatory network comprised 214 microRNAs, 257 transcription factors, and 23 DEIRGs. Finally, RT-qPCR confirmed the expression levels of nine DEIRGs, aligning with public database results. The study revealed numerous immune-related biomarkers, verifying expression in five pivotal genes (ICAM1, CXCL10, IGF1, CX3CL1, and EGFR) and highlighting four genes with notable diagnostic potential (TNFAIP3, BDNF, NR1D2, and PPARA). Additionally, it explored the roles of key biomarkers in inflammatory responses, relevant signaling pathways, and interaction networks, offering new insights into DILI diagnosis, mechanistic understanding, and treatment strategies.

Drug-induced liver injury. Part I: Classification, diagnosis and treatment

Drug-induced liver injury (DILI) is a growing clinical problem. Antibiotics remain the most common cause of DILI in Europe. Their clinical spectrum is very broad, from asymptomatic to acute liver failure. Currently, DILI is categorized as hepatocellular (R ≥ 5), cholestatic (R ≤ 2) or mixed (R = 2-5) injury based on the serum alanine aminotransferase (ALT)/alkaline phosphatase (ALP) ratio. DILI is a diagnosis of exclusion and requires a wide differential diagnosis. The most important step in management is discontinuation of the drug suspected of causing liver damage. The list of specific antidotes that eliminate the effects of hepatotoxins is unfortunately very short. In symptomatic treatment, glucocorticosteroids and ursodeoxycholic acid have been used in selected cases. Liver transplantation is an optional treatment in patients with acute liver failure.

Liver Injury due to Intravenous Methylprednisolone in the Drug-Induced Liver Injury Network

BACKGROUND AND AIMS

Short courses of intravenous (iv) methylprednisolone (MP) can cause drug induced liver injury (DILI). The aim of this study was to assess the clinical features and HLA associations of MP-related DILI enrolled in the US DILI Network (DILIN).

METHODS

DILIN cases with MP as a suspected drug were reviewed. DILIN causality scoring was assigned on a 5-point scale (definite, highly likely, probable, possible, unlikely). All cases with MP causality scores of definite, highly likely or probable were analysed. HLA data from direct sequencing were analysed.

RESULTS

Eleven cases of definite, highly likely, or probable MP DILI were identified. The median age was 48 years; 73% were female; median latency to onset was 30 days; 55% were jaundiced; and all had hepatocellular injury with one patient requiring transplantation. Nine of the 11 cases were in patients with multiple sclerosis (MS). Liver biopsies in 7 cases revealed mild acute hepatitis with/without cholestasis. HLA data demonstrated that HLA-DRB1*15:01, the primary HLA class II allele associated with MS was over-represented. HLA-DQB1*06:02-HLA-DQA1*01:02 which is haplotypic with the HLA-DRB1*15 haplotype was more common in the MP DILI cases compared to other DILI controls (p = 0.03) and to DILI controls exposed to MP (p = 0.04).

CONCLUSION

MP DILI is characterised by hepatocellular injury, short latency and generally rapid recovery. There was no independent HLA haplotype associated with MP DILI.

Polygenic modelling and machine learning approaches in pharmacogenomics: Importance in downstream analysis of genome-wide association study data

Genome-wide association studies (GWAS) have identified genetic variations associated with adverse drug effects in pharmacogenomics (PGx) research. However, interpreting the biological implications of these associations remains a challenge. This review highlights 2 promising post-GWAS methods for PGx. First, we discuss the polygenic architecture of the PGx traits, especially for drug-induced liver injury. Experimental modelling using multiple donors' human primary hepatocytes and human liver organoids demonstrated the polygenic architecture of drug-induced liver injury susceptibility and found biological vulnerability in genetically high-risk tissue donors. Second, we discuss the challenges of interpreting the roles of variants in noncoding regions. Beyond methods involving expression quantitative trait locus analysis and massively parallel reporter assays, we suggest the use of in silico mutagenesis through machine learning methods to understand the roles of variants in transcriptional regulation. This review underscores the importance of these post-GWAS methods in providing critical insights into PGx, potentially facilitating drug development and personalized treatment.

Genetic and Genomic Approaches to the Study of Drug-Induced Liver Injury

Idiosyncratic hepatotoxicity induced by prescribed drugs has been known since the early 20th century. Identifying risk factors, including genetic factors, that trigger this drug-induced liver injury (DILI) has been an important priority for many years, both to prevent drugs that cause liver injury being licensed and as a potential means of preventing at-risk patients being prescribed causative drugs. Improved methods for genomic analysis, particularly the development of genome-wide association studies, have facilitated the identification of genomic risk factors for DILI, but, to date, there are only two main examples, liver injury caused by amoxicillin-clavulanate (AC) and by flucloxacillin, where genetic risk factors causing the injury have been identified and replicated with understanding of the underlying mechanism. There has also been progress on identifying genetic risk factors for liver injury caused by other anti-infective agents, herbal remedies and nonsteroidal anti-inflammatory drugs. The majority of genetic risk factors identified to date are specific human leucocyte antigen (HLA) alleles and evidence that these alleles preferentially present self-peptides inappropriately to T cells in the liver has been obtained. Non-HLA genes also contribute to genetic susceptibility, both as co-factors in T-cell responses and, in the case of isoniazid-only, drug metabolism. Polygenic risk scores to predict DILI have been developed, both a simple score that predicts AC injury and complex scores that may be applied to DILI more generally and provide evidence that additional risk factors other than HLA genes exist.

Hepatic immune regulation and sex disparities

Chronic liver disease is a major cause of morbidity and mortality worldwide. Epidemiology, clinical phenotype and response to therapies for gastrointestinal and liver diseases are commonly different between women and men due to sex-specific hormonal, genetic and immune-related factors. The hepatic immune system has unique regulatory functions that promote the induction of intrahepatic tolerance, which is key for maintaining liver health and homeostasis. In liver diseases, hepatic immune alterations are increasingly recognized as a main cofactor responsible for the development and progression of chronic liver injury and fibrosis. In this Review, we discuss the basic mechanisms of sex disparity in hepatic immune regulation and how these mechanisms influence and modify the development of autoimmune liver diseases, genetic liver diseases, portal hypertension and inflammation in chronic liver disease. Alterations in gut microbiota and their crosstalk with the hepatic immune system might affect the progression of liver disease in a sex-specific manner, creating potential opportunities for novel diagnostic and therapeutic approaches to be evaluated in clinical trials. Finally, we identify and propose areas for future basic, translational and clinical research that will advance our understanding of sex disparities in hepatic immunity and liver disease.

Genetic variants associated with immune-mediated liver injury from checkpoint inhibitors

BACKGROUND

The clinical features, liver histology, and genetic variants in 57 patients with moderate to severe immune-mediated liver injury from checkpoint inhibitors (ILICI) are presented.

METHODS

Between 2010 and 2022, 57 high-causality ILICI cases were enrolled in the Drug-Induced Liver Injury Network. HLA and selected candidate gene variants were tested for association with ILICI risk compared to the general population and other DILI controls.

RESULTS

The 57 high-causality cases were attributed to pembrolizumab (16), ipilimumab (15), ipilimumab and nivolumab (13), and other immune checkpoint inhibitors (13) and occurred at a median of 72 days after the first infusion. Median age was 57.8 years, 66% male, and 89% were non-Hispanic Whites. At DILI onset, 53% had hepatocellular, 35% mixed, and 15% cholestatic, with younger patients more likely to have hepatocellular injury. The incidence of ANA, smooth muscle antibody, and elevated IgG levels was low (17%, 23%, and 0%), but corticosteroids were given to 86%. Microgranulomas and hepatic steatosis were seen in 54% and 46% of the 26 liver biopsies, respectively. The HLA alleles associated with autoimmune hepatitis were not over-represented, but 2 host immune response genes (EDIL3 and SAMA5A) and 3 other genes (GABRP, SMAD3, and SLCO1B1) were associated with ILICI (OR: 2.08-2.4, p<0.01).

CONCLUSIONS

ILICI typically arises within 12 weeks of initiating immunotherapy and is self-limited in most cases. Genetic variants involved in host T-cell regulation and drug disposition were identified, implicating these pathways in the pathogenesis of ILICI. If validated, these findings could lead to improved diagnostic instruments and possible treatments for ILICI.

ERAP-1 and ERAP-2 Variants in Liver Injury After COVID-19 mRNA Vaccination: A US Multicenter Study

INTRODUCTION

The aim of this study is to describe the presenting features, genetic factors, and outcomes of 23 adults who developed liver injury after coronavirus disease 2019 (COVID-19) mRNA vaccination.

METHODS

Patients with suspected COVID-19 vaccine hepatitis were enrolled into the Drug-Induced Liver Injury Network. Causality was assessed using the Drug-Induced Liver Injury Network expert opinion score. High-resolution HLA sequencing was undertaken using Illumina platform.

RESULTS

Amongst the 16 high causality cases, median time to onset was 16 days, median age was 63 years, and 75% were female. The injury was hepatocellular in 75% with a median alanine aminotransferase of 497 U/L, and 37% had jaundice. An antinuclear antibody and smooth muscle antibody were detectable in 27% and 36%, but only 12% had an elevated immunoglobulin G level. During follow-up, 37% received a short course of corticosteroids, and 88% fully recovered by 6 months with no deaths observed. HLA alleles associated with autoimmune hepatitis were not overrepresented compared with controls, but an ERAP-2 variant (rs1263907) and the ERAP-1 Hap6 haplotype were significantly overrepresented in the high causality cases vs controls ( P = 0.026 and 5 × 10 -5 , respectively).

DISCUSSION

Acute liver injury may arise within 8 weeks of COVID-19 mRNA vaccination that is generally mild and self-limited in most patients. The absence of an association with the AIH HLA alleles combined with the significant ERAP-2 and ERAP-1 Hap6 haplotype associations implicates a unique but very rare host immune response to vaccine-derived antigens in the pathogenesis of COVID-19 vaccine hepatotoxicity.

Drug hypersensitivity reactions: review of the state of the science for prediction and diagnosis

Drug hypersensitivity reactions (DHRs) are a type of adverse drug reaction that can occur with different classes of drugs and affect multiple organ systems and patient populations. DHRs can be classified as allergic or non-allergic based on the cellular mechanisms involved. Whereas nonallergic reactions rely mainly on the innate immune system, allergic reactions involve the generation of an adaptive immune response. Consequently, drug allergies are DHRs for which an immunological mechanism, with antibody and/or T cell, is demonstrated. Despite decades of research, methods to predict the potential for a new chemical entity to cause DHRs or to correctly attribute DHRs to a specific mechanism and a specific molecule are not well-established. This review will focus on allergic reactions induced by systemically administered low-molecular weight drugs with an emphasis on drug- and patient-specific factors that could influence the development of DHRs. Strategies for predicting and diagnosing DHRs, including potential tools based on the current state of the science, will also be discussed.

Drug-induced liver injury (DILI) ascribed to non-steroidal anti-inflammatory drugs (NSAIDs) in the USA-Update with genetic correlations

OBJECTIVE

To describe patients with NSAID-DILI, including genetic factors associated with idiosyncratic DILI.

METHODS

In DILIN, subjects with presumed DILI are enrolled and followed for at least 6 months. Causality is adjudicated by a Delphic approach. HLA sequencing of multiethnic NSAID-DILI patients and HLA allele imputation of matching population controls were performed following overall, class and drug-based association analysis. Significant results were tested in a non-Hispanic White (NHW) case-control replication cohort.

RESULTS

Between September 2004 and March 2022, causality was adjudicated in 2498, and 55 (41 [75%] women) were assessed as likely due to NSAIDs. Median age at onset was 55 y (range 22-83 y). Diclofenac was the causative drug in 29, celecoxib in 7, ibuprofen in 5, etodolac and meloxicam each in 4. Except for meloxicam and oxaprozin (n = 2), the liver injury was hepatocellular with median R 15-25. HLA-DRB1*04:03 and HLA-B*35:03 were significantly more frequent in NSAID-DILI patients than in non-NSAID DILI controls. Interestingly, 85% of the HLA-DRB1*04:03 carriers developed DILI due to the use of acetic acid derivative NSAIDs, supporting the hypothesis that HLA-DRB1*04:03 could be a drug and/or class risk factor. HLA-B*35:03 but not HLA-DRB1*04:03 association was confirmed in the independent NHW replication cohort, which was largely driven by diclofenac.

CONCLUSIONS

Despite prevalent use, NSAID-DILI is infrequent in the United States. Diclofenac is the most commonly implicated, and adherence to warnings of risk and close observation are recommended. The increased frequency of HLA-B*35:03 and DRB1*04:03, driven by diclofenac, suggests the importance of immune-mediated responses.

Susceptibility to Hepatotoxic Drug-Induced Liver Injury Increased After Traumatic Brain Injury in Mice

The early stages of brain injury can induce acute liver injury, which can be recovered in the short term. Continued medication treatment during hospitalization for brain injury alleviates the prognosis and contributes to a high incidence of drug-induced liver injury (DILI). We hypothesize that there is an interaction between changes in the hepatic environment after brain injury and liver injury produced by intensive drug administration, leading to an upregulation of the organism's sensitivity to DILI. In this study, mice models of TBI were established by controlled cortical impact (CCI) and models of DILI were constructed by acetaminophen (APAP). All mice were divided into four groups: Sham, TBI, APAP, and TBI+APAP, and related liver injury indicators in liver and serum were detected by Western blot, Quantitative real-time PCR (qRT-PCR), and immunohistochemical staining. The results suggested that liver injury induced in the early stages of brain injury recovered in 3 days, but this state could still significantly aggravate DILI, represented by higher liver enzymes (aspartate aminotransferase [AST] and alanine aminotransferase [ALT]), oxidative stress (increase in malondialdehyde [MDA] concentration and deregulation of glutathione [GSH] and superoxide dismutase [SOD] activities), inflammatory response (activation of the HMGB1/TLR4/NF-κB signaling pathway, and increased messenger RNA [mRNA] and protein levels of pro-inflammatory cytokines including tumor necrosis factor alpha [TNF-α], interleukin [IL]-6, and IL-1β), and apoptosis (TUNEL assay, upregulation of Bax protein and deregulation of Bcl-2 protein). In summary, our results suggested that TBI is a potential susceptibility factor for DILI and exacerbates DILI.

Diagnosis and management of immune mediated liver injury from checkpoint inhibitors

PURPOSE OF REVIEW

The aim is to summarize the latest data on the incidence, clinical manifestations, and management of immune- mediated liver injury from checkpoint inhibitors (ILICI).

RECENT FINDINGS

ILICI develops in 10-15% of oncology patients receiving immunotherapy with most having asymptomatic serum aminotransferase and/or alkaline phosphatase elevations. Most grade 1-2 ILICI patients improve with drug discontinuation and/or short-term oral corticosteroids. In contrast, the 2-3% with grade 3/4 hepatotoxicity frequently require oral or intravenous corticosteroids and some are hospitalized to initiate further immunosuppression with mycophenolate mofetil or azathioprine. Liver biopsy is generally reserved for patients with atypical features or those with severe hepatotoxicity who fail to respond to treatment. Up to 3% of ILICI patients with a cholestatic profile have MRI evidence of intra or extrahepatic cholangitis that responds poorly to immunosuppression. Most ILICI patients improve during follow-up and liver-related death is very uncommon (<1%). Up to 30% of rechallenged ILICI patients develop recurrent hepatotoxicity with a shorter latency.

SUMMARY

ILICI is increasingly encountered by gastroenterologists evaluating oncology patients with abnormal liver biochemistries. A stepwise approach to exclude viral hepatitis, alcohol, hepatic metastases, and pancreaticobiliary disease is recommended. The majority of ILICI patients fully recover with ICI discontinuation and short-term corticosteroids or a second line immunosuppressant.

Hepatotoxicity of Antibiotics and Antifungals and Their Safe Use in Hepatic Impairment

Idiosyncratic drug-induced liver injury (DILI) is a rare and unpredictable form of hepatotoxicity. While its clinical course is usually benign, cases leading to liver transplantation or death can occur. Based on modern prospective registries, antimicrobials including antibiotics and antifungals are frequently implicated as common causes. Amoxicillin-clavulanate ranks as the most common cause for DILI in the Western World. Although the absolute risk of hepatotoxicity of these agents is low, as their usage is quite high, it is not uncommon for practitioners to encounter liver injury following the initiation of antibiotic or antifungal therapy. In this review article, mechanisms of hepatoxicity are presented. The adverse hepatic effects of well-established antibiotic and antifungal agents are described, including their frequency, severity, and pattern of injury and their HLA risks. We also review the drug labeling and prescription guidance from regulatory bodies, with a focus on individuals with hepatic impairment.

Chinese guideline for the diagnosis and treatment of drug-induced liver injury: an update

Drug-induced liver injury (DILI) is an important adverse drug reaction that can lead to acute liver failure or even death in severe cases. Currently, the diagnosis of DILI still follows the strategy of exclusion. Therefore, a detailed history taking and a thorough and careful exclusion of other potential causes of liver injury is the key to correct diagnosis. This guideline was developed based on evidence-based medicine provided by the latest research advances and aims to provide professional guidance to clinicians on how to identify suspected DILI timely and standardize the diagnosis and management in clinical practice. Based on the clinical settings in China, the guideline also specifically focused on DILI in chronic liver disease, drug-induced viral hepatitis reactivation, common causing agents of DILI (herbal and dietary supplements, anti-tuberculosis drugs, and antineoplastic drugs), and signal of DILI in clinical trials and its assessment.

Dietary Supplement-Induced Hepatotoxicity: A Clinical Perspective

The consumption of dietary supplements (DS) has resulted in a significant and escalating number of cases involving liver injury. It is crucial for clinicians and consumers to be well informed about the adverse effects of such products, leading to their discontinuation and timely reporting of any harmful cases. This article delves into the clinical perspective of DS-related hepatotoxicity, highlighting key concepts such as a systematic diagnostic approach. The discussion extends to notable examples of both currently popular and potential future dietary supplements, such as garcinia cambogia, turmeric, and ashwagandha, accompanied by an overview of recent findings. Causality assessment tools play a crucial role in establishing a connection between these products and instances of liver injury, with consideration of the advantages and disadvantages associated with their use. Fostering a comprehensive understanding of regulatory standards, coupled with a solid foundation of knowledge of DS, will prove instrumental in preventing DS-related hepatotoxicity. Achieving this goal requires collaborative efforts from both consumers and clinicians.

Genetic Variations and Antibiotic-Related Adverse Events

Antibiotic-related adverse events are common in both adults and children, and knowledge of the factors that favor the development of antibiotic-related adverse events is essential to limit their occurrence and severity. Genetics can condition the development of antibiotic-related adverse events, and the screening of patients with supposed or demonstrated specific genetic mutations may reduce drug-related adverse events. This narrative review discusses which genetic variations may influence the risk of antibiotic-related adverse events and which conclusions can be applied to clinical practice. An analysis of the literature showed that defined associations between genetic variations and specific adverse events are very few and that, at the moment, none of them have led to the implementation of a systematic screening process for patients that must be treated with a given antibiotic in order to select those at risk of specific adverse events. On the other hand, in most of the cases, more than one variation is implicated in the determination of adverse events, and this can be a limitation in planning a systematic screening. Moreover, presently, the methods used to establish whether a patient carries a "dangerous" genetic mutation require too much time and waiting for the result of the test can be deleterious for those patients urgently requiring therapy. Further studies are needed to definitively confirm which genetic variations are responsible for an increased risk of a well-defined adverse event.

Recent advances in the diagnosis of drug-induced liver injury

Drug-induced liver injury (DILI) is a major problem in the United States, commonly leading to hospital admission. Diagnosing DILI is difficult as it is a diagnosis of exclusion requiring a temporal relationship between drug exposure and liver injury and a thorough work up for other causes. In addition, DILI has a very variable clinical and histologic presentation that can mimic many different etiologies of liver disease. Objective scoring systems can assess the probability that a drug caused the liver injury but liver biopsy findings are not part of the criteria used in these systems. This review will address some of the recent updates to the scoring systems and the role of liver biopsy in the diagnosis of DILI.

Roadmap to DILI research in Europe. A proposal from COST action ProEuroDILINet

In the current article the aims for a constructive way forward in Drug-Induced Liver Injury (DILI) are to highlight the most important priorities in research and clinical science, therefore supporting a more informed, focused, and better funded future for European DILI research. This Roadmap aims to identify key challenges, define a shared vision across all stakeholders for the opportunities to overcome these challenges and propose a high-quality research program to achieve progress on the prediction, prevention, diagnosis and management of this condition and impact on healthcare practice in the field of DILI. This will involve 1. Creation of a database encompassing optimised case report form for prospectively identified DILI cases with well-characterised controls with competing diagnoses, biological samples, and imaging data; 2. Establishing of preclinical models to improve the assessment and prediction of hepatotoxicity in humans to guide future drug safety testing; 3. Emphasis on implementation science and 4. Enhanced collaboration between drug-developers, clinicians and regulatory scientists. This proposed operational framework will advance DILI research and may bring together basic, applied, translational and clinical research in DILI.

The expanding role of HLA gene tests for predicting drug side effects

Adverse drug reactions can be either dose-dependent (Type A) or idiosyncratic (Type B). Type B adverse drug reactions tend to be extremely rare and difficult to predict. They are usually immune-mediated. Examples include severe skin reactions and drug-induced liver injury. For many commonly prescribed drugs (such as antibiotics), the risk of developing an idiosyncratic adverse drug reaction is influenced by variability in the human leukocyte antigen (HLA) genes. Because these HLA-mediated adverse drug reactions can be lethal, there is growing interest in defining which specific drug-gene relationships might benefit from pre-emptive HLA genotyping and automated clinical decision support. This review summarizes the literature for HLA-mediated adverse reactions linked to common drugs.

HLA-B*53:01 Is a Significant Risk Factor of Liver Injury due to Phenytoin and Other Antiepileptic Drugs in African Americans

INTRODUCTION

To investigate human leukocyte antigen alleles associated with liver injury due to antiepileptic drugs (AEDs) in African Americans (AA).

METHODS

In this study, 21 AA with AED drug-induced liver injury (DILI), 176 AA with DILI due to non-AEDs, and 5816 AA population controls were included.

RESULTS

HLA-B*53:01 was significantly associated with aromatic AED-DILI (odds ratio: 4.52, 95% confidence interval: 2.42-8.44, P = 1.46 × 10 -5 ). Phenytoin DILI showed the strongest association with HLA-B*53:01 (odds ratio: 9.17; 95% confidence interval: 3.61-23.28, P = 1.1 × 10 -5 ). The HLA-B*53:01 allele was carried by 8 of 9 AA phenytoin DILI cases.

DISCUSSION

HLA-B*53:01 is a significant risk factor of liver injury due to antiepileptics, particularly phenytoin, in AA.

Development and validation of a novel model to predict liver-related mortality in patients with idiosyncratic drug-induced liver injury

BACKGROUND

Early identification of patients with high mortality risk is critical for optimizing the clinical management of drug-induced liver injury (DILI). We aimed to develop and validate a new prognostic model to predict death within 6 months in DILI patients.

METHODS

This multicenter study retrospectively reviewed the medical records of DILI patients admitted to three hospitals. A DILI mortality predictive score was developed using multivariate logistic regression and was validated with area under the receiver operating characteristic curve (AUC). A high-mortality-risk subgroup was identified according to the score.

RESULTS

Three independent DILI cohorts, including one derivation cohort (n = 741) and two validation cohorts (n = 650, n = 617) were recruited. The DILI mortality predictive (DMP) score was calculated using parameters at disease onset as follows: 1.913 × international normalized ratio + 0.060 × total bilirubin (mg/dL) + 0.439 × aspartate aminotransferase/alanine aminotransferase - 1.579 × albumin (g/dL) - 0.006 × platelet count (109/L) + 9.662. The predictive performance for 6-month mortality of DMP score was desirable, with an AUC of 0.941 (95% CI: 0.922-0.957), 0.931 (0.908-0.949) and 0.960 (0.942-0.974) in the derivation, validation cohorts 1 and 2, respectively. DILI patients with a DMP score ≥ 8.5 were stratified into high-risk group, whose mortality rates were 23-, 36-, and 45-fold higher than those of other patients in the three cohorts.

CONCLUSIONS

The novel model based on common laboratory findings can accurately predict mortality within 6 months in DILI patients, which should serve as an effective guidance for management of DILI in clinical practice.

Review of human risk factors for idiosyncratic drug-induced liver injury: latest advances and future goals

INTRODUCTION

Idiosyncratic drug-induced liver injury (DILI) is a common cause of acute liver injury and can lead to death from acute liver failure or require liver transplantation. Although the total burden of liver injury is high, the frequency of DILI caused by specific agents is often low. As the liver injury is by per definition idiosyncratic, the prediction of which patients will develop liver injury from specific drugs is currently a very difficult challenge.

AREAS COVERED

The current paper highlights the most important studies on prediction of DILI published in 2019-2023, including studies on genetic, metabolomic, and demographic risk factors, concomitant medication, and the role of comorbid liver diseases. Risk stratification using demographic, metabolomic, and multigenetic risk factors is discussed.

EXPERT OPINION

Great advances have been made in identifying genetic risk factors for DILI. Combining these risk factors with demographic information and other biomarkers into multigenetic risk models might become highly useful in risk stratifying patients exposed to DILI. However, a more detailed mapping of genetic risk factors is needed. Results of these studies need to be validated in the selected ethnic groups before applicability and cost-effectiveness can be determined.

Higher urinary glyphosate exposure is associated with increased risk of liver dysfunction in adults: An analysis of NHANES, 2013-2016

Glyphosate (GLY) exposure, both exogenous and endogenous, is a global concern. Multiple studies of model systems in vitro and in vivo have demonstrated the potential toxic effects of GLY exposure on human organs, particularly the liver and renal system. However, there is currently limited epidemiological evidence establishing a link between GLY exposure and hepatorenal function in the general population. In this study, a multivariable linear regression model and forest plots were employed to evaluate the connection between urinary GLY and biomarkers of hepatorenal function in 2241 participants from the National Health and Nutrition Examination Survey 2013-2016. Additionally, subgroup analyses were conducted based on age, gender, race, BMI, and chronic kidney disease (CKD). Alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), AST/ALT and fibrosis 4 score (FIB-4) all increased with elevated urinary GLY concentrations after adjusting for potential confounders, while albumin (ALB) exhibited the opposite trend, particularly among younger, female, non-Hispanic white, overweight, and CKD participants. Furthermore, individuals in the third tertile had a greater risk of liver dysfunction than those in the first tertile after categorizing urinary GLY concentrations. However, our study showed no proof that GLY exposure affects the ratio of urine albumin to creatinine (ACR) or serum creatinine levels. Overall, these results imply that GLY exposure may have adverse effects on human liver function.

Drug-Induced Liver Injury with Commonly Used Antibiotics in the All of Us Research Program

Antibiotics are a known cause of idiosyncratic drug-induced liver injury (DILI). According to the Centers for Disease Control and Prevention, the five most commonly prescribed antibiotics in the United States are azithromycin, ciprofloxacin, cephalexin, amoxicillin, and amoxicillin-clavulanate. We quantified the frequency of acute DILI for these common antibiotics in the All of Us Research Program, one of the largest electronic health record (EHR)-linked research cohorts in the United States. Retrospective analyses were conducted applying a standardized phenotyping algorithm to de-identified clinical data available in the All of Us database for 318,598 study participants. Between February 1984 and December 2022, more than 30% of All of Us participants (n = 119,812 individuals) had been exposed to at least 1 of our 5 study drugs. Initial screening identified 591 potential case patients that met our preselected laboratory-based phenotyping criteria. Because DILI is a diagnosis of exclusion, we then used phenome scanning to narrow the case counts by (i) scanning all EHRs to identify all alternative diagnostic explanations for the laboratory abnormalities, and (ii) leveraging International Classification of Disease 9th revision (ICD)-9 and ICD 10th revision (ICD)-10 codes as exclusion criteria to eliminate misclassification. Our final case counts were 30 DILI cases with amoxicillin-clavulanate, 24 cases with azithromycin, 24 cases with ciprofloxacin, 22 cases with amoxicillin alone, and < 20 cases with cephalexin. These findings demonstrate that data from EHR-linked research cohorts can be efficiently mined to identify DILI cases related to the use of common antibiotics.

The Evolving Profile of Idiosyncratic Drug-Induced Liver Injury

Idiosyncratic drug-induced liver injury (DILI) is an infrequent but important cause of liver disease. Newly identified causes of DILI include the COVID vaccines, turmeric, green tea extract, and immune checkpoint inhibitors. DILI is largely a clinical diagnosis of exclusion that requires evaluation for more common causes of liver injury and a compatible temporal association with the suspect drug. Recent progress in DILI causality assessment includes the development of the semi-automated revised electronic causality assessment method (RECAM) instrument. In addition, several drug-specific HLA associations have been identified that can help with the confirmation or exclusion of DILI in individual patients. Various prognostic models can help identify the 5%-10% of patients at highest risk of death. Following suspect drug cessation, 80% of patients with DILI fully recover, whereas 10%-15% have persistently abnormal laboratory studies at 6 months of follow-up. Hospitalized patients with DILI with an elevated international normalized ratio or mental status changes should be considered for N-acetylcysteine therapy and urgent liver transplant evaluation. Selected patients with moderate to severe drug reaction with eosinophilia and systemic symptoms or autoimmune features on liver biopsy may benefit from short-term corticosteroids. However, prospective studies are needed to determine the optimal patients and dose and duration of steroids to use. LiverTox is a comprehensive, freely accessible Web site with important information regarding the hepatotoxicity profile of more than 1000 approved medications and 60 herbal and dietary supplement products. It is hoped that ongoing "omics" studies will lead to additional insight into DILI pathogenesis, improved diagnostic and prognostic biomarkers, and mechanism-based treatments.

Liver injury from direct oral anticoagulants

BACKGROUND

Drug-induced liver injury (DILI) can be caused by any prescribed drug and is a significant reason for the withdrawal of newly launched drugs. Direct-acting oral anticoagulants (DOACs) are non-vitamin K-based antagonists recently introduced and increasingly used for various clinical conditions. A meta-analysis of 29 randomised controlled trials and 152116 patients reported no increased risk of DILI with DOACs. However, it is challenging to predict the risk factors for DILI in individual patients with exclusion of patients with pre-existing liver disease from these studies.

AIM

To determine the risk factors and outcomes of patients who developed DILI secondary to DOACs by systematic review and meta-summary of recent case reports and series.

METHODS

A systematic search was conducted on multiple databases including PubMed, Science Direct, Reference Citation Analysis, and Google Scholar. The search terms included "Acute Liver Failure" OR "Acute-On-Chronic Liver Failure" OR "Acute Chemical and Drug Induced Liver Injury" OR "Chronic Chemical and Drug Induced Liver Injury" AND "Factor Xa Inhibitors" OR "Dabigatran" OR "Rivaroxaban" OR "apixaban" OR "betrixaban" OR "edoxaban" OR "Otamixaban". The results were filtered for literature published in English and on adult patients. Only case reports and case studies reporting cases of DILI secondary to DOACs were included. Data on demographics, comorbidities, medication history, laboratory investigations, imaging, histology, management, and outcomes were extracted.

RESULTS

A total of 15 studies (13 case reports and 2 case series) were included in the analysis, comprising 27 patients who developed DILI secondary to DOACs. Rivaroxaban was the most commonly implicated DOAC (n = 20, 74.1%). The mean time to onset of DILI was 40.6 d. The most common symptoms were jaundice (n = 15, 55.6%), malaise (n = 9, 33.3%), and vomiting (n = 9, 33.3%). Laboratory investigations showed elevated liver enzymes and bilirubin levels. Imaging studies and liver biopsies revealed features of acute hepatitis and cholestatic injury. Most patients had a favourable outcome, and only 1 patient (3.7%) died due to liver failure.

CONCLUSION

DOACs are increasingly used for various clinical conditions, and DILI secondary to DOACs is a rare but potentially serious complication. Prompt identification and cessation of the offending drug are crucial for the management of DILI. Most patients with DILI secondary to DOACs have a favourable outcome, but a small proportion may progress to liver failure and death. Further research, including post-marketing population-based studies, is needed to better understand the incidence and risk factors for DILI secondary to DOACs.

New Insights into Herb-Induced Liver Injury

Significance: Herbs are widely used worldwide. However, inappropriate use of some of the herbs can lead to herb-induced liver injury (HILI). Intriguingly, HILI incidents are on the rise, and our understanding of the underlying etiologies is in progress, and hence, an update on the current status of incidents as well as our understanding on the etiologies of HILI is appropriate. Recent Advances: HILI reports due to the use of some herbs that are traditionally considered to be safe are also on the rise. Furthermore, HILI due to the use of certain herbs in combination with other herbs (herb-herb interaction [HHI]) or non-herb components (herb-drug interaction [HDI]) has also been reported, suggesting a potentially important new type of inappropriate use of herbs. Critical Issues: Updated overviews focus on the epidemiology, etiology, phenotypes, and risk factors of HILI, as well as HDI and HHI, and analysis on several types of newly reported "toxic" effects of herbs based on types of hepatotoxicity and the HILI mechanisms. Future Directions: HILI will continue to be a significant public health challenge in the near future. In the light of the lack of broadly available guidelines and regulations for proper and safe uses of herbs worldwide, raising the public awareness of HILI will remain one of the most effective measures. In particular, it should include a better understanding of the contributing factors; a more detail subclassification and description of HILI, better characterization of the components/substances that could induce HILI; and development of HILI diagnosis based on the Roussel Uclaf Causality Assessment Method (RUCAM). Antioxid. Redox Signal. 38, 1138-1149.

Genetic alterations and molecular mechanisms underlying hereditary intrahepatic cholestasis

Hereditary cholestatic liver disease caused by a class of autosomal gene mutations results in jaundice, which involves the abnormality of the synthesis, secretion, and other disorders of bile acids metabolism. Due to the existence of a variety of gene mutations, the clinical manifestations of children are also diverse. There is no unified standard for diagnosis and single detection method, which seriously hinders the development of clinical treatment. Therefore, the mutated genes of hereditary intrahepatic cholestasis were systematically described in this review.

Microphysiological Models for Mechanistic-Based Prediction of Idiosyncratic DILI

Drug-induced liver injury (DILI) is a major contributor to high attrition rates among candidate and market drugs and a key regulatory, industry, and global health concern. While acute and dose-dependent DILI, namely, intrinsic DILI, is predictable and often reproducible in preclinical models, the nature of idiosyncratic DILI (iDILI) limits its mechanistic understanding due to the complex disease pathogenesis, and recapitulation using in vitro and in vivo models is extremely challenging. However, hepatic inflammation is a key feature of iDILI primarily orchestrated by the innate and adaptive immune system. This review summarizes the in vitro co-culture models that exploit the role of the immune system to investigate iDILI. Particularly, this review focuses on advancements in human-based 3D multicellular models attempting to supplement in vivo models that often lack predictability and display interspecies variations. Exploiting the immune-mediated mechanisms of iDILI, the inclusion of non-parenchymal cells in these hepatoxicity models, namely, Kupffer cells, stellate cells, dendritic cells, and liver sinusoidal endothelial cells, introduces heterotypic cell-cell interactions and mimics the hepatic microenvironment. Additionally, drugs recalled from the market in the US between 1996-2010 that were studies in these various models highlight the necessity for further harmonization and comparison of model characteristics. Challenges regarding disease-related endpoints, mimicking 3D architecture with different cell-cell contact, cell source, and the underlying multi-cellular and multi-stage mechanisms are described. It is our belief that progressing our understanding of the underlying pathogenesis of iDILI will provide mechanistic clues and a method for drug safety screening to better predict liver injury in clinical trials and post-marketing.

Mapping the incidence of drug-induced liver injury: A systematic review and meta-analysis

OBJECTIVES

Drug-induced liver injury (DILI) is an increasing etiology of liver dysfunction, with various incidence worldwide. To better understand the disease burden and establish appropriate preventive and treatment strategies, a systematic review and meta-analysis was conducted.

METHODS

PubMed, EMBASE, Web of Science, and Cochrane Library were searched for studies on the incidence of DILI published up to June 1, 2022. According to the predefined criteria, only population-based studies were included. Incidence was presented as cases per 100 000 person-years with 95% confidence interval (CI) using a random-effects model.

RESULTS

A total of 14 studies were included. The overall incidence of DILI was 4.94 per 100 000 person-years (95% CI 4.05-5.83). Time-based cumulative meta-analysis suggested that the incidence of DILI increased over time since 2010. The incidence varied by regions, with Asia having the highest incidence of 17.82 per 100 000 person-years (95% CI 6.26-29.38), while North America having the lowest incidence of 1.72 per 100 000 person-years (95% CI 0.48-2.95). All studies reported a higher incidence of DILI in the elderly but comparable incidences between male and female (3.42 per 100 000 person-years vs 4.64 per 100 000 person-years).

CONCLUSIONS

The global incidence of DILI has been increasing since 2010, with the highest incidence in Asia. Understanding the epidemiological characteristics of DILI helps establish specific strategies to deal with this emerging health problems.

Genome-wide Association Study of Methotrexate-Induced Liver Injury in Rheumatoid Arthritis Patients

Hepatotoxicity is a serious adverse drug reaction related to methotrexate (MTX). However, the cause of drug-induced liver injury (DILI) is still unclear and unpredictable. Genetic risk factors may predispose for MTX-DILI. Therefore, we conducted a nested case-control genome-wide association study to explore genetic risk factors associated with MTX-DILI. Seven international groups contributed blood samples and data of patients with rheumatoid arthritis who used MTX. MTX-DILI was defined as an alanine aminotransferase (ALT) level of at least three times the upper limit of normal (ULN), to increase contrast controls ALT levels did not raise above two times the ULN. Per study site, control subjects and patients with MTX-DILI (ratio 3:1) were matched for age, gender, and duration of MTX use. Patients were genotyped using Illumina GSA MD-24v1-0 and data were imputed using the 1000 Genomes reference panel. Single-nucleotide polymorphisms (SNPs) were analyzed using an additive genetic model, corrected for sex, country, and age. A P-value of ≤ 5 × 10^-8 was considered significant, whereas a  P-value of ≤ 5 × 10^-6 was considered suggestive. A total of 108 MTX-DILI cases and 311 controls were included for association analysis. None of the SNPs were significantly associated with MTX-DILI. However, we found seven suggestive genetic variants associated with MTX-DILI (P-values 7.43 × 10^-8 to 4.86 × 10^-6 ). Of those, five SNPs were in the intronic protein-coding regions of FTCDNL1, BCOR, FGF14, RBMS3, and PFDN4/DOK5. Investigation of candidates SPATA9 (rs72783407), PLCG2 (rs60427389), RAVER2 (rs72675408), JAK1 (rs72675451), PTPN2 (rs2476601), MTHFR C677T (rs1801133), and into the HLA region did not show significant findings. No genetic variants associated with MTX-DILI were found, whereas suggestive SNPs need further investigation.

Identification of Reduced ERAP2 Expression and a Novel HLA Allele as Components of a Risk Score for Susceptibility to Liver Injury Due to Amoxicillin-Clavulanate

BACKGROUND & AIMS

Drug-induced liver injury (DILI) due to amoxicillin-clavulanate (AC) has been associated with HLA-A∗02:01, HLA-DRB1∗15:01, and rs2476601, a missense variant in PTPN22. The aim of this study was to identify novel risk factors for AC-DILI and to construct a genetic risk score (GRS).

METHODS

Transcriptome-wide association study and genome-wide association study analyses were performed on 444 AC-DILI cases and 10,397 population-based controls of European descent. Associations were confirmed in a validation cohort (n = 133 cases and 17,836 population-based controls). Discovery and validation AC-DILI cases were also compared with 1358 and 403 non-AC-DILI cases.

RESULTS

Transcriptome-wide association study revealed a significant association of AC-DILI risk with reduced liver expression of ERAP2 (P = 3.7 × 10-7), coding for an aminopeptidase involved in antigen presentation. The lead eQTL single nucleotide polymorphism, rs1363907 (G), was associated with AC-DILI risk in the discovery (odds ratio [OR], 1.68; 95% CI, 1.23-1.66; P = 1.7 × 10-7) and validation cohorts (OR, 1.2; 95% CI, 1.04-2.05; P = .03), following a recessive model. We also identified HLA-B∗15:18 as a novel AC-DILI risk factor in both discovery (OR, 4.19; 95% CI, 2.09-8.36; P = 4.9 × 10-5) and validation (OR, 7.78; 95% CI, 2.75-21.99; P = .0001) cohorts. GRS, incorporating rs1363907, rs2476601, HLA-B∗15:18, HLA-A∗02:01, and HLA-DRB1∗15:01, was highly predictive of AC-DILI risk when cases were analyzed against both general population and non-AC-DILI control cohorts. GRS was the most significant predictor in a regression model containing known AC-DILI clinical risk characteristics and significantly improved the predictive model.

CONCLUSIONS

We identified novel associations of AC-DILI risk with ERAP2 low expression and with HLA-B∗15:18. GRS based on the 5 risk variants may assist AC-DILI causality assessment and risk management.

Relevance of Pharmacogenomics to the Safe Use of Antimicrobials

There has been widespread implementation of pharmacogenomic testing to inform drug prescribing in medical specialties such as oncology and cardiology. Progress in using pharmacogenomic tests when prescribing antimicrobials has been more limited, though a relatively large number of pharmacogenomic studies on aspects such as idiosyncratic adverse drug reactions have now been performed for this drug class. Currently, there are recommendations in place from either National Regulatory Agencies and/or specialist Pharmacogenomics Advisory Groups concerning genotyping for specific variants in MT-RNR1 and CYP2C19 before prescribing aminoglycosides and voriconazole, respectively. Numerous additional pharmacogenomic associations have been reported concerning antimicrobial-related idiosyncratic adverse drug reactions, particularly involving specific HLA alleles, but, to date, the cost-effectiveness of genotyping prior to prescription has not been confirmed. Polygenic risk score determination has been investigated to a more limited extent but currently suffers from important limitations. Despite limited progress to date, the future widespread adoption of preemptive genotyping and genome sequencing may provide pharmacogenomic data to prescribers that can be used to inform prescribing and increase the safe use of antimicrobials.

Clinical features, outcomes, and HLA risk factors associated with nitrofurantoin-induced liver injury

BACKGROUND & AIMS

Nitrofurantoin (NTF) is widely used for the treatment (short-term) and prevention (long-term) of urinary tract infections. We aimed to describe the clinical characteristics, outcomes, and HLA risk factors for NTF-induced liver injury (NTF-DILI) among individuals enrolled in the Drug Induced Liver Injury Network (DILIN).

METHODS

Seventy-eight individuals with definite, highly likely, or probable NTF-DILI were enrolled into DILIN studies between 2004-2020. HLA alleles were compared between NTF-DILI and three control groups: population (n = 14,001), idiopathic autoimmune hepatitis (n = 231), and non-NTF DILI (n = 661).

RESULTS

Liver injury was hepatocellular in 69% and icteric in 55%. AST > ALT was more common in the 44 long-exposure (≥1 year) NTF-DILI cases than in the 18 short (≤7 days) and 16 intermediate (>7 to <365 days) exposure cases (73% vs. 33% vs. 50%, respectively, p = 0.018), as was ANA or SMA positivity (91% vs. 44% vs. 50%, respectively, p <0.001), and corticosteroid use (61% vs. 27% vs. 44%, respectively, p = 0.06). In long-term NTF-DILI, bridging fibrosis, nodularity or cirrhosis, or clinical and imaging evidence for cirrhosis were present in 38%, with massive or sub-massive necrosis in 20%. No one in the short-term exposure group died or underwent transplantation, whereas 7 (12%) patients from the other groups died or underwent transplantation. After covariate adjustments, HLA-DRB1∗11:04 was significantly more frequent in NTF-DILI compared to population controls (odds ratio [OR] 4.29, p = 1.15 × 10-4), idiopathic autoimmune hepatitis (OR 11.77, p = 7.76 × 10-5), and non-NTF DILI (OR 3.34, p = 0.003).

CONCLUSION

NTF-DILI can result in parenchymal necrosis, bridging fibrosis, cirrhosis, and death or liver transplantation, especially with long-term exposure, and is associated with HLA-DRB1∗11:04. To mitigate against serious liver injury associated with NTF, regulators should revise the prescribing information and consider other mitigation strategies.

IMPACT AND IMPLICATIONS

Nitrofurantoin is a recognized cause of drug-induced liver injury (DILI). In this study consisting of a large cohort of well-phenotyped individuals with nitrofurantoin-induced liver injury, two distinct patterns of liver injury were identified: liver injury associated with short-term exposure, which is generally self-limiting, and liver injury associated with long-term exposure, which can lead to advanced fibrosis, cirrhosis and liver failure. HLA DRB1∗11:04 is a risk factor for liver injury due to long-term nitrofurantoin exposure. Our findings are important for regulators as well as physicians prescribing and pharmacists dispensing nitrofurantoin.

Review article: clinical assessment of suspected drug-induced liver injury and its management

BACKGROUND

Idisyncratic drug-induced liver injury (DILI) is a rare instance of liver injury after exposure to an otherwise safe drug or herbal or dietary supplement. DILI can be associated with significant morbidity and mortality. Furthermore, it is an important consideration in drug development due to safety concerns.

AIMS AND METHODS

To highlight pearls and pitfalls to aid clinicians in diagnosing DILI and surmising the management options. We also share the best practices from personal insights developed from decades long participation in the causality assessment committee meetings of the DILI Network.

RESULTS

DILI lacks a diagnostic test and is currently diagnosed through a process of exclusion of competing aetiologies of liver injury. This requires a high degree of suspicion to consider the possibility of DILI, skill in ruling out the obvious and less obvious competing liver insults, and an understanding of the expected phenotypes of DILI. The facets of DILI cover multiple aspects, including the latency, liver injury pattern, course of injury, and associated autoimmune or immuno-allergic features. Care for patients with DILI is geared towards stopping the offending drug and symptom management that include the use of corticosteroids in select cases.

CONCLUSION

The diagnosis of DILI is challenging and is primarily made through a carefully crafted patient interview, temporal relationship with the implicated drug or supplement, and exclusion of competing aetiology. LiverTox is a useful resource for clinicians to review the literature and recognise the likelihood of the implicated agent in causing DILI.

Genetics of drug-induced liver injury: Current knowledge and future prospects

Idiosyncratic drug-induced liver injury (DILI) remains an important clinical problem, both during drug development and the prescription of a range of licensed drugs. Although rare, the consequences are serious. Ongoing studies on genetic risk factors for DILI, especially genomewide association studies, have resulted in the identification of a number of genetic risk factors, including particular HLA alleles and a few non-HLA genes, both immune-related and metabolic. Some non-HLA associations, such as N-acetyltransferase 2 in isoniazid DILI and interferon regulatory factor 6 in interferon-beta DILI are likely to be drug-specific due to the role of the associated gene, but there is also evidence for polygenic susceptibility involving pathways such as oxidative and endoplasmic reticulum stress and mitochondrial function for DILI induced by multiple drugs. Increased knowledge of genetic risk factors should assist in better understanding underlying DILI mechanisms and help improve methods for identifying hepatotoxic drugs early in development. HLA allele-specific T cell proliferation together with in silico prediction of drug binding to specific HLA proteins have confirmed genetic findings for certain common causes of DILI. However, studies in hepatocytes exposed to high drug concentrations suggest toxicity that is not dependent on genotype also occurs. It seems likely that susceptibility to DILI involves several genetic risk factors combining with other factors that affect drug levels. Despite recent progress in detecting genetic risk factors for DILI, low positive predictive values mean that general implementation of genotyping prior to prescription of potentially hepatotoxic drugs is not useful currently.

Antibiotics enhancing drug-induced liver injury assessed for causality using Roussel Uclaf Causality Assessment Method: Emerging role of gut microbiota dysbiosis

Drug-induced liver injury (DILI) is a disease that remains difficult to predict and prevent from a clinical perspective, as its occurrence is hard to fully explain by the traditional mechanisms. In recent years, the risk of the DILI for microbiota dysbiosis has been recognized as a multifactorial process. Amoxicillin-clavulanate is the most commonly implicated drug in DILI worldwide with high causality gradings based on the use of RUCAM in different populations. Antibiotics directly affect the structure and diversity of gut microbiota (GM) and changes in metabolites. The depletion of probiotics after antibiotics interference can reduce the efficacy of hepatoprotective agents, also manifesting as liver injury. Follow-up with liver function examination is essential during the administration of drugs that affect intestinal microorganisms and their metabolic activities, such as antibiotics, especially in patients on a high-fat diet. In the meantime, altering the GM to reconstruct the hepatotoxicity of drugs by exhausting harmful bacteria and supplementing with probiotics/prebiotics are potential therapeutic approaches. This review will provide an overview of the current evidence between gut microbiota and DILI events, and discuss the potential mechanisms of gut microbiota-mediated drug interactions. Finally, this review also provides insights into the "double-edged sword" effect of antibiotics treatment against DILI and the potential prevention and therapeutic strategies.

Incidence and risk factors of drug-induced liver injury

The epidemiology and aetiology of drug-induced liver injury (DILI) vary across different countries and populations. Overall, DILI is rare in the general population but has become more prevalent in hospitalized patients, especially among patients with unexplained liver conditions. In addition, drugs implicated in DILI differ between Western and Eastern countries. Antibiotics are the leading drugs implicated in DILI in the West, whereas traditional Chinese medicine is the primary cause implicated in DILI in the East. The incidence of herbal and dietary supplements-induced hepatotoxicity is increasing globally. Several genetic and nongenetic risk factors associated with DILI have been described in the literature; however, there are no confirmed risk factors for all-cause DILI. Some factors may contribute to the risk of DILI in a drug-specific manner.

Genetics are not likely to offer clinically useful predictions for elevated liver enzyme levels in patients using low dose methotrexate

OBJECTIVE

To examine genetic influence on the risk of elevations in liver function tests (AST and ALT) among patients using low-dose methotrexate (LD-MTX).

METHODS

We examined data from the LD-MTX arm of a randomized double-blind placebo-controlled trial conducted among subjects without rheumatic disease. Genome wide association studies (GWAS) were performed in subjects of European ancestry to test the association between single nucleotide polymorphisms (SNPs) and the log transformed maximum values of AST, ALT, and dichotomized outcome with AST or ALT > 2 times upper limit of normal (ULN). The association between variants in MTX metabolism candidate genes and the outcomes was also tested. Furthermore, associations between a drug induced liver injury (DILI) weighted genetic risk score (wGRS) and the outcomes were tested, combining 10 SNPs and 11 classical HLA alleles associated with DILI.

RESULTS

In genome-wide genetic analyses among 1,429 subjects of European ancestry who were randomized to receive LD-MTX, two SNPs reached genome wide significance for association with log transformed maximum ALT. We observed associations between established candidate genes in MTX pharmacogenetics and log transformed maximum AST and ALT, as well as in dichotomized outcome with AST or ALT > 2 x ULN. There was no association between DILI wGRS or candidate variants and AST, ALT, or DILI response.

CONCLUSIONS

Modest evidence was observed that common variants affected AST and ALT levels in subjects of European ancestry on LD-MTX, but this genetic effect is not useful as a clinical predictor of MTX toxicity.

Impact of SLCO1B1*5 on Flucloxacillin and Co-Amoxiclav-Related Liver Injury

Background: Idiosyncratic drug-induced liver injury (DILI) is a serious uncommon disease that may develop as a result of the intake of certain drugs such as the antimicrobials flucloxacillin and co-amoxiclav. The reported cases showed significant associations between DILI and various human leukocyte (HLA) markers. The solute carrier organic anion transporter 1B1 (SLCO1B1), a non-HLA candidate gene, was previously reported as a risk factor for liver injury induced by rifampin and methimazole. This study presumed that SLCO1B1 may play a general role in the DILI susceptibility and therefore investigated the association of rs4149056 (SLCO1B1*5, T521C) polymorphism with flucloxacillin- and co-amoxiclav-induced liver injury. Methodology: We recruited 155 and 165 DILI cases of white ancestral origin from various European countries but mainly from the United Kingdom owing to flucloxacillin and co-amoxiclav, respectively. Only adult patients (≥18 years) who were diagnosed with liver injury and who showed i) clinical jaundice or bilirubin >2x the upper limit of normal (ULN), ii) alanine aminotransferase (ALT) >5x ULN or iii) alkaline phosphatase (ALP) >2x ULN and bilirubin > ULN were selected. The population reference sample (POPRES), a European control group (n = 282), was used in comparison with the investigated cases. TaqMan SNP genotyping custom assay designed by Applied Biosystems was used to genotype both DILI cohorts for SLCO1B1 polymorphism (rs4149056). Allelic discrimination analysis was performed using a step one real-time PCR machine. Genotype differences between cases and controls were examined using Fisher's exact test. GraphPad Prism version 5.0 was used to determine the p-value, odds ratio, and 95% confidence interval. Compliance of the control group with Hardy-Weinberg equilibrium was proven using a web-based calculator available at https://wpcalc.com/en/equilibrium-hardy-weinberg/. Results: A small number of cases failed genotyping in each cohort. Thus, only 149 flucloxacillin and 162 co-amoxiclav DILI cases were analyzed. Genotyping of both DILI cohorts did not show evidence of association with the variant rs4149056 (T521C) (OR = 0.71, 95% CI = 0.46-1.12; p = 0.17 for flucloxacillin cases and OR = 0.87, 95% CI = 0.56-1.33; p = 0.58 for co-amoxiclav), although slightly lower frequency (22.8%) of positive flucloxacillin cases was noticed than that of POPRES controls (29.4%). Conclusion: Carriage of the examined allele SLCO1B1*5 is not considered a risk factor for flucloxacillin DILI or co-amoxiclav DILI as presumed. Testing a different allele (SLCO1B1*1B) and another family member gene (SLCO1B3) may still be needed to provide a clearer role of SLCO1B drug transporters in DILI development-related to the chosen antimicrobials.

Newly identified genetic variants associated with idiosyncratic drug-induced liver injury

PURPOSE OF REVIEW

Datasets of well characterized drug or herbal and dietary supplement-associated liver injury has provided a rich resource to identify genetic variants associated with hepatic injury that further supports the role of immune activation in drug-induced liver injury (DILI).

RECENT FINDINGS

Using DNA microarrays, whole genome sequencing, HLA-restricted DNA sequencing with appropriate ethnically matched population controls have identified HLA-specific genetic variants for drugs or botanical compounds with the same HLA variant associated with different agents. In addition to HLAs, two genes involved with immune signaling were also identified: a functional PTPN22 variant associated with increased DILI risk to any agent or clinical presentation and a variant in ERAP2 hepatic gene expression that trims peptide in preparation for presentation in the HLA cleft increased the risk for DILI in amoxicillin-clavulanate DILI when present with known HLA risk alleles.

SUMMARY

Variants in HLA and other genes involved in immune regulations further supports immune system activation in DILI. In the future, identifying these variants before exposure may minimize the risk for DILI events, help with assessment of drug causality for causing DILI and with greater understanding of DILI mechanisms, has important implication for future drug development.