Drug-induced cholestasis

Association of GST polymorphism with adverse drug reactions: an analysis across multiple drug categories

INTRODUCTION

Adverse drug reactions (ADRs) pose a significant challenge in clinical practice, impacting patient safety and treatment outcomes. Genetic variations in drug-metabolizing enzymes, particularly glutathione S-transferases (GSTs), have been implicated in modulating individual susceptibility to ADRs.

AREAS COVERED

This overview aims to explore the association between GSTs genetic polymorphisms and ADRs across diverse drug categories documented in current literature. Here we cover antiepileptic, immunosuppressive, chemotherapeutic agents, analgesics, antivirals, and antibiotics.

EXPERT OPINION

According to the existing literature, the association between genetic polymorphisms in GST theta (GSTT1), GST mu (GSTM1), and GST pi (GSTP1) and adverse drug reaction occurrence has been frequently reported. However, the strength of these associations varies considerably among studies, with some showing inconsistent or contradictory results, underscoring the need for further investigations.

Novel clinical phenotypes, drug categorization, and outcome prediction in drug-induced cholestasis: Analysis of a database of 432 patients developed by literature review and machine learning support

BACKGROUND

Serum transaminases, alkaline phosphatase and bilirubin are common parameters used for DILI diagnosis, classification, and prognosis. However, the relevance of clinical examination, histopathology and drug chemical properties have not been fully investigated. As cholestasis is a frequent and complex DILI manifestation, our goal was to investigate the relevance of clinical features and drug properties to stratify drug-induced cholestasis (DIC) patients, and to develop a prognosis model to identify patients at risk and high-concern drugs.

METHODS

DIC-related articles were searched by keywords and Boolean operators in seven databases. Relevant articles were uploaded onto Sysrev, a machine-learning based platform for article review and data extraction. Demographic, clinical, biochemical, and liver histopathological data were collected. Drug properties were obtained from databases or QSAR modelling. Statistical analyses and logistic regressions were performed.

RESULTS

Data from 432 DIC patients associated with 52 drugs were collected. Fibrosis strongly associated with fatality, whereas canalicular paucity and ALP associated with chronicity. Drugs causing cholestasis clustered in three major groups. The pure cholestatic pattern divided into two subphenotypes with differences in prognosis, canalicular paucity, fibrosis, ALP and bilirubin. A predictive model of DIC outcome based on non-invasive parameters and drug properties was developed. Results demonstrate that physicochemical (pKa-a) and pharmacokinetic (bioavailability, CYP2C9) attributes impinged on the DIC phenotype and allowed the identification of high-concern drugs.

CONCLUSIONS

We identified novel associations among DIC manifestations and disclosed novel DIC subphenotypes with specific clinical and chemical traits. The developed predictive DIC outcome model could facilitate DIC prognosis in clinical practice and drug categorization.

Investigating bile acid-mediated cholestatic drug-induced liver injury using a mechanistic model of multidrug resistance protein 3 (MDR3) inhibition

Inhibition of the canalicular phospholipid floppase multidrug resistance protein 3 (MDR3) has been implicated in cholestatic drug-induced liver injury (DILI), which is clinically characterized by disrupted bile flow and damage to the biliary epithelium. Reduction in phospholipid excretion, as a consequence of MDR3 inhibition, decreases the formation of mixed micelles consisting of bile acids and phospholipids in the bile duct, resulting in a surplus of free bile acids that can damage the bile duct epithelial cells, i.e., cholangiocytes. Cholangiocytes may compensate for biliary increases in bile acid monomers via the cholehepatic shunt pathway or bicarbonate secretion, thereby influencing viability or progression to toxicity. To address the unmet need to predict drug-induced bile duct injury in humans, DILIsym, a quantitative systems toxicology model of DILI, was extended by representing key features of the bile duct, cholangiocyte functionality, bile acid and phospholipid disposition, and cholestatic hepatotoxicity. A virtual, healthy representative subject and population (n = 285) were calibrated and validated utilizing a variety of clinical data. Sensitivity analyses were performed for 1) the cholehepatic shunt pathway, 2) biliary bicarbonate concentrations and 3) modes of MDR3 inhibition. Simulations showed that an increase in shunting may decrease the biliary bile acid burden, but raise the hepatocellular concentrations of bile acids. Elevating the biliary concentration of bicarbonate may decrease bile acid shunting, but increase bile flow rate. In contrast to competitive inhibition, simulations demonstrated that non-competitive and mixed inhibition of MDR3 had a profound impact on phospholipid efflux, elevations in the biliary bile acid-to-phospholipid ratio, cholangiocyte toxicity, and adaptation pathways. The model with its extended bile acid homeostasis representation was furthermore able to predict DILI liability for compounds with previously studied interactions with bile acid transport. The cholestatic liver injury submodel in DILIsym accounts for several processes pertinent to bile duct viability and toxicity and hence, is useful for predictions of MDR3 inhibition-mediated cholestatic DILI in humans.

Drug-induced liver injury: A management position paper from the Latin American Association for Study of the liver

Idiosyncratic drug-induced liver injury (DILI) caused by xenobiotics (drugs, herbals and dietary supplements) is an uncommon cause of liver disease presenting with a wide range of phenotypes and disease severity, acute hepatitis mimicking viral hepatitis to autoimmune hepatitis, steatosis, fibrosis or rare chronic vascular syndromes. Disease severity ranges from asymptomatic liver test abnormalities to acute liver failure. DILI has been traditionally classified in predictable or intrinsic (dose-related) or unpredictable (not dose-related) mechanisms. Few prospective studies are assessing the real prevalence and incidence of hepatotoxicity in the general population. DILI registries represent useful networks used for the study of liver toxicity, aimed at improving the understanding of causes, phenotypes, natural history, and standardized definitions of hepatotoxicity. Although most of the registries do not carry out population-based studies, they may provide important data related to the prevalence of DILI, and also may be useful to compare features from different countries. With the support of the Spanish Registry of Hepatotoxicity, our Latin American Registry (LATINDILI) was created in 2011, and more than 350 DILI patients have been recruited to date. This position paper describes the more frequent drugs and herbs-induced DILI in Latin America, mainly focusing on several features of responsible medicaments. Also, we highlighted the most critical points on the management of hepatotoxicity in general and those based on findings from our Latin American experience in particular.

Drug-Induced Vanishing Bile Duct Syndrome: From Pathogenesis to Diagnosis and Therapeutics

The most concerned issue in the context of drug/herb-induced chronic cholestasis is vanishing bile duct syndrome. The progressive destruction of intrahepatic bile ducts leading to ductopenia is usually not dose dependent, and has a delayed onset that should be suspected when abnormal serum cholestasis enzyme levels persist despite drug withdrawal. Immune-mediated cholangiocyte injury, direct cholangiocyte damage by drugs or their metabolites once in bile, and sustained exposure to toxic bile salts when biliary epithelium protective defenses are impaired are the main mechanisms of cholangiolar damage. Current therapeutic alternatives are scarce and have not shown consistent beneficial effects so far. This review will summarize the current literature on the main diagnostic tools of ductopenia and its histological features, and the differential diagnostic with other ductopenic diseases. In addition, pathomechanisms will be addressed, as well as the connection between them and the supportive and curative strategies for ductopenia management.

Second-Generation Cephalosporins-Associated Drug-Induced Liver Disease: A Study in VigiBase with a Focus on the Elderly

Background: The objective of this study was to characterize individual case safety reports (ICSRs) and adverse drug reactions (ADRs) related to second-generation cephalosporins and resulting in hepatobiliary disorders, in VigiBase, WHO global database. Methods: All second-generation cephalosporins hepatobiliary ADRs reported up to July 2019 were included. Characteristic of cephalosporins and ADRs, aside from disproportionality data were evaluated. Results: A total of 1343 ICSRs containing 1585 ADRs were analyzed. Cefuroxime was suspected to have caused hepatobiliary disorders in most cases—in 38% of adults and in 35% of elderly. Abnormal hepatic function was the most frequent ADR, followed by jaundice and hepatitis. For 49% of the ADRs reported in the elderly and 51% in the adult population, the outcome was favorable, with fatal outcome for 2% of the adults and 10% of the elderly. Higher proportional reporting ration (PRR) values were reported in the elderly for cefotetan-associated jaundice, cefuroxime-associated acute hepatitis and hepatitis cholestatic as well as for cefotiam and cefmetazole-associated liver disorder. Conclusion: Hepatobiliary ADRs were reported for 2nd generation cephalosporins, with over 50% of cases in adults, without gender differences. Cholestatic hepatitis was predominately reported in the elderly and this category was more prone to specific hepatic reactions.

Drug-Induced Liver Injury Caused by Amoxicillin/Clavulanate

Drug-induced liver injury (DILI) has a relatively low incidence, and as it is a diagnosis of exclusion, it can become quite a challenge for the clinician. Amoxicillin/clavulanate continues to be one of the most prescribed antibiotics and only rarely causes liver injury. We report a case of DILI associated with this antibiotic to bring attention to a rare side effect of a very commonly prescribed drug. This is the case of a 71-year-old man, with no relevant past medical history, who presented to the Emergency Department due to jaundice in the previous two weeks, with no immediate identifiable cause. The patient was admitted to our Internal Medicine Ward, and after getting a detailed clinical history and excluding other common and severe causes of liver injury, the diagnosis was made that liver injury was due to amoxicillin/clavulanate intake, thus demonstrating the importance of an in-depth history.

A Novel MicroRNA Signature for Cholestatic Drugs in Human Hepatocytes and Its Translation into Novel Circulating Biomarkers for Drug-Induced Liver Injury Patients

Drug-induced liver injury (DILI) diagnosis and classification (hepatocellular, cholestatic, and mixed) relies on traditional clinical biomarkers (eg ALT and ALP), despite limitations such as extrahepatic interferences, narrow dynamic ranges, and low mechanistic value. microRNAs may be very useful for complementing traditional DILI biomarkers but most studies in this direction have considered only paracetamol poisoning. Thus the value of microRNAs (miRNAs) as biomarkers for idiosyncratic DILI has not yet been demonstrated. In this study, we first examined the effect of model cholestatic drugs on the human hepatocyte miRNome by RNAseq and RT-qPCR. Results demonstrated that chlorpromazine, cyclosporin A, and ANIT induced (miR-21-3p, -21-5p, -22-3p, -27a-5p, -1260b, -34a-5p, and -98-5p) and repressed (-122-5p, -192-5p, -30c-5p, -424-5p, and -16-5p) specific miRNAs in sandwich-cultured upcyte hepatocytes. However, no common signature was found for cholestatic drugs. Next we investigated the levels of these miRNA in human serum and found that most were also significantly altered in cholestatic/mixed DILI patients upon hospital/ambulatory admission. However, miR-122-5p, -192-5p, -34a-5p, and -22-3p demonstrated a much more significant induction in patients with hepatocellular DILI, thus revealing better specificity for hepatocellular damage. Time-course analyses demonstrated that -1260b and -146 had a very similar profile to ALP, but with wider dynamic ranges, while -16-5p and -451a showed a negative correlation. Conversely, -122-5p and -192-5p correlated with ALT but with wider dynamic ranges and faster recoveries. Finally, the 122/451a and 122/16 ratios showed excellent prediction performances in both the study [area under the receiver operating characteristic curve (AUROC) >0.93] and the validation cohort (AUROC > 0.82), and can, therefore, be postulated for the first time as circulating miRNA biomarkers for idiosyncratic DILI.

A Severe Case of Drug-Induced Liver Injury after Gemcitabine Administration: A Highly Probable Causality Grading as Assessed by the Updated RUCAM Diagnostic Scoring System

Gemcitabine is an antineoplastic drug used in several forms of advanced pancreatic, lung, breast, ovarian, and bladder cancer. Common side effects include bone marrow suppression, fatigue, diarrhea, nausea, gastrointestinal upset, rash, alopecia, and stomatitis. Transient serum enzyme elevations could be observed during therapy, but clinically significant acute liver injury has been rarely associated with its use. Few cases of acute liver injury have been reported in the literature. We reported the clinical case of a 73--year-old man who developed clinically significant acute hepatic injury after using gemcitabine. Possible causes, clinical presentation, and treatments are discussed. According to the updated RUCAM score, the case was rated 10 points and became a suspected drug-induced liver injury. Moreover, on the liver biopsy, there were histological findings of mild-to-moderate portal hepatitis, eosinophilia, bile duct injury, and mild perisinusoidal fibrosis, suggesting drug damage.

Bile canaliculi contract autonomously by releasing calcium into hepatocytes via mechanosensitive calcium channel

Drug-induced hepatocellular cholestasis leads to altered bile flow. Bile is propelled along the bile canaliculi (BC) by actomyosin contractility, triggered by increased intracellular calcium (Ca²⁺). However, the source of increased intracellular Ca²⁺ and its relationship to transporter activity remains elusive. We identify the source of the intracellular Ca²⁺ involved in triggering BC contractions, and we elucidate how biliary pressure regulates Ca²⁺ homeostasis and associated BC contractions. Primary rat hepatocytes were cultured in collagen sandwich. Intra-canalicular Ca²⁺ was measured with fluo-8; and intra-cellular Ca²⁺ was measured with GCaMP. Pharmacological modulators of canonical Ca²⁺-channels were used to study the Ca²⁺-mediated regulation of BC contraction. BC contraction correlates with cyclic transfer of Ca²⁺ from BC to adjacent hepatocytes, and not with endoplasmic reticulum Ca²⁺. A mechanosensitive Ca²⁺ channel (MCC), Piezo-1, is preferentially localized at BC membranes. The Piezo-1 inhibitor GsMTx-4 blocks the Ca²⁺ transfer, resulting in cholestatic generation of BC-derived vesicles whereas Piezo-1 hyper-activation by Yoda1 increases the frequency of Ca²⁺ transfer and BC contraction cycles. Yoda1 can recover normal BC contractility in drug-induced hepatocellular cholestasis, supporting that Piezo-1 regulates BC contraction cycles. Finally, we show that hyper-activating Piezo-1 can be exploited to normalize bile flow in drug-induced hepatocellular cholestasis.

Cholestatic liver injury induced by food additives, dietary supplements and parenteral nutrition

Cholestasis refers to the accumulation of toxic levels of bile acids in the liver due to defective bile secretion. This pathological situation can be triggered by drugs, but also by ingredients contained in food, food supplements and parenteral nutrition. This paper provides an overview of the current knowledge on cholestatic injury associated with such ingredients, with particular emphasis on the underlying mechanisms of toxicity.

The Cumulative Risk Assessment of Hepatotoxic Chemicals: A Hepatic Histopathology Perspective

The increased concern on the consequence of exposure to multiple chemical combinations has led national regulatory authorities to develop different concepts to conduct risk assessments on chemical mixtures. Pesticide residues were identified as "problem formulation" in the respective European regulations and in this context, the European Food and Safety Authority has suggested to group pesticidal active ingredients (AIs) into cumulative assessment groups (CAGs) based on the toxicological properties of each AI. One proposed CAG, on the liver, currently consists of 15 subgroups, each representing a specific hepatotoxic effect observed in toxicity studies. Dietary cumulative risk assessments would then have to be conducted assuming dose additivity of all members of each CAG subgroup. The purpose of this publication is to group AIs based upon the knowledge of the pathogenesis of liver effects to discriminate between primary end points (direct consequence of chemical interaction with a biological target) and secondary end points (which are a consequence of, or that arise out of, a previous pathological change). Focusing on the relevant primary end points strengthens and simplifies the selection of compounds for cumulative risk assessment regarding the liver and better rationalizes the basis for chemical grouping. Relevant dose additivity is to be expected at the level of the primary/leading pathological end points and not at the level of the secondary end points. We recognize, however, that special consideration is needed for substances provoking neoplasia, and this category is included in the group of primary end points for which chemicals inducing them are grouped for risk assessment. Using the pathological basis for defining the respective CAGs, 6 liver subgroups and 2 gallbladder/bile duct groups are proposed. This approach simplifies the cumulative assessment calculation without obviously affecting consumer safety.

Mechanisms of Hepatic Cholestatic Drug Injury

Drug-induced cholestasis represents a form of drug-induced liver disease that can lead to severe impairment of liver function. Numerous drugs have been shown to cause cholestasis and consequently bile duct toxicity. However, there is still lack of therapeutic tools that can prevent progression to advanced stages of liver injury. This review focuses on the various pathological mechanisms by which drugs express their hepatotoxic effects, as well as consequences of increased bile acid and toxin accumulation in the hepatocytes.

Bibliometric Analysis of Global Research on Clavulanic Acid

Clavulanic acid (CA), a potent inhibitor of the β-lactam, ase enzyme, is frequently co-formulated with a broad spectrum of antibiotics to treat infections caused by β-lactamase-producing pathogens. In order to evaluate the impact and the progress of CA studies in the last four decades, a bibliometric analysis of the global scientific production of CA was carried out. A total of 39,758 records in the field of CA were indexed in the Scopus database for a 43-year period of study (1975⁻2017). The results indicated that CA studies have grown, showing three phases (1975⁻1999, 2000⁻2003 and 2004⁻2017) based on records of publications; the results showed a sigmoidal profile. Medicine was the main subject area for CA studies, whereas biochemistry, genetics and molecular biology were areas of research for CA production by Streptomyces clavuligerus (S. clavuligerus). Nevertheless, chemical engineering (as a subject area) had the highest increase in the percentage of publications related to CA production by S. clavuligerus. The United States, France, the United Kingdom, Spain and Brazil were the leading countries in the scientific production of studies on both CA and CA related to S. clavuligerus. This analysis allowed the identification of the area of knowledge with the highest impact on CA studies, the top researchers and their geographic distribution, and also helped to highlight the existence of antibiotic-resistant bacteria as an emergent area in CA research.

Advances in drug-induced cholestasis: Clinical perspectives, potential mechanisms and in vitro systems

Despite growing research, drug-induced liver injury (DILI) remains a serious issue of increasing importance to the medical community that challenges health systems, pharmaceutical industries and drug regulatory agencies. Drug-induced cholestasis (DIC) represents a frequent manifestation of DILI in humans, which is characterised by an impaired canalicular bile flow resulting in a detrimental accumulation of bile constituents in blood and tissues. From a clinical point of view, cholestatic DILI generates a wide spectrum of presentations and can be a diagnostic challenge. The drug classes mostly associated with DIC are anti-infectious, anti-diabetic, anti-inflammatory, psychotropic and cardiovascular agents, steroids, and other miscellaneous drugs. The molecular mechanisms of DIC have been investigated since the 1980s but they remain debatable. It is recognised that altered expression and/or function of hepatobiliary membrane transporters underlies some forms of cholestasis, and this and other concomitant mechanisms are very likely in DIC. Deciphering these processes may pave the ways for diagnosis, prognosis and prevention, for which currently major gaps and caveats exist. In this review, we summarise recent advances in the field of DIC, including clinical aspects, the potential mechanisms postulated so far and the in vitro systems that can be useful to investigate and identify new cholestatic drugs.

The Incidence and Predictive Factors in the Development of Acute Hepatitis in Patients with Leukemia

Introduction

Liver involvement is common in hematological malignancies, but the incidence and pattern of liver injury vary among the different types. The aims of our study were to determine the incidence and clinical course of acute hepatitis and the important factors for its development in patients with leukemia after chemotherapy.

Materials and methods

All patients with the diagnosis of leukemia who were treated at the Department of Hematology between January 2008 and January 2013 were included in the study. A detailed medical history, clinical and laboratory findings, treatment modalities, complications, and clinical course were recorded retrospectively.

Results

A total of 124 patients (64 females) with the diagnosis of leukemia were included in the study. The mean age was 45.2 years (16-89 years) and mean follow-up time was 29.7 months (0.25-192 months). A total of 43 (34.6%) patients had acute hepatitis after chemotherapy. Pattern of liver injury was hepatocellular in 31 patients, cholestasis in 2, and mix in 10 patients. Age (p = 0.001), hepatitis B surface antigen (HBsAg, p = 0.007), acute leukemia (p < 0.001), positive blood culture (p = 0.004), the amount of transfused red blood cell (p = 0.001), and amount of transfused platelets (p = 0.002) were significantly different under univariate analysis between the acute hepatitis group and the nonacute hepatitis group. Under multivariate analysis, only acute lymphoblastic leukemia (ALL) was identified as independent predictive factor for development of acute hepatitis after starting chemotherapy.

Conclusion

Acute and self-limited hepatitis develops in the substantial proportion of patients with leukemia. The most important factor for development of acute hepatitis is the type of leukemia.

How to cite this article: Kaya M, Akdogan R, Uçmak F, Ayyildiz MO, Karakus A, Kaplan MA. The Incidence and Predictive Factors in the Development of Acute Hepatitis in Patients with Leukemia. Euroasian J Hepato-Gastroenterol 2018;8(1):31-37.

Cross-validation Studies of a Novel Low-cost Hepatitis B Virus Quantitative Polymerase Chain Reaction System

Aim

This research focused on the results of the cross-validation program related with the performance of a Cuban novel low-cost real-time quantitative polymerase chain reaction (qPCR) assay for hepatitis B virus (HBV) quantification developed by the Therapeutic Vaccine against Hepatitis B Department, Vaccines Division, Center for Genetic Engineering and Biotechnology (CIGB), Havana, Cuba.

Materials and methods

Dilution series with the plasmid standard at concentrations of 900,000 to 0.09 copies/reaction (c/r) were made for each PCR instrument. The mean cycles threshold (Ct) values and PCR efficiency were compared among the cyclers. Hepatitis B virus-positive serum samples were used for the calculation of reproducibility of the HBV assay. Biotecon Diagnostics (BCD) also ordered the oligo sequences from a second supplier and compared the PCR performance to those provided from the CIGB.

Results

All PCR cyclers were able to detect concentrations up to 0.09 c/r. However, below the concentration of 9 c/r, the variation of results increased within and between the cyclers. The PCR efficiency showed satisfying results. The overall coefficient of variation (CV) cycler values were 1.29 and 0.91% for M6 and M19 respectively. No significance was observed between the different primer suppliers.

Conclusion

The HBV assay was performed with a good concordance between the five real-time instruments from different suppliers. The HBV assay was also performed with a high reproducibility for samples with a high and a low viral load. The HBV assay is robust against different primer suppliers.

How to cite this article: Aguiar J, Silva JA, García G, Guillén G, Aguilar JC. Cross-validation Studies of a Novel Low-cost Hepatitis B Virus Quantitative Polymerase Chain Reaction System. Euroasian J Hepato-Gastroenterol 2018;8(1):38-41.

Review article: therapeutic bile acids and the risks for hepatotoxicity

BACKGROUND

Bile acids play important roles in cholesterol metabolism and signal through farnesoid X receptor and G protein-coupled receptors. Given their importance in liver biology, bile acid therapy enables therapeutic applications beyond the treatment of cholestatic liver disease. However, predicting hepatotoxicity of bile acids in humans is obscured due to inconsistent extrapolations of animal data to humans.

AIM

To review the evidence that could explain discordant bile acids hepatotoxicity observed in humans and animals.

METHOD

Literature search was conducted in PubMed using keywords "bile acid," "transporter," "hepatotoxicity," "clinical study," "animal study," "species difference," "mechanism," "genetic disorder." Relevant articles were selected for review.

RESULTS

Clinically significant hepatotoxicity was reported in response to certain bile acids, namely chenodeoxycholic acid, which was given a boxed warning for potential hepatotoxicity. The chemical structure, specifically the number and orientation of hydroxyl groups, significantly affects their hydrophobicity, an important factor in bile acid toxicity. Experimental studies show that hydrophobic bile acids can lead to liver injury through various mechanisms, such as death receptor signalling, mitochondrial dysfunction and inflammation. Although animal studies play a central role in investigating bile acid safety, there are considerable differences in bile acid composition, metabolism and hepatobiliary disposition across species. This does not allow appropriate safety inference, especially for predicting hepatotoxicity in humans. Exploring evidences stemming from inborn errors, genetic models of disease and toxicology studies further improves an understanding of bile acid hepatotoxicity.

CONCLUSION

Species differences should be considered in the development of bile acid related therapeutics. Although the mechanism of bile acid hepatotoxicity is still not fully understood, continued mechanistic studies will deepen our understanding.

Drug-induced cholestasis

Cholestatic drug-induced liver injury (DILI) can be a diagnostic challenge due to a large differential diagnosis, variability in clinical presentation, and lack of serologic biomarkers associated with this condition. The clinical presentation of drug-induced cholestasis includes bland cholestasis, cholestatic hepatitis, secondary sclerosing cholangitis, and vanishing bile duct syndrome. The associate mortality of cholestatic DILI can be as high as 10%, and thus prompt recognition and removal of the offending agent is of critical importance. Several risk factors have been identified for drug-induced cholestasis, including older age, genetic determinants, and properties of certain medications. Antibiotics, particularly amoxicillin/clavulanate, remain the predominant cause of cholestatic DILI, although a variety of other medications associated with this condition have been identified. In this review, we summarize the presentation, clinical approach, risk factors, implicated medications, and management of drug-induced cholestatic liver injury. (Hepatology Communications 2017;1:726-735).

The in silico identification of human bile salt export pump (ABCB11) inhibitors associated with cholestatic drug-induced liver injury

Drug-induced liver injury (DILI) is one of the major causes of drug attrition and failure. Currently, there is increasing evidence that direct inhibition of the human bile salt export pump (BSEP/ABCB11) by drugs and/or metabolites is one of the most important mechanisms of cholestatic DILI. In the present study, we employ two in silico methods, random forest (RF) and the pharmacophore method, to recognize potential BSEP inhibitors that could cause cholestatic DILI, with the aim of mitigating the risk of cholestatic DILI to some extent. The RF model achieved the best prediction performance, producing AUC (area under receiver operating characteristic curve) values of 0.901, 0.929 and 0.996 for leave-one-out cross-validation, the test set and the external test set, respectively, indicating that the built RF model has a satisfactory identification ability. As a complement to the RF model, the pharmacophore model was also built and was proved to be reliable with good predictive performance based on the internal and external validation results. Further analysis indicates that hydrophobicity, molecular size and polarity are important factors that influence the inhibitory activity of BSEP. Furthermore, the two models are applied to screen FDA-approved small molecule drugs, among which the drugs with the potential risk of cholestatic DILI are reported. In conclusion, the RF and pharmacophore models that we present can be considered as integrated screening tools to indicate the potential risk of cholestatic DILI by inhibition of BSEP.

Rho-kinase/myosin light chain kinase pathway plays a key role in the impairment of bile canaliculi dynamics induced by cholestatic drugs

Intrahepatic cholestasis represents a frequent manifestation of drug-induced liver injury; however, the mechanisms underlying such injuries are poorly understood. In this study of human HepaRG and primary hepatocytes, we found that bile canaliculi (BC) underwent spontaneous contractions, which are essential for bile acid (BA) efflux and require alternations in myosin light chain (MLC2) phosphorylation/dephosphorylation. Short exposure to 6 cholestatic compounds revealed that BC constriction and dilation were associated with disruptions in the ROCK/MLCK/myosin pathway. At the studied concentrations, cyclosporine A and chlorpromazine induced early ROCK activity, resulting in permanent MLC2 phosphorylation and BC constriction. However, fasudil reduced ROCK activity and caused rapid, substantial and permanent MLC2 dephosphorylation, leading to BC dilation. The remaining compounds (1-naphthyl isothiocyanate, deoxycholic acid and bosentan) caused BC dilation without modulating ROCK activity, although they were associated with a steady decrease in MLC2 phosphorylation via MLCK. These changes were associated with a common loss of BC contractions and failure of BA clearance. These results provide the first demonstration that cholestatic drugs alter BC dynamics by targeting the ROCK/MLCK pathway; in addition, they highlight new insights into the mechanisms underlying bile flow failure and can be used to identify new predictive biomarkers of drug-induced cholestasis.

Case Characterization, Clinical Features and Risk Factors in Drug-Induced Liver Injury

Idiosyncratic drug-induced liver injury (DILI) caused by xenobiotics (drugs, herbals and dietary supplements) presents with a range of both phenotypes and severity, from acute hepatitis indistinguishable of viral hepatitis to autoimmune syndromes, steatosis or rare chronic vascular syndromes, and from asymptomatic liver test abnormalities to acute liver failure. DILI pathogenesis is complex, depending on the interaction of drug physicochemical properties and host factors. The awareness of risk factors for DILI is arising from the analysis of large databases of DILI cases included in Registries and Consortia networks around the world. These networks are also enabling in-depth phenotyping with the identification of predictors for severe outcome, including acute liver failure and mortality/liver transplantation. Genome wide association studies taking advantage of these large cohorts have identified several alleles from the major histocompatibility complex system indicating a fundamental role of the adaptive immune system in DILI pathogenesis. Correct case definition and characterization is crucial for appropriate phenotyping, which in turn will strengthen sample collection for genotypic and future biomarkers studies.

Pathophysiology and Diseases of the Proximal Pathways of the Biliary System

CONTEXT

Diseases of the proximal pathways of the biliary system can be divided into those that affect the interlobular bile ducts and those that affect the bile canaliculi. The former include primary biliary cirrhosis, small-duct variant of primary sclerosing cholangitis, graft-versus-host disease, and drug-induced liver injury, whereas the latter include progressive familial intrahepatic cholestasis, benign recurrent intrahepatic cholestasis, intrahepatic cholestasis of pregnancy, and drug-induced liver injury.

OBJECTIVE

To summarize the current state of knowledge of diseases of the proximal pathways of the biliary system, with special emphasis on clinical presentation, pathological features, and differential diagnosis.

DATA SOURCES

Clinicopathological information was extracted from pertinent published literature.

CONCLUSIONS

Care of the patient with cholestasis hinges on identifying the etiology. Diagnostic steps in cholestatic conditions comprise a thorough patient history, abdominal imaging, distinct serological studies, and liver biopsy. Primary biliary cirrhosis is characterized by distinctive serological and histological findings. The small-duct variant of primary sclerosing cholangitis is very rare and difficult to diagnose; imaging of the bile ducts is not helpful. Graft-versus-host disease is characterized by damage and loss of intrahepatic bile ducts. Drugs can cause injury variably at the level of bile canaliculus or the interlobular bile duct. Loss of bile ducts may be seen with primary biliary cirrhosis, primary sclerosing cholangitis, graft-versus-host disease, and drug-induced liver injury. Progressive familial intrahepatic cholestasis and progressive familial intrahepatic cholestasis represent 2 extreme ends of the spectrum of abnormalities in transporters responsible for bile formation. Intrahepatic cholestasis of pregnancy has a variable incidence in different parts of the world and may be due to abnormalities in transporter molecules.

Psychotropic medication use: what will it do to my liver?

Liver toxicity is the leading reason for withdrawal of marketed drugs and is a common reason for terminating the development of new drugs. Anticonvulsant, antidepressant, and antipsychotic drugs can be associated with significant liver injury or liver failure, but this is relatively rare compared to other non-psychotropic drug classes. More commonly, mild asymptomatic elevations in liver function tests are seen and these are not predictive of progression to more severe liver injury. Laboratory monitoring of liver function before and during treatment is recommended with the use of valproic acid and carbamazepine, but not for other psychotropic drugs, although regular laboratory testing is not a reliable method for detecting or preventing severe liver injury. Clinical monitoring for signs and symptoms suggesting hepatotoxicity or hypersensitivity reactions that affect the liver is more important.

Risk factors for severe or fatal drug-induced liver injury from amoxicillin-clavulanic acid

AIM

To identify risk factors for severe liver injury or mortality from drug-induced liver injury (DILI) from amoxicillin-clavulanic acid. To determine if co-administration of potentially hepatotoxic drugs was associated with an increased risk of DILI from amoxicillin-clavulanic acid.

METHODS

We conducted a systematic review of the published work and data extraction of articles on DILI injury from amoxicillin-clavulanic acid. Potentially hepatotoxic drugs were defined as medications with DILI listed in the package insert or reported in the published work. Individual patient data were entered into an SPSS (version 17.0; Chicago, IL, USA) database and were analyzed using the χ(2) -test or Fisher's exact test; Student's t-test; and non-parametric tests such as Mann-Whitney U-test as appropriate.

RESULTS

We identified 3932 articles of which 41 publications with 255 reported cases met inclusion criteria. Mortality from DILI from amoxicillin-clavulanic acid was increased among patients receiving concomitant potentially hepatotoxic drugs compared with patients not on concomitant potential hepatotoxic drugs (21.4% [3/14] vs 2.3% [2/89], P = 0.017]. The most common classes of concomitant drugs were: antimicrobials, analgesics and hormonal therapy. Female patients were more likely to receive a concomitant potentially hepatotoxic medication (25% vs 9.1% for men, P = 0.05).

CONCLUSION

Patients who developed severe or fatal DILI from amoxicillin-clavulanic acid were more likely to be on concomitant hepatotoxic medications. Female patients were more likely to receive concomitant hepatotoxic drugs. Further studies are needed to investigate drug interaction between amoxicillin-clavulanic acid and concomitant potentially hepatotoxic drugs.

Quantitative assessment of the multiple processes responsible for bilirubin homeostasis in health and disease

Serum bilirubin measurements are commonly obtained for the evaluation of ill patients and to screen for liver disease in routine physical exams. An enormous research effort has identified the multiple mechanisms involved in the production and metabolism of conjugated (CB) and unconjugated bilirubin (UB). While the qualitative effects of these mechanisms are well understood, their expected quantitative influence on serum bilirubin homeostasis has received less attention. In this review, each of the steps involved in bilirubin production, metabolism, hepatic cell uptake, and excretion is quantitatively examined. We then attempt to predict the expected effect of normal and defective function on serum UB and CB levels in health and disease states including hemolysis, extra- and intrahepatic cholestasis, hepatocellular diseases (eg, cirrhosis, hepatitis), and various congenital defects in bilirubin conjugation and secretion (eg, Gilbert's, Dubin-Johnson, Crigler-Najjar, Rotor syndromes). Novel aspects of this review include: 1) quantitative estimates of the free and total UB and CB in the plasma, hepatocyte, and bile; 2) detailed discussion of the important implications of the recently recognized role of the hepatic OATP transporters in the maintenance of CB homeostasis; 3) discussion of the differences between the standard diazo assay versus chromatographic measurement of CB and UB; 4) pharmacokinetic implications of the extremely high-affinity albumin binding of UB; 5) role of the enterohepatic circulation in physiologic jaundice of newborn and fasting hyperbilirubinemia; and 6) insights concerning the clinical interpretation of bilirubin measurements.

Atypical causes of cholestasis

Cholestatic liver disease consists of a variety of disorders. Primary sclerosing cholangitis and primary biliary cirrhosis are the most commonly recognized cholestatic liver disease in the adult population, while biliary atresia and Alagille syndrome are commonly recognized in the pediatric population. In infants, the causes are usually congenital or inherited. Even though jaundice is a hallmark of cholestasis, it is not always seen in adult patients with chronic liver disease. Patients can have “silent” progressive cholestatic liver disease for years prior to development of symptoms such as jaundice and pruritus. In this review, we will discuss some of the atypical causes of cholestatic liver disease such as benign recurrent intrahepatic cholestasis, progressive familial intrahepatic cholestasis, Alagille Syndrome, biliary atresia, total parenteral nutrition induced cholestasis and cholestasis secondary to drug induced liver injury.

The role of canalicular ABC transporters in cholestasis

Cholestasis, a hallmark feature of hepatobiliary disease, is characterized by the retention of biliary constituents. Some of these constituents, such as bile acids, inflict damage to hepatocytes and bile duct cells. This damage may lead to inflammation, fibrosis, cirrhosis, and eventually carcinogenesis, sequelae that aggravate the underlying disease and deteriorate clinical outcome. Canalicular ATP-binding cassette (ABC) transporters, which mediate the excretion of individual bile constituents, play a key role in bile formation and cholestasis. The study of these transporters and their regulatory nuclear receptors has revolutionized our understanding of cholestatic disease. This knowledge has served as a template to develop novel treatment strategies, some of which are currently already undergoing phase III clinical trials. In this review we aim to provide an overview of the structure, function, and regulation of canalicular ABC transporters. In addition, we will focus on the role of these transporters in the pathogenesis and treatment of cholestatic bile duct and liver diseases.

Drug-induced cholestasis

Drug-induced cholestasis manifests as an acute self-limiting injury or as a chronic perpetuating injury, resulting in duct loss and cirrhosis. The number of drugs implicated in drug-induced cholestasis grows every year as new drugs are developed and approved. Other agents such as herbals, nutritional supplements, and complementary and alternative medicines are also reported to cause cholestatic liver injury. Recent literature on molecular transporters involved in bile transport has improved our understanding of patterns of drug-induced liver injury and the mechanisms of cholestasis. This article summarizes the probable offending drugs, and the diagnosis and management of drug-induced cholestasis.

Drug-induced perturbations of the bile acid pool, cholestasis, and hepatotoxicity: mechanistic considerations beyond the direct inhibition of the bile salt export pump

The bile salt export pump (BSEP) is located on the canalicular plasma membrane of hepatocytes and plays an important role in the biliary clearance of bile acids (BAs). Therefore, any drug or new chemical entity that inhibits BSEP has the potential to cause cholestasis and possibly liver injury. In reality, however, one must consider the complexity of the BA pool, BA enterohepatic recirculation (EHR), extrahepatic (renal) BA clearance, and the interplay of multiple participant transporters and enzymes (e.g., sulfotransferase 2A1, multidrug resistance-associated protein 2, 3, and 4). Moreover, BAs undergo extensive enzyme-catalyzed amidation and are subjected to metabolism by enterobacteria during EHR. Expression of the various enzymes and transporters described above is governed by nuclear hormone receptors (NHRs) that mount an adaptive response when intracellular levels of BAs are increased. The intracellular trafficking of transporters, and their ability to mediate the vectorial transport of BAs, is governed by specific kinases also. Finally, bile flow, micelle formation, canalicular membrane integrity, and BA clearance can be influenced by the inhibition of multidrug resistant protein 3- or ATPase-aminophospholipid transporter-mediated phospholipid flux. Consequently, when screening compounds in a discovery setting or conducting mechanistic studies to address clinical findings, one has to consider the direct (inhibitory) effect of the parent drug and metabolites on multiple BA transporters, as well as inhibition of BA sulfation and amidation and NHR function. Vectorial BA transport, in addition to BA EHR and homoeostasis, could also be impacted by drug-dependent modulation of kinases and enterobacteria.

Biliary Proliferative Lesions in the Sprague-Dawley Rat

Whether biliary proliferative lesions in nonclinical species are predictive of potential hepatotoxicity in humans depends, at least in part, on the nature and severity of such changes in the nonclinical species. We reviewed published literature (clinical and nonclinical) and experimental data from rat toxicology studies conducted by GlaxoSmithKline and the National Institute of Environmental Health Sciences’ National Toxicology Program in an effort to better characterize the relative risk of hepatobiliary effects in humans. Available evidence supports the interpretation that minimal “typical” appearing bile duct hyperplasia limited to the portal triads may be considered non-adverse in the rat and is of little to no concern to humans. The toxicological relevance of mild to moderate “typical” hyperplasia is less certain, and may be considered adverse in the rat and potentially pose a risk for humans, particularly if accompanied by evidence of hepatobiliary injury or functional compromise. In addition, any proliferative lesion that includes atypical or dysplastic epithelial changes, oval cell proliferation, and/or significant extension beyond the portal tracts is considered more ominous and may be considered adverse in the rat.