Pharmacogenetic study of drug-metabolising enzyme polymorphisms on the risk of anti-tuberculosis drug-induced liver injury: a meta-analysis

Genetic polymorphisms and anti-tuberculosis drug-induced liver injury: an umbrella review of the evidence

BACKGROUND

Anti-tuberculosis drug-induced liver injury (ATLI) is a significant adverse drug reaction with genetic susceptibility implications.

AIM

This study aimed to integrate findings from systematic reviews and meta-analyses on genetic polymorphisms associated with ATLI risk, enhance evidence synthesis, and identify susceptibility gene polymorphisms linked to ATLI occurrence.

METHOD

The protocol was registered in PROSPERO (CRD42024517311). Systematic searches of PubMed, EMBASE, Web of Science, and Cochrane Library databases were conducted to identify eligible studies from inception to February 21, 2024. Two authors independently reviewed eligibility, extracted data, and assessed quality. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate associations between genetic polymorphisms and ATLI susceptibility.

RESULTS

A total of 25 meta-analyses were included, including 57 single nucleotide polymorphisms (SNPs) in 15 candidate genes. Significant associations were found for the glutathione S-transferase M1 (GSTM1) null genotype (OR = 1.43, 95% CI: 1.18-1.73, P < 0.001) and N-acetyltransferase 2 (NAT2) polymorphisms, including rs1799929 (dominant model, OR = 1.35, 95% CI: 1.12-1.63, P < 0.001), rs1799930 (dominant model, OR = 1.43, 95% CI: 1.23-1.66, P < 0.001), rs1799931 (dominant model, OR = 1.22, 95% CI: 1.02-1.46, P = 0.03), and the slow acetylator (SA) phenotype (OR = 2.91, 95% CI: 2.43-3.49, P < 0.001). No significant association was found between the CYP2E1 RsaI/PstI polymorphism (C1/C1 genotype) and ATLI risk (dominant model, OR = 0.79, 95% CI: 0.61-1.02, P = 0.08).

CONCLUSION

This umbrella review confirms that the GSTM1 null genotype, NAT2 polymorphisms (rs1799929, rs1799930, rs1799931), and the slow acetylator phenotype are associated with increased ATLI risk. These findings provide a foundation for further research on genotype-guided approaches to mitigating ATLI.

Pharmacogenetics of tuberculosis treatment toxicity and effectiveness in a large Brazilian cohort

BACKGROUND

Genetic polymorphisms have been associated with risk of antituberculosis treatment toxicity. We characterized associations with adverse events and treatment failure/recurrence among adults treated for tuberculosis in Brazil.

METHODS

Participants were followed in Regional Prospective Observational Research in Tuberculosis (RePORT)-Brazil. We included persons with culture-confirmed drug-susceptible pulmonary tuberculosis who started treatment between 2015 and 2019, and who were eligible for pharmacogenetics. Treatment included 2 months of isoniazid, rifampin or rifabutin, pyrazinamide, and ethambutol, then 4 months of isoniazid and rifampin or rifabutin, with 24-month follow-up. Analyses included 43 polymorphisms in 20 genes related to antituberculosis drug hepatotoxicity or pharmacokinetics. Whole exome sequencing was done in a case-control toxicity subset.

RESULTS

Among 903 participants in multivariable genetic association analyses, NAT2 slow acetylator status was associated with increased risk of treatment-related grade 2 or greater adverse events, including hepatotoxicity. Treatment failure/recurrence was more likely among NAT2 rapid acetylators, but not statistically significant at the 5% level. A GSTM1 polymorphism (rs412543) was associated with increased risk of treatment-related adverse events, including hepatotoxicity. SLCO1B1 polymorphisms were associated with increased risk of treatment-related hepatoxicity and treatment failure/recurrence. Polymorphisms in NR1/2 were associated with decreased risk of adverse events and increased risk of failure/recurrence. In whole exome sequencing, hepatotoxicity was associated with a polymorphism in VTI1A , and the genes METTL17 and PRSS57 , but none achieved genome-wide significance.

CONCLUSION

In a clinical cohort representing three regions of Brazil, NAT2 acetylator status was associated with risk for treatment-related adverse events. Additional significant polymorphisms merit investigation in larger study populations, particularly regarding risk of treatment failure/recurrence.

One Step Ahead in Realizing Pharmacogenetics in Low- and Middle-Income Countries: What Should We Do?

Pharmacogenetics is a promising approach in future personalized medicine. This field holds excellent prospects for healthcare quality acceleration. It promotes the transition to the precision medicine era, whereby a health treatment is driven by a deeper understanding of individual characteristics by interpreting the underlying genomic variation. Pharmacogenetics has been developing rapidly since the human genome project. Many pharmacogenetics studies have shown the association between genetic variants and therapy outcomes. Several pharmacogenetics working groups have recommended guidelines for the clinical application of pharmacogenetics. However, the development of pharmacogenetics in low- and middle-income countries (LMICs) is still retarded behind. The problems mainly include clinical evidence, technology, policy and regulation, and human resources. Currently, available genome and drug effect data in LMICs are scarce. Pharmacogenetics development should be escalated with evidence proof through research collaboration across countries. The challenges of pharmacogenetics implementation are discussed comprehensively in this article, along with the prospect of pharmacogenetics-guided personalized medicine in developed countries. Stepwise is expected to help the researchers and stakeholders define the problem that hindered the pharmacogenetics application.

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.

The effect of Polymorphism of the MDR1 (ABCB1) Gene on the Risk of Hepatotoxic Reactions in Patients with Pulmonary Tuberculosis

Currently, a decrease is seen in the effectiveness of treatment in patients with tuberculosis due to the appearance of adverse reactions to anti-tuberculosis drugs. Hepatotoxic reactions play an especially important role in anti-tuberculosis therapy, and phthisiologists often have to deal with the cancellation of a number of anti-tuberculosis drugs. The aim of the study was to investigate the relationship of polymorphic gene variants of xenobiotic biotransformation metabolizing enzymes (NAT2 (590G>A (rs1799930), CYP2E1 (9896C>G (rs2070676), ABCB1 (3435T>C (rs1045642), GSTM1 (E/D), GSTT1 (E/D) with the risk of hepatotoxic reactions in patients with pulmonary tuberculosis. Material and methods. The logistic regression analysis method was used to predict the probability of hepatoxic reactions during specific anti-tuberculosis therapy. Results: 1 statistically significant model was obtained, which reflects the association with hepatotoxic reactions to anti-tuberculosis drugs of the TS genotypes or the TS gene (T allele) ABSV1 (rs1045642). Conclusion. Pharmacogenetic testing used in the study allows us to identify risk groups of patients with pulmonary tuberculosis according to the likelihood of hepatotoxic reactions, which may provide an individualized approach to the treatment of these patients in the future.

Evaluation of the Ethanolic Leaf Extract of Abutilon indicum on Isonicotinic Acid Hydrazide-Induced Proinflammatory Marker Gene Expression Changes

BACKGROUND

Abutilon indicum, widely found in India, Sri Lanka, and parts of America and Malaysia, is renowned for its rich bioactive compounds including alkaloids, flavonoids, and sesquiterpene lactones. Due to its diverse pharmacological potential, it has garnered significant attention in traditional medicine. In particular, the ethanolic leaf extract of Abutilon indicum (ELEAI) has demonstrated anti-inflammatory effects, notably targeting the 5-lipoxygenase enzyme pivotal in inflammatory responses.

OBJECTIVE

This study aimed to elucidate the impact of the ELEAI on proinflammatory marker gene expression induced by isoniazid (INH).

METHODS

A total of 36 rats were systematically divided into six experimental groups. The control group received DMSO orally for the initial 30 days followed by distilled water for the subsequent 30 days. The INH group received a daily dose of INH (30 mg/kg b.w., i.p.) for 30 days and the rats were then sacrificed on day 30. The ELEAI (250 mg/kg) group was administered INH daily for 30 days, followed by daily post-treatment with ELEAI (250 mg/kg) for another 30 days. Similarly, the ELEAI (500 mg/kg) group received INH daily for 30 days, followed by daily post-treatment with ELEAI (500 mg/kg) for another 30 days. The silymarin (SIL) group was given INH daily for 30 days, followed by post-treatment with SIL at a dose of 100 mg/kg body weight daily for the subsequent 30 days. Finally, the ELEAI (500 mg/kg) alone group was administered distilled water orally for the first 30 days and then received ELEAI at a dose of 500 mg/kg b.w. orally once daily for the next 30 days.

RESULTS

Continuous INH exposure for a month led to a pronounced increase in proinflammatory genes like TNF-α, TGF-β, and NF-kB and a decrease in the IkB gene in rat liver tissues. Subsequent treatment with SIL (100 mg/kg) and ELEAI (250 and 500 mg/kg) post-INH exposure resulted in a marked decrease in proinflammatory genes and a surge in IkB expression.

CONCLUSION

The findings suggest that the ELEAI exerts a dose-responsive influence on proinflammatory activities. Notably, A. indicum counteracts inflammation, especially that triggered by bradykinin and prostaglandins. The ELEAI showcases promising therapeutic potential, exhibiting both pro and anti-inflammatory properties and antiproliferative characteristics.

Pharmacogenetics of tuberculosis treatment toxicity and effectiveness in a large Brazilian cohort

Background

Genetic polymorphisms have been associated with risk of anti-tuberculosis treatment toxicity. We characterized associations with adverse events and treatment failure/recurrence among adults treated for tuberculosis in Brazil.

Methods

Participants were followed in Regional Prospective Observational Research in Tuberculosis (RePORT)-Brazil. We included persons with culture-confirmed drug-susceptible pulmonary tuberculosis who started treatment between 2015-2019, and who were evaluable for pharmacogenetics. Treatment included 2 months of isoniazid, rifampin or rifabutin, pyrazinamide, and ethambutol, then 4 months of isoniazid and rifampin or rifabutin, with 24 month follow-up. Analyses included 43 polymorphisms in 20 genes related to anti-tuberculosis drug hepatotoxicity or pharmacokinetics. Whole exome sequencing was done in a case-control toxicity subset.

Results

Among 903 participants in multivariable genetic association analyses, NAT2 slow acetylator status was associated with increased risk of treatment-related grade 2 or greater adverse events, including hepatotoxicity. Treatment failure/recurrence was more likely among NAT2 rapid acetylators, but not statistically significant at the 5% level. A GSTM1 polymorphism (rs412543) was associated with increased risk of treatment-related adverse events, including hepatotoxicity. SLCO1B1 polymorphisms were associated with increased risk of treatment- related hepatoxicity and treatment failure/recurrence. Polymorphisms in NR1/2 were associated with decreased risk of adverse events and increased risk of failure/recurrence. In whole exome sequencing, hepatotoxicity was associated with a polymorphism in VTI1A , and the genes METTL17 and PRSS57 , but none achieved genome-wide significance.

Conclusions

In a clinical cohort representing three regions of Brazil, NAT2 acetylator status was associated with risk for treatment-related adverse events. Additional significant polymorphisms merit investigation in larger study populations.

Association of Cytochrome P450 2E1 and N-Acetyltransferase 2 Genotypes with Serum Isoniazid Level and Anti-Tuberculosis Drug-Induced Hepatotoxicity: A Cross-Sectional Study

Background

Anti-tuberculosis drug-induced hepatotoxicity can result from genetic polymorphism of the isoniazid (INH) metabolizing enzyme. This study aimed to determine the effect of genetic polymorphism of N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1) genes on serum isoniazid level and drug-induced hepatotoxicity.

Methods

A cross-sectional study was conducted on 120 patients (with and without hepatotoxicity) with pulmonary tuberculosis from June 2019 to April 2022 in Tehran (Iran). High-performance liquid chromatography was used to measure the serum concentration of INH and acetylisoniazid (AcINH). NAT2 and CYP2E1 genotypes were determined using polymerase chain reaction and restriction fragment length polymorphism methods. Data were analyzed using SPSS software (version 22.0) with independent two-sample t test, Chi square test, or Fisher's exact test. P<0.05 was considered statistically significant.

Results

A total of 40 patients showed hepatotoxicity. The risk of anti-tuberculosis drug-induced hepatotoxicity was significantly higher in patients who are slow acetylator (SA) phenotype than in rapid or intermediate acetylator (P<0.001). NAT2*4/*4 genotypes were not found in patients with hepatotoxicity. The frequency of NAT2*5 and NAT2*6 haplotypes and serum INH concentration was significantly higher in patients with hepatotoxicity than in those without (P=0.003, P<0.001, and P<0.001, respectively). NAT2*4 haplotype was correlated with protection against hepatotoxicity. A combination of SA and CYP2E1 C1/C1 genotype was significantly associated with hepatotoxicity (P<0.001).

Conclusion

Hepatotoxicity in Iranian patients with tuberculosis was confirmed due to the presence of NAT2 SA polymorphism. Determining NAT2 and CYP2E1 genotypes and/or INH concentration can be a valuable tool to identify patients susceptible to hepatotoxicity.

Human Cytochrome P450 1, 2, 3 Families as Pharmacogenes with Emphases on Their Antimalarial and Antituberculosis Drugs and Prevalent African Alleles

Precision medicine gives individuals tailored medical treatment, with the genotype determining the therapeutic strategy, the appropriate dosage, and the likelihood of benefit or toxicity. Cytochrome P450 (CYP) enzyme families 1, 2, and 3 play a pivotal role in eliminating most drugs. Factors that affect CYP function and expression have a major impact on treatment outcomes. Therefore, polymorphisms of these enzymes result in alleles with diverse enzymatic activity and drug metabolism phenotypes. Africa has the highest CYP genetic diversity and also the highest burden of malaria and tuberculosis, and this review presents current general information on CYP enzymes together with variation data concerning antimalarial and antituberculosis drugs, while focusing on the first three CYP families. Afrocentric alleles such as CYP2A6*17, CYP2A6*23, CYP2A6*25, CYP2A6*28, CYP2B6*6, CYP2B6*18, CYP2C8*2, CYP2C9*5, CYP2C9*8, CYP2C9*9, CYP2C19*9, CYP2C19*13, CYP2C19*15, CYP2D6*2, CYP2D6*17, CYP2D6*29, and CYP3A4*15 are implicated in diverse metabolic phenotypes of different antimalarials such as artesunate, mefloquine, quinine, primaquine, and chloroquine. Moreover, CYP3A4, CYP1A1, CYP2C8, CYP2C18, CYP2C19, CYP2J2, and CYP1B1 are implicated in the metabolism of some second-line antituberculosis drugs such as bedaquiline and linezolid. Drug-drug interactions, induction/inhibition, and enzyme polymorphisms that influence the metabolism of antituberculosis, antimalarial, and other drugs, are explored. Moreover, a mapping of Afrocentric missense mutations to CYP structures and a documentation of their known effects provided structural insights, as understanding the mechanism of action of these enzymes and how the different alleles influence enzyme function is invaluable to the advancement of precision medicine.

NAT2 and CYP2E1 polymorphisms and antituberculosis drug-induced hepatotoxicity in Peruvian patients

BACKGROUND

In Peru, 32,970 people were diagnosed with tuberculosis (TB) in 2019. Although TB treatment is effective, 3.4%-13% is associated with significant adverse drug reactions (ADR), considering drug-induced liver injury (DILI) as the most prevalent. Among the first-line anti-TB drugs, isoniazid (INH) is primarily responsible for the occurrence of DILI. INH is metabolized in the liver by the enzymes N-acetyltransferase-2 (NAT2) and Cytochrome P450 2E1 (CYP2E1). Based on the previous studies, we hypothesized that the interactions between slow CYP2E1 genotype and NAT2 slow acetylators will induce DILI in TB patients.

METHODS

In this cross-sectional study, all 377 participants completed their anti-TB treatment, and we genotyped SNPs: rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931 for NAT2 and rs3813867 and rs2031920 for CYP2E1.

RESULTS

We found that rapid, intermediate, and slow NAT2 acetylator were 15%, 38%, and 47%, respectively, in the general population. Intermediate NAT2 acetylator is the least prevalent among patients with adverse reactions (p = 0.024). We did not confirm our hypothesis, however, we found that the combination of intermediate NAT2 acetylators and CYP2E1 c1/c1 genotype significantly protected (OR = 0.16; p = 0.049) against the development of DILI in our population.

CONCLUSION

We propose that the presence of NAT2 intermediate and CYP2E1 c1/c1 genotype could help in therapeutic drug monitoring, and optimize its therapeutic benefits while minimizing its risk for side effects or toxicity.

Optimizing Antimicrobial Therapy by Integrating Multi-Omics With Pharmacokinetic/Pharmacodynamic Models and Precision Dosing

In the era of “Bad Bugs, No Drugs,” optimizing antibiotic therapy against multi-drug resistant (MDR) pathogens is crucial. Mathematical modelling has been employed to further optimize dosing regimens. These models include mechanism-based PK/PD models, systems-based models, quantitative systems pharmacology (QSP) and population PK models. Quantitative systems pharmacology has significant potential in precision antimicrobial chemotherapy in the clinic. Population PK models have been employed in model-informed precision dosing (MIPD). Several antibiotics require close monitoring and dose adjustments in order to ensure optimal outcomes in patients with infectious diseases. Success or failure of antibiotic therapy is dependent on the patient, antibiotic and bacterium. For some drugs, treatment responses vary greatly between individuals due to genotype and disease characteristics. Thus, for these drugs, tailored dosing is required for successful therapy. With antibiotics, inappropriate dosing such as insufficient dosing may put patients at risk of therapeutic failure which could lead to mortality. Conversely, doses that are too high could lead to toxicities. Hence, precision dosing which customizes doses to individual patients is crucial for antibiotics especially those with a narrow therapeutic index. In this review, we discuss the various strategies in optimizing antimicrobial therapy to address the challenges in the management of infectious diseases and delivering personalized therapy.

Research Progress of Pharmacogenomics in Drug-Induced Liver Injury

Background: Drug-induced liver injury (DILI) is a common and serious adverse drug reaction with insufficient clinical diagnostic strategies and treatment methods. The only clinically well-received method is the Roussel UCLAF Causality Assessment Method scale, which can be applied to both individuals and prospective or retrospective studies. However, in severe cases, patients with DILI still would develop acute liver failure or even death. Pharmacogenomics, a powerful tool to achieve precision medicine, has been used to study the polymorphism of DILI related genes.

Summary: We summarized the pathogenesis of DILI and findings on associated genes and variations with DILI, including but not limited to HLA genes, drug metabolizing enzymes, and transporters genes, and pointed out further fields for DILI related pharmacogenomics study to provide references for DILI clinical diagnosis and treatment.

Key Messages: At present, most of the studies are mainly limited to CGS and GWAS, and there is still a long way to achieve clinical transformation. DNA methylation could be a new consideration, and ethnic differences and special populations also deserve attention.

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 liver injury: Asia Pacific Association of Study of Liver consensus guidelines

Idiosyncratic drug-induced liver injury mimics acute and chronic liver disease. It is under recognized and underrecognised because of the lack of pathognomonic diagnostic serological markers. Its consequences may vary from being asymptomatic to self-limiting illness to severe liver injury leading to acute liver failure. Its incidence is likely to be more common in Asia than other parts of the world, mainly because of hepatotoxicity resulting from the treatment of tuberculosis disease and the ubiquitous use of traditional and complimentary medicines in Asian countries. This APASL consensus guidelines on DILI is a concise account of the various aspects including current evidence-based information on DILI with special emphasis on DILI due to antituberculosis agents and traditional and complementary medicine use in Asia.

Pharmacogenetics of common SNP affecting drug metabolizing enzymes: comparison of allele frequencies between European and Malaysian/Singaporean

Compared to Europe, data on genetic variation in genes transcribing drug metabolizing enzymes among Asian is limited due to ethnic diversity. Here we compare frequencies for clinically relevant single nucleotide polymorphism (SNP) commonly observed in drug metabolizing enzymes between European and Malaysian/Singaporean. Minor allele frequencies (MAF) for the indicated SNPs for European, South Asian and East Asian populations were obtained from the NCBI website (https://www.ncbi.nlm.nih.gov/snp). The SNP prevalence among Malaysian/Singaporean was characterized from gene association studies. Generally, some SNPs in CYP2D6 and CYP2C19 do not show good agreement between the two populations as to the MAF value obtained. CYP2D6*4 tends to be more common among European, whereas CYP2D6*10 is more common in Malays and Chinese among Singaporean. Regardless of different phenotype, MAF of CYP2D6*4 for Indians is similar to that seen by the European. Singaporeans show smaller MAF for CYP2C19*17 but higher CYP2C19*2 frequencies as opposed to European ones. Following growing attention to the contribution of CYP3A4/5, N-acetyltransferases (NAT2), thiopurine methyltransferase (TPMT) and uridine diphosphate glucuronosyltransferases (UGT)2B7 in predicting drug response across Europe, there are limited pharmacogenetics (PGx) studies examining the gene-drug interaction among Malaysian/Singaporean. To better understand the heterogeneity of the drug response, PGx studies for the abovementioned enzymes between ethnics in Malaysian/Singaporean should be identified.

Pharmacogenetics of common SNP affecting drug metabolizing enzymes: comparison of allele frequencies between European and Malaysian/Singaporean

Compared to Europe, data on genetic variation in genes transcribing drug metabolizing enzymes among Asian is limited due to ethnic diversity. Here we compare frequencies for clinically relevant single nucleotide polymorphism (SNP) commonly observed in drug metabolizing enzymes between European and Malaysian/Singaporean. Minor allele frequencies (MAF) for the indicated SNPs for European, South Asian and East Asian populations were obtained from the NCBI website (https://www.ncbi.nlm.nih.gov/snp). The SNP prevalence among Malaysian/Singaporean was characterized from gene association studies. Generally, some SNPs in CYP2D6 and CYP2C19 do not show good agreement between the two populations as to the MAF value obtained. CYP2D6*4 tends to be more common among European, whereas CYP2D6*10 is more common in Malays and Chinese among Singaporean. Regardless of different phenotype, MAF of CYP2D6*4 for Indians is similar to that seen by the European. Singaporeans show smaller MAF for CYP2C19*17 but higher CYP2C19*2 frequencies as opposed to European ones. Following growing attention to the contribution of CYP3A4/5, N-acetyltransferases (NAT2), thiopurine methyltransferase (TPMT) and uridine diphosphate glucuronosyltransferases (UGT)2B7 in predicting drug response across Europe, there are limited pharmacogenetics (PGx) studies examining the gene-drug interaction among Malaysian/Singaporean. To better understand the heterogeneity of the drug response, PGx studies for the abovementioned enzymes between ethnics in Malaysian/Singaporean should be identified.

Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice

Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratory abnormalities to acute liver failure (ALF) and death. The cellular and molecular mechanisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts-neoantigens-that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanistic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.

Variability of the Genes Involved in the Cellular Redox Status and Their Implication in Drug Hypersensitivity Reactions

Adverse drug reactions are a major cause of morbidity and mortality. Of the great diversity of drugs involved in hypersensitivity drug reactions, the most frequent are non-steroidal anti-inflammatory drugs followed by β-lactam antibiotics. The redox status regulates the level of reactive oxygen and nitrogen species (RONS). RONS interplay and modulate the action of diverse biomolecules, such as inflammatory mediators and drugs. In this review, we address the role of the redox status in the initiation, as well as in the resolution of inflammatory processes involved in drug hypersensitivity reactions. We summarize the association findings between drug hypersensitivity reactions and variants in the genes that encode the enzymes related to the redox system such as enzymes related to glutathione: Glutathione S-transferase (GSTM1, GSTP, GSTT1) and glutathione peroxidase (GPX1), thioredoxin reductase (TXNRD1 and TXNRD2), superoxide dismutase (SOD1, SOD2, and SOD3), catalase (CAT), aldo-keto reductase (AKR), and the peroxiredoxin system (PRDX1, PRDX2, PRDX3, PRDX4, PRDX5, PRDX6). Based on current evidence, the most relevant candidate redox genes related to hypersensitivity drug reactions are GSTM1, TXNRD1, SOD1, and SOD2. Increasing the understanding of pharmacogenetics in drug hypersensitivity reactions will contribute to the development of early diagnostic or prognosis tools, and will help to diminish the occurrence and/or the severity of these reactions.

Hepatotoxicity during TB treatment in people with HIV/AIDS related to NAT2 polymorphisms in Pernambuco, Northeast Brazil

INTRODUCTION AND OBJECTIVE

Hepatotoxicity during tuberculosis (TB) treatment is frequent and may be related to the Arylamine N-Acetyltransferase (NAT2) acetylator profile, in which allele frequencies differ according to the population. The aim of this study was to investigate functional polymorphisms in NAT2 associated with the development of hepatotoxicity after initiating treatment for TB in people living with HIV/AIDS (PLWHA) in Pernambuco, Northeast Brazil.

MATERIAL AND METHODS

This was a prospective cohort study that investigated seven single nucleotide polymorphisms located in the NAT2 coding region in 173 PLWHA undergoing TB treatment. Hepatotoxicity was defined as elevated aminotransferase levels and identified as being three times higher than it was before initiating TB treatment, with associated symptoms of hepatitis. A further 80 healthy subjects, without HIV infection or TB were used as a control group. All individuals were genotyped by direct sequencing.

RESULTS

The NAT2*13A and NAT2*6B variant alleles were significantly associated with the development of hepatotoxicity during TB treatment in PLWHA (p<0.05). Individual comparisons between the wild type and each variant genotype revealed that PLWHA with signatures NAT2*13A/NAT2*13A (OR 4.4; CI95% 1.1-18.8; p 0.037) and NAT2*13A/NAT2*6B (OR 4.4; CI95% 1.5-12.7; p 0.005) significantly increased the risk of hepatotoxicity.

CONCLUSION

This study suggests that NAT2*13A and NAT2*6B variant alleles are risk factors for developing hepatotoxicity, and PLWHA with genotypes NAT2*13A/NAT2*13A and NAT2*13A/NAT2*6B should be targeted for specific care to reduce the risk of hepatotoxicity during treatment for tuberculosis.

Pharmacogenetic interactions of rifapentine plus isoniazid with efavirenz or nevirapine

OBJECTIVES

The effect of rifapentine plus isoniazid on efavirenz pharmacokinetics was characterized in AIDS Clinical Trials Group protocol A5279 (NCT01404312). The present analyses characterize pharmacogenetic interactions between these drugs, and with nevirapine.

METHODS

A subset of HIV-positive individuals receiving efavirenz- or nevirapine-containing antiretroviral therapy in A5279 underwent pharmacokinetic evaluations at baseline, and again weeks 2 and 4 after initiating daily rifapentine plus isoniazid. Associations with polymorphisms relevant to efavirenz, nevirapine, isoniazid, and rifapentine pharmacokinetics were assessed.

RESULTS

Of 128 participants, 101 were evaluable for associations with rifapentine and its active 25-desacetyl metabolite, 87 with efavirenz, and 38 with nevirapine. In multivariable analyses, NAT2 slow acetylators had greater week 4 plasma concentrations of rifapentine (P = 2.6 × 10) and 25-desacetyl rifapentine (P = 7.0 × 10) among all participants, and in efavirenz and nevirapine subgroups. NAT2 slow acetylators also had greater plasma efavirenz and nevirapine concentration increases from baseline to week 4, and greater decreases from baseline in clearance. CYP2B6 poor metabolizers had greater efavirenz concentrations at all weeks and greater nevirapine concentrations at baseline. None of 47 additional polymorphisms in 11 genes were significantly associated with pharmacokinetics.

CONCLUSIONS

Among HIV-positive individuals receiving efavirenz or nevirapine, and who then initiated rifapentine plus isoniazid in A5279, NAT2 slow acetylators had greater rifapentine and 25-desacetyl rifapentine concentrations, and greater increases from baseline in plasma efavirenz and nevirapine concentrations. These associations are likely mediated by greater isoniazid exposure in NAT2 slow acetylators.

Case Study 10: A Case to Investigate Acetyl Transferase Kinetics

Major routes of metabolism for marketed drugs are predominately driven by enzyme families such as cytochromes P450 and UDP-glucuronosyltransferases. Less studied conjugative enzymes, like N-acetyltransferases (NATs), are commonly associated with detoxification pathways. However, in the clinic, the high occurrence of NAT polymorphism that leads to slow and fast acetylator phenotypes in patient populations has been linked to toxicity for a multitude of drugs. A key example of this is the observed clinical toxicity in patients who exhibit the slow acetylator phenotype and were treated with isoniazid. Toxicity in patients has led to detailed characterization of the two NAT isoforms and their polymorphic genotypes. Investigation in recombinant enzymes, genotyped hepatocytes, and in vivo transgenic models coupled with acetylator status-driven clinical studies have helped understand the role of NATs in drug development, clinical study design and outcomes, and potential roles in human disease models. The selected case studies herein document NAT enzyme kinetics to explore substrate overlap from two human isoforms, preclinical species considerations, and clinical genotype population concerns.

Genetic Risk Factors in Drug-Induced Liver Injury Due to Isoniazid-Containing Antituberculosis Drug Regimens

Drug-induced liver injury (DILI) is a complication of treatment with antituberculosis (TB) drugs, especially in isoniazid (INH)-containing regimens. To investigate genetic risk factors, we performed a genomewide association study (GWAS) involving anti-TB DILI cases (55 Indian and 70 European) and controls (1,199 Indian and 10,397 European). Most cases were treated with a standard anti-TB drug regimen; all received INH. We imputed single nucleotide polymorphism and HLA genotypes and performed trans-ethnic meta-analysis on GWAS and candidate gene genotypes. GWAS found one significant association (rs117491755) in Europeans only. For HLA, HLA-B*52:01 was significant (meta-analysis odds ratio (OR) 2.67, 95% confidence interval (CI) 1.63-4.37, P = 9.4 × 10^-5 ). For N-acetyltransferase 2 (NAT2), NAT2*5 frequency was lower in cases (OR 0.69, 95% CI 0.57-0.83, P = 0.01). NAT2*6 and NAT2*7 were more common, with homozygotes for NAT2*6 and/or NAT2*7 enriched among cases (OR 1.89, 95% CI 0.84-4.22, P = 0.004). We conclude HLA genotype makes a small contribution to TB drug-related DILI and that the NAT2 contribution is complex, but consistent with previous reports when differences in the metabolic effect of NAT2*5 compared with those of NAT2*6 and NAT2*7 are considered.

Perspective for Precision Medicine for Tuberculosis

Tuberculosis is a bacterial infectious disease that is mainly transmitted from human to human via infectious aerosols. Currently, tuberculosis is the leading cause of death by an infectious disease world-wide. In the past decade, the number of patients affected by tuberculosis has increased by ~20 percent and the emergence of drug-resistant strains of Mycobacterium tuberculosis challenges the goal of elimination of tuberculosis in the near future. For the last 50 years, management of patients with tuberculosis has followed a standardized management approach. This standardization neglects the variation in human susceptibility to infection, immune response, the pharmacokinetics of drugs, and the individual duration of treatment needed to achieve relapse-free cure. Here we propose a package of precision medicine-guided therapies that has the prospect to drive clinical management decisions, based on both host immunity and M. tuberculosis strains genetics. Recently, important scientific discoveries and technological advances have been achieved that provide a perspective for individualized rather than standardized management of patients with tuberculosis. For the individual selection of best medicines and host-directed therapies, personalized drug dosing, and treatment durations, physicians treating patients with tuberculosis will be able to rely on these advances in systems biology and to apply them at the bedside.

Treatment of hepatitis induced by anti-tuberculosis drugs (experimental research)

Introduction: Tuberculosis is a widely spread infection. While treating patients for it, they are given simultaneously and for a long period 5-6 antibacterial drugs, which are, as a rule, bad for the liver. It quite often (up to 20%) causes drug-induced hepatitis. As experimental means of protecting the liver, the following peptides are suggested: chorionic gonadotropin, a recombinant drug of luteinizing hormone – luveris, and oligopeptide drugs: semax and selank.

Materials and Methods: The research was conducted on 104 outbred white male rats weighing 170-220 g. Each group included at least 10 animals. Drug-induced hepatitis was simulated through the combined 21-day administration of isoniazid, rifamycin, and ethanol. Chorionic gonadotropin, luveris, semax and selank, as well as a comparison drug mexidol, were administered once a day during the experiment. Healthy control animals and rats with drug-induced hepatitis were used as comparison groups. For evaluation of the efficiency of administered drugs, the obtained biochemical and histomorphological research data was used.

Results and Discussion: During the experiment, chorionic gonadotropin (ChG), semax and selank showed a greater therapeutic activity than mexidol and luveris. Only in the case of administering ChG, selank and semax, there was parallelism between the restoration of biochemical parameters of blood and histomorphological parameters of the liver. Administering both selank and ChG was also characterized by more active regenerative processes.

Conclusion: Administering ChG, selank and semax to patients with tuberculosis would significantly reduce the number and severity of hepatotoxic reactions.

The role of NAT2 polymorphism and methylation in anti-tuberculosis drug-induced liver injury in Mongolian tuberculosis patients

WHAT IS KNOWN AND OBJECTIVE

Anti-tuberculosis drug-induced liver injury (ATLI) is one of the most significant adverse reactions for this line of therapy. N-acetyltransferase 2 (NAT2) is an important metabolic enzyme involved in drug metabolism and detoxification. Genetic polymorphism and DNA methylation have been proven to be key factors that affect the expression of NAT2. Therefore, the objective of the study was to investigate the relationship between NAT2 gene polymorphism and DNA methylation in the promoter region with ATLI risk in Mongolian tuberculosis patients.

METHODS

Our study is a case-control design. Chi-square test, Mann-Whitney U non-parametric test and Pearson test were all used to analyse existing relationships. The association between NAT2 gene acetylation phenotype and the total methylation of the NAT2 promoter region was analysed by means of binary logistic regression analysis. The general situation of the patients was evaluated by questionnaire, and the NAT2 genotyping of the three major polymorphism loci of gene coding was carried out by a gene sequencing technique. The methylation status of the NAT2 gene promoter region was detected by bisulphite sequencing and mass spectrometry.

RESULT AND DISCUSSION

Our study found that the detection rate of ATLI in Mongolian tuberculosis patients was 27.6%. There were no significant differences in demographic characteristics and living habits amongst the two groups, while significant differences were observed in the polymorphism of the NAT2 genes 481 (rs1799929) and 590 (rs1799930) and the acetylation phenotype. Moreover, the composition and distribution of the NAT2*4/4 and NAT2*4/5 genotypes were found in the two groups. The risk of ATLI in the slow acetylation type was 3.56 times higher than that of the fast acetylation type. Compared with the control group, the CpG5, CpG10, CpG11.12 and total methylation of the NAT2 promoter region in the ATLI group showed a hypermethylated pattern (P < .05). However, on performing binary logistic regression, neither the slow acetylation, intermediate acetylation nor rapid acetylation were found to be associated with ATLI (P > .05). It was found that the total methylation of NAT2 gene promoter region was an independent influencing factor of ATLI in Mongolian tuberculosis patients. With the increase of the total methylation level of NAT2 gene promoter region, the risk of ATLI increased gradually. (OR = 8.371, 95% CI: 2.391 ~ 29.315). CpG1, CpG4, CpG9, CpG10 and CpG11.12 were positively correlated with a total methylation level in the ATLI group.

WHAT IS NEW AND CONCLUSION

The detection rate of ATLI in Mongolian tuberculosis patients was 27.6%, and there were differences in the NAT2 genotypes and acetylated phenotypes. The slow acetylated type was the risk factor for ATLI. Methylation in the promoter region of the NAT2 gene has an effect on the risk of ATLI. After adjusting for the interference of three acetylation types, it was found that the total methylation of the promoter region of NAT2 gene in Mongolian tuberculosis patients is an independent influencing factor of ATLI. Furthermore, there is a moderate to high correlation between some sites and the overall level of methylation.

Drug induced liver injury: East versus West - a systematic review and meta-analysis

Drug induced liver injury (DILI) may be different in the East compared to the West due to differing disease prevalence, prescribing patterns and pharmacogenetic profiles. To review existing literature on causative agents of DILI in the East compared to the West, a comprehensive literature search was performed on electronic databases: MEDLINE/PubMed, Embase, Cochrane Library and China National Knowledge Infrastructure without language restrictions. Studies which involve patients having DILI and reported the frequency of causative agents were included. A random effects model was applied to synthesize the current evidence using prevalence of class-specific and agent-specific causative drugs with 95% confidence intervals. Of 6,914 articles found, 12 showed the distribution of drugs implicated in DILI in the East with a total of 33,294 patients and 16 in the West with a total of 26,069 DILI cases. In the East, the most common agents by class were anti-tuberculosis drugs (26.6%), herbal and alternative medications (25.3%), and antibiotics (15.7%), while in the West, antibiotics (34.9%), cardiovascular agents (17.3%), and non-steroidal anti-inflammatory drugs (12.5%) were the commonest. For individual agents, the most common agents in the East were isoniazid-rifampicin-pyrazinamide (25.4%), phenytoin (3.5%), and cephalosporin (2.9%) while in the West, amoxicillin-potassium clavulanate combination acid (11.3%), nimesulide (6.3%), and ibuprofen (6.1%) were the commonest. There was significant heterogeneity due to variability in single-centre compared to multi-centre studies. Differences in DILI in the East versus the West both in drug classes and individual agents are important for clinicians to recognize.

Management of latent tuberculosis infection in China: Exploring solutions suitable for high-burden countries

China is one of the countries with a high burden of tuberculosis (TB) and latent tuberculosis infection (LTBI). It was recently estimated that China had the highest LTBI burden in the world, with approximately 350 million persons living with the infection. The prevalence of LTBI in China is overestimated by tuberculin skin test (TST) as compared to interferon-gamma release assay (IGRA). A population-based study found that IGRA positivity rates ranged between 13.5% and 19.8%. The annual TB infection rate in the rural population was 1.5% based on persistent positive IGRA results in converters. The development of active TB from LTBI in the general rural population was 0.87 per 100 person-years in the first 2 years among individuals who newly converted to IGRA-positive. TB control in students has been paid more attention by the government, which also improved LTBI management among students in close contact with active TB patients. A 3-month regimen of twice-weekly rifapentine plus isoniazid (3H₂P₂, both with a maximum dose of 600 mg) has been practiced for LTBI treatment in China for years. With respect to LTBI management in populations using immune inhibitors, an expert consensus on TB prevention and management in tumor necrosis factor antagonist application was published in 2013 in China. In order to achieve the global goals of the End TB Strategy, China needs innovative ideas and technologies to reduce the TB incidence by management of LTBI, such as the identification of populations for LTBI testing and treatment, selecting and developing reliable LTBI tests, exploring safe and effective preventive treatment tools, and establishing a set of optimized LTBI management systems.

GSTM1 and GSTT1 genetic polymorphisms and their association with antituberculosis drug-induced liver injury

Antituberculosis (anti-TB) drugs are the most common cause of drug-induced liver injury (DILI). There are numerous studies revealing the associations between the polymorphisms of pharmacogenes and the risk of anti-TB DILI (ATDILI). In the present study, relevant studies regarding the pharmacogenes associated with ATDILI were systematically searched in PubMed and Scopus. A total of 24 genes associated with ATDILI were reported on and the top five reported genes in terms of frequency were revealed to be N-acetyltransferase 2, cytochrome P450 family 2 subfamily E member 1, glutathione S-transferases [glutathione S-transferase mu 1 (GSTM1) and glutathione S-transferase theta 1 (GSTT1)] and solute carrier organic anion transporter family member 1B1. As ATDILI may be the result of direct and indirect interactions, the encoded proteins were further analysed using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) to observe the protein-protein interactions and the associations amongst these proteins. The results suggested that only GSTT1 and GSTM1 were central proteins associated with all the other analysed proteins. Therefore, the association between GSTT1 or GSTM1 and the risk of developing ATDILI were further analysed. The results revealed that a GSTM1 deletion genotype was significantly associated with risk of ATDILI [odds ratio (OR), 1.28; 95% confidence interval (CI), 1.08-1.51; P=0.004], whereas the GSTT1 deletion genotype and GSTM1/GSTT1 dual-deletion genotype were not significantly associated with risk of ATDILI. Subgroup analysis based on ethnicity was performed and the results demonstrated a significant association between GSTM1 and ATDILI in South Asian individuals (OR, 1.48; 95% CI, 1.12-1.95; P=0.005), which has not been reported previously, to the best of our knowledge. In conclusion, GSTM1 was associated with ATDILI in South Asian individuals.

Correlation between lncRNA AC079767.4 variants and liver injury from antituberculosis treatment in West China

Antituberculosis drug-induced adverse drug reactions (ADRs) has been attached the increasing attention currently. And many host genetic determinants of ADRs have been identified. However, the possible relationship between long non-coding RNA (lncRNA) and ADRs is little investigated in tuberculosis (TB). We conducted a prospective survey and comprehensively collected the information of diverse ADRs during antituberculosis therapy. Next, we analyzed whether single nucleotide polymorphisms (SNPs) within lncRNA AC079767.4 gene are associated with ADRs development of patients with TB. Our results showed that the overall occurrence rate of ADRs due to TB treatment was 16.39% (70/427), of which the anti-tuberculosis drug-induced hepatotoxicity (ATDH) constituted the most common adverse events with prevalence rate of 12.88% (55/427). Notably, TB patients carrying T allele-containing genotypes in rs1055229 locus potentially presented a greater risk (1.85-fold, 95%CI = 1.04-3.28) for developing ATDH when compared with those CC genotype carriers, 17.28% versus. 10.19%, respectively, with the age- and gender -adjusted p-value of 0.035. Our data suggest that the ADRs exhibit serious morbidity in TB patients in West China, and for the first time we show that the AC079767.4 rs1055229 is a potential genetic risk component for ATDH development. Further studies on larger population and other ethnic groups are needed to confirm our results.

Selank and semax as potential hepatoprotectors in medical treatment of tuberculosis

Introduction: Drug-induced hepatitis is common in clinical practice. This problem is particularly relevant in the treatment of tuberculous infection, because for this purpose, up to 5–6 hepatotoxic drugs are used simultaneously for a long time, which often (in 15–20% of cases) leads to medical liver lesion. To protect the liver, Semax and Selank are offered – drugs of regulatory peptides group.

Materials and Methods: The research was conducted on 96 outbred white male rats weighing 180–220 g. The experimental group included about 10 animals. Drug-induced hepatitis was simulated through the combined 21-day administration of isoniazid, rifampicin and ethanol. Semax and Selank, as well as Essentiale N and Mexidol (comparison drugs) were administered once a day during the experiment. Healthy control animals with experimental hepatitis were used for comparison. Subsequently, the obtained biochemical and histomorphological parameters were evaluated.

Results and Discussion: In the experiment, Semax and Selank showed a greater therapeutic activity than the recognized hepatoprotectors – Essentiale and Mexidol. Only in the case of administering Selank and Semax, there was parallelism between the restoration of biochemical parameters of blood and histomorphological parameters of the liver. Selank was also characterized by an increased activity of regenerative processes.

Conclusion: Administering Selank and Semax to patients with tuberculosis would significantly reduce the number and severity of hepatotoxic reactions.

Association of genetic polymorphisms of CYP2E1, NAT2, GST and SLCO1B1 with the risk of anti-tuberculosis drug-induced liver injury: a systematic review and meta-analysis

OBJECTIVES

The objective of this study was to investigate the association between genetic polymorphisms of N-acetyltransferase 2 (NAT2), cytochrome P450 2E1 (CYP2E1), glutathione S-transferase (GST) and solute carrier organic anion transporter family member 1B1 (SLCO1B1) and the risk of anti-tuberculosis drug-induced liver injury (ATDILI).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed, Embase, Web of Science and Cochrane Reviews databases were searched through April 2019.

ELIGIBILITY CRITERIA

We included case-control or cohort studies investigating an association between NAT2, CYP2E1, GST or SLCO1B1 polymorphisms and the ATDILI risk in patients with tuberculosis.

DATA EXTRACTION AND SYNTHESIS

Three authors screened articles, extracted data and assessed study quality. The strength of association was evaluated for each gene using the pooled OR with a 95% CI based on the fixed-effects or random-effects model. Sensitivity analysis was performed to confirm the reliability and robustness of the results.

RESULTS

Fifty-four studies were included in this analysis (n=26 for CYP2E1, n=35 for NAT2, n=19 for GST, n=4 for SLCO1B1). The risk of ATDILI was significantly increased with the following genotypes: CYP2E1 RsaI/PstI c1/c1 (OR=1.39, 95% CI 1.06 to 1.83), NAT2 slow acetylator (OR=3.30, 95% CI 2.65 to 4.11) and GSTM1 null (OR=1.30, 95% CI 1.12 to 1.52). No significant association with ATDILI was found for the genetic polymorphisms of CYP2E1 DraI, GSTT1, GSTM1/GSTT1, SLCO1B1 388A>G and SLCO1B1 521T>C (p>0.05).

CONCLUSIONS

ATDILI is more likely to occur in patients with NAT2 slow acetylator genotype, CYP2E1 RsaI/PstI c1/c1 genotype and GSTM1 null genotype. Close monitoring may be warranted for patients with these genotypes.

Genomewide Association Study Confirming the Association of NAT2 with Susceptibility to Antituberculosis Drug-Induced Liver Injury in Thai Patients

Antituberculosis drug-induced liver injury (ATDILI) is a common side effect leading to tuberculosis (TB) treatment disruption. The mechanism of the disease remains poorly understood. We conducted a genomewide association study (GWAS) to investigate all possible genetic factors of ATDILI in Thai patients. This study was carried out in Thai TB patients, including 79 ATDILI cases and 239 tolerant controls from our network hospitals in Thailand. Nearly 1 million single-nucleotide polymorphisms (SNPs) were genotyped across the whole genome using an Illumina OmniExpress Exome BeadChip array. In the discovery stage, we identified strong association signals on chromosome 8 originating from the N-acetyltransferase (NAT2) region. The A allele of rs1495741, the top SNP in the intergenic region of NAT2 and PSD3 (14 kb from NAT2), was significantly associated with ATDILI (recessive model, odds ratio of 6.01 [95% confidence interval, 3.42 to 10.57]; P = 6.86E-11). This particular SNP was reported as a tag SNP for NAT2 inferred phenotypes. The AA, AG, and GG genotypes represented NAT2 slow acetylators, intermediate acetylators, and fast acetylators, respectively. The tag SNP genotypes demonstrated a concordance rate of 94.98% with NAT2 acetylator phenotypes. This GWAS shows that NAT2 is the most important risk factor for ATDILI in the Thai population.

N-acetyltransferase 2 polymorphism and acetylation profiles in Buginese ethnics of Indonesia

BACKGROUND

N-acetyltransferase 2 (NAT2) is a key enzyme involved in the phase II metabolism of aromatic amines and heterocyclic aromatic amines present in a wide range of xenobiotics. The aim of this study was to investigate the NAT2 polymorphism in the Buginese ethnic group of Indonesia to determine the frequency of NAT2 alleles in this population.

RESULTS

We found six haplotypes consisting of six single-nucleotide polymorphisms and 12 NAT2 genotype variations. NAT2*6A haplotype (42%) showed the highest frequency, followed by NAT2*4 (33%), NAT2*7B (15%), NAT2*5B (5%), NAT2*12A (3%), and NAT2*13 (2%). In terms of phenotypes, the Buginese population comprised 18% rapid acetylators, 40% intermediate acetylators, and 42% slow acetylators.

CONCLUSION

We confirmed the high-frequency slow acetylator phenotype in the Buginese population. The NAT2*6A/*6A genotype was the most frequent slow acetylator genotype, followed by NAT2*6A/*7B. The pattern of NAT2 alleles of Buginese is similar to Southeast Asian populations but not Northeast Asian populations. However, the slow acetylator frequencies in the Buginese population were higher than those in Northeast Asian populations and lower than those in Caucasians and some American populations.

EASL Clinical Practice Guidelines: Drug-induced liver injury

Idiosyncratic (unpredictable) drug-induced liver injury is one of the most challenging liver disorders faced by hepatologists, because of the myriad of drugs used in clinical practice, available herbs and dietary supplements with hepatotoxic potential, the ability of the condition to present with a variety of clinical and pathological phenotypes and the current absence of specific biomarkers. This makes the diagnosis of drug-induced liver injury an uncertain process, requiring a high degree of awareness of the condition and the careful exclusion of alternative aetiologies of liver disease. Idiosyncratic hepatotoxicity can be severe, leading to a particularly serious variety of acute liver failure for which no effective therapy has yet been developed. These Clinical Practice Guidelines summarize the available evidence on risk factors, diagnosis, management and risk minimization strategies for drug-induced liver jury.

NAT2 variants and toxicity related to anti-tuberculosis agents: a systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) patients receiving anti-tuberculosis treatment may experience serious adverse drug reactions (ADRs) such as hepatotoxicity. Variants of the N-acetyltransferase 2 (NAT2) gene may increase the risk of experiencing such toxicity events.

OBJECTIVE

To provide a comprehensive evaluation of the evidence base for associations between NAT2 variants and anti-tuberculosis drug-related toxicity.

METHOD

This was a systematic review and meta-analysis. We searched for studies in Medline, PubMed, EMBASE, BIOSIS and Web of Science. We included data from 41 articles (39 distinct cohorts of patients). We pooled effect estimates for each genotype on each outcome using meta-analyses stratified by country.

RESULTS

We assessed the quality of the included studies, which was variable, with many areas of concern. Slow/intermediate NAT2 acetylators were statistically significantly more likely to experience hepatotoxicity than rapid acetylators (OR 1.59, 95%CI 1.26-2.01). Heterogeneity was not detected in the overall pooled analysis (I² = 0%). NAT2 acetylator status was significantly associated with the likelihood of experiencing anti-tuberculosis drug-related hepatotoxicity.

CONCLUSION

We encountered several challenges in performing robust syntheses of data from pharmacogenetic studies, and we outline recommendations for the future reporting of pharmacogenetic studies to enable high-quality systematic reviews and meta-analyses to be performed.

The changing epidemiology of liver diseases in the Asia-Pacific region

This Review presents current epidemiological trends of the most common liver diseases in Asia-Pacific countries. Hepatitis B virus (HBV) remains the primary cause of cirrhosis; despite declining prevalence in most Asian nations, this virus still poses a severe threat in some territories and regions. Mortality resulting from HBV infection is declining as a result of preventive measures and antiviral treatments. The epidemiological transition of hepatitis C virus (HCV) infection has varied in the region in the past few decades, but the medical burden of infection and the prevalence of its related cancers are increasing. The lack of licensed HCV vaccines highlights the need for novel treatment strategies. The prevalence of nonalcoholic fatty liver disease (NAFLD) has risen in the past decade, mostly owing to increasingly urbanized lifestyles and dietary changes. Alternative herbal medicine and dietary supplements are major causes of drug-induced liver injury (DILI) in some countries. Complications arising from these chronic liver diseases, including cirrhosis and liver cancer, are therefore emerging threats in the Asia-Pacific region. Key strategies to control these liver diseases include monitoring of at-risk populations, implementation of national guidelines and increasing public and physician awareness, in concert with improving access to health care.

Short-course regimens of rifapentine plus isoniazid to treat latent tuberculosis infection in older Chinese patients: a randomised controlled study

Latent tuberculosis infection (LTBI) management is now a critical component of the World Health Organization's End TB Strategy.In this randomised controlled trial (Chinese Clinical Trial Registry identifier ChiCTR-IOR-15007202), two short-course regimens with rifapentine plus isoniazid (a 3-month once-weekly regimen and a 2-month twice-weekly regimen) were initially designed to be evaluated for rural residents aged 50-69 years with LTBI in China.Due to the increasingly rapid growth and unexpected high frequency of adverse effects, the treatments were terminated early (after 8 weeks for the once-weekly regimen and after 6 weeks for the twice-weekly regimen). In the modified intention-to-treat analysis on the completed doses, the cumulative rate of active disease during 2 years of follow-up was 1.21% (14 out of 1155) in the untreated controls, 0.78% (10 out of 1284) in the group that received the 8-week once-weekly regimen and 0.46% (six out of 1299) in the group that received the 6-week twice-weekly regimen. The risk of active disease was decreased, with an adjusted hazard ratio of 0.63 (95% CI 0.27-1.43) and 0.41 (95% CI 0.15-1.09) for the treatments, respectively. No significant difference was found in the occurrence of hepatotoxicity (1.02% (13 out of 1279) versus 1.17% (15 out of 1279); p=0.704).The short regimens tested must be used with caution among the elderly because of the high rates of adverse effects. Further work is necessary to test the ultrashort regimens in younger people with LTBI.

Building capacity for advances in tuberculosis research; proceedings of the third RePORT international meeting

RePORT International is a global network of research sites in India, Brazil, Indonesia, South Africa, China, and the Philippines dedicated to collaborative tuberculosis research in the context of HIV. A standardized research protocol (the Common Protocol) guides the enrollment of participants with active pulmonary tuberculosis and contacts into observational cohorts. The establishment of harmonized clinical data and bio-repositories will allow cutting-edge, large-scale advances in the understanding of tuberculosis, including identification of novel biomarkers for progression to active tuberculosis and relapse after treatment. The RePORT International infrastructure aims to support research capacity development through enabling globally-diverse collaborations. To that end, representatives from the RePORT International network sites, funding agencies, and other stakeholders gathered together in Brazil in September 2017 to present updates on relevant research findings and discuss ideas for collaboration. Presenters emphasized research involving biomarker identification for incipient tuberculosis, host immunity and pharmacogenomics, co-morbidities such as HIV and type 2 diabetes mellitus, and tuberculosis transmission in vulnerable and high-risk populations. Currently, 962 active TB participants and 670 household contacts have contributed blood, sputum, urine and microbes to in-country biorepositories. Cross-consortium collaborations have begun sharing data and specimens to analyze molecular and cytokine predictive patterns.

CYP genetic variants and toxicity related to anti-tubercular agents: a systematic review and meta-analysis

BACKGROUND

Treatment with anti-tuberculosis drugs may cause patients to experience serious adverse effects. Genetic factors, such as polymorphisms of CYP genes, may increase the likelihood of a patient experiencing such adverse drug reactions. In this systematic review and meta-analysis, we synthesised evidence for associations between CYP genetic variants and anti-tuberculosis drug-related toxicity outcomes.

METHODS

We searched MEDLINE, PubMed, EMBASE, BIOSIS and Web of Science to identify relevant studies. We performed meta-analyses to obtain an effect estimate for each genetic variant on each outcome, and stratified all analyses by country. We qualitatively assessed the methodological quality of the included studies.

RESULTS

We included data from 28 distinct cohorts of patients in the review. We identified many areas of concern with regard to the quality of included studies. Patients with homozygous mutant-type or heterozygous genotype at the CYP2E1 RsaI polymorphism were significantly less likely to experience hepatotoxicity than patients with homozygous wild-type genotype (odds ratio [OR] = 0.75, 95% confidence interval [CI] 0.56-1.00; p = 0.047, I2 = 58.2%). No significant differences were observed for the CYP2E1 DraI and PstI polymorphisms. For the 96-bp deletion-insertion single-nucleotide polymorphism (SNP) of the CYP2E1 gene, homozygous mutant-type significantly increased hepatotoxicity risk compared with homozygous wild-type (OR = 8.20, 95% CI 1.38-48.68, I2 = 0%); no significant difference was observed for heterozygous genotype compared with homozygous wild-type (OR = 0.77, 95% CI 0.19-3.21, I2 = 0%).

CONCLUSIONS

Generally, we identified that coverage of the association between SNPs of CYP genes and anti-tuberculosis drug-related toxicity outcomes is incomplete. We observed significant associations between the RsaI and 96-bp deletion-insertion SNPs of the CYP2E1 gene and anti-tuberculosis drug-related hepatotoxicity. We were unable to comment on the impact of ethnicity on the investigated associations, as information on participants' ethnicity was sparsely reported in the included studies.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42017068448.

Oxidative Stress and First-Line Antituberculosis Drug-Induced Hepatotoxicity

Hepatotoxicity induced by antituberculosis drugs is a serious adverse reaction with significant morbidity and even, rarely, mortality. This form of toxicity potentially impacts the treatment outcome of tuberculosis in some patients. Covering only first-line antituberculosis drugs, this review addresses whether and how oxidative stress and, more broadly, disturbance in redox homeostasis alongside mitochondrial dysfunction may contribute to the hepatotoxicity induced by them. Risk factors for such toxicity that have been identified, in addition to genetic factors, principally include old age, malnutrition, alcoholism, chronic hepatitis C and chronic hepatitis B infection, HIV infection, and preexisting liver disease. Importantly, these comorbid conditions are associated with oxidative stress. Thus, the shared pathogenetic mechanism(s) for liver injury might be in operation due to disease-drug interaction. Our current ability to predict, prevent, or treat hepatotoxicity (other than removing potentially hepatotoxic drugs) remains limited. More translational research to unravel the pathogenesis, inclusive of the underlying molecular basis, regarding antituberculosis drug-induced hepatotoxicity is needed, and so is clinical research pertaining to the advances in therapy with antioxidants and drugs related to antioxidants, especially those for management of mitochondrial dysfunction. The role of pharmacogenetics in the clinical management of drug-induced hepatotoxicity also likely merits further evaluation.

Genetic Variations Associated with Anti-Tuberculosis Drug-Induced Liver Injury

Purpose of this Review

In order to combat the development of drug resistance, the clinical treatment of tuberculosis requires the combined use of several anti-tuberculosis (anti-TB) drugs, including isoniazid and rifampicin. Combinational treatment approaches are suggested by the World Health Organization (WHO) and are widely accepted throughout the world. Unfortunately, a major side effect of the treatment is the development of anti-tuberculosis drug-induced liver injury (AT-DILI). Many factors contribute to isoniazid- and rifampicin-mediated AT-DILI and genetic variations are among the most common factors. The purpose of this review is to provide information on genetic variations associated with isoniazid- and rifampicin-mediated AT-DILI.

Recent Findings

The genetic variations associated with AT-DILI have been identified in the genomic regions within or near genes encoding proteins in the following pathways: drug metabolizing enzymes (NAT2, CYP2E1, and GSTs), accumulation of bile acids, lipids, and heme metabolites (CYP7A1, BSEP, UGTs, and PXR), immune adaptation (HLAs and TNF-α), and oxidant challenge (TXNRD1, SOD1, BACH1, and MAFK).

Summary

The information summarized in this review considers the genetic bases of risk factors contributing to AT-DILI and provides information that may help for future studies. Some of the implicated genetic variations can be used in the design of genetic tests and serve as biomarkers for the prediction of isoniazid- and rifampicin-mediated AT-DILI risk in personalized medicine.

Models of Drug Induced Liver Injury (DILI) - Current Issues and Future Perspectives

BACKGROUND

Drug-induced Liver Injury (DILI) is an important cause of acute liver failure cases in the United States, and remains a common cause of withdrawal of drugs in both preclinical and clinical phases.

METHODS

A structured search of bibliographic databases - Web of Science Core Collection, Scopus and Medline for peer-reviewed articles on models of DILI was performed. The reference lists of relevant studies was prepared and a citation search for the included studies was carried out. In addition, the characteristics of screened studies were described.

RESULTS

One hundred and six articles about the existing knowledge of appropriate models to study DILI in vitro and in vivo with special focus on hepatic cell models, variations of 3D co-cultures, animal models, databases and predictive modeling and translational biomarkers developed to understand the mechanisms and pathophysiology of DILI are described.

CONCLUSION

Besides descriptions of current applications of existing modeling systems, associated advantages and limitations of each modeling system and future directions for research development are discussed as well.

Influence of genetic variants on toxicity to anti-tubercular agents: a systematic review and meta-analysis (protocol)

BACKGROUND

Tuberculosis patients receiving anti-tuberculosis treatment may experience serious adverse drug reactions, such as hepatotoxicity. Genetic risk factors, such as polymorphisms of the NAT2, CYP2E1 and GSTM1 genes, may increase the risk of experiencing such toxicity events. Many pharmacogenetic studies have investigated the association between genetic variants and anti-tuberculosis drug-related toxicity events, and several meta-analyses have synthesised data from these studies, although conclusions from these meta-analyses are conflicting. Many meta-analyses also have serious methodological limitations, such as applying restrictive inclusion criteria, or not assessing the quality of included studies. Most also only consider hepatotoxicity outcomes and specific genetic variants. The purpose of this systematic review and meta-analysis is to give a comprehensive evaluation of the evidence base for associations between any genetic variant and anti-tuberculosis drug-related toxicity.

METHODS

We will search for studies in MEDLINE, EMBASE, BIOSIS and Web of Science. We will also hand search reference lists from relevant studies and contact experts in the field. We will include cohort studies, case-control studies and randomised controlled trials that recruited patients with tuberculosis who were either already established on anti-tuberculosis treatment or were commencing treatment and who were genotyped to investigate the effect of genetic variants on any anti-tuberculosis drug-related toxicity outcome. One author will screen abstracts to identify potentially relevant studies and will then obtain the full text for each potentially relevant study in order to assess eligibility. At each of these stages, a second author will independently screen/assess 10% of studies. Two authors will independently extract data and assess the quality of studies using a pre-piloted data extraction form. If appropriate, we will pool estimates of effect for each genotype on each outcome using meta-analyses stratified by ethnicity.

DISCUSSION

Our review and meta-analysis will update and add to the existing research in this field. By not restricting the scope of the review to a specific drug, genetic variant, or toxicity outcome, we hope to synthesise data for associations between genetic variants and anti-tuberculosis drug-related toxicity outcomes that have previously not been summarised in systematic reviews, and consequently, add to the knowledge base of the pharmacogenetics of anti-tuberculosis drugs.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017068448.

Clinical Pharmacogenetic Testing and Application: Laboratory Medicine Clinical Practice Guidelines

Pharmacogenetic testing for clinical applications is steadily increasing. Correct and adequate use of pharmacogenetic tests is important to reduce unnecessary medical costs and adverse patient outcomes. This document contains recommended pharmacogenetic testing guidelines for clinical application, interpretation, and result reporting through a literature review and evidence-based expert opinions for the clinical pharmacogenetic testing covered by public medical insurance in Korea. This document aims to improve the utility of pharmacogenetic testing in routine clinical settings.

Baseline HBV load increases the risk of anti-tuberculous drug-induced hepatitis flares in patients with tuberculosis

Hepatitis associated anti-tuberculous treatment (HATT) has been a main obstacle in managing patients co-infected with Mycobacterium tuberculosis and hepatitis B virus (HBV). Therefore, we evaluated the factors related to the severity of adverse effects during HATT, especially those associated with liver failure. A retrospective study was carried out at Tongji Hospital from 2007 to 2012. Increases in serum transaminase levels of >3, 5, and 10 times the upper limit of normal (ULN) were used to define liver damage as mild, moderate, and severe, respectively. Patients with elevated total bilirubin (TBil) levels that were more than 10 times the ULN (>171 μmol/L) with or without decreased (<40%) prothrombin activity (PTA) were diagnosed with liver failure. A cohort of 87 patients was analyzed. The incidence of liver damage and liver failure was 59.8% (n=52) and 25.3% (n=22), respectively. The following variables were correlated with the severity of hepatotoxicity: albumin (ALB) levels, PTA, platelet counts (PLT), and the use of antiretroviral therapies (P<0.05). Hypo-proteinemia and antiretroviral therapy were significantly associated with liver failure, and high viral loads were a significant risk factor with an odds ratio (OR) of 2.066. Judicious follow-up of clinical conditions, liver function tests, and coagulation function, especially in patients with high HBV loads and hypoalbuminemia is recommended. It may be advisable to reconsider the use of antiviral drugs failure during the course of anti-tuberculous treatment of HBV infection patients to avoid the occurrence of furious liver failure.

Hepatic and Intra-abdominal Tuberculosis: 2016 Update

Mycobacterium tuberculosis (TB) infection affects nearly 10 million people a year and causes 1.5 million deaths. TB is common in the immunosuppressed population with 12 % of all new diagnoses occurring in human immune deficiency virus (HIV)-positive patients. Extra-pulmonary TB occurs in 12 % of patients with active TB infection of which 3.5 % is hepatobiliary and 6-38 % is intra-abdominal. Hepatobiliary and intra-abdominal TB can present with a myriad of non-specific symptoms, and therefore, diagnosis requires a high level of suspicion. Accurate and rapid diagnosis requires a multidisciplinary team (MDT) approach using radiology, interventional radiology, surgery and pathology services. Treatment of TB is predominantly medical, yet surgery plays an important role in managing the complications of hepatobiliary and intra-abdominal TB.

Isoniazid metabolism and hepatotoxicity

Isoniazid (INH) is highly effective for the management of tuberculosis. However, it can cause liver injury and even liver failure. INH metabolism has been thought to be associated with INH-induced liver injury. This review summarized the metabolic pathways of INH and discussed their associations with INH-induced liver injury.