Association of NAT2, GST and CYP2E1 polymorphisms and anti-tuberculosis drug-induced hepatotoxicity

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.

Alcohol consumption as a risk factor for anti-tuberculosis drug induced liver injury: A systematic review and meta-analysis

BACKGROUND

Tuberculosis (TB) is a major infectious disease in the world, and liver injury caused by anti-tuberculosis (ATTB) drugs is an important reason for reduced patient compliance with ATTB treatment. At present, there is controversy over the role of alcohol consumption in ATTB drugs induced liver injury (ATDILI).

METHODS

All data on alcohol consumption and ATDILI were collected from PubMed, Web of Science, Scopus and Embase databases from inception to April 2023. Odds ratio (OR) and 95 % confidence interval (95 % CI) were used for statistical analysis, and Begg test and Egger test were used to evaluate publication bias.

RESULTS

A total of 1152 literatures were reviewed, and 53 literatures were included for systematic review and meta-analysis. Studies have found that alcohol consumption increases the risk of ATDILI (OR: 1.55; 95 % CI: 1.19-2.04). And an increased risk of ATDILI was found in both the alcoholic and non-alcoholic subgroups. The Begg test and Egger test showed no publication bias.

CONCLUSION

Alcohol consumption is a risk factor for ATDILI in TB patients on treatment. While on ATTB treatment, patients need to reduce alcohol consumption. More research is needed to assess the link between alcohol consumption and ATDILI.

Incidence and risk factors of antituberculosis drug-induced liver injury in India: A systematic review and meta-analysis

BACKGROUND

Antituberculosis drug-induced liver injury (ATDILI) is a significant problem of tuberculosis treatment. This systematic review and meta‑analysis aimed at evaluating the incidence and risk factors of ATDILI in adult patients with tuberculosis in India.

METHODS

Five electronic databases were searched comprehensively for studies on Indian adult patients with tuberculosis investigating the incidence and/or risk factors of ATDILI. The relevant data was pooled in a random or fixed-effect model to calculate the pooled incidence with a 95% confidence interval (CI), standardized mean difference (MD) or odds ratio (OR).

RESULTS

Following the screening of 3221 records, 43 studies with 12,041 tuberculosis patients were finally included. Based on the random effect model, the pooled incidence of ATDILI was 12.6% (95% CI, 9.9-15.3%, p < 0.001, I2 = 95.1%). The pooled incidence was higher in patients with daily treatment regimen compared to the thrice weekly regimen (16.5% vs. 3.5%). The concurrent hepatitis B or C infection, alcohol consumption and underlying chronic liver disease were associated with high incidence of ATDILI. The pooled incidence of acute liver failure (ALF) among ATDILI patients was 6.78% (95% CI 3.9-9.5%). Female gender (OR 1.24), older age (MD 0.26), lean body mass index (OR 3.8), hypoalbuminemia (OR 3.09), N-acetyltransferase slow acetylator genotypes (OR 2.3) and glutathione S-transferases M null mutation (OR 1.6) were found to be associated with an increased risk of ATDILI. The pooled mortality rate of ATDILI patients was 1.72% (95% CI 0.4-3.0%) overall and 71.8% (95% CI 49.3-94.2%) in case of ALF.

CONCLUSION

Overall, 12.6% patients of tuberculosis in India developed ATDILI when combination of first-line antituberculosis drugs was used. An average of 7% of ATDILI patients progressed to ALF which had a high mortality rate. Older age, female, poor nutritional status and some genetic polymorphisms were identified as significant risk factors.

Drug-induced hepatotoxicity and association with slow acetylation variants NAT2*5 and NAT2*6 in Cameroonian patients with tuberculosis and HIV co-infection

BACKGROUND

Human immunodeficiency virus (HIV) and tuberculosis (TB) are major contributors to morbidity and mortality in sub-Saharan Africa including Cameroon. Pharmacogenetic variants could serve as predictors of drug-induced hepatotoxicity (DIH), in patients with TB co-infected with HIV. We evaluated the occurrence of DIH and pharmacogenetic variants in Cameroonian patients.

METHODS

Treatment-naïve patients with HIV, TB or TB/HIV co-infection were recruited at three hospitals in Cameroon, between September 2018 and November 2019. Appropriate treatment was initiated, and patients followed up for 12 weeks to assess DIH. Pharmacogenetic variants were assessed by allele discrimination TaqMan SNP assays.

RESULTS

Of the 141 treatment naïve patients, the overall incidence of DIH was 38% (53/141). The highest incidence of DIH, 52% (32/61), was observed among HIV patients. Of 32 pharmacogenetic variants, the slow acetylation variants NAT2*5 was associated with a decreased risk of DIH (OR: 0.4; 95%CI: 0.17-0.96; p = 0.038), while NAT2*6 was found to be associated with an increased risk of DIH (OR: 4.2; 95%CI: 1.1-15.2; p = 0.017) among patients treated for TB. Up to 15 SNPs differed in ≥ 5% of allele frequencies among African populations, while 25 SNPs differed in ≥ 5% of the allele frequencies among non-African populations, respectively.

CONCLUSIONS

DIH is an important clinical problem in African patients with TB and HIV. The NAT2*5 and NAT2*6 variants were found to be associated with DIH in the Cameroonian population. Prior screening for the slow acetylation variants NAT2*5 and NAT2*6 may prevent DIH in TB and HIV-coinfected patients.

Formation of potentially toxic metabolites of drugs in reactions catalyzed by human drug-metabolizing enzymes

Data are presented on the formation of potentially toxic metabolites of drugs that are substrates of human drug metabolizing enzymes. The tabular data lists the formation of potentially toxic/reactive products. The data were obtained from in vitro experiments and showed that the oxidative reactions predominate (with 96% of the total potential toxication reactions). Reductive reactions (e.g., reduction of nitro to amino group and reductive dehalogenation) participate to the extent of 4%. Of the enzymes, cytochrome P450 (P450, CYP) enzymes catalyzed 72% of the reactions, myeloperoxidase (MPO) 7%, flavin-containing monooxygenase (FMO) 3%, aldehyde oxidase (AOX) 4%, sulfotransferase (SULT) 5%, and a group of minor participating enzymes to the extent of 9%. Within the P450 Superfamily, P450 Subfamily 3A (P450 3A4 and 3A5) participates to the extent of 27% and the Subfamily 2C (P450 2C9 and P450 2C19) to the extent of 16%, together catalyzing 43% of the reactions, followed by P450 Subfamily 1A (P450 1A1 and P450 1A2) with 15%. The P450 2D6 enzyme participated in an extent of 8%, P450 2E1 in 10%, and P450 2B6 in 6% of the reactions. All other enzymes participate to the extent of 14%. The data show that, of the human enzymes analyzed, P450 enzymes were dominant in catalyzing potential toxication reactions of drugs and their metabolites, with the major role assigned to the P450 Subfamily 3A and significant participation of the P450 Subfamilies 2C and 1A, plus the 2D6, 2E1 and 2B6 enzymes contributing. Selected examples of drugs that are activated or proposed to form toxic species are discussed.

Lagerstroemia speciosa Pers. (Lythraceae) Ethanolic Extract Attenuates Isoniazid-Induced Oxidative Stress and Hepatic Inflammation in Rats

Background Drug-induced liver injury is a common cause of acute liver failure. Isoniazid (INH) is used as a first-line treatment for tuberculosis. Clinical and experimental studies have reported abnormal liver function after INH therapy. Lagerstroemia speciosa Pers., commonly known as banaba, has been traditionally used to treat various ailments including diabetes and obesity due to its antioxidant and anti-inflammatory properties. Aim To investigate the hepatoprotective effect of ethanolic banaba leaf extract (EBLE) against INH-induced hepatotoxicity in rats. Materials and methods A total of 30 male Wistar albino rats (150 - 200 g) were divided into five groups (n = 6). Group I rats were served as a control and were administered dimethyl sulfoxide for the first 30 days and water for the next 30 consecutive days. Group II rats were administered INH (50 mg/kg, p.o.) once in the first 30 consecutive days and sacrificed at Day 30. Group III rats were administered INH for 30 consecutive days and left without treatment for the next 30 days. In Groups IV and V, rats were post-treated orally with EBLE 250 and 500 mg/kg, p.o. (0.3 ml/rat) for 30 days after INH administration. At the end of Day 60, the remaining group of animals were sacrificed. The blood and liver tissues were collected. The marker enzymes of hepatotoxicity, oxidative stress markers, inflammatory markers, and histopathology were analyzed. Results INH administration induced significant elevation of marker enzymes (aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, bilirubin, gamma-glutamyl transpeptidase) of hepatotoxicity in the serum. This treatment also increased lipid peroxidation and proinflammatory marker expression (tumor necrosis factor-alpha, transforming growth factor-beta, and nuclear factor kappa B (NF-κB) except inhibitor of NF-κB) and decreased antioxidants such superoxide dismutase, catalase, and glutathione in the liver tissue. All these abnormalities were significantly mitigated after treatment with EBLE. Conclusion The results of this study suggest that EBLE can be used for INH-induced hepatotoxicity.

A prospective observational study to evaluate Glutathione S-transferase gene polymorphism and its association with Antitubercular drugs induced liver injury in tertiary hospital

BACKGROUND

Anti-TB drugs are most common cause of idiosyncratic hepatotoxicity worldwide. Reactive metabolite formed during drug metabolism has been involved in a clinical toxicity are described as 'idiosyncratic' drug induce liver injury (DILI). We have observed the distribution of glutathione S -transferase (GST) gene polymorphism & its association with drug-induced liver injury in patients taking anti-tubercular treatment.

METHODS

A prospective observational study including 96 patients receiving anti-tubercular treatment. Blood sample was collected for LFT and gene extraction after ruling out other cause of liver injury. DNA extraction for GST gene was done follow by polymerase chain reaction to identify homozygous null mutation at GSTM1 and GSTT1 loci. Association of GSTM1 and GSTT1 gene with DILI was seen.

RESULTS

Out of 96 tubercular patients under treatment, drug induced liver injury was found in 21 (21.9%) patients and 75 does not develop DILI, GST M1 gene null mutation was observed in 14 (66.7%), GST T1 gene null mutation was observed in 9 (42.9%), Both GST gene null mutation was observed in 8 (38.1%) in DILI group.

CONCLUSION

The GSTM1 gene null mutation and both GSTM1 and T1 gene null mutation were a risk factor for the development of DILI. But there is no significant association between GSTT1 gene null mutation and DILI in TB patients.

Allelic and genotypic frequencies of NAT2, CYP2E1, and AADAC genes in a cohort of Peruvian tuberculosis patients

Background

We determined the frequency of genetic polymorphisms in three anti‐TB drug metabolic proteins previously reported: N‐acetyltransferase 2 (NAT2), cytochrome P450 2E1 (CYP2E1), and arylacetamide deacetylase (AADAC) within a Peruvian population in a cohort of TB patients.

Methods

We genotyped SNPs rs1041983, rs1801280, rs1799929, rs1799930, rs1208, and rs1799931 for NAT2; rs3813867 and rs2031920 for CYP2E1; and rs1803155 for AADAC in 395 participants completed their antituberculosis treatment.

Results

Seventy‐four percent of the participants are carriers of slow metabolizer genotypes: NAT2*5, NAT2*6, and NAT2*7, which increase the sensitivity of INH at low doses and increase the risk of drug‐induced liver injuries. Sixty‐four percent are homozygous for the wild‐type CYP2E1*1A allele, which could increase the risk of hepatotoxicity. However, 16% had a NAT2 fast metabolizer phenotype which could increase the risk of acquiring resistance to INH, thereby increasing the risk of multidrug‐resistant (MDR) or treatment failure. The frequency of rs1803155 (AADAC*2 allele) was higher (99.9%) in Peruvians than in European American, African American, Japanese, and Korean populations.

Conclusions

This high prevalence of slow metabolizers for isoniazid in the Peruvian population should be further studied and considered to help individualize drug regimens, especially in countries with a great genetic diversity like Peru. These data will help the Peruvian National Tuberculosis Control Program develop new strategies for therapies.

Genetic variation of ABCB1 (rs1128503, rs1045642) and CYP2E1 rs3813867 with the duration of tuberculosis therapy: a pilot study among tuberculosis patients in Indonesia

Objective

The risk of contracting tuberculosis (TB) and the efficacy of TB therapy are affected by several factors, including genetic variation among populations. In the Indonesian population, data on the genes involved in drug transport and metabolism of TB therapy are limited. The aim of this study was to identify the genetic profile of the ABCB1 gene (rs1128503 and rs1045642) and CYP2E1 gene (rs3813867) in Indonesians with TB. This study was a cross-sectional study of 50 TB outpatients in Jambi city, Indonesia. Sociodemographic characteristics were obtained from medical records. Whole blood was collected, and genomic DNA was isolated. Single nucleotide polymorphisms were determined using polymerase chain reaction-restriction fragment length polymorphism with HaeIII, MboI, and PstI for rs1128503, rs1045642 (ABCB1), and rs3813867 (CYP2E1), respectively.

Result

The frequency of alleles of each gene was analyzed by Hardy–Weinberg equilibrium. The genetic profiles of ABCB1 rs1128503 and rs1045642 were varied (CC, CT, TT), while CYP2E1 rs3813867 was present in CC (wild type). The genetic variations of ABCB1 and CYP2E1 may have no significant correlation with the duration of TB therapy. Nevertheless, this study may provide as preliminary results for the genetic profiles of ABCB1 (rs1128503, rs1045642) and CYP2E1 (rs3813867) in the Indonesia population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05711-8.

CYP2E1, GSTM1, and GSTT1 genetic polymorphisms and their associations with susceptibility to antituberculosis drug-induced liver injury in Thai tuberculosis patients

Antituberculosis drug-induced liver injury (ATDILI) is the common adverse reaction of antituberculosis drugs. Glutathione S-transferases (GSTs), which are phase II metabolizing enzymes for detoxification, are recognized as potential mediators of hepatotoxicity. However, role of GSTs polymorphisms in ATDILI pathogenesis has never been observed in Thais. This study aimed to investigate associations between GSTs and ATDILI susceptibility. This retrospective case-control multicentered study was conducted by the collaboration from ten secondary and tertiary care hospitals across Thailand, including Northern, Central, and Southern parts of Thailand. We enrolled 80 tuberculosis (TB) patients with ATDILI and 174 those without ATDILI into the study. Polymerase chain reaction (PCR) was used to determine genetic polymorphisms of GSTM1 and GSTT1 genes. CYP2E1 genotyping data were derived from microarray data. We illustrated that GSTT1 null and GSTM1/GSTT1 dual null genotypes were correlated with an increased risk of ATDILI with odds ratio (OR) at 1.83 (95% confidence interval (CI), 1.00 to 3.35; P = 0.049) and 2.12 (95%CI, 1.02 to 4.38; P = 0.044), respectively. Interestingly, GSTT1 null and GSTM1/GSTT1 dual null genotypes were found to be correlated with an increased risk of ATDILI in Thai TB patients who carried CYP2E1 wild type phenotype with OR 2.99 (95%CI, 1.07 to 8.39; P = 0.037) and 3.44 (95%CI, 1.01 to 11.71; P = 0.048), respectively. Collectively, GSTT1 null and GSTM1/GSTT1 dual null genotypes were associated with a higher risk of ATDILI in Thai TB patients, which may serve as alternative genetic biomarkers for ATDILI.

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 considerations in the treatment of co-infections with HIV/AIDS, tuberculosis and malaria in Congolese populations of Central Africa

BACKGROUND

HIV-infection, tuberculosis and malaria are the big three communicable diseases that plague sub-Saharan Africa. If these diseases occur as co-morbidities they require polypharmacy, which may lead to severe drug-drug-gene interactions and variation in adverse drug reactions, but also in treatment outcomes. Polymorphisms in genes encoding drug-metabolizing enzymes are the major cause of these variations, but such polymorphisms may support the prediction of drug efficacy and toxicity. There is little information on allele frequencies of pharmacogenetic variants of enzymes involved in the metabolism of drugs used to treat HIV-infection, TB and malaria in the Republic of Congo (ROC). The aim of this study was therefore to investigate the occurrence and allele frequencies of 32 pharmacogenetic variants localized in absorption distribution, metabolism and excretion (ADME) and non-ADME genes and to compare the frequencies with population data of Africans and non-Africans derived from the 1000 Genomes Project.

RESULTS

We found significant differences in the allele frequencies of many of the variants when comparing the findings from ROC with those of non-African populations. On the other hand, only a few variants showed significant differences in their allele frequencies when comparing ROC with other African populations. In addition, considerable differences in the allele frequencies of the pharmacogenetic variants among the African populations were observed.

CONCLUSIONS

The findings contribute to the understanding of pharmacogenetic variants involved in the metabolism of drugs used to treat HIV-infection, TB and malaria in ROC and their diversity in different populations. Such knowledge helps to predict drug efficacy, toxicity and ADRs and to inform individual and population-based decisions.

Toxicoproteomic Profiling of hPXR Transgenic Mice Treated with Rifampicin and Isoniazid

Tuberculosis is a global health threat that affects millions of people every year, and treatment-limiting toxicity remains a considerable source of treatment failure. Recent reports have characterized the nature of hPXR-mediated hepatotoxicity and the systemic toxicity of antitubercular drugs. The antitubercular drug isoniazid plays a role in such pathologic states as acute intermittent porphyria, anemia, hepatotoxicity, hypercoagulable states (deep vein thrombosis, pulmonary embolism, or ischemic stroke), pellagra (vitamin B₃ deficiency), peripheral neuropathy, and vitamin B₆ deficiency. However, the mechanisms by which isoniazid administration leads to these states are unclear. To elucidate the mechanism of rifampicin- and isoniazid-induced liver and systemic injury, we performed tandem mass tag mass spectrometry-based proteomic screening of mPxr^-/- and hPXR mice treated with combinations of rifampicin and isoniazid. Proteomic profiling analysis suggested that the hPXR liver proteome is affected by antitubercular therapy to disrupt [Fe-S] cluster assembly machinery, [2Fe-2S] cluster-containing proteins, cytochrome P450 enzymes, heme biosynthesis, homocysteine catabolism, oxidative stress responses, vitamin B₃ metabolism, and vitamin B₆ metabolism. These novel findings provide insight into the etiology of some of these processes and potential targets for subsequent investigations. Data are available via ProteomeXchange with identifier PXD019505.

Single-nucleotide polymorphisms of HLA and Polygonum multiflorum-induced liver injury in the Han Chinese population

BACKGROUND

Polygonum multiflorum is one of the leading causes of herb-induced liver injury in China. HLA-B*35:01 is reported to be a potential biomarker of Polygonum multiflorum-induced liver injury (PM-DILI). However, little is known about the relationship between single-nucleotide polymorphisms (SNPs) and PM-DILI.

AIM

To identify SNPs that indicate susceptibility to PM-DILI.

METHODS

We conducted a systematic study enrolling 382 participants from four independent hospitals, including 73 PM-DILI patients, 118 patients with other drug-induced liver injury (other-DILI) and 191 healthy controls. Whole-exome sequencing was performed for 8 PM-DILI patients and 8 healthy controls who were randomly selected from the above subjects. Nineteen SNPs that showed high frequencies in the 8 PM-DILI patients were selected as candidate SNPs and then screened in 65 PM-DILI patients, 118 other-DILI patients and 183 healthy controls using the MassARRAY system. HLA-B high-resolution genotyping was performed for the 73 PM-DILI and 118 other-DILI patients. The Han-MHC database was selected as a population control for HLA-B analysis. P < 6.25 × 10^-3 after Bonferroni correction was considered significant.

RESULTS

The frequencies of rs111686806 in the HLA-A gene, rs1055348 in the HLA-B gene, and rs202047044 in the HLA-DRB1 gene were significantly higher in the PM-DILI group than in the control group [27.2% vs 11.6%, P = 1.72 × 10^-5, odds ratio (OR) = 3.96, 95% confidence interval (CI): 2.21-7.14; 42.5% vs 8.6%, P = 1.72 × 10^-19, OR = 13.62, 95%CI: 7.16-25.9; 22.9% vs 8.1%, P = 4.64 × 10^-6, OR = 4.1, 95%CI: 2.25-7.47]. Only rs1055348 showed a significantly higher frequency in the PM-DILI group than in the other-DILI group (42.5% vs 13.6%, P = 1.84 × 10^-10, OR = 10.06, 95%CI: 5.06-20.0), which suggested that it is a specific risk factor for PM-DILI. rs1055348 may become a tag for HLA-B*35:01 with 100% sensitivity and 97.7% specificity in the PM-DILI group and 100% sensitivity and 98.1% specificity in the other-DILI group. Furthermore, HLA-B*35:01 was confirmed to be associated with PM-DILI with a frequency of 41.1% in the PM-DILI group compared with 11.9% (P = 4.30 × 10^-11, OR = 11.11, 95%CI: 5.57-22.19) in the other-DILI group and 2.7% (P = 6.22 × 10^-166, OR = 62.62, 95%CI: 35.91-109.20) in the Han-MHC database.

CONCLUSION

rs111686806, rs1055348, and rs202047044 are associated with PM-DILI, of which, rs1055348 is specific to PM-DILI. As a tag for HLA-B*35:01, rs1055348 may become an alternative predictive biomarker of PM-DILI.

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.

Molecular Biomarkers in Drug-Induced Liver Injury: Challenges and Future Perspectives

Drug-induced liver injury (DILI) is one among the common adverse drug reactions and the leading causes of drug development attritions, black box warnings, and post-marketing withdrawals. Despite having relatively low clinical incidence, its potentially severe adverse events should be considered in the individual patients due to the high risk of acute liver failure. Although traditional liver parameters have been applied to the diagnosis of DILI, the lack of specific and sensitive biomarkers poses a major limitation, and thus accurate prediction of the subsequent clinical course remains a significant challenge. These drawbacks prompt the investigation and discovery of more effective biomarkers, which could lead to early detection of DILI, and improve its diagnosis and prognosis. Novel promising biomarkers include glutamate dehydrogenase, keratin 18, sorbitol dehydrogenase, glutathione S-transferase, bile acids, cytochrome P450, osteopontin, high mobility group box-1 protein, fatty acid binding protein 1, cadherin 5, miR-122, genetic testing, and omics technologies, among others. Furthermore, several clinical scoring systems have gradually emerged for the diagnosis of DILI including the Roussel Uclaf Causality Assessment Method (RUCAM), Clinical Diagnostic Scale (CDS), and Digestive Disease Week Japan (DDW-J) systems. However, currently their predictive value is limited with certain inherent deficiencies. Thus, perhaps the greatest benefit would be achieved by simultaneously combining the scoring systems and those biomarkers. Herein, we summarized the recent research progress on molecular biomarkers for DILI to improved approaches for its diagnosis and clinical management.

Genetic Polymorphisms in Antioxidant Enzymes Modulate the Susceptibility of Idiosyncratic Antituberculous Drug-Induced Liver Injury and Treatment Outcomes in Patients with Tuberculosis

BACKGROUND

The pathogenic mechanism of antituberculous drug-induced liver injury (ATDILI) is associated with antioxidant enzymes. The objective of the present study was to investigate the associations of ATDILI susceptibility with genetic polymorphisms of antioxidant enzyme genes including nitric oxide synthase 2 (NOS2), thioredoxin reductase 1 (TXNRD1), superoxide dismutase 2 (SOD2), BTB domain and CNC homolog 1 (BACH1), and MAF bZIP transcription factor K (MAFK).

METHODS

Thirty tag single nucleotide polymorphisms (tag-SNPs) from the all candidate genes were genotyped in a 2-stage cohort study including an initial discovery stage with 461 ATDILI patients and 466 controls and a replication stage with 216 ATDILI patients and 432 controls. The frequencies and distributions of genotypes and haplotypes were compared between the case and control groups. Three different genetic models including dominant, recessive, and additive models were used to determine the associations with susceptibility to ATDILI.

RESULTS

The SNPs rs9906835, rs944725, and rs3794764 of the NOS2 gene were significantly associated with an increased risk of ATDILI. The MAFK rs3735656 SNP was significantly associated with a decreased risk for ATDILI. The AAA haplotype of the NOS2 gene was associated with susceptibility to ATDILI. The treatment outcomes of patients with tuberculosis were further affected by genetic variants of the NOS2 and MAFK genes.

CONCLUSIONS

Genetic polymorphisms of NOS2 and MAFK are associated with ATDILI susceptibility in Chinese patients with tuberculosis. The variants in NOS2 and MAFK affect treatment outcomes of tuberculosis patients. Further studies are needed to better understand the molecular mechanisms of ATDILI susceptibility via regulation of the expression of ATDILI-susceptibility genes and proteins.

Relationship of anti-tuberculosis drug-induced liver injury and genetic polymorphisms in CYP2E1 and GST

SETTING

Treatment of tuberculosis (TB) can result in Drug-Induced Liver Injury (DILI) since hepatotoxic metabolites are formed during the biotransformation of isoniazid (INH). DILI can be related to the genetic profile of the patient. Single nucleotide polymorphisms in the CYP2E1 gene and GSTM1 and GSTT1 deletion polymorphisms have been associated with adverse events caused by INH.

OBJECTIVE

To characterize the genetic polymorphisms of CYP2E1, GSTT1 and GSTM1 in TB carriers.

DESIGN

This is an observational prospective cohort study of 45 patients undergoing treatment of TB. PCR-RFLP and multiplex-PCR were used.

RESULTS

The distribution of genotypic frequency in the promoter region (CYP2E1 gene) was: 98% wild genotype and 2% heterozygous. Intronic region: 78% wild genotype; 20% heterozygous and 2% homozygous variant. GST enzyme genes: 24% Null GSTM1 and 22% Null GSTT1. Patients with any variant allele of the CYP2E1 gene were grouped in the statistical analyses.

CONCLUSION

Patients with the CYP2E1 variant genotype or Null GSTT1 showed higher risk of presenting DILI (p=0.09; OR: 4.57; 95% CI: 0.75-27.6). Individuals with both genotypes had no increased risk compared to individuals with one genotype.

Are genetic variations in glutathione S-transferases involved in anti-tuberculosis drug-induced liver injury? A meta-analysis

WHAT IS KNOWN AND OBJECTIVE

As a crucial protective role in the detoxifying mechanisms of drugs, glutathione S-transferases (GSTs) may affect an individual patient's susceptibility to anti-tuberculosis drug-induced liver injury (ATLI). However, the results of studies investigate the association between GSTM1, GSTT1 and GSTP1 polymorphisms and risk of ATLI are inconclusive. A meta-analysis on this topic was performed.

METHODS

PubMed, EMBASE, ISI web of science and the Chinese National Knowledge Infrastructure (CNKI) were systematically searched to identify relevant studies. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were calculated. Heterogeneity among articles and publication bias were also tested.

RESULTS AND DISCUSSION

After excluding one study as an outlier, the null GSTM1 genotype was associated with an increased risk of ATLI (OR = 1.270, 95% CI (1.014-1.590, P = .038), especially in East Asians (OR = 1.501, 95% CI (1.303-1.730). With similar exclusion, the null GSTT1 genotype increased the risk of ATLI in the total population (OR = 1.169, 95% CI: 1.028-1.330) and in Indians (OR = 1.732, 95% CI: 1.229-2.416). No statistically significant association was observed between the mutant GSTP1 genotype with risk of ATLI, which may need more rigorous and uniform case-control or cohort studies for more robust inferences.

WHAT IS NEW AND CONCLUSION

This up-to-date meta-analysis strongly suggests associations of GSTM1 and GSTT1 polymorphisms with ATLI. The results show the increased risk of ATL1 with the null GSTM1 and GSTT1 genotype on ATLI development. No such association is shown with the mutant GSTP1 genotype.

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.

Isoniazid Concentration and NAT2 Genotype Predict Risk of Systemic Drug Reactions during 3HP for LTBI

Weekly rifapentine and isoniazid therapy (known as 3HP) for latent tuberculosis infection (LTBI) is increasingly used, but systemic drug reactions (SDR) remain a major concern. Methods: We prospectively recruited two LTBI cohorts who received the 3HP regimen. In the single-nucleotide polymorphism (SNP) cohort, we collected clinical information of SDRs and examined the NAT2, CYP2E1, and AADAC SNPs. In the pharmacokinetic (PK) cohort, we measured plasma drug and metabolite levels at 6 and 24 h after 3HP administration. The generalised estimating equation model was used to identify the factors associated with SDRs. Candidate SNPs predicting SDRs were validated in the PK cohort. A total of 177 participants were recruited into the SNP cohort and 129 into the PK cohort, with 14 (8%) and 13 (10%) in these two cohorts developing SDRs, respectively. In the SNP cohort, NAT2 rs1041983 (TT vs. CC+CT, odds ratio [OR] [95% CI]: 7.00 [2.03–24.1]) and CYP2E1 rs2070673 (AA vs. TT+TA, OR [95% CI]: 3.50 [1.02–12.0]) were associated with SDR development. In the PK cohort, isoniazid level 24 h after 3HP administration (OR [95% CI]: 1.61 [1.15–2.25]) was associated with SDRs. Additionally, the association between the NAT2 SNP and SDRs was validated in the PK cohort (rs1041983 TT vs. CC+CT, OR [95% CI]: 4.43 [1.30–15.1]). Conclusions: Isoniazid played a role in the development of 3HP-related SDRs. This could provide insight for further design of a more optimal regimen for latent TB infection.

Pharmacokinetics of isoniazid: The good, the bad, and the alternatives

Although isoniazid (INH) has been successful in treating Tuberculosis (TB) since its introduction in 1952, there has been continual reports of drug-associated hepatotoxicity in TB patients. These toxic side effects may reveal more about the recipient of the drug, than the drug itself. A combination of pharmacogenetic and pharmacokinetic studies have identified polymorphisms within enzymes involved in INH metabolism and detoxification. These essential metabolic enzymes include N-acetyltransferase 2, Cytochrome P450 2E1, and glutathione S transferases. Different phenotypes of these enzymes can affect the rate of INH metabolism, resulting in production of hepatotoxic metabolites. This review is intended to elucidate the pharmacokinetics of INH by examining its Administration, Distribution, Metabolism, and Elimination, while suggesting potential alternatives within INH personalized treatment to help reduce hepatotoxicity.

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.

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.

The association between the NAT2 genetic polymorphisms and risk of DILI during anti-TB treatment: a systematic review and meta-analysis

AIMS

The aim of this study is to evaluate the potential association between N-acetyltransferase type 2 (NAT2) polymorphisms and drug-induced liver injury during anti-TB treatment (AT-DILI).

METHODS

We conducted a systematic review and performed a meta-analysis to clarify the role of NAT2 polymorphism in AT-DILI. PubMed, Medline and EMBASE databases were searched for studies published in English to December 31, 2017, on the association between the NAT2 polymorphism and AT-DILI risk. Outcomes were pooled with random-effects meta-analysis. Details were registered in the PROSPERO register (number: CRD42016051722).

RESULTS

Thirty-seven studies involving 1527 cases and 7184 controls were included in this meta-analysis. The overall odds ratio (OR) of AT-DILI associated with NAT2 slow acetylator phenotype was 3.15 (95% CI 2.58-3.84, I²  = 51.3%, P = 0.000). The OR varied between different ethnic populations, ranging from 6.42 (95% CI 2.41-17.10, I²  = 2.3%) for the West Asian population to 2.32 (95% CI 0.58-9.24, I²  = 80.3%) for the European population. Within the slow NAT2 genotype, variation was also observed; NAT2*6/*7 was associated with the highest risk of AT-DILI (OR = 1.68, 95% CI 1.09-2.59) compared to the other slow NAT2 acetylators combined.

CONCLUSIONS

NAT2 slow acetylation was observed to increase the risk of AT-DILI in tuberculosis patients. Our results support the hypothesis that the slow NAT2 genotype is a risk factor for AT-DILI.

Urgent Living-Donor Liver Transplantation in a Patient With Concurrent Active Tuberculosis: A Case Report

BACKGROUND

Although active tuberculosis (TB) is considered a contraindication for liver transplantation (LT), this is the only treatment in patients with liver failure and concurrent active TB. We report a case with successful urgent living-donor LT for irreversible liver failure in the presence of active TB.

CASE PRESENTATION

A 48-year-old man, with a history of decompensated alcoholic liver cirrhosis, was presented with stupor. At admission, his consciousness had deteriorated to semi-coma, and his renal function also rapidly deteriorated to hepatorenal syndrome. A preoperative computed tomography scan of the chest revealed several small cavitary lesions in both upper lobes, and acid-fast bacillus stain from his sputum was graded 2+. Adenosine deaminase levels from ascites were elevated, suggesting TB peritonitis. A first-line anti-TB drug regimen was started immediately (rifampin, isoniazid, levofloxacin, and amikacin). An urgent living-donor LT was performed 2 days later. After LT, the regimen was changed to second-line anti-TB drugs (amikacin, levofloxacin, cycloserine, and pyridoxine). The sputum acid-fast bacillus stain tested negative on postoperative day 10. His liver function remained well preserved, even after the reversion to first-line anti-TB treatment. The patient recovered without any anti-TB medication-related complications and was discharged.

CONCLUSIONS

LT can be prudently performed as a life-saving option, particularly for patients with liver failure and concurrent active TB.

Liver toxicity associated with tuberculosis chemotherapy in the REMoxTB study

BACKGROUND

Drug-induced liver injury (DILI) is a common complication of tuberculosis treatment. We utilised data from the REMoxTB clinical trial to describe the incidence of predisposing factors and the natural history in patients with liver enzyme levels elevated in response to tuberculosis treatment.

METHODS

Patients received either standard tuberculosis treatment (2EHRZ/4HR), or a 4-month regimen in which moxifloxacin replaced either ethambutol (isoniazid arm, 2MHRZ/2MHR) or isoniazid (ethambutol arm, 2EMRZ/2MR). Hepatic enzymes were measured at 0, 2, 4, 8, 12 and 17 weeks and as clinically indicated during reported adverse events. Patients included were those receiving at least one dose of drug and with two or more hepatic enzyme measurements.

RESULTS

A total of 1928 patients were included (639 2EHRZ/4HR, 654 2MHRZ/2MHR and 635 2EMRZ/2MR). DILI was defined as peak alanine aminotransferase (ALT) ≥ 5 times the upper limit of normal (5 × ULN) or ALT ≥ 3 × ULN with total bilirubin > 2 × ULN. DILI was identified in 58 of the 1928 (3.0%) patients at a median time of 28 days (interquartile range IQR 14-56). Of 639 (6.4%) patients taking standard tuberculosis therapy, 41 experienced clinically significant enzyme elevations (peak ALT ≥ 3 × ULN). On standard therapy, 21.1% of patients aged >55 years developed a peak ALT/aspartate aminotransferase (AST) ≥ 3 × ULN (p = 0.01) and 15% of HIV-positive patients experienced a peak ALT/AST ≥ 3 × ULN compared to 9% of HIV-negative patients (p = 0.160). The median peak ALT/AST was higher in isoniazid-containing regimens vs no-isoniazid regimens (p < 0.05), and lower in moxifloxacin-containing arms vs no-moxifloxacin arms (p < 0.05). Patients receiving isoniazid reached a peak ALT ≥ 3 × ULN 9.5 days earlier than those on the ethambutol arm (median time of 28 days vs 18.5 days). Of the 67 Asian patients with a peak ALT/AST ≥ 3 × ULN, 57 (85.1%) were on an isoniazid-containing regimen (p = 0.008).

CONCLUSIONS

Our results provide evidence of the risk of DILI in tuberculosis patients on standard treatment. Older patients on standard therapy, HIV-positive patients, Asian patients and those receiving isoniazid were at higher risk of elevated enzyme levels. Monitoring hepatic enzymes during the first 2 months of standard therapy detected approximately 75% of patients with a peak enzyme elevation ≥3 × ULN, suggesting this should be a standard of care. These results provide evidence for the potential of moxifloxacin in hepatic sparing.

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.

Effect of gene-gene and gene-environment interactions associated with antituberculosis drug-induced hepatotoxicity

OBJECTIVES

This study evaluated the association between environmental factors and genetic variations in enzymes that metabolize antituberculosis (anti-TB) drugs [arylamine N-acetyltransferase 2, cytochrome P450 2E1 (CYP2E1), glutathione S-transferase theta 1 (GSTT1), and glutathione S-transferase mu 1] with antituberculosis drug-induced hepatotoxicity (ATDH). We also investigated the potential gene-gene and gene-environment interactions as well as their association with ATDH development in a population of hospitalized TB patients from Buenos Aires.

PATIENTS AND METHODS

We investigated 364 TB patients who received anti-TB drugs. Physicians collected demographic and clinical data to identify environmental risk factors for ATDH development. Polymorphisms were detected using gene sequencing, PCR, and PCR-restriction fragment length polymorphisms. A binary logistic regression analysis was carried out to compare the results of TB patients with and without the development of hepatotoxicity. The multifactor dimensionality reduction method was used to examine genetic and environmental interactions in association with ATDH.

RESULTS

This study suggests that the slow acetylator profile [odds ratio (OR): 3.02; 95% confidence interval (CI): 1.82-5.00; P<0.001], genotypes carrying the c2 variant (OR: 2.16; 95% CI: 1.33-3.51; P=0.002) or the A4 variant of CYP2E1 (OR: 2.13; 95% CI: 1.06-4.29; P=0.050), and female sex (OR: 1.94; 95% CI: 1.20-3.14; P=0.006) were independent predictor variables for ATDH. Patients carrying the slow acetylator profile and the c2 variant showed an increased risk (OR: 7.068; 95% CI: 3.34-14.95; P<0.001). We also identified a synergic interaction (epistasis) between GSTT1 and CYP2E1 associated with an increased risk for ATDH. A meaningful gene-environment interaction was associated with an increased risk of ATDH [testing balance accuracy=0.675 (P=0.001) and cross-validation consistency=10/10].

CONCLUSION

ATDH is a severe and prevalent adverse drug reaction and leads to drug discontinuation in 11% of TB patients. Our study created a prediction model that properly classified the 67.5% of TB patients in their risk of developing ATDH. The considerable number of TB patients in our country supports the use of pharmacogenetic testing and a comprehensive clinical history to identify patients with a high risk of suffering hepatotoxicity.

Advances and Challenges of HDAC Inhibitors in Cancer Therapeutics

Since the identification and cloning of human histone deacetylases (HDACs) and the rapid approval of vorinostat (Zolinza®) for the treatment of cutaneous T-cell lymphoma, the field of HDAC biology has met many initial successes. However, many challenges remain due to the complexity involved in the lysine posttranslational modifications, epigenetic transcription regulation, and nonepigenetic cellular signaling cascades. In this chapter, we will: review the discovery of the first HDAC inhibitor and present discussion regarding the future of next-generation HDAC inhibitors, give an overview of different classes of HDACs and their differences in lysine deacylation activity, discuss different classes of HDAC inhibitors and their HDAC isozyme preferences, and review HDAC inhibitors' preclinical studies, their clinical trials, their pharmacokinetic challenges, and future direction. We will also discuss the likely reason for the failure of multiple HDAC inhibitor clinical trials in malignancies other than lymphoma and multiple myeloma. In addition, the potential molecular mechanism(s) that may play a key role in the efficacy and therapeutic response rate in the clinic and the likely patient population for HDAC therapy will be discussed.

Molecular characterization of mutations associated with resistance to second-line tuberculosis drug among multidrug-resistant tuberculosis patients from high prevalence tuberculosis city in Morocco

BACKGROUND

The emergence of extensively drug-resistant tuberculosis (XDR-TB) has raised public health concern for global TB control. Although multi drug-resistant tuberculosis (MDR- TB) prevalence and associated genetic mutations in Morocco are well documented, scarce information on XDR TB is available. Hence, the evaluation of pre-XDR and XDR prevalence, as well as the mutation status of gyrA, gyrB, rrs, tlyA genes and eis promoter region, associated with resistance to second line drugs, is of great value for better management of M/XDR TB in Morocco.

OBJECTIVES

To evaluate pre-XDR and XDR prevalence, as well as the mutation status of gyrA, gyrB, rrs, tlyA genes and eis promoter region, associated with resistance to second line drug resistance, in 703 clinical isolates from TB patients recruited in Casablanca, and to assess the usefulness of molecular tools in clinical laboratories for better management of M/XDR TB in Morocco.

METHODS

Drug susceptibility testing (DST) was performed by the proportional method for first line drugs, and then the selected MDR isolates were tested for second line drugs (Ofloxacin, Kanamycin, Amikacin and Capreomycin). Along with DST, all samples were subjected to rpoB, katG and p-inhA mutation analysis by PCR and DNA sequencing. MDR isolates as well as 30 pan-susceptible strains were subjected to PCR and DNA sequencing of gyrA, gyrB, rrs, tlyA genes and eis promoter, associated with resistance to fluoroquinolones and injectable drugs.

RESULTS

Among the 703 analysed strains, 12.8% were MDR; Ser531Leu and Ser315Thr being the most common recorded mutations within rpoB and katG genes associated with RIF and INH resistance respectively. Drug susceptibility testing for second line drugs showed that among the 90 MDR strains, 22.2% (20/90) were resistant to OFX, 2.22% (2/90) to KAN, 3.33% (3/90) to AMK and 1.11% (1/90) to CAP. Genotypic analysis revealed that 19 MDR strains harbored mutations in the gyrA gene; the most recorded mutation being Asp91Ala accounting for 47.6% (10/21), and 2 isolates harbored mutations in the promoter region of eis gene. No mutation was found in gyrB, rrs and tlyA genes. Moreover, none of the pan-susceptible isolates displayed mutations in targeted genes.

CONCLUSION

Most of mutations associated with SLD resistance occurred in gyrA gene (codons 90-94) and eis promoter region. These findings highlight the impact of mutations in gyrA on the development of fluroquinolones resistance and provide the first estimates of the proportion of pre-XDR-TB among MDR-TB cases in Morocco.

Substantially Higher and Earlier Occurrence of Anti-Tuberculosis Drug-Related Adverse Reactions in HIV Coinfected Tuberculosis Patients: A Matched-Cohort Study

Little information exists on the frequency, severity, and timing of first-line anti-tuberculosis drug-related adverse events (TB-AEs) in HIV-tuberculosis coinfected (HIV-TB) patients in the antiretroviral therapy (ART) era. This matched-cohort study included HIV-TB patients as cases and HIV-uninfected tuberculosis (non-HIV-TB) patients as controls. Tuberculosis was culture-confirmed in both groups. Cases were matched to controls in a 1:4 ratio on age, sex, and year of diagnosis. TB-AEs were defined as Grade 2 or higher requiring drug discontinuation/regimen change. From 2003 to 2015, 94 cases and 376 controls were analyzed (95% men, 98% Asians). Standard four-drug combination therapy was initiated in 91% of cases and 89% of controls (p = 0.45). Cases had a higher frequency of TB-AE [51% (48/94) vs. 10% (39/376), p < 0.001]. Their major TB-AEs were fever (19%), rash (11%), and neutropenia (11%). TB-AEs were more severe in cases [Grade 3 or higher: cases (71%, 34/48) vs. controls (49%, 19/39), p < 0.001]. The time from treatment initiation to TB-AE was shorter in cases [median 18 (interquartile range 12-28) vs. 27 (15-57) days, p = 0.027], and 73% of TB-AEs in cases occurred within 4 weeks of starting anti-tuberculosis treatment. HIV infection was an independent risk factor for TB-AEs in the multivariate Cox analysis [adjusted HR (aHR): 6.96; 95% confidence interval: 3.93-12.3]. TB-AEs occurred more frequently in HIV-TB than in non-HIV-TB patients, and were more severe. The majority of TB-AEs occurred within 4 weeks of initiating anti-tuberculosis treatment. Because TB-AEs may delay ART initiation, careful monitoring during this period is warranted in coinfected patients.

Association and clinical utility of NAT2 in the prediction of isoniazid-induced liver injury in Singaporean patients

BACKGROUND AND AIMS

Isoniazid (INH) is part of the first-line-therapy for tuberculosis (TB) but can cause drug-induced liver injury (DILI). Several candidate single nucleotide polymorphisms (SNPs) have been previously identified but the clinical utility of these SNPs in the prediction of INH-DILI remains uncertain. The aim of this study was to assess the association between selected candidate SNPs and the risk of INH-DILI and to assess the clinical validity of associated variants in a Singaporean population.

METHODS

This was a case-control study where 24 INH-DILI cases and 79 controls were recruited from the TB control unit in a tertiary hospital. Logistic regression was used to test for the association between candidate SNPs and INH-DILI. NAT2 acetylator status was inferred from genotypes and tested for association with INH-DILI. Finally, clinical validity measures were estimated for significant variants.

RESULTS

Two SNPs in NAT2 (rs1041983 and rs1495741) and NAT2 slow acetylators (SA) were significantly associated with INH-DILI (OR (95% CI) = 13.86 (4.30-44.70), 0.10 (0.03-0.33) and 9.98 (3.32-33.80), respectively). Based on an INH-DILI prevalence of 10%, the sensitivity, specificity, positive and negative predictive values of NAT2 SA were 75%, 78%, 28% and 97%, respectively. The population attributable fraction (PAF) and number needed to test (NNT) for NAT2 SA were estimated to be 0.67 and 4.08, respectively. A model with clinical and NAT2 acetylator status provided significantly better prediction for INH-DILI than a clinical model alone (area under receiver operating characteristic curve = 0.863 vs. 0.766, respectively, p = 0.027).

CONCLUSIONS

We show the association between NAT2 SA and INH-DILI in a Singaporean population and demonstrated its clinical utility in the prediction of INH-DILI.

Hepatotoxicity in Rats Induced by Aqueous Extract of Polygoni Multiflori Radix, Root of Polygonum multiflorum Related to the Activity Inhibition of CYP1A2 or CYP2E1

The objective of this study is to investigate the relationship between the hepatotoxicity induced by Polygoni Multiflori Radix (PMR, root of Polygonum multiflorum Thunb., He Shou Wu) and the activity of CYP1A2 or CYP2E1 in the rat liver. Levels of rat serum transaminases ALT and AST were not altered but the activity of CYP1A2 or CYP2E1 in the rat liver was significantly inhibited after oral administration of aqueous extract of PMR under the experimental dosage. However, levels of ALT and AST were significantly increased and the activity of CYP1A2 or CYP2E1 was significantly decreased after injection of specific inhibitor for CYP1A2 or CYP2E1 combined with oral administration of aqueous extract of PMR, especially under the repeated treatment over interval times. Liver histopathological observation showed that a moderate liver injury occurred in rats receiving PMR treatment with the activity of CYP1A2 or CYP2E1 inhibited, but there was no significant liver damage in rats receiving PMR treatment or CYP inhibitor alone. These suggested that low level activity of CYP1A2 or CYP2E1 from genetic polymorphism among people might be one of the important reasons for the hepatotoxicity induced by PMR in clinical practice.

Mechanisms of Drug-Induced Hepatotoxicity

Drug-induced hepatotoxicity (DIH) is a significant cause of acute liver failure and liver transplantation. Diagnosis is challenging due to the idiosyncratic nature, its presentation in the form of other liver disease, and the lack of a definite diagnostic criteria. Generation of reactive metabolites, oxidative stress, and mitochondrial dysfunction are common mechanisms involved in DIH. Certain risk factors associated with a drug and within an individual further predispose patients to DIH.

Are Polymorphisms in Genes Relevant to Drug Disposition Predictors of Susceptibility to Drug-Induced Liver Injury?

Despite considerable progress in identifying specific HLA alleles as genetic risk factors for some forms of drug-induced liver injury, progress in understanding whether genetic polymorphisms relevant to drug disposition also contribute to risk for developing this serious toxicity has been more limited. Evidence from both candidate-gene case control studies and genome-wide association studies is now discussed. In the case of genes relevant to drug metabolism, polymorphisms in cytochromes P450, UDP-glucuronosyltransferases, N-acetyltransferases and glutathione S-transferases as risk factors for DILI are assessed. The relevance of ABC transporters to drug-induced liver injury is also considered, together with data showing associations of particular ABCB11, ABCB1 and ABCC2 polymorphisms with some forms of drug-induced liver injury. Very few of the associations with genes relevant to drug disposition that have been reported have been well replicated. Even apparently well-studied associations such as that between isoniazid liver injury and N-acetyltransferase 2 slow acetylators remain problematic, though it seems likely that polymorphisms in drug metabolism genes do contribute to risk for some specific drugs. A better understanding of genetic risk factors for drug-induced liver injury will require further genome-wide association studies with larger numbers of cases, especially for forms of drug-induced liver injury where HLA genotype does not appear to be a risk factor.

Polymorphisms in NAT2 (N-acetyltransferase 2) gene in patients with systemic lupus erythematosus

OBJECTIVE

To investigate potential associations of four substitutions in NAT2 gene and of acetylator phenotype of NAT2 with systemic lupus erythematosus (SLE) and clinical phenotypes.

METHODS

Molecular analysis of 481C>T, 590G>A, 857G>A, and 191G>A substitutions in the NAT2 gene was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique, from DNA extracted from peripheral blood samples obtained from patients with SLE (n=91) and controls (n=97).

RESULTS AND CONCLUSIONS

The 857GA genotype was more prevalent among nonwhite SLE patients (OR=4.01, 95% CI=1.18-13.59). The 481T allele showed a positive association with hematological disorders that involve autoimmune mechanisms, specifically autoimmune hemolytic anemia or autoimmune thrombocytopenia (OR=1.97; 95% CI=1.01-3.81).

Hepatotoxicity during Treatment for Tuberculosis in People Living with HIV/AIDS

Hepatotoxicity is frequently reported as an adverse reaction during the treatment of tuberculosis. The aim of this study was to determine the incidence of hepatotoxicity and to identify predictive factors for developing hepatotoxicity after people living with HIV/AIDS (PLWHA) start treatment for tuberculosis. This was a prospective cohort study with PLWHA who were monitored during the first 60 days of tuberculosis treatment in Pernambuco, Brazil. Hepatotoxicity was considered increased levels of aminotransferase, namely those that rose to three times higher than the level before initiating tuberculosis treatment, these levels being associated with symptoms of hepatitis. We conducted a multivariate logistic regression analysis and the magnitude of the associations was expressed by the odds ratio with a confidence interval of 95%. Hepatotoxicity was observed in 53 (30.6%) of the 173 patients who started tuberculosis treatment. The final multivariate logistic regression model demonstrated that the use of fluconazole, malnutrition and the subject being classified as a phenotypically slow acetylator increased the risk of hepatotoxicity significantly. The incidence of hepatotoxicity during treatment for tuberculosis in PLWHA was high. Those classified as phenotypically slow acetylators and as malnourished should be targeted for specific care to reduce the risk of hepatotoxicity during treatment for tuberculosis. The use of fluconazole should be avoided during tuberculosis treatment in PLWHA.

Genotype and allele frequencies of isoniazid-metabolizing enzymes NAT2 and GSTM1 in Latvian tuberculosis patients

Pharmacogenomic testing of tuberculosis drug-metabolizing enzyme genes was proposed as a strategy to identify patients at risk for suboptimal responses to medications. However, variations of the genotype frequencies among ethnic groups exist and new alleles are been identified. The aim of this study was to identify polymorphisms of genes encoding metabolic enzymes NAT2 and GSTM1 in tuberculosis patients in Latvia and to estimate the frequency of NAT2 slow acetylator and GSTM1 null genotypes. In total, 85 DNA samples were genotyped, all individuals were Caucasian. An ethnic heterogeneity reflecting the multiethnic population of the country was observed. 49 patients were Latvians, 30 were Russians and 6 of other ethnicity. In total, 7 NAT2 alleles were identified: *4, *5, *6, *7, *11, *12, * and *13. The most frequent was the slow acetylation allele NAT2*6 (frequency 0.388) followed by the slow acetylation allele NAT2*5 and the rapid acetylation allele NAT2*4 (frequencies 0.306 and 0.194, respectively). The predominance of slow (51.8%) and intermediate (43.5%) acetylators compared with rapid acetylators (4.7%) was observed. The GSTM1 null genotype was detected in 48.2% of tuberculosis patients. When subgroup analysis was performed according to ethnicity, the results showed that neither NAT2 allele frequencies nor GSTM1 null genotype frequency did not differ significantly in TB patients of Latvian or Russian ethnicity. Overall, genotyping results were similar with previous reports of a NAT2 gene variation and GSTM1 null genotype frequency in Caucasians. Our findings have a contribution for the pharmacogenetics-based tuberculosis therapy in Latvia in future.

Update meta-analysis of the CYP2E1 RsaI/PstI and DraI polymorphisms and risk of antituberculosis drug-induced hepatotoxicity: evidence from 26 studies

WHAT IS KNOWN AND OBJECTIVE

Several studies have investigated the association of the CYP2E1 RsaI/PstI and/or DraI polymorphisms with susceptibility to antituberculosis drug-induced hepatotoxicity (ATDH), but the results have been inconsistent. Therefore, we performed a large meta-analysis to determine a more precise estimation of this relationship.

METHODS

The PubMed, EMBASE, China National Knowledge Infrastructure and Chinese Biomedical Literature databases were systematically searched to identify relevant studies. Meta-analyses based on the entire population and subgroups were performed to examine the association between CYP2E1 polymorphisms and susceptibility to ATDH. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of the associations.

RESULTS AND DISCUSSION

Twenty-six studies with a total of 7423 participants were analysed. The overall ORs of relevant studies demonstrated that the CYP2E1 RsaI/PstI C1/C1 genotype was associated with an elevated risk of ATDH (OR = 1·32, 95% CI 1·03-1·69, P = 0·027), but for the DraI polymorphism there was no increase in risk (OR = 1·05, 95% CI 0·80-1·37, P = 0·748). In subgroup analyses of the RsaI/PstI polymorphism, significant results were found in East Asians, patients who used isoniazid + rifampicin + pyrazinamide + ethambutol and patients with twice the upper limit of normal as the minimum standard for defining ATDH.

WHAT IS NEW AND CONCLUSION

This meta-analysis suggests that there is an increased risk of ATDH in individuals carrying the C1/C1 genotype of the CYP2E1 RsaI/PstI polymorphism. However, no association was found for the DraI polymorphism.

Prevalence, risk factors, management, and treatment outcomes of first-line antituberculous drug-induced liver injury: a prospective cohort study

PURPOSE

Antituberculosis drug-induced liver injury (ATDILI) is one of the most deleterious side effects associated with chemotherapy against tuberculosis (TB). In this study, our objective was to determine the incidence, risk factors, and management of ATDILI and analyze its impact on the treatment outcome in patients receiving standard anti-TB chemotherapy.

METHODS

A prospective cohort study of ATDILI prevalence was conducted in 938 enrolled patients of the 1426 TB cases in Shanghai from March 2011 to September 2012. Patients were followed up until February 2014. Univariate and multivariate logistic regression analyses were used to determine the risk factors of ATDILI. Successful therapeutic outcome, rates of drug resistance conversion, sputum smear/culture conversion, and lung cavity closure were analyzed.

RESULTS

Hepatitis B surface antigen/hepatitis B e antigen-positive hepatitis B carriers, complicated with systemic lupus erythematosus, albumin ≤ 25 g/L, and chronic alcoholism were independent risk factors for ATDILI. Of the 121 cases with ATDILI (incidence rate of 12.9%), 84 (69.4%) used modified anti-TB therapy after recovery of liver function. Compared with the non-ATDILI group, patients with ATDILI exhibited remarkably decreased lung cavity closure rate (84.6% vs. 93.0%, P < 0.001) along with significantly reduced sputum smear/culture conversion rate (85.4% vs. 94.0%, P < 0.001).

CONCLUSIONS

Our findings indicated that 12.9% patients developed ATDILI during standard anti-TB therapy, resulting in poor therapeutic outcome. Hepatitis B carriers with systemic lupus erythematosus, albumin ≤ 25 g/L, and chronic alcoholism manifested increased risks for ATDILI. Copyright © 2016 John Wiley & Sons, Ltd.

Might isoniazid plasma exposure be a valuable predictor of drug-related hepatotoxicity risk among adult patients with TB?

OBJECTIVES

To investigate the relationship between isoniazid plasma exposure and the likelihood of elevation of ALT (≥51 IU/L) among adult patients with TB.

METHODS

A retrospective observational study was conducted in patients who underwent periodic monitoring of hepatic function and in whom pharmacokinetic data were collected. Monte Carlo simulation was performed with the intent of identifying the probability of achieving an AUC24 greater than the identified threshold of hepatotoxicity with different dosing regimens (2.5, 5.0 and 7.5 mg/kg/day).

RESULTS

Forty-one out of 185 evaluable patients (22.2%) had an ALT elevation. A mild correlation between isoniazid AUC0-24 and ALT increase was observed (Spearman's ρ = 0.34, P < 0.001). Patients with ALT ≥51 IU/L showed significantly higher isoniazid exposure than those with ALT <51 IU/L (mean AUC24 of 58.33 versus 31.28 mg·h/L, P < 0.001). The probabilities of ALT elevation were 0.82 and 0.12 for isoniazid AUC24 ≥55.0 and <55.0 mg·h/L, respectively. Use of a logistic regression model estimated a likelihood of developing hepatotoxicity of 0.5 and 0.9 when in the presence of an isoniazid AUC24 of 53.7 and 70.0 mg·h/L, respectively. Simulation showed that the standard isoniazid 5 mg/kg daily dose gave a probability of ALT increase of 0.46 for slow acetylators and 0.03 for rapid acetylators.

CONCLUSIONS

Plasma isoniazid exposure might be a valuable predictor of drug-related hepatotoxicity. Early assessment of isoniazid exposure at the beginning of treatment might allow prompt dosage reduction among those patients who are experiencing drug overexposure, thus containing the risk of hepatotoxicity occurrence.

Susceptibility of N-acetyltransferase 2 slow acetylators to antituberculosis drug-induced liver injury: a meta-analysis

AIM

This study aimed to evaluate the association between N-acetyltransferase 2 (NAT2) gene polymorphisms and the risk of antituberculosis drug-induced liver injury (ATLI).

MATERIALS & METHODS

A meta-analysis was performed including 27 studies with 1289 cases and 5462 controls. Odds ratio with 95% CI was used to evaluate the strength of association.

RESULTS

Our meta-analysis found that NAT2 slow acetylators were associated with increased risk of ATLI compared with fast and intermediate acetylators when standard dose of isoniazid was administrated (odds ratio: 3.08; 95% CI: 2.29-4.15).

CONCLUSION

Individuals with NAT2 slow acetylators may have increased risk of ATLI when standard dose of isoniazid was used. Detection of NAT2 genotype may benefit to the prevention of ATLI.

Isoniazid-induced polyneuropathy in a tuberculosis patient - implication for individual risk stratification with genotyping?

BACKGROUND

Development of polyneuropathy (PNP) under treatment for tuberculosis (TB), including isoniazid (INH), is a highly relevant adverse drug effect. The NAT2 acetylation status is a predictor of potential toxic effects of INH. The question as to whether individual risk stratification by genotyping is useful to avoid suffering of patients and to lower costs for the health care system is of considerable clinical importance.

CASE PRESENTATION

After drug treatment for TB, including INH, a 23-year-old man developed severe PNP. During the treatment, laboratory results have been indicating incipient liver and renal injury. Later, molecular genetic analyses were performed and revealed a variation in the NAT2 gene and the c1/c2 genotype of the CYP2E1 gene, both described to contribute to an elevated risk for anti-tuberculostatic-induced liver damages (ATIL).

CONCLUSION

The combination of metabolizer genotypes should be taken into account as a cause for toxic effects and the development of PNP. Individual genotyping, performed before medication or at least if an elevation of liver parameters is observed, may reduce the risk of severe cases of PNP by early adjustment of treatment. Our case study indicates that evaluation of individual risk stratification with systematic pharmacogenetic genotyping of metabolizer gene combinations in the context of TB treatment should be addressed in clinical studies with larger cohorts.

Impact of glutathione S-transferase M1 and T1 on anti-tuberculosis drug-induced hepatotoxicity in Chinese pediatric patients

Background

Anti-tuberculosis drug induced hepatotoxicity (ATDH) is a major adverse drug reaction associated for anti-tuberculosis therapy. The glutathione S-transferases (GST) plays a crucial role in the detoxification of hepatotoxic metabolites of anti-tuberculosis drugs.An association between GSTM1/GSTT1 null mutations and increased risk of ATDH has been demonstrated in adults. Given the ethnic differences and developmental changes, our study aims to investigate the potential impacts of GSTM1/GSTT1genotypes on the development of ATDH in Han Chinese children treated with anti-tuberculosis therapy.

Methods

Children receiving anti-tuberculosis therapy with or without evidence of ATDH were considered as the cases or controls, respectively. The GSTM1 and GSTT1 genotyping were performed using the polymerase chain reaction.

Results

One hundred sixty-three children (20 cases and 143 controls) with a mean age of 4.7 years (range: 2 months-14.1 years) were included. For the GSTM1, 14 (70.0%) cases and 96 (67.1%) controls had homozygous null mutations. For the GSTT1, 13 (65.0%) cases and 97 (67.8%) controls had homozygous null mutations. Neither the GSTM1, nor the GSTT1 polymorphism was significantly correlated with the occurrence of ATHD.

Conclusion

Ourresults did not support the GSTM1 and GSTT1 polymorphisms as the predictors of ADTH in Chinese Han children treated with anti-tuberculosis drugs. An age-related association between pharmacogenetics and ATHD need to be confirmed in the further study.