Genetic variations of NAT2 and CYP2E1 and isoniazid hepatotoxicity in a diverse population

OUP accepted manuscript

Drug-induced nephrotoxicity is a common problem in clinical medicine and the frequency of drug-related acute and chronic kidney dysfunction worldwide. One of them is anti-tuberculosis (TB) drugs that cause renal function impairment during TB treatment. Medicinal plants contain bioactive compounds that are capable for treating drug or toxin-induced renal disorders. The aim of the present study was to assess the protective effect of the ethanolic extract of Nigella sativa seeds (NS) against anti-TB drugs (ATDs) induced nephrotoxicity in Wistar albino rats. Rats were treated with ATDs for 12weeks (3 alternative days in a week). Supplementation with 125mg NS/kg, p.o. was administered to the experimental rats for 12weeks (3 alternative days in a week considering next day of ATDs treatment). The results demonstrated that NS treatment protected against renal damage induced by ATDs, as evidenced by the reduction in serum urea, creatinine, uric acid, urea nitrogen levels, pro-inflammatory markers (TNF-α and IL-6), whereas improvement in histological tubular and glomerular damage. In addition, NS enhanced the antioxidant enzyme activity (superoxide dismutase and catalase) and decreased the lipid peroxidation and glutathione level in the kidney. In conclusion, NS could reduce chronic nephritis in ATDs treated group through suppressing inflammation and oxidative stress. It suggests that NS can be used as supplementary preventive and protective drug against kidney injury during anti-TB treatment.

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.

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.

Pharmaceutical care for patients with anti-tuberculosis drug induced liver injury

Drug induced liver injury is one of the most important and serious adverse effects of anti-tuberculosis drugs. The clinical features of anti-tuberculosis drug induced liver injury (ATLI) ranges from asymptomatic alanine aminotransferase (ALT) elevations to acute hepatitis symptoms, and the mortality cases associated with liver failure are not rare. ATLI diminishes the effectiveness of anti-tuberculosis treatment, as they may cause non-adherence, and further leads to treatment interruption, recurrence or the emergence of drug resistance. The aim of this paper is to discuss the clinical features, mechanisms, risk factors and treatment principles for ATLI. In addition, the reasonable adjustment of anti-tuberculosis treatment and implementation of pharmaceutical care are also reviewed so as to provide thoughts on the prevention, diagnosis and timely intervention of ATLI.

Distribution of allelic and genotypic frequencies of NAT2 and CYP2E1 variants in Moroccan population

Background

Several pathogenesis and genetic factors influence predisposition to antituberculosis drug-induced hepatotoxicity (ATDH) especially for isoniazid (INH). However, the major susceptibility genes for ATDH are N-acetyltransferase 2 (NAT2) and cytochrome P450 2E1 (CYP2E1). NAT2 gene determines the individual’s acetylator status (fast, intermediate or slow) to metabolize drugs and xenobiotics, while CYP2E1 c1/c1 genotype carriers had an increased risk of ATDH.

Polymorphisms of the NAT2 and CYP2E1 genes vary remarkably among the populations of different ethnic origins.

The aim of this study was to determine, for the first time, the frequency of slow acetylators in Moroccan population by genotyping of NAT2 gene variants and determining the genotype c1/c1 for CYP2E1 gene, in order to predict adverse effects of Tuberculosis treatment, particularly hepatotoxicity.

Results

The frequencies of specific NAT2 alleles were 53%, 25%, 2% and 4% for NAT2*5, NAT2*6, NAT2*7 and NAT2*14 respectively among 163 Moroccan studied group. Genotyping of CYP2E1 gene, by real-time polymerase chain reaction using TaqMan probes, revealed frequencies of 98.5% for c1/c1 and 1.5% for c1/c2 among 130 Moroccan studied group.

Conclusion

The most prevalent genotypes of NAT2 gene in Moroccans are those which encode slow acetylation phenotype (72.39%), leading to a high risk of ATDH. Most Moroccans are homozygous for c1 allele of CYP2E1 gene which aggravates hepatotoxicity in slow acetylators.

This genetic background should be taken into account in determining the minimum dose of INH needed to treat Moroccan TB patients, in order to decrease adverse effects.

CYP2E1, GSTM1 and GSTT1 genetic polymorphisms and susceptibility to antituberculosis drug-induced hepatotoxicity: a nested case-control study

WHAT IS KNOWN AND OBJECTIVE

The pathogenic mechanism of antituberculosis drug-induced hepatotoxicity (ATDH) is thought to involve drug-metabolizing enzymes including N-acetyl transferase2 (NAT2), cytochrome P4502E1 (CYP2E1) and glutathione S-transferase (GST) M1, T1. The associations between genetic polymorphisms of those genes and ATDH have been reported but with inconsistent results. Moreover, most studies were hospital-based retrospective studies and not prospective. We aimed to investigate possible associations of CYP2E1, GSTM1 and GSTT1 genetic polymorphisms with ATDH using a more robust case-control study nested in a population-based prospective antituberculosis treatment cohort.

METHODS

A total of 4304 patients with smear-positive tuberculosis (TB) who received standard short-course chemotherapy were monitored for 6-9 months. Incidence density sampling method was adopted to select controls and 4 : 1 matched with each ATDH cases by age (± 5 years), sex, treatment history, disease severity and drug dosage. The CYP2E1, GSTM1 and GSTT1 polymorphisms were genotyped using PCR-RFLP and multiplex PCR methods. Conditional logistic regression model was used to calculate odds ratio (OR) and 95% confidence interval (CI), as well as corresponding P-values.

RESULTS AND DISCUSSION

A total of 89 ATDH cases and 356 controls were included in this study. There was no statistically significant association between CYP2E1 RsaI c1/c1 genotype or DraI C/C genotype and ATDH (OR = 0·99, 95% CI:0·62-1·59; OR = 1·13, 95% CI: 0·40-3·20, respectively) compared with CYP2E1 RsaI c1/c2 or c2/c2 genotypes or DraI D/D genotype, or between GSTM1/GSTT1 null genotypes and ATDH (OR = 1·22, 95% CI: 0·76-1·96; OR = 0·96, 95% CI: 0·60-1·52, respectively) compared with non-null genotypes.

WHAT IS NEW AND CONCLUSION

This is the first study of the involvement of CYP2E1, GSTM1 and GSTT1 genetic polymorphisms in ATDH using a nested case-control population-based prospective cohort design. We could not confirm positive associations of genetic polymorphisms of CYP2E1 RsaI, CYP2E1 DraI, GSTM1 null and GSTT1 null with ATDH reported by various groups, in our Chinese TB population.