Determination of NAT2 Genotypes in a Cohort of Patients with Suspected TB in the State of Rio de Janeiro.

The human N-acetyltransferase 2 enzyme, encoded by the NAT2 gene, plays an important role in the metabolism of isoniazid, the main drug used to treat tuberculosis. The interindividual variation in the response of patients to drug treatment for tuberculosis may be responsible for the occurrence of unfavorable outcomes. The presence of polymorphisms in genes associated with the metabolism and transport of drugs, receptors, and therapeutic targets has been identified as a major determinant of this variability. The objective of this study was to identify the genetic profile of NAT2 in the study population. Using the obtained genomic DNA followed by PCR amplification and sequencing, the frequency of nine SNPs as well as alleles associated with slow (47.9%), intermediate (38.7%), and fast acetylation phenotypes (11.3%), in addition to those whose phenotype has not yet been characterized (2.1%), was estimated. The NAT2*5B allele was identified more frequently (31.3%). The description of SNPs in pharmacogenes and the establishment of their relationship with the pharmacokinetics of an individual offer an individualized approach that allows us to reduce the unfavorable outcomes of a therapy, ensure better adherence to treatment, prevent the emergence of MDR strains, reduce the cost of treatment, and improve the quality of patients' lives.

Experimental Infection of Rhodnius prolixus (Hemiptera, Triatominae) with Mycobacterium leprae Indicates Potential for Leprosy Transmission.

Leprosy is a chronic dermato-neurological disease caused by infection with Mycobacterium leprae. In 2013 almost 200,000 new cases of leprosy were detected around the world. Since the first symptoms take from years to decades to appear, the total number of asymptomatic patients is impossible to predict. Although leprosy is one of the oldest records of human disease, the mechanisms involved with its transmission and epidemiology are still not completely understood. In the present work, we experimentally investigated the hypothesis that the mosquitoes Aedes aegypti and Culex quinquefasciatus and the hemiptera Rhodnius prolixus act as leprosy vectors. By means of real-time PCR quantification of M. leprae 16SrRNA, we found that M. leprae remained viable inside the digestive tract of Rhodnius prolixus for 20 days after oral infection. In contrast, in the gut of both mosquito species tested, we were not able to detect M. leprae RNA after a similar period of time. Inside the kissing bug Rhodnius prolixus digestive tract, M. leprae was initially restricted to the anterior midgut, but gradually moved towards the hindgut, in a time course reminiscent of the life cycle of Trypanosoma cruzi, a well-known pathogen transmitted by this insect. The maintenance of M. leprae infectivity inside the digestive tract of this kissing bug is further supported by successful mice footpad inoculation with feces collected 20 days after infection. We conclude that Rhodnius prolixus defecate infective M. leprae, justifying the evaluation of the presence of M. leprae among sylvatic and domestic kissing bugs in countries endemic for leprosy.

Experimental infection of Rhodnius prolixus (Hemiptera, Triatominae) with Mycobacterium leprae indicates potential for leprosy transmission

Leprosy is a chronic dermato-neurological disease caused by infection with Mycobacterium leprae. In 2013 almost 200,000 new cases of leprosy were detected around the world. Since the first symptoms take from years to decades to appear, the total number of asymptomatic patients is impossible to predict. Although leprosy is one of the oldest records of human disease, the mechanisms involved with its transmission and epidemiology are still not completely understood. In the present work, we experimentally investigated the hypothesis that the mosquitoes Aedes aegypti and Culex quinquefasciatus and the hemiptera Rhodnius prolixus act as leprosy vectors. By means of real-time PCR quantification of M. leprae 16SrRNA, we found that M. leprae remained viable inside the digestive tract of Rhodnius prolixus for 20 days after oral infection. In contrast, in the gut of both mosquito species tested, we were not able to detect M. leprae RNA after a similar period of time. Inside the kissing bug Rhodnius prolixus digestive tract, M. leprae was initially restricted to the anterior midgut, but gradually moved towards the hindgut, in a time course reminiscent of the life cycle of Trypanosoma cruzi, a well-known pathogen transmitted by this insect. The maintenance of M. leprae infectivity inside the digestive tract of this kissing bug is further supported by successful mice footpad inoculation with feces collected 20 days after infection. We conclude that Rhodnius prolixus defecate infective M. leprae, justifying the evaluation of the presence of M. leprae among sylvatic and domestic kissing bugs in countries endemic for leprosy.

Genetic polymorphisms of NAT2, CYP2E1 and GST enzymes and the occurrence of antituberculosis drug-induced hepatitis in Brazilian TB patients.

Isoniazid (INH), one of the most important drugs used in antituberculosis (anti-TB) treatment, is also the major drug involved in hepatotoxicity. Differences in INH-induced toxicity have been attributed to genetic variability at several loci, such as NAT2, CYP2E1, GSTM1 and GSTT1, that code for drug-metabolising enzymes. Our goal was to examine the polymorphisms in these enzymes as susceptibility factors to anti-TB drug-induced hepatitis in Brazilian individuals. In a case-control design, 167 unrelated active tuberculosis patients from the University Hospital of the Federal University of Rio de Janeiro, Brazil, were enrolled in this study. Patients with a history of anti-TB drug-induced acute hepatitis (cases with an increase to 3 times the upper limit of normal serum transaminases and symptoms of hepatitis) and patients with no evidence of anti-TB hepatic side effects (controls) were genotyped for NAT2, CYP2E1, GSTM1 and GSTT1 polymorphisms. Slow acetylators had a higher incidence of hepatitis than intermediate/rapid acetylators [22% (18/82) vs. 9.8% (6/61), odds ratio (OR), 2.86, 95% confidence interval (CI), 1.06-7.68, p = 0.04). Logistic regression showed that slow acetylation status was the only independent risk factor (OR 3.59, 95% CI, 2.53-4.64, p = 0.02) for the occurrence of anti-TB drug-induced hepatitis during anti-TB treatment with INH-containing schemes in Brazilian individuals.

Genetic polymorphisms of NAT2, CYP2E1 and GST enzymes and the occurrence of antituberculosis drug-induced hepatitis in Brazilian TB patients

Isoniazid (INH), one of the most important drugs used in antituberculosis (anti-TB) treatment, is also the major drug involved in hepatotoxicity. Differences in INH-induced toxicity have been attributed to genetic variability at several loci, such as NAT2, CYP2E1, GSTM1 and GSTT1, that code for drug-metabolising enzymes. Our goal was to examine the polymorphisms in these enzymes as susceptibility factors to anti-TB drug-induced hepatitis in Brazilian individuals. In a case-control design, 167 unrelated active tuberculosis patients from the University Hospital of the Federal University of Rio de Janeiro, Brazil, were enrolled in this study. Patients with a history of anti-TB drug-induced acute hepatitis (cases with an increase to 3 times the upper limit of normal serum transaminases and symptoms of hepatitis) and patients with no evidence of anti-TB hepatic side effects (controls) were genotyped for NAT2, CYP2E1, GSTM1 and GSTT1 polymorphisms. Slow acetylators had a higher incidence of hepatitis than intermediate/rapid acetylators [22 percent (18/82) vs. 9.8 percent (6/61), odds ratio (OR), 2.86, 95 percent confidence interval (CI), 1.06-7.68, p = 0.04). Logistic regression showed that slow acetylation status was the only independent risk factor (OR 3.59, 95 percent CI, 2.53-4.64, p = 0.02) for the occurrence of anti-TB drug-induced hepatitis during anti-TB treatment with INH-containing schemes in Brazilian individuals.

Influência da variabilidade genética humana dos genes NAT2, CYP2E1, GSTM1 e GSTT1 na ocorrência de reações adversas hepáticas induzidas pela isoniazida em pacientes com tuberculose ativa / Influence of human genetic variability of genes NAT2, CYP2E1, GSTM1 and GSTT1 in the occurrence of hepatic adverse reactions induced by isoniazid in patients with active tuberculosis

A isoniazida (INH), uma das principais drogas usadas no esquema de tratamento de primeira linha anti-tuberculose (anti-TB), tem sido associada à intensificação de efeitos adversos principalmente hepáticos. Sabe-se hoje, que variações polimórficas em genes humanos codificando enzimas envolvidas na biotransformação de diferentes fármacos podem contribuir para diferenças interindividuais na resposta farmacológica ou toxicológica de várias drogas estando diretamente relacionadas aos desfechos de falha terapêutica e reações adversas a drogas (ADRs). A INH é geralmente administrada de forma oral sendo metabolizada por enzimas hepáticas. O mecanismo de lesão hepatocelular induzido pela isoniazida envolve as enzimas de biotransformação N-acetiltransferase 2 e a mono-oxigenase CYP450 2E1. Mutações pontuais na região codificante de NAT2 são capazes de alterar a atividade de acetilação da enzima gerando três possíveis fenótipos: acetiladores lentos, intermediários e rápidos. Os indivíduos que apresentam uma acetilação lenta acumulam intermediários hepatotóxicos levando a ocorrência de ADRs. Outra classe de enzimas cuja participação na biotransformação da isoniazida vem sendo especulada é a glutationa S-transferase (GST). Considerando a importância das variantes alélicas dos genes envolvidos na metabolização da isoniazida e que suas frequências variam entre as diferentes etnias este trabalho teve como objetivos principais: (i) análise descritiva da distribuição dos alelos de NAT2 em duas regiões diferentes do Brasil: (ii) identificação de novas mutações e caracterização haplotípica de novos alelos de NAT2 bem como análise estrutural da influência dessas alterações na estrutura protéica de NAT2 e (iii) estudo de associação, caso-controle, entre as variáveis genéticas presentes nos genes que codificam para NAT2, CYP2E1 e GSTs humanas, com a ocorrência de reações adversas em pacientes com TB em tratamento com esquemas contendo isoniazida. Dezessete SNPs previamente descritos foram identificados na população estudada, dos quais, sete: 191G maior que A; 282C maior que T; 341T maior que C; 481C maior que T; 590G maior que A; 803 maior que G e 857G maior que A são os mais frequentes na população mundial. Adicionalmente, seis mutações novas foram identificadas e sete novos alelos de NAT2 circulantes no Rio de Janeiro e/ou Goiás foram caracterizados através de clonagem e resequenciamento e experimentos de modelagem molecular. Nossos resultados mostraram a predominância de alelos de NAT2 associados com o fenótipo de acetilação lenta em indivíduos brasileiros e que a distribuição desses alelos varia significativamente de acordo com a região brasileira estudada. Além disso, fomos capazes de constatar que os acetiladores lentos apresentaram um risco significativamente maior em desenvolver hepatotoxicidade (OR: 2,62; IC 95por cento: 1,75-3.49; p igual 0.03) ou hepatite medicamentosa (OR: 3,59; IC 95por cento: 2,53-4.64; p igual 0,02) quando comparados aos acetiladores intermediários/rápidos. Por outro lado, não observamos qualquer relação entre polimorfismos nos genes CYP2E1, GSTM1 e GSTT1 com a ocorrência de ADRs durante tratamento anti-TB. Sendo assim, nossos resultados sugerem...colaterais.