Whole genome sequence of Mycobacterium kansasii isolates of the genotype 1 from Brazilian patients with pulmonary disease demonstrates considerable heterogeneity.

Mycobacterium kansasii is an opportunistic pathogen and one of the most commonly encountered species in individuals with lung disease. We here report the complete genome sequence of 12 clinical isolates of M. kansasii from patients with pulmonary disease in Brazil.

Genetic Characterization and Population Structure of Drug-Resistant Mycobacterium tuberculosis Isolated from Brazilian Patients Using Whole-Genome Sequencing.

The present study aimed to determine the genetic diversity of isolates of Mycobacterium tuberculosis (Mtb) from presumed drug-resistant tuberculosis patients from several states of Brazil. The isolates had been submitted to conventional drug susceptibility testing for first- and second-line drugs. Multidrug-resistant (MDR-TB) (54.8%) was the most frequent phenotypic resistance profile, in addition to an important high frequency of pre-extensive resistance (p-XDR-TB) (9.2%). Using whole-genome sequencing (WGS), we characterized 298 Mtb isolates from Brazil. Besides the analysis of genotype distribution and possible correlations between molecular and clinical data, we determined the performance of an in-house WGS pipeline with other online pipelines for Mtb lineages and drug resistance profile definitions. Sub-lineage 4.3 (52%) was the most frequent genotype, and the genomic approach revealed a p-XDR-TB level of 22.5%. We detected twenty novel mutations in three resistance genes, and six of these were observed in eight phenotypically resistant isolates. A cluster analysis of 170 isolates showed that 43.5% of the TB patients belonged to 24 genomic clusters, suggesting considerable ongoing transmission of DR-TB, including two interstate transmissions. The in-house WGS pipeline showed the best overall performance in drug resistance prediction, presenting the best accuracy values for five of the nine drugs tested. Significant associations were observed between suffering from fatal disease and genotypic p-XDR-TB (p = 0.03) and either phenotypic (p = 0.006) or genotypic (p = 0.0007) ethambutol resistance. The use of WGS analysis improved our understanding of the population structure of MTBC in Brazil and the genetic and clinical data correlations and demonstrated its utility for surveillance efforts regarding the spread of DR-TB, hopefully helping to avoid the emergence of even more resistant strains and to reduce TB incidence and mortality rates.

Phylogenomic and genomic analysis reveals unique and shared genetic signatures of Mycobacterium kansasii complex species.

Species belonging to the Mycobacterium kansasii complex (MKC) are frequently isolated from humans and the environment and can cause serious diseases. The most common MKC infections are caused by the species M. kansasii (sensu stricto), leading to tuberculosis-like disease. However, a broad spectrum of virulence, antimicrobial resistance and pathogenicity of these non-tuberculous mycobacteria (NTM) are observed across the MKC. Many genomic aspects of the MKC that relate to these broad phenotypes are not well elucidated. Here, we performed genomic analyses from a collection of 665 MKC strains, isolated from environmental, animal and human sources. We inferred the MKC pangenome, mobilome, resistome, virulome and defence systems and show that the MKC species harbours unique and shared genomic signatures. High frequency of presence of prophages and different types of defence systems were observed. We found that the M. kansasii species splits into four lineages, of which three are lowly represented and mainly in Brazil, while one lineage is dominant and globally spread. Moreover, we show that four sub-lineages of this most distributed M. kansasii lineage emerged during the twentieth century. Further analysis of the M. kansasii genomes revealed almost 300 regions of difference contributing to genomic diversity, as well as fixed mutations that may explain the M. kansasii's increased virulence and drug resistance.

Mycobacterium fragae sp. nov., a non-chromogenic species isolated from human respiratory specimens.

Three isolates of a slow-growing, non-chromogenic mycobacterium were grown from three sputum samples of a patient from the north-eastern Ceará state in Brazil. Identification at species level could not be obtained with PCR restriction analysis of the hsp65 gene. In order to characterize the isolates we carried out phenotypic and genotypic tests. We sequenced the nearly complete 16S rRNA gene and obtained partial sequences of the hsp65 (encoding the hypervariable region of the 65 kDa heat-shock protein) and rpoB (encoding the beta-subunit of RNA polymerase) genes. The three isolates turned out to be identical and most closely related to the species Mycobacterium celatum and Mycobacterium kyorinense. The results, however, showed significant differences between these species and the isolates studied, which led us to consider them members of a novel species for which we propose the name Mycobacterium fragae. The type strain is HF8705(T) ( = Fiocruz-INCQS/CMRVS P4051(T) = DSM 45731(T)).

First isolation of Mycobacterium kyorinense from clinical specimens in Brazil.

In this article, the first isolation of Mycobacterium kyorinense specimens in Brazil is described. M. kyorinense is a recently identified species, with a few strains reported only in Japan. The Brazilian isolates were initially identified as Mycobacterium celatum by PCR restriction enzyme pattern analysis (PRA) with hsp65. However, biochemical tests indicated the same profile of M. kyorinense and distinguished them from M. celatum and Mycobacterium branderi. The sequencing of the hsp65, rpoB, and 16S rRNA genes allowed the accurate identification of isolates as M. kyorinense.

Pulmonary Granuloma Is Not Always the Tuberculosis Hallmark: Pathology of Tuberculosis Stages in New World and Old World Monkeys Naturally Infected with the Mycobacterium tuberculosis Complex.

We present the pathology of monkeys naturally infected with Mycobacterium tuberculosis complex from five different colonies in Rio de Janeiro, Brazil. On the basis of gross and histopathological findings, the lesions were classified into chronic-active, extrapulmonary, early-activation or latent-reactivation stages. Typical granulomatous pneumonia was seen in 46.6% of cases (six rhesus monkeys [Macaca mulatta] and one Uta Hick's bearded saki [Chiropotes utahickae]). The absence of pulmonary granulomas did not preclude a diagnosis of tuberculosis (TB): classical granulomatous pneumonia was observed in the chronic-active and latent-reactivation stages but not in the extrapulmonary and early-activation stages. The early-activation stage was characterized by interstitial pneumonia with a predominance of foamy macrophages and molecular and immunohistochemical evidence of M. tuberculosis complex infection. TB should be considered as a cause of interstitial pneumonia in New World Monkeys. We recommend the use of immunohistochemistry and molecular analysis for diagnosis of TB, even when typical macroscopic or histological changes are not observed.

Inhibitory effect of the alkaloid warifteine purified from Cissampelos sympodialis on B lymphocyte function in vitro and in vivo.

The aqueous fraction of the ethanolic extract of the plant CISSAMPELOS SYMPODIALIS (Menispermaceae) was previously described to inhibit B cell function. The alkaloid warifteine is the major component of this extract. In the present study we investigated the effect of warifteine on B lymphocyte function and characterized its mechanism of action. Purified splenic murine B lymphocytes were stimulated with either Toll-like receptor (TLR) ligands (LPS, Pam (3)Cys and CpG oligodeoxynucleotides) or anti-IgM antibody and the effect of warifteine on B cell response was investigated. Warifteine inhibited both the proliferative response and immunoglobulin (Ig) secretion induced by these stimuli. Kinetics studies demonstrated that warifteine blocked B cell function even when added after 24 h of a 72 h culture. The inhibitory effect of warifteine was also detected in cultures activated by phorbol myristate acetate and calcium ionophore. We investigated the signal transduction pathways blocked by warifteine. It did not modify the total protein phosphorylation pattern in LPS and anti-IgM-stimulated B cell cultures. It did, however, decrease the rise in intracellular calcium levels, the phosphorylation of the mitogen activated protein kinase (MAPK) ERK and the intranuclear levels of the transcription factor NFkappaB. Warifteine also induced an increase in cAMP and its effect on LPS-induced proliferation was mimicked by the control adenyl cyclase activator forskolin. IN VIVO Ig production induced by the TI-2 antigen TNP-ficoll was also inhibited by warifteine. Taking together, our data suggest that warifteine is a potent inhibitor of B cell response both IN VITRO and IN VIVO and that this effect may be due to the induction of increased intracellular cAMP levels, suggesting that this substance may be useful as a modulator of B cell function.

Discovery of a novel Mycobacterium asiaticum PRA-hsp65 pattern.

Twenty-one pulmonary sputum samples from nine Brazilian patients were analyzed by the PRA-hsp65 method for identification of Mycobacterium species and the results were compared by sequencing. We reported a mutation at the position 381, that generates a suppression cutting site in the BstEII enzyme, thus leading to a new PRA-hsp65 pattern for M. asiaticum identification.

Drug susceptibility profile of Mycobacterium kansasii clinical isolates from Brazil.

OBJECTIVES: Mycobacterium kansasii (M. kansasii) pulmonary infection can cause disease with clinical and radiological features similar to tuberculosis. Failure to treat M. kansasii infection is usually associated with resistance; to increase the chance of successful treatment it is important to identify the species and know the susceptibility profile. This study aimed to evaluate the antimycobacterial susceptibility profiles of M. kansasii isolates from Brazil. METHODS: Sixty-nine M. kansasii isolates from 69 patients were identified by partial sequencing of the hsp65 gene, and their susceptibility profiles were analysed by minimal inhibitory concentration (MIC) assays. RESULTS: From 69 isolates, 68 showed susceptibility to clarithromycin, amikacin, and moxifloxacin. Most strains showed high rates of resistance to trimethoprim-sulfamethoxazole and ciprofloxacin. Resistance to rifampicin and ethambutol was found in 12% and 25% of isolates, respectively. CONCLUSIONS: Worrying results were found regarding susceptibility to some drugs used as first-line agents in the treatment of diseases caused by M. kansasii.

Factors associated with loss to follow-up and death in cases of drug-resistant tuberculosis (DR-TB) treated at a reference center in Rio de Janeiro, Brazil. / Fatores associados ao abandono e ao óbito de casos de tuberculose drogarresistente (TBDR) atendidos em um centro de referência no Rio de Janeiro, Brasil.

Drug-resistant tuberculosis (DR-TB) poses a serious threat to tuberculosis (TB) control in Brazil and worldwide. The current study investigated factors associated with loss to follow-up and death in the course of treatment for DR-TB in a tertiary reference center in the city of Rio de Janeiro, Brazil. This was a retrospective cohort study of cases reported to the Information System on Special Treatments for Tuberculosis (SITETB) from January 1, 2012, to December 31, 2013. A total of 257 patients were reported to the SITETB and initiated treatment for DR-TB. Of this total, 139 (54.1%) achieved treatment success as the outcome, 54 (21%) were lost to follow-up, and 21 (8.2%) died. Following a multiple multinomial logistic regression analysis, the age bracket older than 50 years was the only protective factor against loss to follow-up, whereas less than eight years of schooling and reentry after loss to follow-up were considered risk factors. Reentry after loss to follow-up, relapse, and treatment failure appeared as risk factors. Our data reinforce the concept that loss to follow-up in drug-resistant tuberculosis is a serious public health problem, and that adequate follow-up of treatment is necessary in patients with this history and low schooling. A social support network for patients is also indispensable for avoiding unfavorable outcomes.

A tuberculose drogarresistente (TBDR) representa hoje uma grave ameaça aos avanços no controle da tuberculose (TB) no Brasil e no mundo. Neste estudo, investigam-se fatores associados ao abandono e ao óbito de casos em tratamento para TBDR, em um centro de referência terciária do Município do Rio de Janeiro, Brasil. Trata-se de um estudo de coorte retrospectiva, a partir dos casos notificados no Sistema de Informação de Tratamentos Especiais de Tuberculose (SITETB), no período de 1º de janeiro de 2012 a 31 de dezembro de 2013. Um total de 257 pacientes foi notificado no SITETB e iniciou o tratamento para TBDR. Desse total, 139 (54,1%) tiveram sucesso terapêutico como desfecho, 54 (21%) abandonaram o tratamento e 21 (8,2%) evoluíram para óbito. Após análise de regressão logística multinomial múltipla, a faixa etária acima de cinquenta anos foi observada como único fator de proteção ao abandono, ao passo que ter menos de oito anos de escolaridade e reingresso após abandono foram considerados como fatores de risco. Reingresso após abandono, recidiva e falência indicaram fatores de risco. Nossos dados reforçam a concepção de que o abandono do tratamento de tuberculose resistente é um sério problema de saúde pública, sendo necessário um adequado acompanhamento no tratamento de pacientes com esse histórico e com baixa escolaridade. Além disso, uma rede de apoio social ao paciente é imprescindível para que desfechos desfavoráveis sejam evitados.

La tuberculosis farmacorresistente (TBFR) representa hoy una grave amenaza para los avances en el control de la tuberculosis (TB) en Brasil y en el mundo. En este estudio, se investigan factores asociados al abandono y al óbito de casos en tratamiento para TBDR, dentro de un centro de referencia de carácter terciario del municipio de Río de Janeiro, Brasil. Se trata de un estudio de cohorte retrospectiva, a partir de los casos notificados en el Sistema de Información de Tratamientos Especiales de Tuberculosis (SITETB), durante el período del 1 de enero de 2012 al 31 de diciembre de 2013. Un total de 257 pacientes fue notificado en el SITETB y comenzó el tratamiento para TBDR. De ese total, 139 (un 54,1%) tuvieron éxito terapéutico como desenlace, 54 (un 21%) abandonaron el tratamiento y un 21 (8,2%) evolucionaron hacia óbito. Tras el análisis de regresión logística multinomial múltiple, la franja de edad por encima de cincuenta años se observó como el único factor de protección al abandono, al mismo tiempo que tener menos de ocho años de escolaridad y reingresar en el sistema educativo tras el abandono fueron considerados como factores de riesgo. Reingreso tras abandono, recidiva e insolvencia indicaron factores de riesgo. Nuestros datos refuerzan la concepción de que el abandono del tratamiento de tuberculosis resistente es un serio problema de salud pública, siendo necesario un adecuado acompañamiento en el tratamiento de pacientes con este historial y con baja escolaridad. Además, una red de apoyo social entorno al paciente es imprescindible para que los desenlaces desfavorables sean evitados.

Integrated analysis of ethionamide resistance loci in Mycobacterium tuberculosis clinical isolates.

Tuberculosis patients taking second line drugs such as ethionamide (ETH) have often experienced previous treatment failure and usually have a complex history of disease and treatment that can span decades. Mutations in the ETH activating enzyme, EthA, confer resistance through undescribed mechanisms. To explore the impact of EthA mutations on ETH resistance, data from a total of 160 ETHR isolates was analysed. The most frequently mutated positions are within regions that display sequence conservation with the active site of OTEMO, another FAD-containing NADH-binding Baeyer-Villiger monooxygenase (BVMO), or with the sugar binding site of galectin-4N. Additionally, to look at a possible role of EthR on ETH resistance we purified an EthR mutant identified in a clinical isolate, F110L, and found it to bind the ethA-ethR intergenic region with higher affinity than the wild type regulator in gel shift assays. The ability of cyclic di-GMP to enhance DNA binding is maintained in the EthR mutant. To our knowledge, this is the first ETH resistance study that combines sequence and resistance data of clinical isolates with functional and structural information.

Lysophosphatidylcholine produced by the phospholipase A2 isolated from Lachesis muta snake venom modulates natural killer activity as a protein kinase C effector.

We have showed that a phospholipase A(2) isolated from Lachesis muta snake venom, denoted LM-PLA(2)-I, had some biological effects. Here, we examined its effects on lymphocytes. Pre-incubation of human peripheral blood lymphocytes with LM-PLA(2)-I plus phosphatidylcholine (PC) stimulated the natural killer (NK) activity. This was accompanied by DNA binding of nuclear transcription factor kappaB and the increase in PKC activity with translocation of the enzyme from the cytoplasma into the plasma membrane. These effects were reproduced when lymphocytes were pre-incubated with commercial lysophosphatidylcholine (LPC) and abolished by stausrosporin or p-bromophenacyl bromide. Evaluation of phosphorylated PKC isoforms showed that pre-incubation with LPC activated the autophosphorylation of the PKCzeta isoform. Taken together, these results confirm that the enzymatic activity of the phospholipase A(2) present in L. muta venom is for the biological activity of the snake venom, and strongly suggest that the LPC produced may be acting as a modulator of PKC isoforms.

Detection of mycobacterial infection in non-human primates using the Xpert MTB/RIF molecular assay.

Tuberculosis is a major public health concern, and diagnostic strategies applied to animal populations are scarce. As part of ongoing efforts to control tuberculosis dissemination at our animal facility, two non-human primates (NHP, Saimiri sciureus) presenting cutaneous lesions were examined for mycobacterial infection. Both animals tested positive for acid-fast bacilli and Mycobacterium tuberculosis using a molecular assay (IS6110 PCR). Animals were euthanized and several samples were tested for M. tuberculosis using the Xpert MTB/RIF assay. Many samples were positive for M. tuberculosis and rifampicin resistance, and some produced mycobacterial growth. Oral swabs from cage mates were then tested with Xpert MTB/RIF, and the majority tested positive for M. tuberculosis and rifampicin resistance, and produced growth in culture. To our knowledge, this is the first report of multidrug-resistant mycobacterial infection in NHP. Additionally, our data shows that the Xpert MTB/RIF assay can be useful as a screening tool for tuberculosis infection in NHP.

First detection of Mycobacterium triplex in Latin America.

In this study we describe the first isolation of Mycobacterium triplex in Latin America. This species causes infections in humans, with very few reports from around the world. We isolated two sputum specimens of a patient with a 6-year history of human immunodeficiency and tuberculosis treatment failure. All tests used confirmed M. triplex and the patient responded well to drug therapy for 18months.

Fatores associados ao abandono e ao óbito de casos de tuberculose drogarresistente (TBDR) atendidos em um centro de referência no Rio de Janeiro, Brasil / Factores asociados al abandono y al fallecimiento por casos de tuberculosis farmacorresistente (TBFR), atendidos en un centro de referencia en Río de Janeiro, Brasil / Factors associated with loss to follow-up and death in cases of drug-resistant tuberculosis (DR-TB) treated at a reference center in Rio de Janeiro, Brazil

Resumo: A tuberculose drogarresistente (TBDR) representa hoje uma grave ameaça aos avanços no controle da tuberculose (TB) no Brasil e no mundo. Neste estudo, investigam-se fatores associados ao abandono e ao óbito de casos em tratamento para TBDR, em um centro de referência terciária do Município do Rio de Janeiro, Brasil. Trata-se de um estudo de coorte retrospectiva, a partir dos casos notificados no Sistema de Informação de Tratamentos Especiais de Tuberculose (SITETB), no período de 1º de janeiro de 2012 a 31 de dezembro de 2013. Um total de 257 pacientes foi notificado no SITETB e iniciou o tratamento para TBDR. Desse total, 139 (54,1%) tiveram sucesso terapêutico como desfecho, 54 (21%) abandonaram o tratamento e 21 (8,2%) evoluíram para óbito. Após análise de regressão logística multinomial múltipla, a faixa etária acima de cinquenta anos foi observada como único fator de proteção ao abandono, ao passo que ter menos de oito anos de escolaridade e reingresso após abandono foram considerados como fatores de risco. Reingresso após abandono, recidiva e falência indicaram fatores de risco. Nossos dados reforçam a concepção de que o abandono do tratamento de tuberculose resistente é um sério problema de saúde pública, sendo necessário um adequado acompanhamento no tratamento de pacientes com esse histórico e com baixa escolaridade. Além disso, uma rede de apoio social ao paciente é imprescindível para que desfechos desfavoráveis sejam evitados.

Resumen: La tuberculosis farmacorresistente (TBFR) representa hoy una grave amenaza para los avances en el control de la tuberculosis (TB) en Brasil y en el mundo. En este estudio, se investigan factores asociados al abandono y al óbito de casos en tratamiento para TBDR, dentro de un centro de referencia de carácter terciario del municipio de Río de Janeiro, Brasil. Se trata de un estudio de cohorte retrospectiva, a partir de los casos notificados en el Sistema de Información de Tratamientos Especiales de Tuberculosis (SITETB), durante el período del 1 de enero de 2012 al 31 de diciembre de 2013. Un total de 257 pacientes fue notificado en el SITETB y comenzó el tratamiento para TBDR. De ese total, 139 (un 54,1%) tuvieron éxito terapéutico como desenlace, 54 (un 21%) abandonaron el tratamiento y un 21 (8,2%) evolucionaron hacia óbito. Tras el análisis de regresión logística multinomial múltiple, la franja de edad por encima de cincuenta años se observó como el único factor de protección al abandono, al mismo tiempo que tener menos de ocho años de escolaridad y reingresar en el sistema educativo tras el abandono fueron considerados como factores de riesgo. Reingreso tras abandono, recidiva e insolvencia indicaron factores de riesgo. Nuestros datos refuerzan la concepción de que el abandono del tratamiento de tuberculosis resistente es un serio problema de salud pública, siendo necesario un adecuado acompañamiento en el tratamiento de pacientes con este historial y con baja escolaridad. Además, una red de apoyo social entorno al paciente es imprescindible para que los desenlaces desfavorables sean evitados.

Abstract: Drug-resistant tuberculosis (DR-TB) poses a serious threat to tuberculosis (TB) control in Brazil and worldwide. The current study investigated factors associated with loss to follow-up and death in the course of treatment for DR-TB in a tertiary reference center in the city of Rio de Janeiro, Brazil. This was a retrospective cohort study of cases reported to the Information System on Special Treatments for Tuberculosis (SITETB) from January 1, 2012, to December 31, 2013. A total of 257 patients were reported to the SITETB and initiated treatment for DR-TB. Of this total, 139 (54.1%) achieved treatment success as the outcome, 54 (21%) were lost to follow-up, and 21 (8.2%) died. Following a multiple multinomial logistic regression analysis, the age bracket older than 50 years was the only protective factor against loss to follow-up, whereas less than eight years of schooling and reentry after loss to follow-up were considered risk factors. Reentry after loss to follow-up, relapse, and treatment failure appeared as risk factors. Our data reinforce the concept that loss to follow-up in drug-resistant tuberculosis is a serious public health problem, and that adequate follow-up of treatment is necessary in patients with this history and low schooling. A social support network for patients is also indispensable for avoiding unfavorable outcomes.

Whole genome sequence of Mycobacterium kansasii isolates of the genotype 1 from Brazilian patients with pulmonary disease demonstrates considerable heterogeneity

Mycobacterium kansasii is an opportunistic pathogen and one of the most commonly encountered species in individuals with lung disease. We here report the complete genome sequence of 12 clinical isolates of M. kansasii from patients with pulmonary disease in Brazil.

Thalidomide modulates Mycobacterium leprae-induced NF-κB pathway and lower cytokine response.

It is widely accepted that tumor necrosis factor alpha (TNF-α) plays a critical role in the development of tissue and nerve damage in leprosy and during the reactional episodes of acute inflammation. Thalidomide (N-α-phthalimidoglutarimide), a drug used to treat leprosy reaction, modulates immune response, inhibits inflammation and NF-κB activity. Here we investigated whether thalidomide inhibits NF-κB activation induced by Mycobacterium leprae, p38 and ERK1/2 MAPK activation. EMSA and supershift assays were performed to investigate NF-κB activation in response to M. leprae and its modulation following in vitro treatment with thalidomide. Luciferase assay was assayed in transfected THP-1 cells to determine NF-κB transcriptional activity. Flow cytometry and immunofluorescence were used to investigate p65 accumulation in the nucleus. Immunoblotting was used to investigate p38 and ERK1/2 phosphorylation. Following activation of PBMC and monocytes with M. leprae, the formation and nuclear localization of NF-κB complexes composed mainly of p65/p50 and p50/p50 dimers was observed. Induction of NF-κB activation and DNA binding activity was inhibited by thalidomide. The drug also reduced M. leprae-induced TNF-α production and inhibited p38 and ERK1/2 activation. Definition of the activation mechanisms in cells stimulated with M. leprae can lead to the development of new therapy applications to modulate NF-κB activation and to control the inflammatory manifestations due to enhanced TNF-α response as observed in leprosy and in leprosy reactions.

Mycobacterium leprae induces NF-kappaB-dependent transcription repression in human Schwann cells.

Mycobacterium leprae, the causative agent of leprosy, invades peripheral nerve Schwann cells, resulting in deformities associated with this disease. NF-kappaB is an important transcription factor involved in the regulation of host immune antimicrobial responses. We aimed in this work to investigate NF-kappaB signaling pathways in the human ST88-14 Schwannoma cell line infected with M. leprae. Gel shift and supershift assays indicate that two NF-kappaB dimers, p65/p50 and p50/p50, translocate to the nucleus in Schwann cells treated with lethally irradiated M. leprae. Consistent with p65/p50 and p50/p50 activation, we observed IkappaB-alpha degradation and reduction of p105 levels. The nuclear translocation of p50/p50 complex due to M. leprae treatment correlated with repression of NF-kappaB-driven transcription induced by TNF-alpha. Moreover, thalidomide inhibited p50 homodimer nuclear translocation induced by M. leprae and consequently rescues Schwann cells from NF-kappaB-dependent transcriptional repression. Here, we report for the first time that M. leprae induces NF-kappaB activation in Schwann cells and thalidomide is able to modulate this activation.