Hanseníase: uma doença genética?

Genetic polymorphisms of toll-like receptors in leprosy patients from southern Brazil

Leprosy is a chronic disease and also a global health issue, with a high number of new cases per year. Toll-like receptors can respond to mycobacterial molecules in the early stage of infection. As important components of the innate immune response, alterations in genes coding for these receptors may contribute to susceptibility/protection against diseases. In this context, we used a case-control study model (183 leprosy cases vs. 185 controls) to investigate whether leprosy patients and the control group, in southern Brazil, have different frequencies in TLR1 (TLR1 G>T; rs5743618), TLR2 (TLR2 T>C, rs1816702 and rs4696483), and TLR4 (TLR4 A>G, rs1927911) polymorphisms. Analysis of the TLR1 1805G>T polymorphism presented the G/G genotype more frequently in the control group. TLR2 T>C rs1816702 and TLR2 T>C rs4696483, the T/T and C/T genotype, respectively, were more frequent in the control group than in leprosy patients, suggesting protection from leprosy when the T allele is present (rs4696483). Haplotype analyses between TLR1 (rs5743618) and TLR2 (rs1816702 and rs4696483) polymorphisms suggest risk for the presence of the TCC haplotype and protection in the presence of the TCT haplotype. This study suggests that polymorphisms in TLR1 and TLR2 are factors that may contribute to development/resistance of leprosy.

Association of CD209 (DC-SIGN) rs735240 SNV with paucibacillary leprosy in the Brazilian population and its functional effects

BACKGROUND

Leprosy, caused by Mycobacterium leprae, is a public health problem in Brazil that affects peripheral nerves, resulting in physical disabilities. During host-pathogen interactions, the immune response determines leprosy outcomes from a localised (paucibacillary) form to a disseminated (multibacillary) form. The recognition of M. leprae involves the DC-SIGN receptor, which is present on the dendritic cells (DCs) and participates in immune activation.

OBJECTIVES

To evaluate the association of polymorphisms in the promoter region of the gene encoding DC-SIGN (CD209) and the clinical form of leprosy, and to investigate its functional effects.

METHODS

The study population included 406 leprosy patients from an endemic area in Brazil [310 multibacillary (MB); 96 paucibacillary (PB)]. A functional evaluation based on the effects of the single nucleotide variant (SNV) associated with PB leprosy on the specific immune response was also performed.

RESULTS

The GA genotype and the presence of the A allele of rs735240 (-939G>A) were associated with PB leprosy [OR: 2.09 (1.18-3.69) and 1.84 (1.07-3.14), respectively]. Carriers of the A allele showed reduced expression of CD209 and TGF-β1 in leprosy lesions in comparison with individuals with GG genotype, in addition to a higher response to the Mitsuda test.

CONCLUSION

These data suggest that rs735240 influences the immune response against M. leprae and clinical presentation of leprosy.

Gene Association with Leprosy: A Review of Published Data

Leprosy is a chronic infectious disease caused by an obligate intracellular bacterium known as Mycobacterium leprae. Exposure to the bacillus is necessary, but this alone does not mean an individual will develop clinical symptoms of the disease. In recent years, several genes have been associated with leprosy and the innate immune response pathways converge on the main hypothesis that genes are involved in the susceptibility for the disease in two distinct steps: for leprosy per se and in the development of the different clinical forms. These genes participate in the sensing, main metabolic pathway of immune response activation and, subsequently, on the evolution of the disease into its clinical forms. The aim of this review is to highlight the role of innate immune response in the context of leprosy, stressing their participation in the signaling and targeting processes in response to bacillus infection and on the evolution to the clinical forms of the disease.

Genetic risk factors for human susceptibility to infections of relevance in dermatology

BACKGROUND

In the pre-microbiological era, it was widely accepted that diseases, today known to be infectious, were hereditary. With the discovery of microorganisms and their role in the pathogenesis of several diseases, it was suggested that exposure to the pathogen was enough to explain infection. Nowadays, it is clear that infection is the result of a complex interplay between pathogen and host, therefore dependant on the genetic make-up of the two organisms. Dermatology offers several examples of infectious diseases in different stages of understanding of their molecular basis. In this review, we summarize the main advances towards dissecting the genetic component controlling human susceptibility to infectious diseases of interest in dermatology. Widely investigated diseases such as leprosy and leishmaniasis are discussed from the genetic perspective of both host and pathogen. Others, such as rare mycobacterioses, fungal infections and syphilis, are presented as good opportunities for research in the field of genetics of infection.

Leprosy epidemics during history increased protective allele frequency of PARK2/PACRG genes in the population of the Mljet Island, Croatia

INTRODUCTION

Two regulatory polymorphisms (rs1040079 and rs9356058) shared by PARK2 and PACRG genes were identified as major risk variants for leprosy susceptibility. The aim of this study was to investigate if allele frequencies of these polymorphisms in the isolated population of the island of Mljet, which served as a quarantine for leprosy patients during past centuries, were different to allele frequencies in two control populations with no history of leprosy.

SUBJECTS AND METHODS

This study included 88 unrelated Caucasian individuals from the island of Mljet while two control groups included 93 individuals from the island of Rab and 160 individuals from the region of Split. Genotyping for rs1040079 and rs9356058 was performed by "real-time" PCR analysis. We also compared the allele frequency of the rs9356058 polymorphism from the population of Mljet with allele frequencies derived from the existing genome wide association scans in two additional island populations, Vis (924 subjects) and Korcula (909 subjects).

RESULTS

We found a significant increase in the frequency of rs9356058 allele C in the population of Mljet when compared to both control groups. We also observed a significant increase in the frequency of rs1040079 allele A in the population of Mljet when compared with the population of Rab, however this increase was not significant when compared with the population of Split. Allele frequencies of both examined polymorphisms did not differ between the two control populations. Protective haplotype rs9356058-rs1040079 CA was also more frequent in the population of Mljet compared with the Rab and Split populations. In addition, an increase of frequency of rs9356058 allele C was also observed in the population of Mljet when compared with the frequency in the Korcula population.

CONCLUSION

The results of our study show the association of polymorphisms rs9356058 and rs1040079 in gene PARK2/PACRG with leprosy. The results of our study indicate that exposure to leprosy and mortality in the population caused by leprosy on Mljet resulted in the selection of rs9356058 "protective" C allele in the PARK2 gene, while this was not observed in the two control groups. This is the first study to assess the genetic susceptibility to leprosy in a European population.

[Peripheral nervous system and grounds for the neural insult in leprosy]

The mechanism of interaction between Mycobacterium leprae and neural cells has not been elucidated so far. No satisfactory interpretation exists as to the bacterium tropism to the peripheral nervous system in particular. The present study is a review of the micro-physiology of the extracellular apparatus attached to Schwann cells, as well as on the description of morphological units probably involved in the process of the binding to the bacterial wall.

Polimorfismos do gene NRAMP1 em indivíduos com reações hansênicas, atendidos em dois Centros de Referência no Recife, nordeste do Brasil

INTRODUÇÃO: Para investigar susceptibilidade às reações hansênicas, três polimorfismos do gene natural resistance-associated macrophage protein (NRAMP1), foram determinados em 201 indivíduos, atendidos em dois centros de referência no Recife, entre 2007 e 2008, sendo 100 paucibacilares e 101 multibacilares. MÉTODOS: A determinação dos polimorfismos 274C/T, D543N e 1729+55del4 do gene NRAMP1 foi realizada utilizando a técnica do polimorfismo de fragmento de restrição em DNA extraído de sangue periférico e as estimativas das freqüências alélicas e genotípicas foram feitas por contagem direta. RESULTADOS: Os genótipos predominantes foram: CC (51,8%) para 274C/T, GG (86,6%) para D543N e +-TGTG (59,9%) para 1729+55del4. O genótipo mutante 274 TT predominou na negatividade da reação reversa (p=0,03) e na positividade do eritema nodoso (p=0,04). CONCLUSÕES: Nossos resultados sugerem que o polimorfismo 274 C/T do gene NRAMP1 pode auxiliar na determinação da susceptibilidade à reação tipo II em indivíduos com hanseníase.

Imunologia da hanseníase

A hanseníase é doença crônica infecciosa que se caracteriza por apresentar formas clínicas contrastantes, que são dependentes da interação do bacilo com a resposta imune do hospedeiro. O estudo dos processos imunológicos torna-se fundamental para o entendimento dos mecanismos envolvidos na apresentação e no desenvolvimento da doença. Neste artigo, é revisada a imunopatogênese da hanseníase.