Myelination key factor krox-20 is downregulated in Schwann cells and murine sciatic nerves infected by Mycobacterium leprae.

Schwann cells (SCs) critically maintain the plasticity of the peripheral nervous system. Peripheral nerve injuries and infections stimulate SCs in order to retrieve homeostasis in neural tissues. Previous studies indicate that Mycobacterium leprae (ML) regulates the expression of key factors related to SC identity, suggesting that alterations in cell phenotype may be involved in the pathogenesis of neural damage in leprosy. To better understand whether ML restricts the plasticity of peripheral nerves, the present study sought to determine the expression of Krox-20, Sox-10, c-Jun and p75NTR in SC culture and mice sciatic nerves, both infected by ML Thai-53 strain. Primary SC cultures were stimulated with two different multiplicities of infection (MOI 100:1; MOI 50:1) and assessed after 7 and 14 days. Sciatic nerves of nude mice (NU-Foxn1nu ) infected with ML were evaluated after 6 and 9 months. In vitro results demonstrate downregulation of Krox-20 and Sox-10 along with the increase in p75NTR-immunolabelled cells. Concurrently, sciatic nerves of infected mice showed a significant decrease in Krox-20 and increase in p75NTR. Our results corroborate previous findings on the interference of ML in the expression of factors involved in cell maturation, favouring the maintenance of a non-myelinating phenotype in SCs, with possible implications for the repair of adult peripheral nerves.

Advances in leprosy immunology and the field application: A gap to bridge.

Advances concerning the hosts' immune response to Mycobacterium leprae infection have focused on elucidating the immune pathomechanisms involved, with the hope that predictive diagnostic and prognostic parameters (biomarkers) for field use would emerge; however, improvements in our understanding of the immunologic responses to this complex disease have, to date, somewhat failed to provide the effective and robust methods for improving its predictive diagnosis in the field situation, particularly in those patients suffering from paucibacillary disease. In this contribution we have attempted to review some of the advances both in the immunology and immunopathology of leprosy, and also highlight the limited clusters of immune parameters that are now available. Most importantly, we point out the limitations that still prevail in the provision of effective biomarkers in the field situation for either: (1) the diagnosis of indeterminate disease, (2) predictive diagnosis of individuals developing reactional states, (3) monitoring efficacy of treatment, or (4) monitoring treatment of reactional states.

The GATA3 gene is involved in leprosy susceptibility in Brazilian patients.

Leprosy outcome is a complex trait and the host-pathogen-environment interaction defines the emergence of the disease. Host genetic risk factors have been successfully associated to leprosy. The 10p13 chromosomal region was linked to leprosy in familial studies and GATA3 gene is a strong candidate to be part of this association. Here, we tested tag single nucleotide polymorphisms at GATA3 in two case-control samples from Brazil comprising a total of 1633 individuals using stepwise strategy. The A allele of rs10905284 marker was associated with leprosy resistance. Then, a functional analysis was conducted and showed that individuals carrying AA genotype express higher levels of GATA-3 protein in lymphocytes. So, we confirmed that the rs10905284 is a locus associated to leprosy and influences the levels of this transcription factor in the Brazilian population.