SB-83, a 2-Amino-thiophene derivative orally bioavailable candidate for the leishmaniasis treatment.

Leishmaniasis, affecting more than 12 million people worldwide has become a severe public-health problem. The therapeutic arsenal against leishmaniasis is mainly administered by parenteral route; it is toxic, expensive, and associated with recurrence risk. The need for further therapeutic compounds research is pressing. In previous studies, we demonstrated the antileishmanial activities of ten 2-amino-thiophene derivatives, which evidenced the action of a compound, called SB-83, having expressive antileishmania activity in an in vitro infection model. In the present work, we describe preclinical studies of the thiophenic derivative SB-83, such as acute toxicity, genotoxicity, in vivo oral efficacy in a murine model, and in vitro antileishmanial activity against an L. amazonensis SbIII-resistant strain. Determining acute preclinical toxicity, the LD50 of SB-83 was estimated at 2500 mg/kg orally, with few behavioral changes in Swiss mice. Further, treatment with 2000 mg/kg of SB-83 did not induce in vivo genotoxic activity in the peripheral blood micronucleus assay. In 7 weeks of oral treatment, SB-83 reduced paw lesion size in L. amazonensis infected mice by 52.47 ± 5.32%, and decreased the parasite load of the popliteal lymph node and spleen at the highest dose tested (200 mg/kg) respectively by 42.57 ± 3.14%, and 100%, without presenting weight change or other changes of clinical importance in the biochemical and hematological profiles. The treatment of promastigotes and intracellular amastigotes of SbIII sensitive and resistant strains with SB-83 did not produce differences in antileishmania activity, which suggests no cross-resistance. Thus, this work demonstrated that SB-83 has potential as a new active drug candidate even when orally administered, which may become a new therapeutic alternative for the treatment of leishmaniasis.

Short-term protection conferred by Leishvacin® against experimental Leishmania amazonensis infection in C57BL/6 mice.

To date, there is no vaccine available against human leishmaniasis. Although some vaccination protocols can induce immunity in murine models, they fail to induce protection in humans. The reasons for that remain unclear. The aim of the present study was to characterize the changes in the pattern of the immune response during subcutaneous vaccination with Leishvacin® in mice. We also investigated whether IFN-γ and nitric oxide synthase are indispensable for the protection elicited by the vaccine. C57BL/6 WT vaccinated mice showed smaller lesions and fewer numbers of parasites in footpads until 8 weeks post-infection. Up to this time, they produced higher levels of IFN-γ, IL-2, IL-4, IL-17A and IL-10 and higher specific antibody response than control non-vaccinated mice. Moreover, we showed that IFN-γ, most likely by induction of iNOS expression, is essential for immunity. However, after 12 weeks of infection, we observed loss of difference in lesion size and parasite burden between the groups. Loss of resistance was associated with the disappearance of differences in cytokine patterns between vaccinated and control mice, but not of antibody response, which remained different until a later time of infection. The reversal of resistance to L. amazonensis could not be explained by upregulation of regulatory cytokines. Our data point to a subversion of the host immune response by L. amazonensis even when a protective response was previously induced.

Influence of microbiota in experimental cutaneous leishmaniasis in Swiss mice

Neste trabalho, estudamos a infeccao experimental de camundongos Suicos/NIH com Leishmania major em comparacao com camundongos isogenicos C57BL/6 e BALB/c que sao resistentes e suceptiveis a esta infeccao, respectivamente. Camundongos Suicos mostraram lesoes que se curaram espontaneamente e se restringiram ao local de inoculacao. Celulas linfoides derivadas destes animais desenvolveram uma resposta do tipo Th1, caracterizada pela producao de niveis altos de IFN-gama e niveis baixos de IL-4. Com o objetivo de estudar a importancia da microbiota no desenvolvimento da leishmaniose cutanea neste modelo, camundongos Suicos sem germes foram infectados na pata com promastigotas de L. major, convencionalizados apos 3 semanas de infeccao e as lesoes comparadas com as observadas em camundongos convencionais...

Isolamento e caracterização de parasitas responsáveis pela leishmaniose visceral em João Pessoa - Paraíba - Brasil / Isolation and characterization of visceral leishmaniosis in João Pessoa - Paraíba - Brazil

Objetivo: Isolar parasitas de Leishmania a partir de humanos e cães com quadro clínico de leishmaniose visceral da cidade de João Pessoa e estudar estes isolados através da técnica de RAPD-PCR. Metodologia: Os isolados de Leishmania de casos humanos foram obtidos através de punção de medula óssea de pacientes com quadro clínico de leishmaniose visceral e os de origem canina foram obtidos de amostras do baço de cães sintomáticos. Todas as amostras foram inoculadas em meio NNN/BHI e incubadas a 25°C. Foi realizada extração de DNA de todos os isolados de Leishmania e monitoradas as reações de RAPD-PCR. Os produtos destas reações foram aplicados em gel de agarose e os padrões de bandas analisados comparativamente. Resultados: Foram obtidos três isolados de Leishmania de origem humana e quatro isolados de origem canina. A análise dos padrões de bandas da molécula de DNA dos isolados obtidos com a técnica de RAPD demonstrou que os isolados de origem canina compartilharam o mesmo número de bandas com a cepa de referência Leishmania chagasi e os de origem humana apresentaram diferenças quanto ao número de bandas compartilhadas com esta cepa. Conclusão: Existe diversidade genética entre os parasitas de Leishmania que causam a leishmaniose visceral humana e canina na cidade de João Pessoa, sugerindo a presença de mais de uma cepa deste parasita nesta localidade