In vivo antileishmanial efficacy of a naphthoquinone derivate incorporated into a Pluronic? F127-based polymeric micelle system against Leishmania amazonensis infection.

New therapeutic strategies against leishmaniasis are desirable, since the treatment against disease presents problems, such as the toxicity, high cost and/or parasite resistance. As consequence, new antileishmanial compounds are necessary to be identified, as presenting high activity against Leishmania parasites, but low toxicity in mammalian hosts. Flau-A is a naphthoquinone derivative recently showed to presents an in vitro effective action against Leishmania amazonensis and L. infantum species. In the present work, the in vivo efficacy of Flau-A, which was incorporated into a Poloxamer 407-based micelle system, was evaluated in a murine model against L. amazonensis infection. Amphotericin B (AmB) and Ambisome? were used as controls. The animals were infected and later treated with the compounds. Thirty days after the treatment, parasitological and immunological parameters were evaluated. Results showed that AmB, Ambisome? , Flau-A or Flau-A/M-treated animals presented significantly lower average lesion diameter and parasite burden in tissue and organs evaluated, when compared to the control (saline and micelle) groups. Flau-A or Flau-A/M-treated mice were those presenting the most significant reductions in the parasite burden, when compared to the others. These animals developed also a more polarized antileishmanial Th1 immune response, which was based on significantly higher levels of IFN-?, IL-12, TNF-?, GM-CSF, and parasite-specific IgG2a isotype; associated with low levels of IL-4, IL10, and IgG1 antibody. The absence of toxicity was found in these animals, although mice receiving AmB have showed high levels of renal and hepatic damage markers. In conclusion, results suggested that the Flau-A/M compound may be considered as a possible therapeutic target to be evaluated against human leishmaniasis

Avaliação da proteína amastina de Leishmania sob a forma recombinante e de epítopo específico de células B para o diagnóstico sorológico diferencial da leishmaniose visceral

Submitted by Danniele Vale ([email protected]) on 2019-11-05T15:15:01Z No. of bitstreams: 1 Dissertação Danniele Vale.pdf: 2367158 bytes, checksum: 7ec1d4af142904d9d690bf820f9c664d (MD5)Approved for entry into archive by Eliane Araujo ([email protected]) on 2019-11-11T19:55:42Z (GMT) No. of bitstreams: 1 Dissertação Danniele Vale.pdf: 2367158 bytes, checksum: 7ec1d4af142904d9d690bf820f9c664d (MD5)Made available in DSpace on 2019-11-19T10:52:33Z (GMT). No. of bitstreams: 1 Dissertação Danniele Vale.pdf: 2367158 bytes, checksum: 7ec1d4af142904d9d690bf820f9c664d (MD5) Previous issue date: 2019-08-02FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas GeraisO diagnóstico da leishmaniose visceral (LV) apresenta problemas devido à toxicidade e / ou alto custo dos medicamentos. Além disso, não existe vacina para proteger contra doenças humanas. Neste estudo, a antigenicidade e a imunogenicidade da proteína amastina foram avaliadas em cães e humanos infectados por L. infantum. Para o diagnóstico, além da proteína recombinante, 1 epítopo linear de célula B foi sintetizado e avaliado em ensaios sorológicos. Os resultados mostraram alta sensibilidade e especificidade para detectar a doença quando ambos os antígenos foram empregados contra um painel sorológico canino e humano. Em contraste, quando se utiliza rA2 e uma preparação antigênica de Leishmania solúvel, os valores de sensibilidade e especificidade mostraram-se mais baixos. Um estudo preliminar de imunogenicidade mostrou que a proteína amastina induziu alta produção de IFN-γ e baixa IL-10 em PBMC estimuladas derivadas de pacientes com VL tratados e indivíduos saudáveis, sugerindo um uso potencial dessa proteína como um imunógeno para proteger contra doenças humanas.The diagnosis of visceral leishmaniasis (VL) presents problems due to the toxicity and/or high cost of drugs. In addition, no vaccine exists to protect against human disease. In this study, the antigenicity and immunogenicity of amastin protein were evaluated in L. infantum–infected dogs and humans. For the diagnosis, besides the recombinant protein, 1 linear B-cell epitope was synthetized and evaluated in serological assays. Results showed high sensitivity and specificity values to detect the disease when both antigens were employed against a canine and human serological panel. By contrast, when using rA2 and a soluble Leishmania antigenic preparation, sensitivity and specificity values proved to be lower. A preliminary immunogenicity study showed that the amastin protein induced high IFN-γ and low IL-10 production in stimulated PBMC derived from treated VL patients and healthy subjects, thus suggesting a potential use of this protein as an immunogen to protect against human disease

Recombinant guanosine-5′-triphosphate (GTP)-binding protein associated with Poloxamer 407-based polymeric micelles protects against Leishmania infantum infection

Leishmania virulence proteins should be considered as vaccine candidates against disease, since they are involved in developing infection in mammalian hosts. In a previous study, a Leishmania guanosine-5′-triphosphate (GTP)-binding protein was identified as a potential parasite virulence factor. In the present work, the gene encoding GTP was cloned and the recombinant protein (rGTP) was evaluated as a vaccine candidate against Leishmania infantum infection. The protein was associated with saponin (rGTP/Sap) or Poloxamer 407-based micelles (rGTP/Mic) as adjuvants, and protective efficacy was investigated in BALB/c mice after parasite challenge. Both rGTP/Sap and rGTP/Mic compositions induced a Th1-type immune response in vaccinated animals, with significantly higher levels of IFN-γ, IL-12, IL-2, TNF-α, GM-CSF, nitrite, specific IgG2a isotype antibody and positive lymphoproliferation, when compared to the control groups. This response was accompanied by significantly lower parasite load in the spleens, livers, bone marrows and draining lymph nodes of the animals. Immunological and parasitological evaluations indicated that rGTP/Mic induced a more polarized Th1-type response and higher reduction in the organ parasitism, and with lower hepatotoxicity, when compared to the use of rGTP/Sap. In conclusion, our preliminary data suggest that rGTP could be considered for further development as a vaccine candidate to protect against VL.</p