Hidroximetilnitrofural (NFOH): Estudo da Atividade em Fase Aguda e Crônica da doença de Chagas em Modelo Animal, infectados com cepas Bolívia (TcI) e CL Brener luc bioluminescênte (TcVI) de T. cruzi
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Data
2020-03-24
Autores
Scarim, Cauê Benito [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A tripanossomíase americana ou doença de Chagas é uma zoonose endêmica em 21 países das Américas do Sul e Central, apontada como uma grave doença parasitária resultante da infecção por Trypanosoma cruzi que utiliza insetos triatomíneos como vetores. Existem dois fármacos para o tratamento dessa enfermidade, o nifurtimox (NFX) e o benznidazol (BNZ), ativos apenas na fase aguda da doença, sendo que no Brasil apenas o BNZ é comercializado. Em busca de novas alternativas para o tratamento, destaca-se o hidroximetilnitrofural (NFOH), ativo contra as formas tripomastigotas e amastigotas em ensaio in vitro e in vivo (agudo). O objetivo deste trabalho foi estudar os efeitos do NFOH em ensaios in vivo na fase aguda e crônica utilizando cepa Bolívia e cepa CL Brener bioluminescênte. O estudo com a cepa Bolívia em fase crônica utilizou um ciclo de imunossupressão de 14 dias consecutivos com dexametasona (5 mg/kg) para verificação da reativação da parasitémia, enquanto o ensaio (agudo e crônico) com cepa Brener CL bioluminescênte, aplicando-se 2-3 ciclos de imunossupressão com ciclofosfamida (200 mg/kg, intervalos de quatro dias entre as doses). Os resultados demonstraram efeito semelhantes nos tratamentos com NFOH (150 mg/kg/ 20 dias) e BZN (100 mg/kg /20 dias) na fase aguda com cepa Bolívia, com eliminação da parasitémia e diminuição dos infiltrados inflamatórios e ninhos amastigotas. No ensaio de fase crônica com cepa Bolívia, o NFOH (150 mg/kg/ 60 dias) foi eficaz em eliminar a parasitémia após o ciclo de imunossupressão, negativação confirmada por xenodiagnóstico, bem como reduziu infiltrados inflamatórios e ninhos amastigotas. No ensaio com a cepa CL Brener luc bioluminescênte, os resultados mostraram reativação da infecção quando tratados com NFOH (100 mg/kg/ 5 dias), após dois ciclos de imunossupressão. No modelo utilizando a cepa CL Brener luc bioluminescênte, o NFOH (100 mg/kg), exibiu 100% de cura dos animais, mantendo-se inalterado após dois ciclos de imunossupressão. Entretanto, depois do 3o ciclo, houve reativação em dois dos seis animais analisados, confirmando 50% de cura pelo ensaio ex vivo. O BZN (100 mg/kg), no mesmo protocolo, demonstrou 100% de cura. A análise histopatológica dos órgãos (com as duas cepas) mostrou que o NFOH reduziu o número de infiltrados inflamatórios e fibrose cardíaca e no tecido hepático foi capaz de reduzir a quantidade de infiltrados inflamatórios e colágeno total, valores significativamente diferentes do BZN, demostrando, que NFOH é menos tóxico que o BZN. Os resultados demonstram o potencial do candidato a fármaco NFOH e mais estudos devem ser realizados para obtenção de negativação total após vários ciclos de imunossupressão.
American trypanosomiasis or Chagas disease is an endemic zoonosis in 21 countries of South and Central America, and is a serious parasitic disease resulting from infection by the hemoflagellate parasite called Trypanosoma cruzi, which uses triatomine insects as vectors. There are two drugs for the treatment of this disease, nifurtimox (NFX) and benznidazole (BNZ), active only in the acute phase of the disease, and in Brazil only BNZ is marketed. In the search for new alternatives for treatment, hydroxymethyl nitrofural (NFOH), active against trypomastigotes and amastigotes in vitro and in vivo tests (acute), stands out. The objective of this work was to study the effects of NFOH in vivo and acute phase studies using Bolivia strain and bioluminescent CL Brener strain. The study with the chronic Bolivia strain used a 14-day cycle of immunosuppression with dexamethasone (5 mg/kg) to verify the reactivation of parasitémia, while the test (acute and chronic) with bioluminescent Brener CL strain were applied in 2-3 cycles of immunosuppression with cyclophosphamide (200 mg/kg, four-day intervals between doses). The results showed a similar effect in treatments with NFOH (150 mg/kg/ 20 days) and BZN (100 mg/kg/ 20 days) in the acute phase with strain Bolivia, with elimination of parasitémia, and decrease of parasite infiltrates in hitopathological analisys as well. In the chronic phase assay with strain Bolivia, NFOH (150 mg/kg/ 60 days) was effective in eliminating parasitémia after the immunosuppressive cycle, which was confirmed by xenodiagnoses, and was able to reduce the parasite infiltrates in hitopathological analisys as well. In the bioluminescent Brener CL strain, the results showed reactivation of the infection when treated with NFOH (100 mg/kg/ 5 days), after two cycles of immunosuppression. In the model using bioluminescent Brener strain, NFOH (100 mg/kg) showed 100% cure of the animals, remaining unchanged after two cycles of immunosuppression. However, after the 3rd cycle, there was reactivation in two of the six animals analyzed, confirming 50% cure by the ex vivo assay. BZN (100 mg/kg), in the same protocol, showed 100% cure. Histopathological analysis of the organs (with both strains) showed that NFOH reduced the number of inflammatory infiltrates and cardiac fibrosis and in the hepatic tissue was able to reduce the amount of inflammatory infiltrates and total collagen values significantly different from BZN, demonstrating that NFOH is less toxic than BZN. The results demonstrated the potential of the NFOH as drug candidate and further studies should be performed to obtain total negativity after several cycles of immunosuppression.
American trypanosomiasis or Chagas disease is an endemic zoonosis in 21 countries of South and Central America, and is a serious parasitic disease resulting from infection by the hemoflagellate parasite called Trypanosoma cruzi, which uses triatomine insects as vectors. There are two drugs for the treatment of this disease, nifurtimox (NFX) and benznidazole (BNZ), active only in the acute phase of the disease, and in Brazil only BNZ is marketed. In the search for new alternatives for treatment, hydroxymethyl nitrofural (NFOH), active against trypomastigotes and amastigotes in vitro and in vivo tests (acute), stands out. The objective of this work was to study the effects of NFOH in vivo and acute phase studies using Bolivia strain and bioluminescent CL Brener strain. The study with the chronic Bolivia strain used a 14-day cycle of immunosuppression with dexamethasone (5 mg/kg) to verify the reactivation of parasitémia, while the test (acute and chronic) with bioluminescent Brener CL strain were applied in 2-3 cycles of immunosuppression with cyclophosphamide (200 mg/kg, four-day intervals between doses). The results showed a similar effect in treatments with NFOH (150 mg/kg/ 20 days) and BZN (100 mg/kg/ 20 days) in the acute phase with strain Bolivia, with elimination of parasitémia, and decrease of parasite infiltrates in hitopathological analisys as well. In the chronic phase assay with strain Bolivia, NFOH (150 mg/kg/ 60 days) was effective in eliminating parasitémia after the immunosuppressive cycle, which was confirmed by xenodiagnoses, and was able to reduce the parasite infiltrates in hitopathological analisys as well. In the bioluminescent Brener CL strain, the results showed reactivation of the infection when treated with NFOH (100 mg/kg/ 5 days), after two cycles of immunosuppression. In the model using bioluminescent Brener strain, NFOH (100 mg/kg) showed 100% cure of the animals, remaining unchanged after two cycles of immunosuppression. However, after the 3rd cycle, there was reactivation in two of the six animals analyzed, confirming 50% cure by the ex vivo assay. BZN (100 mg/kg), in the same protocol, showed 100% cure. Histopathological analysis of the organs (with both strains) showed that NFOH reduced the number of inflammatory infiltrates and cardiac fibrosis and in the hepatic tissue was able to reduce the amount of inflammatory infiltrates and total collagen values significantly different from BZN, demonstrating that NFOH is less toxic than BZN. The results demonstrated the potential of the NFOH as drug candidate and further studies should be performed to obtain total negativity after several cycles of immunosuppression.
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Doença de Chagas/agudo, doença de Chagas/crônico, T. cruzi, hidroximetilnitrofural (NFOH), benznidazol, cepa Bolívia, cepa CL Brener luc bioluminescênte