Avalia??o da efic?cia do f?rmaco Dissulfiram? em curar camundongos Swiss infectados com o Trypanosoma cruzi.

Programa de P?s-Gradua??o em Ci?ncias Biol?gicas. N?cleo de Pesquisas em Ci?ncias Biol?gicas, Pr?-Reitoria de Pesquisa de P?s Gradua??o, Universidade Federal de Ouro Preto.A doen?a de Chagas (DCh) ? causada pelo protozo?rio flagelado Trypanosoma cruzi (T. cruzi). Desde o final da d?cada de 1960 e in?cio da d?cada de 1970 os f?rmacos Benznidazol (BZ) e Nifurtimox s?o as ?nicas op??es para o tratamento, entretanto, esses f?rmacos est?o associados a uma s?rie de efeitos indesej?veis e apresentam baixa efic?cia na fase cr?nica. Nesse sentido, a busca por f?rmacos mais eficazes e que apresentem baixa toxicidade se faz necess?ria. Testes in vitro demonstraram que o f?rmaco Dissulfiram? (DS) diminui a atividade especifica da enzima mitoc?ndrial delta-1-pirrolina-5-carboxilato desidrogenasse (TcP5CDH) do parasito, a segunda enzima da via oxidativa de prolina. Isto sugere que a interfer?ncia no metabolismo de prolina resultaria numa diminui??o da viabilidade do parasito. Desta forma, o objetivo deste trabalho foi avaliar a efic?cia do DS em camundongos infectados com as cepas Y e VL-10 do T. cruzi. Para cumprir com o objetivo, 290 camundongos Swiss foram divididos em quatro grupos: N?o infectados, Infectados com a cepa Y do T. cruzi e tratados/avaliados na fase aguda; Infectados com a cepa VL-10 do T. cruzi e tratados/avaliados na fase aguda; e infectados com a cepa VL-10 do T. cruzi e tratados/avaliados na fase cr?nica da infec??o. O tratamento foi realizado em dose ?nica di?ria por 20 dias, sendo os esquemas terap?uticos: BZ (100mg/Kg), BZ (50mg/Kg), DS (50mg/Kg), DS (25mg/Kg), BZ + DS (100mg/Kg + 50mg/Kg), BZ + DS (50mg/Kg + 50mg/Kg), BZ + DS (100mg/Kg + 25mg/Kg) e BZ + DS (50mg/Kg + 25mg/Kg). Os par?metros avaliados foram: parasitemia, taxa de sobrevida, cura parasitol?gica, parasitismo tecidual, processo inflamat?rio e fibrose no cora??o e c?lon, concentra??o de ?xido n?trico, aspartato aminotransferase e alanina aminotransferase no soro, estresse oxidativo no f?gado dos animais infectados com a cepa Y do T. cruzi e propriedades f?sico qu?micas. Em todos os grupos experimentais, os animais tratados com DS apresentaram ?rea sob a curva de parasitemia significativamente maior quando comparado aos demais grupos e taxa de sobrevida menor que 100%. No grupo infectado com a cepa Y do T. cruzi, a associa??o BZ + DS (100mg/Kg + DS 50mg/Kg) apresentou 100% de sobrevida, a maior taxa de cura parasitol?gica e diminuiu significativamente o processo inflamat?rio no tecido muscular card?aco quando comparado ao grupo tratado apenas BZ 50mg/Kg. Nos animais infectados com a cepa VL-10 do T. cruzi e tratados tanto na fase aguda quanto na fase cr?nica, ocorreu redu??o do processo inflamat?rio e forma??o de fibrose na camada muscular do c?lon dos animais tratados com DS. J? a associa??o BZ+DS (100mg/Kg +50mg/Kg) apresentou ?rea de fibrose no tecido card?aco significativamente menor quando comparado aos demais grupos. Desta forma, a efic?cia do DS ? dose, cepa e tecido dependentes. A associa??o BZ+DS (100mg/Kg+50mg/Kg) apresentou os melhores resultados. S?o necess?rios mais estudos com o objetivo de desenvolver um f?rmaco que apresente al?m do efeito tripanocida e baixa toxicidade, caracter?sticas f?sicoqu?micas ideais para alcan?ar todos os ?rg?os-alvo da doen?a.Chagas disease is caused by the flagellated protozoan Trypanosoma cruzi (T. cruzi). Since the late 1960s and early 1970s Benznidazole (BZ) and Nifurtimox drugs have been the only treatment option, however, these drugs are associated with a number of undesirable effects and have low efficacy in the chronic phase. In this sense, the search for more effective drugs with low toxicity is necessary. In vitro tests have shown that the drug Disulfiram? (DS) decreases the specific activity of the mitochondrial enzyme delta-1-pyrroline-5-carboxylate dehydrogenase (TcP5CDH), the second enzyme of the proline oxidative pathway. This suggests that interference with proline metabolism would result in decreased parasite viability. Thus, the aim of this study was to evaluate the efficacy of (DS) in curing T. cruzi Y and VL-10 infected mice. To achieve this objective, 320 Swiss mice were divided into four groups: Uninfected animals; Infected with T. cruzi Y strain and treated/evaluated in the acute phase; Infected with the T. cruzi strain VL-10 and treated/evaluated in the acute phase; and infected with the T. cruzi VL-10 strain and treated/evaluated in the chronic phase of infection. The treatment was performed in a single daily dose for 20 days, and the therapeutic regimens: BZ (100mg/Kg), BZ (50mg/Kg), DS (50mg/Kg), DS (25mg/Kg), BZ + DS (100mg/Kg + 50mg/Kg), BZ + DS (50mg/Kg + 50mg/Kg), BZ + DS (100mg/Kg + 25mg/Kg) e BZ + DS (50mg/Kg + 25mg/Kg). The parameters evaluated were: parasitemia, survival rate, parasitological cure, tissue parasitism, inflammatory process and collagen formation in the heart and colon, nitric oxide concentration, serum aspartate aminotransferase and alanine aminotransferase, oxidative stress in the liver of animals infected with the T. cruzi Y strain and physicochemical properties. In all experimental groups, the animals treated with DS presented significantly larger area under the parasitemia curve when compared to the other groups and survival rate lower than 100%. In the group infected with T. cruzi strain Y, the association BZ + DS (100mg/Kg + DS 50mg/Kg) showed the highest parasitological cure rate, significantly decreased the inflammatory process in the cardiac tissue when compared to the group treated with only BZ 50mg/kg and 100% survival. In animals infected with the T. cruzi strain VL-10 and euthanized in both acute and chronic phase, there was a reduction in the inflammatory process and formation of fibrosis in the colon muscle layer of animals treated with DS. The association BZ + DS (100mg/kg + 50mg/kg) presented significantly smaller area of fibrosis in the cardiac tissue when compared to the other groups. In general, the efficacy of DS is dose dependent, strain and tissue dependent. The association BZ + DS (100mg/kg + 50mg/kg) presented the best results. Further studies are needed to develop a drug that has, besides its trypanocidal effect and low toxicity, ideal physicochemical characteristics to reach all target organs of the disease