Avaliação da metaciclogênese in vitro de Leishmania (V.) braziliensis e Leishmania (L.) amazonensis

• Autor(a) principal: Silva Junior, Ildefonso Alves da
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/4640
• topic: Leishmania braziliensis; Leishmania amazonensis,; Metaciclogênese; Macrófago humano; Metacyclogenesis; Human macrophage; CIENCIAS BIOLOGICAS::IMUNOLOGIA

The American Tegumentary Leishmaniasis (ATL), caused by Leishmania protozoa, affects the skin and oropharyngeal/nasal mucosa. During transmission cycle, the procyclic promastigote forms grow in the vector gut and differentiate into infective metacyclic promastigotes by a process called metacyclogenesis, which also occurs in axenic cultures. The aim of this study was to evaluate the in vitro metacyclogenesis of L. (Viannia) braziliensis and L. (L.) amazonensis isolates obtained from patients with different clinical forms of ATL, using different methodologies, and the ability of these isolates to infect human macrophages. Parasites (L. (Viannia) braziliensis: IMG3, PPS6m, M2903 and L. (L.) amazonensis: MAB6 and PH8) were cultured in Grace´s insect medium and the amount of metacyclic forms was evaluated by using morphometry, Bauhinia purpurea lectin (BPL, to L. (Viannia) braziliensis) or 3A1-La antibody (to L. (L.) amazonensis) negative selection, flow cytometry and Complement-resistance test after 2, 6 and 10 days of culture. Human monocyte-derived macrophages from healthy donors, activated or not with interferon gamma (IFN) and lipopolysaccharide (LPS), were infected with parasites from different days of culture or with selected metacyclic forms with BPL/3A1-La (1:1 parasite: macrophage) for 24 or 72 h. Growth patterns were similar among the isolates. Stationary-phase promastigotes (6, 10 days) showed morphological changes such as a reduction of the cell body and an increase in the flagellum length, in comparison to the parasites of the 2nd day. Leishmania. (L.) amazonensis promastigotes of the 6th and 10th day of culture presented higher length of the cell body and flagellum than L. (Viannia) braziliensis isolates. In stationary phase there was a significant increase in the percentage of metacyclic forms detected by the four techniques used (M2903: 71-86%; IMG3: 41-85%; PPS6m: 39-76%; PH8: 38-69% e MAB6: 47-84%; 6th day, medians of the techniques used). Despite the four techniques demonstrated similar metacyclogenesis profiles for all isolates evaluated, metacyclic forms densities varied with the technique and the day of culture. The BLP/3A1-La selection consistently identified the highest frequencies of metacyclic forms for all isolates (6th day) among the four techniques. Metacyclogenesis of the isolates was confirmed in in vitro macrophage infection assays which showed a significant increase of the index of infection with parasites of the 6th and 10th day compared to those of the 2nd day (24 or 72 h). No significant differences in capability to infect macrophages were detected between unfractionated or 6th day-selected metacyclic forms. The isolates showed different profiles of susceptibility to macrophage microbicidal mechanisms. The M2903 and PH8 strains were the most susceptible whereas MAB6 isolate was the most resistant among the isolates. As high amounts of metacyclic forms were present in all isolate cultures, considering BPL/3A1-La selection, the results suggest that resistance/susceptibility to macrophage control mechanisms is an intrinsic characteristic of the isolates. To evaluate the metacyclogenesis of clinical isolates together with the ability of parasites to infect human macrophages sets the conditions for obtaining efficient parasites to establish a successful infection what is critical for the evaluation of the pathogenesis and natural immune response in leishmaniasis.