Histopathological changes in the gastrointestinal tract and systemic alterations triggered by experimental oral infection with Trypanosoma cruzi.

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in almost all countries of Latin America. In Brazil, oral infection is becoming the most important mechanism of transmission of the disease in several regions of the country. The gastrointestinal tract is the gateway for the parasite through this route of infection, however, little is known about the involvement of these organs related to oral route. In this sense, the present study evaluated the impact of oral infection on the digestive tract in mice infected by Berenice-78 (Be-78) T. cruzi strain, in comparison with the intraperitoneal route of infection. In this work, the intraperitoneal route group showed a peak of parasitemia similar to the oral route group, however the mortality rate among the orally infected animals was higher when compared to intraperitoneal route. By analyzing the frequency of blood cell populations, differences were mainly observed in CD4+ T lymphocytes, and not in CD8+, presenting an earlier reduction in the number of CD4+ T cells, which persisted for a longer period, in the animals of the oral group when compared with the intraperitoneal group. Animals infected by oral route presented a higher tissue parasitism and inflammatory infiltrate in stomach, duodenum and colon on the 28th day after infection. Therefore, these data suggest that oral infection has a different profile of parasitological and immune responses compared to intraperitoneal route, being the oral route more virulent and with greater tissue parasitism in organs of the gastrointestinal tract evaluated during the acute phase.

Low-dose of benznidazole promotes therapeutic cure in experimental chronic Chagas' disease with absence of parasitism in blood, heart and colon.

Studies suggest that the dose of the standard benznidazole (BNZ) treatment regimen might be too high. We investigated the efficacy of BNZ 20 and 40 mg/kg/day compared with standard dose (100 mg/kg/day) to induce cure in mice infected with Trypanosoma cruzi Y strain in the acute and chronic phases of Chagas' disease. Our findings indicate that an experimental treatment with a BNZ low-dose (40 mg/kg/day) is similarly effective as the usual dose in the chronic mice model (100% of cure). In addition, the treatment in the chronic model of Chagas' disease presented better results than the acute model and colon appears to be a key tissue when it comes to evaluating treatment efficacy compared to blood and heart. Therefore, our data suggest the reconsideration of the current therapy, mainly in the chronic phase of the disease.

Leishmania chagasi heparin-binding protein: Cell localization and participation in L. chagasi infection.

Visceral leishmaniasis is a fatal human disease caused by the intracellular protozoan parasite Leishmania chagasi that is captured by host cells in a process involving classics receptors mediated phagocytosis. The search for molecules involved in this process is important to design strategies to disease control. In this work, we verified the presence of heparin-binding protein (HBP) in L. chagasi promastigotes forms. HBP is a lectin of the group of ubiquitous proteins, whose main characteristic is to bind to carbohydrates present in glycoproteins or glycolipids, which is poorly studied in Leishmania species. L. chagasi HBP (HBPLc) was purified by affinity chromatography using heparin-agarose column in FPLC automated system. Its localization in the parasite was assessed by immunolabeling and electronic transmission microscopy tests using anti-HBPLc polyclonal antibodies, which showed HBP spread over the parasite outer surface and internally next to the kynetoplast. In addition, we verified that HBPLc participates in the process of parasite infection, since its blocking with heparin generated a partial reduction in the internalization of Leishmania by RAW macrophages "in vitro". According to these results, it is believed that, in further "in vivo" studies, interference on this parasitic protein may provide us prophylactic and therapeutic alternatives against visceral leishmaniasis.