Estudos pré-clínicos com nanopartículas de antimônio pentavalente no tratamento da Leishmaniose cutânea

Abstract

Cutaneous leishmaniasis is a neglected disease, endemic in tropical and subtropical areas, and Brazil is one of the countries most affected by the disease. Treatment with pentavalent antimonials has been used for over 70 years as the first choice drug in the country and has been shown to be ineffective against some Leishmania species. In addition to toxic, it presents in injectable form, offers a wide spectrum of adverse effects and still represents a high acquisition cost for the country. Consequently, there is an immediate need for research into new antileishmania compounds in order to combat resistance to the drugs used and to demonstrate efficacy and safety in order to facilitate the treatment of the disease. Nanoparticles (NPs) promise an alternative approach to new drugs in the treatment of infectious diseases because their small size and large surface area provide an opportunity for them to interact with vital components of infectious agents, and are more effective than traditional therapies. In this study, pentavalent antimony NPs (Sb+5 NPs) were produced and characterized in order to evaluate their effect in vitro and in vivo in the treatment of cutaneous leishmaniasis. The concentration of Sb+5 was determined by graphite furnace atomic absorption spectrometry; The NPs were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM), submitted to in vitro bioassays against promastigotes and amastigotes of Leishmania amazonensis, by the direct counting method in the Neubauer chamber and To cytotoxic activity in J774 lineage macrophages. In the in vivo assay, the hamsters (Mesocricetus auratus) experimentally inoculated with L. amazonensis were grouped to receive intralesional (snout) treatment, with subsequent euthanasia for removal of tissue fragments for analysis by impression by apposition, culture of lesion biopsy, histopathology And MET. The results obtained in this study showed NPs with mean size of 42 nanometers and zeta potential around -49.8 mV, spherical shape, smooth surface and dispersed in suspensions. Bioassays indicated that these NPs showed cytotoxicity at the highest concentrations tested. The most promising suspension was ETSbL2, which had the highest antileishmania activity, with EC50 of 1.05 mg/mL in 72h. The persistence of infection in experimentally infected macrophages when treated with Sb5 + NPs was not noted. After 26 days of experimental treatment, the animals had statistically significant differences between the control group and the groups treated with NPs, regarding the area and clinical aspect of the lesion, and regarding the parasitic control. The histological findings of the lesions of the groups treated with these Sb+5 NPs showed intense inflammatory infiltrate, compromising both the dermosuperficial layer and the dermoprofound of the tissue. Histological changes were also observed in the liver, spleen and kidney. However, ETSbL1[b] (18.6 mg/Sb5+/kg/day) showed greater efficiency in clinical cure regarding reduction in lesion size and parasitic load among the NPs tested. These results suggest the continuity of this study with new tests in animals less susceptible to infection (mice) aiming at a possible clinical and parasitological cure, as well as the evaluation of toxicological and biochemical parameters after treatment.