Efeito do veneno de crotalus durissus terrificus e suas frações sobre macrófagos murinos infectados com leishmania (Leishmania) amazonensis

Abstract

Cutaneous leishmaniasis are a group of diseases caused by parasites of the genus Leishmania which often occurs in countries from tropical and subtropical regions. These parasitic diseases are characterized by skin lesions that may progress to a more advanced stage leading to a disfiguring appearance. Treatment of these diseases is traditionally performed with pentavalent antimony that besides having significant side effects are often ineffective due to the acquisition of resistance by parasites. In this way, the search for alternative treatment for these diseases is imperative. Previous studies have shown that isolated venom components of some snake species exhibited growth inhibition of certain parasites including some species of Leishmania. The aim of the present study was to evaluate the in vitro effects of fractions from Crotalus durissus terrificus snake venom on intracellular forms of Leishmania (Leishmania) amazonensis. These fractions were tested at two concentrations (25 and 50 mg/mL) for determination of their 50% inhibitory concentration on the parasites (IC50). The assays were carried out on bone marrow derived macrophages infected with L. (L.) amazonensis and results are expressed as the infection index of macrophage cultures, whereas the cytotoxicity tests were performed by the MTT method. Furthermore, secretion of TGF-β, a cytokine implicated in Leishmania infection, as well as nitric oxide, were measured in the supernatants from L. (L.) amazonensis-infected macrophages treated with the venom fractions. The results showed that all fractions, except convulxin at 25 g/mL, exhibited a significant leishmanicidal activity, while there was no viability loss of macrophages in the presence of all fractions until 50 g/mL. The crotamine fraction displayed the most effective leishmanicidal effect. There was a decrease of TGF-β concentration in the presence of all fractions tested compared to that observed in control group and any of the fractions led to the secretion of nitric oxide in treated cultures. The present results showed the significant leishmanicidal activity of all fractions from Crotalus durissus terrificus venom on L. (L.) amazonensis in vitro with the generation of an inflammatory environment, supporting the potential use of these fractions as an alternative choice for the chemotherapy of cutaneous leishmaniasis.