Avaliação in vitro da atividade antihelmíntica da toxina BnSP-6 contra Strongyloides venezuelensis e seu rastreamento utilizando CdSe/CdS Magic Sized Quantum Dots

Abstract

Strongyloidiasis is a neglected parasitic disease caused by helminths of the genus Strongyloides. Currently, ivermectin is the drug of choice for its treatment, however, cases of therapeutic failure in immunosuppressed patients were reported. The search for new drugs is an important topic in biomedical research. Phospholipases A2 (PLA2) are enzymes that have shown pharmacological potential against tumors and bacteria. This study shows the BnSP-6 action, a PLA2 derived from Bothrops pauloensis snake venom, against Strongyloides venezuelensis, employing CdSe/CdS magic-sized quantum dots (MSQD) as a tracking label. Human intestinal cells (Caco-2), S. venezuelensis infective larvae and parthenogenetic females were cultured and treated with different concentrations of BnSP-6. Cytotoxicity analysis was evaluated using 3- (4,5-dimethylthiazol-2yl) -2,5-diphenyl tetrazoline bromide (MTT). Autophagy and apoptosis were evaluated through fluorescence labelling with Monodansiylcadaverine (MDC) and Propiodium Iodide (PI) respectively. To verify the absorption site, BnSP-6 was bioconjugated with MSQDs. Larvae were treated with bioconjugate, whereas luminescence was monitored by fluorescence microscopy. BnSP-6 showed similar cytotoxicity at a concentration 12-fold lower than ivermectin. Autophagy and late apoptosis were verified in both evolutionary forms of the parasite. Fluorescence microscopy indicated that the bioconjugate was located in the infective larvae intestine after 24 hours, suggesting intestinal absorption before cytotoxic action. In summary, we showed that BnSP-6 does not demonstrate cytotoxicity against Caco-2, and is effective against S. venezuelensis, being absorbed through the larvae intestine, inducing autophagy and apoptosis, indicating its potential as a new tool for strongyloidiasis treatment.