Glibenclamide, a blocker of KATP channels, shows anthelmintic activity in Echinococcus granulosus larval stage involving an autophagy mechanism

LOOS, JULIA A.; CUMINO A. C.

Mar del Plata

Congreso; LVII Reunión Anual de la Sociedad Argentina de Investigación Clínica, LX Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2012

Sociedad Argentina de Investigaciones Clínicas

ATP-sensitive potassium (KATP) channels serve as a vital link between cellular metabolism and membrane electrical activity in cells of vertebrate and invertebrate. The pharmacologic characteristics of KATP channels include blockade by sulfonylureas such as glibenclamide (GBC), that cause the closure of the ATP-modulated K+ channels through binding to regulatory subunit SUR (sulfonylurea receptor), altering the membrane potential and triggering a variety of downstream events. This inhibition of KATP channels may cause membrane depolarization and a release of calcium via voltage-dependent channels. In this work we tested GBC as a new antiechinoccocal compound against the larval stages of Echinococcus granulosus (Eg), the causative agent of human hydatid disease. GBC inhibited viability in protoscoleces and cysts, in a dose-dependent manner. After 15 days of incubation with 200µM GBC the viability of treated protoscoleces was reduced to 45 ± 5% whereas after 2 days of treatment, the in vitro culture of cysts resulted in detachment of the germinal layers. Ultrastructural damages, determined by SEM, appeared earlier than the viability inhibition, and with lower drug concentrations. In addition, on treated protoscoleces with GBC an increase in intracellular Ca2+ concentration (labeling with Fluo-3 AM) was observed. GBC also increased the level of acidic vesicles (detected by staining with acridine orange and confocal microscopy), upregulated the LC3II expression (confirmed by immunoblot) and the key genes of the autophagic pathway (atg6, atg8, atg12 and atg18) in treated protoscoleces. As GLB sensitivity is the major criterion used to detect SUR, we identified in silico one putative E-SUR ortholog in Echinococcus genome (pathogen_EMU_scaffold007728) that showed 38% of identity with H. sapiens ortholog. Our data reveal conservation of possible GBC-sensitive K+ channels in Echinococcus and suggest that may play an important role in the survival of larval stage.