Exosome-like vesicles secreted by Echinococcus granulosus larval stage contain proteins involved in parasite-host communication

NICOLAO, MARÍA CELESTE; RODRIGUEZ RODRIGUES, CHRISTIAN; ANDREA C. CUMINO

San Francisco

Congreso; 3rd Annual Congress on Infectious Diseases; 2017

Statement of the Problem: Human echinococcosis is a zoonotic cestode disease caused by Echinococcus sp. larval stage. Thesehelminth parasites lack digestive and excretory system but they have developed active endocytic-exocytic cellular processesto regulate metabolite uptake and excretion. The purpose of this study is to analyze the cestode exosome-like productionand to characterize these vesicles focusing on the parasite-host interaction. Methodology & Theoretical Orientation: Viableprotoscoleces and metacestodes were in vitro cultured in presence of loperamide or in control conditions and viability andcalcium concentration were determined. Additionally, extracellular vesicles were purified from parasite-culture medium throughseveral centrifugation and ultracentrifugation steps and were analyzed by confocal imaging, TEM, western blot and proteomicanalysis. Findings: Loperamide reduced the viability of both larval stages in a dose-dependent manner, provoked a cytosoliccalcium level increment and induced a higher density of vesicles respect to the control. In addition, TEM analysis enabled thevesicles morphological characterization and the identification of abundant exosomes (30-100 nm vesicles with cup-shapedmorphology). Finally, a large amount of exosomal proteins have been identified by proteomic analysis, among them Alix andTSG101 which are components of the endosomal sorting complex required for transport and are considered exosomal proteinmarkers; Syntenin-1 implicated in the regulation of exosome biogenesis; Tetraspanins, related to cell adhesion (in particularCD9, whose expression was corroborated by WB); proteins involved in vesicle related transport (such as rab proteins, syntaxinbindingprotein) and proteins involved in host immune response, parasite antigens and uncharacterized proteins which are ofspecial interest for their putative role in parasite-host interaction. Conclusion & Significance: Echinococcus granulosus secretesexosome-like vesicles which could be involved in the host immune response. Further studies are needed to fully investigatethese vesicles which could be involved in parasite establishment and immune tolerance that guarantees cestode survival.