Exosomes are small vesicles of endocytic origin, which are released into the extracellular environment and mediate a variety of physiological and pathological conditions. In a recent study, a team led by researchers from McGill University show that Schistosoma mansoni releases exosome-like vesiclesin vitro.

Vesicles were purified from culture medium by sucrose gradient fractionation and fractions containing vesicles verified by western blot analyses and electron microscopy. Proteomic analyses of exosomal contents unveiled 130 schistosome proteins. Among these proteins are common exosomal markers such as heat shock proteins, energy-generating enzymes, cytoskeletal proteins, and others. In addition, the schistosome extracellular vesicles contained proteins of potential importance for host-parasite interaction, notably peptidases, signaling proteins, cell adhesion proteins (e.g., integrins) and previously described vaccine candidates, including glutathione-S-transferase (GST), tetraspanin (TSP-2) and calpain. S. mansoniexosomes. Small RNA sequencing indicated these vesicles also contain 143 microRNAs (miRNA), of which 25 are present at high levels, including miRNAs detected in sera of infected hosts. Quantitative PCR analysis confirmed the presence of schistosome-derived miRNAs in exosomes purified from infected mouse sera.

These results provide evidence of vesicle-mediated secretion in these parasites and suggest that schistosome-derived exosomes could play important roles in host-parasite interactions and could be a useful tool in the development of vaccines and therapeutics.

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Overview of the procedure used for isolation and characterization of secreted exosome-like vesicles from Schistosoma mansoni. (A) Adult male and female worms were cultured 48-72 h in media containing exosome-depleted serum. (B) Schematic of the two major types of secretory extracellular vesicles.


V. Samoil, M. Dagenais, V. Ganapathy, J. Aldridge, A. Glebov, A. Jardim, P. Ribeiro (2017) Vesicle-based secretion in schistosomes: Analysis of protein and microRNA (miRNA) content of exosome-like vesicles derived fromSchistosoma mansoni Molecular and Cellular Biochemistry doi: 10.1038/s41598-018-21587-4 [article]

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