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Abstract
Background
Penetration of skin, migration through tissues and establishment of long-lived intravascular partners require Schistosoma parasites to successfully manipulate definitive host defences. While previous studies of larval schistosomula have postulated a function for excreted/secreted (E/S) products in initiating these host-modulatory events, the role of extracellular vesicles (EVs) has yet to be considered. Here, using preparatory ultracentrifugation as well as methodologies to globally analyse both proteins and small non-coding RNAs (sncRNAs), we conducted the first characterization of Schistosoma mansoni schistosomula EVs and their potential host-regulatory cargos.
Results
Transmission electron microscopy analysis of EVs isolated from schistosomula in vitro cultures revealed the presence of numerous, 30–100 nm sized exosome-like vesicles. Proteomic analysis of these vesicles revealed a core set of 109 proteins, including homologs to those previously found enriched in other eukaryotic EVs, as well as hypothetical proteins of high abundance and currently unknown function. Characterization of E/S sncRNAs found within and outside of schistosomula EVs additionally identified the presence of potential gene-regulatory miRNAs (35 known and 170 potentially novel miRNAs) and tRNA-derived small RNAs (tsRNAs; nineteen 5′ tsRNAs and fourteen 3′ tsRNAs).
Conclusions
The identification of S. mansoni EVs and the combinatorial protein/sncRNA characterization of their cargo signifies that an important new participant in the complex biology underpinning schistosome/host interactions has now been discovered. Further work defining the role of these schistosomula EVs and the function/stability of intra- and extra-vesicular sncRNA components presents tremendous opportunities for developing novel schistosomiasis diagnostics or interventions.
To access the supplementary material to this article, please see Supplementary files under ‘Article Tools’.
To access the supplementary material to this article, please see Supplementary files under ‘Article Tools’.
Acknowledgements
This work was supported by an IBERS PhD studentship awarded to FCN. We acknowledge all members of the Hoffmann laboratory for assisting in the maintenance of the schistosome lifecycle, Dr Kathy Geyer and Ms Jennifer Edwards for helminth fluorescent bioassay set-up and Dr Steven Wade for helping with TEM visualization of schistosomula EVs. We also thank Drs Jennifer Fitzpatrick and Emily Peak for contributing the TEM and epifluorescent images of cercaria and schistosomula samples included in this study.
Notes
To access the supplementary material to this article, please see Supplementary files under ‘Article Tools’.