Vesicle-based secretion in schistosomes: Analysis of protein and microRNA (miRNA) content of exosome-like vesicles derived from Schistosoma mansoni

Abstract

Exosomes are small vesicles of endocytic origin, which are released into the extracellular environment and mediate a variety of physiological and pathological conditions. Here we show that Schistosoma mansoni releases exosome-like vesicles in 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 contain 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. mansoni exosomes 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. The 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.

Epigenetic and parasitological parameters are modulated in EBi3-/- mice infected with Schistosoma mansoni

“…A previous work of our group identified a set of miRNAs in silico highlighting their conservation in S. mansoni [31]. Recently some miRNAs present in the work of our group cited before were found in S. mansoni exosomes from parasite culture medium and also in mice serum, bouncing their potential to act in host targets and to be involved in host-parasite interactions [30]. Some of these miRNAs were tested in the experiments of this present work to detect if exists also alterations in miRNA expression influenced by immune response of the host, given its importance as possible biomarkers and interactions with the host.…”

“…MiRNAs are well explored in S. mansoni adult males and females have different repertoires or amounts of some miRNAs, many of which are important for the normal development of the parasite's reproductive organs in addition, these molecules are distributed for all chromosomes autosomal and sexual [29]. Adult worms have miRNAs with some predicted targets located in the definitive host, reinforcing the role of these molecules in parasite-host interaction [30]. A previous work of our group identified a set of miRNAs in silico highlighting their conservation in S. mansoni [31].…”

Schistosomal extracellular vesicle‐enclosed miRNAs modulate host T helper cell differentiation

“…To further assess whether miRNAs were transferred by these EVs, the schistosomal EVs or the control pellets were added to the Jurkat cells. For this purpose, we decided to further investigate the targets of miR-10, based on several reasons: (i) In previous analyses of EVs, it appeared as the most abundant miRNA in S. japonicum [31], and one of the most abundant in S. mansoni [32,64]. The schistosomal miRNAs miR-125 and Bantam were detected in schistosomal-EV-exposed Jurkat cells but not in the control (Appendix Fig S4).…”

Evidence for transposable element control by Argonautes in a parasitic flatworm lacking the piRNA pathway

“…These important control pathways are the subject of much research in model organisms 29 and disease and, consequently, much is known about TE control and NS mechanisms in 30 plants [2], fruit flies [3,4], nematodes [5], mammals [6] and cancer [7,8]. Notably, the 31 mechanisms of NS vary greatly across the tree of life, indicating independent evolutionary 32 origins [9,10].…”

“…While in the nucleus, SmAGO2 could undertake nuclear 159 silencing using TE-derived small RNAs [24] to target nascent TE transcripts, when 160 shifted to the cytoplasm, SmAGO2 could be packed into vesicles ready to be deployed to 161 4/10 the environment, as is the case in H. polygyrus bakeri [27]. However, proteomics studies 162 targeting extracellular vesicles have not detected SmAGO2 in samples from S. mansoni 163 [28,29,30]. Further investigations will be required to underpin the extent of functions 164 that can be attributed to these flatworm-specific genes.…”