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dc.contributor.advisorBuck, Amy
dc.contributor.advisorMaizels, Rick
dc.contributor.authorCoakley, Gillian
dc.date.accessioned2017-08-30T13:02:44Z
dc.date.available2017-08-30T13:02:44Z
dc.date.issued2017-07-07
dc.identifier.urihttp://hdl.handle.net/1842/23464
dc.description.abstractThe parasite secretome has been shown to play a key role in both pathogenicity and the regulation of host defence, allowing pathogens, such as helminths, to establish a chronic infection within the host. The recently discovered presence of extracellular vesicles within parasite-derived excretory-secretory products introduces a new mechanism of potential cross-species communication. Extracellular vesicles (EVs), such as exosomes, facilitate cellular communication through the transfer of small RNAs, lipids and proteins between cells and organisms across all three kingdoms of life. In addition to their roles in normal physiology, EVs also transport molecules from pathogens to hosts, presenting parasite antigens and transferring infectious agents. Here, I examine secreted vesicles from the murine gastrointestinal nematode Heligmosomoides polygyrus, and their potential role in the host-helminth interactions. Transmission electron microscopy reveals vesicle-like structures of 50- 100 nM in the ultracentrifuged secretory product, and potential evidence of multi-vesicular bodies in the worm intestine. This, coupled with information from the exoproteome, helped support the hypothesis that exosomes originate from the parasite intestinal tract. I have completed a series of studies looking at the fundamental properties of exosome-cell interactions, providing comparative studies between mammalian and H. polygyrus-derived exosomes. I have determined some of the key factors influencing exosome uptake, including time of incubation, cell type and exosome origin. Through microarray analysis of H. polygyrus exosome-treated small intestinal epithelial cells, we see significant gene expression changes, including those involved in the regulation of signalling and the immune response, such as DUSP1 (dual-specificity phosphatase) and IL1RL1 (the receptor for IL-33). The modest reduction of inflammatory cytokine responses by exosomes in small intestinal cell lines was amplified in immune cells, such as macrophages. Exosomes can significantly reduce expression of classical activation markers, as well as inflammatory cytokine production in the macrophage cell line RAW 264.7, and this is further supported by similar responses in bone marrow-derived macrophages. Owing to their suppressive nature, I demonstrate that immunization of mice with an exosome/alum conjugate generates significant protection from a subsequent H. polygyrus larval challenge, as seen through a reduction in egg counts and worm burden. I have investigated the role of the IL33 receptor (IL-33R); a key molecule associated with parasitic resistance that is suppressed by exosomes in type-2 associated immune responses. Uptake of H. polygyrus-derived exosomes by alternatively activated macrophages caused the suppression of type 2 cytokine/protein release and the reduction of key genes associated with this phenotype. In addition, there was also significant repression of both transcript and surface T1/ST2, a subunit of the IL-33R). Using a model of lung inflammation, in vivo studies demonstrate that, in both prophylactic and co-administration experiments, exosomes modulate the innate cellular response. This is represented by changes in the number of innate lymphoid cells (ILCs), bronchoalveolar lavage eosinophils and type-2 cytokine output. In this system, the expression of T1/ST2 on type 2 ILCs was also significantly reduced. I have extended the investigation on exosome-IL-33R responses by using T1/ST2 knockout mice. Despite generating strong antibody responses, vaccination against exosomes could not protect T1/ST2 knockout mice against a subsequent infection. This work suggests that exosomes secreted by nematodes could mediate the transfer and uptake of parasite products into host cells, establishing cross-species communication to suppress the host ‘danger’ or inflammatory response.en
dc.contributor.sponsorBiotechnology and Biological Sciences Research Council (BBSRC)en
dc.language.isoenen
dc.publisherThe University of Edinburghen
dc.relation.hasversionCoakley, G., R.M. Maizels, and A.H. Buck, Exosomes and Other Extracellular Vesicles: The New Communicators in Parasite Infections. Trends Parasitol, 2015.31(10): p.477-89.en
dc.relation.hasversionG., A.H. Buck, and R.M. Maizels, Host parasite communications; Messages from helminths for the immune system: Parasite communication and cell-cell interactions. Mol Biochem Parasitol, 2016.en
dc.relation.hasversionExosomes secreted by nematode parasites transfer small RNAs to mammalian cells and modulate innate immunity Nature Communications, (2014). 10.1038/ncomms6488 Amy H. Buck, Gillian Coakley, Fabio Simbari, Henry J. McSorley, Juan F. Quintana, Thierry Le Bihan, Sujai Kumar, Cei Abreu-Goodger, Marissa Lear, Yvonne Harcus, Alessandro Ceroni, Simon A. Babayan, Mark Blaxter, Alasdair Ivens & Rick M. Maizelsen
dc.subjecthelminthen
dc.subjectparasiteen
dc.subjectexosomesen
dc.subjectextracellular vesiclesen
dc.subjecttype-2 immunityen
dc.subjectcross-species communicationen
dc.titleCharacterisation of secreted exosomes from the intestinal nematode Heligmosomoides polygyrusen
dc.typeThesis or Dissertationen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD Doctor of Philosophyen


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