Carcinogenic Liver Fluke Secretes Extracellular Vesicles That Promote Cholangiocytes to Adopt a Tumorigenic Phenotype

Abstract

Background. Throughout Asia, there is an unprecedented link between cholangiocarcinoma and infection with the liver fluke Opisthorchis viverrini. Multiple processes, including chronic inflammation and secretion of parasite proteins into the biliary epithelium, drive infection toward cancer. Until now, the mechanism and effects of parasite protein entry into cholangiocytes was unknown.Methods. Various microscopy techniques were used to identify O. viverrini extracellular vesicles (EVs) and their internalization by human cholangiocytes. Using mass spectrometry we characterized the EV proteome and associated changes in cholangiocytes after EV uptake, and we detected EV proteins in bile of infected hamsters and humans. Cholangiocyte proliferation and interleukin 6 (IL-6) secretion was measured to assess the impact of EV internalization.Results. EVs were identified in fluke culture medium and bile specimens from infected hosts. EVs internalized by cholangiocytes drove cell proliferation and IL-6 secretion and induced changes in protein expression associated with endocytosis, wound repair, and cancer. Antibodies to an O. viverrini tetraspanin blocked EV uptake and IL-6 secretion by cholangiocytes.Conclusions. This is the first time that EVs from a multicellular pathogen have been identified in host tissues. Our findings imply a role for O. viverrini EVs in pathogenesis and highlight an approach to vaccine development for this infectious cancer.

Human liver flukes

“…Excretory-secretory products of O. viverrini induce expression of Interleukin-6 (IL-6) (50) . Extracellular vesicles containing excretorysecretory products, are taken up by cholangiocytes, and induce release of IL-6, as well as changes in protein expression associated with cancer (51) . IL-6 drives release of human pro-granulin, which is associated with development of many cancers, including cholangiocarcinoma (52) , and may represent a biomarker for development of advanced periportal fibrosis and cholangiocarcinoma (36,50) .…”

Characterization of Trichuris muris secreted proteins and extracellular vesicles provides new insights into host–parasite communication

“…Helminth EVs have immunomodulatory effects and contribute to pathogenesis. For instance, EVs secreted by parasitic flatworms can promote tumorigenesis [18] and polarize host macrophages towards a M1 phenotype [19], while EVs from the gastrointestinal nematode Heligmosomoides polygyrus contain small RNAs that can modulate host innate immunity [20]. …”

Effect of Opisthorchis felineus infection and dimethylnitrosamine administration on the induction of cholangiocarcinoma in Syrian hamsters

“…It is believed that liver flukes can cause damage to the bile duct epithelium in several ways: (i) via mechanical damage; (ii) as a result of action of reactive oxygen species that are produced by the host cells at the site of inflammation; and (iii) because of direct action of fluke-secreted proteins that induce cell proliferation and inhibit apoptosis [34–36]. All these processes lead to lesions in the genetic material and mutations, which get fixed after DNA replication.…”