title: Excretory/secretory products of the carcinogenic liver fluke are endocytosed by human cholangiocytes and drive cell proliferation and IL6 production.
abstract: Liver fluke infection caused by Opisthorchis viverrini remains a major public health problem in many parts of Asia including Thailand, Lao PDR, Vietnam and Cambodia, where there is a strikingly high incidence of cholangiocarcinoma (CCA - hepatic cancer of the bile duct epithelium). Among other factors, uptake of O. viverrini excretory/secretory products (OvES) by biliary epithelial cells has been postulated to be responsible for chronic inflammation and proliferation of cholangiocytes, but the mechanisms by which cells internalise O. viverrini excretory/secretory products are still unknown. Herein we incubated normal human cholangiocytes (H69), human cholangiocarcinoma cells (KKU-100, KKU-M156) and human colon cancer (Caco-2) cells with O. viverrini excretory/secretory products and analysed the effects of different endocytic inhibitors to address the mechanism of cellular uptake of ES proteins. Opisthorchis viverrini excretory/secretory products was internalised preferentially by liver cell lines, and most efficiently/rapidly by H69 cells. There was no evidence for trafficking of ES proteins to cholangiocyte organelles, and most of the fluorescence was detected in the cytoplasm. Pretreatment with clathrin inhibitors significantly reduced the uptake of O. viverrini excretory/secretory products, particularly by H69 cells. Opisthorchis viverrini excretory/secretory products induced proliferation of liver cells (H69 and CCA lines) but not intestinal (Caco-2) cells, and proliferation was blocked using inhibitors of the classical endocytic pathways (clathrin and caveolae). Opisthorchis viverrini excretory/secretory products drove IL6 secretion by H69 cells but not Caco-2 cells, and cytokine secretion was significantly reduced by endocytosis inhibitors. This the first known study to address the endocytosis of helminth ES proteins by host epithelial cells and sheds light on the pathways by which this parasite causes one of the most devastating forms of cancer in south-eastern Asia.
authors.affiliation: Biomedical Sciences Program, Graduate School, Khon Kaen University, Khon Kaen, Thailand; Tropical Disease Research Laboratory, Department of Pathology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sujittra
authors.initials: S
authors.lastname: Chaiyadet
authors.affiliation: Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Smout
authors.affiliation: Faculty of Science, University of Technology Sydney, Sydney, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Johnson
authors.affiliation: Faculty of Science, University of Technology Sydney, Sydney, Australia.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Whitchurch
authors.affiliation: Faculty of Science, University of Technology Sydney, Sydney, Australia.
authors.forename: Lynne
authors.initials: L
authors.lastname: Turnbull
authors.affiliation: Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
authors.forename: Sasithorn
authors.initials: S
authors.lastname: Kaewkes
authors.affiliation: Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia.
authors.forename: Javier
authors.initials: J
authors.lastname: Sotillo
authors.affiliation: Centre for Biodiscovery and Molecular Development of Therapeutics, Australian Institute of Tropical Health and Medicine, James Cook University, Cairns, Australia.
authors.forename: Alex
authors.initials: A
authors.lastname: Loukas
authors.affiliation: Tropical Disease Research Laboratory, Department of Pathology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand. Electronic address: banchob@kku.ac.th.
authors.forename: Banchob
authors.initials: B
authors.lastname: Sripa
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology*; D015801:Helminth Proteins / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D009891:Opisthorchis / Q000378:metabolism*
chemical_list: D015801:Helminth Proteins; D015850:Interleukin-6
keywords: Carcinogenesis; Cholangiocyte; Endocytosis; Excretory/secretory products; IL6; Opisthorchis viverrini