Excretory/secretory products of the carcinogenic liver fluke are endocytosed by human cholangiocytes and drive cell proliferation and IL6 production

© 2015 Australian Society for Parasitology Inc. 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

Spatial Distribution of, and Risk Factors for, Opisthorchis viverrini Infection in Southern Lao PDR

The liver fluke Opisthorchis viverrini mainly occurs in Lao PDR and Thailand. Humans become infected through the consumption of raw or insufficiently cooked freshwater fish. Chronic infections may lead to severe liver (bile duct) diseases that eventually develop into a bile duct cancer with extremely poor prognosis. Current control efforts aim at preventing heavy morbidity and mortality. In recent years, spatial modeling, using data from well designed surveys, has been employed to better understand the distribution and determinants of parasitic diseases for guiding subsequent control. However, a spatial modeling approach has not been used for O. viverrini before. The purpose of the current study was to map the distribution of O. viverrini infection in Champasack province in southern Lao PDR, to identify risk factors of infection, and to predict the distribution at non-surveyed locations. We found that the risk of O. viverrini infection is higher for people living in close proximity to freshwater bodies, whereas the lack of sanitation sustained environmental contamination and transmission. High risk zones in Champasack province are concentrated in the Mekong River corridor, and hence control efforts should be targeted along the Mekong River

Insights into SCP/TAPS Proteins of Liver Flukes Based on Large-Scale Bioinformatic Analyses of Sequence Datasets

Background: SCP/TAPS proteins of parasitic helminths have been proposed to play key roles in fundamental biological processes linked to the invasion of and establishment in their mammalian host animals, such as the transition from free-living to parasitic stages and the modulation of host immune responses. Despite the evidence that SCP/TAPS proteins of parasitic nematodes are involved in host-parasite interactions, there is a paucity of information on this protein family for parasitic trematodes of socio-economic importance.\ud \ud Methodology/Principal Findings: We conducted the first large-scale study of SCP/TAPS proteins of a range of parasitic trematodes of both human and veterinary importance (including the liver flukes Clonorchis sinensis, Opisthorchis viverrini, Fasciola hepatica and F. gigantica as well as the blood flukes Schistosoma mansoni, S. japonicum and S. haematobium). We mined all current transcriptomic and/or genomic sequence datasets from public databases, predicted secondary structures of full-length protein sequences, undertook systematic phylogenetic analyses and investigated the differential transcription of SCP/TAPS genes in O. viverrini and F. hepatica, with an emphasis on those that are up-regulated in the developmental stages infecting the mammalian host.\ud \ud Conclusions: This work, which sheds new light on SCP/TAPS proteins, guides future structural and functional explorations of key SCP/TAPS molecules associated with diseases caused by flatworms. Future fundamental investigations of these molecules in parasites and the integration of structural and functional data could lead to new approaches for the control of parasitic diseases

Unlocking the Transcriptomes of Two Carcinogenic Parasites, Clonorchis sinensis and Opisthorchis viverrini

The two parasitic trematodes, Clonorchis sinensis and Opisthorchis viverrini, have a major impact on the health of tens of millions of humans throughout Asia. The greatest impact is through the malignant cancer ( = cholangiocarcinoma) that these parasites induce in chronically infected people. Therefore, both C. sinensis and O. viverrini have been classified by the World Health Organization (WHO) as Group 1 carcinogens. Despite their impact, little is known about these parasites and their interplay with the host at the molecular level. Recent advances in genomics and bioinformatics provide unique opportunities to gain improved insights into the biology of parasites as well as their relationships with their hosts at the molecular level. The present study elucidates the transcriptomes of C. sinensis and O. viverrini using a platform based on next-generation (high throughput) sequencing and advanced in silico analyses. From 500,000 sequences, >50,000 sequences were assembled for each species and categorized as biologically relevant based on homology searches, gene ontology and/or pathway mapping. The results of the present study could assist in defining molecules that are essential for the development, reproduction and survival of liver flukes and/or that are linked to the development of cholangiocarcinoma. This study also lays a foundation for future genomic and proteomic research of C. sinensis and O. viverrini and the cancers that they are known to induce, as well as novel intervention strategies

Elevated Plasma IL-6 Associates with Increased Risk of Advanced Fibrosis and Cholangiocarcinoma in Individuals Infected by Opisthorchis viverrini

Opisthorchis viverrini is considered among the most important of the food-borne trematodes due to its strong association with advanced periductal fibrosis and bile duct cancer (cholangiocarcinoma). We investigated the relationship between plasma levels of Interleukin (IL)-6 and the risk of developing advanced fibrosis and bile duct cancer from chronic Opisthorchis infection. We show that IL-6 circulates in plasma at concentrations 58 times higher in individuals with advanced fibrosis than age, sex, and nearest-neighbor matched controls and 221 times higher in individuals with bile duct cancer than controls. We also observed a dose-response relationship between increasing levels of plasma IL-6 and increasing risk of advanced fibrosis and bile duct cancer; for example, in age and sex adjusted analyses, individuals with the highest quartiles of plasma IL-6 had a 19 times greater risk of developing advanced periductal fibrosis and a 150 times greater risk of developing of bile duct cancer than individuals with no detectable level of plasma IL-6. Finally, we show that a single plasma IL-6 measurement has excellent positive predictive value for the detection of both advanced bile duct fibrosis and bile duct cancer in regions with high O. viverrini transmission. These data support our hypothesis that common mechanisms drive bile duct fibrosis and bile duct tumorogenesis from chronic O. viverrini infection. Our study also adds a unique aspect to the literature on circulating levels of IL-6 as an immune marker of hepatobiliary pathology by showing that high levels of circulating IL-6 in plasma are not related to infection with O. viverrini, but to the development of the advanced and often lethal pathologies resulting from chronic O. viverrini infection

Modeling liver fluke transmission in northeast Thailand: Impacts of development, hydrology, and control.

Human infection with the Southeast Asian liver fluke Opisthorchis viverrini and liver fluke-associated cholangiocarcinoma cause significant disease burden in Southeast Asia. While there has been considerable work to understand liver fluke pathology and to reduce infection prevalence, there remains a limited understanding of the environmental determinants of parasite transmission dynamics to inform treatment and control programs. A particular setting where targeted control efforts have taken place is the Lawa Lake complex in northeast Thailand. Here, we describe the recent history of host infections, as well as the hydrologic characteristics of this floodplain ecosystem that influence the extent of snail habitat and fish mobility and the transport of human waste and parasite cercariae. Using mathematical modeling, we outline a framework for reconstructing environmental transmission of O. viverrini over the course of the Lawa Project control program from its inception in 2008 until 2016, using locally acquired but fragmentary longitudinal infection data for both humans and environmental hosts. The role of water flow in facilitating movement between snail, fish, human, and reservoir hosts is a particular focus with respect to its relevant scales and its impact on success of interventions. In this setting, we argue that an understanding of the key environmental drivers of disease transmission processes is central to the effectiveness of any environmental intervention

Modeling liver fluke transmission in northeast Thailand: Impacts of development, hydrology, and control.

Human infection with the Southeast Asian liver fluke Opisthorchis viverrini and liver fluke-associated cholangiocarcinoma cause significant disease burden in Southeast Asia. While there has been considerable work to understand liver fluke pathology and to reduce infection prevalence, there remains a limited understanding of the environmental determinants of parasite transmission dynamics to inform treatment and control programs. A particular setting where targeted control efforts have taken place is the Lawa Lake complex in northeast Thailand. Here, we describe the recent history of host infections, as well as the hydrologic characteristics of this floodplain ecosystem that influence the extent of snail habitat and fish mobility and the transport of human waste and parasite cercariae. Using mathematical modeling, we outline a framework for reconstructing environmental transmission of O. viverrini over the course of the Lawa Project control program from its inception in 2008 until 2016, using locally acquired but fragmentary longitudinal infection data for both humans and environmental hosts. The role of water flow in facilitating movement between snail, fish, human, and reservoir hosts is a particular focus with respect to its relevant scales and its impact on success of interventions. In this setting, we argue that an understanding of the key environmental drivers of disease transmission processes is central to the effectiveness of any environmental intervention