Identification and characterization of Clonorchis sinensis cathepsin B proteases in the pathogenesis of clonorchiasis.

Wenjun Chen,Jin Xu,Jiufeng Sun,Yan Huang,Xiaoli Lv,Xiaoyun Wang,Tingjin Chen,Dan Ning,De Wu,Xinbing Yu

doi:10.1186/s13071-015-1248-9

Abstract

BackgroundHuman clonorchiasis is a prevailing food-borne disease caused by Clonorchis sinensis infection. Functional characterizations of key molecules from C. sinensis could facilitate the intervention of C. sinensis associated diseases.MethodsIn this study, immunolocalization of C. sinensis cathepsin B proteases (CsCBs) in C. sinensis worms was investigated. Four CsCBs were expressed in Pichia pastoris yeast cells. Purified yCsCBs were measured for enzymatic and hydrolase activities in the presence of various host proteins. Cell proliferation, wound-healing and transwell assays were performed to show the effect of CsCBs on human cells.ResultsCsCBs were localized in the excretory vesicle, oral sucker and intestinal tract of C. sinensis. Recombinant yCsCBs from yeast showed active enzymatic activity at pH 5.0–5.5 and at 37–42 °C. yCsCBs can degrade various host proteins including human serum albumin, human fibronectin, human hemoglobin and human IgG. CsCBs were detected in liver tissues of mice and cancer patients afflicted with clonorchiasis. Various bioassays collectively demonstrated that CsCBs could promote cell proliferation, migration and invasion of human cancer cells.ConclusionOur results demonstrated that CsCBs can degrade various human proteins and we proved that the secreted CsCBs are involved in the pathogenesis of clonorchiasis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-015-1248-9) contains supplementary material, which is available to authorized users.

Highlights

Human clonorchiasis is a prevailing food-borne disease caused by Clonorchis sinensis infection
Adult worms reside in the bile ducts of hosts and secreted products from C. sinensis eventually lead to clonorchiasis resulting in: cholangectasis, cholecystitis, cholelithiasis, hepatic fibrosis, and even liver cancer and bile duct cancer [1,2,3]
Our results provide evidence to support the role of C. sinensis cathepsin B proteases (CsCBs) in the pathogenesis of clonorchiasis

Summary

Introduction

Human clonorchiasis is a prevailing food-borne disease caused by Clonorchis sinensis infection. Clonorchiasis is a food-borne parasitic disease caused by infection with Clonorchis sinensis (C. sinensis). Adult worms reside in the bile ducts of hosts and secreted products from C. sinensis eventually lead to clonorchiasis resulting in: cholangectasis, cholecystitis, cholelithiasis, hepatic fibrosis, and even liver cancer and bile duct cancer [1,2,3]. It is estimated that about 35 million people are afflicted with clonorchiasis, with most cases in Asian countries such as Korea, China and Vietnam [4, 5]. Food security problems caused by liver flukes have attracted high attention of public health, increasing the urgency of finding new approaches to prevent the spread of clonorchiasis. Clonorchiasis is listed among food-borne parasitic diseases requiring urgent control in China

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