Expression, refolding and purification of Ov-GRN-1, a granulin-like growth factor from the carcinogenic liver fluke, that causes proliferation of mammalian host cells

Animal granulins: In the GRN scheme of things

Granulins are conserved in nearly all metazoans, with an intriguing loss in insects. These pleiotropic peptides are involved in numerous physiological and pathological processes yet have been overwhelmingly examined in mammalian systems. While work in other animal models has been informative, a richer understanding of the proteins should be obtained by integrating knowledge from all available contexts. The main bodies of work described here include 1) the structure-function relationships of progranulin and its cleavage products, 2) the role of expanded granulin gene families and different isoforms in fish immunology, 3) the release of granulin peptides to promote host angiogenesis by parasitic worms, 4) a diversity of molluscan uses for granulins, including immune activation in intermediate hosts to trematodes, 5) knowledge gained on lysosomal functions from C. elegans and the stress-related activities of granulins. We provide an overview of functional reports across the Metazoa to inform much-needed future research.

Inflammatory pathways and cholangiocarcinoma risk mechanisms and prevention

Cholangiocarcinoma (CCA), a neoplasm burdened by a poor prognosis and currently lacking adequate therapeutic treatments, can originate at different levels of the biliary tree, in the intrahepatic, hilar, or extrahepatic area. The main risk factors for the development of CCA are the presence of chronic cholangiopathies of various etiology. To date, the most studied prodromal diseases of CCA are primary sclerosing cholangitis, Caroli's disease and fluke infestations, but other conditions, such as metabolic syndrome, nonalcoholic fatty liver disease and obesity, are emerging as associated with an increased risk of CCA development. In this review, we focused on the analysis of the pro-inflammatory mechanisms that induce the development of CCA and on the role of cells of the immune response in cholangiocarcinogenesis. In very recent times, these cellular mechanisms have been the subject of emerging studies aimed at verifying how the modulation of the inflammatory and immunological responses can have a therapeutic significance and how these can be used as therapeutic targets.

Identification and Analysis of the Tegument Protein and Excretory-Secretory Products of the Carcinogenic Liver Fluke Clonorchis sinensis

Liver fluke proteins, including excretory-secretory products (ESPs) and tegument proteins, are critical for the pathogenesis, nutrient metabolism, etiology and immune response of liver cancer. To understand the functions of various proteins in Clonorchis sinensis physiology and human clonorchiasis, the ESPs and tegument proteins of C. sinensis were identified. Supernatants containing ESPs from adult C. sinensis after culture for 6 h were harvested and concentrated. The tegument was detached using a freeze/thaw method and successively extracted using various extraction buffers. The outer surface proteins of C. sinensis were labeled with biotin, and the biotinylated proteins were purified. The ESP, tegument and labeled outer surface proteins were identified and analyzed by high-resolution LC-MS/MS. The identified proteins were compared with those of other flukes, and the protein functions associated with pathogenesis, carcinogenesis and potential vaccine antigens and drug targets were predicted and analyzed. A total of 175 proteins were identified after the 6-h culture of C. sinensis ESPs. A total of 352 tegument proteins were identified through sequential solubilization of the isolated teguments, and a subset of these proteins were localized to the surface membrane of the tegument by labeling with biotin. Thirty identified proteins, including annexins, actin and tetraspanins, were identified as potential immunomodulators and promising vaccine antigens. Interestingly, among the 352 tegument proteins, as many as 155 were enzymes, and most were oxidoreductases, hydrolases or transferases. A comparison of the outer surface proteins of C. sinensis with those of other flukes indicated that flukes have some common outer surface proteins, such as actin, tetraspanin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and annexin. Granulin, thioredoxin peroxiredoxin, carbonyl reductase 1 and cystatin were identified in the C. sinensis proteome and predicted to be related to liver disease and cancer. The analysis of the C. sinensis proteome could contribute to a more in-depth understanding of complex parasite-host relationships, improve the diagnosis of clonorchiasis and benefit research on the pathogenesis and development of novel interventions, drugs and vaccines to control C. sinensis infection.

Liver fluke granulin promotes extracellular vesicle-mediated crosstalk and cellular microenvironment conducive to cholangiocarcinoma

Crosstalk between malignant and neighboring cells contributes to tumor growth. In East Asia, infection with the liver fluke is a major risk factor for cholangiocarcinoma (CCA). The liver fluke Opisthorchis viverrini secretes a growth factor termed liver fluke granulin, a homologue of the human progranulin, which contributes significantly to biliary tract fibrosis and morbidity. Here, extracellular vesicle (EV)-mediated transfer of mRNAs from human cholangiocytes to naïve recipient cells was investigated following exposure to liver fluke granulin. To minimize the influence of endogenous progranulin, its cognate gene was inactivated using CRISPR/Cas9-based gene knock-out. Several progranulin-depleted cell lines, termed ΔhuPGRN-H69, were established. These lines exhibited >80% reductions in levels of specific transcript and progranulin, both in gene-edited cells and within EVs released by these cells. Profiles of extracellular vesicle RNAs (evRNA) from ΔhuPGRN-H69 for CCA-associated characteristics revealed a paucity of transcripts for estrogen- and Wnt-signaling pathways, peptidase inhibitors and tyrosine phosphatase related to cellular processes including oncogenic transformation. Several CCA-specific evRNAs including MAPK/AKT pathway members were induced by exposure to liver fluke granulin. By comparison, estrogen, Wnt/PI3K and TGF signaling and other CCA pathway mRNAs were upregulated in wild type H69 cells exposed to liver fluke granulin. Of these, CCA-associated evRNAs modified the CCA microenvironment in naïve cells co-cultured with EVs from ΔhuPGRN-H69 cells exposed to liver fluke granulin, and induced translation of MAPK phosphorylation related-protein in naïve recipient cells in comparison with control recipient cells. Exosome-mediated crosstalk in response to liver fluke granulin promoted a CCA-specific program through MAPK pathway which, in turn, established a CCA-conducive disposition.

Conotoxins: Chemistry and Biology

The venom of the marine predatory cone snails (genus Conus) has evolved for prey capture and defense, providing the basis for survival and rapid diversification of the now estimated 750+ species. A typical Conus venom contains hundreds to thousands of bioactive peptides known as conotoxins. These mostly disulfide-rich and well-structured peptides act on a wide range of targets such as ion channels, G protein-coupled receptors, transporters, and enzymes. Conotoxins are of interest to neuroscientists as well as drug developers due to their exquisite potency and selectivity, not just against prey but also mammalian targets, thereby providing a rich source of molecular probes and therapeutic leads. The rise of integrated venomics has accelerated conotoxin discovery with now well over 10,000 conotoxin sequences published. However, their structural and pharmacological characterization lags considerably behind. In this review, we highlight the diversity of new conotoxins uncovered since 2014, their three-dimensional structures and folds, novel chemical approaches to their syntheses, and their value as pharmacological tools to unravel complex biology. Additionally, we discuss challenges and future directions for the field.

Liver Fluke-Associated Biliary Tract Cancer

Cholangiocarcinoma (CCA) is an aggressive cancer arising from epithelial cells of the bile duct. Most patients with CCA have an unresectable tumor at the time of diagnosis. In Western countries, the risk of CCA increases in patients with primary sclerosing cholangitis, whereas liver fluke infection appears to be the major risk factor for CCA in Asian countries. A diagnosis of liver fluke infection often relies on stool samples, including microscopic examination, polymerase chain reaction-based assays, and fluke antigen detection. Tests of serum, saliva and urine samples are also potentially diagnostic. The presence of liver fluke along with exogenous carcinogens magnifies the risk of CCA in people living in endemic areas. The “liver fluke-cholangiocarcinoma” carcinogenesis pathways consist of mechanical damage to the bile duct epithelium, immunopathologic and cellular reactions to the liver fluke’s antigens and excretory/secretory products, liver fluke-induced changes in the biliary tract microbiome and the effects of repeated treatment for liver fluke. A vaccine and novel biomarkers are needed for the primary and secondary prevention of CCA in endemic areas. Importantly, climate change exerts an effect on vector-borne parasitic diseases, and awareness of liver fluke should be enhanced in potentially migrated habitat areas.

Evaluation of Opisthorchis viverrini calreticulin for potential host modulation

The multifunctional calreticulin (CALR) was identified as a major calcium-binding protein of the endoplasmic reticulum before being recognized as a chaperone in the same place. Only later were activities of calreticulin outside the endoplasmic reticulum described that for example affect cell proliferation and the innate immune system. In the present work we have investigated those extracellular activities of CALR from the cancerogenic human liver fluke Opisthorchis viverrini (OvCALR), as they might be important in host/parasite interaction. We first demonstrate that OvCALR is released from the parasite and stimulates a specific humoral immune response. Recombinant OvCALR is then shown to suppress proliferation of primary endothelial cells, their motility and sprouting activities. The potential of OvCALR to interfere with the complement system is established, firstly by demonstrating its direct binding to C1q and, secondly by suppression of hemolysis of sensitized red blood cells. These findings suggest that OvCALR is an important parasite antigen that could modulate diverse host functions and support parasite survival.

Granulin Expression in Hamsters during Opisthorchis viverrini Infection-Induced Cholangiocarcinogenesis

The secreted growth factor granulin (GRN) is upregulated during diverse epithelial cancers. GRN stimulates cell growth and development while inhibiting apoptosis. Orthologues of vertebrate granulins evolved in other animals including the liver fluke Opisthorchis viverrini. Curiously, liver fluke granulin, termed Ov-GRN-1 promotes cholangiocarcinogenesis during chronic opisthorchiasis but, by contrast, limited information is available concerning mammalian GRN during liver fluke infection-induced cholangiocarcinoma (CCA). Here we investigated the expression of mammalian granulin in the O. viverrini-associated a hamster model of opisthorchiasis and liver fluke infection-induced CCA. Male Syrian golden hamsters were assigned to one of four treatment groups, each group included 30 hamsters: 1) normal (control), 2) infected with O. viverrini (OV); 3) exposed to N-dimethylnitrosamine in drinking water (DMN); and 4) infected with O. viverrini and exposed to DMN (OVDMN). Immunohistochemistry using an anti-granulin specific probe for mammalian granulin was undertaken to monitor expression and location in hepatobiliary tissues of the hamsters. In parallel, cognate studies of transcription of mRNA and protein. Histopathological examination revealed development of proliferative lesions from the onset and eruption of CCA onwards, an outcome that was most prominent in the OVDMN hamsters. Proliferating cell nuclear antigen (PCNA) index rose continuously from initiation of infection and increased with lesion progression in OV, DMN and markedly in OVDMN hamsters. Expression of GRN in biliary was elevated in biliary epithelial cells in CCA lesions in hamsters in the DMN and OVDMN groups. Expression of GRN as assayed by western blot and RT-PCR reflected the same trend as seen with PCNA. Together the histopathogical and molecular assay based findings revealed marked expression of granulin during cholangiocarcinoma in these hamsters, and highlighted the prospect that granulin represents a potential prognostic marker for cholangiocarcinoma.

Structural Variants of a Liver Fluke Derived Granulin Peptide Potently Stimulate Wound Healing

Granulins are a family of growth factors involved in cell proliferation. The liver-fluke granulin, Ov-GRN-1, isolated from a carcinogenic liver fluke Opisthorchis viverrini, can significantly accelerate wound repair in vivo and in vitro. However, it is difficult to express Ov-GRN-1 in recombinant form at high yield, impeding its utility as a drug lead. Previously we reported that a truncated analogue ( Ov-GRN_{12-35_3s}) promotes healing of cutaneous wounds in mice. NMR analysis of this analogue indicates the presence of multiple conformations, most likely as a result of proline cis/ trans isomerization. To further investigate whether the proline residues are involved in adopting the multiple confirmations, we have synthesized analogues involving mutation of the proline residues. We have shown that the proline residues have a significant influence on the structure, activity, and folding of Ov-GRN_{12-35_3s}. These results provide insight into improving the oxidative folding yield and bioactivity of Ov-GRN_{12-35_3s} and might facilitate the development of a novel wound healing agent.

Structure dissection of zebrafish progranulins identifies a well-folded granulin/epithelin module protein with pro-cell survival activities

The ancient and pluripotent progranulins contain multiple repeats of a cysteine-rich sequence motif of ∼60 amino acids, called the granulin/epithelin module (GEM) with a prototypic structure of four β-hairpins zipped together by six inter-hairpin disulfide bonds. Prevalence of this disulfide-enforced structure is assessed here by an expression screening of 19 unique GEM sequences of the four progranulins in the zebrafish genome, progranulins 1, 2, A and B. While a majority of the expressed GEM peptides did not exhibit uniquely folded conformations, module AaE from progranulin A and AbB from progranulin B were found to fold into the protopypic 4-hairpin structure along with disulfide formation. Module AaE has the most-rigid three-dimensional structure with all four β-hairpins defined using high-resolution (H-¹⁵ N) NMR spectroscopy, including 492 inter-proton nuclear Overhauser effects, 23 ³ J(HN,H_α ) coupling constants, 22 hydrogen bonds as well as 45 residual dipolar coupling constants. Three-dimensional structure of AaE and the partially folded AbB re-iterate the conformational stability of the N-terminal stack of two beta-hairpins and varying degrees of structural flexibility for the C-terminal half of the 4-hairpin global fold of the GEM repeat. A cell-based assay demonstrated a functional activity for the zebrafish granulin AaE in promoting the survival of neuronal cells, similarly to what has been found for the corresponding granulin E module in human progranulin. Finally, this work highlights the remaining challenges in structure-activity studies of proteins containing the GEM repeats, due to the apparent prevalence of structural disorder in GEM motifs despite potentially a high density of intramolecular disulfide bonds.

Granulin Secreted by the Food-Borne Liver Fluke Opisthorchis viverrini Promotes Angiogenesis in Human Endothelial Cells

The liver fluke Opisthorchis viverrini is a food-borne, zoonotic pathogen endemic to Thailand and adjacent countries in Southeast Asia. The adult developmental stage of the O. viverrini parasite excretes and secretes numerous proteins within the biliary tract including the gall bladder. Lesions caused by the feeding activities of the liver fluke represent wounds that undergo protracted cycles of healing and re-injury during chronic infection, which can last for decades. Components of the excretory/secretory (ES) complement released by the worms capably drive proliferation of bile duct epithelial cells and are implicated in establishing the oncogenic milieu that leads to bile duct cancer, cholangiocarcinoma. An ES protein, the secreted granulin-like growth factor termed Ov-GRN-1, accelerates wound resolution in mice and in vitro. To investigate angiogenesis (blood vessel development) that may contribute to wound healing promoted by liver fluke granulin and, by implication, to carcinogenesis during chronic opisthorchiasis, we employed an in vitro tubule formation assay (TFA) where human umbilical vein endothelial cells were grown on gelled basement matrix. Ten and 40 nM Ov-GRN-1 significantly stimulated angiogenesis as monitored by cellular proliferation and by TFA in real time. This demonstration of potent angiogenic property of Ov-GRN-1 bolsters earlier reports on the therapeutic potential for chronic non-healing wounds of diabetics, tobacco users, and the elderly and, in addition, showcases another of the hallmark of cancer characteristic of this carcinogenic liver fluke.

Opisthorchis viverrini Proteome and Host-Parasite Interactions

The omics technologies have improved our understanding of the molecular events that underpin host-parasite interactions and the pathogenesis of parasitic diseases. In the last decade, proteomics and genomics in particular have been used to characterize the surface and secreted products of the carcinogenic liver fluke Opisthorchis viverrini and revealed important roles for proteins at the host-parasite interface to ensure that the flukes can migrate, feed and reproduce in a hostile environment. This review summarizes the advances made in this area, primarily focusing on discoveries enabled by the publication of the fluke secreted proteomes over the last decade. Protein families that will be covered include proteases, antioxidants, oncogenic proteins and the secretion of exosome-like extracellular vesicles. Roles of these proteins in host-parasite interactions and pathogenesis of fluke-induced hepatobiliary diseases, including cholangiocarcinogenesis, are discussed. Future directions for the application of this knowledge to control infection and disease will also be discussed.

Conotoxin Φ-MiXXVIIA from the Superfamily G2 Employs a Novel Cysteine Framework that Mimics Granulin and Displays Anti-Apoptotic Activity

Conotoxins are a large family of disulfide-rich peptides that contain unique cysteine frameworks that target a broad range of ion channels and receptors. We recently discovered the 33-residue conotoxin Φ-MiXXVIIA from Conus miles with a novel cysteine framework comprising three consecutive cysteine residues and four disulfide bonds. Regioselective chemical synthesis helped decipher the disulfide bond connectivity and the structure of Φ-MiXXVIIA was determined by NMR spectroscopy. The 3D structure displays a unique topology containing two β-hairpins that resemble the N-terminal domain of granulin. Similar to granulin, Φ-MiXXVIIA promotes cell proliferation (EC₅₀ 17.85 μm) while inhibiting apoptosis (EC₅₀ 2.2 μm). Additional framework XXVII sequences were discovered with homologous signal peptides that define the new conotoxin superfamily G2. The novel structure and biological activity of Φ-MiXXVIIA expands the repertoire of disulfide-rich conotoxins that recognize mammalian receptors.

Development of a Potent Wound Healing Agent Based on the Liver Fluke Granulin Structural Fold

Granulins are a family of protein growth factors that are involved in cell proliferation. An orthologue of granulin from the human parasitic liver fluke Opisthorchis viverrini, known as Ov-GRN-1, induces angiogenesis and accelerates wound repair. Recombinant Ov-GRN-1 production is complex and poses an obstacle for clinical development. To identify the bioactive region(s) of Ov-GRN-1, four truncated N-terminal analogues were synthesized and characterized structurally using NMR spectroscopy. Peptides that contained only two native disulfide bonds lack the characteristic granulin β-hairpin structure. Remarkably, the introduction of a non-native disulfide bond was critical for formation of β-hairpin structure. Despite this structural difference, both two and three disulfide-bonded peptides drove proliferation of a human cholangiocyte cell line and demonstrated potent wound healing in mice. Peptides derived from Ov-GRN-1 are leads for novel wound healing therapeutics, as they are likely less immunogenic than the full-length protein and more convenient to produce.

Hypothetical granulin-like molecule from Fasciola hepatica identified by bioinformatics analysis

Fasciola hepatica is considered an emergent human pathogen, causing liver fibrosis or cirrhosis, conditions that are known to be direct causes of cancer. Some parasites have been categorized by WHO as carcinogenic agents such as Opisthorchis viverrini, a relative of F. hepatica. Although these two parasites are from the same class (Trematoda), the role of F. hepatica in carcinogenesis is unclear. We hypothesized that F. hepatica might share some features with O. viverrini and to be responsible to induce proliferation of host cells. We analyzed the recently released genome of F. hepatica looking for a gene coding a granulin-like growth factor, a protein secreted by O. viverrini (Ov-GRN-1), which is a potent stimulator of proliferation of host cells. Using computational biology tools, we identified a granulin-like molecule in F. hepatica, here termed FhGLM, which has high sequence identity level to Ov-GRN-1 and human progranulin. We found evidence of an upstream promoter compatible with the expression of FhGLM. The FhGLM architecture showed to have five granulin domains, one of them, the domain 3, was homologue to Ov-GRN-1 and human GRNC. The structure of the FhGLM granulin domain 3 resulted to have the overall folding of its homologue the human GRNC. Our findings show the presence of a homologue of a potent modulator of cell growth in F. hepatica that might have, as other granulins, a proliferative action on host cells during fascioliasis. Future experimental assays to demonstrate the presence of FhGLM in F. hepatica are needed to confirm our hypothesis.

Proteomic characterization of the internalization of Opisthorchis viverrini excretory/secretory products in human cells

The association between liver fluke infection caused by Opisthorchis viverrini and cholangiocarcinoma (CCA - hepatic cancer of the bile duct epithelium) has been well established. Multiple mechanisms play a role in the development of CCA, but the excretory/secretory products released by O. viverrini (OvES) represent the major interface between the parasite and its host, and their uptake by biliary epithelial cells has been suggested to be responsible for proliferation of cholangiocytes, the cells that line the biliary epithelium. Despite recent progress in the study of the molecular basis of O. viverrini-host interactions, little is known about the effects that OvES induces upon internalization by host cells. In the present study we incubated non-cancerous human cholangiocytes (H69) and human colon cancer (CaCo-2) cells with OvES and performed a time-course quantitative proteomic analysis on the cells to determine the early changes induced by the parasite. Different KEGG pathways were altered in H69 cells compared to Caco-2 cells: glycolysis/gluconeogenesis and protein processing in the endoplasmic reticulum. In addition, the Reactome pathway analysis showed a predominance of proteins involved in cellular pathways related to apoptosis and apoptotic execution phase in H69 cells after incubation with OvES. The present study provides the first proteomic analysis to address the molecular mechanisms by which OvES products interact with host cells, and Sheds light on the cellular processes involved in O. viverrini-induced CCA.

Genomics of worms, with an emphasis on Opisthorchis viverrini - opportunities for fundamental discovery and biomedical outcomes

Neglected tropical diseases cause substantial morbidity and mortality in animals and people globally. Opisthorchiasis is one such disease, caused by the carcinogenic, Asian liver fluke, Opisthorchis viverrini. This hepatobiliary disease is known to be associated with malignant cancer (cholangiocarcinoma, CCA) and affects millions of people in Asia, including Thailand, Lao People's Democratic Republic (PDR) and Cambodia. No vaccine is available, and only one drug (praziquantel) is routinely employed against the parasite. Relatively little is known about the molecular biology of the fluke itself and the disease complex that it causes in humans. With the advent of high-throughput nucleic acid sequencing and bioinformatic technologies, it has now become possible to gain global insights into the molecular biology of parasites. The purpose of this minireview is (i) to discuss recent progress on the genomics of parasitic worms, with an emphasis on the draft genome and transcriptome of O. viverrini; (ii) to use results from an integrated, global analysis of the genomic and transcriptomic data, to explain how we believe that this carcinogenic fluke establishes in the biliary system, how it feeds, survives and protects itself in such a hostile, microaerobic environment within the liver, and to propose how this parasite evades or modulates host attack; and (iii) to indicate some of the challenges, and, more importantly, the exciting opportunities that the 'omic resources for O. viverrini now provide for a plethora of fundamental and applied research areas. Looking ahead, we hope that this genomic resource stimulates vibrant and productive collaborations within a consortium context, focused on the effective control of opisthorchiasis.

Carcinogenic Parasite Secretes Growth Factor That Accelerates Wound Healing and Potentially Promotes Neoplasia

Infection with the human liver fluke Opisthorchis viverrini induces cancer of the bile ducts, cholangiocarcinoma (CCA). Injury from feeding activities of this parasite within the human biliary tree causes extensive lesions, wounds that undergo protracted cycles of healing, and re-injury over years of chronic infection. We show that O. viverrini secreted proteins accelerated wound resolution in human cholangiocytes, an outcome that was compromised following silencing of expression of the fluke-derived gene encoding the granulin-like growth factor, Ov-GRN-1. Recombinant Ov-GRN-1 induced angiogenesis and accelerated mouse wound healing. Ov-GRN-1 was internalized by human cholangiocytes and induced gene and protein expression changes associated with wound healing and cancer pathways. Given the notable but seemingly paradoxical properties of liver fluke granulin in promoting not only wound healing but also a carcinogenic microenvironment, Ov-GRN-1 likely holds marked potential as a therapeutic wound-healing agent and as a vaccine against an infection-induced cancer of major public health significance in the developing world.

Viability of developmental stages of Schistosoma mansoni quantified with xCELLigence worm real-time motility assay (xWORM)

Infection with helminth parasites causes morbidity and mortality in billions of people and livestock worldwide. Where anthelmintic drugs are available, drug resistance is a major problem in livestock parasites, and a looming threat to public health. Monitoring the efficacy of these medicines and screening for new drugs has been hindered by the lack of objective, high-throughput approaches. Several cell monitoring technologies have been adapted for parasitic worms, including video-, fluorescence-, metabolism enzyme- and impedance-based tools that minimize the screening bottleneck. Using the xCELLigence impedance-based system we previously developed a motility-viability assay that is applicable for a range of helminth parasites. Here we have improved substantially the assay by using diverse frequency settings, and have named it the xCELLigence worm real-time motility assay (xWORM). By utilizing strictly standardized mean difference analysis we compared the xWORM output measured with 10, 25 and 50 kHz frequencies to quantify the motility of schistosome adults (human blood flukes) and hatching of schistosome eggs. Furthermore, we have described a novel application of xWORM to monitor movement of schistosome cercariae, the developmental stage that is infectious to humans. For all three stages, 25 kHz was either optimal or near-optimal for monitoring and quantifying schistosome motility. These improvements in methodology sensitivity should enhance the capacity to screen small compound libraries for new drugs both for schistosomes and other helminth pathogens at large.

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25 kHz on the xCELLigence system dramatically improves the schistosome xWORM assay.

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xWORM assay can efficiently determine viability of Schistome adults or eggs.

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First time cercariae have been incorporated into an automated viability assay.

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Other helminth monitoring may benefit from alternate xCELLigence frequency options.

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

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.

A tegument-specific venom allergen-like protein of Clonorchis sinensis

Venom allergen-like (VAL) proteins, members of the SCP/TAPS (sperm coating protein/Tpx-1/Ag5/PR-1/Sc7) protein superfamily, have been reported from several parasitic helminths. As little is known about their biological functions, a VAL protein of the Chinese liver fluke Clonorchis sinensis was cloned and characterized. A complementary DNA (cDNA) encoding a 25-kDa protein was identified from an EST database of C. sinensis. A BLAST search revealed that the protein shares 46% sequence identity with Schistosoma mansoni VAL 13 protein, and thus, the protein was named CsVAL13. Multiple sequence alignment indicated that the SCP/TAPS domain of CsVAL13 shares 39-46% sequence identity with VAL proteins from parasitic helminths. His and Tyr, which help to stabilize protein structure, were highly conserved across the VAL protein sequences. Phylogenetic analysis showed that the SCP/TAPS domain of the CsVAL13 sequence clusters together with other group 2 VAL protein sequences. In the homology-modeled structure of CsVAL13, an α-β-α sandwich and residues for a putative active site were highly conserved. Immune sera were obtained from BALB/c mice immunized with the recombinant CsVAL13 protein. Immunohistochemical localization using the immune sera revealed that CsVAL13 was distributed mainly in the tegument and intrauterine eggs of adult C. sinensis. These findings suggest that CsVAL13 may be involved in host-parasite interactions and immune stimulation on the surrounding host environments.

Suppression of Ov-grn-1 encoding granulin of Opisthorchis viverrini inhibits proliferation of biliary epithelial cells

Multistep processes likely underlie cholangiocarcinogenesis induced by chronic infection with the fish-borne liver fluke, Opisthorchis viverrini. One process appears to be cellular proliferation of the host bile duct epithelia driven by excretory-secretory (ES) products of this pathogen. Specifically, the secreted growth factor Ov-GRN-1, a liver fluke granulin, is a prominent component of ES and a known driver of hyper-proliferation of cultured human and mouse cells in vitro. We show potent hyper-proliferation of human cholangiocytes induced by low nanomolar levels of recombinant Ov-GRN-1 and similar growth produced by low microgram concentrations of ES products and soluble lysates of the adult worm. To further explore the influence of Ov-GRN-1 on the flukes and the host cells, expression of Ov-grn-1 was repressed using RNA interference. Expression of Ov-grn-1 was suppressed by 95% by day 3 and by ~100% by day 7. Co-culture of Ov-grn-1 suppressed flukes with human cholangiocyte (H-69) or human cholangiocarcinoma (KKU-M214) cell lines retarded cell hyper-proliferation by 25% and 92%, respectively. Intriguingly, flukes in which expression of Ov-grn-1 was repressed were less viable in culture, suggesting that Ov-GRN-1 is an essential growth factor for survival of the adult stage of O. viverrini, at least in vitro. To summarize, specific knock down of Ov-grn-1 reduced in vitro survival and capacity of ES products to drive host cell proliferation. These findings may help to contribute to a deeper understanding of liver fluke induced cholangiocarcinogenesis.

The tumorigenic liver fluke Opisthorchis viverrini--multiple pathways to cancer

Liver fluke infection caused by Opisthorchis viverrini is a major public health problem in Thailand and adjacent countries. In addition to infection-associated morbidity, infection with O. viverrini and the related Clonorchis sinensis are unarguable risk factors for cholangiocarcinoma (CAA, bile-duct cancer). Here we review the pathogenesis of opisthorchiasis and the association between O. viverrini infection and bile-duct cancer, focusing on the molecular parallels between wound healing, chronic inflammation, and cancer development. We review a schema for human disease progression from fluke infection, chronic opisthorchiasis, advanced periductal fibrosis, and cholangiocarcinogenesis, and present a rationale for biomarker discovery to facilitate early intervention. We conclude by addressing post-genomic advances with a view to developing new control strategies to combat this infectious cancer.

A research agenda for helminth diseases of humans: basic research and enabling technologies to support control and elimination of helminthiases

Successful and sustainable intervention against human helminthiases depends on optimal utilisation of available control measures and development of new tools and strategies, as well as an understanding of the evolutionary implications of prolonged intervention on parasite populations and those of their hosts and vectors. This will depend largely on updated knowledge of relevant and fundamental parasite biology. There is a need, therefore, to exploit and apply new knowledge and techniques in order to make significant and novel gains in combating helminthiases and supporting the sustainability of current and successful mass drug administration (MDA) programmes. Among the fields of basic research that are likely to yield improved control tools, the Disease Reference Group on Helminth Infections (DRG4) has identified four broad areas that stand out as central to the development of the next generation of helminth control measures: 1) parasite genetics, genomics, and functional genomics; 2) parasite immunology; 3) (vertebrate) host–parasite interactions and immunopathology; and 4) (invertebrate) host–parasite interactions and transmission biology. The DRG4 was established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR). The Group was given the mandate to undertake a comprehensive review of recent advances in helminthiases research in order to identify notable gaps and highlight priority areas. This paper summarises recent advances and discusses challenges in the investigation of the fundamental biology of those helminth parasites under the DRG4 Group's remit according to the identified priorities, and presents a research and development agenda for basic parasite research and enabling technologies that will help support control and elimination efforts against human helminthiases.