Exploring the second intermediate hosts and morphology of human- and cat-specific Opisthorchis viverrini-like populations.

Infection by the zoonotic fish-borne trematode, Opisthorchis viverrini, remains a crucial health issue in Thailand and neighboring countries. Recently, molecular analysis revealed two populations of putative O. viverrini: one found primarily in human hosts ("human-specific" population) and the other primarily in cats ("cat-specific" population). It is unclear how the infective stages (metacercariae) of these different populations circulate among definitive and reservoir hosts in nature. To gain an insight into this, mitochondrial cox1 and nad1 gene sequences of metacercariae from fish intermediate hosts were examined. None of 192 metacercariae from cyprinid fish in Lao PDR and Thailand had sequences typical of "cat-specific" O. viverrini, suggesting that cyprinid fish are not the main second intermediate hosts of this population. Interestingly, all 20 O. viverrini-like metacercariae from snakehead fish (Channa striata) shared 99.51-100% sequence identity with eggs from cats naturally infected in a previous study. Hence, we propose a modification of the known transmission dynamics of O. viverrini: consumption of metacercariae within snakehead fish provides another pathway for cats and (occasionally) humans to acquire infection. We also performed morphological comparisons of eggs, metacercariae, and adult flukes (raised in hamsters) of both Opisthorchis populations. The "cat-specific" population has eggs that are narrower and adults that are shorter and wider than in the human-specific population. The metacercaria of the "cat-specific" population is elliptical, while that of the "human-specific" population is oval, occasionally rounded. Our results confirmed that O. viverrini-like metacercariae from snakehead fish are the infective stages of the "cat-specific" fluke. This provides a new insight into the dissemination and transmission of each population in the second intermediate host. The identity of the cat-specific population is discussed.

Inflammatory responses to Opisthorchis viverrini infection in animal models: A comparison between susceptible and nonsusceptible hosts in different anatomical locations.

Background: Inflammation caused by Opisthorchis viverrini infection increases the risk of cholangitis, cholecystitis, and leads to bile duct cancer (cholangiocarcinoma or CCA). However, only certain infected individuals are susceptible to CCA, suggesting the involvement of host factors in cancer development. In addition, there are reports indicating differences in the locations of CCA. Aim: This study aims to investigate cellular inflammatory responses in the common bile duct (CB), intrahepatic bile duct (IHB), and gallbladder (GB) in susceptible and non-susceptible hosts following O. viverrini infection. Methods: Thirty Syrian golden hamsters (a susceptible host) and 30 BALB/c mice (a non-susceptible host) infected with O. viverrini were studied at six time points (five animals per group). Histopathological evaluations were conducted on samples from the IHB, CB, and GB. Inflammatory cell infiltration was quantitatively assessed and compared between groups and time points. Statistical analysis was performed using one-way ANOVA, with a significance level of p < 0.05. Results: Inflammation was significantly more pronounced in the IHB compared to the other two biliary locations. In comparison between susceptible and non-susceptible hosts, the intensity of inflammation was higher in the OV+H group than in the OV+M group (p < 0.05). Conclusion: This study highlights the association between host response to inflammation, tissue location, and host susceptibility, with the IHB showing particular susceptibility to inflammation and pathological changes. These findings contribute to our understanding of the increased risk of CCA in susceptible hosts.

Opisthorchis viverrini excretory-secretory products suppress GLUT8 of cholangiocytes.

Opisthorchis viverrini infection and the subsequent bile duct cancer it induces remains a significant public health problem in Southeast Asia. Opisthorchiasis has been reported to cause reduced plasma glucose levels among infected patients. The underlying mechanism for this phenomenon is unclear. In the present study, evidence is presented to support the hypothesis that O. viverrini exploits host cholangiocyte glucose transporters (GLUTs) in a similar manner to that of rodent intestinal nematodes, to feed on unabsorbed glucose in the bile for survival. GLUT levels in a cholangiocyte H69 cell line co-cultured with excretory-secretory products of O. viverrini were examined using qPCR and immunoblotting. GLUT 8 mRNA and expressed proteins were found to be downregulated in H69 cells in the presence of O. viverrini. This suggests that O. viverrini alters glucose metabolism in cells within its vicinity by limiting transporter expression resulting in increased bile glucose that it can utilize and potentially explains the previously reported anti-insulin effect of opisthorchiasis.

T helper cell responses to Opisthorchis viverrini infection associate with host susceptibility.

Opisthorchis viverrini infection is endemic in the lower Mekong subregion. The liver is an organ that worms are drawn to and cause damage. However, the immune-related susceptibility in the liver is poorly understood. In this study, we investigated T helper (Th) cell responses in the liver of BALB/c mice and golden Syrian hamsters during 2-28 days post-infection (DPI). We found that Th cell responses were distinct between mice and hamsters in terms of dynamics and polarization. Mice exhibited the early induction of Th1, Th2, Th17, and regulatory T (Treg) cells responses after the presence of O. viverrini worms at 2 DPI. In hamsters, the late induction of Th1/Th17, downregulation of Th2/Treg responses and early elevation of suppressive cytokine interleukin (IL)-10 were found together with swift reduction of Th cell numbers. Interestingly, expressions of IL-4 (Th2 functional cytokine) and Foxp3 (Treg lineage) were completely different between mice and hamsters which elevated in mice but suppressed in hamsters. These results suggest that early induction and well-regulation are related to host resistance. In contrast, late induction of Th cell response might allow immature worms to develop in the host. Our findings provide a greater understanding in Th cell response-related susceptibility in O. viverrini infection which would be targeting immunity for the development of immune-based intervention such as vaccine.

Recombinant protein production and functional analysis of a M60-like-2 metallopeptidase enzyme from the carcinogenic liver fluke Opisthorchis viverrini.

Mucin plays a crucial role in safeguarding mucosal tissues by obstructing the translocation of microorganisms. Mucosal tissue-dwelling parasites must devise a strategy to surmount this mucin barrier in order to establish colonization. In a recent discovery, it was observed that the liver fluke Opisthorchis viverrini secretes two mucinases, namely Ov-M60-like-1 and Ov-M60-like-2. Ov-M60-like-1 was previously characterized. Here, we study the Ov-M60-like-2 by utilizing the wheat germ expression system to produce recombinant proteins and conducted a functional analysis of its enzymatic activity on bovine submaxillary mucin (BSM). Subsequently, we delved deeper into understanding the role of this enzyme in host-parasite interactions by evaluating its mucinase activity on mucins from the bile duct of O. viverrini-infected hamsters. Through successful production of recombinant proteins using the wheat germ expression system, we observed that this enzyme displayed mucinase activity over a wide pH range (pH 2 to pH 10) against BSM. Our investigations revealed it ability to digest mucin from the bile duct. These findings suggest that Ov-M60-like-2 possess a mucinase activity, together with Ov-M60-like-1, enabling the liver fluke to successful colonization of the host's bile duct.

Inflammatory cell responses in biliary mucosa during Opisthorchis viverrini infection: Insights into susceptibility differences among hosts.

Background: Individual host susceptibility is believed to be a risk factor in the interaction between the host and the parasite. Since studying time series in humans is limited, animal models are replaced. Aim: This study aims to explore and compare the pattern of inflammatory cell types along the biliary tract and their association with proliferative lesions in the early development of cholangiocarcinoma from susceptible and nonsusceptible animal models. Methods: Thirty male Syrian golden hamsters and 30 BALB/c mice, serving as the susceptible and nonsusceptible animal models, were used in this comparative study. The animals were infected with 50 Opisthorchis viverrini metacercariae via gastric intubation. At days 1, 2, 7, 14, 28, and 56 postinfection (p.i.), five animals were randomly selected from each group and humanely sacrificed. The hepatobiliary tissues were collected and processed for histopathological study. Histochemical and immunohistochemical staining were applied to differentiate the inflammatory cell types. Kruskal-Wallis and Mann-Whitney tests were applied to assess all semi-quantitative and quantitative variables. The correlation between each variable was also analyzed using Spearman rank at a p-value < 0.05. Results: The results demonstrated that mice had different patterns of infiltrating cell types when compared to hamsters. This suggested that the cellular response to the infection in mice occurred earlier than that in hamsters. The response in mice reached its peak at D7 to D14 and then rapidly declined at D28. In contrast, although the inflammatory response in hamsters started slowly, the response reached the peak at D28 and maintained a high level until D56. Significant differences in the number of inflammatory cells between mice and hamsters were seen at D1 (p = 0.047), D7 (p = 0.049), D28 (p = 0.040), and D56 (p < 0.040). Conclusion: The inflammatory responses to O. viverrini infection in the nonsusceptible animal model occurred and declined earlier while the response in the susceptible animal model occurred later in a gradual manner. Both rodents are suitable animal models for the studies of opisthorchiasis susceptibility.

Association of MICA Gene Polymorphism in Opisthorchis viverrini-Induced Periductal Fibrosis in Northeastern Thais.

OBJECTIVE: Chronic Opisthorchis viverrini (OV) infection is the cause of advanced periductal fibrosis (APF), subsequently leading to cholangiocarcinoma (CCA). Natural killer (NK) cells can kill hepatic stellate cells (HSCs), the initiating cells for fibrosis formation, by using the interaction between the natural killer group 2 member D (NKG2D) receptor and its ligand on the HSCs. This can inhibit the fibrosis formation. Major histocompatibility complex class I chain-related A (MICA) is the ligand of the NKG2D receptor and has highly polymorphic characteristics that are involved in NKG2D binding and NK cell activation. This study aimed to investigate the polymorphism of MICA in OV-induced fibrosis. METHOD: MICA typing was performed by polymerase chain reaction- sequence specific primer (PCR-SSP) and sequencing in two groups: OV infection without fibrosis (N = 99) and with fibrosis (N = 290). RESULT: Six alleles were identified and the MICA*010 allele had the highest frequency in both groups. The MICA*00201-02 allele was a protective factor for fibrosis (OR= 0.508, 95%CI= 0.34-0.76, Pc <0.05), while the MICA*019 allele was suggested to be a risk allele for fibrosis (OR=1.95, 95%CI=1.25-3.03, Pc<0.005). In addition, two motifs, glycine (G) at position 14 and glutamine (Q) at position 251, were negatively associated with fibrosis (G14: OR=0.508, 95%CI=0.34-0.76, Pc <0.05 and Q251: OR=0.586, 95%CI=0.41-0.84, Pc <0.05). Moreover, the distribution of the MICA-129 genotype also showed the protective genotype (Pc<0.05, OR=0.319, 95%CI= 0.12-0.54) for fibrosis. The MICA*00201-02 allele encoded all these motifs, and this suggested that it might lead to strong NK cell activation to kill HSCs, subsequently preventing fibrosis formation. CONCLUSION: This study described initial evidence suggesting that the polymorphism of the MICA gene might be a marker for OV-derived periductal fibrosis.

Distinct antibody response in susceptible and non-susceptible hosts of the carcinogenic liver fluke Opisthorchis viverrini infection.

Opisthorchis viverrini is a carcinogenic parasite that can cause bile duct cancer called cholangiocarcinoma. A study of the immune response of this parasite in susceptible and non-susceptible hosts may provide a clue to develop vaccines and immunodiagnostic markers, which are currently not available. Here, we compared the antibody response in susceptible Golden Syrian hamsters and non-susceptible BALB/c mice infected by the liver fluke. In mice, the antibody was detected between 1 and 2 weeks post-infection, whereas it was positive between 2 and 4 weeks post-infection in hamsters. Immunolocalization revealed that the antibody from mice reacts strongly with the tegumental surface and gut epithelium of the worm, while hamster antibody showed a weak signal in the tegument and a comparable signal in the gut of the worm. Immunoblot of the tegumental proteins demonstrated that while hamster antibody showed a broad specificity, mice strongly reacted with a single protein band. Mass spectrometry revealed these immunogenic targets. Recombinant proteins of the reactive targets were produced in the bacterial expression system. The immunoblot of these recombinant proteins confirm the reactivity of their native form. In summary, there is a different antibody response against O. viverrini infection in susceptible and non-susceptible hosts. The non-susceptible host reacts quicker and stronger than the susceptible host.

Immunolocalization and functional analysis of Opisthorchis viverrini-M60-like-1 metallopeptidase in animal models.

Host mucins have crucial physical roles in preventing the parasitic establishment and maturation, and also in expelling the invading parasites. However, some parasites utilize mucinase enzymes to facilitate the infection. Recently, we have identified a mucinase enzyme of the liver fluke Opisthorchis viverrini, Ov-M60-like-1, which exhibits metallopeptidase activity against bovine submaxillary mucin substrate. Here, we aimed to study the localization of this enzyme in O. viverrini and the bile duct of hamsters using immunohistochemistry and functional analysis by mucin digestion in hamsters and mice tissues. The results showed that Ov-M60-like-1 was detected strongly in the tegument, tegumental cells, vitelline glands and mature eggs with miracidium. Expression in the gut, ovary and testis of the parasite was moderate while parenchyma showed slight colour intensity. In addition, the mucinase was also detected in the host biliary epithelial cells and goblet cells surrounding the worm. The mucinase assay revealed that the Ov-M60-like-1 could digest neutral mucin in the parenchyma, testis and seminal receptacle, but not the mucin in the tegument, tegumental cells and vitelline glands of the worm. The enzyme can also digest mucin in the cholangiocytes and modified the mixture type in the bile duct goblet cells of the infected hamsters, a susceptible host. In contrast, the enzyme was unable to digest neutral, acid and mixture mucin in the bile duct of the mice, a non-susceptible host. These findings indicate that Ov-M60-like-1 may have functions in both housekeeping tasks and host­parasite interactions, especially in modification of host susceptibility.

Population dynamics and diversity of trematode infections in Bithynia siamensis goniomphalos in an irrigated area in northeast Thailand.

Several trematodes including Opisthorchis viverrini utilize Bithynia siamensis goniomphalos as a snail intermediate host in their life cycles. In order to capture a comprehensive range of host­parasite interactions and their transmission dynamic patterns, B. s. goniomphalos were sampled monthly over 4 consecutive years in an irrigated paddy-field habitat in northeast Thailand. Using a standard cercarial shedding method, a high diversity of trematodes (17 types) was recovered. Virgulate xiphidiocercariae were the most prevalent (7.84%) followed by O. viverrini (0.71%). In addition to seasonal and environmental factors, the quantity of irrigation water for rice cultivation correlated with transmission dynamics of trematodes in B. s. goniomphalos. The peak prevalence of all trematode infections combined in the snails shifted from the cool-dry season in 2010­2012 to the hot-dry season in 2013 associated with an increasing quantity of water irrigation. A low frequency of mixed trematode infections was found, indicating that the emergence of virgulate cercariae, but not of O. viverrini, was negatively impacted by the presence of other trematodes in the same snail. Taken together, the observed results suggest that interactions between host and parasite, and hence transmission dynamics, depend on specific characteristics of the parasite and environmental factors including irrigated water for rice cultivation.

Helicobacter pylori GroEL Seropositivity Is Associated with an Increased Risk of Opisthorchis viverrini-Associated Hepatobiliary Abnormalities and Cholangiocarcinoma.

Despite the synergistic effect of Opisthorchis viverrini and Helicobacter pylori co-infection on pathogenesis of severe hepatobiliary abnormalities (HBA) including advanced periductal fibrosis and replace with cholangiocarcinoma (CCA) have been established, the immune response to H. pylori in O. viverrini infected population has never been explored. Hence, this study aimed to investigate the antibody responses to 2 immunogenic H. pylori proteins in O. viverrini-infected patients with HBA and CCA. The risk analysis by multinomial logistic regression revealed that GroEL seropositivity was associated with higher risks of hepatobiliary abnormalities and CCA with adjusted odds ratios (95% confidence intervals) of 2.11 (95% CI=1.20-3.71, P=0.008) and 2.13 (95% CI=1.21-3.75, P=0.009), respectively. These findings indicate that GroEL seropositivity might be a biomarker for early detection of O. viverrini associated HBA and CCA.

Correction: Doum, D., et al. Dengue Seroprevalence and Seroconversion in Urban and Rural Populations in Northeastern Thailand and Southern Laos. Int. J. Environ. Res. Public Health 2020, 17, 9134.

There was an error in the original article [...].

Dengue Seroprevalence and Seroconversion in Urban and Rural Populations in Northeastern Thailand and Southern Laos.

Dengue is the most rapidly spreading mosquito-borne viral disease in the world. The detection of clinical cases enables us to measure the incidence of dengue infection, whereas serological surveys give insights into the prevalence of infection. This study aimed to determine dengue seroprevalence and seroconversion rates in northeastern Thailand and southern Laos and to assess any association of mosquito control methods and socioeconomic factors with dengue virus (DENV) infection. Cross-sectional seroprevalence surveys were performed in May and November 2019 on the same individuals. Blood samples were collected from one adult and one child, when possible, in each of 720 randomly selected households from two urban and two rural sites in both northeastern Thailand and southern Laos. IgG antibodies against DENV were detected in serum using a commercial enzyme-linked immunosorbent assay (ELISA) kit. Overall, 1071 individuals participated in the study. The seroprevalence rate was high (91.5%) across all 8 study sites. Only age and province were associated with seroprevalence rates. There were 33 seroconversions during the period from May to November, of which seven reported fever. More than half of the seroconversions occurred in the rural areas and in Laos. Dengue seroconversion was significantly associated with young age (<15 years old), female gender, province, and duration of living in the current residence. No socioeconomic factors or mosquito control methods were found to be associated with seroprevalence or seroconversion. Notably, however, the province with most seroconversions had lower diurnal temperature ranges than elsewhere. In conclusion, our study has highlighted the homogeneity of dengue exposure across a wide range of settings and most notably those from rural and urban areas. Dengue can no longer be considered to be solely an urban disease nor necessarily one linked to poverty.

Characterization and in vitro functional analysis of thioredoxin glutathione reductase from the liver fluke Opisthorchis viverrini.

The carcinogenic liver fluke Opisthorchis viverrini causes several hepatobiliary diseases including a bile duct cancer-cholangiocarcinoma (CCA), which is a major public health problem in many countries in the Greater Mekong Sub-region. Praziquantel is the main drug against this parasite, however, reduced drug efficacy has been observed in some endemic areas. Therefore, alternative drugs are needed to prepare for praziquantel resistance in the future. The selenoprotein thioredoxin glutathione reductase (TGR) enzyme, which plays a crucial role in cellular redox balance of parasitic flatworms, has been shown as a potential drug target against these parasites. Hence, this study aimed to investigate the TGR of O. viverrini and assess its potential as a drug target. An open reading frame (ORF) that encodes O. viverrini TGR (Ov-TGR) was cloned from an O. viverrini cDNA library and the nucleotide were sequenced. The 1,812 nucleotides of the Ov-TGR full ORF encoded a polypeptide of 603 amino acid residues with a predicted molecular mass of 66 kDa. The putative amino acid sequence shared 55-96.8% similarities with TGRs from other helminths and mammals. Phylogenetic analysis revealed a close relationship of Ov-TGR with that of other trematodes. The ORF of Ov-TGR was inserted into pABC2 plasmid and transformed into Escherichia coli strain C321.ΔA to facilitate selenocysteine incorporation. The recombinant Ov-TGR (rOv-TGR-SEC) was expressed as a soluble protein and detected as a dimer form in the non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Its thioredoxin reductase (TrxR) and glutathione reductase (GR) activities were detected using DTNB, Trx and GSSG substrates with the Michaelis constant (Km) of 292.6 ± 52.3 µM, 8.09 ± 1.91 µM and 13.74 ± 1.2 µM, respectively. The TGR enzyme activities were effectively inhibited by a well-known inhibitor, auranofin in a dose-dependent manner. Moreover, auranofin expressed a lethal toxic effect on both newly excysted juveniles (NEJs) and adult worms of O. viverrini in vitro. Taken together, these results indicated that Ov-TGR is crucial for O. viverrini survival and maybe a potential target for the development of novel agents against opisthorschiasis.

Identification, recombinant protein production, and functional analysis of a M60-like metallopeptidase, secreted by the liver fluke Opisthorchis viverrini.

The carcinogenic liver fluke Opisthorchis viverrini (O. viverrini) is endemic in Thailand and neighboring countries including Laos PDR, Vietnam and Cambodia. Infections with O. viverrini lead to hepatobiliary abnormalities including bile duct cancer-cholangiocarcinoma (CCA). Despite decades of extensive studies, the underlying mechanisms of how this parasite survives in the bile duct and causes disease are still unclear. Therefore, this study aims to identify and characterize the most abundant protein secreted by the parasite. Proteomics and bioinformatics analysis revealed that the most abundant secretory protein is a metallopeptidase, named Ov-M60-like-1. This protein contains an N-terminal carbohydrate-binding domain and a C-terminal M60-like domain with a zinc metallopeptidase HEXXH motif. Further analysis by mass spectrometry revealed that Ov-M60-like-1 is N-glycosylated. Recombinant Ov-M60-like-1 (rOv-M60-like-1) expressed in Escherichia coli (E. coli) was able to digest bovine submaxillary mucin (BSM). The mucinase activity was inhibited by the ion chelating agent EDTA, confirming its metallopeptidase identity. The enzyme was active at temperatures ranging 25-37 °C in a broad pH range (pH 2-10). The identification of Ov-M60-like-1 mucinase as the major secretory protein of O. viverrini worms warrants further research into the role of this glycoprotein in the pathology induced by this carcinogenic worm.

A preliminary epidemiological study of pinworm infection in Thaklong Municipal Early Childhood Development Center and Rangsit Babies' Home, Pathum Thani, Thailand.

OBJECTIVES: We investigated the prevalence and risk factors for Enterobius vermicularis in children at the Thaklong Municipal Early Childhood Development Center (TMECDC), and the Rangsit Babies' Home (RBH) in Pathum Thani, Thailand using the Scotch tape method. RESULTS: 397 children aged 3-6 years were sampled (male = 198); 31 (7.8%) were E. vermicularis positive: 1 (TMECDC) and 30 (RBH). 264/397 (66.50%) of parents had incomes > 12,000 baht/month and 313/397 (78.84%) were educated from primary school to college. Univariate analysis identified (i) age 5-6 years, (ii) female sex, (iii) lower education of mother/father, (iv) being a house wife, (v) being a low income family, (vi) being resident in the orphanage, (vii) reporting anorexia and/or fever, and (viii) not washing their bottoms as factors for a positive slide. By logistic regression, education level and age group were independently associated with a positive Scotch tape result. Older children and higher family education had opposing associations with E. vermicularis. Strategies to control pinworm infection should focus on high-risk children in orphanages.

Diagnostic performance of urinary IgG antibody detection: A novel approach for population screening of strongyloidiasis.

The diagnosis of strongyloidiasis by coprological methods has a low sensitivity, underestimating the prevalence of Strongyloides stercoralis in endemic areas. Serodiagnostic tests for strongyloidiasis have shown robust diagnostic properties. However, these methods require a blood draw, an invasive and labor-intensive sample collection method, especially in the resource-limited settings where S. stercoralis is endemic. Our study examines a urine-based assay for strongyloidiasis and compares its diagnostic accuracy with coprological and serological methods. Receiver operating characteristic (ROC) curve analyses determined the diagnostic sensitivity (D-Sn) and specificity (D-Sp) of the urine ELISA, as well as estimates its positive predictive value and diagnostic risk. The likelihood ratios of obtaining a positive test result (LR+) or a negative test result (LR-) were calculated for each diagnostic positivity threshold. The urine ELISA assay correlated significantly with the serological ELISA assay for strongyloidiasis, with a D-Sn of 92.7% and a D-Sp of 40.7%, when compared to coprological methods. Moreover, the urine ELISA IgG test had a detection rate of 69%, which far exceeds the coprological method (28%). The likelihood of a positive diagnosis of strongyloidiasis by the urine ELISA IgG test increased significantly with increasing units of IgG detected in urine. The urine ELISA IgG assay for strongyloidiasis assay has a diagnostic accuracy comparable to serological assay, both of which are more sensitive than coprological methods. Since the collection of urine is easy and non-invasive, the urine ELISA IgG assay for strongyloidiasis could be used to screen populations at risk for strongyloidiasis in S. stercoralis endemic areas.

Epidemiology of Opisthorchis viverrini Infection.

Opisthorchiasis in the Lower Mekong Subregion is a parasitic disease caused by the liver fluke Opisthorchis viverrini. This parasite has a well-documented distribution in Thailand, Lao PDR, Cambodia, Myanmar and Southern Vietnam. In this chapter, we describe the current knowledge of the epidemiology of O. viverrini infection, highlighting advances in control efforts made in the last four decades in Thailand and identifying ongoing gaps in our epidemiological knowledge which need to be filled to support efforts to permanently overcome the heavy morbidity and mortality burden caused by these parasites within their endemic regions.

Elevated Levels of Urinary 8-oxodG Correlate with Persistent Periductal Fibrosis after Praziquantel Treatment in Chronic Opisthorchiasis.

Previous studies demonstrated that urinary 8-oxodG is a predictive biomarker for Opisthorchis viverrini (OV)-associated hepatobiliary disease (HBD) and cholangiocarcinoma (CCA). This study examined the effects of praziquantel treatment on the profile of urinary 8-oxodG in relation to HBD status. Infection with OV, levels of urinary 8-oxodG, and HBD status in terms of periductal fibrosis (PDF) assessed by abdominal ultrasonography (US) were monitored and compared in cohorts of participants in Khon Kaen, Thailand, before and 1 year after praziquantel treatment. Urinary 8-oxodG levels significantly decreased after treatment compared with the baseline level in OV-infected participants who had no HBD (PDF negative; PDF-ve) (N = 14). Levels of 8-oxodG were unchanged after treatment in OV-infected subjects (OV+ve) who had positive PDF (N = 52). Within the positive PDF (PDF+ve) group who became PDF-ve after treatment, there was no significant change in 8-oxodG levels between pre-and posttreatment (reversible PDF = 65.3%). In those who had persistent PDF+ve at both ultrasound sampling points, there was no significant difference in urinary 8-oxodG levels between pre- and posttreatment (persistent PDF = 34.6%). Based on a logistic regression model and receiver operation curve analysis, the increase of 8-oxodG levels was found to be associated with increasing risk of PDF. Measurement of urinary 8-oxodG and US increased the likelihood of discovering persistent PDF, which is a predictable condition for the patients at risk of OV-associated CCA. To identify high-risk individuals for CCA, it is useful to perform US in combination with urinary 8-oxodG measurement.

Levels of 8-OxodG Predict Hepatobiliary Pathology in Opisthorchis viverrini Endemic Settings in Thailand.

Opisthorchis viverrini is distinct among helminth infections as it drives a chronic inflammatory response in the intrahepatic bile duct that progresses from advanced periductal fibrosis (APF) to cholangiocarcinoma (CCA). Extensive research shows that oxidative stress (OS) plays a critical role in the transition from chronic O. viverrini infection to CCA. OS also results in the excision of a modified DNA lesion (8-oxodG) into urine, the levels of which can be detected by immunoassay. Herein, we measured concentrations of urine 8-oxodG by immunoassay from the following four groups in the Khon Kaen Cancer Cohort study: (1) O. viverrini negative individuals, (2) O. viverrini positive individuals with no APF as determined by abdominal ultrasound, (3) O. viverrini positive individuals with APF as determined by abdominal ultrasound, and (4) O. viverrini induced cases of CCA. A logistic regression model was used to evaluate the utility of creatinine-adjusted urinary 8-oxodG among these groups, along with demographic, behavioral, and immunological risk factors. Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive accuracy of urinary 8-oxodG for APF and CCA. Elevated concentrations of 8-oxodG in urine positively associated with APF and CCA in a strongly dose-dependent manner. Urinary 8-oxodG concentrations also accurately predicted whether an individual presented with APF or CCA compared to O. viverrini infected individuals without these pathologies. In conclusion, urinary 8-oxodG is a robust 'candidate' biomarker of the progression of APF and CCA from chronic opisthorchiasis, which is indicative of the critical role that OS plays in both of these advanced hepatobiliary pathologies. The findings also confirm our previous observations that severe liver pathology occurs early and asymptomatically in residents of O. viverrini endemic regions, where individuals are infected for years (often decades) with this food-borne pathogen. These findings also contribute to an expanding literature on 8-oxodG in an easily accessible bodily fluid (e.g., urine) as a biomarker in the multistage process of inflammation, fibrogenesis, and infection-induced cancer.