Connexin 43 plays an important role in the transformation of cholangiocytes with Clonochis sinensis excretory-secretory protein and N-nitrosodimethylamine.

BACKGROUND: Clonorchis sinensis is a group I bio-carcinogen responsible for cholangiocarcinoma (CHCA) in humans. However, the mechanism by which C. sinensis promotes carcinogenesis is unclear. METHODOLOGY: Using the human cholangiocyte line H69, we investigated cell proliferation and gap junction protein expression after stimulation with the hepatotoxin N-nitrosodimethylamine (NDMA) and/or excretory-secretory products (ESP) of C. sinensis, which induce inflammation. NDMA and ESP treatment increased proliferation by 146% and the proportion of cells in the G2/M phase by 37%. Moreover, the expression of the cell proliferation-related proteins E2F1, Ki-67, and cancer related protein cytokeratin 19 and Cox-2 increased in response to combined treatment with NDMA and ESP. The gap-junction proteins connexin (Cx) 43 and Cx26 increased. In contrast, Cx32 expression decreased in cells treated with NDMA and ESP. Silencing of Cx43 reduced cell proliferation and significantly suppressed Cx26 and Cox-2 expression. CONCLUSIONS: These results suggest that Cx43 is an important factor in CHCA induced by C. sinensis ESP and NDMA and further investigations targeting this pathway may allow prevention of this deadly disease.

Local immune response to primary infection and re-infection by Clonorchis sinensis in FVB mice.

Although Clonorchis sinensis lives in the bile duct, few studies have investigated the local immune response in the liver and bile duct. To investigate the local immune response to C. sinensis, we investigated the activation and recruitment of various immune cells and cytokine levels in the liver and bile duct lymph nodes (BLN) in FVB mice after primary infection and re-infection. Male 4-week-old FVB mice were divided into 6 experimental groups: uninfected controls, primary infection lasting 1week (PI 1w), primary infection lasting 4weeks (PI 4w), praziquantel treatment after PI 4w (Tx), re-infection lasting 1week after Tx (RI 1w), and re-infection lasting 4weeks after Tx (RI 4w). Recovery rates were 80.0% and 73.0% in PI 1w and PI 4w mice, respectively, but significantly decreased during re-infection to 26.6% in RI 1w and 13.3% in RI 4w. This result suggested that the mice were resistant to re-infection. In the liver, Kupffer cells were augmented 70-fold in PI 1w mice (P<0.001). Kupffer cells expressed Th2-related cytokines (IL-10 and IL-13) during primary infection. In addition, serum levels of C. sinensis-specific IgG1 and IgG2a strongly increased in RI 1w mice. Secretion of C. sinensis-specific IgE reached a plateau at 4weeks after primary infection, and remained elevated in all infected groups. In conclusion, during infection with C. sinensis, Kupffer cells likely act as antigen-presenting cells, stimulating the Th2 cytokine production system.

Correlations Between the Incidence of National Notifiable Infectious Diseases and Public Open Data, Including Meteorological Factors and Medical Facility Resources.

OBJECTIVES: This study was performed to investigate the relationship between the incidence of national notifiable infectious diseases (NNIDs) and meteorological factors, air pollution levels, and hospital resources in Korea. METHODS: We collected and stored 660,000 pieces of publicly available data associated with infectious diseases from public data portals and the Diseases Web Statistics System of Korea. We analyzed correlations between the monthly incidence of these diseases and monthly average temperatures and monthly average relative humidity, as well as vaccination rates, number of hospitals, and number of hospital beds by district in Seoul. RESULTS: Of the 34 NNIDs, malaria showed the most significant correlation with temperature (r=0.949, p<0.01) and concentration of nitrogen dioxide (r=-0.884, p<0.01). We also found a strong correlation between the incidence of NNIDs and the number of hospital beds in 25 districts in Seoul (r=0.606, p<0.01). In particular, Geumcheon-gu was found to have the lowest incidence rate of NNIDs and the highest number of hospital beds per patient. CONCLUSIONS: In this study, we conducted a correlational analysis of public data from Korean government portals that can be used as parameters to forecast the spread of outbreaks.

Regulation of anti-inflammatory cytokines IL-10 and TGF-ß in mouse dendritic cells through treatment with Clonorchis sinensis crude antigen.

Dendritic cells (DCs), which are regarded as the most potent antigen-presenting cells, are involved in innate and adaptive immunity. Upon uptake of pathogens, DCs express cell surface markers and secrete cytokines. In this study, we analyzed production of cytokines and found that interleukin (IL)-10 and transforming growth factor (TGF)-ß production significantly increased in bone marrow-derived DCs and a mouse DC line, DC2.4, after treatment with crude antigen (CA) from liver fluke, Clonorchis sinensis. However, expression patterns of several activation molecules did not change. In addition, following treatment of DC2.4 cells with antigen from the lung fluke, Paragonimus westermani, production of IL-10 and TGF-ß significantly increased compared with groups treated with other parasite antigens, Spirometra erinacei plerocercoid CA and Echinococcus granulosus hydatid cystic fluid. We also found that treatment of DC2.4 cells with C. sinensis CA resulted in rapid and significant phosphorylation of extracellular signal-regulated kinase 1/2, a mitogen-activated protein kinase. Following treatment of DC2.4 cells with C. sinensis CA, treatment with an inhibitor specific to an extracellular signal-regulated kinase inhibited production of IL-10 and TGF-ß. Our results suggest that CA from C. sinensis has a role in the anti-inflammatory function of DC cells by inducing IL-10 and TGF-ß through activation of extracellular signal-regulated kinase 1/2.

In vitro maintenance of Clonorchis sinensis adult worms.

Clonorchis sinensis is a biological carcinogen inducing human cholangiocarcinoma, and clonorchiasis is one of the important endemic infectious diseases in East Asia. The present study investigated survival longevity of C. sinensis adult worms in various in vitro conditions to find the best way of keeping the worms longer. The worms were maintained in 0.85% NaCl, 1×PBS, 1×Locke's solution, RPMI-1640, DMEM, and IMDM media, and in 1×Locke's solution with different supplements. All of the worms died within 3 and 7 days in 0.85% NaCl and 1×PBS, respectively, but survived up to 57 days in 1×Locke's solution. The worms lived for 106 days in DMEM, and 114 days in both RPMI-1640 and IMDM media. The survival rate in RPMI-1640 medium was the highest (50%) compared to that in DMEM (20±10%) and in IMDM (33.3±25.2%) after 3 months. The 1×Locke's solution with 0.005% bovine bile supplement showed increased duration of maximum survival from 42 days to 70 days. Higher concentration of bile supplements than 0.005% or addition of glucose were disadvantageous for the worm survival. The worms died rapidly in solutions containing L-aspartic acid, L-glutamic acid, and adenine compared to L-arginine, L-serine, and L-tryptophan. In conclusion, the 1×Locke's solution best supports the worms alive among inorganic solutions for 57 days, and the RPMI-1640 medium maintains living C. sinensis adults better and longer up to 114 days in vitro than other media.

Predominance of IL-10 and TGF-ß production from the mouse macrophage cell line, RAW264.7, in response to crude antigens from Clonorchis sinensis.

Parasitic helminths are well-known to have the ability to modulate host immune responses. In this study, we investigated the fundamental immunoregulatory mechanism of the liver fluke Clonorchis sinensis (C. sinensis) using a murine macrophage RAW 264.7 (RAW) cell line and mouse bone marrow derived macrophages (BMDMs). We found that C. sinensis crude antigen (CA) is able to differentiate macrophage RAW cells into dendritic-like cells that can be detected by morphological observations. In addition, CA induces prominent secretion of anti-inflammatory cytokines such as IL-10 and TGF-ß; however, we did not observe changes in cell surface markers that are involved in antigen recognition, antigen presentation, and T cell activation. Additionally, CA treatment induced ERK and JNK phosphorylation, and unexpectedly, elevated levels of IL-10 and TGF-ß were inhibited by the addition of an ERK-specific inhibitor. Taken together, these data demonstrate that CA from C. sinensis may modulate host immune responses by upregulating anti-inflammatory cytokines via the regulation of ERK.

Crude extracts of Caenorhabditis elegans suppress airway inflammation in a murine model of allergic asthma.

Epidemiological studies suggest an inverse relationship between helminth infections and allergic disease, and several helminth-derived products have been shown to suppress allergic responses in animals. This study was undertaken to evaluate the effect of a crude extract of Caenorhabditis elegans on allergic airway inflammation in a murine model of asthma. Allergic airway inflammation was induced in BALB/c mice by sensitization with ovalbumin. The effect of the C. elegans crude extract on the development of asthma and on established asthma was evaluated by analyzing airway hyperresponsiveness, serum antibody titers, lung histology and cell counts and cytokine levels in the bronchoalveolar lavage fluid. The role of IFN-γ in the suppression of asthma by the C. elegans crude extract was investigated in IFN-γ knockout and wild-type mice. When mice were sensitized with ovalbumin together with the crude extract of C. elegans, cellular infiltration into the lung was dramatically reduced in comparison with the ovalbumin-treated group. Treatment of mice with the C. elegans crude extract significantly decreased methacholine-induced airway hyperresponsiveness and the total cell counts and levels of IL-4, IL-5 and IL-13 in the bronchoalveolar lavage fluid but increased the levels of IFN-γ and IL-12. Sensitization with the C. elegans crude extract significantly diminished the IgE and IgG1 responses but provoked elevated IgG2a levels. However, the suppressive effect of the C. elegans crude extract was abolished in IFN-γ knockout mice, and the Th2 responses in these mice were as strong as those in wild-type mice sensitized with ovalbumin. The crude extract of C. elegans also suppressed the airway inflammation associated with established asthma. This study provides new insights into immune modulation by the C. elegans crude extract, which suppressed airway inflammation in mice not only during the development of asthma but also after its establishment by skewing allergen-induced Th2 responses to Th1 responses.

Strain variation in the susceptibility and immune response to Clonorchis sinensis infection in mice.

Mice have shown various susceptibility to infection by Clonorchis sinensis. To compare the intra-specific variation in the host-parasite relationship of C. sinensis, 6 strains of mice (ICR, BALB/c, C57BL/6, DDY, CBA/N, and C3H/HeN) with 3 different haplotypes were evaluated on their susceptibility. The worm recovery rate and immunological responses were observed after 4 and 8 weeks of infection with 30 metacercariae. The highest worm recovery rate was observed as 20.7% in the C3H/HeN strain after 4 weeks of infection along with histopathological changes. The rate was 10.0% in C57BL/6 mice after 8 weeks. ICR, BALB/c, and CBA/N showed elevated levels of IgE at both time points when compared to the rest of the strains. The serum IgG1 and IgG2a levels were elevated in most of the strains; however, the C57BL/6 strain showed a lower level of IgG2a that indicated the IgG1 predominance over IgG2a. The production of IL-4 after concanavalin-A stimulation of splenocytes slightly increased among the mouse strains except C3H/HeN after 4 or 8 weeks of infection, but each strain produced high levels of IFN-γ after 8 weeks, which implied mixed Th1/Th2 responses. ICR, DDY, CBA/N, and C3H/HeN strains showed a significantly increased level of IL-10 after 8 weeks as compared to C57BL/6. All of the strains showed an increased level of IL-13 and suggested fibrotic changes in the mice. In conclusion, mice are insusceptible to infection with C. sinensis; however, the C57BL/6, BALB/c and ICR strains are relatively susceptible after 8 weeks of infection among the six strains. Worm expulsion may be one of the causes of low susceptibility of C3H/HeN mice strain at the 8th week. Elevated IgE, IFN-γ, and IL-13 of infected mice suggest both Th1 and Th2 responses that may be related to the low host susceptibility.

Coproantigen capture ELISA for detection of Clonorchis sinensis infection in experimentally infected rats.

The present study investigated the diagnostic value of an ELISA for the detection of Clonorchis sinensis antigen in the feces of experimentally infected rats. A mouse polyclonal IgG antibody against adult C. sinensis crude antigen (CsAg) was used to capture the C. sinensis coproantigen. The detection limit for pure CsAg was 20 ng/ml in sample buffer and 40 ng/ml in uninfected fecal extract. The test was evaluated using a follow-up of five groups of rats experimentally infected with 100, 50, 10, 5 and 1 metacercariae of C. sinensis and an uninfected control group. Coproantigen was detected in all infected groups of rats from 2 weeks of infection, whereas fecal eggs were not observed until 3 weeks of infection. As the infection period progressed, the fecal CsAg concentration increased in all groups of infected rats, even those infected with a single metacercaria. The fecal CsAg concentration was correlated positively with fecal egg counts and worm burden. This coproantigen capture ELISA is highly sensitive for the detection of CsAg in rat feces, and with further development, should be useful for mass screening of human subjects in clonorchiasis-endemic areas.

Cyst formation, increased anti-inflammatory cytokines and expression of chemokines support for Clonorchis sinensis infection in FVB mice.

To verify the hypothesis that different pathology of Clonorchis sinensis infection by mouse strains is determined by different responses of cytokines and chemokines, we compared those responses of FVB with those of BALB/c mice. All of FVB mice infected with 30 metacercariae of C. sinensis showed cystic dilatation in the liver, whereas infected BALB/c mice did not. Mature worms were recovered from 19 of 20 liver sections of FVB mice while only one of 20 sections of BALB/c mice revealed a mature worm. In both strains the proportion of CD4(+) T cells was lower in C. sinensis-infected than in the uninfected group. However, the proportion of CD8(+) T cells was elevated in C. sinensis-infected from both strains compared to uninfected mice. The Th2-associated anti-inflammatory cytokines such as IL-4, IL-5 and IL-13, IL-10 and TGF-ß, were significantly more produced by the lymphocytes of FVB than by those of BALB/c mice. Especially, the 2 anti-inflammatory cytokines, IL-10 and TGF-ß, were presumably related with susceptibility and the development of worms in the liver. C. sinensis infected FVB mice also produced more chemokines such as RANTES and MIP-1α in the liver lymphocytes than BALB/c mice. In conclusion, the FVB mice provide the favorable niche for C. sinensis by cyst formation in the bile duct, increased production of Th2-associated anti-inflammatory cytokines and upregulation of chemokines.

Production and deformation of Clonorchis sinensis eggs during in vitro maintenance.

Clonorchis sinensis is a carcinogenic human liver fluke. The present study monitored eggs produced by long-term maintained adult worms of C. sinensis to confirm their egg productivity in vitro. The worms from infected rabbits were incubated in vitro in 1× Locke's solution and broth media (RPMI-1640, DMEM and IMDM). Numbers of expelled eggs were counted sequentially and their morphological changes were monitored by microscopy after 1, 30, 60, and 90 days of cultivation. On the 1-3 days of cultivation, the eggs counted maximum 4,756±202 eggs/worm/day in IMDM medium. The number of eggs gradually decreased less than 1,000 at 7-14 days and below 100 at 21days but continued to pass eggs after 56 days in all media. Length of the eggs were reduced about 1 µm at 30 days, and the length/width ratio was maintained around 1.8 at 30 days but decreased to 1.7 at 60 days and 1.5 at 90 days. Faust-Meleney index (FMI) decreased as the cultivation duration increased and lowest FMI (5662.9±974.7) observed in IMDM media at day 90 (P = 0.001). Microscopic findings of the eggs recognized the miracidium in most of eggs at 60 days but not in those at 90 days. Instead, the eggs contained dark granules or vacuoles in the deformed shell at 90 days. Scanning electron microscopy revealed partial loss of wrinkles on the deformed egg surface and prominent abopercular knob. Eggs viability decreased as the cultivation progressed and showed significant positive correlation with FMI and length/width ratio. In conclusion, the cultivated worms pass only the eggs which are preformed in their uterus before cultivation. One gravid C. sinensis contains about 37,000 eggs in its uterus and produces about 4,000 eggs every day. The deformed eggs with FMI less than 7,000 and length/width ratio lower than 1.7 are non-viable.

Correlation between discharged worms and fecal egg counts in human clonorchiasis.

BACKGROUND: Stool examination by counting eggs per gram of feces (EPGs) is the best method to estimate worm burden of Clonorchis sinensis in infected humans. The present study investigated a correlation between EPGs and worm burden in human clonorchiasis. METHODS AND FINDINGS: A total of 60 residents, 50 egg-positive and 10 egg-negative, in Sancheong-gun, Korea, participated in this worm collection trial in 2006-2009. They were diagnosed by egg positivity in feces using the Kato-Katz method. After administration of praziquantel, they were purged with cathartics on the next day, and then discharged adult worms were collected from their feces. Their EPGs ranged from 0 to 65,544. Adult worms of C. sinensis were collected from 17 egg-positive cases, and the number of worms ranged from 1 to 114 in each individual. A positive correlation between EPGs and numbers of worms was demonstrated (r = 0.681, P<0.001). Worm recovery rates were 9.7% in cases of EPGs 1-1,000 and 73.7% in those of EPGs over 1,000. No worms were detected from egg-negative subjects. Maximum egg count per worm per day was roughly estimated 3,770 in a subject with EPGs 2,664 and 106 collected worms. CONCLUSIONS: The numbers of the worms are significantly correlated with the egg counts in human clonorchiasis. It is estimated that at least 110 worms are infected in a human body with EPGs around 3,000, and egg productivity of a worm per day is around 4,000.

Early detection and estimation of infection burden by real-time PCR in rats experimentally infected with Clonorchis sinensis.

A real-time PCR assay targeting the cytochrome c oxidase gene of Clonorchis sinensis was developed and its diagnostic value was investigated in experimentally infected rats. The PCR assay amplified as little as 0.1 pg of C. sinensis genomic DNA and a single egg from experimentally spiked negative feces. The assay could detect C. sinensis DNA in feces 2 weeks post-infection (PI), whereas the Kato-Katz method and formalin-ether concentration techniques could detect the eggs in the feces from 3 weeks PI. Inverse correlations between eggs per gram of feces (EPG) and Ct values were observed 4, 6, and 8 weeks PI. Worm burden was positively correlated with EPG but negatively correlated with Ct values in different groups at 8 weeks PI. Fecal real-time PCR provides a potential tool for the diagnosis of clonorchiosis before eggs can be detected by conventional methods, and may be used to estimate the worm burden in the host.

Differential protein expression in Spirometra erinacei according to its development in its final host.

This study was undertaken to identify genes involved in the growth and development of Spirometra erinacei larvae, an intestinal tapeworm of cats and dogs, within the final host. The differential protein expression at three different stages of S. erinacei, the plerocercoid larvae, 8-day-old juveniles, and adults, was compared using two-dimensional electrophoresis. Specifically or highly expressed proteins in juvenile worms were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (MS)/MS. The proteome map of larvae showed fewer protein spots than juveniles or adults, whereas juveniles or adults revealed a similar protein expression profile. Eight juvenile-specific and five upregulated proteins of juveniles were identified and matched to proteins of known biological functions. These were grouped into several categories of functionally related proteins: DNA/RNA metabolism, cell trafficking, cytoskeleton, protein processing and degradation, energy metabolism, and oxidative stress. Our results give an overview of the growth and development mechanisms of cestodes within the final host and extend our understanding of parasite biology in the host-parasite relationship.

Serodiagnostic applicability of recombinant antigens of Clonorchis sinensis expressed by wheat germ cell-free protein synthesis system.

We evaluated the diagnostic applicability of recombinant proteins from Clonorchis sinensis, the human liver fluke. Four recombinant proteins, 7-kDa protein (Cs7P), 28-kDa cysteine protease (Cs28CP), and 26- and 28-kDa glutathione s-transferases (Cs26GST and Cs28GST), were expressed by wheat germ cell-free protein synthesis system. In ELISA, crude antigen showed the highest sensitivity (92.7%). However, sensitivities of r7P (47.3%), r28CP (30.9%), r26GST (21.8%), and r28GST (14.5%) were dramatically lower. The overall specificities of the crude antigen, r7P, r28CP, r26GST, and r28GST, were 100%, 94.5%, 96.7%, 94.5%, and 98.9%, respectively. Taken together, r7P and r28CP showed moderate sensitivities and high specificities, whereas r26GST and r28GST revealed low sensitivities and high specificities. We demonstrated that recombinant antigens, when used as a single antigen for ELISA, are not sensitive enough to diagnose clonorchiasis. Cocktail or chimeric antigens may be useful to increase the sensitivity of each antigen and may improve the serodiagnosis of clonorchiasis.

Resistance of cholangiocarcinoma cells to parthenolide-induced apoptosis by the excretory-secretory products of Clonorchis sinensis.

Infection by Clonorchis sinensis, the Chinese or oriental liver fluke, is a significant risk factor for the development of cholangiocarcinoma, a human epithelial carcinoma of the intrahepatic bile duct. Parthenolide is a sesquiterpene lactone that has strong anticancer properties and is also known to induce apoptosis in cholangiocarcinoma cells. Many investigators have reported that excretory-secretory (ES) products of C. sinensis as well as Opisthorchis viverrini promote the development of cholangiocarcinomas. However, the intrinsic mechanism is not clearly understood. Therefore, we investigated the biological roles of the ES products in a cholangiocarcinoma cell line, HuCCT1. The ES products of C. sinensis increased proliferation of HuCCT1 cells and augmented the expression of cyclooxygenase (COX)-2. To determine whether cells treated with ES products would respond differently to parthenolide, HuCCT1 cells were treated with parthenolide alone or parthenolide after pretreatment with ES products. Cells pretreated with ES products were resistant to parthenolide-induced apoptosis. Because parthenolide has been reported to be a COX-2 inhibitor, we hypothesize that COX-2 might be a key factor that promotes resistance of cholangiocarcinoma cancer cells to parthenolide-induced apoptosis. These results suggest that chemotherapy treatment regimens in cholangiocarcinoma patients with C. sinensis infection should be modulated to account for ES products excreted by the liver fluke.

Effects of excretory/secretory products from Clonorchis sinensis and the carcinogen dimethylnitrosamine on the proliferation and cell cycle modulation of human epithelial HEK293T cells.

Clonorchis sinensis is one of the most prevalent parasitic helminths in Korea. Although cholangiocarcinoma can be induced by C. sinensis infection, the underlying mechanism is not clearly understood. To assess the role of C. sinensis infection in carcinogenesis, an in vitro system was established using the human epithelial cell line HEK293T. In cells exposed to the excretory/secretory products (ESP) of C. sinensis and the carcinogen dimethylnitrosamine (DMN), cellular proliferation and the proportion of cells in the G2/M phase increased. Moreover, the expression of the cell cycle proteins E2F1, p-pRb, and cyclin B was dramatically increased when ESP and DMN were added together. Similarly, the transcription factor E2F1 showed its highest level of activity when ESP and DMN were added simultaneously. These findings indicate that DMN and ESP synergistically affect the regulation of cell cycle-related proteins. Our results suggest that exposure to C. sinensis and a small amount of a carcinogen such as DMN can promote carcinogenesis in the bile duct epithelium via uncontrolled cellular proliferation and the upregulation of cell cycle-related proteins.

Infection status of freshwater fish with metacercariae of Clonorchis sinensis in Korea.

This study investigated freshwater fish for their current infection status with metacercariae of Clonorchis sinensis in Korea. Twenty-one species of freshwater fish (n = 677) were collected from 34 regions nationwidely from February 2007 to June 2008. They were individually examined by digestion technique. Eight species of freshwater fish from 17 different regions were recognized positive for the metacercariae of C. sinensis. The positive rates (range of metacercariae number per fish) of fish by the species were as follows: 48% (1-1,142) in Pseudorasbora parva, 60% (1-412) in Pungtungia herzi, 15.7% (1-23) in Pseudogobio esocinus, 29% (1-7) in Acheilognathus intermedia, 21% (1-4) in Odontobutis interrupta, 33% (1-6) in Zacco temmincki, 3.6% (1-4) in Zacco platypus, and 26.3% (1) in Hemibarbus labeo. The two species, P. parva and P. herzi, are able to be the index fish for estimation of C. sinensis transmission in a certain locality. Still several species of freshwater fish are briskly transmitting C. sinensis infection in many riverside areas of southern Korea.

Proliferative effects of excretory/secretory products from Clonorchis sinensis on the human epithelial cell line HEK293 via regulation of the transcription factor E2F1.

Clonorchis sinensis is one of the most prevalent parasitic helminths of humans in East Asia. Although several complications in bile duct epithelial cells are caused by C. sinensis infection, the mechanism is not clearly understood. To clarify the effects of C. sinensis excretory-secretory products (ES products) on bile duct epithelial cells, we investigated their effects on the human embryonic kidney epithelial cell line HEK293 in vitro. Our results show that ES products alter the proportion of cells in each stage of the cell cycle and induce HEK293 cell proliferation. Among cell cycle-related proteins, the expression of cyclin E increased markedly after treatment with ES products, indicating that the G1/S transition occurred. In addition, the expression of the transcription factor E2F1 was up-regulated by the addition of ES products. Small interfering RNA (siRNA) was used to demonstrate that the transcription factor E2F1 is a key factor in the control of cell proliferation in HEK293 cells. The present results demonstrate that ES products from C. sinensis stimulate cell proliferation by inducing E2F1 expression. We suggest that the ES products released from C. sinensis during infection may play an important role in the development of cholangiocarcinoma via the overgrowth of the bile duct epithelium.

Tissue parasitic helminthiases are prevalent at Cheongjin, North Korea.

We investigated a small-scale serological survey to screen tissue-parasitic helminthiases of North Koreans as one of research programs for re-unification of Korea. Soil-transmitted helminthiases were found highly prevalent among North Korean residents at the border with China. ELISA using 4 tissue-parasitic helminth antigens was applied to 137 residents living in Cheongjin-shi, Hamgyeongbuk-do, North Korea and 133 female refugees in South Korea in 2004-2005. Among a total of 270 samples, 31 (11.5%), 25 (9.3%), and 11 (4.1%) were positive for specific IgG antibodies to antigens of Clonorchis sinensis, Taenia solium metacestode, and sparganum, respectively. The overall positive rate was 21.5%; 38.2% in males and 15.8% in females. The present finding suggests that tissue parasites, such as C. sinensis, T. solium metacestode and sparganum are highly prevalent in some limited areas of North Korea. These foodborne tissue-parasitic helminthiases should be considered for future control measures of parasitic diseases in North Korea.