A cross-sectional study on intestinal parasitic infections in rural communities, northeast Thailand.

Despite the existence of effective anthelmintics, parasitic infections remain a major public health problem in Southeast Asia, including Thailand. In rural communities, continuing infection is often reinforced by dietary habits that have a strong cultural basis and by poor personal hygiene and sanitation. This study presents a survey of the prevalence of intestinal parasitic infections among the people in rural Thailand. The community-based cross-sectional study was conducted in villages in Khon Kaen Province, northeastern Thailand, from March to August 2013. A total of 253 stool samples from 102 males and 140 females, aged 2-80 years, were prepared using formalin-ethyl acetate concentration methods and examined using light microscopy. Ninety-four individuals (37.2%) were infected with 1 or more parasite species. Presence of parasitic infection was significantly correlated with gender (P=0.001); nearly half of males in this survey (49.0%) were infected. Older people had a higher prevalence than younger members of the population. The most common parasite found was Opisthorchis viverrini (26.9%), followed by Strongyloides stercoralis (9.5%), Taenia spp. (1.6%), echinostomes (0.4%), and hookworms (0.4%). The prevalence of intestinal protozoa was Blastocystis hominis 1.6%, Entamoeba histolytica 0.8%, Entamoeba coli 0.8%, Balantidium coli 0.4%, Iodamoeba bütschlii 0.4%, and Sarcocystis hominis 0.4%. Co-infections of various helminths and protozoa were present in 15.9% of the people. The present results show that the prevalence of parasitic infections in this region is still high. Proactive education about dietary habits, personal hygiene, and sanitation should be provided to the people in this community to reduce the prevalence of intestinal parasite infections. Moreover, development of policies and programs to control parasites is needed.

Involvement of c-Ski oncoprotein in carcinogenesis of cholangiocacinoma induced by Opisthorchis viverrini and N-nitrosodimethylamine.

Opisthorchiasis is the major public health problem in the endemic areas of Thailand and Laos because Opisthorchis viverrini infection causes serious hepatobiliary diseases including CCA. The molecular mechanism of the CCA carcinogenesis induced by the infection remains obscure. To reveal the potential genes and signaling pathways to involve in the carcinogenesis, the present study investigated the expression of c-Ski, an oncogene, and two TGF-ß signaling pathway relative genes, TGF-ß and Smad4, during the development of CCA induced by O. viverrini infection in hamster model, and in human opisthorchiasis associated CCA. The results showed that the expression of c-Ski gene was greatly up-regulated during the carcinogenesis of CCA in hamster model. The overexpression of c-Ski was confirmed by immunohistological staining result which showed the increased expression of c-Ski protein in cytoplasm of the epithelial lining of hepatic bile ducts. Moreover, the immunohistological staining of the specimens of human opisthorchiasis associated CCA revealed the up-regulated expression of c-Ski and Smad4 proteins in the cytoplasm of the epithelial lining of hepatic bile ducts and stomal fibrosis respectively. The expression of TGF-ß and Smad4 were up-regulated, which expression kinetics was time-dependent of CCA development. These results suggest that c-Ski is likely involved in the carcinogenesis of CCA induced by O. viverrini infection through regulating TGF-ß signaling pathway.

Effect of fingerroot on reducing inflammatory cells in hamster infected with Opisthorchis viverrini and N-nitrosodimethylamine administration.

The active compound in fingerroot is effective in the treatment of many inflammatory diseases. The aim of our present study was to evaluate the efficacy of fingerroot on reducing histopathological changes in hamsters that were infected with the liver fluke Opisthorchis viverrini or were administered N-nitrosodimethylamine (NDMA), and then treated with fingerroot. Light microscopic observation and liver function tests for alanine transaminase (ALT), alkaline phosphatase (ALP), and direct bilirubin were investigated. The results of histopathological changes show that fingerroot has anti-inflammatory properties--in the case of N-nitrosodimethylamine administration on day 30--by reducing the aggregation of inflammatory cells surrounding the hepatic bile ducts, which correlates with a decreased serum ALT level. The decrease of direct bilirubin levels in hamsters treated with fingerroot suggests that fingerroot may enhance biliary contraction. The present study found that fingerroot clearly reduces the inflammatory cells in hamsters that were administered NDMA, but not in the case of O. viverrini infection. This finding suggests that fingerroot has anti-inflammatory property, but not in the case of hamster opisthorchiasis.

Curcumin reduces oxidative and nitrative DNA damage through balancing of oxidant-antioxidant status in hamsters infected with Opisthorchis viverrini.

Opisthorchis viverrini (OV) infection is endemic in northeastern Thailand. We have previously reported that OV infection induces oxidative and nitrative DNA damage via chronic inflammation, which contributes to the disease and cholangiocarcinogenesis. Here, we examined the effect of curcumin, an antioxidant, on pathogenesis in OV-infected hamsters. DNA lesions were detected by double immunofluorescence and the hepatic expression of oxidant-generating and antioxidant genes was assessed by quantitative RT-PCR analysis. Dietary 1.0% curcumin significantly decreased OV-induced accumulation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an oxidative DNA lesion, and 8-nitroguanine, a nitrative DNA lesion, in the nucleus of bile duct epithelial and inflammatory cells. Expression of oxidant-generating genes (inducible nitric oxide synthase; iNOS, its nuclear transcriptional factor, NF-kappaB, and cyclooxygenase-2), and plasma levels of nitrate, malondialdehyde, and alanine aminotransferase, were also decreased in curcumin-treated group. In contrast, curcumin increased the mRNA expression of antioxidant enzymes (Mn-superoxide dismutase and catalase), and ferric-reducing anti-oxidant power in the plasma. In conclusion, curcumin reduced oxidative and nitrative DNA damage by suppression of oxidant-generating genes and enhancement of antioxidant genes, leading to inhibition of oxidative and nitrative stress. Therefore, curcumin may be used as a chemopreventive agent to reduce the severity of OV-associated diseases and the risk of cholangiocarcinoma (CCA).

Turmeric reduces inflammatory cells in hamster opisthorchiasis.

The curcumin compound from turmeric is effective in the treatment of many inflammatory diseases. The aim of our present study was to evaluate the efficacy of turmeric on reducing the histopathological changes of hamster opisthorchiasis. Hamsters were infected with Opisthorchis viverrini and then administered turmeric. Using light microscopic observation, liver function tests for alanine transaminase (ALT), alkaline phosphatase, and direct bilirubin were investigated. The resulting histopathological changes show that turmeric has anti-inflammatory properties--during both N-nitrosodimethylamine administration and O. viverrini infection--by reducing the aggregation of inflammatory cells surrounding the hepatic bile ducts, which correlates with a decreased serum ALT level. The decrease in direct bilirubin levels in the hamsters treated with turmeric suggests that turmeric may enhance biliary contraction. The present study found that turmeric clearly reduces the inflammatory cells in hamster opisthorchiasis at an early stage. This finding may be connected with a reduction in the risk factors of cholangiocarcinoma development.

Alterations of gene expression of RB pathway in Opisthorchis viverrini infection-induced cholangiocarcinoma.

Opisthorchiasis has the significant relationship with the high prevalence of cholangiocarcinoma (CCA; a bile duct cancer) in the endemic areas in Southeast Asia. To reveal the molecular mechanism of the tumorigenesis induced by Opisthorchis viverrini infection, the present study investigated the kinetic expression of RB pathway genes, including RB1, p16(INK4), cyclin D1, and CDK4, during the development of opisthorchiasis-associated CCA in hamster model. The results of quantitative real-time polymerase chain reaction indicated that the expressions of RB1 and p16(INK4) were down-regulated during the development of CCA induced by infection plus N-nitrosodimethylamine treatment in a time-dependent manner. On the other hand, the expressions of cyclin D1 and CDK4 were up-regulated. The expression kinetics was corresponding to the pathological progression of the opisthorchiasis-associated CCA, revealed by histopathological observation. Moreover, the analysis of the expression of these genes in human opisthorchiasis-associated CCA cases showed the decreased expression of RB1 and p16(INK4) in 50% and 82.7% cases and overexpression of cyclin D1 and CDK4 in half cases, respectively. The results suggested that RB pathway is likely involved in the tumorigenesis of opisthorchiasis-induced CCA and proposed the potential application of some of these genes as biomarkers in predispose and molecular therapy of the parasite-associated cancer.

Animal models for Opisthorchis viverrini infection.

We investigated the utility of various animal models for the study of opisthorchiasis in humans and its common sequel of cholangiocarcinoma (CCA). Rats, mice, gerbils, and hamsters were infected with Opisthorchis viverrini metacercariae. Worms from the infected animal hosts were recovered from livers and counts made of eggs per gram of feces. Worms were observed in and recovered from hamsters and gerbils but not rats and mice. The recovered worms from the infected gerbils were larger and more physiologically developed than those from the infected hamsters. The results suggest that gerbils are more susceptible to infection by Opisthorchis viverrini and thus more suitable for modeling opisthorchiasis and its connection to CCA.

Effect of curcumin on pathogenesis of hamster-opisthorchiasis through apoptosis-related gene expression.

The present study investigated the effect of curcumin, a phenolic compound with yellow color from Curcuma longa L., on the expression of the apoptosis-related genes [BAX (Bcl-2 associated protein X), PKB, p53, MDM2 (mouse double minute 2), caspase 9, c-Ski, smad1 and smad4] in hamster opisthorchiasis. On Opisthorchis viverrini infection treated with dietary curcumin apoptosis-related gene expression profiles were similar to O. viverrini-infected group, but the expression levels seemed lower. Light microscopic observation revealed that aggregation of inflammatory cells surrounding the hepatic bile ducts in the groups infected with O. viverrini and treated with dietary curcumin was lower than in infected group. The intensity of the response is correlated with expression of the genes studied. The results suggest that curcumin reduces pathogenesis in hamster-opisthorchiasis by controlling apoptosis-related gene expression.

Oxidative and nitrative stress in Opisthorchis viverrini-infected hamsters: an indirect effect after praziquantel treatment.

Praziquantel causes adverse effects after short-term treatment. To examine the mechanism of these effects, we studied the distribution of Opisthorchis viverrini antigens and the expression of inducible nitric oxide synthase (iNOS), nuclear factor-kappaB (NF-kappaB), and antioxidant enzymes in O. viverrini-infected hamsters during short-term praziquantel treatment. Praziquantel-induced dispersion of parasite antigens produced a recruitment of inflammatory cells. NF-kappaB and iNOS mRNA expression was significantly elevated and associated with their immunoreactivity in the bile duct epithelium and inflammatory cells. Plasma nitrate, end products of nitric oxide, and malondialdehyde level increased significantly. Expression of mRNA for antioxidant enzymes (superoxide dismutases, catalase, and glutathione peroxidase) also increased significantly, which suggests host defense against oxidative stress. These results suggest that short-term praziquantel treatment induces inflammation and resulting oxidative and nitrative stress through O. viverrini antigen release. Data in this study can be used as a basis to understand potential side effects of praziquantel treatment in humans.