Xenobiotic-Metabolizing Enzymes in Trematodes

Trematode infections occur worldwide causing considerable deterioration of human health and placing a substantial financial burden on the livestock industry. The hundreds of millions of people afflicted with trematode infections rely entirely on only two drugs (praziquantel and triclabendazole) for treatment. An understanding of anthelmintic biotransformation pathways in parasites should clarify factors that can modulate therapeutic potency of anthelmintics currently in use and may lead to the discovery of synergistic compounds for combination treatments. Despite the pronounced epidemiological significance of trematodes, there is still no adequate understanding of the functionality of their metabolic systems, including xenobiotic-metabolizing enzymes. The review is focused on the structure and functional significance of the xenobiotic-metabolizing system in trematodes. Knowledge in this field can solve practical problems related to the search for new targets for antiparasitic therapy based on a focused action on certain elements of the parasite’s metabolic system. Knowledge of the functionality of this system is required to understand the adaptation of the biochemical processes of parasites residing in the host and mechanisms of drug resistance development, as well as to select a promising molecular target for the discovery and development of new anthelmintic drugs

The liver fluke

Opisthorchiasis caused by the liver fluke Opisthorchis felineus is one of the most common helminthic infections in the Russian Federation. The largest area affected by opisthorchiasis felinea occupies almost the entire territory of Western Siberia and extends to northern Kazakhstan and a part of the Ural region. Natural endemic regions of opisthorchiasis also exist in the European part of Russia, and in the regions of Western and Eastern Europe. According to the official statistics of the Russian Federation, up to 40 000 patients with opisthorchiasis are registered annually in the country. Opisthorchiasis felinea affects the hepatobiliary system and causes serious liver disorders, including cancer of the biliary tract. Other parasitoses, opisthorchiasis viverrini and clonorchiasis, are widespread in the Southeast Asia and China. The causative agents of these diseases, liver flukes O. viverrini and Clonorchis sinensis, are officially recognized as Group 1 biological carcinogens and are classified as the main risk factors for cholangiocarcinoma. O. felineus is included in Group 3 of biological carcinogens and is not officially considered carcinogenic to humans. Studies on the carcinogenic potential of this liver fluke and the epidemiology of cholangiocarcinoma in the Russian Federation have started in earnest quite recently. Nevertheless, we have some evidence that infection with O. felineus leads to a precancerous state of the bile duct epithelium. This state, combined with additional risk factors, poses a real risk of cholangiocarcinoma. In our opinion, taking into consideration the accumulated facts, the classification of the carcinogenic potential of O. felineus requires revision. In this review, we focus on the relevant characteristics of the biology and epidemiology of this helminth as well as experimental data on opisthorchiasis felinea; this information might clarify the carcinogenicity of O. felineus to humans

Plastoquinone-Derivative SkQ1 Improved the Biliary Intraepithelial Neoplasia during Liver Fluke Infection

Carcinogenic food-borne liver fluke infections are a serious epidemiological threat worldwide. The major complications of Opisthorchis felineus infection are chronic inflammation and biliary intraepithelial neoplasia. Although evidence has accumulated that increased reactive oxygen species production is observed in liver fluke infection, a direct relationship between the oxidative stress and biliary intraepithelial neoplasia has not been shown. Quinones and SkQ1, a derivative of plastoquinone, have been demonstrated to be cytoprotective in numerous liver injuries due to their potent antioxidant properties. This study is aimed to assess the level of biliary intraepithelial neoplasia in O. felineus-infected hamsters after treatment with mitochondria-targeted SkQ1. SkQ1 significantly reduced the biliary intraepithelial neoplasia, which was accompanied by a decrease in lipid and DNA oxidation byproducts, mRNA expression and level of proteins associated with inflammation (TNF-α, CD68) and fibrogenesis (CK7, αSMA), and was also associated with an activation of the Keap1-Nrf2 pathway. Thus, a direct relationship was found between oxidative stress and the severity of biliary intraepithelial neoplasia in O. felineus-infected hamsters. The hepatoprotective effect of plastoquinone-derivative SkQ1 was established; therefore, this compound is a promising agent in complex therapy in the treatment of opisthorchiasis

Specific activation of human interleukin-5 depends on de Novo synthesis of an AP-1 complex

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Trapidil inhibits monocyte CD40 expression by preventing IFN-γ-induced STAT1 S727 phosphorylation

Trapidil is a triazolopyrimidine that has been found to prevent restenosis after vascular injury. Although its precise mode of action is still unclear, several biological effects have been described including inhibition of IFN-γ-induced CD40 expression on monocytes. Herein, we investigated the molecular mechanisms by which Trapidil exerts this inhibitory action. First, we observed that the inhibition of CD40 expression is associated with the suppression of CD40 gene transcription, as demonstrated by a clear decrease of CD40 nuclear RNA (nRNA) levels and unchanged CD40 mRNA half-life. IFN-γ-induced CD40 transcription has been shown to be mediated by STAT1α dimers (p91/p84) which, after nuclear translocation, bind to GAS elements present in the promoter of IFN-γ responsive genes. Electrophoresis mobility shift assay (EMSA) with both STAT1 consensus and CD40 mGAS probes showed that Trapidil did not affect the DNA binding ability of STAT1 dimers. STAT1 dimerization and activation are conferred by upstream phosphorylation of two amino acid residues of the STAT1 protein. The subsequent studies on these two potential STAT1 phosphorylation sites (Tyr701, Ser727) revealed that Trapidil attenuated IFN-γ-induced Ser727 but not Tyr701 phosphorylation. The inhibition of CD40 transcription by Trapidil could at least partially owing to the impaired Ser727 phosphorylation of STAT1, since IFN-γ failed to trigger CD40 expression in U3A S727A cells, a cell line displaying a point mutation at the Ser727 site. Collectively, our results indicate that phosphorylation of STAT1 at the Ser727 site enhances CD40 transcription and that Trapidil might be used as a selective inhibitor that could differentially modulate STAT1 target genes. © 2004 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

GATA-3 Has Dual Regulatory Functions in Human Interleukin-5 Transcription

Interleukin-5 (IL-5) is a T-cell cytokine involved in Type 2 diseases and is commonly described as being coordinately regulated with other Type 2 cytokines, such as IL-4 and IL-13. Considering the unique control of eosinophilia by IL-5, such coordinate regulation would be surprising. In fact, the biological specificity of eosinophilia and its control by IL-5 suggests a unique and independent control of IL-5 regulation. In this report we show the binding of GATA-3 to three sites in the human IL-5 promoter in the human T-cell line PER117. The previously identified -70 site and another site at position - 152 are shown to positively regulate IL-5 transcription. More importantly, the site located at -400 acts as a powerful repressor of IL-5 transcription with mutagenesis of this site allowing a high level expression of IL-5 without the activation of other factors normally required for IL-5 expression. Whereas GATA-3 has been proposed to be involved in the regulation of the IL-4/IL-5/ IL-13 locus, we show here that it has another function in controlling IL-5 transcription that supports the observed unique biological function of this cytokine.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Opisthorchis felineus infection provokes time-dependent accumulation of oxidative hepatobiliary lesions in the injured hamster liver.

Opisthorchiasis caused by food-borne trematode Opisthorchis felineus is a substantial public health problem, with 17 million persons infected worldwide. This chronic disease is associated with hepatobiliary inflammation, cholangiocyte dysplasia, cholangiofibrosis, intraepithelial neoplasia, and even cholangiocarcinoma among chronically infected individuals. To provide first insights into the mechanism by which O. felineus infection causes precancerous liver lesions, we investigated the level of oxidative stress (lipid peroxidation byproducts and 8-hydroxy-2'-deoxyguanosine) as well as the time course profiles of chronic inflammation and fibrogenesis markers in the dynamics of opisthorchiasis from 1 month to 1.5 years postinfection in an experimental model based on golden hamsters Mesocricetus auratus. For the first time, we showed that O. felineus infection provokes time-dependent accumulation of oxidative hepatobiliary lesions in the injured liver of hamsters. In particular, over the course of infection, lipid peroxidation byproducts 4-hydroxynonenal and malondialdehyde were upregulated; these changes in general correlate with the dynamics of hepatic histopathological changes. We detected macrophages with various immunophenotypes and elevated levels of CD68, COX2, and CD163 in the O. felineus-infected animals. Meanwhile, there was direct time-dependent elevation of TNF-α (R = 0.79; p < 0.001) and CD163 protein levels (R = 0.58; p = 0.022). We also provide quantitative data about epithelial hyperplasia marker CK7 and a marker of myofibroblast activation (α smooth muscle actin). Our present data provide first insights into the histopathological mechanism by which O. felineus infection causes liver injuries. These findings support the inclusion of O. felineus in Group 1 of biological carcinogens

Detection of regulatory SNPs in human genome using ChIP-seq ENCODE data.

A vast amount of SNPs derived from genome-wide association studies are represented by non-coding ones, therefore exacerbating the need for effective identification of regulatory SNPs (rSNPs) among them. However, this task remains challenging since the regulatory part of the human genome is annotated much poorly as opposed to coding regions. Here we describe an approach aggregating the whole set of ENCODE ChIP-seq data in order to search for rSNPs, and provide the experimental evidence of its efficiency. Its algorithm is based on the assumption that the enrichment of a genomic region with transcription factor binding loci (ChIP-seq peaks) indicates its regulatory function, and thereby SNPs located in this region are more likely to influence transcription regulation. To ensure that the approach preferably selects functionally meaningful SNPs, we performed enrichment analysis of several human SNP datasets associated with phenotypic manifestations. It was shown that all samples are significantly enriched with SNPs falling into the regions of multiple ChIP-seq peaks as compared with the randomly selected SNPs. For experimental verification, 40 SNPs falling into overlapping regions of at least 7 TF binding loci were selected from OMIM. The effect of SNPs on the binding of the DNA fragments containing them to the nuclear proteins from four human cell lines (HepG2, HeLaS3, HCT-116, and K562) has been tested by EMSA. A radical change in the binding pattern has been observed for 29 SNPs, besides, 6 more SNPs also demonstrated less pronounced changes. Taken together, the results demonstrate the effective way to search for potential rSNPs with the aid of ChIP-seq data provided by ENCODE project