Infection with the liver fluke Opisthorchis viverrini (Digenea) (Poirier, 1886) causes bile duct injury and periductal fibrosis by chronic overproduction of inflammatory-mediators and eventually results in cholangiocarcinoma development. While extensive research works have been done on O. viverrini infection-associated changes of bile ducts and periductal fibrosis, little attention was paid on morphological and biochemical changes of the bile canaliculi (BC), the origin of bile flow. We aimed to investigate the morphological and functional alterations of BC in the liver of hamsters infected with O. viverrini at one and three months post-infection. Ultrastructural changes of BC showed dilatation of BC and significant reduction of the density of microvilli as early as at one month post-infection. Immunohistochemistry revealed that CD10, a BC marker, expression was reduced early as one month post-infection. The mRNA expression of the genes encoding molecules related to bile secretion including bile acid uptake transporters (slc10a1 and slco1a1), bile acid dependent (abcb11) and independent (abcc2) bile flow and bile acid biosynthesis (cyp7a1 and cyp27a1) were significantly decreased at one month post-infection in association with the reduction of bile volume. In contrast, the expression of the mRNA of bile acid regulatory genes (fxr and shp-1) was significantly increased. These changes essentially persisted up to three months post-infection. In conclusion, O. viverrini infection induces morphological and functional changes of BC in association with the decrease of bile volume.
We examined the phylogeography and the variation of the mitochondrial DNA (mtDNA) cytochrome c oxidase subunit 1 gene (cox1) of the Chinese liver fluke Clonorchis sinensis (Cobbold, 1875) in two geographic localities in the Russian southern Far East and compared them with those from different geographical regions (China, Korea, Japan and Vietnam). The Russian samples differed from those of the other regions in haplotype frequencies, haplotype and nucleotide diversities, and AT/GC ratios. Only 4 of the 18 haplotypes were common to Russian and Chinese samples, and two haplotypes were common to Russia and other regions. The intraspecific genetic distances ranged from 0 to 1.58% for the entire dataset studied and from 0 to 1.25% among the samples from Russia. Phylogenetic trees revealed no significant genealogical clades of samples corresponding to sampling localities and no strong isolation by distance was estimated with Mantel test. Neutrality test analysis suggested a relatively recent population expansion for C. sinensis, whereas goodness-of-fit tests indicated deviation from the strict model of uniform expansion. Therefore, the sequences of the mtDNA cox1 gene provide useful genetic markers for evaluating intraspecific diversity and generating phylogeographic reconstructions for this fish-borne trematode.
The liver fluke Clonorchis sinensis (Digenea) is a high-risk parasite that causes serious diseases such as cirrhosis, carcinogenic liver damage and clonorchiasis in East Asia. This study was conducted to evaluate the relationship between stress/endocrine hormones and inflammation induced by infection as well as the expression of heat shock proteins (hsp-27, hsp-90), cox-2 and cytokines in the livers of hamsters infected with C. sinensis. The average body weight of infected hamsters decreased up to 25% compared with that of the control group, and bile duct hyperplasia with inflammation, liver fibrosis and hepatic necrosis were observed in C. sinensis-infected livers. The expression of hsp-27, hsp-90, and cox-2 was significantly increased in the livers of C. sinensis-infected hamsters compared with the control group. Moreover, the expression levels of inflammatory cytokines (IL-1β, IL-2, TGF-β2 and IFN-α1) were markedly increased in the livers of the infected group compared with those of the control group. Consistently, plasma IL-3 and IL-6 levels gradually increased during the infection period, and the concentration levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone (FSH), corticosterone, and adrenocorticotropic hormone (ACTH) in C. sinensis-infected hamsters increased over 25%, compared with those of the uninfected normal group. These results demonstrate that C. sinensis infection may increase the expression of hsp27, hsp90 and cox-2 as well as it may cause periductal fibrosis, chronic inflammation and hepatic necrosis in the liver. Furthermore, the results indicate that C. sinensis infection induces not only stress-induced hormone imbalance but also the sustained secretion of inflammatory cytokines through chronic stress/stimuli.