OBJECTIVETo investigate the role of excretory/secretory antigens from Clonorchis sinensis (CsESAs) in hepatic fibrosis induced by C. sinensis infection in rats and explore the possible mechanism.

METHODSCsESAs was collected from adult C. sinensis cultured in sterile condition for 12 h and injected intraperitoneally in Wistar rats. Masson staining was used to observe the changes in the hepatic collagen fiber after the injection. HE staining and immunofluorescence staining were performed to detect the expression of alpha-smooth muscle actin (alpha-SMA) to examine the proliferation and the activity of hepatic stellate cells. The specific antibody titer of CsESAs was determined using enzyme-linked immunosorbent assay to investigate the role of the antigen-antibody complex in the development of hepatic fibrosis.

RESULTSAfter intraperitoneal injection of CsESAs, obvious hepatic fibrosis and hepatic stellate cell proliferation and activation were observed in the rat livers. The severity of the hepatic fibrosis was associated with the dose of CsESAs injected, whereas the titer of the specific antibody against CsESAs showed no direct relation to the hepatic fibrosis.

CONCLUSIONIntraperitoneal injection of CsESAs can cause hepatic stellate cell activation and hepatic fibrosis in rats, but the antigen-antibody complex does not seem to play the key role in the activation of the hepatic stellate cells.

Actins ; metabolism ; Animals ; Antigens, Helminth ; immunology ; Clonorchiasis ; parasitology ; Clonorchis sinensis ; immunology ; pathogenicity ; Hepatic Stellate Cells ; pathology ; Liver Cirrhosis ; immunology ; parasitology ; Male ; Rats ; Rats, Wistar

This study describes an evaluation of the sonographic, cholangiographic, pathological, and immunological findings, and the protective effect shown by rats reinfected with Clonorchis sinensis. Eight experimental rat groups were, namely, a normal control, a primary infection control, a reinfection I (reinfection 7 week after treatment following 3-week infection), a reinfection II (reinfection 2 week after treatment following 8-week infection), a reinfection III (exploration of the intrahepatic bile ducts 1 week after reinfection 4 week after treatment following 4-week infection), a superinfection, a secondary infection control, and an infection following immunization group. Sonographic and cholangiographic findings showed moderate or marked dilatation of the bile duct confluence in the primary infection control, reinfection II, and secondary infection control groups. Juvenile worms survived in the intrahepatic bile ducts 1 week after reinfection following treatment in the reinfection III group. It was concluded that reinfecting juvenile worms found during the first week following reinfection failed to survive or grow further. Anatomical, pathophysiological, or immunological changes may induce protection from reinfection in rats.
Animals ; Anthelmintics/administration & dosage/therapeutic use ; Antibodies, Helminth/blood ; Antigens, Helminth/administration & dosage/immunology ; Bile Duct Diseases/parasitology/*pathology/ultrasonography ; Bile Ducts, Intrahepatic/parasitology/*pathology/ultrasonography ; Cholangiography ; Clonorchiasis/parasitology/*pathology/ultrasonography ; Clonorchis sinensis/*pathogenicity ; Immunization ; Praziquantel/administration & dosage/therapeutic use ; Rats ; Rats, Sprague-Dawley ; Sound Spectrography ; Support, Non-U.S. Gov't

We investigated the induction of resistance to Clonorchis sinensis infection by prior infection in rat and hamster models. Animals were challenged with C. sinensis metacercariae, then treated with praziquantel and reinfected. Worm recovery rate in reinfected animals was used to estimate resistance to reinfection. The determined resistance rates to reinfection in rats and hamsters were 97.7% and 10.3%, respectively. In rats, cure from the primary infection of C. sinensis increased resistant to reinfection, and the greatert the worm burden and the longer the duration of primary infection, the higher was the resistance rate. For primary infection doses of 10, 40 and 100 metacercariae per rat, the resistance rates were 87.4%, 93.8% and 98.4%, respectively. The resistance rates in rats after 2 or 8-week primary infection were 78.7% and 95.3%, respectively. All worms recovered from reinfected rats were immature. When cured rats were administered with methylprednisolone, resistance to reinfection became impaired. These findings indicate that rats develop a high degree of resistance to reinfection by C. sinensis after cure. The growths and maturations of reinfected worms were also impaired.
Animals ; Anthelmintics/administration & dosage/therapeutic use ; Anti-Inflammatory Agents/administration & dosage ; Clonorchiasis/*immunology/parasitology/*pathology ; Clonorchis sinensis/*pathogenicity ; Disease Models, Animal ; Female ; Hamsters ; Immunocompetence ; Immunosuppression ; Male ; Mesocricetus ; Methylprednisolone/administration & dosage ; Praziquantel/administration & dosage/therapeutic use ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't