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Parasitic infection by Echinococcus granulosus in humans induces hydatidosis (echinococcosis), which is a zoonotic disease that seriously endangers public health. This study was to determine the status of cell apoptosis in the protoscoleces of E. granulosus, which were isolated from hydatid cysts in livers or lungs of sheep. Those protoscoleces were incubated with drugs (at the concentration of 1 mmol L(-1) H(2)O(2) and 5 mmol L(-1)dexamethasone) for 8 h, the apoptosis were examined by transmission electron microscopy and TUNEL assay, the expression of caspase-1 and caspase-3 were detected by immunohistochemistry and caspase-3 activity was detected by colorimetric assay. Our results have clearly demonstrated the presence of cell apoptosis in protoscoleces in the absence or presence of drug (H(2)O(2), dexamethasone) treatment, but drug-induced apoptosis rate, caspase-1 and caspase-3 expression levels were higher than no-drug induce and caspase-3 activity were significantly increasing. We found H(2)O(2) and dexamethasone can induce the cell apoptosis of protoscoleces. Our results implied the existence of a CED-3 like apoptosis gene in protoscolces and provide a rationale for further exploring the induction of apoptosis as non-surgical treatment method in treating this parasitic disease.

To explore the apoptosis induced by dexamethasone and adenosine triphosphate (ATP) in protoscolex of Echinococcus granulosus.Protoscoleces were cultured in vitro and used for the experiment in 4 groups: dexamethasone (5 mmol/L) group, ATP (1.6 mmol/L) group, dexamethasone (5 mmol/L)+ATP (1.6 mmol/L) group, and RPMI 1640 medium as control group. The morphology of protoscolex was observed by light microscopy. After drug treatment for 8 h, the group with significant morphological changes in protoscolex was selected to observe the ultrastructure of protoscolex by transmission electron microscopy. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay (TUNEL) was employed to observe the apoptosis. Caspase-3 activity was detected with a kit, and DNA fragments were seperated by agarose gel electrophoresis.After induced for 8 h, the protoscoleces shrank in dexamethasone group and dexamethasone+ATP group, the rostellum was invaginated. Compared with the control, the calcareous corpuscles in the protoscolex significantly reduced and blurred in the two groups The morphological changes in protoscolex of dexamethasone+ATP group was more obvious than that of dexamethasone group. Electron microscopy showed that dexamethasone+ATP-treated protoscoleces possessed typical morphological features of apoptosis, including the cell volume reduction with densified cytoplasm, cell membrane blebbing, and nuclear heterochromatin peripheral aggregation below the nuclear membrane. A few apoptotic cells were found in protoscolex of dexamethasone+ATP group by TUNEL, while none in the control. Caspase-3 activity significantly increased 12-fold compared to the control. About 150 bp DNA fragment exhibited the typical DNA ladder formation characteristic for apoptosis in dexamethasone+ATP group.Apoptosis in the protoscolex of E. granulosus may be induced by dexamethasone and ATP in vitro.

To explore the apoptosis induced by hydrogen peroxide (H2O2) in protoscolex of Echinococcus granulosus.Protoscoleces were cultured in vitro, and used for the experiment in 2 groups: RPMI 1640 medium and RPMI 1640 medium added with glutamine. They were then treated with different concentrations of H2O2 to induce apoptosis. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay (TUNEL) was employed to observe the apoptosis. Protein expression of caspase-1, caspase-3 and Fas was detected by SP immunohistochemical technique, stained with DAB restained with hematoxylin. A yellow or brown color nucleus revealed positive apoptosis cells in protoscolex, a brown reaction product in cytoplasm showed positive cells of caspase-1 and caspase-3, and brown cell membrane and cytoplasm revealed Fas product; otherwise it was judged as negative. According to the percentage of positive cells in a protoscolex, the expression level was divided as 4 grades. The percentage of less than 5% was regarded as "-", 5%-25% as "+", 26%-50% as "++", more than 50% as "+++". The experiments were repeated 2 times with controls.In RPMI 1640 group, positive TUNEL was found in the protoscolex induced by 1 mmol/L H2O2 inducing for 12 hours. Induced by 1 mmol/L H2O2 for 4 h, the "+-++" expression rate of caspase-1 and caspase-3 in the protoscoleces was 86.6% and 77.8%, and for 8 h, 86.6% and 80.0% respectively, a significant increase in comparison to the control (P0.05). Induced by 5 mmol/L H2O2 for 4 hours, the "++-+++" expression rate of caspase-1 was 93.0%, and the "+-++" expression rate of caspase-3 was 89.5%; induced for 8 h, the "++-+++" expression rate of caspase-1 decreased to 53.2%, and the "+-++" expression rate of caspase-3 decreased to 48.4% and "-" expression rate increased to 46.8%. Under 5 mmol/L H2O2 for 4 h the expression rate of caspase-3 significantly decreased at 8 h (P0.01). In the group of RPMI 1640 plus glutamine, induced by 5 mmol/L H2O2 for 8 h, the "++ -+++" expression rate of caspase-3 in protoscolex was 100% (P0.01). However, in RPMI 1640 group, induced by 5 mmol/L H2O2 for 8 h, the "++-+++" expression rate of caspase-3 in protoscolex was 32.2% and 46.8% were negative. The Fas product with positive reaction in protoscolex was found in both control and induced groups: in RPMI 1640 group, under 5 mmol/L H2O2 induced for 4 h, "+-++" expression rate was 53.0% and control was 20.0%; and in the group of RPMI 1640 plus glutamine, under 5 mmol/L H2O2 induced for 8 h, "+-++" expression rate was 88.7% and control was 71.4%, increased in both groups after induction (P0.05).Apoptosis in the protoscolex of E. granulosus may be induced by H2O2.