| Popis: |
Background: Echinococcosis caused by the larvae of cestodes of the genus Echinococcus is a parasitic zoonosis that poses a serious threat to the health of humans and animals globally. Albendazole is the drug of choice for the treatment of echinococcosis, but it is difficult to meet clinical goals with this chemotherapy due to its low cure rate and the assocaiated side effects after long-time use. Hence, novel anti-parasitic targets and effective treatment alternatives are urgently needed. A previous study showed that verapamil can suppress the growth of Echinococcus granulosus larvae; however, the mechanism of this effect remains unclear. The aim of the present study was to gain insight into the anti-echinococcal effect of verapamil on Echinococcus with a particular focus on the regulatory effect of verapamil on calcium/calmodulin-dependent protein kinase Ⅱ (Ca2+/CaM-CamKⅡ) in infected mice.Methods: The anti-echinococcal effects of verapamil on E. granulosus protoscoleces (PSC) in vitro and E. multilocularis metacestodes in infected mice were assessed. The morphological alterations in Echinococcus spp. induced by verapamil were observed by scanning electron microscopy (SEM), and the changes in calcium content in both the parasite and mouse serum and liver were measured by SEM-energy dispersive spectrometry, inductively coupled plasma mass spectrometry and Alizarin red staining. Additionally, the changes in the protein and mRNA levels of CaM and CamKⅡ in infected mice, and in the mRNA levels of CamKⅡ in E. granulosus PSC were evaluated after treatment with verapamil by immunohistochemistry and/or real-time quantitative polymerase chain reaction.Results: In vitro, E. granulosus PSC could be killed by verapamil at a concentration of 0.5 μg/mL or higher within 8 days. Under these conditions, the ultrastructure of PSC was damaged, and this damage was accompanied obvious calcium loss and downregulation of CamKⅡ mRNA expression. In vivo, the weight and the calcium content of E. multilocularis metacestodes from mice were reduced after treatment with 40 mg/kg verapamil, and an elevation of the calcium content in the sera and livers of infected mice was observed. In addition, downregulation of CaM and CamKⅡ protein and mRNA expression in the livers of mice infected with E. multilocularis metacestodes was found after treatment with verapamil.Conclusions: Verapamil exerted a parasiticidal effect against Echinococcus both in vitro and in vivo through downregulating the expression of Ca2+/CaM-CamKⅡ, which were over-activated by parasitic infection. The results suggested that Ca2+/CaM-CamKⅡ may be a novel drug-target, and verapamil was shown to be a potential anti-echinococcal drug for controlling echinococcosis in the future. |
