Drug repurposing for the treatment of alveolar echinococcosis: in vitro and in vivo effects of silica nanoparticles modified with dichlorophen.

Alveolar echinococcosis is a neglected parasitic zoonosis caused by the metacestode Echinococcus multilocularis, which grows as a malignant tumour-like infection in the liver of humans. Albendazole (ABZ) is the antiparasitic drug of choice for the treatment of the disease. However, its effectiveness is low, due to its poor absorption from the gastro-intestinal tract. It is also parasitostatic and in some cases produces side-effects. Therefore, an alternative to the treatment of this severe human disease is necessary. In this context, the repositioning of drugs combined with nanotechnology to improve the bioavailability of drugs emerges as a useful, fast and inexpensive tool for the treatment of neglected diseases. The in vitro and in vivo efficacy of dichlorophen (DCP), an antiparasitic agent for intestinal parasites, and silica nanoparticles modified with DCP (NP-DCP) was evaluated against E. multilocularis larval stage. Both formulations showed a time and dose-dependent in vitro effect against protoscoleces. The NP-DCP had a greater in vitro efficacy than the drug alone or ABZ. In vivo studies demonstrated that the NP-DCP (4 mg kg-1) had similar efficacy to ABZ (25 mg kg-1) and greater activity than the free DCP. Therefore, the repurposing of DCP combined with silica nanoparticles could be an alternative for the treatment of echinococcosis.

Albendazole nanocrystals in experimental alveolar echinococcosis: Enhanced chemoprophylactic and clinical efficacy in infected mice.

Human alveolar echinococcosis is caused by the fox tapeworm Echinococcus multilocularis and is usually fatal if left untreated. Medical treatment with albendazole (ABZ) remains an effective option. However, due to its low aqueous solubility, ABZ is poorly and erratically absorbed following oral administration resulting in low drug levels in plasma and liver distribution. Thus, there arises the need to find a simple, efficient and scalable method to produce new ABZ formulations with increased bioavailability. Bearing this in mind, ABZ nanocrystals (ABZ-NCs) appears to be a useful tool to achieve this goal. The aim of the current study was to investigate the chemoprophylactic and clinical efficacy of an ABZ-NC formulation on mice infected with E. multilocularis. In the chemoprophylactic efficacy study, mean weight of the cysts recovered from the ABZ-NC group was 50% lower than that recorded from untreated mice, whereas the treatment with ABZ suspension did not show preventive effect. The viability of protoscoleces isolated from ABZ-NC treated mice was significantly lower than control groups. In the clinical efficacy studies, both ABZ formulations resulted in a reduction in the mean weight of the cysts obtained from mice, however only the treatment with the nanosuspension revealed significant differences (P < 0.05) compared to the control groups. Treatment with ABZ-NCs reduced the weight of the cysts by 77% and the viability of their protoscoleces to 34%. All these results coincided with the tissue damage determined at the ultrastructural level. The enhanced chemoprophylactic and clinical efficacy of ABZ-NCs observed in this study could be attributed to an increase in the oral bioavailability of the drug. In a next step, we will characterize the cyst concentration profile after the administration of ABZ-NCs in mice infected with E. multilocularis.

Primary cell culture of Echinococcus granulosus developed from the cystic germinal layer: biological and functional characterization.

Cell cultures of parasitic helminths are an invaluable tool for investigations of basic biological processes, as well as for development of improved chemotherapeutic agents and molecular interactions between host and parasite. We carried out a simple and efficient methodology to isolate Echinococcus granulosus germinal cells which were maintained for at least 4 months while cultivated in the presence of reducing agents and hormones. Microscopic analysis of the primary cell culture revealed the presence of cells with similar Echinococcus germinal cell morphology and behaviour. Population doubling time was estimated at 48 h, showing a rapid division rate. To discard possible host contamination, the specificity of the primary culture was tested by nested PCR, analyzing mdh gene expression and obtaining only one product with the expected size. We also studied the expression of specific E. granulosus proteins in primary cell culture. The novel and systematized method described here constitutes a powerful tool for investigations in cystic echinococcosis on biochemical and biological aspects related to the life cycle of the parasite and mechanisms of host-parasite interactions. This method also constitutes a powerful tool for the design of more efficient therapeutic alternatives.

Efficacy of thymol against Echinococcus granulosus protoscoleces.

The aim of the present work was to determine the in vitro protoscolicidal effect of thymol against Echinococcus granulosus. Protoscoleces of E. granulosus were incubated with thymol at concentrations of 10, 5 and 1 mug/ml. The first signs of thymol-induced damage were observed between 1 and 4 days post-incubation. The maximum protoscolicidal effect was found with thymol at 10 microg/ml, viability reduced to 53.5+/-11.9% after 12 days of incubation. At day 42, viability was 11.5+/-15.3% and, reached 0% after 80 days. Thymol at concentrations of 5 and 1 microg/ml provoked a later protoscolicidal effect. Results of viability tests were consistent with the tissue damage observed at the ultrastructural level. The primary site of damage was the tegument of the parasite. The morphological changes included contraction of the soma region, formation of blebs on the tegument, rostellar disorganization, loss of hooks and destruction of microtriches. The data reported in this article demonstrate a clear in vitro effect of thymol against E. granulosus protoscoleces.