Efficacy of albendazole in combination with thymol against Echinococcus multilocularis protoscoleces and metacestodes

Receptor Tyrosine Kinase Signaling Involves Echinococcus-Host Intercommunication: A Potential Therapeutic Target in Hepatic Echinococcosis

Echinococcosis, one of the most serious and life-threatening parasitic forms of zoonosis worldwide, is caused by the larvae of Echinococcus granulosus (E. granulosus) and Echinococcus multilocularis (E. multilocularis). Various drugs are being applied clinically to treat zoonosis; however, their therapeutic efficacy remains a great challenge, especially with albendazole as the preferred drug of choice. Receptor tyrosine kinase (RTK) signaling controls normal cellular proliferation, differentiation, and metabolism in humans and mammals, which are intermediate hosts of E. granulosus and E. multilocularis. Disruption of RTK signaling can cause various forms of carcinogenesis and exacerbate the progression of certain forms of parasitic disease. As a result, a significant number of studies on tyrosine kinase inhibitors (TKIs) have been conducted for the treatment of cancer and parasitic infection, with some TKIs already approved for clinical use for cancer. Notably, RTK signaling has been identified in the parasites E. granulosus and E. multilocularis; however, the mechanisms of RTK signaling response in Echinococcus-host intercommunication are not fully understood. Thus, understanding the RTK signaling response in Echinococcus-host intercommunication and the potential effect of RTK signaling is crucial for identifying new drug targets for echinococcosis. The present review illustrates that RTK signaling in the host is over-activated following infection by E. granulosus or E. multilocularis and can further facilitate the development of metacestodes in vitro. In addition, some TKIs exert strong parasitostatic effects on E. granulosus or E. multilocularis, both in vitro and/or in vivo, through downregulation of RTK signaling molecules. The summarized findings suggest that RTK signaling may be a promising drug target and that TKIs could be potential anti-Echinococcus drugs warranting further research.

Efficacy and mechanism of energy metabolism dual-regulated nanoparticles (atovaquone-albendazole nanoparticles) against cystic echinococcosis

BACKGROUND

Albendazole (ABZ) and atovaquone (ATO) achieve killing efficacy on Echinococcus granulosus (Egs) by inhibiting energy metabolism, but their utilization rate is low. This study aims to analyze the killing efficacy of ABZ-ATO loading nanoparticles (ABZ-ATO NPs) on Egs.

METHODS

Physicochemical properties of NPs were evaluated by ultraviolet spectroscopy and nanoparticle size potentiometer. In vitro experiments exmianed the efficacy of ATO, ABZ, or ATO-ABZ NPs on protoscolex activity, drug toxicity on liver cell LO2, ROS production, and energy metabolism indexes (lactic dehydrogenase, lactic acid, pyruvic acid, and ATP). In vivo of Egs-infected mouse model exmianed the efficacy of ATO, ABZ, or ATO-ABZ NPs on vesicle growth and organ toxicity.

RESULTS

Drug NPs are characterized by uniform particle size, stability, high drug loading, and - 21.6mV of zeta potential. ABZ or ATO NPs are more potent than free drugs in inhibiting protoscolex activity. The protoscolex-killing effect of ATO-ABZ NPs was stronger than that of free drugs. In vivo Egs-infected mice experiment showed that ATO-ABZ NPs reduced vesicle size and could protect various organs. The results of energy metabolism showed that ATO-ABZ NPs significantly increased the ROS level and pyruvic acid content, and decreased lactate dehydrogenase, lactic acid content, and ATP production in the larvae. In addition, ATO-ABZ NPs promoted a decrease in DHODH protein expression in protoscolexes.

CONCLUSION

ATO-ABZ NPs exhibits anti-CE in vitro and in vivo, possibly by inhibiting energy production and promoting pyruvic acid aggregation.

Efficacy and Safety of Asparagusic Acid against Echinococcus multilocularis In Vitro and in a Murine Infection Model

Alveolar echinococcosis (AE) stands as a perilous zoonotic affliction caused by the larvae of Echinococcus multilocularis. There is an imperative need to explore novel therapeutic agents or lead compounds for the treatment of AE. Asparagusic acid, characterized by its low toxicity and possessing antimicrobial, antioxidant, and anti-parasitic attributes, emerges as a promising candidate. The aim of this study was to investigate the in vivo and in vitro efficacy of asparagusic acid against E. multilocularis. Morphological observations, scanning electron microscopy, ROS assays, mitochondrial membrane potential assays, and Western blot were used to evaluate the in vitro effects of asparagusic acid on protoscoleces. The effects of asparagusic acid on vesicles were assessed via PGI release, γ-GGT release, and transmission electron microscopy observations. CellTiter-Glo assays, Caspase3 activity assays, flow cytometry, and Western blot were used for an evaluation of the effect of asparaginic acid on the proliferation and apoptosis of germinal cells. The in vivo efficacy of asparagusic acid was evaluated in a murine AE model. Asparagusic acid exhibited a pronounced killing effect on the protoscoleces post-treatment. Following an intervention with asparagusic acid, there was an increase in ROS levels and a decline in mitochondrial membrane potential in the protoscolex. Moreover, asparagusic acid treatment resulted in the upregulation of PGI and γ-GGT release in metacestode vesicles, concomitant with the inhibition of germinal cell viability. Furthermore, asparagusic acid led to an enhanced relative expression of Caspase3 in the culture supernatant of both the protoscoleces and germinal cells, accompanied by an increase in the proportion of apoptotic germinal cells. Notably, asparagusic acid induced an augmentation in Bax and Caspase3 protein expression while reducing Bcl2 protein expression in both the protoscoleces and germinal cells. In vitro cytotoxicity assessments demonstrated the low toxicity of asparagusic acid towards normal human hepatocytes and HFF cells. Additionally, in vivo experiments revealed that asparagusic acid administration at doses of 10 mg/kg and 40 mg/kg significantly reduced metacestode wet weight. A histopathological analysis displayed the disruption of the germinal layer structure within lesions post-asparagusic acid treatment, alongside the preservation of laminated layer structures. Transmission electron microscopy further revealed mitochondrial swelling and heightened cell necrosis subsequent to the asparagusic acid treatment. Furthermore, asparagusic acid promoted Caspase3 and Bax protein expression while decreasing Bcl2 protein expression in perilesional tissues. Subsequently, it inhibited the expression of Ki67, MMP2, and MMP9 proteins in the perilesional tissues and curbed the activation of the PI3K/Akt signaling pathway within the lesion-host microenvironmental tissues. Asparagusic acid demonstrated a pronounced killing effect on E. multilocularis, suggesting its potential as a promising therapeutic agent for the management of AE.

Experimental treatment of cystic echinococcosis: Combination therapy with carvacrol and thymol versus albendazole

Cystic echinococcosis is a worldwide zoonotic disease caused by Echinococcus granulosus sensu lato (s.l.), which produces serious health and economic problems. For human treatment, chemotherapy with albendazole (ABZ), a derivative of benzimidazoles, is widely used. However, due to its low efficacy and the lack of alternatives to ABZ, novel compounds are urgently needed. Aromatic plants exhibit powerful pharmacological activities, are accessible, have a relatively low cost, and have generally mild toxicities, making them an effective choice to traditional therapies. In particular, the pharmaceutical properties of aromatic plants are partially attributed to essential oils (EOs). The aim of the present study was to assess the in vitro and in vivo effects of the combined carvacrol and thymol against E. granulosus sensu stricto (s.s.). The greatest protoscolicidal effect was observed with the 9:1 and 5:5 (carvacrol:thymol) combinations which caused a marked decrease in viability after 6 days post-incubation, agreeing with the ultrastructural changes obtained. Permeation of the cysts and loss of turgidity was observed with the incubation with the different combinations of carvacrol:thymol. In the clinical efficacy study, the combination of thymol (40 mg/kg) and carvacrol (40 mg/kg) caused a tendency to diminish the weight of the cysts in comparison with the control group. On the other hand, the treatment of infected mice with ABZ, thymol or carvacrol, caused a significant decrease in the weight of the cysts. In conclusion, we here demonstrated the efficacy of different concentrations of combined carvacrol and thymol against E. granulosus s.s. protoscoleces and murine cysts, where short periods of treatment were sufficient to achieve a pharmacological effect. Moreover, we observed a reduction in the weight of the cysts in experimentally infected mice after treatment with carvacrol and thymol. The strategy used has an advantage over synthetic drugs because natural compounds are generally safe and non-toxic. Moreover, the combination of two drugs with different modes of action would cause a reduction in the doses and treatment times. Based on the promising results obtained in vitro, in the future, different doses of the combined drugs will be assayed in vivo to determine the potential of these compounds for the treatment of cystic echinococcosis.

Status and prospect of novel treatment options toward alveolar and cystic echinococcosis

Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are the two most important global parasitic infectious diseases caused by species of Echinococcus granulosus and E. multilocularis, respectively. Although numerous trials have been performed in search of novel therapeutic options to curb the neglected zoonosis, no other nonsurgical options are currently available to replace the licensed anti echinococcal drugs albendazole (ABZ) and mebendazole (MBZ). A safer and more effective treatment plan for echinococcosis is therefore urgently needed to compensate for this therapeutic shortfall. Here, we present a review of the literature for state-of-the-art valuable anti-parasitic compounds and novel strategies that have proved effective against CE and AE, which includes details about the pharmaceutical type, practical approach, experimental plan, model application and protoscolecidal effects in vivo and in vitro. The content includes the current application of traditional clinical chemicals, the preparation of new compounds with various drug loadings, repurposing findings, combined programs, the prospects for Chinese herbal medicines, non-drug administrations and the exploration of target inhibitors based on open-source information for parasitic genes. Next the conventional experimental projects and pharmacodynamic evaluation methods are systematically summarized and evaluated. The demands to optimize the construction of the echinococcosis model and improve the dynamic monitoring method in vivo are also discussed given the shortcomings of in vivo models and monitoring methods.

The combination of carvacrol and albendazole enhanced the efficacy of monotherapy in experimental alveolar echinococcosis

Alveolar echinococcosis is a helminthic zoonosis caused by the larval stage of Echinococcus multilocularis. When surgical resection of the parasite is not feasible, pharmacological treatment with albendazole is the only option. Due to the difficulties in achieving the success of treatment, it is necessary to find new drugs to improve the treatment of this disease. In the present work, the efficacy of carvacrol alone or combined with albendazole was evaluated against E. multilocularis metacestodes. The association of carvacrol with albendazole produced a greater in vitro effect than the compounds incubated separately. The most effective treatment was the combination of 10 μg/ml of carvacrol and 1 μg/ml of albendazole. In the clinical efficacy study, treatment of infected mice with carvacrol (40 mg/kg) and albendazole (25 mg/kg) reduced the weight of metacestodes by 29 % and 50 %, respectively; while the combination of drugs had an efficacy of 83 %. These results coincided with the tissue damage observed at the ultrastructural level. In conclusion, carvacrol and albendazole combination enhanced the efficacy of monotherapy. This strategy would allow to improve the efficacy of the treatment without increasing the doses of albendazole or lengthen the treatment period, reducing the occurrence of adverse effects.

In vitro and in vivo efficacy of thiacloprid against Echinococcus multilocularis

BACKGROUND

Alveolar echinococcosis (AE) is a chronic zoonosis caused by the larval form of Echinococcus multilocularis (E. multilocularis). Current chemotherapy against AE has relied on albendazole and mebendazole, which only exhibit parasitostatic and not parasiticidal efficacy. Therefore, novel compounds for the treatment of this disease are needed.

METHODS

Phosphoglucose isomerase (PGI) assays were used for compound screening of seven neonicotinoids. The anti-parasitic effects of thiacloprid were then evaluated on E. multilocularis metacestode vesicles, germinal cells and protoscoleces in vitro. Human foreskin fibroblasts (HFF) and Reuber rat hepatoma (RH) cells were used to assess cytotoxicity. Glucose consumption in E. multilocularis protoscoleces and germinal cells was assessed by measuring uptake of 2-deoxyglucose (2-DG). Molecular docking was used to evaluate the potential binding sites of thiacloprid to acetylcholine receptors. In vivo efficacy of thiacloprid was evaluated in mice by secondary infection with E. multilocularis. In addition, ELISA and flow cytometry were used to evaluate the effects of cytokines and T lymphocyte subsets after thiacloprid treatment. Furthermore, collagen deposition and degradation in the host lesion microenvironment were evaluated.

RESULTS

We found that thiacloprid is the most promising compound, with an IC50 of 4.54 ± 1.10 μM and 2.89 ± 0.34 μM, respectively, against in vitro-cultured E. multilocularis metacestodes and germinal cells. Thiacloprid was less toxic for HFF and RH mammalian cell lines than for metacestodes. In addition, thiacloprid inhibited the acetylcholinesterase activity in protoscoleces, metacestodes and germinal cells. Thiacloprid inhibited glucose consumption by protoscoleces and germinal cells. Subsequently, transmission electron microscopy revealed that treatment with thiacloprid damaged the germinal layer. In vivo, metacestode weight was significantly reduced following oral administration of thiacloprid at 15 and 30 mg/kg. The level of CD4+ T lymphocytes in metacestodes and spleen increased after thiacloprid treatment. Anti-echinococcosis-related cytokines (IL-2, IL-4, IL-10) were significantly increased. Furthermore, thiacloprid inhibited the expression of matrix metalloproteinases (MMPs 1, 3, 9, 13) and promoted collagen deposition in the host lesion microenvironment.

CONCLUSIONS

The results demonstrated that thiacloprid had parasiticidal activity against E. multilocularis in vitro and in vivo, and could be used as a novel lead compound for the treatment of AE.

In vivo and in vitro efficacy of crocin against Echinococcus multilocularis

Background

Alveolar echinococcosis (AE) is a fatal zoonosis caused by the larvae of Echinococcus multilocularis. However, current chemotherapy treatment options are based on benzimidazoles [albendazole (ABZ) and mebendazole], which have limited efficacy. Therefore, novel drugs are necessary for the treatment of this disease.

Methods

The anthelmintic effects of crocin were tested on E. multilocularis metacestodes, germinal cells and protoscoleces in vitro. Human foreskin fibroblasts (HFFs) and Reuber rat hepatoma (RH) cells were used to assess cytotoxicity. The in vivo efficacy of crocin was investigated in mice following secondary infection with E. multilocularis. Furthermore, collagen deposition and degradation in host tissues around the metacestodes were evaluated.

Results

In vitro, crocin had a median effective concentration of 11.36 μM against cultured E. multilocularis metacestodes, while it reduced germinal cell viability at a median inhibitory concentration of 10.05 μM. Crocin was less toxic to HFFs and RH mammalian cell lines than to metacestodes. Transmission electron microscopy revealed that crocin treatment resulted in structural damage in the germinal layer. In addition, 60.33 ± 3.06% of protoscoleces were killed by treatment with 10 μM crocin for 7 days, indicating that crocin has a parasiticidal effect. In vivo, the metacestode weight was significantly reduced after the administration of crocin at 50 mg/kg and 100 mg/kg (55.1 and 68.1%, respectively). Metacestode pathology showed structural disruption of the germinal and laminated layers after crocin treatment. The crocin- and ABZ-treated groups presented significant increases in the levels of interleukin (IL)-2 and IL-4. Furthermore, crocin inhibited the expression of matrix metalloproteinases (MMPs) (MMP2 and MMP9) and promoted collagen deposition in the metacestode.

Conclusions

Crocin was demonstrated to exert parasiticidal activity against E. multilocularis in vitro and in vivo, and can be developed as a novel drug for the treatment of AE.

Graphical abstract

Supplementary information

The online version contains supplementary material available at 10.1186/s13071-021-04866-4.

Anti-echinococcal effect of verapamil involving the regulation of the calcium/calmodulin-dependent protein kinase II response in vitro and in a murine infection model

Background

Echinococcosis, which is 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 associated side effects after its long-term use. Hence, novel anti-parasitic targets and effective treatment alternatives are urgently needed. A previous study showed that verapamil (Vepm) 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 Vepm on Echinococcus with a particular focus on the regulatory effect of Vepm on calcium/calmodulin-dependent protein kinase II (Ca²⁺/CaM-CaMKII) in infected mice.

Methods

The anti-echinococcal effects of Vepm on Echinococcus granulosus protoscoleces (PSC) in vitro and Echinococcus multilocularis metacestodes in infected mice were assessed. The morphological alterations in Echinococcus spp. induced by Vepm 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 Vepm by immunohistochemistry and/or real-time quantitative polymerase chain reaction.

Results

In vitro, E. granulosus PSC could be killed by Vepm 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 by 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 Vepm, 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 Vepm.

Conclusions

Vepm exerted a parasiticidal effect against Echinococcus both in vitro and in vivo through downregulating the expression of Ca²⁺/CaM-CaMKII, which was over-activated by parasitic infection. The results suggest that Ca²⁺/CaM-CaMKII may be a novel drug target, and that Vepm is a potential anti-echinococcal drug for the future control of echinococcosis.

In vitro potential effect of Pipper longum methanolic extract against protoscolices of hydatid cysts

This study aimed to evaluate the efficacy of methanolic extract of P. longum (PLM) against protoscolices of hydatid cyst in vitro. Four different concentrations of PLM extract (25, 50, 100 and 150 mg/ml) were used for the experiments. The metabolites in the PLM extract were characterized by Gas chromatography-mass spectrometry (GC-MS). The results showed the highest lethality of PLM extract in 50 mg/ml for 60 min exposure. The IC₅₀ value obtained about 20 mg/ml for 60 min of PLM extract exposure. In this study, valuable findings were obtained for the first time about the scolicidal activity of P. longum, which is expected to conduct further studies in this field in the future.

Dihydroartemisinin induces ER stress-dependent apoptosis of Echinococcus protoscoleces in vitro

In this study, we investigated the effect of dihydroartemisinin on Echinococcus protoscoleces and explored the role of endoplasmic reticulum stress in this process. Echinococcus protoscoleces were collected and cultured in RPMI 1640 medium. Changes in the expressions of glucose-regulated protein 78 (GRP-78), caspase-12, and C/EBP homologous protein (CHOP) were assessed through confocal immunofluorescence and western blot analysis. Cell viability and morphological changes were observed under a light microscope. The ultrastructure of protoscoleces was observed by scanning electron microscopy and transmission electron microscopy. Caspase-3 activity was detected using an enzyme assay kit. After dihydroartemisinin treatment, the protoscoleces showed loss of viability, and morphological changes including soma contraction, blebs formation, hooks loss, microtrichia destruction, and development of lipid droplets was observed. The levels of caspase-12 and CHOP were increased within 2 days of dihydroartemisinin treatment. However, the levels of GRP-78, caspase-12, and CHOP were decreased in 4 days. Furthermore, caspase-3 activity was increased after treatment with different concentrations of dihydroartemisinin. Dihydroartemisinin can induce apoptosis in protoscoleces via the ER stress-caspase-3 apoptotic pathway in vitro. These results indicate that dihydroartemisinin is a potentially valuable therapeutic agent against echinococcosis.

Drug repurposing applied: Activity of the anti-malarial mefloquine against Echinococcus multilocularis

The current chemotherapeutical treatment against alveolar echinococcosis relies exclusively on benzimidazoles, which are not parasiticidal and can induce severe toxicity. There are no alternative treatment options. To identify novel drugs with activity against Echinococcus multilocularis metacestodes, researchers have studied potentially interesting drug targets (e.g. the parasite's energy metabolism), and/or adopted drug repurposing approaches by undertaking whole organism screenings. We here focus on drug screening approaches, which utilize an in vitro screening cascade that includes assessment of the drug-induced physical damage of metacestodes, the impact on metacestode viability and the viability of isolated parasite stem cells, structure-activity relationship (SAR) analysis of compound derivatives, and the mode of action. Finally, once in vitro data are indicative for a therapeutic window, the efficacy of selected compounds is assessed in experimentally infected mice. Using this screening cascade, we found that the anti-malarial mefloquine was active against E. multilocularis metacestodes in vitro and in vivo. To shed more light into the mode of action of mefloquine, SAR analysis on mefloquine analogues was performed. E. multilocularis ferritin was identified as a mefloquine-binding protein, but its precise role as a drug target remains to be elucidated. In mice that were infected either intraperitoneally with metacestodes or orally with eggs, oral treatment with mefloquine led to a significant reduction of parasite growth compared to the standard treatment with albendazole. However, mefloquine was not acting parasiticidally. Assessment of mefloquine plasma concentrations in treated mice showed that levels were reached which are close to serum concentrations that are achieved in humans during long-term malaria prophylaxis. Mefloquine might be applied in human AE patients as a salvage treatment. Future studies should focus on other repurposed anti-infective compounds (MMV665807, niclosamide, atovaquone), which showed stronger in vitro activity against E. multilocularis than mefloquine.

Anti-echinococcal activity of menthol and a novel prodrug, menthol-pentanol, against Echinococcus multilocularis

Alveolar echinococcosis is one of the most dangerous parasitic zoonoses. This disease, widely distributed in the northern hemisphere, is caused by the metacestode stage of the tapeworm Echinococcus multilocularis. All surgical and non-surgical patients should perform chemotherapy with benzimidazoles, mainly with albendazole. However, the efficacy of albendazole is variable due to its deficient pharmacokinetic properties. Therefore, the need to find new therapeutic alternatives for the treatment of alveolar echinococcosis is evident. Menthol is a natural compound of low toxicity, used in industries such as cosmetics and gastronomy and generally recognized as safe by the Food and Drug Administration. In addition, menthol has important pharmacological effects and is effective against a wide variety of organisms. The development of prodrugs allows improving the pharmacokinetic properties of the parental drug. To improve lipophilicity and therefore the bioavailability of menthol, a novel prodrug called menthol-pentanol was developed by masking the functional polar group of menthol by linking n-pentanol by a carbonate bond. The aim of the current work was to evaluate the in vitro and in vivo efficacy of menthol and menthol-pentanol against E. multilocularis. Menthol-pentanol had a greater protoscolicidal effect than menthol. In addition, the prodrug demonstrated a similar clinical efficacy to albendazole. The increase in lipophilicity of the prodrug with respect to menthol was reflected in an increase in its antiparasitic activity against E. multilocularis. Thus, menthol-pentanol appears as a promising candidate for further evaluation as a potential alternative for the treatment of alveolar echinococcosis.

Individualized biliary reconstruction techniques in autotransplantation for end-stage hepatic alveolar echinococcosis

BACKGROUND

Biliary reconstruction in ex vivo liver resection followed by autotransplantation (ERAT) for end-stage hepatic alveolar echinococcosis (HAE) remains the most challenging step, we present our experience with this complex procedure.

METHODS

A retrospective data analysis of 55 patients with end-stage HAE underwent ERAT, the biliary reconstruction techniques and short- and long-term outcomes were discussed.

RESULTS

All autografts were derived from the left lateral section after extensive ex vivo liver resection, multiple bile ducts were observed in 52 (94.5%) patients, and forty-four (80.0%) cases required ductoplasty. Biliary reconstruction was achieved with duct-to-duct anastomosis in 32 (58.2%) patients, Roux-en-Y hepaticojejunostomy (RYHJ) in 14 (25.5%) patients, and a combination of the two methods in 9 (16.4%) patients. Twenty (36.4%) patients had multiple anastomoses. Biliary leakage occurred in 8 (14.5%) patients postoperatively. Three (5.5%) patients died of liver failure, cerebral hemorrhage and intraabdominal bleeding. During a median of 31 months followed-up time, 3 (5.5%) patients developed anastomotic stricture, 1 of whom was treated by repeat RYHJ, while the others were managed with stenting.

CONCLUSIONS

With a well-designed plan and precise anastomosis, complex biliary reconstruction in ERAT can be performed with few biliary complications by a professional team.

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.

The importance of being parasiticidal… an update on drug development for the treatment of alveolar echinococcosis

The lethal disease alveolar echinococcosis (AE) is caused by the metacestode stage of the fox tapeworm Echinococcus multilocularis. Current chemotherapeutical treatment of AE relies on albendazole and mebendazole, with the caveat that these compounds are not parasiticidal. Drugs have to be taken for a prolonged period of time, often life-long, which can cause adverse effects and reduces the patients' quality of life. In some individuals, benzimidazoles are inactive or cause toxicity, leading to treatment discontinuation. Alternatives to benzimidazoles are urgently needed. Over the recent years, in vivo and in vitro models for low-to-medium throughput drug discovery against AE have been set in place. In vitro drug tests include the phosphoglucose-isomerase (PGI) assay to measure physical damage induced to metacestodes, and viability assays to assess parasiticidal activity against metacestodes and stem cells. In vitro models are also employed for studies on mechanisms of action. In vivo models are thus far based on rodents, mainly mice, and benefits could be gained in future by comparative approaches in naturally infected dogs or captive monkeys.

For the identification of novel drugs against AE, a rare disease with a low expected market return, drug-repurposing is the most promising strategy. A variety of chemically synthesized compounds as well as natural products have been analyzed with respect to in vitro and/or in vivo activities against AE. We here review and discuss the most active of these compounds including anti-infective compounds (benzimidazoles, nitazoxanide, amphotericin B, itraconazole, clarithromycin, DB1127, and buparvaquone), the anti-infective anti-malarials (artemisinin, ozonids, mefloquine, and MMV665807) and anti-cancer drugs (isoflavones, 2-methoxyestradiol, methotrexate, navelbine, vincristine, kinase inhibitors, metallo-organic ruthenium complexes, bortezomib, and taxanes). Taking into account the efficacy as well as the potential availability for patients, the most promising candidates are new formulations of benzimidazoles and mefloquine. Future drug-repurposing approaches should also target the energy metabolism of E. multilocularis, in particular the understudied malate dismutation pathway, as this offers an essential target in the parasite, which is not present in mammals.

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Benzimidazoles are used to treat AE, but new drugs are needed.

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New drugs against AE can be identified by drug repurposing.

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Drugs against other infectious diseases and cancer can be repurposed against AE.

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Most promising are new formulations of benzimidazoles and mefloquine.

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Future approaches should include targeting the energy metabolism of the parasite.

Could beta-myrcene be an alternative to albendazole for the treatment of experimental cystic echinococcosis?

Echinococcus granulosus causes hydatidosis or cystic echinococcosis in humans and livestock. In humans, this disease can be managed with surgery, percutaneous treatment, chemotherapy and/or observation. The chemotherapeutic agents used and approved for treatment of hydatidosis are benzimidazoles. Because of the difficulties in achieving successful treatment, considerable efforts have been made to find new natural compounds against hydatid disease. Beta-myrcene is a monoterpene presented in the essential oils of different plants. It is the principal component of essential oil of Rosmarinus officinalis (rosemary). The goal of the present study was to evaluate the in vitro effects of beta-myrcene against germinal cells, protoscoleces and murine cyst of E. granulosus, as well also, investigate its chemoprophylactic activity in a murine model of cystic echinococcosis. For the in vitro assays, the parasites were incubated with beta-myrcene at 10, 5 and 1 μg/mL. The treatments were dose and time-dependent, and consistent with the observed morphological alterations. In the chemoprophylactic efficacy study, the effect of beta-myrcene was similar to albendazole, the reference drug for human echinococcosis treatment.

Anthelmintic effect of thymol and thymol acetate on sheep gastrointestinal nematodes and their toxicity in mice

Thymol is a monoterpene and acetylation form of this compound can reduce the toxicity and enhance its biological effects. The objective of this study was to evaluate the effect of thymol and thymol acetate (TA) on egg, larva and adult Haemonchus contortus and the cuticular changes, acute toxicity in mice and the efficacy on sheep gastrointestinal nematodes. In vitro tests results were analyzed by analysis of variance (ANOVA) and followed by comparison with Tukey test or Bonferroni. The efficacy of in vivo test was calculated by the BootStreet program. In the egg hatch test (EHT), thymol (0.5 mg/mL) and TA (4 mg/mL) inhibited larval hatching by 98% and 67.1%, respectively. Thymol and TA (8 mg/mL) inhibited 100% of larval development. Thymol and TA (800 µg/mL) reduced the motility of adult worms, by 100% and 83.4%, respectively. Thymol caused cuticular changes in adult worm teguments. In the acute toxicity test, the LD50 of thymol and TA were 1,350.9 mg/kg and 4,144.4 mg/kg, respectively. Thymol and TA reduced sheep egg count per gram of faeces (epg) by 59.8% and 76.2%, respectively. In in vitro tests thymol presented better anthelmintic activity than TA. However TA was less toxic and in in vivo test efficacy was similar.

In Vitro Effects of Amino Alcohols on Echinococcus granulosus

Cystic echinococcosis is a globally distributed zoonotic disease, which is caused by the larval stage of Echinococcosus granulosus sensu lato. The chemotherapy of the disease is limited to the use of benzimidazoles. Recently, mefloquine and its analogues, aminoalcohol-carbazole, and some amino alcohol derivatives were reported to display inhibitory effects on parasites. Here, the activities of 130 amino alcohol compounds against E. granulosus were tested on protoscoleces and germinal cells at a concentration of 20 μg/ml over a period of three days. As a result, sixteen compounds totally were effective against both protoscoleces and germinal cells, and their IC₅₀ and LC₅₀ were also calculated respectively. Then effects of the most active compounds were observed on metacestodes over 14 days in vitro. Although the structure of active compounds were variable, hydroxyl and amino groups connected by two carbon atoms are held in common as the key feature of these compounds. The further investigation on metacestodes incubated with these active compounds revealed that the effects of JF16 and BTB4 were comparable to that of mefloquine and mebendazole. In addition, the ultrastructure alternations induced by these compounds on E. granulosus were confirmed by scanning electron microscopy and transmission electron microscopy observations. In conclusion, amino alcohols were a class of compounds with efficacy against E. granulosus. The most effective compounds JF16 and BTB4 indicated that their basic structure would be useful in the synthesis of new compound for the treatment of echinococcosis. However, their in vivo efficacy and toxicity need to be carefully evaluated in the future.

Progress in the pharmacological treatment of human cystic and alveolar echinococcosis: Compounds and therapeutic targets

Human cystic and alveolar echinococcosis are helmintic zoonotic diseases caused by infections with the larval stages of the cestode parasites Echinococcus granulosus and E. multilocularis, respectively. Both diseases are progressive and chronic, and often fatal if left unattended for E. multilocularis. As a treatment approach, chemotherapy against these orphan and neglected diseases has been available for more than 40 years. However, drug options were limited to the benzimidazoles albendazole and mebendazole, the only chemical compounds currently licensed for treatment in humans. To compensate this therapeutic shortfall, new treatment alternatives are urgently needed, including the identification, development, and assessment of novel compound classes and drug targets. Here is presented a thorough overview of the range of compounds that have been tested against E. granulosus and E. multilocularis in recent years, including in vitro and in vivo data on their mode of action, dosage, administration regimen, therapeutic outcomes, and associated clinical symptoms. Drugs covered included albendazole, mebendazole, and other members of the benzimidazole family and their derivatives, including improved formulations and combined therapies with other biocidal agents. Chemically synthetized molecules previously known to be effective against other infectious and non-infectious conditions such as anti-virals, antibiotics, anti-parasites, anti-mycotics, and anti-neoplastics are addressed. In view of their increasing relevance, natural occurring compounds derived from plant and fungal extracts are also discussed. Special attention has been paid to the recent application of genomic science on drug discovery and clinical medicine, particularly through the identification of small inhibitor molecules tackling key metabolic enzymes or signalling pathways.

Human cystic and alveolar echinococcosis (CE and AE), caused by the larval stages of the helminths Echinococcus granulosus and E. multilocularis, respectively, are progressive and chronic diseases affecting more than 1 million people worldwide. Both are considered orphan and neglected diseases by the World Health Organization. As a treatment approach, chemotherapy is limited to the use of benzimidazoles, drugs that stop parasite growth but do not kill the parasite. To compensate this therapeutic shortfall, new treatment alternatives are urgently needed. Here, we present the state-of-the-art regarding the alternative compounds and new formulations of benzimidazoles assayed against these diseases until now. Some of these new and modified compounds, either alone or in combination, could represent a step forward in the treatment of CE and AE. Unfortunately, few compounds have reached clinical trials stage in humans and, when assayed, the design of these studies has not allowed evidence-based conclusions. Thus, there is still an urgent need for defining new compounds or improved formulations of those already assayed, and also for a careful design of clinical protocols that could lead to the draw of a broad international consensus on the use of a defined drug, or a combination of drugs, for the effective treatment of CE and AE.

Management of Advanced Hepatic Alveolar Echinococcosis: Report of 42 Cases

Radical resection is the first choice for hepatic alveolar echinococcosis (HAE). However, many patients with advanced HAE have no chance to be treated with curative resection owing to the long clinical latency. This study aimed to evaluate the necessity of aggressive operations, like palliative resection and orthotopic liver transplantation (OLT), in the management of advanced HAE. A retrospective study analyzed 42 patients with advanced HAE treated with palliative resection (N = 15), palliative nonresective procedures (N = 13), OLT (N = 3), or albendazole therapy alone (N = 11). The patients' condition before treatments was comparable among all the four groups. The overall 1-year, 3-year, and 5-year survival rates of the 42 cases were 81.0%, 45.2%, and 23.8%, respectively. No event occurred to end the follow-up during the 5-year observation period except death. The survival time (median ± standard error) of the palliative resection group (3.6 ± 1.4 years) was longer than that of the palliative nonresective procedures group (1.5 ± 0.2) and the albendazole therapy-alone group (1.0 ± 0.4). The 5-year survival rates after palliative resection and liver transplantation were 40.0% and 66.7%, compared with only 7.7% and 9.1% after palliative nonresective procedures or albendazole therapy alone. Therefore, we concluded that aggressive treatment with a multimodality strategy could contribute to prolonged survival in patients with advanced HAE. Moreover, the prognosis of the patients who received albendazole therapy alone or palliative nonresective procedures is poor.

Optimization of fluoride-containing bioactive glasses as a novel scolicidal agent adjunct to hydatid surgery

We have presented a novel scolicidal agent made from fluoride-containing bioactive glass (FBG). The samples were characterized by XRD and the ion release behavior of the samples was evaluated at 37°C. The scolicidal activity, cellular response and antibacterial activity and biocompatibility of the different concentrations of the FBG (ranging from 0.5 to 2 mg ml(-1)) were evaluated in vitro and in vivo. The results showed an easy diffusion of the fluoride through the glass matrix in an F concentration-dependent manner. The FBG showed an intensive scolicidal property, so that toxicity effect begun from 5 min and the samples with 20, 10, 5 and 0% fluoride showed 98±2, 93±5.8, 76.2±6 and 5.8±1.7% scolicidal activity, respectively, after 8h exposing time. Our data revealed that scolicidal activity of the FBG increased with the increase of F ratio and concentrations of the bioactive glass. On the other hand, all the synthesized FBG samples found to be cyto-biocompatible when tested in vitro (MTT and LDH assays) and in vivo (no significant infiltration of inflammatory cells compared with control, p>0.05), and antibacterial against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa. The results demonstrated that the synthesized FBG might have a potential application in prevention of post-surgery infections, especially hydatidosis.

In vivo activity of albendazole in combination with thymol against Echinococcus multilocularis

Human alveolar echinococcosis (AE) is caused by the fox tapeworm Echinococcus multilocularis and is usually lethal if left untreated. The current strategy for treating human AE is surgical resection of the parasite mass complemented by chemotherapy with benzimidazole compounds. However, reliable chemotherapeutic alternatives have not yet been developed stimulating the research of new treatment strategies such as the use of medicinal plants. The aim of the current study was to investigate the efficacy of the combination albendazole (ABZ)+thymol on mice infected with E. multilocularis metacestodes. For this purpose, mice infected with parasite material were treated daily for 20 days with ABZ (5 mg/kg), thymol (40 mg/kg) or ABZ (5 mg/kg)+thymol (40 mg/kg) or left untreated as controls. After mice were euthanized, cysts were removed from the peritoneal cavity and the treatment efficacy was evaluated by the mean cysts weight, viability of protoscoleces and ultrastructural changes of cysts and protoscoleces. The application of thymol or the combination of ABZ+thymol resulted in a significant reduction of the cysts weight compared to untreated mice. We also found that although ABZ and thymol had a scolicidal effect, the combination of the two compounds had a considerably stronger effect showing a reduction in the protoscoleces viability of 62%. These results were also corroborated by optical microscopy, SEM and TEM. Protoscoleces recovered from ABZ or thymol treated mice showed alterations as contraction of the soma region, rostellar disorganization and presence of blebs in the tegument. However both drugs when combined lead to a total loss of the typical morphology of protoscoleces. All cysts removed from control mice appeared intact and no change in ultrastructure was detected. In contrast, cysts developed in mice treated with ABZ revealed changes in the germinal layer as reduction in cell number, while the treatment with thymol or the ABZ+thymol combination predominantly showed presence of cell debris. On the other hand, no differences were found in alkaline phosphatase (AP), glutamate oxaloacetate transaminase (GOT) and glutamate pyruvate transaminase (GPT) activities between control and treated mice, indicating the lack of toxicity of the different drug treatments during the experiment. Because combined ABZ+thymol treatment exhibited higher treatment efficiency compared with the drugs applied separately against murine experimental alveolar echinococcosis, we propose it would be a useful option for the treatment of human AE.