Carolina Miguel Fraga

Taenia crassiceps: host treatment alters glycolisis and tricarboxilic acid cycle in cysticerci.

Human cysticercosis by Taenia crassiceps is rare although it is considered of zoonotic risk, especially to immunocompromised individuals. Albendazole and praziquantel are widely used and effective in its treatment. Their active forms inhibit the glucose uptake by the parasite and induce muscle contractions that alter its glycogen levels interfering in the energetic metabolism of the parasite and leading to its death. The aim of this study was to evaluate alterations in glycolysis, the tricarboxylic acid cycle and glucose concentrations caused by low dosage treatments of the hosts with albendazole and praziquantel. Therefore, T. crassiceps intraperitoneally infected mice were treated by gavage feeding with 5.75 or 11.5 mg/kg of albendazole and 3.83 or 7.67 mg/kg of praziquantel. The treated mice were euthanized after 24 h and the cysticerci collected were morphologically classified into initial, larval or final phases. Concentrations of the organic acid produced and glucose were evaluated to detect alterations into the glycolysis and the tricarboxylic acid cycle pathways through chromatography and spectrophotometry. The low dosage treatment caused a partial blockage of the glucose uptake by the cysticerci in spite of the non significant difference between its concentrations. An activation of the tricarboxylic acid cycle was noted in the cysticerci that received the treatment due to an increase in the production of citrate, malate and α-ketoglutarate and the consumption of oxaloacetate, succinate and fumarate. The detection of α-ketoglutarate indicates that the cysticerci which were exposed to the drugs after host treatment present different metabolic pathways than the ones previously described after in vitro treatment.

Fatty acids oxidation and alternative energy sources detected in Taenia crassiceps cysticerci after host treatment with antihelminthic drugs

Human cysticercosis caused by Taenia crassiceps is rare however it is considered of zoonotic risk. The treatment of the infected patients was successful when using albendazole or praziquantel. The active forms of albendazole inhibit the glucose uptake and the active forms of praziquantel alter glycogen levels and nutrients absorption. The aim of this study was to analyze the production of organic acids that indicate the oxidation of fatty acids and the use of alternative energy sources from T. crassiceps cysticerci removed from the peritoneal cavity of mice treated with low dosages of albendazole (5.75 and 11.5mg/kg) or praziquantel (3.83 and 7.67 mg/kg). The beta-hydroxibutyrate production was higher by the larval stage cysticerci in all treated groups and the propionate production was higher in final stage cysticerci treated with 11.5mg/kg of albendazole when compared to the control group. The larval stages of cysticerci from the groups treated with 5.75 mg/kg of albendazole and 3.83 mg/kg of praziquantel produced more urea than the initial and final stages which indicate amino acids breakdown. We conclude that it was possible to detect the fatty acid oxidation and amino acids breakdown which indicate the use of alternative energy production sources as the used dosages only cause a partial blockage of the glucose uptake and leads to metabolic alterations in the cysticerci. The metabolic behavior observed after host treatment was different from former descriptions of the in vitro one which indicates great host-parasite interaction.

Elucidating the influence of praziquantel nanosuspensions on the in vivo metabolism of Taenia crassiceps cysticerci

The aim of this work was to develop nanosuspensions of praziquantel (PZQ) and to evaluate their influence on the energetic metabolism of cysticerci inoculated in BALB/c mice. We analyzed metabolic alterations of glycolytic pathways and the tricarboxylic acid cycle in the parasite. The nanosuspensions were prepared by precipitation and polyvinyl alcohol (PVA), poloxamer 188 (P188) and poloxamer 407 (P407) were used as stabilizers. Nanosuspension prepared with PVA had a particle size of 100nm, while P188- and P407-based nanosuspensions had particle sizes of 74nm and 285nm, respectively. The zeta potential was -8.1, -8.6, and -13.2 for the formulations stabilized with PVA, P188 and P407, respectively. Treatments of T. crassiceps cysticerci-infected mice resulted in an increase in glycolysis organic acids, and enhanced the partial reversion of the tricarboxylic acid cycle, the urea cycle and the production of ketonic bodies in the parasites when compared to the groups treated with conventional PZQ. These data suggest that PZQ nanosuspensions greatly modified the energetic metabolism of cysticerci in vivo. Moreover, the remarkable metabolic alterations produced by the stabilizers indicate that further studies on nanoformulations are required to find potentially suitable nanomedicines.

Alternative energy production pathways in Taenia crassiceps cysticerci in vitro exposed to a benzimidazole derivative (RCB20)

Biochemical studies of benzimidazole derivatives are important to determine their mode of action and activity against parasites. The lack of antihelminthic alternatives to treat parasitic infections and albendazole resistance cases make the search for new antiparasitary drugs of utmost importance. The 6-chloro-5-(1-naphthyloxy)-2-(trifluoromethyl)-1H-benzimidazole (RCB20) is a benzimidazole derivative with promising effect. This study evaluated the effect of different concentrations of RCB20 in the alternative energetic pathway of in vitro Taenia crassiceps cysticerci. The parasites were in vitro exposed to 6.5 and 13 µM of RCB20 and albendazole sulfoxide (ABZSO). The quantification of acetate, acetoacetate, β-hydroxybutyrate, fumarate and propionate was performed by high-performance liquid chromatography. The quantification of urea, creatinine and total proteins was performed by spectrophotometry. The increase in β-hydroxybutyrate reflects the enhancement of the fatty acid oxidation in the treated groups. Volatile fatty acids secretion, acetate and propionate, was increased in the treated groups. The secretion mechanisms of the treated parasites were impaired due to organic acids increased concentrations in the cysticerci. It is possible to conclude that the metabolic effect on alternative energetic pathways is slightly increased in the parasites treated with RCB20 than the ones treated with ABZSO.

A benzimidazole derivative (RCB15) in vitro induces the alternative energetic metabolism and glycolysis in Taenia crassiceps cysticerci

The emergence of resistance to albendazole has encouraged the search for effective alternatives for cysticercosis and other parasitosis treatment. RCB15 is a benzimidazole derivative that may be used against such diseases. The aim of this study was to determine the in vitro effect of RCB15 on the alternative energetic pathways of Taenia crassiceps cysticerci. The cysticerci were in vitro exposed to albendazole sulphoxide (ABZSO) or RCB15 at different concentrations during 24h. The cysticerci extract and the culture medium were analyzed through spectrophotometry and high performance liquid chromatography as to detect glucose, urea, creatinine and organic acids of the energetic metabolism. The drugs did not influence the protein catabolism. Fatty acids oxidation was enhanced through significantly higher acetate concentrations in the groups treated with RCB15 and ABZSO. Beta-hydroxybutyrate concentrations were decreased which indicates the use of fatty acids towards acetyl-CoA synthesis. There was a decrease in glucose uptake and pyruvate concentrations. The absence of lactate indicates the use of pyruvate in gluconeogenesis. Therefore it is possible to conclude that RCB15 enhanced the alternative energetic pathways of cysticerci in vitro exposed to different concentration, with emphasis on the fatty acids catabolism.

In vitro stressing factors altering the TCA cycle and morphology of Taenia crassiceps cysticerci

Abstract Objective To determine the morphological and biochemical alterations of in vitro induced Taenia crassiceps cysticerci by the presence of glucose, insulin and praziquantel isolated and in association. Methods The cysticerci were cultured for 24 h in supplemented Roswell Park Memorial Institute culture medium and added to two different concentrations of glucose, insulin and praziquantel. The morphometrical analysis was performed through the ImageJ programme, and the biochemical one through high-performance liquid chromatography. Results The exposure to the stressing factors led to alterations in the morphology and decrease in the growth rate of the parasite. Conclusions The metabolic effects are related to a decrease in the tricarboxylic acid cycle and fatty acids oxidation metabolites due to the drugs mode of action. Interestingly, the praziquantel, insulin and glucose association enhanced the drugs mode of action with a greater decrease of the tricarboxylic acid cycle metabolites.