Different Therapeutic Outcomes of Benznidazole and VNI Treatments in Different Genders in Mouse Experimental Models of Trypanosoma cruzi Infection

Abstract

The lack of translation between preclinical assays and clinical trials for novel therapies for Chagas disease (CD) indicates a need for more feasible and standardized protocols and experimental models. Here, we investigated the effects of treatment with benznidazole (Bz) and with the potent experimental T. cruzi CYP51 inhibitor VNI in mouse models of Chagas disease by using different animal genders and parasite strains and employing distinct types of therapeutic schemes. Our findings confirm that female mice are less vulnerable to the infection than males, show that male models are less susceptible to treatment with both Bz and VNI, and thus suggest that male models are much more suitable for selection of the most promising antichagasic agents. Additionally, we have found that preventive protocols (compound given at 1 dpi) result in higher treatment success rates, which also should be avoided during advanced steps of in vivo trials of novel anti-T. cruzi drug candidates. Another consideration is the relevance of immunosuppression methods in order to verify the therapeutic profile of novel compounds, besides the usefulness of molecular diagnostic tools (quantitative PCR) to ascertain compound efficacy in experimental animals. Our study aims to contribute to the development of more reliable methods and decision gates for in vivo assays of novel antiparasitic compounds in order to move them from preclinical to clinical trials for CD. (1), is a neglected pathology caused by the obligately intracellular protozoan parasite Trypanosoma cruzi. The disease is endemic in 21 countries of Central and South America, where about 8 million people are infected and more than 12,000 die annually (http: //www.dndial.org). The treatment for CD is limited to the use of two nitroderivatives (benznidazole [Bz] and nifurtimox [Nf]), which are largely unsatisfactory, indicating a need for novel, safer, and more efficient therapies (2). Although a large number of in vitro and in vivo studies have been performed on experimental chemotherapy of novel drug candidates for CD, besides Bz and Nf, very few compounds have moved to clinical trials (3). C hagas disease (CD), discovered by Carlos ChagasRecently, two antifungal drugs, posaconazole and E1224 (the prodrug of ravuconazole), which are inhibitors of fungal sterol 14a-demethylase (CYP51), were evaluated as potential antichagasic drugs on chronic patients, but unfortunately both displayed rather high (70 to 80%) rates of therapeutic failure (4, 5). It has been suggested that at least part of this unexpected failure could be due to the lack of translation from in vitro and in vivo models to the clinic and that a redesign of the current screening strategy during the drug discovery process should be considered (5). On the other hand, recent data demonstrated the potency and selectivity of a novel experimental inhibitor of T. cruzi CYP51, the VNI molecule, which yielded promising in vivo findings even with highly resistant T. cruzi strains (6). In this vein, we evaluated the effects and outco...

Antitrypanosomal Activity of Sterol 14α-Demethylase (CYP51) Inhibitors VNI and VFV in the Swiss Mouse Models of Chagas Disease Induced by the Trypanosoma cruzi Y Strain

“…The comparative testing of VNI and VFV in the mouse models of infection with the Y strain of T. cruzi was performed by using both genders, different drug delivery vehicles, and different treatment schemes (Table 2). Both genders were included in the experiments because male mice infected with the Y strain of T. cruzi display about 2-fold greater parasite loads at the peak of parasitemia (which corresponds to day 8 after infection with the Y strain of T. cruzi in this experimental mouse model) and appeared to be more suitable for screening of antiparasitic compounds (32). Indeed, VNI, particularly if the treatment was started 5 days postinfection (dpi) (3 days before peak parasitemia), caused a Ͼ91% peak parasitemia reduction in all male mouse groups versus a Ͼ99% peak parasitemia reduction in the female mouse groups (Table 2).…”

“…For in vivo analysis, the compounds were diluted with three different vehicles, (i) 20% HPCD (CTD, Inc., USA) (36), (ii) 10% DMSO and 5% DGA (as reported in reference 29 for Colombiana T. cruzi infection), and (iii) 5% DMSO and DGAT (26). Cy (Genuxal) was purchased from Baxter Oncology (Frankfurt, Germany) and prepared in sterile distilled water (32). Bz was purchased from Laboratório Farmacêutico do Estado de Pernambuco, LAFEPE, Brazil, and dissolved in sterile distilled water supplemented with 3% Tween 80 as described previously (32).…”

“…Cy (Genuxal) was purchased from Baxter Oncology (Frankfurt, Germany) and prepared in sterile distilled water (32). Bz was purchased from Laboratório Farmacêutico do Estado de Pernambuco, LAFEPE, Brazil, and dissolved in sterile distilled water supplemented with 3% Tween 80 as described previously (32).…”

“…Parasitemia was individually checked by direct microscopic counting of parasites in 5 l of blood, and mortality rates were checked daily until 30 days posttreatment and expressed as percent cumulative mortality as described before (32).…”

“…Similar to VNI, VFV was proven to be 100% efficient in curing Tulahuen T. cruzi infection and displayed higher potency than VNI in a mouse model of visceral leishmaniasis (31). In this study, we compared the effects of VNI and VFV in mouse models of infection with the Y strain of T. cruzi by using both genders (32), different drug delivery vehicles, and different treatment schemes.…”