Different infective forms trigger distinct lesions in the colon during experimental Chagas disease.

With the control of vectorial transmission of Chagas disease caused by metacyclic trypomastigotes (MT) in endemic countries, other pathways of infection have become important. The infection caused by blood trypomastigotes (BT) is relevant in places where the blood transfusion and organ transplantation are poorly controlled. This study aimed to evaluate immunopathogenic parameters in the colon during the acute and chronic phases of experimental infection in Swiss mice infected with BT or MT forms of VL-10 strain of Trypanosoma cruzi. We have found that animals infected with MT forms presented lower survival rate, and higher tissue parasitism in the acute phase of the disease, which may be associated with the exacerbated activation of the immune system with the production of pro-inflammatory cytokines even in the chronic phase of infection. Taken together, these results can also be associated to the maintenance of the inflammatory process in chronic phase and an earlier denervation of myenteric plexus in colon. These findings emphasized the importance of the inoculum source and the strain, once different forms of different strains seem to promote distinct diseases.

Population pharmacokinetics and biodistribution of benznidazole in mice.

OBJECTIVES: To evaluate the population pharmacokinetics of different benznidazole treatment regimens and the drug's biodistribution in mice. METHODS: Two hundred mice were divided into five groups according to benznidazole dosing regimens: (1) 100 mg/kg/day for 20 days; (2) 100 mg/kg/day for 40 days; (3) 200 mg/kg/day for 20 days; (4) 40 mg/kg/day for 20 days; or (5) 40 mg/kg/day for 40 days. The mice were euthanized and blood, heart, liver, colon and brain were collected. Samples were prepared by liquid-liquid extraction and analysed by HPLC-diode-array detection. The pharmacokinetic analysis of benznidazole was evaluated via non-linear mixed-effects modelling using the NONMEN program. RESULTS: Our results demonstrate that mouse weight allometrically influences benznidazole clearance; the AUC curve and the highest plasma concentration are dose proportional; benznidazole does not influence its own metabolism; its tissue distribution is limited; and the standard treatment regimen for Chagas' disease in mice (100 mg/kg/day for 20 days) is inadequate from a pharmacokinetic standpoint, as are the other regimens tested in this study (100 mg/kg/day for 40 days, 200 mg/kg/day for 20 days and 40 mg/kg/day for 20 or 40 days). CONCLUSIONS: Benznidazole reformulations that allow better tissue penetration and plasma and tissue exposure should be evaluated to enable higher cure rates in both animals and patients. The population pharmacokinetic model developed here can allow optimization of the dosing regimen of benznidazole to treat experimental Chagas' disease. Determining appropriate treatment regimens in animals allows translation of these to clinical studies.

The effect of benznidazole dose among the efficacy outcome in the murine animal model. A quantitative integration of the literature.

Despite more than 100 years since it was firstly described Chagas disease, only two drugs are available to treat Chagas disease: Nifurtimox launched by Bayer in 1965 and benznidazole launched by Roche in 1971. Drug discovery initiatives have been looking for new compounds as an alternative to these old drugs. Although new platforms have been used with the latest technologies, a critical step on that process still relies on the in vivo model. Unfortunately, to date, available animal models have limited predictive value and there is no standardization. With the aim to better understand the role of benznidazole, the current standard of care of Chagas disease, we performed this review. We intend to analyze the influence of the experimental design of the most used animal model, the murine model, in the assessment of the efficacy endpoint.

Synthesis and anti-Trypanosoma cruzi activity of diaryldiazepines.

Chagas disease is a so-called "neglected disease" and endemic to Latin America. Nifurtimox and benznidazole are drugs that have considerable efficacy in the treatment of the acute phase of the disease but cause many significant side effects. Furthermore, in the Chronic Phase its efficiency is reduced and their therapeutic effectiveness is dependent on the type of T. cruzi strain. For this reason, the present work aims to drive basic research towards the discovery of new chemical entities to treat Chagas disease. Differently substituted 5,7-diaryl-2,3-dihydro-1,4-diazepines were synthesized by cyclocondensation of substituted flavones with ethylenediamine and tested as anti-Trypanosoma cruzi candidates. Epimastigotes of the Y strain from T. cruzi were used in this study and the number of parasites was determined in a Neubauer chamber. The most potent diaryldiazepine that reduced epimastigote proliferation exhibited an IC50 value of 0.25 µM, which is significantly more active than benznidazole.

Dogs infected with the blood trypomastigote form of Trypanosoma cruzi display an increase expression of cytokines and chemokines plus an intense cardiac parasitism during acute infection.

The recent increase in immigration of people from areas endemic for Chagas disease (Trypanosoma cruzi) to the United States and Europe has raised concerns about the transmission via blood transfusion and organ transplants in these countries. Infection by these pathways occurs through blood trypomastigotes (BT), and these forms of T. cruzi are completely distinct of metacyclic trypomastigotes (MT), released by triatomine vector, in relation to parasite-host interaction. Thus, research comparing infection with these different infective forms is important for explaining the potential impacts on the disease course. Here, we investigated tissue parasitism and relative mRNA expression of cytokines, chemokines, and chemokine receptors in the heart during acute infection by MT or BT forms in dogs. BT-infected dogs presented a higher cardiac parasitism, increased relative mRNA expression of pro-inflammatory and immunomodulatory cytokines and of the chemokines CCL3/MIP-1α, CCL5/RANTES, and the chemokine receptor CCR5 during the acute phase of infection, as compared to MT-infected dogs. These results suggest that infection with BT forms may lead to an increased immune response, as revealed by the cytokines ratio, but this kind of immune response was not able to control the cardiac parasitism. Infection with the MT form presented an increase in the relative mRNA expression of IL-12p40 as compared to that of IL-10 or TGF-ß1. Correlation analysis showed increased relative mRNA expression of IFN-γ as well as IL-10, which may be an immunomodulatory response, as well as an increase in the correlation of CCL5/RANTES and its CCR5 receptor. Our findings revealed a difference between inoculum sources of T. cruzi, as vectorial or transfusional routes of T. cruzi infection may trigger distinct parasite-host interactions during the acute phase, which may influence immunopathological aspects of Chagas disease.

Prednisolone and cyclosporine A: effects on an experimental model of ancylostomiasis.

Corticosteroids and cyclosporine A (CsA) are important clinical immunosuppressive drugs used in the maintenance of organ transplants and in suppressing undesired autoimmune or allergic immune responses. To study the effect of CsA and prednisolone on the course of an Ancylostoma ceylanicum infection, hamsters were treated with commercially available prednisolone or CsA. For both drugs, half the recommended dose was sufficient to inhibit the proliferation of more than 70% of hamster lymph node cells. There was no difference in the recovery of adult worms; however, animals treated with prednisolone presented with low egg counts in the feces. Infection with A. ceylanicum resulted in an increase in specific antibodies against adult worm antigens, but hamsters treated with either drug presented with lower IgG titers. We observed that A. ceylanicum infection caused peripheral cellular immune suppression, which is characterized by a reduction in the total white cell count, neutropenia and lymphopenia. We also observed a lymphoplasmacytic pattern and few eosinophils in the mucosal inflammatory infiltrate for all the animals. The animals treated with prednisolone showed changes in the architecture of the intestine, including the loss of the mucosa, intense congestion and inflammation. In spleen, we observed hyperplasia of white pulp in all infected animals; in addition, there was a loss of tissue architecture in the animals treated with prednisolone. In conclusion, this work shows that an A. ceylanicum infection leads to acute peripheral cellular immune suppression in hamsters but not humoral immune suppression and that CsA treatment does not interfere with the process of infection. However, prednisolone treatment causes intestinal injury, what could hamper the parasite attachment to the intestinal wall, and as a result affects copulation and, consequently, decreases the number of eggs eliminated in the feces. Moreover, the possibility that the drug can also be exerting an effect on female fertility should be considered.