Phenotypic investigation of 4-nitrophenylacetyl- and 4-nitro-1H-imidazoyl-based compounds as antileishmanial agents.

Cutaneous leishmaniasis (CL) is a spectrum of clinical manifestations characterized by severe skin ulcerations that leads to social stigma. There are limited treatment options for CL, and the available drugs are becoming less efficacious due to drug resistance. More efficacious and safer antileishmanial drugs are needed. In this study, the biological effect of seven synthetically accessible nitroaromatic compounds was evaluated in vitro against amastigotes of Leishmania amazonensis, followed by in vivo evaluation using mouse models of CL. Two compounds (6 and 7) were active against amastigotes in vitro [half-maximal effective concentration (EC50): 4.57 ± 0.08 and 9.19 ± 0.68 µm, respectively], with selectivity indexes >50, and the other compounds were not selective. In vivo, compounds 6 and 7 (10 mg kg−1, twice a day for 14 days) failed to reduce skin lesion sizes and parasite loads determined by light microscopy of lesion imprints and quantitative polymerase chain reaction. Nevertheless, the in vitro leishmanicidal efficacy sustained their use as templates for nitroimidazole-based antileishmanial drug discovery programmes focusing on analogues with more suitable properties.

In Vitro and In Vivo Evaluation of an Adamantyl-Based Phenyl Sulfonyl Acetamide against Cutaneous Leishmaniasis Models of Leishmania amazonensis.

Phenotypic assay against Leishmania amazonensisin vitro and in vivo led to identification of an adamantyl-based phenyl sulfonyl acetamide (compound 1) as a promising antileishmanial agent. Compound 1 inhibited the growth of intracellular forms of L. amazonensis (50% inhibitory concentration [IC50] = 4 µM) and exhibited low toxicity to host cells, with a selectivity index (SI) of >125. However, in a cutaneous leishmaniasis (CL) mouse model, compound 1 did not reduce lesions and parasite load when administered as monotherapy or when given simultaneously with a suboptimal dose of miltefosine.

In Vitro, In Silico, and In Vivo Analyses of Novel Aromatic Amidines against Trypanosoma cruzi.

Five bis-arylimidamides were assayed as anti-Trypanosoma cruzi agents by in vitro, in silico, and in vivo approaches. None were considered to be pan-assay interference compounds. They had a favorable pharmacokinetic landscape and were active against trypomastigotes and intracellular forms, and in combination with benznidazole, they gave no interaction. The most selective agent (28SMB032) tested in vivo led to a 40% reduction in parasitemia (0.1 mg/kg of body weight/5 days intraperitoneally) but without mortality protection. In silico target fishing suggested DNA as the main target, but ultrastructural data did not match.

Oral administration of GW788388, an inhibitor of transforming growth factor beta signaling, prevents heart fibrosis in Chagas disease.

BACKGROUND: Chagas disease induced by Trypanosoma cruzi (T. cruzi) infection is a major cause of mortality and morbidity affecting the cardiovascular system for which presently available therapies are largely inadequate. Transforming Growth Factor beta (TGFß) has been involved in several regulatory steps of T. cruzi invasion and in host tissue fibrosis. GW788388 is a new TGFß type I and type II receptor kinase inhibitor that can be orally administered. In the present work, we studied its effects in vivo during the acute phase of experimental Chagas disease. METHODOLOGY/PRINCIPAL FINDINGS: Male Swiss mice were infected intraperitoneally with 10(4) trypomastigotes of T. cruzi (Y strain) and evaluated clinically. We found that this compound given once 3 days post infection (dpi) significantly decreased parasitemia, increased survival, improved cardiac electrical conduction as measured by PR interval in electrocardiography, and restored connexin43 expression. We could further show that cardiac fibrosis development, evaluated by collagen type I and fibronectin expression, could be inhibited by this compound. Interestingly, we further demonstrated that administration of GW788388 at the end of the acute phase (20 dpi) still significantly increased survival and decreased cardiac fibrosis (evaluated by Masson's trichrome staining and collagen type I expression), in a stage when parasite growth is no more central to this event. CONCLUSION/SIGNIFICANCE: This work confirms that inhibition of TGFß signaling pathway can be considered as a potential alternative strategy for the treatment of the symptomatic cardiomyopathy found in the acute and chronic phases of Chagas disease.

Induction of proinflammatory cytokines and nitric oxide by Trypanosoma cruzi in renal cells.

Chagas disease is typically associated with cardiac involvement. During the acute phase of murine infection with Trypanosoma cruzi, severe acute myocarditis can develop. Prior to cardiac alteration, however, infected mice present with renal inflammatory infiltration causing acute kidney injury due to an ischemia/reperfusion lesion. Thus, the present study was undertaken in order to evaluate whether the parasites or some of their components would directly affect renal cells. As such, this study employed kidney cell lines (mesangial, epithelial, and proximal tubular) that mimic different regions of the renal system. Mesangial cells are more resistant to infection, showing reduced parasite internalization relative to epithelial and proximal tubular cells. Upon infection, mesangial cells produced more nitric oxide, tumor factor necrosis-α, and interferon-γ and showed decreased viability when compared to the other cell lines. These results indicate that the resistance of mesangial cells to infection may be related to the increased expression of nitric oxide and proinflammatory cytokines. Conversely, the high levels of nitric oxide produced by these cells caused impairment of cell integrity and viability. Higher nitric oxide concentrations promote cellular injury and can be involved in the genesis of ischemia/reperfusion lesions in acute kidney injury.

Pharmacological inhibition of transforming growth factor beta signaling decreases infection and prevents heart damage in acute Chagas' disease.

Chagas' disease induced by Trypanosoma cruzi infection is an important cause of mortality and morbidity affecting the cardiovascular system for which presently available therapies are largely inadequate. We previously reported that transforming growth factor beta (TGF-beta) is implicated in several regulatory aspects of T. cruzi invasion and growth and in host tissue fibrosis. This prompted us to evaluate the therapeutic action of an inhibitor of TGF-beta signaling (SB-431542) administered during the acute phase of experimental Chagas' disease. Male Swiss mice were infected intraperitoneally with 10(4) trypomastigotes of T. cruzi (Y strain) and evaluated clinically for the following 30 days. SB-431542 treatment significantly reduced mortality and decreased parasitemia. Electrocardiography showed that SB-431542 treatment was effective in protecting the cardiac conduction system. By 14 day postinfection, enzymatic biomarkers of tissue damage indicated that muscle injury was decreased by SB-431542 treatment, with significantly lower blood levels of aspartate aminotransferase and creatine kinase. In conclusion, inhibition of TGF-beta signaling in vivo appears to potently decrease T. cruzi infection and to prevent heart damage in a preclinical mouse model. This suggests that this class of molecules may represent a new therapeutic agent for acute and chronic Chagas' disease that warrants further clinical exploration.