RESUMO
(â¢)NO is considered to be a key macrophage-derived cytotoxic effector during Trypanosoma cruzi infection. On the other hand, the microbicidal properties of reactive oxygen species (ROS) are well recognized, but little importance has been attributed to them during in vivo infection with T. cruzi. In order to investigate the role of ROS in T. cruzi infection, mice deficient in NADPH phagocyte oxidase (gp91(phox) (-/-) or phox KO) were infected with Y strain of T. cruzi and the course of infection was followed. phox KO mice had similar parasitemia, similar tissue parasitism and similar levels of IFN-γ and TNF in serum and spleen cell culture supernatants, when compared to wild-type controls. However, all phox KO mice succumbed to infection between day 15 and 21 after inoculation with the parasite, while 60% of wild-type mice were alive 50 days after infection. Further investigation demonstrated increased serum levels of nitrite and nitrate (NOx) at day 15 of infection in phox KO animals, associated with a drop in blood pressure. Treatment with a NOS2 inhibitor corrected the blood pressure, implicating NOS2 in this phenomenon. We postulate that superoxide reacts with (â¢)NO in vivo, preventing blood pressure drops in wild type mice. Hence, whilst superoxide from phagocytes did not play a critical role in parasite control in the phox KO animals, its production would have an important protective effect against blood pressure decline during infection with T. cruzi.
Assuntos
Doença de Chagas/imunologia , Glicoproteínas de Membrana/deficiência , Glicoproteínas de Membrana/imunologia , NADPH Oxidases/deficiência , NADPH Oxidases/imunologia , Fagócitos/enzimologia , Fagócitos/imunologia , Choque , Trypanosoma cruzi/imunologia , Animais , Células Cultivadas , Doença de Chagas/mortalidade , Modelos Animais de Doenças , Feminino , Interferon gama/sangue , Interferon gama/metabolismo , Leucócitos Mononucleares/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , NADPH Oxidase 2 , Parasitemia/imunologia , Baço/imunologia , Análise de Sobrevida , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/metabolismoRESUMO
The phytochemical investigation on the aereal parts of Lychnophora pinaster Mart., Asteraceae, was carried to isolation of triterpenes. 3-O-Acetyl-lupeol (1), 3-O-acetyl-pseudotaraxasterol (2), and 3-O-acetyl-α-amyrin (3) were isolated from hexanic extract and 4,4-dimethyl-cholesta-22,24-dien-5-ol (4), α-amyrin (5), and lupeol (6) were isolated from hexanic/dichlorometanic extract of the leaves. Compounds Δ7-bauerenyl acetate (7), friedelin (8), stigmasterol (9), and sitosterol (10) were isolated from the hexanic/dichlorometanic extract of the stems. The steroids 9 and 10 were also isolated from the hexanic/dichlorometanic extract of the flowers. Triterpenes 1, 3, 4, and 7 are described for the first time in the genus Lychnophora. The apolar fractions of the leaf and stem extracts and some isolated triterpenes showed low trypanocidal activity. Moreover, apolar fractions of the leaf and stem extracts and 5 showed antibacterial action against Staphylococcus aureus.
RESUMO
We investigated the influence of CD4(+) T lymphocytes, CD8(+) T lymphocytes, and B lymphocytes on the efficacy of posaconazole (POS) and the reference drug benznidazole (BZ) during treatment of acute Trypanosoma cruzi infection in a murine model. Wild-type mice infected with T. cruzi and treated with POS or BZ presented no parasitemia, 100% survival, and 86 to 89% cure rates, defined as the percentages of animals with negative hemocultures at the end of the observation period. CD4(+)-T-lymphocyte-knockout (KO) mice infected with T. cruzi and treated with BZ or POS controlled parasitemia during treatment, although circulating parasites reappeared after drug pressure cessation, leading to only a 6% survival rate and no cure. CD8(+)-T-lymphocyte-KO mice infected with T. cruzi and treated with POS or BZ had intermediate results, displaying discrete parasitemia after the treatment was ended, 81 and 86% survival, and cure rates of 31 and 66%, respectively. B-lymphocyte-KO mice infected with T. cruzi and treated with BZ relapsed with parasitemia 1 week after the end of treatment and had a 67% survival rate and only a 22% cure rate. In contrast, the activity of POS was much less affected in these animals, with permanent suppression of parasitemia, 100% survival, and a 71% cure rate. Our results demonstrate that abrogation of different lymphocytes' activities has distinct effects on the efficacy of POS and BZ in this experimental model, probably reflecting different parasite stages preferentially targeted by the two drugs and distinct cooperation patterns with the host immune system.
Assuntos
Linfócitos B/fisiologia , Linfócitos T CD4-Positivos/fisiologia , Linfócitos T CD8-Positivos/fisiologia , Doença de Chagas/tratamento farmacológico , Nitroimidazóis/uso terapêutico , Triazóis/uso terapêutico , Animais , Linfócitos B/imunologia , Linfócitos B/metabolismo , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Doença de Chagas/genética , Doença de Chagas/imunologia , Masculino , Camundongos , Camundongos Knockout , Tripanossomicidas/uso terapêutico , Trypanosoma cruziRESUMO
We have investigated the influences of gamma interferon (IFN-gamma) and interleukin-12 (IL-12) on the efficacy of posaconazole (POS) treatment of acute experimental infections with Trypanosoma cruzi; the standard drug, benznidazole (BZ), was used as a positive control. Wild-type (WT) mice infected with T. cruzi and treated with POS or BZ had no parasitemia, 100% survival, and cure rates of 86 to 89%. IFN-gamma-knockout (KO) mice infected with T. cruzi and treated with BZ controlled the infection during treatment but relapsed after the drug pressure ceased and had 0% survival, while those receiving POS better controlled the infection after the end of treatment and had 70% survival (P<0.0001 compared to the results for both untreated and BZ-treated animals). IL-12-KO mice infected and treated with POS or BZ had intermediate results, displaying enhanced parasitemia, decreased survival (77 to 83%), and reduced cure rates (35 to 39%) compared with those of the WT animals. Our results demonstrate that either IFN-gamma or IL-12 deficiency reduces the efficacy of POS or BZ in this experimental model but also indicate that the anti-T. cruzi activity of POS is much less dependent on the activity of IFN-gamma than that of BZ is.
Assuntos
Doença de Chagas/tratamento farmacológico , Interferon gama/uso terapêutico , Nitroimidazóis/uso terapêutico , Triazóis/uso terapêutico , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Animais , Interferon gama/farmacologia , Interleucina-12/biossíntese , Interleucina-12/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Nitroimidazóis/farmacologia , Triazóis/farmacologiaRESUMO
The natural lignans veraguensin and grandisin have been reported to be active against Trypanosoma cruzi bloodstream forms. Aiming at the total synthesis of these and related compounds, we prepared three 2-arylfurans and eight 2,5-diarylfurans. They were evaluated for their potential as T. cruzi trypanothione reductase (TR) inhibitors as well against the parasite's intracellular (amastigote) and bloodstream (trypomastigote) forms. Compound 12 was the most effective against TR with an IC50 of 48.5 microM while 7 and 14 were active against amastigotes, inhibiting the parasite development by 60% at 20 microg/ml (59 and 90 microM, respectively). On the other hand, none of the compounds was significantly active against the parasite bloodstream forms even at 250 microg/ml (0.6-1.5 mM).
Assuntos
Inibidores Enzimáticos/farmacologia , Furanos/farmacologia , NADH NADPH Oxirredutases/antagonistas & inibidores , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Inibidores Enzimáticos/química , Furanos/química , Concentração Inibidora 50 , Masculino , Camundongos , Relação Estrutura-AtividadeRESUMO
The natural lignans veraguensin and grandisin have been reported to be active against Trypanosoma cruzi bloodstream forms. Aiming at the total synthesis of these and related compounds, we prepared three 2-arylfurans and eight 2,5-diarylfurans. They were evaluated for their potential as T. cruzi trypanothione reductase (TR) inhibitors as well against the parasite's intracellular (amastigote) and bloodstream (trypomastigote) forms. Compound 12 was the most effective against TR with an IC50 of 48.5 æM while 7 and 14 were active against amastigotes, inhibiting the parasite development by 60 percent at 20 æg/ml (59 and 90 æM, respectively). On the other hand, none of the compounds was significantly active against the parasite bloodstream forms even at 250 æg/ml (0.6-1.5 mM).
Assuntos
Animais , Masculino , Camundongos , Furanos/farmacologia , Inibidores Enzimáticos/farmacologia , NADH NADPH Oxirredutases/antagonistas & inibidores , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Furanos/química , Inibidores Enzimáticos/química , Relação Estrutura-AtividadeRESUMO
Fourteen compounds were evaluated for their activity against Trypanosoma cruzi blood stream forms at the concentration of 500 g/ml. Six compounds were active and re-tested at lower concentrations.
Assuntos
Nitrocompostos/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Avaliação Pré-Clínica de Medicamentos , Concentração Inibidora 50 , Camundongos , Nitrocompostos/químicaRESUMO
Fourteen compounds were evaluated for their activity against Trypanosoma cruzi blood stream forms at the concentration of 500 æg/ml. Six compounds were active and re-tested at lower concentrations
Assuntos
Animais , Camundongos , Nitrocompostos , Trypanosoma cruzi , Avaliação Pré-Clínica de Medicamentos , Concentração Inibidora 50 , NitrocompostosRESUMO
Studies in humans and in experimental models suggest the involvement of the immune system for efficacy of drug treatment against protozoan parasites. This study tested this hypothesis by using various cytokine and inducible nitric oxide synthase (iNOS) knockout (KO) mice infected with Trypanosoma cruzi and treated with benznidazole. In contrast with the 100% parasitologic cure rate achieved in wild-type animals, benznidazole failed to cure 100%, 42%, 35%, and 28% of interferon-gamma, interleukin-12 (protein 40), protein 55-tumor necrosis factor receptor, and iNOS KO mice, respectively. These results suggest that activation of the immune system by the parasite and endogenous interferon-gamma play a major role in the efficacy of benznidazole against infection with T. cruzi.