RESUMO
The search for new compounds with trypanocidal activity is crucial for the treatment of Chagas' disease. Previous in vitro studies have shown that the diterpene 5-epi-icetexone (ICTX) is active against Trypanosoma cruzi. The aim of this work was to evaluate the effect of ICTX on the parasites in infected mice, in an experimental model that mimics the acute phase of the disease. Swiss albino mice were infected with T. cruzi and treated daily with 10mg/kg/day ICTX (i.p.). Infected mice and mice injected with either saline or the vehicle DMSO were used as controls. Animals' survival and parasitemia were monitored once a week and histological studies were made at necropsy by the 5th week after infection. It was observed that the administration of ICTX increased the survival of mice infected, and induced a significant decrease in the parasitemia, as compared to controls. A similar protective effect was observed when animals were treated orally with benznidazole (BZN, used as a control of antiparasitic effect). By the 5th week post-infection, the presence of amastigote nests was observed within the fibers of the cardiac and skeletal muscle in controls, but not in animals treated with either ICTX or BZN. In addition, inflammatory infiltrates were observed in the tissues of controls, but not in animals treated with the drugs. We conclude that ICTX has an antiparasitic effect against T. cruzi, thus constituting an interesting option for the treatment of Chagas' disease, alone or combined with other drugs.
Assuntos
Doença de Chagas/tratamento farmacológico , Diterpenos/farmacologia , Diterpenos/uso terapêutico , Salvia/química , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Administração Oral , Animais , Doença de Chagas/parasitologia , Dimetil Sulfóxido/administração & dosagem , Modelos Animais de Doenças , Diterpenos/isolamento & purificação , Coração/parasitologia , Camundongos , Músculo Esquelético/parasitologia , Músculo Esquelético/patologia , Miocárdio/patologia , Nitroimidazóis/administração & dosagem , Nitroimidazóis/uso terapêutico , Parasitemia/tratamento farmacológico , Tripanossomicidas/isolamento & purificação , Tripanossomicidas/farmacologiaRESUMO
Changes in the cardiac beta-adrenergic system in early stages of Trypanosoma cruzi infection have been described. Here, we studied an early (135 days post-infection-p.i.) and a late stage (365 days p.i.) of the cardiac chronic form of the experimental infection (Tulahuen or SGO-Z12 strains), determining plasma epinephrine and norepinephrine levels, beta-receptor density, affinity and function, cardiac cAMP concentration and phosphodiesterase activity, cardiac contractility, and the presence of beta-receptor autoantibodies. Tulahuen-infected mice presented lower epinephrine and norepinephrine levels; lower beta-receptor affinity and density; a diminished norepinephrine response and higher cAMP levels in the early stage, and a basal contractility similar to non-infected controls in the early and augmented in the late stage. The Tulahuen strain induced autoantibodies with weak beta-receptor interaction. SGO-Z12-infected mice presented lower norepinephrine levels and epinephrine levels that diminished with the evolution of the infection; lower beta-receptor affinity and an increased density; unchanged epinephrine and norepinephrine response in the early and a diminished response in the late stage; higher cAMP levels and unchanged basal contractility. The SGO-Z12 isolate induced beta-receptor autoantibodies with strong interaction with the beta-receptors. None of the antibodies, however, acted a as beta-receptor agonist. The present results demonstrate that this system is seriously compromised in the cardiac chronic stage of T. cruzi infection.
Assuntos
Cardiomiopatia Chagásica/fisiopatologia , Receptores Adrenérgicos beta/metabolismo , Trypanosoma cruzi , Agonistas Adrenérgicos beta/sangue , Agonistas Adrenérgicos beta/farmacologia , Animais , Especificidade de Anticorpos , Autoanticorpos/sangue , Autoanticorpos/imunologia , Cardiomiopatia Chagásica/sangue , Cardiomiopatia Chagásica/patologia , Doença Crônica , AMP Cíclico/metabolismo , Epinefrina/sangue , Epinefrina/farmacologia , Coração/efeitos dos fármacos , Coração/fisiopatologia , Camundongos , Contração Miocárdica/efeitos dos fármacos , Miocárdio/metabolismo , Miocárdio/patologia , Norepinefrina/sangue , Norepinefrina/farmacologia , Diester Fosfórico Hidrolases/metabolismo , Receptores Adrenérgicos beta/análiseRESUMO
The parasite Trypanosoma cruzi is the causative agent of Chagas disease. T. cruzi invasion and replication in cardiomyocytes induce cellular injuries and cytotoxic reactions, with the production of inflammatory cytokines and nitric oxide, both source of reactive oxygen species. The myocyte response to oxidative stress involves the progression of cellular changes primarily targeting mitochondria. We studied the cardiac mitochondrial structure and the enzymatic activity of citrate synthase and respiratory chain CI-CIV complexes, in Albino Swiss mice infected with T. cruzi, Tulahuen strain and SGO Z12 isolate, in two periods of the acute infection. Changes in the mitochondrial structure were detected in both infected groups, reaching values of 71% for Tulahuen and 88% for SGO Z12 infected mice, 30 days post infection. The citrate synthase activity was different according to the evolution of the infection and the parasite strain, but the respiratory chain alterations were similar with either strain.
Assuntos
Doença de Chagas/patologia , Citrato (si)-Sintase/metabolismo , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/patologia , Complexos Multienzimáticos/metabolismo , Doença Aguda , Animais , Modelos Animais de Doenças , Feminino , Masculino , Camundongos , Mitocôndrias Cardíacas/ultraestrutura , Parasitemia/patologia , Trypanosoma cruzi/classificação , Trypanosoma cruzi/patogenicidadeRESUMO
The susceptibility of Trypanosoma cruzi strains to nifurtimox and benznidazole has been investigated and resistant strains have been described. Some tricyclic drugs are lethal for trypomastigote and epimastigote forms of T. cruzi (Tulahuen strain) and prevent the disease in mice. We investigated whether clomipramine, a tricyclic antidepressant drug with anti-trypanothione reductase and anti-calmodulin effects, could be effective in treating Albino Swiss mice infected with trypomastigotes of a new T. cruzi isolate from a chronic patient from an endemic area of Argentina in two different treatment schedules. Both treatment schedules were effective in reducing electrocardiographic changes and preventing myocardial structural damage. The cardiac beta-receptors low affinity was compensated for by an increment in their density. This probably maintained cardiac function since 70% of the mice survived for more than 2 years even though anti-cruzipain titers remained high. These results demonstrate that clomipramine, clinically used as a neuroleptic, could be a promising trypanocidal agent for the treatment of Chagas' disease.
Assuntos
Doença de Chagas/tratamento farmacológico , Clomipramina/uso terapêutico , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Animais , Anticorpos Antiprotozoários/sangue , Antidepressivos Tricíclicos/farmacologia , Antidepressivos Tricíclicos/uso terapêutico , Antígenos de Protozoários/imunologia , Calmodulina/antagonistas & inibidores , Cardiomiopatia Chagásica/parasitologia , Cardiomiopatia Chagásica/prevenção & controle , Doença de Chagas/parasitologia , Doença de Chagas/patologia , Clomipramina/farmacologia , Cisteína Endopeptidases/imunologia , Resistência a Medicamentos , Eletrocardiografia , Humanos , Imunoglobulina G/sangue , Masculino , Camundongos , Miocárdio/metabolismo , Miocárdio/patologia , Parasitemia/tratamento farmacológico , Parasitemia/parasitologia , Proteínas de Protozoários , Receptores Adrenérgicos beta/efeitos dos fármacos , Receptores Adrenérgicos beta/metabolismo , Tripanossomicidas/efeitos adversos , Tripanossomicidas/farmacologia , Trypanosoma cruzi/imunologia , Trypanosoma cruzi/patogenicidadeRESUMO
BACKGROUND: Chagas' disease, which is caused by Trypanosoma cruzi, affects 20 million people. The electrocardiographic alterations are usually the first evidence of disease progression. In this work, we evaluated if two different T. cruzi strains presented electrocardiographic and heart histopathological alterations that could be characteristic and only achieved to the parasite strain. The moment when the electric alterations began was also studied. METHODS: Albino mice (n=100) were inoculated with 50 (n=50) and 500 (n=50) trypomastigotes of T. cruzi, for Tulahuen strain and SGO-Z12 isolate, respectively. Electrocardiograms were obtained before infection and once a week from 7 to 147 days post infection (d.p.i). Dipolar and unipolar leads were analyzed. Hearts were removed by necropsy on 14, 90 and 147 d.p.i. Each heart was cut horizontally into 5-mum sections and they were stained with Hematoxilin-Eosine. RESULTS: At 147 d.p.i., 30% of Tul-infected mice were found alive, while in the SGO-Z12 infected group, 75% were alive at the same moment. The Tul-infected group showed more intraventricular blockage alterations than the other groups from 49 to 70 d.p.i, (p<0.01). No structural cardiac alterations were detected in SGO-Z12-infected mice at 7 d.p.i., while the Tul-infected group showed mononuclear cell infiltrates. At 147 d.p.i., fiber disorganization and cell infiltration were observed in the SGO-Z12 and Tul-infected groups. CONCLUSIONS: We demonstrated that T. cruzi Tulahuen strain and SGO-Z12 isolate determined different electrocardiographic alterations which were characteristic for each stage of the experimental Chagas' disease. These results highlight the importance of the T. cruzi strain in the severity of the cardiopathy.
Assuntos
Cardiomiopatia Chagásica/fisiopatologia , Eletrocardiografia , Trypanosoma cruzi , Animais , Arritmias Cardíacas/etiologia , Arritmias Cardíacas/fisiopatologia , Cardiomiopatia Chagásica/complicações , Cardiomiopatia Chagásica/patologia , Modelos Animais de Doenças , Feminino , Seguimentos , Coração/parasitologia , Camundongos , Miocárdio/patologia , Fatores de Tempo , Trypanosoma cruzi/isolamento & purificação , Trypanosoma cruzi/patogenicidadeRESUMO
Trypanosoma cruzi trypanothione reductase is an enzyme that has been identified as a potential target for chemotherapy. Thioridazine inhibits it and prevented cardiopathy in mice infected with T. cruzi Tulahuen strain. As not all T. cruzi strains respond to treatment in the same way, an isolate from a chronic patient (SGO Z12) was used; parasitaemias were studied along with, survival, serology, electrocardiography, histology and cardiac beta receptor function. Parasitaemia in thioridazine (80 mg/(kg day) for 3 days) treated mice was less and lasted for a shorter period (P < 0.01), there were reduced electrocardiographic and histological alterations and significantly improved survival (80% of non-treated died). Treated mice had lower receptor affinity and higher density as a compensatory mechanism, modifying the course of T. cruzi infection (SGO Z12 isolate) and preventing the consequent cardiopathy.
Assuntos
Cardiomiopatia Chagásica/prevenção & controle , Doença de Chagas/complicações , Doença de Chagas/tratamento farmacológico , Tioridazina/farmacologia , Tioridazina/uso terapêutico , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Animais , Anticorpos Antiprotozoários/sangue , Modelos Animais de Doenças , Eletrocardiografia , Masculino , Camundongos , Miocárdio/patologia , NADH NADPH Oxirredutases/antagonistas & inibidores , NADH NADPH Oxirredutases/efeitos dos fármacos , Parasitemia , Análise de Sobrevida , Tripanossomicidas/farmacologiaRESUMO
Chagas' disease, caused by Trypanosoma cruzi, affects approximately 20 million people. There are 3 stages in the disease: acute, intermediate and chronic, the diversity and severity of the symptoms range from a mild electrocardiographic alteration to sudden death. We have previously demonstrated that when reinfections were carried out in the acute phase they produce greater cardiac damage. The aim of the present work was to investigate whether T. cruzi reinfected mice present electrocardiographic abnormalities that could be characteristic and only achieved after reinfections. Of the mice reinfected during the acute phase 100% showed abnormalities from days 90 post-infection, with a predominance of auricle ventricle blocks (67-71%). All the mice reinfected during the chronic infection showed electrocardiographic alteration after 30 days post-first reinfection. Of the mice infected, without reinfection, 60% exhibited electrocardiographic dysfunction at 90 days post-infection. Our results demonstrated that when the host was reinfected in the acute phase, more serious electrocardiographic alterations were developed than when the reinfections were carried out in the chronic stage. Sudden death described in some chagasic patients, might be related to some of the findings described here.
Assuntos
Cardiomiopatia Chagásica/fisiopatologia , Trypanosoma cruzi/crescimento & desenvolvimento , Animais , Arritmias Cardíacas/parasitologia , Arritmias Cardíacas/fisiopatologia , Cardiomiopatia Chagásica/parasitologia , Eletrocardiografia , Feminino , Camundongos , Parasitemia/parasitologia , Parasitemia/fisiopatologiaRESUMO
Chagas' disease affects about 18 million people and 25% of the population of Latin America is at risk of acquiring Chagas' disease. The chemotherapy of Chagas' disease is still an open field and remains as an unsolved problem. Nifurtimox and benznidazole are currently used to treat this disease, however, both drugs have high toxicity and are mutagenic with the result that the patients frequently fail to follow treatment. T. cruzi enzimes such as trypanothione reductase, represent potential drug targets because they play an essential role in the life of this organism. This enzyme has been isolated, purified and studied by X ray crystallography. Phenothiazines and related compounds inhibit trypanothione reductase and a specially favoured fit is a phenothiazine with a 2- substitued with 2- chloro and 2- trifluoromethyl with a remote hydrophobic patch. The essential phenothiazine nucleus can adopt more than one inhibitory orientation in its binding site. Phenothiazines and related compounds are drugs used in psychiatric treatments. These anti-depressants inhibit trypanothione reductase through the peroxidase/ H2O2/ system, and also exert other trypanocidal effects upon epimastigotes and tripomastigotes forms: clomipramine through an anticalmodulin action; trifluopherazine and thioridazine induced disruption of mitochondria and prometazine provoked serious cell membrane disorganization. Clomipramine and thioridazine were also effective in treatment of mice with experimental Chagas' disease, significantly modifying the natural evolution of the infection; cardiac function and survival of infected and treated animals were not different from non infected animals. Phenothiazines and related compounds are promising trypanocidal agents for treatment of Chagas' disease. Other trypanocidal agents as nifurtimox, benznidazol,Allopurinol, cystein protease inhibitors and others, are also discussed.
Assuntos
Antiprotozoários/uso terapêutico , Doença de Chagas/tratamento farmacológico , Inibidores Enzimáticos/uso terapêutico , NADH NADPH Oxirredutases/antagonistas & inibidores , Fenotiazinas/uso terapêutico , Trypanosoma cruzi/enzimologia , Animais , Antiprotozoários/farmacologia , Doença de Chagas/enzimologia , Inibidores Enzimáticos/farmacologia , Humanos , NADH NADPH Oxirredutases/metabolismo , Fenotiazinas/farmacologia , Trypanosoma cruzi/efeitos dos fármacosRESUMO
Trypanosoma cruzi, widely distributed in Latin American countries, provokes Chagas disease, characterized by cardiomyopathy and mega-viscera. The drugs used currently for treatment of acute Chagas disease are highly toxic; the side-effects are undesirable and patients may abandon treatment. We have previously demonstrated that clomipramine (CLO) exerts trypanocidal effects upon epimastigotes and trypomastigotes in vitro with anticalmodulin activity. The present study analyses the effectiveness of CLO treatment in mice infected with a low number of T. cruzi, an animal model that reproduces acute, indeterminate and chronic phases of this trypanosomiasis. In this work, our results demonstrated that CLO 5 mg/kg daily for 30 days, or 2 doses of CLO 40 mg/kg given intraperitoneally at 1 h and 7 days after infection, was not toxic for the host, but was effective against the parasite in that parasitaemias became negative and only mild heart structural and electrocardiographic alterations were detected in the chronic phase in the group treated with CLO 5 mg/kg. In mice treated with CLO 40 mg/kg, none of these alterations was detected. Cardiac beta receptor density and affinity returned to normal in the chronic stage in both experimental groups. T. cruzi enzymes such as calmodulin and trypanothione reductase represent potential drug targets. It has been reported that both can be inhibited by CLO, a tricyclic drug used in clinical therapeutics. We have shown that CLO strongly decreased the mortality rate and electrocardiographic alterations; in addition cardiac beta receptor density and heart histology returned to, or close to, normality 135 days post infection. These results clearly demonstrated that CLO treatment modified significantly the natural evolution of T. cruzi infection.
Assuntos
Antidepressivos Tricíclicos/uso terapêutico , Cardiomiopatia Chagásica/tratamento farmacológico , Clomipramina/uso terapêutico , Animais , Avaliação Pré-Clínica de Medicamentos , Eletrocardiografia , Camundongos , Receptores Adrenérgicos beta/metabolismo , Análise de Sobrevida , Trypanosoma cruziRESUMO
Human and murine infection with Trypanosoma cruzi parasite is usually accompanied by strong humoral and cellular immune response to cruzipain, a parasite immunodominant antigen. In the present study we report that the immunization of mice with cruzipain devoid of enzymatic activity, was able to induce antibodies which bind to a 223-kDa antigen from a mouse heart extract. We identified this protein as the mouse cardiac myosin heavy chain by sequencing analysis. The study of IgG isotype profile revealed the occurrence of all IgG isotypes against cruzipain and myosin. IgG1 showed the strongest reactivity against cruzipain, whereas IgG2a was the main isotype against myosin. Anti-cruzipain antibodies purified by immunoabsorption recognized the cardiac myosin heavy chain, suggesting cross-reactive epitopes between cruzipain and myosin. Autoimmune response in mice immunized with cruzipain was associated to heart conduction disturbances. In addition, ultrastructural findings revealed severe alterations of cardiomyocytes and IgG deposit on heart tissue of immunized mice. We investigated whether antibodies induced by cruzipain transferred from immunized mothers to their offsprings could alter the heart function in the pups. All IgG isotypes against cruzipain derived from transplacental crossing were detected in pups' sera. Electrocardiographic studies performed in the offsprings born to immunized mothers revealed conduction abnormalities. These results provide strong evidence for a pathogenic role of autoimmune response induced by a purified T. cruzi antigen in the development of experimental Chagas' disease.