Evaluation of antioxidant therapy in experimental Chagas disease

Abstract INTRODUCTION: Stimulation of inflammatory mediators such as cytokines and chemokines may cause oxidative stress in Chagas disease. In this study, we evaluated the merit of vitamins C and E as antioxidant therapy to minimize the oxidative stress-induced damage in an experimental model of Chagas disease. METHODS: Ninety-six Swiss mice were infected with Trypanosoma cruzi QM2 and treated with vitamins C, E, or both (C/E) for 60 and 120 days, and their effects compared to placebo administration were evaluated in the acute and chronic disease phases. RESULTS: There was no difference in parasitemia among treatment groups. However, histological analysis showed more severe inflammation in the skeletal muscle in the vitamin supplementation groups at both the acute and chronic phases. Biochemical analyses during the acute phase showed increased ferric-reducing ability of plasma (FRAP) and glutathione (GSH) levels in the vitamin C and C/E groups. In the chronic phase, a decrease in GSH levels was observed in the vitamin E group and a decrease in thiobarbituric acid reactive substances (TBARS) was observed in the vitamin C/E group. Moreover, there was a decrease in TBARS in the cardiac tissues of the vitamin C and C/E groups compared to that of the placebo group, although this level was greater in the vitamin E group than in the vitamin C group. CONCLUSIONS: The antioxidant action of vitamins C and E reduced oxidative stress in both the acute and chronic phases of Chagas disease, with a marked effect from joint administration, indicating their inherent synergism.

Pharmacokinetic and pharmacodynamic responses in adult patients with Chagas disease treated with a new formulation of benznidazole

Pharmacological treatment of Chagas disease with benznidazole (BNZ) is effective in children in all stages, but it is controversial in chronically infected adults. We report the pharmacokinetics and pharmacodynamics in six adult patients with Chagas disease treated with the new BNZ formulation (ABARAX®) in doses between 2.5-5.5 mg/Kg/day. All but one patient had plasmatic BNZ concentrations within the expected range. All patients finalised treatment with nondetectable Trypanosoma cruziquantitative polymerase chain reaction, which remained nondetectable at the six month follow-up. Our data suggests parasitological responses with the new BNZ and supports the hypothesis that treatment protocols with lower BNZ doses may be effective.

Fibronectin modulates thymocyte-thymic epithelial cell interactions following Trypanosoma cruzi infection

Developing thymocytes interact with thymic epithelial cells (TECs) through cell-cell interactions, TEC-derived secretory moieties and extracellular matrix (ECM)-mediated interactions. These physiological interactions are crucial for normal thymocyte differentiation, but can be disrupted in pathological situations. Indeed, there is severe thymic atrophy in animals acutely infected with Trypanosoma cruzi due to CD4+CD8+ thymocyte depletion secondary to caspase-mediated apoptosis, together with changes in ECM deposition and thymocyte migration. We studied an in vitro model of TEC infection by T. cruzi and found that infected TEC cultures show a reduced number of cells, which was likely associated with decreased proliferative capacity, but not with increased cell death, as demonstrated by bromodeoxyuridine and annexin-V labelling. The infected TEC cultures exhibited increased expression of fibronectin (FN), laminin (LM) and type IV collagen. Importantly, treatment with FN increased the relative number of infected cells, whereas treatment with anti-FN or anti-LM antibodies resulted in lower infection rates. Consistent with these data, we observed increased thymocyte adhesion to infected TEC cultures. Overall, these results suggest that ECM molecules, particularly FN, facilitate infection of the thymic epithelium and that the consequent enhancement of ECM expression might be associated with changes in TEC-thymocyte interactions.

O carvedilol potencializa o efeito antioxidante das vitaminas E e C na cardiopatia chagásica crônica / Carvedilol enhances the antioxidant effect of vitamins E and C in chronic chagas heart disease

FUNDAMENTO: A doença de Chagas continua a ser uma importante doença endêmica no país, sendo o acometimento cardíaco a sua manifestação mais grave. OBJETIVO: Verificar se o uso concomitante de carvedilol potencializará o efeito antioxidante das vitaminas E e C na atenuação do estresse oxidativo sistêmico na cardiopatia chagásica crônica. MÉTODOS: Foram estudados 42 pacientes com cardiopatia chagásica, agrupados de acordo com a classificação modificada de Los Andes, em quatro grupos: 10 pacientes no grupo IA (eletrocardiograma e ecocardiograma normais: sem envolvimento do coração), 20 pacientes do grupo IB (eletrocardiograma normal e ecocardiograma anormal: ligeiro envolvimento cardíaco), oito pacientes no grupo II (eletrocardiograma e ecocardiograma anormais, sem insuficiência cardíaca: moderado envolvimento cardíaco) e quatro pacientes no grupo III (eletrocardiograma e ecocardiograma anormais com insuficiência cardíaca: grave envolvimento cardíaco). Os marcadores de estresse oxidativo foram medidos no sangue, antes e após um período de seis meses de tratamento com carvedilol e após seis meses de terapia combinada com vitaminas E e C. Os marcadores foram: atividades da superóxido dismutase, catalase, glutationa peroxidase, glutationa S-transferase e redutase, mieloperoxidase e adenosina deaminase, e os níveis de glutationa reduzida, de espécies reativas do ácido tiobarbitúrico, proteína carbonilada, vitamina E e óxido nítrico. RESULTADOS: Após o tratamento com carvedilol, todos os grupos apresentaram diminuições significativas dos níveis de proteína carbonilada e glutationa reduzida, enquanto os níveis de óxido nítrico e atividade da adenosina aumentaram significativamente apenas no grupo menos acometido (IA). Além disso, a maioria das enzimas antioxidantes mostrou atividades diminuídas nos grupos menos acometidos (IA e IB). Com a adição das vitaminas ao carvedilol houve diminuição dos danos em proteínas, nos níveis de glutationa e na maior parte da atividade das enzimas antioxidantes. CONCLUSÕES: A queda dos níveis de estresse oxidativo, verificada pelos marcadores testados, foi mais acentuada quando da associação do fármaco carvedilol com as vitaminas antioxidantes. Os dados sugerem que tanto o carvedilol isoladamente como sua associação com as vitaminas foram eficazes em atenuar o dano oxidativo sistêmico em pacientes com CC, especialmente aqueles menos acometidos, sugerindo a possibilidade de sinergismo entre esses compostos.

BACKGROUND: Chagas disease is still an important endemic disease in Brazil, and the cardiac involvement is its more severe manifestation. OBJECTIVE: To verify whether the concomitant use of carvedilol will enhance the antioxidant effect of vitamins E and C in reducing the systemic oxidative stress in chronic Chagas heart disease. METHODS: A total of 42 patients with Chagas heart disease were studied. They were divided into four groups according to the modified Los Andes classification: 10 patients in group IA (normal electrocardiogram and echocardiogram; no cardiac involvement); 20 patients in group IB (normal electrocardiogram and abnormal echocardiogram; mild cardiac involvement); eight patients in group II (abnormal electrocardiogram and echocardiogram; no heart failure; moderate cardiac involvement); and four patients in group III (abnormal electrocardiogram and echocardiogram with heart failure; severe cardiac involvement). Blood levels of markers of oxidative stress were determined before and after a six-month period of treatment with carvedilol, and six months after combined therapy of carvedilol with vitamins E and C. The markers analyzed were as follows: activities of superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase and reductase, myeloperoxidade and adenosine deaminase; and the levels of reduced glutathione, thiobarbituric-acid reactive substances, protein carbonyls, vitamin E, and nitric oxide. RESULTS: After treatment with carvedilol, all groups showed significant decrease in protein carbonyls and reduced glutathione levels, whereas nitric oxide levels and adenosine activity increased significantly only in the less severely affected group (IA). In addition, the activity of most of the antioxidant enzymes was decreased in the less severely affected groups (IA and IB). By combining the vitamins with carvedilol, a reduction in protein damage, in glutathione levels, and in the activity of most of the antioxidant enzymes were observed. CONCLUSIONS: The decrease in oxidative stress levels observed by means of the markers tested was more significant when carvedilol was used in combination with the antioxidant vitamins. The findings suggest that both carvedilol alone and in combination with the vitamins were effective in attenuating the systemic oxidative stress in patients with Chagas heart disease, especially those less severely affected, thus suggesting the possibility of synergism between these compounds.

A influência do metabolismo redox na transmissão da doença de Chagas / The influence of the redox metabolism upon the transmission of Chagas disease

As formas epimastigotas de Trypanosoma cruzi proliferam e se diferenciam no interior de diferentes compartimentos do trato digestivo dos triatomíneos. Esses ambientes antagônicos, no que diz respeito à concentração de nutrientes, pH e status redox, constituem um desafio para o protozoário por conterem moléculas e fatores capazes de deflagrar diferentes sinalizações e respostas no parasito. Por isso, testamos a influência de produtos abundantes do metabolismo do vetor e de status redox distintos, frente aos processos de proliferação e diferenciação in vivo e in vitro. Como exemplo temos o heme e a hemozoína, subprodutos da digestão da hemoglobina, e o urato, rico na urina dos insetos. O heme é uma importante molécula em todos os seres vivos. Nosso grupo mostrou seu papel na proliferação in vitro de T. cruzi e que esse sinal é governado pela enzima redox-sensível CaMKII (Lara et al., 2007; Souza et al., 2009). Esse efeito parece depender de uma sinalização redox, onde o heme e não seus análigos induz a formação de EROs, modulando a atividade da CaMKII (Nogueira et al, 2011). Apesar de gerar espécies reativas de oxigênio (EROs) em formas epimastigotas, o heme não alterou a ultraestrutura desses parasitos mostrando uma adaptação a ambientes oxidantes. Além disso, a adição de FCCP inibiu a formação de EROs mitocondrial, diminuindo a proliferação dos parasitos. Em contrapartida, a AA aumentou drasticamente a produção de EROs mitocondrial levando à morte dos epimastigotas. Estes resultados confirmam a hipótese de regulação redox do crescimento de epimastigotas...

Trypanosoma cruzi epimastigotes proliferate and differentiate inside different compartments of the triatomines gut. These environments are antagonic in terms of nutrient content, pH and redox status. All these factors represent a challenge to the protozoan due to the presence of molecules and factors which are able to induce different signals to the parasite. Thus, we tested the influence of abundant metabolism products of the vector, with distinct redox status, in the proliferation and metacyclogenesis in vitro and in vivo. These molecules are heme and hemozoin, both byproducts of hemoglobin digestion, and urate, present in the urine of insects. Heme is a ubiquitous molecule present in all living organisms. Our group studied its role in T. cruzi growth in vitro, showing that this signal is governed by the redox-sensitive enzyme CaMKII (Lara et al., 2007; Souza et al., 2009). Indeed, it seems to rely on a redox signaling pathway in which heme, but not its analogs, induces ROS formation, thus modulating CaMKII activity (Nogueira et al., 2011). Although it induces ROS in epimastigotes, the heme molecule had no deleterious effect upon the parasites ultrastructure, suggesting an adaptation to oxidative environments. In addition, FCCP inhibited mitochondrial ROS formation, then decreasing the parasite proliferation. On the other hand, AA drastically increased mitochondrial ROS production leading to cell death. These results corroborate the hypothesis of redox regulation of epimastigotes proliferation. Hemozoin (β- hematin) formation is an elegant strategy to minimize the toxic effect of heme in hematophagous insects. However, β-hematin had no influence upon the proliferation or metacyclogenesis in vitro. Also, urate, GSH and NAC impaired epimastigote proliferation. These effects were partially reversed when the antioxidants were incubated along with heme...

Aspectos nutricionais associados a infecção crônica por Trypanossoma cruzi (Chagas 1909) entre idosos: Projeto Bambuí

A doença de Chagas, ainda constitui-se como um dos principais problemas médicosociais,sendo reconhecida pela Organização Mundial da Saúde (OMS) como umadas 13 doenças tropicais mais negligenciadas do mundo e um grave problema desaúde pública na América Latina. Com o objetivo de verificar os aspectosnutricionais associados à infecção crônica pelo Trypanosoma cruzi em idososresidentes no município de Bambuí, Minas Gerais, foi realizado um estudo seccionalentre participantes do Projeto Bambuí. Os 1742 residentes na área urbana com 60ou mais anos de idade foram selecionados em 1997 para participar da linha de basedo estudo de coorte, sendo que 1606 (92,2%) foram entrevistados e 1496 (85,9%)foram examinados. Para verificar a associação entre a infecção crônica pelo T. cruzie as variáveis nutricionais, ajustadas por potenciais fatores de confusão, utilizou-se aregressão de Poisson robusta e respectivos intervalos de confiança (95%)

Foramconsideradas as seguintes variáveis antropométricas: Índice Massa Corporal (kg/m2)(IMC), Circunferência da Cintura (cm) (CC), Dobra Cutânea Tricipital (mm) (DCT),Perímetro Braço (cm) (PB), Circunferência Muscular do Braço (cm) (CMB) e ÁreaMuscular do Braço corrigida (cm2) (AMBc). As variáveis bioquímicas foram: dosagemde albumina (g/dL), nível de hemoglobina (g/dL), razão colesterol total / colesterolHDL, glicemia (mg/dL). Do total de idosos avaliados, 60,9% eram do sexo feminino,com média de idade de 69,3 anos (desvio padrão = 7,4 anos). A infecção pelo T.cruzi foi observada em 38,1% dos idosos, sendo 31,1% entre homens e 42,5% entremulheres (p<0,001). Considerando a população total, todas as variáveisantropométricas apresentaram associação significativa com a infecção pelo T. cruzi,apontando menores valores entre os infectados. Entre as variáveis bioquímicas,apenas o nível de glicemia se mostrou significativamente mais baixo entre os idososinfectados. Quando se estratificou por faixa etária, algumas diferenças foramobservadas, sendo que a DCT manteve a associação apenas entre os mais velhos,e as variáveis CMB, AMBc e glicemia apresentaram associação significativa apenasentre os idosos de 60 a 69 anos. O estudo permitiu concluir que idosos chagásicoscomparados àqueles sem a presença da infecção, apresentaram um pior estadonutricional, demonstrando um desequilíbrio nesta relação

Aspectos nutricionais associados a infecção crônica por Trypanossoma cruzi (Chagas 1909) entre idosos: Projeto Bambuí / Nutritional aspects associated with chronic infection with Trypanosoma cruzi (Chagas 1909) among the elderly: Bambuí

A doença de Chagas, ainda constitui-se como um dos principais problemas médicosociais,sendo reconhecida pela Organização Mundial da Saúde (OMS) como umadas 13 doenças tropicais mais negligenciadas do mundo e um grave problema desaúde pública na América Latina. Com o objetivo de verificar os aspectosnutricionais associados à infecção crônica pelo Trypanosoma cruzi em idososresidentes no município de Bambuí, Minas Gerais, foi realizado um estudo seccionalentre participantes do Projeto Bambuí. Os 1742 residentes na área urbana com 60ou mais anos de idade foram selecionados em 1997 para participar da linha de basedo estudo de coorte, sendo que 1606 (92,2%) foram entrevistados e 1496 (85,9%)foram examinados. Para verificar a associação entre a infecção crônica pelo T. cruzie as variáveis nutricionais, ajustadas por potenciais fatores de confusão, utilizou-se aregressão de Poisson robusta e respectivos intervalos de confiança (95%). Foramconsideradas as seguintes variáveis antropométricas: Índice Massa Corporal (kg/m2)(IMC), Circunferência da Cintura (cm) (CC), Dobra Cutânea Tricipital (mm) (DCT),Perímetro Braço (cm) (PB), Circunferência Muscular do Braço (cm) (CMB) e ÁreaMuscular do Braço corrigida (cm2) (AMBc). As variáveis bioquímicas foram: dosagemde albumina (g/dL), nível de hemoglobina (g/dL), razão colesterol total / colesterolHDL, glicemia (mg/dL). Do total de idosos avaliados, 60,9% eram do sexo feminino,com média de idade de 69,3 anos (desvio padrão = 7,4 anos). A infecção pelo T.cruzi foi observada em 38,1% dos idosos, sendo 31,1% entre homens e 42,5% entremulheres (p<0,001). Considerando a população total, todas as variáveisantropométricas apresentaram associação significativa com a infecção pelo T. cruzi,apontando menores valores entre os infectados. Entre as variáveis bioquímicas,apenas o nível de glicemia se mostrou significativamente mais baixo entre os idososinfectados. Quando se estratificou por faixa etária, algumas diferenças foramobservadas, sendo que a DCT manteve a associação apenas entre os mais velhos,e as variáveis CMB, AMBc e glicemia apresentaram associação significativa apenasentre os idosos de 60 a 69 anos. O estudo permitiu concluir que idosos chagásicoscomparados àqueles sem a presença da infecção, apresentaram um pior estadonutricional, demonstrando um desequilíbrio nesta relação.

Transmisión oral de la enfermedad de chagas: con especial referencia a la patología de los casos del año 2009 / Oral transmission of chagas disease due to oral: with special reference to the pathology of the cases from the year 2009

La transmisión oral de la enfermedad de Chagas habitual en el ciclo selvático es una forma rará en el ser humano. En este último, se debe a la contaminación de las heces con Trypanosoma cruzi (Tcruzi) en los alimentos o a la manipulación infectada de los mismos. Más raramente a la ingesta de carne de reservorios infectados. En esta comunicación, se ponen en el tapete, los trabajos experimentales y naturales del investigador Díaz-Ungría quien demostró el importante papel que juega la mosca doméstica en la contaminación de los alimentos con las heces infectadas de los vectores. Igualmente, se destaca la importancia del perro como reservorio doméstico, todos los cuales podrían ser factores determinantes en la causa de los brotes agudos presentados en los dos últimos años en nuestro país. Se exponen las características de la miocarditis aguda chagásica como la expresión más constante de la forma aguda de la enfermedad por transmisión oral. Se destacan las medidas de prevención efectuadas por las autoridades sanitarias en estas circunstancias

Oral transmission of Chagas disease is common in the forest'cycle and is a rare form in humans. In the human is due to contamination of the stool with T.cruzi in food or infected by their manipulation. More rarely due to reservoirs infected T.cruzi meat intake. In this communication we described the natural and experimental works of the Díaz-Ungría researcher who demonstrated the important role played bi the house fly in the contamination of food with vectors infected faeces. It also highlights the importance of the dog as domestic reservoir, all of which could be determining factors in the cause of acute outbreaks in the past two years in our country. The features of acute Chagasic'myocarditis are exposed as the constant expression of the acute form of the disease by oral transmission. The prevention measures carried out by the health authorities in these circunstances are high lighted

Avaliação do metabolismo dos fosfatos de alta energia em pacientes com doença de Chagas / Evaluation of the metabolism of high energy phosphates in patients with Chagas' disease

FUNDAMENTO: Anormalidades do metabolismo miocárdico têm sido observadas em pacientes com insuficiência cardíaca de diferentes etiologias. A espectroscopia por ressonância magnética (ERM) com fósforo 31 é uma técnica não invasiva que permite a detecção de alterações metabólicas miocárdicas. OBJETIVO: Determinar o metabolismo de repouso dos fosfatos de alta energia em pacientes portadores de doença de Chagas (DC) pela ERM com fósforo 31. MÉTODOS: Foram estudados 39 pacientes com DC, sendo 23 com função ventricular preservada (Grupo FP) e 16 com disfunção ventricular (Grupo DV), avaliados pela ecodopplercardiografia. A ERM da região anterosseptal foi realizada nos 39 pacientes e em 8 indivíduos normais (Grupo C), por meio de um aparelho Phillips de 1,5 Tesla, obtendo-se a relação fosfocreatina/trifosfato de adenosina beta (PCr/β-ATP) miocárdicos. RESULTADOS: Os níveis cardíacos de PCr/β-ATP estavam reduzidos no Grupo DV em relação ao Grupo FP, e estes apresentaram níveis reduzidos em relação ao Grupo C (Grupo DV: 0,89 ± 0,31 vs Grupo FP: 1,47 ± 0,34 vs Grupo C: 1,88 ± 0,08, p < 0,001). Houve correlação entre a fração de ejeção do ventrículo esquerdo e a PCr/β-ATP nos 39 pacientes estudados (r = 0,64, p < 0,001). Os pacientes em classe funcional I (n = 22) apresentaram PCr/β-ATP de 1,45 ± 0,35, e aqueles em classes funcionais II e III (n = 17), PCr/β-ATP de 0,94 ± 0,36 (p < 0,001). CONCLUSÃO: A ERM permitiu detectar de forma não invasiva alterações no metabolismo energético em pacientes com DC, mesmo sem disfunção sistólica; tais alterações estavam relacionadas com a gravidade do comprometimento cardíaco.

BACKGROUND: Abnormalities in myocardial metabolism have been observed in patients with heart failure of different etiologies. Magnetic resonance spectroscopy (MRS) with phosphorus-31 is a noninvasive technique that allows detection of myocardial metabolic changes. OBJECTIVE: To determine the resting metabolism of high-energy phosphates in patients with Chagas' disease (CD) by MRS with phosphorus-31. METHODS: We studied 39 patients with CD, 23 with preserved ventricular function (PF Group) and 16 with ventricular dysfunction (VD Group), assessed by Doppler echocardiography. MRS of the anterosseptal region was performed in 39 patients and 8 normal subjects (C Group) through a Phillips 1.5 Tesla device, obtaining the phosphocreatine/beta-adenosine triphosphate myocardial ratio (PCr/β-ATP). RESULTS: The levels of cardiac PCr/β-ATP were reduced in VD Group in relation to PF Group, and the latter presented reduced levels compared to C Group (VD Group: 0.89 ± 0.31 vs PF Group: 1.47 ± 0.34 vs C Group: 1.88 ± 0.08, p < 0.001). A correlation was found between left ventricular ejection fraction and PCr/β-ATP in 39 patients (r = 0.64, p < 0.001). Patients under functional class I (n = 22) presented PCr/β-ATP of 1.45 ± 0.35, and those in functional classes II and III (n = 17), PCr/β-ATP of 0.94 ± 0.36 (p < 0.001). CONCLUSION: The 31-phosphorus MRS was able to detect non-invasively changes in the rest energy metabolism of patients with Chagas' disease, with and without systolic dysfunction. These changes were related to the severity of heart impairment.

Mortalidad por enfermedad de chagas: a propósito de los brotes de chagas agudo como enfermedad reemergente de transmisión alimentaria

Tras la ocurrencia de los primeros brotes de Chagas agudos en la capital (diciembre 2007) y Estado Vargas (marzo 2009) por trasmisión oral, se procedió a una revisión de la mortalidad por la enfermedad registrada entre 1997 y 2006, cuyos datos se analizaron de acuerdo a la edad, sexo y forma de presentación. El número absoluto de muertes sigue siendo elevado con promedio de 796 muertes anuales, de predominio en el sexo masculino, la mayoría en después de los 60 años de edad. Llama la atención que de las 18 muertes por forma aguda 5 no afectaron al corazón, mientras en la forma crónica, apenas 10 afectan al sistema digestivo y 6 otros órganos. Durante el período analizado no se registraron muertes con afección del sistema nervioso central

After the first Chagas’ acute outbreaks occurred in Caracas (December 2007) and Vargas State (March 2009) by oral transmission, we proceeded to revise the registered mortality data due to the disease between 1997 and 2006 and to analyze them by age, sex and the form of presentation. Absolute annual number of deaths still is high with an average of 796, male predominant and occurrence after 60 years of age. We should pay attention to the fact that out of the 18 acute deaths, 5 did not affect the heart, while in the chronic form, only 10 affected the digestive system and 6 affected other organs. During the analyzed time period there were no registered deaths due to nervous system compromise

Gap junction reduction in cardiomyocytes following transforming growth factor-â treatment and Trypanosoma cruzi infection

Gap junction connexin-43 (Cx43) molecules are responsible for electrical impulse conduction in the heart and are affected by transforming growth factor-â (TGF-â). This cytokine increases during Trypanosoma cruzi infection, modulating fibrosis and the parasite cell cycle. We studied Cx43 expression in cardiomyocytes exposed or not to TGF-â T. cruzi, or SB-431542, an inhibitor of TGF-â receptor type I (ALK-5). Cx43 expression was also examined in hearts with dilated cardiopathy from chronic Chagas disease patients, in which TGF-â signalling had been shown previously to be highly activated. We demonstrated that TGF-â treatment induced disorganised gap junctions in non-infected cardiomyocytes, leading to a punctate, diffuse and non-uniform Cx43 staining. A similar pattern was detected in T. cruzi-infected cardiomyocytes concomitant with high TGF-â secretion. Both results were reversed if the cells were incubated with SB-431542. Similar tests were performed using human chronic chagasic patients and we confirmed a down-regulation of Cx43 expression, an altered distribution of plaques in the heart and a significant reduction in the number and length of Cx43 plaques, which correlated negatively with cardiomegaly. We conclude that elevated TGF-â levels during T. cruzi infection promote heart fibrosis and disorganise gap junctions, possibly contributing to abnormal impulse conduction and arrhythmia that characterise severe cardiopathy in Chagas disease.

Epidermal growth factor receptors, testosterone levels and parotid gland changes in rats infected with Trypanosoma cruzi

It has been demonstrated that parotid glands of rats infected with Trypanosoma cruzi present severe histological alterations; changes include reduction in density and volume of the acini and duct systems and an increase in connective tissue. We evaluated the association between morphological changes in parotid glands, circulating testosterone levels and epidermal growth factor receptor (EGF-R) expression in experimental Chagas disease in rats. Animals at 18 days of infection (acute phase) showed a significant decrease in body weight, serum testosterone levels and EGF-R expression in the parotid gland compared with a control group. Since decreases in body weight could lead to a reduction in circulating testosterone concentration, we believe that the reduction in EGF-R expression in parotid glands of infected rats is due to alterations in testosterone levels and atrophy of parotid glands is caused by changes in EGF-R expression. Additionally, at 50 days (chronic phase) of infection parotid glands showed a normal histological aspect likely due to the normalization of the body weight. These findings suggest that the testosterone-EGF-R axis is involved in the histological changes.

Chagas disease, adipose tissue and the metabolic syndrome

Trypanosoma cruzi infection of the adipose tissue of mice triggers the local expression of inflammatory mediators and a reduction in the expression of the adipokine adiponectin. T. cruzi can be detected in adipose tissue by PCR 300 days post-infection. Infection of cultured adipocytes results in increased expression of cytokines and chemokines and a reduction in the expression of adiponectin and the peroxisome proliferator-activated receptor ³, both of which are negative regulators of inflammation. Infection also results in the upregulation of cyclin D1, the Notch pathway, and extracellular signal-regulated kinase and a reduction in the expression of caveolin-1. Thus, T. cruzi infection of cultured adipocytes leads to an upregulation of the inflammatory process. Since adiponectin null mice have a cardiomyopathic phenotype, it is possible that the reduction in adiponectin contributes to the pathogenesis of chagasic cardiomyopathy. Adipose tissue may serve as a reservoir for T. cruzi from which parasites can become reactivated during periods of immunosuppression. T. cruzi infection of mice often results in hypoglycemia. In contrast, hyperglycemia as observed in diabetes results in increased parasitemia and mortality. Adipose tissue is an important target tissue of T. cruzi and the infection of this tissue is associated with a profound impact on systemic metabolism, increasing the risk of metabolic syndrome.

The effects of nitric oxide on the immune system during Trypanosoma cruzi infection

Trypanosoma cruzi infection triggers substantial production of nitric oxide (NO), which has been shown to have protective and toxic effects on the host's immune system. Sensing of trypomastigotes by phagocytes activates the inducible NO-synthase (NOS2) pathway, which produces NO and is largely responsible for macrophage-mediated killing of T. cruzi. NO is also responsible for modulating virtually all steps of innate and adaptive immunity. However, NO can also cause oxidative stress, which is especially damaging to the host due to increased tissue damage. The cytokines IFN-³ and TNF-±, as well as chemokines, are strong inducers of NOS2 and are produced in large amounts during T. cruzi acute infection. Conversely, TGF-² and IL-10 negatively regulate NO production. Here we discuss the recent evidence describing the mechanisms by which NO is able to exert its antimicrobial and immune regulatory effects, the mechanisms involved in the oxidative stress response during infection and the implications of NO for the development of therapeutic strategies against T. cruzi.

Contribuição para o diagnóstico da doença de chagas pelas reações de imunidade: II: Isolamento de polissacarídeos, seu comportamento nas reações de fixação do complemento e de hipersensibilidade: os testes de floculação (sublimado e formol-gel) / Contribution to the diagnosis of Chagas disease by the reactions of immunity: II: isolation of polysaccharides, their behavior in the reactions of complement fixation and hypersensitivity: the flocculation tests (and sublimated formol gel)

Revisões históricas aos avanços científicos para o controle da doença, o Simpósio Internacional Comemorativo do Centenário da Descoberta da Doença de Chagas (1909-2009).

Trypanosoma cruzi: Transporte de metabolitos esenciales obtenidos del hospedador / Trypanosoma cruzi: Transport of essential metabolites acquired from the host

El Trypanosoma cruzi es el agente causal de la enfermedad de Chagas, endémica en Argentina y en toda América Latina. Presenta numerosas características metabólicas diferenciales respecto a sus hospedadores insectos y mamíferos. Algunas de estas diferencias fueron consecuencia de millones de años de adaptación al parasitismo en los cuales estos organismos protozoarios reemplazaron, a lo largo de su evolución, muchas rutas metabólicas de biosíntesis por sistemas de transporte de metabolitos desde el hospedador. En esta revisión se describen los avances en el conocimiento de los sistemas de transporte tanto bioquímicos como también de las moléculas involucradas en dichos procesos. Se aborda con especial énfasis los transportadores de aminoácidos y poliaminas de T. cruzi de la familia AAAP (Amino Acid/Auxin Permeases) ya que parece ser exclusiva de los tripanosomátidos. Teniendo en cuenta que estas moléculas se encuentran completamente ausentes en mamíferos podrían ser consideradas como potenciales blancos contra el Trypanosoma cruzi.

Trypanosoma cruzi is the etiological agent of Chagas disease, a disease endemic not only in Argentina but also in all of Latinamerica. T. cruzi presents several metabolic characteristics which are completely absent in its insect vectors and in mammalian hosts. Some of these differences were acquired after millions of years of adaptation to parasitism, during which this protozoan replaced many biosynthetic routes for transport systems. In the present review, we describe the advances in the knowledge of T. cruzi transport processes and the molecules involved. In particular, we focus on aminoacid and polyamine transporters from the AAAP family (Amino Acid/Auxin Permeases), because they seem to be exclusive transporters from trypanosomatids. Taking into account that these permeases are completely absent in mammals, they could be considered as a potential target against Trypanosoma cruzi.

Trypanosoma cruzi infection induces up-regulation of cardiac muscarinic acetylcholine receptors in vivo and in vitro

The pathogenesis of chagasic cardiomyopathy is not completely understood, but it has been correlated with parasympathetic denervation (neurogenic theory) and inflammatory activity (immunogenic theory) that could affect heart muscarinic acetylcholine receptor (mAChR) expression. In order to further understand whether neurogenic and/or immunogenic alterations are related to changes in mAChR expression, we studied two models of Trypanosoma cruzi infection: 1) in 3-week-old male Sprague Dawley rats chronically infected with T. cruzi and 2) isolated primary cardiomyocytes co-cultured with T. cruzi and peripheral blood mononuclear cells (PBMC). Using [³H]-quinuclidinylbenzilate ([³H]-QNB) binding assays, we evaluated mAChR expression in homogenates from selected cardiac regions, PBMC, and cultured cardiomyocytes. We also determined in vitro protein expression and pro-inflammatory cytokine expression in serum and cell culture medium by ELISA. Our results showed that: 1) mAChR were significantly (P < 0.05) up-regulated in right ventricular myocardium (means ± SEM; control: 58.69 ± 5.54, N = 29; Chagas: 72.29 ± 5.79 fmol/mg, N = 34) and PBMC (control: 12.88 ± 2.45, N = 18; Chagas: 20.22 ± 1.82 fmol/mg, N = 19), as well as in cardiomyocyte transmembranes cultured with either PBMC/T. cruzi co-cultures (control: 24.33 ± 3.83; Chagas: 43.62 ± 5.08 fmol/mg, N = 7 for both) or their conditioned medium (control: 37.84 ± 3.84, N = 4; Chagas: 54.38 ± 6.28 fmol/mg, N = 20); 2) [³H]-leucine uptake was increased in cardiomyocytes co-cultured with PBMC/T. cruzi-conditioned medium (Chagas: 21,030 ± 2321; control 10,940 ± 2385 dpm, N = 7 for both; P < 0.05); 3) plasma IL-6 was increased in chagasic rats, IL-1â, was increased in both plasma of chagasic rats and in the culture medium, and TNF-á level was decreased in the culture medium. In conclusion, our results suggest that cytokines are involved in the up-regulation of mAChR in chronic Chagas disease.

Delay in maturation of the submandibular gland in Chagas disease correlates with lower DNA synthesis

It has been demonstrated that the acute phase of Trypanosoma cruzi infection promotes several changes in the oral glands. The present study examined whether T. cruzi modulates the expression of host cell apoptotic or mitotic pathway genes. Rats were infected with T. cruzi then sacrificed after 18, 32, 64 or 97 days, after which the submandibular glands were analyzed by immunohistochemistry. Immunohistochemical analyses using an anti-bromodeoxyuridine antibody showed that, during acute T. cruzi infection, DNA synthesizing cells in rat submandibular glands were lower than in non-infected animals (p < 0.05). However, after 64 days of infection (chronic phase), the number of immunolabeled cells are similar in both groups. However, immunohistochemical analysis of Fas and Bcl-2 expression did not find any difference between infected and non-infected animals in both the acute and chronic stages. These findings suggest that the delay in ductal maturation observed at the acute phase of Chagas disease is correlated with lower expression of DNA synthesis genes, but not apoptotic genes.

Participation of cytokines in the necrotic-inflammatory lesions in the heart and skeletal muscles of Calomys callosus infected with Trypanosoma cruzi

Calomys callosus, a sylvatic reservoir of Trypanosoma cruzi, when infected with the Colombian strain (Biodeme Type III, T. cruzi I ) develops necrotic-inflammatory lesions and intense early fibrogenesis in the heart and skeletal muscles, that spontaneously regress. Participation of pro-inflammatory and pro-fibrogenic cytokines, such as tumor necrosis factor-alpha (TNF-alpha), gamma interferon (IFN-gamma) , and tumor growth factor-beta (TGF-beta), in the pathogenesis of the lesions is herein studied. Eighty C. callosus weighing 20 to 30 g were used. Seventy of them were inoculated with the Colombian strain (10(5) blood forms) and 10 were maintained as intact non-infected controls. After infection, C. callosus were sacrificed at different time-points from 15 to 70 days. The heart and skeletal muscle were processed for histopathology and cryopreserved for immunohistochemistry. Early necrotic lesions of parasitized skeletal muscle and myocardium with intense inflammatory lesions were present. Search for the in situ presence of TNF-alpha and IFN-gamma, was performed using rat-IgG anti-mouse antibodies against these cytokines. For the in situ search of TGF-beta, rabbit IgG anti-mouse antibodies were used. Immunolabeling of the cytokines in tissues of infected C. callosus was successful. The cytokines TNF-alpha, IFN-gamma , and TGF-beta were detected in the cytoplasm of macrophages and in the necrotic material from 15 to 45 days post-infection, decreasing their intensity until complete disappearance by the 65th day, which correlated with subsiding histopathological lesions. These findings suggest the participation of these cytokines in the control of parasite multiplication, in the development of an early fibrogenesis and in the regression of fibrotic-inflammatory lesions observed in C. callosus.

Antígeno B13 de Trypanosama cruzi: estudo imunológico e estrutural do reconhecimento por anticorpos de pacientes chagásicos e polimorfismo do gene correspondente / Trypanosama cruzi B13 antigen: structural and immunological study of antibodies recognition of chagasics patients and correspondent gene polymorphism

A proteína recombinante B13 contém repetições seriadas de 12 aminoácidos e corresponde a uma região do antígeno imunodominante de 140-116 KDa encontrado na superfície da forma tripomastigota de T. cruzi (cepa Y). A proteína B13 apresenta elevada sensibilidade e especificidade no diagnóstico sorológico da Doença de Chagas. A análise da distribuição de subclasses de IgG anti-B13 em soros de pacientes chagásicos cardiopatas (SCC) e de assintomáticas (SCI) mostrou o mesmo padrão: IgG1¼IgG3>IgG2>IgG4. No entanto, a média da reatividade a B13 foi maior no grupo SCC do que no grupo SCI. Dados anteriores de nosso grupo indicam que a resposta de célula T a B13 é restrita ao grupo HLA de classe II...