Analysis of Iron Metabolism in Chronic Chagasic Cardiomyopathy / Análise do Metabolismo do Ferro na Cardiomiopatia Chagásica Crônica

Abstract Changes in iron metabolism in heart failure (HF) have been described as an important prognostic marker. To check if the markers of iron kinetics are related to the morbidity and etiology of chagasic cardiomyopathy. Patients with Chronic Chagasic Cardiomyopathy (CCC, n = 40), with indeterminate form (IND, n = 40), besides non-chagasic cardiomyopathy (NCh, n = 40). The mean age was 50.98 ± 5.88 in CCC, 50% were male, 49.68 ± 5.28 in IND, 52.2% were male, and 49.20 ± 10.09 in NCh, 12.5% were male. Lower levels of iron (FeSe) were observed in the CCC groups (93.15 ± 36.53), when compared to IND (125.30 ± 22.79) and NCh (114.77 ± 18.90) (p = 0.0004), lower IST transferrin saturation index in CCC (29.48 ± 6.59), when compared to IND (30.95 ± 7.06) and in the NCh group (39.70 ± 7.54) p = 0.0001), total binding capacity of the lower CTLF iron in the CCC group (297.30 ± 36.46), when compared to the IND group (196.52 ± 56.95) and the NCh group (275.18 ± 33, 48) (p = 0.0001), lower ferritin in the CCC group (134.55, 1.56-42.36), when compared to the IND group (156,25, 1,72-42,20) and the NCh group (112.95, 2.88-42.66) (p = 0.0004). It was also observed that FeSe (95% CI 1.00-1.04, p = 0.0014), IST (95% CI 1.02-1.22) (p = 0.0012) and gender (95% CI 1.07-14.43 p = 0.0038) were independently associated with the degree of ventricular dysfunction in chagasic cardiomyopathy. CCC patients showed greater change in iron metabolism regarding the indeterminate form and other forms of cariomyopathies.

Resumo A alteração do metabolismo do ferro na insuficiência cardíaca (IC) tem sido descrita como um importante marcador prognóstico. Verificar se os marcadores da cinética do ferro guardam relação com a morbidade e a etiologia da cardiomiopatia chagásica. Pacientes com cardiomiopatia chagásica crônica (CCC, n = 40), com a forma indeterminada (IND, n = 40), além de cardiomiopatia não chagásica (NCh, n = 40). A idade média foi de 50,98 ± 5,88 no CCC, 50% eram do sexo masculino, 49,68 ± 5,28 no IND, 52,2% eram do sexo masculino e 49,20 ±10,09 no NCh, 12,5% eram do sexo masculino. Observaram-se níveis de ferro (FeSe) menores no grupos CCC (93,15 ± 36,53), quando comparados ao IND (125,30 ± 22,79) e NCh (114,77 ± 18,90) (p = 0,0004), índice de saturação de transferrina (IST) menor no CCC (29,48 ± 6,59), quando comparado ao IND (30,95 ± 7,06) e no grupo NCh (39,70 ± 7,54) (p= 0,0001), capacidade total de ligação do ferro CTLF menor no grupo CCC (297,30 ± 36,46), quando comparado ao grupo IND (196,52 ± 56,95) e ao grupo NCh (275,18 ± 33,48) (p = 0,0001), ferritina menor no grupo CCC (134,55, 1,56-42,36), quando comparada ao grupo IND (156,25, 1,72 - 42,20) e ao grupo NCh (112,95, 2,88-42,66) (p = 0.0004). Verificou-se também que o FeSe (IC% 95% 1,00-1,04; p = 0,0014), o IST (IC 95% 1,02-1,22) (p = 0,0012) e o sexo (IC 95% 1,07-14,43 p = 0,0038) associaram-se independentemente ao grau de disfunção ventricular na cardiomiopatia chagásica. Os pacientes com CCC demonstraram maior alteração no metabolismo do ferro em relação a forma indeterminada e outras formas de miocardiopatias.

Trypanosoma cruzi down-regulates mechanosensitive proteins in cardiomyocytes

BACKGROUND Cardiac physiology depends on coupling and electrical and mechanical coordination through the intercalated disc. Focal adhesions offer mechanical support and signal transduction events during heart contraction-relaxation processes. Talin links integrins to the actin cytoskeleton and serves as a scaffold for the recruitment of other proteins, such as paxillin in focal adhesion formation and regulation. Chagasic cardiomyopathy is caused by infection by Trypanosoma cruzi and is a debilitating condition comprising extensive fibrosis, inflammation, cardiac hypertrophy and electrical alterations that culminate in heart failure. OBJECTIVES Since mechanotransduction coordinates heart function, we evaluated the underlying mechanism implicated in the mechanical changes, focusing especially in mechanosensitive proteins and related signalling pathways during infection of cardiac cells by T. cruzi. METHODS We investigated the effect of T. cruzi infection on the expression and distribution of talin/paxillin and associated proteins in mouse cardiomyocytes in vitro by western blotting, immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR). FINDINGS Talin and paxillin spatial distribution in T. cruzi-infected cardiomyocytes in vitro were altered associated with a downregulation of these proteins and mRNAs levels at 72 h post-infection (hpi). Additionally, we observed an increase in the activation of the focal adhesion kinase (FAK) concomitant with increase in β-1-integrin at 24 hpi. Finally, we detected a decrease in the activation of FAK at 72 hpi in T. cruzi-infected cultures. MAIN CONCLUSION The results suggest that these changes may contribute to the mechanotransduction disturbance evidenced in chagasic cardiomyopathy.

Metabolismo do ferro na cardiomiopatia chagásica crônica: [Carta ao Editor] / Iron metabolism in chronic Chagas cardiomyopathy: [Letter to Editor]

É notória uma intensa resposta inflamatória em indivíduos infectados com adoença de Chagas (Trypanosoma cruzi), enfermidade crônica degenerativa na qual estão envolvidos eventos inflamatórios que atingem um dos principais órgãos-alvo, o coração, com demonstrados efeitos colaterais cardiometabólicos.1 De fato, segundo relatos de Pinto2 e confirmado em estudos, a deficiência de ferro potencializa o processo infeccioso, levando a acentuada piora no prognóstico dos pacientescom essa enfermidade.3 Análise feita em pacientes com insuficiência cardíaca revela alterações no metabolismo do ferro, sendo este fato intrínseco ao mecanismo patofisiológico da insuficiência cardíaca.4 O complexo questionamento paradoxal de um estudo de revisão Pinto2, chama a atenção e leva a hipóteses levantadas em outros estudos, em que a infecção pelo T. Cruzi ativa uma cascata imunológica. Nesse contexto, há um hormônio chamado hepcidina, que é estimulado por célulasespecíficas do sistema imunológico, tendo, portanto, participação nos mecanismos reguladores do metabolismo do ferro5. Diante disso, o paralelo entre o metabolismo do ferro descrito durante a resposta inflamatória perpassa pelo eixo hepcidina-IL-6 (citocina pró-inflamatória).

Carvedilol atenua o estresse oxidativo na cardiopatia chagásica crônica / Carvedilol attenuates oxidative stress in chronic chagasic cardiomyopathy / Carvedilol atenúa el estrés oxidativo en la cardiopatía chagásica crónica

FUNDAMENTO: Há cada vez mais evidências sugerindo que doença de Chagas envolve dano oxidativo e contribui para a progressão da doença cardíaca. OBJETIVO: Avaliar o efeito do carvedilol sobre marcadores de estresse oxidativo na doença de Chagas crônica. MÉTODOS: A população de estudo incluiu 42 pacientes com cardiopatia chagásica e os biomarcadores de estresse oxidativo foram medidos antes e após um período de seis meses de tratamento com carvedilol (37,5 mg/dia). Os pacientes foram considerados de acordo com a classificação de Los Andes, e a atividade da superóxido dismutase, catalase, glutationa peroxidase, S-transferase e redutase, mieloperoxidase e adenosina deaminase; e os níveis de glutationa reduzida, de espécies reativas do ácido tiobarbitúrico, proteína carbonil, vitamina E e óxido nítrico foram medidos no sangue. RESULTADOS: Após o tratamento com carvedilol, todos os grupos apresentaram reduções significativas nos níveis de proteína carbonil e glutationa reduzida, enquanto os níveis de óxido nítrico e atividade da adenosina aumentaram significativamente somente no grupo IA. Além disso, a maioria das enzimas antioxidantes apresentou diminuição de suas atividades, nos grupos IA e IB. CONCLUSÃO: Os dados sugerem que o tratamento com carvedilol foi eficaz na atenuação do dano oxidativo, um efeito que pode ser particularmente importante em doença de Chagas crônica com cardiopatia.

BACKGROUND: There is increasing evidence suggesting that Chagas disease involves oxidative damage and contributes to heart disease progression. OBJECTIVE: To evaluate the effect of carvedilol on oxidative stress markers in chronic Chagas disease. METHODS: The study population included 42 patients with Chagas cardiomyopathy and oxidative stress biomarkers were measured before and after a period of six months of treatment with carvedilol (37.5 mg/day). Patients were considered according to the Los Andes classification and the activity of superoxide dismutase, catalase, glutathione peroxidase, S-transferase and reductase, myeloperoxidase and adenosine deaminase; levels of reduced glutathione, thiobarbituric acid reactive species, carbonyl protein, vitamin E and nitric oxide were measured in blood. RESULTS: After treatment with carvedilol, all groups showed significant reductions in levels of carbonyl protein and reduced glutathione, whereas the levels of nitric oxide and adenosine activity increased significantly only in group IA. Moreover, most of the antioxidant enzymes showed decrease in activity in groups IA and IB. CONCLUSION: The data suggest that treatment with carvedilol was effective in attenuating oxidative damage, an effect that may be particularly important in patients with chronic Chagas' disease cardiomyopathy.

FUNDAMENTO: Hay cada vez más evidencias sugiriendo que la enfermedad de Chagas envuelve daño oxidativo y contribuye a la progresión de la enfermedad cardíaca. OBJETIVO: Evaluar el efecto del carvedilol sobre marcadores de estrés oxidativo en la enfermedad de Chagas crónica. MÉTODOS: La población de estudio incluyó 42 pacientes con cardiopatía chagásica y los biomarcadores de estrés oxidativo fueron medidos antes y después de un período de seis meses de tratamiento con carvedilol (37,5 mg/día). Los pacientes fueron considerados de acuerdo con la clasificación de Los Andes, y la actividad de la superóxido dismutasa, catalasa, glutatión peroxidasa, S-transferasa y reductasa, mieloperoxidasa y adenosina deaminasa; y los niveles de glutatión reducida, de especies reactivas del ácido tiobarbitúrico, proteína carbonil, vitamina E y óxido nítrico fueron medidos en la sangre. RESULTADOS: Después del tratamiento con carvedilol, todos los grupos presentaron reducciones significativas en los niveles de proteína carbonil y glutatión reducida, mientras que los niveles de óxido nítrico y actividad de la adenosina aumentaron significativamente solamente en el grupo IA. Además de eso, la mayoría de las enzimas antioxidantes presentó disminución de sus actividades, en los grupos IA e IB. CONCLUSIONES: Los datos sugieren que el tratamiento con carvedilol fue eficaz en la atenuación del daño oxidativo, un efecto que puede ser particularmente importante en enfermedad de Chagas crónica con cardiopatía.

Pressão arterial, respostas metabólicas e autonômicas à insulina e infusão de intralipid® em pacientes chagásicos / Blood pressure, metabolic and autonomic responses to insulin and intralipid® infusion in chagasic patients / Presión arterial, respuestas metabólicas y autonómicas a la insulina e infusión de intralipid® en pacientes chagásicos

FUNDAMENTO: Infusão de intralipid e heparina resulta em aumento da pressão arterial e também em anormalidades autonômicas em indivíduos normais e hipertensos. OBJETIVO: Avaliar a sensibilidade a insulina e o impacto da infusão de intralipid e de heparina (ILH) sobre a resposta hemodinâmica, metabólica e autonômica em pacientes com a forma indeterminada da doença de Chagas. MÉTODOS: Doze pacientes com a forma indeterminada da doença de Chagas e 12 voluntários saudáveis foram avaliados. RESULTADOS: A pressão arterial basal e a frequência cardíaca foram semelhantes nos dois grupos. Os níveis plasmáticos de noradrenalina encontravam-se ligeiramente aumentados no grupo de pacientes chagásicos. Após o Teste de Tolerância a Insulina (TTI), houve um declínio significativo na glicose dos dois grupos. A Infusão de ILH resultou em aumento da pressão arterial em ambos os grupos, mas não houve nenhuma mudança significativa na noradrenalina plasmática. O componente de Baixa Frequência (BF) mostrou-se semelhante e aumentou de forma semelhante em ambos os grupos. O componente de Alta Frequência (AF) apresentou-se menor no grupo chagásico. CONCLUSÃO: Pacientes com forma indeterminada da doença de Chagas apresentaram aumento da atividade simpática no momento basal e uma resposta inadequada à insulina. Eles também tiveram um menor componente de alta frequência e sensibilidade barorreflexa prejudicada no momento basal e durante a infusão de intralipid e heparina.

BACKGROUND: Intralipid and heparin infusion results in increased blood pressure and autonomic abnormalities in normal and hypertensive individuals. OBJECTIVE: To evaluate insulin sensitivity and the impact of Intralipid and heparin (ILH) infusion on hemodynamic, metabolic, and autonomic response in patients with the indeterminate form of Chagas' disease. METHODS: Twelve patients with the indeterminate form of Chagas' disease and 12 healthy volunteers were evaluated. RESULTS: Baseline blood pressure and heart rate were similar in both groups. Plasma noradrenaline levels were slightly increased in the Chagas' group. After insulin tolerance testing (ITT), a significant decline was noted in glucose in both groups. ILH infusion resulted in increased blood pressure in both groups, but there was no significant change in plasma noradrenaline. The low-frequency component (LF) was similar and similarly increased in both groups. The high-frequency component (HF) was lower in the Chagas' group. CONCLUSION: Patients with the indeterminate form of Chagas' disease had increased sympathetic activity at baseline and impaired response to insulin. They also had a lower high-frequency component and impaired baroreflex sensitivity at baseline and during Intralipid and heparin infusion.

FUNDAMENTO: La Infusión de intralipid® y de heparina trae como resultado un aumento de la presión arterial y también de las anormalidades autonómicas en los individuos normales e hipertensos. OBJETIVO: Evaluar la sensibilidad a la insulina y el impacto de la infusión de intralipid® y de heparina (ILH) sobre la respuesta hemodinámica, metabólica y autonómica en pacientes con la forma indefinida de la Enfermedad de Chagas. MÉTODOS: Fueron evaluados doce pacientes con la forma indefinida de la Enfermedad de Chagas y 12 voluntarios sanos. RESULTADOS: La presión arterial basal y la frecuencia cardíaca fueron similares en los dos grupos. Los niveles plasmáticos de noradrenalina estaban ligeramente más elevados en el grupo de pacientes chagásicos. Después del Test de Tolerancia a la Insulina (TTI), se produjo una ostensible disminución en la glucosa de los dos grupos. La Infusión de ILH trajo como consecuencia el aumento de la presión arterial en ambos grupos, pero no hubo ningún cambio significativo en la noradrenalina plasmática. El componente de Baja Frecuencia (BF), fue similar y aumentó de forma parecida en ambos grupos. El componente de Alta Frecuencia (AF) se presentó con un menor nivel en el grupo chagásico. CONCLUSIONES: Los pacientes con una forma indeterminada de la Enfermedad de Chagas, presentaron un aumento en la actividad simpática al momento basal y una respuesta inadecuada a la insulina. También tuvieron un menor componente de alta frecuencia y de sensibilidad barorrefleja, que fue perjudicado en el momento basal y durante la infusión de intralipid® y heparina.

Ativação adrenérgica intramiocárdica na cardiomiopatia chagásica e doença arterial coronariana / Intramyocardial adrenergic activation in chagasic cardiomyopathy and coronary artery disease / Activación adrenérgica intramiocárdica en la cardiomiopatía chagásica y enfermedad arterial coronaria

FUNDAMENTO: A norepinefrina miocárdica está alterada na disfunção ventricular esquerda. Em pacientes com cardiomiopatia chagásica (CC), essa questão ainda não foi discutida. OBJETIVO: Determinar o nível de norepinefrina (NE) miocárdica em pacientes com CC e compará-la em pacientes com doença arterial coronariana (DAC) e relacionar NE miocárdica com a fração de ejeção do ventrículo esquerdo (FEVE). MÉTODOS: Estudamos 39 pacientes com CC, divididos em grupo 1: 21 indivíduos com FEVE normal e grupo 2: 18 com FEVE diminuída. Dezessete pacientes com DAC foram divididos em grupo 3: 12 indivíduos com FEVE normal e grupo 4: 5 indivíduos com FEVE diminuída. Ecocardiografia bidimensional foi usada para medir a FEVE. A NE miocárdica foi determinada através de Cromatografia Líquida de Alta Eficiência (HPLC). RESULTADOS: A NE miocárdica na CC com e sem disfunção ventricular foi 1,3±1,3 e 6,1±4,2 pg/μg de proteína não-colagenosa, respectivamente (p<0,0001); na DAC com e sem disfunção ventricular, foi 3,3±3,0 e 9,8±4,2 pg/μg de proteína não-colagenosa, respectivamente (p<0,0001). Uma correlação positive foi observada entre a FEVE e a concentração de NE miocárdica em pacientes com CC (p<0,01; r = 0,57) e também naqueles com DAC (p<0,01; r=0,69). Uma diferença significante foi demonstrada entre as concentrações de NE em pacientes com FEVE normal (grupos 1 e 3; p = 0,0182), mas nenhuma diferença foi observada em pacientes com FEVE diminuída (grupos 2 e 4; p = 0,1467). CONCLUSÃO: Pacientes com CC e fração de ejeção global normal apresentam uma denervação cardíaca precoce, quando comparados à pacientes com doença arterial coronariana.

BACKGROUND: Myocardial norepinephrine is altered in left ventricular impairment. In patients with Chagas' cardiomyopathy (CC), this issue has not been addressed. OBJECTIVE: To determine the level of myocardial norepinephrine in patients with CC and compare it in patients with coronary artery disease, and to relate myocardial norepinephrine to left ventricular ejection fraction (LVEF). METHODS: We studied 39 patients with CC, divided into group 1: 21 individuals with normal LVEF and group 2: 18 individuals with decreased LVEF. Seventeen patients with coronary artery disease were divided into group 3: 12 individuals with normal LVEF and group 4: 5 individuals with decreased LVEF. Two-dimensional echocardiography was used to measure LVEF. Myocardial norepinephrine was determined by high-performance liquid chromatography. RESULTS: Myocardial norepinephrine in CC with and without ventricular dysfunction was 1.3±1.3 and 6.1±4.2 pg/μg noncollagen protein, respectively (p<0.0001); in coronary artery disease with and without ventricular dysfunction, it was 3.3±3.0 and 9.8±4.2 pgμg noncollagen protein, respectively (p<0.0001). A positive correlation was found between LVEF and myocardial norepinephrine concentration in the patients with Chagas' cardiomyopathy (p<0.01, r = 0.57) and also in those with coronary artery disease (p<0.01, r=0.69). A significant difference was demonstrated between norepinephrine concentrations in patients with normal LVEF (groups 1 and 3; p = 0.0182), but no difference was found in patients with decreased LVEF (groups 2 and 4; p = 0.1467). CONCLUSION: In patients with Chagas' cardiomyopathy and normal global ejection fraction there is an early cardiac denervation, when compared to coronary artery disease patients.

FUNDAMENTO: La norepinefrina miocárdica está alterada en la disfunción ventricular izquierda. En pacientes con cardiomiopatía chagásica (CC), esa cuestión aun no fue discutida. OBJETIVO: Determinar el nivel de norepinefrina (NE) miocárdica en pacientes con CC y compararla en pacientes con enfermedad arterial coronaria (EAC) y relacionar NE miocárdica con la fracción de eyección del ventrículo izquierdo (FEVI). MÉTODOS: 39 pacientes con CC, divididos en grupo 1: 21 individuos con FEVI normal y grupo 2: 18 con FEVI disminuida. Diecisiete pacientes con EAC fueron divididos en grupo 3: 12 individuos con FEVI normal y grupo 4: 5 individuos con FEVI disminuida. Ecocardiografía bidimensional fue usada para medir la FEVI. La NE miocárdica fue determinada a través de Cromatografía Líquida de Alta Eficiencia (HPLC). RESULTADOS: La NE miocárdica en la CC con y sin disfunción ventricular fue 1,3±1,3 y 6,1±4,2 pg/µg de proteína no colagenosa, respectivamente (p<0,0001); en la EAC con y sin disfunción ventricular, fue 3,3±3,0 y 9,8±4,2 pg/µg de proteína no colagenosa, respectivamente (p<0,0001). Una correlación positiva fue observada entre la FEVI y la concentración de NE miocárdica en pacientes con CC (p<0,01; r=0,57) y también en aquellos con EAC (p<0,01; r=0,69). Una diferencia significativa fue demostrada entre las concentraciones de NE en pacientes con FEVI normal (grupos 1 y 3; p = 0,0182), pero ninguna diferencia fue observada en pacientes con FEVI disminuida (grupos 2 y 4; p = 0,1467). CONCLUSIONES: Pacientes con CC y fracción de eyección global normal presentan una denervación cardíaca precoz, cuando son comparados a pacientes con enfermedad arterial coronaria.

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.

Endothelin-1 receptors play a minor role in the protection against acute Trypanosoma cruzi infection in mice

Chagas' disease, caused by the protozoan Trypanosoma cruzi, is a major cause of cardiovascular disability in countries where it is endemic. Damage to the heart microvasculature has been proposed to be an important factor in the pathogenesis of heart dysfunction. Endothelin-1 (ET-1) is a potent vasoconstrictor and exerts its effects via specific ET A and ET B receptors. A few studies have suggested a role for ET-1 and its receptors in the pathogenesis of Chagas' disease. We investigated the effects of treatment with bosentan, an ET A/ET B receptor antagonist, on the course of T. cruzi infection (Y strain) in C57Bl/6 mice. Treatment with bosentan (100 mg kg-1 day-1) was given per os starting day 0 after infection until sacrifice. Bosentan significantly increased myocardial inflammation, with no effects on parasitemia. Although the total number of nests was similar, a lower number of intact amastigote nests was found in the heart of bosentan-treated animals. Bosentan failed to affect the infection-associated increase in the cardiac levels of the cytokines IFN-g and TNF-a and the chemokines CCL2/MCP-1, CCL3/MIP-1a and CCL5/RANTES. In vitro, pre-incubation with ET-1 (0.1 æM) 4 h before infection enhanced the uptake of the parasites by peritoneal macrophages, and this effect was abrogated when macrophages were pre-treated with bosentan (1 æM) 15 min before incubation with ET-1. However, ET-1 did not alter killing of intracellular parasites after 48 h of in vitro infection. Our data suggest that bosentan-treated mice have a delay in controlling parasitism which is compensated for exacerbated inflammation. Infection is eventually controlled in these animals and lethality is unchanged, demonstrating that ET-1 plays a minor role in the protection against acute murine T. cruzi infection.

Proteomic inventory of myocardial proteins from patients with chronic Chagas' cardiomyopathy

Chronic Chagas' disease cardiomyopathy (CCC) is an often fatal outcome of Trypanosoma cruzi infection, with a poorer prognosis than other cardiomyopathies. CCC is refractory to heart failure treatments, and is the major indication of heart transplantation in Latin America. A diffuse myocarditis, plus intense myocardial hypertrophy, damage and fibrosis, in the presence of very few T. cruzi forms, are the histopathological hallmarks of CCC. To gain a better understanding of the pathophysiology of CCC, we analyzed the protein profile in the affected CCC myocardium. Homogenates from left ventricular myocardial samples of end-stage CCC hearts explanted during heart transplantation were subjected to two-dimensional electrophoresis with Coomassie blue staining; protein identification was performed by MALDI-ToF mass spectrometry and peptide mass fingerprinting. The identification of selected proteins was confirmed by immunoblotting. We demonstrated that 246 proteins matched in gels from two CCC patients. They corresponded to 112 distinct proteins. Along with structural/contractile and metabolism proteins, we also identified proteins involved in apoptosis (caspase 8, caspase 2), immune system (T cell receptor ß chain, granzyme A, HLA class I) and stress processes (heat shock proteins, superoxide dismutases, and other oxidative stress proteins). Proteins involved in cell signaling and transcriptional factors were also identified. The identification of caspases and oxidative stress proteins suggests the occurrence of active apoptosis and significant oxidative stress in CCC myocardium. These results generated an inventory of myocardial proteins in CCC that should contribute to the generation of hypothesis-driven experiments designed on the basis of the classes of proteins identified here.

O papel do acúmulo de colágeno no interstício miocárdico na sobrevida dos pacientes com cardiomiopatia dilatada idiopática e chagásica / The role of storage of interstitial myocardial collagen on the overlife rate of patients with idiopathic and chagasic dilated cardiomyopathy

OBJETIVO: Avaliar a correlação entre um marcador estrutural do miocárdio e a sobrevida dos pacientes com cardiomiopatia dilatada. MÉTODOS: Mediante realização da biópsia endomiocárdica e exame ecocardiográfico foram estudados 9 indivíduos sem doença estrutural miocárdica (controle) e 45 pacientes com cardiomiopatia dilatada grave de etiologia idiopática (MCDI) e chagásica (MCDC). Foi analisada a correlação entre a quantidade de colágeno miocárdico intersticial (FVCI) e a sobrevida desses pacientes, se a FVCI diferia entre as etiologias, e se a fibrose interferia na função e geometria do miocárdio. RESULTADOS: Foi observado que a FVCI foi 15 vezes maior nos cardiomiopatas em relação ao grupo-controle, mas não diferiu em relação às MCDI e MCDC (*p < 0,001). Não houve correlação da FCVI com a sobrevida dos pacientes com cardiomiopatias (MCDI p = 0,249 e na MCDC p = 0,587) e apenas na MCDI a fração de ejeção do ventrículo esquerdo teve correlação com a FVCI. O diâmetro diastólico final do ventrículo esquerdo não se correlacionou com a FCVI nas duas etiologias. CONCLUSÃO: A fibrose miocárdica não diferiu entre as duas etiologias, não se correlacionou com o prognóstico das MCDC e MCDI e apenas na MCDI ela se correlacionou com a FEVE.

OBJECTIVE: To find out whether there is a correlation between a myocardial structural marker and the overlife rate of patients with dilated cardiomyopathy. METHODS: Using endomyocardial biopsy and 2D-echocardiogram, we studied nine patients with no changes in myocardial structure (control) and 45 patients with severe dilated cardiomyopathy of idiopathic etiology (IDCM) and of Chagasic etiology (CDCM). We analyzed the correlation between the quantity of interstitial myocardial collagen (ICVF) and the overlife rates of these patients. We also evaluated the difference in ICVF between these groups and whether fibrosis interfered on the geometry and function of the myocardium. RESULTS: We observed that ICVF was 15 times higher in cardiomyopathy patients than in the control group, but there was no difference in ICVF between CDCM and IDCM (*p < 0.001) patients. There was no correlation between ICVF and the overlife rate in cardiomyopathy patients (IDCM p = 0.249, and CDCM p = 0.587). We observed a significant correlation between ICVF and left ventricular ejection fraction (LVEF) only for IDCM. There was no correlation between ICVF and left ventricular diastolic diameter in either etiology. CONCLUSION: There was no difference in myocardial fibrosis between patients with CDCM or IDCM, and there was no correlation between fibrosis and the prognosis either for IDCM or CDCM. There was a correlation between myocardial fibrosis and LVEF only for IDCM.

Protein 3-nitrotyrosine formation during Trypanosoma cruzi infection in mice

Nitric oxide (ÀNO) is a diffusible messenger implicated in Trypanosoma cruzi resistance. Excess production of ÀNO and oxidants leads to the generation of nitrogen dioxide (ÀNO2), a strong nitrating agent. Tyrosine nitration is a post-translational modification resulting from the addition of a nitro (-NO2) group to the ortho-position of tyrosine residues. Detection of protein 3-nitrotyrosine is regarded as a marker of nitro-oxidative stress and is observed in inflammatory processes. The formation and role of nitrating species in the control and myocardiopathy of T. cruzi infection remain to be studied. We investigated the levels of ÀNO and protein 3-nitrotyrosine in the plasma of C3H and BALB/c mice and pharmacologically modulated their production during the acute phase of T. cruzi infection. We also looked for protein 3-nitrotyrosine in the hearts of infected animals. Our results demonstrated that C3H animals produced higher amounts of ÀNO than BALB/c mice, but their generation of peroxynitrite was not proportionally enhanced and they had higher parasitemias. While N G-nitro-arginine methyl ester treatment abolished ÀNO production and drastically augmented the parasitism, mercaptoethylguanidine and guanido-ethyl disulfide, at doses that moderately reduced the ÀNO and 3-nitrotyrosine levels, paradoxically diminished the parasitemia in both strains. Nitrated proteins were also demonstrated in myocardial cells of infected mice. These data suggest that the control of T. cruzi infection depends not only on the capacity to produce ÀNO, but also on its metabolic fate, including the generation of nitrating species that may constitute an important element in parasite resistance and collateral myocardial damage.

CC-chemokine receptors: a potential therapeutic target for Trypanosoma cruzi-elicited myocarditis

The comprehension of the pathogenesis of Trypanosoma cruzi-elicited myocarditis is crucial to delineate new therapeutic strategies aiming to ameliorate the inflammation that leads to heart dysfunction, without hampering parasite control. The augmented expression of CCL5/RANTES and CCL3/MIP-1alpha, and their receptor CCR5, in the heart of T. cruzi-infected mice suggests a role for CC-chemokines and their receptors in the pathogenesis of T. cruzi-elicited myocarditis. Herein, we discuss our recent results using a CC-chemokine receptor inhibitor (Met-RANTES), showing the participation of CC-chemokines in T. cruzi infection and unraveling CC-chemokine receptors as an attractive therapeutic target for further evaluation in Chagas disease.

Heart rate responses to a muscarinic agonist in rats with experimentally induced acute and subacute chagasic myocarditis

We administered arecoline to rats, with experimentally induced chagasic myocarditis, in order to study the sinus node sensitivity to a muscarinic agonist. Sixteen month old rats were inoculated with 200,000 T. cruzi parasites ("Y" strain). Between days 18 and 21 (acute stage), 8 infected rats and 8 age-matched controls received intravenous arecoline as a bolus injection at the following doses: 5.0, 10.0, 20.0, 40.0, and 80.0 mug/kg. Heart rate was recorded before, during and after each dose of arecoline. The remaining 8 infected animals and 8 controls were subjected to the same experimental procedure during the subacute stage, i.e., days 60 to 70 after inoculation. The baseline heart rate, of the animals studied during the acute stage (349 Ý 68 bpm, mean Ý SD), was higher than that of the controls (250 Ý 50 bpm, p < 0.005). The heart rate changes were expressed as percentage changes over baseline values. A dose-response curve was constructed for each group of animals. Log scales were used to plot the systematically doubled doses of arecoline and the induced-heart rate changes. The slope of the regression line for the acutely infected animals (r = - 0.99, b =1.78) was not different from that for the control animals (r = - 0.97, b = 1.61). The infected animals studied during the subacute stage (r = - 0.99, b = 1.81) were also not different from the age-matched controls (r = - 0.99, b = 1.26, NS). Consequently, our results show no pharmacological evidence of postjunctional hypersensitivity to the muscarinic agonist arecoline. Therefore, these results indirectly suggest that the postganglionic parasympathetic innervation, of the sinus node of rats with autopsy proved chagasic myocarditis, is not irreversibly damaged by Trypanosoma cruzi.