RESUMO
BACKGROUND: Adults with chronic Trypanosoma cruzi exhibit a poorly functional T cell compartment, characterized by monofunctional (IFN-γ-only secreting) parasite-specific T cells and increased levels of terminally differentiated T cells. It is possible that persistent infection and/or sustained exposure to parasites antigens may lead to a progressive loss of function of the immune T cells. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, the quality and magnitude of T. cruzi-specific T cell responses were evaluated in T. cruzi-infected children and compared with long-term T. cruzi-infected adults with no evidence of heart failure. The phenotype of CD4(+) T cells was also assessed in T. cruzi-infected children and uninfected controls. Simultaneous secretion of IFN-γ and IL-2 measured by ELISPOT assays in response to T. cruzi antigens was prevalent among T. cruzi-infected children. Flow cytometric analysis of co-expression profiles of CD4(+) T cells with the ability to produce IFN-γ, TNF-α, or to express the co-stimulatory molecule CD154 in response to T. cruzi showed polyfunctional T cell responses in most T. cruzi-infected children. Monofunctional T cell responses and an absence of CD4(+)TNF-α(+)-secreting T cells were observed in T. cruzi-infected adults. A relatively high degree of activation and differentiation of CD4(+) T cells was evident in T. cruzi-infected children. CONCLUSIONS/SIGNIFICANCE: Our observations are compatible with our initial hypothesis that persistent T. cruzi infection promotes eventual exhaustion of immune system, which might contribute to disease progression in long-term infected subjects.
Assuntos
Doença de Chagas/imunologia , Linfócitos T/imunologia , Trypanosoma cruzi/imunologia , Adolescente , Adulto , Ligante de CD40/análise , Criança , Pré-Escolar , ELISPOT , Feminino , Citometria de Fluxo , Humanos , Imunofenotipagem , Interferon gama/metabolismo , Interleucina-2/metabolismo , Masculino , Pessoa de Meia-Idade , Linfócitos T/química , Fator de Necrose Tumoral alfa/metabolismoRESUMO
We had formerly demonstrated that subjects chronically infected with Trypanosoma cruzi show impaired T cell responses closely linked with a process of T cell exhaustion. Recently, the expression of several inhibitory receptors has been associated with T cell dysfunction and exhaustion. In this study, we have examined the expression of the cytotoxic T lymphocyte antigen 4 (CTLA-4) and the leukocyte immunoglobulin like receptor 1 (LIR-1) by peripheral T. cruzi antigen-responsive IFN-gamma (IFN-γ)-producing and total T cells from chronically T. cruzi-infected subjects with different clinical forms of the disease. CTAL-4 expression was also evaluated in heart tissue sections from subjects with severe myocarditis. The majority of IFN-γ-producing CD4(+) T cells responsive to a parasite lysate preparation were found to express CTLA-4 but considerably lower frequencies express LIR-1, irrespective of the clinical status of the donor. Conversely, few IFN-γ-producing T cells responsive to tetanus and diphtheria toxoids expressed CTLA-4 and LIR-1. Polyclonal stimulation with anti-CD3 antibodies induced higher frequencies of CD4(+)CTAL-4(+) T cells in patients with severe heart disease than in asymptomatic subjects. Ligation of CTLA-4 and LIR-1 with their agonistic antibodies, in vitro, reduces IFN-γ production. Conversely, CTLA-4 blockade did not improved IFN-γ production in response to T. cruzi antigens. Subjects with chronic T. cruzi infection had increased numbers of CD4(+)LIR-1(+) among total peripheral blood mononuclear cells, relative to uninfected individuals and these numbers decreased after treatment with benznidazole. CTLA-4 was also expressed by CD3(+) T lymphocytes infiltrating heart tissues from chronically infected subjects with severe myocarditis. These findings support the conclusion that persistent infection with T. cruzi leads to the upregulation of inhibitory receptors which could alter parasite specific T cell responses in the chronic phase of Chagas disease.
Assuntos
Antígenos CD/metabolismo , Linfócitos T CD4-Positivos/metabolismo , Antígeno CTLA-4/metabolismo , Doença de Chagas/imunologia , Regulação da Expressão Gênica/imunologia , Coração/parasitologia , Receptores Imunológicos/metabolismo , Trypanosoma cruzi/patogenicidade , Adulto , Antígenos de Protozoários/imunologia , Linfócitos T CD4-Positivos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/parasitologia , Doença de Chagas/complicações , Doença de Chagas/tratamento farmacológico , Doença de Chagas/metabolismo , Doença Crônica , Regulação da Expressão Gênica/efeitos dos fármacos , Coração/efeitos dos fármacos , Humanos , Interferon gama/biossíntese , Receptor B1 de Leucócitos Semelhante a Imunoglobulina , Masculino , Pessoa de Meia-Idade , Miocardite/complicações , Miocardite/imunologia , Miocardite/metabolismo , Nitroimidazóis/farmacologia , Nitroimidazóis/uso terapêutico , Especificidade da Espécie , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/imunologiaRESUMO
BACKGROUND: The main criterion for treatment effectiveness in Chagas Disease has been the seronegative conversion, achieved many years post-treatment. One of the main limitations in evaluating treatment for chronic Chagas disease is the lack of reliable tests to ensure parasite clearance and to examine the effects of treatment. However, declines in conventional serological titers and a new multiplex assay can be useful tools to monitor early the treatment impact. METHODOLOGY/PRINCIPAL FINDINGS: Changes in antibody levels, including seronegative conversion as well as declines in titers, were serially measured in 53 benznidazole-treated and 89 untreated chronic patients in Buenos Aires, Argentina with a median follow-up of 36 months. Decrease of titers (34/53 [64%] treated vs. 19/89 [21%] untreated, p<0.001) and seronegative conversion (21/53, [40%] treated vs. 6/89, [7%] untreated, p<0.001) in at least one conventional serological test were significantly higher in the benznidazole-treated group compare with the untreated group. When not only complete seronegative conversion but also seronegative conversion on 2 tests and the decreases of titers on 2 or 3 tests were considered, the impact of treatment on conventional serology increased from 21% (11/53 subjects) to 45% (24/53 subjects). A strong concordance was found between the combination of conventional serologic tests and multiplex assay (kappa index 0.60) to detect a decrease in antibody levels pos-treatment. CONCLUSIONS/SIGNIFICANCE: Treatment with benznidazole in subjects with chronic Chagas disease has a major impact on the serology specific for T. cruzi infection in a shorter follow-up period than previously considered, reflected either by a complete or partial seronegative conversion or by a significant decrease in the levels of T. cruzi antibodies, consistent with a possible elimination or reduction of parasite load.
Assuntos
Anticorpos Antiprotozoários/sangue , Doença de Chagas/tratamento farmacológico , Monitoramento de Medicamentos/métodos , Trypanosoma cruzi/imunologia , Adulto , Antiprotozoários/administração & dosagem , Argentina , Doença de Chagas/parasitologia , Doença Crônica , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Nitroimidazóis/administração & dosagemRESUMO
BACKGROUND: As many as 20 million people are living with Trypanosoma cruzi infection in Latin American, yet few receive any treatment. The major limitation in developing and evaluating potential new drugs for their efficacy is the lack of reliable tests to assess parasite burden and elimination. METHODS: Adults volunteers with chronic T. cruzi infection were evaluated clinically and stratified according to the Kuschnir classification. Individuals with group 0 and group 1 clinical status were treated with benznidazole (5 mg/kg per day for 30 days). The changes in T. cruzi-specific T cell and antibody responses, as well as in clinical status, were measured periodically over the 3-5-year follow-up period and were compared with pretreatment conditions and with values in an untreated control group. RESULTS: The frequency of peripheral interferon (IFN)-gamma-producing T cells specific for T. cruzi declined as early as 12 months after benznidazole treatment and subsequently became undetectable in a substantial proportion of treated subjects. In addition, decreases in antibody responses to a pool of recombinant T. cruzi proteins also decreased in many of these same subjects. The shift to negative IFN-gamma T cell responses was highly associated with an early increase in IFN-gamma-producing T cells with phenotypic features of effector/effector memory cells in a subset of subjects. Benznidazole treatment also resulted in an increase in naive and early differentiated memory-like CD8(+) T cells in a majority of subjects. CONCLUSIONS: Benznidazole treatment during chronic Chagas disease has a substantial impact on parasite-specific immune response that is likely indicative of treatment efficacy and cure.
Assuntos
Doença de Chagas/tratamento farmacológico , Doença de Chagas/imunologia , Nitroimidazóis/uso terapêutico , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/fisiologia , Adulto , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Citometria de Fluxo , Humanos , Interferon gama/metabolismo , Interleucina-2/metabolismo , Pessoa de Meia-Idade , Linfócitos T/imunologia , Linfócitos T/metabolismo , Resultado do Tratamento , Trypanosoma cruzi/imunologia , Adulto JovemRESUMO
Objetivos: Comparar la evolución alejada de pacientes crónicos tratados con benznidazol y sin tratamiento. Métodos: Se incluyeron 1835 pacientes con enfermedad de Chagas crónica y más de 1 año de seguimiento. El punto final principal de evaluación fue la progresión de la miocardiopatía y los puntos finales secundarios incluyeron los cambios electrocardiográficos y la negativización serológica. Los resultados del tratamiento se evaluaron en un modelo multivariado (Cox) ajustados para la edad, sexo, síntomas y ECG. Los pacientes tratados recibieron 5 mg/kg de peso/día de benznidazol oral, durante 30 días (760 pacientes) o continuaron sin tratamiento (1075 pacientes). Resultados: La edad, los síntomas y el ECG anormal fueron predictores independientes de progresión de la miocardiopatía. El tratamiento con benznidazol redujo la progresión de la cardiopatía (HR 0.63; IC 95%: 0.47-0.95; p = 0.02), la mortalidad (HR 0.54; IC 95%: 0.30-0.97; p = 0.04) y los cambios del ECG (HR 0.59; IC 95%: 0.44-0.79; p < 0.001), mientras que aumentó la frecuencia de negativización completa de la serología (HR 1.78; IC 95%: 1.16-2.73; p = 0.008). Conclusiones: El tratamiento con benznidazol mostró un beneficio clínico y serológico sobre la evolución de la enfermedad de Chagas crónica.
Assuntos
Humanos , Masculino , Feminino , Antiparasitários/administração & dosagem , Antiparasitários , Antiparasitários/uso terapêutico , Doença de Chagas/complicações , Doença de Chagas/terapiaRESUMO
Chagas disease is caused by a parasite, Trypanosoma cruzi, transmitted primarily by a triatomine insect and affects approximately 8 million people in Latin American countries. The principal aim of the management of the disease is to avoid the development of cardiomyopathy and transmission by blood transfusion, congenital and organ transplants. Currently, benznidazole is the only etiological treatment commercially available for the disease until new and better drugs can be developed and tested. Benznidazole has been used even though it does not have all the conditions of an ideal drug. The efficacy and tolerance of benznidazole is inversely related to the age of the patient, while its side effects are more frequent in elderly patients. The side effects are systematically evaluated only in controlled studies designed for that purpose. However, the true clinical impact of the side effects could be different, considering that the treatment is for a short duration (between 30 and 60 days) and only carried out once. In this article, we discuss the benefits and risks of the treatment with benznidazole from a clinical point of view to be considered for the management of the treatment of chronic adult Chagas disease patients in the current medical practice.
Assuntos
Doença de Chagas/tratamento farmacológico , Nitroimidazóis/efeitos adversos , Tripanossomicidas/efeitos adversos , Fatores Etários , Animais , Doença de Chagas/parasitologia , Doença Crônica , Humanos , Nitroimidazóis/administração & dosagem , Nitroimidazóis/uso terapêutico , Tripanossomicidas/administração & dosagem , Tripanossomicidas/uso terapêutico , Trypanosoma cruziRESUMO
BACKGROUND: Previously, we identified a set of HLA-A020.1-restricted trans-sialidase peptides as targets of CD8+ T cell responses in HLA-A0201+ individuals chronically infected by T. cruzi. METHODS AND FINDINGS: Herein, we report the identification of peptides encoded by the same trans-sialidase gene family that bind alleles representative of the 6 most common class I HLA-supertypes. Based on a combination of bioinformatic predictions and HLA-supertype considerations, a total of 1001 epitopes predicted to bind to HLA A01, A02, A03, A24, B7 and B44 supertypes was selected. Ninety-six supertype-binder epitopes encoded by multiple trans-sialidase genes were tested for the ability to stimulate a recall CD8+ T cell response in the peripheral blood from subjects with chronic T. cruzi infection regardless the HLA haplotype. An overall hierarchy of antigenicity was apparent, with the A02 supertype peptides being the most frequently recognized in the Chagas disease population followed by the A03 and the A24 supertype epitopes. CD8+ T cell responses to promiscuous epitopes revealed that the CD8+ T cell compartment specific for T. cruzi displays a functional profile with T cells secreting interferon-gamma alone as the predominant pattern and very low prevalence of single IL-2-secreting or dual IFN-gamma/IL-2 secreting T cells denoting a lack of polyfunctional cytokine responses in chronic T. cruzi infection. CONCLUSIONS: This study identifies a set of T. cruzi peptides that should prove useful for monitoring immune competence and changes in infection and disease status in individuals with chronic Chagas disease.
Assuntos
Linfócitos T CD8-Positivos/imunologia , Doença de Chagas/imunologia , Epitopos de Linfócito T/genética , Glicoproteínas/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Neuraminidase/genética , Adulto , Animais , América Central/epidemiologia , Doença de Chagas/epidemiologia , Doença de Chagas/genética , Ensaio de Imunoadsorção Enzimática , Epitopos de Linfócito T/imunologia , Antígenos HLA/genética , Antígenos HLA/imunologia , Antígenos HLA-A/genética , Antígeno HLA-A2 , Antígenos HLA-B/imunologia , Hemaglutinação , Humanos , Interferon gama/imunologia , Pessoa de Meia-Idade , América do Sul/epidemiologia , Linfócitos T/imunologia , Trypanosoma cruzi/imunologiaRESUMO
Para determinar el efecto del tratamiento con benznidazol sobre las células T de memoria específica para Trypanosoma cruzi, se seleccionaron 47 pacientes con tres reacciones serológicas positivas para T. cruzi, sin cardiopatía y edades comprendidas entre los 30 y los 50 años. El tratamiento se realizó con benznidazol en dosis de 5 mg/kg/d por 30 días. Se efectuó una evaluación serológica, inmunológica y clínica pretratamiento (tiempo 0) y a los 2, 6 y 12 meses postratamiento. Posteriormente, los controles se hicieron anualmente. La respuesta de linfocitos T frente a un lisado de amastigotas de T. cruzi se evaluó por la técnica de ELISPOT para IFN-ã. La frecuencia de linfocitos T de memoria productores de IFN-ã específicos para T. cruzi disminuyó significativamente en el grupo tratado (n = 33) versus el no tratado (n = 14) 12 meses después del seguimiento. Once de 25 (44%) pacientes que recibieron benznidazol negativizaron la respuesta para IFN-ã. Cuatro de los 11 (36%) pacientes con ELISPOT (+) que negativizaron la respuesta por ELISPOT para IFN-ã también negativizaron la serología convencional a los 2 años postratamiento. Durante el seguimiento no se observaron alteraciones clínicas. Estos hallazgos muestran que el benznidazol es capaz de modular la respuesta celular T de memoria específica para T. cruzi. La medición de la frecuencia de linfocitos T de memoria productores de IFN-ã podría constituir un ensayo más sensible y precoz para determinar el impacto/eficacia del tratamiento específico contra este parásito.
To determine the effect of benznidazol therapy on memory T cells specific for Trypanosoma cruzi, 47 patients between 30 and 50 years old and three positive serological tests for T. cruzi without cardiopathy were selected. Benznidazol was administered in a dose of 5 mg/kg/d during 30 days. Serological, immunological and clinical assessment was performed at basal (time 0) and at 2, 6 and 12 months following treatment, and once a year thereafter. IFN-ã ELISPOT assay was used to evaluate T cell responses against a T. cruzi lysate obtained from amastigotes. The frequency of IFN-ã - producing memory T lymphocytes specific for T. cruzi was significantly lower in the treatment group (n=33) compared to the control group (n=14) 12 months after the therapy. IFN- ã response became negative in 11 patients in the treatment group (44%). Among these 11 patients, conventional serology also became negative in 4 patients (36%) after 2 years of treatment. No clinical manifestations occurred during follow-up. These findings show that benznidazol is capable of modulating T cell responses specific for T. cruzi. Measuring the frequency of memory T lymphocytes producing IFN-ã might become a more sensitive test to determine earlier the impact and/or efficacy of the specific treatment against this parasite.
RESUMO
INTRODUCTION AND OBJECTIVES: The development of asymptomatic left ventricular dysfunction signifies a worsening of chronic chagasic cardiomyopathy. Our objective was to identify factors that predict the development of heart failure and all-cause mortality. METHODS: The study included 95 patients with an echocardiographic diagnosis of asymptomatic left ventricular dysfunction. The patients' clinical, electrocardiographic and echocardiographic characteristics were recorded. Factors associated with the development of heart failure were evaluated by Cox regression modeling. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated. Receiver operating characteristic (ROC) curves were used to evaluate the sensitivity and specificity of continuous variables identified as significant in the regression analysis. RESULTS: Patients (mean age, 55 [11] years) were followed up for a median of 63 months (interquartile range, 32-110 months). Univariate analysis showed that there were significant differences in mild and severe systolic dysfunction, age on admission, and E-point-to-septal separation, while the only significant predictors of heart failure found on Cox regression analysis were severe systolic dysfunction (HR=3.53; 95% CI, 1.21-10.30; P=.021) and E-point-to-septal separation (HR=1.12; 95% CI, 1.02-1.23; P=.014). The mortality rate was 3% (3/95) in patients who continued to have asymptomatic left ventricular dysfunction and 37% (10/27) in those who developed heart failure. CONCLUSIONS: The E-point-to-septal separation and the presence of severe systolic dysfunction can serve as predictors of heart failure in patients with chronic chagasic cardiomyopathy and asymptomatic left ventricular dysfunction.
Assuntos
Cardiomiopatia Chagásica/complicações , Insuficiência Cardíaca/etiologia , Disfunção Ventricular Esquerda/complicações , Progressão da Doença , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , PrognósticoRESUMO
BACKGROUND: Benznidazole is effective for treating acute-stage Chagas disease, but its effectiveness for treating indeterminate and chronic stages remains uncertain. OBJECTIVE: To compare long-term outcomes of patients with nonacute Chagas disease treated with benznidazole versus outcomes of those who did not receive treatment. DESIGN: Clinical trial with unblinded, nonrandom assignment of patients to intervention or control groups. SETTING: Chagas disease center in Buenos Aires, Argentina. PATIENTS: 566 patients 30 to 50 years of age with 3 positive results on serologic tests and without heart failure. MEASUREMENTS: The primary outcome was disease progression, defined as a change to a more advanced Kuschnir group or death. Secondary outcomes included new abnormalities on electrocardiography and serologic reactivity. INTERVENTION: Oral benznidazole, 5 mg/kg of body weight per day for 30 days (283 patients), or no treatment (283 patients). RESULTS: Fewer treated patients had progression of disease (12 of 283 [4%] vs. 40 of 283 [14%]; adjusted hazard ratio, 0.24 [95% CI, 0.10 to 0.59]; P = 0.002) or developed abnormalities on electrocardiography (15 of 283 [5%] vs. 45 of 283 [16%]; adjusted hazard ratio, 0.27 [CI, 0.13 to 0.57]; P = 0.001) compared with untreated patients. Left ventricular ejection fraction (hazard ratio, 0.97 [CI, 0.94 to 0.99]; P < 0.002) and left ventricular diastolic diameter (hazard ratio, 2.45 [CI, 1.53 to 3.95]; P < 0.001) were also associated with disease progression. Conversion to negative results on serologic testing was more frequent in treated patients than in untreated patients (32 of 218 [15%] vs. 12 of 212 [6%]; adjusted hazard ratio, 2.1 [CI, 1.06 to 4.06]; P = 0.034). LIMITATIONS: Nonrandom, unblinded treatment assignment was used, and follow-up data were missing for 20% of patients. Loss to follow-up was more common among patients who were less sick. Two uncontrolled interim analyses were conducted. CONCLUSIONS: Compared with no treatment, benznidazole treatment was associated with reduced progression of Chagas disease and increased negative seroconversion for patients presenting with nonacute disease and no heart failure. These observations indicate that a randomized, controlled trial should now be conducted.