B-Cell Responses in Chronic Chagas Disease: Waning of Trypanosoma cruzi-Specific Antibody-Secreting Cells Following Successful Etiological Treatment

BACKGROUND

A drawback in the treatment of chronic Chagas disease (American trypanosomiasis) is the long time required to achieve complete loss of serological reactivity, the standard for determining treatment efficacy.

METHODS

Antibody-secreting cells and memory B cells specific for Trypanosoma cruzi and their degree of differentiation were evaluated in adult and pediatric study participants with chronic Chagas disease before and after etiological treatment.

RESULTS

T. cruzi-specific antibody-secreting cells disappeared from the circulation in benznidazole or nifurtimox-treated participants with declining parasite-specific antibody levels after treatment, whereas B cells in most participants with unaltered antibody levels were low before treatment and did not change after treatment. The timing of the decay in parasite-specific antibody-secreting B cells was similar to that in parasite-specific antibodies, as measured by a Luminex-based assay, but preceded the decay in antibody levels detected by conventional serology. The phenotype of total B cells returned to a noninfection profile after successful treatment.

CONCLUSIONS

T. cruzi-specific antibodies in the circulation of chronically T. cruzi-infected study participants likely derive from both antigen-driven plasmablasts, which disappear after successful treatment, and long-lived plasma cells, which persist and account for the low frequency and long course to complete seronegative conversion in successfully treated participants.

Serological reactivity against T. cruzi-derived antigens: Evaluation of their suitability for the assessment of response to treatment in chronic Chagas disease

Chagas disease, caused by the protozoan Trypanosoma cruzi, affects more than 6 million people worldwide. Following a mostly asymptomatic acute phase, the disease progresses to a long-lasting chronic phase throughout which life-threatening disorders to the heart and/or gastrointestinal tract will manifest in about 30% of those chronically infected. During the chronic phase, the parasitemia is low and intermittent, while a high level of anti-T. cruzi antibodies persist for years. These two features hamper post-chemotherapeutic follow-up of patients with the tools available. The lack of biomarkers for timely assessment of therapeutic response discourages a greater use of the two available anti-parasitic drugs, and complicates the evaluation of new drugs in clinical trials. Herein, we investigated in a blinded case-control study the serological reactivity over time of a group of parasite-derived antigens to potentially address follow up of T. cruzi chronically infected subjects after treatment. We tested PFR2, KMP11, HSP70, 3973, F29 and the InfYnity multiplexed antigenic array, by means of serological assays on a multi-national retrospective collection of samples. Some of the antigens exhibited promising results, underscoring the need for further studies to determine their potential role as treatment response biomarkers.

Reduced Trypanosoma cruzi-specific humoral response and enhanced T cell immunity after treatment interruption with benznidazole in chronic Chagas disease

BACKGROUND

Interruption of benznidazole therapy due to the appearance of adverse effects, which is presumed to lead to treatment failure, is a major drawback in the treatment of chronic Chagas disease.

METHODS

Trypanosoma cruzi-specific humoral and T cell responses, T cell phenotype and parasite load were measured to compare the outcome in 33 subjects with chronic Chagas disease treated with an incomplete benznidazole regimen and 58 subjects treated with the complete regimen, during a median follow-up period of 48 months.

RESULTS

Both treatment regimens induced a reduction in the T. cruzi-specific antibody levels and similar rates of treatment failure when evaluated using quantitative PCR. Regardless of the regimen, polyfunctional CD4+ T cells increased in the subjects, with successful treatment outcome defined as a decrease of T. cruzi-specific antibodies. Regardless of the serological outcome, naive and central memory T cells increased after both regimens. A decrease in CD4+ HLA-DR+ T cells was associated with successful treatment in both regimens. The cytokine profiles of subjects with successful treatment showed fewer inflammatory mediators than those of the untreated T. cruzi-infected subjects. High levels of T cells expressing IL-7 receptor and low levels of CD8+ T cells expressing the programmed cell death protein 1 at baseline were associated with successful treatment following benznidazole interruption.

CONCLUSIONS

These findings challenge the notion that treatment failure is the sole potential outcome of an incomplete benznidazole regimen and support the need for further assessment of the treatment protocols for chronic Chagas disease.

Impaired frequencies and function of platelets and tissue remodeling in chronic Chagas disease

Chronic inflammation, as a consequence of the persistent infection with Trypanosoma cruzi, leads to continuous activation of the immune system in patients with chronic Chagas disease. We have previously shown that increased sera levels of soluble P-selectin are associated with the severity of the cardiomyopathy distinctive of chronic Chagas disease. In this study, we explored the expression of biomarkers of platelet and endothelial activation, tissue remodeling, and mediators of the coagulation cascade in patients at different clinical stages of chronic Chagas heart disease. The frequencies of activated platelets, measured by the expression of CD41a and CD62P were decreased in patients with chronic Chagas disease compared with those in uninfected subjects, with an inverse association with disease severity. Platelet activation in response to adenosine diphosphate was also decreased in T. cruzi-infected subjects. A major proportion of T. cruzi infected subjects showed increased serum levels of fibrinogen. Patients with severe cardiac dysfunction showed increased levels of endothelin-1 and normal values of procollagen I. In conclusion, chronic infection with T. cruzi induced hemostatic alterations, even in those patients who do not yet present cardiac symptoms.

Distinct monocyte subset phenotypes in patients with different clinical forms of chronic Chagas disease and seronegative dilated cardiomyopathy

Background

Chronic infection with Trypanosoma cruzi leads to a constant stimulation of the host immune system. Monocytes, which are recruited in response to inflammatory signals, are divided into classical CD14^hiCD16^—, non-classical CD14^loCD16⁺ and intermediate CD14^hiCD16⁺ subsets. In this study, we evaluated the frequencies of monocyte subsets in the different clinical stages of chronic Chagas disease in comparison with the monocyte profile of seronegative heart failure subjects and seronegative healthy controls. The effect of the anti-parasite drug therapy benznidazole on monocyte subsets was also explored.

Methodology/Principal findings

The frequencies of the different monocyte subsets and their phenotypes were measured by flow cytometry. Trypanosoma cruzi-specific antibodies were quantified by conventional serological tests. T. cruzi-infected subjects with mild or no signs of cardiac disease and patients suffering from dilated cardiomyopathy unrelated to T. cruzi infection showed increased levels of non-classical CD14^loCD16⁺ monocytes compared with healthy controls. In contrast, the monocyte profile in T. cruzi-infected subjects with severe cardiomyopathy was skewed towards the classical and intermediate subsets. After benznidazole treatment, non-classical monocytes CD14^loCD16⁺ decreased while classical monocytes CD14^hiCD16^—increased.

Conclusions/Significance

The different clinical stages of chronic Chagas disease display distinct monocyte profiles that are restored after anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might also alter cell components of the innate immune system.

Monocytes are key players during infection, and they leave the bloodstream and migrate into tissues in response to inflammatory signals. Although the recruitment of monocytes is essential for the effective control and clearance of microorganisms, they can also be highly damaging to neighboring tissues. Based on the expression of CD14 and CD16, monocytes are classified into classical, non-classical and intermediate subsets, all of which exert different functions. Because chronic T. cruzi infection induces a constant activation of the host immune system, inflammatory signals are exacerbated, possibly leading to alterations in the frequencies of monocyte subsets. In this study, we evaluated the monocyte profile in Trypanosoma cruzi-infected subjects with different degrees of cardiac dysfunction and explored whether this profile was similar between seropositive and seronegative subjects with heart failure. We found that the different clinical stages of chronic Chagas disease displayed distinct monocyte profiles, which are susceptible to being restored by modulating the parasite load with anti-parasite drug therapy. T. cruzi-infected subjects with severe cardiac disease displayed a profile of monocytes subsets suggestive of a more pronounced inflammatory environment compared with subjects suffering from heart failure not related to T. cruzi infection, supporting that parasite persistence might be a detrimental factor in the evolution of the cardiac disease induced by T. cruzi.

Distinct Treatment Outcomes of Antiparasitic Therapy in Trypanosoma cruzi-Infected Children Is Associated With Early Changes in Cytokines, Chemokines, and T-Cell Phenotypes

Background: In contrast to adults, Trypanosoma cruzi-infected children have more broadly functional Trypanosoma cruzi-specific T cells, and the total T-cell compartment exhibits fewer signs of immune exhaustion. However, not much is known about the link between immunocompetence and the treatment efficacy for human Chagas disease.

Methods: Using cytokine enzyme-linked immunosorbent spot (ELISPOT) polychromatic flow cytometry, cytometric bead assay, multiplex serological assays and quantitative PCR, we evaluated T. cruzi-specific T-cell and antibody immune responses, T-cell phenotypes and parasitemia in children in the early chronic phase of Chagas disease undergoing anti-Trypanosoma cruzi treatment.

Results: Treatment with benznidazole or nifurtimox induced a decline in T. cruzi-specific IFN-γ- and IL-2-producing cells and proinflammatory cytokines and chemokines. T-cell responses became detectable after therapy in children bearing T-cell responses under background levels prior to treatment. The total frequencies of effector, activated and antigen-experienced T cells also decreased following anti-T. cruzi therapy, along with an increase in T cells expressing the receptor of the homeostatic cytokine IL-7. Posttreatment changes in several of these markers distinguished children with a declining serologic response suggestive of successful treatment from those with sustained serological responses in a 5-year follow-up study. A multivariate analysis demonstrated that lower frequency of CD4⁺CD45RA⁻CCR7⁻CD62L⁻ T cells prior to drug therapy was an independent indicator of successful treatment.

Conclusions: These findings further validate the usefulness of alternative metrics to monitor treatment outcomes. Distinct qualitative and quantitative characteristics of T cells prior to drug therapy may be linked to treatment efficacy.

Flow Mediated Dilation in Cirrhosis: A Pilot Study in Different Stages of the Disease

INTRODUCTION

Cirrhosis is associated with changes in the cardiovascular system, where the circulatory dysfunction is compensated by the development of a hyperdynamic circulation. Endothelial function can be understood as the endothelium capability to release Nitric Oxide (NO) where an impairment in the normal development of this process constitutes a main step in the genesis and progression of atherosclerosis, a major cause of cardiovascular events. In recent years, non-invasive measurements have gained attention, due to the potential complications associated to invasive procedures.

OBJECTIVE

To evaluate endothelial function (EF) in patients with cirrhosis, in different stages of the disease, complemented with hemodynamic measurements.

METHODS

Individuals were divided in three age groups, according to the severity of their disease. EF was assessed by using the flow mediated dilation technique (FMD), jointly with noninvasive determination of cardiac output (CO), total peripheral resistance (TPR) and arterial compliance (AC).

RESULTS

TPR showed a decrease in advanced severity while AC had an increase. Particularly, EF was found to be higher in CHC group, decreasing in CHB and more pronounceably in CHA. Concomitantly, an inverse behavior was observed regarding CO evolution.

CONCLUSION

EF was noninvasively evaluated in cirrhosis, in terms of the progression of the disease. Hyperdynamic states in the more advanced condition were accompanied by a higher vascular reactivity, probably associated with higher peripheral NO release and increased AC.

Treatment Success in Trypanosoma cruzi Infection Is Predicted by Early Changes in Serially Monitored Parasite-Specific T and B Cell Responses

BACKGROUND

Chagas disease is the highest impact parasitic disease in Latin America. We have proposed that changes in Trypanosoma cruzi-specific immune responses might serve as surrogate indicators of treatment success. Herein, we addressed in a long-term follow-up study whether cure achieved after treatment can be predicted by changes in non-conventional indexes of anti-parasite serological and T cell activities.

METHODOLOGY/PRINCIPAL FINDINGS

T. cruzi-specific T cell responses, as measured by interferon-γ ELISPOT and T. cruzi-specific antibodies assessed by ELISA, hemagglutination and immunofluorescence tests as well as by a multiplex assay incorporating 14 recombinant T. cruzi proteins were measured in 33 patients at 48-150 months post-benznidazole treatment. Cure - as assessed by conventional serological tests - was associated with an early decline in T. cruzi-specific IFN-γ-producing T cells and in antibody titers measured by the multiplex serological assay. Changes in the functional status and potential of T. cruzi-specific T cells, indicative of reduced antigen stimulation, provided further evidence of parasitological cure following benznidazole treatment. Patients showing a significant reduction in T. cruzi-specific antibodies had higher pre-therapy levels of T. cruzi-specific IFN-γ- producing T cells compared to those with unaltered humoral responses post-treatment.

CONCLUSIONS/SIGNIFICANCE

Monitoring of appropriate immunological responses can provide earlier and robust measures of treatment success in T. cruzi infection.

Perturbed T cell IL-7 receptor signaling in chronic Chagas disease

We have previously demonstrated that immune responses in subjects with chronic Trypanosoma cruzi infection display features common to other persistent infections with signs of T cell exhaustion. Alterations in cytokine receptor signal transduction have emerged as one of the cell-intrinsic mechanisms of T cell exhaustion. In this study, we performed an analysis of the expression of IL-7R components (CD127 and CD132) on CD4(+) and CD8(+) T cells and evaluated IL-7-dependent signaling events in patients at different clinical stages of chronic chagasic heart disease. Subjects with no signs of cardiac disease showed a decrease in CD127(+)CD132(+) cells and a reciprocal gain of CD127(-)CD132(+) in CD8(+) and CD4(+) T cells compared with either patients exhibiting heart enlargement or uninfected controls. T. cruzi infection, in vitro, was able to stimulate the downregulation of CD127 and the upregulation of CD132 on T cells. IL-7-induced phosphorylation of STAT5 as well as Bcl-2 and CD25 expression were lower in T. cruzi-infected subjects compared with uninfected controls. The serum levels of IL-7 were also increased in chronic chagasic patients. The present study highlights perturbed IL-7/IL-7R T cell signaling through STAT5 as a potential mechanism of T cell exhaustion in chronic T. cruzi infection.

Presence of antigen-experienced T cells with low grade of differentiation and proliferative potential in chronic Chagas disease myocarditis

BACKGROUND

The main consequence of chronic Trypanosoma cruzi infection is the development of myocarditis in approximately 20-30% of infected individuals but not until 10-20 years after the initial infection. We have previously shown that circulating interferon-γ-secreting T cells responsive to Trypanosoma cruzi antigens in chronic Chagas disease patients display a low grade of differentiation and the frequency of these T lymphocytes decreases along with the severity of heart disease. This study thought to explore the expression of inhibitory receptors, transcription factors of type 1 or regulatory T cells, and markers of T cell differentiation, immunosenescence or active cell cycle in cardiac explants from patients with advanced Chagas disease myocarditis.

METHODOLOGY/PRINCIPAL FINDINGS

The expression of different markers for T and B cells as well as for macrophages was evaluated by immunohistochemistry and immunofluorescence techniques in cardiac explants from patients with advanced chronic Chagas disease submitted to heart transplantation. Most infiltrating cells displayed markers of antigen-experienced T cells (CD3(+), CD4(+), CD8(+), CD45RO(+)) with a low grade of differentiation (CD27(+), CD57(-), CD45RA(-), PD(-)1(-)). A skewed T helper1/T cytotoxic 1 profile was supported by the expression of T-bet; whereas FOXP3(+) cells were scarce and located only in areas of severe myocarditis. In addition, a significant proliferative capacity of CD3(+) T cells, assessed by Ki67 staining, was found.

CONCLUSIONS/SIGNIFICANCE

The quality of T cell responses and immunoregulatory mechanisms might determine the pattern of the cellular response and the severity of disease in chronic Trypanosoma cruzi infection.

Polyfunctional T cell responses in children in early stages of chronic Trypanosoma cruzi infection contrast with monofunctional responses of long-term infected adults

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.

Towards a paradigm shift in the treatment of chronic Chagas disease

Treatment for Chagas disease with currently available medications is recommended universally only for acute cases (all ages) and for children up to 14 years old. The World Health Organization, however, also recommends specific antiparasite treatment for all chronic-phase Trypanosoma cruzi-infected individuals, even though in current medical practice this remains controversial, and most physicians only prescribe palliative treatment for adult Chagas patients with dilated cardiomyopathy. The present opinion, prepared by members of the NHEPACHA network (Nuevas Herramientas para el Diagnóstico y la Evaluación del Paciente con Enfermedad de Chagas/New Tools for the Diagnosis and Evaluation of Chagas Disease Patients), reviews the paradigm shift based on clinical and immunological evidence and argues in favor of antiparasitic treatment for all chronic patients. We review the tools needed to monitor therapeutic efficacy and the potential criteria for evaluation of treatment efficacy beyond parasitological cure. Etiological treatment should now be mandatory for all adult chronic Chagas disease patients.

Sequential combined treatment with allopurinol and benznidazole in the chronic phase of Trypanosoma cruzi infection: a pilot study

OBJECTIVES

Even though the use of combined drugs has been proved to be effective in other chronic infections, assessment of combined treatment of antiparasitic drugs in human Chagas' disease has not been performed. Herein, a pilot study was conducted to evaluate the tolerance and side effects of a sequential combined treatment of two antiparasitic drugs, allopurinol and benznidazole, in the chronic phase of Trypanosoma cruzi infection.

PATIENTS AND METHODS

Changes in total and T. cruzi-specific T and B cells were monitored during a median follow-up of 36 months. Allopurinol was administered for 3 months (600 mg/day) followed by 30 days of benznidazole (5 mg/kg/day) in 11 T. cruzi-infected subjects.

RESULTS

The combined sequential treatment of allopurinol and benznidazole was well tolerated. The levels of T. cruzi-specific antibodies significantly decreased after sequential combined treatment, as determined by conventional serology and by a multiplex assay using recombinant proteins. The frequency of T. cruzi-specific interferon-γ-producing T cells significantly increased after allopurinol treatment and decreased to background levels following benznidazole administration in a substantial proportion of subjects evaluated. The levels of total naive (CD45RA + CCR7 + CD62L+) CD4 + and CD8 + T cells were restored after allopurinol administration and maintained after completion of the combined drug protocol, along with a decrease in T cell activation in total peripheral CD4 + and CD8 + T cells.

CONCLUSIONS

This pilot study shows that the combination of allopurinol and benznidazole induces significant modifications in T and B cell responses indicative of a reduction in parasite burden, and sustains the feasibility of administration of two antiparasitic drugs in the chronic phase of Chagas' disease.

Seronegative conversion after incomplete benznidazole treatment in chronic Chagas disease

In 12-18% of adult patients, treatment with benznidazole for chronic Chagas disease has to be discontinued because of side-effects. We identified and analysed a cohort of 81 adult patients with three positive tests for Trypanosoma cruzi infection and serological monitoring following incomplete treatment with benznidazole for a median of 10 days. Twenty percent of these patients (16/81) met the criteria of cure, showing that the optimal schedule of benznidazole administration remains to be determined.

Impact of aetiological treatment on conventional and multiplex serology in chronic Chagas disease

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.

Therapy, diagnosis and prognosis of chronic Chagas disease: insight gained in Argentina

The purpose of this review is to describe research findings regarding chronic Chagas disease in Argentina that have changed the standards of care for patients with Trypanosoma cruzi infection. Indirect techniques (serological tests) are still the main tools for the primary diagnosis of infection in the chronic phase, but polymerase chain reaction has been shown to be promising. The prognosis of patients with heart failure or advanced stages of chagasic cardiomyopathy is poor, but a timely diagnosis during the initial stages of the disease would allow for prescription of appropriate therapies to offer a better quality of life. Treatment of T. cruzi infection is beneficial as secondary prevention to successfully cure the infection or to delay, reduce or prevent the progression to disease and as primary disease prevention by breaking the chain of transmission. Current recommendations have placed the bulk of the diagnostic and treatment responsibility on the Primary Health Care System. Overall, the current research priorities with respect to Chagas disease should be targeted towards (i) the production of new drugs that would provide a shorter treatment course with fewer side effects; (ii) the development of new tools to confirm cure after a full course of treatment during the chronic phase and (iii) biomarkers to identify patients with a high risk of developing diseases.

The impact of socioeconomic conditions on chronic Chagas disease progression

INTRODUCTION AND OBJECTIVES

The extent to which a patient's socioeconomic conditions determine the persistence or control of chronic Chagas disease has not been previously investigated. The aim of this study was to evaluate the effect of socioeconomic conditions on clinical and serologic measures of disease progression.

METHODS

Data on the following socioeconomic variables were obtained by questioning as part of medical history taking at admission: birth in a rural area, time of residence in endemic and urban areas (in years), overcrowding index (i.e. number of inhabitants/number of bedrooms), absence of toilet facilities, years of education, employed or unemployed, and health insurance coverage (i.e. private contributory medical insurance cover). The study endpoints for the Cox regression analysis were: consistently negative results on serologic tests and on tests for markers of cardiomyopathy progression by the end of the study.

RESULTS

The study included 801 Argentine patients (mean age 42 years) who were followed up for a mean of 10 years between 1990 and 2005. After adjustment for age and antiparasitic treatment, negative seroconversion was associated with a short time of residence in an endemic area (hazard ratio [HR]=0.97; 95% confidence interval [CI], 0.96-0.99; P=.004), a low overcrowding index (HR=0.82; 95% CI, 0.70-0.97; P=.022) and medical insurance cover (HR=1.46; 95% CI, 1.01-2.09; P=.04). After adjustment for age, sex, ECG abnormalities and antiparasitic treatment, a low rate of cardiomyopathy progression was associated with more years of education (HR=0.88; 95% CI, 0.80-0.97; P=.01) and higher medical insurance cover (HR=0.49; 95% CI, 0.30-0.81; P=.005).

CONCLUSIONS

Socioeconomic conditions had a significant effect on chronic Chagas disease progression which was independent of antiparasitic treatment and clinic characteristics.

Changes in Trypanosoma cruzi-specific immune responses after treatment: surrogate markers of treatment efficacy

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.

Chronic human infection with Trypanosoma cruzi drives CD4+ T cells to immune senescence

Previously we found that the frequency of IFN-gamma-producing CD8(+) T cells specific for Trypanosoma cruzi inversely correlates with disease severity in chronic human Chagas disease along with low levels of IL-2-secreting CD8(+) T cells in all clinical stages. This impairment of the parasite-specific T cell responses was associated with phenotypic features of immune senescence of the CD8(+) T cell compartment. These data prompted us to address the question of whether the CD4(+) T cell compartment also experiences signs of exhaustion. Thus, we performed a functional and phenotypical characterization of T. cruzi-specific and overall CD4(+) T cells in chronically infected subjects with different degrees of cardiac dysfunction. The results show an inverse association between disease severity and the frequency of T. cruzi-specific IFN-gamma-producing CD4(+) T cells. The high expression of CD27 and CD28 with a relative low expression of CD57 found on CD4(+)IFN-gamma(+) T cells suggests that the effector T cell pool in chronic T. cruzi infection includes a high proportion of newly recruited T cells, but a low frequency of long-term memory cells. The total CD4(+) T cell compartment shows signs of senescence and later stages of differentiation associated with more severe stages of the disease. These findings support the hypothesis that long-term T. cruzi infection in humans might exhaust long-lived memory T cells.

[Predictors of heart failure in chronic chagasic cardiomyopathy with asymptomatic left ventricular dysfunction]

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.

Etiological treatment of chronic Chagas disease: neglected 'evidence' by evidence-based medicine

No randomized clinical trials regarding the etiological treatment of chronic Chagas disease can be found in the medical literature. However, other 'evidence' sustaining the use of anti-Trypanosoma cruzi drugs for adult individuals with Chagas disease will be analyzed along with the limitations in evaluating the treatment efficacy. Today, the hypothesis of T. cruzi persistence in the target organs giving rise to the chronic inflammatory response is sustained. In addition, several experimental, pathological, nonrandomized clinical studies and studies based on the response or serological evolution (besides the clinical experience) demonstrate the role of T. cruzi in the pathogenesis of the chronic stage and the efficacy of etiological treatment to reduce the titers of antibodies and the progression of chronic Chagas heart disease. All of this supports the recommendation of treatment for every patient diagnosed with Chagas disease. The interpretation of this sum of evidence is not considered from the perspective of evidence-based medicine.

Is manual dexterity essential in the selection of dental students?

OBJECTIVE

The purpose of this study was to determine whether basic manual dexterity (BMD) could be an important parameter in selecting students for the Degree in Dentistry (CLOPD) and to assess whether initial manual dexterity in students admitted to the CLOPD can improve with training in pre-clinical and clinical practice.

DESIGN

Observational study.

SETTING

The study was carried out at the Catholic University of Rome, in five consecutive academic years.

SUBJECTS AND METHODS

Four hundred and thirty-three subjects (262 males and 171 females) were tested (10 different exercises) in five consecutive years. Two retests were performed after three and five years respectively from the beginning of the experimentation.

MAIN OUTCOME MEASURES

The scores of individual exercises were averaged for each candidate, assessing the mean value of basic manual dexterity score (BMDS).

RESULTS

It was possible to observe some differences among candidates coming from different types of high schools, since those having a prior university degree or a scientific high school degree proved better than those with classical or vocational high school qualifications (p < 0.05). A statistically significant improvement of BMDS has been observed in students who attended the CLOPD for at least 32 months.

CONCLUSIONS

Data obtained revealed that basic manual dexterity is not essential in the selection of dental students. Students who could follow training significantly improved in their manual ability.

Long-term cardiac outcomes of treating chronic Chagas disease with benznidazole versus no treatment: a nonrandomized trial

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.

[Clinical predictors of chronic chagasic myocarditis progression]

INTRODUCTION AND OBJECTIVES

Previous prognostic studies of Chagas' disease have focused on mortality associated with end-stage cardiopathy (i.e., heart failure). Our aim was to identify indicators of progression in early-stage Chagas' heart disease.

MATERIAL AND METHOD

The study included 856 patients with 3 positive anti-Trypanosoma cruzi test results. Those with heart failure were excluded. Patients were divided into 3 clinical groups: those without heart disease (Group I); those with heart disease but without left ventricular enlargement (Group II); and those with left ventricular enlargement but without heart failure (Group III). The endpoint was progression to a more severe clinical stage or death due to cardiovascular disease. A Cox regression model was used to derive a clinical risk score from clinical, electrocardiographic and echocardiographic variables.

RESULTS

At study entry, the patients' mean age was 43.7 years. They were followed up for a mean of 8 years. The following were predictors of heart disease progression: age at entry (HR=1.05; 95% CI, 1.02-1.07; P<.001), left ventricular systolic diameter (HR=1.06; 95% CI, 1.04-1.09; P<.001), intraventricular conduction abnormalities (HR=1.85; 95% CI, 1.02-3.36; P=.04), and sustained ventricular tachycardia (HR=3.97; 95% CI, 1.65-9.58; P=.002). Treatment with benznidazole reduced the risk of progression (HR=0.40; 95% CI, 0.23-0.72; P=.002). The devised clinical risk score was effective in stratifying the likelihood of cardiopathy progression.

CONCLUSIONS

Specific clinical indicators and a derived clinical risk score can be used to predict the progression of chronic chagasic myocarditis in patients without heart failure.

[Treatment of Chagas disease with benznidazole and thioctic acid]

A multicenter, randomized, triple blind and controlled trial was designed to determine whether the combination with thioctic acid (TA), an antioxidant agent, can reduce the intolerance rate to Benznidazol (BZ) in patients infected with Trypanosoma cruzi. Four regimens were assigned randomly for 3 age intervals, administrating placebo or TA orally at daily doses of 50 to 100 mg in association with BZ at a dose of 5 mg/k/day for 30 days. In some, medication was given during a run-in period. Safety controls were carried out on days 10, 20, 37 and 52 days after therapy initiation. A total of 249 patients between 15 and 44 years old were enrolled. At the end of the trial, 70.3% of the patients had completed the treatment, while 17.7% required its suspension due to BZ related adverse reactions. The proportion of individuals affected with at least one side effect ranged from 54.8% to 58%; however, none were serious. Reported side effects included: cutaneous maculopapular rush (28%), pruritus (13.6%), headache (8%), epigastralgia (6.2%), fever (6.2%), fatigue (4.3%), nausea (4%), myalgias (4.3%), others (21.5%). The incidence of these reactions did not differ significantly among the 4 therapeutic regimens, nor even among the age intervals considered. It can be concluded that the association with TA did not prevent the occurrence of adverse reactions related to BZ administration. However, a single month cycle of this parasiticide permitted a high compliance rate to therapy among infected outpatients.

Treatment of chronic Chagas' disease with benznidazole: clinical and serologic evolution of patients with long-term follow-up

Prescribing etiologic treatment for chronic Chagas' disease is highly controversial because of the difficulties involved in assessing its therapeutic efficacy--the low degree of parasitemia, the persistence of positive immunologic reactions, the lack of clinical findings to support each type of treatment, and the necessarily prolonged follow-up of the patient. An 8-year average follow-up was performed on 131 patients treated with benznidazole (5 mg/kg/day for 30 days) (TP) and 70 untreated patients (UTP) by serial electrocardiograms and analysis of the cardiomyopathic progress of the clinical groups, and by immunologic tests at both the beginning and end of the study. TPs presented less electrocardiographic changes during the follow-up period (4.2% vs 30%) and a lower frequency of deterioration in their clinical condition (2.1% vs 17%). The percentage of TPs who were serologically negative was 19.1% whereas 6% of the UTPs became serologically negative, a result that correlated with a lack of progress in the cardiomyopathy. Benznidazole treatment significantly decreased serologic titers, signifying parasitologic cure in two patients.