Chronic Chagas Disease-the Potential Role of Reinfections in Cardiomyopathy Pathogenesis.

PURPOSE OF THE REVIEW: Chagas disease is a neglected anthropozoonosis of global importance with significant cardiovascular-associated mortality. This review focuses on the Trypanosoma cruzi reinfections' role in chronic Chagas cardiomyopathy pathogenesis. We discuss and summarize the available data related to pathology, pathogenesis, diagnosis, and treatment of reinfections. RECENT FINDINGS: Reinfections influence the genetic and regional diversity of T. cruzi, tissue tropism, modulation of the host's immune system response, clinical manifestations, the risk for congenital infections, differences in diagnostics performances, response to antiparasitic therapy, and the natural history of the disease. Animal models suggest that reinfections lead to worse outcomes and increased mortality, while other studies showed an association between reinfections and lower parasitemia levels and subsequent infection protection. In some regions, the human risk of reinfections is 14% at 5 years. Evidence has shown that higher anti-T. cruzi antibodies are correlated with an increased rate of cardiomyopathy and death, suggesting that a higher parasite exposure related to reinfections may lead to worse outcomes. Based on the existing literature, reinfections may play a role in developing and exacerbating chronic Chagas cardiomyopathy and are linked to worse outcomes. Control efforts should be redirected to interventions that address structural poverty for the successful and sustainable prevention of Chagas disease.

Chagas Cardiomyopathy in Latin America Review.

PURPOSE OF REVIEW: Chagas cardiomyopathy is a major public health disease in Latin America and, due to migration, is becoming a worldwide health and economic burden. This review sought to present the clinical and epidemiological aspects of Chagas cardiomyopathy, as well as some specific features and principles of treatment. We also retrospectively assessed our institutional experience with mechanical circulatory support in refractory heart failure due to Chagas cardiomyopathy over a 10-year period. RECENT FINDINGS: The role of antiparasitic treatment in patients with heart failure due to Chagas cardiomyopathy is controversial. Heart transplantation, although formerly contraindicated, is currently established as an important therapeutic option. Also, the favorable characteristics of Chagas patients, such as younger age, little comorbidity, and no reoperations or severe pulmonary hypertension, could be an advantage for a mechanical circulatory support indication in advanced heart failure due to Chagas cardiomyopathy. Despite the absence of large evidence-based data, much has been accomplished since Carlos Chagas' discovery one century ago. Our institutional experience shows that mechanical circulatory support in Chagas patients is associated with more successful bridging to heart transplantation when compared to non-Chagas patients.

Heart transplant outcomes in patients with Chagas cardiomyopathy in the United States.

BACKGROUND: Chagas cardiomyopathy (CC) is one of the chronic manifestations of Trypanosoma cruzi (T. cruzi) infection and is among the leading reasons for heart transplantation (HT) in Latin America. Chagas disease is also present in areas with large Hispanic communities in the United States. Our objective is to evaluate the outcomes of cardiac allograft recipients with the diagnosis of CC in the United States. METHODS AND RESULTS: We identified 25 adult patients with CC and 15 930 with idiopathic dilated cardiomyopathy (IDCMP) who underwent HT between 1987 and 2015. CC patients were mostly Hispanics, had lower mean pulmonary artery pressure (23 vs 29 mm Hg, P = .035) and lower BMI (24 vs 26, P = .007). Patients with CC were more likely to be supported with a total artificial heart (TAH) as bridge to transplant (P = .009). There were no statistical differences for overall mortality and graft survival between CC and IDCMP cardiac allograft recipients. Induction therapy and mycophenolate mofetil (MMF) use were associated with higher rate of infection in Chagas patients. CONCLUSIONS: Heart transplantation recipients with CC diagnosis appear to have similar outcomes to IDCMP patients. Induction therapy and MMF use may be associated with higher risk of infection in CC patients who underwent transplantation.

Chronic Chagas cardiomyopathy: a review of the main pathogenic mechanisms and the efficacy of aetiological treatment following the BENznidazole Evaluation for Interrupting Trypanosomiasis (BENEFIT) trial.

Chagas cardiomyopathy is the most frequent and most severe manifestation of chronic Chagas disease, and is one of the leading causes of morbidity and death in Latin America. Although the pathogenesis of Chagas cardiomyopathy is incompletely understood, it may involve several mechanisms, including parasite-dependent myocardial damage, immune-mediated myocardial injury (induced by the parasite itself and by self-antigens), and microvascular and neurogenic disturbances. In the past three decades, a consensus has emerged that parasite persistence is crucial to the development and progression of Chagas cardiomyopathy. In this context, antiparasitic treatment in the chronic phase of Chagas disease could prevent complications related to the disease. However, according to the results of the BENEFIT trial, benznidazole seems to have no benefit for arresting disease progression in patients with chronic Chagas cardiomyopathy. In this review, we give an update on the main pathogenic mechanisms of Chagas disease, and re-examine and discuss the results of the BENEFIT trial, together with its limitations and implications.

Heart transplant recipient with history of Chagas disease and elevated panel-reactive antibodies.

Chagas disease is caused by a protozoan named Trypanosoma cruzi transmitted to humans by reduviid bugs. Severe dilated cardiomyopathy from chronic T cruzi infection is the most common finding, leading to end-stage heart failure. Heart transplant is an effective treatment for Chagas heart disease. However, T cruzi reactivation is of great concern, predisposing patients to episodes of myocarditis and rejection. A 56-year-old woman with a history of Chagas disease and elevated calculated panel reactive antibodies (CPRAs) underwent induction therapy and desensitization strategies aimed at lowering CPRAs, as elevated CPRAs have been implicated in the development of antibody-mediated rejection and reduced allograft survival. Clinical phases and signs and symptoms of Chagas disease are briefly described in an attempt to promote awareness of the disease among clinicians. In addition, serology assays approved in the United States as well as recommendations of experts on Chagas disease to assess tissues and blood specimens from endemic areas are outlined. Ultimately, the importance of ongoing surveillance is emphasized, as the future of heart transplant recipients with Chagas disease is unpredictable and the presence or reactivation of the disease requires prompt attention in an effort to prevent graft failure and death.

Case Report: A Case of Post-Transplant Chagas Reactivation after Negative Trypanosoma cruzi Testing.

Patients with Chagas cardiomyopathy carry a significant risk of reactivation after heart transplantation. Reactivation of Chagas disease can lead to graft failure or systemic complications such as fulminant central nervous system disease and sepsis. As such, careful screening for Chagas seropositivity prior to transplant is crucial to preventing negative outcomes in the post-transplant setting. One challenge in screening these patients is the variety of laboratory tests available and their differing sensitivities and specificities. In this case report, we present a patient who tested positive by a commercial Trypanosoma cruzi antibody assay and later tested negative by CDC confirmatory serological analysis. After the patient underwent orthotopic heart transplant, he underwent protocol-based polymerase chain reaction surveillance for reactivation as a result of persistent concerns for T. cruzi infection. It was discovered shortly thereafter that the patient had reactivation of Chagas disease, confirming that he did have Chagas cardiomyopathy prior to transplantation, despite negative confirmatory testing. This case illustrates the complexities of serological diagnosis of Chagas disease and the importance of additional testing for T. cruzi when the post-test probability remains high even with a commercial, negative serologic test.

Chronic Chagas' heart disease: a disease on its way to becoming a worldwide health problem: epidemiology, etiopathology, treatment, pathogenesis and laboratory medicine.

Chagas' disease, caused by Trypanosoma cruzi infection, is ranked as the most serious parasitic disease in Latin America. Nearly 30% of infected patients develop life-threatening complications, and with a latency of 10-30 years, mostly Chagas' heart disease which is currently the major cause of morbidity and mortality in Latin America, enormously burdening economic resources and dramatically affecting patients' social and labor situations. Because of increasing migration, international tourism and parasite transfer by blood contact, intrauterine transfer and organ transplantation, Chagas' heart disease could potentially become a worldwide problem. To raise awareness of this problem, we reflect on the epidemiology and etiopathology of Chagas' disease, particularly Chagas' heart disease. To counteract Chagas' heart disease, in addition to the general interruption of the infection cycle and chemotherapeutic elimination of the infection agent, early and effective causal or symptomatic therapies would be indispensable. Prerequisites for this are improved knowledge of the pathogenesis and optimized patient management. From economic and logistics viewpoints, this last prerequisite should be performed using laboratory medicine tools. Consequently, we first summarize the mechanisms that have been suggested as driving Chagas' heart disease, mainly those associated with the presence of autoantibodies against G-protein-coupled receptors; secondly, we indicate new treatment strategies involving autoantibody apheresis and in vivo autoantibody neutralization; thirdly, we present laboratory medicine tools such as autoantibody estimation and heart marker measurement, proposed for diagnosis, risk assessment and patient guidance and lastly, we critically reflect upon the increase in inflammation and oxidative stress markers in Chagas' heart disease.

Stroke history and Chagas disease are independent predictors of silent cerebral microembolism in patients with congestive heart failure.

BACKGROUND: Chagas disease is endemic in South and Central America, where 18 million individuals are infected by Trypanosoma cruzi, causing congestive heart failure (CHF) and cardioembolic stroke. Transcranial Doppler (TCD) is able to detect real-time microembolic signals (MES) to the brain vessels and may represent a surrogate marker of stroke risk. We aimed to determine predictors of MES in a population of patients with CHF. METHODS: Consecutive CHF patients from a university-based cardiomyopathy clinic underwent TCD recording of the middle cerebral artery for 60 min by a single investigator who was blinded to all clinical data including cardiomyopathy etiology. Predictors of MES were sought by multivariable logistic regression analysis. RESULTS: From April 2004 to February 2009, 144 patients were studied, including 62 (44.6%) patients with Chagas disease. MES were detected in 9 (6.2%) patients and were more frequent in patients with Chagas disease than in patients with other causes of CHF (12.9 vs. 1.2%, p = 0.005). In multivariate analysis corrected for age and left-ventricular ejection fraction, predictors of MES were Chagas disease (odds ratio = 1.15, 95% confidence interval = 1.05-1.26, p = 0.004) and stroke history (odds ratio = 1.27, 95% confidence interval = 1.08-1.50, p = 0.005). CONCLUSIONS: Chagas disease and stroke history are risk factors for MES independent of cardiac disease severity. Other mechanisms besides structural cardiac disease may be operative, increasing embolic risk in Chagas disease.

Autoantibodies against the immunodominant sCha epitope discriminate the risk of sudden death in chronic Chagas cardiomyopathy.

In Chagas disease (ChD) caused by Trypanosoma cruzi, new biomarkers to predict chronic cardiac pathology are urgently needed. Previous studies in chagasic patients with mild symptomatology showed that antibodies against the immunodominant R3 epitope of sCha, a fragment of the human basic helix-loop-helix transcription factor like 5, correlated with cardiac pathology. To validate sCha as a biomarker and to understand the origin of anti-sCha antibodies, we conducted a multicenter study with several cohorts of chagasic patients with severe cardiac symptomatology. We found that levels of antibodies against sCha discriminated the high risk of sudden death, indicating they could be useful for ChD prognosis. We investigated the origin of the antibodies and performed an alanine scan of the R3 epitope. We identified a minimal epitope MRQLD, and a BLAST search retrieved several T. cruzi antigens. Five of the hits had known or putative functions, of which phosphonopyruvate decarboxylase showed the highest cross-reactivity with sCha, confirming the role of molecular mimicry in the development of anti-sCha antibodies. Altogether, we demonstrate that the development of antibodies against sCha, which originated by molecular mimicry with T. cruzi antigens, could discriminate electrocardiographic alterations associated with a high risk of sudden death.

MICA and KIR: Immunogenetic Factors Influencing Left Ventricular Systolic Dysfunction and Digestive Clinical Form of Chronic Chagas Disease.

Tissue damage observed in the clinical forms of chronic symptomatic Chagas disease seems to have a close relationship with the intensity of the inflammatory process. The objective of this study was to investigate whether the MICA (MHC class I-related chain A) and KIR (killer cell immunoglobulin-like receptors) polymorphisms are associated with the cardiac and digestive clinical forms of chronic Chagas disease. Possible influence of these genes polymorphisms on the left ventricular systolic dysfunction (LVSD) in patients with chronic Chagas heart disease was also evaluated. This study enrolled 185 patients with positive serology for Trypanosoma cruzi classified according to the clinical form of the disease: cardiac (n=107) and digestive (n=78). Subsequently, patients with the cardiac form of the disease were sub-classified as with LVSD (n=52) and without LVSD (n=55). A control group was formed of 110 healthy individuals. Genotyping was performed by polymerase chain reaction-sequence specific oligonucleotide probes (PCR-SSOP). Statistical analyzes were carried out using the Chi-square test and odds ratio with 95% confidence interval was also calculated to evaluate the risk association. MICA-129 allele with high affinity for the NKG2D receptor was associated to the LVSD in patients with CCHD. The haplotype MICA*008~HLA-C*06 and the KIR2DS2-/KIR2DL2-/KIR2DL3+/C1+ combination were associated to the digestive clinical form of the disease. Our data showed that the MICA and KIR polymorphisms may exert a role in the LVSD of cardiac patients, and in digestive form of Chagas disease.

Molecular mimicry between the immunodominant ribosomal protein P0 of Trypanosoma cruzi and a functional epitope on the human beta 1-adrenergic receptor.

Sera from chagasic patients possess antibodies recognizing the carboxy-terminal part of the ribosomal P0 protein of Trypanosoma cruzi and the second extracellular loop of the human beta 1-adrenergic receptor. Comparison of both peptides showed that they contain a pentapeptide with very high homology (AESEE in P0 and AESDE in the human beta 1-adrenergic receptor). Using a competitive immunoenzyme assay, recognition of the peptide corresponding to the second extracellular loop (H26R) was inhibited by both P0-14i (AAAESEEEDDDDDF) and P0-beta (AESEE). Concomitantly, recognition of P0-beta was inhibited with the H26R peptide. Recognition of P0 in Western blots was inhibited by P0-14i, P0-beta, and H26R, but not by a peptide corresponding to the second extracellular loop of the human beta 2-adrenergic receptor or by an unrelated peptide. Autoantibodies affinity purified with the immobilized H26R peptide were shown to exert a positive chronotropic effect in vitro on cardiomyocytes from neonatal rats. This effect was blocked by both the specific beta 1 blocker bisoprolol and the peptide P0-beta. These results unambiguously prove that T. cruzi is able to induce a functional autoimmune response against the cardiovascular human beta 1-adrenergic receptor through a molecular mimicry mechanism.

Prevalence of Chagas heart disease in dilated cardiomyopathy.

OBJECTIVES: The main objective is to determine the prevalence of American trypanosomiasis in patients with dilated cardiomyopathy in a tertiary hospital in western Mexico. METHODS: From January 1991 to February 2016, 387 consecutive patients with a confirmed diagnosis of dilated cardiomyopathy were included in the study. Cases with ventricular dilatation secondary to ischemic heart disease, valvular heart disease, hypertension, lung disease, pericardial disease, or congenital heart disease were excluded from the study. Diagnosis was made detecting antibodies against Trypanosoma cruzi with two different methods or parasite in blood. RESULTS: Were included 387 patients with dilated cardiomyopathy, Chagas cardiomyopathy was confirmed in 6.9%, two patients in the acute phase (in one, suspected transfusion transmission was detected). Most patients were born in rural areas. About 96.2% showed congestive heart failure, only one patient with apical left ventricular aneurysm manifested palpitations. About 66% with right bundle branch block, left anterior fascicular block, or the association of both, in 14.8%, non-sustained ventricular tachycardia was found. CONCLUSIONS: Chagas cardiomyopathy is common in México, mainly in people who were born or lived during childhood in rural areas. It is a common cause of heart failure. Chagas' heart disease should be suspected in patients receiving a blood transfusion, even without another epidemiological history.

Lack of Association of IL6 polymorphism with the susceptibility to Chagas disease in Latin American populations.

The aim of the present study was to analyze IL6 rs1800795 genetic variant in the susceptibility to Trypanosoma cruzi infection and in the development of chronic Chagas cardiomyopathy (CCC), in five independent Latin American cohorts. A total of 3,087 individuals from Latin American countries (Argentina, Bolivia, Peru, and two cohorts from Colombia) were studied. In all cohorts, patients were classified as seropositive for T. cruzi antigens (n= 1,963) and seronegative (n= 1,124). Based on clinical evaluation, the seropositive patients, were classified as CCC (n= 900) and asymptomatic (n= 1,063). No statistically significant differences in the frequency of IL6 rs1800795 between seropositive and seronegative, or between CCC and asymptomatic patients, were found. Furthermore, after the meta-analysis no statistically significant differences were observed. Our results do not support a contribution of IL6 rs1800795 genetic variant in the susceptibility to the infection and the development of chronic Chagas cardiomyopathy in the studied populations.

Myocardial Involvement in Chagas Disease and Insulin Resistance: A Non-Metabolic Model of Cardiomyopathy.

Background: Heart failure (HF) and type 2 Diabetes Mellitus (T2DM) represent two chronic interrelated conditions accounting for significant morbidity and mortality worldwide. Insulin resistance (IR) has been identified as a risk factor for HF; however, the risk of IR that HF confers has not been well elucidated. The present study aims to analyze the association between myocardial involvement in Chronic Chagas Cardiomyopathy (CCM) and IR, taking advantage of this non-metabolic model of the disease. Methods: Cross-sectional study performed during the period 2015-2016. Adults with a serological diagnosis of Chagas disease were included, being divided into two groups: CCM and non-CCM. IR was determined by HOMA-IR index. Bivariate analysis and multivariate logistic regression were performed to determine the association between IR as an outcome and CCM as primary exposure. Results: 200 patients were included in the study, with a mean age of 54.7 years and a female predominance (53.5%). Seventy-four (37.0%) patients were found to have IR, with a median HOMA-IR index of 3.9 (Q1 = 3.1; Q3 = 5.1). Multiple metabolic variables were significantly associated with IR. In a model analyzing only individuals with an altered HWI, an evident association between CCM and IR was observed (OR 4.08; 95% CI 1.55-10.73, p = 0.004). Conclusion: CCM was significantly associated with IR in patients with an altered HWI. The presence of this association in a non-metabolic model of HF (in which the myocardial involvement is expected to be mediated mostly by the parasitic infection) may support the evidence of a direct unidirectional correlation between this last and IR.

Pediatric clinical pharmacology studies in Chagas disease: focus on Argentina.

Chagas disease is a neglected parasitic disease endemic in the Americas. It mainly affects impoverished populations and the acute phase of the infection mostly affects children. Many cases have also been detected in nonendemic countries as a result of recent migratory trends. The chronic phase is relatively asymptomatic, but 30% of patients with chronic infection eventually develop cardiac and digestive complications that commonly lead to death or disability. Only two drugs are available for the treatment of Chagas disease, benznidazole and nifurtimox. These drugs have been shown to be effective in the treatment of both acute and early chronic phases in children, but the pharmacokinetics of these drugs have never been studied in this population. We have set out to conduct a pharmacokinetics study of benznidazole in a pediatric population with Chagas disease. The results of this study are expected to allow better estimation of the optimal doses and schedule of pharmacotherapy for Chagas disease in children.

Chagas heart disease pathogenesis: one mechanism or many?

Chagas heart disease (CHD), caused by the protozoan parasite Trypanosoma cruzi, is the leading cause of infectious myocarditis in the world. The etiology of CHD is unclear and multiple mechanisms have been proposed to explain the pathogenesis of the disease. This review describes the proposed mechanisms of CHD pathogenesis and evaluates the historical significance and evidence supporting each. Although the majority of CHD-related pathologies are currently attributed to parasite persistence in the myocardium and autoimmunity, there is strong evidence that CHD develops as a result of additive and even synergistic effects of several distinct mechanisms rather than one factor.

Pathology and Pathogenesis of Chagas Heart Disease.

Chagas heart disease is an inflammatory cardiomyopathy that develops in approximately one-third of people infected with the protozoan parasite Trypanosoma cruzi. One way T. cruzi is transmitted to people is through contact with infected kissing bugs, which are found in much of the Western Hemisphere, including in vast areas of the United States. The epidemiology of T. cruzi and Chagas heart disease and the varied mechanisms leading to myocyte destruction, mononuclear cell infiltration, fibrosis, and edema in the heart have been extensively studied by hundreds of scientists for more than 100 years. Despite this wealth of knowledge, it is still impossible to predict what will happen in an individual infected with T. cruzi because of the tremendous variability in clonal parasite virulence and human susceptibility to infection and the lack of definitive molecular predictors of outcome from either side of the host-parasite equation. Further, while several distinct mechanisms of pathogenesis have been studied in isolation, it is certain that multiple coincident mechanisms combine to determine the ultimate outcome. For these reasons, Chagas disease is best considered a collection of related but distinct illnesses. This review highlights the pathology and pathogenesis of the most common adverse sequela of T. cruzi infection-Chagas heart disease-and concludes with a discussion of key unanswered questions and a view to the future.

Case Report: High Mannose-Binding Lectin Serum Determined by MBL2 Genotype and Risk for Clinical Progression to Chagasic Cardiomyopathy: A Case Report of Three Patients.

Chagas disease (CD), caused by infection with the parasite Trypanosoma cruzi, leads to severe cardiomyopathy in 20-30% of patients, whereas the remainder may stay asymptomatic and never develop cardiomyopathy or other clinical manifestations. The underlying cause for this variable outcome is not fully characterized, although previous studies have found high levels of circulating mannose-binding lectin (MBL) to be associated with cardiac failure echocardiographic changes. We report three indeterminate (asymptomatic) chronic Chagas patients who were followed up for 10 years. Two of these patients developed chronic chagasic cardiomyopathy (CCC) during this follow-up period and, when genotyped, were found to be carriers of the high MBL producer HYPA/HYPA genotype, suggesting that genetically determined high MBL serum might be associated with the risk of CCC development. These results suggest the use of MBL quantification and MBL2 genotyping as tools for clinical assessment in patients with chronic CD.

A retrospective study on the influence of siblings' relatedness in Bolivian patients with chronic Chagas disease.

BACKGROUND: Chagas disease is a protozoan infection caused by Trypanosoma cruzi. The disease has a chronic course in which 20-30% of the patients would develop progressive damage to the cardiovascular system and the gastrointestinal tube. We are still unable to predict who will develop end-organ damage but there are some acquired and genetic risk factors already known. RESULTS: We reviewed data from 833 patients with serologically confirmed Chagas disease in this retrospective study. Patients were classified as siblings or non-siblings (controls) and the results of pre-treatment blood PCR assay, end-organ damage (cardiac and/or gastrointestinal), and the presence of delayed type hypersensitivity (DTH) skin involvement in patients treated with benznidazole were analyzed. Siblings were grouped by family and we randomly generated groups of 2 or 3 persons with the remaining controls. We classified the results of each variable as concordant or discordant and compared the concordance in these results among the sibling groups with that among control groups. We identified 71 groups of siblings and randomly generated 299 groups of non-related patients. Pre-treatment blood PCR concordance was significantly higher (19%) among siblings compared to controls (P = 0.02), probably due to a higher frequency in pre-treatment positive results. No other statistically significant differences were found. CONCLUSIONS: A significant difference was found in the concordance of pre-treatment blood PCR for T. cruzi among siblings compared to non-related controls.