Chronic Chagas Disease Research Articles

Evaluation of parasitemia by qPCR in patients with chronic Chagas disease treated with benznidazole

Objective: To evaluate parasitemia by qPCR in patients undergoing etiological treatment and followed in a Brazilian reference center. Methods: Parasite load was quantified by qPCR in 32 participants with chronic Chagas disease who were treated with benznidazole. Serological analyses were performed before and after the treatment and parasite loads were compared prior and 12/18 months post the treatment. Results: Thirty-two participants were recruited and treated with benznidazole, and 20 were followed-up. Adverse events (AE) were observed in 22 out of 29 participants that had safety data (76%), and dermatological alterations were the most frequently observed AE. Of the 20 participants analyzed, 13 and 7 completed 12 and 18 months follow-up after the treatment, respectively. 12 Months after the final treatment, Trypanosoma cruzi was detectable in 3 patients by qPCR; 18 months after the final treatment, Trypanosoma cruzi was detectable per qPCR in 4 of the 7 participants. Thus, between 12 and 18 months, 7 participants of the 20 initial follow-up cases showed positive qPCR, indicating treatment failures. Conclusions: qPCR can be used as an alternative method for evaluating the effectiveness of the etiological treatment of CD, and can be applied to analyze early therapeutic failures. The study showed that benznidazole therapy had limited effectiveness in treating chronic CD patients, thus emphasizing the importance of conducting continued research for developing more effective therapies and diagnosis for CD.

Chagas Disease, A Review of the Literature

Chagas disease is a vector-borne (triatomine) infection caused by the protozoan parasite Trypanosoma cruzi. Synonyms for this disease are: American trypanosomiasis, Chagas disease and T. cruzi infection. 10, 5 The most common form of transmission of Chagas disease is through hematophagous triatomine insects (triatominae), which develop in dwellings in precarious conditions, The disease can also be transmitted by blood transfusion, organ transplantation, oral and congenital routes, and even more rarely by exceptional routes such as sexual contact and non-Triatominae vectors. American Trypanosomiasis is endemic in much of Mexico, Central and South America 1,11. it is estimated that ~6 million individuals are infected throughout Latin America, while ~300,000 are infected in the U.S.1, 10, 11,16 Chagas disease has two clearly differentiated phases. Initially, the acute phase lasts about two months after infection, they may have a skin lesion or a purplish swelling of an eyelid, they may have fever, headache, enlarged lymph nodes, pallor, muscle aches, shortness of breath, swelling, and abdominal or chest pain. During the chronic phase, the infection can cause sudden death due to cardiac arrhythmias or progressive heart failure due to destruction of the cardiac muscle and its innervations. 15 Appropriate diagnostics for acute infection, nucleic acid amplification testing (NAAT) from blood is recommended; For chronic infection, serological testing is employed. Antitrypanosomal agents, benznidazole and nifurtimox, have shown efficacy in treating T. cruzi infection, The most serious complication is chronic chagasic heart disease, since it is the main cause of death in sick patients. 16

Reactivation of Tumor-like Chagas Disease in the Central Nervous System in Cardiac Transplant Patients: A Case Series and Literature Review

Abstract Introduction Chagas disease is an important public health problem in Latin American countries, affecting ∼ 6 million people within the region. In patients with chronic Chagas disease who undergo some type of immunosuppression reactivation of the acute form may occur, and manifestations involve many organs, including the central nervous system. Tumor-like brain reactivations are well described in patients with acquired immunodeficiency syndrome; however, this is a very rare event among Chagasic patients immunosuppressed after a heart transplantation. Case Report We describe three cases of cardiac transplant patients who had a tumor-like intracranial lesion, whose biopsies were compatible with Chagas disease. All 3 patients were treated with benznidazole, and 2 of them presented parameters of cure after 60 days of treatment, while 1 required a 2nd cycle of treatment. Discussion A tumor-like Chagas disease reactivation in the central nervous system may happen in heart-transplant patients and, due to the multiple differential diagnoses, we believe that brain biopsies should be considered when feasible.

Abstract 11704: Conduction Abnormalities Among Chronic Chagas’ Disease Patients With Heart Involvement and Events of Cardiogenic Shock

Introduction: Chronic Chagas Cardiomyopathy can disrupt various conduction pathways, triggering arrhythmias and cardiogenic shock (CS). The American Heart Association recently advocated for better global awareness in endemic regions. We aim to provide a perspective on cardiac arrhythmias seen in Chronic Chagas disease with heart involvement in the United States. Methods: Cases of “Chagas' disease (chronic) with heart involvement” were used via the 2016-2020 National Inpatient Sample. The presence of several cardiac arrhythmias was analyzed. Results: Between 1st January 2016 to 31st December 2020, around 1920 patients were hospitalized with Chronic Chagas’ disease with heart involvement in the United States. The cases were predominantly Males (61.2%) who were also younger compared to Females (mean age of Males: 55.83 years vs. mean age of Females 58.86 years, p<0.01). The mean age of all patients was estimated at 57.0 years. The patients were primarily covered by Medicaid (40.4%), followed by Medicare (26.0%), and Private insurance (21.9%). Moreover, 90.9% of hospitalizations took place in Urban-teaching centers. Several arrhythmias such as atrial fibrillation (37.2%, 715 cases), supraventricular tachycardia (4.7%, 90 cases), ventricular tachycardia (29.2%, 560 cases), ventricular fibrillation (4.2%, 80 cases), and atrial flutter (6.8%, 130 cases), as well as conduction defects such as first-degree Atrioventricular block (1.6%, 30 cases), complete atrioventricular block (3.9%, 75 cases), and sick sinus syndrome (2.9%, 55 cases), were observed. The mean Charlson Comorbidity Index (CCI) score among these patients was 2.66. Around 185 patients (9.6%) developed CS during their hospitalization. While no statistical significance was seen in the mean ages of patients with and without CS (58.57 vs. 56.84 years, p=0.062), those with CS had a higher mean CCI score (3.73 vs. 2.55, p<0.01; 14.6% of patients with CCI≥4 vs. 8.0% with CCI <4, p<0.01), with a longer hospitalization (22.97 days vs. 6.49 days, p<0.01). Conclusions: Patients with Chagas disease with heart involvement can experience various conduction abnormalities. CS was more common in patients with a higher CCI score, resulting in a longer stay.

Abstract 14709: Association Between Esophageal and Cardiac Autonomic Dysfunction in Chagas Disease

Introduction: Chronic Chagas disease (ChD) may manifest as the indeterminate form, or with chronic cardiopathy (CCM), digestive or mixed forms. CCM is characterized by complex arrhythmias and sudden death, linked to autonomic dysfunction. Pathological involvement of the enteric nervous system triggers the development of the digestive form, and esophageal dysmotility may be another surrogate for dysautonomia. We aimed to assess the association between esophageal autonomic denervation and cardiac autonomic dysfunction in individuals in the indeterminate (ICF) and CCM forms of ChD. Methods: Consented patients with serological diagnosis of ChD and ICF ( n = 30) and CCM ( n = 33) forms were enrolled. All patients underwent esophageal scintigraphy, and esophageal transit time (ETT) and percentage of esophageal emptying (%EE) were recorded. They also underwent 24h Holter monitoring, and heart rate variability (HRV) indices and burden of ventricular extrasystoles (VES) were revised by a cardiologist. The correlation between ETT, %EE and HRV indices ((SDNN (standard deviation of adjacent RR intervals), low and high-frequency power (LFP, HFP(ms)), in addition to the number of VES in 24h was assessed with the SPSS 23 software. Results: 63 patients were enrolled, 54% women, with mean age of 58 years. Left ventricular ejection fraction was lower in the CCM group (44,0 ± 10,8 vs. 64,9 ± 6,6, p<0.001). Autonomic dysfunction showed a distinct pattern between ICF and CCM, with lower SDNN and LF/HF values in the CCM group (100,0 ± 49,9 vs. 124,6 ± 43,2, p=0.042 and 1,4 (0,9 - 2,2) vs. 4,5 (1,5 - 9,5), p<0.001, respectively). The CCM group also had higher 24h VES values (890,0 (120,0 - 2743,0) vs. 47,0 (1,7 - 395,7), p=0.002). There was significant inverse correlation between ETT and SDNN (ß=-0,449, p=0.001), LFP (ms) (ß=-0.288, p=0.025), HFP (ms) (ß=-0.368, p=0.004) and LH/FH (ß=-0.334, p=0.008) in the total sample. There was also a statistically significant and direct correlation between ETT and VES (ß=0.578, p<0.05) in the total sample. Conclusions: ChD individuals with greater esophageal dysmotility showed a decrease in the oscillatory components of HRV and greater arrhythmic density, possibly as a result of more severe sympathetic and parasympathetic cardiac denervation.

Abstract 11768: Regression of Inflammation by Cardiac Magnetic Resonance in Chronic Chagasic Patients Treated With Benznidazole

Introduction: Chagas disease (CD) is a neglected disease caused by Trypanosoma cruzi ( T. cruzi ), and benznidazole (BZN) is the most prescribed trypanocidal drug in Brazil in function of its best tolerability profile. While treatment with this drug is effective in acute disease, there is no consensus on its effectiveness in adults with chronic infection. Although it is now accepted that treatment directed against T. cruzi is necessary to avoid the long-term sequelae of the disease, the lack of reliable markers for assessment of treatment efficacy is a major obstacle to evaluating new drugs. Hypothesis: the objective of this study is to determine if BZN treatment reduces cardiac inflammation/fibrosis as assessed by magnetic resonance imaging (MRI), using parametric mapping techniques. Methods: Prospective, multi-center study of chronic CD patients underwent MRI T1 and T2 mapping and extracellular volume measurement (ECV) using the modified Look-Locker inversion recovery (MOLLI) sequence, undergoing treatment with BZN, at a dose of 300 mg/kg daily divided into two doses and taken for 60 days. Absolute change T1 and T2 mapping, ECV, left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV) and left ventricle ejection fraction (LVEF) were analyzed from baseline to 6-month follow-up. Results: 53 patients (females 83%, 53.9 ± 11.9 years old) were studied. LVEDV (149 ± 27ml vs 147 ± 29ml, p = 0.52), LVESV (66 ± 29 vs 64 ± 15, p = 0.65) and LVEF (55 ± 11% vs 57 ± 8%, p = 0,28) did not change between baseline and post treatment. Native T1 time showed reduced values among anterior (1030 ± 41ms vs 1011 ± 52ms, p = 0.011), septal (1052 ± 53ms vs 1006 ± 38ms, p = 0.000) and lateral (1042 ± 55ms vs 1019 ± 44ms, p = 0.003) LV walls. T2 mapping showed reduction in LV septal wall (53 ± 4ms vs 52 ± 3ms, p = 0.005). ECV showed significant reduction from baseline to 6-month follow-up (29.9 ± 3,3% vs 28.2 ± 3.5%, p = 0.0001). Conclusions: For the first time, we observe favorable changes in CMR ECV, T1 and T2 mapping induced by benznidazole therapy in chronic Chagas disease patients. These findings suggest that there may be an opportunity to decrease fibrosis/inflammation in chronic CD patients with the use of this therapeutic approach.

Inflammation and mitochondria in the pathogenesis of chronic Chagas disease cardiomyopathy.

Chagas disease (CD), caused by the protozoan parasite Trypanosoma cruzi, is a neglected disease affecting around 6 million people. About 30% of CD patients develop chronic Chagas disease cardiomyopathy (CCC), an inflammatory cardiomyopathy that occurs decades after the initial infection, while most infected patients (60%) remain asymptomatic in the so-called indeterminate form (IF). Death results from heart failure or arrhythmia in a subset of CCC patients. Myocardial fibrosis, inflammation, and mitochondrial dysfunction are involved in the arrhythmia substrate and triggering events. Survival in CCC is worse than in other cardiomyopathies, which may be linked to a Th1-T cell rich myocarditis with abundant interferon (IFN)-γ and tumor necrosis factor (TNF)-α, selectively lower levels of mitochondrial energy metabolism enzymes in the heart, and reduced levels of high-energy phosphate, indicating poor adenosine triphosphate (ATP) production. IFN-γ and TNF-α signaling, which are constitutively upregulated in CD patients, negatively affect mitochondrial function in cardiomyocytes, recapitulating findings in CCC heart tissue. Genetic studies such as whole-exome sequencing (WES) in nuclear families with multiple CCC/IF cases has disclosed rare heterozygous pathogenic variants in mitochondrial and inflammatory genes segregating in CCC cases. In this minireview, we summarized studies showing how IFN-γ and TNF-α affect cell energy generation, mitochondrial health, and redox homeostasis in cardiomyocytes, in addition to human CD and mitochondria. We hypothesize that cytokine-induced mitochondrial dysfunction in genetically predisposed patients may be the underlying cause of CCC severity and we believe this mechanism may have a bearing on other inflammatory cardiomyopathies.

An end is in sight: a perspective on PCR as an endpoint for Chagas disease treatment trials

Novel therapies for chronic indeterminate Chagas disease (CICD) are needed, but trials are limited by the absence of tests to detect infection and early treatment efficacy. This perspective highlights the shortfalls and strengths of polymerase chain reaction (PCR) as a study endpoint for anti-parasitic drug development. Serologic reversion, the gold standard test of cure, may take decades to occur in adults and therefore is challenging as an endpoint for drug development. Use of PCR as a marker of infection and treatment response has notable limitations due to low parasitemia in CICD, fluctuations in circulating (versus tissue) parasite burden, strain differences, and assay performance. It is, however, rapidly responsive to therapy, and technological advances have improved detection of different strains and may allow for parasite quantification. Until we have more sensitive tests for parasitological clearance, PCR as a measure of treatment failure may be the best available efficacy endpoint to accelerate early development of much-needed novel therapies. Adequately designed clinical studies are needed to correlate PCR clearance with clinical outcomes and to identify novel biomarkers predictive of clinical outcomes in patients with CICD. Public-private partnerships and health authority engagement are paramount to identify feasible trial endpoints and deliver promising new drug candidates for Chagas disease.

Seroepidemiological Survey of Chronic Chagas Disease in a Rural Community in Southern Bahia, Brazil, Using Recombinant Chimeric Antigens.

Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is a neglected tropical disease with life-threatening implications. In this study, we conducted a seroepidemiological survey to determine the prevalence and clinical profiles of CD in 217 individuals from an impoverished rural community in Southern Bahia, Brazil. The overall prevalence of CD in the studied community was 0.92%, detected through latent class analysis (LCA). Two individuals tested positive for anti-T. cruzi IgG, both being male farmers. One case was a 22-year-old man born in Camamu, with no evidence of congenital transmission, suggesting other routes of transmission such as vector-borne transmission due to migratory activities. The other case was a 69-year-old man born in São Felipe, who had lived in an adobe/brick house and had a pacemaker due to cardiac involvement caused by CD. The prevalence in this community was lower than expected, given the socioeconomic conditions and environmental factors that contribute to T. cruzi transmission. This could be attributed to the implementation of preventive measures and vector control programs by the Brazilian Government. However, continuous monitoring and surveillance are essential to sustain control efforts and detect any potential re-emergence of the disease. While the overall prevalence was low, the detection of positive cases underscores the need for continued surveillance and control measures in vulnerable populations, such as rural communities. Active surveillance, early diagnosis, and timely treatment are crucial in preventing disease progression and complications, thereby enhancing the effectiveness of screening and treatment programs.

Oxidative stress evaluation in patients with chronic Chagas disease.

Chagas disease (CD), caused by protozoan Trypanosoma cruzi (T. cruzi), is a neglected disease that affects millions of people worldwide. The parasite clearance by the immune cells is accomplished by the activation of inflammation and production of reactive oxygen species, including nitric oxide (NO) that can lead to tissue injury and DNA damage. On the other hand, to balance the oxidative environment and decrease free radicals, there is an antioxidant system composed of enzymes and vitamins. The aim was to evaluate oxidative stress parameters in symptomatic and asymptomatic patients with Chagas disease. Participants were divided into three groups: indeterminate CD (asymptomatic, n=8), CD with cardiac/digestive involvement (symptomatic, n=14), and Control healthy individuals (n=20). The following parameters were analyzed: DNA damage, NO serum levels, hydrophilic antioxidant capacity (HAC) and vitamin E. Symptomatic patients showed increased DNA damage and NO levels and lower HAC and vitamin E levels compared to asymptomatic patients and control subjects. It is possible to conclude that CD patients with clinical symptoms have higher oxidative stress, characterized by increased DNA damage and NO levels, and reduced antioxidant capacity and vitamin E levels.

Unveiling challenges in real-time PCR strategies for detecting treatment failure: observations from clinical trials on chronic Chagas disease

Chagas disease (CD) caused by Trypanosoma cruzi remains a Neglected Tropical Disease with limited access to diagnosis and treatment, particularly for chronically infected patients. Clinical trials are underway to improve treatment using new drugs or different regimens, and Real-Time PCR is used to assess the parasitological response as a surrogate biomarker. However, PCR-based strategies have limitations due to the complex nature of T. cruzi infection. The parasite exhibits asynchronous replication, different strains and clones, and diverse tissue tropism, making it challenging to determine optimal timeline points for monitoring treatment response. This mini-review explores factors that affect PCR-based monitoring and summarizes the endpoints used in clinical trials for detecting treatment failure. Serial sampling and cumulative PCR results may improve sensitivity in detecting parasitemia and treatment failure in these trials.

Seroepidemiology of Chagas disease in at-risk individuals in Caraíbas, a city with high endemicity in Bahia State, Brazil.

In Brazil, an estimated 1.1 million people are infected with Trypanosoma cruzi, the causative agent of Chagas disease (CD). Despite the high number of cases, the estimated prevalence of infection per 100 inhabitants is low (0.03). However, the actual number of chronically infected individuals is still unknown. Therefore, we sought to determine the prevalence of chronic CD in at-risk individuals in Caraíbas (Bahia, Brazil) through active case finding. A total of 572 individuals living in rural or urban areas of Caraíbas were eligible for the study. A serum sample was collected from 226 individuals, and the diagnosis performed according to international guidelines. The overall prevalence of anti-T. cruzi IgG was 4.42%. The median age of anti-T. cruzi IgG-positive individuals was 54.5 years, and the female-to-male ratio was 1.5:1. The prevalence of anti-T. cruzi IgG was similar in rural (4.29%) and urban areas (4.65%). Compared with national estimates, we concluded that Caraíbas had a high prevalence for chronic CD and a high risk for persistent transmission. Through our study, it was possible to monitor individuals who were unaware of their clinical condition, thus improving their quality of life.

Use of sera cell free DNA (cfDNA) and exovesicle-DNA for the molecular diagnosis of chronic Chagas disease.

Chagas disease, a neglected tropical disease, is now considered a worldwide health concern as a result of migratory movements from Central and South America to other regions that were considered free of the disease, and where the epidemiological risk is limited to transplacental transmission or blood or organ donations from infected persons. Parasite detection in chronically ill patients is restricted to serological tests that only determine infection by previous infection and not the presence of the parasite, especially in patients undergoing treatment evaluation or in newborns. We have evaluated the use of nucleic acids from both circulating exovesicles and cell-free DNA (cfDNA) from 50 samples twice randomly selected from a total of 448 serum samples from immunologically diagnosed patients in whom the presence of the parasite was confirmed by nested PCR on amplicons resulting from amplification with kinetoplastid DNA-specific primers 121F-122R. Six samples were randomly selected to quantify the limit of detection by qPCR in serum exovesicles. When the nucleic acids thus purified were assayed as a template and amplified with kinetoplastid DNA and nuclear satellite DNA primers, a 100% positivity rate was obtained for all positive samples assayed with kDNA-specific primers and 96% when SAT primers were used. However, isolation of cfDNA for Trypanosoma cruzi and amplification with SAT also showed 100% positivity. The results demonstrate that serum exovesicles contain DNA of mitochondrial and nuclear origin, which can be considered a mixed population of exovesicles of parasitic origin. The results obtained with serum samples prove that both cfDNA and Exovesicle DNA can be used to confirm parasitaemia in chronically ill patients or in samples where it is necessary to demonstrate the active presence of the parasite. The results confirm for the first time the existence of exovesicles of mitochondrial origin of the parasite in the serum of those affected by Chagas disease.

Identification of the ATPase alpha subunit of Trypanosoma cruzi as a potential biomarker for the diagnosis of Chagas disease

BackgroundChagas disease (CD) is considered by the World Health Organisation (WHO) a neglected disease endemic to the Americas, but it has spread throughout the world due to migrations. The disease is almost 100% curable if detected in time. Still, the lack of rapid diagnostic tests with sufficient sensitivity and specificity leads to a chronic phase with a mortality of about 50,000 people worldwide per year.MethodsUsing the total proteins extracted from serum samples of patients confirmed with chronic phase CD; we performed the Bio-SELEX strategy. The best aptamers were selected using next-generation sequencing (NGS) based on their most abundant sequences (reads and rpm). Then, selected aptamers were used to isolate potential biomarkers directly from serum samples of patients with chronic phase CD using pull-down and mass spectrometry experiments.ResultsCH1 aptamer was the aptamer selected after the NGS results analysis. The pull-down and mass spectrometry experiments identified the presence of the ATPase alpha subunit of T. cruzi circulating in serum samples of patients with chronic phase CD.ConclusionsWe report the ATPase alpha subunit of T. cruzi as a potential biomarker for chronic phase CD and CH1 aptamer as a potential tool for diagnosing CD.

Parasitemia and antibody response to benznidazole treatment in a cohort of patients with chronic Chagas disease

BackgroundEvaluating the effectiveness of Chagas disease treatment poses challenges due to the lack of biomarkers for disease progression and therapeutic response. In this study, we aimed to assess the clearance of Trypanosoma cruzi (T. cruzi) parasites in a group of benznidazole (BNZ)-treated chronic Chagas disease patients using high-sensitivity quantitative PCR (qPCR) and track T. cruzi antibody levels through a semiquantitative chemiluminescent assay.MethodsA total of 102 T. cruzi seropositive patients with previous PCR-positive results were enrolled in the study. We collected samples 30 days before treatment (T-30d), on the day before initiating BNZ treatment (T0d), and at follow-up visits 60 days (T60d), 6 months (T6M), 12 months (T12M), and 36 months (T36M) after treatment initiation. Treatment efficacy was assessed by testing of serial samples using a target-capture qPCR assay specific to satellite T. cruzi DNA and the ORTHO T. cruzi ELISA Test System for antibody quantitation.ResultsOf the enrolled individuals, 87 completed at least 50% of the treatment course, and 86 had PCR results at follow-up visits T6M, T12M, and T36M. PCR results exhibited fluctuations before and after treatment, but levels were significantly lower post-treatment. Only 15 cases consistently tested PCR-negative across all post-treatment visits. Notably, nearly all participants demonstrated a declining antibody trajectory, with patients who tested PCR-negative at T36M exhibiting an earlier and more pronounced decline compared to PCR-positive cases at the same visit.ConclusionOur study suggests that serial PCR results pose challenges in interpretation. In contrast, serial antibody levels may serve as an ancillary, or even a more reliable indicator of parasite decline following BNZ treatment. Monitoring antibody levels can provide valuable insights into the efficacy of treatment and the persistence of parasites in Chagas disease patients.

Use of PET/CT to detect myocardial inflammation and the risk of malignant arrhythmia in chronic Chagas disease.

Chagas heart disease (CHD) is characterized by progressive myocardial inflammation associated with myocardial fibrosis and segmental abnormalities that may lead to malignant ventricular arrhythmia and sudden cardiac death. This arrhythmia might be related to the persistence of parasitemia or inflammation in the myocardium in late-stage CHD. Positron emission tomography/computed tomography (PET/CT) has been used to detect myocardial inflammation in non-ischemic cardiomyopathies, such as sarcoidosis, and might be useful for risk prediction in patients with CHD. Twenty-four outpatients with chronic CHD were enrolled in this prospective cross-sectional study between May 2019 and March 2022. The patients were divided into two groups: those with sustained ventricular tachycardia and/or aborted sudden cardiac death who required implantable cardioverter-defibrillators, and those with the same stages of CHD and no complex ventricular arrhythmia. Patients underwent 18F-fluorodeoxyglucose (18F-FDG) and 68Ga-DOTATOC PET/CT, and blood samples were collected for qualitative parasite assessment by polymerase chain reaction. Although similar proportions of patients with and without complex ventricular arrhythmia showed 18F-FDG and 68Ga-DOTATOC uptake, 68Ga-DOTATOC corrected SUVmax was higher in patients with complex arrhythmia (3.4 vs 1.7; P = .046), suggesting that inflammation could be associated with the presence of malignant arrhythmia in the late stages of CHD. We also detected Trypanosoma cruzi in both groups, with a nonsignificant trend of increased parasitemia in the group with malignant arrhythmia (66.7% vs 33.3%). 18F-FDG and 68Ga-DOTATOC uptake on PET/CT may be useful for the detection of myocardial inflammation in patients with Chagas cardiomyopathy, and 68Ga-DOTATOC uptake may be associated with the presence of malignant arrhythmia, with potential therapeutic implications.

Immunopathogenesis in Trypanosoma cruzi infection: a role for suppressed macrophages and apoptotic cells.

During Trypanosoma cruzi infection, macrophages phagocytose parasites and remove apoptotic cells through efferocytosis. While macrophage 1 (M1) produces proinflammatory cytokines and NO and fights infection, M2 macrophages are permissive host cells that express arginase 1 and play a role in tissue repair. The regulation of M1 and M2 phenotypes might either induce or impair macrophage-mediated immunity towards parasite control or persistence in chronic Chagas disease. Here, we highlight a key role of macrophage activation in early immune responses to T. cruzi that prevent escalating parasitemia, heart parasitism, and mortality during acute infection. We will discuss the mechanisms of macrophage activation and deactivation, such as T cell cytokines and efferocytosis, and how to improve macrophage-mediated immunity to prevent parasite persistence, inflammation, and the development of chagasic cardiomyopathy. Potential vaccines or therapy must enhance early T cell-macrophage crosstalk and parasite control to restrain the pathogenic outcomes of parasite-induced inflammation in the heart.

Deep serological profiling of the Trypanosoma cruzi TSSA antigen reveals different epitopes and modes of recognition by Chagas disease patients.

Trypanosoma cruzi, the agent of Chagas disease, displays a highly structured population, with multiple strains that can be grouped into 6-7 evolutionary lineages showing variable eco-epidemiological traits and likely also distinct disease-associated features. Previous works have shown that antibody responses to 'isoforms' of the polymorphic parasite antigen TSSA enable robust and sensitive identification of the infecting strain with near lineage-level resolution. To optimize the serotyping performance of this molecule, we herein used a combination of immunosignaturing approaches based on peptide microarrays and serum samples from Chagas disease patients to establish a deep linear B-cell epitope profiling of TSSA. Our assays revealed variations in the seroprevalence of TSSA isoforms among Chagas disease populations from different settings, hence strongly supporting the differential distribution of parasite lineages in domestic cycles across the Americas. Alanine scanning mutagenesis and the use of peptides of different lengths allowed us to identify key residues involved in antibody pairing and the presence of three discrete B-cell linear epitopes in TSSAII, the isoform with highest seroprevalence in human infections. Comprehensive screening of parasite genomic repositories led to the discovery of 9 novel T. cruzi TSSA variants and one TSSA sequence from the phylogenetically related bat parasite T. cruzi marinkellei. Further residue permutation analyses enabled the identification of diagnostically relevant or non-relevant substitutions among TSSA natural polymorphisms. Interestingly, T. cruzi marinkellei TSSA displayed specific serorecognition by one chronic Chagas disease patient from Colombia, which warrant further investigations on the diagnostic impact of such atypical TSSA. Overall, our findings shed new light into TSSA evolution, epitope landscape and modes of recognition by Chagas disease patients; and have practical implications for the design and/or evaluation of T. cruzi serotyping strategies.

Chagas disease is related to structural changes of the gut microbiota in adults with chronic infection (TRIPOBIOME Study).

The implications of the gut microbial communities in the immune response against parasites and gut motility could explain the differences in clinical manifestations and treatment responses found in patients with chronic Chagas disease. In this pilot prospective cross-sectional study, we included 80 participants: 29 with indeterminate CD (ICD), 16 with cardiac CD (CCD), 15 with digestive CD (DCD), and 20 controls without CD. Stool was collected at the baseline visit and faecal microbial community structure DNA was analyzed by whole genome sequencing. We also performed a comprehensive dietary analysis. Ninety per cent (72/80) of subjects were of Bolivian origin with a median age of 47 years (IQR 39-54) and 48.3% (29/60) had received benznidazole treatment. There were no substantial differences in dietary habits between patients with CD and controls. We identified that the presence or absence of CD explained 5% of the observed microbiota variability. Subjects with CD exhibited consistent enrichment of Parabacteroides spp, while for Enterococcus hirae, Lactobacillus buchneri and Megamonas spp, the effect was less clear once excluded the outliers values. Sex, type of visceral involvement and previous treatment with benznidazole did not appear to have a confounding effect on gut microbiota structure. We also found that patients with DCD showed consistent Prevotella spp enrichment. We found a detectable effect of Chagas disease on overall microbiota structure with several potential disease biomarkers, which warrants further research in this field. The analysis of bacterial diversity could prove to be a viable target to improve the prognosis of this prevalent and neglected disease.

Differential expression profile of genes involved in the immune response associated to progression of chronic Chagas disease.

Patients with chronic Chagas disease present marked clinical and immunological heterogeneity. During the disease, multiple immune mechanisms are activated to fight the parasite. The purpose of this study was to investigate the expression patterns of genes involved in relevant immunological processes throughout the disease in patients with chronic Chagas disease. High-throughput RT-qPCR with QuantStudio 12K Flex real-time PCR system was used to evaluate the expression of 106 immune-related genes in PBMC from a cohort of cardiac Chagas disease patients (CCC I), asymptomatic patients (IND) and healthy donors (HD) after being stimulated with T. cruzi soluble antigens. Principal component analysis (PCA), cluster analysis and volcano plots were used to identify differentially expressed genes. In addition, gene set enrichment analysis (GSEA) was employed to identify the enriched immunological pathways in which these genes are involved. PCA revealed the existence of a statistically divergent expression profile of the 36 genes correlated with PC1 between CCC I patients and HD (p < 0.0001). Differential gene expression analysis revealed upregulation of 41 genes (expression fold-change > 1.5) and downregulation of 14 genes (expression fold-change < 0.66) (p = 8.4x10-13 to p = 0.007) in CCC I patients versus HD. Furthermore, significant differences in the expression level of specific genes have been identified between CCC I and IND patients (8 up and 1 downregulated). GSEA showed that several upregulated genes in CCC I patients participate in immunological pathways such as antigen-dependent B cell activation, stress induction of HSP regulation, NO2-dependent IL12 pathway in NK cells, cytokines-inflammatory response and IL-10 anti-inflammatory signaling. Cardiac Chagas disease patients show an antigen-specific differential gene expression profile in which several relevant immunological pathways seem to be activated. Assessment of gene expression profiles reveal unique insights into the immune response that occurs along chronic Chagas disease.