Cardiac Abnormalities in a Predictive Mouse Model of Chagas Disease

Chronic Chagas cardiomyopathy (CCC) results from infection with the protozoan parasite Trypanosoma cruzi and is a prevalent cause of heart disease in endemic countries. We previously found that cardiac fibrosis can vary widely in C3H/HeN mice chronically infected with T. cruzi JR strain, mirroring the spectrum of heart disease in humans. In this study, we examined functional cardiac abnormalities in this host:parasite combination to determine its potential as an experimental model for CCC. We utilised electrocardiography (ECG) to monitor T. cruzi-infected mice and determine whether ECG markers could be correlated with cardiac function abnormalities. We found that the C3H/HeN:JR combination frequently displayed early onset CCC indicators, such as sinus bradycardia and right bundle branch block, as well as prolonged PQ, PR, RR, ST, and QT intervals in the acute stage. Our model exhibited high levels of cardiac inflammation and enhanced iNOS expression in the acute stage, but denervation did not appear to have a role in pathology. These results demonstrate the potential of the C3H/HeN:JR host:parasite combination as a model for CCC that could be used for screening new compounds targeted at cardiac remodelling and for examining the potential of antiparasitic drugs to prevent or alleviate CCC development and progression.

Cost-effectiveness of an exercise-based cardiovascular rehabilitation program in patients with chronic Chagas cardiomyopathy in Brazil: An analysis from the PEACH study

OBJECTIVES

The present study aimed to perform a cost-effectiveness analysis of an exercise-based cardiovascular rehabilitation (CR) program in patients with chronic Chagas cardiomyopathy (CCC).

METHODS

Cost-effectiveness analysis alongside a randomised clinical trial evaluating the effects of a 6-month exercise-based CR program. The intervention group underwent 3 weekly exercise sessions. The variation of peak oxygen consumption (VO_2peak ) was used as a measurement of clinical outcome. Cost information from all healthcare expenses (examinations, healthcare visits, medication and hospitalisation) were obtained from the medical records in Brazilian reais (R$) and transformed into dollars using the purchasing power parity ($PPP). The longitudinal costs variation was evaluated through linear mixed models, represented by β coefficient, adjusted for the baseline values of the dependent variable. The cost-effectiveness evaluation was determined through an incremental cost-effectiveness ratio using the HEABS package (Stata 15.0).

RESULTS

The intervention group presented higher costs with healthcare visits (β = +3317.3; p < 0.001), hospitalisation (β = +2810.4; p = 0.02) and total cost (β = +6407.9; p < 0.001) after 3 months of follow-up. Costs related to healthcare visits (β = +2455.8; p < 0.001) and total cost (β = +4711.4; p < 0.001) remained higher in the intervention group after 6 months. The CR program showed an incremental cost-effectiveness ratio (ICER) of $PPP 1874.3 for each increase of 1.0 ml kg^-1  min^-1 of VO_2peak .

CONCLUSIONS

The CR program can be considered a cost-effective alternative and should be included as an intervention strategy in the care of patients with CCC.

Parasitic Load Correlates With Left Ventricular Dysfunction in Patients With Chronic Chagas Cardiomyopathy

Background: Chronic Chagas disease (CChD), one of the infectious parasitic diseases with the greatest social and economic impact upon a large part of the American continent, has distinct clinical manifestations in humans (cardiac, digestive, or mixed clinical forms). The mechanisms underlying the development of the most common and ominous clinical form, the chronic Chagas cardiomyopathy (CCC) have not been completely elucidated, despite the fact that a high intensity of parasite persistence in the myocardium is deemed responsible for an untoward evolution of the disease. The present study aimed to assess the parasite load CCC and its relation to left ventricular ejection fraction (LVEF), a definite prognostic marker in patients with CCC.

Methods: Patients with CCC were clinically evaluated using 12-lead-electrocardiogram, echocardiogram, chest X-ray. Peripheral blood sampling (5 ml of venous blood in guanidine/EDTA) was collected from each patient for subsequent DNA extraction and the quantification of the parasite load using real-time PCR.

Results: One-hundred and eighty-one patients with CCC were evaluated. A total of 140 (77.3%) had preserved left ventricular ejection fraction (of ≥40%), and 41 individuals had LV dysfunction (LVEF of <40%). A wide variation in parasite load was observed with a, mean of 1.3460 ± 2.0593 (0.01 to 12.3830) par. Eq./mL. The mean ± SD of the parasite load was 0.6768 ± 0.9874 par. Eq./mL and 3.6312 ± 2.9414 par. Eq./mL in the patients with LVEF ≥ 40% and <40%, respectively.

Conclusion: The blood parasite load is highly variable and seems to be directly related to the reduction of LVEF, an important prognostic factor in CCC patients.

Feasibility of a Combined Mobile-Health Electrocardiographic and Rapid Diagnostic Test Screening for Chagas-Related Cardiac Alterations

BACKGROUND

Chronic Chagas cardiomyopathy (CChC) is the most common cause of death related to Chagas disease (CD). The aim of this study was to assess the feasibility of a combined rapid diagnostic test (RDT) and electrocardiographic (ECG) screening in a remote rural village of the Bolivian Chaco, with a high prevalence of CChC.

METHODS

Consecutive healthy volunteers > 15 years were enrolled in the community of Palmarito (municipality of Gutierrez, Santa Cruz Department, Bolivia) in February 2019. All patients performed an RDT with Chagas Stat-Pak® (CSP, Chembio Diagnostic System, Medford, NY, USA) and an ECG by D-Heart® technology, a low-cost, user-friendly smartphone-based 8-lead Bluetooth ECG. RDTs were read locally while ECGs were sent to a cardiology clinic which transmitted reports within 24 h from recording.

RESULTS

Among 140 people (54 men, median age 38(interquartile range 23-54) years), 98 (70%) were positive for Trypanosoma cruzi infection, with a linear, age-dependent, increasing trend (p < 0.001). Twenty-five (18%) individuals showed ECG abnormalities compatible with CD. Prevalence of ECG abnormalities was higher in infected individuals and was associated with higher systolic blood pressure and smoking. Following screening, 22 (16%) individuals underwent clinical evaluation and chest X-ray and two were referred for further evaluation. At multivariate analysis, positive CSP results (OR = 4.75, 95%CI 1.08-20.96, p = 0.039) and smoking (OR = 4.20, 95%CI 1.18-14.92, p = 0.027) were independent predictors of ECG abnormalities. Overall cost for screening implementation was <10 $.

CONCLUSIONS

Combined mobile-Health and RDTs was a reliable and effective low-cost strategy to identify patients at high risk of disease needing cardiologic assessment suggesting potential future applications.

Trypanosoma cruzi Induces Regulatory B Cell Alterations in Patients With Chronic Chagas Disease

The clinical evolution of patients with chronic Chagas disease (CCD) is mainly associated with an excessive inflammation and a defective immunomodulatory profile caused by the interaction between T. cruzi and the host. Regulatory B (Breg) cells exert immune suppression mostly through IL-10 production (B10 cells), but also through IL-10-independent mechanisms. Previously, we demonstrated that CCD patients with cardiomyopathy show changes in the ex vivo Breg cell phenotypic distribution although maintain IL-10 production capacity. Here, we sought to identify potential alterations on Breg cells upon in vitro stimulation. Isolated B cells from CCD patients with or without cardiomyopathy and non-infected (NI) donors were stimulated with T. cruzi lysate or CpG + CD40L, and characterized by flow cytometry based on the expression of CD24, CD27, CD38, and the regulatory molecules IL-10 and PD-L1. IL-10 and IL-17 secretion in the supernatant of B cells was evaluated by ELISA. Data showed that T. cruzi stimulation diminished the expression of CD24 and CD38 on CD27- B cells while reducing the percentage of CD24high inside CD27+ B cells. Furthermore, T. cruzi induced a regulatory B cell phenotype by increasing B10 cells and IL-10 secretion in all the groups. The innate-like B10 cells expansion observed in patients with cardiomyopathy would be associated with CD27- B10 cell subsets, while no predominant phenotype was found in the other groups. Patients with cardiomyopathy also displayed higher IL-17 secretion levels in T. cruzi-activated B cells. CpG + CD40L stimulation revealed that B cells from CCD patients and NI donors had the same ability to differentiate into B10 cells and secrete IL-10 in vitro. Additionally, CCD patients showed an increased frequency of CD24-CD27- B cells and a reduction in the percentage of CD24highCD27+ Breg cells, which appeared to be inversely correlated with the presence of T. cruzi DNA in blood. Finally, CCD patients exhibited a higher frequency of PD-L1+ B cells in T. cruzi-stimulated samples, suggesting that IL-10-independent mechanisms could also be tangled in the control of inflammation. Altogether, our results provide evidence about the potential role of Breg cells in the immune response developed against T. cruzi and its contribution to chronic Chagas cardiomyopathy.

Circulating Trypanosoma cruzi load and major cardiovascular outcomes in patients with chronic Chagas cardiomyopathy: a prospective cohort study

OBJECTIVES

To analyse the effect of parasite load assessed by quantitative reverse transcription PCR (RT-qPCR) in serum on the prognosis of patients with chronic Chagas cardiomyopathy (CCM) after a 2-year follow-up.

METHODS

Prospective cohort study conducted between 2015 and 2017. One hundred patients with CCM were included. Basal parasitaemia levels of Trypanosoma cruzi (T. cruzi) were measured using a quantitative polymerase chain reaction (qPCR) test. The primary composite outcome (CO) was all-cause mortality, cardiac transplantation and implantation of a left ventricular assist device. Secondary outcomes were the baseline levels of serum biomarkers and echocardiographic variables.

RESULTS

After a 2 years of follow-up, the primary CO rate was 16%. A positive qPCR was not associated with a higher risk of the CO. However, when parasitaemia was evaluated by comparing tertiles (tertile 1: undetectable parasitaemia, tertile 2: low parasitaemia and tertile 3: high parasitaemia), a higher risk of the CO (HR 3.66; 95% CI 1.11-12.21) was evidenced in tertile 2. Moreover, patients in tertile 2 had significantly higher levels of high-sensitivity troponin T and cystatin C and more frequently exhibited an ejection fraction <50%.

CONCLUSION

Low parasitaemia was associated with severity markers of myocardial injury and a higher risk of the composite outcome when compared with undetectable parasitaemia. This finding could be hypothetically explained by a more vigorous immune response in patients with low parasitaemia that could decrease T. cruzi load more efficiently, but be associated with increased myocardial damage. Additional studies with a larger number of patients and cytokine measurement are required to support this hypothesis.

Myocardial fibrosis in chagas disease and molecules related to fibrosis

Chronic Chagas cardiomyopathy (CCC) is responsible for the disease's greater morbidity and poor prognosis. Although understanding the pathophysiology of CCC and the fundamentals of its clinical management derives from research related to other cardiomyopathies, there are peculiarities that distinguish CCC from the others. CCC is the most fibrous heart disease, and its myocardial involvement is important as it disorganizes or disrupts the extracellular matrix, creating an environment conducive to the formation of arrhythmogenic foci. It is also considered the most arrhythmogenic of the known heart diseases, giving rise to complex arrhythmias, usually associated with varying degrees of stimulus conduction disorders. The central proposal of this review is to describe a possible association between the distribution and degree of myocardial fibrosis and cardiac arrhythmogenicity in patients with Chagas cardiomyopathy, drawing attention to the importance of noninvasive biomarkers for the quantification of myocardial fibrosis.

Programmed Cell Death Protein 1-PDL1 Interaction Prevents Heart Damage in Chronic Trypanosoma cruzi Infection

Chagas disease is a neglected parasitic infection that affects around six to seven million people, mainly in Latin America. About 30–35% of infected people present chronic Chagas cardiomyopathy (CCC), which eventually leads to death. This condition is characterized by local parasite persistence and leukocyte infiltration. In a murine model of CCC, we observed that among infiltrating leukocytes, CD4⁺ and CD8⁺ T cells were in higher frequency in the heart of chronically infected mice, although elevated expression of the regulatory molecules programmed cell death protein 1 (PD1) and PDL1 suggested these cells could be inhibited. To investigate if PD1–PDL1 interaction in the heart of chronically infected mice negatively impacts on the local immune response, facilitating parasite persistence, and progression to CCC, we attempted to recover the local immune response by treating chronically infected mice with anti-PD1 and anti-PDL1-blocking antibodies together with irradiated Trypanosoma cruzi, which provides immune response boosting. Irradiated parasites promote expression of costimulatory molecules in dendritic cells and provide specific parasite antigen, which should aid T cell reactivation upon checkpoint blockade. Following treatment, there was an increased frequency of heart-infiltrating CD4⁺ and CD8⁺ T cells with an effector memory phenotype, an increased histopathology score and decreased heart rate, supporting our previous hypothesis of local immunosuppression induced by this pathway during CCC. In addition, blood parasitemia was reduced, which was associated with increased T. cruzi-specific immunoglobulin G 1 antibodies. However, no difference was observed in cytokine production or T. cruzi burden in the hearts of treated mice. Taken together, our results suggest PD1–PDL1 interaction protects the heart from excessive immune response.

Nanomedicines against Chagas disease: an update on therapeutics, prophylaxis and diagnosis

Chagas disease is a neglected parasitic infection caused by the protozoan Trypanosoma cruzi. After a mostly clinically silent acute phase, the disease becomes a lifelong chronic condition that can lead to chronic heart failure and thromboembolic phenomena followed by sudden death. Antichagasic treatment is only effective in the acute phase but fails to eradicate the intracellular form of parasites and causes severe toxicity in adults. Although conventional oral benznidazol is not a safe and efficient drug to cure chronic adult patients, current preclinical data is insufficient to envisage if conventional antichagasic treatment could be realistically improved by a nanomedical approach. This review will discuss how nanomedicines could help to improve the performance of therapeutics, vaccines and diagnosis of Chagas disease.