Mitochondrial DNA haplogroups and variants predispose to chagas disease cardiomyopathy

Cardiomyopathies are major causes of heart failure. Chagas disease (CD) is caused by the parasite Trypanosoma cruzi, and it is endemic in Central and South America. Thirty percent of cases evolve into chronic chagas cardiomyopathy (CCC), which has worse prognosis as compared with other cardiomyopathies. In vivo bioenergetic analysis and ex vivo proteomic analysis of myocardial tissues highlighted worse mitochondrial dysfunction in CCC, and previous studies identified nuclear-encoded mitochondrial gene variants segregating with CCC. Here, we assessed the role of the mitochondrial genome through mtDNA copy number variations and mtDNA haplotyping and sequencing from heart or blood tissues of severe, moderate CCC and asymptomatic/indeterminate Chagas disease as well as healthy controls as an attempt to help decipher mitochondrial-intrinsic genetic involvement in Chagas disease development. We have found that the mtDNA copy number was significantly lower in CCC than in heart tissue from healthy individuals, while blood mtDNA content was similar among asymptomatic Chagas disease, moderate, and severe CCC patients. An MtDNA haplogrouping study has indicated that African haplogroups were over represented in the Chagas subject groups in comparison with healthy Brazilian individuals. The European lineage is associated with protection against cardiomyopathy and the macro haplogroup H is associated with increased risk towards CCC. Using mitochondria DNA sequencing, 84 mtDNA-encoded protein sequence pathogenic variants were associated with CCC. Among them, two variants were associated to left ventricular non-compaction and two to hypertrophic cardiomyopathy. The finding that mitochondrial protein-coding SNPs and mitochondrial haplogroups associate with risk of evolving to CCC is consistent with a key role of mitochondrial DNA in the development of chronic chagas disease cardiomyopathy.

Blood DNA methylation marks discriminate Chagas cardiomyopathy disease clinical forms

Chagas disease is a parasitic disease from South America, affecting around 7 million people worldwide. Decades after the infection, 30% of people develop chronic forms, including Chronic Chagas Cardiomyopathy (CCC), for which no treatment exists. Two stages characterized this form: the moderate form, characterized by a heart ejection fraction (EF) ≥ 0.4, and the severe form, associated to an EF < 0.4. We propose two sets of DNA methylation biomarkers which can predict in blood CCC occurrence, and CCC stage. This analysis, based on machine learning algorithms, makes predictions with more than 95% accuracy in a test cohort. Beyond their predictive capacity, these CpGs are located near genes involved in the immune response, the nervous system, ion transport or ATP synthesis, pathways known to be deregulated in CCCs. Among these genes, some are also differentially expressed in heart tissues. Interestingly, the CpGs of interest are tagged to genes mainly involved in nervous and ionic processes. Given the close link between methylation and gene expression, these lists of CpGs promise to be not only good biomarkers, but also good indicators of key elements in the development of this pathology.

Epigenetic regulation of transcription factor binding motifs promotes Th1 response in Chagas disease cardiomyopathy

Abstract: Chagas disease, caused by the protozoan Trypanosoma cruzi, is an endemic parasitic disease of Latin America, affecting 7 million people. Although most patients are asymptomatic, 30% develop complications, including the often-fatal Chronic Chagasic Cardiomyopathy (CCC). Although previous studies have demonstrated some genetic deregulations associated with CCCs, the causes of their deregulations remain poorly described. Based on bulk RNA-seq and whole genome DNA methylation data, we investigated the genetic and epigenetic deregulations present in the moderate and severe stages of CCC. Analysis of heart tissue gene expression profile allowed us to identify 1407 differentially expressed transcripts (DEGs) specific from CCC patients. A tissue DNA methylation analysis done on the same tissue has permitted the identification of 92 regulatory Differentially Methylated Regions (DMR) localized in the promoter of DEGs. An in-depth study of the transcription factors binding sites (TFBS) in the DMRs corroborated the importance of TFBS's DNA methylation for gene expression in CCC myocardium. TBX21, RUNX3 and EBF1 are the transcription factors whose binding motif appears to be affected by DNA methylation in the largest number of genes. By combining both transcriptomic and methylomic analysis on heart tissue, and methylomic analysis on blood, 4 biological processes affected by severe CCC have been identified, including immune response, ion transport, cardiac muscle processes and nervous system. An additional study on blood methylation of moderate CCC samples put forward the importance of ion transport and nervous system in the development of the disease.

Isolation and molecular characterization of circulating extracellular vesicles from blood of chronic Chagas disease patients.

Extracellular vesicles (EVs) are lipid bilayer envelopes that encase several types of molecules. Their contents mostly reflect their cell origin and possible targets at other locations in the organism and can be modified in pathological conditions to interfere with intercellular communication, thus promoting disease establishment and development. These characteristics, in addition to their presence in virtually all body fluids, make such vesicles ideal for biomarker discovery in human diseases. Here, we describe the effect of different anticoagulants and the combination of two purification methods for isolation and characterization of circulating EVs from blood of chronic Chagas disease (CCD) patients. We illustrated this procedure by studying a population of patients with Chagas disease at the indeterminate chronic stage, in which the Trypanosoma cruzi is very scarce in circulation. EVs were harvested from blood collected without or with different anticoagulants. Protein and nanoparticle tracking analysis was used to measure EVs size and concentration. The EVs were purified by ultracentrifugation, followed by size-exclusion chromatography and characterized by chemiluminescent enzyme-linked immunosorbent assay and dot blot using antibodies that recognized parasite-derived EVs, such as hyperimmune sera, polyclonal and monoclonal antibodies against trans-sialidase and mucins. In parallel, antibodies against classical human EV markers CD9, CD63, CD81, and CD82, were also analyzed. The results showed that anticoagulants did not interfere with the analyzed parameters and circulating EVs from CCD patients contain T. cruzi antigens and classical human exosomal markers. Overall, our protocol is adequate for the isolation of the total circulating EVs and can serve as an important basis for further studies on biomarker discovery in Chagas' disease.

Pericardial Effusion and Cardiac Tamponade: Etiology and Evolution in the Contemporary Era

Abstract Background: Pericardial effusion is a relatively common finding and can progress to cardiac tamponade; etiological diagnosis is important for guiding treatment decisions. With advances in medicine and improvement in the social context, the most frequent etiological causes have changed. Objectives: To evaluate the clinical and laboratory characteristics, etiology, and clinical course of patients with pericardial effusion and cardiac tamponade. Materials and methods: Patients with pericardial effusion classified as small (< 10 mm), moderate (between 10-20 mm), or severe (> 20 mm) were included. Data from the clinical history, physical examination, laboratory tests, and complementary tests were evaluated in patients with pericardial effusion and cardiac tamponade. The significance level was set at 5%. Results: A total of 254 patients with a mean age of 53.09 ± 17.9 years were evaluated, 51.2% of whom were female. A total of 40.4% had significant pericardial effusion (> 20 mm). Pericardial tamponade occurred in 44.1% of patients. Among pericardial effusion patients without tamponade, the most frequent etiologies were: idiopathic (44.4%) and postsurgical (17.6%), while among those with tamponade, the most frequent etiologies were postsurgical (21.4%) and postprocedural (19.6%). The mean follow-up time was 2.2 years. Mortality was 42% and 23.2 in those with and without tamponade, respectively (p=0.001). Conclusions: There is an etiological difference between pericardial effusion patients with and without cardiac tamponade. An idiopathic etiology is more common among those without tamponade, while postinterventional/postsurgical is more common among those with tamponade. The tamponade group had a higher mortality rate.

New Biomarker in Chagas Disease: Extracellular Vesicles Isolated from Peripheral Blood in Chronic Chagas Disease Patients Modulate the Human Immune Response.

Chagas disease, a neglected tropical disease (NTD) caused by the flagellated protozoan Trypanosoma cruzi (T. cruzi), is a major public health problem. It was initially restricted to Latin America, but it is now expanding globally. Host and pathogen interactions are crucial in the establishment of disease, and since 1970, it has been known that eukaryotic cells release extracellular vesicles (EVs), which in turn have an important role in intercellular communication in physiological and pathological conditions. Our study proposed to characterize and compare circulating EVs isolated from the plasma of chronic Chagas disease (CCD) patients and controls. For this, peripheral blood was collected from patients and controls, and mononuclear cells (PBMCs) were isolated and stimulated with parasite EVs, showing that patient cells released fewer EVs than control cells. Then, after plasma separation followed by EV total shedding enrichment, the samples were subjected to ultracentrifugation to isolate the circulating EVs, which then had their size and concentration characterized by nanoparticle tracking analysis (NTA). This showed that patients had a lower concentration of circulating EVs while there were no differences in size, corroborating the in vitro data. Additionally, circulating EVs were incubated with THP-1 cells (macrophages) that, after the interaction, had their supernatant analyzed by ELISA for cytokine detection. In relation to their ability to induce cytokine production, the CCD patient EVs were able to induce a differential production of IFN-γ and IL-17 in relation to controls, with differences being more evident in earlier/less severe stages of the disease. In summary, a decreased concentration of circulating EVs associated with differential activation of the immunological system in patients with CCD is related to parasite persistence and the establishment of chronic disease. It is also a potential biomarker for monitoring disease progression.

Corrigendum: Polymorphisms in Genes Affecting Interferon-γ Production and Th1 T Cell Differentiation Are Associated With Progression to Chagas Disease Cardiomyopathy.

[This corrects the article DOI: 10.3389/fimmu.2020.01386.].

Polymorphisms in Genes Affecting Interferon-γ Production and Th1 T Cell Differentiation Are Associated With Progression to Chagas Disease Cardiomyopathy.

Background: Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is the most important clinical consequence of T. cruzi infection, while the others remain asymptomatic (ASY). IFN-γ and IFN-γ-producing Th1-type T cells are increased in peripheral blood and CCC myocardium as compared to ASY patients, while the Th1-antagonizing cytokine IL-10 is more expressed in ASY patients. Importantly IFN-γ-producing Th1-type T cells are the most frequent cytokine-producing T cell subset in CCC myocardium, while expression of Th1-antagonizing cytokines IL-10 and IL-4 is unaltered. The control of IFN-γ production by Th1-type T cells may be a key event for progression toward CCC. A genetic component to disease progression was suggested by the familial aggregation of cases and the association of gene polymorphisms with CCC development. We here investigate the role of gene polymorphisms (SNPs) in several genes involved in the control of IFN-γ production and Th1 T cell differentiation in CCC development. Methods: We studied a Brazilian population including 315 CCC cases and 118 ASY subjects. We assessed 35 Tag SNPs designed to represent all the genetic information contained in the IL12B, IL10, IFNG, and IL4 genes. Results: We found 2 IL12 SNPs (rs2546893, rs919766) and a trend of association for a IL10 SNP (rs3024496) to be significantly associated with the ASY group. these associations were confirmed by multivariate analysis and allele tests. The rs919766C, 12rs2546893G, and rs3024496C alleles were associated to an increase risk to CCC development. Conclusions: Our data show that novel polymorphisms affecting IL12B and IL10, but not IFNG or IL4 genes play a role in genetic susceptibility to CCC development. This might indicate that the increased Th1 differentiation and IFN-γ production associated with CCC is genetically controlled.

Polymorphisms in genes affecting interferon-γ production and Th1 T cell differentiation are associated with progression to Chagas Disease cardiomyopathy

BACKGROUND: Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is the most important clinical consequence of T. cruzi infection, while the others remain asymptomatic (ASY). IFN-γ and IFN-γ-producing Th1-type T cells are increased in peripheral blood and CCC myocardium as compared to ASY patients, while the Th1-antagonizing cytokine IL-10 is more expressed in ASY patients. Importantly IFN-γ-producing Th1-type T cells are the most frequent cytokine-producing T cell subset in CCC myocardium, while expression of Th1-antagonizing cytokines IL-10 and IL-4 is unaltered. The control of IFN-γ production by Th1-type T cells may be a key event for progression toward CCC. A genetic component to disease progression was suggested by the familial aggregation of cases and the association of gene polymorphisms with CCC development. We here investigate the role of gene polymorphisms (SNPs) in several genes involved in the control of IFN-γ production and Th1 T cell differentiation in CCC development. METHODS: We studied a Brazilian population including 315 CCC cases and 118 ASY subjects. We assessed 35 Tag SNPs designed to represent all the genetic information contained in the IL12B, IL10, IFNG, and IL4 genes. RESULTS: We found 2 IL12 SNPs (rs2546893, rs919766) and a trend of association for a IL10 SNP (rs3024496) to be significantly associated with the ASY group. these associations were confirmed by multivariate analysis and allele tests. The rs919766C 12rs2546893G, and rs3024496C alleles were associated to an increase risk to CCC development. CONCLUSIONS: Our data show that novel polymorphisms affecting IL12B and IL10, but not IFNG or IL4 genes play a role in genetic susceptibility to CCC development. This might indicate that the increased Th1 differentiation and IFN-γ production associated with CCC is genetically controlled.

Evaluation of Galectin-3 and myocardial fibrosis in patients with hypertrophic cardiomyopathy / Avaliação de Galectina-3 e fibrose miocárdica em pacientes com cardiomiopatia hipertrófica

Background: Galectin-3 is the designation given to the protein that binds to ß-galactosides, expressed by activated macrophages and described as a cardiac fibrosis mediator. In hypertrophic cardiomyopathy (HCM), myocardial fibrosis is an independent predictor of adverse outcome; however, the association between Galectin-3 and myocardial fibrosis has not been studied in this cardiopathy. Objective: To evaluate the association of Galectin-3 and the presence of myocardial fibrosis in a patient with hypertrophic cardiomyopathy. Methods: Galectin-3 was measured in automated equipment using the Elisa technique in 100 participants divided into two groups: 50 patients with hypertrophic cardiomyopathy and 50 healthy control subjects. All patients with hypertrophic cardiomyopathy underwent magnetic nuclear resonance with the late enhancement technique to investigate myocardial fibrosis. For the statistical analysis, p values < 0.05 were considered statistically significant. Results: Galectin-3 levels were low and did not show significant differences between patients with hypertrophic cardiomyopathy and the control group,10.3 ± 3.1 ng/dL and 11.3 ± 2.6 ng/dL (p = 0.12) respectively. Myocardial fibrosis was a common finding and was identified in 84% (42/50) of patients with HCM, but no differences were observed between Galectin-3 levels when comparing patients with and without fibrosis, 10.3 ± 2.4 ng/dL and 10.1 ± 2.1 ng/dL (p = 0.59). Conclusion: The results did not show an association between Galectin-3 and myocardial fibrosis in patients with hypertrophic cardiomyopathy, suggesting that non-inflammatory mechanisms of myocardial fibrosis formation and cardiac remodeling are involved in this cardiopathy

Archaea Symbiont of T. cruzi Infection May Explain Heart Failure in Chagas Disease.

Background: Archaeal genes present in Trypanosoma cruzi may represent symbionts that would explain development of heart failure in 30% of Chagas disease patients. Extracellular vesicles in peripheral blood, called exosomes (< 0.1 µm) or microvesicles (>0.1 µm), present in larger numbers in heart failure, were analyzed to determine whether they are derived from archaea in heart failure Chagas disease. Methods: Exosomes and microvesicles in serum supernatant from 3 groups were analyzed: heart failure Chagas disease (N = 26), asymptomatic indeterminate form (N = 21) and healthy non-chagasic control (N = 16). Samples were quantified with transmission electron microscopy, flow cytometer immunolabeled with anti-archaemetzincin-1 antibody (AMZ 1, archaea collagenase) and probe anti-archaeal DNA and zymography to determine AMZ1 (Archaeal metalloproteinase) activity. Results: Indeterminate form patients had higher median numbers of exosomes/case vs. heart failure patients (58.5 vs. 25.5, P < 0.001), higher exosome content of AMZ1 antigens (2.0 vs. 0.0; P < 0.001), and lower archaeal DNA content (0.2 vs. 1.5, P = 0.02). A positive correlation between exosomes and AMZ1 content was seen in indeterminate form (r = 0.5, P < 0.001), but not in heart failure patients (r = 0.002, P = 0.98). Higher free archaeal DNA (63.0 vs. 11.1, P < 0.001) in correlation with exosome numbers (r = 0.66, P = 0.01) was seen in heart failure but not in indeterminate form (r = 0.29, P = 0.10). Flow cytometer showed higher numbers of AMZ1 microvesicles in indeterminate form (64 vs. 36, P = 0.02) and higher archaeal DNA microvesicles in heart failure (8.1 vs. 0.9, P < 0.001). Zymography showed strong% collagenase activity in HF group, mild activity in IF compared to non-chagasic healthy group (121 ± 14, 106 ± 13 and 100; P < 0.001). Conclusions: Numerous exosomes, possibly removing and degrading abnormal AMZ1 collagenase, are associated with indeterminate form. Archaeal microvesicles and their exosomes, possibly associated with release of archaeal AMZ1 in heart failure, are future candidates of heart failure biomarkers if confirmed in larger series, and the therapeutic focus in the treatment of Chagas disease.

Left Atrial Function in Patients with Chronic Chagasic Cardiomyopathy / Função Atrial Esquerda em Pacientes com Miocardiopatia Chagásica Crônica

Chagas disease is a cause of dilated cardiomyopathy, and information about left atrial (LA) function in this disease still lacks.

A doença de Chagas é uma causa de miocardiopatia dilatada, sendo ainda pouco conhecida a função do átrio esquerdo (AE) nessa doença.

Left Atrial Function in Patients with Chronic Chagasic Cardiomyopathy.

BACKGROUND: Chagas disease is a cause of dilated cardiomyopathy, and information about left atrial (LA) function in this disease still lacks. OBJECTIVE: To assess the different LA functions (reservoir, conduit and pump functions) and their correlation with the echocardiographic parameters of left ventricular (LV) systolic and diastolic functions. METHODS: 10 control subjects (CG), and patients with Chagas disease as follows: 26 with the indeterminate form (GI); 30 with ECG alterations (GII); and 19 with LV dysfunction (GIII). All patients underwent M-mode and two-dimensional echocardiography, pulsed-wave Doppler and tissue Doppler imaging. RESULTS: Reservoir function (Total Emptying Fraction: TEF): (p <0.0001), lower in GIII as compared to CG (p = 0.003), GI (p <0.001) and GII (p <0.001). Conduit function (Passive Emptying Fraction: PEF): (p = 0.004), lower in GIII (GIII and CG, p = 0.06; GI and GII, p = 0.06; and GII and GIII, p = 0.07). Pump function (Active Emptying Fraction: AEF): (p = 0.0001), lower in GIII as compared to CG (p = 0.05), GI (p<0.0001) and GII (p = 0.002). There was a negative correlation of E/e' (average) with the reservoir and pump functions (TEF and AEF), and a positive correlation of e' (average) with s' wave (both septal and lateral walls) and the reservoir, conduit and pump LA functions. CONCLUSION: An impairment of LA functions in Chagas cardiomyopathy was observed.

Functional IL18 polymorphism and susceptibility to Chronic ChagasDisease

Background: Chronic Chagas Disease cardiomyopathy (CCC), a life-threatening inflammatory dilated cardiomyopathy,affects 30% of the approximately 8 million patients infected by Trypanosoma cruzi, the restof the infected subjects remaining asymptomatic (ASY). The Th1 T cell-rich myocarditis plays a pivotalrole in CCC pathogenesis. Local expression of IL-18 in CCC myocardial tissue has recently been described.IL-18 could potentially amplify the process by inducing increased expression of IFN-c which in turn canincrease the production of IL-18, thereby creating a positive feedback mechanism. In order to assess thecontribution of the IL-18 to susceptibility to Chronic Chagas Disease, we investigated the associationbetween a single nucleotide polymorphism (SNP) located in the IL-18 gene with the risk of developingChagas cardiomyopathy.Methods and results: We analyzed the rs2043055 marker in the IL18 gene in a cohort of Chagas diseasecardiomyopathy patients (n = 849) and asymptomatic subjects (n = 202). We found a significant differencein genotype frequencies among moderate and severe CCC patients with ventricular dysfunction.Conclusions: Our analysis suggests that the IL18 rs2043055 polymorphism- or a SNP in tight linkagedisequilibrium with it- may contribute to modulating the Chagas cardiomyopathy outcome.

Genetic susceptibility to Chagas disease cardiomyopathy: involvement of several genes of the innate immunity and chemokine-dependent migration pathways.

BACKGROUND: Chagas disease, caused by the protozoan Trypanosoma cruzi is endemic in Latin America. Thirty percent of infected individuals develop chronic Chagas cardiomyopathy (CCC), an inflammatory dilated cardiomyopathy that is, by far, the most important clinical consequence of T. cruzi infection. The others remain asymptomatic (ASY). A possible genetic component to disease progression was suggested by familial aggregation of cases and the association of markers of innate and adaptive immunity genes with CCC development. Migration of Th1-type T cells play a major role in myocardial damage. METHODS: Our genetic analysis focused on CCR5, CCL2 and MAL/TIRAP genes. We used the Tag SNPs based approach, defined to catch all the genetic information from each gene. The study was conducted on a large Brazilian population including 315 CCC cases and 118 ASY subjects. RESULTS: The CCL2rs2530797A/A and TIRAPrs8177376A/A were associated to an increase susceptibility whereas the CCR5rs3176763C/C genotype is associated to protection to CCC. These associations were confirmed when we restricted the analysis to severe CCC, characterized by a left ventricular ejection fraction under 40%. CONCLUSIONS: Our data show that polymorphisms affecting key molecules involved in several immune parameters (innate immunity signal transduction and T cell/monocyte migration) play a role in genetic susceptibility to CCC development. This also points out to the multigenic character of CCC, each polymorphism imparting a small contribution. The identification of genetic markers for CCC will provide information for pathogenesis as well as therapeutic targets.

Myocardial chemokine expression and intensity of myocarditis in Chagas cardiomyopathy are controlled by polymorphisms in CXCL9 and CXCL10.

BACKGROUND: Chronic Chagas cardiomyopathy (CCC), a life-threatening inflammatory dilated cardiomyopathy, affects 30% of the approximately 8 million patients infected by Trypanosoma cruzi. Even though the Th1 T cell-rich myocarditis plays a pivotal role in CCC pathogenesis, little is known about the factors controlling inflammatory cell migration to CCC myocardium. METHODS AND RESULTS: Using confocal immunofluorescence and quantitative PCR, we studied cell surface staining and gene expression of the CXCR3, CCR4, CCR5, CCR7, CCR8 receptors and their chemokine ligands in myocardial samples from end-stage CCC patients. CCR5+, CXCR3+, CCR4+, CCL5+ and CXCL9+ mononuclear cells were observed in CCC myocardium. mRNA expression of the chemokines CCL5, CXCL9, CXCL10, CCL17, CCL19 and their receptors was upregulated in CCC myocardium. CXCL9 mRNA expression directly correlated with the intensity of myocarditis, as well as with mRNA expression of CXCR3, CCR4, CCR5, CCR7, CCR8 and their ligands. We also analyzed single-nucleotide polymorphisms for genes encoding the most highly expressed chemokines and receptors in a cohort of Chagas disease patients. CCC patients with ventricular dysfunction displayed reduced genotypic frequencies of CXCL9 rs10336 CC, CXCL10 rs3921 GG, and increased CCR5 rs1799988CC as compared to those without dysfunction. Significantly, myocardial samples from CCC patients carrying the CXCL9/CXCL10 genotypes associated to a lower risk displayed a 2-6 fold reduction in mRNA expression of CXCL9, CXCL10, and other chemokines and receptors, along with reduced intensity of myocarditis, as compared to those with other CXCL9/CXCL10 genotypes. CONCLUSIONS: Results may indicate that genotypes associated to reduced risk in closely linked CXCL9 and CXCL10 genes may modulate local expression of the chemokines themselves, and simultaneously affect myocardial expression of other key chemokines as well as intensity of myocarditis. Taken together our results may suggest that CXCL9 and CXCL10 are master regulators of myocardial inflammatory cell migration, perhaps affecting clinical progression to the life-threatening form of CCC.

Plasma pro-B-type natriuretic peptide testing as a screening method for hypertrophic cardiomyopathy.

BACKGROUND: Clinical multistage risk assessment associated with electrocardiogram (ECG) and NT-proBNP may be a feasible strategy to screen hypertrophic cardiomyopathy (HCM). We investigated the effectiveness of a screening based on ECG and NT-proBNP in first-degree relatives of patients with HCM. METHODS AND RESULTS: A total of 106 first-degree relatives were included. All individuals were evaluated by echocardiography, ECG, NT-proBNP, and molecular screening (available for 65 individuals). From the 106 individuals, 36 (34%) had diagnosis confirmed by echocardiography. Using echocardiography as the gold standard, ECG criteria had a sensitivity of 0.71, 0.42, and 0.52 for the Romhilt-Estes, Sokolow-Lyon, and Cornell criteria, respectively. Mean values of NT-ProBNP were higher in affected as compared with nonaffected relatives (26.1 vs. 1290.5, P < .001). The AUC of NT-proBNP was 0.98. Using a cutoff value of 70 pg/mL, we observed a sensitivity of 0.92 and specificity of 0.96. Using molecular genetics as the gold standard, ECG criteria had a sensitivity of 0.67, 0.37, and 0.42 for the Romhilt-Estes, Sokolow-Lyon, and Cornell criteria, respectively. Using a cutoff value of 70 pg/mL, we observed a sensitivity of 0.83 and specificity of 0.98. CONCLUSION: Values of NT-proBNP above 70 pg/mL can be used to effectively select high-risk first-degree relatives for HCM screening.

Evidence for T Cell Help in the IgG Response against Tandemly Repetitive Trypanosoma cruzi B13 Protein in Chronic Chagas Disease Patients.

The tandemly repetitive Trypanosoma cruzi B13 protein is an immunodominant antigen among Chagas disease patients. Such repetitive domains may behave as T-independent antigens. However, T cells can recognize B13 epitopes in an HLA class II-restricted fashion and could potentially provide cognate T cell help and boost antibody titers. We assessed whether the presence of HLA class II molecules able to present B13 epitopes to T cells could affect anti-B13 IgG levels in a cognate fashion, in both major clinical forms of chronic Chagas disease. We found no difference between anti-B13 IgG antibody levels between patients carrying HLA class II molecules associated to T cell responses or other alleles. The predominant anti-B13 IgG subclass was IgG1, with negligible IgG2, suggesting a T-dependent, noncognate help for antibody production. In addition, the finding of increased anti-B13 IgG levels in sera from CCC patients indicates that clinical presentation is associated with increased anti-B13 antibody levels.

Serum NT pro-BNP: relation to systolic and diastolic function in cardiomyopathies and pericardiopathies.

BACKGROUND: NT pro-BNP is a marker of systolic and diastolic dysfunction. OBJECTIVE: To determine NT pro-BNP levels in patients with chagasic, hypertrophic, and restrictive heart diseases, as well as with pericardial diseases, and their relation to echocardiographic measurements of systolic and diastolic dysfunction. METHODS: A total of 145 patients were divided into the following groups: 1) Chagas' heart disease (CHD)--14 patients; 2) hypertrophic cardiomyopathy (HCM)--71 patients; 3) endomyocardial fibrosis (EMF)--26 patients; 4) pericardial effusion (PE)--18 patients; and 5) constrictive pericarditis (CP)--16 patients. The control group was comprised of 40 individuals with no heart disease. The degree of myocardial impairment and pericardial effusion were assessed by two-dimensional echocardiography and the degree of restriction by pulsed Doppler transmitral flow. The diagnosis of CP was confirmed through magnetic resonance imaging. NT pro-BNP levels were determined through electrochemiluminescence immunoassay. RESULTS: NT pro-BNP was increased (p < 0.001) in CHD (median = 513.8 pg/ml), HCM (median = 848 pg/ml), EMF (median = 633 pg/ml), CP (median = 568 pg/ml), and PE (median = 124 pg/ml), when compared with the control group (median = 28 pg/ml). No statistically significant differences were found between CP and EMF (p = 0.14). In the hypertrophic group, NT pro-BNP was correlated with left atrial size (r = 0.40; p < 0.001) and with E/Ea ratio (p < 0.01). In the restrictive group, there was a trend of correlation with E-wave peak velocity (r = 0.439; p = 0.06). CONCLUSION: NT pro-BNP is increased in the different cardiomyopathies and pericardial diseases and is correlated with the degree of systolic and diastolic dysfunction.