RNA-Binding Protein LIN28a Regulates New Myocyte Formation in the Heart Through Long Noncoding RNA-H19.

BACKGROUND: Developmental cardiac tissue holds remarkable capacity to regenerate after injury and consists of regenerative mononuclear diploid cardiomyocytes. On maturation, mononuclear diploid cardiomyocytes become binucleated or polyploid and exit the cell cycle. Cardiomyocyte metabolism undergoes a profound shift that coincides with cessation of regeneration in the postnatal heart. However, whether reprogramming metabolism promotes persistence of regenerative mononuclear diploid cardiomyocytes enhancing cardiac function and repair after injury is unknown. Here, we identify a novel role for RNA-binding protein LIN28a, a master regulator of cellular metabolism in cardiac repair after injury. METHODS: LIN28a overexpression was tested using mouse transgenesis on postnatal cardiomyocyte numbers, cell cycle, and response to apical resection injury. With the use of neonatal and adult cell culture systems and adult and Mosaic Analysis with Double Markers myocardial injury models in mice, the effect of LIN28a overexpression on cardiomyocyte cell cycle and metabolism was tested. Last, isolated adult cardiomyocytes from LIN28a and wild-type mice 4 days after myocardial injury were used for RNA-immunoprecipitation sequencing. RESULTS: LIN28a was found to be active primarily during cardiac development and rapidly decreases after birth. LIN28a reintroduction at postnatal day (P) 1, P3, P5, and P7 decreased maturation-associated polyploidization, nucleation, and cell size, enhancing cardiomyocyte cell cycle activity in LIN28a transgenic pups compared with wild-type littermates. Moreover, LIN28a overexpression extended cardiomyocyte cell cycle activity beyond P7 concurrent with increased cardiac function 30 days after apical resection. In the adult heart, LIN28a overexpression attenuated cardiomyocyte apoptosis, enhanced cell cycle activity, cardiac function, and survival in mice 12 weeks after myocardial infarction compared with wild-type littermate controls. Instead, LIN28a small molecule inhibitor attenuated the proreparative effects of LIN28a on the heart. Neonatal rat ventricular myocytes overexpressing LIN28a mechanistically showed increased glycolysis, ATP production, and levels of metabolic enzymes compared with control. LIN28a immunoprecipitation followed by RNA-immunoprecipitation sequencing in cardiomyocytes isolated from LIN28a-overexpressing hearts after injury identified long noncoding RNA-H19 as its most significantly altered target. Ablation of long noncoding RNA-H19 blunted LIN28a-induced enhancement on cardiomyocyte metabolism and cell cycle activity. CONCLUSIONS: Collectively, LIN28a reprograms cardiomyocyte metabolism and promotes persistence of mononuclear diploid cardiomyocytes in the injured heart, enhancing proreparative processes, thereby linking cardiomyocyte metabolism to regulation of ploidy/nucleation and repair in the heart.

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

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.

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.

A Major Downregulation of Circulating microRNAs in Zika Acutely Infected Patients: Potential Implications in Innate and Adaptive Immune Response Signaling Pathways.

Zika virus (ZIKV) is an arbovirus mainly transmitted by mosquitos of the genus Aedes. The first cases of ZIKV infection in South America occurred in Brazil in 2015. The infection in humans causes diverse symptoms from asymptomatic to a syndrome-like dengue infection with fever, arthralgia, and myalgia. Furthermore, ZIKV infection during pregnancy is associated with fetal microcephaly and neurological disorders. The identification of host molecular mechanisms responsible for the modulation of different signaling pathways in response to ZIKV is the first step to finding potential biomarkers and therapeutic targets and understanding disease outcomes. In the last decade, it has been shown that microRNAs (miRNAs) are important post-transcriptional regulators involved in virtually all cellular processes. miRNAs present in body fluids can not only serve as key biomarkers for diagnostics and prognosis of human disorders but also contribute to cellular signaling offering new insights into pathological mechanisms. Here, we describe for the first time ZIKV-induced changes in miRNA plasma levels in patients during the acute and recovery phases of infection. We observed that during ZIKV acute infection, among the dysregulated miRNAs (DMs), the majority is with decreased levels when compared to convalescent and control patients. We used systems biology tools to build and highlight biological interactions between miRNAs and their multiple direct and indirect target molecules. Among the 24 DMs identified in ZIKV + patients, miR-146, miR-125a-5p, miR-30-5p, and miR-142-3p were related to signaling pathways modulated during infection and immune response. The results presented here are an effort to open new vistas for the key roles of miRNAs during ZIKV infection.

Plasma biomarkers reflecting high oxidative stress in the prediction of myocardial injury due to anthracycline chemotherapy and the effect of carvedilol: insights from the CECCY Trial.

BACKGROUND: Anthracycline (ANT) is often used for breast cancer treatment but its clinical use is limited by cardiotoxicity (CTX). CECCY trial demonstrated that the ß-blocker carvedilol (CVD) could attenuate myocardial injury secondary to ANT. Mieloperoxydase (MPO) is a biomarker of oxidative stress and galectin-3 (Gal-3) is a biomarker of fibrosis and cardiac remodeling. We evaluated the correlation between MPO and Gal-3 behavior with CTX. MATERIALS AND METHODS: A post hoc analysis was performed in the patients who were included in the CECCY trial. A total of 192 women had her blood samples stored during the study at -80°C until the time of assay in a single batch. Stored blood samples were obtained at baseline, 3 and 6 months after randomization. We excluded samples from 18 patients because of hemolysis. MPO and Gal-3 were measured using Luminex xMAP technology through MILLIPLEX MAP KIT (Merck Laboratories). RESULTS: 26 patients (14.9%) had a decrease of at least 10% in LVEF at 6 months after the initiation of chemotherapy. Among these, there was no significant difference in the MPO and Gal-3 when compared to the group without drop in LVEF (p = 0.85 for both MPO and Gal-3). Blood levels of MPO [baseline: 13.2 (7.9, 24.8), 3 months: 17.7 (11.1, 31.1), 6 months: 19.2 (11.1, 37.8) ng/mL] and Gal-3 [baseline: 6.3 (5.2, 9.6), 3 months: 12.3 (9.8, 16.0), 6 months: 10.3 (8.2, 13.1) ng/mL] increased after ANT chemotherapy, and the longitudinal changes were similar between the placebo and CVD groups (p for interaction: 0.28 and 0.32, respectively). In an exploratory analysis, as there is no normal cutoff value established for Gal-3 and MPO in the literature, the MPO and Gal-3 results were splited in two groups: above and below median. In the placebo group, women with high (above median) baseline MPO blood levels demonstrated a greater increase in TnI blood levels than those with low baseline MPO blood levels (p = 0.041). Compared with placebo, CVD significantly reduced TnI blood levels in women with high MPO blood levels (p < 0.001), but did not reduce the TnI levels in women with low baseline MPO blood levels (p = 0.97; p for interaction = 0.009). There was no significant interaction between CVD treatment and baseline Gal-3 blood levels (p for interaction = 0.99). CONCLUSIONS: In this subanalysis of the CECCY trial, MPO and Gal-3 biomarkers did not predict the development of CTX. However, MPO blood levels above median was associated with more severe myocardial injury and identified women who were most likely to benefit from carvedilol for primary prevention (NCT01724450).

Rare Pathogenic Variants in Mitochondrial and Inflammation-Associated Genes May Lead to Inflammatory Cardiomyopathy in Chagas Disease.

Cardiomyopathies are an important cause of heart failure and sudden cardiac death. Little is known about the role of rare genetic variants in inflammatory cardiomyopathy. Chronic Chagas disease cardiomyopathy (CCC) is an inflammatory cardiomyopathy prevalent in Latin America, developing in 30% of the 6 million patients chronically infected by the protozoan Trypanosoma cruzi, while 60% remain free of heart disease (asymptomatic (ASY)). The cytokine interferon-γ and mitochondrial dysfunction are known to play a major pathogenetic role. Chagas disease provides a unique model to probe for genetic variants involved in inflammatory cardiomyopathy. METHODS: We used whole exome sequencing to study nuclear families containing multiple cases of Chagas disease. We searched for rare pathogenic variants shared by all family members with CCC but absent in infected ASY siblings and in unrelated ASY. RESULTS: We identified heterozygous, pathogenic variants linked to CCC in all tested families on 22 distinct genes, from which 20 were mitochondrial or inflammation-related - most of the latter involved in proinflammatory cytokine production. Significantly, incubation with IFN-γ on a human cardiomyocyte line treated with an inhibitor of dihydroorotate dehydrogenase brequinar (enzyme showing a loss-of-function variant in one family) markedly reduced mitochondrial membrane potential (ΔψM), indicating mitochondrial dysfunction. CONCLUSION: Mitochondrial dysfunction and inflammation may be genetically determined in CCC, driven by rare genetic variants. We hypothesize that CCC-linked genetic variants increase mitochondrial susceptibility to IFN-γ-induced damage in the myocardium, leading to the cardiomyopathy phenotype in Chagas disease. This mechanism may also be operative in other inflammatory cardiomyopathies.

Carvedilol for Prevention of Chemotherapy-Related Cardiotoxicity: The CECCY Trial.

BACKGROUND: Anthracycline (ANT) chemotherapy is associated with cardiotoxicity. Prevention with ß-blockers remains controversial. OBJECTIVES: This prospective, randomized, double-blind, placebo-controlled study sought to evaluate the role of carvedilol in preventing ANT cardiotoxicity. METHODS: The authors randomized 200 patients with HER2-negative breast cancer tumor status and normal left ventricular ejection fraction (LVEF) referred for ANT (240 mg/m2) to receive carvedilol or placebo until chemotherapy completion. The primary endpoint was prevention of a ≥10% reduction in LVEF at 6 months. Secondary outcomes were effects of carvedilol on troponin I, B-type natriuretic peptide, and diastolic dysfunction. RESULTS: Primary endpoint occurred in 14 patients (14.5%) in the carvedilol group and 13 patients (13.5%) in the placebo group (p = 1.0). No differences in changes of LVEF or B-type natriuretic peptide were noted between groups. A significant difference existed between groups in troponin I levels over time, with lower levels in the carvedilol group (p = 0.003). Additionally, a lower incidence of diastolic dysfunction was noted in the carvedilol group (p = 0.039). A nonsignificant trend toward a less-pronounced increase in LV end-diastolic diameter during the follow-up was noted in the carvedilol group (44.1 ± 3.64 mm to 45.2 ± 3.2 mm vs. 44.9 ± 3.6 mm to 46.4 ± 4.0 mm; p = 0.057). CONCLUSIONS: In this largest clinical trial of ß-blockers for prevention of cardiotoxicity under contemporary ANT dosage, the authors noted a 13.5% to 14.5% incidence of cardiotoxicity. In this scenario, carvedilol had no impact on the incidence of early onset of LVEF reduction. However, the use of carvedilol resulted in a significant reduction in troponin levels and diastolic dysfunction. (Carvedilol Effect in Preventing Chemotherapy-Induced Cardiotoxicity [CECCY]; NCT01724450).

Impact of Delayed Whole Blood Processing Time on Plasma Levels of miR- 1 and miR-423-5p up to 24 Hours.

BACKGROUND: Circulating cell-free miRNAs hold great promise as a new class of biomarkers due to their high stability in body fluids and association with disease stages. However, even using sensitive and specific methods, technical challenges are associated with miRNA analysis in body fluids. A major source of variation in plasma and serum is the potential cell-derived miRNA contamination from hemolysis. OBJECTIVES: The study aimed to evaluate the effect of the delayed whole blood processing time on the concentrations of miR-1 and -423-5p. METHODS: Ten blood samples were incubated for 0, 3 and 24 hours at room temperature prior to processing into plasma. For each time point, hemolysis was assessed in plasma by UV spectrophotometry at 414nm wavelength (λ414). Circulating levels of miR-1 and -423-5p were measured by RT-qPCR; miR-23a and -451 were also analyzed as controls. RESULTS: A significant hemolysis was observed only after 24h (λ414 0.3 ± 0.02, p < 0.001). However, only small changes in miR-1 and -423-5p levels were observed up to 24h of storage at room temperature (Ct 31.5 ± 0.5 to 31.8 ± 0.6for miR-1, p = 0.989; and 29.01 ± 0.3 to 29.04 ± 0.3, p = 0.614 for - 423-5p). No correlation was observed between hemolysis and the levels of miR-1 and -423-5p. CONCLUSION: Our data indicate that the storage of whole blood samples at room temperature for up to 24h prior to their processing into plasma does not appear to have a significant impact on miR-1 and - 423-5p concentrations.

Whole-Genome Cardiac DNA Methylation Fingerprint and Gene Expression Analysis Provide New Insights in the Pathogenesis of Chronic Chagas Disease Cardiomyopathy.

Background: Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and affects 10 million people worldwide. Approximately 12000 deaths attributable to Chagas disease occur annually due to chronic Chagas disease cardiomyopathy (CCC), an inflammatory cardiomyopathy presenting with heart failure and arrythmia; 30% of infected subjects develop CCC years after infection. Genetic mechanisms play a role in differential progression to CCC, but little is known about the role of epigenetic modifications in pathological gene expression patterns in CCC patients' myocardium. DNA methylation is the most common modification in the mammalian genome. Methods: We investigated the impact of genome-wide cardiac DNA methylation on global gene expression in myocardial samples from end-stage CCC patients, compared to control samples from organ donors. Results: In total, 4720 genes were differentially methylated between CCC patients and controls, of which 399 were also differentially expressed. Several of them were related to heart function or to the immune response and had methylation sites in their promoter region. Reporter gene and in silico transcription factor binding analyses indicated promoter methylation modified expression of key genes. Among those, we found potassium channel genes KCNA4 and KCNIP4, involved in electrical conduction and arrythmia, SMOC2, involved in matrix remodeling, as well as enkephalin and RUNX3, potentially involved in the increased T-helper 1 cytokine-mediated inflammatory damage in heart. Conclusions: Results support that DNA methylation plays a role in the regulation of expression of pathogenically relevant genes in CCC myocardium, and identify novel potential disease pathways and therapeutic targets in CCC.

Circulating miR-1 as a potential biomarker of doxorubicin-induced cardiotoxicity in breast cancer patients.

Cardiotoxicity is associated with the chronic use of doxorubicin leading to cardiomyopathy and heart failure. Identification of cardiotoxicity-specific miRNA biomarkers could provide clinicians with a valuable prognostic tool. The aim of the study was to evaluate circulating levels of miRNAs in breast cancer patients receiving doxorubicin treatment and to correlate with cardiac function. This is an ancillary study from "Carvedilol Effect on Chemotherapy-induced Cardiotoxicity" (CECCY trial), which included 56 female patients (49.9±3.3 years of age) from the placebo arm. Enrolled patients were treated with doxorubicin followed by taxanes. cTnI, LVEF, and miRNAs were measured periodically. Circulating levels of miR-1, -133b, -146a, and -423-5p increased during the treatment whereas miR-208a and -208b were undetectable. cTnI increased from 6.6±0.3 to 46.7±5.5 pg/mL (p<0.001), while overall LVEF tended to decrease from 65.3±0.5 to 63.8±0.9 (p=0.053) over 12 months. Ten patients (17.9%) developed cardiotoxicity showing a decrease in LVEF from 67.2±1.0 to 58.8±2.7 (p=0.005). miR-1 was associated with changes in LVEF (r=-0.531, p<0.001). In a ROC curve analysis miR-1 showed an AUC greater than cTnI to discriminate between patients who did and did not develop cardiotoxicity (AUC = 0.851 and 0.544, p= 0.0016). Our data suggest that circulating miR-1 might be a potential new biomarker of doxorubicin-induced cardiotoxicity in breast cancer patients.

Blood Gene Signatures of Chagas Cardiomyopathy With or Without Ventricular Dysfunction.

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects 7 million people in Latin American areas of endemicity. About 30% of infected patients will develop chronic Chagas cardiomyopathy (CCC), an inflammatory cardiomyopathy characterized by hypertrophy, fibrosis, and myocarditis. Further studies are necessary to understand the molecular mechanisms of disease progression. Transcriptome analysis has been increasingly used to identify molecular changes associated with disease outcomes. We thus assessed the whole-blood transcriptome of patients with Chagas disease. Microarray analysis was performed on blood samples from 150 subjects, of whom 30 were uninfected control patients and 120 had Chagas disease (1 group had asymptomatic disease, and 2 groups had CCC with either a preserved or reduced left ventricular ejection fraction [LVEF]). Each Chagas disease group displayed distinct gene expression and functional pathway profiles. The most different expression patterns were between CCC groups with a preserved or reduced LVEF. A more stringent analysis indicated that 27 differentially expressed genes, particularly those related to natural killer (NK)/CD8+ T-cell cytotoxicity, separated the 2 groups. NK/CD8+ T-cell cytotoxicity could play a role in determining Chagas disease progression. Understanding genes associated with disease may lead to improved insight into CCC pathogenesis and the identification of prognostic factors for CCC progression.