Unraveling the Etiology of Dilated Cardiomyopathy through Differential miRNA-mRNA Interactome

Dilated cardiomyopathy (DCM) encompasses various acquired or genetic diseases sharing a common phenotype. The understanding of pathogenetic mechanisms and the determination of the functional effects of each etiology may allow for tailoring different therapeutic strategies. MicroRNAs (miRNAs) have emerged as key regulators in cardiovascular diseases, including DCM. However, their specific roles in different DCM etiologies remain elusive. Here, we applied mRNA-seq and miRNA-seq to identify the gene and miRNA signature from myocardial biopsies from four patients with DCM caused by volume overload (VCM) and four with ischemic DCM (ICM). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were used for differentially expressed genes (DEGs). The miRNA-mRNA interactions were identified by Pearson correlation analysis and miRNA target-prediction programs. mRNA-seq and miRNA-seq were validated by qRT-PCR and miRNA-mRNA interactions were validated by luciferase assays. We found 112 mRNAs and five miRNAs dysregulated in VCM vs. ICM. DEGs were positively enriched for pathways related to the extracellular matrix (ECM), mitochondrial respiration, cardiac muscle contraction, and fatty acid metabolism in VCM vs. ICM and negatively enriched for immune-response-related pathways, JAK-STAT, and NF-kappa B signaling. We identified four pairs of negatively correlated miRNA-mRNA: miR-218-5p-DDX6, miR-218-5p-TTC39C, miR-218-5p-SEMA4A, and miR-494-3p-SGMS2. Our study revealed novel miRNA-mRNA interaction networks and signaling pathways for VCM and ICM, providing novel insights into the development of these DCM etiologies.

Prevalence and Clinical Burden of Idiopathic Dilated Cardiomyopathy in the United States

Background

Dilated cardiomyopathy (DCM) contributes significantly to heart failure prevalence, yet supporting epidemiologic data is sparse. This study sought to estimate the period prevalence of DCM and the proportion of idiopathic DCM in the United States using a large, diverse electronic health records (EHR) database.

Methods

This retrospective, observational study included 56,812,806 deidentified patients in Optum EHR with visits between 2017 and 2019. Suspected DCM cases were identified using ICD-10 coding. Deidentified clinical notes from 1000 randomly selected cases were manually reviewed to determine the diagnosis of DCM and estimate the proportion of idiopathic DCM. The period prevalence and clinical burden of DCM and idiopathic DCM were estimated.

Results

Manual clinical review demonstrated that our definition had a positive predictive value of 92.5% for DCM, with 46.3% estimated as the idiopathic DCM proportion. The estimated period prevalence of DCM between 2017 and 2019 was 118.33 per 100,000. Prevalence increased for adults ≥65 years of age, males, and African Americans. Extrapolation to the 2019 US population led to an overall estimated burden of roughly 388,350 patients. Adjusting for the proportion of cases with idiopathic DCM yielded an idiopathic DCM prevalence of 59.23 per 100,000 and a burden of 194,385 patients. Evidence of clinical genetic testing in this population was scarce, with less than 0.43% of DCM cases reporting a testing code.

Conclusions

This study establishes a conservative period prevalence for DCM and idiopathic DCM and demonstrates very low molecular genetic testing for DCM. These findings suggest that the clinical burden of genetic DCM may be underestimated.

A Kaposi's sarcoma-associated herpes virus-encoded microRNA contributes to dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is the leading cause of heart transplantation. By microRNA (miRNA) array, a Kaposi's sarcoma-associated herpes virus (KSHV)-encoded miRNA, kshv-miR-K12-1-5p, was detected in patients with DCM. The KSHV DNA load and kshv-miR-K12-1-5p level in plasma from 696 patients with DCM were measured and these patients were followed-up. Increased KSHV seropositivity and quantitative titers were found in the patients with DCM compared with the non-DCM group (22.0% versus 9.1%, p < 0.05; 168 versus 14 copies/mL plasma, p < 0.05). The risk of the individual end point of death from cardiovascular causes or heart transplantation was increased among DCM patients with the KSHV DNA seropositivity during follow-up (adjusted hazard ratio 1.38, 95% confidence interval 1.01-1.90; p < 0.05). In heart tissues, the KSHV DNA load was also increased in the heart from patients with DCM in comparison with healthy donors (1016 versus 29 copies/105 cells, p < 0.05). The KSHV and kshv-miR-K12-1-5p in DCM hearts were detected using immunofluorescence and fluorescence staining in situ hybridization. KSHV itself was exclusively detectable in CD31-positive endothelium, while kshv-miR-K12-1-5p could be detected in both endothelium and cardiomyocytes. Moreover, kshv-miR-K12-1-5p released by KSHV-infected cardiac endothelium could disrupt the type I interferon signaling pathway in cardiomyocytes. Two models of kshv-miR-K12-1-5p overexpression (agomiR and recombinant adeno-associated virus) were used to explore the roles of KSHV-encoded miRNA in vivo. The kshv-miR-K12-1-5p aggravated known cardiotropic viruses-induced cardiac dysfunction and inflammatory infiltration. In conclusion, KSHV infection was a risk factor for DCM, providing developmental insights of DCM involving virus and its miRNA ( https://clinicaltrials.gov . Unique identifier: NCT03461107).

Pragmatic electrocardiogram tracings in non-ischaemic dilated cardiomyopathy: diagnostic and prognostic role

Dilated cardiomyopathy (DCM) is a primitive heart muscle disease characterized by a great heterogeneous aetiology and prognostic outcome. Dilated cardiomyopathy is an umbrella term encompassing different aetiologies that might require specific treatments. It principally affects young and male adults, with high-risk arrhythmic competitive risk. Unfortunately, the prevention of major ventricular arrhythmic events remains a clinical challenge. In the era of advanced multimodality imaging and widely available genetic testing, electrocardiogram (ECG) continues to represent a reliable diagnostic tool, for specific work up of every single patient. However, approaching DCM patients, only a cardiomyopathy-oriented reading makes the role of ECG central in the management of DCM, both for diagnosis, prognosis, and therapeutic management. In this paper, we present four ECGs of four different DCM patients, in order to guide a cardiomyopathy-oriented ECG reading, emphasizing its impact in an early, cost-effective, and personalized diagnostic and prognostic work up in this specific setting.

From the phenotype to precision medicine: an update on the cardiomyopathies diagnostic workflow

Cardiomyopathies are disease of the cardiac muscle largely due to genetic alterations of proteins with 'structural' or 'functional' roles within the cardiomyocyte, going from the regulation of contraction-relaxation, metabolic and energetic processes to ionic fluxes. Modifications occurring to these proteins are responsible, in the vast majority of cases, for the phenotypic manifestations of the disease, including hypertrophic, dilated, arrhythmogenic and restrictive cardiomyopathies. Secondary nonhereditary causes to be excluded include infections, toxicity from drugs or alcohol or medications, hormonal imbalance and so on. Obtaining a phenotypic definition and an etiological diagnosis is becoming increasingly relevant and feasible, thanks to the availability of new tailored treatments and the diagnostic advancements made particularly in the field of genetics. This is, for example, the case for transthyretin cardiac amyloidosis, Fabry disease or dilated cardiomyopathies due to laminopathies. For these diseases, specific medications have been developed, and a more tailored arrhythmic risk stratification guides the implantation of a defibrillator. In addition, new medications directly targeting the altered protein responsible for the phenotype are becoming available (including the myosin inhibitors mavacantem and aficamten, monoclonal antibodies against Ras-MAPK, genetic therapies for sarcoglycanopathies), thus making a precision medicine approach less unrealistic even in the field of cardiomyopathies. For these reasons, a contemporary approach to cardiomyopathies must consider diagnostic algorithms founded on the clinical suspicion of the disease and developed towards a more precise phenotypic definition and etiological diagnosis, based on a multidisciplinary methodology putting together specialists from different disciplines, facilities for advanced imaging testing and genetic and anatomopathological competencies.

Role of oxidative stress and inflammation-related signaling pathways in doxorubicin-induced cardiomyopathy

Doxorubicin (DOX) is a powerful and commonly used chemotherapeutic drug, used alone or in combination in a variety of cancers, while it has been found to cause serious cardiac side effects in clinical application. More and more researchers are trying to explore the molecular mechanisms of DOX-induced cardiomyopathy (DIC), in which oxidative stress and inflammation are considered to play a significant role. This review summarizes signaling pathways related to oxidative stress and inflammation in DIC and compounds that exert cardioprotective effects by acting on relevant signaling pathways, including the role of Nrf2/Keap1/ARE, Sirt1/p66Shc, Sirt1/PPAR/PGC-1α signaling pathways and NOS, NOX, Fe²⁺ signaling in oxidative stress, as well as the role of NLRP3/caspase-1/GSDMD, HMGB1/TLR4/MAPKs/NF-κB, mTOR/TFEB/NF-κB pathways in DOX-induced inflammation. Hence, we attempt to explain the mechanisms of DIC in terms of oxidative stress and inflammation, and to provide a theoretical basis or new idea for further drug research on reducing DIC. Video Abstract.

Clinical characterization and natural history of chemotherapy-induced dilated cardiomyopathy

AIMS

Chemotherapy-induced dilated cardiomyopathy (CI-DCM) is a well-recognized phenotype of non-ischemic dilated cardiomyopathy (DCM), characterized by poor outcomes. However, a detailed comparison between idiopathic DCM (iDCM) and CI-DCM is still lacking.

METHODS AND RESULTS

All consecutive DCM patients enrolled in the Trieste Muscle Heart Disease Registry were analysed. CI-DCM and iDCM were defined according to current recommendations. The primary study outcome measure was all-mortality death and secondary outcomes were a) a composite of cardiovascular death/heart-transplantation/ventricular-assist-device implantation, and b) major ventricular arrhythmias. The study included 551 patients (499 iDCM and 52 CI-DCM). At enrolment, compared with iDCM, CI-DCM patients were older (51 ± 14 years vs. 58 ± 3 years, respectively, P < 0.001) and had a higher left ventricular ejection fraction (32% ± 9 vs. 35% ± 10, respectively, P = 0.03). Over a median follow-up of 90 months (IQR 54-140 months), CI-DCM patients had a higher incidence of all-cause mortality compared with iDCM (36.5% vs. 8.4% in CI-DCM and iDCM respectively, P < 0.001), while the incidence of major ventricular arrhythmias was higher in the iDCM group compared with CI-DCM (4% vs. 0%, in CI-DCM and iDCM respectively, P = 0.03). The risk of the composite outcome was comparable between the two groups (P = 0.91). At Cox multivariable analysis, the diagnosis of CI-DCM emerged as independently associated to primary outcome (HR 6.42, 95% C.I. 2.52-16.31, P < 0.001).

CONCLUSIONS

In a well-selected DCM cohort, patients with a chemotherapy-induced aetiology had a higher incidence of all-cause mortality compared with iDCM. Conversely, the incidence of life-threatening ventricular arrhythmic events was higher among patients with iDCM.

Dilated cardiomyopathy in the era of precision medicine: latest concepts and developments

Dilated cardiomyopathy (DCM) is an umbrella term entailing a wide variety of genetic and non-genetic etiologies, leading to left ventricular systolic dysfunction and dilatation, not explained by abnormal loading conditions or coronary artery disease. The clinical presentation can vary from asymptomatic to heart failure symptoms or sudden cardiac death (SCD) even in previously asymptomatic individuals. In the last 2 decades, there has been striking progress in the understanding of the complex genetic basis of DCM, with the discovery of additional genes and genotype-phenotype correlation studies. Rigorous clinical work-up of DCM patients, meticulous family screening, and the implementation of advanced imaging techniques pave the way for a more efficient and earlier diagnosis as well as more precise indications for implantable cardioverter defibrillator implantation and prevention of SCD. In the era of precision medicine, genotype-directed therapies have started to emerge. In this review, we focus on updates of the genetic background of DCM, characteristic phenotypes caused by recently described pathogenic variants, specific indications for prevention of SCD in those individuals and genotype-directed treatments under development. Finally, the latest developments in distinguishing athletic heart syndrome from subclinical DCM are described.

Integrative bioinformatics analysis of potential therapeutic targets and immune infiltration characteristics in dilated cardiomyopathy

Background

Dilated cardiomyopathy (DCM) is currently the major cause of systolic heart failure. This study explored potential therapeutic targets and investigated the role of immune cell infiltration in DCM.

Methods

Three DCM datasets (GSE3585, GSE9800, and GSE84796) from the Gene Expression Omnibus (GEO) database were merged into an integrated dataset, and batch effects were removed. Differentially expressed genes (DEGs) were screened and the associations between gene co-expression modules and clinical traits were assessed by weighted gene co-expression network analysis (WGCNA) in R software. Any DEGs from the integrated dataset overlapped with the significant module genes were defined as common genes (CGs). Enrichment analysis of the CGs was performed. The protein-protein interaction (PPI) network of the CGs was visualized and the hub gene was identified by using Cytoscape 3.8.2 software. The miRNA-transcription factor-mRNA (miRNA-TF-mRNA) network was constructed using Cytoscape to unveil the regulatory relationships in DCM. Finally, the CIBERSORT method (https://cibersort.stanford.edu/) was used to investigate immune cell infiltration in DCM.

Results

A total of 53 DEGs were identified, and 5 gene co-expression modules were detected by WGCNA of the DCM and control group samples of cardiac tissue. Genes such as FRZB, ASPN, and PHLDA1 were significantly upregulated, whereas IDH2 and ENDOG were significantly downregulated. Functional enrichment analysis showed that CGs were mainly enriched in the extracellular matrix (ECM) signaling pathway. ASPN was the hub gene in the PPI network. The miRNA-TF-mRNA network revealed that FRZB and ASPN were targeted by paired related homeobox 2 (Prrx2). We also found that miR-129-5p could regulate ASPN, PHLDA1, and IDH2 simultaneously. The immune infiltration analysis revealed higher levels of M1 macrophages in DCM samples than in the control samples.

Conclusions

In conclusion, we speculate that miR-129-5p might target ASPN in regulating DCM via the ECM signaling pathway. Macrophage infiltration may be involved in ECM remodeling and eventually lead to DCM.

Anticoagulation in cardiomyopathy: unravelling the hidden threat and challenging the threat individually

Cardiomyopathy comprises a heterogeneous group of myocardial abnormalities, structural or functional in nature, in the absence of coronary artery disease and other abnormal loading conditions. These myocardial pathologies can result in premature death or disability from progressive heart failure, arrhythmia, stroke, or other embolic events. The European Cardiomyopathy Registry reports a high stroke risk in cardiomyopathy patients ranging from 2.1% to 4.5%, as well as high prevalence of atrial fibrillation ranging from 14.0% to 48.5%. There is a growing interest in evaluating the risk of thromboembolism depending on the type of cardiomyopathy, as well as if anticoagulation is indicated in patients with cardiomyopathy without atrial fibrillation. Data available do not unequivocally support anticoagulation therapy in all of these patients; the management of these patients remains challenging. Many published reports pertaining to the risk of thromboembolism and consecutive treatment strategies mainly focus on single cardiomyopathy subtype. We summarize essential pathophysiological knowledge and review current literature associated with thromboembolism in various cardiomyopathy subtypes, providing recommendations for the diagnostic evaluation as well as clinical management strategies in this field. Certain cardiomyopathy subtypes require anticoagulation independent of atrial fibrillation or CHA2 DS2 -VASc score. Despite the scarcity of evidence regarding the choice of anticoagulation regimen (vitamin K antagonist vs. non-vitamin K oral anticoagulants) in cardiomyopathy, it is discussed and reviewed in this article. Each patient should receive a tailored strategy based on thorough clinical evaluation, published evidence, and clinical experience, due to the current recommendations mostly developed on small-sample studies or empirical evidence. The future research priorities in this area are also addressed in this article.

Echocardiographic Advances in Dilated Cardiomyopathy

Although the overall survival of patients with dilated cardiomyopathy (DCM) has improved significantly in the last decades, a non-negligible proportion of DCM patients still shows an unfavorable prognosis. DCM patients not only need imaging techniques that are effective in diagnosis, but also suitable for long-term follow-up with frequent re-evaluations. The exponential growth of echocardiography’s technology and performance in recent years has resulted in improved diagnostic accuracy, stratification, management and follow-up of patients with DCM. This review summarizes some new developments in echocardiography and their promising applications in DCM. Although nowadays cardiac magnetic resonance (CMR) remains the gold standard technique in DCM, the echocardiographic advances and novelties proposed in the manuscript, if properly integrated into clinical practice, could bring echocardiography closer to CMR in terms of accuracy and may certify ultrasound as the technique of choice in the follow-up of DCM patients. The application in DCM patients of novel echocardiographic techniques represents an interesting emergent research area for scholars in the near future.

Contemporary etiology and prognosis of dilated non-ischemic cardiomyopathy

INTRODUCTION

Non-ischemic dilated cardiomyopathy (NI-DCM) represents a specific etiology of systolic heart failure that usually affect young individuals with a genetic background in up to 40% of cases. Behind the term NI-DCM there is a spectrum of different diseases, and an accurate etiological classification appears pivotal for the clinical management and prognostic stratification of these patients.

EVIDENCE ACQUISITION

In the last years the prognosis of NI-DCM patients dramatically improved thanks to the progresses in medical treatment/ device therapy and earlier diagnosis especially in familial context. In this review we summarize the actual state of art in the management of these patients.

EVIDENCE SYNTHESIS

In the era of precision medicine, a lot of progresses have been made to expand our knowledge on the management of NI-DCM patients. A complex interaction between genotype and external triggers is the main determinant of the clinical phenotype in NI-DCM, and a lot of efforts must be done by clinicians to systematically rule out all the possible causes involved in the pathogenesis. Progresses in cardiac imaging and familial screening led us to detect subtle abnormalities in the initial phase of the disease and also helped us to furtherly stratify the prognosis and arrhythmic risk of these patients. It is plausible that a more precise etiological classification will be needed in the near future.

CONCLUSIONS

NI-DCM contains a spectrum of different diseases. Proper etiological classification, early diagnosis and strict follow-up are essential to tailor care of these patients.

Circulating microRNA-29-5p can add to the discrimination between dilated cardiomyopathy and ischaemic heart disease

Aims

Heart failure describes a large and heterogeneous spectrum of underlying cardiac diseases. MicroRNAs (miRs) are small non‐coding RNAs that in recent years have been shown to play an important role in the pathogenesis of heart failure. Cardiac magnetic resonance imaging is a powerful imaging modality for the evaluation of cardiac characteristics in heart failure. In this study, we sought to compare heart failure patients with a diagnosis of either idiopathic dilated cardiomyopathy (DCM) or ischaemic heart disease (IHD), in the context of serum levels of certain miRs and also magnetic resonance imaging parameters of cardiac structure and function.

Methods and results

A total of 135 subjects were studied: 53 patients with DCM (age: 59 ± 12 years, mean ± SD), 34 patients with IHD (66 ± 9 years), and 48 controls (64 ± 5 years). The participants underwent baseline medical examination, blood sampling, and a cardiac magnetic resonance imaging examination at 3 Tesla (Philips Ingenia). The serum levels of seven different miRs were analysed and assessed: 16‐5p, 21‐5p, 29‐5p, 133a‐3p, 191‐5p, 320a, and 423‐5p, all of which have been demonstrated to play potential roles in the pathogenesis of heart failure.

The patients in the DCM and IHD groups had left ventricles that had larger end‐diastolic volume (P < 0.001), larger mass (P < 0.001), and lower ejection fraction (P < 0.001) compared with controls. Serum levels of miR‐29‐5p were increased in DCM compared with IHD (P < 0.005) and serum levels of miR‐320a were elevated in DCM compared with healthy controls (P < 0.05). There was no significant association between miR levels and magnetic resonance imaging parameters of left ventricular structure and function.

Conclusions

Circulating miR‐320a can add to the discrimination between patients with DCM and healthy controls and circulating miR‐29‐5p can add to the discrimination between DCM and IHD.

Phenotypic clustering of dilated cardiomyopathy patients highlights important pathophysiological differences

AIMS

The dilated cardiomyopathy (DCM) phenotype is the result of combined genetic and acquired triggers. Until now, clinical decision-making in DCM has mainly been based on ejection fraction (EF) and NYHA classification, not considering the DCM heterogenicity. The present study aimed to identify patient subgroups by phenotypic clustering integrating aetiologies, comorbidities, and cardiac function along cardiac transcript levels, to unveil pathophysiological differences between DCM subgroups.

METHODS AND RESULTS

We included 795 consecutive DCM patients from the Maastricht Cardiomyopathy Registry who underwent in-depth phenotyping, comprising extensive clinical data on aetiology and comorbodities, imaging and endomyocardial biopsies. Four mutually exclusive and clinically distinct phenogroups (PG) were identified based upon unsupervised hierarchical clustering of principal components: [PG1] mild systolic dysfunction, [PG2] auto-immune, [PG3] genetic and arrhythmias, and [PG4] severe systolic dysfunction. RNA-sequencing of cardiac samples (n = 91) revealed a distinct underlying molecular profile per PG: pro-inflammatory (PG2, auto-immune), pro-fibrotic (PG3; arrhythmia), and metabolic (PG4, low EF) gene expression. Furthermore, event-free survival differed among the four phenogroups, also when corrected for well-known clinical predictors. Decision tree modelling identified four clinical parameters (auto-immune disease, EF, atrial fibrillation, and kidney function) by which every DCM patient from two independent DCM cohorts could be placed in one of the four phenogroups with corresponding outcome (n = 789; Spain, n = 352 and Italy, n = 437), showing a feasible applicability of the phenogrouping.

CONCLUSION

The present study identified four different DCM phenogroups associated with significant differences in clinical presentation, underlying molecular profiles and outcome, paving the way for a more personalized treatment approach.

Obesity, inflammation, and heart failure: links and misconceptions

Obesity has been linked with heart failure (HF) with preserved left ventricular (LV) ejection fraction (HFpEF). This link has been attributed to obesity-induced metabolic and inflammatory disturbances leading to HFpEF. However, HF is a syndrome in which disease evolvement is associated with a dynamic unraveling of functional and structural changes leading to unique disease trajectories, creating a spectrum of phenotypes with overlapping distinct characteristics extending beyond the LV ejection fraction (LVEF). In this regard, despite quantitative differences between the two extremes (HFpEF and HF with reduced LVEF, HFrEF), there is important overlap between the phenotypes along the entire spectrum. In this paper, we describe the systemic pro-inflammatory state that is present throughout the HF spectrum and emphasize that obesity intertwines with HF beyond the LVEF construct.