Relations between circulating microRNAs and atrial fibrillation: data from the Framingham Offspring Study

Identification of miR-1 and miR-499 in chronic atrial fibrillation by bioinformatics analysis and experimental validation

Background

Atrial fibrillation (AF) is one of the most prevalent arrhythmias and is characterized by a high risk of heart failure and embolic stroke, yet its underlying mechanism is unclear. The primary goal of this study was to establish a miRNA-mRNA network and identify the miRNAs associated with chronic AF by bioinformatics and experimental validation.

Methods

The GSE79768 dataset was collected from the Gene Expression Omnibus(GEO) database to extract data from patients with or without persistent AF. Differentially expressed genes (DEGs) were identified in left atrial appendages (LAAs). The STRING platform was utilized for protein-protein interaction (PPI) network analysis. The target miRNAs for the top 20 hub genes were predicted by using the miRTarBase Web tool. The miRNA-mRNA network was established and visualized using Cytoscape software. The key miRNAs selected for verification in the animal experiment were confirmed by miRwalk Web tool. We used a classic animal model of rapid ventricular pacing for chronic AF. Two groups of animals were included in the experiment, namely, the ventricular pacing group (VP group), where ventricular pacing was maintained at 240-280 bpm for 2 weeks, and the control group was the sham-operated group (SO group). Finally, we performed reverse transcription-quantitative polymerase chain reaction (RT-qPCR) to validate the expression of miR-1 and miR-499 in LAA tissues of the VP group and the SO group. Left atrial fibrosis and apoptosis were evaluated by Masson staining and caspase-3 activity assays, respectively.

Results

The networks showed 48 miRNAs in LAA tissues. MiR-1 and miR-499 were validated using an animal model of chronic AF. The expression level of miR-1 was increased, and miR-499 was decreased in VP group tissues compared to SO group tissues in LAAs (P < 0.05), which were correlated with left atrial fibrosis and apoptosis in AF.

Conclusion

This study provides a better understanding of the alterations in miRNA-1 and miR-499 in chronic AF from the perspective of the miRNA-mRNA network and corroborates findings through experimental validation. These findings may offer novel potential therapeutic targets for AF in the future.

No Detectable Differences in microRNA Plasma Levels between Diabetic Hypertensive Patients with and without Incident Subclinical Atrial Fibrillation

Background: Long-term rhythm monitoring (LTRM) can detect undiagnosed atrial fibrillation (AF) in patients at risk of AF and stroke. Circulating microRNAs (miRNAs), which have been shown to play a role in atrial electrical and structural remodelling, could help to select patients who would benefit most from LTRM. The aim of this study was to investigate whether patients with diabetes mellitus (DM) and hypertension and screen-detected subclinical AF (SCAF) using an insertable cardiac monitor (ICM) have significantly different plasma baseline levels of five selected miRNAs playing a role in the modulation of atrial electrical and structural remodelling (miR-21-5p, miR-29b-3p, miR-150-5p, miR-328-3p, and miR-432-5p) compared to those without SCAF. Methods: This study was performed at the outpatient clinic of a secondary academic teaching hospital between December 2013 and November 2015. Eligible patients were ≥65 years of age with DM and hypertension but without known heart diseases. All patients received an ICM. On the day of ICM implantation, blood samples for the measurement of plasma levels of the five miRNAs were drawn. In this post hoc analysis, we investigated their expression by reverse transcription-quantitative polymerase chain reaction. MiRNA plasma levels in patients with and without newly detected SCAF were compared. Results: We included 82 consecutive patients (median age of 71.3 years (IQR 67.4-75.1)), who were followed for a median of 588 days (IQR: 453-712 days). Seventeen patients (20.7%) had ICM-detected SCAF. Plasma levels of miR-328-3p, miR-29b-3p, miR-21-5p, miR-432-5p, and miR-150-5p were slightly but not significantly different in patients with incident SCAF compared with patients without. Conclusions: In patients with hypertension and DM, newly detected SCAF was not significantly associated with changes in expression levels of miR-21-5p, miR-29b-3p, miR-150-5p, miR-328-3p, and miR-432-5p.

Pathophysiology and clinical relevance of atrial myopathy

Atrial myopathy is a condition that consists of electrical, structural, contractile, and autonomic remodeling of the atria and is the substrate for development of atrial fibrillation, the most common arrhythmia. Pathophysiologic mechanisms driving atrial myopathy are inflammation, oxidative stress, atrial stretch, and neurohormonal signals, e.g., angiotensin-II and aldosterone. These mechanisms initiate the structural and functional remodeling of the atrial myocardium. Novel therapeutic strategies are being developed that target the pathophysiologic mechanisms of atrial myopathy. In this review, we will discuss the pathophysiology of atrial myopathy, as well as diagnostic and therapeutic strategies.

MicroRNAs: diagnostic, prognostic and therapeutic role in heart failure-a review

Heart failure is a leading cause of morbidity and mortality, with relevant social and economic burden on global healthcare system. Although the development of novel diagnostic tools and the advance in therapies have deeply influenced the diagnosis and treatment of this disease, improving both prognosis and life expectancy of patients, hospitalization is still high, and mortality remains considerable. MicroRNAs are small endogenous RNA molecules that post-transcriptionally regulate gene expression in both physiological and pathological processes. In recent years, microRNA have arisen as attractive therapeutic targets in the treatment of a wide spectrum of pathologies, including heart failure. In cardiac pathology, deregulation of microRNAs expression and function is associated to adverse outcome and heart failure progression. Circulating levels of specific microRNAs have emerged as useful biomarkers for the diagnosis of heart failure or as prognostic indicators. In the present review, we summarize the state of current research on the role of miRNAs as biomarkers for diagnosis and prognosis in patients with heart failure and their use as potential therapeutic targets for this condition.

Circulating miR-451a Expression May Predict Recurrence in Atrial Fibrillation Patients after Catheter Pulmonary Vein Ablation

Atrial fibrillation is the most prevalent tachyarrhythmia in clinical practice, with very high cardiovascular morbidity and mortality with a high-cost impact in health systems. Currently, it is one of the main causes of stroke and subsequent heart failure and sudden death. miRNAs mediate in several processes involved in cardiovascular disease, including fibrosis and electrical and structural remodeling. Several studies suggest a key role of miRNAs in the course and maintenance of atrial fibrillation. In our study, we aimed to identify the differential expression of circulating miRNAs and their predictive value as biomarkers of recurrence in atrial fibrillation patients undergoing catheter pulmonary vein ablation. To this effect, 42 atrial fibrillation patients were recruited for catheter ablation. We measured the expression of 84 miRNAs in non-recurrent and recurrent groups (45.2%), both in plasma from peripheral and left atrium blood. Expression analysis showed that miRNA-451a is downregulated in recurrent patients. Receiver operating characteristic curve analysis showed that miR-451a in left atrium plasma could predict atrial fibrillation recurrence after pulmonary vein isolation. In addition, atrial fibrillation recurrence is positively associated with the increment of scar percentage. Our data suggest that miRNA-451a expression plays an important role in AF recurrence by controlling fibrosis and progression.

Association between leucocyte telomere length and the risk of atrial fibrillation: An updated systematic review and meta-analysis

BACKGROUND AND AIMS

Advancing age is the most important risk factor of atrial fibrillation (AF). The shortening of telomere length is a biomarker of biologic aging. There is an increasing body of evidence that leucocyte telomere length (LTL) is associated with the risk of AF development. However, the results in these studies were controversial. The current systematic review and meta-analysis was conducted to examine the role of LTL in predicting the incidence of AF.

METHODS AND RESULTS

Observational studies reporting the association between LTL and the risk of AF were retrieved through 25th June, 2022 from PubMed and Embase. A total of twelve studies including 18,293 patients were included in the present analysis. Leucocyte telomere shortening was found to be an independent predictor of AF as a continuous variable in both univariate [OR:2.14; 95%CI(1.48,3.10); P < 0.0001] and multivariate analyses [OR:1.41;95%CI(1.11,1.79); P = 0.005], as well as categorical variable in multivariate analysis [OR:1.53; 95%CI(1.04,2.27); P = 0.03]. Furthermore, leucocyte telomere shortening was significantly associated with recurrent AF [OR:4.32;95%CI(2.42,7.69); P < 0.00001] but not new-onset AF [OR:1.14; 95%CI(0.90,1.45); P = 0.29]. Leucocyte telomere shortening was also associated with an increased risk of persistent AF [OR:14.73;95%CI (3.16,68.67); P = 0.0006] and paroxysmal AF [OR:2.74;95%CI(1.45,5.18); P = 0.002]. Besides, LTL was an independent predictor for progression from paroxysmal AF to persistent AF [OR:3.2;95%CI(1.66,6.18); P = 0.0005]. Differences between males [OR:1.99; 95%CI(1.29,3.06); P = 0.002] and females [OR:0.86; 95%CI (0.29,2.56);P = 0.79] were observed.

CONCLUSIONS

Leucocyte telomere shortening predicts the risk of AF, especially recurrent AF. The predictive value is more prominent in males than in females. Shortening in LTL can predict the progression from paroxysmal to persistent AF.

Potential clinical applications of exosomes in the diagnosis, treatment, and prognosis of cardiovascular diseases: a narrative review

Background and Objective

Cardiovascular diseases (CVDs) have been one of the most common threats to human health in recent decades. At present, despite many diagnostic, prognostic and therapeutic methods being applied in the clinic, the prevalence of CVDs continues to rise. Therefore, new discovery is needed and exosomes have received extensive attention. Exosomes are extracellular vesicles that enable communication between cells. They are widely distributed in biofluids, suggesting that they may be useful in CVD diagnosis and prognosis. Furthermore, exosomes are ideal drug transporters with relatively high transport efficiency and the capability to target different kinds of tissues. However, the present research concentrates, for the most part, on mechanistic studies with less attention to clinical applications.

Methods

More than 150 relevant scientific articles from databases like PubMed, Web of Science were screened and analysed for this narrative review. Data of clinical trials are collected from clinicaltrials.gov.

Key Content and Findings

In this review, we concentrate on different exosomes and CVDs, and we summarize the physiological and pathological roles of CVD-related exosomes. We focused on the role exosomes may have as biomarkers of CVDs, therapeutic opportunities, and possible hurdles to the clinical application of exosomes, aiming to provide a useful reference for its translational use in the CVD field.

Conclusions

Specific changes in exosome cargos (mainly miRNAs and proteins) are in accordance with the occurrence and development of CVDs including acute myocardial infarction (AMI), arrhythmia, coronary artery disease (CAD), heart failure (HF) and cardiomyopathy, therefore meaningful for diagnosis and prognosis of CVDs. For exosome related therapeutic methods, potential ways consist of direct administration of exosomes, targeting on exosome synthesis, processing and release, and working as adjuvants. All in all, exosomes are expected to serve as meaningful tools in the diagnosis, treatment and prognosis of CVDs.

MicroRNAs Regulate TASK-1 and Are Linked to Myocardial Dilatation in Atrial Fibrillation

Background

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. However, underlying molecular mechanisms are insufficiently understood. Previous studies suggested that microRNA (miRNA) dependent gene regulation plays an important role in the initiation and maintenance of AF. The 2‐pore‐domain potassium channel TASK‐1 (tandem of P domains in a weak inward rectifying K⁺ channel–related acid sensitive K⁺ channel 1) is an atrial‐specific ion channel that is upregulated in AF. Inhibition of TASK‐1 current prolongs the atrial action potential duration to similar levels as in patients with sinus rhythm. Here, we hypothesize that miRNAs might be responsible for the regulation of KCNK3 that encodes for TASK‐1.

Methods and Results

We selected miRNAs potentially regulating KCNK3 and studied their expression in atrial tissue samples obtained from patients with sinus rhythm, paroxysmal AF, or permanent/chronic AF. MiRNAs differentially expressed in AF were further investigated for their ability to regulate KCNK3 mRNA and TASK‐1 protein expression in human induced pluripotent stem cells, transfected with miRNA mimics or inhibitors. Thereby, we observed that miR‐34a increases TASK‐1 expression and current and further decreases the resting membrane potential of Xenopus laevis oocytes, heterologously expressing hTASK‐1. Finally, we investigated associations between miRNA expression in atrial tissues and clinical parameters of our patient cohort. A cluster containing AF stage, left ventricular end‐diastolic diameter, left ventricular end‐systolic diameter, left atrial diameter, atrial COL1A2 (collagen alpha‐2(I) chain), and TASK‐1 protein level was associated with increased expression of miR‐25, miR‐21, miR‐34a, miR‐23a, miR‐124, miR‐1, and miR‐29b as well as decreased expression of miR‐9 and miR‐485.

Conclusions

These results suggest an important pathophysiological involvement of miRNAs in the regulation of atrial expression of the TASK‐1 potassium channel in patients with atrial cardiomyopathy.

Upregulated miR-328-3p and its high risk in atrial fibrillation: A systematic review and meta-analysis with meta-regression

BACKGROUND

Several studies have shown miR-328-3p increased in atrial fibrillation (AF), but some researches indicated no difference or even decreased. This inconsistent result confuses researchers, and it is urgent to know the truth. This study is to assess the association between miR-328-3p levels in plasma/atrial tissue and patients with AF.

METHODS

PubMed, EMBASE, Scopus, Web of Science, and ProQuest were searched from inception to February 1, 2021. The standardized mean differences (SMD) with their 95% confidence interval (CI) were calculated to evaluate the association between miR-328-3p levels and AF.

RESULTS

Twelve studies met the inclusion criteria and were used for our meta-analysis. Overall, the levels of miR-328-3p were higher in patients with AF than in the control group (SMD = 0.69, 95% CI [0.10, 1.28], P = .022). After adjustment, the overall SMD was 0.82 (95% CI [0.22, 1.42], P = .007). Sensitivity analysis indicated that the results were stable, and the trim-fill analysis showed that the results were credible. Subgroup analyses showed that AF patients, n ≥ 30, various of comorbidity, articles published earlier, and Asia groups had higher levels of expression of miR-328-3p.

CONCLUSIONS

High levels of miR-328-3p are significantly associated with an increased risk of AF. It implies that miR-328-3p played an important role in diagnosis and may serve as a potential momentous, and useful biomarker to identify AF.

Increased expression of six-large extracellular vesicle-derived miRNAs signature for nonvalvular atrial fibrillation

Backgrounds

Non-valvular atrial fibrillation (AF) is the most common type of cardiac arrhythmia. AF is caused by electrophysiological abnormalities and alteration of atrial tissues, which leads to the generation of abnormal electrical impulses. Extracellular vesicles (EVs) are membrane-bound vesicles released by all cell types. Large EVs (lEVs) are secreted by the outward budding of the plasma membrane during cell activation or cell stress. lEVs are thought to act as vehicles for miRNAs to modulate cardiovascular function, and to be involved in the pathophysiology of cardiovascular diseases (CVDs), including AF. This study identified lEV-miRNAs that were differentially expressed between AF patients and non-AF controls.

Methods

lEVs were isolated by differential centrifugation and characterized by Nanoparticle Tracking Analysis (NTA), Transmission Electron Microscopy (TEM), flow cytometry and Western blot analysis. For the discovery phase, 12 AF patients and 12 non-AF controls were enrolled to determine lEV-miRNA profile using quantitative reverse transcription polymerase chain reaction array. The candidate miRNAs were confirmed their expression in a validation cohort using droplet digital PCR (30 AF, 30 controls). Bioinformatics analysis was used to predict their target genes and functional pathways.

Results

TEM, NTA and flow cytometry demonstrated that lEVs presented as cup shape vesicles with a size ranging from 100 to 1000 nm. AF patients had significantly higher levels of lEVs at the size of 101–200 nm than non-AF controls. Western blot analysis was used to confirm EV markers and showed the high level of cardiomyocyte expression (Caveolin-3) in lEVs from AF patients. Nineteen miRNAs were significantly higher (> twofold, p < 0.05) in AF patients compared to non-AF controls. Six highly expressed miRNAs (miR-106b-3p, miR-590-5p, miR-339-3p, miR-378-3p, miR-328-3p, and miR-532-3p) were selected to confirm their expression. Logistic regression analysis showed that increases in the levels of these 6 highly expressed miRNAs associated with AF. The possible functional roles of these lEV-miRNAs may involve in arrhythmogenesis, cell apoptosis, cell proliferation, oxygen hemostasis, and structural remodeling in AF.

Conclusion

Increased expression of six lEV-miRNAs reflects the pathophysiology of AF that may provide fundamental knowledge to develop the novel biomarkers for diagnosis or monitoring the patients with the high risk of AF.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-03213-6.

Circulatory MicroRNAs in Plasma and Atrial Fibrillation in the General Population: The Rotterdam Study

Background: MicroRNAs (miRNAs), small non-coding RNAs regulating gene expression, have been shown to play an important role in cardiovascular disease. However, limited population-based data regarding the relationship between circulatory miRNAs in plasma and atrial fibrillation (AF) exist. Moreover, it remains unclear if the relationship differs by sex. We therefore aimed to determine the (sex-specific) association between plasma circulatory miRNAs and AF at the population level. Methods: Plasma levels of miRNAs were measured using a targeted next-generation sequencing method in 1999 participants from the population-based Rotterdam Study. Logistic regression and Cox proportional hazards models were used to assess the associations of 591 well-expressed miRNAs with the prevalence and incidence of AF. Models were adjusted for cardiovascular risk factors. We further examined the link between predicted target genes of the identified miRNAs. Results: The mean age was 71.7 years (57.1% women), 98 participants (58 men and 40 women) had prevalent AF at baseline. Moreover, 196 participants (96 men and 100 women) developed AF during a median follow-up of 9.0 years. After adjusting for multiple testing, miR-4798-3p was significantly associated with the odds of prevalent AF among men (odds ratio, 95% confidence interval, 0.39, 0.24–0.66, p-value = 0.000248). No miRNAs were significantly associated with incident AF. MiR-4798-3p could potentially regulate the expression of a number of AF-related genes, including genes involved in calcium and potassium handling in myocytes, protection of cells against oxidative stress, and cardiac fibrosis. Conclusions: Plasma levels of miR-4798-3p were significantly associated with the odds of prevalent AF among men. Several target genes in relation to AF pathophysiology could potentially be regulated by miR-4798-3p that warrant further investigations in future experimental studies.

Exosomes and Exosomal Non-coding RNAs Are Novel Promises for the Mechanism-Based Diagnosis and Treatments of Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia worldwide and has a significant impact on human health and substantial costs. Currently, there is a lack of accurate biomarkers for the diagnosis and prognosis of AF. Moreover, the long-term efficacy of the catheter ablation in the AF is unsatisfactory. Therefore, it is necessary to explore new biomarkers and treatment strategies for the mechanism-based AF. Exosomes are nano-sized biovesicles released by nearly all types of cells. Since the AF would be linked to the changes of the atrial cells and their microenvironment, and the AF would strictly influence the exosomal non-coding RNAs (exo-ncRNAs) expression, which makes them as attractive diagnostic and prognostic biomarkers for the AF. Simultaneously, the exo-ncRNAs have been found to play an important role in the mechanisms of the AF and have potential therapeutic prospects. Although the role of the exo-ncRNAs in the AF is being actively investigated, the evidence is still limited. Furthermore, there is a lack of consensus regarding the most appropriate approach for exosome isolation and characterization. In this article, we reviewed the new methodologies available for exosomes biogenesis, isolation, and characterization, and then discussed the mechanism of the AF and various levels and types of exosomes relevant to the AF, with the special emphasis on the exo-ncRNAs in the diagnosis, prognosis, and treatment of the mechanism-based AF.

A narrative review of non-coding RNAs in atrial fibrillation: potential therapeutic targets and molecular mechanisms

Objective

This review summarizes the advances in the study of ncRNAs and atrial remodeling mechanisms to explore potential therapeutic targets and strategies for AF.

Background

Atrial fibrillation (AF) is one of the most common arrhythmias, and its morbidity and mortality rates are gradually increasing. Non-coding ribonucleic acid RNAs (ncRNAs) are transcribed from the genome and do not have the ability to be translated into proteins. A growing body of evidence has shown ncRNAs are extensively involved in the pathophysiological processes underlying AF. However, the precise molecular mechanisms of these associations have not been fully elucidated. Atrial remodeling plays a key role in the occurrence and development of AF, and includes electrical remodeling, structural remodeling, and autonomic nerve remodeling. Research has shown that ncRNA expression is altered in the plasma and tissues of AF patients that mediate cardiac excitation and arrhythmia, and is closely related to atrial remodeling.

Methods

Literatures about ncRNAs and atrial fibrillation were extensively reviewed to discuss and analyze.

Conclusions

The biology of ncRNAs represents a relatively new field of research and is still in an emerging stage. Recent studies have laid a foundation for understanding the molecular mechanisms of AF, future studies aimed at identifying how ncRNAs act on atrial fibrillation to provide potentially promising therapeutic targets for the treatment of atrial fibrillation.

Pharmacogenomic Effects of β-Blocker Use on Femoral Neck Bone Mineral Density

CONTEXT

Recent studies have shown that β-blocker (BB) users have a decreased risk of fracture and higher bone mineral density (BMD) compared to nonusers, likely due to the suppression of adrenergic signaling in osteoblasts, leading to increased BMD. There is also variability in the effect size of BB use on BMD in humans, which may be due to pharmacogenomic effects.

OBJECTIVE

To investigate potential single-nucleotide variations (SNVs) associated with the effect of BB use on femoral neck BMD, we performed a cross-sectional analysis using clinical data, dual-energy x-ray absorptiometry, and genetic data from the Framingham Heart Study's (FHS) Offspring Cohort. We then sought to validate our top 4 genetic findings using data from the Rotterdam Study, the BPROOF Study, the Malta Osteoporosis Fracture Study (MOFS), and the Hertfordshire Cohort Study.

METHODS

We used sex-stratified linear mixed models to determine SNVs that had a significant interaction effect with BB use on femoral neck (FN) BMD across 11 gene regions. We also evaluated the association of our top SNVs from the FHS with microRNA (miRNA) expression in blood and identified potential miRNA-mediated mechanisms by which these SNVs may affect FN BMD.

RESULTS

One variation (rs11124190 in HDAC4) was validated in females using data from the Rotterdam Study, while another (rs12414657 in ADRB1) was validated in females using data from the MOFS. We performed an exploratory meta-analysis of all 5 studies for these variations, which further validated our findings.

CONCLUSION

This analysis provides a starting point for investigating the pharmacogenomic effects of BB use on BMD measures.

The Role of Exosomes and Their Cargos in the Mechanism, Diagnosis, and Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common persistent arrhythmia, but the mechanism of AF has not been fully elucidated, and existing approaches to diagnosis and treatment face limitations. Recently, exosomes have attracted considerable interest in AF research due to their high stability, specificity and cell-targeting ability. The aim of this review is to summarize recent literature, analyze the advantages and limitations of exosomes, and to provide new ideas for their use in understanding the mechanism and improving the diagnosis and treatment of AF.

New biomarkers from multiomics approaches: improving risk prediction of atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia leading to many adverse outcomes and increased mortality. Yet the molecular mechanisms underlying AF remain largely unknown. Recent advances in high-throughput technologies make large-scale molecular profiling possible. In the past decade, multiomics studies of AF have identified a number of potential biomarkers of AF. In this review, we focus on the studies of multiomics profiles with AF risk. We summarize recent advances in the discovery of novel biomarkers for AF through multiomics studies. We also discuss limitations and future directions in risk assessment and discovery of therapeutic targets for AF.

Transcriptome analysis reveals key pathways that vary in patients with paroxysmal and persistent atrial fibrillation

The present study evaluated mRNA and long non-coding RNA (lncRNA) expression profiles and the pathways involved in paroxysmal atrial fibrillation (ParoAF) and persistent atrial fibrillation (PersAF). Nine left atrial appendage (LAA) tissues collected from the hearts of patients with AF (patients with ParoAF=3; and patients with PersAF=3) and healthy donors (n=3) were analyzed by RNA sequencing. Differentially expressed (DE) mRNAs and lncRNAs were identified by |Log₂ fold change|>2 and P<0.05. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes pathway enrichment, protein-protein interaction network and mRNA-lncRNA interaction network analyses of DE mRNA and mRNA at the upstream/downstream of DE lncRNA were conducted. A total of 285 and 275 DE mRNAs, 575 and 583 DE lncRNAs were detected in ParoAF and PersAF samples compared with controls, respectively. PI3K/Akt and transforming growth factor-β signaling pathways were significantly enriched in the ParoAF_Control and the calcium signaling pathway was significantly enriched in the PersAF_Control. Cis and trans analyses revealed some important interactions in DE mRNAs and lncRNA, including an interaction of GPC-AS2 with dopachrome tautomerase, and phosphodiesterase 4D and cAMP-specific with XLOC_110310 and XLOC_137634. Overall, the present study provides a molecular basis for future clinical studies on ParoAF and PersAF.

miRNA Mechanisms Underlying the Association of Beta Blocker Use and Bone Mineral Density

Osteoporosis is a debilitating and costly disease that causes fractures in 33% of women and 20% of men over the age of 50 years. Recent studies have shown that beta blocker (BB) users have higher bone mineral density (BMD) and decreased risk of fracture compared with non-users. The mechanism underlying this association is thought to be due to suppression of adrenergic signaling in osteoblasts, which leads to increased BMD in rodent models; however, the mechanism in humans is unknown. Also, several miRNAs are associated with adrenergic signaling and BMD in separate studies. To investigate potential miRNA mechanisms, we performed a cross-sectional analysis using clinical data, dual-energy X-ray absorptiometry (DXA) scans, and miRNA and mRNA profiling of whole blood from the Framingham Study's Offspring Cohort. We found nine miRNAs associated with BB use and increased BMD. In parallel network analyses, we discovered a subnetwork associated with BMD and BB use containing two of these nine miRNAs, miR-19a-3p and miR-186-5p. To strengthen this finding, we showed that these two miRNAs had significantly higher expression in individuals without incident fracture compared with those with fracture in an external data set. We also noted a similar trend in association between these miRNA and Z-score as calculated from heel ultrasound measures in two external cohorts (SOS-Hip and SHIP-TREND). Because miR-19a directly targets the ADRB1 mRNA transcript, we propose BB use may downregulate ADRB1 expression in osteoblasts through increased miR-19a-3p expression. We used enrichment analysis of miRNA targets to find potential indirect effects through insulin and parathyroid hormone signaling. This analysis provides a starting point for delineating the role of miRNA on the association between BB use and BMD. © 2020 American Society for Bone and Mineral Research (ASBMR).

Differential Role of Circulating microRNAs to Track Progression and Pre-Symptomatic Stage of Chronic Heart Failure: A Pilot Study

(1)Background: Chronic heart failure (CHF) contributes to the overall burden of cardiovascular disease. Early identification of at-risk individuals may facilitate the targeting of precision therapies. Plasma microRNAs are promising circulating biomarkers for their implications with cardiac pathologies. In this pilot study, we investigate the possible exploitability of circulating micro-RNAs (miRNAs) to track chronic heart failure (CHF) occurrence, and progression from NYHA class I to IV. (2)Methods: We screened 367 microRNAs using TaqMan microRNA Arrays in plasma samples from healthy controls (HC) and CHF NYHA-class I-to-IV patients (5/group). Validation was performed by singleplex assays on 10 HC and 61 CHF subjects. Differences in the expression of validated microRNAs were evaluated through analysis of covariance (ANCOVA). Associations between N-terminal pro-BNP (NT-proBNP), left ventricular end-diastolic volume (LVEDV) or peak oxygen uptake (VO2 peak) and plasma microRNA were assessed by multivariable linear regression analysis. (3)Results: Twelve microRNAs showed higher expression in CHF patients vs. HC. Seven microRNAs were associated with NT-proBNP concentration; of these, miR-423-5p was also an independent predictor of LVEDV. Moreover, miR-499-5p was a predictor of the VO2 peak. Finally, a cluster of 5 miRNAs discriminated New York Heart Association (NYHA) class-I from HC subjects. (4)Conclusions: Our data suggest that circulating miRNAs have the potential to serve as pathophysiology-based markers of HF status and progression, and as indicators of pre-symptomatic individuals.

MicroRNAs: New contributors to mechano-electric coupling and atrial fibrillation

Atrial fibrillation (AF) is a multifactorial disease, which often occurs in the presence of underlying cardiac abnormalities and is supported by electrophysiological and structural alterations, generally referred to as atrial remodeling. Abnormal substrates are commonly encountered in various conditions that predispose to AF, such as hypertension, heart failure, obesity, and sleep apnea, in which atrial stretch plays a key mechanistic role. Emerging evidence suggests a role for microRNAs (small non-coding RNAs) in the pathogenesis of AF, where they can act as post-transcriptional regulators of the genes involved in atrial remodeling. This review summarizes the experimental and clinical evidence that supports the role of microRNAs in the modulation of atrial electrical and structural remodeling with a focus on overload-induced atrial alterations, and discusses the potential contribution of microRNAs to mechano-electrical coupling and AF.

Relations between plasma microRNAs, echocardiographic markers of atrial remodeling, and atrial fibrillation: Data from the Framingham Offspring study

BACKGROUND

Circulating microRNAs may reflect or influence pathological cardiac remodeling and contribute to atrial fibrillation (AF).

OBJECTIVE

The purpose of this study was to identify candidate plasma microRNAs that are associated with echocardiographic phenotypes of atrial remodeling, and incident and prevalent AF in a community-based cohort.

METHODS

We analyzed left atrial function index (LAFI) of 1788 Framingham Offspring 8 participants. We quantified expression of 339 plasma microRNAs. We examined associations between microRNA levels with LAFI and prevalent and incident AF. We constructed pathway analysis of microRNAs' predicted gene targets to identify molecular processes involved in adverse atrial remodeling in AF.

RESULTS

The mean age of the participants was 66 ± 9 years, and 54% were women. Five percent of participants had prevalent AF at the initial examination and 9% (n = 157) developed AF over a median 8.6 years of follow-up (IQR 8.1-9.2 years). Plasma microRNAs were associated with LAFI (N = 73, p<0.0001). Six of these plasma microRNAs were significantly associated with incident AF, including 4 also associated with prevalent AF (microRNAs 106b, 26a-5p, 484, 20a-5p). These microRNAs are predicted to regulate genes involved in cardiac hypertrophy, inflammation, and myocardial fibrosis.

CONCLUSIONS

Circulating microRNAs 106b, 26a-5p, 484, 20a-5p are associated with atrial remodeling and AF.

Noncoding RNAs in Cardiovascular Disease: Current Knowledge, Tools and Technologies for Investigation, and Future Directions: A Scientific Statement From the American Heart Association

BACKGROUND

The discovery that much of the non-protein-coding genome is transcribed and plays a diverse functional role in fundamental cellular processes has led to an explosion in the development of tools and technologies to investigate the role of these noncoding RNAs in cardiovascular health. Furthermore, identifying noncoding RNAs for targeted therapeutics to treat cardiovascular disease is an emerging area of research. The purpose of this statement is to review existing literature, offer guidance on tools and technologies currently available to study noncoding RNAs, and identify areas of unmet need.

METHODS

The writing group used systematic literature reviews (including MEDLINE, Web of Science through 2018), expert opinion/statements, analyses of databases and computational tools/algorithms, and review of current clinical trials to provide a broad consensus on the current state of the art in noncoding RNA in cardiovascular disease.

RESULTS

Significant progress has been made since the initial studies focusing on the role of miRNAs (microRNAs) in cardiovascular development and disease. Notably, recent progress on understanding the role of novel types of noncoding small RNAs such as snoRNAs (small nucleolar RNAs), tRNA (transfer RNA) fragments, and Y-RNAs in cellular processes has revealed a noncanonical function for many of these molecules. Similarly, the identification of long noncoding RNAs that appear to play an important role in cardiovascular disease processes, coupled with the development of tools to characterize their interacting partners, has led to significant mechanistic insight. Finally, recent work has characterized the unique role of extracellular RNAs in mediating intercellular communication and their potential role as biomarkers.

CONCLUSIONS

The rapid expansion of tools and pipelines for isolating, measuring, and annotating these entities suggests that caution in interpreting results is warranted until these methodologies are rigorously validated. Most investigators have focused on investigating the functional role of single RNA entities, but studies suggest complex interaction between different RNA molecules. The use of network approaches and advanced computational tools to understand the interaction of different noncoding RNA species to mediate a particular phenotype may be required to fully comprehend the function of noncoding RNAs in mediating disease phenotypes.

Long Non-Coding RNAs in Atrial Fibrillation: Pluripotent Stem Cell-Derived Cardiomyocytes as a Model System

Atrial fibrillation (AF) is a type of sustained arrhythmia in humans often characterized by devastating alterations to the cardiac conduction system as well as the structure of the atria. AF can lead to decreased cardiac function, heart failure, and other complications. Long non-coding RNAs (lncRNAs) have been shown to play important roles in the cardiovascular system, including AF; however, a large group of lncRNAs is not conserved between mouse and human. Furthermore, AF has complex networks showing variations in mechanisms in different species, making it challenging to utilize conventional animal models to investigate the functional roles and potential therapeutic benefits of lncRNAs for AF. Fortunately, pluripotent stem cell (PSC)-derived cardiomyocytes (CMs) offer a reliable platform to study lncRNA functions in AF because of certain electrophysiological and molecular similarities with native human CMs. In this review, we first summarize the broad aspects of lncRNAs in various heart disease settings, then focus on their potential roles in AF development and pathophysiology. We also discuss current uses of PSCs in AF research and describe how these studies could be developed into novel therapeutics for AF and other cardiovascular diseases.

Identification of microRNA biomarkers in serum of patients at different stages of atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is a type of cardiac arrhythmia which is caused by irregular electrical activities in the atria.

OBJECTIVE

To identify serum microRNA (miRNA) biomarkers at three durations (duration since diagnosis of AF) of AF.

METHODS

This study included 14 patients with AF and 8 healthy subjects. The blood sample was collected from each patient at baseline (time of diagnosis) and 12-month and 24-month follow-up periods. The serum was used for miRNA sequencing. The differentially expressed miRNAs (DEMs) between the 3 AF and control groups were independently compared. The predicted target genes of DEMs were subjected to functional enrichment and protein-protein interaction network analyses. Additionally, the miRNA-target gene networks were constructed for the 3 AF groups and miRNA time series analysis was performed. The expression of several key miRNAs was verified by real-time quantitative polymerase chain reaction (qRT-PCR).

RESULTS

In total, 28, 22, and 24 DEMs were identified in the baseline, 12-month, and 24-month groups, respectively. miR-483-5p was the common DEM in the 3 AF groups. In the baseline and 12-month groups, the miR-200b-3p and miR-125b-5p target genes were significantly enriched in the Wnt signaling and several cancer-related pathways, respectively. In the 12-month group, the miR-34a-5p target genes were enriched in the cancer-related pathways. In the miRNA-target gene network, miR-34a-5p regulated the highest number of target genes. The time series analysis revealed that 7 miRNAs, which were downregulated in the control group, were upregulated in the AF groups. The qRT-PCR analysis revealed that the 24-month group exhibited a significant upregulation of miR-483-5p (p < 0.05), whereas the baseline group exhibited significant a downregulation of miR-125b-5p (p < 0.05).

CONCLUSION

In patients with AF, miR-125b-5p and miR-483-5p can be potential biomarkers of the baseline and 24-month periods, respectively.

RNAs and Gene Expression Predicting Postoperative Atrial Fibrillation in Cardiac Surgery Patients Undergoing Coronary Artery Bypass Grafting

Postoperative atrial fibrillation (POAF) is linked with increased morbidity, mortality rate and financial liability. About 20–50% of patients experience POAF after coronary artery bypass graft (CABG) surgery. Numerous review articles and meta-analyses have investigated links between patient clinical risk factors, demographic conditions, and pre-, peri- and post-operative biomarkers to forecast POAF incidence in CABG patients. This narrative review, for the first time, summarize the role of micro-RNAs, circular-RNAs and other gene expressions that have shown experimental evidence to accurately predict the POAF incidence in cardiac surgery patients after CABG. We envisage that identifying specific genomic markers for predicting POAF might be a significant step for the prevention and effective management of this type of post-operative complication and may provide critical perspective into arrhythmogenic substrate responsible for POAF.

Circulating MicroRNA Expression Profiles in Patients with Stable and Unstable Angina

OBJECTIVES

High incidence and case fatality of unstable angina (UA) is, to a large extent, a consequence of the lack of highly sensitive and specific non-invasive markers. Circulating microRNAs (miRNAs) have been widely recommended as potential biomarkers for numerous diseases. In the present study, we characterized distinctive miRNA expression profiles in patients with stable angina (SA), UA, and normal coronary arteries (NCA), and identified promising candidates for UA diagnosis.

METHODS

Serum was collected from patients with SA, UA, and NCA who visited the Department of Cardiovascular Diseases of the Meizhou People's Hospital. Small RNA sequencing was carried out on an Illumina HiSeq 2500 platform. miRNA expression in different groups of patients was profiled and then confirmed based on that in an independent set of patients. Functions of differentially expressed miRNAs were predicted using gene ontology classification and Kyoto Encyclopedia of Genes and Genomes pathway analysis.

RESULTS

Our results indicated that circulating miRNA expression profiles differed between SA, UA, and NCA patients. A total of 36 and 161 miRNAs were dysregulated in SA and UA patients, respectively. miRNA expression was validated by reverse transcription quantitative polymerase chain reaction.

CONCLUSION

The results suggest that circulating miRNAs are potential biomarkers of UA.

MicroRNA expression signatures of atrial fibrillation: The critical systematic review and bioinformatics analysis

Association between microRNA (miRNA) expression signatures and atrial fibrillation has been evaluated with inconsistent findings in different studies. This study aims to identify miRNAs that actually play vital role in pathophysiological process of atrial fibrillation and explore miRNA-targeted genes and the involved pathways. Relevant studies were retrieved from the electronic databases of Embase, Medline, and Cochrane Library to determine the miRNA expression profiles between atrial fibrillation subjects and non-atrial fibrillation controls. Robustness of results was assessed using sensitivity analysis. Subgroup analyses were performed based on species, miRNA detection method, sample source, and ethnicity. Quality assessment of studies was independently conducted according to QUADAS-2. Bioinformatics analysis was applied to explore the potential genes and pathways associated with atrial fibrillation, which were targeted by differentially expressed miRNAs. Form of pooled results was shown as log10 odds ratios (logORs) with 95% confidence intervals (CI), and random-effects model was used. In total, 40 articles involving 283 differentially expressed miRNAs were reported. And 51 significantly dysregulated miRNAs were identified in consistent direction, with 22 upregulated and 29 downregulated. Among above-mentioned miRNAs, miR-223-3p (logOR 6.473; P < 0.001) was the most upregulated, while miR-1-5p (logOR 7.290; P < 0.001) was the most downregulated. Subgroup analysis confirmed 53 significantly dysregulated miRNAs (21 upregulated and 32 downregulated) in cardiac tissue, with miRNA-1-5p and miRNA-223-3p being the most upregulated and downregulated miRNAs, respectively. Additionally, miR-328 and miR-1-5p were highly blood-specific, and miR-133 was animal-specific. In the detection method sub-groups, miRNA-29b and miRNA-223-3p were differentially expressed consistently. Four miRNAs, including miRNA-223-3p, miRNA-21, miRNA-328, and miRNA-1-5p, were consistently dysregulated in both Asian and non-Asian. Results of sensitivity analysis showed that 47 out of 51 (92.16%) miRNAs were dysregulated consistently. Totally, 51 consistently dysregulated miRNAs associated with atrial fibrillation were confirmed in this study. Five important miRNAs, including miR-29b, miR-328, miR-1-5p, miR-21, and miR-223-3p may act as potential biomarkers for atrial fibrillation.

Impact statement

Atrial fibrillation (AF) is considered as the most common arrhythmia, and it subsequently causes serious complications including thrombosis and heart failure that increase the social burden. The definite mechanisms underlying AF pathogenesis remain complicated and unclear. Many studies attempted to discover the transcriptomic changes using microarray technologies, and the present studies for this hot topic have assessed individual miRNAs profiles for AF. However, results of different articles are controversial and not each reported miRNA is actually associated with the pathogenesis of AF. The present systematic review and meta-analysis identified that 51 consistently dysregulated miRNAs were associated with AF. Of these miRNAs, five miRNAs (miRNA-1-5p, miRNA-328, miRNA-29b, miRNA-21, and miRNA-223-3p) may act as novel biomarkers for AF. The findings could offer a better description of the biological characteristics of miRNAs, meanwhile might serve as new target for the intervention and monitoring AF in future studies.

Micro-RNAs Are Related to Epicardial Adipose Tissue in Participants With Atrial Fibrillation: Data From the MiRhythm Study

Introduction: Epicardial adipose tissue (EAT) has been linked to incidence and recurrence of atrial fibrillation (AF), but the underlying mechanisms that mediate this association remain unclear. Circulating microRNAs (miRNAs) contribute to the regulation of gene expression in cardiovascular diseases, including AF. Thus, we sought to test the hypothesis that circulating miRNAs relate to burden of EAT.

Methods: We examined the plasma miRNA profiles of 91 participants from the miRhythm study, an ongoing study examining associations between miRNA and AF. We quantified plasma expression of 86 unique miRNAs commonly expressed in cardiomyocytes using quantitative reverse transcriptase polymerase chain reaction (qPCR). From computed tomography, we used validated methods to quantify the EAT area surrounding the left atrium (LA) and indexed it to body surface area (BSA) to calculate indexed LA EAT (iLAEAT). Participants were divided into tertiles of iLAEAT to identify associations with unique miRNAs. We performed logistic regression analyses adjusting for factors associated with AF to examine relations between iLAEAT and miRNA. We performed further bioinformatics analysis of miRNA predicted target genes to identify potential molecular pathways are regulated by the miRNAs.

Results: The mean age of the participants was 59 ± 9, 35% were women, and 97% were Caucasian. Participants in the highest tertile of iLAEAT were more likely to have hypertension, heart failure, and thick posterior walls. In regression analyses, we found that miRNAs 155-5p (p < 0.001) and 302a-3p (p < 0.001) were significantly associated with iLAEAT in patients with AF. The predicted targets of the miRNAs identified were implicated in the regulation of cardiac hypertrophy, adipogenesis, interleukin-8 (IL-8), and nerve growth factor (NGF) signaling.

Conclusion: miRNA as well as EAT have previously been linked to AF. Our finding that iLAEAT and miRNAs 155-5p and 302a-3p are associated suggest a possible direct link to between these entities in the development and maintenance of AF. Further research is needed to study causal relationships between these biomarkers.

Whole blood microRNA expression associated with stroke: Results from the Framingham Heart Study

Emerging evidence suggests microRNAs (miRNAs) may play an important role in explaining variation in stroke risk and recovery in humans, yet there are still few longitudinal studies examining the association between whole blood miRNAs and stroke. Accounting for multiple testing and adjusting for potentially confounding technical and clinical variables, here we show that whole blood miR-574-3p expression was significantly lower in participants with chronic stroke compared to non-cases. To explore the functional relevance of our findings, we analyzed miRNA-mRNA whole blood co-expression, pathway enrichment, and brain tissue gene expression. Results suggest miR-574-3p is involved in neurometabolic and chronic neuronal injury response pathways, including brain gene expression of DBNDD2 and ELOVL1. These results suggest miR-574-3p plays a role in regulating chronic brain and systemic cellular response to stroke and thus may implicate miR-574-3p as a partial mediator of long-term stroke outcomes.

Abnormal expression of miR-331 leads to impaired heart function

MicroRNAs (miRNAs) play important roles in maintaining normal heart function. Abnormal expression of miR-331 has been observed in the hearts of patients with atrial fibrillation and Marfan syndrome. However, whether miR-331 regulates cardiac function under physiological and pathological conditions still remains unknown. In the present study, we investigated the function and underlying mechanisms of miR-331 in a pressure overload-induced heart failure model and miR-331 transgenic rat model. First, we found that the expression of miR-331-3p exhibited a 1.7-fold increase in hypertrophy compared with that in the sham group (P < 0.01), yet the expression of miR-331-5p remained unchanged. Furthermore, overexpression of miR-331 in cardiomyocytes and defective excitation-contraction (E-C) coupling efficiency were observed. Luciferase assays showed that miR-331-3p suppressed JPH2 expression by binding to the coding region of JPH2 mRNA. Finally, in the miR-331 transgenic rat model, JPH2 expression was suppressed at both the mRNA and protein levels in vivo, which resulted in impairment of both the E-C coupling efficiency of cardiomyocytes and systolic function of the heart. This finding mechanistically linked miR-331 to JPH2 downregulation and suggested an important role for the abnormal expression of miR-331 leading to the dysfunction of E-C coupling in heart failure.

Identification of microRNA biomarkers in atrial fibrillation: A protocol for systematic review and bioinformatics analysis

BACKGROUND

Atrial fibrillation (AF) is recognized as the most prevalent arrhythmia, and its subsequently serious complications of heart failure and thromboembolism always raise the social attention. To date, the molecular pathogenesis of AF has largely remained unclear. Publications of contemporary studies have evaluated individual miRNAs expression signatures for AF, and findings of different studies are inconsistent and not all miRNAs reported are actually important in the pathogenesis of AF.

METHODS

Medline, Embase, and Cochrane Library databases will be comprehensively searched (up to April 30, 2019) for studies identifying miRNA expression profiling in subjects with and without AF. Log10 odds ratios (logORs) and associated 95% confidence interval (95%CI) will be calculated using random-effects models. Subgroup analysis will be performed according to miRNA detecting methods, species, sample types, and ethnicities. Sensitivity analysis will be conducted to detect the robustness of the findings. The methodological quality of studies will be independently assessed using criteria adopted from the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2). Furthermore, bioinformatics analysis will be performed to identify the potential target genes in AF and the corresponding pathways of dysregulated miRNAs. Two reviewers will independently screen potential studies and extract data in a structured eligibility items, with any disagreements being resolved by consensus.

RESULTS

The present systematic review will identify potential biomarkers by pooling all differentially expressed miRNAs in AF studies, as well as to predict miRNA-target interactions and to identify the potential biometric functions using bioinformatics analysis.

CONCLUSIONS

This systematic review and bioinformatics analysis will identify several miRNAs as potential biomarkers for AF, and explore the biological pathways regulated by the eligible miRNAs.

PROSPERO REGISTRATION NUMBER

CRD42019127594.

Circulating extracellular RNAs, myocardial remodeling, and heart failure in patients with acute coronary syndrome

BACKGROUND

Given high on-treatment mortality in heart failure (HF), identifying molecular pathways that underlie adverse cardiac remodeling may offer novel biomarkers and therapeutic avenues. Circulating extracellular RNAs (ex-RNAs) regulate important biological processes and are emerging as biomarkers of disease, but less is known about their role in the acute setting, particularly in the setting of HF.

METHODS

We examined the ex-RNA profiles of 296 acute coronary syndrome (ACS) survivors enrolled in the Transitions, Risks, and Actions in Coronary Events Center for Outcomes Research and Education Cohort. We measured 374 ex-RNAs selected a priori, based on previous findings from a large population study. We employed a two-step, mechanism-driven approach to identify ex-RNAs associated with echocardiographic phenotypes (left ventricular [LV] ejection fraction, LV mass, LV end-diastolic volume, left atrial [LA] dimension, and LA volume index) then tested relations of these ex-RNAs with prevalent HF (N=31, 10.5%). We performed further bioinformatics analysis of microRNA (miRNAs) predicted targets' genes ontology categories and molecular pathways.

RESULTS

We identified 44 ex-RNAs associated with at least one echocardiographic phenotype associated with HF. Of these 44 exRNAs, miR-29-3p, miR-584-5p, and miR-1247-5p were also associated with prevalent HF. The three microRNAs were implicated in the regulation p53 and transforming growth factor-β signaling pathways and predicted to be involved in cardiac fibrosis and cell death; miRNA predicted targets were enriched in gene ontology categories including several involving the extracellular matrix and cellular differentiation.

CONCLUSIONS

Among ACS survivors, we observed that miR-29-3p, miR-584-5p, and miR-1247-5p were associated with both echocardiographic markers of cardiac remodeling and prevalent HF.

RELEVANCE FOR PATIENTS

miR-29c-3p, miR-584-5p, and miR-1247-5p were associated with echocardiographic phenotypes and prevalent HF and are potential biomarkers for adverse cardiac remodeling in HF.

Biomarkers in Atrial Fibrillation and Heart Failure

Atrial fibrillation (AF) is the most common sustained arrhythmia encountered in clinical practice and an important contributor to cardiovascular morbidity and mortality. Although the exact mechanisms behind AF are not completely elucidated, the underlying pathophysiological changes have been well described. Predisposal factors for AF include the older age, the increased left atrial size, the decreased left atrial function, the presence of heart failure and left ventricular systolic dysfunction and the presence of coronary heart disease or pulmonary or mitral valve disease. In addition to these factors, emerging evidence demonstrate that myocardial strain, fibrosis and inflammation, are associated with AF as well as the pathogenesis of the arrhythmia. The natruretic peptide system including Atrial Natriuretic Peptide (ANP), Brain Natriuretic Peptide (BNP) and C-type Natriuretic Peptide (CNP) is indicative of the level of myocardial strain which may predispose to AF. As a result, the aforementioned peptides are increased in AF patients. The levels of myocardial fibrosis biomarkers, such as ST2 and Galectin-3, are elevated suggesting atrial structural abnormalities, while the increased levels of CRP and Interleukin-6 supplement the inflammatory profile of AF patients. Emerging data for the aforementioned biomarkers are discussed in the present review.

Plasma miR-22-5p, miR-132-5p, and miR-150-3p Are Associated with Acute Myocardial Infarction

Circulating microRNAs (miRNAs) are potential biomarkers for cardiovascular diseases. Our study aimed to determine whether miR-22-5p, miR-132-5p, and miR-150-3p represent novel biomarkers for acute myocardial infarction (AMI). Plasma samples were isolated from 35 AMI patients and 55 matched controls. Total RNA was extracted, and quantitative real-time PCR and ELISA were performed to investigate the expressions of miRNAs and cardiac troponin I (cTnI), respectively. We found that plasma levels of miR-22-5p and miR-150-3p were significantly higher during the early stage of AMI and their expression levels peaked earlier than cTnI. Conversely, circulating miR-132-5p was sustained at a low level during the early phase of AMI. All three circulating miRNAs were correlated with plasma cTnI levels. A receiver operating characteristic (ROC) analysis suggested that each single miRNA had considerable diagnostic efficacy for AMI. Moreover, combining the three miRNAs improved their diagnostic efficacy. Furthermore, neither heparin nor medications for coronary heart disease (CHD) affected plasma levels of miR-22-5p and miR-132-5p, but circulating miR-150-3p was downregulated by medications for CHD. We concluded that plasma miR-22-5p, miR-132-5p, and miR-150-3p may serve as candidate diagnostic biomarkers for early diagnosis of AMI. Moreover, a panel consisting of these three miRNAs may achieve a higher diagnostic value.

Opportunities for microRNAs in the Crowded Field of Cardiovascular Biomarkers

Cardiovascular diseases exist across all developed countries. Biomarkers that can predict or diagnose diseases early in their pathogeneses can reduce their morbidity and mortality in afflicted individuals. microRNAs are small regulatory RNAs that modulate translation and have been identified as potential fluid-based biomarkers across numerous maladies. We describe the current state of cardiovascular disease biomarkers across a range of diseases, including myocardial infarction, acute coronary syndrome, myocarditis, hypertension, heart failure, heart transplantation, aortic stenosis, diabetic cardiomyopathy, atrial fibrillation, and sepsis. We present the current understanding of microRNAs as possible biomarkers in these categories and where their best opportunities exist to enter clinical practice.

Exploring microRNAs, Target mRNAs and their Functions in Leguminous Plant Arachis hypogaea

BACKGROUND

MicroRNAs (miRNAs) are a class of small non-coding, endogenous RNAs that regulate gene expression at post-transcriptional level. In plants, miRNAs are usually of 18-24 nucleotide in length and play humongous role by aiding in development, growth, defense, biotic and abiotic stress responses, etc. Objective: Arachis hypogaea is an economically important oil seed crop and human dietary source cultivated mostly in tropical and subtropical regions. In the present study, an initiative was taken to uncover miRNAs, their targets and functions in this important plant species.

METHOD

Comparative genomics strategy coupled with bioinformatics approaches was deployed for the identification of miRNAs, their corresponding targets and functions by exploiting biological databases and tools.

RESULTS

The study was able to identify 34 conserved miRNA candidates, belonging to 17 miRNA families, contributed by 23 and 3 precursor miRNAs from A. hypogaea Expressed Sequence Tags (EST) and Genome Survey Sequences (GSS), respectively. As well, 495 EST and 917 unigene sequences were predicted as targets for the identified miRNAs. Herein, psRNAtarget server and TargetFinder tool were used to predict unigene targets, whereas comparative genomics strategy was used for identifying EST targets. Functional annotation of the identified targets revealed that the identified miRNAs regulate mRNAs that participate in key biological and metabolic processes. Pathway enrichment analysis using KEGG database also revealed that they regulate important metabolic pathways including antibiotic biosynthesis, biosynthesis of unsaturated fatty acids, amino acids metabolism and flavonoid biosynthesis.

CONCLUSION

The outcome of the study would aid experimental biologists to focus on these miRNAs to facilitate improved crop development and yield.

Modulation of genomic and epigenetic end-points by celecoxib

Celecoxib, a nonsteroidal anti-inflammatory drug that selectively targets cyclooxygenase-2, is a promising cancer chemopreventive agent. However, safety concerns have been raised in clinical trials evaluating its ability to prevent colorectal adenomas. The rationale for the herein reported studies was to analyze genomic and epigenetic end-points aimed at investigating both the chemopreventive properties of celecoxib towards cigarette smoke-associated molecular alterations and its possible adverse effects. We carried out three consecutive studies in mice treated with either smoke and/or celecoxib. Study 1 investigated early DNA alterations (DNA adducts, oxidative DNA damage, and systemic genotoxic damage) and epigenetic alterations (expression of 1,135 microRNAs) in lung and blood of Swiss H mice; Study 2 evaluated the formation of DNA adducts in lung, liver, and heart; and Study 3 evaluated the expression of microRNAs in 10 organs and 3 body fluids of ICR (CD-1) mice. Surprisingly, the oral administration of celecoxib to smoke-free mice resulted in the formation of DNA adducts in both lung and heart and in dysregulation of microRNAs in mouse organs and body fluids. On the other hand, celecoxib attenuated smoke-related DNA damage and dysregulation of microRNA expression. In conclusion, celecoxib showed pleiotropic properties and multiple mechanisms by counteracting the molecular damage produced by smoke in a variety of organs and body fluids. However, administration of celecoxib to non-smoking mice resulted in evident molecular alterations, also including DNA and RNA alterations in the heart, which may bear relevance in the pathogenesis of the cardiovascular adverse effects of this drug.

Antiremodeling Effect of Xanthine Oxidase Inhibition in a Canine Model of Atrial Fibrillation

In a canine rapid atrial stimulation model of atrial fibrillation (AF), we have demonstrated an increased production of reactive oxygen species (ROS) along with electrical and structural remodeling. In the present study, we hypothesized that antioxidants can suppress atrial remodeling canines with AF. We therefore evaluated the effect of febuxostat, a xanthine oxidase (XO) inhibitor and a pure antioxidant, on atrial remodeling.AF was produced by performing a 3-week rapid atrial pacing (400 bpm) in 13 dogs divided into three groups: pacing + febuxostat group (n = 5; atrial pacing with 50 mg/day of febuxostat (administration); pacing control group (n = 5; atrial pacing without any drug administration); and non-pacing group (n = 3). Electrophysiological studies were conducted in the first 2 groups every week. Atrial tissue fibrosis was evaluated by Azan and immunofluorescent staining of fibronectin. Oxidative stress was evaluated by DHE and FCF-DA staining.Shortening of the refractory period and increase in AF inducibility appeared gradually in the pacing control group, but such changes were suppressed in the pacing + febuxostat group (P = 0.05). The pacing control group showed increase in fibrosis, which was suppressed in the febuxostat group. In DHE and DCF-DA staining, the pacing control group showed an increase in oxidative stress, which was suppressed in the pacing + febuxostat group. The pacing control group exhibited fibronectin expression, which was suppressed in the pacing + febuxostat group.The antioxidant effect of febuxostat may achieve an inhibition of new-onset AF in canines.

MicroRNAs in Atrial Fibrillation: from Expression Signatures to Functional Implications

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with pronounced morbidity and mortality. Its prevalence, expected to further increase for the forthcoming years, and associated frequent hospitalizations turn AF into a major health problem. Structural and electrical atrial remodelling underlie the substrate for AF, but the exact mechanisms driving this remodelling remain incompletely understood. Recent studies have shown that microRNAs (miRNA), short non-coding RNAs that regulate gene expression, may be involved in the pathophysiology of AF. MiRNAs have been implicated in AF-induced ion channel remodelling and fibrosis. MiRNAs could therefore provide insight into AF pathophysiology or become novel targets for therapy with miRNA mimics or anti-miRNAs. Moreover, circulating miRNAs have been suggested as a new class of diagnostic and prognostic biomarkers of AF. However, the origin and function of miRNAs in tissue and plasma frequently remain unknown and studies investigating the role of miRNAs in AF vary in design and focus and even present contradicting results. Here, we provide a systematic review of the available clinical and functional studies investigating the tissue and plasma miRNAs in AF and will thereafter discuss the potential of miRNAs as biomarkers or novel therapeutic targets in AF.

Increased right atrial appendage apoptosis is associated with differential regulation of candidate MicroRNAs 1 and 133A in patients who developed atrial fibrillation after cardiac surgery

Atrial fibrillation (AF) following on-pump coronary artery bypass grafting (CABG) is a common condition associated with increased morbidity and mortality. We investigated the possibility that miRs may play a contributory role in postoperative AF and associated apoptosis. A total of 42 patients (31 males and 11 females, mean age 65.0 ± 1.3 years) with sinus rhythm and without a history of AF were prospectively enrolled. We examined the levels of the muscle-specific miRs 1 and 133A and markers of apoptosis including TUNEL staining, caspase-3 activation, Bcl2 and Bax mRNAs in right atrial appendage (RAA) biopsies and blood plasma taken before aortic cross-clamping and after reperfusion. After reperfusion, indices of apoptosis increased the RAA. There was no change in tissue or plasma miR -1 and -133A levels compared to pre CABG. However, in patients who postoperatively developed AF (n = 14, 7 males and 7 females), compared to patients that remained in SR (n = 28, 24 males and 4 females) post CABG, tissue miR-1 increased whereas miR-133A decreased and negatively correlated with RAA apoptosis. Mechanistically, overexpression of miR-133A inhibited hypoxia-induced rat neonatal cardiomyocyte apoptosis and phosphorylated pro-survival Akt, responses abolished by a miR-133A antisense inhibitor oligonucleotide or by pre-treatment with an Akt inhibitor. In postoperative AF, differential regulation of pro- and anti-apoptotic miRs-1 and -133A respectively in the RAA, may contribute to postoperative apoptosis. These results provide new insights into molecular mechanisms of postoperative AF with potential therapeutic implications.

Circulating miRNAs in acute new-onset atrial fibrillation and their target mRNA network

BACKGROUND

MicroRNAs (miRNAs) are involved in the pathogenesis of atrial fibrillation (AF), acting on development and progression. Our pilot study investigated the expression of six miRNAs and their miRNA-mRNA interactions in patients with acute new-onset AF, well-controlled AF, and normal sinus rhythm (controls).

METHODS AND RESULTS

Plasma of acute new-onset AF patients (n = 5) was collected in the emergency room when patients presented with irregular and fast-atrial fibrillation rhythm. Samples from well-controlled AF (n = 16) and control (n =  15) patients were collected during medical appointments following an ECG. Expression of miR-21, miR-133a, miR-133b, miR-150, miR-328, and miR-499 was analyzed by real-time PCR. Ingenuity Pathway Analysis and the TargetScan database identified the top 30 mRNA targets of these miRNA, seeking the miRNA-mRNA interactions in cardiovascular process. Increased expression of miR-133b (1.4-fold), miR-328 (2.0-fold), and miR-499 (2.3-fold) was observed in patients with acute new-onset AF, compared with well-controlled AF and control patients. Decreased expression of miR-21 was seen in patients with well-controlled AF compared to those with acute new-onset AF and controls (0.6-fold). The miRNA-mRNA interaction demonstrated that SMAD7 and FASLG genes were the targets of miR-21, miR-133b, and miR-499 and were directly related to AF, being involved in apoptosis and fibrosis.

CONCLUSION

The miRNAs had different expression profiles dependent on the AF condition, with higher expression in the acute new-onset AF than well-controlled AF. Clinically, this may contribute to an effective assessment for patients, leading to early detection of AF and monitoring to reduce the risk of other serious cardiovascular events.

Atrial overexpression of microRNA-27b attenuates angiotensin II-induced atrial fibrosis and fibrillation by targeting ALK5

Atrial fibrosis influences atrial fibrillation (AF) development by transforming growth factor beta 1 (TGF-β1)/Smad pathway. Although microRNAs are implicated in the pathogenesis of various diseases, information regarding the functional role of microRNAs in atrial dysfunction is limited. In the present study, we found that microRNA-27b (miR-27b) was the dominant member of miR-27 family expressed in left atrium. Moreover, the expression of miR-27b was significantly reduced after angiotensin II (AngII) infusion. Masson's trichrome staining revealed that delivery of miR-27b adeno-associated virus to left atrium led to a decrease in atrial fibrosis induced by AngII. The increased expression of collagen I, collagen III, plasminogen activator inhibitor type 1 and alpha smooth muscle actin was also inhibited after miR-27b upregulation. In isolated perfused hearts, miR-27b restoration markedly attenuated AngII-induced increase in interatrial conduction time, AF incidence and AF duration. Furthermore, our data evidence that miR-27b is a novel miRNA that targets ALK5, a receptor of TGF-β1, through binding to the 3' untranslated region of ALK5 mRNA. Ectopic miR-27b suppressed luciferase activity and expression of ALK5, whereas inhibition of miR-27b increased ALK5 luciferase activity and expression. Additionally, miR-27b inhibited AngII-induced Smad-2/3 phosphorylation without altering Smad-1 activity. Taken together, our study demonstrates that miR-27b ameliorates atrial fibrosis and AF through inactivation of Smad-2/3 pathway by targeting ALK5, suggesting miR-27b may play an anti-fibrotic role in left atrium and function as a novel therapeutic target for the treatment of cardiac dysfunction.

The Role of Platelet Microparticle Associated microRNAs in Cellular Crosstalk

Platelet is an anucleate cell containing abundant messenger RNAs and microRNAs (miRNAs), and their functional roles in hemostasis and inflammation remain elusive. Accumulating evidence has suggested that platelets can actively transfer RNAs to hepatocytes, vascular cells, macrophages, and tumor cells. The incorporated mRNAs are translated into proteins, and miRNAs were found to regulate the gene expression, resulting in the functional change of the recipient cells. This novel intercellular communication opens up a new avenue for the pathophysiological role of platelet in platelet-associated vascular diseases. Therefore, understanding the underlying mechanism and identification of the platelet miRNAs involved in this biological process would provide novel diagnostic and therapeutic targets for cardiovascular diseases.

miR-941 as a promising biomarker for acute coronary syndrome

BACKGROUND

Circulating miRNAs can function as biomarkers for diagnosis, treatment, and prevention of diseases. However, it is unclear whether miRNAs can be used as biomarkers for acute coronary syndrome (ACS). To this end, we applied gene chip technology to analyze miRNA expression in patients with stable angina (SA), non-ST elevation ACS (NSTE-ACS), and ST-segment elevation myocardial infarction (STEMI).

METHODS

We enrolled patients with chest pain who underwent diagnostic coronary angiography, including five patients each with SA, NSTE-ACS, or STEMI, and five controls without coronary artery disease (CAD) but with three or more risk factors. After microarray analysis, differential miRNA expression was confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

Compared with those in patients with STEMI, differentially expressed microRNAs in controls and patients with SA or NSTE-ACS were involved in inflammation, protein phosphorylation, and cell adhesion. Pathway analysis showed that differentially expressed miRNAs were related to the mitogen-activated protein kinase signaling, calcium ion pathways, and cell adhesion pathways. Compared with their expression levels in patients with STEMI, miR-941, miR-363-3p, and miR-182-5p were significantly up-regulated (fold-change: 2.0 or more, P < 0.05) in controls and patients with SA or NSTE-ACS. Further, qRT-PCR showed that plasma miR-941 level was elevated in patients with NSTE-ACS or STEMI as compared with that in patients without CAD (fold-change: 1.65 and 2.28, respectively; P < 0.05). Additionally, miR-941 expression was significantly elevated in the STEMI group compared with that in the SA (P < 0.01) and NSTE-ACS groups (P < 0.05). Similarly, miR-941 expression was higher in patients with ACS (NSTE-ACS or STEMI) than in patients without ACS (without CAD or with SA; P < 0.01). There were no significant differences in miR-182-5p and miR-363-3p expression. The areas under the receiver operating characteristic curves were 0.896, 0.808, and 0.781 for patients in the control, SA, and NSTE-ACS groups, respectively, compared with that for patients with STEMI; that for the ACS group compared with the non-ACS group was 0.734.

CONCLUSION

miR-941 expression was relatively higher in patients with ACS and STEMI. Thus, miR-941 may be a potential biomarker of ACS or STEMI.

Potential Biological Markers of Atrial Fibrillation: A Chance to Prevent Cryptogenic Stroke

Stroke affects millions of people all over the world, causing death and disability. The most frequent type of this disease is ischemic stroke, which can be caused by different factors. In approximately 25 percent of cases, no obvious cause can be found. Recent observations have shown that paroxysmal atrial fibrillation could be responsible for a significant number of cryptogenic stroke events. Short- or long-lasting ECG monitoring could help with the diagnosis of transient arrhythmias. Unfortunately, these techniques either are expensive or require good patient compliance. An alternative option is the identification of biological markers that are specific for atrial fibrillation and can be used to predict arrhythmia. In this review, we give a summary of the recent advances in the research of arrhythmia markers. Based on their structure and function, we differentiated four groups of biomarkers: markers of inflammation, markers of fibrosis, markers with hormonal activity, and other markers. In spite of intensive researches, the optimal biological marker is still not available, but there are some promising markers, like NT-proBNP/BNP.

Differential expression of microRNAs following cardiopulmonary bypass in children with congenital heart diseases

Background

Children with congenital heart defects (CHDs) are at high risk for myocardial failure after operative procedures with cardiopulmonary bypass (CPB). Recent studies suggest that microRNAs (miRNA) are involved in the development of CHDs and myocardial failure. Therefore, the aim of this study was to determine alterations in the miRNA profile in heart tissue after cardiac surgery using CPB.

Methods

In total, 14 tissue samples from right atrium were collected from patients before and after connection of the CPB. SurePrint™ 8 × 60K Human v21 miRNA array and quantitative reverse transcription-polymerase chain reaction (RT-qPCR) were employed to determine the miRNA expression profile from three patients before and after connection of the CPB. Enrichment analyses of altered miRNA expression were predicted using bioinformatic tools.

Results

According to miRNA array, a total of 90 miRNAs were significantly altered including 29 miRNAs with increased and 61 miRNAs with decreased expression after de-connection of CPB (n = 3) compared to before CPB (n = 3). Seven miRNAs had been validated using RT-qPCR in an independent cohort of 11 patients. Enrichment analyses applying the KEGG database displayed the highest correlation for signaling pathways, cellular community, cardiovascular disease and circulatory system.

Conclusion

Our result identified the overall changes of the miRNome in right atrium tissue of patients with CHDs after CPB. The differentially altered miRNAs lay a good foundation for further understanding of the molecular function of changed miRNAs in regulating CHDs and after CPB in particular.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-017-1213-9) contains supplementary material, which is available to authorized users.