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

From Beats to Metabolism: the Heart at the Core of Interorgan Metabolic Cross Talk

The heart, once considered a mere blood pump, is now recognized as a multifunctional metabolic and endocrine organ. Its function is tightly regulated by various metabolic processes, at the same time it serves as an endocrine organ, secreting bioactive molecules that impact systemic metabolism. In recent years, research has shed light on the intricate interplay between the heart and other metabolic organs, such as adipose tissue, liver, and skeletal muscle. The metabolic flexibility of the heart and its ability to switch between different energy substrates play a crucial role in maintaining cardiac function and overall metabolic homeostasis. Gaining a comprehensive understanding of how metabolic disorders disrupt cardiac metabolism is crucial, as it plays a pivotal role in the development and progression of cardiac diseases. The emerging understanding of the heart as a metabolic and endocrine organ highlights its essential contribution to whole body metabolic regulation and offers new insights into the pathogenesis of metabolic diseases, such as obesity, diabetes, and cardiovascular disorders. In this review, we provide an in-depth exploration of the heart's metabolic and endocrine functions, emphasizing its role in systemic metabolism and the interplay between the heart and other metabolic organs. Furthermore, emerging evidence suggests a correlation between heart disease and other conditions such as aging and cancer, indicating that the metabolic dysfunction observed in these conditions may share common underlying mechanisms. By unraveling the complex mechanisms underlying cardiac metabolism, we aim to contribute to the development of novel therapeutic strategies for metabolic diseases and improve overall cardiovascular health.

The Role of Epicardial Adipose Tissue-Derived MicroRNAs in the Regulation of Cardiovascular Disease: A Narrative Review

Cardiovascular diseases have been leading cause of death worldwide for many decades, and obesity has been acknowledged as a risk factor for cardiovascular diseases. In the present review, human epicardial adipose tissue-derived miRNAs reported to be differentially expressed under pathologic conditions are discussed and summarized. The results of the literature review indicate that some of the epicardial adipose tissue-derived miRNAs are believed to be cardioprotective, while some others show quite the opposite effects depending on the underlying pathologic conditions. Furthermore, they suggest that that the epicardial adipose tissue-derived miRNAs have great potential as both a diagnostic and therapeutic modality. Nevertheless, mainly due to highly limited availability of human samples, it is very difficult to make any generalized claims on a given miRNA in terms of its overall impact on the cardiovascular system. Therefore, further functional investigation of a given miRNA including, but not limited to, the study of its dose effect, off-target effects, and potential toxicity is required. We hope that this review can provide novel insights to transform our current knowledge on epicardial adipose tissue-derived miRNAs into clinically viable therapeutic strategies for preventing and treating cardiovascular diseases.

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.

Advances of Liquid Biopsy for Diagnosis of Atrial Fibrillation and Its Recurrence After Ablation in Clinical Application

Atrial fibrillation (AF) is a common arrhythmia disease with high morbidity in clinical practice and leads to stroke, heart failure, peripheral embolism, and other severe complications. With aging of the society, AF has become one of the biggest public health challenges. Effective treatments including antiarrhythmic drugs, electrical cardioversion, and ablation (with or without catheters) can alleviate the symptoms of AF. Ablation is the most effective method for the treatment of persistent AF, but cannot cure all patients. Recurrence of AF is a realistic and unavoidable problem. For early predicting and warning of AF and its recurrence, liquid biopsy for accurate molecular analysis of biofluids is a new strategy with potential value and easy sampling and can detect genetic and epigenetic polymorphisms, especially microRNAs. In this review, liquid biopsy is constructed as a new powerful way for diagnosing AF and predicting its recurrence, contributing to the treatment of AF.

Integrated Analysis of the microRNA–mRNA Network Predicts Potential Regulators of Atrial Fibrillation in Humans

Atrial fibrillation (AF) is a form of sustained cardiac arrhythmia and microRNAs (miRs) play crucial roles in the pathophysiology of AF. To identify novel miR–mRNA pairs, we performed RNA-seq from atrial biopsies of persistent AF patients and non-AF patients with normal sinus rhythm (SR). Differentially expressed miRs (11 down and 9 up) and mRNAs (95 up and 82 down) were identified and hierarchically clustered in a heat map. Subsequently, GO, KEGG, and GSEA analyses were run to identify deregulated pathways. Then, miR targets were predicted in the miRDB database, and a regulatory network of negatively correlated miR–mRNA pairs was constructed using Cytoscape. To select potential candidate genes from GSEA analysis, the top-50 enriched genes in GSEA were overlaid with predicted targets of differentially deregulated miRs. Further, the protein–protein interaction (PPI) network of enriched genes in GSEA was constructed, and subsequently, GO and canonical pathway analyses were run for genes in the PPI network. Our analyses showed that TNF-α, p53, EMT, and SYDECAN1 signaling were among the highly affected pathways in AF samples. SDC-1 (SYNDECAN-1) was the top-enriched gene in p53, EMT, and SYDECAN1 signaling. Consistently, SDC-1 mRNA and protein levels were significantly higher in atrial samples of AF patients. Among negatively correlated miRs, miR-302b-3p was experimentally validated to suppress SDC-1 transcript levels. Overall, our results suggested that the miR-302b-3p/SDC-1 axis may be involved in the pathogenesis of AF.

Hub microRNAs and genes in the development of atrial fibrillation identified by weighted gene co-expression network analysis

Co-expression network may contribute to better understanding molecular interaction patterns underlying cellular processes. To explore microRNAs (miRNAs) expression patterns correlated with AF, we performed weighted gene co-expression network analysis (WGCNA) based on the dataset GSE28954. Thereafter, we predicted target genes using experimentally verified databases (ENOCRI, miRTarBase, and Tarbase), and overlapped genes with differentially expressed genes (DEGs) from GSE79768 were identified as key genes. Integrated analysis of association between hub miRNAs and key genes was conducted to screen hub genes. In general, we identified 3 differentially expressed miRNAs (DEMs) and 320 DEGs, predominantly enriched in inflammation-related functional items. Two significant modules (red and blue) and hub miRNAs (hsa-miR-146b-5p and hsa-miR-378a-5p), which highly correlated with AF-related phenotype, were detected by WGCNA. By overlapping the DEGs and predicted target genes, 38 genes were screened out. Finally, 9 genes (i.e. ATP13A3, BMP2, CXCL1, GABPA, LIF, MAP3K8, NPY1R, S100A12, SLC16A2) located at the core region in the miRNA-gene interaction network were identified as hub genes. In conclusion, our study identified 2 hub miRNAs and 9 hub genes, which may improve the understanding of molecular mechanisms and help to reveal potential therapeutic targets against AF.

An update on the roles of immune system-derived microRNAs in cardiovascular diseases

Cardiovascular diseases (CVD) are a leading cause of human death worldwide. Over the past two decades, the emerging field of cardioimmunology has demonstrated how cells of the immune system play vital roles in the pathogenesis of CVD. MicroRNAs (miRNAs) are critical regulators of cellular identity and function. Cell-intrinsic, as well as cell-extrinsic, roles of immune and inflammatory cell-derived miRNAs have been, and continue to be, extensively studied. Several 'immuno-miRNAs' appear to be specifically expressed or demonstrate greatly enriched expression within leucocytes. Identification of miRNAs as critical regulators of immune system signalling pathways has posed the question of whether and how targeting these molecules therapeutically, may afford opportunities for disease treatment and/or management. As the field of cardioimmunology rapidly continues to advance, this review discusses findings from recent human and murine studies which contribute to our understanding of how leucocytes of innate and adaptive immunity are regulated-and may also regulate other cell types, via the actions of the miRNAs they express, in the context of CVD. Finally, we focus on available information regarding miRNA regulation of regulatory T cells and argue that targeted manipulation of miRNA regulated pathways in these cells may hold therapeutic promise for the treatment of CVD and associated risk factors.

Association between adiponectin-to-leptin ratio and heart rate variability in new-onset paroxysmal atrial fibrillation: A retrospective cohort study

Background

The adiponectin‐to‐leptin (A/L) ratio has been identified as a potential surrogate biomarker for metabolic disorders. However, it remains unknown whether the serum A/L ratio is associated with heart rate variability in paroxysmal atrial fibrillation (AF).

Methods

For this retrospective study, we included consecutive patients who underwent 24‐h long‐range electrocardiogram examination in our center for paroxysmal AF. The results of echocardiography, heart rate variability tests, and blood tests were also retrieved. Multivariate line regression analysis was performed to evaluate identify factors independently associated with heart rate variability.

Results

Among the 85 included patients with paroxysmal AF, the median A/L ratio was 1.71. Univariate analysis indicated that patients with a low A/L ratio (<1.71, n = 42) had a lower high‐frequency (HF) power and a higher hs‐CRP level, low‐frequency (LF) power, and LF/HF ratio than those with a high A/L ratio (≥1.71, n = 43). Multivariate linear regression analysis showed that the serum leptin concentration was independently and positively associated with LF (β = 0.175, p = .028), while the serum adiponectin concentration was independently and positively associated with HF (β = 0.321, p = .001). Moreover, the A/L ratio was independently and negatively associated with the LF/HF ratio (β = −0.276, p = .007).

Conclusions

The A/L ratio was independently and negatively associated with the LF/HF ratio in patients with new‐onset paroxysmal AF.

The Sick Adipose Tissue: New Insights Into Defective Signaling and Crosstalk With the Myocardium

Adipose tissue (AT) biology is linked to cardiovascular health since obesity is associated with cardiovascular disease (CVD) and positively correlated with excessive visceral fat accumulation. AT signaling to myocardial cells through soluble factors known as adipokines, cardiokines, branched-chain amino acids and small molecules like microRNAs, undoubtedly influence myocardial cells and AT function via the endocrine-paracrine mechanisms of action. Unfortunately, abnormal total and visceral adiposity can alter this harmonious signaling network, resulting in tissue hypoxia and monocyte/macrophage adipose infiltration occurring alongside expanded intra-abdominal and epicardial fat depots seen in the human obese phenotype. These processes promote an abnormal adipocyte proteomic reprogramming, whereby these cells become a source of abnormal signals, affecting vascular and myocardial tissues, leading to meta-inflammation, atrial fibrillation, coronary artery disease, heart hypertrophy, heart failure and myocardial infarction. This review first discusses the pathophysiology and consequences of adipose tissue expansion, particularly their association with meta-inflammation and microbiota dysbiosis. We also explore the precise mechanisms involved in metabolic reprogramming in AT that represent plausible causative factors for CVD. Finally, we clarify how lifestyle changes could promote improvement in myocardiocyte function in the context of changes in AT proteomics and a better gut microbiome profile to develop effective, non-pharmacologic approaches to CVD.

Adipose-related microRNAs as modulators of the cardiovascular system: the role of epicardial adipose tissue

Adipose tissue expansion and subsequent metabolic dysfunction has been considered one of the major risk factors for development of cardiometabolic disease. Epicardial adipose tissue (EAT) in particular is a unique subtype of visceral adipose tissue located on the surface of the heart, around the coronary arteries. Due to its proximity, EAT can modulate the local metabolic and immune function of cardiomyocytes and coronary arteries. Several microRNAs have been described as key players in both cardiac and vascular function that when dysregulated will contribute to dysfunction. Here we review the influence of obesity in the crosstalk between specific adipose tissue types, in particular the EAT-secreted microRNAs, as key modulators of cardiac disease progression, not only as early biomarkers but also as therapeutic targets for cardiometabolic disease.

Circulating miR-155 and JAK2/STAT3 Axis in Acute Ischemic Stroke Patients and Its Relation to Post-Ischemic Inflammation and Associated Ischemic Stroke Risk Factors

Background

“Micro RNAs and their target genes recently have been identified to play a crucial role in the molecular pathogenesis of post-stroke ischemic cellular injury, which elucidates their new role in ischemic stroke diagnosis and therapy”. Thus, we evaluated the relative serum expression of miR-155, an inflammatory micro RNA, and the mRNAs (JAK2/STAT3) in acute ischemic stroke patients and its associations with the inflammatory cytokine TNF-α and different stroke risk factors.

Subjects and Methods

The relative expression of serum miR-155 and mRNAs (JAK2/STAT3) was assessed using RT-PCR, serum TNF-α was measured using ELIZA in 46 acute ischemic stroke patients and 50 control subjects. Receiver operating characteristic (ROC) curve was constructed to assess the specificity and sensitivity of circulating miR-155, JAK2/STAT3 as biomarkers for acute ischemic stroke.

Results

Circulating miR-155, JAK2/STAT3 were significantly up-regulated among stroke patients (8.5, 2.9, 4.2 fold respectively, P<0.001) with significant increase in TNF-α (263.8 ± 10.7 pg/mL, P <0.001). MiR-155, JAK2/STAT3 were positively correlated with TNF-α. MiR-155, JAK2/STAT3 were significantly increased in stroke patients and associated with risk factors such as hypertension, carotid atherosclerosis, and atrial fibrillation. Our study revealed that miR-155 has diagnostic accuracy for acute ischemic stroke where AUC=0.9, (P<0.001).

Conclusion

The elevated expressions of circulating miR-155, JAK2/STAT3, and TNF-α in acute ischemic stroke patients could trigger post-stroke cellular inflammation. MiR-155 could be used as potential inflammatory biomarker for acute ischemic stroke. However, further clinical studies are still needed to determine the exact role of miRNAs and different signal transduction expressions in the stage of acute ischemic stroke.

MicroRNA-200b-3p promotes endothelial cell apoptosis by targeting HDAC4 in atherosclerosis

Background

Epicardial adipose tissue (EAT) shares the same microcirculation with coronary arteries through coronary arteries branches, and contributes to the development of atherosclerosis. MicroRNAs (miRNAs) are involved in the formation of atherosclerosis. However, the alteration of miRNA profile in EAT during atherosclerosis is still uncovered.

Methods

The miRNA expression profiles of EAT from non-coronary atherosclerosis disease (CON, n = 3) and coronary atherosclerosis disease (CAD, n = 5) patients was performed to detect the differentially expressed miRNA. Then the expression levels of miRNA in other CON (n = 5) and CAD (n = 16) samples were confirmed by realtime-PCR. miR-200b-3p mimic was used to overexpress the miRNA in HUVECs. The apoptosis of HUVECs cells was induced by H₂O₂ and ox-LDL, and detected by Annexin V/PI Staining, Caspase 3/7 activity and the expression of BCL-2 and BAX.

Results

250 miRNAs were differentially expressed in EAT from CAD patients, which were associated with metabolism, extracellular matrix and inflammation process. Among the top 20 up-regulated miRNAs, the expression levels of miR-200 family members (hsa-miR-200b/c-3p, miR-141-3p and miR-429), which were rich in endothelial cells, were increased in EAT from CAD patients significantly. Upregulation of miR-200 family members was dependent on the oxidative stress. The overexpression of miR-200b-3p could promote endothelial cells apoptosis under oxidative stress by targeting HDAC4 inhibition.

Conclusions

Our study suggests that EAT derived miR-200b-3p promoted oxidative stress induced endothelial cells damage by targeting HDAC4, which may provide a new and promising therapeutic target for AS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-021-01980-0.

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.

The roles of epicardial adipose tissue in heart failure

Heart failure is a growing health problem resulting in the decreased life expectancy of patients and severely increased the healthcare burden. Penetrating research on the pathogenesis and regulation mechanism of heart failure is important for treatment of heart failure. Epicardial adipose tissue (EAT) has been demonstrated as not only a dynamic organ with biological functions but also an inert lipid store with regulating systemic metabolism. EAT mediates physiological and pathophysiological processes of heart failure by regulating adipogenesis, cardiac remodeling, insulin resistance, cardiac output, and renin angiotensin aldosterone system (RAAS). Moreover, EAT secretes a wide range of adipokines, adrenomedullin, adiponectin, and miRNAs through paracrine, endocrine, and vasocrine pathways, which involve in various extracellular and intracellular mechanism of cardiac-related cells in the progress of cardiovascular disease especially in heart failure. Nevertheless, mechanisms and roles of EAT on heart failure are barely summarized. Understanding the regulating mechanisms of EAT on heart failure may give rise to novel therapeutic targets and will open up innovative strategies to myocardial injury as well as in heart failure.