Project description:Circular RNAs (circRNAs) are an emerging class of RNA species that may play a critical regulatory role in gene expression control, which can serve as diagnostic biomarkers for many diseases due to their abundant, stable, and cell- or tissue-specific expression. However, the association between circRNAs and atrial fibrillation (AF) is still not clear. In this study, we used RNA sequencing data to identify and quantify the circRNAs. Differential expression analysis of the circRNAs identified 250 up- and 126 down-regulated circRNAs in AF subjects compared with healthy donors, respectively. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of the parental genes of the dysregulated circRNAs indicated that the up-regulated parental genes may participate in the process of DNA damage under oxidative stress. Furthermore, to annotate the dysregulated circRNAs, we constructed and merged the competing endogenous RNA (ceRNA) network and protein-protein interaction (PPI) network, respectively. In the merged network, 130 of 246 dysregulated circRNAs were successfully characterized by more than one pathway. Notably, the five circRNAs, including chr9:15474007-15490122, chr16:75445723-75448593, hsa_circ_0007256, chr12:56563313-56563992, and hsa_circ_0003533, showed the highest significance by the enrichment analysis, and four of them were enriched in cytokine-cytokine receptor interaction. These dysregulated circRNAs may mainly participate in biological processes of inflammatory response. In conclusion, the present study identified a set of dysregulated circRNAs, and characterized their potential functions, which may be associated with inflammatory responses in AF. To our knowledge, this is the first study to uncover the association between circRNAs and AF, which not only improves our understanding of the roles of circRNAs in AF, but also provides candidates of potentially functional circRNAs for AF researchers.
Project description:Atrial fibrillation (AF) is the most common tachyarrhythmia and seriously affects human health. Key targets of AF bioinformatics analysis can help to better understand the pathogenesis of AF and develop therapeutic targets. The left atrial appendage tissue of 20 patients with AF and 10 patients with sinus rhythm were collected for sequencing, and the expression data of the atrial tissue were obtained. Based on this, 2578 differentially expressed genes were obtained through differential analysis. Different express genes (DEGs) were functionally enriched on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG), mainly focusing on neuroactive ligand-receptor interactions, neuronal cell body pathways, regulation of neurogenesis, and neuronal death,regulation of neuronal death, etc. Secondly, 14 significant module genes were obtained by analyzing the weighted gene co-expression network of DEGs. Next, LASSO and SVM analyzes were performed on the differential genes, and the results were in good agreement with the calibration curve of the nomogram model for predicting AF constructed by the weighted gene co-expression network key genes. The significant module genes obtained by the area under the ROC curve (AUC) analysis were analyzed. Through crossover, two key disease characteristic genes related to AF, HOXA2 and RND2, were screened out. RND2 was selected for further research, and qPCR verified the expression of RND2 in sinus rhythm patients and AF patients. Patients with sinus rhythm were significantly higher than those in AF patients. Our study shows that RND2 can be used as a new target for the diagnosis and treatment of AF.
Project description:Background. A recent study identified a rare variant in the MRC2 gene in individuals with familial reentrant supraventricular tachycardia, a Wolff-Parkinson-White (WPW) ECG pattern, and structurally normal hearts. WPW syndrome is associated with atrial fibrillation (AF), and MRC2 was recently proposed as a protective gene for AF. Objective. We aimed to determine whether the E990G-heterozygous (het) loss-of-function variant in MRC2 increases AF susceptibility and aberrant atrial cardiofibroblast (ACF) function in mice. Methods. Programmed electrical stimulation (PES) was performed to determine AF susceptibility in E990G-het mice and wild-type (WT) controls. ACFs were isolated from these mice and cultured, and their migration, and collagen deposition were quantified. Finally, transcriptomic profiling by RNA sequencing and secretomic/proteomic profiling by mass spectrometry were performed on ACFs and whole atrial tissue. Results. E990G-het mice exhibited increased susceptibility to pacing-induced AF and had decreased atrioventricular effective refractory periods compared to WT controls. ACFs isolated from E990G-het mice deposited greater amounts of acid-soluble collagen in 2D cultures as quantified by Sirius red staining compared with WT controls. Transcriptomic, secretomic, and proteomic profiling of cultured ACFs and whole-atrial tissue suggest that some fibrotic regulators are differentially expressed or secreted, including decreased ACF expression of matrix metalloproteinase 13 (MMP-13), which degrades collagen types I, II, and III; decreased ACF expression, ACF secretion, and atrial tissue levels of matrix metalloproteinase 12 (MMP-12), which degrades collagen types I, III, IV, elastin, and fibronectin; and increased tissue levels of cellular communication network factor 2/connective tissue growth factor (CCN2/CTGF), a profibrotic regulator. Conclusions. MRC2 E990G-het mice exhibit increased AF susceptibility, altered collagen deposition by ACFs, and differentially regulated fibrotic genes and proteins. Together, these findings suggest that excessive collagen deposition and reduced MMP-mediated collagen removal generate a substrate for the development of AF in the presence of a loss-of-function variant in MRC2.
Project description:Background. A recent study identified a rare variant in the MRC2 gene in individuals with familial reentrant supraventricular tachycardia, a Wolff-Parkinson-White (WPW) ECG pattern, and structurally normal hearts. WPW syndrome is associated with atrial fibrillation (AF), and MRC2 was recently proposed as a protective gene for AF. Objective. We aimed to determine whether the E990G-heterozygous (het) loss-of-function variant in MRC2 increases AF susceptibility and aberrant atrial cardiofibroblast (ACF) function in mice. Methods. Programmed electrical stimulation (PES) was performed to determine AF susceptibility in E990G-het mice and wild-type (WT) controls. ACFs were isolated from these mice and cultured, and their migration, and collagen deposition were quantified. Finally, transcriptomic profiling by RNA sequencing and secretomic/proteomic profiling by mass spectrometry were performed on ACFs and whole atrial tissue. Results. E990G-het mice exhibited increased susceptibility to pacing-induced AF and had decreased atrioventricular effective refractory periods compared to WT controls. ACFs isolated from E990G-het mice deposited greater amounts of acid-soluble collagen in 2D cultures as quantified by Sirius red staining compared with WT controls. Transcriptomic, secretomic, and proteomic profiling of cultured ACFs and whole-atrial tissue suggest that some fibrotic regulators are differentially expressed or secreted, including decreased ACF expression of matrix metalloproteinase 13 (MMP-13), which degrades collagen types I, II, and III; decreased ACF expression, ACF secretion, and atrial tissue levels of matrix metalloproteinase 12 (MMP-12), which degrades collagen types I, III, IV, elastin, and fibronectin; and increased tissue levels of cellular communication network factor 2/connective tissue growth factor (CCN2/CTGF), a profibrotic regulator. Conclusions. MRC2 E990G-het mice exhibit increased AF susceptibility, altered collagen deposition by ACFs, and differentially regulated fibrotic genes and proteins. Together, these findings suggest that excessive collagen deposition and reduced MMP-mediated collagen removal generate a substrate for the development of AF in the presence of a loss-of-function variant in MRC2.
Project description:AimsRecent studies suggest that bioactive mediators called resolvins promote an active resolution of inflammation. Inflammatory signalling is involved in the development of the substrate for atrial fibrillation (AF). The aim of this study is to evaluate the effects of resolvin-D1 on atrial arrhythmogenic remodelling resulting from left ventricular (LV) dysfunction induced by myocardial infarction (MI) in rats.Methods and resultsMI was produced by left anterior descending coronary artery ligation. Intervention groups received daily intraperitoneal resolvin-D1, beginning before MI surgery (early-RvD1) or Day 7 post-MI (late-RvD1) and continued until Day 21 post-MI. AF vulnerability was evaluated by performing an electrophysiological study. Atrial conduction was analysed by using optical mapping. Fibrosis was quantified by Masson's trichrome staining and gene expression by quantitative polymerase chain reaction and RNA sequencing. Investigators were blinded to group identity. Early-RvD1 significantly reduced MI size (17 ± 6%, vs. 39 ± 6% in vehicle-MI) and preserved LV ejection fraction; these were unaffected by late-RvD1. Transoesophageal pacing induced atrial tachyarrhythmia in 2/18 (11%) sham-operated rats, vs. 18/18 (100%) MI-only rats, in 5/18 (28%, P < 0.001 vs. MI) early-RvD1 MI rats, and in 7/12 (58%, P < 0.01) late-RvD1 MI rats. Atrial conduction velocity significantly decreased post-MI, an effect suppressed by RvD1 treatment. Both early-RvD1 and late-RvD1 limited MI-induced atrial fibrosis and prevented MI-induced increases in the atrial expression of inflammation-related and fibrosis-related biomarkers and pathways.ConclusionsRvD1 suppressed MI-related atrial arrhythmogenic remodelling. Early-RvD1 had MI sparing and atrial remodelling suppressant effects, whereas late-RvD1 attenuated atrial remodelling and AF promotion without ventricular protection, revealing atrial-protective actions unrelated to ventricular function changes. These results point to inflammation resolution-promoting compounds as novel cardio-protective interventions with a particular interest in attenuating AF substrate development.
Project description:BackgroundCardiac autonomic perturbations frequently antecede onset of paroxysmal atrial fibrillation (AF). Interventions that influence autonomic inputs to myocardium may prevent AF. However, whether low heart rate or heart rate variability (HRV), which are noninvasive measures of cardiac autonomic dysfunction, are associated with AF incidence is unclear.ObjectivesThis study sought to study the association between HRV and risk of AF.MethodsThis study included 11,715 middle-aged adults in the ARIC (Atherosclerosis Risk In Communities) cohort with heart rate and HRV measures obtained from 2-min electrocardiogram recordings performed at baseline (1987 to 1989). These measures included SD of normal-to-normal RR intervals, high-frequency (HF) (0.15 to 0.40 Hz), low-frequency (0.04 to 0.15 Hz), and the low-frequency/HF ratio (denoting a greater sympathetic to parasympathetic dominance). Incident AF cases were ascertained by electrocardiogram at ARIC follow-up visits, hospital discharge diagnosis, or death certificates through 2011.ResultsDuring an average follow-up of 19.4 years, 1,580 or 13.5% of participants developed AF. A baseline heart rate <60 beats/min was associated modestly with an increased risk of AF. Lower overall HRV as well as increased sympathetic/parasympathetic tone were associated independently with a higher risk of AF; the hazard ratio for each 1 SD lower SD of normal-to-normal RR intervals was 1.14 (95% confidence interval: 1.08 to 1.21), for HF was 1.12 (95% confidence interval: 1.06 to 1.17), and for low frequency/HF was 1.08 (95% confidence interval: 1.03 to 1.14).ConclusionsCardiac autonomic dysfunction denoted by low resting short-term HRV was associated with higher AF incidence. A low heart rate may be associated with higher AF risk. Further studies are needed to determine whether interventions in the general population to restore autonomic balance may prevent AF.
Project description:Atrial fibrillation (AF) is the most common sustained arrhythmia characterized by rapid and multiple irregular excitations within the atria. AF is associated with serious morbidity and increased mortality, and its prevalence is prospected to increase as society ages. The limited therapeutic efficacy of AF treatment as well as its high socioeconomic burden makes AF a major clinical challenge. Despite our expanding knowledge of individual proteins and pathways involved in the complex pathophysiology of atrial fibrillation (AF), an unbiased overview of proteins and functionally enriched biological processes as well as their crosstalk is lacking. Here, we performed an explorative proteomics analysis to reveal the global abundance of proteins in cardiac tissue of patients, and deciphered functionally grouped gene ontologies (GO) to uncover a perspective of the disease biology driving or driven by AF. A total of 2703 proteins were identified by liquid chromatography coupled to tandem mass spectrometry. Among them, 150 proteins (accounting for 5.6% of 2703) had a significantly altered abundance (100 proteins increased and 50 decreased) in AF. A significant biological connection was found between those (protein-protein interaction enrichment p-value=1.0e-16). GO enrichment analysis showed that these 150 proteins were mainly located in extracellular/cytoplasmic vesicles, mitochondrion, and cytoskeletal compartments. Correspondingly, the 100 proteins increased in AF were significantly enriched in the GO terms related to immune system, metabolic process, iron process, ECM disassembly, mitochondrial translation and apoptotic signaling. Partially clustered proteins with dense functional link were found in immune system and metabolic process, and were respectively annotated in neutrophil degranulation, and oxoacid metabolic process coupled to the subunits of mitochondrial dehydrogenase NADH. Those processes enriched in AF had crosstalk via the proteins involved in neutrophil degranulation. Selected proteins such as LCN2 (neutrophil degranulation), CA3 (immune system), NDUFS2 (complex I) and MYH10 (actin motor protein) were validated by western blot or qPCR in an independent cohort. The 50 proteins decreased in AF were collectively enriched in vesicle-mediated transport and actin filament-based movement. We demonstrate that important biological processes underlying persistent AF as well as their crosstalk via the components of neutrophil degranulation. Our study provides a novel insight for a more efficient targeting strategy for AF treatment.
Project description:Atrial fibrillation (AFib) and the risk of its lethal complications are worsened by atrial fibrosis. A recent study implicates osteopontin (encoded by Spp1) secreted by atrial TREM2+ macrophages in this fibrosis. Here, we show that silencing Spp1 in TREM2+ cardiac macrophages using an antibody-siRNA conjugate (ARC) reduces atrial fibrosis and suppresses AFib, thus offering a new immunotherapy for this common arrhythmia.
Project description:Atrial fibrillation (AF) is associated with complex and multifaceted etiology including neural modulation that alters atrial electrophysiology. To explore potential biomarkers for AF and AF recurrence. Peripheral histidine levels in PeAF were significantly higher compared to those in the right atrium and coronary sinus. Receiver operating characteristic (ROC) analysis revealed that peripheral histidine was predictive of AF recurrence, with an optimal cutoff value of ≤ 4.71 µg/mL, yielding a sensitivity of 76.3% and a specificity of 76.5%. The area under the ROC curve (AUC) was 0.75 (95% CI, 0.59–0.90). Peripheral His was robustly associated with lower incidence of AF recurrence after covariates adjustment (OR 0.34, 95% CI 0.14- 0.71, p=0.01).