Background: We aimed to identify the miRNA expression profiles in left atrial appendage, with the intention of\nidentifying miRNAs that were significantly associated with non-valvular paroxysmal AF.\nMethods: The RNA samples were isolated from healthy controls (n = 5) and patients with atrial fibrillation (n = 8). To\nconfirm the findings obtained by analyzing the miRNA profile, we measured the expression of selected miRNAs in\nthe entire cohort by quantitative PCR.\nResults: Ten specific miRNAs were found to be differentially expressed between atrial fibrillation and healthy controls\nwith more than a 2-fold change (P < 0.05). Consistent with the data obtained for the profile, expression levels of\nmiRNA-155, miRNA-146b-5p and miRNA-19b were significantly increased in patients with atrial fibrillation. Interestingly,\nlevels of miRNA-146b-5p and miRNA-155, which are known to be associated with inflammation, were independently\nand positively associated with left atrium dimension, atrial fibrillation duration and high sensitivity C-reactive protein\nlevels. By using four Databases (TargetScan, miRanda, Starbase Clip-seq and miRDB) to perform target gene prediction,\nthere were four genes were related to the inflammatory response and fibrosis, and three others encoding cardiac ion\nchannel proteins. As a result of TaqMan qPCR and Western analysis, the relative mRNA and protein expression level of\nthree target genes (DIER-1, TIMP-4 and CACNA1C) were significantly lower in the atrial fibrillation group than that in\nthe healthy control group.\nConclusions: Expression of inflammation-associated miRNAs is significantly up-regulated in the left atrial appendage of\npatients with non-valvular paroxysmal atrial fibrillation, which may play a significant role in electrical and structural\nremodeling.
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