Abstract
BackgroundAlthough microRNA (miRNA) regulates initiation and/or progression of atrial fibrillation (AF) in canine AF models, the underlying mechanism in humans remains unclear. We speculated that certain miRNAs in atrial tissue are related to AF, and evaluated the relationship of miRNA expression in human atrial tissue in cardiac surgery patients.MethodsRight atrial tissues from 29 patients undergoing cardiovascular surgery were divided into 3 groups [A: chronic AF or unsuccessful maze, n=6; B: successful maze, n=10; C: sinus rhythm (SR) n=13]. miRNA expression was determined using high density microarrays and with Reverse transcriptase-polymerase chain reaction (RT-PCR). Fibrosis was examined using Masson trichrome staining.ResultsmiRNA microarray analysis showed elevated miRNA-21, miRNA-23b, miRNA-199b, and miRNA-208b in AF as compared to SR groups. RT-PCR showed elevated miRNA-21 (1.9-fold) and miRNA-208b (4.2-fold) in AF as compared to the SR groups. miRNA-21 expression increased from Group C to A (A: 2.1-fold, B: 1.8-fold, C: 1.0-fold). Fibrosis increased from C to A (A: 43.0±12.9%, B: 21.3±6.1%, C: 11.9±3.1%). Percent fibrosis and miRNA-21 expression were correlated (r=0.508, p<0.05). The plasma levels of miRNA-21 in AF patients was significantly decreased as compared to the healthy volunteers (p<0.05).ConclusionThe expression of miRNA-21 in human atrial tissue was found to be related to atrial fibrosis and might affect AF occurrence, indicating its usefulness as a biomarker for cardiac surgery management.
Highlights
Atrial fibrillation (AF), the most common type of arrhythmia, affects 5% of the population older than 65 years old and 7.1% of those older than 85 years old [1]
There are several potential structural changes in atrial tissue that affect the occurrence of atrial fibrillation (AF), including dilatation and fibrosis [4]. microRNAs comprise a broad class of small noncoding RNAs composed of 21-25 ribonucleotides, which control the expression of complementary target messenger RNAs [5,6,7,8]
Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of miRNA expression Independent RNA samples that were prepared in parallel with the samples for the microarray were used for quantitative real-time RT-PCR analysis. miRNAs previously described to be related to the heart or AF were investigated in all of the specimens (Table S2)
Summary
Atrial fibrillation (AF), the most common type of arrhythmia, affects 5% of the population older than 65 years old and 7.1% of those older than 85 years old [1]. There are several potential structural changes in atrial tissue that affect the occurrence of AF, including dilatation and fibrosis [4]. Scant information regarding the relationship between miRNA expression in human atrial tissue and occurrence of AF is available. MicroRNA (miRNA) regulates initiation and/or progression of atrial fibrillation (AF) in canine AF models, the underlying mechanism in humans remains unclear. We speculated that certain miRNAs in atrial tissue are related to AF, and evaluated the relationship of miRNA expression in human atrial tissue in cardiac surgery patients. Conclusion: The expression of miRNA-21 in human atrial tissue was found to be related to atrial fibrosis and might affect AF occurrence, indicating its usefulness as a biomarker for cardiac surgery management
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