Ablation alleviates atrial fibrillation by regulating the signaling pathways of endothelial nitric oxide synthase/nitric oxide via miR-155-5p and miR-24-3p.

Background: This study aimed to identify the microRNAs implicated in atrial fibrillation (AF) to investigate the molecular mechanisms underlying the role of microRNAs in ablation-based AF treatment.

Methods: Real-time polymerase chain reaction (PCR) and microRNA microarrays were utilized to measure the profiles of microRNA expression in AF to identify differentially expressed microRNAs. Enzyme-linked immunosorbent assay, real-time PCR, Western blot analysis, and immunohistochemistry assays were also performed to investigate the regulatory relationships among various factors implicated in AF. Finally, bioinformatic tools and luciferase assays were used to confirm the roles of miR-155-5p, miR-24-3p, endothelial nitric oxide synthase (eNOS), and nitric oxide (NO) in the pathogenesis of AF.

Results: We demonstrated that the levels of miR-155-5p and miR-24-3p were greatly reduced in postablation AF patients compared with those AF patients not treated by ablation. Furthermore, the NO level in the AF+ group was much lower than that of the AF- group. Finally, in a swine model of AF, evident upregulation of miR-155-5p and miR-24-3p was found in AF pigs, whereas the ablation treatment reduced the levels of miR-155-5p and miR-24-3p in AF pigs. On contrary, as targets of miR-155-5p and miR-24-3p, the levels of eNOS and NO increased when the expression of miR-155-5p and miR-24-3p decreased.

Conclusion: MiR-155-5p and miR-24-3p are involved in the pathogenesis of AF via regulating the expression of eNOS and the production of NO. In addition, ablation treatment helps the recovery from AF by reducing the expression of miR-155-5p and miR-24-3p.