Myofibroblast-Derived Exosomes Contribute to Development of a Susceptible Substrate for Atrial Fibrillation.
- 作者列表："Li S","Gao Y","Liu Y","Li J","Yang X","Hu R","Liu J","Zhang Y","Zuo K","Li K","Yin X","Chen M","Zhong J","Yang X
OBJECTIVE:Atrial fibrosis plays a critical role in atrial fibrillation (AF). A key event in the pathogenesis of fibrosis is the activation of fibroblasts (FBs) into myofibroblasts (MFBs). Paracrine factors released from MFBs lead to ion channel expression changes in cardiomyocytes (CMs). Downregulation of L-type calcium channel Cav1.2 expression is a hallmark of AF-associated ionic remodeling. However, whether exosome (Exo)-mediated crosstalk between MFBs and CMs regulates Cav1.2 expression remains unknown. METHODS:Atrial FBs and CMs were isolated and cultured from neonatal rats by enzymatic digestion. The activation of FBs into MFBs was induced by angiotensin II. Co-culture assay and in vitro Exo treatment were used to determine the effect of MFB-derived Exos on Cav1.2 expression. Confocal Ca2+ imaging was performed to examine the adrenergic stimulation-elicited Ca2+ influx signals. The levels of potential Cav1.2-inhibitory microRNAs (miRNAs) were measured by qRT-PCR. RESULTS:Untreated FBs expressed limited amounts of alpha smooth muscle actin (α-SMA), while angiotensin II induced a significant upregulation of α-SMA-expressing MFBs. Co-cultures of MFBs and CMs resulted in downregulation of Cav1.2 expression in CMs, which was largely abolished by pretreatment of MFBs with exosomal inhibitor GW4869. More importantly, treatment with MFB-derived Exos caused repression of Cav1.2 expression in CMs. Additionally, the adrenergic receptor agonist-elicited Ca2+ influx signals in CMs were remarkably attenuated by pretreatment with MFB-derived Exos, corresponding to the paralleled change in Cav1.2 expression. Finally, miR-21-3p, a potential Cav1.2-inhibitory miRNA, was enriched in MFB-derived Exos and upregulated in CMs in response to MFB-derived Exos. CONCLUSION:We uncover an Exo-mediated crosstalk between MFBs and CMs, contributing to increased vulnerability to AF by reducing the expression of Cav1.2 in CMs.
目的: 心房纤维化在心房颤动 (房颤) 的发生中起着重要作用。纤维化发病机制中的一个关键事件是成纤维细胞 (FBs) 活化为肌成纤维细胞 (mfb)。MFBs 释放的旁分泌因子导致心肌细胞 (CMs) 离子通道表达变化。L 型钙通道 Cav1.2 表达下调是 AF 相关离子重塑的标志。然而，exosome (Exo) 介导的 mfb 和 CMs 之间的串扰是否调控 Cav1.2 表达仍然未知。 方法: 采用酶消化法从新生大鼠体内分离培养心房 FBs 和 CMs。血管紧张素 ⅱ 诱导 FBs 转化为 mfb。共培养试验和体外 Exo 处理用于确定 MFB 来源的 Exos 对 Cav1.2 表达的影响。进行共聚焦 Ca2 + 成像检查肾上腺素能刺激引起的 Ca2 + 内流信号。通过 qRT-PCR 测量潜在 Cav1.2 抑制性 microrna (miRNAs) 的水平。 结果: 未处理的 FBs 表达有限量的 α 平滑肌肌动蛋白 (α-SMA)，而血管紧张素 ⅱ 诱导表达 α-SMA 的 mfb 显著上调。MFBs 和 CMs 共培养导致 CMs 中 Cav1.2 表达下调，这在很大程度上被外泌体抑制剂 gw4869 预处理 MFBs 所消除。更重要的是，MFB 来源的 Exos 治疗引起了 CMs 中 Cav1.2 表达的抑制。此外，通过 MFB 衍生的 Exos 预处理，CMs 中肾上腺素能受体激动剂诱导的 Ca2 + 内流信号显著减弱，相当于 Cav1.2 表达的平行变化。最后，miR-21-3p，一种潜在的 Cav1.2 抑制性 miRNA，在 MFB 来源的 Exos 中富集，并在 CMs 中上调，以响应 MFB 来源的 Exos。 结论: 我们揭示了 mfb 和 CMs 之间的一个 Exo 介导的串扰，通过降低 Cav1.2 在 CMs 中的表达来增加对 AF 的脆弱性。
METHODS:AIMS:Pulmonary vein isolation (PVI) using ablation index (AI) incorporates stability, contact force (CF), time, and power. The CLOSE protocol combines AI and ≤6 mm interlesion distance. Safety concerns are raised about surround flow ablation catheters (STSF). To compare safety and effectiveness of an atrial fibrillation (AF) ablation strategy using AI vs. CLOSE protocol using STSF.,METHODS AND RESULTS:First cluster was treated using AI and second cluster using CLOSE. Procedural data, safety, and recurrence of any atrial tachycardia (AT) or AF >30 s were collected prospectively. All Classes 1c and III anti-arrhythmic drugs (AAD) were stopped after the blanking period. In total, all 215 consecutive patients [AI: 121 (paroxysmal: n = 97), CLOSE: n = 94 (paroxysmal: n = 74)] were included. Pulmonary vein isolation was reached in all in similar procedure duration (CLOSE: 107 ± 25 vs. AI: 102 ± 24 min; P = 0.1) and similar radiofrequency time (CLOSE: 36 ± 11 vs. AI: 37 ± 8 min; P = 0.4) but first pass isolation was higher in CLOSE vs. AI [left veins: 90% vs. 80%; P < 0.05 and right veins: 84% vs. 73%; P < 0.05]. Twelve-month off-AAD freedom of AF/AT was higher in CLOSE vs. AI [79% (paroxysmal: 85%) vs. 64% (paroxysmal: 68%); P < 0.05]. Only four patients (2%) without recurrence were on AAD during follow-up. Major complications were similar (CLOSE: 2.1% vs. AI: 2.5%; P = 0.87).,CONCLUSION:The CLOSE protocol is more effective than a PVI approach solely using AI, especially in paroxysmal AF. In this off-AAD study, 79% of patients were free from AF/AT during 12-month follow-up. The STSF catheter appears to be safe using conventional CLOSE targets.
METHODS:OBJECTIVE:To investigate the role of driver mechanism and the effect of electrogram dispersion-guided driver mapping and ablation in atrial fibrillation (AF) at different stages of progression.,METHODS:A total of 256 consecutive patients with AF who had undergone pulmonary vein isolation (PVI) plus driver ablation or conventional ablation were divided into three groups: paroxysmal atrial fibrillation (PAF; group A, n = 51); persistent atrial fibrillation (PsAF; group B, n = 38); and long standing-persistent atrial fibrillation (LS-PsAF; group C, n = 39). PVI was performed with the guidance of the ablation index. The electrogram dispersion was analyzed for driver mapping.,RESULTS:The most prominent driver regions were at roof (28.0%), posterior wall (17.6%), and bottom (21.3%). From patients with PAF to those with PsAF and LS-PsAF: the complexity of extra-pulmonary vein (PV) drivers including distribution, mean number, and area of dispersion region increased (P < .001). Patients who underwent driver ablation vs conventional ablation had higher procedural AF termination rate (76.6% vs 28.1%; P < .001). With AF progression, the termination rate gradually decreased from group A to group C, and the role of PVI in AF termination was also gradually weakened from group A to group C (39.6%, 7.4%, and 4.3%; P < .001) in patients with driver ablation. At the end of the follow-up, the rate of sinus rhythm maintenance was higher in patients with driver ablation than those with conventional ablation (89.1% vs 70.3%; P < .001).,CONCLUSION:The formation of extra-PV drivers provides an important mechanism for AF maintenance with their complexity increasing with AF progression. Electrogram dispersion-guided driver ablation appears to be an efficient adjunctive approach to PVI for AF treatment.
METHODS:PURPOSE:Whether or not pulmonary vein isolation (PVI) plus left atrial posterior wall isolation (PWI) using contact force (CF) sensing improves the ablation outcome for persistent atrial fibrillation (AF) is unclear. This study compared the outcome of PVI plus PWI and additional non-PV trigger ablation for persistent AF with/without CF sensing. METHODS:This retrospective cohort study analyzed 148 propensity score-matched persistent AF patients (median duration of persistent AF, 8 months (interquartile range, 3-24 months); left atrial diameter, 43 ± 7 mm) undergoing PVI plus PWI and ablation of non-PV triggers provoked by high-dose isoproterenol, including 74 with CF-sensing catheters (CF group) and 74 with conventional catheters (non-CF group). PVI plus PWI with no additional ablation but cavotricuspid isthmus ablation was performed without non-PV triggers in 48 CF patients (65%) and 54 non-CF patients (73%) (P = 0.38). In all other patients, we performed additional ablation of provoked non-PV triggers. RESULTS:The Kaplan-Meier estimate of the rate of freedom from atrial tachyarrhythmia recurrence of antiarrhythmic drugs at 12 months after the single procedure was higher in the CF group than in the non-CF group (85 vs. 70%, log-rank P = 0.030). A multivariable analysis revealed that using CF sensing and non-inducibility of AF from a non-PV trigger after PVI and PWI were significantly associated with a reduced rate of atrial tachyarrhythmia recurrence. CONCLUSIONS:Compared with non-CF sensing, PVI plus PWI and additional non-PV trigger ablation using CF-sensing catheters for persistent AF can reduce the rate of atrial tachyarrhythmia recurrence.