Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, 250 Wu-Hsing Street, Taipei 11031, Taiwan.
Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan.
Europace. 2023 Feb 16;25(2):698-706. doi: 10.1093/europace/euac152.
Macrophage migration inhibitory factor (MIF), a pleiotropic inflammatory cytokine, is highly expressed in patients with atrial fibrillation (AF). Inflammation increases the risk of AF and is primarily triggered by pulmonary vein (PV) arrhythmogenesis. This study investigated whether MIF can modulate the electrical activity of the PV and examined the underlying mechanisms of MIF.
A conventional microelectrode, a whole-cell patch clamp, western blotting, and immunofluorescent confocal microscopy were used to investigate electrical activity, calcium (Ca2+) regulation, protein expression, ionic currents, and cytosolic reactive oxygen species (ROS) in rabbit PV tissue and isolated single cardiomyocytes with and without MIF incubation (100 ng/mL, treated for 6 h). The MIF (100 ng/mL)-treated PV tissue (n = 8) demonstrated a faster beating rate (1.8 ± 0.2 vs. 2.6 ± 0.1 Hz, P < 0.05), higher incidence of triggered activity (12.5 vs. 100%, P < 0.05), and premature atrial beat (0 vs. 100%, P < 0.05) than the control PV tissue (n = 8). Compared with the control PV cardiomyocytes, MIF-treated single PV cardiomyocytes had larger Ca2+ transients (0.6 ± 0.1 vs. 1.0 ± 0.1, ΔF/F0, P < 0.05), sarcoplasmic reticulum Ca2+ content (0.9 ± 0.20 vs. 1.7 ± 0.3 mM of cytosol, P < 0.05), and cytosolic ROS (146.8 ± 5.3 vs. 163.7 ± 3.8, ΔF/F0, P < 0.05). Moreover, MIF-treated PV cardiomyocytes exhibited larger late sodium currents (INa-Late), L-type Ca2+ currents, and Na+/Ca2+ exchanger currents than the control PV cardiomyocytes. KN93 [a selective calcium/calmodulin-dependent protein kinase II (CaMKII) blocker, 1 μM], ranolazine (an INa-Late inhibitor, 10 μM), and N-(mercaptopropionyl) glycine (ROS inhibitor, 10 mM) reduced the beating rates and the incidence of triggered activity and premature captures in the MIF-treated PV tissue.
Macrophage migration inhibitory factor increased PV arrhythmogenesis through Na+ and Ca2+ dysregulation through the ROS activation of CaMKII signalling, which may contribute to the genesis of AF during inflammation. Anti-CaMKII treatment may reverse PV arrhythmogenesis. Our results clearly reveal a key link between MIF and AF and offer a viable therapeutic target for AF treatment.
巨噬细胞移动抑制因子（MIF）是一种多功能炎症细胞因子，在心房颤动（AF）患者中高度表达。炎症会增加 AF 的风险，主要由肺静脉（PV）心律失常发生触发。本研究旨在探讨 MIF 是否可以调节 PV 的电活动，并研究 MIF 的潜在机制。
使用常规微电极、全细胞膜片钳、Western blot 和免疫荧光共聚焦显微镜，研究了在有和没有 MIF 孵育（100ng/mL，处理 6 小时）的兔 PV 组织和分离的单个心肌细胞中的电活动、钙（Ca2+）调节、蛋白表达、离子电流和细胞浆活性氧（ROS）。与对照组 PV 组织（n=8）相比，MIF（100ng/mL）处理的 PV 组织（n=8）的搏动率更快（1.8±0.2 比 2.6±0.1Hz，P<0.05），触发活动的发生率更高（12.5 比 100%，P<0.05），房性早搏的发生率更高（0 比 100%，P<0.05）。与对照组 PV 心肌细胞相比，MIF 处理的单个 PV 心肌细胞的 Ca2+瞬变更大（0.6±0.1 比 1.0±0.1，ΔF/F0，P<0.05），肌浆网 Ca2+含量更大（0.9±0.20 比 1.7±0.3mM 细胞质，P<0.05），细胞浆 ROS 更多（146.8±5.3 比 163.7±3.8，ΔF/F0，P<0.05）。此外，与对照组 PV 心肌细胞相比，MIF 处理的 PV 心肌细胞的晚期钠电流（INa-Late）、L 型 Ca2+电流和 Na+/Ca2+交换体电流更大。KN93（一种选择性钙/钙调蛋白依赖性蛋白激酶 II（CaMKII）抑制剂，1μM）、雷诺嗪（INa-Late 抑制剂，10μM）和 N-（巯基丙酰基）甘氨酸（ROS 抑制剂，10mM）降低了 MIF 处理的 PV 组织的搏动率和触发活动的发生率以及房性早搏的发生率。
MIF 通过 ROS 激活 CaMKII 信号转导，导致 Na+和 Ca2+紊乱，从而增加 PV 心律失常的发生，这可能是炎症期间 AF 发生的原因。抗 CaMKII 治疗可能逆转 PV 心律失常。我们的研究结果清楚地揭示了 MIF 与 AF 之间的关键联系，并为 AF 的治疗提供了一个可行的治疗靶点。
