M2c巨噬细胞对心房肌细胞电生理影响及在房颤防治中的应用

Atrial fibrillation (AF) is the most common cardiac arrhythmia. It is widely thought that inflammation played an important role in the initiation and maintenance of AF. Our previous work has found that there was increased infiltration of M1 (pro-inflammatory) macrophages in atria of AF patients. These macrophages elevated the incidence of AF by cytokines secretion. Since the M1 (pro-inflammatory) macrophages increased AF incidence, we speculated that M2c (anti-inflammatory) macrophages may serve as a protective role. To verify the hypothesis, we have done some preliminary studies, in which we found that M2c macrophages inhibited the potassium channel KCNQ1 protein expression via IL10 secretion, which further decreased the slow delayed rectifier potassium currents (Iks). This change led to the increase of repolarization time which improved the atrial electrical remodeling. On the basis of our previous work, we will further study the underlying cellular signaling using a combination of technologies including RNA-seq, KCNQ1-GFP reporter knockin strategy and genome scale CRISPR/Cas9 knockout screening. Moreover, we will design an IL10-conjugated gold nanoparticles to delivery IL10 to the atria in order to promote the atrial macrophages subtype transition (from M1 to M2c), which may decrease the AF incidence. Our work will provide a new mechanism as well as a novel therapeutic approach of AF.

目前认为心房颤动与炎症有关，其中巨噬细胞发挥重要作用。申请者在前期研究中发现，房颤患者心房中M1型（促炎型）巨噬细胞浸润增加，并通过分泌炎症因子，增加房颤诱发率。既然M1型巨噬细胞能易化房颤，我们推测M2c型（抑炎型）巨噬细胞有可能减少房颤发生。通过预实验申请者初步发现，M2c巨噬细胞可通过分泌IL10，引起心房肌细胞钾离子通道蛋白KCNQ1表达下调，减少缓慢延迟整流钾电流，延长复极化时间，从而达到改善心房电重构的作用。申请者将在前期研究基础上，利用转录组测序、KCNQ1-GFP报告基因敲入，人全基因敲除筛选等最新技术，研究M2c巨噬细胞对心房肌电生理影响的分子机制，并设计IL10偶联金纳米颗粒，利用心房炎症状态下高渗透性（EPR效应），将IL10靶向至心房炎症区域，实现心脏原位巨噬细胞类型转换（M1转换为M2c），减少房颤发生。本研究结果将完善房颤的发生机制，并提供基础向临床转化的途径

房颤是最常见的心律失常。既往研究发现炎症在房颤的发生发展中起重要作用。我们的既往研究发现房颤患者心房中M1型巨噬细胞浸润增加，并通过分泌炎症因子促进了房颤的发生。既然M1型巨噬细胞可以增加房颤诱发率，我们推测M2c型巨噬细胞可能对房颤发生有保护作用。为研究这一假说，我们进行了膜片钳检测，我们发现M2型巨噬细胞可以延长心房肌细胞动作电位时程。为进一步研究其分子机制，我们开展了RNA-seq，我们发现，M2c型巨噬细胞可抑制心房肌细胞KCNQ1表达，从而导致IKs电流的减少。进一步的研究发现，M2c型巨噬细胞可分泌IL-10，从而抑制心房肌细胞KCNQ1表达。使用激动剂和抑制剂，我们发现M2c型巨噬细胞抑制KCNQ1是通过激动AMPK信号通路实现的。为进一步确认M2c型巨噬细胞对房颤诱发率的影响，我们采用羽扇豆醇促进心房巨噬细胞从M1型向M2c型转换，我们发现，M2c型巨噬细胞可减少房颤的诱发率。综上，我们发现了一个全新的房颤发生机制，并提出羽扇豆醇可能是潜在的房颤治疗靶点。

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