Cardiac resident macrophages in AV node conduction

心脏常驻巨噬细胞参与房室结传导

• 批准号: 10365141
• 负责人: Maarten Hulsmans
• 金额: $ 76.28万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-12-01 至 2025-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10365141
• 关键词: Ablation; Adopted; Apoptosis; Atrioventricular Block; Autopsy; Biological Assay; Biomedical Engineering; CSF3 gene; Cardiac; Cardiac Myocytes; Cause of Death; Cells; Communication; Confocal Microscopy; Connexin 43; Connexins; Coupling; Data; Devices; Diphtheria Toxin; Disease; Dose; Electrocardiogram; Electrophysiology (science); Etiology; Extracellular Matrix; Fibrosis; Genetic; Granulocyte-Macrophage Colony-Stimulating Factor; Heart; Heterogeneity; Human; Image; Immune; Immunology; Implant; Incidence; Infusion procedures; Injections; Interleukin-4; Location; Macrophage Colony-Stimulating Factor; Mediating; Monitor; Mus; Muscle Cells; Myeloid Cells; Optics; Pacemakers; Parabiosis; Patients; Phenotype; Population; Process; Protocols documentation; Publishing; Recovery; Recovery of Function; Research; Role; Sampling; Somatotropin; Source; Spatial Distribution; Stains; Stromal Cells; System; Techniques; Telemetry; Testing; Time; Tissues; Work; atrioventricular node; base; clinically relevant; experimental study; improved; in vivo; macrophage; monocyte; mortality; multiphoton microscopy; novel; optogenetics; progenitor; single-cell RNA sequencing; targeted treatment; translational goal

Atrioventricular (AV) conduction abnormalities are common and potentially lethal if not treated with a pacemaker. We recently discovered that macrophages inhabit the mouse and human AV node, and that depletion of macrophages in the Cd11bDTR mouse leads to complete AV block. In the normal murine AV node, macrophages electrically couple to conducting cells via connexin 43. This electrotonic coupling creates a source-sink relationship between macrophages and conducting cardiomyocytes. Genetic interference with macrophage-myocyte coupling weakened AV conduction while optogenetically enhanced communication improved AV node function. These data, which we recently published in Cell, establish that resident macrophages augment the fidelity of AV node conduction. We have continued this work by performing survival studies after macrophage depletion, finding that all mice with AV block die. In preliminary work for this application, we adopted an implantable pacemaker system for mice, and were able to pace mice for several weeks. We here propose to use this technique in Cd11bDTR mice. We will conduct studies to better understand the function of AV node macrophages in order to advance our long-term translational goal to one day develop macrophage-targeted therapeutics as a new option for conduction disorders. We will implant pacemakers into Cd11bDTR mice and pace them for up to three months after macrophage depletion. We will test the hypothesis that, if the mice are supported with a pacemaker, spontaneous recovery of AV node conduction will occur due to recovery of tissue macrophages. We will test for AV node recovery by ECG telemetry in conjunction with in vivo electrophysiological and ex vivo optical mapping studies to provide a comprehensive assessment of AV node function. After recovery, we will isolate AV nodes to investigate the cellular and structural landscape with special focus on macrophage numbers, subset heterogeneity and spatial distribution by FACS, single-cell RNA-sequencing and imaging. Using parabiosis, we will determine whether cardiac macrophages repopulate from circulating monocytes or from tissue progenitors. We will further test whether enhancing tissue macrophage numbers will influence AV node recovery. Since AV node macrophages are reduced in mice lacking macrophage colony stimulating factor (M-CSF), we will treat macrophage-depleted mice with M-CSF to test the hypothesis that such treatment will increase local proliferation of remaining AV node macrophages, and thus ushers in recovery of AV node conduction. We will also explore other growth hormones with influence on myeloid cell replenishment. In a translational aim, we will study macrophages, other non-cardiomyocytes and structural remodeling processes in human AV nodes obtained from patients with AV block. Our collaborative application unites an interdisciplinary team with expertise in electrophysiology, immunology and bioengineering. While the novel research plan is ambitious, we believe that our preliminary data demonstrate feasibility and provide us with a unique opportunity to study a question with high clinical relevance.

房室 (AV) 传导异常很常见，如果不及时治疗，可能会致命 起搏器。我们最近发现巨噬细胞存在于小鼠和人类房室结中，并且 Cd11bDTR 小鼠巨噬细胞的耗竭导致完全房室传导阻滞。在正常小鼠房室结中， 巨噬细胞通过连接蛋白 43 与传导细胞电耦合。这种电耦合产生了 巨噬细胞和传导心肌细胞之间的源库关系。遗传干扰 巨噬细胞-肌细胞耦合减弱了房室传导，同时光遗传学增强了通讯 改进了房室结功能。我们最近在《细胞》杂志上发表的这些数据表明，居民 巨噬细胞增强房室结传导的保真度。我们通过生存来继续这项工作 巨噬细胞耗竭后的研究发现，所有患有房室传导阻滞的小鼠都会死亡。在这方面的前期工作中 在应用程序中，我们为小鼠采用了植入式起搏器系统，并且能够对小鼠起搏数次 几周。我们在这里建议在 Cd11bDTR 小鼠中使用这种技术。我们将进行研究以更好地了解 房室结巨噬细胞的功能，以推进我们的长期转化目标有朝一日发展 巨噬细胞靶向疗法作为传导障碍的新选择。我们将植入起搏器 Cd11bDTR 小鼠，并在巨噬细胞耗尽后对它们进行长达三个月的步调。我们将检验假设 如果小鼠有起搏器支持，房室结传导会自发恢复，因为 组织巨噬细胞的恢复。我们将通过 ECG 遥测结合测试 AV 节点恢复 体内电生理学和离体光学测绘研究可提供 AV 的全面评估 节点功能。恢复后，我们将隔离 AV 节点，以研究细胞和结构景观 通过 FACS、单细胞特别关注巨噬细胞数量、子集异质性和空间分布 RNA 测序和成像。利用联体共生，我们将确定心脏巨噬细胞是否重新增殖 来自循环单核细胞或来自组织祖细胞。我们将进一步测试是否增强组织 巨噬细胞数量会影响房室结的恢复。由于小鼠房室结巨噬细胞减少 缺乏巨噬细胞集落刺激因子（M-CSF），我们将用 M-CSF 治疗巨噬细胞耗尽的小鼠 检验这样的治疗将增加剩余房室结巨噬细胞的局部增殖的假设，并且 从而迎来房室结传导的恢复。我们还将探索其他影响的生长激素 骨髓细胞补充。在转化目标中，我们将研究巨噬细胞、其他非心肌细胞和 从房室传导阻滞患者获得的人类房室结的结构重塑过程。我们的合作 该应用程序联合了一支跨学科团队，拥有电生理学、免疫学和 生物工程。虽然新的研究计划雄心勃勃，但我们相信我们的初步数据表明 可行性并为我们提供了一个独特的机会来研究具有高度临床相关性的问题。