Mechanisms of Cardiac Injury Resolution by CX3CR1+ Macrophages

项目总结/摘要 心肌梗死（MI）等缺血性心脏病引起的心力衰竭（HF）是全球性的健康问题 因此，迫切需要新的治疗方法来限制MI后HF的进展。MI后患者结局 这在很大程度上取决于组织重塑的幅度、严重程度和持续时间--这是一个复杂的过程， 心脏结构、功能和细胞组成对损伤的反应的急性和慢性变化。在 特别地，需要适当的瘢痕形成以充分愈合和维持心脏功能。然而，在这方面， 受伤的心脏易患慢性炎症和过度瘢痕形成或纤维化， 功能障碍、病理性重塑和HF倾向。众所周知， 心肌梗死后重塑过程中的反应是瘢痕形成是否以有益的方式进行的关键决定因素。 实现组织愈合或进展为慢性病理性纤维化的途径。心肌梗死后炎症 既有利又有害。例如，急性心肌梗死患者给予广谱抗炎药 由于轻微的纤维化反应，易于发生壁破裂，突出了炎症反应的关键作用。 细胞通过成纤维细胞活性介导急性愈合。以前的工作从建议PI作为博士后 一位研究员发现了一个意想不到的范例，激活先天免疫细胞的一个子集，心脏组织- 常驻巨噬细胞（TRM）表达趋化因子受体CX 3CR 1（CX 3），改善心脏创伤 在小鼠模型中MI后的愈合和有限的纤维化。这提供了概念验证的证据， 可以选择性地增强炎症反应的各个方面，以保持MI后重塑的平衡， 改善成果。然而，在巨噬细胞中驱动这种促愈合表型的精确细胞信号 目前尚不清楚，这阻碍了利用心脏TRM的这些有益作用的治疗的发展。 该提案试图通过阐明CX 3 + TRM在细胞和分子机制中的作用来解决这一问题， 在小鼠MI模型中解决慢性炎症和病理性纤维化。为了实现这一目标，我们将聘请两名 抑制CX 3 + TRM的不同遗传小鼠模型，遗传巨噬细胞追踪，明确的手术模型 以及心脏纤维化的尖端多组学、生物物理学和分子测定。在具体目标1中， 将检验CX 3是心脏TRM促进MI后愈合所需的假设，通过减弱 成纤维细胞扩张和细胞外基质重塑。在具体目标2中，我们利用全面的空间 转录组学和蛋白质组学方法来检验局部心脏微环境提示 炎性巨噬细胞的其它亚群通过CX 3 + TRM阻止纤维化的消退和组织愈合。 总体而言，我们的提案将确定CX 3 + TRM如何在机制上促进心肌愈合， 解决慢性炎症和纤维化。这些数据将揭示潜在的治疗途径，以提高 通过促进CX 3 + TRM功能进行梗死修复。我们的长期目标是提供新的见解， 了解和治疗调节心脏组织重塑，从而限制HF的进展。

PROJECT SUMMARY/ABSTRACT Heart failure (HF) due to ischemic heart diseases such as myocardial infarction (MI) remains a global health crisis and new therapies to limit the progression to HF after MI are greatly needed. Patient outcomes after MI largely depend on the magnitude, severity, and duration of tissue remodeling - a complex process that involves acute and chronic changes in the structure, function, and cellular makeup of the heart in response to injury. In particular, proper scar formation is required for adequate healing and maintenance of cardiac function. However, the injured heart is predisposed to chronic inflammation and excess scarring, or fibrosis, which promotes cardiac dysfunction, pathological remodeling, and propensity towards HF. It is well recognized that the inflammatory response during post-MI remodeling is a critical determinant of whether scar formation proceeds in a beneficial way to achieve tissue healing or progresses to chronic pathological fibrosis. Inflammation in the post-MI setting is both beneficial and detrimental. For example, acute MI patients given broad-acting anti-inflammatory agents are predisposed to wall rupture due to a muted fibrotic response, highlighting the critical role of inflammatory cells in mediating acute healing through fibroblast activity. Prior work from the proposal PI as a postdoctoral fellow uncovered an unexpected paradigm where activating a subset of innate immune cells, cardiac tissue- resident macrophages (TRMs) expressing the chemokine receptor CX3CR1 (CX3), improved cardiac wound healing and limited fibrosis after MI in a mouse model. This provided proof-of-concept evidence that certain aspects of the inflammatory response can be selectively enhanced to keep post-MI remodeling in balance and improve outcomes. However, the precise cellular signals that drive this pro-healing phenotype in macrophages remain unclear, preventing the development of therapies that harness these beneficial effects of cardiac TRMs. This proposal seeks to address this by elucidating the cellular and molecular mechanisms whereby CX3+ TRMs resolve chronic inflammation and pathological fibrosis in a mouse MI model. To achieve this, we will employ two distinct genetic mouse models to inhibit CX3+ TRMs, genetic macrophage tracking, a well-defined surgical model of MI, and cutting-edge multi-omics, biophysical, and molecular assays of cardiac fibrosis. In Specific Aim 1, we will test the hypothesis that CX3 is required for cardiac TRMs to promote healing post-MI, through attenuating fibroblast expansion and extracellular matrix remodeling. In Specific Aim 2, we leverage a comprehensive spatial transcriptomics and proteomics approach to test the hypothesis that local cardiac microenvironment cues from other subsets of inflammatory macrophages prevent resolution of fibrosis and tissue healing by CX3+ TRMs. Overall our Proposal will determine how CX3+ TRMs act mechanistically to promote myocardial healing and resolve chronic inflammation and fibrosis. These data will reveal potential therapeutic pathways to enhance infarct repair by promoting CX3+ TRM functions. Our long-term goal is to contribute novel insights to better understand and therapeutically modulate cardiac tissue remodeling, thus limiting the progression of HF.