Targeting Immune-Fibroblast Crosstalk in Myocardial Infarction and Cardiac Fibrosis III

Inflammation and tissue fibrosis co-exist and are causally linked to organ dysfunction. However, the molecular mechanisms driving immune-fibroblast crosstalk in human cardiac disease remains unexplored, and there are currently no approved treatments that directly target cardiac fibrosis. Here, we performed multi-omic single-cell gene expression, epitope mapping, and chromatin accessibility profiling in 45 donors, acutely infarcted, and chronically failing human hearts. We identified a disease-associated fibroblast trajectory marked by cell surface expression of fibroblast activator protein (FAP), which diverged into distinct myofibroblasts and pro-fibrotic fibroblast populations, the latter resembling matrifibrocytes. We lineage traced FAP fibroblasts in vivo and showed that they contribute to the POSTN lineage but not the myofibroblast lineage. We assessed the applicability of experimental systems to model tissue fibrosis and demonstrated that 3 different in vivo mouse models of cardiac injury were superior compared to cultured human heart and dermal fibroblasts in recapitulating the human disease phenotype. Ligand-receptor analysis and spatial transcriptomics predicted that interactions between C-C chemokine receptor type 2 (CCR2) macrophages and fibroblasts mediated by interleukin 1 beta (IL-1ß) signaling drove the emergence of pro-fibrotic fibroblasts within spatially defined niches. In vivo, we deleted the IL-1 receptor on fibroblasts, the IL-1ß ligand in CCR2 monocytes and macrophages, and inhibited IL-1ß signaling using a monoclonal antibody and showed fewer pro-fibrotic fibroblasts, decreased cardiac fibrosis, and improved cardiac function. Herein, we characterize fibroblast lineage diversification in the failing heart and showed a subset of macrophages signal to fibroblasts via IL-1ß and rewire their gene regulatory network and differentiation trajectory towards a pro-fibrotic fibroblast phenotype. These findings highlight the broader therapeutic potential of targeting inflammation to treat tissue fibrosis and preserve organ function. Overall design: To dissect the epigenetic landscape of MI and HF, we performed Multiome (paired single nucleus RNA and ATAC) sequencing of 23 samples including donors, AMI, ICM, and NICM.

炎症与组织纤维化常伴随存在，且与器官功能障碍存在因果关联。然而，人类心脏疾病中驱动免疫-成纤维细胞串扰的分子机制仍未被阐明，且目前尚无获批的直接靶向心脏纤维化的治疗手段。本研究对45名健康供体、急性心肌梗死及慢性心力衰竭的人类心脏样本开展多组学单细胞基因表达、表位作图及染色质可及性分析。本研究鉴定出以成纤维细胞激活蛋白（fibroblast activator protein, FAP）细胞表面表达为特征的疾病相关成纤维细胞分化轨迹，该轨迹可分化为两种截然不同的细胞群：肌成纤维细胞与促纤维化成纤维细胞，后者类似基质成纤维细胞。我们对FAP阳性成纤维细胞开展体内谱系示踪，结果显示其归属POSTN谱系，而非肌成纤维细胞谱系。我们评估了用于模拟组织纤维化的实验系统的适用性，结果表明，相较于体外培养的人类心脏成纤维细胞与皮肤成纤维细胞，3种不同的心脏损伤体内小鼠模型更能重现人类疾病表型。配体-受体分析与空间转录组学研究预测，由白细胞介素1β（interleukin 1 beta, IL-1β）信号介导的C-C趋化因子受体2型（C-C chemokine receptor type 2, CCR2）阳性巨噬细胞与成纤维细胞之间的相互作用，可驱动空间特异性微环境中促纤维化成纤维细胞的产生。体内实验中，我们敲除了成纤维细胞上的IL-1受体、CCR2阳性单核细胞与巨噬细胞中的IL-1β配体，并通过单克隆抗体抑制IL-1β信号通路，结果显示促纤维化成纤维细胞数量减少、心脏纤维化程度降低，且心脏功能得到改善。本研究阐明了衰竭心脏中成纤维细胞的谱系分化特征，并证实部分巨噬细胞可通过IL-1β向成纤维细胞传递信号，重塑其基因调控网络与分化轨迹，使其向促纤维化成纤维细胞表型转变。上述研究结果凸显了靶向炎症以治疗组织纤维化、维持器官功能的广泛治疗潜力。研究整体设计：为解析心肌梗死（myocardial infarction, MI）与心力衰竭（heart failure, HF）的表观遗传调控网络，我们对23例样本开展了Multiome（配对单细胞核RNA与ATAC）测序，样本涵盖健康供体、急性心肌梗死（acute myocardial infarction, AMI）、缺血性心肌病（ischemic cardiomyopathy, ICM）及非缺血性心肌病（non-ischemic cardiomyopathy, NICM）患者。