Non-ischemic cardiomyopathy (NICM) can cause left ventricular dysfunction through interstitial fibrosis, which corresponds to the failure of cardiac tissue remodeling. Recent evidence implicates monocytes/macrophages in the etiopathology of cardiac fibrosis, but giving their heterogeneity and the antagonizing roles of macrophage subtypes in fibrosis, targeting these cells has been challenging. Here we focus on WWP2, an E3 ubiquitin ligase that acts as a positive genetic regulator of human and murine cardiac fibrosis, and show that myeloid specific deletion of WWP2 reduces cardiac fibrosis in hypertension-induced NICM. By using single cell RNA sequencing analysis of immune cells in the same model, we establish the functional heterogeneity of macrophages and define an early pro-fibrogenic phase of NICM that is driven by Ccl5-expressing Ly6c^high monocytes. Among cardiac macrophage subtypes, WWP2 dysfunction primarily affects Ly6c^high monocytes via modulating Ccl5, and consequentially macrophage infiltration and activation, which contributes to reduced myofibroblast trans-differentiation. WWP2 interacts with transcription factor IRF7, promoting its non-degradative mono-ubiquitination, nuclear translocation and transcriptional activity, leading to upregulation of Ccl5 at transcriptional level. We identify a pro-fibrogenic macrophage subtype in non-ischemic cardiomyopathy, and demonstrate that WWP2 is a key regulator of IRF7-mediated Ccl5/Ly6c^high monocyte axis in heart fibrosis.

非缺血性心肌病（NICM）可通过间质纤维化引起左心室功能障碍，对应于心脏组织重构的失败。最近的证据表明单核细胞/巨噬细胞与心脏纤维化的病因病理学有关，但鉴于它们的异质性和巨噬细胞亚型在纤维化中的拮抗作用，靶向这些细胞一直具有挑战性。在这里，我们关注 WWP2，一种 E3 泛素连接酶，作为人类和小鼠心脏纤维化的正基因调节剂，并表明 WWP2 的骨髓特异性缺失可减少高血压诱导的 NICM 中的心脏纤维化。通过对同一模型中的免疫细胞进行单细胞 RNA 测序分析，我们确定了巨噬细胞的功能异质性，并定义了由 NICM 驱动的早期促纤维化阶段Ccl5-表达Ly6c^的高单核细胞。在心脏巨噬细胞亚型中，WWP2 功能障碍主要通过调节 Ccl5 影响 Ly6c^高单核细胞，并因此影响巨噬细胞浸润和激活，这有助于减少肌成纤维细胞的转分化。WWP2 与转录因子 IRF7 相互作用，促进其非降解性单泛素化、核易位和转录活性，导致Ccl5在转录水平上调。我们鉴定了非缺血性心肌病中的促纤维化巨噬细胞亚型，并证明 WWP2 是心脏纤维化中 IRF7 介导的 Ccl5/Ly6c^{高单核细胞轴的关键调节因子。}