Background and Aims: Liver fibrosis represents a global health burden, given the paucity of approved antifibrotic therapies. Liver sinusoidal endothelial cells (LSECs) play a major gatekeeping role in hepatic homeostasis and liver disease pathophysiology. In early tumorigenesis, runt-related transcription factor 3 (RUNX3) functions as a sentinel; however, its function in liver fibrosis in LSECs remains unclear. This study aimed to investigate the role of RUNX3 as an important regulator of the gatekeeping functions of LSECs and explore novel angiocrine regulators of liver fibrosis. Approach and Results: Mice with endothelial Runx3 deficiency develop gradual and spontaneous liver fibrosis secondary to LSEC dysfunction, thereby more prone to liver injury. Mechanistic studies in human immortalized LSECs and mouse primary LSECs revealed that IL-6/JAK/STAT-3 pathway activation was associated with LSEC dysfunction in the absence of RUNX3. Single-cell RNA sequencing and quantitative RT-PCR revealed that leucine-rich alpha-2-glycoprotein 1 (LRG1) was highly expressed in RUNX3-deficient and dysfunctional LSECs. In in vitro and coculture experiments, RUNX3-depleted LSECs secreted LRG1, which activated hepatic stellate cells via TGFBR1–SMAD2/3 signaling in a paracrine manner. Furthermore, circulating LRG1 levels were elevated in mouse models of liver fibrosis and in patients with fatty liver and cirrhosis. Conclusions: RUNX3 deficiency in the endothelium induces LSEC dysfunction, LRG1 secretion, and liver fibrosis progression. Therefore, endothelial RUNX3 is a crucial gatekeeping factor in LSECs, and profibrotic angiocrine LRG1 may be a novel target for combating liver fibrosis.

中文翻译：

---

内皮RUNX3控制LSEC功能障碍和血管分泌LRG1信号传导以预防肝纤维化


背景和目的：鉴于批准的抗纤维化疗法很少，肝纤维化是全球健康负担。肝窦内皮细胞（LSEC）在肝脏稳态和肝脏疾病病理生理学中发挥着重要的把关作用。在早期肿瘤发生过程中，runt 相关转录因子 3 (RUNX3) 发挥着哨兵的作用。然而，其在 LSEC 肝纤维化中的作用仍不清楚。本研究旨在探讨RUNX3作为LSEC守门功能的重要调节因子的作用，并探索肝纤维化的新型血管分泌调节因子。方法和结果：具有内皮细胞的小鼠奔跑x3缺乏会导致 LSEC 功能障碍继发的逐渐自发性肝纤维化，从而更容易发生肝损伤。对人永生化 LSEC 和小鼠原代 LSEC 的机制研究表明，在 RUNX3 缺失的情况下，IL-6/JAK/STAT-3 通路激活与 LSEC 功能障碍相关。单细胞 RNA 测序和定量 RT-PCR 揭示富含亮氨酸的 α-2-糖蛋白 1 ( LRG1 ) 在 RUNX3 缺陷和功能失调的 LSEC 中高表达。在体外和共培养实验中，RUNX3耗尽的LSEC分泌LRG1，LRG1通过TGFBR1-SMAD2/3信号以旁分泌方式激活肝星状细胞。此外，在肝纤维化小鼠模型以及脂肪肝和肝硬化患者中，循环 LRG1 水平升高。结论：内皮细胞 RUNX3 缺陷会导致 LSEC 功能障碍、LRG1 分泌和肝纤维化进展。因此，内皮RUNX3是LSEC中关键的把关因子，而促纤维化血管分泌素LRG1可能是对抗肝纤维化的新靶点。