Abstract：
Varicose veins are the most common venous disorder in humans and are characterized by hemodynamic instability due to valvular insufficiency and orthostatic lifestyle factors. It is unclear how changes in biomechanical signals cause aberrant remodeling of the vein wall. Our previous studies suggest that Notch signaling is implicated in varicose vein arterialization. In the arterial system, mechanoresponsive ETS1 is a transcriptional activator of the endothelial Notch, but its involvement in sensing disrupted venous flow and varicose vein formation has not been investigated. Here, we use human varicose veins and cultured human venous endothelial cells to show that disturbed venous shear stress activates ETS1-NOTCH4/DLL4 signaling. Notch components were highly expressed in the neointima, whereas ETS1 was upregulated in all histological layers of varicose veins. In vitro microfluidic flow-based studies demonstrate that even minute changes in venous flow patterns enhance ETS1-NOTCH4/DLL4 signaling. Uniform venous shear stress, albeit an inherently low-flow system, does not induce ETS1 and Notch proteins. ETS1 activation under altered flow was mediated primarily by MEK1/2 and, to a lesser extent, by MEK5 but was independent of p38 MAP kinase. Endothelial cell-specific ETS1 knockdown prevented disturbed flow-induced NOTCH4/DLL4 expression. TK216, an inhibitor of ETS-family, prevented the acquisition of arterial molecular identity and loss of endothelial integrity in cells exposed to the ensuing altered shear stress. We conclude that ETS1 senses blood flow disturbances and may promote venous remodeling by inducing endothelial dysfunction. Targeting ETS1 rather than downstream Notch proteins could be an effective and safe strategy to develop varicose vein therapies.
摘要：
静脉曲张是人类最常见的静脉疾病，其特征是由于瓣膜功能不全和体位生活方式因素导致的血液动力学不稳定。目前尚不清楚生物力学信号的变化如何导致静脉壁的异常重塑。我们先前的研究表明，Notch信号与静脉曲张动脉化有关。在动脉系统中,机械反应ETS1是内皮Notch的转录激活因子，但尚未研究其在感知静脉血流中断和静脉曲张形成中的参与。这里,我们使用人静脉曲张和培养的人静脉内皮细胞显示受干扰的静脉剪切力激活ETS1-NOTCH4/DLL4信号传导.Notch成分在新内膜中高度表达，而ETS1在静脉曲张的所有组织学层中上调。基于体外微流体流动的研究表明，即使静脉流动模式的微小变化也会增强ETS1-NOTCH4/DLL4信号传导。均匀的静脉剪切应力，尽管是一个固有的低流量系统，不诱导ETS1和Notch蛋白。改变血流下的ETS1激活主要由MEK1/2介导，在较小程度上，MEK5，但与p38MAP激酶无关。内皮细胞特异性ETS1敲低阻止了受干扰的流动诱导的NOTCH4/DLL4表达。TK216是ETS家族的抑制剂,在暴露于随后改变的剪切应力的细胞中，阻止了动脉分子身份的获得和内皮完整性的丧失。我们得出的结论是，ETS1可感知血流紊乱，并可能通过诱导内皮功能障碍来促进静脉重塑。靶向ETS1而不是下游Notch蛋白可能是开发静脉曲张治疗的有效和安全的策略。
