Choi Hyun-Jung, Kim Na-Eun, Kim Jayoung, An Sunho, Yang Seung-Hee, Ha Jimin, Cho Sunghee, Kwon Il, Kim Young Dae, Nam Hyo Suk, Heo Ji Hoe
Severance Integrative Research Institute for Cerebral & Cardiovascular Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea.
Severance Integrative Research Institute for Cerebral & Cardiovascular Diseases, Yonsei University College of Medicine, Seoul, Republic of Korea; Brain Korea 21 Plus Project for Medical Science, Yonsei University, Seoul 03722, Republic of Korea.
Thromb Res. 2018 Apr 25. doi: 10.1016/j.thromres.2018.04.019.
Dabigatran etexilate (DE), a new oral anti-coagulant, is a direct thrombin inhibitor. Clinical trials showed the favorable benefit-to-risk profile of DE compared to warfarin for the prevention of ischemic stroke in patients with atrial fibrillation. Remarkably, patients treated with dabigatran showed reduced rates of intracerebral hemorrhage compared to warfarin. As the breakdown of endothelial barrier integrity is associated with hemorrhagic events and as thrombin increases endothelial permeability, we hypothesized that dabigatran preserves the endothelial barrier by inhibiting thrombin-induced permeability. We assessed leakage of fluorescein isothiocyanate (FITC)-dextran through the endothelial monolayer and measured trans-endothelial electrical resistance of the endothelial monolayer after treatment of thrombin or thrombin pre-incubated with dabigatran. Thrombin increased the permeability of endothelial cells. Dabigatran effectively blocked the ability of thrombin to increase permeability. Dabigatran inhibited the formation of actin stress fibers induced by thrombin and inhibited consequent destabilization of junctional protein complexes and intercellular gap formation. The interaction of thrombin with protease activated receptor-1 activates the Rho A guanosine triphosphate (GTP)ase-myosin light chain (MLC) phosphorylation signaling axis, leading to actin cytoskeleton changes. This signaling pathway was effectively inhibited by dabigatran in endothelial cells. Consistently, the number of phosphorylated MLC-positive cells was significantly decreased in ischemic tissue of rat brains. These results indicate dabigatran blocks the ability of thrombin to induce vascular permeability and the resulting underlying signaling cascade in endothelial cells. Our findings provide evidence that dabigatran may confer a lower risk of intracerebral hemorrhage by preserving endothelial barrier integrity.
达比加群酯（DE）是一种新型口服抗凝剂，是一种直接凝血酶抑制剂。临床试验表明，与华法林相比，DE在预防心房颤动患者缺血性卒中方面具有良好的效益风险比。值得注意的是，与华法林相比，接受达比加群治疗的患者脑出血发生率降低。由于内皮屏障完整性的破坏与出血事件相关，且凝血酶会增加内皮通透性，我们推测达比加群通过抑制凝血酶诱导的通透性来维持内皮屏障。我们评估了异硫氰酸荧光素（FITC）-葡聚糖通过内皮单层的渗漏情况，并在凝血酶或与达比加群预孵育的凝血酶处理后测量了内皮单层的跨内皮电阻。凝血酶增加了内皮细胞的通透性。达比加群有效地阻断了凝血酶增加通透性的能力。达比加群抑制了凝血酶诱导的肌动蛋白应力纤维的形成，并抑制了随后连接蛋白复合物的不稳定和细胞间间隙的形成。凝血酶与蛋白酶激活受体-1的相互作用激活了Rho A鸟苷三磷酸（GTP）酶-肌球蛋白轻链（MLC）磷酸化信号轴，导致肌动蛋白细胞骨架变化。在内皮细胞中，这条信号通路被达比加群有效地抑制。同样，在大鼠脑缺血组织中，磷酸化MLC阳性细胞的数量显著减少。这些结果表明，达比加群阻断了凝血酶诱导血管通透性的能力以及内皮细胞中由此产生的潜在信号级联反应。我们的研究结果提供了证据，表明达比加群可能通过维持内皮屏障完整性而降低脑出血风险。
