Endothelial dysfunction is implicated in the thrombotic events reported in patients with coronavirus disease (COVID-19), but the underlying molecular mechanisms are unknown. Circulating levels of the coagulation cascade activator PAI-1 are substantially higher in patients with COVID-19 with severe respiratory dysfunction than in patients with bacterial sepsis and acute respiratory distress syndrome. Indeed, the elevation of PAI-1 is recognized as an early marker of endothelial dysfunction. Here, we report that the rSARS-CoV-2-S1 (recombinant severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2] viral envelope spike) glycoprotein stimulated robust production of PAI-1 by human pulmonary microvascular endothelial cells (HPMECs). We examined the role of protein degradation in this SARS-CoV-2-S1 induction of PAI-1 and found that the proteasomal degradation inhibitor bortezomib inhibited SARS-CoV-2-S1–mediated changes in PAI-1. Our data further show that bortezomib upregulated KLF2, a shear-stress–regulated transcription factor that suppresses PAI-1 expression. Aging and metabolic disorders are known to increase mortality and morbidity in patients with COVID-19. We therefore examined the role of ZMPSTE24 (zinc metallopeptidase STE24), a metalloprotease with a demonstrated role in host defense against RNA viruses that is decreased in older individuals and in metabolic syndrome, in the induction of PAI-1 in HPMECs by SARS-CoV-2-S1. Indeed, overexpression of ZMPSTE24 blunted enhancement of PAI-1 production in spike protein–exposed HPMECs. In addition, we found that membrane expression of the SARS-CoV-2 entry receptor ACE2 was reduced by ZMPSTE24-mediated cleavage and shedding of the ACE2 ectodomain, leading to accumulation of ACE2 decoy fragments that may bind SARS-CoV-2. These data indicate that decreases in ZMPSTE24 with age and comorbidities may increase vulnerability to vascular endothelial injury by SARS-CoV-2 viruses and that enhanced production of endothelial PAI-1 might play role in prothrombotic events in patients with COVID-19.

内皮功能障碍与冠状病毒病 (COVID-19) 患者报告的血栓形成事件有关，但潜在的分子机制尚不清楚。具有严重呼吸功能障碍的 COVID-19 患者的凝血级联激活剂 PAI-1 的循环水平明显高于细菌性败血症和急性呼吸窘迫综合征患者。事实上，PAI-1 的升高被认为是内皮功能障碍的早期标志。在这里，我们报告了 rSARS-CoV-2-S1（重组严重急性呼吸系统综合症冠状病毒 2 [SARS-CoV-2] 病毒包膜刺突）糖蛋白刺激了人肺微血管内皮细胞 (HPMEC) 产生 PAI-1。我们检查了蛋白质降解在 PAI-1 的 SARS-CoV-2-S1 诱导中的作用，发现蛋白酶体降解抑制剂硼替佐米抑制了 SARS-CoV-2-S1 介导的 PAI-1 变化。我们的数据进一步表明，硼替佐米上调 KLF2，这是一种抑制 PAI-1 表达的剪切应力调节转录因子。众所周知，衰老和代谢紊乱会增加 COVID-19 患者的死亡率和发病率。因此，我们研究了 ZMPSTE24（锌金属肽酶 STE24）的作用，这是一种金属蛋白酶，在宿主防御 RNA 病毒方面具有明显作用，在老年人和代谢综合征中降低，在 SARS-CoV 诱导 HPMEC 中 PAI-1 中的作用- 2-S1。事实上，ZMPSTE24 的过表达减弱了暴露于刺突蛋白的 HPMEC 中 PAI-1 产生的增强。此外，我们发现 SARS-CoV-2 进入受体 ACE2 的膜表达因 ZMPSTE24 介导的 ACE2 胞外域的裂解和脱落而降低，导致可能与 SARS-CoV-2 结合的 ACE2 诱饵片段的积累。这些数据表明，随着年龄和合并症的增加，ZMPSTE24 的减少可能会增加 SARS-CoV-2 病毒对血管内皮损伤的脆弱性，并且内皮 PAI-1 的产生增加可能在 COVID-19 患者的血栓前事件中起作用。