Abstract：
Platelet hyperreactivity contributes to the pathogenesis of COVID-19, which is associated with a hypercoagulability state and thrombosis disorder. It has been demonstrated that Vitamin D deficiency is associated with the severity of COVID-19 infection. Vitamin D supplement is widely used as a dietary supplement due to its safety and health benefits. In this study, we investigated the direct effects and underlying mechanisms of 1,25(OH)2D3 on platelet hyperreactivity induced by SRAS-CoV-2 spike protein via Western blot and platelet functional studies in vitro. Firstly, we found that 1,25(OH)2D3 attenuated platelet aggregation and Src-mediated signaling. We further observed that 1,25(OH)2D3 attenuated spike protein-potentiated platelet aggregation in vitro. Mechanistically, 1,25(OH)2D3 attenuated spike protein upregulated-integrin αIIbβ3 outside-in signaling such as platelet spreading and the phosphorylation of β3, c-Src and Syk. Moreover, using PP2, the Src family kinase inhibitor to abolish spike protein-stimulated platelet aggregation and integrin αIIbβ3 outside-in signaling, the combination of PP2 and 1,25(OH)2D3 did not show additive inhibitory effects on spike protein-potentiated platelet aggregation and the phosphorylation of β3, c-Src and Syk. Thus, our data suggest that 1,25(OH)2D3 attenuates platelet aggregation potentiated by spike protein via downregulating integrin αIIbβ3 outside-in signaling.
摘要：
血小板高反应性与COVID-19的发病机制有关，COVID-19与高凝状态和血栓形成障碍有关。已经证明维生素D缺乏与COVID-19感染的严重程度有关。维生素D补充剂由于其安全和健康益处而被广泛用作膳食补充剂。在这项研究中,我们通过Westernblot和体外血小板功能研究，研究了1,25（OH）2D3对SRAS-CoV-2刺突蛋白诱导的血小板高反应性的直接影响和潜在机制。首先,我们发现1,25(OH)2D3减弱血小板聚集和Src介导的信号传导。我们进一步观察到1,25(OH)2D3在体外减弱刺突蛋白增强的血小板聚集。机械上,1,25（OH）2D3减弱了刺突蛋白上调的整合素αIIbβ3的外在信号传导，例如血小板扩散以及β3，c-Src和Syk的磷酸化。此外，使用PP2，Src家族激酶抑制剂来消除刺突蛋白刺激的血小板聚集和整合素αIIbβ3外部信号，PP2和1,25（OH）2D3的组合对标蛋白增强的血小板聚集和β3，c-Src和Syk的磷酸化没有显示出累加抑制作用。因此，我们的数据表明,1,25(OH)2D3通过下调整合素αIIbβ3的外-内信号传导,减弱刺突蛋白增强的血小板聚集.
