SARS-CoV-2 Spike protein activates TMEM16F-mediated platelet procoagulant activity.
SARS-CoV-2 Spike protein activates TMEM16F-mediated platelet procoagulant activity.
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DOI：
10.3389/fcvm.2022.1013262
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发表时间：
2022
影响因子：
3.6
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中科院分区：
文献类型：
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肺微血管系统血栓形成是COVID-19疾病的特征，与其他形式的急性呼吸窘迫综合征相比，观察到的血栓形成大大过量，因此表明肺内源性血栓形成的触发因素。我们最近的工作表明，SARS-CoV-2刺突蛋白激活细胞TMEM 16 F氯离子通道和扰码酶。通过对> 3，000种FDA/EMA批准的药物的筛选，我们将氯硝柳胺和氯法齐明鉴定为抑制刺突诱导的TMEM 16活化的最有效分子。由于TMEM 16 F在刺激血小板的促凝血活性中起重要作用，我们研究了刺突是否直接影响血小板活化和促血栓形成功能，并测试了氯硝柳胺和氯法齐明对这些过程的影响。在这里，我们表明，刺，目前无论是在病毒体包膜或细胞质膜上，促进血小板活化，粘附和扩散。Spike作为唯一的激动剂具有活性，或者更有效地通过增强已知血小板激活剂的功能来发挥作用。特别是，穗诱导血小板显着的促凝血表型，通过增强Ca 2+流量，磷脂酰丝氨酸外化的血小板外细胞膜，凝血酶的产生。最终，这增加了凝血酶诱导的凝块形成和收缩。氯硝柳胺和氯法齐明都阻断了这种刺突诱导的促凝血反应。这些发现为解释与严重COVID-19感染相关的肺血栓形成提供了致病机制。我们认为，刺突，存在于SARS-CoV-2病毒体或暴露在肺部感染细胞的表面，增强炎症的影响，并导致局部血小板刺激和随后的凝血级联激活。由于血小板TMEM 16 F在这一过程中起着关键作用，这些发现加强了将氯硝柳胺重新用于COVID-19治疗的理由。
Thrombosis of the lung microvasculature is a characteristic of COVID-19 disease, which is observed in large excess compared to other forms of acute respiratory distress syndrome and thus suggests a trigger for thrombosis that is endogenous to the lung. Our recent work has shown that the SARS-CoV-2 Spike protein activates the cellular TMEM16F chloride channel and scramblase. Through a screening on >3,000 FDA/EMA approved drugs, we identified Niclosamide and Clofazimine as the most effective molecules at inhibiting Spike-induced TMEM16 activation. As TMEM16F plays an important role in stimulating the procoagulant activity of platelets, we investigated whether Spike directly affects platelet activation and pro-thrombotic function and tested the effect of Niclosamide and Clofazimine on these processes. Here we show that Spike, present either on the virion envelope or on the cell plasma membrane, promotes platelet activation, adhesion and spreading. Spike was active as a sole agonist or, even more effectively, by enhancing the function of known platelet activators. In particular, Spike-induced a marked procoagulant phenotype in platelets, by enhancing Ca2+ flux, phosphatidylserine externalization on the platelet outer cell membrane, and thrombin generation. Eventually, this increased thrombin-induced clot formation and retraction. Both Niclosamide and Clofazimine blocked this Spike-induced procoagulant response. These findings provide a pathogenic mechanism to explain lung thrombosis-associated with severe COVID-19 infection. We propose that Spike, present in SARS-CoV-2 virions or exposed on the surface of infected cells in the lungs, enhances the effects of inflammation and leads to local platelet stimulation and subsequent activation of the coagulation cascade. As platelet TMEM16F is central in this process, these findings reinforce the rationale of repurposing Niclosamide for COVID-19 therapy.