Recent articles report elevated markers of coagulation, endothelial injury, and microthromboses in lungs from deceased COVID‐19 patients. However, there has been no discussion of what may induce intravascular coagulation. Platelets are critical in the formation of thrombi and their most potent trigger is platelet activating factor (PAF), first characterized by Demopoulos and colleagues in 1979. PAF is produced by cells involved in host defense and its biological actions bear similarities with COVID‐19 disease manifestations. PAF can also stimulate perivascular mast cell activation, leading to inflammation implicated in severe acute respiratory syndrome (SARS). Mast cells are plentiful in the lungs and are a rich source of PAF and of inflammatory cytokines, such as IL‐1β and IL‐6, which may contribute to COVID‐19 and especially SARS. The histamine‐1 receptor antagonist rupatadine was developed to have anti‐PAF activity, and also inhibits activation of human mast cells in response to PAF. Rupatadine could be repurposed for COVID‐19 prophylaxis alone or together with other PAF‐inhibitors of natural origin such as the flavonoids quercetin and luteolin, which have antiviral, anti‐inflammatory, and anti‐PAF actions.

中文翻译：

---

COVID-19，微血栓形成，炎症和血小板活化因子

最近的文章报道死者COVID-19患者的肺部凝血，内皮损伤和微血栓形成标志物升高。但是，尚未讨论什么可能引起血管内凝血。血小板对血栓形成至关重要，其最有效的触发机制是血小板活化因子（PAF），该因子最初由Demopoulos及其同事于1979年表征。PAF由参与宿主防御的细胞产生，其生物学作用与COVID-19疾病相似表现形式。PAF还可以刺激血管周围肥大细胞的活化，从而导致严重的急性呼吸综合征（SARS）引起的炎症。肥大细胞在肺中丰富，并且是PAF和炎性细胞因子（例如IL-1β和IL-6）的丰富来源，这可能有助于COVID-19，尤其是SARS。组胺-1受体拮抗剂卢帕他定具有抗PAF活性，并且还可以响应PAF抑制人肥大细胞的活化。卢帕他定可单独或与其他天然PAF抑制剂（例如类黄酮槲皮素和木犀草素）一起用于预防COVID-19，它们具有抗病毒，抗炎和抗PAF作用。