Coagulopathy in viral haemorrhagic fevers and beyond: molecular mechanisms and targeted interventions.

Coagulopathy refers to any medical condition which affects the ability of the blood to clot. It can be caused due to genetic conditions like haemophilia, von Willebrand disease, or it can be caused through liver disease or deficiency of Vitamin K. It also involves a broad range of diseases affecting hemostasis as an unbalanced and even bidirectional relationship between thrombosis and bleeding. Coagulopathy can also be caused by thromboinflammation, as seen in VHFs like Ebola, Dengue, Marburg, Crimean-Congo Hemorrhagic Fever, Yellow Fever, and Hantavirus infection. The immune response and coagulation system are intricately linked in such cases. Infections from VHFs cause endothelial cell dysfunction through the immune response, monocytes/macrophages activation, and increased expression of tissue factor (TF), which in turn causes excessive thrombin production and fibrin formation. These conditions result in microvascular thrombosis, organ dysfunction, consumption of platelets and coagulation factors, causing a balanced but fragile state of hemostasis that could tip over towards either thrombosis or bleeding. New therapies have been developed that interfere with these processes, such as interference with the TF pathway (for instance, rNAPc2) and regulation of fibrinolysis (tranexamic acid). The recognition of the double-edged sword of coagulopathy is critical for the development of treatment strategies targeting coagulation disorders. This literature review discusses the molecular basis of immunothrombosis and endothelial dysfunction in VHFs.