Venous thromboembolism: thrombosis, inflammation, and immunothrombosis for clinicians

Venous thromboembolism (VTE) is a worldwide disease related with mortality, cardiovascular disability, impaired quality of life and, cause major long-term complications. Clinicians related to the acute and longterm patients care must be involved in the molecular mechanisms of thrombosis. The vessel wall and its inner lining of the endothelium are critical to the maintenance of a patent vasculature. After endothelial disruption, collagen ( first line of endothelial defense) and intravascular tissue factor ( second line of endothelial defense) are exposed to blood flow, starting the formation of a thrombus. Anticoagulant endovascular proteins and endogenous fibrinolysis have an active role in hemostasis. Currently, the process of coagulation is a cell surface-based model that includes three overlapping phases: initiation, amplification, and propagation. From a simple view, inflammation is one of the first responses of the immune system to infection; inflammation is driven by eicosanoids and cytokines, which are released by injured or infected cells. Common cytokines, which regulate inflammatory response, include interleukins (mainlyinterleukin-6) that are responsible for communication among white blood cells, chemokines that promote chemotaxis, and interferons that have anti- viral effects. Acute infections have been associated with a transient increase in the risk of myocardial infarction, stroke and recently with venous thrombosis, supporting the notion that systemic and respiratory infections increase the risk of thromboembolic events. Recently, immunothrombosis, another thrombosis mechanism that includes innate immune mechanisms, the neutrophil extracellular genetic traps, and the immunothrombosis dysregulation, could explain some cases of "unprovoked" VTE especially in elderly, a high-risk population for thrombosis.