The role of inflammation in venous thromboembolism and the link between arterial and venous thrombosis

During the last decade, the role of inflammation in the etiopathogenesis of arterial thrombosis has been elucidated. However, little is known about the relationship between inflammation and venous thrombosis. Recently, inflammation has been accepted as a possible mechanism through which different risk factors trigger thrombus formation in veins. The data indicate that inflammation of the vessel wall initiates thrombus formation in an intact vein and that inflammation and coagulation systems are coupled by a common activation pathway. The first event in thrombus formation is most probably activation of endothelial cells, platelets and leucocytes, with initiation of inflammation and formation of microparticles that trigger the coagulation system through the induction of a tissue factor. Therefore, the key event in the initiation of venous thrombus formation is most probably vein wall inflammation. However, expected relationship between inflammatory markers as indicators of inflammatory process and clinical venous thromboembolism (VTE) has not yet been elucidated. C-reactive protein does not appear to be useful in predicting future venous thrombosis or to be useful in the diagnosis of VTE. Recently, it was demonstrated that probable association between VTE and several other markers of inflammation such as: interleukin (IL)-6, IL-8 and tumor necrosis factor-a exists. While these markers of inflammation were studied during or after acute venous thrombosis, further prospective studies are needed to determine the predictive value of inflammatory markers for VTE. The identification and elucidation of inflammatory markers relevant to venous thrombosis could provide targets for future therapy. That inflammation is the basic etiopathogenetic process of VTE is also supported by the relation of some risk factors to both arterial and venous thrombosis: age, increased body mass index, hypercholesterolemia, hypertension, lupus anticoagulant and hyperhomocysteinemia. A relation was also found between preclinical and clinical atherosclerotic disease and VTE. Also in line with these arguments are the preventive effects of aspirin and statins in both arterial and venous disease.