Vascular involvement in inflammatory bowel disease: pathogenesis and clinical aspects

Crohn's disease (CD) and ulcerative colitis (UC), the two major forms of inflammatory bowel disease (IBD), are chronic inflammatory conditions, characterized by a microvascular and also macrovascular involvement. Chronically inflamed intestinal microvessels of IBD patients have demonstrated significant alterations in their physiology and function compared with vessels from healthy and uninvolved IBD intestine. Recently, some studies have revealed that the poor mucosal healing, refractory inflammatory ulcerations and damage in the IBD intestine could depend on microvascular dysfunction, resulting in diminished vasodilatory capacity and tissue hypoperfusion in the IBD gut. Furthermore, several data show that the activation of intestinal endothelium plays a critical role in the pathogenesis and/or in perpetuating and amplifying the inflammatory process in IBD and, consequently, it is now emerging as a potential use of anticoagulant or coagulation-related drugs in treating IBD. IBD is also associated with an increased risk of macrovascular venous and arterial thrombosis. Thrombotic events occur prevalently as deep vein thrombosis and pulmonary embolism. They happen at an earlier age than in non-IBD patients. Prothrombotic risk factors in IBD patients could be distinguished as acquired, such as active inflammation, immobility, surgery, steroid therapy, and use of central venous catheters, and inherited. Furthermore, it has been found that IBD, per se, is an independent risk factor for thrombosis. The prevention of thromboembolic events in IBD patients includes the elimination of removable risk factors and, if thrombosis occurs, a pharmacological therapy similar to that used for thromboembolic events occurring in the general population.