The CD40-CD40L system in cardiovascular disease.

The CD40-CD40L system is a pathway which is associated with both prothrombotic and proinflammatory effects. CD40 and its ligand were first discovered on the surface of activated T cells, but its presence on B cells, antigen-presenting cells, mast cells, and finally platelets, is evident. The soluble form of CD40L (sCD40L) is derived mainly from activated platelets and contributes to the pathophysiology of atherosclerosis and atherothrombosis. Indeed, sCD40L has autocrine, paracrine, and endocrine activities, and it enhances platelet activation, aggregation, and platelet-leucocyte conjugation that may lead to atherothrombosis. It has even been suggested that sCD40L may play a pathogenic role in triggering acute coronary syndromes. Conversely, blockade of this pathway with anti-CD40L antibodies may prevent or delay the progression of atherosclerosis. Concentrations of sCD40L also predict risk of future cardiovascular disease in healthy women and clinical outcomes in patients with acute coronary syndromes. However, there are controversial and uncertain points over the application of this biomarker to clinical cardiology. In this review, we provide an overview of potential implications of CD40-CD40L signalling and sCD40L as a biomarker in patients with atherosclerotic vascular diseases.