Diabetes and Endothelial Dysfunction

Abstract

Diabetes mellitus is a major risk factor for cardiovascular morbidity and mortality. This condition increases the risk of developing coronary, cerebrovascular and peripheral arterial disease up to 4-fold. Disease severity, as measured by chronic glycaemia, is associated with an increasing frequency of clinical events in each vascular bed. Several trials established that hyperglycaemia is the initiating cause of the diabetic tissue injury that we see in daily clinical practice. This process is modulated by genetic determinants of individual susceptibility and by independent accelerating factors such as hypertension and dyslipidaemia, but glycaemic control remains crucial for prevention of cardiovascular disease. The endothelium plays a key role in control of vascular tone by releasing endothelium-derived autacoids, the most important of which is nitric oxide (NO). Reduced NO bioavailability may represent an important triggering event in the initiation and progression of diabetic disease. The L-arginine/NO pathway is impaired at a number of sites in individuals with diabetes. Endothelial dysfunction is associated with a decrease in either basal or stimulated release of NO or there may be an increased breakdown of NO. In a high glucose setting, vascular cells present an increased generation of reactive oxygen species (ROS), with a consequent reduced bioavailability of NO. In this review we analyse the molecular mechanisms involved in the development and progression of diabetic vascular disease; to this purpose, we examine all the pathways, looking for common up- or down-stream events, the ‘unifying mechanism’, that gives us a more complete picture of diabetic disease. Moreover, we focus on the role of a small adaptor protein, p66shc, involved in the generation and regulation of ROS by mitochondria, referring to our experience in the field. Finally, we look at future perspectives and the promising field of stem cells.