The role of immune and inflammatory processes in the development of macrovascular disease in diabetes.

Diabetes is associated with a high incidence of cardiovascular disease, which is the major cause of morbidity and mortality in this disease. There is considerable interest in defining factors responsible for the accelerated development of atherosclerosis in diabetes. There is no evidence to suggest that the inflammatory process in diabetic patients is different from those in non-diabetic individuals. The main difference may lie on factors able to trigger the inflammatory process. Diabetes is a major predisposing factor for the generation of modified proteins though advanced glycation and oxidation, two intimately interrelated processes. Advanced glycation end-products modified low density lipoprotein (AGE-LDL) and other AGE-modified proteins as well as oxidized LDL (oxLDL) are able to interact with a variety of cells and induce cell dysfunction and the release of pro-inflammatory mediators. But AGE-LDL and oxLDL are also immunogenic. Activated T lymphocytes reacting with peptides derived from oxidized LDL have been detected in atheromatous lesions. Their pro-inflammatory potential is directly linked to the release of interferon-gamma and other cytokines able to activate macrophages, smooth muscle cells, and endothelial cells. On the other hand, antibodies to oxidized and AGE-modified LDL have been isolated from diabetic patients and shown to belong predominantly to the IgG isotype, subclasses 1 and 3, which have well-defined proinflammatory properties. These autoantibodies to modified lipoproteins have sufficient affinity to form stable antigen-antibody complexes, which have been also shown to have pro-atheromatous and pro-inflammatory properties.