AGE, RAGE, and ROS in diabetic nephropathy.

Diabetic nephropathy is a major cause of morbidity and mortality in diabetic patients. Two key mechanisms implicated in the development of diabetic nephropathy include advanced glycation and oxidative stress. Advanced glycation is the irreversible attachment of reducing sugars onto amino groups of proteins to form advanced glycation end products (AGEs). AGE modification of proteins may lead to alterations in normal function by inducing cross-linking of extracellular matrices. Intracellular formation of AGEs also can cause generalized cellular dysfunction. Furthermore, AGEs can mediate their effects via specific receptors, such as the receptor for AGE (RAGE), activating diverse signal transduction cascades and downstream pathways, including generation of reactive oxygen species (ROS). Oxidative stress occurs as a result of the imbalance between ROS production and antioxidant defenses. Sources of ROS include the mitochondria, auto-oxidation of glucose, and enzymatic pathways including nicotinamide adenine dinucleotide phosphate reduced (NAD[P]H) oxidase. Beyond the current treatments to treat diabetic complications such as the optimization of blood pressure and glycemic control, it is predicted that new therapies designed to target AGEs, including AGE formation inhibitors and cross-link breakers, as well as targeting ROS using novel highly specific antioxidants, will become part of the treatment regimen for diabetic renal disease.