Highlights and Hotspots of Protein Glycation in End-Stage Renal Disease

Analysis of tissues, plasma, urine, other body fluids, and dialysate for glycation adducts has revealed the presence of two major forms: glycation adduct residues of proteins and related glycated amino acids-called glycation free adducts. The major effect on protein glycation in uremia is loss of clearance of glycation free adducts and their marked increase in plasma. Changes in glycation adduct residue content of plasma protein in uremia is, in contrast, relatively modest. There is now doubt as to whether the concept of interaction of advanced glycation endproduct (AGE)-modified proteins with putative AGE receptors can be sustained in vivo. A residual important feature of the receptor for AGEs may be decrease in expression of glyoxalase 1 of the antiglycation defence by S100A12 protein leaving the vasculature vulnerable to dicarbonyl stress and related AGE formation. The dicarbonyl proteome, proteins susceptible to dicarbonyl glycation at functional sites, is the likely mediator of glycation damage in uremia. Glycation of type IV collagen with shedding of endothelial cells and glycation of apolipoprotein B100 with increased atherogenicity of low density lipoprotein are two examples which may link protein glycation to increased risk of cardiovascular disease in end-stage renal disease.