Several thrombogenic abnormalities are associated with diabetes. To investigate the underlying molecular mechanisms, we examined the effects of advanced glycation endproducts (AGE), non-en; zymatically glycated protein derivatives, on the production of prostacyclin (PGI(2)), an anti-thrombogenic prostanoid, and of plasminogen activator inhibitor-1 (PAI-1), a fast-acting serine protease inhibitor of fibrinolysis, in human microvascular endothelial cells (EC). Firstly, AGE-bovine serum albumin (BSA) but not non-glycated BSA, was found to considerably decrease the production of PGI(2) to about two-thirds of the control value. Secondly, quantitative reverse transcription-polymerase chain reaction showed that AGE-BSA increased the EC levels of mRNA coding for PAI-1, this being associated with a concomitant increase in the immunoreactive PAI-1 contents and the anti-fibrinolytic activity. Thirdly, the effects of AGE on PGI(2) and PAI-1 syntheses in EC were found to be mediated by a receptor for AGE (RAGE) because antisense DNA against RAGE mRNA could reverse the AGE effects. Further, it was found that AGE decreased the intracellular cyclic AMP concentrations in EC and that cyclic AMP agonists such as dibutyryl cyclic AMP, forskolin and PGI(2) analogue reduced the AGE-stimulated PAI-1 production, suggesting the involvement of cyclic AMP in the AGE-signalling pathway. The results thus suggest that AGE have the ability to cause platelet aggregation and fibrin stabilization, resulting in a predisposition to thrombogenesis and thereby contributing to the development and progression of diabetic vascular complications.
