Background: Non-enzymatic glycation leading to advanced glycation endproduct (AGE) formation is thought to contribute to vascular pathology. In the present study, AGEs and anti-AGE antibodies in free and immune complex-bound form were assayed in the serum of diabetic (DMCAD) (n = 69) and nondiabetic (n = 78) patients with coronary artery disease (CAD) and in control subjects (n = 47) free from vascular disease.
Methods: A blocking enzyme-linked immunosorbent assay (ELISA) was used to test immunoreactivity against AGE epitope(s) and a competitive ELISA was used to measure total AGE content.
Results: Anti-AGE immunoreactivity was significantly higher in diabetic than in control subjects (P = 0.045). Although a wide range of anti-AGE antibody titres were observed in nondiabetic CAD patients, there was no significant difference from those of control subjects. Both diabetic and nondiabetic CAD patients had a higher concentration of circulating immune complexes containing the AGE moiety as antigen than did control subjects (DMCAD versus control, P = 0.041; CAD versus control, P = 0.047). Study patients showed a positive correlation between serum AGE and AGE-immune complexes (DM, r = 0.29, P = 0.014; CAD, r = 0.26, P = 0.019), whereas no such correlation was recorded in controls (r = 0.08, P = 0.89).
Conclusion: To our knowledge, this is the first study demonstrating increased AGE-immune complexes in patients with CAD, either with or without diabetes, suggesting that AGE-immune complexes might be involved in the atherosclerotic process, either as the result of it or as part of the pathophysiologic process.
