Abstract 19027: Glycation of ApoA-IV is Associated With the Severity of Coronary Artery Disease in Diabetic Patients and Glycated ApoA-IV Protein Promotes Atherogenesis Through Nuclear Receptor NR4A3 Mediation

Abstract

Background: ApoA-IV is associated with HDL in plasma but a large portion circulates lipid free. It has been shown to possess anti-inflammatory and anti-atherosclerotic effects. Methods and Results: We isolated HDL from plasma of type 2 diabetic patients and healthy controls, and found that apoA-IV of HDL from diabetic patients was significantly glycated by using Western blot and mass spectrometry. The glycation levels of apoA-IV were higher in diabetic patients than in controls, and were associated with the severity of coronary artery disease. Immunohistochemically, glycation sites co-localized with apoA-IV in atherosclerotic plaques from diabetic patients. In cell and animal studies, in vitro glycated apoA-IV protein promoted inflammatory reactions in human aortic endothelial cells and atherogenesis in apoE-KO mice as compared with control, whereas apoA-IV exhibited anti-inflammatory and anti-atherogenic effects. The pro-inflammatory action of glycated apoA-IV was mediated by receptor for glycation end products in endothelial cells. In microarray analysis and verification in endothelial cells, glycated apoA-IV but not apoA-IV, enhanced the expression of nuclear receptor NR4A3 greatly. Glycated apoA-IV-induced inflammatory reaction and atherogenic effect was significantly attenuated in endothelial cell with siRNA-NR4A3, native endothelial cells and macrophages from NR4A3-KO mice and in NR4A3-KO mice. Co-localization of NR4A3 with CD31 was observed in atherosclerotic plaque from diabetic patients. Moreover, glycated apoA-IV but not apoA-IV induced trans-activation of NR4A3 to the promoter of adhesion molecules (VCAM-1, ICAM-1 and E-selectin). ESI-Q-TOF-MS identified several glycation sites including K78, K189 and K328 in apoA-IV from diabetic patients, but not in controls. Mutated apoA-IV proteins (m-apoA-IV-K78A/K189A/K328A) were made. In vitro glycated m-apoA-IV displayed significantly attenuated activation of NR4A3 in endothelial cells and atherogenesis in apoE-KO mice, as compared with glycated apoA-IV. Conclusion: Glycation of apoA-IV is associated with the severity of coronary artery disease in diabetic patients and glycated apoA-IV protein promotes atherogenesis through nuclear receptor NR4A3 mediation.