ABSTRACT
Angiogenic response is impaired in diabetes. Here, we examined the involvement of receptor for advanced glycation end products (RAGE) in diabetes-related impairment of angiogenesis in vivo. Angiogenesis was determined in reconstituted basement membrane protein (matrigel) plugs containing vascular endothelial growth factor (VEGF) implanted into nondiabetic or insulin-deficient diabetic wild-type or RAGE(-/-) mice. The total, endothelial, and smooth muscle (or pericytes) cells in the matrigel were significantly decreased in diabetes, with the regulation dependent on RAGE. In the matrigel, proangiogenic VEGF expression was decreased, while antiangiogenic thrombospondin-1 was upregulated in diabetic mice, regardless of the presence of RAGE. In wild-type mice, proliferating cell nuclear antigen (PCNA)-positive cells in the matrigel were significantly less in diabetic than in nondiabetic mice, while the numbers of transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells were significantly higher. This alteration in PCNA- and TUNEL-positive cells in diabetes was not observed in RAGE(-/-) mice. Similarly, the percentage of nuclear factor kappaB-activated cells is enhanced in diabetes, with the regulation dependent on the presence of RAGE. Importantly, adenovirus-mediated overexpression of endogenous secretory RAGE, a decoy receptor for RAGE, restores diabetes-associated impairment of angiogenic response in vivo. Thus, RAGE appears to be involved in impairment of angiogenesis in diabetes, and blockade of RAGE might be a potential therapeutic target.
Subject(s)
Diabetes Mellitus, Experimental/physiopathology , Neovascularization, Physiologic/physiology , Receptors, Immunologic/physiology , Adenoviridae/genetics , Angiopoietin-1/analysis , Angiopoietin-2/analysis , Animals , Apoptosis , Cell Count , Cell Division , Collagen , Drug Combinations , Drug Implants , Endothelial Cells , Gene Expression , Gene Expression Regulation , Glycation End Products, Advanced/blood , Immunohistochemistry , In Situ Nick-End Labeling , Laminin , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 9/genetics , Mice , Mice, Inbred C57BL , Muscle, Smooth, Vascular/cytology , NF-kappa B/physiology , Proliferating Cell Nuclear Antigen/analysis , Proteoglycans , Receptor for Advanced Glycation End Products , Receptors, Immunologic/deficiency , Receptors, Immunologic/genetics , Reverse Transcriptase Polymerase Chain Reaction , Thrombospondin 1/analysis , Transfection , Vascular Endothelial Growth Factor A/administration & dosage , Vascular Endothelial Growth Factor A/analysisABSTRACT
OBJECTIVE: Advanced glycation endproducts, AGEs, and its specific receptor, RAGE, are involved in diabetic vascular complications. Endogenous secretory RAGE, esRAGE, has been identified as an alternatively spliced form of RAGE, and shown to act as a decoy receptor for AGE. Here, we measured plasma esRAGE level with a recently developed enzyme-linked immunosorbent assay (ELISA) and examined its association with atherosclerosis in age- and gender-matched 203 type 2 diabetic and 134 nondiabetic subjects. METHODS AND RESULTS: Plasma esRAGE was inversely associated with carotid or femoral atherosclerosis, as quantitatively measured as intimal-medial thickness (IMT) by arterial ultrasound. Stepwise regression analyses revealed that plasma esRAGE was the third strongest and independent factor associated with carotid IMT, following age and systolic blood pressure. Plasma esRAGE was significantly lower in diabetic patients (0.176+/-0.092 ng/mL) than nondiabetic controls (0.253+/-0.111). Of note, in all, diabetic or nondiabetic group, plasma esRAGE was significantly and inversely correlated with components of the metabolic syndrome including body mass index, blood pressure, triglyceride, HbA1c, or an insulin resistance index. Stepwise regression analyses showed that body mass index or insulin resistance index was the major factor determining plasma esRAGE in all, nondiabetic or diabetic population. CONCLUSIONS: esRAGE is a novel and potential protective factor for the metabolic syndrome and atherosclerosis.
