Abstract 3645: RAGE Impairs Angiogenesis Consequent to Femoral Artery Ligation in Diabetic Mice
The Receptor for Advanced Glycation Endproducts (RAGE) is implicated in the pathogenesis of diabetic complications. Previous studies illustrated that blockade/genetic deletion of RAGE prevented aberrant neointimal expansion in atherosclerosis and carotid artery balloon injury. Here, we tested the hypothesis that RAGE would contribute to impaired revascularization in the setting of acute femoral artery (FA) ligation, especially in diabetes. Wild type (WT) and RAGE−/−mice were rendered diabetic (D) with streptozotocin (stz); non-diabetic (ND) cohorts were treated with buffer alone. RAGE antigen (Western blotting) was upregulated ≈2.1 fold in the ipsilateral muscle tissue of animals subjected to arterial ligation beginning on day 3 and persisting through 28 days post-operatively; confocal microscopy localized RAGE expression to cells expressing CD31 (EC) and SM actin (SMC). A key proinflammatory RAGE ligand, S100B, was highly upregulated (Western blot) in the ipsilateral muscle tissue from day 1 through 14 after ligation and localized to cells expressing CD45 (inflammatory) and vascular cells (expressing CD31 and SMA). To test the role of RAGE in FA ligation, ND and D mice were subjected to surgery; immediately after surgery, animals received either RAGE ligand-binding decoy soluble RAGE (sRAGE), 200 μg, i/p per day for 7 days) or vehicle, PBS. In D mice, administration of sRAGE resulted in improved blood flow ratios on days 3 and 7 after FA ligation vs. vehicle (p<0.01). To dissect the particular role of RAGE, we tested homozygous RAGE null mice. Both ND and D RAGE−/− mice displayed improved blood flow ratios (laser Doppler) on days 28 after FA ligation compared to ND and D WT mice (p<0.05 & p<0.01). Immunohistochemistry staining with CD31 on ipsilateral muscle tissue demonstrated significantly increased microvessel density in D RAGE−/− mice on days 28 after FA ligation compared to D WT mice (p<0.001). Together, these data link the ligand/RAGE axis to impaired vascular responses consequent to severe tissue ischemia in the peripheral vasculature, particularly in diabetes.