Abstract 512: RAGE-dependent Down-regulation of Glyoxalase-1 Impairs Inflammatory Response and Angiogenesis in Hind Limb Ischemia in Diabetic Mice
Critical limb ischemia is a serious form of peripheral artery disease. Previous studies linked the advanced glycation end products (AGEs) and its receptor, RAGE, to impairment of angiogenesis in hind limb ischemia in diabetes. Here, we tested the hypothesis that reduction of RAGE ligand, AGEs, by transgenic (Tg) overexpression of glyoxalase-1 (Glo1), an enzyme that detoxifies AGE precursor methylglyoxal, improves inflammatory responses, angiogenesis and blood flow recovery in hind limb ischemia in diabetic mice. Wild type (WT), Ager-/- (devoid of RAGE) and Tg (Glo1) mice were rendered diabetic (D) with streptozotocin (stz); non-diabetic (ND) cohorts were treated with buffer alone. After two month of diabetes, at age 16 weeks, mice were subjected to unilateral hind limb ischemia. In skeletal muscle tissue within the tributary of the femoral arterial system, a significant increase of Glo1 mRNA was evident in both ND and D Ager-/- mice vs. WT mice after ischemia (p<0.05). A significant reduction in carboxymethyl lysine (CML)-AGEs modified protein was observed in Tg (Glo1) mice compared to WT mice at baseline and on day 5 after ischemia in non-diabetes and diabetes (p<0.05). A significant increase of inflammatory mediators, early growth response-1 (Egr1) (p<0.001) and monocyte chemotactic protein-1 (MCP-1/CCL2) (p<0.01) was observed in ND and D Tg (Glo1) vs. WT mice after ischemia. In parallel, significantly augmented inflammatory cell infiltration identified by increasing CD68+ cell numbers in skeletal muscle tissues was observed in ND and D Tg (Glo1) compared to WT on day 7 after ischemia (p<0.05). Tg(Glo1) mice displayed significantly improved capillary density in both the non-diabetic and diabetic states compared to WT mice on day 28 after ischemia (p<0.05 and p<0.01). Increased blood flow was observed in ND and D Tg (Glo1) mice vs. WT controls (p<0.01). Our findings reveal that RAGE-dependent down-regulation of Glo1 is mechanistically linked, at least in part, to the impaired angiogenic responses observed in WT diabetic mice after hind limb ischemia, suggesting that suppression of AGE-RAGE axis and consequent upregulation of the Glo1 pathway may provide an important therapeutic target in the prevention of diabetic vascular damage.
Author Disclosures: S. Yan: None. X. Shen: None. R. Rosario: None. A. Schmidt: None.
- © 2015 by American Heart Association, Inc.