Abstract 1602: Atorvastatin Confers Ischemic Limb Salvage in Type 2 Diabetic Mice by Modulation of Angiogenesis and the Akt/MDM2/p53 Activity
BACKGROUD: Diabetes is a major risk factor for atherosclerotic disease including peripheral artery disease (PAD). Diabetes is known to retard angiogenesis and wound repair possibly through p53-mediated tissue apoptosis. HMG-CoA reductase inhibitors (statins) have been shown to enhance angiogenesis and recently demonstrated to modulate p53 degradation through MDM2, a ubiquitin ligase for p53 in non-diabetic models, however, the effects of statins on the diabetic PAD remains unclear. We examined the effects of statins on the impaired angiogenesis and wound repair using a PAD model of type 2 diabetic mice (KK/Ay).
METHODS AND RESULTS: Autoamputation was frequently observed in the ischemic limb of KK/Ay (16 out of 16, 100%). Ex vivo analyses (aortic ring assay and EPC culture assay) revealed that KK/Ay exhibited impaired angiogenesis (4.97±1.38% vs non-diabetic control, p<0.05) and decline in the endothelial progenitor cell (EPC) number (non-diabetic control: 434.6±13.6 cells/high power field (HPF); KK/Ay:70.8±4.68/HPF, respectively, p<0.05). Immunoblot analysis revealed that expression level of p53, of which expression was not detectable in non diabetic control, was markedly enhanced in the limb of KK/Ay even at non-ischemic condition. Limb ischemia further enhanced the p53 expression in KK/Ay (4.96±0.46 fold vs non-ischemic leg in densitometry, p<0.05). Atorvastatin treatment (2 mg/kg/day p.o., 4 week) ameliorated the impaired angiogenesis and reduced EPC number in KK/Ay. Atorvastatin also enhanced the Akt phosphorylation coupled with enhanced serine 166 phosphorylation of MDM2, that promotes its interaction with p300, allowing MDM2-mediated ubiquitination and degradation of p53, in the ischemic limb of KK/Ay. Enhanced p53 expression was abrogated in the ischemic limb of atorvastatin-treated KK/Ay, leading to the reduction of ischemic limb loss ratio (8 out of 18, 44%).
CONCLUSIONS: Our study demonstrates that atorvastatin improved PAD outcome in diabetic model by facilitating angiogenesis and tissue repair through the degradation of p53 via the Akt-MDM2 pathway.