Abstract 664: Regulation of Angiogenesis and Associated Inflammation by Antioxidant Glutathione in Smooth Muscle Cells

Abstract

Peripheral artery blockage due to formation of atherosclerotic plaques in PVD (Peripheral Vascular Diseases) causes loss of blood flow to peripheral limbs leading to pathogenic consequences, necrosis and in severe cases amputation of the limb. Angiogenesis, the development of new collateral blood vessels is necessary to compensate for this loss of blood flow and prevent pathogenesis resulting from blockage. However, PVD patients, to their detriment, often see decreased angiogenesis and lack of adequate compensatory neo-vascularization along with decreased circulating antioxidant levels. Angiogenesis requires a specific balance of Reactive Oxygen Species(ROS) and neutralizing antioxidants including Glutathione (GSH). Interestingly, our mouse models of PVD with femoral artery ligation (FAL) show a contradictory increase in angiogenesis with a slight decrease in GSH (~80% GSH, Gclm HET mice) compared to WT (100% GSH), not seen with severely decreased GSH in Gclm KO mice (~20% GSH). This suggests that the balance of ROS and antioxidants can be adjusted to a favorable outcome. This led us to hypothesize that a slight decrease in GSH is beneficial and provides “necessary” inflammation to kick-start angiogenesis. To investigate this hypothesis, we performed mRNA-seq analysis on Smooth Muscle Cells (SMCs), an important component of blood vessels known to promote angiogenesis. SMCs were isolated from Gclm WT/HET/KO mice and subjected to hypoxia/re-oxygenation (HR) to mimic blood flow blockage and reperfusion in-vivo . Our hypothesis was confirmed with an increased inflammatory gene expression profile in HET SMCs compared to WT and KO. Results show that slight decrease in antioxidant GSH leads to significant increases in the IL-8, NF-kB, fMLP, MAPK kinase and Notch related signaling pathways, all of which positively influence inflammation associated angiogenesis. Our study suggests that a slight increase in oxidative stress leads to an “appropriate” increase in inflammation and provides adequate environment for accelerated angiogenesis and subsequent tissue perfusion.