Abstract 421: Aldose Reductase Protects Against the Early Atherosclerotic Lesion Formation InApoe-null Mice
Atherosclerotic lesion formation is associated with extensive oxidation of unsaturated lipids and the accumulation of lipid oxidation products. Products of lipid oxidation, particularly aldehydes, stimulate cytokine production and enhance monocyte adhesion. Aldehydes generated by oxidized lipids are metabolized by several biochemical pathways, of which aldose reductase (AR)-catalyzed reduction represents a metabolic fate common to both free and phospholipid esterified aldehydes. Herein, we tested the hypothesis that inhibition of AR could aggravate atherosclerotic lesion formation by preventing the removal and the detoxification of aldehydes generated by oxidized lipids. In atherosclerotic lesions of apoE-null mice, AR protein was associated with macrophage-rich regions and its abundance increased with lesion progression. Treatment of 8 week old apoE-null mice with AR inhibitors sorbinil or tolrestat for 4 weeks increased lesion formation in the aortic arch (P<0.01) and the aortic sinus (P<0.01). No change in lesion formation was observed when 24 week old mice were fed AR inhibitors for 12 weeks. To probe the role of AR in atherogenesis further, we generated AR−/−/apoE−/− mice. Lesions of 8 week old AR−/−/apoE−/− mice maintained on high fat diet for 4 or 12 weeks were significantly larger throughout the aortic tree (P<0.01 for both the groups) when compared with age-matched AR+/+/apoE−/− mice. Lesions in AR−/−/apoE−/− mice exhibited increased collagen (P<0.01) and macrophage content (P<0.01) and a decrease in smooth muscle cells (P<0.01). GC-MS analysis showed that the concentration of AR substrates HNE and hexanal was increased by 2.5–3 fold (P<0.01) in the plasma of AR−/−/apoE−/− mice as compared with AR+/+/apoE−/− mice. Immunohistochemical analysis showed greater accumulation of protein-HNE adducts in arterial lesions of AR−/−/apoE−/− mice. These observations suggest that AR is up regulated during atherosclerosis and that this protein protects against early stages of atherosclerotic lesion formation by removing aldehydes generated by lipid oxidation.