The protective effect of superoxide dismutase mimetic M40401 on balloon injury-related neointima formation: Role of the lectin-like oxidized low-density lipoprotein receptor-1

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the principal receptor for oxidized low-density lipoprotein (ox-LDL) in vascular endothelial cells (ECs), has recently been suggested to exert a pivotal role in atherogenesis, possibly by mediating ox-LDL-evoked endothelial dysfunction. On the other hand, LOX-1 expression seems to strongly correlate with the oxidative stress occurring in the vascular wall of experimentally injured blood vessels. Here, we investigated LOX-1 expression and superoxide generation during neointima formation in a balloon injury rat carotid artery model. To test this, we used M40401 [a manganese(II) complex with a bis(cyclo-hexylpyridine-substituted) macrocyclic ligand], a synthetic superoxide dismutase mimetic that is a selective scavenger of superoxide. The injury was performed inserting the balloon catheter through the rat common carotid artery and after 14 days a histopathological analysis revealed a significant restenosis with smooth muscle cell proliferation and neointima formation that was associated with an enhanced expression of LOX-1, nitrotyrosine (the footprint of peroxynitrite) staining, and lipid peroxidation as assessed by malondialdehyde (MDA) formation. Pretreatment of rats with M40401 (0.5-10 mg/kg i.p. daily) reduced neointima formation, MDA accumulation, nitrotyrosine staining, and LOX-1 expression. Here, we show that removal of superoxide formation occurring in injured arteries reduces both neointima formation and LOX-1 expression and that this may represent a novel therapeutical approach in the treatment of vascular disorders in which proliferation of vascular smooth muscle cells and ox-LDL-related endothelial cell dysfunction occur.