Increased expression of Nox1 in neointimal smooth muscle cells promotes activation of matrix metalloproteinase-9.

Objective: Vascular injury causes neointimal hypertrophy, which is characterized by redox-mediated matrix degradation and smooth muscle cell (SMC) migration and proliferation. We hypothesized that, as compared to the adjacent medial SMCs, neointimal SMCs produce increased superoxide via NADPH oxidase, which induces redox-sensitive intracellular signaling to activate matrix metalloproteinase-9 (MMP-9).

Methods And Results: Two weeks after balloon injury, rat aorta developed a prominent neointima, containing increased expression of NADPH oxidase and reactive oxygen species (ROS) as compared to the medial layer.