Deficiency of CuZn superoxide dismutase promotes inflammation and alters medial structure following vascular injury.

Aim: The anti-oxidant enzyme copper/zinc superoxide dismutase (CuZnSOD) metabolizes superoxide anion (O(2)(-)) in vascular cells. However, the role of CuZnSOD in vascular injury remains poorly understood.

Methods: Using CuZnSOD-deficient (CuZnSOD(-/-)) mice and wild-type (WT) mice, we investigated morphometric changes and the role of O(2)(-) in vascular remodeling after femoral artery injury induced by an external vascular cuff model.

Results: Three days post-injury, inflammatory cell infiltration increased significantly. Moreover, the percent positive area of tumor necrosis factor-α (TNF-α), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in media were higher in CuZnSOD(-/-) mice than in WT mice (TNF-α: 34.8±8.4% versus 18.8±5.6%, p < 0.05, ICAM-1: 29.6±6.5% versus 11.0±2.8%, p < 0.05, VCAM-1: 23.5±7.5% versus 3.7±1.1%, p < 0.05). mRNA expression of iNOS was markedly increased in CuZnSOD(-/-) mice with cuff injury. Dihydroethidine staining revealed increased levels of vascular O(2)(-) in media from CuZnSOD(-/-) mice. Although neointimal formation remained unchanged, 14 days postinjury, we observed degeneration of the media, and the media/vessel wall ratio increased in CuZnSOD(-/-) mice (40.4±2.1% versus 26.8±1.4%, p < 0.05). Furthermore, SMemb/MHC-B-stained lesions increased markedly in CuZnSOD(-/-) mice.

Conclusions: CuZnSOD-deficiency promoted inflammation, expressed adhesion molecules, and altered the structure of the media post-injury. Our results suggest that O(2)(-) participates importantly in the progression of early stage vascular inflammation, resulting in vascular remodeling in media but not neointimal formation, post-injury.