Out of balance: a role of impaired superoxide dismutase activity for vascular constrictive remodeling after angioplasty

Differential roles of NADPH oxidases in vascular physiology and pathophysiology

Reactive oxygen species (ROS) are produced by all vascular cells and regulate the major physiological functions of the vasculature. Production and removal of ROS are tightly controlled and occur in discrete subcellular locations, allowing for specific, compartmentalized signaling. Among the many sources of ROS in the vessel wall, NADPH oxidases are implicated in physiological functions such as control of vasomotor tone, regulation of extracellular matrix and phenotypic modulation of vascular smooth muscle cells. They are involved in the response to injury, whether as an oxygen sensor during hypoxia, as a regulator of protein processing, as an angiogenic stimulus, or as a mechanism of wound healing. These enzymes have also been linked to processes leading to disease development, including migration, proliferation, hypertrophy, apoptosis and autophagy. As a result, NADPH oxidases participate in atherogenesis, systemic and pulmonary hypertension and diabetic vascular disease. The role of ROS in each of these processes and diseases is complex, and a more full understanding of the sources, targets, cell-specific responses and counterbalancing mechanisms is critical for the rational development of future therapeutics.

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.