Superoxide dismutase and catalase inhibit oxidized low-density lipoprotein-induced human aortic smooth muscle cell proliferation: role of cell-cycle regulation, mitogen-activated protein kinases, and transcription factors.

Several antioxidant enzymes, including copper, zinc-superoxide dismutase (Cu, Zn-SOD) and catalase, have been suggested to be protective against the proliferation of vascular smooth muscle cells exposed to oxidative stress. In the present study, we investigated effects of Cu, Zn-SOD and/or catalase on oxLDL-induced proliferation of, and intracellular signaling in, human aortic smooth muscle cells (HASMCs). HASMCs were transfected with adenovirus carrying the human Cu, Zn-SOD gene and/or the human catalase gene. This resulted in a high level of Cu, Zn-SOD and/or catalase overexpression and decreased oxLDL-induced proliferation. Cu, Zn-SOD and/or catalase also arrested cell cycle progression, which was associated with decreased expression of cyclin D1, cyclin E, CDK2, and CDK4 and upregulation of p21(Cip1) and p27(Kip1). Phosphorylation studies on ERK1/2, JNK, and p38, three major subgroups of mitogen activator protein kinases, demonstrated that Cu, Zn-SOD and/or catalase overexpression suppressed ERK1/2 and JNK phosphorylation. Gel-mobility shift analysis showed that oxLDL caused an increase in the DNA binding activity of activator protein-1 (AP-1) and nuclear factor kappaB (NF-kappaB), which was inhibited by Cu, Zn-SOD and/or catalase overexpression. These results provide the first evidence that overexpression of Cu, Zn-SOD and/or catalase in HASMCs attenuates the cell proliferation caused by oxLDL stimulation and that this inhibitory effect is mediated via downregulation of ERK1/2 and JNK phosphorylation and AP-1 and NF-kappaB inactivation. These observations support the feasibility of the increase of Cu, Zn-SOD and/or catalase expression in human smooth muscle cells as a means of protection against oxidant injury.

Induction of prostacyclin/PGI2 synthase expression after cerebral ischemia-reperfusion.

Prostacyclin (PGI2), a potent vasodilator and inhibitor of platelet aggregation and leukocyte activation, is crucial in vascular diseases such as stroke. Prostacyclin synthase (PGIS) is the key enzyme for PGI2 synthesis. Although expression of PGIS was noted in the brain, its role in ischemic insult remains unclear. Here we reported the temporal and spatial expression of PGIS mRNA and protein after 60-min transient ischemia. Northern blot and in situ hybridization revealed a delayed increase of PGIS mRNA in the ischemic cortex at 24- to 72-h after ischemia; PGIS was detected mainly in the ipsilateral penumbra area, pyriform cortex, hippocampus, and leptomeninges. Western blot and immunohistochemical analysis revealed that PGIS proteins were expressed temporally and spatially similar to PGIS mRNA. PGIS was heavily colocalized with PECAM-1 to endothelial cells at the leptomeninges, large and small vessels, and localized to neuronal cells, largely at the penumbra area. A substantial amount of PGIS was also detected in the macrophage and glial cells. To evaluate its role against ischemic infarct, we overexpressed PGIS by adenoviral gene transfer. When infused 72 h before ischemia (- 72 h), Adv-PGIS reduced infarct volume by approximately 50%. However, it had no effect on infarct volume when infused immediately after ischemia (0 h). Eicosanoid analysis revealed selective elevation of PGI2 at - 72 h while PGI2 and TXB2 were both elevated at 0 h, altering the PGI2/thromboxane A2 (TXA2) ratio from 10 to 4. These findings indicate that PGIS protects the brain by enhancing PGI2 synthesis and creating a favorable PGI2/TXA2 ratio.

Superoxide dismutase inhibits the expression of vascular cell adhesion molecule-1 and intracellular cell adhesion molecule-1 induced by tumor necrosis factor-alpha in human endothelial cells through the JNK/p38 pathways.

OBJECTIVE: Expression of adhesion molecules on endothelial cells and subsequent leukocyte recruitment are critical early events in the development of atherosclerosis. We tried to study possible effects of Cu/Zn superoxide dismutase (SOD) on adhesion molecule expression and its underlying mechanism in the prevention and treatment of cardiovascular disorders. METHODS AND RESULTS: Human aortic endothelial cells (HAECs) were transfected with adenovirus carrying the human SOD gene (AdSOD) to investigate whether SOD expression in HAECs attenuated tumor necrosis factor (TNF)-alpha-induced reactive oxygen species production and adhesion molecule expression and to define the mechanisms involved. SOD expression significantly suppressed TNF-alpha-induced expression of vascular cell adhesion molecule-1 and intercellular cell adhesion molecule-1 and reduced the binding of the human neutrophils to TNF-alpha-stimulated HAECs. SOD expression suppressed c-JUN N-terminal kinase and p38 phosphorylation. It also attenuated intracellular superoxide anion production and NADPH oxidase activity in TNF-alpha-treated HAECs. CONCLUSIONS: These results provide evidence that SOD expression in endothelial cells attenuates TNF-alpha-induced superoxide anion production and adhesion molecule expression, and that this protective effect is mediated by decreased JNK and p38 phosphorylation and activator protein-1 and nuclear factor kappaB inactivation. These results suggest that SOD has antiinflammatory properties and may play important roles in the prevention of atherosclerosis and inflammatory response. Superoxide dismutase overexpression in endothelial cells attenuates tumor necrosis factor alpha-induced superoxide anion production and adhesion molecule expression, and this effect is mediated by decreased JNK and p38 phosphorylation and AP-1 and nuclear factor B inactivation. These results suggest that superoxide dismutase may play an important role in the prevention of atherosclerosis and inflammatory response.