Oxidative stress exacerbates neovascularization (NV) in many disease processes. In this study we investigated the mechanism of that effect. Mice deficient in
superoxide dismutase 1 (Sod1(-/-) mice) have increased oxidative stress and show severe ocular NV that is reduced to baseline by
antioxidants. Compared with wild-type mice with ischemic retinopathy, Sod1(-/-) mice with ischemic retinopathy had increased expression of several NF-κB-responsive genes, but expression of
vascular cell-adhesion molecule-1 (Vcam1) was particularly high.
Intraocular injection of anti-VCAM-1 antibody eliminated the excessive
ischemia-induced
retinal NV. Elements that contributed to oxidative stress-induced worsening of
retinal NV that were abrogated by blockade of
VCAM-1 included increases in
leukostasis, influx of bone marrow-derived cells, and capillary closure. Compared with
ischemia alone,
ischemia plus oxidative stress resulted in increased expression of several HIF-1-responsive genes caused in part by VCAM-1-induced worsening of nonperfusion and, hence,
ischemia, because anti-VCAM-1 significantly reduced the increased expression of all but one of the genes. These data explain why oxidative stress worsens
ischemia-induced
retinal NV and may be relevant to other neovascular diseases in which oxidative stress has been implicated. The data also suggest that antagonism of
VCAM-1 provides a potential
therapy to combat worsening of neovascular diseases by oxidative stress.