Activation of AP-1 and increased synthesis of MMP-9 in the rabbit retina induced by lipid hydroperoxide

Purpose: We identified the temporal expression of activator protein-1 (AP-1) and matrix metalloproteinases (MMPs) after linoleic acid hydroperoxide (LHP) induction of retinal neovascularization. Methods: After injection of LHP into the vitreous of rabbits, samples were collected for AP-1 binding activity and mRNA for MMP-9 and MMPs activity. AP-1 binding activity was measured by eletrophoretic mobility shift assay. MMP-9 activity was measured by zymography and mRNA by quantitative RT-PCR. Results: AP-1 binding activity was increased at 1-3 hr. MMP-9 mRNA levels were increased at 3 hr in the neural retina and by 12 hr in the retinal pigment epithelium (RPE) layer. MMP-9 proteolytic activity was elevated within the neural retina and within the vitreous and in the RPE-interphotoreceptor matrix (IPM) at 12 hr and peaked at 24 hr or 4 days. Conclusions: LHP increases the transcription factor AP-1 which in turn may regulate retinal MMP-9 synthesis during neovascularization.