Overexpression of 15-lipoxygenase-1 in oxygen-induced ischemic retinopathy inhibits retinal neovascularization via downregulation of vascular endothelial growth factor-A expression

PURPOSE 15-Lipoxygenase-1 (15-LOX-1) plays an important role in regulating angiogenesis, but the mechanism to date is controversial, even contradictory. The goal of our study was to investigate whether 15-LOX-1 plays a role in inhibiting retinal neovascularization (RNV) in a mouse model of oxygen-induced retinopathy (OIR) and the underlying mechanism. METHODS Experiments were performed using retinas from a mouse model of OIR that was treated with and without intravitreous injection of adenoviral-15-lipoxygenase-1 (Ad-15-LOX-1) or adenoviral-green fluorescence protein (Ad-GFP) at postnatal day 12 (P12). At P17, the efficacy of the gene transfer was assessed with immunofluorescence staining. RNV was evaluated with fluorescein angiography on flatmounted retinas and quantified by counting the preretinal neovascular cells. Expression of 15-LOX-1 and vascular endothelial growth factor-A (VEGF-A) were determined with real-time PCR and western blot. RESULTS RNV during OIR was associated with decreased 15-LOX-1 expression, and retinal 15-LOX-1 levels were negatively correlated with the progression of RNV. In the intravitreous injected Ad-15-LOX-1 mice with OIR, retinal 15-LOX-1 expression was significantly increased at the protein and mRNA levels at P17. 15-LOX-1 expression was clearly demonstrated, primarily in the outer plexiform layer, inner nuclear layer, and ganglion cell layer retinas, five days after gene delivery. Fluorescein retinal angiography and quantification of the preretinal neovascular cells demonstrated that RNV was significantly inhibited. Meanwhile, the expression levels of VEGF-A were significantly decreased at the transcriptional and translational levels. CONCLUSIONS Our results suggest that overexpression of 15-LOX-1 inhibits RNV in a mouse model of OIR via downregulation of VEGF-A expression, and 15-LOX-1 may be a novel therapeutic target for ocular neovascularization diseases.