[Overexpression of 15-lipoxygenase-1 inhibits oxygen-induced retinal neovascularization in mice].

OBJECTIVE

To investigate the mechanism and inhibitory effects of overexpression of 15-lipoxygenase-1 inhibiting oxygen-induced retinal neovascularization in mice.

METHODS

Experimental study. Eighty-eight 7-day-old C57BL/6J mice were randomly divided into the normal control group, induced model group, gene treated group and empty vector group with 22 mice in each group. The mice with their mothers were arisen in 75% ± 2% O₂ environment for 5 days and then returned to normoxia for 5 days to establish the oxygen-induced retinopathy (OIR) model. At postnatal day 12, the gene treated group was received an intravitreous injection of Ad-15-LOX-1-EGFP at 1.0 µl, while the empty vector group was received the same volume of Ad-EGFP. At postnatal day 17, real-time PCR and Western Blot methods were used to detect the mRNA and protein expression levels of 15-LOX-1, peroxisome proliferator-activated receptor γ (PPAR-γ) , vascular endothelial growth factor-A (VEGF-A) and vascular endothelial growth factor receptor 2 (VEGFR-2) in the retina. The relative retinal non-perfusion and neovascularization areas were evaluated by FITC-dextran fluorescein angiography on flat-mounted retina. The number of endothelial cell nuclei breaking through the inner limiting membrane (ILM) was counted on hematoxylin and eosin-stained retinal section. Rank sum test and one-way ANOVA were used to assess statistical significance within groups.

RESULTS

The 15-LOX-1 and PPAR-γ mRNA and protein expression levels were higher in gene treated group (15-LOX-1: 2.17 ± 0.25, 1.45 ± 0.10;PPAR-γ:2.12 ± 0.29, 0.85 ± 0.03) than those in induced model group (15-LOX-1:0.62 ± 0.03, 0.66 ± 0.04; PPAR-γ:0.67 ± 0.18, 0.48 ± 0.03) and empty vector group (15-LOX-1:0.51 ± 0.14,0.57 ± 0.03;PPAR-γ:1.07 ± 0.09,0.52 ± 0.02) ( t15-LOX-1 = 12.511, 13.402, both P < 0.01; tPPAR-r = 9.420, 6.813, both P < 0.01). On the contrary,VEGF-A and VEGFR-2 expression levels were lower in gene treated group (

VEGF-A: 0.87 ± 0.07, 0.34 ± 0.01; VEGFR-2:1.02 ± 0.12, 0.45 ± 0.03) than those in induced model group (

VEGF-A: 3.49 ± 0.53,0.74 ± 0.04; VEGFR-2:2.28 ± 0.44, 0.82 ± 0.01) and empty vector group (

VEGF-A: 2.30 ± 0.25,0.69 ± 0.02; VEGFR-2:1.88 ± 0.16, 0.76 ± 0.03) (tVEGF-A = 10.662, 5.843, both P < 0.01; tVEGFR-2 = 6.731, 4.763, both P < 0.01). The relative retinal non-perfusion and neovascularization areas were significantly smaller, and the number of endothelial cell nuclei breaking through the ILM was obviously lower in gene treated group(5.88 ± 1.12; 9.37 ± 1.85; 1.25 ± 0.89) than those in induced model group (21.25 ± 2.87; 24.13 ± 4.29; 60.63 ± 10.82) and empty vector group (19.50 ± 1.78; 23.13 ± 3.52; 54.63 ± 7.63) (P < 0.01; P < 0.01).

CONCLUSION

Overexpression of 15-LOX-1 inhibits ORI neovascularization in mice via up-regulation of PPAR-γ and down-regulation of VEGF-A and VEGFR-2 expression.