A study on retinal angiomatous proliferation and its mechanism in apolipoprotein E-deficient mouse with dyslipidemia / 中华实验眼科杂志

ABSTRACT

Background Retinal angiomatous proliferation (RAP) is a subtype of neovascular age-related macular degeneration (AMD).There are currently very few studies on RAP.Objective This study was to explore the pathogenic mechanism of RAP in apolipoprotein E-deficient (ApoE-/-) mice with dyslipidemia.Methods Twenty-four 2-month-old SPF ApoE-/-mice were randomly divided into the high fat diet group and the normal diet group,and twelve 2-month-old C57BL/6 mice received the normal diet as controls.A diet with a higher content of fat was given for 4 consecutive months in the high fat diet group,and normal diet was given in the same way in the mice of the normal diet group.The mice were sacrificed at 6 months of age.The expression of vascular endothelial growth factor (VEGF) in the retinal pigment epithelial (RPE) cells,the expression of vascular endothelial growth factor receptor-2 (VEGFR-2) in the outer plexiform layer (OPL),microvascular density (MVD) and microvascular area (MVA) in the OPL were examined by immunohistochemistry and semi-quantitatively by histopathology with the Mias 2000 Imaging Analyzer System.The expression of VEGF protein in the retina was examined by Western blot.Results The MVD in the retinal OPL were (20.67±3.20) and (19.50± 1.87),respectively,in the ApoE-/-mice of the high fat diet group and the normal diet group,which were significantly higher than that (12.50±1.87) of the C57BL/6 normal diet group (all at P＜0.01).MVA in the retinal OPL were (626.49± 120.99) μm2 and (514.06±88.83) μm2 in the ApoE-/-mice of the high fat diet group and the normal diet group,respectively,showing a significant increase in comparison with the (336.52±84.96) μm2 of the C57BL/6 normal diet group (P＜0.01).The staining area of VEGF in RPE cells was (21 048±1849) μm2 in the ApoE-/-mice of the high fat diet group,showing a significant increase in comparison with the (17 116±2023) μm2 of the C57BL/6 normal diet group.However,no significant difference was found in the staining area of VEGF between the ApoE-/-mice with normal diet group and the C57BL/6 normal diet group ([17 854±2967] μm2 vs.[17 116±2023] μm2) (P＞0.05).Significant elevation was also seen in the staining area of VEGFR-2 in the retinal OPL of the ApoE-/-mice of the high fat diet group (12 193±3806)μm2 and the ApoE-/-mice of the normal diet group (11 969± 3616)xm2 compared with C57BL/6 mice of the normal diet group (5387±2225)μm2(all at P＜0.01).The relative expression values (VEGF/β-actin) of VEGF in the retinas were (1.51 ±0.32) and (1.17±0.39) in the ApoE-/-mice of the high fat diet group and the normal diet group,respectively,showing a significant increase in comparison with (0.28±0.14) of the C57BL/6 normal diet group (P＜0.01).Conclusions The expression of VEGF and VEGFR-2 in the retinas increases in the ApoE-/-mouse,which leads to the enlargement of MVD and MVA in the retinal OPL and subsequent RAP occurrence.