Inhibitory effects of pigment epithelium derived factor on oxygen-induced retinal neovascularization / 中华眼底病杂志

ABSTRACT

Objective To study the inhibitory effects of pigment epithelium derived factor (PEDF) on oxygen-induced retinal neovascularization in mice,and to investigate the possible involvement of interleukin-1β (IL-1β) in the neovascular-inhibitory function of PEDF.Methods A total of 140 postnatal day (P)7 C57BL/6 mice were randomly divided into normal control group,oxygen-induced retinopathy (OIR) model group,PEDF treatment group and PBS treatment control group.All mice except normal control group with their mothers were exposed to (75 ± 2)％ oxygen environment for 5 days and then kept in room air for another 5 days to establish the OIR model.Mice in normal control group were kept in room air only.At P12 and P14,respectively,mice in PEDF treatment group received intravitreous injections of 1 μl PEDF (2 μg/μl),while PBS treatment control group received the same volume of PBS (10 mmol/L,pH7.4).All mice were euthanized at P17 and eyes were isolated.The changes of retinal vessels were observed on retinal flat mounts and cryosections by fluorescence microscopy.Retinal specimens were prepared for IL-1β protein and mRNA analysis by Western blot and real time fluorescence quantitative reverse transcription-polymerase chain reaction (Real-time RT-PCR).Results Changes of retinal vessels had been viewed by fluorescence microscopy on flat-mounted retina,the relative retinal neovascularization areas were significantly increased in OIR model group compared with normal control group (t =15.02,P＜0.01),and the relative retinal neovascularization areas were obviously smaller in PEDF treatment group than those in PBS treatment control group (t=5.96,P＜0.01).Fluorescence staining revealed that retinal vascular tufts were extending from outer plexiform layer (OPL) to ganglion cell layer (GCL) of the retina along with multiple interconnections; Neovascular tufts in OIR model group and PBS treatment control group were presenting distinctly more than those of normal control group and PEDF treatment group.The specific expression levels of IL-1β protein in retinas of OIR mice by Western blot analysis were higher than those of normal control group(t=3.35,P＜0.05),While these of PEDF treatment group showed a considerable decline in comparison with PBS treatment control group (P＜0.01),and there were no difference in normal control group and PEDF-treated group (F=11.764,P＞0.05).Similarly,expression levels of IL-1β mRNA tested by Real-time RT-PCR were obviously increased in the OIR model group when compared to normal control group(t =4.43,P ＜ 0.01).After treated with PEDF,expression levels of IL-1β mRNA showed a considerable decrease when compared to PBS treatment control group (P ＜ 0.01),and there were no difference in normal control group and PEDF-treated group (F=11.15,P＞0.05).Conclusions PEDF can inhibit oxygen-induced retinal neovascularization.The mechanism may be related to that PEDF can downregulate the expression of IL 1β in retina.