Influence of erythropoietin on expression of matrix metalloproteinases in retinal pigment epithelium with photic injury / 中华实验眼科杂志

ABSTRACT

Background Increase in ophthalmic optical medical instruments and microsurgical applications leads to retinal photochemical damage and other problems delivery of a variety of devices,so the in-depth study and understanding of its pathogenesis after retina light damage can provide a reference for the clinical treatment of related diseases.Objective This study was to investigate the therapeutic effect and relative mechanism of erythropoietin (EPO) on mouse retina photic injury by studying the expression of matrix metalloproteinases-2 (MMP-2)and MMP-9.Methods Fifty-two SPF BALB/c mice were randomized into normal control group,simple light-induced group and EPO pretreatment group by balloting method.The mice of simple light-induced group and EPO pretreatment group were continuously irradiated with 6000 lx diffuse light for 4 hours in a home-made box to establish the models of light-induced damage;while recombinant human EPO (rhEPO)of 5000 U/kg was intraperitoneally injected prior to the light exposure in the EPO pretreatment group.The expressions of MMP-2 and MMP-9 were examined at 6,12,36,72,96 hours and 7 days following light-exposure by immunohistochemistry.Results Edema and structural disorder of RPE cells appeared inthe simple light-induced group after light-exposure and aggravated with lapse of light-exposure time,but no similar change was seen until 7 days in the EPO pretreatment group.The immunohistochemistry findings showed that the expression of MMP-2(A value)in RPE cells was less in the normal mice.However,a large quantity of positive cells appeared in RPE layer 36 hours after light-exposure.Compared with the simple light-induced group,the positive expression of MMP-2 protein in EPO pretreatment group was significantly decreased,showing statistically significant differences among these three groups and different time points (Fgroup =3.68,P =0 04; Ftime =9.13,P=0.00).There was hardly any MMP-9 expression in the retina of the normal mice.In simple light-induced group,a few of positive cells appeared in RPE layer 6 hours after light-exposure and reached its peak 12 hours following light-exposure.The gradually down-regulation of MMP-9 expression happened 96 hours later following light-irradiation.The expression tendency of MMP-9 in EPO pretreatment group was similar to the simple light-induced group.Significant differences in expressions of MMP-9 were found among different groups and time points (Fgroup=3.61,P =0.04;Ftime =16.91,P=0.00).Conclusions MMP-2 and MMP-9 may be involved in the mechanism of retina photic injury by down-regulating the expression of MMP-2 and MMP-9 in RPE cells.