Expression Of Matrix Metalloproteinases In Retinal Pigment Epithelium After Photic Injury And After Erythropoietin Treatment

【Objective】To investigate the therapeutic effect and relative mechanism of EPO(erythropoietin)onmice retina photic injury by studying the expression of MMP(Matrix metalloproteinases)-2, MMP-9and caspase-3.【Methods】RPE(Retinal pigment epithilium) apoptosis was induced in retinas ofBALB/c mice by exposure to 6000lux of diffuse white light. 52 BALB/c mice were randomly dividedinto control group(CON), simple light-induced group(SL) and EPO pretreatment group (EP), the miceof SL and EP were continually exposed to light for 4h, which built model of light-induceddamage. Morphologic difference of RPE in different group was examined by light microscope and HEStaining, Different expression of MMP-2,MMP-9 and caspase-3 gene was examined byimmunohistochemical method.【Result】(1)The result of HE stain showed that the early phenomenonof SL group is RPE cellularoedema, loosened arrangement, irregular form, cell lossed will appear astime of light exposure was increased, and at last, cell apoptosis induced. In EP group, the change ofRPE histology happened lately and less obviously, moreover, the number of apoptosis cells wasdecreased.(2) The immunohistochemistry findings showed that in the normal retina, the expression ofMMP-2 was low. A great quantity of positive numbers appeared in RPE layer after 36 hours lightexposure. Compared with the injury group, the positive expression of MMP-2 protein of EP groupdecreased significantly(P＜0.01).(3) The immunohistochemistry findings showed that in the normalretina, there was hardly any MMP-9 expression. A few of positive cells appeared in RPE layer 6h afterlight exposure. The expression reached its peak 12h after light exposure and keep hyposiexpression. Ithappened to decrease progressively in 96h sub-group. The expression trendency of MMP-9 in EP groupis the same as the SL group, but decresed generally. Compared with the two group, there was statisticalsignificance(P＜0.01).(4)In the normal retina, caspase-3 was negative. We can see positive expression ofcaspase-3 protein which rasised progressively in every simple light-induced sub-group as time of ligheexposure was increased. The expression reached its peak 96h after light exposure. Compared with theinjury group, the expression of caspase-3 protein in the 96h EP subgroup was significantlylower(P＜0.01).【Conclusion】MMP-2 and MMP-9 which induced RPE cell apotosis at last may beinvolved in the mechanism of retina photic injury. We inferred that EPO protected retina fromapoptosis by inhibiting the increased expression of MMP-2,MMP-9 and caspase-3.