MMP-2、TIMP-2与碱烧伤后角膜新生血管形成的实验研究

The experimental study on MMP-2 and TIMP-2 in corneal neovascularization of rats after alkali burn

目的:探讨基质金属蛋白酶-2(MMP-2)、基质金属蛋白酶-2组织型抑制剂(TIMP-2)在碱烧伤大鼠角膜新生血管(CNV)形成中的表达和意义。方法:采用碱烧伤大鼠角膜建立CNV模型,摘除角膜作病理切片,多形核白细胞(PMN)记数;免疫组化法检测MMP-2、TIMP-2的表达。结果:烧伤后1d角膜缘PMN开始增多,到CNV7d组PMN增加最明显,此后逐渐减少;免疫组化显示:MMP-2在CNV中阳性表达逐渐增加,于7d表达最明显,此后随炎性细胞的减少而减弱,21d后几乎无表达;TIMP-2则于早期变化不明显,7d表达开始升高,14d达高峰。结论:烧伤后CNV形成早期,MMP-2活性增高,继而TIMP-2表达增加,使MMP-2活性受抑,基底膜降解受阻,新生血管延伸停滞;CNV形成中,MMP-2的表达增加,并与角膜的炎性反应程度一致,PMN浸润可能是CNV形成的关键因素。

Objective:To study the expressions of matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in corneal neovascularization (CNV). Methods: Corneal neovascularization was induced by NaOH cauterizing the surface of cornea in 40 rats. The corneas were enucleated for histopathological examination; Polymorphonuclear leukocyte (PMN) was counted; The expressions of MMP-2 and TIMP-2 were studied by immunohistochemistry. Results:The histopathological study showed the number of PMNs increased gradually and was the highest in CNV 7d group and began to decrease after 7th day; Immunohistochemistry demonstrated: the positive expression of MMP-2 in CNV progressed gradually, and involved the entire cornea on the 7th day post-treatment. After 7 days the expression decreased following the decrease of inflammatory cells, and 21 days post treatment the positive expression was not found. However, the changes of TIMP-2 were not obvious in the early phase, and the expression of TIMP-2 tended to greatly increase on the 7th day, and reach the highest on the 14th day. Conclusions:The activity of MMP-2 increases in the early stage of rats CNV model, then is inhibited by the increased expression of TIMP-2, the degradation of ECM is disrupted,and CNV is stopped; With the development of CNV, the expressions of MMP-2 is paralleled with the corneal inflammatory reaction. Furthermore,PMNs may play key roles in CNV.