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Kousuke Noda, Susumu Ishida, Makoto Inoue, Ken-ichi Obata, Yoshihisa Oguchi, Yasunori Okada, Eiji Ikeda; Production and Activation of Matrix Metalloproteinase-2 in Proliferative Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2003;44(5):2163-2170. doi: 10.1167/iovs.02-0662.
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purpose. To investigate the matrix metalloproteinase (MMP) species and their activation associated with the pathogenesis of proliferative diabetic retinopathy (PDR).
methods. Sandwich enzyme immunoassays were used to measure concentrations of MMP-1, -2, -3, -7, -8, -9, and -13 in vitreous samples from patients with PDR and nondiabetic vitreoretinal diseases. To evaluate activation ratios of the zymogen of MMP-2 (proMMP-2) and -9 (proMMP-9) in the vitreous samples and fibrovascular tissues, gelatin zymography was performed. Production and tissue localization of MMP-2, membrane type 1-MMP (MT1-MMP), tissue inhibitor of metalloproteinases (TIMP)-2, and MMP-9 in the fibrovascular tissues were examined by immunohistochemistry. mRNA expression of MT1-MMP in the tissues was determined by reverse transcription–polymerase chain reaction (RT-PCR).
results. Among the seven different MMPs examined in the vitreous samples, only the levels of MMP-2 and -9 were significantly higher in the PDR samples than in the control. However, activation ratios of proMMP-2 (10.6% ± 11.8%) and proMMP-9 (2.5% ± 5.1%) in PDR vitreous samples were low and not significantly different from those of the control. In contrast, high activation ratios of proMMP-2 (54.3% ± 13.6%) and notable activation of proMMP-9 (19.5% ± 7.8%) were observed in the fibrovascular tissues. Immunohistochemical study demonstrated the localization of MMP-2 and -9 in the endothelial cells and glial cells of the fibrovascular tissues. MMP-2 was colocalized with MT1-MMP and TIMP-2, which are an activator and an activation-enhancing factor, respectively, for proMMP-2. RT-PCR analysis indicated the gene expression of MT1-MMP in the tissues.
conclusions. These data demonstrate that proMMP-2 is efficiently activated in the fibrovascular tissues of PDR, probably through interaction with MT1-MMP and TIMP-2, and suggest the possibility that the activity of MMP-2 and MT1-MMP is involved in the formation of the fibrovascular tissues.
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