Production and activation of matrix metalloproteinase-2 in proliferative diabetic retinopathy

Invest Ophthalmol Vis Sci. 2003 May;44(5):2163-70. doi: 10.1167/iovs.02-0662.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Diabetic Retinopathy / enzymology*
  • Endothelium, Vascular / enzymology
  • Enzyme Activation
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunoenzyme Techniques
  • Male
  • Matrix Metalloproteinase 2 / metabolism*
  • Matrix Metalloproteinase 9 / metabolism
  • Matrix Metalloproteinases, Membrane-Associated
  • Metalloendopeptidases / genetics
  • Middle Aged
  • Neuroglia / enzymology
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tissue Inhibitor of Metalloproteinase-2 / metabolism
  • Vitreoretinopathy, Proliferative / enzymology*
  • Vitreous Body / enzymology*

Substances

  • RNA, Messenger
  • Tissue Inhibitor of Metalloproteinase-2
  • Matrix Metalloproteinases, Membrane-Associated
  • Metalloendopeptidases
  • Matrix Metalloproteinase 2
  • Matrix Metalloproteinase 9