Abstract
Abstract: :
Purpose: To determine expression and localization of matrix metalloproteinases (MMPs) in epiretinal membranes from proliferative vitreoretinopathy (PVR). Methods: 32 fibrocellular membranes obtained from eyes undergoing vitreoretinal surgery for PVR (stage III or worse) were collected in a balanced salt solution. The membranes specimens were embedded in OCT compound, rapidly frozen in liquid nitrogen. Specimens were serially sectioned on a cryostat at 6-mm and placed on glass slides. Immunohistochemical staining was then performed with antibodies to selected MMPs, including MMP-1, MMP-2, MMP-3, and MMP-9. Subsequent workup used biotinylated secondary antibodies and AEC as chromogen according to standard protocol. The positive cells were identified by double staining with cytokeratin (for RPE), anti-smooth muscle actin (for myofibrablasts), and glial fibrillary acidic protein (for glial cells) using peroxidase and alkaline phosphatase detection system. The sections were viewed at 400 X magnification. Results: 27 of 32 membranes stained positively for MMP-1, with 25 exhibiting moderate to strong staining. MMP-2 and MMP-3 were both less prevalent than MMP-1 in the PVR membranes. MMP-9 was found to be present in only 6 specimens. Double labeled results indicate codistribution of MMPs, and in particular MMP-1, with cytokeratin within PVR membranes. MMP-1 was also found to co-localise with SMA in 1 out of 10 membranes. MMP-2 showed co-localised staining with cytokeratin in 1 out of 6 specimens, as did MMP-9 with cytokeratin. Conclusion: This is the first study to indicate the colocalization of MMP-1 with cytokeratin, and suggests a possible relationship between MMP-1 and RPE cells in PVR. Supported by CIHR.
Keywords: 524 proliferative vitreoretinopathy • 403 extracellular matrix • 474 microscopy: light/fluorescence/immunohistochemistry