Proteinases in subretinal fluid

Background: Degradation of the extracellular matrix by secreted proteases is connected to cell migration and proliferation in invasive growth and in scar tissue formation. In retinal detachment, retinal pigment epithelium (RPE) cells loosened from their monolayer are often seen in the subretinal fluid (SRF) and the vitreous, where they may participate in the scar tissue formation of proliferative vitreoretinopathy. To evaluate the role of SRF constituents on the release of RPE cells, we analyzed SRF in patients with retinal detachment for the presence of enzymes able to degrade extracellular matrix. Methods: SRF was collected altogether from 16 patients undergoing retinal reattachment surgery and analyzed for activities against some of the key enzymes in extracellular proteolysis, namely collagenases, gelatinases, elastase and cathepsin G. Results: Seventy-two-kilodalton gelatinase was found in all SRF samples studied, whereas the neurophil-type 92-kDa gelatinase could not be detected. Low collagenase, elastase and cathepsin G activities could also be detected in some samples. Conclusions: The predominant type of matrix metalloproteinase present in SRF is the 72-kDa MMP-2. The proteolytic activity in SRF may be connected to the release of RPE cells into SRF and to degradation of components of the vitreous exposed to SRF.