Matrix metalloproteinases and metalloproteinase inhibitors in human interphotoreceptor matrix and vitreous

Purpose. We wished to establish which matrix metalloproteinases (MMPs) and metalloproteinase inhibitors (TIMPs) were present in human interphotoreceptor matrix (IPM) and vitreous. Methods. IPM and vitreous were obtained from postmortem human eyebank eyes. Western immunoblots were probed with antibodies against human MMPs and TIMPs. Assays specific for elastase activity were also performed. Results. Immunoblot analysis indicated the presence of MMP-1 (interstitial collagenase), MMP-2 and MMP-9 (gelatinases A and B), MMP-3 (stromelysin-1) and TIMP-1, -2 and -3 in both IPM and vitreous. MMP-7 (matrilysin) and MMP-12 (metalloelastase) were not found in either LPM or vitreous. Conclusions. This is the first demonstration of the MMPs and TIMPs in human IPM and of the TIMPs in human vitreous. While these enzymes are most likely involved in normal turnover within the extracellular matrices that surround the neural retina, they may also play a role in a number of retinal diseases, particularly proliferative diabetic retinopathy and age-related macular degeneration.