Matrix metalloproteinases in human diabetic and nondiabetic vitreous

Purpose: To compare matrix metalloproteinase (MMP) activities in human vitreous samples from patients with diabetic retinopathy (DR) and other vitreoretinal diseases, and to investigate the factors influencing the MMP activities in human DR vitreous samples. Methods: Thirty-one diabetic and 17 nondiabetic vitreous samples (from nine patients with macular holes and eight patients with epiretinal membranes) were examined. Samples collected at the time of pars plana vitrectomy were subjected to substrate zymography to conduct a quantitative analysis of MMP activity. Immunoblotting against antihuman MMP-1, 2, and 9 was performed to identify MMP in vitreous samples. The effects of posterior vitreous detachment (PVD), vitreous hemorrhage, proliferative membrane, traction detachment, and cystoid macular edema on MMP activities were investigated. Results: All vitreous samples from both DR and non-DR patients showed a single band at the position of 72 kD, corresponding to MMP-2. Another band at 99 kD, corresponding to MMP-9, was detected significantly more often in DR samples than in non-DR samples: 45.2% and 0%, respectively (P = 0.0007). The number of samples showing a band from MMP-9 was significantly higher in partial PVD samples than in complete PVD samples: 66.7% and 15.4%, respectively (P = 0.001). Conclusion: The results indicated that MMP-9 may be involved in DR and that partial PVD may be related to the MMP-9 activity in DR.