Correlation Between Angiotensin-converting Enzyme, Vascular Endothelial Growth Factor, and Matrix Metalloproteinase-9 in the Vitreous of Eyes With Diabetic Retinopathy

To investigate the involvement of angiotensin-converting enzyme (ACE) with angiogenic factors, vascular endothelial growth factor (VEGF), and matrix metalloproteinase (MMP)-9 in the vitreous of eyes with proliferative diabetic retinopathy (PDR). Observational case series. Angiotensin-conerting enzyme activity in the vitreous was measured by using a synthetic substrate for ACE. VEGF and MMP-9 concentrations were determined by enzyme-linked immunosorbent assay. Vitreous ACE activity was significantly higher in eyes with PDR (1.4 ± 1.3 mU/ml) than in eyes with macular holes (0.22 ± 0.11 mU/ml). Vitreous VEGF concentration in the eyes with PDR (1067 ± 1076 pg/ml) was significantly higher than in eyes with macular holes (34 ± 5.5 pg/ml). Vitreous MMP-9 concentration was also significantly higher in eyes with PDR (7.5 ± 3.8 ng/ml) than in eyes with macular holes (4.2 ± 1.4 ng/ml). Significant correlations between ACE and VEGF ( P < .01) and between ACE and MMP-9 ( P < .01) were observed in the vitreous of eyes with PDR. Angiotensin-converting enzyme was significantly correlated with angiogenic factors, VEGF and MMP-9, in the vitreous of eyes with PDR.