Vitreous levels of vascular cell adhesion molecule and vascular endothelial growth factor in patients with proliferative diabetic retinopathy - A case-control study

OBJECTIVE - To evaluate the intravitreous concentration of vascular cell ad hesion molecule (VCAM)-1 in diabetic patients with proliferative diabetic r etinopathy (PDR) and the relationship of VCAM-1 with vascular endothelial g rowth factor (VEGF). RESEARCH DESIGN AND METHODS - Serum and vitreous fluid samples were obtaine d simultaneously at the onset of vitrectomy from 20 diabetic patients with PDR and 20 nondiabetic control subjects with nonproliferative ocular diseas e. Both groups were matched by serum levels of VCAM-1 and VEGF. VCAM-1 and VEGF were determined bq enzyme-linked immunosorbent assay. Statistics were determined using the Mann-Whitney U test and Spearman's rank correlation te st. RESULTS - The intravitreous concentration of VCAM-1 was significantly eleva ted in diabetic patients with PDR compared with control subjects (26 ng/ml [19-118] vs. 22 ng/ml [20-47], P < 0.05). A direct correlation between VCAM -1 and total citreous proteins was detected in diabetic patients (r = 0.64, P = 0.003), but not in control subjects. After adjusting for total intravi treous proteins, VCAM-1 was significantly lower in diabetic patients with P DR than in control subjects (8.2 ng/ml [4-31.4] vs. 43.1 ng/ml [9.7-100], P < 0.001). Intravitreous VEGF concentrations were higher in patients with P DR than in control subjects in absolute terms (1.34 ng/ml [0.16-6.22] vs. 0 .009 ng/ml [0.009-0.044], P < 0.0001) and after correcting for total vitrea l proteins (0.33 ng/ml [0.01-2.3] vs. 0.013 ng/ml [0.003-0.035], P = 0.0001 ). Finally, the vitreous ratio of VCAM-1 to proteins correlated with the vi treous ratio of VEGF to proteins in both diabetic patients (r = 0.74, P = 0 .001) and control subjects (r = 0.84, P = 0.005). CONCLUSIONS - The low proportion of VCAM-1 in relation to total vitreal pro teins observed in diabetic patients with PDR suggests that VCAM-1 is quench ed by diabetic retina. In addition, the direct correlation detected between VCAM-1 and VEGF suggests that cellular adhesion and neovascularization may be linked processes.