Abstract
Purpose: :
Diabetic retinopathy (DR) and nephropathy are major microvascular complications in patients with diabetes, and they are considered to be related. Pigment epithelium-derived factor (PEDF) is a strong inhibitor of angiogenesis, and earlier studies showed that PEDF was significantly elevated in the blood of diabetic patients especially those with proliferative diabetic retinopathy (PDR). The level of PEDF in the blood, on the other hand, was reported to be low in an animal model of diabetic nephropathy. The aim of this study was to determine the relationship between PEDF in the blood and renal function in patients with DR.
Methods: :
A total of 243 type 2 diabetic patients were studied. The relationship between the DR and the levels of PEDF in the blood, HbA1c, blood urea nitrogen (BUN), and creatinine were evaluated. The plasma level of PEDF was measured by ELISA, and the stage of DR was determined by ophthalmic examinations. The data were analyzed statistically by one way analysis of variance (ANOVA) with Fisher’s PSLD test and Pearson's product moment correlation coefficient (r).
Results: :
The mean plasma PEDF level in patients with PDR (7.69 ± 6.14 µg/ml; means ± standard error) was significantly higher than that of mild to moderate nonproliferative DR (M-NPDR) (5.07 ± 4.37 µg/ml, P = 0.02). The level of BUN and creatinine increased as the stage of DR advanced. The level of BUN in the PDR group (27.1 ± 2.5 mg/dl) was significantly higher than that in the no apparent DR (NDR) (15.6 ± 1.0 mg/dl), M-NPDR (18.5 ± 1.1 mg/dl), and the severe nonproliferative DR (S-NPDR) groups (19.9 ± 0.9 mg/dl, P = 0.002, P = 0.01, P = 0.003, respectively). The level of creatine in the PDR (1.94 ± 0.30 mg/dl) group was significantly higher than that in NDR (0.69 ± 0.06 mg/dl), M-NPDR (0.71 ± 0.06 mg/dl), and S-NPDR (1.01 ±0.19 mg/dl, P = 0.01, P = 0.005, P = 0.008, respectively) groups. The plasma PEDF levels were significantly correlated with the levels of BUN and creatinine (r = 0.54, P < 0.0001; r = 0.57, P < 0.0001, respectively).
Conclusions: :
The levels of plasma PEDF increases with advances in both DR and nephropathy. Thus, increased levels of PEDF in the blood may indicate microvascular damages in diabetic patients and may be a predictor of the progression of retinopathy and nephropathy.
Keywords: diabetic retinopathy • diabetes • growth factors/growth factor receptors