Pigment epithelium-derived factor inhibits advanced glycation end products-induced retinal vascular permeability

Vascular hyperpermeability associated with retinal vascular leakage is known to occur in patients with diabetes, and contributes to endothelial barrier dysfunction. This study aimed to examine the effect of pigment epithelium-derived factor (PEDF) on advanced glycation end products (AGEs)-induced endothelial cell permeability. Cultured porcine retinal endothelial cell (PREC) was exposed to AGE-modified bovine serum albumin (AGE-BSA) and the endothelial cell permeability was detected by measuring the flux of rhodamine B isothiocyanate (RITC)-dextran across the PREC monolayers. We found that AGE-BSA increased the RITC-dextran flux across a PREC monolayer and PEDF blocked the solute flux induced by AGE-BSA. In order to explore the underlying signaling mechanism of PEDF on the inhibitory effect of AGE-BSA-induced permeability, we demonstrate that PEDF could inhibit the AGE-BSA-induced permeability via phosphatidylinositol 3-kinase (PI3K)/Akt pathway. AGE-BSA also increased the endothelial cell permeability by stimulating the reactive oxygen species (ROS) generation via NADPH oxidase activity and Akt phosphorylation at Ser473. PEDF decreased ROS generation in AGE-BSA-exposed endothelial cells by suppressing the NADPH oxidase activity via down regulating the phosphorylation of p22PHOx at Thr147. This led to blockade of AGE-induction of PI3K/Akt activation in permeability. Furthermore, PEDF inhibited the AGE-BSA-induced permeability by increased expression of tight junction protein zona occludens-1(ZO-1), co-incident with an increase in barrier properties of endothelial monolayer. Together, our results indicate that PEDF could possibly act as potent anti-permeability molecule by targeting the PI3K/Akt signaling pathway by suppressing if NADPH oxidase mediated ROS generation and ZO-1 tight junction protein and it offers potential targets to inhibit the ocular related diseases such as diabetic retinopathy.