Abstract
Purpose: :
Diabetic retinopathy (DR) is a leading cause of blindness in the developed countries. Retinal vascular leakage and chronic inflammation are common complications in diabetic retinopathy. Our previous studies showed that plasminogen kringle 5 (K5), a fragment of plasminogen, inhibits retinal neovascularization and reduces retinal vascular leakage. Present study is to test if long term K5 expression, from nanoparticles and adenovirus expressing the K5 gene, in the retina reduce chronic inflammation and retinal vascular leakage in a type I diabetic model and ischemia induced retinopathy.
Methods: :
An expression plasmid of K5 was encapsulated with poly lactide-co-glycolide (PLGA) to form K5 nanoparticles (K5-NP). Expression and secretion of K5 were detected in 293A cells transfected with K5-NP and Ad-K5, but not in the cells treated with Control-NP and Ad-GFP. Pro-inflammation factors, such as TNF-alpha, Cox2, VEGF and ICAM-1 in BRCEC under hypoxia were measured using ELISA kit and Western blot analysis. To determine its effect in vivo, K5-NP or Ad-K5 was intra-vitreously injected into the left eye of rats with oxygen-induced retinopathy (OIR), a commonly used model of retinal neovascularization, and the same titer of Control-NP or Ad-GFP was into the right eye. The retinal vascular permeability was performed using Evens blue permeability assay as described previously, and the productions of pro-inflammation factors in the retinas were determined using ELISA and Western blotting analysis.
Results: :
K5-NP and Ad-K5 significantly down-regulates expression of TNF-alpha, Cox2, VEGF and ICAM-1 in BRCEC under hypoxia. Intravitreal injection of K5-NP or Ad-K5 significant reduced retinal vascular leakage and the production of pro-inflammation factors, when compared to the contralateral eyes injected with Control-NP or Ad-GFP. The injection of K5-NP and Ad-K5 also decreased inflammatory factors in the retina of OIR rats.
Keywords: diabetic retinopathy • inflammation • retina