Erythropoietin Protects Retinal Pigment Epithelium in Experimental Diabetic Retinopathy

Abstract

Purpose : This study was to explore the possible protective mechanism(s) of EPO on retinal pigment epithelial cells (RPE) in diabetic rat retinas.

Methods : The Sprague-Dawley rats were rendered diabetes with intraperitoneal injection of streptozotocin, followed by intravitreal injection of EPO after 2 hours; 2 and 4 weeks later, the permeability of outer blood-retinal barrier was examined by using FITC-dextran leakage assay. The glyoxal-treated ARPE-19 cells, incubated with EPO or soluble EPO receptor, were studied for cell viability, barrier function, etc. The expressions of ZO-1, occludin, VEGFR2, HIF-1α, MAPKs and AKT were examined with Western blot and immunofluorescence.

Results : The leakage of FITC-dextran was detected mainly in outer nuclear layer in 2-week diabetic rat retinas and became more obvious in 4-week diabetic rat retinas. The leakage was largely ameliorated in EPO-treated diabetic rats. The protein expressions of ZO-1 and occludin in the RPE-Bruch’s membrane choriocapillaris complex were decreased, while HIF-1α and JNK pathways were increased, significantly in 4-week diabetic rats, which were reversed by EPO treatment. The in vitro study with ARPE-19 cells also confirmed above changes and the protective effect of EPO.

Conclusions : EPO could protect RPE cells and maintain its barrier integrity through upregulation of ZO-1 and occludin in diabetic rats. The protective mechanism(s) of EPO might be through its downregulation of HIF-1α and JNK pathways, thus protecting outer blood-retinal barrier.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.