Abstract
Purpose :
Diabetic retinopathy (DR) is a leading cause of preventable blindness in developed countries. Breakdown of the blood retinal barrier (BRB) leads to macular edema and is one of the earliest events in the development of DR. Previous work from our laboratory suggest that hyperinsulinemia (as seen in type 2 diabetes) may lead to disruption of the outer BRB. The purpose of this study is to explore the effect of hyperglycemia/hyperinsulinemia on the permeability and expression of tight junction proteins (claudin 19, claudin 10, zonula occludens-1 (ZO-1) in primary porcine retinal pigment epithelial (RPE) cells. The proposed study will provide a better understanding of the molecular mechanisms involved in the breakdown of the BRB in DR.
Methods :
Impedance spectroscopy was used to evaluate the transepithelial electrical resistance (TEER) as well as capacitance of primary porcine RPE cells grown in media containing 5 mM D-glucose (mimicking physiological conditions) or 25 mM D-glucose (mimicking high glucose as seen in diabetic patients). Once cells reached confluence, the effect of exposure to 100 nM insulin over 2 weeks was evaluated. Expression of tight junction proteins were evaluated by western blotting and the spatial localization of these proteins was evaluated by immunofluorescence.
Results :
RPE cells cultured in physiological glucose (5mM) had a lower TEER compared to RPE cells cultured in high glucose (25mM). Insulin induced a significant decrease in TEER in RPE cells only in high glucose (25mM) conditions with no effect on cells cultured in physiological glucose media.
Conclusions :
These data suggests that high levels of insulin can induce BRB breakdown under hyperglycemic conditions and may have implications for the development of DR in type 2 diabetes.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.