Abstract
Purpose :
Homocysteine (Hcy) is a sulfur-containing amino acid which has been reported to be elevated in plasma, vitreous and aqueous of patients with diabetic retinopathy (DR). This study is aiming to investigate the potential role of Hcy in DR via alteration of retinal endothelial cells barrier function and enhancing their angiogenic potential.
Methods :
ELISA kit has been used to measure Hcy levels in the vitreous of patients with DR and in the blood of animal models of type 1 diabetes (akita mice and streptozocin injected mice & rats) and in db/db mice as a model of type 2 diabetes. Human retinal endothelial cells (HRECs) treated for 24 hours with and without Hcy (20, 50, 100 µM) were evaluated for blood retinal barrier integrity by FITC–Dextran flux permeability assay, Electric Cell-substrate Impedance Sensing (ECIS) to measure the transelectrical resistance (TER) as well as evaluation of the level and organization of tight junction proteins, ZO-1 and occludin by Western blot and immunofluorescence (IF). Furthermore, angiogenic potential of HRECs was evaluated by tube formation assay.
Results :
Hcy was significantly elevated in human patients and in all animal models of diabetes. Hcy incapacitated the barrier function and enhanced angiogenesis in HRECs as evinced by increased leakage in Hcy treated HRECs in FITC-dextran permeability assay, decreased TER, down-regulation of tight junction proteins as well as induction of tube formation in Hcy-treated HRECs.
Conclusions :
Our data suggest the involvement of Hcy in the development and/or the progression of DR. Therefore, elimination of excess Hcy might provide a potential therapeutic avenue to prevent microvascular dysfunction associated with DR.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.