Abstract
Purpose: :
Retinal pigment epithelial (RPE) cells are inolved in age-related macular degeneration, but their role in diabetic retinopathy has been little studied. Oxidative stress and inflammation have been demonstrated in both conditions. The purpose of the present study was thus to evaluate the mRNA expression of antioxidative enzymes and inflammatory mediators in human RPE cells exposed to hyperglycemia.
Methods: :
Human RPE cells from the ARPE-19 cell line were exposed to 5mM or 20 mM glucose for 2 h, 24 h or 5 days, and one group to 40 mM glucose for 5 days. 0.2% or 0.5% mannitol were added to the culture medium to ocmpensate for the osmotic effects of hyperglycemia. The mRNA expression of the antioxidative enzymes superoxide dismutase -1 (SOD-1), glutathione peroxidase- 1 (GPX-1), catalytic subunit of glytamyl cystein ligase (CGLc) and catalase, as well as the inflammatory mediators tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), vascular cellular adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1) were analyzed with real-time RT-PCR and related to the endogenous control cyclophilin B.
Results: :
Hyperglycemia for 24 h increased the expressions of GPX-1 (6.6-fold, p=0.009) and ICAM-1 (6.1-fold, p=0.041). VCAM-1 expression was not detectable in any group, and the expression of TNF-α were varying and inconsistent. Exposure for 2 h or 5 days did not result in any expression differences.
Keywords: diabetic retinopathy • retinal pigment epithelium • inflammation