Abstract
Purpose:
Methylglyoxal (MG) is the intermediate product of glycation and is the precursor of advanced glycation endproducts (AGEs). MG itself and its metabolic products play a role in the pathogenesis of age-related macular degeneration (AMD) and diabetic retinopathy. Urokinase-type plasminogen activator (uPA) is a protease involved in tissue remodeling and angiogenesis. The present study investigated the effects of subtoxic levels of MG on the production of uPA by cultured human retinal pigment epithelial cells (RPE).
Methods:
The toxic effects of MG on human RPE cell viability were tested using the MTT test. The effects of subtoxic levels of MG on the production of uPA were tested by an ELISA method. Cells were seeded into multi-well plates. MG was added to the medium at 1-100 μM and cultured for 24 hr. Conditioned medium was collected. uPA in the conditioned medium was measured using an uPA ELISA kit. Cells cultured without MG were used as negative controls. All groups were tested in triplicate, and the results were analyzed by one-way ANOVA test.
Results:
MG at 1-100 μM did not influence cell viability of cultured RPE cells. Cultured human RPE cells (ARPE19) showed a low level of constitutive production of uPA (18.3 pg/ml). MG stimulated the production of uPA in a dose-dependent manner. uPA levels in conditioned medium from cells cultured with MG at 1, 10 and 100 µM was 1.12-, 1.47-, and 1.88-fold of that in the controls, respectively (P < 0.05 in 10 and 100 µM groups). Studies in a primary culture of human RPE cells revealed a similar result.
Conclusions:
MG-induced production of uPA in RPE cells may play a role in the neovascularization process in proliferative diabetic retinopathy and wet AMD. Various anti-uPA agents may be useful for inhibition of angiogenesis in these eye diseases.
Keywords: 412 age-related macular degeneration •
499 diabetic retinopathy •
701 retinal pigment epithelium