Abstract
Purpose: :
Oxidative stress is considered a major contributing factor to a variety of eye diseases. Retinal pigment epithelium (RPE) represents a key tissue that prevents oxidative stress induced retinal diseases. It has been shown to be more resistant against oxidative stress than other ocular tissues. The main cytosolic factor that triggers the cells transscriptional response to oxidavtive stress is nucleotid related factor E2 related factor 2 (Nrf2). Thus a transgenic mouse model with a double knock out (KO) of Nrf2 seems to be promising for research on oxidative stress in the eye. However, the antioxidant stress resistance of PRE-cells differs depending on the species from which they are obtained.
Methods: :
Primary retinal pigment epithelial cell cultures from pig, Nrf2-knock-out mice and wild type (WT) mice were exposed to tert-butyl hydroperoxid (tBH)-induced oxidative stress. TBH concentrations of 100, 250 and 500µM were examined. Cell survival was measured by MTT essay.
Results: :
Nrf2-KO RPE cells were most susceptible against oxidative stress andexhibited profound cell death at a concentration of 100 µM, compared to WT cells which showed cell death from a concentration of 250 µM. Most resistant against tBH-induced cell death were porcine RPE cells which exhibited profound cell death at a concentration of 500 µM, but not 250 µM. Moreover, cell death induced by tBH could be dimished by the inhibition of the Erk-pathway by U0126 in porcine, but not in wildtyp murine cells.
Conclusions: :
Nrf2-KO RPE cells from mice are more susceptible against oxidative stress than RPE cells from their littermates. These, however, are less resistant than porcine RPE cells, which are reported to have a comparable oxidative stress resistance to the human RPE-cell line ARPE19. Also, the stress pathway seems to differ beween the species. This has to be taken into consideration when drawing conclusions about human pathophysiology from RPE cell cultures taken from other species.
Keywords: retinal pigment epithelium • cell survival • oxidation/oxidative or free radical damage