|Caceres, Maria Andrea|
|Ronchi, Carlos F.|
|Chen, C-y Oliver|
|Blumberg, Jeffery B.|
Submitted to: Molecular Vision
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2011
Publication Date: 12/7/2011
Citation: Gao, S., Qin, T., Liu, Z., Caceres, M., Ronchi, C., Chen, C., Yeum, K., Taylor, A., Blumberg, J., Liu, Y., Shang, F. 2011. Lutein and zeaxanthin supplementation reduces H202-induced oxidative damage in human lens epithelial cells. Molecular Vision. 17:3180-3190. Interpretive Summary: Oxidative damage to the eye lens is one of the major causes of cataract (loss of transparency of the lens). Any means that reduce oxidative damage to the lens may be a potential strategy for prevention of cataract, the leading cause of blindness in the elderly. In this study we investigated the effects of lutein and zeaxanthin, two related antioxidant nutrients on oxidative damage to lens protein, lipid and DNA using cultured lens cells as a model system. The data show that supplementation with lutein or zeaxanthin reduced the levels of oxidized proteins and oxidized lipids and fragmented DNA damage upon exposure to oxidative insults. The protective effects of lutein, zeaxanthin were comparable to that of vitamin E. These data indicate that lutein or zeaxanthin supplementation protects lens proteins, lipid and DNA from oxidative damage and improve intracellular antioxidant potentials, implying that sufficient intake of lutein and zeaxanthin may reduce the risk for cataract via protecting lens from oxidative damage.
Technical Abstract: Purpose: Epidemiological studies suggest that dietary intake of lutein and zeaxanthin is inversely related to the risk for senile cataract. The objectives of this work were to investigate the mechanisms by which these nutrients provide anti-cataract effects. We evaluated their modulation of oxidative damage in human lens epithelial cells (HLEC) and their interaction with intracellular glutathione (GSH). Methods: Subconfluent HLEC were pre-incubated with or without 5 uM lutein, zeaxanthin or alpha-tocopherol for 48 h and then exposed to 100 uM H2O2 for 1 h. Levels of protein carbonyls in the cells were measured by western-blotting analysis following reaction with 2,4-dinitrophenylhydrazine (DNPH). Levels of malondialdehyde (MDA), GSH and GSSG were measured by an HPLC system. DNA damage was assessed using comet assays. Cell viability was determined by MTS assay. Results: In the absence of H2O2, HLEC had very low levels of protein carbonyl and MDA. Supplementation with lutein, zeaxanthin or alpha-tocopherol to the unstressed HLEC had no detectable effects on levels of oxidized proteins and lipid in the cells. Exposure of HLEC to H2O2 significantly increased levels of oxidized proteins, lipid peroxidation and DNA damage. Pre-incubation with lutein, zeaxanthin or alpha-tocopherol dramatically reduced the levels of H2O2 -induced protein carbonyl, MDA and DNA damage in HLEC. The protective effects of lutein, zeaxanthin and alpha-tocopherol against protein oxidation, lipid peroxidation and DNA damage were comparable. Supplementation with lutein, zeaxanthin or alpha-tocopherol increased GSH levels and GSH:GSSG ratio, particularly in response to oxidative stress. Depletion of GSH resulted in significant increase in susceptibility to H2O2-induced cell death. Supplementation with alpha-tocopherol, but not lutein or zeaxanthin, can partially restore the resistance of GSH-depleted cells to H2O2. Conclusions: These data indicate that lutein or zeaxanthin supplementation protects lens protein, lipid and DNA from oxidative damage and improves intracellular redox status upon oxidative stress. The protective effects are comparable to that of alpha-tocopherol, except that lutein and zeaxanthin cannot compensate for GSH depletion. The data imply that sufficient intake of lutein and zeaxanthin may reduce the risk for senile cataract via protecting the lens from oxidative damage.