title: Lutein protects retinal pigment epithelium from cytotoxic oxidative stress.
abstract: BACKGROUND
  Lutein (LUT) and zeaxanthin (ZEA) are currently under investigation in clinical trials as prophylactic nutritional agents for age-related macular degeneration (AMD). However, dose used in these trials is empirical and not been investigated in in vitro studies.
  
  
  OBJECTIVE
  In this study, we investigated the dose-response effect of LUT and ZEA in protecting retinal pigment epithelium (RPE) from oxidative stress, a common underlying pathology in AMD.
  
  
  METHODS
  Three thousand cultured human retinal pigment epithelial cells (ARPE-19) were plated in 72-well plate and after 24 h were exposed to increasing concentrations of hydrogen peroxide (H2O2). ARPE-19 cells were exposed to four different concentrations of LUT (0.5, 1, 2 and 4 µg/mL) and ZEA (0.1, 0.2, 0.4 and 0.8 µg/mL). After 24 h incubation, cells were subjected to oxidative stress induced with H2O2. Cultures containing saline solution and dichloromethane served as controls. Cell viability was assessed using the WST-1 assay. Pathophysiological pathways were evaluated by measuring caspase-3 levels as an indicator of apoptosis induction. Reactive oxygen species (ROS) levels were measured using dihydrorhodamine-123.
  
  
  RESULTS
  Cell viability as a percentage of control was 81.3%, 81.1%, and 88.8% at 0.5, 1, and 2 µg/ml, respectively of LUT (p < 0.001). The maximum cytoprotective effect was seen with LUT at 2 μg/mL. ZEA did not show any cytoprotective effect at all concentrations used in the study. Caspase-3 showed a corresponding decrease in levels with LUT (1 and 2 µg/ml). Significant decrease in ROS levels were measured only with LUT at 4 µg/ml (p = 0.02).
  
  
  CONCLUSIONS
  Results from our study provide in vitro data to support the epidemiologic studies, which are currently underway to provide evidence that lutein may act as cofactor that modulates processes implicated in AMD pathogenesis.
authors.affiliation: Department of Ophthalmology, University of Florida-College of Medicine , Jacksonville, FL , USA and.
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Murthy
authors.forename: Kavitha
authors.initials: K
authors.lastname: Ravi
authors.forename: Sankarathi
authors.initials: S
authors.lastname: Balaiya
authors.forename: Vikram S
authors.initials: VS
authors.lastname: Brar
authors.forename: Kakarla V
authors.initials: KV
authors.lastname: Chalam
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006801:Humans; D006861:Hydrogen Peroxide; D014975:Lutein / Q000494:pharmacology*; D016877:Oxidants; D018384:Oxidative Stress / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D065146:Zeaxanthins / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D016877:Oxidants; D017382:Reactive Oxygen Species; D065146:Zeaxanthins; D006861:Hydrogen Peroxide; D053148:Caspase 3; D014975:Lutein
keywords: Carotenoids; macular degeneration; oxidative stress; retinal pigment epithelium