title: Anti-inflammatory and anti-oxidative effects of the green tea polyphenol epigallocatechin gallate in human corneal epithelial cells.
abstract: OBJECTIVE
  To determine the anti-inflammatory and anti-oxidant effects of epigallocatechin gallate (EGCG), the major polyphenol component of green tea, in human corneal epithelial cells (HCEpiC).
  
  
  METHODS
  HCEpiC were challenged with interleukin-1β (IL-1β) for 18 h or hyperosmolarity (440 mOsm) for 24 h. Luminex technology was used to determine the effects of EGCG (0.3-30 µM) on IL-1β- or hyperosmolar-induced cytokine release into the medium. Cell metabolic activity was measured using the alamarBlue assay. Effects of EGCG on mitogen-activated protein kinase (MAPK) phosphorylation were determined by cell-based enzyme-linked immunosorbent assay (ELISA) and western blotting. Effects of EGCG on nuclear factor kappa B (NFκB) and activator protein-1 (AP-1) transcriptional activity were assessed by reporter gene assay. The effects of EGCG on glucose oxidase (GO)-induced reactive oxygen species (ROS) production was determined using the ROS probe CM-H₂DCFDA.
  
  
  RESULTS
  Treatment of HCEpiC with 1 ng/ml IL-1β for 18 h significantly increased release of the cytokines/chemokines granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1), while hyperosmolarity-induced release of IL-6 and MCP-1. When cells were treated with IL-1β and EGCG or hyperosmolarity and EGCG there was a dose-dependent reduction in release of these cytokines/chemokines, with significant inhibition observed at 3-30 µM. There was no effect of EGCG on cell metabolic activity at any of the doses tested (0.3-30 µM). EGCG significantly inhibited phosphorylation of the MAPKs p38 and c-Jun N-terminal kinase (JNK), and NFκB and AP-1 transcriptional activities. There was a significant dose-dependent decrease in GO-induced ROS levels after treatment of HCEpiC with EGCG.
  
  
  CONCLUSIONS
  EGCG acts as an anti-inflammatory and anti-oxidant agent in HCEpiC and therefore may have therapeutic potential for ocular inflammatory conditions such as dry eye.
authors.affiliation: Global Pharmaceutical R&D, Bausch + Lomb, Rochester, NY 14609, USA. Megan.Cavet@bausch.com
authors.forename: Megan E
authors.initials: ME
authors.lastname: Cavet
authors.forename: Karen L
authors.initials: KL
authors.lastname: Harrington
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Vollmer
authors.forename: Keith W
authors.initials: KW
authors.lastname: Ward
authors.forename: Jin-Zhong
authors.initials: JZ
authors.lastname: Zhang
mesh_terms: D000893:Anti-Inflammatory Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology; D019573:Epithelium, Corneal / Q000166:cytology*; D005419:Flavonoids / Q000494:pharmacology*; D005949:Glucose Oxidase / Q000378:metabolism; D006801:Humans; D053583:Interleukin-1beta / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009997:Osmotic Pressure / Q000187:drug effects; D010636:Phenols / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D059808:Polyphenols; D017382:Reactive Oxygen Species / Q000378:metabolism; D013662:Tea / Q000737:chemistry*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D016207:Cytokines; D005419:Flavonoids; D053583:Interleukin-1beta; D016328:NF-kappa B; D010636:Phenols; D059808:Polyphenols; D017382:Reactive Oxygen Species; D013662:Tea; D018808:Transcription Factor AP-1; D002392:Catechin; C045651:epigallocatechin gallate; D005949:Glucose Oxidase; D048031:JNK Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases