Anti-inflammatory and anti-oxidative effects of the green tea polyphenol epigallocatechin gallate in human corneal epithelial cells

Mol Vis. 2011 Feb 18;17:533-42.

Abstract

Purpose: 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.

MeSH terms

  • Anti-Inflammatory Agents / pharmacology*
  • Antioxidants / pharmacology*
  • Catechin / analogs & derivatives*
  • Catechin / pharmacology
  • Cytokines / metabolism
  • Enzyme Activation / drug effects
  • Epithelial Cells / drug effects*
  • Epithelial Cells / enzymology
  • Epithelium, Corneal / cytology*
  • Flavonoids / pharmacology*
  • Glucose Oxidase / metabolism
  • Humans
  • Interleukin-1beta / pharmacology
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / metabolism
  • Osmotic Pressure / drug effects
  • Phenols / pharmacology*
  • Phosphorylation / drug effects
  • Polyphenols
  • Reactive Oxygen Species / metabolism
  • Tea / chemistry*
  • Transcription Factor AP-1 / metabolism
  • Transcriptional Activation / drug effects
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • Anti-Inflammatory Agents
  • Antioxidants
  • Cytokines
  • Flavonoids
  • Interleukin-1beta
  • NF-kappa B
  • Phenols
  • Polyphenols
  • Reactive Oxygen Species
  • Tea
  • Transcription Factor AP-1
  • Catechin
  • epigallocatechin gallate
  • Glucose Oxidase
  • JNK Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases