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

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.

• Authors: Megan E Cavet, Karen L Harrington, Thomas R Vollmer, Keith W Ward, Jin-Zhong Zhang
• Journal: Molecular vision (Mol Vis) Vol. 17 Pg. 533-42 (Feb 18 2011) ISSN: 1090-0535 [Electronic] United States
• PMID: 21364905 (Publication Type: Journal Article)

Chemical References

• 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

Topics

• Anti-Inflammatory Agents (pharmacology)
• Antioxidants (pharmacology)
• Catechin (analogs & derivatives, pharmacology)
• Cytokines (metabolism)
• Enzyme Activation (drug effects)
• Epithelial Cells (drug effects, 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)