Abstract
Purpose: :
The aim of this study was 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 IL-1β for 18 hours. Cell metabolic activity was measured using the alamarBlue assay and Luminex technology was used to determine the effects of EGCG (0.3 - 30 µM) on IL-1β-induced cytokine release (G-CSF, GM-CSF, IL-6, IL-8, and MCP-1) into the medium. Effects of EGCG on mitogen-activated protein kinase (MAPK) phosphorylation were determined by cell based 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-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 G-CSF, GM-CSF, IL-6, IL-8 and MCP-1. When cells were treated with IL-1β 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). Both 3 and 30 µM EGCG significantly inhibited phosphorylation of the MAPKs p38 and 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 3, 10 or 30 µM EGCG.
Conclusions: :
EGCG acts as an anti-inflammatory and anti-oxidant agent in HCEpiC and therefore may have therapeutic potential for ocular inflamatory conditions such as dry eye.
Keywords: inflammation • cornea: epithelium • antioxidants