Anti-inflammatory effects of EGCG or EGCG3Me against hyperosmotic-induced inflammation in humans conjunctival epithelial cells.

Abstract

Purpose: Osmotic pressure of the tear in dry-eye patient is usually higher than that in normal people. The cause of dry-eye is reported as two factors; reduction of the tear volume, and destabilization of the tear film. Reduction of the tear raise the osmotic pressure of the tear, and cause inflammation on surface of eyes. And if goblet cell injured, production of mucin will lead to destabilization of the tear film and further reduction of tear. That is a vicious circle in dry-eye patient. Recently, It have reported that the tea caetichin ,especially, (-)-Epigallocatechin Gallate (EGCG) and (-)-Epigallocatekin 3-(3"-O-Methyl)Gallate (EGCG3Me) have numerous bioactivity, for example, antiallery, anti-inflammation, and anticancer activity. We used human conjunctival epithelium cell (HCE cell) to elucidate how hyperosmolarity induced inflammation , and reveal the anti-inflammatory action of catechin.

Methods: We cultivated HCE cells in 2mM glutamine + 1% penicillin streptomycin + 10% Fetal Bovine serum Medium199 with FBS in 5% CO₂、37℃ environment. HCE cells were exposed to hyperosmotic medium (440mOsm i.e. 123mM sucrose in medium) or were maintained in isosmotic medium (289mOsm). We determined the rate of apoptotic cells and IL-6 level during 1 to 24 hours after applying hyperosmotic stress. Moreover, hyperosmotic stress 1 hour before treatment of EGCG and EGCG3Me, and exposed to hyperosmotic stress, we measured p38 MAPK and phosphorylation of IL-6 level 1 hour later.

Results: Both the rate of apoptotic cells and the IL-6 level elevated with time after applying hyperosmotic stress. For this inflammation, EGCG3Me significantly inhibited increase of the IL-6 level and phosphorylated p38 MAPK than EGCG.

Conclusions: Hyperosmotic stress to HCE cells induce apoptosis and inflammation with p38MAPK. For this inflammation, EGCG and EGCG3Me significantly showed anti-inflammatory action particularly effects of EGCG3Me were strong. These findings suggested that EGCG3Me might be useable as one of therapeutic approaches of dry eyes.