Blueberry Component Pterostilbene Protects Corneal Epithelial Cells from Inflammatory and oxidative stress

Abstract

Purpose : Pterostilbene (PS), a naturally dietary compound of blueberries, has been proven to be an anti-inflammatory and anti-oxidative agent. However, there is no study on its effect on ocular diseases, such as dry eye. This study was to explore potential protective effects of PS on dry eye using an in vitro culture model of human corneal epithelial cells (HCECs) exposed to hyperosmotic medium.

Methods : Primary HCECs were cultured from fresh donor limbal explants. Hyperosmolarity model was established by switching HCECs from isosmotic (312 mOsm) to hyperosmotic medium (450 mOsm) alone or in the presence of different concentration (5-20μM) of PS for 4-24h. Gene expression was detected by RT-qPCR; and protein production or activity was evaluated by ELISA, zymography, Western blotting and immunostaining. Reactive oxygen species (ROS) production was measured using a DCFDA kit.

Results : The addition of PS significantly reduced the expression of pro-inflammatory mediators, TNF-α, IL-1β, IL-6, MMP-2 and MMP-9 in HCECs exposed to hyperosmotic medium. Pre-treatment with PS (5 to 20µM) suppressed ROS overproduction in a dose-dependent manner. Additionally, PS significantly decreased the levels of oxidative damage biomarkers, malondialdehyde (MDA), 4-hydroxynonenal (4-HNE), aconitase-2 and 8-hydroxydeoxyguanosine (8-OHdG). Importantly, PS was found to rebalance homeostasis between oxygenases and anti-oxidative enzymes by decreasing cyclooxygenase 2 (COX2) expression and restoring the activity of antioxidant enzymes, super oxide dismutase 1 (SOD1) and peroxiredoxin-4 (PRDX4) during hyperosmotic stress.

Conclusions : Our findings demonstrate for the first time that blueberry component pterostilbene protects the human cornea from hyperosmolarity-induced inflammation and oxidative stress, suggesting the protective potential to dry eye disease.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.