Abstract
Purpose :
Hyperosmolarity and inflammation are recognized as both a cause and consequence of dry eye. Higher cytokine levels such as interleukin (IL), interferon (IFN) and tumor necrosis factor (TNF) are detected in the tears fluid of dry eye patient. The aim of this study was to comparatively determine the anti-inflammatory (AI) effect of hyaluronic acid (HA), lipoic acid (LA) and trehalose (T), alone or in combination, on human corneal epithelial (HCE) cells under hyperosmolar stress conditions.
Methods :
HCE cells were pre-incubated with hydrocortisone (HC) at 5µg/ml as positive control, active ingredient alone (T, LA or HA) or in combination (T+HA or LA+HA) for 17 hours. Then, cells were incubated under either iso-osmolar conditions (for T0 assessment) or hyperosmotic conditions using NaCl (100 mM) for 4 hours and 8 hours. IFN-γ, TNF-α, TNF-β and 12 IL levels were quantified into the supernatants of HCE cells by multiplexed ELISA at 3 different time points (0 hours, 4 hours, 8 hours). The cytokines expression profiles were normalized by total protein content. The sum of degree of change of each cytokine was calculated and the related total score allowed to determine a ranking of AI effect (high >5, moderate 3 to 5, low 1 to 3 and inflammation <1). Mann-Whitney nonparametric test (p < 0.05) were used to assess the statistical significance of this score compared to the NaCl control.
Results :
From a total of 15 inflammatory markers tested, significant signal of expression was observed for 12 of them. Cytokines levels reduction was demonstrated in this hyperosmotic model from the beginning of NaCl exposure to 8 hours. T3%+HA0.15% had the lowest AI score (1.63, p<0.05) whereas LA0.01%+HA0.18% presented the highest score (11.80, p<0.05) after 4 hours exposure to hyperosmotic stress. At 8 hours, T3% and T3%+HA0.15% had AI effect scores of 2.38 (p<0.05) and 5.69 (p<0.05) respectively. The highest AI values after 8 hours were associated to A0.01%+HA0.18% (12.42, p<0.05) and HA0.18% (17.65, p<0.05) samples.
Conclusions :
HA showed significantly high modulation of inflammatory activity at 0.18%. T3% and T3%+HA0.15% presented respectively low and medium protection after 8 hours of hyperosmotic stress. From the two tested combinations, LA0.01%+HA0.18% significantly provided the highest AI effect at each time points with improvement over the time.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.