Abstract
Purpose :
Ophthalmic glucocorticoids are often used to treat ocular surface inflammation and dry eye in graft versus host disease. A decrease in ocular surface inflammatory cells and cytokine levels has been shown to contribute to the ameliorative effect of glucocorticoids. Mucins are vital for keeping the ocular surface moist and lubricated. The present study investigates the effect of glucocorticoid receptor activation on modulation of ocular surface mucins.
Methods :
Human conjunctival and corneal epithelial cells were used. Conjunctival cells were grown in serum-free low calcium F12/DMEM medium then switched to serum-containing keratinocyte medium for stratification. Corneal epithelial cells were grown on transwell membrane inserts, in growth factor-supplemented keratinocyte medium. The dose and time-dependent effect of glucocorticoid receptor activation on mucin gene expression was tested by exposing the conjunctival and corneal cells to 25, 50 100 nM of fluorometholone, a glucocorticoid receptor agonist. To test whether the fluorometholone-mediated modulation of mucin expression was glucocorticoid receptor mediated, the cells were exposed to fluorometholone alone or with mifepristone (10μM), a glucocorticoid receptor antagonist. The cells were harvested at 12 and 24 hours of fluorometholone+/-mifepristone exposure. The mRNA isolation, cDNA preparation and protein extraction was performed. The mucins 1,4,5AC,16&19 gene expression and protein quantification was done using real time PCR and ELISA respectively. Statistical analysis was performed by One/Two way ANOVA and tuckey’s or Bonferonni’s tests.
Results :
Fluorometholone caused a dose-dependent increase in the expression of ocular mucins in the conjunctival and corneal epithelial cells, and the results were statistically significant after 24 hours exposure at 50 and 100 nM dose (p<0.01). Mifepristone significantly (p<0.01) antagonized flurometholone-mediated increase in ocular mucins suggesting that increase in ocular mucins was mediated by activation of glucocorticoid receptors.
Conclusions :
Glucocorticoid receptor activation increases the expression of ocular surface mucins. The observed increase in mucins may be a novel mechanism underlying the therapeutic benefits of glucocorticoids in ocular surface inflammatory diseases besides the well-documented anti-inflammatory effect.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.