Fluorometholone modulates gene expression of ocular surface mucins

Purpose: Mucins are vital to keep the ocular surface hydrated. Genes encoding for mucins contain a glucocorticoid response element. The purpose of this study was to evaluate the effect of fluorometholone, a Glucocorticoid Receptor agonist used in the management of dry eye, on the gene expression of conjunctival and corneal epithelial cell mucins.

Methods: Stratified cultures of human conjunctival and corneal epithelial cells were exposed to 25, 50 and 100 nM of fluorometholone alone or in presence of mifepristone, a Glucocorticoid Receptor antagonist. The mRNA was isolated from the cells and reverse transcribed to cDNA. The cDNA was used for quantification of gene expression of Mucin (MUC) 1, 4, 16 and 19 using Real-Time PCR.

Results: Fluorometholone caused a dose- and time-dependent increase in the gene expression of MUC1, MUC4, MUC16 and MUC19 in the conjunctival as well as corneal epithelial cells. Mifepristone, a Glucocorticoid Receptor antagonist, inhibited fluorometholone-mediated increase in the gene expression of conjunctival and corneal mucins. At the tested concentration, neither fluorometholone nor mifepristone caused any notable changes in the cellular phenotype or viability of conjunctival and corneal epithelial cells.

Conclusion: Fluorometholone increases the gene expression of MUC1, MUC4, MUC16 and MUC19 in the conjunctival and corneal epithelial cells through activation of glucocorticoid receptors. The increased expression of mucins can be an additional possible mechanism contributing to the beneficial effects of fluorometholone in dry eye in addition to its well-known anti-inflammatory effects.