Effects of dexamethasone on mucin gene expression in cultured human nasal epithelial cells

Objective: To clarify 1) which mucin gene expression is influenced by glucocorticoid and 2) whether glucocorticoid influences steady-state mucin expression or mucin gene expression induced by lipopolysaccharide. Methods: Dissociated cells obtained from nasal polys were cultured on a collagen gel substrate in an air-liquid interface. Dexamethasone was added to the culture medium in the steady-state and prior to the stimulation by LPS. RNAs were extracted from culture cells, and semiquantitative reverse transcriptase-polymerase chain reaction was performed for MUC2, MUC5AC, MUC5B, MUC8, and beta-actin. Results: Dexamethasone did not influence steady-state messenger RNA levels of either mucin gene. Dexamethasone suppressed lipopolysaccharide-induced messenger RNA levels of MUC8. Conclusion: Glucocorticoid does not influence steady-state mucin gene expression but suppresses mucin gene expression induced by secretagogues such as lipopolysaccharide.