Induction of apoptosis in nasal polyp fibroblasts by glucocorticoids in vitro

OBJECTIVE: To examine the possible mechanisms underlying the therapeutic mode of action of glucocorticoids (GCs) in nasal polyposis. MATERIAL AND METHODS: The effects of GCs on nasal polyps were firstly evaluated by examining the growth of fibroblasts derived from 10 nasal polyps in vitro. Subsequently, the ability of GCs to induce apoptotic cell death in fibroblasts was examined. RESULTS: Addition of betamethasone 21-phosphate (BET) at a concentration of > 1 x 10(-3) M to cell cultures inhibited cell growth in all cases examined. BET and dexamethasone 21-phosphate, but not testosterone or estradiol, caused apoptotic cell death in 2/10 nasal polyp fibroblasts, as assessed by agarose gel electrophoresis, when the cells were cultured with the agents for > 96 h. The minimum concentration of agent needed to cause apoptosis was 1 x 10(-3) M, which is half of the recommended therapeutic dose. CONCLUSION: The present findings suggest that topical application of GCs in nasal polyposis patients suppresses proliferation of fibroblasts in polyps and results in favorable modification of the clinical status of these patients.