Expression of the glucocorticoid receptor alpha and beta isoforms in human nasal mucosa and polyp epithelia cells

Abstract

The lower sensitivity of the inflamed nasal mucosa to glucocorticoids might be related to an increased expression of the glucocorticoid receptor (GR) beta isoform. We investigated GRα and GRβ mRNA expression in epithelial cells from nasal mucosa and nasal polyps, GRα mRNA was at least 1000 times more expressed than GRβ mRNA in both tissues. GRβ expression (mean ± SEM of 103 cDNA copies/μg of total RNA) was higher in nasal polyps (1.15 ± 0.19; n=27; P < 0.01) than in nasal mucosa (0.62 ± 0.10; n=32). Nasal polyps with > 3% of inflammatory cells had higher GRβ levels (1.40 ± 0.29; n=16) than both nasal mucosa (P < 0.01) and polyps with ≤ 3% of inflammatory cells (0.80 ± 0.18; n=11; P < 0.05). No difference in GRβ expression was found between nasal mucosa and polyps with ≤ 3% of inflammatory cells. GRβ expression correlated with the inflammatory cell number, especially with mast cells (r=0.50, P < 0.0001). There was no difference in GRα mRNA expression between nasal mucosa and nasal polyps. In summary, GRα is far more expressed than GRβ in both tissues. The increased expression of GRβ may be related to the presence of inflammatory cells. © 2002 Elsevier Science Ltd. All rights reserved.