AJP - Lung Cellular and Molecular Physiology, Vol 272, Issue 5 838-L843, Copyright © 1997 by American Physiological Society

ARTICLES

Glucocorticoid receptor signaling in a bronchial epithelial cell line

T. D. LeVan, F. D. Behr, K. K. Adkins, R. L. Miesfeld and J. W. Bloom
Respiratory Sciences Center, University of Arizona, Tucson 85724, USA.

Glucocorticoids are an effective anti-inflammatory therapy for the treatment of asthma. The anti-inflammatory effects of glucocorticoids may be due to the inhibition of transcription factors that regulate cytokine synthesis. Because of the potential role of the bronchial epithelium in asthmatic inflammation and the possibility that this cell may be the main target of inhaled glucocorticoids, we have characterized glucocorticoid receptors (GR) and GR signaling in the human bronchial epithelial cell line BEAS-2B. Western blot analysis and radioligand binding studies demonstrated that BEAS-2B cells have functional GR that bind to dexamethasone (Dex) (dissociation constant = 5.6 nM and maximal density of binding sites = 228 +/- 3.3 fmol/mg protein). GR were activated by Dex as assessed using a glucocorticoid-responsive reporter plasmid. Transfection of BEAS-2B cells with an activator protein-1 (AP-1) reporter construct followed by 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment resulted in a fivefold induction of reporter gene activity. Transfection with a nuclear factor (NF)-kappa B reporter construct followed by tumor necrosis factor-alpha (TNF-alpha) treatment resulted in a 10-fold induction of reporter gene activity. Dex (10(-7) M) markedly repressed both the induced AP-1 and NF-kappa B activity. The GR antagonist RU-486 inhibited the repressive effect of Dex on TNF-alpha-induced NF-kappa B activity by 81% but only counteracted the repressive effect of Dex on TPA-induced AP-1 activity by 43%. These studies demonstrate that cross-signaling between AP-1 and NF-kappa B with GR may explain the anti-inflammatory properties of glucocorticoids in airway epithelial cells.

This article has been cited by other articles:

				A. Dagenais, R. Frechette, M.-E. Clermont, C. Masse, A. Prive, E. Brochiero, and Y. Berthiaume Dexamethasone inhibits the action of TNF on ENaC expression and activity Am J Physiol Lung Cell Mol Physiol, December 1, 2006; 291(6): L1220 - L1231. [Abstract] [Full Text] [PDF]

				M. Cecilia Berin, L. Eckmann, D. H. Broide, and M. F. Kagnoff Regulated Production of the T Helper 2-Type T-Cell Chemoattractant TARC by Human Bronchial Epithelial Cells In Vitro and in Human Lung Xenografts Am. J. Respir. Cell Mol. Biol., April 1, 2001; 24(4): 382 - 389. [Abstract] [Full Text]

				C. Stellato, S. Matsukura, A. Fal, J. White, L. A. Beck, D. Proud, and R. P. Schleimer Differential Regulation of Epithelial-Derived C-C Chemokine Expression by IL-4 and the Glucocorticoid Budesonide J. Immunol., November 15, 1999; 163(10): 5624 - 5632. [Abstract] [Full Text] [PDF]