Corticosteroid‐induced gene expression in allergen‐challenged asthmatic subjects taking inhaled budesonide

Abstract

BACKGROUND AND PURPOSEInhaled corticosteroids (ICS) are the cornerstone of asthma pharmacotherapy and, acting via the glucocorticoid receptor (GR), reduce inflammatory gene expression. While this is often attributed to a direct inhibitory effect of the GR on inflammatory gene transcription, corticosteroids also induce the expression of anti-inflammatory genes in vitro. As there are no data to support this effect in asthmatic subjects taking ICS, we have assessed whether ICS induce anti-inflammatory gene expression in subjects with atopic asthma. EXPERIMENTAL APPROACHBronchial biopsies from allergen-challenged atopic asthmatic subjects taking inhaled budesonide or placebo were subjected to gene expression analysis using real-time reverse transcriptase-PCR for the corticosteroid-inducible genes (official gene symbols with aliases in parentheses): TSC22D3 [glucocorticoid-induced leucine zipper (GILZ)], dual-specificity phosphatase-1 (MAPK phosphatase-1), both anti-inflammatory effectors, and FKBP5 [FK506-binding protein 51 (FKBP51)], a regulator of GR function. Cultured pulmonary epithelial and smooth muscle cells were also treated with corticosteroids before gene expression analysis. KEY RESULTSCompared with placebo, GILZ and FKBP51 mRNA expression was significantly elevated in budesonide-treated subjects. Budesonide also increased GILZ expression in human epithelial and smooth muscle cells in culture. Immunostaining of bronchial biopsies revealed GILZ expression in the airways epithelium and smooth muscle of asthmatic subjects. CONCLUSIONS AND IMPLICATIONSExpression of the corticosteroid-induced genes, GILZ and FKBP51, is up-regulated in the airways of allergen-challenged asthmatic subjects taking inhaled budesonide. Consequently, the biological effects of corticosteroid-induced genes should be considered when assessing the actions of ICS. Treatment modalities that increase or decrease GR-dependent transcription may correspondingly affect corticosteroid efficacy. AbbreviationsAP-1, activator protein 1; ASM, airway smooth muscle; DMEM, Dulbecco's modified Eagle's medium; FCS, fetal calf serum; FKBP51, FK506-binding protein 51; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; GILZ, glucocorticoidinduced leucine zipper; GR, glucocorticoid receptor; GRE, glucocorticoid response element; HBE, human bronchial epithelial; ICS, inhaled corticosteroid; MKP, MAPK phosphatase; RT, reverse transcriptase BJP British Journal of Pharmacology DOI:10.1111DOI:10. /j.1476DOI:10. -5381.2011 British Journal of Pharmacology (2012) IntroductionIn asthma, inhaled corticosteroids (ICS), also called glucocorticoids, are highly effective at reducing inflammation and improving patient outcomes (Barnes, 2006), and ICS remain the cornerstone of pharmacological therapy (Bateman et al., 2008). ICS attenuate airway eosinophil numbers, reduce asthma exacerbations and mortality and lead to improvements in lung function and health-related quality of life (Suissa et al., 2000;Pauwels et al., 2003;Kelly et al., 2006b;Busse et al., 2008;Newton et al....

Glucocorticoid Genes and the Developmental Origins of Asthma Susceptibility and Treatment Response

“…Based on its role in glucocorticoid signaling, FKBP5 expression has been previously studied in bronchial biopsy specimens in subjects with asthma. Similar to our findings in bronchial brushing and biopsy specimens, inhaled budesonide treatment has previously been shown to increase FKBP5 expression in bronchial biopsy specimens of subjects with asthma (46). However, in a previous genetic association study, there was no association of genetic polymorphisms in FKBP5 with improved lung function in subjects with asthma treated with inhaled corticosteroids (47).…”

Phosphodiesterase 4 Inhibitors Augment the Ability of Formoterol to Enhance Glucocorticoid-Dependent Gene Transcription in Human Airway Epithelial Cells: A Novel Mechanism for the Clinical Efficacy of Roflumilast in Severe Chronic Obstructive Pulmonary Disease

“…As outlined in the Introduction, transactivation is now believed to constitute a major mechanism of glucocorticoid action, which likely operates in tandem with the more established process of transrepression. Indeed, the expression of the anti-inflammatory gene GILZ is significantly upregulated in bronchial biopsies harvested from human asthmatic subjects given inhaled budesonide (Kelly et al, 2012). On this basis, we propose that roflumilast in combination with an ICS may be more effective in reducing exacerbation frequency and improving lung function in patients with severe COPD relative to either drug alone due to their ability, at least in part, to interact in a positive cooperative manner on the expression of a variety of glucocorticoid-inducible, anti-inflammatory genes.…”

Induction of Regulator of G-Protein Signaling 2 Expression by Long-Acting β2-Adrenoceptor Agonists and Glucocorticoids in Human Airway Epithelial Cells

“…In the context of inhaled therapeutics, lung concentrations of ICS can readily reach 1-100 nM (Esmailpour et al, 1997;Miller-Larsson and Selroos, 2002;Todorova et al, 2006;van den Brink et al, 2008). Furthermore, in mild atopic asthmatics, inhalation of a moderate dose of budesonide (800 mg per day) for 10 days significantly increased the expression of glucocorticoid-induced leucine zipper (GILZ/ TSC22D3) and FK506-binding protein 51 (FKBP51/FKBP5) (Kelly et al, 2012). Thus, glucocorticoid concentrations necessary to induce gene expression are achieved by ICS and glucocorticoid-dependent increases in gene expression occur with therapeutic intervention.…”