Long-Actingβ₂-Adrenoceptor Agonists Enhance Glucocorticoid Receptor (GR)–Mediated Transcription by Gene-Specific Mechanisms Rather Than Generic Effects via GR

Abstract

In asthma, the clinical efficacy of inhaled corticosteroids (ICSs) is enhanced by long-acting -adrenoceptor agonists (LABAs). ICSs, or more accurately, glucocorticoids, promote therapeutically relevant changes in gene expression, and, in primary human bronchial epithelial cells (pHBECs) and airway smooth muscle cells, this genomic effect can be enhanced by a LABA. Modeling this interaction in human bronchial airway epithelial BEAS-2B cells transfected with a 2× glucocorticoid response element (2×GRE)-driven luciferase reporter showed glucocorticoid-induced transcription to be enhanced 2- to 3-fold by LABA. This glucocorticoid receptor (GR; NR3C1)-dependent effect occurred rapidly, was insensitive to protein synthesis inhibition, and was maximal when glucocorticoid and LABA were added concurrently. The ability of LABA to enhance GR-mediated transcription was not associated with changes in GR expression, serine (Ser, Ser, Ser) phosphorylation, ligand affinity, or nuclear translocation. Chromatin immunoprecipitation demonstrated that glucocorticoid-induced recruitment of GR to the integrated 2×GRE reporter and multiple gene loci, whose mRNAs were unaffected or enhanced by LABA, was also unchanged by LABA. Transcriptomic analysis revealed glucocorticoid-induced mRNAs were variably enhanced, unaffected, or repressed by LABA. Thus, events leading to GR binding at target genes are not the primary explanation for how LABAs modulate GR-mediated transcription. As many glucocorticoid-induced genes are independently induced by LABA, gene-specific control by GR- and LABA-activated transcription factors may explain these observations. Because LABAs promote similar effects in pHBECs, therapeutic relevance is likely. These data illustrate the need to understand gene function(s), and the mechanisms leading to gene-specific induction, if existing ICS/LABA combination therapies are to be improved.

Impact of Phosphodiesterase 4 Inhibition on the Operational Efficacy, Response Maxima, and Kinetics of Indacaterol-Induced Gene Expression Changes in BEAS-2B Airway Epithelial Cells: A Global Transcriptomic Analysis

“…While the mechanism of action of roflumilast is unclear, its ability to improve lung function and reduce exacerbation frequency (Wedzicha et al, 2016), in the absence of direct bronchodilatation (Grootendorst et al, 2003), implies that suppression of inflammation plays a role (Gamble et al, 2003;Grootendorst et al, 2007). We have reported previously that LABAs promote changes in gene expression in human airway epithelial cells that may contribute to: 1) their clinical efficacy in obstructive lung diseases, especially when combined with an ICS (Giembycz andNewton, 2011, 2015;Rider et al, 2018); and 2) the AEs that are associated with chronic b 2 -adrenoceptor agonist monotherapy (vide infra; Yan et al, 2018). This study extended those findings by establishing that PDE4 inhibitors also promoted changes in gene expression in BEAS-2B cells and, perhaps more importantly, increased the operational efficacy, enhanced the magnitude of response, and variably altered gene expression kinetics induced by LABAs.…”

“…LABAs and PDE4 inhibitors also induced several genes that may encode negative feedback regulators of inflammation that include KLF2, KLF4, KLF15, and the NR4A family of transcription factors (Rodríguez-Calvo et al, 2017;Sweet et al, 2018). Many of these genes are further upregulated when an LABA and/or a PDE4 inhibitor are combined with a glucocorticoid (Moodley et al, 2013;Rider et al, 2018), which may be relevant to understanding how these drugs work in a clinical setting (Giembycz and Newton, 2014).…”

Recent findings in the genetics and epigenetics of asthma and allergy

“…In general, the combination of ICS and LABA is the cornerstone of therapy in moderate to severe asthmatics and a recent study suggest that the response to combination therapy is under genetic control [90]. Interestingly, many glucocorticoid-induced genes were shown to be independently induced by LABA.…”

Genomic determinants implicated in the glucocorticoid-mediated induction of KLF9 in pulmonary epithelial cells

“…While glucocorticoids are used for their antiinflammatory effects, a significant fraction of the glucocorticoid-regulated transcriptome is modulated by inflammatory stimuli, including lipopolysaccharide (LPS) and TNF (20,33,42,43). A549 cells were therefore treated with budesonide, interleukin-1β (IL1B), or their combination for 1, 2, 6, 12, and 24 h ( Fig.…”