Budesonide and fluticasone propionate differentially affect the airway epithelial barrier

Heijink et al. Respiratory Research (2016) 17:2 DOI 10.1186/s12931-015-0318-z RESEARCH Open Access Budesonide and fluticasone propionate differentially affect the airway epithelial barrier I. H. Heijink1,2,3*, M. R. Jonker1, M. de Vries1,3, A. J. M. van Oosterhout1,3, E. Telenga2,3, N. H. T. ten Hacken2,3, D. S. Postma2,3 and M. van den Berge2,3 Abstract Background: COPD patients have a higher risk of pneumonia when treated with fluticasone propionate (FP) than with placebo, and a lower risk with budesonide (BUD). We hypothesized that BUD and FP differentially affect the mucosal barrier in response to viral infection and/or cigarette smoke. Methods: We assessed protective effects of equivalent concentrations of BUD and FP on cytokine production and barrier function (electrical resistance) in human bronchial epithelial 16HBE cells and primary bronchial epithelial cells (PBECs) upon exposure to viral mimetic poly-(I:C) and/or cigarette smoke extract (CSE) or epidermal growth factor (EGF). Results: BUD and FP were equally effective in suppressing poly-(I:C)- and/or CSE-induced IL-8 secretion in 16HBE and PBECs. Poly-(I:C) substantially decreased electrical resistance in 16HBE cells and both BUD and FP fully counteracted this effect. However, FP hardly affected 16HBE barrier dysfunction induced by CSE with/without poly-(I:C), whereas BUD (16 nM) provided full protection, an effect likely mediated by affecting EGFR-downstream target GSK-3β. Similarly, BUD, but not FP, significantly improved CSE-induced barrier dysfunction in PBECs. Finally, BUD, but not FP, exerted a modest but significant protective effect against Streptococcus Pneumoniae-induced barrier dysfunction, and BUD, but not FP, prevented cellular adhesion and/or internalization of these bacteria induced by poly-(I:C) in 16HBE. Conclusions: Collectively, both BUD and FP efficiently control epithelial pro-inflammatory responses and barrier function upon mimicry of viral infection. Of potential clinical relevance, BUD more effectively counteracted CSE-induced barrier dysfunction, reinforcing the epithelial barrier and potentially limiting access of pathogens upon smoking in vivo. Keywords: Bronchial epithelial cells, COPD, Pneumonia, Cigarette smoke extract, Poly-(I:C) Background Chronic Obstructive Pulmonary Disease (COPD) is a chronic inflammatory respiratory disease affecting millions of people worldwide. Inhaled corticosteroids (ICS) are widely used in the management of COPD. ICS effectively reduce the number of exacerbations and improve respiratory symptoms and quality of life [1]. * Correspondence: 1 Department of Pathology & Medical Biology, Experimental Pulmonology and Inflammation Research, University of Groningen, University Medical Center Groningen,, Hanzeplein 1, NL-9713 GZ, Groningen, The Netherlands 2 Department of Pulmonology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands Full list of author information is available at the end of the article However, ICS use may also increase the risk of pneumonia in COPD [2, 3]. The TORCH study demonstrated this for the first time, comparing fluticasone propionate (FP) and placebo [2, 3]. Findings from this study were confirmed in a meta-analysis by Singh and colleagues [4]. Sixteen of the 18 studies included in the metaanalysis of Singh and colleagues investigated the effects of FP or FP/salmeterol, and it remained unclear whether the increased pneumonia risk would be FP specific or a class effect of ICS and also present with budesonide (BUD) treatment. More recent studies suggested that pneumonia events were lower with BUD than with FP treatment [5, 6]. Furthemore, Suissa and colleagues © 2016 Heijink et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Heijink et al. Respiratory Research (2016) 17:2 reported that FP treatment is associated with a substantial increase in the risk of serious pneumonia in COPD patients, while the risk with BUD was comparatively low, even at high doses [7]. Most recently, Suissa and colleagues reported that discontinuation of ICS use in COPD is associated with a reduction in the elevated risk of serious pneumonia, especially for FP [8]. Thus, the increased risk to develop pneumonia in COPD may be specific to the use of FP and not the result of a class effect of ICS. The cellular mechanisms underlying these differences in safety for ICS use in COPD patients are not well understood. BUD is less lipophilic than FP and has a higher aqueous solubility, leading to a shorter retention time in the lining fluid of the airways, while after being absorbed, BUD is retained in airway tissue/epithelium for a longer time than FP [9, 10]. It is as yet unknown how this may affect the action of BUD and FP in epithelial cells. The bronchial epithelium forms the first continuous physical barrier to microbial infections and is part of the innate immune response, producing antimicrobial and pro-inflammatory peptides/cytokines acting on immune cells, the latter especially when the epithelial layer is damaged. In COPD, aberrant epithelial repair in response to cigarette smoking may disturb epithelial barrier function [11] and we previously observed a reduction in epithelial barrier function upon smoke extract exposure in vitro [12]. Compromised barrier function may render the airways more susceptible to pathogens, and accordingly, rhinovirus-induced barrier dysfunction in mice was shown to increase the risk of a secondary bacterial infection [13]. The corticosteroid dexamethasone improves airway and corneal epithelial barrier function in vitro [14–16]. We hypothesized that BUD is more effective than FP in protecting against airway epithelial barrier dysfunction upon damage by environmental insults. Viral infection may predispose to bacterial pneumonia, activating toll-like receptor 3 (TLR3) on airway epithelium [13, 17]. TLR3-dependent effects have also been demonstrated for Haemophilus Influenza, one of the most common causes of pneumonia in COPD [18]. Therefore, we compared the effect of BUD and FP on viral mimetic poly-(I:C) and/or cigarette smokeinduced epithelial barrier function and proinflammatory cytokine production in both the human bronchial epithelial cell line 16HBE and cultured primary bronchial epithelial cells (PBECs) of smoking individuals with normal lung function. Methods Cell culture The human bronchial epithelial cell line 16HBE was kindly provided by (...truncated)