β2-Agonists Enhance Asthma-Relevant Inflammatory Mediators in Human Airway Epithelial Cells

Comparison of the Genomic Activity of an EP4-Receptor and β2-Adrenoceptor Agonist in BEAS-2B Human Bronchial Epithelial Cells: In Search of Compartmentalized, cAMP-Dependent Gene Expression

It has been proposed that inhaled E-prostanoid 4 (EP4)-receptor agonists could represent a new class of bronchodilators for the treatment of asthma that are as effective as β 2-adrenoceptor agonists. However, the genomic impact of such drugs is unknown despite being potentially deleterious to respiratory health. Herein, we used mRNA-seq to compare the transcriptomic responses produced by 2-[3-[(1R,2S,3R)-3-hydroxy-2-[(E,3S)-3-hydroxy-5-[2-(methoxymethyl)phenyl]pent-1-enyl]-5-oxo-cyclopentyl]sulphanylpropylsulphanyl] acetic acid (ONO-AE1-329; an EP4-receptor agonist) and vilanterol (a β 2-adrenoceptor agonist) in BEAS-2B human airway epithelial cells. We also determined if an increase in cAMP mediated by different G protein-coupled receptors (GPCRs) promoted distinct transcriptional signatures by expanding this inquiry to include the adenosine A2B- and I-prostanoid receptor agonists, 2-[[6-amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]-2-pyridinyl]thio]-acetamide (Bay60-6583) and taprostene, respectively. Maximally-effective concentrations of ONO-AE1-329 and vilanterol significantly regulated (q ≤ 0.05; ≥1.5-/≤0.67-fold) 232 and 320 genes, respectively of which 217 were shared. Spearman analysis showed these gene expression changes to be highly rank order correlated, indicating that the functional overlap between the two interventions should be considerable. Unexpectedly, the genomic effects of ONO-AE1-329, vilanterol, Bay 60-6583, and taprostene were also highly rank order correlated. This finding suggests that cAMP generated by any GPCR would initiate the same transcriptional program. Nevertheless, relative to vilanterol, ONO-AE1-329 typically behaved as a partial agonist that varied across transcripts. These data indicate that each ONO-AE1-329-regulated gene differs in sensitivity to cAMP and is defined by a unique receptor occupancy-response relationship. Moreover, if this relatively modest genomic response in BEAS-2B cells is retained in vivo, then inhaled EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators. SIGNIFICANCE STATEMENT: The genomic consequences of β 2-adrenoceptor agonists in asthma are often overlooked despite being potentially harmful to lung health. We determined that ONO-AE1-329, an EP4-receptor agonist and effective bronchodilator, produced gene expression changes in BEAS-2B cells that were typically modest relative to the β 2-adrenoceptor agonist vilanterol. Furthermore, ONO-AE1-329 behaved as a partial agonist that varied across transcripts. If this genomic activity is reproduced in vivo, then EP4-receptor agonists could represent an alternative, and possibly safer, class of bronchodilators.

Toward Personalized Salbutamol Therapy: Validating Virtual Patient-Derived Population Pharmacokinetic Model with Real-World Data

Interindividual variability, influenced by patient-specific factors including age, weight, gender, race, and genetics, among others, contributes to variations in therapeutic response. Population pharmacokinetic (popPK) modeling is an essential tool for pinpointing measurable factors affecting dose-concentration relationships and tailoring dosage regimens to individual patients. Herein, we developed a popPK model for salbutamol, a short-acting β2-agonist (SABA) used in asthma treatment, to identify key patient characteristics that influence treatment response. To do so, synthetic data from physiologically-based pharmacokinetic (PBPK) models was employed, followed by an external validation using real patient data derived from an equivalent study. Thirty-two virtual patients were included in this study. A two-compartment model, with first-order absorption (no delay), and linear elimination best fitted our data, according to diagnostic plots and selection criteria. External validation demonstrated a strong agreement between individual predicted and observed values. The incorporation of covariates into the basic structural model identified a significant impact of age on clearance (Cl) and intercompartmental clearance (Q); gender on Cl and the constant rate of absorption (ka); race on Cl; and weight on Cl in the volume of distribution of the peripheral compartment (V2). This study addresses critical challenges in popPK modeling, particularly data scarcity, incompleteness, and homogeneity, in traditional clinical trials, by leveraging synthetic data from PBPK modeling. Significant associations between individual characteristics and salbutamol's PK parameters, here uncovered, highlight the importance of personalized therapeutic regimens for optimal treatment outcomes.

SABINA + Hong Kong: a territory wide study of prescribing trends and outcomes associated with the use of short-acting β2 agonists in the Chinese population

BACKGROUND

Excessive use of short-acting β2 agonists (SABA) in patients with asthma continues to be a notable concern due to its link to higher mortality rates. Global relevance of SABA overuse in asthma management cannot be understated, it poses significant health risk to patients with asthma and imposes burden on healthcare systems. This study, as part of global SABINA progamme, aimed to describe the prescribing patterns and clinical outcomes associated with SABA use in the Chinese population.

METHODS

Retrospective cohort study was conducted using anonymized electronic healthcare records of Clinical Data Analysis and Reporting System (CDARS) from Hong Kong Hospital Authority (HA). Patients newly diagnosed with asthma between 2011 and 2018 and aged ≥12 years were included, stratified by SABA use (≤2, 3-6, 7-10, or ≥11 canisters/year) during one-year baseline period since asthma diagnosis date. Patients were followed up from one-year post-index until earliest censoring of events: outcome occurrence and end of study period (31 December 2020). Cox proportional regression and negative binomial regression were used to estimate the mortality risk and frequency of hospital admissions associated with SABA use respectively, after adjusting for age, sex, Charlson Comorbidity Index (CCI), and inhaled corticosteroid (ICS) dose. Outcomes include all-cause, asthma-related, and respiratory-related mortality, frequency of hospital admissions for any cause, and frequency of hospital admissions due to asthma.

RESULTS

17,782 patients with asthma (mean age 46.7 years, 40.8% male) were included and 59.1% of patients were overusing SABA (≥ 3 canisters per year). Each patient was prescribed a median of 5.61 SABA canisters/year. SABA overuse during baseline period was associated with higher all-cause mortality risk compared to patients with ≤2 canisters/year. Association was dose-dependent, highest risk in those used ≥11 canisters/year (adjusted hazard ratio: 1.42, 95% CI: 1.13, 1.79) and 3-6 canisters/year (adjusted hazard ratio: 1.22, 95% CI: 1.00, 1.50). Higher SABA prescription volume associated with increased frequency of hospital admissions with greatest risk observed in 7-10 canisters/year subgroup (adjusted rate ratio: 4.81, 95% CI: 3.66, 6.37).

CONCLUSIONS

SABA overuse is prevalent and is associated with increased all-cause mortality risk and frequency of hospital admissions among the patients with asthma in Hong Kong.

The Wiser Strategy of Using Beta-Agonists in Asthma: Mechanisms and Rationales

Concerns regarding the safety of beta-2 agonists have led to revisions of the major asthma guidelines to better address these issues. Although these updates allow for a combination of previous and current strategies, they may confuse clinical practitioners. Beta-2 agonists are vital for alleviating asthma symptoms by relaxing smooth muscles; however, they also pose significant risks by inducing pro-inflammatory mediators both in vitro and in vivo. In addition to the risks of overuse and symptom masking, the use of beta-agonists alone at therapeutic doses can worsen airway inflammation and enhance virus-induced inflammation during asthma exacerbation. Inhaled corticosteroids (ICS) can effectively prevent these adverse effects. With new insights into the mechanisms of these adverse events, reserving short-acting beta-agonists for acute symptom relief during exacerbations and only for those who are already on ICS or oral steroids represents a careful approach to using beta-agonists with least adverse effects in patients with asthma. However, a major drawback of this approach is the potential non-compliance with ICS, leading to beta-agonist use without the necessary counteraction by ICS. An optimal strategy, both during and outside exacerbations, would integrate beta-agonists into an anti-inflammatory regimen that includes ICS, ideally combined with the same inhaler to ensure their concurrent use where finances allow. This would maintain the beneficial effects of beta-agonists, such as bronchodilation, while preventing the adverse effects from the induction of inflammatory mediators. This method is aligned with diverse clinical settings, maximizes the safe use of beta-agonists, and supports a comprehensive guideline-compliant management strategy.

Salbutamol in the Management of Asthma: A Review

Asthma is a common inflammatory disease of the lungs. The prevalence of asthma is increasing worldwide, and the tendency indicates that the number of asthma sufferers will soar in the coming years for several reasons, in particular, the lifestyles we have adopted that expose us to risk factors. Salbutamol is the first selective short-acting β2-agonist (SABA) used as an alternative reliever in the treatment of asthma. Its therapeutic effect is based on its potent smooth muscle relaxant properties, which allow the inhibition of bronchial smooth muscle contraction and subsequent bronchodilation. Salbutamol can be administered orally, intravenously (IV), intramuscularly (IM), subcutaneously, or by inhalation. For this reason, the pharmacokinetic (PK) parameters-absorption, distribution, metabolism, and elimination-are highly diverse and, consequently, the efficacy and adverse effects also differ between each formulation. Here, we review the pharmacological profile of different salbutamol formulations, focusing on their efficacy and adverse effects for its original application, asthma.

α and β Catalytic Subunits of cAMP-dependent Protein Kinase Regulate Formoterol-induced Inflammatory Gene Expression Changes in Human Bronchial Epithelial Cells

BACKGROUND & PURPOSE

It has been proposed that genomic mechanisms contribute to the adverse-effects that are often experienced by asthmatic subjects who take regular, inhaled β₂ -adrenoceptor agonists as a monotherapy. Moreover, data from preclinical models of asthma suggest that these gene expression changes are mediated by β-arrestin-2 rather than PKA. Herein, we tested this hypothesis by comparing the genomic effects of formoterol, a β₂ -adrenoceptor agonist, with forskolin in human primary bronchial epithelial cells (HBEC).

EXPERIMENTAL APPROACH

Gene expression changes were determined by RNA-sequencing. Gene silencing and genome editing were employed to explore the roles of β-arrestin-2 and PKA.

KEY RESULTS

The formoterol-regulated transcriptome in HBEC treated concurrently with TNFα, was defined by 1480 unique gene expression changes. TNFα-induced transcripts modulated by formoterol were annotated with enriched gene ontology terms related to inflammation and proliferation, notably "GO:0070374~positive regulation of ERK1 and ERK2 cascade", which is an established β-arrestin-2 target. However, expression of the formoterol- and forskolin-regulated transcriptomes were highly rank-order correlated and the effects of formoterol on TNFα-induced inflammatory genes were abolished by an inhibitor of PKA. Furthermore, formoterol-induced gene expression changes in BEAS-2B bronchial epithelial cell clones deficient in β-arrestin-2 were comparable to those expressed by their parental counterparts. Contrariwise, gene expression was partially inhibited in clones lacking the α-catalytic subunit (Cα) of PKA and abolished following the additional knockdown of the β-catalytic subunit (Cβ) paralogue.

CONCLUSIONS

The effects of formoterol on inflammatory gene expression in airway epithelia are mediated by PKA and involve the cooperation of PKA-Cα and PKA-Cβ.

Using correlates to accelerate vaccinology

Correlates and surrogates of desired outcomes are valuable but have limitations.

Potentiation of long-acting β2-agonist and glucocorticoid responses in human airway epithelial cells by modulation of intracellular cAMP

Introduction

Over 300 million people in the world live with asthma, resulting in 500,000 annual global deaths with future increases expected. It is estimated that around 50–80% of asthma exacerbations are due to viral infections. Currently, a combination of long-acting beta agonists (LABA) for bronchodilation and glucocorticoids (GCS) to control lung inflammation represent the dominant strategy for the management of asthma, however, it is still sub-optimal in 35–50% of moderate-severe asthmatics resulting in persistent lung inflammation, impairment of lung function, and risk of mortality. Mechanistically, LABA/GCS combination therapy results in synergistic efficacy mediated by intracellular cyclic adenosine monophosphate (cAMP).

Hypothesis

Increasing intracellular cAMP during LABA/GCS combination therapy via inhibiting phosphodiesterase 4 (PDE4) and/or blocking the export of cAMP by ATP Binding Cassette Transporter C4 (ABCC4), will potentiate anti-inflammatory responses of mainstay LABA/GCS therapy.

Methods

Expression and localization experiments were performed using in situ hybridization and immunohistochemistry in human lung tissue from healthy subjects, while confirmatory transcript and protein expression analyses were performed in primary human airway epithelial cells and cell lines. Intervention experiments were performed on the human airway epithelial cell line, HBEC-6KT, by pre-treatment with combinations of LABA/GCS with PDE4 and/or ABCC4 inhibitors followed by Poly I:C or imiquimod challenge as a model for viral stimuli. Cytokine readouts for IL-6, IL-8, CXCL10/IP-10, and CCL5/RANTES were quantified by ELISA.

Results

Using archived human lung and human airway epithelial cells, ABCC4 gene and protein expression were confirmed in vitro and in situ. LABA/GCS attenuation of Poly I:C or imiquimod-induced IL-6 and IL-8 were potentiated with ABCC4 and PDE4 inhibition, which was greater when ABCC4 and PDE4 inhibition was combined. Modulation of cAMP levels had no impact on LABA/GCS modulation of Poly I:C-induced CXCL10/IP-10 or CCL5/RANTES.

Conclusion

Modulation of intracellular cAMP levels by PDE4 or ABCC4 inhibition potentiates LABA/GCS efficacy in human airway epithelial cells challenged with viral stimuli. The data suggest further exploration of the value of adding cAMP modulators to mainstay LABA/GCS therapy in asthma for potentiated anti-inflammatory efficacy.

β 2-Adrenoceptor Agonists Promote Extracellular Signal-Regulated Kinase 1/2 Dephosphorylation in Human Airway Epithelial Cells by Canonical, cAMP-Driven Signaling Independently of β-Arrestin 2

Chronic use of β 2-adrenoceptor agonists as a monotherapy in asthma is associated with a loss of disease control and an increased risk of mortality. Herein, we tested the hypothesis that β 2-adrenoceptor agonists, including formoterol, promote biased, β-arrestin (Arr) 2-dependent activation of the mitogen-activated protein kinases, ERK1/2, in human airway epithelial cells and, thereby, effect changes in gene expression that could contribute to their adverse clinical outcomes. Three airway epithelial cell models were used: the BEAS-2B cell line, human primary bronchial epithelial cells (HBEC) grown in submersion culture, and HBEC that were highly differentiated at an air-liquid interface. Unexpectedly, treatment of all epithelial cell models with formoterol decreased basal ERK1/2 phosphorylation. This was mediated by cAMP-dependent protein kinase and involved the inactivation of C-rapidly-activated fibrosarcoma, which attenuated downstream ERK1/2 activity, and the induction of dual-specificity phosphatase 1. Formoterol also inhibited the basal expression of early growth response-1, an ERK1/2-regulated gene that controls cell growth and repair in the airways. Neither carvedilol, a β 2-adrenoceptor agonist biased toward βArr2, nor formoterol promoted ERK1/2 phosphorylation in BEAS-2B cells, although β 2-adrenoceptor desensitization was compromised in ARRB2-deficient cells. Collectively, these results contest the hypothesis that formoterol activates ERK1/2 in airway epithelia by nucleating a βArr2 signaling complex; instead, they indicate that β 2-adrenoceptor agonists inhibit constitutive ERK1/2 activity in a cAMP-dependent manner. These findings are the antithesis of results obtained using acutely challenged native and engineered HEK293 cells, which have been used extensively to study mechanisms of ERK1/2 activation, and highlight the cell type dependence of β 2-adrenoceptor-mediated signaling. SIGNIFICANCE STATEMENT: It has been proposed that the adverse effects of β 2-adrenoceptor agonist monotherapy in asthma are mediated by genomic mechanisms that occur principally in airway epithelial cells and are the result of β-arrestin 2-dependent activation of ERK1/2. This study shows that β 2-adrenoceptor agonists, paradoxically, reduced ERK1/2 phosphorylation in airway epithelia by disrupting upstream rat sarcoma-C-rapidly accelerated fibrosarcoma complex formation and inducing dual-specificity phosphatase 1. Moreover, these effects were cAMP-dependent protein kinase-dependent, suggesting that β 2-adrenoceptor agonists were not biased toward β-arrestin 2 and acted via canonical, cAMP-dependent signaling.

Epithelial Barrier Dysfunction in Chronic Respiratory Diseases

Mucosal surfaces are lined by epithelial cells, which provide a complex and adaptive module that ensures first-line defense against external toxics, irritants, antigens, and pathogens. The underlying mechanisms of host protection encompass multiple physical, chemical, and immune pathways. In the lung, inhaled agents continually challenge the airway epithelial barrier, which is altered in chronic diseases such as chronic obstructive pulmonary disease, asthma, cystic fibrosis, or pulmonary fibrosis. In this review, we describe the epithelial barrier abnormalities that are observed in such disorders and summarize current knowledge on the mechanisms driving impaired barrier function, which could represent targets of future therapeutic approaches.

Adrenergic and Glucocorticoid Receptors in the Pulmonary Health Effects of Air Pollution

Adrenergic receptors (ARs) and glucocorticoid receptors (GRs) are activated by circulating catecholamines and glucocorticoids, respectively. These receptors regulate the homeostasis of physiological processes with specificity via multiple receptor subtypes, wide tissue-specific distribution, and interactions with other receptors and signaling processes. Based on their physiological roles, ARs and GRs are widely manipulated therapeutically for chronic diseases. Although these receptors play key roles in inflammatory and cellular homeostatic processes, little research has addressed their involvement in the health effects of air pollution. We have recently demonstrated that ozone, a prototypic air pollutant, mediates pulmonary and systemic effects through the activation of these receptors. A single exposure to ozone induces the sympathetic–adrenal–medullary and hypothalamic–pituitary–adrenal axes, resulting in the release of epinephrine and corticosterone into the circulation. These hormones act as ligands for ARs and GRs. The roles of beta AR (βARs) and GRs in ozone-induced pulmonary injury and inflammation were confirmed in a number of studies using interventional approaches. Accordingly, the activation status of ARs and GRs is critical in mediating the health effects of inhaled irritants. In this paper, we review the cellular distribution and functions of ARs and GRs, their lung-specific localization, and their involvement in ozone-induced health effects, in order to capture attention for future research.

The dynamicity of acute ozone-induced systemic leukocyte trafficking and adrenal-derived stress hormones

Ozone exposure induces neuroendocrine stress response, which causes lymphopenia. It was hypothesized that ozone-induced increases in stress hormones will temporally follow changes in circulating granulocytes, monocytes- and lymphocyte subpopulations. The goal of this study was to chronicle the changes in circulating stress hormones, cytokines, and leukocyte trafficking during 4 h exposure to ozone. Male Wistar Kyoto rats were exposed to air or ozone (0.4 or 0.8 ppm) for 0.5, 1, 2, or 4 h. After each time point, circulating stress hormones, cytokines, and lung gene expression were assessed along with live and apoptotic granulocytes, monocytes (classical and non-classical), and lymphocytes (B, T_h, and T_c) in blood, thymus, and spleen using flow cytometry. Circulating stress hormones began to increase at 1 h of ozone exposure. Lung expression of inflammatory cytokines (Cxcl2, Il6, and Hmox1) and glucocorticoid-responsive genes (Nr3c1, Fkbp5 and Tsc22d3) increased in both a time- and ozone concentration-dependent manner. Circulating granulocytes increased at 0.5 h of ozone exposure but tended to decrease at 2 and 4 h, suggesting a rapid egress and then margination to the lung. Classical monocytes decreased over 4 h of exposure periods (∼80 % at 0.8 ppm). B and T_c lymphocytes significantly decreased after ozone exposure at 2 and 4 h. Despite dynamic shifts in circulating immune cell populations, few differences were measured in serum cytokines. Ozone neither increased apoptotic cells nor altered thymus and spleen lymphocytes. The data show that ozone-induced increases in adrenal-derived stress hormones precede the dynamic migration of circulating immune cells, likely to the lung to mediate inflammation.

Independent roles of beta-adrenergic and glucocorticoid receptors in systemic and pulmonary effects of ozone

Background: The release of catecholamines is preceded by glucocorticoids during a stress response. We have shown that ozone-induced pulmonary responses are mediated through the activation of stress hormone receptors.Objective: To examine the interdependence of beta-adrenergic (βAR) and glucocorticoid receptors (GRs), we inhibited βAR while inducing GR or inhibited GR while inducing βAR and examined ozone-induced stress response.Methods: Twelve-week-old male Wistar-Kyoto rats were pretreated daily with saline or propranolol (PROP; βAR-antagonist; 10 mg/kg-i.p.; starting 7-d prior to exposure) followed-by saline or dexamethasone (DEX) sulfate (GR-agonist; 0.02 mg/kg-i.p.; starting 1-d prior to exposure) and exposed to air or 0.8 ppm ozone (4 h/d × 2-d). In a second experiment, rats were similarly pretreated with corn-oil or mifepristone (MIFE; GR-antagonist, 30 mg/kg-s.c.) followed by saline or clenbuterol (CLEN; β₂AR-agonist; 0.02 mg/kg-i.p.) and exposed.Results: DEX and PROP + DEX decreased adrenal, spleen and thymus weights in all rats. DEX and MIFE decreased and increased corticosterone, respectively. Ozone-induced pulmonary protein leakage, inflammation and IL-6 increases were inhibited by PROP or PROP + DEX and exacerbated by CLEN or CLEN + MIFE. DEX and ozone-induced while MIFE reversed lymphopenia (MIFE > CLEN + MIFE). DEX exacerbated while PROP, MIFE, or CLEN + MIFE inhibited ozone-induced hyperglycemia and glucose intolerance. Ozone inhibited glucose-mediated insulin release.Conclusions: In summary, 1) activating βAR, even with GR inhibition, exacerbated and inhibiting βAR, even with GR activation, attenuated ozone-induced pulmonary effects; and 2) activating GR exacerbated ozone systemic effects, but with βAR inhibition, this exacerbation was less remarkable. These data suggest the independent roles of βAR in pulmonary and dependent roles of βAR and GR in systemic effects of ozone.

G Protein-Coupled Receptors in Asthma Therapy: Pharmacology and Drug Action

Asthma is a heterogeneous inflammatory disease of the airways that is associated with airway hyperresponsiveness and airflow limitation. Although asthma was once simply categorized as atopic or nonatopic, emerging analyses over the last few decades have revealed a variety of asthma endotypes that are attributed to numerous pathophysiological mechanisms. The classification of asthma by endotype is primarily routed in different profiles of airway inflammation that contribute to bronchoconstriction. Many asthma therapeutics target G protein-coupled receptors (GPCRs), which either enhance bronchodilation or prevent bronchoconstriction. Short-acting and long-acting β 2-agonists are widely used bronchodilators that signal through the activation of the β 2-adrenergic receptor. Short-acting and long-acting antagonists of muscarinic acetylcholine receptors are used to reduce bronchoconstriction by blocking the action of acetylcholine. Leukotriene antagonists that block the signaling of cysteinyl leukotriene receptor 1 are used as an add-on therapy to reduce bronchoconstriction and inflammation induced by cysteinyl leukotrienes. A number of GPCR-targeting asthma drug candidates are also in different stages of development. Among them, antagonists of prostaglandin D2 receptor 2 have advanced into phase III clinical trials. Others, including antagonists of the adenosine A2B receptor and the histamine H4 receptor, are in early stages of clinical investigation. In the past decade, significant research advancements in pharmacology, cell biology, structural biology, and molecular physiology have greatly deepened our understanding of the therapeutic roles of GPCRs in asthma and drug action on these GPCRs. This review summarizes our current understanding of GPCR signaling and pharmacology in the context of asthma treatment. SIGNIFICANCE STATEMENT: Although current treatment methods for asthma are effective for a majority of asthma patients, there are still a large number of patients with poorly controlled asthma who may experience asthma exacerbations. This review summarizes current asthma treatment methods and our understanding of signaling and pharmacology of G protein-coupled receptors (GPCRs) in asthma therapy, and discusses controversies regarding the use of GPCR drugs and new opportunities in developing GPCR-targeting therapeutics for the treatment of asthma.

Exacerbation of ozone-induced pulmonary and systemic effects by β2-adrenergic and/or glucocorticoid receptor agonist/s

Agonists of β₂ adrenergic receptors (β₂AR) and glucocorticoid receptors (GR) are prescribed to treat pulmonary diseases. Since ozone effects are mediated through the activation of AR and GR, we hypothesized that the treatment of rats with relevant therapeutic doses of long acting β₂AR agonist (LABA; clenbuterol; CLEN) and/or GR agonist (dexamethasone; DEX) would exacerbate ozone-induced pulmonary and systemic changes. In the first study, male 12-week-old Wistar-Kyoto rats were injected intraperitoneally with vehicle (saline), CLEN (0.004 or 0.02 mg/kg), or DEX (0.02 or 0.1 mg/kg). Since dual therapy is commonly used, in the second study, rats received either saline or combined CLEN + DEX (each at 0.005 or 0.02 mg/kg) one day prior to and on both days of exposure (air or 0.8ppm ozone, 4 hr/day x 2-days). In air-exposed rats CLEN, DEX or CLEN + DEX did not induce lung injury or inflammation, however DEX and CLEN + DEX decreased circulating lymphocytes, spleen and thymus weights, increased free fatty acids (FFA) and produced hyperglycemia and glucose intolerance. Ozone exposure of vehicle-treated rats increased bronchoalveolar lavage fluid protein, albumin, neutrophils, IL-6 and TNF-α. Ozone decreased circulating lymphocytes, increased FFA, and induced hypeerglycemia  and glucose intolerance. Drug treatment did not reverse ozone-induced ventillatory changes, however, lung effects (protein and albumin leakage, inflammation, and IL-6 increase) were exacerbated by CLEN and CLEN + DEX pre-treatment in a dose-dependent manner (CLEN > CLEN + DEX). Systemic effects induced by DEX and CLEN + DEX but not CLEN in air-exposed rats were analogous to and more pronounced than those induced by ozone. These data suggest that adverse air pollution effects might be exacerbated in people receiving LABA or LABA plus glucocorticoids.

ERS/EAACI statement on severe exacerbations in asthma in adults: facts, priorities and key research questions

Despite the use of effective medications to control asthma, severe exacerbations in asthma are still a major health risk and require urgent action on the part of the patient and physician to prevent serious outcomes such as hospitalisation or death. Moreover, severe exacerbations are associated with substantial healthcare costs and psychological burden, including anxiety and fear for patients and their families. The European Academy of Allergy and Clinical Immunology (EAACI) and the European Respiratory Society (ERS) set up a task force to search for a clear definition of severe exacerbations, and to also define research questions and priorities. The statement includes comments from patients who were members of the task force.

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

The effects of phosphodiesterase (PDE) 4 inhibitors on gene expression changes in BEAS-2B human airway epithelial cells are reported and discussed in relation to the mechanism(s) of action of roflumilast in chronic obstructive pulmonary disease (COPD). Microarray-based gene expression profiling failed to identify mRNA transcripts that were differentially regulated by the PDE4 inhibitor 6-[3-(dimethylcarbamoyl)benzenesulphonyl]-4-[(3-methoxyphenyl)amino]-8-methylquinoline-3-carboxamide (GSK 256066) after 1, 2, 6, or 18 hours of exposure. However, real-time polymerase chain reaction analysis revealed that GSK 256066 was a weak stimulus, and the negative microarray results reflected low statistical power due to small sample sizes. Furthermore, GSK 256066, roflumilast, and its biologically active metabolite roflumilast N-oxide generally potentiated gene expression changes produced by the long-acting β 2-adrenoceptor agonists (LABAs) salmeterol, indacaterol, and formoterol. Many of these genes encode proteins with antiviral, anti-inflammatory, and antibacterial activities that could contribute to the clinical efficacy of roflumilast in COPD. RNA-sequencing experiments established that the sensitivity of genes to salmeterol varied by ∼7.5-fold. Consequently, the degree to which a PDE4 inhibitor potentiated the effect of a given concentration of LABA was gene-dependent. Operational model fitting of concentration-response curve data from cells subjected to fractional, β 2-adrenoceptor inactivation determined that PDE4 inhibition increased the potency and doubled the efficacy of LABAs. Thus, adding roflumilast to standard triple therapy, as COPD guidelines recommend, may have clinical relevance, especially in target tissues where LABAs behave as partial agonists. Collectively, these results suggest that the genomic impact of roflumilast, including its ability to augment LABA-induced gene expression changes, may contribute to its therapeutic activity in COPD.