Synergistic inhibition by beta(2)-agonists and corticosteroids on tumor necrosis factor-alpha-induced interleukin-8 release from cultured human airway smooth-muscle cells

Epigenomic response to albuterol treatment in asthma-relevant airway epithelial cells

BACKGROUND

Albuterol is the first-line asthma medication used in diverse populations. Although DNA methylation (DNAm) is an epigenetic mechanism involved in asthma and bronchodilator drug response (BDR), no study has assessed whether albuterol could induce changes in the airway epithelial methylome. We aimed to characterize albuterol-induced DNAm changes in airway epithelial cells, and assess potential functional consequences and the influence of genetic variation and asthma-related clinical variables.

RESULTS

We followed a discovery and validation study design to characterize albuterol-induced DNAm changes in paired airway epithelial cultures stimulated in vitro with albuterol. In the discovery phase, an epigenome-wide association study using paired nasal epithelial cultures from Puerto Rican children (n = 97) identified 22 CpGs genome-wide associated with repeated-use albuterol treatment (p < 9 × 10-8). Albuterol predominantly induced a hypomethylation effect on CpGs captured by the EPIC array across the genome (probability of hypomethylation: 76%, p value = 3.3 × 10-5). DNAm changes on the CpGs cg23032799 (CREB3L1), cg00483640 (MYLK4-LINC01600), and cg05673431 (KSR1) were validated in nasal epithelia from 10 independent donors (false discovery rate [FDR] < 0.05). The effect on the CpG cg23032799 (CREB3L1) was cross-tissue validated in bronchial epithelial cells at nominal level (p = 0.030). DNAm changes in these three CpGs were shown to be influenced by three independent genetic variants (FDR < 0.05). In silico analyses showed these polymorphisms regulated gene expression of nearby genes in lungs and/or fibroblasts including KSR1 and LINC01600 (6.30 × 10-14 ≤ p ≤ 6.60 × 10-5). Additionally, hypomethylation at the CpGs cg10290200 (FLNC) and cg05673431 (KSR1) was associated with increased gene expression of the genes where they are located (FDR < 0.05). Furthermore, while the epigenetic effect of albuterol was independent of the asthma status, severity, and use of medication, BDR was nominally associated with the effect on the CpG cg23032799 (CREB3L1) (p = 0.004). Gene-set enrichment analyses revealed that epigenomic modifications of albuterol could participate in asthma-relevant processes (e.g., IL-2, TNF-α, and NF-κB signaling pathways). Finally, nine differentially methylated regions were associated with albuterol treatment, including CREB3L1, MYLK4, and KSR1 (adjusted p value < 0.05).

CONCLUSIONS

This study revealed evidence of epigenetic modifications induced by albuterol in the mucociliary airway epithelium. The epigenomic response induced by albuterol might have potential clinical implications by affecting biological pathways relevant to asthma.

Glucocorticoid Insensitivity in Asthma: The Unique Role for Airway Smooth Muscle Cells

Although most patients with asthma symptoms are well controlled by inhaled glucocorticoids (GCs), a subgroup of patients suffering from severe asthma respond poorly to GC therapy. Such GC insensitivity (GCI) represents a profound challenge in managing patients with asthma. Even though GCI in patients with severe asthma has been investigated by several groups using immune cells (peripheral blood mononuclear cells and alveolar macrophages), uncertainty exists regarding the underlying molecular mechanisms in non-immune cells, such as airway smooth cells (ASM) cells. In asthma, ASM cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here summarize the current understanding of the actions/signaling of GCs in asthma, and specifically, GC receptor (GR) “site-specific phosphorylation” and its role in regulating GC actions. We also review some common pitfalls associated with studies investigating GCI and the inflammatory mediators linked to asthma severity. Finally, we discuss and contrast potential molecular mechanisms underlying the impairment of GC actions in immune cells versus non-immune cells such as ASM cells.

Synergy across the drugs approved for the treatment of asthma

INTRODUCTION

Inhaled corticosteroids are the cornerstone for the treatment of stable asthma, however, when disease severity increases, escalating therapy to combinations of drugs acting on distinct signalling pathways is required. It is advantageous to providing evidence of a synergistic interaction across drug combinations, as it allows optimizing bronchodilation while lowering the dose of single agents. In the respiratory pharmacology field, two statistical models are accepted as gold standard to characterize drug interactions, namely the Bliss Independence criterion and the Unified Theory. In this review, pharmacological interactions across drugs approved for the treatment of asthma have been systematically assessed.

EVIDENCE ACQUISITION

A comprehensive literature search was performed in MEDLINE for studies that used a validated pharmacological method for assessing drug interaction. The results were extracted and reported via qualitative synthesis.

EVIDENCE SYNTHESIS

Overall, 45 studies were identified from literature search and 5 met the inclusion criteria. Current evidence coming from ex vivo models of asthma indicates that drug combinations modulating bronchial contractility induce a synergistic bronchorelaxant effect. In murine models of lung inflammation, the combination between inhaled corticosteroids and β2- adrenoceptor agonists synergistically improve lung function and the inflammatory profile.

CONCLUSIONS

There is still limited knowledge regarding the mechanistic basis underlying pharmacological interactions across drugs approved for asthma. The synergism elicited by combined agents is an effect of class. Specifically designed clinical trials are needed to confirm the results coming from preclinical evidence, but also to establish the minimal dose for combined agents to induce a synergistic interaction and maximize bronchodilation.

Important lessons learned from studies on the pharmacology of glucocorticoids in human airway smooth muscle cells: Too much of a good thing may be a problem

Glucocorticoids (GCs) are the treatment of choice for chronic inflammatory diseases such as asthma. Despite proven effective anti-inflammatory and immunosuppressive effects, long-term and/or systemic use of GCs can potentially induce adverse effects. Strikingly, some recent experimental evidence suggests that GCs may even exacerbate some disease outcomes. In asthma, airway smooth muscle (ASM) cells are among the targets of GC therapy and have emerged as key contributors not only to bronchoconstriction, but also to airway inflammation and remodeling, as implied by experimental and clinical evidence. We here will review the beneficial effects of GCs on ASM cells, emphasizing the differential nature of GC effects on pro-inflammatory genes and on other features associated with asthma pathogenesis. We will also summarize evidence describing how GCs can potentially promote pro-inflammatory and remodeling features in asthma with a specific focus on ASM cells. Finally, some of the possible solutions to overcome these unanticipated effects of GCs will be discussed.

Benefit:Risk Profile of Budesonide in Obstructive Airways Disease

Airway inflammation is a major contributing factor in both asthma and chronic obstructive pulmonary disease (COPD) and represents an important target for treatment. Inhaled corticosteroids (ICS) as monotherapy or in combination therapy with long-acting β₂-agonists or long-acting muscarinic antagonists are used extensively in the treatment of asthma and COPD. The development of ICS for their anti-inflammatory properties progressed through efforts to increase topical potency and minimise systemic potency and through advances in inhaled delivery technology. Budesonide is a potent, non-halogenated ICS that was developed in the early 1970s and is now one of the most widely used lung medicines worldwide. Inhaled budesonide's physiochemical and pharmacokinetic/pharmacodynamic properties allow it to reach a rapid and high airway efficacy due to its more balanced relationship between water solubility and lipophilicity. When absorbed from the airways and lung tissue, its moderate lipophilicity shortens systemic exposure, and its unique property of intracellular esterification acts like a sustained release mechanism within airway tissues, contributing to its airway selectivity and a low risk of adverse events. There is a large volume of clinical evidence supporting the efficacy and safety of budesonide, both alone and in combination with the fast- and long-acting β₂-agonist formoterol, as maintenance therapy in patients with asthma and with COPD. The combination of budesonide/formoterol can also be used as an as-needed reliever with anti-inflammatory properties, with or without regular maintenance for asthma, a novel approach that is already approved by some country-specific regulatory authorities and currently recommended in the Global Initiative for Asthma (GINA) guidelines. Budesonide remains one of the most well-established and versatile of the inhaled anti-inflammatory drugs. This narrative review provides a clinical reappraisal of the benefit:risk profile of budesonide in the management of asthma and COPD.

Extracellular acidification-induced CXCL8 production through a proton-sensing receptor OGR1 in human airway smooth muscle cells: a response inhibited by dexamethasone

Background

Human airway smooth muscle cells (ASMCs) contribute to bronchial contraction and airway hyperresponsiveness in patients with bronchial asthma. They also generate cytokines, chemokines, and matricellular proteins. Ovarian cancer G protein-coupled receptor 1 (OGR1) senses extracellular protons and mediates the production of interleukin-6 (IL-6) and connective tissue growth factor (CTGF) in ASMCs.

Methods

ASMCs were stimulated for the indicated time by pH 6.3 or pH 7.4-adjusted Dulbecco’s Modified Eagle Medium (DMEM) containing 0.1% bovine serum albumin (BSA) (0.1% BSA-DMEM). As a control stimulant, pH 7.4-adjusted 0.1% BSA-DMEM containing 10 ng/mL tumor necrosis factor-α (TNF-α) was used. Interleukin-8/C-X-C motif chemokine ligand 8 (CXCL8) mRNA expression in ASMCs was quantified by RT-PCR using real-time TaqMan technology. CXCL8 secreted from ASMCs was measured by enzyme-linked immunosorbent assay (ELISA). Phosphorylation at serine 536 of NF-κB p65 and binding of p65 to oligonucleotide containing an NF-κB consensus binding site were analyzed by Western blotting and an ELISA-based kit.

Results

Acidic pH induced a significant increase of CXCL8 mRNA expression and CXCL8 protein secretion in ASMCs. ASMCs transfected with small interfering RNA (siRNA) targeted for OGR1 produced less CXCL8 compared with those transfected with non-targeting siRNA. Protein kinase C (PKC) inhibitor, MEK1/2 inhibitor, and the inhibitor of IκB phosphorylation reduced acidic pH-stimulated CXCL8 production in ASMCs. Dexamethasone also inhibited acidic pH-stimulated CXCL8 production of ASMCs in a dose-dependent manner. Dexamethasone did not affect either phosphorylation or binding to the consensus DNA site of NF-κB p65.

Conclusions

CXCL8 released from ASMCs by extracellular acidification may play a pivotal role in airway accumulation of neutrophils. Glucocorticoids inhibit acidic pH-stimulated CXCL8 production independent of serine 536 phosphorylation and the binding to DNA of NF-κB p65, although NF-κB activity is essential for CXCL8 production in ASMCs.

Routine Use of Budesonide/Formoterol Fixed Dose Combination in Elderly Asthmatic Patients: Practical Considerations

Asthma has been demonstrated to be as common in the elderly as in younger age groups. Although no specific recommendations exist to manage the disease differently in older individuals, functional features and clinical presentations may be affected by age per se, and by age-related conditions, such as comorbidities and polypharmacy. In this review article, we aimed to explore the efficacy and safety in elderly asthmatic patients of one of the most currently used inhaled treatments for asthma, that is, the fixed-dose combination of budesonide/formoterol. We attempted to address some practical questions that are relevant to the daily practice of clinicians. We focused on the efficacy and real-world effectiveness of inhaled corticosteroids and long-acting β-adrenergic bronchodilators (ICS/LABA) as treatment in the elderly population, since data are extrapolated from younger populations. We investigated whether a maintenance and reliever therapy approach is more effective in the elderly as opposed to maintenance regimens, from both the general practitioner's and the pulmonologist's perspective. To address these questions, we scanned electronic databases (PubMed, MEDLINE, Embase, Scopus and Google Scholar) from the date of inception up to October 2016 with a cross-search using the following keywords: 'asthma', 'elderly', 'SMART therapy', 'MART therapy', 'Turbuhaler', and 'budesonide/formoterol'. The available literature on the topic confirms that when the age-associated changes are properly managed in clinical practice, asthma in older populations can be optimally controlled with inhaled treatment including ICS/LABA. This also applies for the budesonide/formoterol fixed combination, thus allowing for the maintenance and reliever therapy approach.

β2-Adrenoceptor Function in Asthma

β2-adrenoceptor agonists, often used in combination with corticosteroids, have been extensively used for the treatment of asthma. However, concerns have been raised regarding their adverse effects and safety including poor asthma control, life-threatening exacerbations, exacerbations that often require hospitalization, and asthma-related deaths. The question as to whether these adverse effects relate to the loss of their bronchoprotective action remains an interesting possibility. In the chapter, we will review the experimental evidence that describes the different potential factors and associated mechanisms that can blunt the therapeutic action of β2-adrenoceptor agonists in asthma. We show here evidence that various key inflammatory cytokines, growth factors, some respiratory viruses, certain allergens, unknown factors present in serum from atopic asthmatics have the capacity to impair β2-adrenoceptor function in airway smooth muscle, the main target of these drugs. More importantly, we present our latest research describing the role played by mast cells in impairing β2-adrenoceptor function. Although no definitive conclusion could be made regarding the implication of one single mechanism, receptor uncoupling, or receptor desensitization due to phosphorylation represents the main inhibitory pathways associated with a loss of β2-adrenoceptor function in airway smooth muscle. Targeting the pathways leading to β2-adrenoceptor dysfunction will likely provide novel therapies to improve the efficacy of β2-agonists in asthma.

β2-receptor agonists salbutamol and terbutaline attenuated cytokine production by suppressing ERK pathway through cAMP in macrophages

β₂-receptor agonists are used in the treatment of inflammatory obstructive lung diseases asthma and COPD as a symptomatic remedy, but they have been suggested to possess anti-inflammatory properties, also. β₂-receptor activation is considered to lead to the activation of ERK pathway through G-protein- and cAMP-independent mechanisms. In this study, we investigated the effects of β₂-receptor agonists salbutamol and terbutaline on the production of inflammatory factors in macrophages. We found that β₂-receptor agonists inhibited LPS-induced ERK phosphorylation and the production of MCP-1. A chemical cAMP analog 8-Br-cAMP also inhibited ERK phosphorylation and TNF and MCP-1 release. As expected, MAPK/ERK kinase (MEK)1/2 inhibitor PD0325901 inhibited ERK phosphorylation and suppressed both TNF and MCP-1 production. In conclusion, we suggest that β₂-receptor agonists salbutamol and terbutaline inhibit inflammatory gene expression partly by a mechanism dependent on cAMP leading to the inhibition of ERK signaling in macrophages. Observed anti-inflammatory effects of β₂-receptor agonists may contribute to the clinical effects of these drugs.

Understanding how long-acting β2 -adrenoceptor agonists enhance the clinical efficacy of inhaled corticosteroids in asthma - an update

In moderate-to-severe asthma, adding an inhaled long-acting β₂ -adenoceptor agonist (LABA) to an inhaled corticosteroid (ICS) provides better disease control than simply increasing the dose of ICS. Acting on the glucocorticoid receptor (GR, gene NR3C1), ICSs promote anti-inflammatory/anti-asthma gene expression. In vitro, LABAs synergistically enhance the maximal expression of many glucocorticoid-induced genes. Other genes, including dual-specificity phosphatase 1(DUSP1) in human airways smooth muscle (ASM) and epithelial cells, are up-regulated additively by both drug classes. Synergy may also occur for LABA-induced genes, as illustrated by the bronchoprotective gene, regulator of G-protein signalling 2 (RGS2) in ASM. Such effects cannot be produced by either drug alone and may explain the therapeutic efficacy of ICS/LABA combination therapies. While the molecular basis of synergy remains unclear, mechanistic interpretations must accommodate gene-specific regulation. We explore the concept that each glucocorticoid-induced gene is an independent signal transducer optimally activated by a specific, ligand-directed, GR conformation. In addition to explaining partial agonism, this realization provides opportunities to identify novel GR ligands that exhibit gene expression bias. Translating this into improved therapeutic ratios requires consideration of GR density in target tissues and further understanding of gene function. Similarly, the ability of a LABA to interact with a glucocorticoid may be suboptimal due to low β₂ -adrenoceptor density or biased β₂ -adrenoceptor signalling. Strategies to overcome these limitations include adding-on a phosphodiesterase inhibitor and using agonists of other Gs-coupled receptors. In all cases, the rational design of ICS/LABA, and derivative, combination therapies requires functional knowledge of induced (and repressed) genes for therapeutic benefit to be maximized.

Combined inhaled corticosteroid and long-acting β2-adrenergic agonist therapy for noncystic fibrosis bronchiectasis with airflow limitation: An observational study

BACKGROUND AND OBJECTIVE

There is presently no clear evidence on the effect of combined treatment for non-cystic fibrosis (non-CF) bronchiectasis with inhaled corticosteroid (ICS) and long-acting β2-adrenergic agonist (LABA). The objective of this study is to assess the efficacy and safety of salmeterol-fluticasone combined inhaled therapy for non-CF bronchiectasis with airflow limitation.

METHODS

An observational study was performed in 120 non-CF bronchiectasis patients diagnosed by high-resolution computed tomography (HRCT) scanning of the chest. Patients received either routine therapy or salmeterol-fluticasone (100/500 μg daily) combined inhaled therapy on the basis of routine therapy. Clinical symptoms, health-related quality of life (HRQL), lung function, short-acting β2-adrenergic agonist (SABA) use, and safety were monitored throughout the study.

RESULTS

OF the 120 subjects, 60 received combined inhaled therapy and 60 received routine therapy. Compared to the control group, the combined inhaled therapy group showed significant improvement in their clinical symptom scores (-2.21 vs. -0.31, P = 0.002) and a reduction in number of weekly SABA usage (-4.2 vs. 0.1, P < 0.01). In addition, patients in the inhaled therapy group achieved a significant improvement in HRQL based on mMRC (-1.51 vs. -0.31, P < 0.005) and SGRQ (-7.83 vs. -2.16, P < 0.01) scoring accompanied with no severe adverse events. There were fewer exacerbation frequencies in the combined inhaled therapy group over the 12 months of treatment compared to the control group (1 [0-2] vs. 2 [1-4], P = 0.017). Furthermore, stratified analysis indicated that combined inhaled therapy partially improve lung function for patients for whom it is severely impaired and those with pseudomonas aeruginosa isolated.

CONCLUSION

Our results show that salmeterol-fluticasone combined inhaled therapy should be effective and safe for non-CF bronchiectasis patients especially for those patients with poor lung function or pseudomonas aeruginosa isolated.

Fetal human airway smooth muscle cell production of leukocyte chemoattractants is differentially regulated by fluticasone

BACKGROUND

Adult human airway smooth muscle (ASM) produce cytokines involved in recruitment and survival of leukocytes within airway walls. Cytokine generation by adult ASM is glucocorticoid-sensitive. Whether developing lung ASM produces cytokines in a glucocorticoid-sensitive fashion is unknown.

METHODS

Cultured fetal human ASM cells stimulated with TNF-α (0-20 ng/ml) were incubated with TNF-α receptor-blocking antibodies, fluticasone (1 and 100 nm), or vehicle. Supernatants and cells were assayed for the production of CCL5, CXCL10, and CXCL8 mRNA and protein and glucocorticoid receptor phosphorylation.

RESULTS

CCL5, CXCL10, and CXCL8 mRNA and protein production by fetal ASM cell was significantly and dose-dependently following TNF-α treatment. Cytokine mRNA and protein production were effectively blocked by TNF-α R1 and R2 receptor neutralizing antibodies but variably inhibited by fluticasone. TNF-α-induced TNF-R1 and R2 receptor mRNA expression was only partially attenuated by fluticasone. Glucocorticoid receptor phosphorylation at serine (Ser) 211 but not at Ser 226 was enhanced by fluticasone.

CONCLUSION

Production of CCL5, CXCL10, and CXCL8 by fetal ASM appears to involve pathways that are both qualitatively and mechanistically distinct to those described for adult ASM. The findings imply developing ASM has potential to recruit leukocyte into airways and, therefore, of relevance to childhood airway diseases.

Why use long acting bronchodilators in chronic obstructive lung diseases? An extensive review on formoterol and salmeterol

Long-acting β2-adrenoceptor agonists, formoterol and salmeterol, represent a milestone in the treatments of chronic obstructive lung diseases. Although no specific indications concerning the choice of one molecule rather than another are provided by asthma and COPD guidelines, they present different pharmacological properties resulting in distinct clinical employment possibilities. In particular, salmeterol has a low intrinsic efficacy working as a partial receptor agonist, while formoterol is a full agonist with high intrinsic efficacy. From a clinical perspective, in the presence of low β2-adrenoceptors availability, like in inflamed airways, a full agonist can maintain its bronchodilatory and non-smooth muscle activities while a partial agonist may be less effective. Furthermore, formoterol presents a faster onset of action than salmeterol. This phenomenon, combined with the molecule safety profile, leads to a prompt amelioration of the symptoms, and allows using this drug in asthma as an "as needed" treatment in patients already on regular treatment. The fast onset of action and the full agonism of formoterol need to be considered in order to select the best pharmacological treatment of asthma and COPD.

Protective Effects of Clenbuterol against Dexamethasone-Induced Masseter Muscle Atrophy and Myosin Heavy Chain Transition

Background

Glucocorticoid has a direct catabolic effect on skeletal muscle, leading to muscle atrophy, but no effective pharmacotherapy is available. We reported that clenbuterol (CB) induced masseter muscle hypertrophy and slow-to-fast myosin heavy chain (MHC) isoform transition through direct muscle β2-adrenergic receptor stimulation. Thus, we hypothesized that CB would antagonize glucocorticoid (dexamethasone; DEX)-induced muscle atrophy and fast-to-slow MHC isoform transition.

Methodology

We examined the effect of CB on DEX-induced masseter muscle atrophy by measuring masseter muscle weight, fiber diameter, cross-sectional area, and myosin heavy chain (MHC) composition. To elucidate the mechanisms involved, we used immunoblotting to study the effects of CB on muscle hypertrophic signaling (insulin growth factor 1 (IGF1) expression, Akt/mammalian target of rapamycin (mTOR) pathway, and calcineurin pathway) and atrophic signaling (Akt/Forkhead box-O (FOXO) pathway and myostatin expression) in masseter muscle of rats treated with DEX and/or CB.

Results and Conclusion

Masseter muscle weight in the DEX-treated group was significantly lower than that in the Control group, as expected, but co-treatment with CB suppressed the DEX-induced masseter muscle atrophy, concomitantly with inhibition of fast-to-slow MHC isoforms transition. Activation of the Akt/mTOR pathway in masseter muscle of the DEX-treated group was significantly inhibited compared to that of the Control group, and CB suppressed this inhibition. DEX also suppressed expression of IGF1 (positive regulator of muscle growth), and CB attenuated this inhibition. Myostatin protein expression was unchanged. CB had no effect on activation of the Akt/FOXO pathway. These results indicate that CB antagonizes DEX-induced muscle atrophy and fast-to-slow MHC isoform transition via modulation of Akt/mTOR activity and IGF1 expression. CB might be a useful pharmacological agent for treatment of glucocorticoid-induced muscle atrophy.

Superiority of combined phosphodiesterase PDE3/PDE4 inhibition over PDE4 inhibition alone on glucocorticoid- and long-acting β2-adrenoceptor agonist-induced gene expression in human airway epithelial cells

Glucocorticoids, also known as corticosteroids, induce effector gene transcription as a part of their anti-inflammatory mechanisms of action. Such genomic effects can be significantly enhanced by long-acting β2-adrenoceptor agonists (LABAs) and may contribute to the clinical superiority of inhaled corticosteroid (ICS)/LABA combinations in asthma and chronic obstructive pulmonary disease (COPD) over ICSs alone. Using models of cAMP- and glucocorticoid-induced transcription in human bronchial epithelial BEAS-2B cells, we show that combining inhibitors of phosphodiesterase (PDE) 3 and PDE4 provides greater benefits compared with inhibiting either PDE alone. In respect to cAMP-dependent transcription, inhibitors of PDE3 (siguazodan, cilostazol) and PDE4 (rolipram, GSK256066, roflumilast N-oxide) each sensitized to the LABA, formoterol. This effect was magnified by dual PDE3 and PDE4 inhibition. Siguazodan plus rolipram was also more effective at inducing cAMP-dependent transcription than either inhibitor alone. Conversely, the concentration-response curve describing the enhancement of dexamethasone-induced, glucocorticoid response element-dependent transcription by formoterol was displaced to the left by PDE4, but not PDE3, inhibition. Overall, similar effects were described for bona fide genes, including RGS2, CD200, and CRISPLD2. Importantly, the combination of siguazodan plus rolipram prolonged the duration of gene expression induced by formoterol, dexamethasone, or dexamethasone plus formoterol. This was most apparent for RGS2, a bronchoprotective gene that may also reduce the proinflammatory effects of constrictor mediators. Collectively, these data provide a rationale for the use of PDE3 and PDE4 inhibitors in the treatment of COPD and asthma where they may enhance, sensitize, and prolong the effects of LABA/ICS combination therapies.

Novel drug targets for asthma and COPD: lessons learned from in vitro and in vivo models

Asthma and chronic obstructive pulmonary disease (COPD) are highly prevalent respiratory diseases characterized by airway inflammation, airway obstruction and airway hyperresponsiveness. Whilst current therapies, such as β-agonists and glucocorticoids, may be effective at reducing symptoms, they do not reduce disease progression. Thus, there is a need to identify new therapeutic targets. In this review, we summarize the potential of novel targets or tools, including anti-inflammatories, phosphodiesterase inhibitors, kinase inhibitors, transient receptor potential channels, vitamin D and protease inhibitors, for the treatment of asthma and COPD.

Inhibition of phosphodiesterase 4 modulates cytokine induction from toll like receptor activated, but not rhinovirus infected, primary human airway smooth muscle

Background

Virus-induced exacerbations of Chronic Obstructive Pulmonary Disease (COPD) are a significant health burden and occur even in those receiving the best current therapies. Rhinovirus (RV) infections are responsible for half of all COPD exacerbations. The mechanism by which exacerbations occur remains undefined, however it is likely to be due to virus-induced inflammation. Given that phophodiesterase 4 (PDE₄) inhibitors have an anti-inflammatory effect in patients with COPD they present a potential therapy prior to, and during, these exacerbations.

Methods

In the present study we investigated whether the PDE₄ inhibitor piclamilast (10^-6 M) could alter RV or viral mimetic (5 μg/mL of imiquimod or poly I:C) induced inflammation and RV replication in primary human airway smooth muscle cells (ASMC) and bronchial epithelial cells (HBEC). The mediators IL-6, IL-8, prostaglandin E₂ and cAMP production were assayed by ELISA and RV replication was assayed by viral titration.

Results

We found that in ASMCs the TLR3 agonist poly I:C induced IL-8 release was reduced while induced IL-6 release by the TLR7/8 agonist imiquimod was further increased by the presence of piclamilast. However, in RV infected ASMCs, virus replication and induced mediator release were unaltered by piclamilast, as was also found in HBECs. The novel findings of this study reveal that although PDE inhibitors may not influence RV-induced cytokine production in ASMCs and replication in either ASMCs or HBECs, they have the capacity to be anti-inflammatory during TLR activation by modulating the induction of these chemotactic cytokines.

Conclusion

By extrapolating our in vitro findings to exacerbations of COPD in vivo this suggests that PDE₄ inhibitors may have beneficial anti-inflammatory properties when patients are infected with bacteria or viruses other than RV.

Induction of regulator of G-protein signaling 2 expression by long-acting β2-adrenoceptor agonists and glucocorticoids in human airway epithelial cells

In asthma and chronic obstructive pulmonary disease (COPD) multiple mediators act on Gαq-linked G-protein-coupled receptors (GPCRs) to cause bronchoconstriction. However, acting on the airway epithelium, such mediators may also elicit inflammatory responses. In human bronchial epithelial BEAS-2B cells (bronchial epithelium + adenovirus 12-SV40 hybrid), regulator of G-protein signaling (RGS) 2 mRNA and protein were synergistically induced in response to combinations of long-acting β2-adrenoceptor agonist (LABA) (salmeterol, formoterol) plus glucocorticoid (dexamethasone, fluticasone propionate, budesonide). Equivalent responses occurred in primary human bronchial epithelial cells. Concentrations of glucocorticoid plus LABA required to induce RGS2 expression in BEAS-2B cells were consistent with the levels achieved therapeutically in the lungs. As RGS2 is a GTPase-activating protein that switches off Gαq, intracellular free calcium ([Ca(2+)]i) flux was used as a surrogate of responses induced by histamine, methacholine, and the thromboxane receptor agonist U46619 [(Z)-7-[(1S,4R,5R,6S)-5-[(E,3S)-3-hydroxyoct-1-enyl]-3-oxabicyclo[2.2.1]heptan-6-yl]hept-5-enoic acid]. This was significantly attenuated by salmeterol plus dexamethasone pretreatment, or RGS2 overexpression, and the protective effect of salmeterol plus dexamethasone was abolished by RGS2 RNA silencing. Although methacholine and U46619 induced interleukin-8 (IL-8) release and this was inhibited by RGS2 overexpression, the repression of U46619-induced IL-8 release by salmeterol plus dexamethasone was unaffected by RGS2 knockdown. Given a role for Gαq-mediated pathways in inducing IL-8 release, we propose that RGS2 acts redundantly with other effector processes to repress IL-8 expression. Thus, RGS2 expression is a novel effector mechanism in the airway epithelium that is induced by glucocorticoid/LABA combinations. This could contribute to the efficacy of glucocorticoid/LABA combinations in asthma and COPD.

Inhaled long-acting β2 agonists enhance glucocorticoid receptor nuclear translocation and efficacy in sputum macrophages in COPD

BACKGROUND

Combination inhaled therapy with long-acting β2 agonists (LABAs) and corticosteroids is beneficial in treating asthma and chronic obstructive pulmonary disease (COPD).

OBJECTIVE

In asthma, LABAs enhance glucocorticoid receptor (GR) nuclear translocation in the presence of corticosteroids. Whether this biological mechanism occurs in COPD, a relatively corticosteroid-resistant disease, is uncertain.

METHODS

Eight patients with mild/moderate COPD participated in a double-blind, placebo-controlled, crossover study and inhaled single doses of fluticasone propionate (FP) 100 μg, FP 500 μg, salmeterol xinafoate (SLM) 50 μg, and combination FP 100 μg + SLM 50 μg. One hour postinhalation, sputum was induced, nuclear proteins isolated from purified macrophages, and levels of activated nuclear GR quantified by using a GR-glucocorticoid response element ELISA-based assay.

RESULTS

Nuclear GR significantly increased after the inhalation of FP 500 μg (P < .01), but not after the inhalation of FP 100 μg or SLM 50 μg, compared with placebo. Interestingly, SLM in combination with FP 100 μg increased nuclear GR levels equivalent to those of FP 500 μg alone. This was significantly greater than either FP 100 μg (P < .05) or SLM 50 μg (P < .01) alone. In vitro in a human macrophage cell line, SLM (10(-8) mol/L) enhanced FP (10(-9) mol/L)-induced mitogen-activated protein kinase phosphatase-1 mRNA (5.8 ± 0.6 vs 8.4 ± 1.1 × 10(-6) copies, P < .05) and 2 × glucocorticoid response element-luciferase reporter gene activity (250.1 ± 15.6 vs 103.1 ± 23.6-fold induction, P < .001). Addition of SLM (10(-9) mol/L) to FP (10(-11) mol/L) significantly enhanced FP-mediated suppression of IL-1β-induced CXCL8 (P < .05).

CONCLUSIONS

Addition of SLM 50 μg to FP 100 μg enhanced GR nuclear translocation equivalent to that seen with a 5-fold higher dose of FP in sputum macrophages from patients with COPD. This may account for the superior clinical effects of combination LABA/corticosteroid treatment compared with either as monotherapy observed in COPD.

Long-acting β2-agonists increase fluticasone propionate-induced mitogen-activated protein kinase phosphatase 1 (MKP-1) in airway smooth muscle cells

Mitogen-activated protein kinase phosphatase 1 (MKP-1) represses MAPK-driven signalling and plays an important anti-inflammatory role in asthma and airway remodelling. Although MKP-1 is corticosteroid-responsive and increased by cAMP-mediated signalling, the upregulation of this critical anti-inflammatory protein by long-acting β2-agonists and clinically-used corticosteroids has been incompletely examined to date. To address this, we investigated MKP-1 gene expression and protein upregulation induced by two long-acting β2-agonists (salmeterol and formoterol), alone or in combination with the corticosteroid fluticasone propionate (abbreviated as fluticasone) in primary human airway smooth muscle (ASM) cells in vitro. β2-agonists increased MKP-1 protein in a rapid but transient manner, while fluticasone induced sustained upregulation. Together, long-acting β2-agonists increased fluticasone-induced MKP-1 and modulated ASM synthetic function (measured by interleukin 6 (IL-6) and interleukin 8 (IL-8) secretion). As IL-6 expression (like MKP-1) is cAMP/adenylate cyclase-mediated, the long-acting β2-agonist formoterol increased IL-6 mRNA expression and secretion. Nevertheless, when added in combination with fluticasone, β2-agonists significantly repressed IL-6 secretion induced by tumour necrosis factor α (TNFα). Conversely, as IL-8 is not cAMP-responsive, β2-agonists significantly inhibited TNFα-induced IL-8 in combination with fluticasone, where fluticasone alone was without repressive effect. In summary, long-acting β2-agonists increase fluticasone-induced MKP-1 in ASM cells and repress synthetic function of this immunomodulatory airway cell type.

cAMP regulation of airway smooth muscle function

Agonists activating β(2)-adrenoceptors (β(2)ARs) on airway smooth muscle (ASM) are the drug of choice for rescue from acute bronchoconstriction in patients with both asthma and chronic obstructive pulmonary disease (COPD). Moreover, the use of long-acting β-agonists combined with inhaled corticosteroids constitutes an important maintenance therapy for these diseases. β-Agonists are effective bronchodilators due primarily to their ability to antagonize ASM contraction. The presumed cellular mechanism of action involves the generation of intracellular cAMP, which in turn can activate the effector molecules cAMP-dependent protein kinase (PKA) and Epac. Other agents such as prostaglandin E(2) and phosphodiesterase inhibitors that also increase intracellular cAMP levels in ASM, can also antagonize ASM contraction, and inhibit other ASM functions including proliferation and migration. Therefore, β(2)ARs and cAMP are key players in combating the pathophysiology of airway narrowing and remodeling. However, limitations of β-agonist therapy due to drug tachyphylaxis related to β(2)AR desensitization, and recent findings regarding the manner in which β(2)ARs and cAMP signal, have raised new and interesting questions about these well-studied molecules. In this review we discuss current concepts regarding β(2)ARs and cAMP in the regulation of ASM cell functions and their therapeutic roles in asthma and COPD.

Thiazolidinediones inhibit airway smooth muscle release of the chemokine CXCL10: in vitro comparison with current asthma therapies

BACKGROUND

Activated mast cells are present within airway smooth muscle (ASM) bundles in eosinophilic asthma. ASM production of the chemokine CXCL10 plays a role in their recruitment. Thus the effects of glucocorticoids (fluticasone, budesonide), long-acting β2-agonists (salmeterol, formoterol) and thiazolidinediones (ciglitazone, rosiglitazone) on CXCL10 production by ASM cells (ASMC) from people with and without asthma were investigated in vitro.

METHODS

Confluent serum-deprived cells were treated with the agents before and during cytokine stimulation for 0-24 h. CXCL10 protein/mRNA, IκB-α levels and p65 activity were measured using ELISA, RT PCR, immunoblotting and p65 activity assays respectively. Data were analysed using ANOVA followed by Fisher's post-hoc test.

RESULTS

Fluticasone and/or salmeterol at 1 and 100 nM inhibited CXCL10 release induced by IL-1β and TNF-α, but not IFNγ or all three cytokines (cytomix). The latter was also not affected by budesonide and formoterol. In asthmatic ASMC low salmeterol, but not formoterol, concentrations increased cytomix-induced CXCL10 release and at 0.01 nM enhanced NF-κB activity. Salmeterol 0.1 nM together with fluticasone 0.1 and 10 nM still increased CXCL10 release. The thiazolidinediones ciglitazone and rosiglitazone (at 25 and 100 μM) inhibited cytomix-induced CXCL10 release but these inhibitory effects were not prevented by the PPAR-g antagonist GW9662. Ciglitazone did not affect early NF-κB activity and CXCL10 mRNA production.

CONCLUSIONS

Thus the thiazolidinediones inhibited asthmatic ASMC CXCL10 release under conditions when common asthma therapies were ineffective or enhanced it. They may provide an alternative strategy to reduce mast cell-ASM interactions and restore normal airway physiology in asthma.

Inhaled Salmeterol/Fluticasone Propionate Combination in Chronic Obstructive Pulmonary Disease

Salmeterol/fluticasone propionate is a fixed-dose combination of the long-acting beta2-adrenoceptor agonist salmeterol and the corticosteroid fluticasone propionate and is inhaled via the Diskus powder inhaler. In three randomized, double-blind, 24-week or 52-week studies in >2850 patients with chronic obstructive pulmonary disease (COPD), administration of salmeterol/fluticasone propionate 50/250 microg twice daily (in one study) and salmeterol/fluticasone propionate 50/500 microg twice daily (in the other studies) provided greater improvement in lung function than placebo or either component alone at the same nominal dosage. Both strengths of the combination product administered twice daily resulted in clinically meaningful increases in scores in health-related quality-of-life questionnaires that were specific for respiratory disease. Improvements in this and almost all other secondary measures of efficacy, including symptomatic outcomes, were significantly greater with the combination product than with placebo. Administration of salmeterol/fluticasone propionate as a combination product did not result in any untoward interactions that affected the pharmacodynamic, pharmacokinetic or tolerability profiles of the individual components. Candidiasis, hoarseness/dysphonia, throat irritation and headache occurred more frequently with salmeterol/fluticasone propionate than with placebo in patients with COPD.

Airway smooth muscle in asthma: just a target for bronchodilation?

Airway smooth muscle (ASM) has long been recognized as the main cell type responsible for bronchial hyperresponsiveness. It has, thus, been considered as a target for bronchodilation. In asthma, however, there is a complex relationship between ASM and inflammatory cells, such as mast cells and T lymphocytes. Moreover, the increased ASM mass in asthmatic airways is one of the key features of airway remodeling. This article aims to review the main concepts about the 3 possible roles of ASM in asthma: (1) contractile tone, (2) inflammatory response, and (3) remodeling.

Glucocorticoid-resistant asthma and novel anti-inflammatory drugs

Synthetic glucocorticoids are among the most commonly used prescription medicines. Nevertheless, their clinical efficacy is accompanied by dose- and indication-limiting acute and chronic adverse effects. Intrinsic or acquired resistance to glucocorticoid actions may also limit clinical efficacy. In chronic inflammatory conditions there has been a considerable focus on understanding mechanism(s) of resistance in cells with a primary immune and/or inflammatory function. However, it has become increasingly accepted that a substantial part of the efficacy of glucocorticoid treatments derives from actions on 'structural' cell types (smooth muscle, fibroblasts, epithelia). In this article we review the mechanism of action of glucocorticoids on structural cells and contrast knowledge of resistance mechanisms between structural and inflammatory cell types, using asthma as an exemplar chronic inflammatory condition associated with glucocorticoid resistance.

Corticosteroids in respiratory diseases in children

We review recent advances in the use of corticosteroids (CS) in pediatric lung disease. CS are frequently used, systemically or by inhalation. Their mechanisms of action in pulmonary diseases are ill defined. CS exert direct inhibitory effects on many inflammatory cells through genomic mechanisms. There is a time lag before clinical response, and the washout of effects is also prolonged. Prompt relief in some conditions, such as croup, may be related to airway mucosal vasoconstriction through a nongenomic mechanism. CS have proven beneficial roles in the treatment of asthma, croup, allergic bronchopulmonary aspergillosis, and subglottic hemangioma. In some conditions, such as bronchiolitis, cystic fibrosis, and bronchopulmonary dysplasia, their use is controversial and is not recommended routinely. In other conditions, such as tuberculosis, interstitial lung disease, acute lung aspiration, and acute respiratory distress syndrome, CS are often used empirically despite the lack of clear evidence of their benefit. New drug regimens, including the more flexible use of inhaled corticosteroids and long-acting β-agonists in asthma, the lack of efficacy of oral corticosteroids in preschool children with acute wheeze, the severe complications of systemic dexamethasone used to prevent bronchopulmonary dysplasia and thus more restricted use, and the beneficial effect of pulse high-dose intravenous methylprednisolone in patients with allergic bronchopulmonary aspergillosis or cystic fibrosis are among the major recent developments. There is concern about adverse effects, especially growth and adrenal suppression, induced by systemic CS in children. These have been reduced, but not eliminated, with the use of the inhaled route. The benefits must be weighed against the potential detrimental effects.

Increased corticosteroid sensitivity by a long acting β2 agonist formoterol via β2 adrenoceptor independent protein phosphatase 2A activation

Long-acting β2-adrenoceptor agonists (LABAs) are reported to enhance anti-inflammatory effects of corticosteroids in vitro and in vivo, although the molecular mechanisms have not yet been elucidated. We investigated the role of serine/threonine protein phosphatase 2A (PP2A) on regulation of corticosteroid sensitivity via inhibition of glucocorticoid receptor (GR) phosphorylation as the target of formoterol, an LABA. Corticosteroid sensitivity was determined as IC50 to dexamethasone (Dex) on TNFα-induced IL-8 release in a U937 monocytic cell line (Dex-IC50). Phosphorylation levels of GR-Ser226 and c-Jun N-terminal kinase (JNK) were determined by western-blotting. Phosphatase activity of immunopurified PP2A was measured by fluorescence-based assay. Exposure to IL-2/IL-4 for 48 h decreased Dex sensitivity with a concomitant increase of GR phosphorylation at Ser226 with JNK1 activation. Formoterol restored Dex sensitivity by inhibiting phosphorylation of GR-Ser226 and JNK1. PP2A inhibition by okadaic acid, a phosphatase inhibitor, abrogated formoterol-mediated effects. In addition, formoterol enhanced PP2A activity in intact or IL-2/IL-4 treated U937 cells and human peripheral blood mononuclear cells. In addition, PP2A activation by formoterol was not antagonized by ICI-118551, and formoterol could activate PP2A directly in cell free system. Taken together, formoterol increases corticosteroid sensitivity via activation of PP2A in receptor independent manner, explaining its benefits as add-on therapy for the treatment of corticosteroid-insensitive diseases, such as severe asthma.

Combined Beta-agonists and corticosteroids do not inhibit extracellular matrix protein production in vitro

Background. Persistent asthma is characterized by airway remodeling. Whereas we have previously shown that neither β(2)-agonists nor corticosteroids inhibit extracellular matrix (ECM) protein release from airway smooth muscle (ASM) cells, the effect of their combination is unknown and this forms the rationale for the present study. Methods. ASM cells from people with and without asthma were stimulated with TGFβ1 (1 ng/ml) with or without budesonide (10(-8) M) and formoterol (10(-10) and 10(-8) M), and fibronectin expression and IL-6 release were measured by ELISA. Bronchial rings from nonasthmatic individuals were incubated with TGFβ1 (1 ng/ml) with or without the drugs, and fibronectin expression was measured using immunohistochemistry. Results. Budesonide stimulated fibronectin deposition, in the presence or absence of TGFβ1, and this was partially reversed by formoterol (10(-8) M) in both asthmatic and nonasthmatic cells. Budesonide and formoterol in combination failed to inhibit TGFβ-induced fibronectin in either cell type. A similar pattern of expression of fibronectin was seen in bronchial rings. TGFβ1-induced IL-6 release was inhibited by the combination of drugs. Conclusion. Current combination asthma therapies are unable to prevent or reverse remodeling events regulated by ASM cells.

Effect of IL-1β and TNF-α vs IL-13 on bronchial hyperresponsiveness, β2-adrenergic responses and cellularity of bronchial alveolar lavage fluid

1 Levels of IL-13, IL-1β and TNF-α are increased in bronchial lavage fluid of asthmatics and induce certain significant features of bronchial asthma including airway hyper-responsiveness (AHR). In this study, we have investigated the effect of these cytokines in naïve mice and those sensitized to ovalbumin (OVA) on bronchoconstrictions to methacholine (MCh) and the functional antagonism induced by β2 -adrenoceptor agonism. 2 Naïve or OVA-sensitized mice were treated for 3 days with IL-1β (250 U), TNF-α (150 ng), IL-13 (5 μg) or combinations of IL-1β with TNF-α or IL-1β with IL-13. MCh-induced bronchoconstriction and its sensitivity to albuterol, a β2-adrenoceptor agonist, was assessed 24 h after the last cytokine administration. 3 In naïve mice, responsiveness to MCh was significantly increased by the combination of IL-1β and TNF-α, IL-13 alone or in combination with IL-1β, but not by treatment with IL-1β or TNF-α alone. Similar results were obtained in OVA-sensitized mice except that treatment with IL-13 alone did not increase sensitivity to MCh. 4 In naïve mice, albuterol sensitivity was only significantly attenuated by treatment with IL-1β and TNF-α in combination. In mice sensitized to OVA, albuterol sensitivity was significantly attenuated by treatment with TNF-α, IL-13 or IL-13 in combination with IL-1β. 5 Inflammatory cell influx was increased by all cytokines and combinations except IL-13 in OVA-sensitized mice. 6 Our data do not support a link between inflammatory cell influx and AHR. In addition, the mechanism of IL-13-induced AHR might involve decreased β2-adrenoceptor responsiveness.

TLR2 ligand engagement upregulates airway smooth muscle TNFα-induced cytokine production

Airway inflammation and respiratory infections are important factors contributing to disease exacerbation in chronic airway diseases such as asthma and chronic obstructive pulmonary disease. Airway smooth muscle (ASM) cells express Toll-like receptors (TLRs) and may be involved in the amplification of airway inflammatory responses during infectious exacerbations. We determined whether infectious stimuli (mimicked using Pam3CSK4, a synthetic bacterial lipopeptide that binds to TLR2/TLR1) further enhance ASM cell inflammatory responses to TNFα in vitro and the signaling pathways involved. Human ASM cells were pretreated for 1 h with Pam3CSK4 (1 μg/ml) in the absence or presence of TNFα (10 ng/ml), and IL-6 and IL-8 release was measured after 24 h. As expected, stimulation with Pam3CSK4 or TNFα alone induced significant IL-6 and IL-8 release. Furthermore, Pam3CSK4 significantly increased TNFα-induced IL-6 and IL-8 mRNA expression and protein release and neutrophil chemotactic activity. The potentiating effect of Pam3CSK4 on TNFα-induced inflammatory responses was not due to enhanced TLR2 expression nor did it involve augmentation of NF-κB or MAPK signaling pathways. Rather, Pam3CSK4 induced cAMP response element (CRE) binding protein phosphorylation and induced CRE-mediated transcriptional regulation, suggesting that Pam3CSK4 and TNFα are acting in concert to enhance ASM cytokine secretion via parallel transcriptional pathways. Our findings suggest that ASM cells may be involved in the amplification of airway inflammatory responses during infectious exacerbations in chronic airway disease.

Fluticasone propionate and Salmeterol combination induces SOCS-3 expression in airway epithelial cells

Fluticasone propionate (FP) and Salmeterol (SAL) are commonly used in combination therapy for patients with Chronic obstructive pulmonary disease (COPD). Clinical studies show that FP/SAL used in combination therapy was found to inhibit airway inflammation in COPD patients. However, the mechanisms associated with FP/SAL induced anti-inflammatory effects were not clear. We have evaluated the effect of FP/SAL and tobacco smoke (TS) on SOCS-3 and interleukine-6 expression in bronchial airway epithelial cells (BAEpCs). Human BAEpCs were exposed to TS and subsequently treated with FP or SAL alone or in combinations in the presence and absence of mitogen activated protein kinase (MAPK) inhibitors for either Erk1/Erk2, or p38 or PI3 kinase. In BAEpCs, TS induced IL-6 expression via ERK1/ERK2 MAPK pathway and FP/SAL inhibited TS mediated IL-6 expression. TS down regulated the SOCS-3 expression via activation of Erk1/Erk2, and p38 MAPK signaling. When TS exposed BAEpCs were treated with FP/SAL SOCS-3 expression was restored. FP/SAL combinations induced significantly higher expression of SOCS-3 in BAEpCs when compared to individual drug. Pretreatment with Ly294002 a PI3 MAPK inhibitor significantly attenuated FP/SAL induced SOCS-3 expression in BAEpCs. Furthermore, FP/SAL blunted TS induced phosphorylation of Erk1/Erk2 and p38 MAPK in BAEpCs. Our study suggests that TS inhibits SOCS-3, combination of FP/SAL has a profound synergistic effect on SOCS-3 induction in BAEpCs and it is dependent on PI3 kinase signaling pathway. SOCS-3 may represent a potential biomarker for understanding the efficacy and a novel anti-inflammatory mechanism of FP/SAL combination therapy in the treatment of COPD.

Budesonide and formoterol reduce early innate anti-viral immune responses in vitro

Asthma is a chronic inflammatory airways disease in which respiratory viral infections frequently trigger exacerbations. Current treatment of asthma with combinations of inhaled corticosteroids and long acting beta2 agonists improves asthma control and reduces exacerbations but what impact this might have on innate anti-viral immunity is unclear. We investigated the in vitro effects of asthma drugs on innate anti-viral immunity. Peripheral blood mononuclear cells (PBMC) from healthy and asthmatic donors were cultured for 24 hours with the Toll-like receptor 7 agonist, imiquimod, or rhinovirus 16 (RV16) in the presence of budesonide and/or formoterol. Production of proinflammatory cytokines and expression of anti-viral intracellular signalling molecules were measured by ELISA and RT-PCR respectively. In PBMC from healthy donors, budesonide alone inhibited IP-10 and IL-6 production induced by imiquimod in a concentration-dependent manner and the degree of inhibition was amplified when budesonide and formoterol were used in combination. Formoterol alone had little effect on these parameters, except at high concentrations (10⁻⁶ M) when IL-6 production increased. In RV16 stimulated PBMC, the combination of budesonide and formoterol inhibited IFNα and IP-10 production in asthmatic as well as healthy donors. Combination of budesonide and formoterol also inhibited RV16-stimulated expression of the type I IFN induced genes myxovirus protein A and 2′, 5′ oligoadenylate synthetise. Notably, RV16 stimulated lower levels of type Myxovirus A and oligoadenylate synthase in PBMC of asthmatics than control donors. These in vitro studies demonstrate that combinations of drugs commonly used in asthma therapy inhibit both early pro-inflammatory cytokines and key aspects of the type I IFN pathway. These findings suggest that budesonide and formoterol curtail excessive inflammation induced by rhinovirus infections in patients with asthma, but whether this inhibits viral clearance in vivo remains to be determined.

p38 mitogen-activated protein kinase-γ inhibition by long-acting β2 adrenergic agonists reversed steroid insensitivity in severe asthma

Corticosteroid insensitivity (CI) is a major barrier to treating severe asthma. Despite intensive research, the molecular mechanism of CI remains uncertain. The aim of this study was to determine abnormality in corticosteroid action in severe asthma and to identify the molecular mechanism of the long-acting β(2)-adrenergic agonists (LABAs) formoterol and salmeterol on restoration of corticosteroid sensitivity in severe asthma in vitro. Peripheral blood mononuclear cells (PBMCs) were obtained from 16 subjects with severe corticosteroid-insensitive asthma, 6 subjects with mild corticosteroid-sensitive asthma, and 11 healthy volunteers. Corticosteroid (dexamethasone) sensitivity was determined on tumor necrosis factor-α (TNF-α)-induced interleukin (IL)-8 production. Glucocorticoid receptor (GR) phosphorylation and kinase phosphorylation were evaluated by immunoprecipitation-Western blotting analysis and kinase phosphorylation array in IL-2/IL-4-treated corticosteroid insensitive model in PBMCs. In vitro corticosteroid sensitivity on TNF-α-induced IL-8 production was significantly lower in patients with severe asthma than in healthy volunteers and patients with mild asthma. This CI seen in severe asthma was associated with reduced GR nuclear translocation and with hyperphosphorylation of GR, which were reversed by LABAs. In IL-2/IL-4-treated PBMCs, LABAs inhibited phosphorylation of Jun-NH(2)-terminal kinase and p38 mitogen-activated protein kinase-γ (p38MAPK-γ) as well as GR. In addition, cells with p38MAPK-γ knockdown by RNA interference did not develop CI in the presence of IL-2/IL-4. Furthermore, p38MAPK-γ protein expression was up-regulated in PBMCs from some patients with severe asthma. In conclusion, p38 MAPK-γ activation impairs corticosteroid action and p38 MAPK-γ inhibition by LABAs has potential for the treatment of severe asthma.

Comparison of Symbicort® versus Pulmicort® on steroid pharmacodynamic markers in asthma patients

BACKGROUND

Combination therapy with inhaled corticosteroids (ICS) and long-acting β(2)-adrenergic agonists (LABA) is reported to have superior effects on controlling asthma symptoms to ICS alone; however, there is no molecular-based evidence to explain the clinical effects. Here, the effect of the ICS/LABA combination was compared with ICS on glucocorticoid receptor (GR) activation in sputum macrophages.

METHODS

In a randomised, double-blind cross-over placebo-controlled 6-visit study, 10 patients with mild asthma were given placebo, formoterol (Oxis(®) 12 μg), budesonide (Pulmicort(®) 200 μg :BUD200, or 800 μg :BUD800), or budesonide/formoterol combination (Symbicort(®)) as a single 100/6 μg (SYM100) or double 200/12 μg (SYM200) dose. Sputum macrophages were separated by plate adhesion from induced sputum. GR binding to the glucocorticoid-response elements on oligonucleotides (GR-GRE binding) was evaluated by ELISA. mRNA expression of MAP-kinase phosphatase (MKP)-1 and IL-8 were measured by quantitative RT-PCR.

RESULTS

GR-GRE binding was significantly increased after treatment with SYM100 (3.5 OD/10 μg protein, median, p < 0.05) versus placebo (1.3) and BUD200 (1.6), and the induction was higher than that of BUD800 (2.4). MKP-1 mRNA was increased and IL-8 mRNA was significantly inhibited by BUD800, SYM100 and SYM200 versus placebo.

CONCLUSIONS

The effects of SYM100 and SYM200 on GR activation were not different from that of BUD800 and superior to BUD200. Thus, it has been confirmed at a molecular level that inhaled combination therapy with a lower dose of budesonide has an equivalent effect to a high dose of budesonide alone. In addition, GR-GRE binding is found to be a valuable pharmacodynamic marker for steroid efficacy in clinical studies.

Harnessing the clinical efficacy of phosphodiesterase 4 inhibitors in inflammatory lung diseases: dual-selective phosphodiesterase inhibitors and novel combination therapies

Phosphodiesterase (PDE) 4 inhibitors have been in development as a novel anti-inflammatory therapy for more than 20 years, with asthma and chronic obstructive pulmonary disease (COPD) being primary indications. Despite initial optimism, only one selective PDE4 inhibitor, roflumilast (Daxas (®)), has been approved for use in humans and available in Canada and the European Union in 2011 for the treatment of a specific population of patients with severe COPD. In many other cases, the development of PDE4 inhibitors of various structural classes has been discontinued due to lack of efficacy and/or dose-limiting adverse events. Indeed, for many of these compounds, it is likely that the maximum tolerated dose is either subtherapeutic or at the very bottom of the efficacy dose-response curve. Thus, a significant ongoing challenge that faces the pharmaceutical industry is to synthesize compounds with therapeutic ratios that are superior to roflumilast. Several strategies are being considered, but clinically effective compounds with an optimal pharmacophore have not, thus far, been reported. In this chapter, alternative means of harnessing the clinical efficacy of PDE4 inhibitors are described. These concepts are based on the assumption that additive or synergistic anti-inflammatory effects can be produced with inhibitors that target either two or more PDE families or with a PDE4 inhibitor in combination with other anti-inflammatory drugs such as a glucocorticoid.

Resveratrol impairs the release of steroid-resistant inflammatory cytokines from human airway smooth muscle cells in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) therapy is complicated by corticosteroid resistance of the interleukin 8 (IL-8)-dependent and granulocyte macrophage-colony stimulating factor (GM-CSF)-dependent chronic airway inflammation, for whose establishment human airway smooth muscle cells (HASMCs) might be crucial. It is unclear whether the release of inflammatory mediators from HASMCs is modulated by cigarette smoking and is refractory to corticosteroids in COPD. Resveratrol, an antiaging drug with protective effects against lung cancer, might be an alternative to corticosteroids in COPD therapy. Vascular endothelial growth factor (VEGF) might offer protection from developing emphysema. We tested the following hypotheses for HASMCs: 1) smoking with or without airway obstruction modulates IL-8, GM-CSF, and VEGF release; and 2) corticosteroids, but not resveratrol, fail to inhibit cytokine release in COPD. Cytokine release from HASMCs exposed to tumor necrosis factor α (TNFα), dexamethasone, and/or resveratrol was measured via enzyme-linked immunosorbent assay and compared between nonsmokers (NS), smokers without COPD (S), and smokers with COPD (all n = 10). In response to TNFα, IL-8 release was increased, but GM-CSF and VEGF release was decreased in S and COPD compared with NS. Dexamethasone and resveratrol inhibited concentration-dependently TNFα-induced IL-8, GM-CSF, and VEGF release. For IL-8 and GM-CSF efficiency of dexamethasone was NS > S > COPD. That of resveratrol was NS = S = COPD for IL-8 and NS = S < COPD for GM-CSF. For VEGF the efficiency of dexamethasone was NS = S = COPD, and that of resveratrol was NS = S > COPD. All resveratrol effects were partially based on p38 mitogen-activated protein kinase blockade. In conclusion, smoking modulates cytokine release from HASMCs. Corticosteroid refractoriness of HASMCs in COPD is cytokine-dependent. Resveratrol might be superior to corticosteroids in COPD therapy, because it more efficiently reduces the release of inflammatory mediators and has limited effects on VEGF in COPD.

Should treatments for asthma be aimed at the airway smooth muscle?

The airway smooth muscle (ASM) cell is an important part of the airway wall of asthma patients because of its increased contractile properties, which appear to be enhanced in this condition and which contribute to airflow obstruction and bronchial hyper-responsiveness. ASM cells are also abnormal in asthma with increased expression of certain chemokines, with increased proliferation rate, numbers and size. beta-adrenergic agonists and corticosteroids are the two most important treatments for asthma; other drugs used are leukotriene receptor antagonists and theophylline. Combination therapy of beta-adrenergic agonists and corticosteroids has become the treatment of choice for moderate-to-severe asthma. beta-adrenergic agonists cause relaxation of ASM cells, leading to a decrease in airflow obstruction of asthma and acute relief of symptoms. Corticosteroids also have direct effects on ASM cells. It is postulated that the effect of anti-inflammatory agents on ASM cells is the most important determinant of the therapeutic effects of these agents. Targeting the ASM cell in asthma could be the focus of therapies for asthma. Specific delivery of active agents to ASM cells may also be part of this strategy.

Salmeterol/fluticasone propionate combination in the treatment of COPD

Chronic obstructive pulmonary disease (COPD) is characterized by poorly reversible airway obstruction and progressive airway inflammation. The long-acting beta2-agonist salmeterol and the corticosteroid fluticasone propionate can be administered in a combination inhaler. Four double-blind, placebo-controlled, randomized clinical trials have demonstrated that salmeterol/fluticasone propionate improves pulmonary function and health status, and also decreases exacerbation rates in COPD patients. The TORCH (Towards a Revolution in COPD Health) study confirmed that the effects of combined therapy with salmeterol/fluticasone propionate are greater than the monocomponents. The TORCH data are also indicative of a beneficial effect of salmeterol/fluticasone propionate on mortality, although there is much debate about this issue. This review critically appraises the pharmacology of salmeterol/fluticasone propionate, the evidence for efficacy in COPD and its potential use in combination with other drugs.

Effect of formoterol and budesonide on chemokine release, chemokine receptor expression and chemotaxis in human neutrophils

Severe persistent asthma and chronic obstructive pulmonary disease (COPD) are associated with neutrophil influx into the airways. It is not clear whether neutrophil chemotaxis is influenced by beta(2)-agonists and glucocorticoids, drugs commonly used in treatment of asthma and COPD. The effect of a long-acting beta(2)-agonist (formoterol), and a glucocorticosteroid (budesonide) on chemokine/cytokine release (CXCL8, CXCL1, IL-6), regulation of chemokine receptors (CXCR1, CXCR2), and migration were assessed in neutrophils from 10 non-allergic, healthy donors. Formoterol enhanced and budesonide inhibited IL-6, CXCL8 and CXCL1 release from LPS-stimulated neutrophils. Formoterol up-regulated both CXCR1 and CXCR2 expression, whereas budesonide up-regulated the expression of CXCR2 only. Despite the effects on chemokine release and drug-induced up-regulation of CXCR1 and CXCR2, no influence on neutrophil chemotaxis could be demonstrated. We conclude that a beta(2)-agonist and a glucocorticoid, commonly used in the treatment of obstructive lung diseases, influence chemokine release and receptor sensitivity but the functional consequences of these findings remain unclear.

Transforming growth factor-β stimulates the expression of eotaxin/CC chemokine ligand 11 and its promoter activity through binding site for nuclear factor-κβ in airway smooth muscle cells

BACKGROUND

Chemokines ligands of CCR3 including eotaxin/CC chemokine ligand 11 (CCL11) may contribute to the pathogenesis of asthma. These chemokines and a growth factor (TGF-beta) may be involved in the process of airway remodelling.

OBJECTIVE

We analysed the effects of TGF-beta on the expression of CCR3 ligands in human airway smooth muscle (HASM) cells and investigated the mechanisms.

METHODS

HASM cells were cultured and treated with TGF-beta and Th2 cytokines IL-4 or IL-13. Expression of mRNA was analysed by real-time PCR. Secretion of CCL11 into the culture medium was analysed by ELISA. Transcriptional regulation of CCL11 was analysed by luciferase assay using CCL11 promoter-luciferase reporter plasmids.

RESULTS

IL-4 or IL-13 significantly up-regulated the expression of mRNAs for CCL11 and CCL26. TGF-beta alone did not increase the expression of chemokine mRNAs, but enhanced the induction of only CCL11 by IL-4 or IL-13 among CCR3 ligands. Activity of the CCL11 promoter was stimulated by IL-4, and this activity was enhanced by TGF-beta. Activation by IL-4 or IL-4 plus TGF-beta was lost by mutation of the binding site for signal transducers and activators of transcription-6 (STAT6) in the promoter. Cooperative activation by IL-4 and TGF-beta was inhibited by mutation of the binding site for nuclear factor-kappaB (NF-kappaB) in the promoter. Pretreatment with an inhibitor of NF-kappaB and glucocorticoid fluticasone propionate significantly inhibited the expression of CCL11 mRNA induced by IL-4 plus TGF-beta, indicating the importance of NF-kappaB in the cooperative activation of CCL11 transcription by TGF-beta and IL-4.

CONCLUSION

These results indicate that Th2 cytokines and TGF-beta may contribute to the pathogenesis of asthma by stimulating expression of CCL11. The transcription factors STAT6 and NF-kappaB may play pivotal roles in this process.

Body mass index and response to asthma therapy: fluticasone propionate/salmeterol versus montelukast

We studied the relationship between body mass index (BMI) on responses to asthma therapy using a retrospective analysis of four previously reported clinical trials. Fluticasone propionate (FP)/salmeterol via Diskus 100/50 microg twice daily and montelukast (MON) 10 mg daily were compared. BMI was classified as underweight (less than 20 kg/m(2)), normal (20-24.9 kg/m(2)), overweight (25-29.9 kg/m(2)), obese-1 (30-34.9 kg/m(2)), obese-2 (35-39.9 kg/m(2)), or obese-3 (at least 40 kg/m(2)). Outcomes assessed included forced expiratory volume in one second (FEV(1)), asthma symptom score, and albuterol use. FP/salmeterol produced greater improvements compared to MON in each of the asthma outcomes studied over the entire BMI range at the week-12 endpoint, with statistically significant differences noted among normal, overweight, obese-1, and obese-3 subjects. The within-treatment responses to FP/salmeterol across BMI ranges at the week-12 endpoint was statistically significantly greater in normal compared to obese-3 for FEV(1) and albuterol use, and in overweight compared to the obese-3 for each outcome studied. The within-treatment comparisons of MON across BMI ranges were significant for albuterol use in normal and underweight compared to obese-3 at the week-12 endpoint. Compared to subjects with normal BMI, the onset to peak FEV(1) may require longer treatment exposure in the very obese. Treatment responses to FP/salmeterol were consistently greater compared to MON and persisted at higher BMI.

Long acting beta2-agonist and corticosteroid restore airway glandular cell function altered by bacterial supernatant

BACKGROUND

Staphylococcus aureus releases virulence factors (VF) that may impair the innate protective functions of airway cells. The aim of this study was to determine whether a long-acting beta2 adrenergic receptor agonist (salmeterol hydroxynaphthoate, Sal) combined with a corticosteroid (fluticasone propionate, FP) was able to regulate ion content and cytokine expression by airway glandular cells after exposure to S. aureus supernatant.

METHODS

A human airway glandular cell line was incubated with S. aureus supernatant for 1 h and then treated with the combination Sal/FP for 4 h. The expression of actin and CFTR proteins was analyzed by immunofluorescence. Videomicroscopy was used to evaluate chloride secretion and X-ray microanalysis to measure the intracellular ion and water content. The pro-inflammatory cytokine expression was assessed by RT-PCR and ELISA.

RESULTS

When the cells were incubated with S. aureus supernatant and then with Sal/FP, the cellular localisation of CFTR was apical compared to the cytoplasmic localisation in cells incubated with S. aureus supernatant alone. The incubation of airway epithelial cells with S. aureus supernatant reduced by 66% the chloride efflux that was fully restored by Sal/FP treatment. We also observed that Sal/FP treatment induced the restoration of ion (Cl and S) and water content within the intracellular secretory granules of airway glandular cells and reduced the bacterial supernatant-dependent increase of pro-inflammatory cytokines IL8 and TNFalpha.

CONCLUSIONS

Our results demonstrate that treatment with the combination of a corticosteroid and a long-acting beta2 adrenergic receptor agonist after bacterial infection restores the airway glandular cell function. Abnormal mucus induced by defective ion transport during pulmonary infection could benefit from treatment with a combination of beta2 adrenergic receptor agonist and glucocorticoid.

Pharmacological strategies for improving the efficacy and therapeutic ratio of glucocorticoids in inflammatory lung diseases

Glucocorticoids are widely used to treat various inflammatory lung diseases. Acting via the glucocorticoid receptor (GR), they exert clinical effects predominantly by modulating gene transcription. This may be to either induce (transactivate) or repress (transrepress) gene transcription. However, certain individuals, including those who smoke, have certain asthma phenotypes, chronic obstructive pulmonary disease (COPD) or some interstitial diseases may respond poorly to the beneficial effects of glucocorticoids. In these cases, high dose, often oral or parental, glucocorticoids are typically prescribed. This generally leads to adverse effects that compromise clinical utility. There is, therefore, a need to enhance the clinical efficacy of glucocorticoids while minimizing adverse effects. In this context, a long-acting beta(2)-adrenoceptor agonist (LABA) can enhance the clinical efficacy of an inhaled corticosteroid (ICS) in asthma and COPD. Furthermore, LABAs can augment glucocorticoid-dependent gene expression and this action may account for some of the benefits of LABA/ICS combination therapies when compared to ICS given as a monotherapy. In addition to metabolic genes and other adverse effects that are induced by glucocorticoids, there are many other glucocorticoid-inducible genes that have significant anti-inflammatory potential. We therefore advocate a move away from the search for ligands of GR that dissociate transactivation from transrepression. Instead, we submit that ligands should be functionally screened by virtue of their ability to induce or repress biologically-relevant genes in target tissues. In this review, we discuss pharmacological methods by which selective GR modulators and "add-on" therapies may be exploited to improve the clinical efficacy of glucocorticoids while reducing potential adverse effects.

Noncontractile functions of airway smooth muscle cells in asthma

Although pivotal in regulating bronchomotor tone in asthma, airway smooth muscle (ASM) also modulates airway inflammation and undergoes hypertrophy and hyperplasia, contributing to airway remodeling in asthma. ASM myocytes secrete or express a wide array of immunomodulatory mediators in response to extracellular stimuli, and in chronic severe asthma, increases in ASM mass may render the airway irreversibly obstructed. Although the mechanisms by which ASM secretes cytokines and chemokines are the same as those regulating immune cells, there exist unique ASM signaling pathways that may provide novel therapeutic targets. This review provides an overview of our current understanding of the proliferative as well as the synthetic properties of ASM.

Drug-regulatable cancer cell death induced by BID under control of the tissue-specific, lung cancer-targeted TTS promoter system

Gene therapy and virotherapy are among the approaches currently being used to treat lung cancer. The success of cancer gene therapy depends on treatments where different types of tumors can be selectively targeted and destroyed without affecting normal cells and tissue. Previously, we described a promoter system (TTS) that we designed that is specifically targeted to lung cancer cells but which does not affect other types of cells including stem cells. In our study, we have enhanced the utility of the TTS system by inserting the pro-apoptotic gene BH3 domain interacting death agonist (Bid) into the TTS promoter system (TTS/Bid) to create a drug regulatable lung cancer-specific gene therapy. A recombinant adenoviral vector was used to introduce TTS/Bid (Ad-TTS/Bid) into lung cancer cells. BID expression and apoptosis occurred in A549 pulmonary adenocarcinoma cells but little Bid expression or apoptosis occurred in MCF7 breast cancer cells or in normal human lung fibroblasts. The use of cisplatin enhanced the processing of full length BID to t-BID which significantly increased lung cancer-specific cell death. In in vivo experiments, intraperitonal injection of cisplatin enhanced the antitumor effects of the vector in a lung cancer xeno-graft mouse model. Moreover, dexamethasone effectively suppressed exogenous BID expression and the antitumor effect of Ad-TTS/Bid both in vitro and in vivo. Here, we describe the efficacy of the use of cisplatin and dexamethasone with the anti lung cancer promoter system (Ad-TTS/Bid) for a safe and effective gene therapy against advanced lung cancer.