Corticosteroid insensitivity in smokers with asthma : clinical evidence, mechanisms, and management

Antioxidant Intake and Biomarkers of Asthma in Relation to Smoking Status-A Review

Asthma is considered a chronic inflammatory disorder associated with airway hyperresponsiveness (AHR). Increased oxidative stress (OS) is a clinical feature of asthma, which promotes the inflammatory responses in bronchial/airway epithelial cells. Smokers and nonsmokers with asthma have been shown to have increases in several OS and inflammatory biomarkers. However, studies suggest significant differences in OS and inflammation biomarkers between smokers and nonsmokers. A few studies suggest associations between antioxidant intake from diet/supplements and asthma in patients with different smoking status. Evidence is lacking on the protective role of antioxidant vitamin and/or mineral consumption against asthma by smoking status with respect to inflammation and OS biomarkers. Therefore, the aim of this review is to highlight current knowledge regarding the relations between antioxidant intake, asthma, and its associated biomarkers, according to smoking status. This paper can be used to guide future research directions towards the health consequences of antioxidant intake in smoking and nonsmoking asthmatics.

Documentation of smoking in scheduled asthma contacts in primary health care: a 12-year follow-up study

Smoking among asthmatics is common and associates with poorer asthma control, more rapid lung function decline and higher health care costs in dose-dependent manner. No previous real-life studies exist, however, on how smoking status and pack-years are documented in scheduled asthma contacts in primary health care (PHC) during long-term follow-up, and how often patients are advised to quit smoking. In this real-life 12-year follow-up study, we showed that out of all scheduled PHC asthma contacts (n = 603) smoking was mentioned only in 17.2% and pack-years only in 6.5%. Smoking data was not recorded even once in 70.9% of never smokers, 64.7% of ex-smokers and 27.3% of current smokers. Smoking including pack-years were mentioned more often if nurse took part on the scheduled contact. For current smokers, smoking cessation was recommended only in 21.7% of their scheduled contacts. Current smokers used more antibiotics and had more unscheduled health care contacts during follow-up.

Association of quality of life and disease control with cigarette smoking in patients with severe asthma

More information is needed on asthma control and health-related quality of life (HRQoL) in smokers with severe asthma. The main study objective was to characterize the association of HRQoL and disease control with cigarette smoking in individuals with severe asthma. A secondary objective was to analyze subject characteristics according to asthma onset: asthma that developed before smoking initiation versus asthma that developed after smoking initiation. This cross-sectional study included subjects with severe asthma aged 18-65 years. HRQoL was assessed using the Asthma Quality of Life Questionnaire (AQLQ) and asthma control was assessed using the Asthma Control Test (ACT) and Global Initiative for Asthma (GINA) criteria. Of the 87 patients studied, 58 (66.7%) were classified as asthmatics who had never smoked and 29 (33.3%) as asthmatics with smoking exposure. The proportion of subjects with uncontrolled asthma was higher in the asthma and smoking group (GINA criteria: P=0.032 and ACT criteria: P=0.003. There were no between-group differences in overall AQLQ score (P=0.475) or AQLQ domain scores (P>0.05). Fifty-eight subjects (66.7%) were nonsmokers, 20 (23%) had asthma onset before smoking, and 9 (10.3%) had asthma onset after smoking. Asthma onset before smoking was associated with uncontrolled asthma (P=0.013). In subjects with severe asthma, smoking was associated with a higher rate of uncontrolled disease but not with HRQoL scores.

Plasma proteins elevated in severe asthma despite oral steroid use and unrelated to Type-2 inflammation

Rationale

Asthma phenotyping requires novel biomarker discovery.

Objectives

To identify plasma biomarkers associated with asthma phenotypes by application of a new proteomic panel to samples from two well-characterised cohorts of severe (SA) and mild-to-moderate (MMA) asthmatics, COPD subjects and healthy controls (HCs).

Methods

An antibody-based array targeting 177 proteins predominantly involved in pathways relevant to inflammation, lipid metabolism, signal transduction and extracellular matrix was applied to plasma from 525 asthmatics and HCs in the U-BIOPRED cohort, and 142 subjects with asthma and COPD from the validation cohort BIOAIR. Effects of oral corticosteroids (OCS) were determined by a 2-week, placebo-controlled OCS trial in BIOAIR, and confirmed by relation to objective OCS measures in U-BIOPRED.

Results

In U-BIOPRED, 110 proteins were significantly different, mostly elevated, in SA compared to MMA and HCs. 10 proteins were elevated in SA versus MMA in both U-BIOPRED and BIOAIR (alpha-1-antichymotrypsin, apolipoprotein-E, complement component 9, complement factor I, macrophage inflammatory protein-3, interleukin-6, sphingomyelin phosphodiesterase 3, TNF receptor superfamily member 11a, transforming growth factor-β and glutathione S-transferase). OCS treatment decreased most proteins, yet differences between SA and MMA remained following correction for OCS use. Consensus clustering of U-BIOPRED protein data yielded six clusters associated with asthma control, quality of life, blood neutrophils, high-sensitivity C-reactive protein and body mass index, but not Type-2 inflammatory biomarkers. The mast cell specific enzyme carboxypeptidase A3 was one major contributor to cluster differentiation.

Conclusions

The plasma proteomic panel revealed previously unexplored yet potentially useful Type-2-independent biomarkers and validated several proteins with established involvement in the pathophysiology of SA.

Application of new proteomic panel in two established European asthma cohorts identifies plasma proteins associated with disease severity independently of Type-2 inflammation, suggesting potentially useful novel biomarkers and therapeutic targets.https://bit.ly/3jtTq5m

CpG oligodeoxynucleotides attenuate RORγt-mediated Th17 response by restoring histone deacetylase-2 in cigarette smoke-exposure asthma

BACKGROUND

Cigarette smoke (CS) exposure increases corticosteroid insensitive asthma related to increased Th17 phenotype, and new treatment strategies are needed for CS-associated asthma. Histone deacetylase 2 (HDAC2), found in the airway epithelium, is critical for ameliorating glucocorticoids insensitivity. We recently demonstrated the anti-inflammatory effects of CpG oligodeoxynucleotides (CpG-ODNs) on CS-exposure asthma. However, the effects of CpG-ODNs on HDAC2 expression and enzymatic activity remain unclear. This study aimed to assess whether CpG-ODNs protect against excessive Th17 immune responses in CS-induced asthma through HDAC2-dependent mechanisms and compared their effects with those of corticosteroids.

METHODS

The effects of CpG-ODNs alone and in combination with budesonide (BUD) on airway inflammation and Th2/Th17-related airway immune responses were determined using an in vivo model of CS-induced asthma and in cultured bronchial epithelial (HBE) cells administered ovalbumin (OVA) and/or cigarette smoke extract (CSE). HDAC2 and retinoid-related orphan nuclear receptor γt (RORγt) expression were also assessed in mouse lung specimens and HBE cells.

RESULTS

CpG-ODNs and BUD synergistically attenuated CS exposure asthmatic responses in vivo by modulating the influx of eosinophils and neutrophils, airway remodeling, Th2/Th17 associated cytokine and chemokine production, and airway hyperresponsiveness and blocking RORγt-mediated Th17 inflammation through induced HDAC2 expression/activity. In vitro, CpG-ODNs synergized with BUD to inhibit Th17 cytokine production in OVA- and CSE-challenged HBE cells while suppressing RORγt and increasing epithelial HDAC2 expression/activity.

CONCLUSIONS

CpG-ODNs reversed CS-induced HDAC2 downregulation and enhanced the sensitivity of CS-exposed asthmatic mice and CSE-induced HBE cells to glucocorticoid treatment. This effect may be associated with HDAC2 restoration via RORγt/IL-17 pathway regulation, suggesting that CpG-ODNs are potential corticosteroid-sparing agents for use in CS-induced asthma with Th17-biased immune conditions.

The role of HDAC2 in cigarette smoke-induced airway inflammation in a murine model of asthma and the effect of intervention with roxithromycin

BACKGROUND

Cigarette smoke is well known to worsen asthma symptoms in asthmatic patients and to make them refractory to treatment, but the underling molecular mechanism is unclear. We hypothesized that cigarette smoke can reduce the expression of HDAC2 in asthma and the process was achieved by activating the PI3K-δ/Akt signaling pathway. We further hypothesized that roxithromycin (RXM) can alleviate the impacts by cigarette smoke.

METHODS

A murine model of asthma induced by ovalbumin (OVA) and cigarette smoke has been established. The infiltration of inflammatory cells and inflammatory factors was examined in this model. Finally, we evaluated the expression of HDAC2, Akt phosphorylation levels, and the effects of RXM treatment on the model described earlier.

RESULTS

Cigarette smoke exposure reduced HDAC2 protein expression by enhancing the phosphorylation of Akt in PI3K-δ/Akt signaling pathway. Furthermore, RMX reduced the airway inflammation and improved the level of expression of HDAC2 in the cigarette smoke-exposed asthma mice.

CONCLUSIONS

This study provides a novel insight into the mechanism of cigarette smoke exposure in asthma and the effects of RXM treatment on this condition. These results may be helpful for treating refractory asthma and emphasizing the need for a smoke-free environment for asthmatic patients.

An observational study of the impact of an antenatal asthma management service on asthma control during pregnancy

OBJECTIVE

We sought to investigate the impact of introducing an antenatal asthma management service (AMS) on asthma control during pregnancy and subsequent perinatal outcomes.

STUDY DESIGN

Prospective, observational cohort study of pregnant asthmatic women attending a tertiary hospital antenatal clinic. Asthmatic women were recruited from the antenatal clinic and were followed prospectively with visits at 12, 20, 28 and 36 weeks gestation. A new nurse-led AMS was introduced offering asthma self-management education and support. Outcomes were compared between women recruited before and after the AMS was introduced (n=89 and 80, respectively) and included; prevalence of exacerbations during pregnancy, asthma control throughout pregnancy and perinatal outcomes, including preterm birth and small-for-gestational-age (SGA).

RESULTS

The relative risk for exacerbations (0.69; CI: 0.33-1.42), loss of control (0.67; CI 0.46-0.99) and persistent uncontrolled asthma (0.48; CI 0.26-0.9) were all reduced with attendance to AMS during pregnancy. AMS was associated with non-statistically significant reductions in asthma exacerbations (19.1-15.0%; p=0.480) and uncontrolled asthma at ≥ 2 study visits (21.3-11.3%; p=0.078).

CONCLUSIONS

These findings demonstrate the potential impact of an AMS in improving asthma control during pregnancy, supporting the need for an adequately powered RCT to determine its clinical- and cost-effectiveness.

Virus-induced modulation of lower airway diseases: pathogenesis and pharmacologic approaches to treatment

Uncomplicated upper respiratory viral infections are the most common cause of days lost from work and school and exert a major economic burden. In susceptible individuals, however, common respiratory viruses, particularly human rhinoviruses, also can have a major impact on diseases that involve the lower airways, including asthma, chronic obstructive pulmonary diseases (COPD) and cystic fibrosis (CF). Respiratory virus-induced wheezing illnesses in early life are a significant risk factor for the subsequent development of asthma, and virus infections may also play a role in the development and progression of airway remodeling in asthma. It is clear that upper respiratory tract virus infections can spread to the lower airway and trigger acute attacks of asthma, COPD or CF. These exacerbations can be life-threatening, and exert an enormous burden on health care systems. In recent years we have gained new insights into the mechanisms by which respiratory viruses may induce acute exacerbations of lower airway diseases, as well as into host defense pathways that may regulate the outcomes to viral infections. In the current article we review the role of viruses in lower airway diseases, including our current understanding on pathways by which they may cause remodeling and trigger acute exacerbations. We also review the efficacy of current and emerging therapies used to treat these lower airway diseases on the outcomes due to viral infection, and discuss alternative therapeutic approaches for the management of virus-induced airway inflammation.

Cyclic nucleotide-based therapeutics for chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) defines a group of chronic inflammatory disorders of the airways that are characterised by a progressive and largely irreversible decline in expiratory airflow. Drugs used to treat COPD through actions mediated by cyclic AMP (cAMP) are restricted to long-acting and short-acting β2-adrenoceptor agonists and, in a subset of patients with chronic bronchitis, a phosphodiesterase 4 inhibitor, roflumilast. These agents relax airway smooth muscle and suppress inflammation. At the molecular level, these effects in the airways are mediated by two cAMP effectors, cAMP-dependent protein kinase and exchange proteins activated by cAMP. The pharmacology of newer agents, acting through these systems, is discussed here with an emphasis on their potential to interact and increase therapeutic effectiveness.

Corticosteroid insensitivity is reversed by formoterol via phosphoinositide-3-kinase inhibition

BACKGROUND AND PURPOSE

Patients with chronic obstructive pulmonary disease (COPD) show a poor response to corticosteroids, which has been linked to oxidative stress. Here we show that the long-acting β(2) -agonist formoterol (FM) reversed corticosteroid insensitivity under oxidative stress via inhibition of phosphoinositide-3-kinase (PI3K) signalling.

EXPERIMENTAL APPROACH

Responsiveness to corticosteroids dexamethasone (Dex), budesonide (Bud) and fluticasone propionate (FP) was determined, as IC(50) values on TNF-α-induced interleukin 8 release, in U937 monocytic cell line treated with hydrogen peroxide (H(2) O(2) ) or peripheral blood mononuclear cells (PBMCs) from patients with COPD or severe asthma.

KEY RESULTS

PBMCs from severe asthma and COPD were less sensitive to Dex compared with those from healthy subjects. Both FM (10(-9)  M) and salmeterol (SM, 10(-8)  M) reversed Dex insensitivity in severe asthma, but only FM restored Dex sensitivity in COPD. Although H(2) O(2) exposure decreased steroid sensitivity in U937 cells, FM restored responsiveness to Bud and FP while the effects of SM were weaker. Additionally, FM, but not SM, partially inhibited H(2) O(2) -induced PI3Kδ-dependent (PKB) phosphorylation. H(2) O(2) decreased SM-induced cAMP production in U937 cells, but did not significantly affect the response to FM. The reduction of SM effects by H(2) O(2) was reversed by pretreatment with LY294002, a PI3K inhibitor, or IC87114, a PI3Kδ inhibitor.

CONCLUSION AND IMPLICATIONS

FM reversed oxidative stress-induced corticosteroid insensitivity and decreased β(2) adrenoceptor-dependent cAMP production via inhibition of PI3Kδ signalling. FM will be more effective than SM, when combined with corticosteroids, for the treatment of respiratory diseases under conditions of high oxidative stress, such as in COPD.

Non-atopic males with adult onset asthma are at risk of persistent airflow limitation

BACKGROUND

Patients with asthma have on average a more rapid decline in FEV (1) as compared with the general population. Recent cluster analysis has revealed different asthma phenotypes that can be distinguished by age of onset and reversibility of airflow limitation.

OBJECTIVE

This study aimed at detecting risk factors associated with persistent airflow limitation in patients with the adult onset asthma phenotype.

METHODS

We recruited 88 patients with adult onset (≥ 18 years) asthma from an academic pulmonary outpatient clinic in the Netherlands. The associations of age, age of asthma onset, asthma duration, gender, race, atopy, smoking pack-years, BMI, use of oral corticosteroids with post-bronchodilator FEV (1) /FVC were investigated.

RESULTS

Multiple linear regression analysis showed an association of absence of atopy (r = -0.27, B = -0.26, P = 0.01) and male gender (r = 0.31, B = 0.30, P = 0.004) with post-bronchodilator FEV (1) /FVC. Multiple logistic regression analysis showed that male patients were 10.8 (CI: 2.6-45.2) times the odds than women to have an FEV (1) /FVC < 0.7, and non-atopic patients were 5.2 (CI: 1.3-20.3) times the odds to have an FEV (1) /FVC < 0.7 than atopic patients.

CONCLUSIONS AND CLINICAL RELEVANCE

We conclude that in patients with adult onset asthma, male gender and absence of atopy are associated with persistent airflow limitation. This might suggest that amongst patients with adult onset asthma, non-atopic male patients are at increased risk of accelerated decline in lung function.

The future of combining inhaled drugs for COPD

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality globally, and its prevalence is projected to continue to increase owing to trends in smoking. Treatment of COPD has evolved from the initial adaptations of drugs and treatment strategies successfully used in asthma into more specific pharmacological strategies following global guidelines. Bronchodilating anticholinergic and beta-2-stimulating agents and anti-inflammatory corticosteroid drugs delivered by inhalators are the mainstay of COPD treatment. Despite significant progress, current pharmacotherapies neither fully alleviate the airway obstruction in COPD, nor reverse the progressive nature of the disease. This review discusses inhalation therapies which have recently become clinically available or are being developed, with focus on combination therapies. There is accumulating evidence that the combination of two or all three drug classes, triple therapy, is superior to single drug therapy. Several fixed combinations of both currently available and novel molecules will be launched for clinical use within the next few years. Also, improved understanding of subgroups within the clinical spectrum of COPD, is likely to offer new potentials to improve COPD care.

[Chronic obstructive pulmonary disease and asthma]

Chronic obstructive pulmonary disease and asthma are both highly prevalent inflammatory diseases characterized by airway obstruction with distinct pathogenic mechanisms and different degrees of response to antiinflammatory therapy. However, forms of presentation that show overlap between both diseases and which are not clearly represented in clinical trials are frequently encountered in clinical practice. These patients may show accelerated loss of pulmonary function and have a worse prognosis. Therefore their early identification is essential. Biomarkers such as bronchial hyperreactivity or nitric oxide in exhaled air have yielded discrepant results. Phenotypic characterization will allow treatment with inhaled corticosteroids to be individually tailored and optimized.

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.

Protocol: influence of budesonide and budesonide/formoterol on asthma control in smoking asthmatic adults

RATIONALE

A reduced response to inhaled corticosteroids (ICS) has been reported in smoking asthmatic patients but the effects of other medications remain to be evaluated in this population.

SUBJECTS AND METHODS

We evaluated the effects of a combined therapy of budesonide 200 microg twice daily and formoterol 6 microg twice daily compared with budesonide 200 microg twice daily alone on asthma control questionnaire (ACQ), asthma quality of life questionnaire (AQLQ- Juniper), pulmonary function and airway inflammation, in a cross-over randomized double-blind study with treatment periods of two months separated by a one-month wash-out period. Seventeen smoking and 22 non-smoking patients not using inhaled corticosteroids with slightly uncontrolled mild asthma completed the study.

RESULTS

ACQ and AQLQ scores were similar in both groups at baseline and improved similarly after treatments. beta2-agonist use was higher in smokers, regardless of the treatment received (p=0.03), as it was on baseline (p=0.003). Smokers treated with budesonide/formoterol showed an increase in the number of asthma episodes (intercurrent asthma symptoms, p=0.016) while non-smoking subjects had a significant decrease in these episodes (p=0.009). No difference was found between smokers and non-smokers in regard to post-treatment airway inflammatory parameters.

CONCLUSIONS

No significant differences were found between smoking and non-smoking subjects with mild asthma in regard to clinical changes in asthma control, pulmonary function and airway inflammation following a 2-month treatment period with budesonide or the association of budesonide and formoterol for a period of 2 months. This should be further explored in larger groups of subjects.

Treatment with a peroxisomal proliferator activated receptor gamma agonist has a modest effect in the allergen challenge model in asthma: a randomised controlled trial

PURPOSE

A considerable body of non clinical evidence has accumulated to support peroxisomal proliferator-activated receptor gamma agonists as candidate anti-inflammatory drugs in asthma. We utilized rosiglitazone as a tool compound in the inhaled allergen challenge model of asthma.

METHODS

A single centre, double-blind, randomised, placebo controlled, two period cross-over study. Subjects received rosiglitazone 4mg and placebo twice daily for 28 days in random order. On day 28, inhaled allergen challenge was performed 1 hour post-dose. A methacholine challenge was performed on day 29 and an adenosine monophosphate challenge on day 14. Exhaled nitric oxide was measured on days 1, 14, 28, 29. Blood was collected pre dose on days 1, 14 and 28 and analysed for markers associated with PPAR activity and systemic markers of inflammation.

RESULTS

The late asthmatic reaction (LAR) change from post saline FEV(1) from 4-10 hrs post allergen on day 28 was statistically significant for the weighted mean LAR. The difference in weighted mean was 0.06 L (95% CI 0.01 to 0.11) which equates to a 15% attenuation of the response during placebo treatment. This was accompanied by trends in other markers of efficacy and anti-inflammatory activity but none were considered major effects.

DISCUSSION

Treatment with a PPARgamma agonist (rosiglitazone) was associated with a modest (15%) reduction in the late asthmatic reaction in the allergen challenge model of asthma. Based on the results of this study, PPARgamma agonist monotherapy is unlikely to represent a clinically useful intervention in human asthma. Registered with www.clinicaltrials.gov (NCT00318630).

Environmental tobacco smoke and its effect on the symptoms and medication in children with asthma

Environmental tobacco smoke (ETS) worsens asthmatic symptoms. We analyzed the relationship between levels of ETS and asthmatic symptoms and medication. We asked parents of 282 asthmatic children about the general condition, smoke exposure and medication. Patients were classified into three groups: no-ETS (no smoking), mild-ETS (smoking in the house but not in the same room as patient), and heavy-ETS (smoking in the same room as patient). We classified 116 children in no-ETS group, 124 children in mild-ETS group and 42 children in heavy-ETS group. The symptoms were worst and prevalence of leukotriene receptor antagonist and long-acting beta(2)-agonist use were highest in heavy-ETS group. However, there was no statistical difference between no-ETS and mild-ETS groups in prevalence of anti-asthmatic drug use and symptoms. We conclude that a smoking ban in rooms used by asthmatic children is an easy way to reduce ETS, asthmatic symptoms and the use of anti-asthmatic drugs.

[What is the therapeutic response to corticosteroid in smokers with asthma?]

Inhaled corticosteroid is the first choice antiinflammatory therapy for chronic asthma. International guidelines are based upon data obtained in the non-smokers with asthma. The objective of this review is to highlight the interaction between cigarette smoking and metabolism of steroids and to consider the consequences of such an interaction on clinical and respiratory function. The mechanisms of corticosteroid resistance induced by cigarette smoking results of overexpression of glucocorticoid receptor beta, increased activation of pro-inflammatory transcription factors (nuclear factor-kappaB) and cytokines (IL-4, IL-8, TNF-alpha) or reduced histone deacetylase activity. Compared with non smokers with asthma, inhaled corticosteroids in smokers with asthma does not improve asthma control, lung function and bronchial obstruction. Active smoking impairs the efficacy of short-term oral corticosteroid treatment. Smoking cessation is the highest priority in smokers with asthma.

A Holy Grail of asthma management: toward understanding how long-acting beta(2)-adrenoceptor agonists enhance the clinical efficacy of inhaled corticosteroids

There is unequivocal evidence that the combination of an inhaled corticosteroid (ICS) -- i.e. glucocorticoid -- and an inhaled long-acting beta(2)-adrenoceptor agonist (LABA) is superior to each component administered as a monotherapy alone in the clinical management of asthma. Moreover, Calverley and colleagues (Lancet 2003, 361: 449-456; N Engl J Med 2007, 356: 775-789) reporting for the 'TRial of Inhaled STeroids ANd long-acting beta(2)-agonists (TRISTAN)' and 'TOwards a Revolution in COPD Health (TORCH)' international study groups also demonstrated the superior efficacy of LABA/ICS combination therapies over ICS alone in the clinical management of chronic obstructive pulmonary disease. This finding has been independently confirmed indicating that the therapeutic benefit of LABA/ICS combination therapies is not restricted to asthma and may be extended to other chronic inflammatory diseases of the airways. Despite the unquestionable benefit of LABA/ICS combination therapies, there is a vast gap in our understanding of how these two drugs given together deliver superior clinical efficacy. In this article, we review the history of LABA/ICS combination therapies and critically evaluate how these two classes of drugs might interact at the biochemical level to suppress pro-inflammatory responses. Understanding the molecular basis of this fundamental clinical observation is a Holy Grail of current respiratory diseases research as it could permit the rational exploitation of this effect with the development of new 'optimized' LABA/ICS combination therapies.