Analysis of induced sputum in adults with asthma: identification of subgroup with isolated sputum neutrophilia and poor response to inhaled corticosteroids

Expression of Inflammatory Mediators in Induced Sputum: Comparative Study in Asthma and COPD

Asthma and COPD are the most common obstructive lung diseases characterized by inflammation in the lower airways which contribute to airflow limitation. Different inflammatory mediators are thought to play a key role in these diseases. This study was conducted in 13 patients with asthma, 12 patients with COPD, and 13 control subjects. The expression of mRNA of IL-6, IL-13, CXCL8, TSLP, IL-33, IL-25, IL-17, ECP, mast cell tryptase, CCL24, and CCL26 was assessed in induced sputum cells by real time PCR. We found that CXCL8 was strongly related to the neutrophil percentage but differed significantly in COPD and asthma patients. The expression of IL-17 was lower in patients with atopic asthma compared to non-atopic asthma. The percentage of macrophages correlated negatively with the expression of mast cell tryptase and ECP in COPD, and with CXCL8 in asthma. The expression of ECP correlated negatively with the severity of COPD symptoms measured by CAT. We conclude that asthma and COPD demonstrate a significant overlap in the airway cytokine profile. Thus, differentiation between the two diseases is difficult as based on a single cytokine, which suggests the coexistence of phenotypes sharing a common cytokine network in these obstructive lung diseases.

Effects of Macrolide and Corticosteroid in Neutrophilic Asthma Mouse Model

BACKGROUND

Asthma is a disease of chronic airway inflammation with heterogeneous features. Neutrophilic asthma is corticosteroid-insensitive asthma related to absence or suppression of TH2 process and increased TH1 and/or TH17 process. Macrolides are immunomodulatory drug that reduce airway inflammation, but their role in asthma is not fully known. The purpose of this study was to evaluate the role of macrolides in neutrophilic asthma and compare their effects with those of corticosteroids.

METHODS

C57BL/6 female mice were sensitized with ovalbumin (OVA) and lipopolysaccharides (LPS). Clarithromycin (CAM) and/or dexamethasone (DXM) were administered at days 14, 15, 21, 22, and 23. At day 24, the mice were sacrificed.

RESULTS

Airway resistance in the OVA+LPS exposed mice was elevated but was more attenuated after treatment with CAM+DXM compared with the monotherapy group (p<0.05 and p<0.01). In bronchoalveolar lavage fluid study, total cells and neutrophil counts in OVA+LPS mice were elevated but decreased after CAM+DXM treatment. In hematoxylin and eosin stain, the CAM+DXM-treated group showed less inflammation additively than the monotherapy group. There was less total protein, interleukin 17 (IL-17), interferon γ, and tumor necrosis factor α in the CAM+DXM group than in the monotherapy group (p<0.001, p<0.05, and p<0.001). More histone deacetylase 2 (HDAC2) activity was recovered in the DXM and CAM+DXM challenged groups than in the control group (p<0.05).

CONCLUSION

Decreased IL-17 and recovered relative HDAC2 activity correlated with airway resistance and inflammation in a neutrophilic asthma mouse model. This result suggests macrolides as a potential corticosteroid-sparing agent in neutrophilic asthma.

Mechanisms of exercise-induced bronchoconstriction in athletes: Current perspectives and future challenges

The evidence of exercise-induced bronchoconstriction (EIB) without asthma (EIBw_A ) occurring in athletes led to speculate about different endotypes inducing respiratory symptoms within athletes. Classical postulated mechanisms for bronchial obstruction in this population include the osmotic and the thermal hypotheses. More recently, the presence of epithelial injury and inflammation in the airways of athletes was demonstrated. In addition, neuronal activation has been suggested as a potential modulator of bronchoconstriction. Investigation of these emerging mechanisms is of major importance as EIB is a significant problem for both recreational and competitive athletes and is the most common chronic condition among Olympic athletes, with obvious implications for their competing performance, health and quality of life. Hereby, we summarize the latest achievements in this area and identify the current gaps of knowledge so that future research heads toward better defining the etiologic factors and mechanisms involved in development of EIB in elite athletes as well as essential aspects to ultimately propose preventive and therapeutic measures.

Strategies towards improving pharmacological management of asthma during pregnancy

Maternal asthma represents a significant burden to individuals and the healthcare system, affecting 1 in 10 pregnancies worldwide. Approximately 50% of asthmatic women experience a deterioration of asthma control at some stage during pregnancy, with a number requiring use of oral corticosteroids for the management of acute exacerbations. The presence of maternal asthma and exacerbations during pregnancy is a noted risk factor for a range of adverse perinatal outcomes including preterm birth, small-for-gestational age, pre-eclampsia, and gestational diabetes. These negative impacts highlight the need for evidence-based approaches for improving asthma management during pregnancy and subsequent perinatal outcomes. Despite this, relatively small progress has been made in enhancing the management of maternal asthma in the clinical setting. A major challenge in improving outcomes of asthmatic pregnancies is that there is no single simplified approach for improving outcomes, but rather the requirement to consider the dynamic relationship between a myriad of interrelated factors that ultimately determine an individual's ability to maintain adequate asthma control. Understanding how these factors are impacted by pregnancy and how they can be addressed through various interventions is therefore important in optimising health outcomes. This review summarises key factors involved in influencing outcomes associated with maternal asthma. This includes an overview of the use of asthma medications in pregnancy, while also considering the impacts of interrelated aspects such as medication adherence, health-seeking behaviours, biological and lifestyle factors, co-morbidities, and asthma self-management strategies on asthma control. Addressing such factors through multidisciplinary approaches towards treatment have potential to improve the health of mothers and their offspring. Optimising asthma control should be a high priority within the antenatal setting, with women advised about the importance of good asthma control, managing asthma actively throughout pregnancy by utilising their asthma medications, and managing exacerbations in a timely and effective manner.

Clinical approaches towards asthma and chronic obstructive pulmonary disease based on the heterogeneity of disease pathogenesis

Asthma and chronic obstructive pulmonary disease (COPD) are each heterogeneous disease classifications that include several clinical and pathophysiological phenotypes. This heterogeneity complicates characterization of each disease and, in some cases, hinders the selection of appropriate treatment. Therefore, in recent years, emphasis has been placed on improving our understanding of the various phenotypes of asthma and of COPD and identifying biomarkers for each phenotype. Likewise, the concept of the endotype has been gaining acceptance; an endotype is a disease subtype that is defined by unique or distinctive functional or pathophysiological mechanisms. Endotypes of asthma or COPD may be primarily characterized by increased susceptibility to type 2 inflammation, increased susceptibility to viral infections, bacterial colonization or impaired lung development. The 'Dutch hypothesis' is as follows: gene variants underlying particular endotypes interact with detrimental environmental stimuli (e.g. smoking, viral infection and air pollution) and contribute to the ultimate development of asthma, COPD or both. Novel approaches that involve multidimensional assessment should facilitate identification and management of the components that generate this heterogeneity. Ultimately, patients with chronic inflammatory lung diseases may be treated based on these endotypes as determined by the respective biomarkers that correspond to individual endotypes instead of on disease labels such as asthma, COPD or even asthma-COPD overlap syndrome (ACOS).

Revisiting Type 2-high and Type 2-low airway inflammation in asthma: current knowledge and therapeutic implications

Asthma is a complex respiratory disorder characterized by marked heterogeneity in individual patient disease triggers and response to therapy. Several asthma phenotypes have now been identified, each defined by a unique interaction between genetic and environmental factors, including inflammatory, clinical and trigger-related phenotypes. Endotypes further describe the functional or pathophysiologic mechanisms underlying the patient's disease. type 2-driven asthma is an emerging nomenclature for a common subtype of asthma and is characterized by the release of signature cytokines IL-4, IL-5 and IL-13 from cells of both the innate and adaptive immune systems. A number of well-recognized biomarkers have been linked to mechanisms involved in type 2 airway inflammation, including fractional exhaled nitric oxide, serum IgE, periostin, and blood and sputum eosinophils. These type 2 cytokines are targets for pharmaceutical intervention, and a number of therapeutic options are under clinical investigation for the management of patients with uncontrolled severe asthma. Anticipating and understanding the heterogeneity of asthma and subsequent improved characterization of different phenotypes and endotypes must guide the selection of treatment to meet individual patients' needs.

Effects of treatment changes on asthma phenotype prevalence and airway neutrophil function

Background

Asthma inflammatory phenotypes are often defined by relative cell counts of airway eosinophils/neutrophils. However, the importance of neutrophilia remains unclear, as does the effect of ICS treatment on asthma phenotypes and airway neutrophil function. The purpose of this study was to assess asthma phenotype prevalence/characteristics in a community setting, and, in a nested preliminary study, determine how treatment changes affect phenotype stability and inflammation, with particular focus on airway neutrophils.

Methods

Fifty adult asthmatics and 39 non-asthmatics were assessed using questionnaires, skin prick tests, spirometry, exhaled nitric oxide (FENO) measurement, and sputum induction. Twenty-one asthmatics underwent further assessment following treatment optimisation (n = 11) or sub-optimisation (n = 10).

Results

Forty percent (20/50) had eosinophilic asthma (EA) and 8% had neutrophilic asthma. EA was associated with increased FENO, bronchodilator reversibility (BDR) and reduced lung function (p < 0.05). Following optimisation/sub-optimisation, the EA/NEA (non-eosinophilic asthma) phenotype changed in 11/21 (52%) asthmatics. In particular, fewer subjects had EA post treatment optimisation, but this was not statistically significant. However, a significant (p < 0.05) reduction in FENO, ACQ7 score, and BDR was observed after treatment optimisation, as well as an increase in FEV₁-% predicted (p < 0.05). It was also associated with reduced eosinophils (p < 0.05) and enhanced neutrophil phagocytosis (p < 0.05) in EA only, and enhanced neutrophil oxidative burst in both EA and NEA (p < 0.05).

Conclusions

In this community based population, non-eosinophilic asthma was common, less severe than EA, and at baseline most asthmatics showed no evidence of inflammation. In the nested change in treatment study, treatment optimisation was associated with reduced sputum eosinophils, improved symptoms and lung function, and enhanced neutrophil function, but a significant reduction in EA could not be demonstrated.

Trial registration

The nested change in treatment component of this study is registered at the Australia and New Zealand Clinical Trial Registry (www.ANZCTR.org.au) ACTRN12617001356358. Registration date 27/09/2017. Retrospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12890-017-0511-6) contains supplementary material, which is available to authorized users.

Neutrophilic Inflammation in Asthma and Association with Disease Severity

Asthma is a chronic inflammatory disorder of the airways. While the local infiltration of eosinophils and mast cells, and their role in the disease have long been recognized, neutrophil infiltration has also been assessed in many clinical studies. In these studies, airway neutrophilia was associated with asthma severity. Importantly, neutrophilia also correlates with asthma that is refractory to corticosteroids, the mainstay of asthma treatment. However, it is now increasingly recognized that neutrophils are a heterogeneous population, and a more precise phenotyping of these cells may help delineate different subtypes of asthma. Here, we review current knowledge of the role of neutrophils in asthma and highlight future avenues of research in this field.

IL-17 and TNF-α Are Key Mediators of Moraxella catarrhalis Triggered Exacerbation of Allergic Airway Inflammation

Alterations of the airway microbiome are often associated with pulmonary diseases. For example, detection of the bacterial pathogen Moraxella catarrhalis in the upper airways is linked with an increased risk to develop or exacerbate asthma. However, the mechanisms by which M. catarrhalis augments allergic airway inflammation (AAI) remain unclear. We here characterized the cellular and soluble mediators of M. catarrhalis triggered excacerbation of AAI in wt and IL-17 deficient as well as in animals treated with TNF-α and IL-6 neutralizing antibodies. We compared the type of inflammatory response in M. catarrhalis infected, house dust mite (HDM)-allergic and animals infected with M. catarrhalis at different time points of HDM sensitization. We found that airway infection of mice with M. catarrhalis triggers a strong inflammatory response with massive neutrophilic infiltrates, high amounts of IL-6 and TNF-α and moderate levels of CD4⁺ T-cell-derived IFN-γ and IL-17. If bacterial infection occurred during HDM allergen sensitization, the allergic airway response was exacerbated, particularly by the expansion of Th17 cells and increased TNF-α levels. Neutralization of IL-17 or TNF-α but not IL-6 resulted in accelerated clearance of M. catarrhalis and effectively prevented infection-induced exacerbation of AAI. Taken together, our data demonstrate an essential role for TNF-α and IL-17 in infection-triggered exacerbation of AAI.

Guiding principles for use of newer biologics and bronchial thermoplasty for patients with severe asthma

BACKGROUND

Severe asthma poses significant disease-related and economic burdens in the United States. Challenges in practice include how to define "severe asthma" for a given patient, knowing which are the right tests to perform and when, and having a better understanding of a patient's asthma phenotype. Furthermore, current guidelines do not address a clear, practical approach to treatment that is based on a patient's asthma phenotype.

OBJECTIVE

To develop a consensus on the definition of severe asthma, the role of biomarkers and phenotyping severe asthma, and the use of newer biologic therapies and bronchial thermoplasty to help guide practicing clinicians.

METHODS

A roundtable meeting was convened with a panel of severe asthma experts to discuss areas in practice that are not adequately addressed by current guidelines, specifically phenotype-guided treatment.

RESULTS

We describe a consensus on the definition of severe asthma, asthma phenotyping with the use of available biomarkers, and guiding principles for newer biologic therapies and bronchial thermoplasty.

CONCLUSION

To optimize therapy and improve outcomes such as daily symptoms, quality of life, exacerbations, and hospitalizations, a clear picture of a patient's asthma phenotype is needed to guide therapy. Determining asthma phenotypes is the foundation of precision medicine for this persistent, often difficult-to-treat disease.

Clinical, functional and inflammatory characteristics in patients with paucigranulocytic stable asthma: Comparison with different sputum phenotypes

BACKGROUND

According to induced sputum cell count, four different asthma phenotypes have been recognized (eosinophilic, neutrophilic, mixed and paucigranulocytic). The aim of this study was to detect functional and inflammatory characteristics of patients with paucigranulocytic asthma.

METHODS

A total of 240 asthmatic patients were categorized into the four phenotypes according to cell counts in induced sputum. All patients underwent pulmonary function tests, and measurement of fraction of exhaled nitric oxide (FeNO). The levels of IL-8, IL-13 and eosinophilic cationic protein (ECP) were also measured in sputum supernatant. Treatment, asthma control and the presence of severe refractory asthma (SRA) were also recorded.

RESULTS

Patients were categorized into the four phenotypes as follows: eosinophilic (40%), mixed (6.7%), neutrophilic (5.4%) and paucigranulocytic (47.9%). Although asthma control test did not differ between groups (P=.288), patients with paucigranulocytic asthma had better lung function (FEV₁ % pred) [median (IQR): 71.5 (59.0-88.75) vs 69.0 (59.0-77.6) vs 68.0 (60.0-85.5) vs 80.5 (69.7-95.0), P=.009] for eosinophilic, mixed, neutrophilic and paucigranulocytic asthma, respectively, P=.009). SRA occurred more frequently in the eosinophilic and mixed phenotype (41.6% and 43.7%, respectively) and less frequently in the neutrophilic and paucigranulocytic phenotype (25% and 21.7%, respectively, P=.01). FeNO, ECP and IL-8 were all low in the paucigranulocytic, whereas as expected FeNO and ECP were higher in eosinophilic and mixed asthma, while IL-8 was higher in patients with neutrophilic and mixed asthma (P<.001 for all comparisons). Interestingly, 14.8% of patients with paucigranulocytic asthma had poor asthma control.

CONCLUSION

Paucigranulocytic asthma most likely represents a "benign" asthma phenotype, related to a good response to treatment, rather than a "true" phenotype of asthma. However, paucigranulocytic patients that remain not well controlled despite optimal treatment represent an asthmatic population that requires further study for potential novel targeted interventions.

How should treatment approaches differ depending on the severity of asthma?

INTRODUCTION

Asthma is nowadays regarded as a syndrome of various overlapping phenotypes with defined clinical characteristics, different underlying inflammatory mechanisms, identifiable genetic background, environmental risk factors and possible biomarkers. There are no doubts that due to the diversity of asthma, a 'one size fits all' management of the disease is no longer valid. Areas covered: Nowadays asthma management is based on the control of the disease, and the goals of asthma treatment are defined as good symptom control, decreased future risk of exacerbations, fixed airflow limitation, and side-effects of treatment. Alternative strategies for adjusting asthma treatment such as sputum or exhaled nitric oxide guided protocols have been evaluated and despite some effectiveness, are regarded as impractical in every-day clinical conditions. Further studies in the field of asthma phenotypes/endotypes and biomarkers are warranted with the main goal to define which of those possible subgroups will be useful in clinical practice in regards to the potential allocation of successful treatment. Expert commentary: Despite the availability of guidelines on the diagnosis and management of asthma, it seems that the disease is still not optimally controlled. Addressing unmet needs in every day care, improving education, adherence/compliance and inhalation technique may significantly improve asthma control across all severities of the disease.

Sputum colour can identify patients with neutrophilic inflammation in asthma

Introduction

Sputum colour is associated with neutrophilic inflammation in chronic bronchitis and chronic obstructive pulmonary disease (COPD). Neutrophilia and sputum expectoration is notable in asthma, but whether sputum colour is associated with and predicts the presence of neutrophilic inflammation in asthma is unknown. The objective of the study is to assess the ability of sputum colour in distinguishing asthma inflammatory phenotypes.

Methods

Induced sputum samples collected from 271 adults with stable asthma were retrospectively assessed. Sputum colour was determined using the BronkoTest sputum colour chart and correlated to differential cell counts and CXCL-8 concentration. Neutrophilic inflammation was defined as an age-corrected sputum neutrophil proportion (≥61.6% for age 20–40 years; ≥63.2% for age 40–60 and ≥67.2% for age >60 years), whereas neutrophilic bronchitis (NB) was defined as high total cell count (≥5.1×10⁶ cells/mL) plus an increased age-corrected neutrophil proportion. The optimal cut-off for sputum colour to predict neutrophilic inflammation and NB was determined using receiver operator characteristic curve analysis.

Results

A sputum colour score of ≥3 represented and predicted neutrophilic inflammation with modest accuracy (area under the curve (AUC)=0.64; p<0.001, specificity=78.4%, sensitivity=49.2%). Participants with a sputum colour score of ≥3 had significantly (p<0.05) higher CXCL-8, total cells and neutrophil number and proportion. Sputum colour score was also positively correlated with these factors. Sputum colour score ≥3 predicted NB with reasonably good accuracy (AUC=0.79, p<0.001, specificity=79.3%, sensitivity=70.7%).

Conclusions

Visual gradation of sputum colour in asthma relates to high total cell count and neutrophilic inflammation. Assessment of sputum colour can identify adults with asthma who are likely to have NB without the need for sputum processing and differential cell count, which may facilitate asthma management.

Personalised medicine in asthma: time for action: Number 1 in the Series "Personalised medicine in respiratory diseases" Edited by Renaud Louis and Nicolas Roche

Asthma is a heterogeneous disease comprising several phenotypes driven by different pathways. To define these phenotypes or endotypes (phenotypes defined by mechanisms), an unbiased approach to clustering of various omics platforms will yield molecular phenotypes from which composite biomarkers can be obtained. Biomarkers can help differentiate between these phenotypes and pinpoint patients suitable for specific targeted therapies - the basis for personalised medicine. Biomarkers need to be linked to point-of-care biomarkers that may be measured readily in exhaled breath, blood or urine. The potential for using mobile healthcare approaches will help patient enpowerment, an essential tool for personalised medicine. Personalised medicine in asthma is not far off - it is already here, but we need more tools and implements to carry it out for the benefit of our patients.

Asthma Endotypes and an Overview of Targeted Therapy for Asthma

Guidelines for the management of severe asthma do not emphasize the measurement of the inflammatory component of airway disease to indicate appropriate treatments or to monitor response to treatment. Inflammation is a central component of asthma and contributes to symptoms, physiological, and structural abnormalities. It can be assessed by a number of endotyping strategies based on “omics” technology such as proteomics, transcriptomics, and metabolomics. It can also be assessed using simple cellular responses by quantitative cytometry in sputum. Bronchitis may be eosinophilic, neutrophilic, mixed-granulocytic, or paucigranulocytic (eosinophils and neutrophils not elevated). Eosinophilic bronchitis is usually a Type 2 (T2)-driven process and therefore a sputum eosinophilia of greater than 3% usually indicates a response to treatment with corticosteroids or novel therapies directed against T2 cytokines such as IL-4, IL-5, and IL-13. Neutrophilic bronchitis represents a non-T2-driven disease, which is generally a predictor of response to antibiotics and may be a predictor to therapies targeted at pathways that lead to neutrophil recruitment such as TNF, IL-1, IL-6, IL-8, IL-23, and IL-17. Paucigranulocytic disease may not warrant anti-inflammatory therapy. These patients, whose symptoms may be driven largely by airway hyper-responsiveness may benefit from smooth muscle-directed therapies such as bronchial thermoplasty or mast-cell directed therapies. This review will briefly summarize the current knowledge regarding “omics-based signatures” and cellular endotyping of severe asthma and give an overview of segmentation of asthma therapeutics guided by the endotype.

TNF-α-induced protein 3 levels in lung dendritic cells instruct TH2 or TH17 cell differentiation in eosinophilic or neutrophilic asthma

BACKGROUND

It is currently unknown why allergen exposure or environmental triggers in patients with mild-to-moderate asthma result in T_H2-mediated eosinophilic inflammation, whereas patients with severe asthma often present with T_H17-mediated neutrophilic inflammation. The activation state of dendritic cells (DCs) is crucial for both T_H2 and T_H17 cell differentiation and is mediated through nuclear factor κB activation. Ablation of TNF-α-induced protein 3 (TNFAIP3), one of the crucial negative regulators of nuclear factor κB activation in myeloid cells and DCs, was shown to control DC activation.

OBJECTIVE

In this study we investigated the precise role of TNFAIP3 in myeloid cells for the development of T_H2- and T_H17-cell mediated asthma.

METHODS

We exposed mice with conditional deletion of the Tnfaip3 gene in either myeloid cells (by using the lysozyme M [LysM] promotor) or specifically in DCs (by using the Cd11c promotor) to acute and chronic house dust mite (HDM)-driven asthma models.

RESULTS

We demonstrated that reduced Tnfaip3 gene expression in DCs in either Tnfaip3^CD11c or Tnfaip3^LysM mice dose-dependently controlled development of T_H17-mediated neutrophilic severe asthma in both acute and chronic HDM-driven models, whereas wild-type mice had a purely T_H2-mediated eosinophilic inflammation. TNFAIP3-deficient DCs induced HDM-specific T_H17 cell differentiation through increased expression of the T_H17-instructing cytokines IL-1β, IL-6, and IL-23, whereas HDM-specific T_H2 cell differentiation was hampered by increased IL-12 and IL-6 production.

CONCLUSIONS

These data show that the extent of TNFAIP3 expression in DCs controls T_H2/T_H17 cell differentiation. This implies that reducing DC activation could be a new pharmacologic intervention to treat patients with severe asthma who present with T_H17-mediated neutrophilic inflammation.

Asthma management: A new phenotype-based approach using presence of eosinophilia and allergy

Asthma is a heterogeneous disease. The Czech Pneumology and Allergology Societies commissioned 10 experts to review the literature and create joint national guidelines for managing asthma, reflecting this heterogeneity. The aim was to develop an easy-to-use diagnostic strategy as a rational approach to the widening opportunities for the use of phenotype-targeted therapy. The guidelines were presented on websites for public comments by members of both the societies. The reviewers' comments contributed to creating the final version of the guidelines. The key hallmark of the diagnostic approach is the pragmatic concept, which assesses the presence of allergy and eosinophilia in each asthmatic patient. The guidelines define three clinically relevant asthma phenotypes: eosinophilic allergic asthma, eosinophilic nonallergic asthma and noneosinophilic nonallergic asthma. The resulting multifunctional classification describing the severity, level of control and phenotype is the starting point for a comprehensive treatment strategy. The level of control is constantly confronted with the intensity of the common stepwise pharmacotherapy, and the concurrently included phenotyping is essential for phenotype-specific therapy. The concept of the asthma approach with assessing the presence of eosinophilia and allergy provides a way for more precise diagnosis, which is a prerequisite for using widening options of personalized therapy.

Tailored interventions based on sputum eosinophils versus clinical symptoms for asthma in children and adults

BACKGROUND

Asthma severity and control can be measured both subjectively and objectively. Sputum analysis for evaluation of percentage of sputum eosinophilia directly measures airway inflammation, and is one method of objectively monitoring asthma. Using sputum analysis to adjust or tailor asthma medications is potentially superior to traditional methods based on symptoms and spirometry.

OBJECTIVES

To evaluate the efficacy of tailoring asthma interventions based on sputum analysis in comparison to traditional methods (usually symptom-based with or without spirometry/peak flow) for asthma-related outcomes in children and adults.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register of Trials, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, trials' registries, and reference lists of articles. The last search was conducted in February 2017.

SELECTION CRITERIA

All randomised controlled comparisons of adjustment of asthma therapy based on sputum eosinophils compared to traditional methods (primarily clinical symptoms and spirometry/peak flow).

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against pre-determined criteria for inclusion. In this update, two reviewers selected relevant studies, independently assessed trial quality and extracted the data. We contacted authors for further information when relevant. We analysed data as 'treatment received' and performed sensitivity analyses.

MAIN RESULTS

Three new studies were added in this update, resulting in a total of six included studies (five in adults and one involving children/adolescents). These six studies were clinically and methodologically heterogeneous (use of medications, cut-off for percentage of sputum eosinophils and definition of asthma exacerbation). Of 374 participants randomised, 333 completed the trials. In the meta-analysis, there was a significant reduction in the occurrence of any exacerbations when treatment was based on sputum eosinophil counts, compared to that based on clinical symptoms with or without lung function; pooled odds ratio (OR) was 0.57 (95% confidence interval (CI) 0.38 to 0.86). The risk of having one or more exacerbations over 16 months was 82% in the control arm and 62% (95% CI 49% to 74%) in the sputum strategy arm, resulting in a number needed to treat to benefit (NNTB) of 6 (95% CI 4 to 13).There were also differences between the groups in the rate of exacerbation (any exacerbation per year) and severity of exacerbations defined by requirement for use of oral corticosteroids and hospitalisations: the risk of one or more hospitalisations over 16 months was 24% in controls compared to 8% (95% CI 3% to 21%) in the sputum arm. Data for clinical symptoms, quality of life and spirometry were not significantly different between groups. The mean dose of inhaled corticosteroids per day was also similar in both groups. However sputum induction was not always possible. The included studies did not record any adverse events.One study was not blinded and thus was considered to have a high risk of bias. However, when this study was removed in a sensitivity analysis, the difference between the groups for the primary outcome (exacerbations) remained statistically significant between groups. The GRADE quality of the evidence ranged from moderate (for the outcomes 'Occurrence of any exacerbation' and 'Hospitalisation' ) to low (for the outcome 'Mean dose of inhaled corticosteroids per person per day') due to the inconsistency in defining exacerbations and the small number of hospital admissions.

AUTHORS' CONCLUSIONS

In this updated review, tailoring asthma interventions based on sputum eosinophils is beneficial in reducing the frequency of asthma exacerbations in adults with asthma. Adults with frequent exacerbations and severe asthma may derive the greatest benefit from this additional monitoring test, although we were unable to confirm this through subgroup analysis. There is insufficient data available to assess tailoring asthma medications based on sputum eosinophilia in children.Further robust RCTs need to be undertaken and these should include participants with different underlying asthma severities and endotypes.

TNF is required for TLR ligand-mediated but not protease-mediated allergic airway inflammation

Asthma is associated with exposure to a wide variety of allergens and adjuvants. The extent to which overlap exists between the cellular and molecular mechanisms triggered by these various agents is poorly understood, but it might explain the differential responsiveness of patients to specific therapies. In particular, it is unclear why some, but not all, patients benefit from blockade of TNF. Here, we characterized signaling pathways triggered by distinct types of adjuvants during allergic sensitization. Mice sensitized to an innocuous protein using TLR ligands or house dust extracts as adjuvants developed mixed eosinophilic and neutrophilic airway inflammation and airway hyperresponsiveness (AHR) following allergen challenge, whereas mice sensitized using proteases as adjuvants developed predominantly eosinophilic inflammation and AHR. TLR ligands, but not proteases, induced TNF during allergic sensitization. TNF signaled through airway epithelial cells to reprogram them and promote Th2, but not Th17, development in lymph nodes. TNF was also required during the allergen challenge phase for neutrophilic and eosinophilic inflammation. In contrast, TNF was dispensable for allergic airway disease in a protease-mediated model of asthma. These findings might help to explain why TNF blockade improves lung function in only some patients with asthma.

A new approach to the classification and management of airways diseases: identification of treatable traits

This review outlines a new, personalized approach for the classification and management of airway diseases. The current approach to airways disease is, we believe, no longer fit for purpose. It is impractical, overgeneralizes complex and heterogeneous conditions and results in management that is imprecise and outcomes that are worse than they could be. Importantly, the assumptions we make when applying a diagnostic label have impeded new drug discovery and will continue to do so unless we change our approach. This review suggests a new mechanism-based approach where the emphasis is on identification of key causal mechanisms and targeted intervention with treatment based on possession of the relevant mechanism rather than an arbitrary label. We highlight several treatable traits and suggest how they can be identified and managed in different healthcare settings.

Gamma tocopherol-enriched supplement reduces sputum eosinophilia and endotoxin-induced sputum neutrophilia in volunteers with asthma

BACKGROUND

We and others have shown that the gamma tocopherol (γT) isoform of vitamin E has multiple anti-inflammatory and antioxidant actions and that γT supplementation reduces eosinophilic and endotoxin (LPS)-induced neutrophilic airway inflammation in animal models and healthy human volunteers.

OBJECTIVE

We sought to determine whether γT supplementation reduces eosinophilic airway inflammation and acute neutrophilic response to inhaled LPS challenge in volunteers with asthma.

METHODS

Participants with mild asthma were enrolled in a double-blinded, placebo-controlled crossover study to assess the effect of 1200 mg of γT daily for 14 days on sputum eosinophils, mucins, and cytokines. We also assessed the effect on acute inflammatory response to inhaled LPS challenge following γT treatment, focusing on changes in sputum neutrophilia, mucins, and cytokines. Mucociliary clearance was measured using gamma scintigraphy.

RESULTS

Fifteen subjects with mild asthma completed both arms of the study. Compared with placebo, γT notably reduced pre-LPS challenge sputum eosinophils and mucins, including mucin 5AC and reduced LPS-induced airway neutrophil recruitment 6 and 24 hours after challenge. Mucociliary clearance was slowed 4 hours postchallenge in the placebo group but not in the γT treatment group. Total sputum mucins (but not mucin 5AC) were reduced at 24 hours postchallenge during γT treatment compared with placebo.

CONCLUSIONS

When compared with placebo, γT supplementation for 14 days reduced inflammatory features of asthma, including sputum eosinophils and mucins, as well as acute airway response to inhaled LPS challenge. Larger scale clinical trials are needed to assess the efficacy of γT supplements as a complementary or steroid-sparing treatment for asthma.

Novel Biologicals for the Treatment of Allergic Diseases and Asthma

PURPOSE OF REVIEW

The development of biological therapies has rapidly progressed during the last few years, and major advances were reported for the treatment of allergic diseases, such as atopic dermatitis, allergic rhinitis, urticaria, food allergy, and asthma. Here, we review biologicals targeting the type 2 immune response involving Th2 cells, type 2 innate lymphoid cells, natural killer T cells, mast cells, basophils, and epithelial cells, such as IL-4, IL-5, IL-13, IL-31, tumor necrosis factor alpha (TNF-α), and thymic stromal lymphopoietin (TSLP).

RECENT FINDINGS

The biologicals that have been currently approved for asthma are omalizumab targeting IgE and reslizumab and mepolizumab targeting interleukin (IL)-5. Many other monoclonal antibodies are currently in various phases of clinical development. The new biological therapies for allergic diseases will eventually be tailored to the endotypes of these diseases and the identification of novel biomarkers. Further development of novel biologicals for the treatment of allergic diseases and asthma will be possible upon improved understanding of mechanisms of allergic diseases. Accordingly, further refinement of endotypes of allergen-specific and non-specific type 2 immune response and related inflammatory mediators is needed for optimal treatment of allergic diseases.

Endotypes of difficult-to-control asthma in inner-city African American children

African Americans have higher rates of asthma prevalence, morbidity, and mortality in comparison with other racial groups. We sought to characterize endotypes of childhood asthma severity in African American patients in an inner-city pediatric asthma population. Baseline blood neutrophils, blood eosinophils, and 38 serum cytokine levels were measured in a sample of 235 asthmatic children (6-17 years) enrolled in the NIAID (National Institute of Allergy and Infectious Diseases)-sponsored Asthma Phenotypes in the Inner City (APIC) study (ICAC (Inner City Asthma Consortium)-19). Cytokines were quantified using a MILLIPLEX panel and analyzed on a Luminex analyzer. Patients were classified as Easy-to-Control or Difficult-to-Control based on the required dose of controller medications over one year of prospective management. A multivariate variable selection procedure was used to select cytokines associated with Difficult-to-Control versus Easy-to-Control asthma, adjusting for age, sex, blood eosinophils, and blood neutrophils. In inner-city African American children, 12 cytokines were significant predictors of Difficult-to-Control asthma (n = 235). CXCL-1, IL-5, IL-8, and IL-17A were positively associated with Difficult-to-Control asthma, while IL-4 and IL-13 were positively associated with Easy-to-Control asthma. Using likelihood ratio testing, it was observed that in addition to blood eosinophils and neutrophils, serum cytokines improved the fit of the model. In an inner-city pediatric population, serum cytokines significantly contributed to the definition of Difficult-to-Control asthma endotypes in African American children. Mixed responses characterized by TH2 (IL-5) and TH17-associated cytokines were associated with Difficult-to-Control asthma. Collectively, these data may contribute to risk stratification of Difficult-to-Control asthma in the African American population.

Race is associated with differences in airway inflammation in patients with asthma

BACKGROUND

African American subjects have a greater burden from asthma compared with white subjects. Whether the pattern of airway inflammation differs between African American and white subjects is unclear.

OBJECTIVE

We sought to compare sputum airway inflammatory phenotypes of African American and white subjects treated or not with inhaled corticosteroids (ICSs; ICS+ and ICS-, respectively).

METHODS

We performed a secondary analysis of self-identified African American and white subjects with asthma enrolled in clinical trials conducted by the National Heart, Lung, and Blood Institute-sponsored Asthma Clinical Research Network and AsthmaNet. Demographics, clinical characteristics, and sputum cytology after sputum induction were examined. We used a sputum eosinophil 2% cut point to define subjects with either an eosinophilic (≥2%) or noneosinophilic (<2%) inflammatory phenotype.

RESULTS

Among 1018 participants, African American subjects (n = 264) had a lower FEV1 percent predicted (80% vs 85%, P < .01), greater total IgE levels (197 vs 120 IU/mL, P < .01), and a greater proportion with uncontrolled asthma (43% vs 28%, P < .01) compared with white subjects (n = 754). There were 922 subjects in the ICS+ group (248 African American and 674 white subjects) and 298 subjects in the ICS- group (49 African American and 249 white subjects). Eosinophilic airway inflammation was not significantly different between African American and white subjects in either group (percentage with eosinophilic phenotype: ICS+ group: 19% vs 16%, P = .28; ICS- group: 39% vs 35%, P = .65; respectively). However, when adjusted for confounding factors, African American subjects were more likely to exhibit eosinophilic airway inflammation than white subjects in the ICS+ group (odds ratio, 1.58; 95% CI, 1.01-2.48; P = .046) but not in the ICS- group (P = .984).

CONCLUSION

African American subjects exhibit greater eosinophilic airway inflammation, which might explain the greater asthma burden in this population.

Pathogenesis of asthma: implications for precision medicine

The pathogenesis of asthma is complex and multi-faceted. Asthma patients have a diverse range of underlying dominant disease processes and pathways despite apparent similarities in clinical expression. Here, we present the current understanding of asthma pathogenesis. We discuss airway inflammation (both T2^HIGH and T2^LOW), airway hyperresponsiveness (AHR) and airways remodelling as four key factors in asthma pathogenesis, and also outline other contributory factors such as genetics and co-morbidities. Response to current asthma therapies also varies greatly, which is probably related to the inter-patient differences in pathogenesis. Here, we also summarize how our developing understanding of detailed pathological processes potentially translates into the targeted treatment options we require for optimal asthma management in the future.

Responsiveness to oral prednisolone in severe asthma is related to the degree of eosinophilic airway inflammation

BACKGROUND

Patients with severe asthma appear relatively corticosteroid resistant. Corticosteroid responsiveness is closely related to the degree of eosinophilic airway inflammation. The extent to which eosinophilic airway inflammation in severe asthma responds to treatment with systemic corticosteroids is not clear.

OBJECTIVE

To relate the physiological and inflammatory response to systemic corticosteroids in asthma to disease severity and the baseline extent of eosinophilic inflammation.

METHODS

Patients with mild/moderate and severe asthma were investigated before and after 2 weeks of oral prednisolone (Clintrials.gov NCT00331058 and NCT00327197). We pooled the results from two studies with common protocols. The US study contained two independent centres and the UK one independent centre. The effect of oral corticosteroids on FEV₁ , Pc20, airway inflammation and serum cytokines was investigated. Baseline measurements were compared with healthy subjects.

RESULTS

Thirty-two mild/moderate asthmatics, 50 severe asthmatics and 35 healthy subjects took part. At baseline, both groups of asthmatics had a lower FEV₁ and Pc20 and increased eosinophilic inflammation compared to healthy subjects. The severe group had a lower FEV₁ and more eosinophilic inflammation compared to mild/moderate asthmatics. Oral prednisolone caused a similar degree of suppression of eosinophilic inflammation in all compartments in both groups of asthmatics. There were small improvements in FEV₁ and Pc20 for both mild/ moderate and severe asthmatics with a correlation between the baseline eosinophilic inflammation and the change in FEV₁ . There was a ~50% reduction in the serum concentration of CXCL10 (IP-10), CCL22 (MDC), CCL17 (TARC), CCL-2 (MCP-1) and CCL-13 (MCP-4) in both asthma groups after oral corticosteroids.

CONCLUSIONS AND CLINICAL RELEVANCE

Disease severity does not influence the response to systemic corticosteroids. The study does not therefore support the concept that severe asthma is associated with corticosteroid resistance. Only baseline eosinophilic inflammation was associated with the physiological response to corticosteroids, confirming the importance of measuring eosinophilic inflammation to guide corticosteroid use.

Precision medicine in patients with allergic diseases: Airway diseases and atopic dermatitis-PRACTALL document of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma & Immunology

In this consensus document we summarize the current knowledge on major asthma, rhinitis, and atopic dermatitis endotypes under the auspices of the PRACTALL collaboration platform. PRACTALL is an initiative of the European Academy of Allergy and Clinical Immunology and the American Academy of Allergy, Asthma & Immunology aiming to harmonize the European and American approaches to best allergy practice and science. Precision medicine is of broad relevance for the management of asthma, rhinitis, and atopic dermatitis in the context of a better selection of treatment responders, risk prediction, and design of disease-modifying strategies. Progress has been made in profiling the type 2 immune response-driven asthma. The endotype driven approach for non-type 2 immune response asthma, rhinitis, and atopic dermatitis is lagging behind. Validation and qualification of biomarkers are needed to facilitate their translation into pathway-specific diagnostic tests. Wide consensus between academia, governmental regulators, and industry for further development and application of precision medicine in management of allergic diseases is of utmost importance. Improved knowledge of disease pathogenesis together with defining validated and qualified biomarkers are key approaches to precision medicine.

Biomarkers in asthmatic patients: Has their time come to direct treatment?

Asthma is a heterogeneous disease with multiple phenotypes that have variable risk factors and responses to therapeutics. Mild-to-moderate asthma often responds to traditional medications, whereas severe disease can be refractory to inhaled corticosteroids, long-acting β-agonists, and leukotriene receptor antagonists. There is robust research into the variable phenotypes of asthma. Biomarkers help define the specific pathophysiology of different asthma phenotypes and identify potential therapeutic targets. The following review will discuss the current use of biomarkers for the diagnosis of asthma, triaging the severity of a patient's disease, and the potential efficacy of treatments. This information can be used to define certain patient populations that are more likely to respond to inhaled corticosteroids or biologics. As knowledge of patient phenotypes and endotypes and biological agents to target specific classes of asthma emerge, the ability to provide personalized care to asthmatic patients will follow.

Eosinophils in COPD: just another biomarker?

Eosinophils are innate immune cells that, under certain conditions, can be recruited to the lungs, where they have an incompletely understood role in health and disease. Eosinophils have been found in the airways, tissues, and circulation of patients with COPD, during both stable disease and exacerbations. Epidemiological studies and post-hoc analyses of clinical trials of corticosteroid treatment for COPD have shown that the blood eosinophil count is associated with the risk of COPD exacerbations, mortality, decline in FEV₁, and response to both inhaled and systemic corticosteroids. Further studies are urgently needed to explore the contribution of eosinophils to the mechanism of disease in COPD and to identify their association with levels of clinical risk. In this review, we explore the role of the eosinophil as a biomarker and mediator of disease in COPD.

Clinical phenotypes in asthma during childhood

Asthma is a heterogeneous disease characterized by numerous phenotypes relating to age of onset, triggers, comorbidities, severity (assessed by multiple exacerbations, lung function pattern) and finally the inflammatory cells involved in the pathophysiologic pathway. These phenotypes can vary over time in relation to changes in the principal triggers involved in the aetiology of the disease. Nevertheless, in a patient with multiple allergies and early-onset disease (defined as multiple sensitizations and allergic comorbidities), the prognosis of asthma is poor with a high risk of persistence and severity of the disease during childhood. Future research will focus on classifying phenotypes into groups based on pathophysiologic mechanisms (endotypes) and the biomarkers attached to these endotypes, which could predict prognosis and lead to targeted therapy. Currently, these biomarkers are related to inflammatory cells associated with the asthma endotype, essentially eosinophils and neutrophils (and related cytokines) attached to Th-2 and non Th-1 pathways, respectively. The most severe asthma (refractory asthma) is linked to neutrophil-derived inflammation (frequently associated with female sex, obesity and possibly disorganized airway microbiota) encountered in very young children or teenagers. Severe asthma is also linked to or a marked eosinophil inflammatory process (frequently associated with multiple atopy and, more rarely, with non-atopic hypereosinophilic asthma in children) and frequently encountered in teenagers. Severe phenotypes of asthma could also play a role in the origin of chronic obstructive pulmonary disease in adult life.

Asthma Control and Sputum Eosinophils: A Longitudinal Study in Daily Practice

BACKGROUND

Longitudinal trials have suggested that asthma control may be influenced by fluctuations in eosinophilic inflammation. This association has however never been confirmed in daily practice.

OBJECTIVE

To investigate the relationship between asthma control and sputum eosinophils in clinical practice.

METHODS

A retrospective longitudinal study was conducted on 187 patients with asthma with at least 2 successful sputum inductions at our Asthma Clinic. Linear mixed models were used to assess the relationship between asthma control and individual changes in sputum eosinophils. Receiver-operating characteristic curves were constructed to define minimal important differences (MIDs) of sputum eosinophils associated with a change of at least 0.5 in Asthma Control Questionnaire (ACQ) score. Then, a validation cohort of 79 patients with asthma was recruited to reassess this relationship and the accuracy of the MID values.

RESULTS

A multivariate analysis showed that asthma control was independently associated with individual fluctuations in sputum eosinophil count (P < .001). In patients with intermittent/persistently eosinophilic asthma, we calculated a minimal important decrease of 4.3% in the percentage of sputum eosinophils (area under the curve [AUC], 0.69; P < .001) or 3.4-fold (AUC, 0.65; P = .003) for a significant improvement in asthma control and a minimal important increase of 3.5% (AUC, 0.67; P = .004) or 1.8-fold (AUC, 0.63; P = .02) for a significant worsening in asthma control. The association between asthma control and sputum eosinophils and the accuracy of the MIDs of sputum eosinophils were confirmed in the validation cohort.

CONCLUSIONS

At the individual level, asthma control was associated with fluctuations in sputum eosinophil count over time.

Inflammatory biomarkers for asthma endotyping and consequent personalized therapy

INTRODUCTION

We argue that asthma be considered a syndrome caused by multiple inflammatory pathogenic processes. Bronchial hyperresponsiveness, reversible airflow limitation, and chronic airway inflammation characterize asthma pathophysiology. Personalized Medicine, i.e. a tailored management approach, is appropriate for asthma management and is based on the identification of discrete phenotypes and endotypes. Biomarkers can help define phenotypes and endotypes. Several biomarkers have been described in asthma, but most of them are not commonly available or still need external validation. Areas covered: This review presents useful pragmatic biomarkers available in daily clinical practice for assessing airway inflammation in asthmatic patients. Expert commentary: Eosinophil counts and serum allergen-specific IgE assessments are the most reliable biomarkers. Lung function, mainly concerning FEF_25-75, and nasal cytology may be envisaged as ancillary biomarkers in asthma management. In conclusion, biomarkers have a clinical relevance in asthma in identifying asthma endotypes to direct personalized therapy.

Association of Blood Eosinophil and Blood Neutrophil Counts with Asthma Exacerbations in the Copenhagen General Population Study

BACKGROUND

Blood eosinophil count is a marker of eosinophilic airway inflammation and disease severity in asthma. However, blood neutrophil count might also be associated with disease severity. We tested the hypothesis that high blood eosinophil and neutrophil counts are both associated with the risk of asthma exacerbations among individuals with asthma from the general population.

METHODS

From the Copenhagen General Population Study with 81351 participants, we included 4838 with self-reported asthma. We recorded baseline blood eosinophil and neutrophil counts, and asthma exacerbations during follow-up in 2003–2011, defined as moderate (short-course treatment of prednisolone) or severe (hospitalization).

RESULTS

The multivariable-adjusted incidence rate ratios (IRRs) were 1.28 (95% CI, 1.06–1.55) for moderate exacerbations and 1.55 (1.20–2.00) for severe exacerbations for individuals with blood eosinophil counts &gt;0.29 × 109/L (highest tertile) vs individuals with blood eosinophil counts &lt;0.18 × 109/L (lowest tertile). For blood neutrophils, the multivariable-adjusted IRRs were 2.14 (1.74–2.63) for moderate exacerbations and 1.18 (0.89–1.55) for severe exacerbations for individuals with blood neutrophil counts &gt;4.85 × 109/L (highest tertile) vs individuals with blood neutrophil counts &lt;3.77 × 109/L (lowest tertile). Blood eosinophil and neutrophil counts interacted on moderate exacerbations (P = 3 × 10−4), but not on severe exacerbations.

CONCLUSIONS

High blood eosinophil counts are associated with an increased risk of both moderate and severe asthma exacerbations, while high blood neutrophil counts are associated with an increased risk of moderate, but not severe exacerbations.

Neutrophilic Steroid-Refractory Recurrent Wheeze and Eosinophilic Steroid-Refractory Asthma in Children

BACKGROUND

Little is known about inflammatory pathways of severe recurrent wheeze in preschool children and severe asthma in children.

OBJECTIVES

The aim of the Severe Asthma Molecular Phenotype cohort was to characterize phenotypes of severe recurrent wheeze and severe asthma during childhood in terms of triggers (allergic or not), involved cells (eosinophil or neutrophil), and corticoid responsiveness.

METHODS

Children with moderate-to-severe asthma and preschool children with moderate-to-severe recurrent wheeze were enrolled prospectively. They underwent standardized clinical and blood workup, and bronchoalveolar lavage (BAL) evaluation. Cluster analysis was applied to 350 children with 34 variables.

RESULTS

Three clusters were identified: cluster 1, Neutrophilic steroid-refractory recurrent wheeze phenotype, with 138 children uncontrolled despite high-dose inhaled corticosteroids (ICS) (92%, P < .001), with more history of pneumonia (31%, P < .001), more gastroesophageal reflux disease (37%, P < .001), and the highest blood neutrophil count (mean 4.524 cells/mm³, P = .05); cluster 2, Severe recurrent wheeze with sensitization to a single aeroallergen (12%, P = .002), with 104 children controlled with high-dose ICS (63%, P < .001); cluster 3, Eosinophilic steroid-refractory asthma phenotype, with 108 children uncontrolled despite high-dose ICS (76%, P < .001) with more allergic rhinitis, atopic dermatitis, and food allergies (82%, 40%, 31%, P < .001, respectively). They also had a higher blood eosinophil count and a higher percentage of BAL eosinophil (506/mm³, 2.6%, P < .001 respectively).

CONCLUSIONS

Inflammation pathway of asthma and recurrent wheeze are related to eosinophil cells in older children and neutrophil cells in younger children. These results could improve personalized treatments.

Asthma and obesity

The problem of modern medicine is to optimize the treatment of patients with comorbidity, whose number has been growing steadily in recent years. The concurrence of asthma and obesity determines the severity of disease, low-level control, and resistance to basic therapy in conjunction with more frequent use of β-agonists for relief of symptoms, and frequent hospitalizations for a disease exacerbation. Currently, there are only a few known pathogenetic components that are responsible for the negative impact of visceral obesity on the course of asthma.

Reslizumab and Eosinophilic Asthma: One Step Closer to Precision Medicine?

Human eosinophils represent approximately 1% of peripheral blood leukocytes. However, these cells have the propensity to leave the blood stream and migrate into inflamed tissues. Eosinophilic inflammation is present in a significant proportion of patients with severe asthma. Asthma is a chronic inflammatory disorder that affects more than 315 million people worldwide, with 10% having severe uncontrolled disease. Although the majority of patients can be efficiently treated, severe asthmatics continue to be uncontrolled and are at risk of exacerbations and even death. Interleukin-5 (IL-5) plays a fundamental role in eosinophil differentiation, maturation, activation and inhibition of apoptosis. Therefore, targeting IL-5 is an appealing approach to the treatment of patients with severe eosinophilic asthma. Reslizumab, a humanized anti-IL-5 monoclonal antibody, binds with high affinity to amino acids 89–92 of IL-5 that are critical for binding to IL-5 receptor α. Two phase III studies have demonstrated that reslizumab administration in adult patients with severe asthma and eosinophilia (≥400 cells/μL) improved lung function, asthma control, and symptoms. Thus, the use of blood eosinophils as a baseline biomarker could help to select patients with severe uncontrolled asthma who are likely to achieve benefits in asthma control with reslizumab. In conclusion, targeted therapy with reslizumab represents one step closer to precision medicine in patients with severe eosinophilic asthma.

Cluster analysis of sputum cytokine-high profiles reveals diversity in T(h)2-high asthma patients

Background

Asthma is characterized by a heterogeneous inflammatory profile and can be subdivided into T(h)2-high and T(h)2-low airway inflammation. Profiling of a broader panel of airway cytokines in large unselected patient cohorts is lacking.

Methods

Patients (n = 205) were defined as being “cytokine-low/high” if sputum mRNA expression of a particular cytokine was outside the respective 10^th/90^th percentile range of the control group (n = 80). Unsupervised hierarchical clustering was used to determine clusters based on sputum cytokine profiles.

Results

Half of patients (n = 108; 52.6%) had a classical T(h)2-high (“IL-4-, IL-5- and/or IL-13-high”) sputum cytokine profile. Unsupervised cluster analysis revealed 5 clusters. Patients with an “IL-4- and/or IL-13-high” pattern surprisingly did not cluster but were equally distributed among the 5 clusters. Patients with an “IL-5-, IL-17A-/F- and IL-25- high” profile were restricted to cluster 1 (n = 24) with increased sputum eosinophil as well as neutrophil counts and poor lung function parameters at baseline and 2 years later. Four other clusters were identified: “IL-5-high or IL-10-high” (n = 16), “IL-6-high” (n = 8), “IL-22-high” (n = 25). Cluster 5 (n = 132) consists of patients without “cytokine-high” pattern or patients with only high IL-4 and/or IL-13.

Conclusion

We identified 5 unique asthma molecular phenotypes by biological clustering. Type 2 cytokines cluster with non-type 2 cytokines in 4 out of 5 clusters. Unsupervised analysis thus not supports a priori type 2 versus non-type 2 molecular phenotypes. www.clinicaltrials.gov NCT01224938. Registered 18 October 2010.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0524-y) contains supplementary material, which is available to authorized users.

Glucocorticoid receptor expression on circulating leukocytes differs between healthy male and female adults

Introduction

The glucocorticoid receptor (GR) is a key receptor involved in inflammatory responses and is influenced by sex steroids. This study measured GR expression on circulating leukocyte subtypes in males and females.

Methods

A total of 23 healthy adults (12 female) participated in this study. GR expression was measured in leukocyte subtypes using flow cytometry. Peripheral blood mononuclear cell (PBMC) gene expression of GR (NR3C1), GR β, TGF-β1 and 2, and glucocorticoid-induced leucine zipper (GILZ) were determined by real-time polymerase chain reaction.

Results

Leukocyte GR was lower in females, particularly in granulocytes, natural killer cells, and peripheral blood mononuclear cells (p≤0.01). GR protein expression was different across leukocyte subtypes, with higher expression in eosinophils compared with granulocytes, T lymphocytes, and natural killer cells (p<0.05). There was higher gene expression of GR β in males (p=0.03).

Conclusions

This is the first study to identify sexual dimorphism in GR expression in healthy adults using flow cytometry. These results may begin to explain the sexual dimorphism seen in many diseases and sex differences in glucocorticoid responsiveness.

T-helper cell type 2 (Th2) and non-Th2 molecular phenotypes of asthma using sputum transcriptomics in U-BIOPRED

Asthma is characterised by heterogeneous clinical phenotypes. Our objective was to determine molecular phenotypes of asthma by analysing sputum cell transcriptomics from 104 moderate-to-severe asthmatic subjects and 16 nonasthmatic subjects.After filtering on the differentially expressed genes between eosinophil- and noneosinophil-associated sputum inflammation, we used unbiased hierarchical clustering on 508 differentially expressed genes and gene set variation analysis of specific gene sets.We defined three transcriptome-associated clusters (TACs): TAC1 (characterised by immune receptors IL33R, CCR3 and TSLPR), TAC2 (characterised by interferon-, tumour necrosis factor-α- and inflammasome-associated genes) and TAC3 (characterised by genes of metabolic pathways, ubiquitination and mitochondrial function). TAC1 showed the highest enrichment of gene signatures for interleukin-13/T-helper cell type 2 (Th2) and innate lymphoid cell type 2. TAC1 had the highest sputum eosinophilia and exhaled nitric oxide fraction, and was restricted to severe asthma with oral corticosteroid dependency, frequent exacerbations and severe airflow obstruction. TAC2 showed the highest sputum neutrophilia, serum C-reactive protein levels and prevalence of eczema. TAC3 had normal to moderately high sputum eosinophils and better preserved forced expiratory volume in 1 s. Gene-protein coexpression networks from TAC1 and TAC2 extended this molecular classification.We defined one Th2-high eosinophilic phenotype TAC1, and two non-Th2 phenotypes TAC2 and TAC3, characterised by inflammasome-associated and metabolic/mitochondrial pathways, respectively.

Two inflammatory phenotypes of nasal polyps and comorbid asthma

BACKGROUND

Nasal polyps and comorbid asthma (NPCA) is a common united airway disease. However, the inflammatory phenotyes of NPCA are not clear.

OBJECTIVE

To identify inflammatory phenotypes of NPCA.

METHODS

A total of 106 patients diagnosed with NPCA were recruited from rhinologic clinics. A combined method of biopsies from nasal polyps and fractional exhaled nitric oxide (FeNO) was used to explore inflammatory phenotyes of NPCA. Patients were evaluated with respect to clinical, functional, and inflammatory parameters. Clinical outcomes after medical treatment were also assessed.

RESULTS

Two distinct inflammatory phenotypes (eosinophilic [64.15%] and noneosinophilic phenotypes [35.85%]) were identified. Inflammatory patterns of upper and lower airways were consistent in NPCA. Patients with eosinophilic NPCA had a higher nasal polyps recurrence rate than did patients with noneosinophilic NPCA, a more severe asthma phenotype (P < .001), higher exhaled nitric oxide levels (P < .001), higher IgE levels (P < .001), higher Lund-Mackay scores (P < .05), and more blood eosinophilia (P < .001). In addition, eosinophilic NPCA was associated with worse pulmonary function and responded well to an 8-week course of medical treatment based on computed tomographic findings and the ratio of forced expiratory volume in 1 second to forced vital capacity. The total IgE concentration was a marker for eosinophilic NPCA (optimal cutoff, >55.5 kU/L; sensitivity, 86.2%; specificity, 85.4%).

CONCLUSION

Patients with NPCA had 2 inflammatory phenotypes with distinct clinical profiles. Total IgE is a marker of eosinophilic NPCA.

Bcl-2 inhibitors reduce steroid-insensitive airway inflammation

BACKGROUND

Asthmatic inflammation is dominated by accumulation of either eosinophils, neutrophils, or both in the airways. Disposal of these inflammatory cells is the key to disease control. Eosinophilic airway inflammation is responsive to corticosteroid treatment, whereas neutrophilic inflammation is resistant and increases the burden of global health care. Corticosteroid-resistant neutrophilic asthma remains mechanistically poorly understood and requires novel effective therapeutic strategies.

OBJECTIVE

We sought to explore the underlying mechanisms of airway inflammation persistence, as well as corticosteroid resistance, and to investigate a new strategy of effective treatment against corticosteroid-insensitive neutrophilic asthma.

METHODS

Mouse models of either eosinophil-dominated or neutrophil-dominated airway inflammation were used in this study to test corticosteroid sensitivity in vivo and in vitro. We also used vav-Bcl-2 transgenic mice to confirm the importance of granulocytes apoptosis in the clearance of airway inflammation. Finally, the Bcl-2 inhibitors ABT-737 or ABT-199 were tested for their therapeutic effects against eosinophilic or neutrophilic airway inflammation and airway hyperresponsiveness.

RESULTS

Overexpression of Bcl-2 protein was found to be responsible for persistence of granulocytes in bronchoalveolar lavage fluid after allergic challenge. This was important because allergen-induced airway inflammation aggravated and persisted in vav-Bcl-2 transgenic mice, in which nucleated hematopoietic cells were overexpressed with Bcl-2 and resistant to apoptosis. The Bcl-2 inhibitors ABT-737 or ABT-199 play efficient roles in alleviation of either eosinophilic or corticosteroid-resistant neutrophilic airway inflammation by inducing apoptosis of immune cells, such as eosinophils, neutrophils, T_H2 cells, T_H17 cells, and dendritic cells. Moreover, these inhibitors were found to be more efficient than steroids to induce granulocyte apoptosis ex vivo from patients with severe asthma.

CONCLUSION

Apoptosis of inflammatory cells is essential for clearance of allergen-induced airway inflammation. The Bcl-2 inhibitors ABT-737 or ABT-199 might be promising drugs for the treatment of airway inflammation, especially for corticosteroid-insensitive neutrophilic airway inflammation.

Therapeutic approaches to asthma-chronic obstructive pulmonary disease overlap

INTRODUCTION

Patients with features of both asthma and chronic obstructive pulmonary disease (COPD) ('asthma-COPD overlap') experience greater symptom burden and higher risk of adverse health outcomes than those with asthma or COPD alone. However, virtually no pharmacotherapy studies have been performed in this overlap population, leading to confusion amongst clinicians regarding therapeutic approaches. Areas covered: A pragmatic approach is suggested to identify patients with typical asthma, typical COPD, and those with overlap features. Interim clinical guidance on the treatment of asthma-COPD overlap is provided, acknowledging that these recommendations are based on expert opinion given the paucity of available evidence. Expert commentary: There is an urgent need for new studies in patients with asthma-COPD overlap to evaluate the efficacy and safety of existing pharmacotherapeutic options. Multiple underlying mechanisms are likely to contribute to the development of asthma-COPD overlap and a greater understanding of these mechanisms may allow a personalised approach to therapy in the future.

Neutrophilic inflammation in asthma: mechanisms and therapeutic considerations

INTRODUCTION

Neutrophilic airway inflammation represents a pathologically distinct form of asthma and frequently appears in symptomatic adulthood asthmatics. However, clinical impacts and mechanisms of the neutrophilic inflammation have not been thoroughly evaluated up to date. Areas covered: Currently, distinct clinical manifestations, triggers, and molecular mechanisms of the neutrophilic inflammation (namely Toll-like receptor, Th1, Th17, inflammasome) are under investigation in asthma. Furthermore, possible role of the neutrophilic inflammation is being investigated in respect to the airway remodeling. We searched the related literatures published during the past 10 years on the website of Pub Med under the title of asthma and neutrophilic inflammation in human. Expert commentary: Epidemiologic and experimental studies have revealed that the neutrophilic airway inflammation is induced by a wide variety of stimuli including ozone, particulate matters, cigarette smoke, occupational irritants, endotoxins, microbial infection and colonization, and aeroallergens. These triggers provoke diverse immune and inflammatory responses leading to progressive and sometimes irreversible airway obstruction. Clinically, neutrophilic airway inflammation is frequently associated with severe asthma and poor response to glucocorticoid therapy, indicating the need for other treatment strategies. Accordingly, therapeutics will be targeted against the main mediators behind the underlying molecular mechanisms of the neutrophilic inflammation.

Biomarkers in the Management of Difficult Asthma

Difficult asthma is a heterogeneous disease of the airways including various types of bronchial inflammation and various degrees of airway remodeling. Therapeutic response of severe asthmatics can be predicted by the use of biomarkers of Type2-high or Type2-low inflammation. Based on sputum cell analysis, four inflammatory phenotypes have been described. As induced sputum is time-consuming and expensive technique, surrogate biomarkers are useful in clinical practice.

Eosinophilic phenotype is likely to reflect ongoing adaptive immunity in response to allergen. Several biomarkers of eosinophilic asthma are easily available in clinical practice (blood eosinophils, serum IgE, exhaled nitric oxyde, serum periostin). Neutrophilic asthma is thought to reflect innate immune system activation in response to pollutants or infectious agents while paucigranulocytic asthma is thought to be not inflammatory and characterized by smooth muscle dysfunction. We currently lack of user-friendly biomarkers of neutrophilic asthma and airway remodeling.

In this review, we summarize the biomarkers available for the management of difficult asthma.

Monoclonal antibody therapy for the treatment of asthma and chronic obstructive pulmonary disease with eosinophilic inflammation

Eosinophils have been linked with asthma for more than a century, but their role has been unclear. This review discusses the roles of eosinophils in asthma and chronic obstructive pulmonary disease (COPD) and describes therapeutic antibodies that affect eosinophilia. The aims of pharmacologic treatments for pulmonary conditions are to reduce symptoms, slow decline or improve lung function, and reduce the frequency and severity of exacerbations. Inhaled corticosteroids (ICS) are important in managing symptoms and exacerbations in asthma and COPD. However, control with these agents is often suboptimal, especially for patients with severe disease. Recently, new biologics that target eosinophilic inflammation, used as adjunctive therapy to corticosteroids, have proven beneficial and support a pivotal role for eosinophils in the pathology of asthma. Nucala® (mepolizumab; anti-interleukin [IL]-5) and Cinquair® (reslizumab; anti-IL-5), the second and third biologics approved, respectively, for the treatment of asthma, exemplifies these new treatment options. Emerging evidence suggests that eosinophils may contribute to exacerbations and possibly to lung function decline for a subset of patients with COPD. Here we describe the pharmacology of therapeutic antibodies inhibiting IL-5 or targeting the IL-5 receptor, as well as other cytokines contributing to eosinophilic inflammation. We discuss their roles as adjuncts to conventional therapeutic approaches, especially ICS therapy, when disease is suboptimally controlled. These agents have achieved a place in the therapeutic armamentarium for asthma and COPD and will deepen our understanding of the pathogenic role of eosinophils.