Periostin is a systemic biomarker of eosinophilic airway inflammation in asthmatic patients

Current and future biomarkers in allergic asthma

Diagnosis early in life, sensitization, asthma endotypes, monitoring of disease and treatment progression are key motivations for the exploration of biomarkers for allergic rhinitis and allergic asthma. The number of genes related to allergic rhinitis and allergic asthma increases steadily; however, prognostic genes have not yet entered clinical application. We hypothesize that the combination of multiple genes may generate biomarkers with prognostic potential. The current review attempts to group more than 161 different potential biomarkers involved in respiratory inflammation to pave the way for future classifiers. The potential biomarkers are categorized into either epithelial or infiltrate-derived or mixed origin, epithelial biomarkers. Furthermore, surface markers were grouped into cell-type-specific categories. The current literature provides multiple biomarkers for potential asthma endotypes that are related to T-cell phenotypes such as Th1, Th2, Th9, Th17, Th22 and Tregs and their lead cytokines. Eosinophilic and neutrophilic asthma endotypes are also classified by epithelium-derived CCL-26 and osteopontin, respectively. There are currently about 20 epithelium-derived biomarkers exclusively derived from epithelium, which are likely to innovate biomarker panels as they are easy to sample. This article systematically reviews and categorizes genes and collects current evidence that may promote these biomarkers to become part of allergic rhinitis or allergic asthma classifiers with high prognostic value.

Diagnosis and investigation in the severe asthma clinic

Severe asthma is recognised as an important and emerging area of unmet need in asthma. The assessment of severe asthma should include three steps; (1) determining the diagnosis of asthma, including verification that the disease is severe asthma, (2) assessing comorbidities and contributing factors that will impact on clinical severity, as well as (3) assessing asthma phenotypes. These steps recognize the importance of heterogeneity in asthma as a key factor that determines the disease course and increasingly the choice of successful therapy. This assessment should be undertaken systematically and is best done by an expert multidisciplinary team. Here, we will outline the important aspects that should be included in the clinical assessment of the patient in the severe asthma clinic, including diagnosis, clinical history, the assessment of important comorbidities and the key investigations needed to support them.

Clinically relevant subgroups in COPD and asthma

As knowledge of airways disease has grown, it has become apparent that neither chronic obstructive pulmonary disease (COPD) nor asthma is a simple, easily defined disease. In the past, treatment options for both diseases were limited; thus, there was less need to define subgroups. As treatment options have grown, so has our need to predict who will respond to new drugs. To date, identifying subgroups has been largely reported by detailed clinical characterisation or differences in pathobiology. These subgroups are commonly called "phenotypes"; however, the problem of defining what constitutes a phenotype, whether this should include comorbid diseases and how to handle changes over time has led to the term being used loosely. In this review, we describe subgroups of COPD and asthma patients whose clinical characteristics we believe have therapeutic or major prognostic implications specific to the lung, and whether these subgroups are constant over time. Finally, we will discuss whether the subgroups we describe are common to both asthma and COPD, and give some examples of how treatment might be tailored in patients where the subgroup is clear, but the label of asthma or COPD is not.

Asthma control and exacerbations: two different sides of the same coin

PURPOSE OF REVIEW

Optimal asthma management includes both the control of asthma symptoms and reducing the risk of future asthma exacerbations. Traditionally, treatment has been adjusted largely on the basis of symptoms and lung function and for many patients, this approach delivers both excellent symptom control and reduced risk. However, the relationship between these two key components of the disease may vary between different asthmatic phenotypes and disease severities and there is increasing recognition of the need for more individualized treatment approaches.

RECENT FINDINGS

A number of factors which predict exacerbation risk have been identified including demographic and behavioural features and specific inflammatory biomarkers. Type-2 cytokine-driven eosinophilic airways inflammation predisposes to frequent exacerbations and predicts response to corticosteroids, and the usefulness of sputum eosinophilia as both a marker of exacerbation risk and biomarker for adjustment of corticosteroid treatment has been established for some time. However, attempts to develop surrogate markers, which would be more straightforward to deliver in the clinic, have been challenging.

SUMMARY

Some patients with asthma have persistent symptoms in the absence of type-2 cytokine driven-eosinophilic airways inflammation due to noncorticosteroid responsive mechanisms (T2-low disease). Composite biomarker strategies using easily measured surrogate indicators of type-2 inflammation (such as fractional exhaled nitric oxide, blood eosinophil count and serum periostin levels) may predict exacerbation risk better but it is unclear if they can be used to adjust corticosteroid treatment. Biomarkers will be used to target novel biologic treatments but additionally may be used to optimize corticosteroid treatment dose and act as prognostics for exacerbation risk and potentially other important longer term asthma outcomes.

Role of T2 inflammation biomarkers in severe asthma

PURPOSE OF REVIEW

Severe asthma is a heterogeneous syndrome. Classification of asthma into phenotypes and endotypes can improve understanding and treatment of the disease. Identification and utilization of biomarkers, particularly those linked to T2 inflammation, can help group patients into phenotypes, predict those who will respond to a specific therapy, and assess the response to treatment.

RECENT FINDINGS

Biomarkers are present in sputum, exhaled breath, and blood of patients with asthma. These include sputum eosinophils and neutrophils, fractional excretion of nitric oxide, blood eosinophilia, IgE, and periostin. Many of these biomarkers are associated with eosinophilic inflammation propagated mainly by T2 cytokines such as IL-5 and IL-13, which are released from Th2 cells and Type 2 innate lymphoid cells. Biomarkers have been utilized in recent trials of novel biologic agents targeted at T2 inflammation and may contribute to the defining population who would respond to these therapies.

SUMMARY

Despite advances in the identification and utilization of asthma biomarkers, further studies are needed to better clarify the role of biomarkers, individually or in combination, in the diagnosis and treatment of severe asthma. Future therapeutic trials should include the use of biomarkers in their design, which may lead to a more personalized approach to therapy and improved outcomes.

Targeting the JAK-STAT pathway in the treatment of 'Th2-high' severe asthma

Severe asthma is a heterogeneous disease characterized by reversible airway obstruction, chronic inflammation and airway remodeling. Phenotyping and/or endotyping can lead to a more personalized treatment strategy, improving the efficacy of novel drugs. Atopic asthma is associated with high levels of Th2 cells, implicated in a number of inflammatory responses. Differentiation of these cells from naive T cells occurs primarily via the JAK-STAT signaling pathway. Targeting this pathway through inhibition of activating cytokines (IL-4 and IL-13) and their receptors, the JAKs or the STATs, has been shown to have a therapeutic effect on asthma pathology. There are a number of novel drugs currently in development, which target various pathway components; these include both biologics and small molecules at various stages of development.

Protein disulfide isomerase-endoplasmic reticulum resident protein 57 regulates allergen-induced airways inflammation, fibrosis, and hyperresponsiveness

BACKGROUND

Evidence for association between asthma and the unfolded protein response is emerging. Endoplasmic reticulum resident protein 57 (ERp57) is an endoplasmic reticulum-localized redox chaperone involved in folding and secretion of glycoproteins. We have previously demonstrated that ERp57 is upregulated in allergen-challenged human and murine lung epithelial cells. However, the role of ERp57 in asthma pathophysiology is unknown.

OBJECTIVES

Here we sought to examine the contribution of airway epithelium-specific ERp57 in the pathogenesis of allergic asthma.

METHODS

We examined the expression of ERp57 in human asthmatic airway epithelium and used murine models of allergic asthma to evaluate the relevance of epithelium-specific ERp57.

RESULTS

Lung biopsy specimens from asthmatic and nonasthmatic patients revealed a predominant increase in ERp57 levels in epithelium of asthmatic patients. Deletion of ERp57 resulted in a significant decrease in inflammatory cell counts and airways resistance in a murine model of allergic asthma. Furthermore, we observed that disulfide bridges in eotaxin, epidermal growth factor, and periostin were also decreased in the lungs of house dust mite-challenged ERp57-deleted mice. Fibrotic markers, such as collagen and α smooth muscle actin, were also significantly decreased in the lungs of ERp57-deleted mice. Furthermore, adaptive immune responses were dispensable for house dust mite-induced endoplasmic reticulum stress and airways fibrosis.

CONCLUSIONS

Here we show that ERp57 levels are increased in the airway epithelium of asthmatic patients and in mice with allergic airways disease. The ERp57 level increase is associated with redox modification of proinflammatory, apoptotic, and fibrotic mediators and contributes to airways hyperresponsiveness. The strategies to inhibit ERp57 specifically within the airways epithelium might provide an opportunity to alleviate the allergic asthma phenotype.

Challenges and Current Efforts in the Development of Biomarkers for Chronic Inflammatory and Remodeling Conditions of the Lungs

This review discusses biomarkers that are being researched for their usefulness to phenotype chronic inflammatory lung diseases that cause remodeling of the lung's architecture. The review focuses on asthma, chronic obstructive pulmonary disease (COPD), and pulmonary hypertension. Bio-markers of environmental exposure and specific classes of biomarkers (noncoding RNA, metabolism, vitamin, coagulation, and microbiome related) are also discussed. Examples of biomarkers that are in clinical use, biomarkers that are under development, and biomarkers that are still in the research phase are discussed. We chose to present examples of the research in biomarker development by diseases, because asthma, COPD, and pulmonary hypertension are distinct entities, although they clearly share processes of inflammation and remodeling.

Matricellular proteins in drug delivery: Therapeutic targets, active agents, and therapeutic localization

Extracellular matrix is composed of a complex array of molecules that together provide structural and functional support to cells. These properties are mainly mediated by the activity of collagenous and elastic fibers, proteoglycans, and proteins such as fibronectin and laminin. ECM composition is tissue-specific and could include matricellular proteins whose primary role is to modulate cell-matrix interactions. In adults, matricellular proteins are primarily expressed during injury, inflammation and disease. Particularly, they are closely associated with the progression and prognosis of cardiovascular and fibrotic diseases, and cancer. This review aims to provide an overview of the potential use of matricellular proteins in drug delivery including the generation of therapeutic agents based on the properties and structures of these proteins as well as their utility as biomarkers for specific diseases.

Asthma phenotyping: a necessity for improved therapeutic precision and new targeted therapies

Asthma is a common heterogeneous disease with a complex pathophysiology that carries a significant mortality rate and high morbidity. Current therapies based on inhaled corticosteroids and long-acting β-agonists remain effective in a large proportion of patients with asthma, but ~10% (considered to have 'severe asthma') do not respond to these treatments even at high doses or with the use of oral corticosteroids. Analytical clustering methods have revealed phenotypes that include dependence on high-dose corticosteroid treatment, severe airflow obstruction and recurrent exacerbations associated with an allergic background and late onset of disease. One severe phenotype is eosinophilic inflammation-predominant asthma, with late-onset disease, rhinosinusitis, aspirin sensitivity and exacerbations. Blood and sputum eosinophilia have been used to distinguish patients with high Th2 inflammation and to predict therapeutic response to treatments targeted towards Th2-associated cytokines. New therapies in the form of humanized antibodies against Th2 targets, such as anti-IgE, anti-IL4Rα, anti-IL-5 and anti-IL-13 antibodies, have shown encouraging results in terms of reduction in exacerbations and improvement in airflow in patients with a 'Th2-high' expression profile and blood eosinophilia. Research efforts are now focusing on elucidating the phenotypes underlying the non-Th2-high (or Th2-low) group, which constitutes ~50% of severe asthma cases. There is an increasing need to use biomarkers to indicate the group of patients who will respond to a specifically targeted treatment. The use of improved tools to measure activity of disease, a better definition of severe asthma and the delineation of inflammatory pathways with omics analyses using computational tools, will lead to better-defined phenotypes for specific therapies.

Periostin - A Novel Systemic Biomarker for Eosinophilic Airway Inflammation: A Case Control Study

INTRODUCTION

Chronic airway inflammation and remodelling are fundamental features of asthma. The molecular phenotypes in asthma are Th2 high and Th2 low. Serum periostin is a biomarker which aid in understanding Th2 high eosinophilic asthma.

AIM

The present study aimed to identify whether or not serum periostin is a systemic biomarker for eosinophilic airway inflammation in asthmatics.

MATERIALS AND METHODS

The study was designed as a prospective, case control study. Patients who presented with consistent symptoms of asthma and confirmed by spirometry with reversibility were the cases. The controls were healthy subjects who had no history of lung disease with normal lung function. The sputum and blood samples were collected from both the groups. Sputum eosinophils, Absolute Eosinophil Counts (AEC) and serum periostin levels were compared between the groups.

RESULTS

The study comprised of 101 participants in which 30 were controls and 71 were cases. In the study group, mean post FEV1 was 64.45. There was a positive correlation of sputum eosinophils with severity of obstruction. The ROC curve analysis showed the cut-off value of 24.556 for serum periostin with the p-value of <0.001. As the severity of obstruction increased, the serum periostin levels were also found to be increased. Serum periostin had a sensitivity and specificity of 97.18% and 86.67% with a diagnostic accuracy of 94.06%.

CONCLUSION

Serum periostin appears to be a more sensitive tool for detection of airflow limitation in asthmatic patients with a Th2 high eosinophilic phenotype when compared to AEC and sputum eosinophils.

Eosinophilic airway inflammation: role in asthma and chronic obstructive pulmonary disease

The chronic lung diseases, asthma and chronic obstructive pulmonary disease (COPD), are common affecting over 500 million people worldwide and causing substantial morbidity and mortality. Asthma is typically associated with Th2-mediated eosinophilic airway inflammation, in contrast to neutrophilic inflammation observed commonly in COPD. However, there is increasing evidence that the eosinophil might play an important role in 10-40% of patients with COPD. Consistently in both asthma and COPD a sputum eosinophilia is associated with a good response to corticosteroid therapy and tailored strategies aimed to normalize sputum eosinophils reduce exacerbation frequency and severity. Advances in our understanding of the multistep paradigm of eosinophil recruitment to the airway, and the consequence of eosinophilic inflammation, has led to the development of new therapies to target these molecular pathways. In this article we discuss the mechanisms of eosinophilic trafficking, the tools to assess eosinophilic airway inflammation in asthma and COPD during stable disease and exacerbations and review current and novel anti-eosinophilic treatments.

Biomarkers in the clinical development of asthma therapies

Here we review how biomarkers have been used in the design, execution and interpretation of recent clinical studies of therapeutic candidates targeting cytokine-mediated inflammatory pathways in asthma. This review focuses on type 2 inflammation, as there are multiple therapeutics and/or clinical studies that can be compared within that specific pathway. Comparative analyses of data from these clinical studies illustrate the utility of biomarkers to quantify pharmacodynamic effects, clarify mechanism of action and stratify patients, which may facilitate the interpretation of outcomes in the development of molecularly targeted therapies. These case examples provide a basis for biomarker considerations in the design of future studies in the asthma setting.

Implications of the inflammatory response for the identification of biomarkers of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by both local and systemic inflammation. Because inflammation plays a critical role in the development, course and severity of COPD, inflammatory markers have the potential to improve the current diagnostic and prognostic approaches. Local inflammation in COPD is characterized by an infiltration of inflammatory cells, with an increased expression of cytokines, chemokines, enzymes, growth factors and adhesion molecules. Systemic low-grade inflammation is another common but nonspecific finding in COPD. Exacerbations of COPD are acute clinical events accompanied by an exaggerated inflammatory response. Future investigations in the field of COPD biomarkers should take into account different study designs and biochemical assays, disease course and duration, variations in symptom severity and timing of measurement.

Higher serum levels of periostin and the risk of exacerbations in moderate asthmatics

BACKGROUND

In asthma, exacerbations and poor disease control are linked to airway allergic inflammation. Serum periostin has been proposed as a systemic biomarker of eosinophilic inflammation. This pilot study aims at evaluating whether in patients with moderate asthma, higher baseline levels of serum periostin are associated with a greater risk of exacerbation.

METHODS

Fifteen outpatients with moderate allergic asthma were recruited. Serum concentrations of periostin were assessed (ELISA) at baseline, and the frequency of asthma exacerbations was recorded during a one-year follow-up.

RESULTS

Patients (M/F: 10/5, mean age of 47.6 ± 11.0 years) had mean ACQ score of 5.5 ± 4.2 and FEV₁%pred of 81.9 ± 21.7 %. Baseline serum levels of periostin did not correlate with lung function parameters, nor with the ACQ score (p ≥0.05 for all analyses). Five subjects (33 % of the study group) reported one or more exacerbations during the following year. Baseline serum levels of periostin were significantly higher in subjects who experienced one or more exacerbations during the one year period of follow-up, compared with subjects with no exacerbations: median serum periostin level was 4047 ng/ml (range: 2231 to 4889 ng/ml) and 222 ng/ml (range 28.2 to 1631 ng/ml) respectively; p = 0.001.

CONCLUSION

The findings of the present pilot study could form the basis for the design of larger studies aiming at developing strategies to identify asthmatic patients at risk for exacerbations.

Recent advances in understanding the roles of vascular endothelial cells in allergic inflammation

Allergic disorders commonly involve both chronic tissue inflammation and remodeling caused by immunological reactions to various antigens on tissue surfaces. Due to their anatomical location, vascular endothelial cells are the final responders to interact with various exogenous factors that come into contact with the epithelial surface, such as pathogen-associated molecular patterns (PAMPs) and antigens. Recent studies have shed light on the important roles of endothelial cells in the development and exacerbation of allergic disorders. For instance, endothelial cells have the greatest potential to produce several key molecules that are deeply involved in allergic inflammation, such as periostin and thymus and activation-regulated chemokine (TARC/CCL17). Additionally, endothelial cells were recently shown to be important functional targets for IL-33--an essential regulator of allergic inflammation. Notably, almost all endothelial cell responses and functions involved in allergic inflammation are not suppressed by corticosteroids. These corticosteroid-refractory endothelial cell responses and functions include TNF-α-associated angiogenesis, leukocyte adhesion, IL-33-mediated responses and periostin and TARC production. Therefore, these unique responses and functions of endothelial cells may be critically involved in the pathogenesis of various allergic disorders, especially their refractory processes. Here, we review recent studies, including ours, which have elucidated previously unknown pathophysiological roles of vascular endothelial cells in allergic inflammation and discuss the possibility of endothelium-targeted therapy for allergic disorders.

Targeted anti-inflammatory therapeutics in asthma and chronic obstructive lung disease

Asthma and chronic obstructive pulmonary disease (COPD) are chronic inflammatory diseases of the airway, although the drivers and site of the inflammation differ between diseases. Asthmatics with a neutrophilic airway inflammation are associated with a poor response to corticosteroids, whereas asthmatics with eosinophilic inflammation respond better to corticosteroids. Biologicals targeting the Th2-eosinophil nexus such as anti-interleukin (IL)-4, anti-IL-5, and anti-IL-13 are ineffective in asthma as a whole but are more effective if patients are selected using cellular (eg, eosinophils) or molecular (eg, periostin) biomarkers. This highlights the key role of individual inflammatory mediators in driving the inflammatory response and for accurate disease phenotyping to allow greater understanding of disease and development of patient-oriented antiasthma therapies. In contrast to asthmatic patients, corticosteroids are relatively ineffective in COPD patients. Despite stratification of COPD patients, the results of targeted therapy have proved disappointing with the exception of recent studies using CXC chemokine receptor (CXCR)2 antagonists. Currently, several other novel mediator-targeted drugs are undergoing clinical trials. As with asthma specifically targeted treatments may be of most benefit in specific COPD patient endotypes. The use of novel inflammatory mediator-targeted therapeutic agents in selected patients with asthma or COPD and the detection of markers of responsiveness or nonresponsiveness will allow a link between clinical phenotypes and pathophysiological mechanisms to be delineated reaching the goal of endotyping patients.

Association of blood eosinophils and plasma periostin with FEV1 response after 3-month inhaled corticosteroid and long-acting beta2-agonist treatment in stable COPD patients

BACKGROUND

COPD patients with increased airway eosinophilic inflammation show a favorable response to inhaled corticosteroids (ICS) in combination with a long-acting bronchodilator. Recent studies have demonstrated a significant correlation of sputum eosinophilia with blood eosinophils and periostin. We investigated whether high blood eosinophils and plasma periostin were associated with an improvement in forced expiratory volume in 1 second (FEV1) after 3-month treatment with ICS/long-acting beta2-agonist (LABA) in stable COPD patients.

PATIENTS AND METHODS

Blood eosinophils and plasma periostin levels were measured in 130 stable COPD subjects selected from the Korean Obstructive Lung Disease cohort. Subjects began a 3-month ICS/LABA treatment after washout period.

RESULTS

High blood eosinophils (>260/µL, adjusted odds ratio =3.52, P=0.009) and high plasma periostin (>23 ng/mL, adjusted odds ratio =3.52, P=0.013) were significantly associated with FEV1 responders (>12% and 200 mL increase in FEV1 from baseline after treatment). Moreover, the addition of high blood eosinophils to age, baseline positive bronchodilator response, and FEV1 <50% of the predicted value significantly increased the area under the curve for prediction of FEV1 responders (from 0.700 to 0.771; P=0.045).

CONCLUSION

High blood eosinophils and high plasma periostin were associated with improved lung function after 3-month ICS/LABA treatment. In particular, high blood eosinophils, in combination with age and baseline lung function parameters, might be a possible biomarker for identification of COPD patients with favorable FEV1 improvement in response to ICS/LABA treatment.

Evolving Concepts of Asthma

Our understanding of asthma has evolved over time from a singular disease to a complex of various phenotypes, with varied natural histories, physiologies, and responses to treatment. Early therapies treated most patients with asthma similarly, with bronchodilators and corticosteroids, but these therapies had varying degrees of success. Similarly, despite initial studies that identified an underlying type 2 inflammation in the airways of patients with asthma, biologic therapies targeted toward these type 2 pathways were unsuccessful in all patients. These observations led to increased interest in phenotyping asthma. Clinical approaches, both biased and later unbiased/statistical approaches to large asthma patient cohorts, identified a variety of patient characteristics, but they also consistently identified the importance of age of onset of disease and the presence of eosinophils in determining clinically relevant phenotypes. These paralleled molecular approaches to phenotyping that developed an understanding that not all patients share a type 2 inflammatory pattern. Using biomarkers to select patients with type 2 inflammation, repeated trials of biologics directed toward type 2 cytokine pathways saw newfound success, confirming the importance of phenotyping in asthma. Further research is needed to clarify additional clinical and molecular phenotypes, validate predictive biomarkers, and identify new areas for possible interventions.

Predicting asthma morbidity in children using proposed markers of Th2-type inflammation

BACKGROUND

Assessment of inflammation is becoming a common practice in the clinical work-up of children with persistent asthma. Biomarkers of Th2-mediated inflammation include blood eosinophils (B-Eos), exhaled nitric oxide (FeNO), total serum IgE (S-IgE), and serum periostin. The aim of this study was to investigate the associations between asthma morbidity and increased levels of these biomarkers in pediatric asthma.

METHODS

School-age children (n = 96) with various manifestations of persistent asthma were included in this nationwide Swedish study. The protocol included the asthma control test, Juniper's quality of life questionnaire (QoL), assessment of pulmonary function, bronchial hyperresponsiveness, height-adjusted FeNO, blood sampling for S-IgE, B-Eos, and periostin, and high-resolution computed tomography (HRCT) of the lungs.

RESULTS

Children with both high levels of height-adjusted FeNO and B-Eos were younger (p = 0.001), had more often severe asthma (p = 0.015), were more allergic (p < 0.001), had a reduced asthma control (p = 0.035), reduced QoL (p = 0.035), more exacerbations (p = 0.004), reduced FEV1/FVC (p = 0.001), and increased bronchial hyperresponsiveness (p < 0.001) as well as greater bronchial wall thickening on HRCT (p = 0.022) compared to those with low levels of both biomarkers. Grouping children according to high and low serum periostin levels did not relate to differences in clinical characteristics and biomarkers.

CONCLUSIONS

Assessment of both local and systemic Th2-mediated inflammation by the analysis of easily attainable biomarkers such as exhaled NO and blood eosinophils has a high predictive value for the identification of children with the highest asthma morbidity. Adjusting FeNO values according to the individual child's height increases the clinical usefulness of this biomarker.

Inhibition of the kinase ITK in a mouse model of asthma reduces cell death and fails to inhibit the inflammatory response

Interleukin-2 (IL-2)-inducible T cell kinase (ITK) mediates T cell receptor (TCR) signaling primarily to stimulate the production of cytokines, such as IL-4, IL-5, and IL-13, from T helper 2 (TH2) cells. Compared to wild-type mice, ITK knockout mice are resistant to asthma and exhibit reduced lung inflammation and decreased amounts of TH2-type cytokines in the bronchoalveolar lavage fluid. We found that a small-molecule selective inhibitor of ITK blocked TCR-mediated signaling in cultured TH2 cells, including the tyrosine phosphorylation of phospholipase C-γ1 (PLC-γ1) and the secretion of IL-2 and TH2-type cytokines. Unexpectedly, inhibition of the kinase activity of ITK during or after antigen rechallenge in an ovalbumin-induced mouse model of asthma failed to reduce airway hyperresponsiveness and inflammation. Rather, in mice, pharmacological inhibition of ITK resulted in T cell hyperplasia and the increased production of TH2-type cytokines. Thus, our studies predict that inhibition of the kinase activity of ITK may not be therapeutic in patients with asthma.

Effect of treatment with inhaled corticosteroid on serum periostin levels in asthma

BACKGROUND AND OBJECTIVE

Periostin is a biomarker of eosinophilic airway inflammation and may contribute to airway remodeling in asthma. The anti-inflammatory activity of inhaled corticosteroids (ICS) for asthma control is widely recognized. The aim of this study was to assess the effects of ICS on serum periostin levels and its relationships to inflammation and airway geometry.

METHODS

Forty-two healthy controls and 20 patients with steroid-naïve asthma before and after treatment with fluticasone propionate (800 μg/day for 16 weeks) were examined. Serum periostin, lung function and inflammatory cell counts in sputum were measured. Airway dimensions were determined by quantitative computed tomography (total area of the airway (Ao), wall area (WA), wall thickness (T) and percentage wall area (WA%) ).

RESULTS

Serum periostin concentrations were significantly higher in patients with asthma than in controls. Periostin levels were correlated with airway wall thickness and sputum eosinophilia and inversely correlated with airflow limitation in asthma. ICS significantly decreased serum periostin (P < 0.01), decreased WA corrected for body surface area (WA/BSA, P < 0.05), T/√BSA (P < 0.01) and WA% (P < 0.01), reduced the percentage of sputum eosinophils (P < 0.01) and improved airflow limitation. The decrease in serum periostin levels was associated with an increased per cent predicted forced expiratory volume in 1 s (r = -0.64, P < 0.01), decreased WA/BSA (r = 0.46, P < 0.05) and decreased sputum eosinophils (r = 0.71, P < 0.01).

CONCLUSION

Serum periostin levels respond partially to ICS and may reflect a reduction in airway inflammation and wall thickening in asthma.

Aberrant expression of regulatory cytokine IL-35 and pattern recognition receptor NOD2 in patients with allergic asthma

We investigated the plasma concentration of the novel regulatory cytokine IL-35 and intracytosolic pattern recognition receptors nucleotide-binding oligomerization domain (NOD)-like receptors in granulocytes and explored their potential implication in disease severity monitoring of allergic asthma. The expression of circulating IL-35 and other pro-inflammatory mediators in asthmatic patients or control subjects were evaluated using enzyme-linked immunosorbent assay (ELISA). The intracellular expressions of NOD1 and NOD2 in CCR3+ granulocytes were assessed using flow cytometry. Plasma concentrations of IL-35, IL-17A, basophil activation marker basogranulin, and eosinophilic airway inflammation biomarker periostin were significantly elevated in allergic asthmatic patients compared to non-atopic control subjects (all probability (p) <0.05). Both granulocyte markers exhibited significant and positive correlation with plasma IL-35 concentration in asthmatic patients (all p < 0.05). Significant positive correlation was also identified between plasma concentrations of IL-35 and periostin with disease severity score in asthmatic patients (both p < 0.05). The basophil activation allergenicity test was positive in allergic asthmatic patients but not in control subjects. Despite significantly elevated eosinophil count in allergic asthmatic patients, downregulation of NOD2 in CCR3+ granulocytes was observed in these patients (both p < 0.05). A negative correlation between plasma concentrations of tumor necrosis factor family member LIGHT and soluble herpesvirus entry mediator was observed in patients with elevated plasma concentration of IL-35 (p < 0.05). Aberrant expression of NOD2 in granulocytes may be contributed to the impaired innate immunity predisposing allergic asthma. IL-35 may serve as a potential surrogate biomarker for disease severity of allergic asthma.

Molecular phenotyping and biomarker development: are we on our way towards targeted therapy for severe asthma?

Although different phenotypes of severe asthma can be identified, all are characterized by common symptoms. Due to their heterogeneity, they exhibit differences in pathogenesis, etiology and clinical responses to therapeutic approaches. The identification of distinct molecular phenotypes to define severe asthmatic patients will allow us to better understand the pathophysiology of the disease and thus to more precisely target the treatment for each patient. To achieve this goal, a systematic search for new, reliable and stable biomarkers specific for each phenotype is essential. This review focuses on the current known molecular phenotypes of severe asthma and highlights the need for biomarkers that could (either alone or in combination) be predictive of the treatment outcome.

H2S Synthesizing Enzymes: Biochemistry and Molecular Aspects

Hydrogen sulfide (H2S) is a biologically active gas that is synthesized naturally by three enzymes, cystathionine γ-lyase (CSE), cystathionine β-synthetase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). These enzymes are constitutively present in a wide array of biological cells and tissues and their expression can be induced by a number of disease states. It is becoming increasingly clear that H2S is an important mediator of a wide range of cell functions in health and in disease. This review therefore provides an overview of the biochemical and molecular regulation of H2S synthesizing enzymes both in physiological conditions and their modulation in disease states with particular focus on their regulation in asthma, atherosclerosis and diabetes. The importance of small molecule inhibitors in the study of molecular pathways, the current use of common H2S synthesizing enzyme inhibitors and the relevant characteristics of mice in which these enzymes have been genetically deleted will also be summarized. With a greater understanding of the molecular regulation of these enzymes in disease states, as well as the availability of novel small molecules with high specificity targeted towards H2S producing enzymes, the potential to regulate the biological functions of this intriguing gas H2S for therapeutic effect can perhaps be brought one step closer.

The past, present, and future of monoclonal antibodies to IL-5 and eosinophilic asthma: a review

Asthma is a heterogeneous syndrome that might be better described as a constellation of phenotypes or endotypes, each with distinct cellular and molecular mechanisms, rather than as a singular disease. One of these phenotypes is eosinophilic asthma. As the development of eosinophilic inflammation is categorically dependent on the biological activity of Interleukin (IL)-5, IL-5 antagonism became an obvious target for therapy in this phenotype. Early trials of monoclonal antibodies targeting the biological activity of IL-5, including reslizumab, mepolizumab, and benralizumab, were performed on asthmatics with no concern for evidence of eosinophilia. These trials were largely unsuccessful. However, during these trials, researchers recognized the need to quantify eosinophilia in asthma subjects in order to identify those asthmatics in whom these medications would be more likely to improve symptoms and lung function. Using biomarkers, such as sputum and blood eosinophilia, recent studies of these medications have shown improvements in blood and sputum eosinophilia, forced expiratory volume in 1 second, and quality of life assessments as well as reducing occurrences of exacerbations. Moving forward, better and less invasive biomarkers of eosinophilia are necessary to ensure that the correct patients are chosen to receive these medications to receive maximal benefit.

The Complex Type 2 Endotype in Allergy and Asthma: From Laboratory to Bedside

Better management of allergic diseases needs a sharpened understanding of disease heterogeneity and mechanisms in relation to clinically significant outcomes. Phenotypes describing observable clinical and morphologic characteristics and unique responses to treatment have been developed; however, they do not relate to disease mechanisms. Recently, extended heterogeneous and disease-related metabolic, inflammatory, immunological, and remodeling pathways have been described, and reproducible patterns are defined as disease endotypes. An endotype might consist of several intricated mechanisms that cannot be clearly separated into "pure single molecular mechanism" thus being a "complex endotype." The description of an endotype may rely on biomarkers, which can be the signature of a complex underlying pathway or a key molecule associated with or directly playing a role in a particular disease endotype. The Th2 type inflammation can be defined as a complex endotype in asthma and linked to mechanisms of disease development and response to treatment and to disease outcomes such as exacerbations and remodeling. The type 2 complex endotype in allergies and asthma includes innate lymphoid cells, T helper 2 cells, tissue eosinophilia, and IgE production. Currently, emerging endotype-driven strategies in asthma, particularly the development of biologicals that target a single molecular pathway, are being focused for solving individualized clinical problems on disease outcomes. Progress is also being made for endotyping rhinitis, chronic rhinosinusitis, and atopic dermatitis.

Type 2 innate lymphoid cells: A novel biomarker of eosinophilic airway inflammation in patients with mild to moderate asthma

BACKGROUND

Eosinophilic airway inflammation can predict the exacerbation of asthma, and we can improve the management of asthma by monitoring the eosinophilic airway inflammation. Although induced sputum and sputum eosinophil count is the gold standard test for diagnosing eosinophilic asthma, a more accessible and receptive method is needed for clinical practice. Type 2 innate lymphoid cells (ILC2) have recently been proposed to play a crucial role in eosinophilic inflammation and have been identified in peripheral blood from patients with asthma.

OBJECTIVES

We sought to identify simple and feasible biomarkers which can predict eosinophilic airway inflammation in asthmatic patients.

METHODS

Sputum was induced for the assessment of eosinophils in 150 asthmatic patients. In parallel, the proportion of ILC2s of peripheral blood lymphocytes (%ILC2), blood eosinophil counts, total immunoglobulin E (IgE), fractional exhaled nitric oxide (FeNO) and lung function tests were measured. 42 healthy donors served as controls.

RESULTS

126 patients finished sputum induction and produced adequate sputum. The ILC2 level was significantly increased in eosinophilic asthmatic patients compared with non-eosinophilic asthmatic patients (0.117 ± 0.090versus0.035 ± 0.021, p < 0.001). A multiple regression model, including age, sex, BMI, blood eosinophil counts, FeNO, IgE and %ILC2, showed that %ILC2, blood eosinophil counts and FeNO were correlative factors of sputum eosinophil counts (p < 0.001, p = 0.037, p < 0.001, respectively) and %ILC2 was the most significant subset of airway eosinophilic inflammation (Estimate = 11.385). A receiver operating characteristic (ROC) analysis showed a sensitivity of 67.7% and a specificity of 95.3% for %ILC2 of 0.076 to distinguish eosinophilic asthmatic patients from non-eosinophilic asthmatic patients.

CONCLUSION

ILC2 is a surrogate marker of airway eosinophilic inflammation in patients with mild to moderate asthma and has great potential advantages for selecting the asthmatic patients most likely to benefit from therapeutics targeting Th2 inflammation.

Drug therapies in severe asthma - the era of stratified medicine

Difficult-to-treat asthma affects up to 20% of patients with asthma and is associated with significant healthcare cost. It is an umbrella term that defines a heterogeneous clinical problem including incorrect diagnosis, comorbid conditions and treatment non-adherence; when these are effectively addressed, good symptom control is frequently achieved. However, in 3-5% of adults with difficult-to-treat asthma, the problem is severe disease that is unresponsive to currently available treatments. Current treatment guidelines advise the 'stepwise' increase of corticosteroids, but it is now recognised that many aspects of asthma are not corticosteroid responsive, and that this 'one size fits all' approach does not deliver clinical benefit in many patients and can also lead to side effects. The future of management of severe asthma will involve optimisation with currently available treatments, particularly corticosteroids, including addressing non-adherence and defining an 'optimised' corticosteroid dose, allied with the use of 'add-on' target-specific novel treatments. This review examines the current status of novel treatments and research efforts to identify novel targets in the era of stratified medicines in severe asthma.

Biomarkers and severe asthma: a critical appraisal

Severe asthma (SA) is a clinically and etiologically heterogeneous respiratory disease which affects among 5–10 % of asthmatic patients. Despite high-dose therapy, a large patients percentage is not fully controlled and has a poor quality of life. In this review, we describe the biomarkers actually known in scientific literature and used in clinical practice for SA assessment and management: neutrophils, eosinophils, periostin, fractional exhaled nitric oxide, exhaled breath condensate and galectins. Moreover, we give an overview on clinical and biological features characterizing severe asthma, paying special attention to the potential use of these ones as reliable markers. We finally underline the need to define different biomarkers panels to select patients affected by severe asthma for specific and personalized therapeutic approach.

Peripheral blood IRF1 expression as a marker for glucocorticoid sensitivity

OBJECTIVE

Despite of the common usage of glucocorticoids (GCs), a significant portion of asthma patients exhibit GC insensitivity. This could be mediated by diverse mechanisms, including genomics. Recent work has suggested that measuring changes in gene expression may provide more predictive information about GC insensitivity than baseline gene expression alone, and that expression changes in peripheral blood may be reflective of those in the airway.

METHODS

We performed in silico discovery using gene expression omnibus (GEO) data that evaluated GC effect on gene expression in multiple tissue types. Subsequently, candidate genes whose expression levels are affected by GC were examined in cell lines and in primary cells derived from human airway and blood.

RESULTS

Through gene expression omnibus analysis, we identified interferon regulator factor 1 (IRF1), whose expression is affected by GC treatment in airway smooth muscle cells, normal human bronchial epithelial (NHBE) cells, and lymphoblastoid cell lines (LCLs). Significant IRF1 downregulation post GC exposure was confirmed in two cultured airway epithelial cell lines and primary NHBE cells (P<0.05). We observed large interindividual variation in GC-induced IRF1 expression changes among primary NHBE cells tested. Significant downregulation of IRF1 was also observed in six randomly selected LCLs (P<0.05), with variable degrees of downregulation among different samples. In peripheral blood mononuclear cells obtained from healthy volunteers, variable downregulation of IRF1 by GC was also shown. NFKB1, a gene whose expression is known to be downregulated by GC and the degree of downregulation of which is reflective of GC response, was used as a control in our study. IRF1 shows more consistent downregulation across tissue types when compared with NFKB1.

CONCLUSION

Our results suggest that GC-induced IRF1 gene expression changes in peripheral blood could be used as a marker to reflect GC response in the airway.

Biomarkers in Pharmaceutical Research

BACKGROUND

Biomarkers are important tools in drug development and are used throughout pharmaceutical research.

CONTENT

This review focuses on molecular biomarkers in drug development. It contains sections on how biomarkers are used to assess target engagement, pharmacodynamics, safety, and proof-of-concept. It also covers the use of biomarkers as surrogate end points and patient selection/companion diagnostics and provides insights into clinical biomarker discovery and biomarker development/validation with regulatory implications. To survey biomarkers used in drug development--acknowledging that many pharmaceutical development biomarkers are not published--we performed a focused PubMed search employing "biomarker" and the names of the largest pharmaceutical companies as keywords and filtering on clinical trials and publications in the last 10 years. This yielded almost 500 entries, the majority of which included disease-related (approximately 60%) or prognostic/predictive (approximately 20%) biomarkers. A notable portion (approximately 8%) included HER2 (human epidermal growth factor receptor 2) testing, highlighting the utility of biomarkers for patient selection. The remaining publications included target engagement, safety, and drug metabolism biomarkers. Oncology, cardiovascular disease, and osteoporosis were the areas with the most citations, followed by diabetes and Alzheimer disease.

SUMMARY

Judicious biomarker use can improve pharmaceutical development efficiency by helping to select patients most appropriate for treatment using a given mechanism, optimize dose selection, and provide earlier confidence in accelerating or discontinuing compounds in clinical development. Optimal application of biomarker technology requires understanding of candidate drug pharmacology, detailed modeling of biomarker readouts relative to pharmacokinetics, rigorous validation and qualification of biomarker assays, and creative application of these elements to drug development problems.

Targeting the interleukin pathway in the treatment of asthma

Asthma is a common heterogeneous disease with a complex pathophysiology. Current therapies based on inhaled corticosteroids and longacting β2 agonists are effective in controlling asthma in most, but not all patients, with a few patients falling into the severe asthma category. Severe asthma is characterised by poor asthma control, recurrent exacerbations, and chronic airflow obstruction despite adequate and, in many cases, high-dose treatments. There is strong evidence supporting the role for interleukins derived from T-helper-2 (Th2) cells and innate lymphoid cells, such as interleukins 4, 5, and 13, as underlying the eosinophilic and allergic inflammatory processes in nearly half of these patients. An anti-IgE antibody, omalizumab, which binds to circulating IgE, a product of B cells from the actions of interleukin 4 and interleukin 13, is used as treatment for severe allergic asthma. Studies examining cytokine blockers such as anti-interleukin-5, anti-interleukin-4Rα, and anti-interleukin-13 monoclonal antibodies in patients with severe asthma with recurrent exacerbations and high blood eosinophil counts despite use of inhaled corticosteroids have reported improved outcomes in terms of exacerbations, asthma control, and forced expiratory volume in 1 s. The US Food and Drug Administration's recommendation to use an anti-interleukin-5 antibody for the treatment of severe eosinophilic asthma suggests that there will be a therapeutic place for these anti-Th2 agents. Biomarkers should be used to identify the right patients for such targeted approaches. More guidance will be needed as to which patients should receive each of these classes of selective antibody-based treatments. Currently, there is no treatment that targets the cytokines driving asthma associated with non-eosinophilic inflammation and low Th2 expression.

Asthma

Asthma is the most common inflammatory disease of the lungs. The prevalence of asthma is increasing in many parts of the world that have adopted aspects of the Western lifestyle, and the disease poses a substantial global health and economic burden. Asthma involves both the large-conducting and the small-conducting airways, and is characterized by a combination of inflammation and structural remodelling that might begin in utero. Disease progression occurs in the context of a developmental background in which the postnatal acquisition of asthma is strongly linked with allergic sensitization. Most asthma cases follow a variable course, involving viral-induced wheezing and allergen sensitization, that is associated with various underlying mechanisms (or endotypes) that can differ between individuals. Each set of endotypes, in turn, produces specific asthma characteristics that evolve across the lifecourse of the patient. Strong genetic and environmental drivers of asthma interconnect through novel epigenetic mechanisms that operate prenatally and throughout childhood. Asthma can spontaneously remit or begin de novo in adulthood, and the factors that lead to the emergence and regression of asthma, irrespective of age, are poorly understood. Nonetheless, there is mounting evidence that supports a primary role for structural changes in the airways with asthma acquisition, on which altered innate immune mechanisms and microbiota interactions are superimposed. On the basis of the identification of new causative pathways, the subphenotyping of asthma across the lifecourse of patients is paving the way for more-personalized and precise pathway-specific approaches for the prevention and treatment of asthma, creating the real possibility of total prevention and cure for this chronic inflammatory disease.

Clinical phenotypes of asthma should link up with disease mechanisms

PURPOSE OF REVIEW

Asthma is a common disease which presents in various clinical forms and levels of severity. The current 'one size fits all' approach to treatment is suboptimal. Using unbiased cluster analysis has identified several asthma phenotypes. Understanding the underlying mechanisms driving these clusters may lead to better patient-orientated medicines.

RECENT FINDINGS

Clustering was initially performed on clinical features only, but the addition of biomarkers that characterize sputum and blood cellular profiles has enabled the prediction of responses to targeted therapies. Clusters of severe asthma include those on high-dose corticosteroid treatment associated with severe airflow obstruction and those with discordance between symptoms and sputum eosinophilia. Sputum eosinophilia can predict therapeutic responses to T-helper type 2 cytokine blockade. Further molecular phenotyping or endotyping of asthma will be necessary to determine new treatment strategies. Low T-helper type 2 expression may be predictive of poor therapeutic response to inhaled corticosteroids, but much less is known about this type of asthma.

SUMMARY

Phenotype-driven treatment of asthma will be further boosted by the integration of genetic, transcriptomic and proteomic technologies to defining distinct severe asthma phenotypes and biomarkers of therapeutic responses. This will lead towards stratified medicine for asthma.

Recent developments regarding periostin in bronchial asthma

Although it is currently recognized that bronchial asthma is not a single disease but a syndrome, we have not yet made use of our new understanding of this heterogeneity as we treat asthma patients. To increase the efficacy of anti-asthma drugs and to decrease costs, it is important to stratify asthma patients into subgroups and to develop therapeutic strategies for each subgroup. Periostin has recently emerged as a biomarker for bronchial asthma, unique in that it is useful not in diagnosis but in categorizing asthma patients. We first found that periostin is a novel component of subepithelial fibrosis in bronchial asthma downstream of IL-13 signals. Thereafter, it was shown that periostin can be a surrogate biomarker of type 2 immune responses, the basis of the notion that a detection system of serum periostin is potentially a companion diagnostic for type 2 antagonists. Furthermore, we have recently shown that serum periostin can predict resistance or hyporesponsiveness to inhaled corticosteroids, based on its contribution to tissue remodeling or fibrosis in bronchial asthma. Thus, serum periostin has two characteristics as a biomarker for bronchial asthma: it is both a surrogate biomarker of type 2 immune responses and a biomarker reflecting tissue remodeling or fibrosis. We can take advantage of these characteristics to develop stratified medicine in bronchial asthma.

Treatment of severe asthma: entering the era of targeted therapy

INTRODUCTION

It is estimated that 5 - 10% of asthma patients suffer from severe asthma. Severe asthma is associated with increased morbidity and mortality. These patients are not controlled with currently available treatments and therefore additional treatment options are needed. Asthma is a heterogeneous disease, and different asthma patient groups probably have different underlying pathophysiology. Novel therapies with, for example, monoclonal antibodies that target certain immunological pathways have become available. These novel treatments are not effective in all patients but only in certain phenotypes.

AREAS COVERED

This review covers the current evidence and novel developments in treatment with monoclonal antibodies in different asthma phenotypes. This includes monoclonal antibodies against IgE, against interleukin (IL)-5 and antibodies targeting IL-13 pathways. Although there is a certain overlap between patient groups benefiting from these treatments, a more detailed identification of responder profiles for these therapies is needed for personalized therapy.

EXPERT OPINION

In recent years, novel monoclonal antibodies have been developed, which are a promising addition to existing therapy in the treatment of severe asthma with eosinophilic inflammation and Th2-driven disease. We expect that several of the new antibodies will become available for clinical practice. In addition, it must be acknowledged that so far no effective strategies are available for patients with non-eosinophilic asthma and further research and development is necessary for this patient group.

New and future strategies to improve asthma control in children

Symptomatic asthma in childhood has lifelong effects on lung function and disease severity, emphasizing the need for improved pediatric asthma control. Control of pediatric risk and impairment domains can be achieved through increased medication adherence or new therapeutic strategies. Developing electronic monitoring device technology with reminders might be a key noninvasive resource to address poor adherence in children and adolescents in a clinical setting. In patients who have persistently poor control despite optimal medication compliance, newly emerging pharmaceuticals, including inhaled therapies and biologics, might be key to their treatment. However, barriers exist to their development in the pediatric population, and insights must be drawn from adult studies, which has its own unique limitations. Biomarkers to direct the use of such potentially expensive therapies to those patients most likely to benefit are imperative. In this review the current literature regarding strategies to improve pediatric asthma control is addressed with the goal of exploring the potential and pitfalls of strategies that might be available in the near future.

Profile of lebrikizumab and its potential in the treatment of asthma

Interleukin (IL)-13 has been associated with multiple inflammatory features of asthma. It affects multiple cellular lines in asthma and is a key mediator in airway hyperreactivity and remodeling. Periostin, an extracellular protein, has been used as a surrogate marker of IL-13 activity and has been linked to airway remodeling by inducing subepithelial fibrosis. Lebrikizumab is a humanized monoclonal antibody that targets IL-13. Studies have demonstrated promising results with lebrikizumab therapy in asthma with regard to pulmonary function and exacerbation rates, especially on those patients with surrogate markers of T helper cell type 2-driven inflammation (ie, elevated immunoglobulin E levels, eosinophil counts, periostin levels). Lebrikizumab appears to be a safe therapy, but there are ongoing studies evaluating its efficacy and safety profile. Other therapies that target IL-13 and the receptor of IL-4/IL-13 have been studied, but future studies are needed to determine their role in the treatment of asthma.

The airway microbiome in patients with severe asthma: Associations with disease features and severity

BACKGROUND

Asthma is heterogeneous, and airway dysbiosis is associated with clinical features in patients with mild-to-moderate asthma. Whether similar relationships exist among patients with severe asthma is unknown.

OBJECTIVE

We sought to evaluate relationships between the bronchial microbiome and features of severe asthma.

METHODS

Bronchial brushings from 40 participants in the Bronchoscopic Exploratory Research Study of Biomarkers in Corticosteroid-refractory Asthma (BOBCAT) study were evaluated by using 16S ribosomal RNA-based methods. Relationships to clinical and inflammatory features were analyzed among microbiome-profiled subjects. Secondarily, bacterial compositional profiles were compared between patients with severe asthma and previously studied healthy control subjects (n = 7) and patients with mild-to-moderate asthma (n = 41).

RESULTS

In patients with severe asthma, bronchial bacterial composition was associated with several disease-related features, including body mass index (P < .05, Bray-Curtis distance-based permutational multivariate analysis of variance; PERMANOVA), changes in Asthma Control Questionnaire (ACQ) scores (P < .01), sputum total leukocyte values (P = .06), and bronchial biopsy eosinophil values (per square millimeter, P = .07). Bacterial communities associated with worsening ACQ scores and sputum total leukocyte values (predominantly Proteobacteria) differed markedly from those associated with body mass index (Bacteroidetes/Firmicutes). In contrast, improving/stable ACQ scores and bronchial epithelial gene expression of FK506 binding protein (FKBP5), an indicator of steroid responsiveness, correlated with Actinobacteria. Mostly negative correlations were observed between biopsy eosinophil values and Proteobacteria. No taxa were associated with a TH2-related epithelial gene expression signature, but expression of TH17-related genes was associated with Proteobacteria. Patients with severe asthma compared with healthy control subjects or patients with mild-to-moderate asthma were significantly enriched in Actinobacteria, although the largest differences observed involved a Klebsiella genus member (7.8-fold increase in patients with severe asthma, adjusted P < .001).

CONCLUSIONS

Specific microbiota are associated with and may modulate inflammatory processes in patients with severe asthma and related phenotypes. Airway dysbiosis in patients with severe asthma appears to differ from that observed in those with milder asthma in the setting of inhaled corticosteroid use.

Heterogeneity of chronic obstructive pulmonary disease exacerbations: a two-axes classification proposal

Exacerbations of chronic obstructive pulmonary disease (COPD) are clinically relevant events with therapeutic and prognostic implications. Yet, they are heterogeneous and can need different therapeutic strategies. In this Viewpoint, we propose an admittedly crude approach to a COPD exacerbation classification that might eventually help to define the most appropriate pharmacological treatment and clinical treatment setting for these patients. Our suggestion is to combine a pathobiological axis (biomarkers) to guide treatment decisions (use of antibiotics, steroids, or both) with a clinical axis (severity score) to decide the organisational context in which to optimally treat the patient. Needless to say, this proposal needs to be researched and eventually validated, refined, or disproved, but we hope that this process will contribute to the improvement of personalised treatment for patients with COPD exacerbations.

Anti-interleukin 4 and 13 for asthma treatment in the era of endotypes

PURPOSE OF REVIEW

To summarize recent advances in IL-4 and IL-13 blockade in the treatment of asthma.

RECENT FINDINGS

Historically, anticytokine therapies have historically been unsuccessful in the treatment of asthma because of the heterogeneity of its pathogenesis. Recent advances in our understanding of asthma pathophysiology and our increased ability to phenotype patients have led to the identification of asthmatic subsets (endotypes) that are most likely to respond to anticytokine therapy. Several new biologic therapies targeting IL-13 or both IL-4 and IL-13 signaling are currently in clinical trials and both types of therapies have demonstrated therapeutic benefit.

SUMMARY

Anti-IL-4/13 therapies, guided by knowledge of an individual's underlying pathophysiology, are a promising class of therapies for treatment of asthma.