The demise of anti IL-5 for asthma, or not

Lebrikizumab in Uncontrolled Asthma: Reanalysis in a Well-Defined Type 2 Population

BACKGROUND

LAVOLTA (L)I, LII, and ACOUSTICS were randomized, placebo-controlled, Phase 3 trials of lebrikizumab, a monoclonal antibody targeting IL-13 in patients with uncontrolled asthma. Failure to demonstrate efficacy may have been related to patient selection in those trials.

OBJECTIVE

To assess the efficacy in a well-defined subpopulation of patients with elevated blood eosinophil counts and a minimum number of prior asthma exacerbations. We performed an additional analysis in a subpopulation of patients with elevated FeNO and prior exacerbations.

METHODS

Adult (LI and LII) and adolescent patients (aged 12-17 years weighing ≥40 kg, ACOUSTICS) with uncontrolled asthma received lebrikizumab (125 mg, n = 832; or 37.5 mg, n = 829) or placebo (n = 833) subcutaneously every 4 weeks. Post hoc analysis of the annualized adjusted exacerbation rate (AER) was performed in a subpopulation of patients with baseline blood eosinophils of 300 cells/μL or greater and history of one or more exacerbations. In this subpopulation, there were 227 patients in the placebo group, 222 in the lebrikizumab 37.5-mg group, and 217 in the lebrikizumab 125-mg group. We summarized safety in patients who received at least one dose of lebrikizumab using adverse events.

RESULTS

Lebrikizumab significantly reduced AER compared with placebo in adults (AER reduction: 125 mg [38%]; and 37.5 mg [41%]) and adolescents (AER reduction:125 mg [59%]; 37.5 mg [64%]) with baseline blood eosinophils of 300 cells/μL or greater and one or more exacerbations. Most adverse events were mild or moderate in severity and did not lead to treatment discontinuation.

CONCLUSION

Lebrikizumab significantly reduced asthma exacerbations in a subpopulation of patients with elevated blood eosinophils, elevated FeNO, and a history of asthma exacerbation.

Mepolizumab in chronic rhinosinusitis with nasal polyposis

Chronic rhinosinusitis with nasal polyposis (CRSwNP) is a heterogeneous upper airway disease that is prevalent globally. Recent research into the molecular basis of the disease has led to the development of biologics as a new therapeutic option for severe and recalcitrant forms of CRSwNP. Mepolizumab is a monoclonal antibody targeting IL-5, one of the signature cytokines of the type 2 immune response and which plays an important role in the pathogenesis of CRSwNP. Here we present the latest evidence behind mepolizumab, examining disease pathophysiology and pharmacology, as well as data from clinical trials, real-life studies and meta-analyses. As we welcome this promising step forward into precision medicine, we discuss practical issues and future perspectives on mepolizumab and biologics for CRSwNP.

Definition, Phenotyping of Severe Asthma, Including Cluster Analysis

Asthma is defined as severe when it is uncontrolled despite the high intensity of treatment, or that loses control when a therapeutic step down is tried.These patients, for years, have been "uniformly" treated with massive doses of inhaled and oral corticosteroids regardless of their inflammatory state.Initially, asthma was considered of genesis "exclusively allergic." Subsequently, thanks to the development of noninvasive tools and of human monoclonal antibodies targeting interleukin 5, a pathogenetic role has been given to eosinophils. Management of steroids based on sputum eosinophil counts has been suggested according to clinical phenotypes identified through cluster analysis.The algorithms obtained from the cluster analysis have proved later to be poorly predictive of the inflammatory phenotype and difficult to apply in clinical practice.In the new era of precision medicine, the greatest challenge is finding clinical or biological elements predictive of response to therapies such as biologics. Cluster analyses performed on omics data or on cohorts of patients treated with biologics are more promising in this sense.In this article, starting from the current definition of severe asthma, we review the phenotypes proposed over time to date, showing the difficulty underlying the process of "phenotyping" due to the scarcity of available biomarkers.

Regulated on Activation, Normal T cell Expressed and Secreted (RANTES) drives the resolution of allergic asthma

RANTES is implicated in allergic asthma and in T cell-dependent clearance of infection. RANTES receptor family comprises CCR1, CCR3, and CCR5, which are G-protein-coupled receptors consisting of seven transmembrane helices. Infections with respiratory viruses like Rhinovirus cause induction of RANTES production by epithelial cells. Here, we studied the role of RANTES in the peripheral blood mononuclear cells in cohorts of children with and without asthma and validated and extended this study to the airways of adults with and without asthma. We further translated these studies to a murine model of asthma induced by house dust mite allergen in wild-type RANTES and CCR5-deficient mice. Here we show an unpredicted therapeutic role of RANTES in the resolution of allergen-induced asthma by orchestrating the transition of effector GATA-3+CD4+ T cells into immune-regulatory-type T cells and inflammatory eosinophils into resident eosinophils as well as increased IL-10 production in the lung.

K2P2.1 (TREK-1) potassium channel activation protects against hyperoxia-induced lung injury

No targeted therapies exist to counteract Hyperoxia (HO)-induced Acute Lung Injury (HALI). We previously found that HO downregulates alveolar K_2P2.1 (TREK-1) K⁺ channels, which results in worsening lung injury. This decrease in TREK-1 levels leaves a subset of channels amendable to pharmacological intervention. Therefore, we hypothesized that TREK-1 activation protects against HALI. We treated HO-exposed mice and primary alveolar epithelial cells (AECs) with the novel TREK-1 activators ML335 and BL1249, and quantified physiological, histological, and biochemical lung injury markers. We determined the effects of these drugs on epithelial TREK-1 currents, plasma membrane potential (Em), and intracellular Ca²⁺ (iCa) concentrations using fluorometric assays, and blocked voltage-gated Ca²⁺ channels (Ca_V) as a downstream mechanism of cytokine secretion. Once-daily, intra-tracheal injections of HO-exposed mice with ML335 or BL1249 improved lung compliance, histological lung injury scores, broncho-alveolar lavage protein levels and cell counts, and IL-6 and IP-10 concentrations. TREK-1 activation also decreased IL-6, IP-10, and CCL-2 secretion from primary AECs. Mechanistically, ML335 and BL1249 induced TREK-1 currents in AECs, counteracted HO-induced cell depolarization, and lowered iCa²⁺ concentrations. In addition, CCL-2 secretion was decreased after L-type Ca_V inhibition. Therefore, Em stabilization with TREK-1 activators may represent a novel approach to counteract HALI.

Cost-Effectiveness of Biologics for Allergic Diseases

The introduction of specific humanized monoclonal antibodies over the past 20 years has dramatically changed the treatment of allergic diseases. At present, 5 mAbs are licensed for treating moderate to severe allergic and eosinophilic asthma, atopic dermatitis, chronic spontaneous urticaria, chronic sinusitis with nasal polyps, and eosinophilic granulomatosis with polyangiitis. Given the high costs of biologics, understanding their cost-effectiveness is critical. As new biologics are developed and new indications are approved for existing biologics, the use of biologics for allergic diseases will increase. Conducting cost-effectiveness evaluations in parallel to efficacy and effectiveness trials will help patients, providers, payers, and policymakers in decision making.

Bronchoscopy-guided bronchial epithelium sampling as a tool for selecting the optimal biologic treatment in a patient with severe asthma: a case report

Background

There are numerous biologics for treating patients with severe asthma. A cost-effective method for selecting the most appropriate biologic therapy for a patient is thus important. Bronchoscopy-guided bronchial epithelium sampling may provide information for determining the type of inflammation in the airways of severe asthma patients through immunochemical analysis and thus help clinicians select the correct biologics.

Case presentation

We report the case of a female with severe asthma and eosinophilia who initially responded to omalizumab treatment. She developed an allergic reaction after four injections of omalizumab. Omalizumab desensitization was successfully conducted. To select an appropriate biologic agent after this hypersensitivity episode, we performed bronchoscopy-guided bronchial epithelium sampling. Omalizumab treatment was resumed based on the findings of immunohistochemical staining after a successful desensitization procedure, leading to long-term control of her severe asthma.

Conclusions

Selecting an adequate biologic agent for severe, uncontrolled asthma is a challenge in clinical medical practice. Although phenotypes, blood eosinophils, and serum IgE levels have been proposed for use as a reference, there is a dissociation between the blood immune-cell level and the airway epithelium immune reaction, as confirmed in previous studies. Airway epithelium immunohistochemistry staining for targeted immune cells has been used to determine various types of airway inflammation; however, this technique is rarely used in a clinical setting. Previous studies have revealed the relative safety of performing bronchoscopy biopsies for patients with severe asthma. Among the sampling techniques used for tissue diagnosis, including nasal biopsies, nasal or bronchial brushing, and bronchoalveolar lavage, bronchoscopy-guided bronchial epithelium sampling provides more accurate information about the epithelial and inflammatory cells in the tissue context. It is thus a powerful tool for selecting the most suitable biologics in difficult clinical conditions.

Achyranthes bidentata Polysaccharide along with Anti-IL-5 Antibody Inhibits Allergic Lung Inflammation and Airway Hyperresponsiveness Mice Induced by House Dust Mites

Bronchial asthma is a chronic inflammatory disease which has become prevalent worldwide. There are millions of new patients and thousands of people die from asthma. Asthma is characterized with infiltration by eosinophils in pulmonary parenchyma, high serum IgE, and cytokines like IL-4, IL-5, and IL-13 secreted by allergen-specific T helper cell-2 (Th2) cells. Products of eosinophils are considered as negative regulators that work on remodeling lung tissue, including airway thickening, fibrosis, and angiogenesis. Achyranthes bidentata polysaccharide (ABPS) is a kind of polysaccharide extracted from the dry root of Achyranthes plant Achyranthes bidentata. ABPS is reported to have multiple biological functions and acts on the human immune system. ABPS can induce production of TNF-α in macrophage, enhance the killing ability of NK cells, and promote the proliferation of B cells. Besides this, ABPS is reported that can induce apoptosis of eosinophils by upregulating the expression of proteins involved in apoptosis. In this study, we constructed chronic allergic asthma mice model induced by house dust mites (HDM) with airway hyperresponsiveness (AHR) and found that anti-IL-5 mAb and ABPS treatment can both decrease inflammatory cells infiltration especially eosinophils and decrease the level of serum IgE and HDM-specific IgG1. The level of IFN-γ is increased and AHR is improved, and a more significant phenomenon was observed in anti-IL-5 mAb and ABPS combined treatment.

A Review of Three New Anti-interleukin-5 Monoclonal Antibody Therapies for Severe Asthma

Asthma is a chronic respiratory condition that is characterized by reversible airflow obstruction. Interleukin-5 (IL-5) is involved in the pathophysiology of the disease and drugs targeting IL-5 have been studied for years as a possible treatment option for severe asthma. In this review, the authors searched PubMed for major drug therapies and clinical trials against IL-5. A total of 29 articles met the criteria for selection and were shortlisted; of these, 10 papers were on benralizumab, 14 on mepolizumab, and five on reslizumab. The three drugs proved to be safe and efficacious for patients with severe asthma, leading to decreased rates of asthma exacerbations, lowered levels of eosinophils, and improved pulmonary functions in various studies. Patients also reported an improvement in the quality of life. The side effects of these three drugs were mild and no deaths directly linked to the drug were reported. However, longer duration studies are required to draw firm and strong conclusions on the safety of these therapeutic agents.

Personalised medicine in asthma: from curative to preventive medicine

The concept of asthma has changed substantially in recent years. Asthma is now recognised as a heterogeneous entity that is complex to treat. The subdivision of asthma, provided by "cluster" analyses, has revealed various groups of asthma patients who share phenotypic features. These phenotypes underlie the need for personalised asthma therapy because, in contrast to the previous approach, treatment must be tailored to the individual patient. Determination of the patient's asthma phenotype is therefore essential but sometimes challenging, particularly in elderly patients with a multitude of comorbidities and a complex exposure history. This review first describes the various asthma phenotypes, some of which were defined empirically and others through cluster analysis, and then discusses personalisation of the patient's diagnosis and therapy, addressing in particular biological therapies and patient education. This personalised approach to curative medicine should make way in the coming years for personalised preventive and predictive medicine, focused on subjects at risk who are not yet ill, with the aim of preventing asthma before it occurs. The concept of personalised preventive medicine may seem a long way off, but is it really?

[Role of fractalkine/CX3CL1 and its receptor CX3CR1 in allergic diseases]

Allergic asthma and atopic dermatitis are diseases mainly resulting from the activation of Th2 cells, that produce cytokines favouring IgE production and eosinophilia but also of Th1 cells, that contribute to inflammation chronicity. Lymphocyte recruitment and retention of Th cells in target organs are 2 key events for asthma and atopic dermatitis pathogenesis. While lymphocyte migration is regulated by chemokines and lipid mediators such as leukotrienes and prostaglandins, factors involved in lymphocyte retention and survival within inflammatory tissues remain poorly understood. Recent works show that, in allergic diseases, there is an increased expression of fractalkine/CX3CL1 and its unique receptor CX3CR1 and that this chemokine does not act as chemoattractant. In allergic asthma, CX3CR1 expression regulates Th2 and Th1 cell survival in the inflammatory lung, while, in atopic dermatitis, it regulate Th2 and Th1 cell retention into the inflammatory site. Use of peptides blocking fractalkine binding to its receptor is currently tested in the treatment of asthma and atopic dermatitis.

Therapeutic potential of targeting interleukin 5 in asthma

It is recognised that airway inflammation is key to asthma pathogenesis. Biopharmaceutical approaches have identified new therapies that target key cells and mediators that drive the inflammatory responses in the asthmatic lung. Such an approach resulted in the development of biologics targeted at inhibition of interleukin (IL)-4, IL-5 and IL-13. However, early clinical trials with these biologics in patients with asthma were, for the most part, disappointing even though they were highly effective in animal models of asthma. It is becoming apparent that significant clinical effects with anti-cytokine-based therapies are more likely in carefully selected patient populations that take asthma phenotypes into account. The development of discriminatory biomarkers and genetic profiling may aid identification of such patients with asthma. This review summarises the current evidence, demonstrating the effectiveness or otherwise of the targeting of IL-5 in patients with asthma.

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

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

An update on biologic-based therapy in asthma

Although it is recognized that airway inflammation is key to asthma pathogenesis, the marked heterogeneity in its clinical course and variations in response to treatment make it a challenging condition for the development of novel and effective biologic-based therapies. Biopharmaceutical approaches have identified new therapies that target key cells and mediators that drive inflammatory responses in the asthmatic lung. Such an approach resulted in the development of biologics targeted at inhibiting IL-4, IL-5 and IL-13. With the notable exception of the anti-IgE monoclonal antibody omalizumab, early clinical trials with cytokine-targeted biologics in patients with asthma were, for the most part, disappointing, despite being highly effective in animal models of asthma. It is becoming apparent that significant clinical effects with anticytokine-based therapies are more likely in carefully selected patient populations that take asthma phenotypes into account. The development of discriminatory biomarkers and genetic profiling may aid identification of such patients with asthma. This review summarizes recent evidence demonstrating the effectiveness or otherwise of monoclonal antibody-based therapies in patients with asthma.

Asthma: beyond corticosteroid treatment

Asthma is one of the most common chronic diseases in the world, affecting over 300 million people. It is an inflammatory disorder characterized by bronchoconstriction and airway hyperresponsiveness, followed by inflammatory manifestations in the respiratory system. The prevalence of asthma is rising and there is a clinical need to develop more effective treatments. While corticosteroids (glucocorticosteroids) remain the mainstay of asthma therapy, they have limitations because of their potentially severe side-effects and the presence of corticosteroid resistance in some patients. This review discusses current strategies in the treatment of asthma and considers new therapeutic regimens of asthma in the drug development pipeline.

[Targeted therapies in severe asthma: the discovery of new molecules]

The pathophysiological mechanisms involved in the chronicity and phenotypic heterogeneity of asthma offer the prospect of new therapeutic opportunities. A better clinical and biological characterisation of selected patients has led to the development of targeted therapies. Studies are under way to demonstrate their efficacy and tolerance and also their impact on the natural history of the disease. This revue aims to examine the therapies, developed during the last ten years, that are based on the immunological mechanisms involved in the pathophysiology of asthma, essentially in its severe form. The rapid expansion of human monoclonal antibodies has allowed testing of various immunological pathways. Anti-IgE, anti- IL-5, and anti-IL-13 strategies seem the most promising. Antagonists to TNF-alpha and I'IL-4 have not succeeded in reducing the events related to severe asthma in a convincing manner. Molecules targeted against thymic stromal lymphopoietin (TSLP) and I'IL-9 are under development. These approaches are involved in the development of therapeutic programmes adapted to the patient's phenotype, that is to say a personalised approach to care.

Eosinophil apoptosis and clearance in asthma

Asthma is an increasingly common respiratory condition characterized by reversible airway obstruction, bronchial hyper-responsiveness and airway inflammation with a clear unmet need for more effective therapy. Eosinophilic asthma is a phenotype of the condition that features increased blood or sputum eosinophils whose numbers correlate with disease severity. Several lines of evidence are now emerging, which implicate increased persistence of eosinophils in the lungs of patients with asthma as a consequence of inhibition of and defects in the apoptotic process, together with impaired apoptotic cell removal mechanisms. This article will update our knowledge of the mechanisms controlling eosinophil apoptosis and clearance, together with evidence implicating defects in apoptosis and pro-inflammatory cell removal in asthma. Recent developments in novel therapies for asthma that target eosinophil apoptotic and/or clearance pathways will also be discussed.

Profile of reslizumab in eosinophilic disease and its potential in the treatment of poorly controlled eosinophilic asthma

Eosinophils are important proinflammatory cells that make a major contribution to the inflammation seen in allergic diseases including asthma. Interleukin-5 is central to eosinophil maturation, release from the bone marrow, and subsequent accumulation, activation, and persistence in the tissues. Reslizumab (Cinquil™) is a humanized monoclonal antibody with potent interleukin-5 neutralizing effects, which represents a potential treatment for poorly controlled eosinophilic asthma. This review will consider the current status of the clinical development of reslizumab for asthma and in other inflammatory diseases with a marked eosinophilic component.

Pathogenesis of aspirin-exacerbated respiratory disease and reactions

Physiologic and pharmacologic studies support the hypothesis that aspirin-exacerbated respiratory disease (AERD) involves fundamental dysregulation in the production of and end-organ responsiveness to both antiinflammatory eicosanoids (prostaglandin E2) and proinflammatory effectors (cysteinyl leukotrienes). The acquired nature of AERD implies a disturbance in a potential epigenetic control mechanism of the relevant mediator systems, which may be a result of incompletely clarified environmental factors (eg, viral or bacterial infections, inhaled pollutants).

CX3CL1 in allergic diseases: not just a chemotactic molecule

Allergic asthma and atopic dermatitis (AD) are two allergic diseases that are primarily driven by the activation of T helper (Th)2 cells. Th2 cells produce cytokines that directly contribute to the symptoms of these diseases. The recruitment and maintenance of Th2 cells into the target tissues are two key events in the pathogenesis of allergic asthma and AD. While migration is mediated by both chemokines and lipid mediators such as leukotrienes and prostaglandins, very little is known about the molecules involved in lymphocyte survival and maintenance in inflamed tissues. However, chemokines could also play a role in this phenomenon. An example of this could be illustrated by CX3CL1, also known as fractalkine. CX3CL1 is a chemokine that is upregulated in some inflammatory diseases including allergic pathologies and that was recently demonstrated to provide a survival signal upon binding to its unique receptor CX3CR1.

Immunologic therapeutic interventions in asthma: impact on natural history

The discovery of new pathobiological pathways involved in asthma chronicity and reliefs offers novel therapeutic avenues. Enhanced phenotyping criteria associated with simple biologic characterization allowed to test targeted interventions in selected patients. Long-term studies are de facto lacking but required to address their impact on the natural history of the disease. Here, the authors review all potential available therapeutics based on immunologic pathways involved in asthma pathophysiology during the last decade.

An update on emerging drugs for asthma

INTRODUCTION

It is recognized that airway inflammation is key to asthma pathogenesis. Biopharmaceutical approaches have identified new therapies that target key cells and mediators that drive the inflammatory responses in the asthmatic lung. Such an approach resulted in the development of biologics including IL-4, IL-5 and IL-13. However, clinical trials with these biologics in patients with asthma were for the most part disappointing even though they proved to be highly effective in animal models of asthma.

AREAS COVERED

This review based on English-language original articles in PubMed or MedLine published in the last 5 years will update the current status, therapeutic potential and potential problems of recent drug developments in asthma therapy.

EXPERT OPINION

It is becoming apparent that significant clinical effects with anti-cytokine-based therapies are more likely in carefully selected patient populations that take asthma phenotypes into account. It might also be more clinically effective if more than one cytokine and/or chemokine were to be targeted rather than a single mediator.

Oligonucleotides: a multi-targeted approach for the treatment of respiratory diseases

Reversing inflammatory lung disease remains the foremost challenge in treating respiratory diseases such as asthma and chronic obstructive pulmonary disease. Reducing (or modifying) the underlying inflammatory process with mono-target drugs has proven challenging. The era of designing ‘one target for one disease’ has evolved such that a growing body of evidence suggests a single drug that is capable of specifically targeting multiple targets and pathways would be better at arresting progression of these respiratory diseases and be an important advancement in current therapy. Oligonucleotide-based drugs represent an emerging class of drug candidates. Their properties, a broader range of targets over conventional small-molecule drugs and recent clinical proof-of-concept support their development as novel multi-targeting agents for the treatment of respiratory diseases.

IL-35 production by inducible costimulator (ICOS)-positive regulatory T cells reverses established IL-17-dependent allergic airways disease

BACKGROUND

Recent evidence suggests that IL-17 contributes to airway hyperresponsiveness (AHR); however, the mechanisms that suppress the production of this cytokine remain poorly defined.

OBJECTIVE

We sought to identify the regulatory cells and molecules that suppress IL-17-dependent allergic airways disease.

METHODS

Mice were sensitized by means of airway instillations of ovalbumin together with low levels of LPS. Leukocyte recruitment to the lung and AHR were assessed after daily challenges with aerosolized ovalbumin. Flow cytometry, quantitative PCR, and gene-targeted mice were used to identify naturally arising subsets of regulatory T (Treg) cells and their cytokines required for the suppression of established allergic airway disease.

RESULTS

Allergic sensitization through the airway primed both effector and regulatory responses. Effector responses were initially dominant and led to airway inflammation and IL-17-dependent AHR. However, after multiple daily allergen challenges, IL-17 production and AHR decreased, even though pulmonary levels of T(H)17 cells remained high. This loss of AHR was reversible and required the expansion of a Treg cell subset expressing both forkhead box protein 3 and inducible costimulator. These Treg cells also expressed the regulatory cytokines IL-10, TGF-β, and IL-35. Whereas IL-10 and TGF-β were dispensable for suppression of AHR, IL-35 was required.

CONCLUSION

IL-35 production by inducible costimulator-positive Treg cells can suppress IL-17 production and thereby reverse established, IL-17-dependent AHR in mice. Targeting this pathway might therefore be of therapeutic value for treating allergic asthma in human subjects.

Using biomarkers in the assessment of airways disease

A biomarker provides a window on underlying disease activity. This is helpful when the pathology, treatment response, or both are heterogeneous or when trying to interpret nonspecific respiratory symptoms in patients with comorbidities. The successful application of a biomarker result is critically dependent on the specific question being addressed and the performance characteristics of the biomarker in relation to that question in the context of pretest probabilities. Negative prediction might be the best way to use a biomarker, such as a D-dimer, pro-brain natriuretic peptide, and exhaled nitric oxide. In this review the role of biomarkers in airways disease (notably induced sputum eosinophils and exhaled nitric oxide) is considered in relation to risk stratification, identification of treatment responders, identification of a clinical phenotype, monitoring of disease, and new drug development.

Functions of T cells in asthma: more than just T(H)2 cells

Asthma has been considered a T helper 2 (T(H)2) cell-associated inflammatory disease, and T(H)2-type cytokines, such as interleukin-4 (IL-4), IL-5 and IL-13, are thought to drive the disease pathology in patients. Although atopic asthma has a substantial T(H)2 cell component, the disease is notoriously heterogeneous, and recent evidence has suggested that other T cells also contribute to the development of asthma. Here, we discuss the roles of different T cell subsets in the allergic lung, consider how each subset can contribute to the development of allergic pathology and evaluate how we might manipulate these cells for new asthma therapies.

CX3CR1 is required for airway inflammation by promoting T helper cell survival and maintenance in inflamed lung

Allergic asthma is a T helper type 2 (T(H)2)-dominated disease of the lung. In people with asthma, a fraction of CD4(+) T cells express the CX3CL1 receptor, CX3CR1, and CX3CL1 expression is increased in airway smooth muscle, lung endothelium and epithelium upon allergen challenge. Here we found that untreated CX3CR1-deficient mice or wild-type (WT) mice treated with CX3CR1-blocking reagents show reduced lung disease upon allergen sensitization and challenge. Transfer of WT CD4(+) T cells into CX3CR1-deficient mice restored the cardinal features of asthma, and CX3CR1-blocking reagents prevented airway inflammation in CX3CR1-deficient recipients injected with WT T(H)2 cells. We found that CX3CR1 signaling promoted T(H)2 survival in the inflamed lungs, and injection of B cell leukemia/lymphoma-2 protein (BCl-2)-transduced CX3CR1-deficient T(H)2 cells into CX3CR1-deficient mice restored asthma. CX3CR1-induced survival was also observed for T(H)1 cells upon airway inflammation but not under homeostatic conditions or upon peripheral inflammation. Therefore, CX3CR1 and CX3CL1 may represent attractive therapeutic targets in asthma.

Janus kinase-3 dependent inflammatory responses in allergic asthma

Allergic asthma is a chronic inflammatory condition of the lung characterized by reversible airway obstruction, high serum immunoglobulin (Ig) E levels, and chronic airway inflammation. A number of cells including mast cells, T cells, macrophages and dendritic cells play a role in the pathogenesis of the disease. Janus kinase (JAK)-3, a non-receptor protein tyrosine kinase, traditionally known to mediate cytokine signaling, also regulates functional responses of these cells. In this review the role of JAK-3 in regulating various pathogenic processes in allergic asthma is discussed. We propose that targeting JAK-3 is a rationale approach to control the inflammatory responses of multiple cell types responsible for the pathogenesis of allergic asthma.

Novel anti-inflammatory treatments for asthma

Inhaled corticosteroids do not suppress inflammation or control symptoms in all asthmatics. In particular, corticosteroid insensitivity exists in many patients and may potentially be reversible. There is a need to develop new anti-inflammatory therapies for this disease. This article critically reviews clinical trial data of novel anti-inflammatory drugs in asthma, encompassing specific anti-eosinophil therapies, including antisense chemokine receptor antagonists, anti-cytokine monoclonal antibodies and small-molecule approaches. We provide an insight into the possible future of asthma therapy by identifying drugs with the most promising therapeutic profile.

Narrative review: the role of Th2 immune pathway modulation in the treatment of severe asthma and its phenotypes

New therapeutic approaches are needed for patients with severe asthma who are refractory to standard therapy comprising high doses of inhaled corticosteroids plus long-acting beta(2)-agonists. Current treatment guidelines for patients with severe asthma from the National Asthma Education and Prevention Program recommend the addition of oral corticosteroids, which are associated with substantial morbidity, and, for those with allergic asthma, anti-IgE. Genetic and translational studies, as well as clinical trials, suggest that in a subgroup of patients, the pathobiology of severe asthma is mediated by immune pathways driven by T-helper 2 (Th2)-type CD4(+) T cells, which produce a characteristic repertoire of interleukins (ILs), including IL-4, IL-5, and IL-13. Therefore, biological modifiers of Th2-type ILs, such as monoclonal antibodies, soluble receptors, and receptor antagonists, are a rational strategy for developing new treatment approaches but will need to be targeted to selected patients in whom the appropriate Th2 immune pathway is "active." The benefits of immune-modifier therapies targeting Th2-type cytokines, however, need to be weighed against the toxicities associated with inhibition of key biological pathways, as well as the expense of future medications. Therefore, future clinical trials need to clearly establish the efficacy and safety of biological modifiers of Th2 immune pathways before these approaches can enter routine clinical practice for the treatment of severe asthma.

Two first-in-human, open-label, phase I dose-escalation safety trials of MEDI-528, a monoclonal antibody against interleukin-9, in healthy adult volunteers

BACKGROUND

Interleukin-9 (IL-9) is involved in pathogenic aspects of the asthmatic response, including induction of the proliferation of T-helper type 2 lymphocytes, mucus production, and mast-cell differentiation, proliferation, and recruitment to the lung. In preclinical studies in mice, inhibition of IL-9 through neutralizing monoclonal antibody (mAb) treatment partially reduced airway hyperresponsiveness and mast-cell progenitor migration to the lung.

OBJECTIVE

The goal of the present studies was to determine the safety and pharmacokinetic profiles and immunogenicity of MEDI-528, a humanized immunoglobulin G1k anti-IL-9 mAb, in healthy adult volunteers.

METHODS

In separate open-label, Phase I dose-escalation studies, single doses of MEDI-528 0.3, 1.0, 3.0, or 9.0 mg/kg were administered as an intravenous infusion (20 mg/min administered over 1-40 minutes, depending on dose) and by subcutaneous injection. All subjects were followed for 84 days. Any laboratory test value outside the normal reference range was considered an adverse event (AE).

RESULTS

Twenty-four subjects were enrolled in the intravenous study, and 29 subjects were enrolled in the subcutaneous study. No deaths or serious or severe AEs occurred in either study. The most frequently reported AEs in the intravenous study were laboratory test abnormalities; the most frequently reported AEs in the subcutaneous study were pharyngolaryngeal pain, palpable lymph nodes, and laboratory test abnormalities. The single-dose pharmacokinetics of MEDI-528 were linear and dose proportional over the dose range studied with both routes of administration. The mean t((1/2)) after intravenous administration was approximately 26 days (range, 25-28 days); the mean t((1/2)) after subcutaneous administration ranged from 33 to 87 days across doses. A low titer (1:80) of antibodies to MEDI-528 was detected on day 84 in a single volunteer receiving intravenous MEDI-528 3.0 mg/kg. No antibody titers were detected in any of the volunteers receiving subcutaneous MEDI-528.

CONCLUSIONS

Administered intravenously or subcutaneously, MEDI-528 had an acceptable safety profile and exhibited linear pharmacokinetics over the dose range studied in healthy adults in these Phase I studies. The findings support further investigation of MEDI-528 in multiple-dose trials in patients with asthma. ClinicalTrials.gov Identification numbers: NCT00192296 (intravenous study); NCT00116168 (subcutaneous study).

Asthma therapies revisited: what have we learned?

Asthma is a heterogenous disorder related to numerous biologic, immunologic, and physiologic components that generate multiple clinical phenotypes. Further, genetic and environmental factors interact in ways that produce variability in both disease onset and severity and differential expression based on both the age and sex of the patient. Thus, the natural history of asthma is complex in terms of disease expression, remission, relapse, and progression. As such, therapy for asthma is complicated and has been approached from the standpoints of primary, secondary, and tertiary prevention. Presently, asthma cannot be cured but can be controlled in most patients, an indication that most of the success clinical research strategies have realized has been in the area of tertiary prevention. Since for many adult patients with asthma their disease had its roots in early life, much recent research has focused on events during early childhood that can be linked to subsequent asthma development with the hopes of creating appropriate interventions to alter its natural history of expression. These research approaches can be categorized into three questions. Who is the right patient to treat? When is the right time to begin treatment? And finally, what is the appropriate treatment to prescribe?

Eosinophil-derived IFN-gamma induces airway hyperresponsiveness and lung inflammation in the absence of lymphocytes

BACKGROUND

Eosinophils are key players in T(H)2-driven pathologies, such as allergic lung inflammation. After IL-5- and eotaxin-mediated tissue recruitment, they release several cytotoxic and inflammatory mediators. However, their exact contribution to asthma remains controversial. Indeed, in human subjects anti-IL-5 treatment inhibits eosinophilia but not antigen-induced airway hyperresponsiveness (AHR). Likewise, lung fibrosis is abrogated in 2 strains of eosinophil-deficient mice, whereas AHR is inhibited in only one of them. Finally, eosinophils have been shown to attract T(H)2 lymphocytes at the inflammatory site.

OBJECTIVE

The ability of eosinophils to promote AHR and lung inflammation independently of lymphocytes was investigated.

METHODS

Adoptive transfers of resting or activated eosinophils from IL-5 transgenic mice were performed into naive BALB/c mice, mice with severe combined immunodeficiency, and IFN-gamma-deficient BALB/c recipients.

RESULTS

Adoptively transferred eosinophils induced lung inflammation, fibrosis, collagen deposition, and AHR not only in BALB/c mice but also in recipient mice with severe combined immunodeficiency. Surprisingly, IFN-gamma expression was increased in lungs from eosinophil-transferred animals. Furthermore, IFN-gamma neutralization in recipients partially inhibited eosinophil-induced AHR. Moreover, IFN-gamma-deficient eosinophils or eosinophils treated with a blocking anti-IFN-gamma receptor antibody failed to induce AHR in IFN-gamma-deficient recipients. Finally, in vitro and at low concentrations, IFN-gamma increased eosinophil peroxidase release, potentiated chemotaxis, and prolonged survival, suggesting the existence of an autocrine mechanism.

CONCLUSIONS

These results support the important and previously unsuspected contribution of eosinophils to lung inflammation independently of lymphocytes through production of IFN-gamma, the prototypical T(H)1 cytokine.

A prostaglandin D2 receptor antagonist modifies experimental asthma in sheep

BACKGROUND

Prostaglandin (PG) D(2) is the major cylooxygenase metabolite released by mast cells upon allergen stimulation, and elicits responses through either the prostanoid DP1 receptor and/or the chemoattractant receptor homologous molecule expressed on T-helper type 2 (Th2) cells (CRTH2/DP2). Experimental evidence suggests that stimulation of one or both these receptors contributes to asthma pathophysiology.

OBJECTIVE

The aim of this study was to test the hypothesis that the prostanoid DP1 receptor contributes to asthma pathophysiology by determining the efficacy of an orally active antagonist for this receptor, S-5751, on allergen-induced bronchoconstriction, airway hyperresponsiveness (AHR) and cellular inflammation in the sheep model of asthma.

METHODS

PGD(2)-induced cyclic adenosine monophosphate (cAMP) production in platelet-rich plasma was used to establish the in vitro efficacy of S-5751. In vivo, sheep naturally allergic to Ascaris suum were challenged with an aerosolized antigen with and without S-5751 treatment (given 4 days before and for 6 days after the challenge).

RESULTS

S-5751 inhibited PGD(2)-induced cAMP production in platelet-rich plasma with an IC(50) value of 0.12 microm. S-5751 at 30 mg/kg, but not at 3 mg/kg, reduced the early bronchoconstriction and inhibited the late bronchoconstriction. AHR and inflammatory cell infiltration in bronchoalveolar lavage fluid at days 1 and 7 were also inhibited with the 30 mg/kg dose. The responses observed with S-5751 at 30 mg/kg were comparable with those with montelukast treatment (0.15 mg/kg, twice a day, intravenous); however, S-5751 did not block inhaled leukotrieneD(4)-induced broncoconstriction.

CONCLUSION

Prostanoid DP1 receptor inhibition may represent an alternative target for asthma therapy.

Mepolizumab and exacerbations of refractory eosinophilic asthma

BACKGROUND

Exacerbations of asthma are associated with substantial morbidity and mortality and with considerable use of health care resources. Preventing exacerbations remains an important goal of therapy. There is evidence that eosinophilic inflammation of the airway is associated with the risk of exacerbations.

METHODS

We conducted a randomized, double-blind, placebo-controlled, parallel-group study of 61 subjects who had refractory eosinophilic asthma and a history of recurrent severe exacerbations. Subjects received infusions of either mepolizumab, an anti-interleukin-5 monoclonal antibody (29 subjects), or placebo (32) at monthly intervals for 1 year. The primary outcome measure was the number of severe exacerbations per subject during the 50-week treatment phase. Secondary outcomes included a change in asthma symptoms, scores on the Asthma Quality of Life Questionnaire (AQLQ, in which scores range from 1 to 7, with lower values indicating more severe impairment and a change of 0.5 unit considered to be clinically important), forced expiratory volume in 1 second (FEV(1)) after use of a bronchodilator, airway hyperresponsiveness, and eosinophil counts in the blood and sputum.

RESULTS

Mepolizumab was associated with significantly fewer severe exacerbations than placebo over the course of 50 weeks (2.0 vs. 3.4 mean exacerbations per subject; relative risk, 0.57; 95% confidence interval [CI], 0.32 to 0.92; P=0.02) and with a significant improvement in the score on the AQLQ (mean increase from baseline, 0.55 vs. 0.19; mean difference between groups, 0.35; 95% CI, 0.08 to 0.62; P=0.02). Mepolizumab significantly lowered eosinophil counts in the blood (P<0.001) and sputum (P=0.002). There were no significant differences between the groups with respect to symptoms, FEV(1) after bronchodilator use, or airway hyperresponsiveness. The only serious adverse events reported were hospitalizations for acute severe asthma.

CONCLUSIONS

Mepolizumab therapy reduces exacerbations and improves AQLQ scores in patients with refractory eosinophilic asthma. The results of our study suggest that eosinophils have a role as important effector cells in the pathogenesis of severe exacerbations of asthma in this patient population. (Current Controlled Trials number, ISRCTN75169762.)

Pulmonary fibrosis: pathogenesis, etiology and regulation

Pulmonary fibrosis and architectural remodeling of tissues can severely disrupt lung function, often with fatal consequences. The etiology of pulmonary fibrotic diseases is varied, with an array of triggers including allergens, chemicals, radiation and environmental particles. However, the cause of one of the most common pulmonary fibrotic conditions, idiopathic pulmonary fibrosis (IPF), is still unclear. This review examines common mechanisms of pulmonary wound-healing responses following lung injury, and highlights the pathogenesis of some of the most widespread pulmonary fibrotic diseases. A three phase model of wound repair is reviewed that includes; (1) injury; (2) inflammation; and (3) repair. In most pulmonary fibrotic conditions dysregulation at one or more of these phases has been reported. Chronic inflammation can lead to an imbalance in the production of chemokines, cytokines, growth factors, and disrupt cellular recruitment. These changes coupled with excessive pro-fibrotic IL-13 and/or TGFbeta1 production can turn a well-controlled healing response into a pathogenic fibrotic response. Endogenous regulatory mechanisms are discussed including novel areas of therapeutic intervention. Restoring homeostasis to these dysregulated healing responses, or simply neutralizing the key pro-fibrotic mediators may prevent or slow the progression of pulmonary fibrosis.

Montelukast and bronchial inflammation in asthma: a randomised, double-blind placebo-controlled trial

BACKGROUND

Examination of bronchoalveolar lavage, induced sputum, and peripheral blood indicate that cysteinyl leukotriene receptor blockers decrease inflammatory cells in asthma but these do not examine airway tissue per se.

OBJECTIVES

Our objective was to determine the effect of montelukast, a leukotriene receptor antagonist, on airway tissue inflammatory cells by direct bronchoscopic examination of the bronchial mucosa.

METHODS

Adult subjects with mild asthma (pre-bronchodilator FEV(1)> or =70% predicted; PC(20) of < or =4 mg/mL) were given 10mg/day oral montelukast (N=38) or placebo (N=37) for 6 weeks. Bronchial mucosal eosinophils and mast cells were identified and counted.

RESULTS

Change from baseline in numbers of biopsy EG2+ ("activated") eosinophils was the primary endpoint; numbers of total (chromotrope 2R+) eosinophils and (tryptase+) mast cells were secondary. Unexpectedly, there were many patients with zero EG2+ eosinophils at baseline. There was a within-group decrease in EG2+ cells, from 13.54 cells/mm (at baseline) to 0.79 cells/mm at 6 weeks in the montelukast group (LS mean change; 95% confidence interval=-13.59 [-25.45, -1.74]cells/mm; P<0.05), a change not observed in the placebo group (-1.17 [-13.26, 10.91]cells/mm; NS). The zero-inflated Poisson statistical model demonstrated that montelukast significantly reduced post-treatment EG2+ cells by 80% compared with placebo (95% CI [70.6-86.8%]; P<0.0001). The data for total eosinophils showed similar changes. The reduction in mast cell numbers was 12% (95% CI [7.9, 16.0]; P<0.0001).

CONCLUSION

Direct examination of airway tissue confirms that montelukast decreases the number of eosinophils and mast cells in asthma.

Biologics in asthma: difficulties and drawbacks

BACKGROUND

Biologics have become an increasingly important class of therapeutic compounds in a variety of immune and/or inflammatory diseases. Patients with severe uncontrolled asthma represent a significant unmet need.

METHODS

This review gives some examples of the complex use of biologics in asthma.

RESULTS/CONCLUSIONS

It is very difficult to predict the efficacy of biologics in severe asthma and only one monoclonal antibody to date has been found to be effective and approved by both the FDA and European Medicines Agency (EMEA) for the treatment of difficult allergic asthma. New pathways may prove to be of importance for the development of biologics. Biologics are not devoid of side effects, which can, although not always, be predicted from their mechanism of action. These include hypersensitivity reactions, which need to be better understood to prevent and control them. Finally, biologics should be cost-effective. This review gives some examples of the complex use of biologics in asthma.

CXCR2 antagonists for the treatment of pulmonary disease

Chemokines have long been implicated in the initiation and amplification of inflammatory responses by virtue of their role in leukocyte chemotaxis. The expression of one of the receptors for these chemokines, CXCR2, on a variety of cell types and tissues suggests that these receptors may have a broad functional role under both constitutive conditions and in the pathophysiology of a number of acute and chronic diseases. With the development of several pharmacological, immunological and genetic tools to study CXCR2 function, an important role for this CXC chemokine receptor subtype has been identified in chronic obstructive pulmonary disease (COPD), asthma and fibrotic pulmonary disorders. Interference with CXCR2 receptor function has demonstrated different effects in the lungs including inhibition of pulmonary damage induced by neutrophils (PMNs), antigen or irritant-induced goblet cell hyperplasia and angiogenesis/collagen deposition caused by lung injury. Many of these features are common to inflammatory and fibrotic disorders of the lung. Clinical trials evaluating small molecule CXCR2 antagonists in COPD, asthma and cystic fibrosis are currently underway. These studies hold considerable promise for identifying novel and efficacious treatments of pulmonary disorders.