Effect of inhaled interleukin-5 on airway hyperreactivity and eosinophilia in asthmatics

Real-World Efficacy of Treatment with Benralizumab, Dupilumab, Mepolizumab and Reslizumab for Severe Asthma: A Systematic Review and Meta-analysis

BACKGROUND

Severe asthma is a major cause of morbidity. Some patients may benefit from biological therapies. Most evaluations of these treatments are derived from randomised controlled trials (RCTs), but few patients are eligible for these trials. Studies involving more diverse groups of participants exist but there is a lack of precise pooled estimates.

OBJECTIVE

This systematic review aims to evaluate the real-world efficacy of recently and nearly licensed biological therapies for severe asthma to assess the generalisability of the RCT data.

METHODS

Clinical outcomes including exacerbation rate, oral corticosteroid (OCS) usage, forced expiratory volume in 1 second (FEV₁ ) and fractional exhaled nitric oxide (FeNO) were examined. Studies were assessed for risk of bias using the Critical Appraisal Skills Programme (CASP) checklist tool. The certainty of evidence was assessed using GRADE.

RESULTS

A total of 21 studies examining biologicals in real-world settings were identified, they mostly focused on benralizumab and mepolizumab. The introduction of biologicals reduced the annualised exacerbation rate significantly by -3.79 (95% CI -4.53, -3.04), -3.17 (95% CI -3.74, -2.59) and -6.72 (95% CI -8.47, -4.97) with benralizumab, mepolizumab and reslizumab respectively. Likewise, improvements were observed in FEV₁ (0.17 L 95% CI 0.11, 0.24) and FeNO (-14.23 ppb 95% CI -19.71, -8.75) following treatment with mepolizumab. After treatment with benralizumab there was an increase in FEV₁ (0.21 L 95% CI 0.08, 0.34).

CONCLUSIONS

These data demonstrate that anti-IL5 biologicals may improve the clinical outcomes of patients with severe asthma in a clinic environment with similar effect sizes to RCTs. The data were mainly retrospective and unadjusted, so estimated effect sizes may not be reliable. More data is needed to acquire accurate effect estimates in different subpopulations of patients.

Location of eosinophils in the airway wall is critical for specific features of airway hyperresponsiveness and T2 inflammation in asthma

Eosinophils are implicated as effector cells in asthma but the functional implications of the precise location of eosinophils in the airway wall is poorly understood. We aimed to quantify eosinophils in the different compartments of the airway wall and associate these findings with clinical features of asthma and markers of airway inflammation.In this cross-sectional study, we utilised design-based stereology to accurately partition the numerical density of eosinophils in both the epithelial compartment and the subepithelial space (airway wall area below the basal lamina including the submucosa) in individuals with and without asthma and related these findings to airway hyperresponsiveness (AHR) and features of airway inflammation.Intraepithelial eosinophils were linked to the presence of asthma and endogenous AHR, the type of AHR that is most specific for asthma. In contrast, both intraepithelial and subepithelial eosinophils were associated with type-2 (T2) inflammation, with the strongest association between IL5 expression and intraepithelial eosinophils. Eosinophil infiltration of the airway wall was linked to a specific mast cell phenotype that has been described in asthma. We found that IL-33 and IL-5 additively increased cysteinyl leukotriene (CysLT) production by eosinophils and that the CysLT LTC₄ along with IL-33 increased IL13 expression in mast cells and altered their protease profile.We conclude that intraepithelial eosinophils are associated with endogenous AHR and T2 inflammation and may interact with intraepithelial mast cells via CysLTs to regulate airway inflammation.

Targeted Anti-IL-5 Therapies and Future Therapeutics for Hypereosinophilic Syndrome and Rare Eosinophilic Conditions

Eosinophilic inflammation is a component of many atopic diseases such as asthma, and biologics targeting eosinophils have been shown to be effective in subsets of these patients. However, there also are conditions in which eosinophils are the key inflammatory cells responsible for driving tissue damage. In these eosinophilic diseases such as hyper-eosinophilic syndrome, eosinophilic esophagitis, and eosinophilic granulomatosis with polyangiitis (EGPA), the development of biologics inhibiting eosinophilic inflammation have offered targeted therapeutic strategies for patients that have not responded well to typical first line drugs, which often have significant adverse side effects with poor disease modification or recurrent relapse with significant morbidity. IL-5 has long been recognized as the key inflammatory cytokine involved in the priming and survival of eosinophils and their proliferation and maturation in eosinophilic disease. There are a number of trials and case series demonstrating the immunomodulatory benefits of anti-IL-5 therapies in these diseases with good clinical responses. Yet, due to the heterogeneity and rarity of these conditions, anti-IL-5 therapies have not resulted in disease remission for all patients. Clearly, further research into the use of anti-IL-5 therapies in various eosinophilic diseases is needed and ongoing investigation into other immune mechanisms underlying chronic eosinophilic diseases may provide alternative therapies for these challenging conditions.

Targeting IL-5 pathway against airway hyperresponsiveness: A comparison between benralizumab and mepolizumab

BACKGROUND AND PURPOSE

Airway hyperresponsiveness (AHR) is a central abnormality in asthma. IL-5 may modulate AHR in animal models of asthma, but the available data is inconsistent on the impact of targeting IL-5 pathway against AHR. The difference between targeting IL-5 or the IL-5 receptor, α subunit (IL-5Rα) in modulating AHR remains to be investigated in human airways. The aim of this study was to compare the role of the anti-IL-5Rα benralizumab and the anti-IL-5 mepolizumab against AHR and to assess whether these agents influence the levels of cAMP.

EXPERIMENTAL APPROACH

Passively sensitized human airways were treated with benralizumab and mepolizumab. The primary endpoint was the inhibition of AHR to histamine. The secondary endpoints were the protective effect against AHR to parasympathetic activation and mechanical stress, and the tissue modulation of cAMP.

KEY RESULTS

Benralizumab and mepolizumab significantly inhibited the AHR to histamine (maximal effect -134.14 ± 14.93% and -108.29 ± 32.16%, respectively), with benralizumab being 0.73 ± 0.10 logarithm significantly more potent than mepolizumab. Benralizumab and mepolizumab significantly inhibited the AHR to transmural stimulation and mechanical stress. Benralizumab was 0.45 ± 0.16 logarithm significantly more potent than mepolizumab against AHR to parasympathetic activation. The effect of these agents was significantly correlated with increased levels of cAMP.

CONCLUSION AND IMPLICATIONS

Targeting the IL-5/IL-5Rα axis is an effective strategy to prevent the AHR. Benralizumab was more potent than the mepolizumab and the concentration-dependent beneficial effects of both these monoclonal antibodies were related to improved levels of cAMP in hyperresponsive airways.

Limonene-induced activation of A2A adenosine receptors reduces airway inflammation and reactivity in a mouse model of asthma

Animal models of asthma have shown that limonene, a naturally occurring terpene in citrus fruits, can reduce inflammation and airway reactivity. However, the mechanism of these effects is unknown. We first performed computational and molecular docking analyses that showed limonene could bind to both A_2A and A_2B receptors. The pharmacological studies were carried out with A_2A adenosine receptor knock-out (A_2AKO) and wild-type (WT) mice using ovalbumin (OVA) to generate the asthma phenotype. We investigated the effects of limonene on lung inflammation and airway responsiveness to methacholine (MCh) and NECA (nonselective adenosine analog) by administering limonene as an inhalation prior to OVA aerosol challenges in one group of allergic mice for both WT and KO. In whole-body plethysmography studies, we observed that airway responsiveness to MCh in WT SEN group was significantly lowered upon limonene treatment but no effect was observed in A_2AKO. Limonene also attenuated NECA-induced airway responsiveness in WT allergic mice with no effect being observed in A_2AKO groups. Differential BAL analysis showed that limonene reduced levels of eosinophils in allergic WT mice but not in A_2AKO. However, limonene reduced neutrophils in sensitized A_2AKO mice, suggesting that it may activate A_2B receptors as well. These data indicate that limonene-induced reduction in airway inflammation and airway reactivity occurs mainly via activation of A_2AAR but A_2B receptors may also play a supporting role.

Targeted biologic therapy for asthma

BACKGROUND

Asthma is a common and potentially serious condition affecting 300 million people worldwide. For many years, we have relied on a one-size-fits-all approach to its management, using corticosteroids and bronchodilators for all symptomatic patients. However, with more recent advances, it has become clear that asthma is a heterogeneous condition with multiple different underlying pathways. Understanding the different subtypes will be a key to giving us the ability to intervene in a targeted way to personalize care for patients with asthma.

SOURCES OF DATA

Key published literature, guidelines and trials from clinicaltrials.gov.

AREAS OF AGREEMENT

The most widely studied of these subtypes is T2 high eosinophilic asthma, for which there are an increasing number of biologic therapies available. T2 high asthma is associated with the cytokines interleukin (IL)-4, IL-5 and IL-13, for each of which biologics have been developed.

AREAS OF CONTROVERSY

It is currently unclear which of the available biologics provides superior efficacy. It is also unclear how to select which biologic for which patient.

GROWING POINTS

Head-to-head trials of the available T2 biologics will be important to determine superiority, and a suggested order for trialling biologics. Going further than this, we would like to see further analyses of available biologics to allow us to predict responders from non-responders in advance of administering therapy.

AREAS TIMELY FOR DEVELOPING RESEARCH

Non-eosinophilic T2 low asthma is an area that is under-researched and for which there are few treatments available. It is likely that there are different subtypes in this category of asthma and unravelling what these are will be crucial to developing effective treatments.

Proinflammatory Pathways in the Pathogenesis of Asthma

There are multiple proinflammatory pathways in the pathogenesis of asthma. These include both innate and adaptive inflammation, in addition to inflammatory and physiologic responses mediated by eicosanoids. An important component of the innate allergic immune response is ILC2 activated by interleukin (IL)-33, thymic stromal lymphopoietin, and IL-25 to produce IL-5 and IL-13. In terms of the adaptive T-lymphocyte immunity, CD4+ Th2 and IL-17-producing cells are critical in the inflammatory responses in asthma. Last, eicosanoids involved in asthma pathogenesis include prostaglandin D₂ and the cysteinyl leukotrienes that promote smooth muscle constriction and inflammation that propagate allergic responses.

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.

Study of Clinical Characteristics and Cytokine Profiles of Asthmatic Children with Rhinovirus Infection during Acute Asthma Exacerbation at National Hospital of Pediatrics

Background

In children with asthma, the viral infection of airways is usually a main cause of acute asthma exacerbation and hospitalization. However, few studies on clinical and biomolecular characteristics of asthmatic children in this field have been done, especially in emergent countries.

Objective

This study described the clinical and biological characteristics of asthmatic children who had acute asthma exacerbation and rhinovirus (RV) infection.

Methods

Children under 15 years of age hospitalized for acute asthma exacerbation were included. They underwent clinical examination and peripheral blood analyses for the cytokine profile. The severity of acute asthma exacerbation was evaluated by Pediatric Asthma Score (PAS). Healthy children under 15 years of age were also invited in this study.

Results

One hundred fifteen asthmatic children were included in this study. There were 18.2% of mild PAS, 37.4% of moderate PAS, and 44.4% of severe PSA. Among them, 63/115 (54.8%) asthmatic children had positive RV infection (RV⁺). The percentages of asthmatic children with RV⁺ had increased polymorphonuclear leucocytes were significantly higher than asthmatic children with RV⁻. There were no significant differences of the concentrations of non-Th2-related cytokines in asthmatic children with RV⁻ and RV⁺. The concentration of Th2-related cytokines (IL-5 and IL-13) in asthmatic children with RV⁺ was significantly higher than those with RV⁻. However, there was no significant difference for the cytokine profile between mild, moderate, and severe asthma.

Conclusion

RV infection is a main cause of acute asthma exacerbation in children with asthma. The increase of Th2-related cytokines, especially IL-5 and IL-13, is a relevant biomarker for RV infection in asthmatic children with severe exacerbation.

Identification of novel 2-benzyl-1-indanone analogs as interleukin-5 inhibitors

A novel series of 2-benzyl-1-indanone analogs were investigated as IL-5 inhibitory activity. Among the synthesized compounds, 7-(cyclohexylmethoxy)-2-(4-hydroxybenzyl)-2,3-dihydro-1H-inden-1-one (7s, 100.0% inhibition at 30 μM, IC₅₀ = 4.0 μM), and 7-(cyclohexylmethoxy)-2-(3-hydroxybenzyl)-2,3-dihydro-1H-inden-1-one (7t, 95.0% inhibition at 30 μM, IC₅₀ = 6.0 μM) showed the best inhibitory activity against IL-5. The 2-benzyl-1-indanone analogs showed moderate to strong IL-5 inhibitory activity. Especially, hydroxyl (HBD/HBA) substituent at position 3 or 4 on phenyl ring B showed potent IL-5 inhibition. Additionally, the bulky hydrophobic cyclohexylmethoxy group at position 7 of the 1-indanone ring is favorable for the inhibitory activity.

Safety of humanized monoclonal antibodies against IL-5 in asthma: focus on reslizumab

INTRODUCTION

Reslizumab, a humanized mAb against IL-5, reduces the number of eosinophils in the blood and lungs. Based on efficacy and safety data from pivotal RCTs, reslizumab had been approved for use as an add-on maintenance treatment of severe asthma with an eosinophilic phenotype in adults who have a history of exacerbations despite receiving their current asthma medicines. Areas covered: Current literature on reslizumab has been reviewed with a specific focus on its safety profile in the treatment of severe asthma. Expert opinion: Large pivotal and supportive trials reinforce the view that reslizumab is well tolerated, with an acceptable safety profile in patients exposed for longer than 2 years. However, no or few data concerning safety in special populations such as smokers, those with immune- and cellular senescence, patients with comorbidities and those receiving multi-drug treatments are available as yet. Furthermore, we need to fully elucidate some fundamental issues such as the risk of anaphylaxis and the long-term risk-benefit ratio of the impact of depletion of eosinophils and the potential risk of malignancies induced by a treatment with this anti-IL-5 agent.

Efficacy and safety of benralizumab for eosinophilic asthma: A systematic review and meta-analysis of randomized controlled trials

CONTEXT

Benralizumab is a humanized monoclonal antibody that targets the α chain of the IL-5 receptor (IL-5Rα) and is currently being assessed in clinical trials for asthma control.

OBJECTIVE

Our systematic review and meta-analysis intends to evaluate the therapeutic efficacy and safety of benralizumab in patients with eosinophilic asthma.

DATA SOURCES AND EXTRACTION

Literature searches of PubMed, Embase, and the Cochrane Library were performed to identify randomized controlled trials of benralizumab and clinic outcomes in asthmatics.

RESULTS

In total, 7 articles with 2,321 subjects met our inclusion criteria. From this pooled analysis, we found that benralizumab significantly reduces exacerbations (RR: 0.63, 95% CI: 0.52-0.76, p < 0.00001; I² = 52%, p = 0.06) compared to placebo in eosinophilic asthma. There was no statistical trend for improvement in forced expiratory volume in 1 second or asthma control indices such as Quality of Life Assessment (AQLQ) and Asthma Control Questionnaire score in benralizumab-treated patients. In addition, safety data indicated that benralizumab administration resulted no increasing incidence of adverse events and was well tolerated (RR: 1.00, 95% CI: 0.95-1.05, p = 0.96; I² = 40%, p = 0.13).

CONCLUSION

These results demonstrate the efficacy and safety of benralizumab for asthma patients with severe or uncontrolled symptoms and elevated eosinophils and provide support for benralizumab as an ideal option to treat asthma in this patient population.

Reslizumab in the treatment of inadequately controlled asthma in adults and adolescents with elevated blood eosinophils: clinical trial evidence and future prospects

Eosinophils have long been implicated as playing a central role in the pathophysiology of asthma in many patients, and eosinophilic asthma is now recognized as an important asthma endotype. Eosinophil differentiation, maturation, migration, and survival are primarily under the control of interleukin-5 (IL-5). Reslizumab is a humanized monoclonal (immunoglobulin G4/κ) antibody that binds with high affinity to circulating human IL-5 and downregulates the IL-5 signaling pathway, potentially disrupting the maturation and survival of eosinophils. In 2016, an intravenous formulation of reslizumab was approved in the USA, Canada, and Europe as add-on maintenance treatment for patients aged ⩾18 years with severe asthma and with an eosinophilic phenotype. The efficacy of reslizumab as add-on intravenous therapy has been reported in several phase III studies in patients with inadequately controlled moderate-to-severe asthma and elevated blood eosinophil counts (⩾400 cells/µl). Compared with placebo, reslizumab was associated with significant improvements in clinical exacerbation rate, forced expiratory volume in 1 s, asthma symptoms and quality of life, and significant reductions in blood eosinophil counts. Reslizumab also demonstrated a favorable tolerability profile similar to that of placebo, with reported adverse events being mostly mild to moderate in severity. Ongoing studies are focusing on the evaluation of a subcutaneous formulation of reslizumab in patients with asthma and elevated eosinophil levels. This review discusses the preclinical and clinical trial data available on reslizumab, potential opportunities for predicting an early response to reslizumab, and future directions in the field of anti-IL-5 antibody therapy.

Novel analogs of N-acylhydroxyethylaminomethyl-4H-chromen-4-one scaffold as IL-5 inhibitors

A number of N-acyl substituted hydroxyethylaminomethyl-4H-chromen-4-ones 6a-u were prepared and evaluated for their IL-5 inhibitory activity. Among them, the compound 6r (95.0% inhibition at 30µM, IC₅₀=10.0µM, ClogP=4.1549) showed most potent inhibitory activity. The structure activity relationship revealed that the bulkier or hydrophobic substituents at urea, carbamate or amide group resulted in good inhibitory activity against IL-5. Moreover, electron donating group at phenyl ring (6g and 6s) is much more active than electron withdrawing group (6f). Finally, replacement of cyclohexylmethoxy group at 5^th position of ring A with bulky aliphatic substituents resulted in the loss of activity.

Natural killer T cell sensitization during neonatal respiratory syncytial virus infection induces eosinophilic lung disease in re-infected adult mice

Respiratory syncytial virus (RSV) is a major viral pathogen that causes severe lower respiratory tract infections in infants and the elderly worldwide. Infants with severe RSV bronchiolitis tend to experience more wheezing and asthma in later childhood. Because invariant natural killer T (iNKT) cells are associated with the asthma pathology, we investigated whether neonatal iNKT cells are involved in the aggravation of pulmonary diseases following RSV infection in mice. Intranasal exposure to the iNKT cell ligand α-galactosylceramide (α-GC) with RSV primary infection in neonatal mice elicited neither cytokine production (except for a slight increase of IL-5) nor pulmonary eosinophilia, despite the presence of both CD1d⁺ cells and NKT cells. Interestingly, in adult mice re-infected with RSV, neonatal iNKT cell sensitization by α-GC during RSV primary infection resulted in much higher levels of pulmonary Th2 cytokines and elevated eosinophilia with airway hyperresponsiveness, whereas this was not observed in cd1d knockout mice. In contrast, α-GC priming of adults during RSV re-infection did not induce more severe airway symptoms than RSV re-infection in the absence of α-GC. α-GC co-administration during RSV primary infection facilitated RSV clearance regardless of age, but viral clearance following re-infection was not iNKT cell-dependent. This study clearly demonstrates that RSV-induced immune responses can be altered by iNKT cells, suggesting that neonatal iNKT cell sensitization during RSV primary infection is associated with exacerbation of pulmonary diseases following RSV re-infection in adulthood.

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

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

Patient stratification and the unmet need in asthma

Asthma is often described as an inflammatory disease of the lungs and in most patients symptomatic treatment with bronchodilators or inhaled corticosteroids is sufficient to control disease. Unfortunately there are a proportion of patients who fail to achieve control despite treatment with the best current treatment. These severe asthma patients have been considered a homogeneous group of patients that represent the unmet therapeutic need in asthma. Many novel therapies have been tested in unselected asthma patients and the effects have often been disappointing, particularly for the highly specific monoclonal antibody-based drugs such as anti-IL-13 and anti-IL-5. More recently, it has become clear that asthma is a syndrome with many different disease drivers. Clinical trials of anti-IL-13 and anti-IL-5 have focused on biomarker-defined patient groups and these trials have driven the clinical progression of these drugs. Work on asthma phenotyping indicates that there is a group of asthma patients where T helper cell type 2 (Th2) cytokines and inflammation predominate and these type 2 high (T2-high) patients can be defined by biomarkers and response to therapies targeting this type of immunity, including anti-IL-5 and anti-IL-13. However, there is still a subset of T2-low patients that do not respond to these new therapies. This T2-low group will represent the new unmet medical need now that the T2-high-targeting therapies have made it to the market. This review will examine the current thinking on patient stratification in asthma and the identification of the T2-high subset. It will also look at the T2-low patients and examine what may be the drivers of disease in these patients.

CSL311, a novel, potent, therapeutic monoclonal antibody for the treatment of diseases mediated by the common β chain of the IL-3, GM-CSF and IL-5 receptors

The β common-signaling cytokines interleukin (IL)-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-5 stimulate pro-inflammatory activities of haematopoietic cells via a receptor complex incorporating cytokine-specific α and shared β common (βc, CD131) receptor. Evidence from animal models and recent clinical trials demonstrate that these cytokines are critical mediators of the pathogenesis of inflammatory airway disease such as asthma. However, no therapeutic agents, other than steroids, that specifically and effectively target inflammation mediated by all 3 of these cytokines exist. We employed phage display technology to identify and optimize a novel, human monoclonal antibody (CSL311) that binds to a unique epitope that is specific to the cytokine-binding site of the human βc receptor. The binding epitope of CSL311 on the βc receptor was defined by X-ray crystallography and site-directed mutagenesis. CSL311 has picomolar binding affinity for the human βc receptor, and at therapeutic concentrations is a highly potent antagonist of the combined activities of IL-3, GM-CSF and IL-5 on primary eosinophil survival in vitro. Importantly, CSL311 inhibited the survival of inflammatory cells present in induced sputum from human allergic asthmatic subjects undergoing allergen bronchoprovocation. Due to its high potency and ability to simultaneously suppress the activity of all 3 β common cytokines, CSL311 may provide a new strategy for the treatment of chronic inflammatory diseases where the human βc receptor is central to pathogenesis. The coordinates for the βc/CSL311 Fab complex structure have been deposited with the RCSB Protein Data Bank (PDB 5DWU).

Emerging monoclonal antibodies as targeted innovative therapeutic approaches to asthma

Asthma is characterized by discordant responses among cells of the adaptive and innate immune systems. This interplay involves a complex pattern of cytokine-driven processes resulting in cell migration and recruitment, inflammation, and proliferative states. The significant majority of asthmatic patients respond well to conventional inhaled treatments. However, about 5% of asthmatics have severe refractory asthma and account for 50% of the health expenditure on asthma. Human(ized) monoclonal antibodies (hMabs) targeting inflammatory pathways are promising therapeutic agents in asthma management. The anti-IgE hMab omalizumab was the first biologic treatment approved for the treatment of allergic asthma. Potential future strategies and targets include interleukin (IL)-5, IL-4, and IL-13, anti-TSLP, IL-25, and IL-33. hMabs targeting IL-5 have shown great promise in severe refractory asthma with a persisting eosinophilia, and clinical trials with hMabs against IL-13 and IL4Rα have also shown clinical benefit. Studies of hMabs against other cytokines in severe asthma are under way.

The contractile lability of smooth muscle in asthmatic airway hyperresponsiveness

The contractile capacity of airway smooth muscle is not fixed but modulated by an impressive number of extracellular inflammatory mediators. Targeting the transient component of airway hyperresponsiveness ascribed to this contractile lability of ASM is a quest of great promises in order to alleviate asthma symptoms during inflammatory flares. However, owing to the plethora of mediators putatively involved and the molecular heterogeneity of asthma, it is more likely that many mediators conspire to increase the contractile capacity of ASM, each of which contributing to a various extent and in a time-varying fashion in individuals suffering from asthma. The task of identifying a common mend for a tissue rendered hypercontractile by imponderable assortments of inflammatory mediators is puzzling.

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.

Characteristics of innate lymphoid cells (ILCs) and their role in immunological disorders (an update)

Innate lymphoid cells (ILCs) are a novel family of hematopoietic effectors and regulators of innate immunity. Although these cells are morphologically similar to B cells and T cells, however they do not express antigen receptors. ILCs seems to have emerging roles in innate immune responses against infectious or non-infectious microorganisms, protection of the epithelial barrier, lymphoid organogenesis and inflammation, tissue remodeling and regulating homeostasis of tissue stromal cells. In addition, it has recently been reported that ILCs have a crucial role in several disorders such as allergy and autoimmunity. Based on their phenotype and functions, ILCs are classified into three major groups called ILCs1, ILCs2, and ILCs3. Here we reviewed the most recent data concerning diverse ILC phenotypes, subclasses, functions in immune responses as well as in immune mediated disorders.

NSFC spurs significant basic research progress of respiratory medicine in China

Over the years, research in respiratory medicine has progressed rapidly in China. This commentary narrates the role of the National Natural Science Foundation of China (NSFC) in supporting the basic research of respiratory medicine, summarizes the major progress of respiratory medicine in China, and addresses the main future research directions sponsored by the NSFC.

Silencing Nociceptor Neurons Reduces Allergic Airway Inflammation

Lung nociceptors initiate cough and bronchoconstriction. To elucidate if these fibers also contribute to allergic airway inflammation, we stimulated lung nociceptors with capsaicin and observed increased neuropeptide release and immune cell infiltration. In contrast, ablating Nav1.8(+) sensory neurons or silencing them with QX-314, a charged sodium channel inhibitor that enters via large-pore ion channels to specifically block nociceptors, substantially reduced ovalbumin- or house-dust-mite-induced airway inflammation and bronchial hyperresponsiveness. We also discovered that IL-5, a cytokine produced by activated immune cells, acts directly on nociceptors to induce the release of vasoactive intestinal peptide (VIP). VIP then stimulates CD4(+) and resident innate lymphoid type 2 cells, creating an inflammatory signaling loop that promotes allergic inflammation. Our results indicate that nociceptors amplify pathological adaptive immune responses and that silencing these neurons with QX-314 interrupts this neuro-immune interplay, revealing a potential new therapeutic strategy for asthma.

Anti-interleukin therapy in asthma

Asthma remains one of the most prevalent and costly diseases in the United States. Asthma accounts for a significant amount of direct medical expenditures and indirect cost from days lost at school and work. Modern understanding of its complex pathogenesis has allowed recognition of the heterogeneity of the disease across populations and the various inflammatory pathways that drive airway inflammation in asthma. Interleukins play important roles in both eosinophilic and noneosinophilic asthma, and anti-interleukin therapy will allow for a targeted, personalized approach to asthma management. With the success of anti-interleukin (IL) -4, IL-5, and IL-13 therapy in recent large trials among specific populations of asthmatics, it is likely that targeted anti-interleukin therapy will be approved for use in the near future. It will be important for clinicians and pharmacists to understand their risks, benefits, and proper indications.

Anti-IL5 therapy for asthma and beyond

Airway inflammation is considered to be the primary component contributing to the heterogeneity and severity of airway disorders. Therapeutic efficacies of diverse novel biologics targeting the inflammatory pathways are under investigation. One such target is IL-5, a type-1 cytokine that is central to the initiation and sustenance of eosinophilic airway inflammation. Over the past decade, anti-IL5 molecules have been documented to have mixed therapeutic benefits in asthmatics. Post hoc analyses of the trials reiterate the importance of identifying the IL-5-responsive patient endotypes. In fact, the currently available anti-IL5 treatments are being considered beyond asthma management; especially in clinical complications with an underlying eosinophilic pathobiology such as hypereosinophilic syndrome (HES) and eosinophilic granulomatosis and polyangitis (EGPA). In addition, closer analyses of the available data indicate alternative mechanisms of tissue eosinophilia that remain uncurbed with the current dosage and delivery platform of the anti-IL5 molecules.

High risk association of IL-4 VNTR polymorphism with asthma in a North Indian population

BACKGROUND

A case-control study was conducted to evaluate the role of IL-4 VNTR polymorphism in asthma that has been associated with various inflammatory diseases worldwide. This is the first case-control study conducted in India, investigating the role of IL-4 VNTR polymorphism in asthma pathogenesis.

METHODS

A case-control study was performed with a total of 824 adult subjects, inducting 410 asthma patients and 414 healthy controls from North India. The genotypes were identified by polymerase chain reaction.

RESULTS

Statistical analysis for the IL-4 VNTR polymorphism revealed that the Rp1 allele was significantly associated with asthma with OR=1.47, 95% CI (1.11-1.94) and p=0.005. The Rp1/Rp1 homozygous mutant genotype posed a high risk towards asthma with OR=2.39, 95% CI (0.96-6.14) and p=0.040. The Rp2/Rp1 heterozygous genotype also posed a risk towards asthma with OR=1.39, 95% CI (1.00-1.94) and p=0.040. Most of the phenotypic traits were significantly associated with the disease.

CONCLUSIONS

IL-4 VNTR polymorphism is a high risk factor for asthma in the studied North Indian population.

Airway hyperresponsiveness is associated with airway remodeling but not inflammation in aging Cav1-/- mice

Background

Airway inflammation and airway remodeling are the key contributors to airway hyperresponsiveness (AHR), a characteristic feature of asthma. Both processes are regulated by Transforming Growth Factor (TGF)-β. Caveolin 1 (Cav1) is a membrane bound protein that binds to a variety of receptor and signaling proteins, including the TGF-β receptors. We hypothesized that caveolin-1 deficiency promotes structural alterations of the airways that develop with age will predispose to an increased response to allergen challenge.

Methods

AHR was measured in Cav1-deficient and wild-type (WT) mice 1 to 12 months of age to examine the role of Cav1 in AHR and the relative contribution of inflammation and airway remodeling. AHR was then measured in Cav1^-/- and WT mice after an ovalbumin-allergen challenge performed at either 2 months of age, when remodeling in Cav1^-/- and WT mice was equivalent, and at 6 months of age, when the Cav1^-/- mice had established airway remodeling.

Results

Cav1^-/- mice developed increased thickness of the subepithelial layer and a correspondingly increased AHR as they aged. In addition, allergen-challenged Cav1^-/- mice had an increase in AHR greater than WT mice that was largely independent of inflammation. Cav1^-/- mice challenged at 6 months of age have decreased AHR compared to those challenged at 2 months with correspondingly decreased BAL IL-4 and IL-5 levels, inflammatory cell counts and percentage of eosinophils. In addition, in response to OVA challenge, the number of goblet cells and α-SMA positive cells in the airways were reduced with age in response to OVA challenge in contrast to an increased collagen deposition further enhanced in absence of Cav1.

Conclusion

A lack of Cav1 contributed to the thickness of the subepithelial layer in mice as they aged resulting in an increase in AHR independent of inflammation, demonstrating the important contribution of airway structural changes to AHR. In addition, age in the Cav1^-/- mice is a contributing factor to airway remodeling in the response to allergen challenge.

Suplatast tosilate ameliorates airway hyperreactivity and inflammation through inhibition of the GATA‑3/IL‑5 signaling pathway in asthmatic rats

Airway hyperreactivity and inflammation are important factors in the aggravation of lung function. Suplatast tosilate (IPD) is a novel and unique anti‑asthma clinical compound. However, the mechanisms of IPD action in the inhibition of asthma remain to be elucidated. The present study aimed to investigate the role of the GATA binding protein 3 (GATA‑3)/interleukin (IL)‑5 signaling pathway in IPD‑induced inhibition of asthma. Sprague‑Dawley rats were sensitized by intraperitoneal injection with ovalbumin (OVA) to establish an animal model of asthma. IPD was administered continuously (C‑IPD) or at a later stage (L‑IPD). Budesonide (BUD) was used as a positive control. Airway resistance and the expression of genes at the mRNA and protein levels were measured. Morphological changes in lung tissue and the percentage of eosinophils (EOS) in peripheral blood were observed and correlation analysis was performed. The results revealed that sensitization by OVA significantly increased airway resistance and the percentage of EOS in peripheral blood and induced significant inflammatory changes in lung tissue, as demonstrated by thick epithelium, goblet cell hyperplasia and submucosal cell infiltration. In addition, sensitization by OVA was found to markedly upregulate IL‑5 mRNA and protein expression. Airway resistance was found to positively correlate with the expression of IL‑5 in the rat lung tissues. Sensitization by OVA was also observed to markedly enhance GATA‑3 protein expression and GATA‑3 levels were found to positively correlate with airway resistance and IL‑5 levels. Similar to the effect of BUD, treatment with C‑IPD or L‑IPD was found to significantly attenuate OVA‑induced increases in airway resistance and the percentage of EOS in peripheral blood. Notably, treatment with C‑IPD or L‑IPD markedly reduced the OVA-induced expression of IL‑5 and GATA‑3. In the present study, IPD intervention was demonstrated to ameliorate airway hyperreactivity and inflammation and the mechanisms may involve inhibition of the GATA‑3/IL‑5 signaling pathway.

Monoclonal antibodies for asthma and chronic obstructive pulmonary disease

INTRODUCTION

In asthma and chronic obstructive pulmonary disease (COPD), the inflammation in the airways cannot always be controlled with conventional therapies, such as inhaled corticosteroids. Addition of more specific anti-inflammatory therapies, such as monoclonal antibodies, against inflammation pathways might improve the disease outcome.

AREAS COVERED

This review individually discusses the major inflammation pathways and their potential blocking monoclonal antibodies in asthma and COPD.

EXPERT OPINION

The current use of omalizumab in asthma provides a good example on the potential therapeutic role of monoclonal antibodies in both asthma and COPD. There are many other monoclonal antibodies which are currently investigated as possible therapies in these diseases. The identification of the disease subsets in which such antibodies might exert the maximum benefit opens the door for personalized medicine and for targeted biological therapy in asthma and COPD.

Regulatory T cells and Th1/Th2 in peripheral blood and their roles in asthmatic children

OBJECTIVE

To determine the changes in CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) and the Th1/Th2 ratio in peripheral blood of children with asthma, in order to investigate its association with asthma.

METHODS

A total of 150 children with asthma were allocated into the acute phase group (n=94) and remission phase group (n=56) based on clinical manifestations. The acute phase group was subdivided into the mild group (n=54) and severe group (n=40). Flow cytometry was applied to determine CD4(+)CD25(+)Foxp3(+) Treg, CD4(+)IFN-γ(+) Th1 and CD4(+)IL-4(+) Th2 levels in peripheral blood of different groups, and the results were compared with normal children (control group, n=50).

RESULTS

The Treg level was significantly lower in the asthma group than the control group (P<0.01): the Treg level was significantly lower in the acute phase group than the remission phase group and control group (P<0.01) and also significantly lower in the severe group than the mild group (P<0.01). The Th1/Th2 ratio was significantly lower in the asthma group than the control group (P<0.01) and also significantly lower in the acute phase group than the remission phase group and control group (P<0.01). The Treg level in peripheral blood of asthmatic children was negatively correlated with the severity of asthma (r=-0.737, P<0.01) and the Th1/Th2 ratio was also negatively correlated with the severity of asthma (r=-0.615, P<0.01), but the Treg level was positively correlated with the Th1/Th2 ratio (r=0.856, P<0.01).

CONCLUSIONS

The significantly decreased level of Treg in peripheral blood and Th subset imbalance in asthmatic children suggest the important roles of Treg and Th immunity in pathogenesis of asthma. The Treg level and Th1/Th2 ratio in peripheral blood can be used to evaluate the severity asthma.

Polyphenols and their components in experimental allergic asthma

The aim of the study was to investigate the potential anti-inflammatory effects in -experimental allergic asthma of natural polyphenolic compounds or their single major components. The experiment was performed after 21-days sensitization of guinea pigs with ovalbumin suspension. Changes in airway reactivity after the long-term treatment with the polyphenolic compounds Provinol and Flavin-7 and their single major components quercetin and resveratrol during were assessed using a whole body plethysmography. Reactivity of tracheal smooth muscle was studied in vitro in response to cumulative doses of the bronchoconstrictive mediators histamine and acetylcholine. Furthermore, concentrations of the inflammatory cytokines IL-4 and IL-5 were measured in bronchoalveolar lavage fluid. The results demonstrate significant anti-inflammatory effects of Provinol and Flavin-7 exerted in the airways. In contrast, chronic treatment with quercetin and resveratrol, single components of the two polyphenols, did not show such activity. We conclude that polyphenolic compounds are more effective in the anti-inflammatory effects in the airways than their separate components.

Neuronal modulation of airway and vascular tone and their influence on nonspecific airways responsiveness in asthma

The autonomic nervous system provides both cholinergic and noncholinergic neural inputs to end organs within the airways, which includes the airway and vascular smooth muscle. Heightened responsiveness of the airways to bronchoconstrictive agents is a hallmark feature of reactive airways diseases. The mechanisms underpinning airways hyperreactivity still largely remain unresolved. In this paper we summarize the substantial body of evidence that implicates dysfunction of the autonomic nerves that innervate smooth muscle in the airways and associated vasculature as a prominent cause of airways hyperresponsiveness in asthma.

IL-5 Promoter Polymorphism Enhances IgE Responses to Staphylococcal Superantigens in Adult Asthmatics

Interleukin 5 (IL-5) is a key cytokine involved in the induction of T-helper type 2 (Th2) responses in the asthmatic airway. We investigated IL-5 genetic polymorphisms associated with asthma phenotypes, including IgE responses to staphylococcal enterotoxins A and B (SEA and SEB, respectively), in asthmatics. Adult asthmatics (n=310) and normal controls (n=160) were enrolled in the present study. Serum total and specific IgE to SEA and SEB were measured. Two IL-5 polymorphisms, -746A>G and +4499T>G, were genotyped using the primer-extension method. There were no significant differences in genotype or haplotype frequencies of these polymorphisms between the two groups. Asthmatics carrying the AG/GG genotype at -746A>G had a significantly higher prevalence of serum specific IgE to SEA (P=0.008), higher total IgE levels (P=0.014), and lower PC20 methacholine levels (P=0.002) compared to those with the AA genotype. These findings suggest that the IL-5 promoter polymorphism at -746A>G enhances serum total and specific IgE responses to SEA, which may augment airway hyperresponsiveness in adult asthmatics.

Anti-Interleukin-5 Monoclonal Antibodies

Descriptive studies have shown an association between eosinophils, interleukin (IL)-5 and pathophysiological processes in patients with atopic asthma. These observations have led to an interest in the eosinophil as the pathogenic cell responsible for many of the clinical features of asthma including symptoms of wheeze, shortness of breath and cough, along with the physiological events such as airway hyperresponsiveness (AHR) and changes in lung function. IL-5 is one of the key cytokines responsible for eosinopoiesis in the bone marrow, along with recruitment and survival of eosinophils in the tissues. In view of this, IL-5 has been an attractive target for the development of anti-IL-5 monoclonal antibodies, inhibiting its action. The results of preclinical studies are viewed as encouraging. Preclinical development involved studies in mice, guinea-pigs and cynomolgus monkeys, with conflicting results in terms of changes in blood and bronchoalveolar lavage eosinophils, AHR and pulmonary resistance. These may be attributed to interspecies differences and to the different models used. Monoclonal antibodies directed against IL-5 have been used in at least four studies involving patients with asthma. Those preliminary studies have shown clear reductions in both blood and sputum eosinophils but no significant changes in physiological parameters of AHR, the late asthmatic reaction or in lung function or symptoms. As in the animal studies, these results suggest a dissociation between eosinophils, AHR, lung function and symptoms of asthma, which may be explained by the multitude of cells involved in the pathogenesis of asthma.

Novel interleukin-5 inhibitors based on hydroxyethylaminomethyl-4H-chromen-4-one scaffold

Hydroxyethylaminomethyl-4H-chromenones were previously discovered as fairly strong IL-5 inhibitor. For determination of detail structure activity relationship, N-substituted hydroxyethylaminomethylchromenones 4a-n were prepared and evaluated for their IL-5 inhibitory activity. Shifting the hydrophobic group to nitrogen from 1-position of hydroxyethylamino moiety of hydroxyethylaminomethyl-4H-chromenones enhances the activity. The increment in bulkiness or hydrophobicity of alkyl side chain at amino group increases the activity. The same level of activity of 5-(cyclohexylmethoxy)-3-(N-benzyl-2-hydroxyethylaminomethyl)-4H-chromenone analogs regardless of hydrophobic or hydrophilic substituents at 4th position of phenyl ring might infer the existence of tunnel structure in the putative receptor for accepting these side chains.

Interleukin 5 is protective during sepsis in an eosinophil-independent manner

RATIONALE

The immune response in sepsis is characterized by overt immune dysfunction. Studies indicate immunostimulation represents a viable therapy for patients. One study suggests a potentially protective role for interleukin 5 (IL-5) in sepsis; however, the loss of eosinophils in this disease presents a paradox.

OBJECTIVES

To assess the protective and eosinophil-independent effects of IL-5 in sepsis.

METHODS

We assessed the effects of IL-5 administration on survival, bacterial burden, and cytokine production after polymicrobial sepsis. In addition, we examined the effects on macrophage phagocytosis and survival using fluorescence microscopy and flow cytometry.

MEASUREMENTS AND MAIN RESULTS

Loss of IL-5 increased mortality and tissue damage in the lung, IL-6 and IL-10 production, and bacterial burden during sepsis. Therapeutic administration of IL-5 improved mortality in sepsis. Interestingly, IL-5 administration resulted in neutrophil recruitment in vivo. IL-5 overexpression in the absence of eosinophils resulted in decreased mortality from sepsis and increased circulating neutrophils and monocytes, suggesting their importance in the protective effects of IL-5. Furthermore, novel data demonstrate IL-5 receptor expression on neutrophils and monocytes in sepsis. IL-5 augmented cytokine secretion, activation, phagocytosis, and survival of macrophages. Importantly, macrophage depletion before the onset of sepsis eliminated IL-5-mediated protection. The protective effects of IL-5 were confirmed in humans, where IL-5 levels were elevated in patients with sepsis. Moreover, neutrophils and monocytes from patients expressed the IL-5 receptor.

CONCLUSIONS

Taken together, these data support a novel role for IL-5 on noneosinophilic myeloid populations, and suggest treatment with IL-5 may be a viable therapy for sepsis.

Overview of animal models of asthma

Asthma is an inflammatory disease characterized by airways obstruction, airways hyperresponsiveness, excessive mucous secretion and cough. Guinea pig airways display many anatomical, physiological and pharmacological attributes of human airways, making this species ideal for modeling the asthmatic condition. This unit provides an overview of animal models of asthma, including definitions, descriptions of available animal models, and discussion of numerous critical issues to consider before designing a model to study this complex disease.

Evaluation of the immunity activity of glycyrrhizin in AR mice

In this study, we evaluated effect of glycyrrhizin on immunity function in allergic rhinitis (AR) mice. The AR mice model were induced by dripping ovalbumin in physiological saline (2 mg mL⁻¹, 10 μL) into the bilateral nasal cavities using a micropipette. After the AR model was induced, mice were randomly divided into six groups: the normal control, model, lycopene 20 mg kg⁻¹ (as positive control drug) group, and glycyrrhizin 10, 20, 30 mg kg⁻¹ groups. After the sensitization day 14, lycopene (20 mg/kg BW) and glycyrrhizin (10, 20 and 30 mg/kg BW) were given orally for 20 days once a day. Mice in the normal control and model groups were given saline orally once a day for 20 days. Results showed that glycyrrhizin treatment could dose-dependently significantly reduce blood immunoglobulin E (IgE), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6), nitrous oxide (NO), tumor necrosis factor-alpha (TNF-α) levels and nitrous oxide synthase (NOS) activity and enhance blood immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), interleukin-2 (IL-2) and interleukin-12 (IL-12) levels in AR mice. Furthermore, glycyrrhizin treatment could dose-dependently significantly enhance acetylcholinesterase (AchE) activity and reduce substance P (SP) level in peripheral blood and nasal mucosa of AR mice. We conclude that glycyrrhizin can improve immunity function in AR mice, suggesting a potential drug for the prevention and therapy of AR.

A 'Good' muscle in a 'Bad' environment: the importance of airway smooth muscle force adaptation to airway hyperresponsiveness

Asthma is characterized by airway inflammation, with a consequent increase in spasmogens, and exaggerated airway narrowing in response to stimuli, termed airway hyperresponsiveness (AHR). The nature of any relationship between inflammation and AHR is less clear. Recent ex vivo data has suggested a novel mechanism by which inflammation may lead to AHR, in which increased basal ASM-tone, due to the presence of spasmogens in the airways, may "strengthen" the ASM and ultimately lead to exaggerated airway narrowing. This phenomenon was termed "force adaptation" [Bossé, Y., Chin, L.Y., Paré, P.D., Seow, C.Y., 2009. Adaptation of airway smooth muscle to basal tone: relevance to airway hyperresponsiveness. Am. J. Respir. Cell Mol. Biol. 40, 13-18]. However, it is unknown whether the magnitude of the effect of force adaptation ex vivo could contribute to exaggerated airway narrowing in vivo. Our aim was to utilize a computational model of ASM shortening in order to quantify the potential effect of force adaptation on airway narrowing when all other mechanical factors were kept constant. The shortening in the model is dictated by a balance between physiological loads and ASM force-generating capacity at different lengths. The results suggest that the magnitude of the effect of force adaptation on ASM shortening would lead to substantially more airway narrowing during bronchial challenge at any given airway generation. We speculate that the increased basal ASM-tone in asthma, due to the presence of inflammation-derived spasmogens, produces an increase in the force-generating capacity of ASM, predisposing to AHR during subsequent challenge.

The relationship of airway hyperresponsiveness and airway inflammation: Airway hyperresponsiveness in asthma: its measurement and clinical significance

Airway hyperresponsiveness (AHR) is a clinical feature of asthma and is often in proportion to the underlying severity of the disease. To understand AHR and the mechanisms that contribute to these processes, it is helpful to divide the airway components that affect this feature of asthma into "persistent" and "variable" categories. The persistent component of AHR represents structural changes in the airway, whereas the variable feature relates to inflammatory events. Insight into how these interrelated components of AHR can contribute to asthma is gained by studying treatment effects and models of asthma provocation.

Use of biologicals as immunotherapy in asthma and related diseases

Recent advances in our understanding of the immune-mediated inflammatory pathways in asthma and other allergic diseases have resulted in the development of novel biological compounds for the treatment of these conditions. These compounds offer an advantage over glucocorticosteroid therapy by specifically targeting components of the immunologic cascade, thereby allowing patients to reduce or discontinue their glucocorticosteroid treatment. Another potential advantage of biological compounds is that they may provide additional anti-inflammatory benefits, over and above those provided by glucocorticosteroid therapy, for patients who continue to have evidence of refractory asthma. The anti-IgE monoclonal antibody omalizumab is already being used for the treatment of allergic asthma and a number of other biological therapies are currently in various stages of clinical development. The purpose of this review is to summarize the data from these studies and to provide a rationale for the use of these compounds in asthma and related allergic airway diseases.

Cytokine antagonists for the treatment of asthma: progress to date

Asthma is a disease of the airways in which several cytokines such as interleukin (IL)-4, IL-5, IL-13 and tumor necrosis factor-alpha (TNFalpha) play a major role in the development and progression of inflammation, airway hyperresponsiveness, mucus production, and airway remodeling. The conventional anti-inflammatory therapies, represented by inhaled corticosteroids and antileukotrienes, are not always able to provide optimal disease control and it is therefore hoped that cytokine antagonists could achieve this goal in such situations. Anticytokine therapies have been tested in preclinical studies and some have entered clinical trials. Anti-IL-4 therapies have been tested in animal models of allergy-related asthma, but because of unclear efficacy their development was discontinued. However, IL-4/IL-13 dual antagonists and IL-13-specific blocking agents are more promising, as they exhibit more sustained anti-inflammatory effects. IL-5 antagonists have been found to be of limited efficacy in clinical studies but might be useful in conditions characterized by severe hypereosinophilia, and in which asthma is one of the disease manifestations. Unlike other chronic inflammatory conditions, such as rheumatoid arthritis, the use of anti-TNFalpha therapies in asthma might be limited by the unfavorable risk/benefit ratio associated with long-term use. The identification of so-called asthma TNFalpha phenotypes and perhaps the use of a less aggressive treatment regimen might address this important aspect. Other cytokine antagonists (for example for IL-9 or IL-25) are currently being evaluated in the asthma setting, and could open new therapeutic perspectives based on their efficacy and safety.

Importance of cytokines in murine allergic airway disease and human asthma

Asthma is a common, disabling inflammatory respiratory disease that has increased in frequency and severity in developed nations. We review studies of murine allergic airway disease (MAAD) and human asthma that evaluate the importance of Th2 cytokines, Th2 response-promoting cytokines, IL-17, and proinflammatory and anti-inflammatory cytokines in MAAD and human asthma. We discuss murine studies that directly stimulate airways with specific cytokines or delete, inactivate, neutralize, or block specific cytokines or their receptors, as well as controversial issues including the roles of IL-5, IL-17, and IL-13Ralpha2 in MAAD and IL-4Ralpha expression by specific cell types. Studies of human asthmatic cytokine gene and protein expression, linkage of cytokine polymorphisms to asthma, cytokine responses to allergen stimulation, and clinical responses to cytokine antagonists are discussed as well. Results of these analyses establish the importance of specific cytokines in MAAD and human asthma and have therapeutic implications.