Importance of concomitant local and systemic eosinophilia in uncontrolled asthma

Eosinophil-mucus interplay in severe asthma: Implications for treatment with biologicals

Airway mucus is a hydrogel with unique biophysical properties due to its primary water composition and a small proportion of large anionic glycoproteins or mucins. The predominant mucins in human mucus, MUC5AC and MUC5B, are secreted by specialized cells within the airway epithelium both in normal conditions and in response to various stimuli. Their relative proportions are correlated with specific inflammatory responses and disease mechanisms. The dysregulation of mucin expression is implicated in numerous respiratory diseases, including asthma, COPD, and cystic fibrosis, where the pathogenic role of mucus has been extensively described yet often overlooked. In airway diseases, excessive mucus production or impaired mucus clearance leads to mucus plugging, with secondary airway occlusion that contribute to airflow obstruction, asthma severity and poor control. Eosinophils and Charcot Leyden crystals in sputum contribute to the mucus burden and tenacity. Mucin may also contribute to eosinophil survival. Other mechanisms, including eosinophil-independent IL-13 release, mast-cell activation and non-type-2 (T2) cytokines, are also likely to participate in mucus pathobiology. An accurate assessment of mucus and its clinical and functional consequences require a thorough approach that includes evaluation of cellular predominance in sputum, airway cytokines and other inflammatory markers, mucus characteristics and composition and structural and functional impact measured by advanced lung imaging. This review, illustrated with clinical scenarios, provides an overview of current methods to assess mucus and its relevance to the choice of biologics to treat patients with severe asthma.

Airway and Systemic Immunoglobulin Profiling and Immune Response in Adult Asthma

INTRODUCTION

Immunoglobulins play a vital role in host immune response and in the pathogenesis of conditions like asthma. Therapeutic agents such as monoclonal antibodies target specific elements of the asthmatic inflammatory cascade. Decisions to utilize these medications are often based on systemic inflammatory profiling without direct insight into the airway inflammatory profile. We sought to investigate the relationship between immunoglobulin and cytokine profiles in the airway and systemic immune compartments of adult asthmatics.

METHODS

Blood sampling and bronchoscopy with bronchoalveolar lavage (BAL) were performed in 76 well-defined adult asthmatics. Antibody and cytokine profiles were measured in both BAL and serum using ELISA and quantibody arrays.

RESULTS

There was no relationship between BAL and serum levels of IgE. This is of significance in an asthma population. For some analytes, correlation analysis was significant (P < 0.05) indicating representativeness of our cohort and experimental setup in those cases. Nevertheless, the predictive power (r2) of the BAL-to-serum comparisons was mostly low except for TNF-α (r2 = 0.73) when assuming a simple (linear) relationship.

CONCLUSION

This study highlights the importance of sample site when investigating the roles of immunoglobulins and cytokines in disease pathogenesis and suggests that both localized and systemic immune responses are at play. The prescription of asthma monoclonal therapy is generally based on systemic evaluation of cytokine and immunoglobulin levels. Our research suggests that this approach may not fully reflect the pathophysiology of the disease and may provide insight into why some patients respond to these targeted therapies while others do not.

Sensitization with Fungal Protease Allergen Establishes Long-Lived, Allergenic Th Cell Memory in the Lung

Allergic asthma is a chronic inflammatory disease that affects millions of individuals worldwide. Exposure to allergens produced by a variety of otherwise harmless microbes, including fungi, predisposes individuals to immunopathologic disease upon subsequent encounters with allergen. We developed a mouse model that employs a purified protease produced by Aspergillus (Asp f 13) to investigate the contributions of CD4+ Th cells to recurrent lung inflammation. Notably, memory CD4+ T cells enhanced the eosinophil response of sensitized/rechallenged animals. In addition, memory CD4+ T cells maintained allergenic features, including expression of GATA-binding protein 3 and IL-5. Th2 memory T cells persisted in the peribronchiolar interstitium of the lung and expressed markers of tissue residence, such as CD69, CCR8, and IL-33R. Lastly, we identified a peptide epitope contained within Asp f 13 and generated a peptide-MHC class II tetramer. Using these tools, we further demonstrated the durability and exquisite sensitivity of memory T cells in promoting lung eosinophilia. Our data highlight important features of memory T cells that strengthen the notion that memory T cells are principal drivers of eosinophilic disease in murine models of allergic sensitization and episodic airway inflammation.

Phenotyping of Severe Asthma in the Era of Broad-Acting Anti-Asthma Biologics

Severe asthma is associated with significant morbidity and mortality despite the maximal use of inhaled corticosteroids and additional controller medications, and has a high economic burden. Biologic therapies are recommended for the management of severe, uncontrolled asthma to help to prevent exacerbations and to improve symptoms and health-related quality of life. The effective management of severe asthma requires consideration of clinical heterogeneity that is driven by varying clinical and inflammatory phenotypes, which are reflective of distinct underlying disease mechanisms. Phenotyping patients using a combination of clinical characteristics such as the age of onset or comorbidities and biomarker profiles, including blood eosinophil counts and levels of fractional exhaled nitric oxide and serum total immunoglobulin E, is important for the differential diagnosis of asthma. In addition, phenotyping is beneficial for risk assessment, selection of treatment, and monitoring of the treatment response in patients with asthma. This review describes the clinical and inflammatory phenotypes of asthma, provides an overview of biomarkers routinely used in clinical practice and those that have recently been explored for phenotyping, and aims to assess the value of phenotyping in severe asthma management in the current era of biologics.

Blood CD62Llow inflammatory eosinophils are related to the severity of asthma and reduced by mepolizumab

BACKGROUND

Eosinophils have been divided into different subpopulations with distinct phenotypes based on CD62L expression. No data are available regarding the correlation between eosinophils subphenotypes and clinical severity of asthma, as well as the effect of anti-IL-5 therapy on these cells. The study investigates the correlation between blood CD62Llow inflammatory eosinophils (iEos) and clinical severity of severe eosinophilic asthma (SEA) and evaluates the impact of mepolizumab on iEos.

METHODS

112 patients were screened and were divided in two groups: biological-naive (n = 51) and biological-treated patients (n = 61). The Biological-naive patients were analyzed before treatment (Group A) and 19 out of 51 patients, were longitudinally analyzed before and after treatment with mepolizumab 100 mg s.c/4 weeks (Group B); 32 patients were excluded because they were being treated with other biological therapies. Blood eosinophils were analyzed by FACS and correlated with clinical scores. In vitro effect of IL-5 and mepolizumab on CD62L expression was assessed.

RESULTS

A significant correlation between blood CD62Llow cells and clinical scores of asthma and nasal polyps, as well as the number of asthma exacerbations in the last year was shown in untreated patients. In longitudinally studied patients we observed a marked reduction of CD62Llow cells paralleled by an increase in the proportion of CD62Lbright cells, associated with clinical improvement of asthma control. In vitro, CD62L expression on eosinophils is modulated by IL-5 and anti-IL-5.

CONCLUSION

A positive correlation between CD62Llow iEos and the baseline clinical features of SEA with CRSwNP was shown. Furthermore mepolizumab restores the healthy balance among eosinophils sub-phenotypes in SEA patients.

Super-responders to anti-IL-5/anti-IL-5R are characterised by high sputum eosinophil counts at baseline

Several clinical trials have demonstrated that anti-IL-5(R) biologics were able to improve lung function, asthma control and chronic oral corticosteroid exposure and reduce exacerbations among eosinophilic asthmatic patients. However, a certain variability in clinical responses to anti-IL-5(R) biologics was brought to light. Our study aimed at evaluating the role of baseline sputum eosinophils in identifying super-responders to mepolizumab and benralizumab. Our study reinforces the importance to examine sputum eosinophils in patients suffering from severe asthma before starting a biologic as it is associated with the intensity of response to mepolizumab and benralizumab.

Upper airway disease diagnosis as a predictive biomarker of therapeutic response to biologics in severe asthma

Asthma is a heterogeneous disease sharing airway instability but with different biology, risk factors, and response-to-therapy patterns. Biologics have revolutionized the one-size-fits-to-all approach to personalized medicine in severe asthma (SA), which relies on the identification of biomarkers that define distinct endotypes. Thus, blood eosinophils and, to some extent, exhaled nitric oxide (FeNO) can predict the response to approved anti-type 2 (T2) biologics (anti-IgE, anti-IL-5, and anti-IL-4R alpha), whereas age at onset and comorbidities such as anxiety/depression, obesity, reflux, and upper airway disease (UAD) also influence therapeutic responses in SA. In this article, focusing on the predictive value of biomarkers for the therapeutic response to biologics in SA, we first summarize the level of prediction achieved by T2 biomarkers (blood eosinophils, FeNO) and then review whether data support the predictive value of upper airway diagnosis on such outcomes. Post hoc analysis of most studies with T2 biologics suggests that chronic rhinosinusitis with nasal polyps (CRSwNP) and, to a lower extent, allergic rhinitis may help in predicting clinical response. Considering that T2 biologics are now also approved for the treatment of severe CRSwNP, diagnosis of upper airway disease is a key step in determining eligibility for such therapy.

Prevalence of eosinophilic, atopic, and overlap phenotypes among patients with severe asthma in Saudi Arabia: a cross-sectional study

Background

Eosinophilia is a significant factor in asthma severity; however, the prevalence of severe eosinophilic asthma in Saudi Arabia is largely unknown. We aimed to determine the prevalence of the eosinophilic (defined in this study as ≥ 300 cells/mm³ in blood), atopic (atopic phenotype 1, defined in this study as > 100 IU/mL total serum IgE; atopic phenotype 2, defined in this study as > 150 IU/mL), and overlap phenotypes among patients with severe asthma in Saudi Arabia.

Methods

A cross-sectional study was conducted in centers specialized in severe asthma management. Patients aged ≥ 12 years with severe asthma were enrolled. Study patients responded to the Global Initiative for Asthma 2018 assessment of asthma control questionnaire and provided study investigators with current information related to the study objectives. Additional medical record data and a blood sample for total serum IgE and complete blood count were collected.

Results

A total of 101 patients were enrolled; 83% were female and the mean (standard deviation) age was 48.7 (13.2) years. Forty-five (45%) patients had the eosinophilic phenotype, 50 (50%) had atopic phenotype 1, and 25 (25%) had phenotypic overlap (eosinophilic and atopic 1). Forty-one (41%) patients had atopic phenotype 2 and 23 (23%) had phenotypic overlap (eosinophilic and atopic 2). Asthma control and oral corticosteroid use patterns were similar and there were no significant differences in number of asthma exacerbations across phenotypes.

Conclusions

In Saudi Arabia, 45% of patients with severe asthma had the eosinophilic phenotype, which is most likely an underestimation as no clinical features of eosinophilia were taken into account in the definition of eosinophilia. Approximately half of them had phenotypic overlap with the atopic phenotype.

Trial registration NCT03931954; ClinicalTrials.gov, April 30, 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01856-9.

Sputum IL-25, IL-33 and TSLP, IL-23 and IL-36 in airway obstructive diseases. Reduced levels of IL-36 in eosinophilic phenotype

INTRODUCTION

Alarmins ((IL-25, IL-33 and thymic stromal lymphopoietin (TSLP)) are known to promote Th2 inflammation and could be associated with eosinophilic airway infiltration. They may also play a role in airway remodeling in chronic airway obstructive diseases such as asthma and chronic obstructive pulmonary disease (COPD). IL-23 and IL-36 were shown to mediate the neutrophilic airway inflammation as seen in chronic airway obstructive diseases.

OBJECTIVES

The purpose of this project was to determine the expression and the production of these cytokines from induced sputum (IS) in patients with chronic airway obstructive diseases including asthmatics and COPD. The relationship of the mediators with sputum inflammatory cellular profile and the severity of airway obstruction was assessed.

METHODS

The alarmins (IL-25, IL-33 and TSLP) as well as IL-23 and IL-36 concentrations were measured in IS from 24 asthmatics and 20 COPD patients compared to 25 healthy volunteers. The cytokines were assessed by ELISA in the IS supernatant and by RT-qPCR in the IS cells.

RESULTS

At protein level, no difference was observed between controls and patients suffering from airway obstructive diseases regarding the different mediators. IL-36 protein level was negatively correlated with sputum eosinophil and appeared significantly decreased in patients with an eosinophilic airway inflammation compared to those with a neutrophilic profile and controls. At gene level, only IL-36, IL-23 and TSLP were measurable but none differed between controls and patients with airway obstructive diseases. IL-36 and IL-23 were significantly increased in patients with an neutrophilic inflammatory profile compared to those with an eosinophilic inflammation and were correlated with sputum neutrophil proportions. None of the mediators were linked to airway obstruction.

CONCLUSIONS

The main finding of our study is that patients with eosinophilic airway inflammation exhibited a reduced IL-36 level which could make them more susceptible to airway infections as IL-36 is implicated in antimicrobial defense. This study showed also an implication of IL-36 and IL-23 in airway neutrophilic inflammation in chronic airway obstructive diseases.

Biomarkers of Type 2 Airway Inflammation as Predictors of Loss of Asthma Control During Step-Down Therapy for Well-Controlled Disease: The Long-Acting Beta-Agonist Step-Down Study (LASST)

BACKGROUND

Biomarkers that can predict loss of asthma control among patients being considered for step-down therapy in well-controlled disease are lacking.

OBJECTIVE

To evaluate whether baseline biomarkers of type 2 airway inflammation and/or serial measurement of fractional exhaled nitric oxide (Feno) predict loss of asthma control as therapy is stepped down.

METHODS

In subanalyses of a multicenter randomized, double-blind, parallel 3-arm trial comparing strategies for step-down therapy in well-controlled asthma (Long-Acting Beta-Agonist Step-Down Study), we assessed whether baseline atopy as determined by serum aeroallergen allergy screening test (Phadiatop), baseline serum eosinophil peroxidase, or baseline or serial Feno measurements during follow-up predicted the time to loss of asthma control among participants. Loss of asthma control was defined in the study protocol. We analyzed these associations in adjusted models including all participants, after testing for interactions with assignment to each of the 3 treatment groups (continuation of stable dose of combination inhaled corticosteroid-long-acting beta-agonist, step-down of inhaled corticosteroid, or discontinuation of long-acting bronchodilator).

RESULTS

Four hundred forty-seven of the 553 Long-Acting Beta-Agonist Step-Down Study participants who were randomized to 1 of 3 treatment arms and had at least 1 biomarker measurement were included in this analysis. At baseline, higher levels of Feno were significantly associated with greater levels of multiallergen IgE levels (P < .001), but not with serum eosinophil peroxidase (P = .742). Among all participants as a group, elevations in baseline biomarkers were not predictive of a higher risk of treatment failure. In addition, Feno levels measured serially at 6-week intervals demonstrated that compared with participants with low levels (<25 parts per billion), those with intermediate (25-50 parts per billion) and high (>50 parts per billion) levels did not have significantly increased likelihood of subsequent treatment failure (hazard ratios, 1.03 [95% CI, 0.59-1.78] and 1.29 [95% CI, 0.65-2.54], respectively). There were no significant interactions of treatment group and baseline biomarkers.

CONCLUSIONS

In patients with well-controlled asthma, neither baseline levels of type 2 airway inflammatory biomarkers nor serial measures of Feno are strong predictors of treatment failure.

A randomized multicenter study evaluating Xolair persistence of response after long-term therapy

BACKGROUND

Few data are available to assist clinicians with decisions regarding long-term use of asthma therapies, including omalizumab.

OBJECTIVE

We sought to evaluate the benefit and persistence of response in subjects continuing or withdrawing from long-term omalizumab treatment.

METHODS

Evaluating the Xolair Persistency Of Response After Long-Term Therapy (XPORT) was a randomized, double-blind, placebo-controlled withdrawal study that included subjects with moderate-to-severe persistent asthma receiving long-term omalizumab. Subjects were randomized by using a hierarchical dynamic randomization scheme to continue their same dose of omalizumab or withdraw to placebo and were then followed every 4 weeks for 1 year. The primary outcome was any protocol-defined severe asthma exacerbation. The secondary outcome was time to first protocol-defined severe asthma exacerbation. Exploratory outcomes included changes in Asthma Control Questionnaire and Asthma Control Test scores.

RESULTS

Significantly more subjects in the omalizumab group (67%) had no protocol-defined exacerbation than in the placebo group (47.7%); an absolute difference of 19.3% (95% CI, 5.0%, 33.6%) represents a 40.1% relative difference. Time to first protocol-defined exacerbation analysis revealed a significantly different between-group exacerbation pattern that was consistent with the primary analysis. Subjects continuing omalizumab had significantly better asthma control (mean [SD] change from baseline to week 52: Asthma Control Test score, -1.16 [4.14] vs placebo, -2.88 [5.38], P = .0188; Asthma Control Questionnaire score, 0.22 [0.66] vs placebo, 0.63 [1.13], P = .0039). Discontinuation of omalizumab was associated with an increase in free IgE levels and an increase in basophil expression of the high-affinity IgE receptor. No safety concerns were noted.

CONCLUSION

Continuation of omalizumab after long-term treatment results in continued benefit, as evidenced by improved symptom control and reduced exacerbation risk.

Clinical asthma phenotypes in the real world: opportunities and challenges

Asthma is a common, chronic and heterogeneous syndrome, affecting people of all ages, all races and both sexes. It may range from mild disease with barely noticeable symptoms, to very severe disease with constant symptoms that greatly hinder the life of the patient. Guidelines issued by various medical societies provide guidance on how to diagnose and manage asthmatic patients. It is now increasingly recognised that asthma management must be individualised, tailored not only to the severity of the disease but to the phenotypic characteristics of each patient. The aim of asthma treatment is control of asthma and the prevention of risk of exacerbations and fixed airflow limitation. Asthma control can be easily assessed clinically through simple screening tools such as the use of validated questionnaires and spirometry. The use of inflammatory biomarkers can be an alternative approach that, however, requires more time and resources. Asthma treatment involves the use of controllers, mainly inhaled corticosteroids and long-acting β2-agonists, and relievers, mainly rapid-acting β2-agonists. Controller medications reduce airway inflammation, lead to better symptom control and reduce the risk of future exacerbations. Reliever (rescue) medications alleviate symptoms and prevent exercise-induced bronchoconstriction. Treatment must be based on a "stepwise approach" in order to achieve good control of symptoms and to minimise future risks of exacerbations. That is, less treatment for mild disease, more treatment for severe, uncontrolled disease. Once good asthma control has been achieved and maintained, treatment should be stepped down. In severe asthmatics, phenotypic characterisation becomes more clinically useful and add-on treatment such as anti-immunoglobulin E monoclonal antibodies may be required. Despite our better understanding of asthma, there are still patients who will not respond to treatment and remain symptomatic. Dissemination of guidelines and national plans allowing early diagnosis of asthma as well as access to specialised primary and secondary care for asthmatic patients, personalised treatment and continuity of care may lead to excellence in care and controlled asthma for the majority of patients. Education of the patient in asthma is also very important, as in every chronic disease, as the patients live with the disease every day while they visit a healthcare professional a few times a year. Future planning for new treatments should focus on the needs of such severe asthma patients.