Perspectives on exhaled nitric oxide

Biologics in T2 Severe Asthma: Unveiling Different Effectiveness by Real-World Indirect Comparison

Background: Indirect comparison among biologics in severe asthma (SA) is a challenging but desirable goal for clinicians in real life. The aim of the study is to define characteristics of a biologic-treated T2-driven-SA population and to evaluate the effectiveness of biologic treatments in a real-world setting by variation in intra/inter-biologic parameters in an up to 4-year follow-up. Methods: Demographic, clinical, functional, and biological characteristics were evaluated retrospectively in 104 patients recruited until July 2022 at baseline (T0) and over a maximum of 4 years (T4) of biologic therapy (omalizumab/OmaG = 41, from T0 to T4, mepolizumab/MepoG = 26, from T0 to T4, benralizumab/BenraG = 18, from T0 to T2, and dupilumab/DupiG = 19, from T0 to T1). Variations of parameters using means of paired Delta were assessed. Results: At baseline, patients had high prevalence of T2-driven comorbidities, low asthma control test (ACT mean 17.65 ± 4.41), impaired pulmonary function (FEV1 65 ± 18 %pred), frequent exacerbations/year (AEs 3.5 ± 3), and OCS dependence (60%). DupiG had lower T2 biomarkers/comorbidities and AEs, and worse FEV1 (57 ± 19 %pred) compared to other biologics (p < 0.05). All biologics improved ACT, FEV1%, FVC%, AEs rate, and OCS use. FEV1% improved in MepoG and BenraG over the minimal clinically important difference and was sustained over 4 years in OmaG and MepoG. A significant RV reduction in OmaG (T4) and DupiG (T1), and BenraG normalization (T2) of airflow limitation were found. We observed through inter-biologic parameters pair delta variation comparison a significant nocturnal awakenings reduction in BenraG vs. OmaG/MepoG, and neutrophils reduction in BenraG/DupiG vs. OmaG. Conclusions: Indirect comparison among biologics unveils clinical and functional improvements that may mark a different effectiveness. These results may highlight the preference of a single biologic compared to another with regard to specific treatable traits.

Type 2 severe asthma: pathophysiology and treatment with biologics

INTRODUCTION

The hallmark of most patients with severe asthma is type 2 inflammation, driven by innate and adaptive immune responses leading to either allergic or non-allergic eosinophilic infiltration of airways. The cellular and molecular pathways underlying severe type 2 asthma can be successfully targeted by specific monoclonal antibodies.

AREAS COVERED

This review article provides a concise overview of the pathophysiology of type 2 asthma, followed by an updated appraisal of the mechanisms of action and therapeutic efficacy of currently available biologic treatments used for management of severe type 2 asthma. Therefore, all reported information arises from a wide literature search performed on PubMed.

EXPERT OPINION

The main result of the recent advances in the field of anti-asthma biologic therapies is the implementation of a personalized medicine approach, aimed to achieve clinical remission of severe asthma. Today this accomplishment is made possible by the right choice of the most beneficial biologic drug for the pathologic traits characterizing each patient, including type 2 severe asthma and its comorbidities.

Fractional nitric oxide measurement in exhaled air (FeNO): perspectives in the management of respiratory diseases

Exhaled nitric oxide (NO) production, upregulated by inflammatory cytokines and mediators in central and peripheral airways, can be easily and non-invasively detected in exhaled air in asthma and other respiratory conditions as a promising tool for disease monitoring. The American Thoracic Society and European Respiratory Society released recommendations that standardize the measurement of the fractional exhaled NO (FeNO). In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways and, as a biomarker of T2 inflammation can be used to identify asthma T2 phenotype. In this setting its measurement has shown to be an important tool especially in the diagnostic process, in the assessment and evaluation of poor adherence or predicting positive response to inhaled corticosteroids treatment, in phenotyping severe asthma patients and as a biomarker to predict the response to biologic treatments. The discovery of the role of NO in the pathogenesis of different diseases affecting the airways and the possibility to estimate the predominant site of increased NO production has provided new insight on its regulatory role in the airways, making it suitable for a potential extended use in clinical practice for different pulmonary diseases, even though its role remains less clear than in asthma. Monitoring FeNO in pulmonary obstructive lung diseases including chronic bronchitis and emphysema, interstitial lung diseases, obstructive sleep apnea and other pulmonary diseases is still under debate but has opened up a window to the role NO may play in the management of these diseases. The use of FeNO is reliable, cost effective and recommendable in both adults and children, and should be implemented in the management of patients with asthma and other respiratory conditions.

Phenotype overlap in the natural history of asthma

The heterogeneity of asthma makes it challenging to unravel the pathophysiologic mechanisms of the disease. Despite the wealth of research identifying diverse phenotypes, many gaps still remain in our knowledge of the disease's complexity. A crucial aspect is the impact of airborne factors over a lifetime, which often results in a complex overlap of phenotypes associated with type 2 (T2), non-T2 and mixed inflammation. Evidence now shows overlaps between the phenotypes associated with T2, non-T2 and mixed T2/non-T2 inflammation. These interconnections could be induced by different determinants such as recurrent infections, environmental factors, T-helper plasticity and comorbidities, collectively resulting in a complex network of distinct pathways generally considered as mutually exclusive. In this scenario, we need to abandon the concept of asthma as a disease characterised by distinct traits grouped into static segregated categories. It is now evident that there are multiple interplays between the various physiologic, cellular and molecular features of asthma, and the overlap of phenotypes cannot be ignored.

Switching Biological Therapies in Severe Asthma

Currently, three classes of monoclonal antibodies targeting type 2 inflammation pathways are available in Italy for the treatment of severe asthma: anti-IgE (Omalizumab), anti-IL-5/anti-IL-5Rα (Mepolizumab and Benralizumab), and anti-IL-4Rα (Dupilumab). Numerous randomized controlled trials (RCTs) and real-life studies have been conducted to define their efficacy and identify baseline patients' characteristics potentially predictive of favorable outcomes. Switching to another monoclonal antibody is recommended in case of a lack of benefits. The aim of this work is to review the current knowledge on the impact of switching biological therapies in severe asthma as well as on predictors of treatment response or failure. Almost all of the information about switching from a previous monoclonal antibody to another comes from a real-life setting. In the available studies, the most frequent initial biologic was Omalizumab and patients who were switched because of suboptimal control with a previous biologic therapy were more likely to have a higher baseline blood eosinophil count and exacerbation rate despite OCS dependence. The choice of the most suitable treatment may be guided by the patient's clinical history, biomarkers of endotype (mainly blood eosinophils and FeNO), and comorbidities (especially nasal polyposis). Due to overlapping eligibility, larger investigations characterizing the clinical profile of patients benefiting from switching to different monoclonal antibodies are needed.

Biological Therapy of Severe Asthma with Dupilumab, a Dual Receptor Antagonist of Interleukins 4 and 13

Interleukin-4 (IL-4) and interleukin-13 (IL-13) are key cytokines involved in the pathophysiology of both immune-inflammatory and structural changes underlying type 2 asthma. IL-4 plays a pivotal role in Th2 cell polarization, immunoglobulin E (IgE) synthesis and eosinophil recruitment into the airways. IL-13 synergizes with IL-4 in inducing IgE production and also promotes nitric oxide (NO) synthesis, eosinophil chemotaxis, bronchial hyperresponsiveness and mucus secretion, as well as the proliferation of airway resident cells such as fibroblasts and smooth muscle cells. The biological effects of IL-4 and IL-13 are mediated by complex signaling mechanisms activated by receptor dimerization triggered by cytokine binding to the α-subunit of the IL-4 receptor (IL-4Rα). The fully human IgG4 monoclonal antibody dupilumab binds to IL-4Rα, thereby preventing its interactions with both IL-4 and IL-13. This mechanism of action makes it possible for dupilumab to effectively inhibit type 2 inflammation, thus significantly reducing the exacerbation of severe asthma, the consumption of oral corticosteroids (OCS) and the levels of fractional exhaled NO (FeNO). Dupilumab has been approved not only for the add-on therapy of severe asthma, but also for the biological treatment of atopic dermatitis and nasal polyposis.

Pulmonary Benefits of Intervention with Air Cleaner among Schoolchildren in Beijing: A Randomized Double-Blind Crossover Study

We conducted a crossover study employing air cleaner intervention among 125 schoolchildren aged 9-12 years in a boarding school in Beijing, China. The PM concentrations were monitored, and 27 biomarkers were analyzed. We used the linear mixed-effects model to evaluate the association of intervention/time-weighted PM concentrations with biomarkers. The outcomes showed that air cleaner intervention was associated with FeNO, exhaled breath condensate (EBC) IL-1β, and IL-6, which decreased by 12.57%, 10.83%, and 4.33%, respectively. Similar results were observed in the associations with PMs. Lag 1 day PMs had the strongest relationship with biomarkers, and significant changes were observed in biomarkers such as FEV₁, FeNO, EBC 8-iso, and MCP-1. Boys showed higher percentage changes than girls, and the related biomarkers were FeNO, EBC 4-HNE, IL-1β, IL-6, and MCP-1. The results showed that biomarkers such as FeNO, EBC IL-6, MCP-1, and 4-HNE could sensitively reflect the early abnormal response of the respiratory system under short-term PM exposure among healthy schoolchildren and indicated that (1) air cleaners exert a protective effect on children's respiratory system. (2) PM had lag and cumulative effect, lag 1 day had the greatest effect. (3) The boys were more sensitive than the girls.

Novel Biological Therapies for Severe Asthma Endotypes

Severe asthma comprises several heterogeneous phenotypes, underpinned by complex pathomechanisms known as endotypes. The latter are driven by intercellular networks mediated by molecular components which can be targeted by specific monoclonal antibodies. With regard to the biological treatments of either allergic or non-allergic eosinophilic type 2 asthma, currently available antibodies are directed against immunoglobulins E (IgE), interleukin-5 (IL-5) and its receptor, the receptors of interleukins-4 (IL-4) and 13 (IL-13), as well as thymic stromal lymphopoietin (TSLP) and other alarmins. Among these therapeutic strategies, the best choice should be made according to the phenotypic/endotypic features of each patient with severe asthma, who can thus respond with significant clinical and functional improvements. Conversely, very poor options so far characterize the experimental pipelines referring to the perspective biological management of non-type 2 severe asthma, which thereby needs to be the focus of future thorough research.

Interleukins 4 and 13 in Asthma: Key Pathophysiologic Cytokines and Druggable Molecular Targets

Interleukins (IL)-4 and -13 play a pivotal role in the pathobiology of type-2 asthma. Indeed, IL-4 is crucially involved in Th2 cell differentiation, immunoglobulin (Ig) class switching and eosinophil trafficking. IL-13 cooperates with IL-4 in promoting IgE synthesis, and also induces nitric oxide (NO) production, goblet cell metaplasia and fibroblast proliferation, as well as elicits contractile responses and hyperplasia of airway smooth muscle cells.

IL-4 and IL-13 share common signaling pathways, activated by the binding of both cytokines to receptor complexes including the α-subunit of the IL-4 receptor (IL-4Rα). Therefore, the subsequent receptor dimerization is responsible for the pathophysiologic effects of IL-4 and IL-13. By selectively blocking IL-4Rα, the fully human IgG4 monoclonal antibody dupilumab behaves as a dual receptor antagonist of both IL-4 and IL-13. Through this mechanism of action, dupilumab exerts effective therapeutic actions in type-2 inflammation, thus decreasing asthma exacerbations, FeNO (fractional exhaled NO) levels, and the intake of oral corticosteroids (OCS). In addition to being approved for the add-on biological therapy of severe asthma, dupilumab has also been licensed for the treatment of nasal polyposis and atopic dermatitis.

Switch from Omalizumab to Benralizumab in Allergic Patients with Severe Eosinophilic Asthma: A Real-Life Experience from Southern Italy

Background. The wide availability of monoclonal antibodies for the add-on therapy of severe asthma currently allows for the personalization of biologic treatment by selecting the most appropriate drug for each patient. However, subjects with overlapping allergic and eosinophilic phenotypes can be often eligible to more than one biologic, so that the first pharmacologic choice can be quite challenging for clinicians. Within such a context, the aim of our real-life investigation was to verify whether allergic patients with severe eosinophilic asthma, not adequately controlled by an initial biologic treatment with omalizumab, could experience better therapeutic results from a pharmacologic shift to benralizumab. Patients and methods. Twenty allergic patients with severe eosinophilic asthma, unsuccessfully treated with omalizumab and then switched to benralizumab, were assessed for at least 1 year in order to detect eventual changes in disease exacerbations, symptom control, oral corticosteroid intake, lung function, and blood eosinophils. Results. In comparison to the previous omalizumab therapy, after 1 year of treatment with benralizumab our patients experienced significant improvements in asthma exacerbation rate (p < 0.01), rescue medication need (p < 0.001), asthma control test (ACT) score (p < 0.05), forced expiratory volume in the first second (FEV₁) (p < 0.05), and blood eosinophil count (p < 0.0001). Furthermore, with respect to the end of omalizumab treatment, the score of sino-nasal outcome test-22 (SNOT-22) significantly decreased after therapy with benralizumab (p < 0.05). Conclusion. The results of this real-life study suggest that the pharmacologic shift from omalizumab to benralizumab can be a valuable therapeutic approach for allergic patients with severe eosinophilic asthma, not adequately controlled by anti-IgE treatment.

Short-Term Evaluation of Dupilumab Effects in Patients with Severe Asthma and Nasal Polyposis

Background

Having been approved for biological treatment of atopic dermatitis, dupilumab has also been recently licensed as add-on therapy for severe asthma and nasal polyposis. With regard to the latter diseases, few real-life clinical investigations have been carried out to date.

Objective

The primary end point of this single-center observational study was to evaluate in a real-life setting the short-term therapeutic effects of dupilumab in patients with severe asthma and nasal polyposis.

Methods

At baseline and after 4 weeks of add-on therapy with dupilumab, several clinical and functional parameters were assessed in 20 patients with severe asthma and nasal polyposis, including both allergic and nonallergic subjects.

Results

After 4 weeks of treatment with dupilumab, all patients experienced remarkable improvement in both severe asthma and nasal polyposis. In particular, asthma-control test and sinonasal outcome test 22 scores had significantly increased (p<0.0001) and decreased (p<0.0001), respectively. Oral corticosteroid intake got to zero within 4 weeks (p<0.0001). Moreover, in week 4, significant increases were detected with regard to both prebronchodilator forced expiratory volume in the first second (p<0.01) and forced vital capacity (FVC; p<0.05). At the same time point, dupilumab had significantly reduced residual volume (p<0.0001) and total lung capacity (p<0.001), whereas it had enhanced forced midexpiratory flow of 25%–75% FVC (p<0.01) and peak expiratory flow (p<0.01). After 4 weeks of treatment, dupilumab had also lowered levels of fractional exhaled nitric oxide (p<0.0001).

Conclusion

The results of this real-life study suggest that dupilumab can be utilized in both allergic and nonallergic patients with severe asthma and nasal polyposis as a valuable add-on biological therapy with rapid onset of action.

Breath Biomarkers in Diagnostic Applications

The detection of chemical compounds in exhaled human breath presents an opportunity to determine physiological state, diagnose disease or assess environmental exposure. Recent advancements in metabolomics research have led to improved capabilities to explore human metabolic profiles in breath. Despite some notable challenges in sampling and analysis, exhaled breath represents a desirable medium for metabolomics applications, foremost due to its non-invasive, convenient and practically limitless availability. Several breath-based tests that target either endogenous or exogenous gas-phase compounds are currently established and are in practical and/or clinical use. This review outlines the concept of breath analysis in the context of these unique tests and their applications. The respective breath biomarkers targeted in each test are discussed in relation to their physiological production in the human body and the development and implementation of the associated tests. The paper concludes with a brief insight into prospective tests and an outlook of the future direction of breath research.

The Role of Dupilumab in Severe Asthma

Dupilumab is a fully humanized monoclonal antibody, capable of inhibiting intracellular signaling of both interleukin (IL)-4 and IL-13. These are two molecules that, together with other proinflammatory cytokines such as IL-5 and eotaxins, play a pivotal role in orchestrating the airway inflammatory response defined as Type 2 (T2) inflammation, driven by Th2 or Type 2 innate lymphoid cells, which is the major feature of the T2 high asthma phenotype. The dual inhibition of IL-4 and IL-13 activities is due to the blockade of type II IL-4 receptor through the binding of dupilumab with the subunit IL-4Rα. This results in the repression of STAT6 and in the suppression of subsequent de novo formation of several molecules involved in the T2 inflammatory signature. Several clinical trials tested the efficacy and safety of dupilumab in large populations of uncontrolled severe asthmatics, revealing significant improvements in lung function, asthma control, and exacerbation rate. Similar results were reported when dupilumab was employed in patients harboring pathogenetic processes related to T2 immune response, such as atopic dermatitis and chronic rhinosinusitis. In this review, we provide an overview of the recent research in the field of respiratory medicine about dupilumab mechanism of action and its effects.

Clinical Characterization of the Frequent Exacerbator Phenotype in Asthma

Background: Asthma exacerbation is episodic worsening of respiratory symptoms in conjunction with the deterioration of lung function, which may occur independently from the asthma severity hampering asthmatics’ quality of life. This study aimed to characterize the patient phenotype more prone to asthma exacerbation (oral corticosteroid burst ≥2 per year) to allow the proper identification of such patients. Methods: This real-life, observational, cross-sectional study evaluated 464 asthmatic patients stratified according to the asthma exacerbations experienced in the previous year. Clinical, functional, and blood parameters were retrieved from chart data and were representative of patients in stable conditions. Results: The frequent asthma exacerbator was more commonly female, suffered from chronic rhinosinusitis with nasal polyposis, had reduced lung function and peripheral oxygen saturation, and had increased daily activity limitations. These patients often had severe asthma and more frequently needed hospitalization in their lives. Furthermore, the frequent asthma exacerbator had higher concentrations of serum immunoglobulin E (IgE) and exhaled nitric oxide with cut-off risk values of 107.5 kU/L (OR = 4.1) and 43.35 ppb (OR = 3.8), respectively. Conclusions: This study illustrates the clinical features of the frequent asthma exacerbator phenotype. Nevertheless, serum IgE and exhaled nitric oxide could allow the identification of this phenotype and the establishment of an appropriate therapeutic approach.

Clinical utility of fractional exhaled nitric oxide in severe asthma management

Asthma is a chronic inflammatory disease of the airways, affecting over 350 million people worldwide and placing a significant burden on healthcare providers and wider society. Approximately 5-10% of asthma patients are diagnosed with severe asthma and typically are associated with increased risk of hospitalisation from exacerbations, increased morbidity, mortality and higher asthma-associated healthcare costs. Nitric oxide (NO) is an important regulator of immune responses and is a product of inflammation in the airways that is over-produced in asthma. Fractional exhaled NO (F _eNO) is predominantly used as a predictor of response to inhaled corticosteroids (ICSs), to monitor adherence and as a diagnostic tool in ICS-naïve patients. In the UK, the National Institute for Health and Care Excellence (NICE) guidelines recommend the use of F _eNO for the initial diagnosis of patients with suspected asthma. In the USA, American Thoracic Society (ATS) guidelines recommend F _eNO as part of the initial diagnosis of asthma and for monitoring of airway inflammation. F _eNO has also been shown to be a predictive factor for asthma exacerbations, with higher levels being associated with a greater number of exacerbations. In addition, higher levels of F _eNO have been shown to be associated with a decline in lung function. F _eNO testing is a cost-effective procedure and has been shown to improve patient management when combined with standard assessment methods. Recent evidence suggests that F _eNO may also be useful as a surrogate biomarker for the assessment and management of severe asthma and to predict responsiveness to some biological therapies.

Inhaled Janus Kinase (JAK) inhibitors for the treatment of asthma

Multiple asthma-relevant cytokines including IL-4, IL-5, IL-13, and TSLP depend upon JAKs for signaling. JAK inhibition may, therefore, offer a novel intervention strategy for patients with disease refractory to current standards of care. Multiple systemically delivered JAK inhibitors have been approved for human use or are under clinical evaluation in autoimmune diseases such as rheumatoid arthritis. However, the on-target side effect profiles of these agents are likely not tolerable for many asthmatic patients. Limiting JAK inhibition to the lung is expected to improve therapeutic index relative to systemic inhibition. Thus, inhaled JAK inhibitors with lung-restricted exposure are of high interest as potential treatments for asthma.

Diagnostic value of fractional exhaled nitric oxide in cough-variant asthma: an updated meta-analysis

Objective: We aimed to evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) in cough-variant asthma (CVA) detection. Methods: Relevant studies on the FeNO test in patients with CVA were retrieved from electronic databases including PubMed, Medline, Springer, Elsevier Science Direct, the Cochrane Library, and Google Scholar, up to August 2018. Meta-analysis for sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) of the FeNO test were conducted after extracting related data from the included studies. Meta-DiSc 1.4 and Stata 12.0 software were applied to perform the meta-analysis. Results: In total, 12 studies involving 1968 participants were selected for the meta-analysis. The pooled results of the FeNO test for CVA diagnosis showed that the sensitivity was 0.74 (95% confidence interval [CI] = 0.70 to 0.77), specificity was 0.82 (95% CI = 0.80 to 0.84), PLR was 4.15 (95% CI = 3.04 to 5.65), NLR was 0.30 (95% CI = 0.22 to 0.41), and DOR was 15.33 (95% CI = 8.43 to 27.86). The area under the curve and Q* index were 0.87 and 0.80, respectively. Moreover, no significant publication bias was observed using Egger's linear regression test (P > 0.05). Conclusion: The FeNO test might be an appropriate diagnostic tool for CVA detection.

Treatment of severe, uncontrolled eosinophilic asthma: Where we are heading

OBJECTIVE

We sought to highlight how our understanding of the pathophysiology of severe asthma has evolved over time and discuss the role of biomarkers in treatment advances and emerging new therapies.

DATA SOURCES

Nonsystematic PubMed literature search.

STUDY SELECTION

Articles were selected based on areas of relevance to the classification of asthma by endotype, with an emphasis on the evolution of current treatment guidelines for severe asthma.

RESULTS

Unlike older guidelines for the treatment of severe asthma, recent updates now distinguish between asthma severity and control. Moreover, asthma classification is shifting from phenotype to endotype with the development of biomarkers used to determine the mechanism driving a patient's disease. Many cases of severe asthma are associated with type-2 inflammation with elevated eosinophil counts in the airways. In recent studies, patients with severe, uncontrolled asthma and high eosinophil counts respond to biologic therapies targeting the type-2 signaling pathway and eosinophils themselves (eg, anti-IL-5 therapy). New treatments that address the pathophysiology of asthma offer a promising alternative to control severe asthma for patients who do not respond to traditional therapies.

CONCLUSION

Understanding and using new treatment guidelines that separate the concepts of asthma severity and control may help clinicians to identify patients with severe, uncontrolled asthma who may benefit from new treatment options, such as anti-IL-5 therapies.

Periostin and Dipeptidyl Peptidase-4: Potential Biomarkers of Interleukin 13 Pathway Activation in Asthma and Allergy

Periostin and dipeptidyl peptidase-4 (DPP-4) are proteins induced by type 2 cytokines interleukin (IL)-4 and IL-13 and show increased expression in asthma and diseases with type 2 inflammation, including atopic dermatitis and chronic rhinosinusitis. Both proteins can also be induced by other stimuli, such as profibrotic factors, which may confound their specificity as biomarkers of IL-13 pathway activation and type 2-driven disease. DPP-4 is important in glucose metabolism; therefore, serum concentrations may be confounded by the presence of concomitant metabolic disease. This review evaluates the potential of these biomarkers for anti-IL-13-directed therapy in asthma and diseases with type 2 inflammation.