Eosinophilic Airway Inflammation Research Articles

Long-Term Exposure to Nitrogen Dioxide and Ozone and Respiratory Health in Children.

Further evaluation of the impact of long-term exposure to the gaseous air pollutants nitrogen dioxide (NO2) and ozone (O3) on child lung function, and of NO2 or O3 on eosinophilic airway inflammation, is needed. To determine whether NO2 and O3 are associated with lung function and FeNO in children. We measured lung function (FEV1 and FVC) at mid-childhood (mean age 7.9 years, n=703), early teens (13.2 years, n=976), and mid-teen (17.6 years, n=624) study visits, and fractional exhaled nitric oxide (FeNO) at the early and mid-teen study visits in Project Viva, a cohort of mother-child pairs in the Boston, MA area. Long-term exposure to NO2 and O3 was estimated at home address using geospatial models. We examined associations of home address NO2 and O3 exposure and proximity to roadway with lung function and FeNO using linear regression models, adjusting for age, sex, height, weight, season, relative humidity, temperature, parental smoking, and measures of socioeconomic status. We examined for effect modification of the mid-teen associations by blood eosinophil level, physical activity, aeroallergen sensitization, and parental atopy. Median exposure to NO2 was 33.1 ppb (interquartile range [IQR] 10.4 ppb) and to O3 was 35.3 ppb (IQR 3.4) in the first year of life. Exposure to NO2 was associated with lower FEV1 and FVC across all age groups and exposure time intervals: e.g. an IQR increment of NO2 exposure from birth through the early teen visit was associated with 189.9 mL lower FEV1 (95% CI -273.3, -106.5) at the mid-teen visit. Lifetime NO2 exposure at was associated with higher FeNO at the early teen visit: e.g. 16.2% higher FeNO [95% CI 7.1-26.4%) per IQR of lifetime NO2 through the early teen visit. O3 exposure was not associated with lung function or FeNO. Aeroallergen sensitization (measured in a subset of participants) modified associations of NO2 and O3 with FeNO. Exposure to NO2 was associated with lower lung function and higher FeNO among generally healthy children and teenagers. As NO2 exposure levels were within the annual EPA standard, these findings suggest a need to reduce exposure to this pollutant to optimize child respiratory health.

Examining the effect of salbutamol use in ozone air pollution by people with exercise-induced bronchoconstriction.

Previous studies based on animal models have raised concerns about salbutamol use in ozone air pollution with regard to ozone related lung injury. We conducted a double-blind, randomized, placebo-controlled crossover study including 18 subjects diagnosed with EIB by a eucapnic voluntary hyperpnea (EVH) test. Participants completed 30 min of standardized moderate to vigorous exercise in four conditions: ozone plus salbutamol; room air plus salbutamol; ozone plus placebo medication; and room air plus placebo medication. Spirometry, fraction of exhaled nitric oxide, and symptoms were measured before, immediately after, 30 min after and 1 h after exercise. Measurements between the four conditions were compared using percent change from pre to post exercise. There was a statistically significant difference between the salbutamol and placebo medication groups for spirometric variables including FEV1 (Estimate = 6.3, 95% CI: 4.23-8.37, p < 0.001). No differences were observed between ozone and room air exposures. There were no significant differences in FeNO response between experimental conditions. We found that salbutamol improved pulmonary function in individuals with EIB when exercising in ozone and did not increase eosinophilic airway inflammation as indicated by FeNO. This evidence suggests that it is safe for people with EIB to continue to use salbutamol as proscribed when ozone levels are elevated.

Enhanced immunomodulatory properties of ovalbumin through transglutaminase and tyrosinase/caffeic acid-catalyzed crosslinking plus galactomannan conjugation alleviates allergic asthma

Ovalbumin (OVA) is the primary allergenic protein, associated with T helper 2 (Th2)-mediated allergy reactions. Here, we studied OVA’s conformational structure, digestibility, and allergenic potency upon galactomannan (Man) conjugation along with transglutaminase-catalyzed crosslinking (TG-Man/OVA) and tyrosinase/caffeic acid-catalyzed crosslinking (Tyr-Man/OVA). Enzymatic glycosylation altered OVA’s conformation and enhanced the gastrointestinal digestibility. Stimulation of bone marrow-derived dendritic cells (BMDCs) with enzymatically glycosylated OVA reduced the expression of CD40, CD80, CD86 and MHC class II molecules. Furthermore, glycosylated OVA increased IL-10 production while suppressing proinflammatory cytokine production in BMDCs. In an OVA-induced mouse asthma model, TG-Man/OVA and Tyr-Man/OVA upregulated IFN-γ and IL-10 expression and downregulated IL-4, IL-5, and IL-13 in lungs. Crosslinked OVA diminished infiltrated cells in bronchoalveolar lavage fluid and lung and attenuated eosinophilic airway inflammation. These findings offer valuable insights into the development of a novel product with improved hypoallergenic and immunomodulatory properties and hold promise in attenuating allergic diseases.

Expression of Epithelial Alarmin Receptor on Innate Lymphoid Cells Type 2 in Eosinophilic Chronic Obstructive Pulmonary Disease.

Studies have shown that eosinophilic COPD (eCOPD) is a distinct phenotype of the disease. It is well established that innate lymphoid cells are involved in the development of eosinophilic inflammation. Interleukin(IL)-25, thymic stromal lymphopoietin (TSLP) and IL-33 are a group of cytokines produced by epithelium in response to danger signals, e.g., cigarette smoke, and potent activators of ILC2s. In the present study, we examined circulating and sputum ILC2 numbers and expression of intracellular IL-5 as well as receptors for TSLP, IL-33 and IL-25 by ILC2s in non-atopic COPD patients with and without (neCOPD) airway eosinophilic inflammation and healthy smokers. In addition, we examined the association between ILC2s and clinical indicators of COPD burden (i.e., symptom intensity and risk of exacerbations). ILC2s were enumerated in peripheral blood and induced sputum by means of flow cytometry. We noted significantly greater numbers of airway IL-5+ILC2s and TSLPR+ILC2s in eCOPD compared with neCOPD (p < 0.05 and p < 0.01, respectively) and HSs (p < 0.001 for both). In addition, we showed that IL-5+ILC2s, IL-17RB+ILC2s and ST2+ILC2s are significantly increased in the sputum of eCOPD patients compared with HSs. In all COPD patients, sputum ILC2s positively correlated with sputum eosinophil percentage (r = 0.48, p = 0.002). We did not find any significant correlations between sputum ILC2s and dyspnea intensity as measured by the modified Medical Research Council scale (mMRC) and symptom intensity measured by the COPD Assessment Test (CAT). These results suggest the involvement of epithelial alarmin-activated ILC2s in the pathobiology of eosinophilic COPD.

(FEV3-FEV1)/FVC: a terminal-airflow variable for airway hyperresponsiveness and inflammation prediction in patients with symptoms despite preserved spirometry

BackgroundSmall-airway function assessment is crucial for asthma diagnosis and management. Abnormalities in terminal airflow deserve attention. ObjectiveThis study investigated whether the ratio of forced expiratory volume in the second and third seconds to forced vital capacity ([FEV3-FEV1]/FVC) correlates with airway hyperresponsiveness (AHR) and inflammation in patients with preserved spirometry. MethodsThis cross-sectional study enrolled patients with FEV1 ≥ 80% predicted, FEV1/FVC ≥ 0.7, and recurring asthma-like symptoms. Data included demographics, fractional exhaled nitric oxide (FeNO), impulse oscillometry, and spirometry. Univariate and combined models predicting AHR was analyzed in 553 patients and validated in 561. Correlations between sputum inflammation and spirometrics were also assessed. ResultsAHR+ patients exhibited higher (FEV3-FEV1)/FVC ratios compared to AHR-. This ratio showed the strongest association with the methacholine dose causing a 20% FEV1 decrease (PD20) and the response dose ratio (RDR)(r = -0.26 and 0.39, respectively; P < .001, both). The area under the receiver operating characteristic curve for AHR diagnosis using (FEV3-FEV1)/FVC was 0.751, increasing to 0.821 when combined with FeNO, confirmed in the validation cohort. (FEV3-FEV1)/FVC was superior to maximal expiratory flow at 50% of forced vital capacity for identifying eosinophilic airway inflammation characterized by elevated FeNO levels. It correlated better with sputum eosinophil count than with the other spirometrics. ConclusionElevated (FEV3-FEV1)/FVC were evident in AHR+ patients with preserved FEV1/FVC ratios. It serves as a sensitive marker of AHR and airway inflammation correlating with RDR, PD20, and sputum eosinophils, suggesting its utility in monitoring patients at risk for uncontrolled asthma.

Pulmonary Administration of TLR2/6 Agonist after Allergic Sensitization Inhibits Airway Hyper-Responsiveness and Recruits Natural Killer Cells in Lung Parenchyma.

Asthma is a chronic lung disease with persistent airway inflammation, bronchial hyper-reactivity, mucus overproduction, and airway remodeling. Antagonizing T2 responses by triggering the immune system with microbial components such as Toll-like receptors (TLRs) has been suggested as a therapeutic concept for allergic asthma. The aim of this study was to evaluate the effect of a TLR2/6 agonist, FSL-1 (Pam2CGDPKHPKSF), administered by intranasal instillation after an allergic airway reaction was established in the ovalbumin (OVA) mouse model and to analyze the role of natural killer (NK) cells in this effect. We showed that FSL-1 decreased established OVA-induced airway hyper-responsiveness and eosinophilic inflammation but did not reduce the T2 or T17 response. FSL-1 increased the recruitment and activation of NK cells in the lung parenchyma and modified the repartition of NK cell subsets in lung compartments. Finally, the transfer or depletion of NK cells did not modify airway hyper-responsiveness and eosinophilia after OVA and/or FSL-1 treatment. Thus, the administration of FSL-1 reduces airway hyper-responsiveness and bronchoalveolar lavage eosinophilia. However, despite modifications of their functions following OVA sensitization, NK cells play no role in OVA-induced asthma and its inhibition by FSL-1. Therefore, the significance of NK cell functions and localization in the airways remains to be unraveled in asthma.

Serum Galectin-10: A biomarker for persistent airflow limitation in adult asthmatics

BackgroundInhaled corticosteroids (ICS) are primary anti-inflammatory medications to control eosinophilic airway inflammation, and prevent asthma exacerbation. However, persistent airflow limitation (PAL) presents in some asthmatics even on ICS treatment, leading to lung function decline. Thus, we evaluated clinical associations of serum galectin-10 (Gal10) and galectin-3 (Gal3) levels in adult asthmatics who had maintained anti-asthma medication. MethodsSixty-seven asthmatics and 78 healthy controls (HCs) were recruited. Serum Gal10 and Gal3 levels were measured by enzyme-linked immunosorbent assay, and their clinical relevance with inflammatory and lung function parameters was evaluated. Spirometry was performed to assess PAL and small airway dysfunction (SAD). Airway epithelial cells were cocultured with eosinophils/neutrophils, and were exposed to house dust mites to assess the production of Gal10 and Gal3. ResultsSerum Gal10 (not Gal3) levels were significantly higher in asthmatics than in HCs (P < 0.001), in asthmatics with PAL than in those without PAL (P = 0.005), and in those with SAD than in those without SAD (P = 0.004). The Gal10-high group had significantly higher levels of peripheral CD66+ neutrophil counts, serum periostin and Gal3, and lower values of FEV1% and MMEF% than the Gal10-low group (P < 0.050 for all). The production of Gal10 and Gal3 was increased in eosinophilic airway model, while Gal10 (not Gal3) levels were increased in neutrophilic airway model as well as house dust mite stimulation. ConclusionOur findings suggest that serum Gal10 level may be a potential biomarker for PAL in adult asthmatics.

Breath and Sputum Analyses in Asthmatic Patients: An Overview.

Recent advancements in asthma management include non-invasive methodologies such as sputum analysis, exhaled breath condensate (EBC), and fractional exhaled nitric oxide (FeNO). These techniques offer a means to assess airway inflammation, a critical feature of asthma, without invasive procedures. Sputum analysis provides detailed insights into airway inflammation patterns and cellular composition, guiding personalized treatment strategies. EBC collection, reflecting bronchoalveolar lining fluid composition, provides a non-invasive window into airway physiology. FeNO emerges as a pivotal biomarker, offering insights into eosinophilic airway inflammation and aiding in asthma diagnosis, treatment monitoring, and the prediction of exacerbation risks. Despite inherent limitations, each method offers valuable tools for a more comprehensive assessment of asthma. Combining these techniques with traditional methods like spirometry may lead to more personalized treatment plans and improved patient outcomes. Future research is crucial to refine protocols, validate biomarkers, and establish comprehensive guidelines in order to enhance asthma management with tailored therapeutic strategies and improved patient outcomes.

Itaconate suppresses house dust mite-induced allergic airways disease and Th2 cell differentiation

Itaconate was initially identified as an antimicrobial compound produced by myeloid cells. Beyond its antimicrobial role, itaconate may also serve as a crucial metabolic and immune modulator. We therefore examined the roles of aconitate decarboxylase 1 (Acod1) and itaconate in house dust mite (HDM)-sensitized and −challenged mice, a model of T helper 2 (Th2)-driven allergic airways disease. HDM treatment induced lung Acod1 mRNA expression and bronchoalveolar lavage (BAL) itaconate levels in wild-type C57BL/6 mice. Acod1 knockout mice (Acod1-KO) with negligible BAL itaconate showed heightened HDM-induced type 2 cytokine expression, increased serum IgE, and enhanced recruitment of Th2 cells in the lung, indicating a shift towards a more pronounced Th2 immune response. Acod1-KO mice also showed increased eosinophilic airway inflammation and hyperresponsiveness. Experiments in chimeric mice demonstrated that bone marrow from Acod1-KO mice is sufficient to increase type 2 cytokine expression in wild-type mice, and that restitution of bone marrow from wild type mice attenuates mRNA expression of Th2 cytokines in Acod1-KO mice. Specific deletion of Acod1 in lysozyme-secreting macrophages (LysM-cre+Acod1flox/flox) recapitulated the exaggerated phenotype observed in whole-body Acod1-KO mice. Adoptive transfer of Acod1-KO bone marrow-derived macrophages also increased lung mRNA expression of Th2 cytokines. In addition, treatment of Th2-polarized CD4 cells with itaconate impeded Th2 cell differentiation, as shown by reduced expression of Gata3 and decreased release of IL-5 and IL-13. Finally, public datasets of human samples show lower Acod1 expression in subjects with allergic asthma, consistent with a protective role of itaconate in asthma pathogenesis. Together, these data suggest that itaconate plays a protective, immunomodulatory role in limiting airway type 2 inflammation after allergen challenge by attenuating T cell responses.

Association between specific IgE to staphylococcal enterotoxin B and the eosinophilic phenotype of asthma.

Sensitization to staphylococcal superantigens (SAgs) could contribute to asthma severity. However, its relevance with eosinophilic phenotype has not yet been clarified. This study aimed to investigate associations between serum specific IgE levels to SAg and eosinophilic airway inflammation in adult asthmatics. The serum specific IgE levels to 3 SAgs, including staphylococcal enterotoxin A (SEA) and B (SEB), and toxic shock syndrome toxin-1 (TSST-1) were measured by ImmunoCAP in 230 adult asthmatic patients and 50 healthy controls (HCs). Clinical characteristics and laboratory parameters, including serum total/free IgE, and 2 eosinophil-activation markers, eosinophil cationic protein (ECP), and eosinophil-derived neurotoxin (EDN), were analyzed according to blood eosinophil counts (BEC; 150 cells/μL) and serum specific IgE levels to 3 SAgs (0.35 kU/L). Asthmatic patients showed higher serum specific IgE levels to 3 SAgs than HCs (p < 0.05 for all). The serum total/clinfree IgE levels were significantly higher in asthmatics with positive IgE responses to 3 SAgs than those without (p < 0.05 for all). There were no significant differences in clinical parameters including age, asthma severity, comorbidities, or smoking according to IgE responses to 3 SAgs. Patients with positive IgE responses to SEB (not to SEA/TSST-1) had higher serum specific IgE levels to house dust mites and ECP/EDN as well as higher BEC with positive correlations between serum SEB-specific IgE levels and BEC/ECP/EDN (p < 0.05 for all). These findings suggest that serum SEB-specific IgE levels could contribute to eosinophil activation as well as IgE production in adult asthma.

Impact of Ongoing Treatment With Inhaled Corticosteroids During Specific Inhalation Challenges for Diagnosing Occupational Asthma

BackgroundSpecific inhalation challenge tests (SIC) are still the reference test for diagnosing sensitizer-induced occupational asthma (SIOA). The European Respiratory Society recommends the cessation of inhaled corticosteroids (ICS) 72h prior to SIC. ObjectiveTo assess the effect of an ongoing ICS treatment during SIC on the maximum fall in FEV1, change in methacholine PC20 as well as sputum eosinophil counts after exposure to the suspected agent. MethodsWe performed a retrospective analysis using a database of cases referred to our center for suspected SIOA from 1999 to 2022. The results of the SIC were compared between subjects treated with ICS during SIC and steroid-naïve subjects. ResultsSix-hundred and seventy-one individuals underwent SIC in the laboratory. Three hundred and eighteen were treated with ICS, whereas 353 were steroid naïve. The proportion of subjects with a positive SIC was greater among ICS treated subjects (39. 6%) compared to steroid-naïve subjects (27.5%, p<0.001). A treatment with ICS did not influence the outcome of the SIC. There was no difference in the change in PC20 or percentage of sputum eosinophils after SIC between steroid-treated and steroid-naïve subjects. ConclusionAn ongoing ICS treatment during a SIC did not affect the occurrence of an asthmatic reaction, the change in airway responsiveness or eosinophilic inflammation after exposure to the suspected agent in subjects who have been treated with ICS for a long period of time.

Association between PM2.5 from a coal mine fire and FeNO concentration 7.5 years later

Background and aimThere are few long-term studies of respiratory health effects of landscape fires, despite increasing frequency and intensity due to climate change. We investigated the association between exposure to coal mine fire PM2.5 and fractional exhaled nitric oxide (FeNO) concentration 7.5 years later.MethodsAdult residents of Morwell, who were exposed to the 2014 Hazelwood mine fire over 6 weeks, and unexposed residents of Sale, participated in the Hazelwood Health Study Respiratory Stream in 2021, including measurements of FeNO concentration, a marker of eosinophilic airway inflammation. Individual exposure to coal mine fire PM2.5 was modelled and mapped to time-location diaries. The effect of exposure to PM2.5 on log-transformed FeNO in exhaled breath was investigated using multivariate linear regression models in the entire sample and stratified by potentially vulnerable subgroups.ResultsA total of 326 adults (mean age: 57 years) had FeNO measured. The median FeNO level (interquartile range [IQR]) was 17.5 [15.0] ppb, and individual daily exposure to coal mine fire PM2.5 was 7.2 [13.8] µg/m3. We did not identify evidence of association between coal mine fire PM2.5 exposure and FeNO in the general adult sample, nor in various potentially vulnerable subgroups. The point estimates were consistently close to zero in the total sample and subgroups.ConclusionDespite previous short-term impacts on FeNO and respiratory health outcomes in the medium term, we found no evidence that PM2.5 from the Hazelwood coal mine fire was associated with any long-term impact on eosinophilic airway inflammation measured by FeNO levels.

Chronic obstructive pulmonary disease (COPD): eosinophilia and novel drug therapies

The phenotyping of chronic obstructive pulmonary disease (COPD) has increasingly gained attention in recent years, as it leads to new and individualized therapeutic concepts. The aim is to provide an overview of the heterogeneity of COPD and to summarize current drug therapy concepts, particularly in the context of eosinophilic airway inflammation. Several prospective, randomized, placebo-controlled studies have shown areduction in exacerbations and overall mortality with inhaled triple therapy using an inhaled corticosteroid and dual bronchodilation. The higher the eosinophils in the blood, the greater the expected effect. In addition, areduction in exacerbations with biologics in COPD with eosinophilia has been demonstrated for dupilumab. Eosinophil-guided therapy for acute exacerbations is the subject of current research. For COPD without exacerbations, dual bronchodilation forms the basis of inhaled therapy. With exacerbations, inhaled triple therapy is indicated for patients with ablood eosinophil count of ≥ 300/µl. This type of treatment may also be useful when eosinophils are between 100 and 300/µl. Therapy with dupilumab is apossible option for the eosinophilic phenotype in the near future.

Discovery and Validation of a Volatile Signature of Eosinophilic Airway Inflammation in Asthma.

Volatile organic compounds (VOCs) in asthmatic breath may be associated with sputum eosinophilia. We developed a volatile biomarker-signature to predict sputum eosinophilia in asthma. VOCs emitted into the space above sputum samples (headspace) from severe asthmatics (n=36) were collected onto sorbent tubes and analysed using thermal desorption gas chromatography-mass spectrometry (TD-GC-MS). Elastic net regression identified stable VOCs associated with sputum eosinophilia ≥3% and generated a volatile biomarker signature. This VOC signature was validated in breath samples from: (I) acute asthmatics according to blood eosinophilia ≥0.3x109cells/L or sputum eosinophilia of ≥ 3% in the UK EMBER consortium (n=65) and U-BIOPRED-IMI consortium (n=42). Breath samples were collected onto sorbent tubes (EMBER) or Tedlar bags (U-BIOPRED) and analysed by gas-chromatography-mass spectrometry (GC×GC-MS -EMBER or GC-MS -U-BIOPRED). The in vitro headspace identified 19 VOCs associated with sputum eosinophilia and the derived VOC signature yielded good diagnostic accuracy for sputum eosinophilia ≥ 3% in headspace (AUROC (95% CI) 0.90(0.80-0.99), p<0.0001), correlated inversely with sputum eosinophil % (rs= -0.71, p<0.0001) and outperformed FeNO (AUROC (95% CI) 0.61(0.35-0.86). Analysis of exhaled breath in replication cohorts yielded a VOC signature AUROC (95% CI) for acute asthma exacerbations of 0.89(0.76-1.0) (EMBER cohort) with sputum eosinophilia and 0.90(0.75-1.0) in U-BIOPRED - again outperforming FeNO in U-BIOPRED 0.62 (0.33-0.90). We have discovered and provided early-stage clinical validation of a volatile biomarker signature associated with eosinophilic airway inflammation. Further work is needed to translate our discovery using point of care clinical sensors.

Correlation of fractional exhaled nitric oxide (FeNO) and clinical outcomes in patients with chronic obstructive pulmonary disease: A prospective cohort study

BackgroundFractional exhaled nitric oxide (FeNO) is an acceptable and noninvasive marker for defining eosinophilic airway inflammation. Further study is necessary to clarify the role of FeNO in patients with chronic obstructive pulmonary disease (COPD). This study aimed to determine the association between FeNO levels and clinical outcomes. MethodsA prospective observational study was conducted at Songklanagarind Hospital from October 2020 to November 2022. FeNO testing and spirometry were performed at the initial visit and 12-month follow-up. Exacerbation, hospitalization, lung function decline, and all-cause mortality were analyzed to determine the association between FeNO levels and clinical outcomes. ResultsA total of 60 patients with COPD were enrolled, 88.3 % of whom were male, with a mean age of 71.3 ± 9.5 years. There were 18 patients (30 %) in the high FeNO group (≥25 ppb) and 42 patients (70 %) in the low (<25 ppb) FeNO group. The mean blood eosinophil count (BEC) was significantly higher in the high FeNO group (p < 0.001). After a 12-month follow-up period, high FeNO group had higher exacerbation events (HR of 1.26, 95 % confidence interval (CI), 1.10–1.97, p= 0.025). Hospitalization and mortality rates were significantly higher in the high FeNO group. Regardless of the inhaled corticosteroids used, patients with high BEC and FeNO levels tended to have a greater risk of exacerbation. ConclusionIn patients with COPD, FeNO levels are strongly correlated with BEC. Poor clinical outcomes were reported in patients with high FeNO levels. FeNO may be a useful biomarker for predicting clinical outcomes in patients with COPD.

Comparing the Efficacy of Inhaled Corticosteroid (ICS) Treatment in COPD Patients Based on Blood Eosinophilia: A Clinical Trial Study

Background: Inhaled corticosteroids (ICSs) have been widely used in the maintenance therapy of chronic obstructive pulmonary disease (COPD). Eosinophilic airway inflammation is a recognized inflammatory endotype in COPD. Nevertheless, the benefits and risks of ICS treatment remain controversial. Objectives: Therefore, in this study, we determine the frequency of eosinophilia in COPD patients and compare the effects of ICSs in patients with and without eosinophilia referring to the lung clinics of Zahedan University of Medical Sciences. Methods: In this study, 58 COPD patients were examined. Peripheral blood smears (PBS) were collected from all patients, and they were randomly divided into 2 groups. First, a 6-minute walking test (6MWT) was performed on all patients. Thereafter, two groups of patients received standard treatment with the Symbicort spray for 3 months. They were followed for this period, and the 6MWT was performed again at the end of the 3 months. Results: The mean results of the 6MWT test before and after intervention in the eosinophilia-positive group were 164.02 meters and 192.11 meters, respectively. Therefore, there was a significant difference in patient activity levels before and after ICSs (P = 0.017). In the eosinophilia-negative group, there was a significant difference in patient activity levels based on the 6MWT test before and after taking ICSs (P &lt; 0.001). However, there was no difference in activity levels between the two groups before and after the intervention (P = 0.68 and P = 0.36). Conclusions: Our finding showed that treatment with inhaled β2-agonists plus corticosteroids did not affect the response to this treatment in subjects' groups with and without eosinophilia compared to the pre-treatment conditions.

The Possible Roles of IL-4/IL-13 in the Development of Eosinophil-Predominant Severe Asthma.

Bronchial asthma is characterized by airway inflammation, airway hyperresponsiveness, and reversible airway obstruction. Eosinophils contribute to the pathogenesis of airway disease mainly by releasing eosinophil-specific granules, lipid mediators, superoxide anions, and their DNA. Type-2 cytokines such as interleukin (IL)-4 and IL-13 also play roles in the development of bronchial asthma. Among these cytokines, IL-4 is involved in T-cell differentiation, B-cell activation, B-cell differentiation into plasma cells, and the production of immunoglobulin E. Although IL-13 has similar effects to IL-4, IL-13 mainly affects structural cells, such as epithelial cells, smooth muscle cells, and fibroblasts. IL-13 induces the differentiation of goblet cells that produce mucus and induces the airway remodeling, including smooth muscle hypertrophy. IL-4 and IL-13 do not directly activate the effector functions of eosinophils; however, they can induce eosinophilic airway inflammation by upregulating the expression of vascular cell adhesion molecule-1 (for adhesion) and CC chemokine receptor 3 ligands (for migration). Dupilumab, a human anti-IL-4 receptor α monoclonal antibody that inhibits IL-4 and IL-13 signaling, decreases asthma exacerbations and mucus plugs and increases lung function in moderate to severe asthma. In addition, dupilumab is effective for chronic rhinosinusitis with nasal polyps and for atopic dermatitis, and IL-4/IL-13 blocking is expected to suppress allergen sensitization, including transcutaneous sensitization and atopic march.

Utility of eosinophil peroxidase as a biomarker of eosinophilic inflammation in asthma

The relative utility of eosinophil peroxidase (EPX) and blood and sputum eosinophil counts as disease biomarkers in asthma is uncertain. We sought to determine the utility of EPX as a biomarker of systemic and airway eosinophilic inflammation in asthma. EPX protein was measured by immunoassay in serum and sputum in 110 healthy controls to establish a normal reference range and in repeated samples of serum and sputum collected during 3 years of observation in 480 participants in the Severe Asthma Research Program 3. Over 3 years, EPX levels in patients with asthma were higher than normal in 27% to 31% of serum samples and 36% to 53% of sputum samples. Eosinophils and EPX correlated better in blood than in sputum (rs values of 0.74 and 0.43, respectively), and high sputum EPX levels occurred in 27% of participants with blood eosinophil counts less than 150 cells/μL and 42% of participants with blood eosinophil counts between 150 and 299 cells/μL. Patients with persistently high sputum EPX values for 3 years were characterized by severe airflow obstruction, frequent exacerbations, and high mucus plug scores. In 59 patients with asthma who started mepolizumab during observation, serum EPX levels normalized in 96% but sputum EPX normalized in only 49%. Lung function remained abnormal even when sputum EPX normalized. Serum EPX is a valid protein biomarker of systemic eosinophilic inflammation in asthma, and sputum EPX levels are a more sensitive biomarker of airway eosinophilic inflammation than sputum eosinophil counts. Eosinophil measures in blood frequently miss airway eosinophilic inflammation, and mepolizumab frequently fails to normalize airway eosinophilic inflammation even though it invariably normalizes systemic eosinophilic inflammation.

Single-Cell Analysis Uncovers Striking Cellular Heterogeneity of Lung-Infiltrating Regulatory T Cells during Eosinophilic versus Neutrophilic Allergic Airway Inflammation.

Allergic airway inflammation results from uncontrolled immune responses to environmental Ags. Although it is well established that allergic immune responses exhibit a high degree of diversity, driven by primary effector cell types such as eosinophils, neutrophils, or CD4 T cells with distinct effector signatures, the mechanisms responsible for such pathogenesis remain elusive. Foxp3+ regulatory T cells (Tregs) are essential immune regulators during chronic inflammation, including allergic airway inflammation. Emerging evidence suggests that Tregs infiltrating inflamed tissues exhibit distinct phenotypes dependent on the specific tissue sites and can display heterogeneity and tissue residency. Whether diverse allergic airway inflammatory responses influence infiltrating Treg heterogeneity or Treg lung residency has not been explored. We employed an unbiased single-cell RNA sequencing approach to investigate lung-infiltrating Tregs in models of eosinophilic and neutrophilic airway inflammation. We found that lung-infiltrating Tregs are highly heterogeneous, and that Tregs displaying lung-resident phenotypes are significantly different depending on the types of inflammation. Treg expression of ST2, a receptor for alarmin IL-33, was predominantly associated with eosinophilic inflammation and tissue residency. Nevertheless, Treg-specific ST2 deficiency did not affect the development of eosinophilic allergic inflammation or the generation of lung-resident Tregs. These results uncover a stark heterogeneity among Tregs infiltrating the lungs during allergic airway inflammation. The results indicate that varying types of inflammation may give rise to phenotypically distinct lung-resident Tregs, underscoring a (to our knowledge) novel mechanism by which inflammatory cues may shape the composition of infiltrating Tregs, allowing them to regulate inflammatory responses through tissue-adapted mechanisms.

The Fractional exhaled Nitric Oxide (FeNO)- test as add-on test in the diagnostic work-up of asthma: a study protocol.

Asthma is a common disease characterized by chronic inflammation of the lower airways, bronchial hyperactivity, and (reversible) airway obstruction. The Global Initiative of Asthma Guideline recommends a flowchart to diagnose asthma with first-step spirometry with reversibility and a bronchial challenge test (BPT) with histamine or methacholine as a second step [1]. The BPT is considered burdensome, time-consuming for patients and staff, can cause side effects, and is expensive. In addition, this test strongly encumbers lung function capacity. Elevated Nitric Oxide (NO) is associated with airway eosinophilic inflammation in asthma patients and can be measured in exhaled air with the Fractional exhaled (Fe) NO-test. This low-burden FeNO-test could be used as an 'add-on' test in asthma diagnostics [2, 3]. This multi-center prospective study (Trial number: NCT06230458) compares the 'standard asthma diagnostic work-up' (spirometry with reversibility and BPT) to the 'new asthma diagnostics work-up' (FeNO-test as an intermediate step between the spirometry with reversibility and the BPT), intending to determine the impact of the FeNO-based strategy, in terms of the number of avoided BPTs, cost-effectiveness and reduced burden to the patient and health care. The cost reduction of incorporating the FeNO-test in the new diagnostic algorithm will be established by the number of theoretically avoided BPT. The decrease in burden will be studied by calculating differences in the Visual Analogue Scale (VAS) -score and Asthma Quality of Life Questionnaire (AQLQ) -score after the BPT and FeNO-test with an independent T-test. The accuracy of the FeNO-test will be calculated by comparing the FeNO-test outcomes to the (gold standard) BPTs outcomes in terms of sensitivity and specificity. The intention is to include 171 patients. The local medical ethics committee approved the proposed study and is considered a low-burden and risk-low study. The local medical ethics committee registration number: R23.005. Strengths: This is the first study that investigates the value of the FeNO-test (cut off ≥ 50 ppb) as an add-on test, to determine the impact of the FeNO-based strategy, in terms of the number of avoided BPTs, cost-effectiveness, and reduced burden on the patient and health care. High FeNO levels may also be observed in other diseases such as eosinophilic chronic bronchitis and allergic rhinitis. The FeNO-test can be used to rule in a diagnosis of asthma with confidence, however, due to the poor sensitivity it is not suitable to rule out asthma.