Nanosized extracellular vesicles (EVs) are released by all cells to convey cell-to-cell communication. EVs, including exosomes and microvesicles, carry an array of bioactive molecules, such as proteins and RNAs, encapsulated by a membrane lipid bilayer. Epithelial cells, endothelial cells, and various immune cells in the lung contribute to the pool of EVs in the lung microenvironment and carry molecules reflecting their cellular origin. EVs can maintain lung health by regulating immune responses, inducing tissue repair, and maintaining lung homeostasis. They can be detected in lung tissues and biofluids such as bronchoalveolar lavage fluid and blood, offering information about disease processes, and can function as disease biomarkers. Here, we discuss the role of EVs in lung homeostasis and pulmonary diseases such as asthma, chronic obstructive pulmonary disease, cystic fibrosis, pulmonary fibrosis, and lung injury. The mechanistic involvement of EVs in pathogenesis and their potential as disease biomarkers are discussed. Finally, the pulmonary field benefits from EVs as clinical therapeutics in severe pulmonary inflammatory disease, as EVs from mesenchymal stem cells attenuate severe respiratory inflammation in multiple clinical trials. Further, EVs can be engineered to carry therapeutic molecules for enhanced and broadened therapeutic opportunities, such as the anti-inflammatory molecule CD24. Finally, we discuss the emerging opportunity of using different types of EVs for treating severe respiratory conditions.

Semaphorin3E has shown promise in alleviating the severity of asthma in preclinical studies; however, its role in the chronic features of type 2-low asthma remains unclear. Therefore, we aimed to investigate the role of Sema3E in a mouse model of severe asthma that exhibits a mix of granulocytic inflammation with neutrophils dominance and compared the results with those from the type-2 high eosinophilic asthma model. Sema3E knockout (KO) and wild-type (WT) mice were subjected to type-2 low and type-2 high regimens using house dust mite (HDM) combined with cyclic-di-GMP or HDM alone, respectively. Airway hyperresponsiveness parameters were measured using the FlexiVent ventilator. Bronchoalveolar lavage fluid cell phenotyping was performed by flowcytometry. Additionally, cytokines and antibodies were quantified using Mesoscale and ELISA. Mucus overproduction and goblet cell hyperplasia were visualized by Periodic-acid-Schiff staining. In comparison to WT mice, Sema3E KO mice exhibited an enhanced tissue resistance and tissue elastance in the type 2-low asthma model. Concurrently, Sema3E KO mice that were subjected to the type-2 low asthma model demonstrated an elevated presence of pulmonary neutrophils, dendritic cells, CD4 T cells, as well as increased levels of IL-17, TNF, IL-1β, CXCL-8, and MCP-1/CCL2 in comparison to their WT counterparts. However, in the type-2 high model, Sema3E KO mice exhibited a significant increase in goblet cell numbers and mucus overproduction, as well as enhancements in the number of eosinophils, IgE-producing B cells, and IL-4 levels compared to WT mice, highlighting the homeostatic role of Sema3E in the distinct immune niche of type-2 low and type-2 high asthma. Overall, our data showed that Sema3E is critical in modulating AHR, airway inflammation, and tissue remodelling in type 2 low and type 2 high phenotypes of asthma. The Sema3E regulatory network varies depending on the immunization regimen, affecting distinct parameters in type-2 low and type-2 high asthma models.

Our understanding of the airway epithelium's role in driving asthma pathogenesis has evolved over time. From being regarded primarily as a physical barrier that could be damaged via inflammation, the epithelium is now known to actively contribute to asthma development through interactions with the immune system. The airway epithelium contains multiple cell types with specialized functions spanning barrier action, mucociliary clearance, immune cell recruitment, and maintenance of tissue homeostasis. Environmental insults may cause direct or indirect injury to the epithelium leading to impaired barrier function, epithelial remodelling, and increased release of inflammatory mediators. In severe asthma, the epithelial barrier repair process is inhibited and the response to insults is exaggerated, driving downstream inflammation. Genetic and epigenetic mechanisms also maintain dysregulation of the epithelial barrier, adding to disease chronicity. Here, we review the role of the airway epithelium in severe asthma and how targeting the epithelium can contribute to asthma treatment.

Nearly 8% of the U.S. population is diagnosed with asthma, leading to more than 5 million office visits and 1 million emergency department visits annually. Both outpatient and inpatient internal medicine clinicians treat asthma frequently, but nuances in diagnosis and management have emerged. This article highlights many of these developments.

The impact of chronic medical conditions on the developing brain has gained recent attention, but the neurocognitive risks associated with asthma, which has high prevalence in childhood, are still largely unknown. Recent findings have underscored that children with asthma may be at higher risk for developing cognitive difficulties. In this review, we examine the pathophysiology of asthma and its associations with brain and cognitive development based on rodent models and relatively scant research in humans. We also examine risk factors that may exacerbate asthma symptoms and neurocognitive outcomes, and we discuss why children may be particularly vulnerable to asthma-related neurocognitive consequences. We conclude by providing a framework for future research.

The US Food and Drug Administration (FDA) hosted a workshop on February 22, 2024, to discuss the status of biomarkers in drug development for allergic asthma and food allergy. The workshop provided a forum for open discussion among regulators, academicians, National Institutes of Health staff and industry to inform stakeholders of the requirements for the FDA to adopt a biomarker as a surrogate end point for a clinical trial, and to inform FDA of the status of various biomarkers in development. The workshop was divided into 3 sessions: (1) FDA and European Union regulators discussing regulatory perspectives on use of biomarkers in drug development programs, (2) investigators discussing biomarkers for pediatric and adult asthma, and (3) investigators discussing biomarkers for food allergy. In this report, we review the information presented at the workshop and summarize the current status of potential biomarkers for these allergic diseases.

Viral infections constitute a primary trigger for asthma exacerbations. While vaccines protect against viral infections by eliciting a Th1 immune response, the impact of the asthmatic immune milieu which is characterized by Th2 cytokine dominance and elevated IgE levels on post-vaccination antibody production remains elusive. Therefore, vaccination protocols tailored to asthma patients need to be formulated.

The levels of IgG specific for SARS-CoV-2 S protein were measured in the sera of vaccinated and unvaccinated individuals by ELISA. The differences in antibody titers between asthma patients and healthy controls, as well as among distinct asthma subgroups were analyzed.

The vaccinated individuals had significantly elevated serum antibody levels compared to their unvaccinated counterparts. There were no significant differences in the antibody titers of asthma patients and healthy controls after completion of the three-dose vaccination regimen. Furthermore, no discernible variations in antibody titers were detected among the asthma subgroups.

Asthma patients can safely adhere to the same vaccination strategies as the general healthy population, negating the need for any specialized vaccination protocols based solely on the asthmatic immune landscape.

Asthma is a chronic and multifaceted respiratory condition that affects over 300 million individuals across the globe. It is characterized by persistent inflammation of the airways, which leads to episodes of wheezing, breathlessness, chest tightness, and coughing. The most prevalent form of asthma is classified as Type 2 or T2-high asthma. In this variant, the immune response is heavily driven by eosinophils, mast cells, and T-helper 2 (Th2) cells. These components release a cascade of cytokines, including interleukin-4 (IL-4), interleukin-5 (IL-5), and interleukin-13 (IL-13). This release promotes several processes: the production of immunoglobulin E (IgE), which is integral to allergic responses; the recruitment of eosinophils-white blood cells that contribute to inflammation and tissue damage. Conversely, non-Type 2 or T2-low asthma is typically associated with a different inflammatory profile characterized by neutrophilic inflammation. This type of asthma is driven by T-helper 1 (Th1) and T-helper 17 (Th17) immune responses, which are often present in older adults, smokers, and those suffering from more severe manifestations of the disease. Among asthmatic patients, approximately 80-85% of cases are classified as T2-high asthma, while only 15-20% are T2-low asthma. Treatment of asthma focuses heavily on controlling inflammation. Inhaled corticosteroids remain the cornerstone therapy for managing T2-high asthma. For more severe or treatment-resistant cases, biologic therapies targeting specific inflammatory pathways, such as anti-IgE (omalizumab), anti-IL-5 (mepolizumab, benralizumab), and anti-IL-4/IL-13 (dupilumab), have shown great promise. For T2-low asthma, macrolide antibiotics like azithromycin and other novel therapies are being explored. This article reviews the safety, efficacy, and indications of the currently approved biologics and discusses potential novel biologics for asthma.

Hundreds of genetic associations for asthma have been identified, yet translating these findings into mechanistic insights remains challenging. We leveraged plasma proteomics from the UK Biobank Pharma Proteomics Project (UKB-PPP) to identify biomarkers and effectors of asthma risk or heterogeneity using genetic causal inference approaches. We identified 609 proteins associated with asthma status (269 proteins after controlling for body mass index [BMI] and smoking). Analysis of genetically predicted protein levels identified 70 proteins with putative causal roles in asthma risk, including known drug targets and proteins without prior genetic evidence in asthma (e.g., GCHFR, TDRKH, and CLEC7A). The genetic architecture of causally associated proteins provided evidence for a Toll-like receptor (TLR)1-interleukin (IL)-27 asthma axis. Lastly, we identified evidence of causal relationships between proteins and heterogeneous aspects of asthma biology, including between TSPAN8 and neutrophil counts. These findings illustrate that integrating biobank-scale genetics and plasma proteomics can provide a framework to identify therapeutic targets and mechanisms underlying disease risk and heterogeneity.

The objective of this study was to examine the associations of blood inflammatory phenotypes with acute pediatric asthma exacerbations during different seasons and the COVID-19 pandemic.

A retrospective study was conducted involving 32,160 pediatric asthma patients from January 2008 to December 2021. Asthma blood inflammatory phenotypes were categorized based on low (L) and high (H) eosinophils (E) and neutrophils (N) (LBE/HBE: ≥ 0.25 × 109/L and LBN/HBN: ≥ 5 × 109/L, respectively) and logistic regression was used to examine the odds ratio (OR) of outcome variables.

A 109/L increase of neutrophils and eosinophils was associated with a 1.015-fold (95% CI: 1.009-1.021) and a 1.057-fold increase in the OR (95% CI: 1.026-1.088) for asthma exacerbations of hospitalized pediatric asthma patients. An increase in HBE/LBN phenotype was associated with a respective 1.232-fold (95% CI: 1.081-1.404) and 1.248-fold (95% CI: 1.101-1.414) increase in the OR for asthma exacerbations of hospitalized pediatric asthma patients before the COVID-19 pandemic in the winter and autumn seasons. However, an increase of LBE/LBN phenotype was associated with a respective 0.873-fold (95% CI: 0.769-0.991), 0.872-fold (95% CI: 0.771-0.986), and 0.813-fold (95% CI: 0.709-0.932) decrease in the OR for asthma exacerbations in the winter, spring and summer seasons.

HBE/LBN phenotype had a higher risk of asthma exacerbations among hospitalized pediatric asthma patients in the winter and autumn, while LBE/LBN phenotype had a lower risk in the winter, spring, and summer.

Blood eosinophils and neutrophils have been indicated to have a potential influence on pediatric asthma development and severity. HBE/LBN phenotype was associated with increased asthma exacerbations among hospitalized pediatric asthma patients during winter and autumn. Eosinophil and neutrophil predominance exhibited a higher influence on pediatric asthma exacerbations.

The use of long-acting muscarinic antagonists (LAMA) in asthma is supported by their mechanism of action and evidence of drug synergy with inhaled corticosteroids ± long-acting β-agonists. This review discusses the scientific rationale, clinical data, and recommendations for the use of LAMA in the asthma therapeutic strategy. Adding a LAMA to a dual therapy with an inhaled corticosteroid and long-acting β-agonist has been shown to reduce exacerbations, increase asthma control, and improve quality of life, with a good safety profile. In addition, using a single inhaler device containing multiple drugs enhances patients' adherence to therapy. Some predictive factors of the efficacy of this triple therapy have been suggested in the literature: patients with a history of at least one exacerbation within the past 12 months, male patients, those younger than 65 years, and non-smokers have been reported to have a greater improvement from baseline forced expiratory volume in 1 second (FEV1) compared with patients without these characteristics, while patients with high bronchial hyperresponsiveness and persistent airway limitations (PAL) seem to show better gains in the exacerbation rate. However, eosinophil levels do not seem to predict the efficacy of LAMA. The role and long-term benefits of LAMA combined with biologic therapy in severe asthma remain uncertain, with more clinical data needed.

Patients with severe asthma may demonstrate reduced sensitivity to steroid treatment. However, the implications of this reduced responsiveness for clinical outcomes and the underlying mechanisms remain unclear.

The aim of this study was to investigate whether steroid sensitivity in patients with asthma is related to severity and clinical outcomes and to elucidate the role of inflammatory pathways in reducing steroid sensitivity.

This observational study of 169 asthma patients, with 161 followed for 1 year, involved isolation of peripheral blood mononuclear cells. These cells were treated with dexamethasone, and the mRNA expression of FKBP5, which is a marker of steroid sensitivity, was measured. To explore the mechanism underlying the reduced steroid sensitivity, cells were exposed to PI3K and MAPK inhibitors in combination with dexamethasone.

A total of 53 patients diagnosed with severe asthma exhibited markedly diminished sensitivity to steroids compared with those with nonsevere asthma. Reduced steroid sensitivity has emerged as a critical risk factor for failure to experience clinical remission and exacerbation. This relationship between reduced steroid sensitivity and disease severity and adverse outcomes was confirmed at the 1-year follow-up. Mechanistic investigations revealed that the degree of recovery from steroid sensitivity after PI3Kδ/γ inhibitor treatment was significantly greater in patients with severe asthma than in those with nonsevere asthma, a finding confirmed at the 1-year follow-up.

Patients with severe asthma demonstrate reduced steroid sensitivity, which results in unfavorable clinical outcomes. Conversely, inhibition of the PI3K pathway significantly improves steroid sensitivity.

Type 2-mediated immune responses protect the body against environmental threats at barrier surfaces, such as large parasites and environmental toxins, and facilitate the repair of inflammatory tissue damage. However, maladaptive responses to typically nonpathogenic substances, commonly known as allergens, can lead to the development of allergic diseases. Type 2 immunity involves a series of prototype TH2 cytokines (IL-4, IL-5, IL-13) and alarmins (IL-33, TSLP) that promote the generation of adaptive CD4+ helper Type 2 cells and humoral products such as allergen-specific IgE. Mast cells and basophils are integral players in this network, serving as primary effectors of IgE-mediated responses. These cells bind IgE via high-affinity IgE receptors (FcεRI) expressed on their surface and, upon activation by allergens, release a variety of mediators that regulate tissue responses, attract and modulate other inflammatory cells, and contribute to tissue repair. Here, we review the biology and effector mechanisms of these cells, focusing primarily on their role in mediating IgE responses in both physiological and pathological contexts.

Cyclic nucleotides are synthesized by adenylyl and/or guanylyl cyclase, and downstream of this synthesis, the cyclic nucleotide phosphodiesterase families (PDEs) specifically hydrolyze cyclic nucleotides. PDEs control cyclic adenosine-3',5'monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) intracellular levels by mediating their quick return to the basal steady state levels. This often takes place in subcellular nanodomains. Thus, PDEs govern short-term protein phosphorylation, long-term protein expression, and even epigenetic mechanisms by modulating cyclic nucleotide levels. Consequently, their involvement in both health and disease is extensively investigated. PDE inhibition has emerged as a promising clinical intervention method, with ongoing developments aiming to enhance its efficacy and applicability. In this comprehensive review, we extensively look into the intricate landscape of PDEs biochemistry, exploring their diverse roles in various tissues. Furthermore, we outline the underlying mechanisms of PDEs in different pathophysiological conditions. Additionally, we review the application of PDE inhibition in related diseases, shedding light on current advancements and future prospects for clinical intervention. SIGNIFICANCE STATEMENT: Regulating PDEs is a critical checkpoint for numerous (patho)physiological conditions. However, despite the development of several PDE inhibitors aimed at controlling overactivated PDEs, their applicability in clinical settings poses challenges. In this context, our focus is on pharmacodynamics and the structure activity of PDEs, aiming to illustrate how selectivity and efficacy can be optimized. Additionally, this review points to current preclinical and clinical evidence that depicts various optimization efforts and indications.

Aberrant immune response is a hallmark of asthma, with 5%-10% of patients suffering from severe disease exhibiting poor response to standard treatment. A better understanding of the immune responses contributing to disease heterogeneity is critical for improving asthma management. T cells are major players in the orchestration of asthma, in both mild and severe disease, but it is unclear whether specific T cell subsets influence asthma symptom duration. Here we show a significant association of airway CD8+ effector memory T cells re-expressing CD45RA (TEMRAs), but not CD8+CD45RO+ or tissue-resident memory T cells, with asthma duration in patients with severe asthma (SA) but not mild to moderate asthma (MMA). Higher frequencies of IFN-γ+CD8+ TEMRAs compared with IFN-γ+CD45RO+ T cells were detected in SA airways, and the TEMRAs from patients with SA but not MMA proliferated ex vivo, although both expressed cellular senescence-associated biomarkers. Prompted by the transcriptomic profile of SA CD8+ TEMRAs and proliferative response to IL-15, airway IL15 expression was higher in patients with SA compared with MMA. Additionally, IL15 expression in asthmatic airways negatively correlated with lung function. Our findings add what we believe is a new dimension to understanding asthma heterogeneity, identifying IL-15 as a potential target for treatment.

Asthma is a chronic respiratory disorder affecting individuals across all age groups. It is characterized by airway inflammation and remodeling and leads to progressive airflow restriction. While corticosteroids remain a mainstay therapy, their efficacy is limited in severe asthma due to genetic and epigenetic alterations, as well as elevated pro-inflammatory cytokines interleukin-4 (IL-4), interleukin-13 (IL-13), and interleukin-5 (IL-5), which drive structural airway changes including subepithelial fibrosis, smooth muscle hypertrophy, and goblet cell hyperplasia. This underscores the critical need for biologically targeted therapies. This review systematically examines the roles of IL-4 and IL-13, key drivers of type-2 inflammation, in airway remodeling and their potential as therapeutic targets. IL-4 orchestrates eosinophil recruitment, immunoglobulin class switching, and Th2 differentiation, whereas IL-13 directly modulates structural cells, including fibroblasts and epithelial cells, to promote mucus hypersecretion and extracellular matrix (ECM) deposition. Despite shared signaling pathways, IL-13 emerges as the dominant cytokine in remodeling processes including mucus hypersecretion, fibrosis and smooth muscle hypertrophy. While IL-4 primarily amplifies inflammatory cascades by driving IgE switching, promoting Th2 cell polarization that sustain cytokine release, and inducing chemokines to recruit eosinophils. In steroid-resistant severe asthma, biologics targeting IL-4/IL-13 show promise in reducing exacerbations and eosinophilic inflammation. However, their capacity to reverse established remodeling remains inconsistent, as clinical trials prioritize inflammatory biomarkers over long-term structural outcomes. This synthesis highlights critical gaps in understanding the durability of IL-4/IL-13 inhibition on airway structure and advocates for therapies combining biologics with remodeling-specific strategies. Through the integration of mechanistic insights and clinical evidence, this review emphasizes the need for long-term studies utilizing advanced imaging, histopathological techniques, and patient-reported outcomes to evaluate how IL-4/IL-13-targeted therapies alter airway remodeling and symptom burden, thereby informing more effective treatment approaches for severe, steroid-resistant asthma.

Genome-wide association studies (GWAS) have identified hundreds of loci underlying adult-onset asthma (AOA) and childhood-onset asthma (COA). However, the causal variants, regulatory elements, and effector genes at these loci are largely unknown.

We performed heritability enrichment analysis to determine relevant cell types for AOA and COA, respectively. Next, we fine-mapped putative causal variants at AOA and COA loci. To improve the resolution of fine-mapping, we integrated ATAC-seq data in blood and lung cell types to annotate variants in candidate cis-regulatory elements (CREs). We then computationally prioritized candidate CREs underlying asthma risk, experimentally assessed their enhancer activity by massively parallel reporter assay (MPRA) in bronchial epithelial cells (BECs) and further validated a subset by luciferase assays. Combining chromatin interaction data and expression quantitative trait loci, we nominated genes targeted by candidate CREs and prioritized effector genes for AOA and COA.

Heritability enrichment analysis suggested a shared role of immune cells in the development of both AOA and COA while highlighting the distinct contribution of lung structural cells in COA. Functional fine-mapping uncovered 21 and 67 credible sets for AOA and COA, respectively, with only 16% shared between the two. Notably, one-third of the loci contained multiple credible sets. Our CRE prioritization strategy nominated 62 and 169 candidate CREs for AOA and COA, respectively. Over 60% of these candidate CREs showed open chromatin in multiple cell lineages, suggesting their potential pleiotropic effects in different cell types. Furthermore, COA candidate CREs were enriched for enhancers experimentally validated by MPRA in BECs. The prioritized effector genes included many genes involved in immune and inflammatory responses. Notably, multiple genes, including TNFSF4, a drug target undergoing clinical trials, were supported by two independent GWAS signals, indicating widespread allelic heterogeneity. Four out of six selected candidate CREs demonstrated allele-specific regulatory properties in luciferase assays in BECs.

We present a comprehensive characterization of causal variants, regulatory elements, and effector genes underlying AOA and COA genetics. Our results supported a distinct genetic basis between AOA and COA and highlighted regulatory complexity at many GWAS loci marked by both extensive pleiotropy and allelic heterogeneity.

Mepolizumab, an anti-IL-5 monoclonal antibody, has shown promise in reducing exacerbations and steroid dependency in severe eosinophilic asthma. This study aims to evaluate the effectiveness of mepolizumab in achieving clinical remission in asthma over 12 months and explore Vitamin D levels as a predictor of response.

We assessed Asthma Control Questionnaire (ACQ) scores, spirometry, number of exacerbations, oral corticosteroid (OCS) use, and inhaled corticosteroid (ICS) use in 32 patients, observing significant clinical improvements. Data were collected 1 year prior to starting mepolizumab and one year after starting mepolizumab. Nasal polyps were not seen in all the patients, and computed tomography of para-nasal sinuses are not available for all the patients, so nasal polyps status are not evaluated to avoid any bias.

Our results indicate that 12 patients achieved clinical remission after starting mepolizumab, with a strong correlation between higher Vitamin D levels and positive treatment outcomes. This suggests that optimizing Vitamin D levels could enhance the response to mepolizumab in asthma patients, and help in achieving better asthma control.

Mepolizumab is an effective treatment for severe eosinophilic asthma, significantly improving clinical outcomes and reducing corticosteroid use. This study highlights the importance of Vitamin D as a predictor of response to mepolizumab, suggesting that higher Vitamin D levels may enhance treatment efficacy.

Objective: Physical exercise in treatment of asthma is scarcely studied with no clear exercise guidelines for asthmatics. We aimed to investigate the associations between physical exercise frequency, systemic inflammation and asthma control. This has not been previously studied in adult-onset asthma.

Methods: This study is part of Seinäjoki Adult Asthma Study (SAAS), where 203 patients with adult-onset asthma were evaluated in 2012-2013. Exercise frequency was recorded with a structured lifestyle questionnaire. Study population was divided into two categories by exercise frequency: Low-frequency group exercised ≤2 times/week and high frequency group >2 times/week. Blood inflammatory markers were measured and IL-6 > 1.55 pg/ml and hs-CRP > 4.12 mg/l indicated systemic inflammation.

Results: High-exercise frequency group had lower levels of hs-CRP (p = 0.007), IL-6 (p = 0.015), suPAR (p = 0.008) and adipsin (p = 0.031) and higher levels of adiponectin (p = 0.010) than low-exercise frequency group. In logistic multivariate regression models, higher-exercise frequency lowered odds for elevated hs-CRP (OR = 0.37, 95% CI 0.15-0.94) and IL-6 levels (OR = 0.43, 95% CI 0.20-0.91), after adjusting for possible confounding factors. There was no difference in lung function tests, asthma control test or airways questionnaire 20 scores between the exercise frequency groups. However, differences were found in single symptom questions; high-exercise frequency group had less symptoms during light housework and laughing but experienced more limitation of activity in self-reports.

Conclusions: Higher-exercise frequency is associated with lower level of systemic inflammation in patients with adult-onset asthma but no clear association was found to asthma outcomes. Exercise frequency may be associated with lesser amount of some individual asthma symptoms.

Neutrophilic asthma is a vexing disease, but mechanistic and therapeutic advancements will require better models of allergy-induced airway neutrophilia. Here, we find that periodic ovalbumin (OVA) inhalation in sensitized mice elicits rapid allergic airway inflammation and pathophysiology mimicking neutrophilic asthma. OVA-experienced murine lungs harbor diverse clusters of CD4+ resident memory T (TRM) cells, including unconventional RORγtnegative/low T helper 17 (TH17) cells. Acute OVA challenge instigates interleukin (IL)-17A secretion from these TRM cells, driving CXCL5 production from Muc5achigh airway secretory cells, leading to destructive airway neutrophilia. The TRM and epithelial cell signals discovered herein are also observed in adult human asthmatic airways. Epithelial antigen presentation regulates this biology by skewing TRM cells toward TH2 and TH1 fates so that TH1-related interferon (IFN)-γ suppresses IL-17A-driven, CXCL5-mediated airway neutrophilia. Concordantly, in vivo IFN-γ supplementation improves disease outcomes. Thus, using our model of neutrophilic asthma, we identify lung epithelial-CD4+ TRM cell crosstalk as a key rheostat of allergic airway neutrophilia.

Obesity and smoking are core treatable traits (TTs) in type 2 (T2)-low asthma, contributing to its pathophysiology. In contrast, core extrapulmonary and behavior/risk factor traits remain unclear in T2-high asthma.

This study aimed to identify core extrapulmonary and behavior/risk factor traits for T2-high asthma.

A cross-sectional study was conducted on 187 people (aged ≥18 years) with severe asthma who completed a multidimensional assessment. T2-high asthma was defined as blood eosinophils ≥150 cells/μL and/or fractional exhaled nitric oxide ≥20 ppb. Core TTs in T2-high asthma were identified among 9 extrapulmonary traits and 4 behavior/risk factor traits, using network analysis and dominance analysis for the Asthma Control Questionnaire scores, the Asthma Quality of Life Questionnaire scores, exacerbation frequency, and lung function. Associations between the identified core TTs and biomarkers were examined in participants with T2-high asthma.

Of 187 participants, 151 (80.7%) had T2-high severe asthma. Dysfunctional breathing and depression had higher values of node strength than other TTs, contributing most to worse asthma symptoms, poorer quality of life, and frequent exacerbations in T2-high asthma. These conditions in T2-high asthma were associated with elevated systemic inflammation, including blood neutrophils, neutrophil-lymphocyte ratio, and serum high-sensitivity C-reactive protein, independent of obesity, oral corticosteroid dose, and anxiety.

Core extrapulmonary and behavior/risk factor traits in T2-high severe asthma were dysfunctional breathing and depression, contributing to worse asthma outcomes, suggesting that core TTs may differ between asthma inflammatory phenotypes. Elevated systemic inflammation may help in recognizing the presence of dysfunctional breathing and depression in T2-high severe asthma.

Background: Omentin (omentin-1, intelectin-1, ITLN-1) is an adipokine considered to be a novel substance. Many chronic, inflammatory, or civilization diseases are linked to obesity, in which omentin plays a significant role. Methods: MEDLINE and SCOPUS databases were searched using the keywords "omentin" or "intelectin-1". Then the most recent articles providing new perspectives on the matter and the most important studies, which revealed crucial insight, were selected to summarize the current knowledge on the role of omentin in a literature review. Results and Conclusions: The valid role of this adipokine is evident in the course of metabolic syndrome. In most cases, elevated omentin expression is correlated with the better course of diseases, including: type 2 diabetes mellitus, polycystic ovary syndrome, rheumatoid arthritis, metabolic dysfunction-associated steatotic liver disease, Crohn's disease, ulcerative colitis, atherosclerosis, or ischemic stroke, for some of which it can be a better marker than the currently used ones. However, results of omentin studies are not completely one-sided. It was proven to participate in the development of asthma and atopic dermatitis and to have different concentration dynamics in various types of tumors. All of omentin's effects and properties make it an attractive subject of research, considering still unexplored inflammation mechanisms, in which it may play an important role. Omentin was proven to prevent osteoarthritis, hepatocirrhosis, and atherosclerosis in mouse models. All of the above places omentin among potential therapeutic products, and not only as a biomarker. However, the main problems with the omentin's research state are the lack of standardization, which causes many contradictions and disagreements in this field.

The relationship between obesity, metabolic syndrome, related disorders, and various allergic diseases remains unclear. An overview of reviews investigating potential associations between obesity or metabolic syndrome and various allergic diseases was conducted. MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched. Systematic reviews and meta-analyses with summary effect size and corresponding 95% confidence intervals for at least one outcome (asthma, atopic dermatitis, and various allergic diseases) were included. This study encompassed 17 systematic review articles and 29 eligible meta-analyses. All included meta-analyses indicated a positive association between obesity/overweight and asthma. Three meta-analyses from one review demonstrated a positive association between obesity/overweight and the risk of atopic dermatitis. However, no meta-analyses focused on the associations between obesity/overweight or metabolic syndrome and allergic rhinitis, allergic conjunctivitis, or other allergic conditions. All included reviews employed poor methodology according to the AMSTAR-2 assessment tools. Our findings suggest that obesity likely increases the risk of asthma. However, evidence for associations with other allergic diseases is limited. Furthermore, no meta-analyses were conducted to assess the relationship between metabolic syndrome and allergic diseases. Further studies are necessary to elucidate the associations between obesity and the full spectrum of allergic diseases.

Background: The data on subphenotypes and treatment responses to biologicals in late-onset asthma (LOA) is limited. This study aims to compare the clinical characteristics and treatment responses in severe asthma patients receiving biological treatments, categorized into early-onset asthma (EOA) and LOA groups. Methods: Patients treated with omalizumab or mepolizumab for at least six months at a tertiary care adult allergy clinic between December 2015 and December 2023 were included. Patients with persistent respiratory symptoms starting at age ≥40 years were categorized as LOA, while those with onset <40 years were categorized as EOA. Changes in Asthma Control Questionnaire (ACQ-6) scores, forced expiratory volume in one second (FEV1) percentages, and blood eosinophil counts were assessed at baseline and 6 months. The percentage change in FEV1 (liters) at 6 months relative to baseline was measured. Clinical remission rates were evaluated in those completing one year of treatment. Results: Among 87 patients, 38 (43.7%) had LOA and 49 (56.3%) had EOA. Of these, 22 (25.3%) received omalizumab and 65 (74.7%) received mepolizumab, with a mean treatment duration of 24.7 (±19.7) months. LOA patients had higher obesity rates and tobacco consumption compared to EOA patients (p = 0.041 and p = 0.024, respectively). There were no significant differences between LOA and EOA groups in ACQ scores, FEV1 percentage, the percentage change in FEV1 in liters and eosinophil counts (p = 0.531, p = 0.219, p = 0.632, p = 0.700, respectively). Within LOA patients, ACQ scores did not significantly differ between those treated with omalizumab and mepolizumab (p = 0.801). At 6 months, eosinophil counts significantly decreased with mepolizumab but not with omalizumab (p = 0.002). Conclusion: Biological treatment responses were similar between LOA and EOA groups. Omalizumab and mepolizumab showed comparable efficacy, with the exception of eosinophil count changes in LOA patients.

Many studies have used game-based interventions to educate children about asthma. The study aims to determine the effectiveness of these games in improving asthma control and related outcomes in children.

Seven databases were searched: PubMed, Cochrane Library, Scopus, CINAHL, Embase, Web of Science, and PsycINFO'. All research papers published until June 2023 were included. MeSH terms and keywords were used in the literature search. The Joanna Briggs Institute Meta-Analysis of Statistics Assessment and Review Instruments was used to assess the risk of bias.

This systematic review and meta-analysis included nine studies with a total sample size of 694 children. The effect size for hospitalization rates was not statistically significant (p > 0.05), although the association was significant (p = 0.004). Conversely, a statistically significant reduction in emergency visits was observed (p < 0.05), with an effect size estimate of 0.376. The analysis also revealed a significant improvement in asthma knowledge (p < 0.05), with an effect size estimate of 0.677 (95 % CI: 0.240 to 1.114, p = 0.002), and an increase in asthma control (p < 0.05), although the association was not statistically significant (p = 0.120) with an effect size estimate of 0.169 (95 % CI: -0.044 to 0.381). Conversely, no statistically significant effect was observed for asthma attitude (p > 0.05).

Game-based interventions have shown promise in improving asthma management in children by enhancing knowledge and control and reducing emergency visits. This approach is increasingly recommended in clinical settings, though there is notable heterogeneity in study design and participant demographics.

Asthma exacerbations are frequently triggered by human rhinoviruses (RVs). Among other pro-inflammatory responses, RV infection of airway epithelium promotes the activation of the inflammasome pathway, the role of which in asthma exacerbations and disease progression is still poorly understood.

Bronchial brushing or biopsy specimens were collected from asthma patients and control subjects. Functional experiments were performed in cultured human bronchial epithelial cells (HBECs) using RV-A16, poly(I:C), and siRNA transfection. Gene expression was analysed by RNA-sequencing, RT-qPCR, immunofluorescence, western blot or ELISA. Caspase-1 activity was evaluated using FAM-FLICA assay.

The expression of NLRP1 was found to be the highest compared to other inflammasome sensors tested in brushed bronchial epithelium samples from asthma patients and control individuals, as well as in cultured primary HBECs. Additionally, we observed increased expression of CASP1 mRNA in bronchial epithelial cells from patients with neutrophilic asthma compared to those with paucigranulocytic and eosinophilic phenotypes. Changes in the expression of inflammasome pathway genes caused by RV-A16 infection were similar in HBEC cultures from asthma patients and controls, except for IL-1β, which showed increased response, and PYCARD, which exhibited decreased change in cells derived from asthma patients. Silencing of NLRP1 expression with siRNAs impeded RV-A16-induced activation of the inflammasome but had no effect on poly(I:C)-induced secretion of IL-1β and IL-18.

NLRP1 is highly expressed inflammasome sensor in both healthy and asthmatic bronchial epithelium and can be activated by RV-A16. RV-induced changes in the expression of inflammasome pathway genes suggest that there may be differences in HBECs derived from asthma patients, which may depend on the prevailing immunological phenotype of the disease.

Asthma is a chronic respiratory condition characterized by airway inflammation, remodeling, and hyperresponsiveness to triggers causing airway constriction. Bronchial smooth muscle plays a critical role by narrowing airways, leading to obstruction and breathing difficulties, often exacerbated by mast cell infiltration and histamine release. Whereas current treatments, including bronchodilators, corticosteroids, and biologics provide effective management for most patients, alternative therapies are needed for difficult-to-treat asthma. Recent research highlights the potential of therapeutic ketosis, achieved through dietary interventions or supplementation with exogenous ketones, to reduce airway hyperresponsiveness and inflammation. Ketone bodies, known for providing energy during carbohydrate scarcity, also influence asthma by activating cell-surface receptors and transporters. In vivo, interventions like weight loss and caloric restriction increase ketone body levels, correlating with improved asthma symptoms, reduced oxidative stress, and inflammation. These effects suggest ketone bodies, particularly β-hydroxybutyrate, may play a therapeutic role in mitigating bronchoconstriction and smooth muscle contraction in asthma. We utilize human bronchial smooth muscle cells (in vitro) and mouse precision-cut lung slices (PCLS) (ex vivo) to assess the effects of BHB on histamine-induced bronchoconstriction. Brightfield microscopy showed that BHB reduces contraction in human bronchial smooth muscle cells, an effect involving free fatty acid receptor 3 (FFAR3) activation. Light microscopy of PCLS revealed that BHB inhibits airway narrowing and cellular extrusion, demonstrating its ability to mitigate bronchoconstriction by suppressing smooth muscle contraction. These results implicate bronchial smooth muscle as a cellular target of therapeutic ketosis, an important contributor to the beneficial effects of BHB in preclinical models of asthma.

To examine airway inflammatory cell profiles in Indigenous Australian adults with asthma and chronic obstructive pulmonary disease (COPD).

A retrospective, cross-sectional study on data from a tertiary referral respiratory outpatient clinic.

Indigenous (n=23) and non-Indigenous (n=71) adults were matched according to diagnosis, gender and age to the ratio of 1:3.

Participants were defined by self-determined identification as Indigenous (Aboriginal) or non-Indigenous. A relevant history was taken, and lung function was measured by spirometry. In those with a diagnosis of asthma, symptom control was assessed by the Asthma Control Questionnaire, six items (ACQ6). In those with a diagnosis of COPD, symptoms were assessed by the COPD assessment test (CAT). Airway cell counts were obtained in all groups from bronchial lavage (BL) cell count.

Lung function and inhaled corticosteroid dose were similar between groups. Current smoking was three times more common in Indigenous people (35%) compared with non-Indigenous people (12%, p=0.009). In participants with asthma, ACQ6 scores were similar between Indigenous and non-Indigenous participants with asthma. In those with COPD, Indigenous participants had significantly higher total CAT scores as well as scores for cough and sputum with a score indicating a high impact on quality of life (CAT score ≥14, 85%-25%, p=0.017). There was no difference in BL cell differential counts.

Indigenous people with COPD had higher smoking rates, worsened CAT scores and more symptoms of cough and sputum production. There were no differences between the groups in airway inflammation, but neutrophilic inflammation was associated with poorly-controlled asthma.

Asthma is a common airway condition causing breathing difficulties due to reversible airflow obstruction. It often affects obese individuals, with symptoms triggered by environmental factors that induce immune responses, leading to inflammation and bronchoconstriction. Bronchial smooth muscle (BSM) plays a central role in airway narrowing, driven by type 2 immune responses involving cytokines like IL-4, IL-5, and IL-13, along with leukocytes including eosinophils and type 2 T-helper cells. These responses cause structural changes such as fibrosis and airway thickening, while BSM cells worsen asthma by releasing pro-inflammatory cytokines in response to allergens, microbial signals, or inflammatory cytokines from other cells. While current treatments manage asthma in most patients, alternative therapies are needed for difficult-to-treat cases, particularly prevalent in obese, allergic individuals. Emerging research suggests that therapeutic ketosis, induced by dietary changes or ketone supplementation, may reduce airway hyperresponsiveness and inflammation. The primary ketone body, β-hydroxybutyrate (BHB), produced during carbohydrate scarcity, acts via cell-surface receptors and transporters, potentially mitigating asthma symptoms. Weight loss and caloric restriction increase ketone levels, correlating with reduced inflammation and improved asthma outcomes. We hypothesized that β-hydroxybutyrate (BHB) reduces bronchoconstriction and inflammation in asthma by targeting bronchial smooth muscle. Using human bronchial smooth muscle cells (HBSMC) in vitro, we demonstrate herein that BHB suppresses IL-1β-induced pro-inflammatory cytokine production through Free Fatty Acid Receptor 3 (FFAR3) activation. These findings suggest that bronchial smooth muscle is a key target of therapeutic ketosis, supporting BHB's potential benefits in preclinical asthma models.

Genome-wide association studies (GWAS) have identified hundreds of loci underlying adult-onset asthma (AOA) and childhood-onset asthma (COA). However, the causal variants, regulatory elements, and effector genes at these loci are largely unknown.

We performed heritability enrichment analysis to determine relevant cell types for AOA and COA, respectively. Next, we fine-mapped putative causal variants at AOA and COA loci. To improve the resolution of fine-mapping, we integrated ATAC-seq data in blood and lung cell types to annotate variants in candidate cis-regulatory elements (CREs). We then computationally prioritized candidate CREs underlying asthma risk, experimentally assessed their enhancer activity by massively parallel reporter assay (MPRA) in bronchial epithelial cells (BECs) and further validated a subset by luciferase assays. Combining chromatin interaction data and expression quantitative trait loci, we nominated genes targeted by candidate CREs and prioritized effector genes for AOA and COA.

Heritability enrichment analysis suggested a shared role of immune cells in the development of both AOA and COA while highlighting the distinct contribution of lung structural cells in COA. Functional fine-mapping uncovered 21 and 67 credible sets for AOA and COA, respectively, with only 16% shared between the two. Notably, one-third of the loci contained multiple credible sets. Our CRE prioritization strategy nominated 62 and 169 candidate CREs for AOA and COA, respectively. Over 60% of these candidate CREs showed open chromatin in multiple cell lineages, suggesting their potential pleiotropic effects in different cell types. Furthermore, COA candidate CREs were enriched for enhancers experimentally validated by MPRA in BECs. The prioritized effector genes included many genes involved in immune and inflammatory responses. Notably, multiple genes, including TNFSF4, a drug target undergoing clinical trials, were supported by two independent GWAS signals, indicating widespread allelic heterogeneity. Four out of six selected candidate CREs demonstrated allele-specific regulatory properties in luciferase assays in BECs.

We present a comprehensive characterization of causal variants, regulatory elements, and effector genes underlying AOA and COA genetics. Our results supported a distinct genetic basis between AOA and COA and highlighted regulatory complexity at many GWAS loci marked by both extensive pleiotropy and allelic heterogeneity.

Asthma is a reversible clinical condition characterized by airway obstruction due to bronchial smooth muscle contraction, inflammation and a hypersecretive state. Severe asthma exacerbations (SAE) may be a part of the natural history of this condition. Patients presenting with SAE are at higher risk of recurrent attacks, often nonresponsive to medical therapy and eventually requiring invasive mechanical ventilation (MV). The use of noninvasive respiratory supports (NRSs) may be beneficial in patients with SAE who are at risk of developing acute respiratory failure (ARF). However, their application is insufficiently supported by the evidence, as reports on their application in asthmatic patients are scarce and only a few retrospective studies with a limited number of participants have been published to date. This review discusses the potentialities of NRS in the treatment of SAE, with reference to the pathophysiological background and future perspectives on their use in asthma management.

Asthma experienced by both adults and children is a phenotypically heterogeneous condition. Severe asthma, characterized by ongoing symptoms and airway inflammation despite high doses of inhaled and/or systemic corticosteroids, is the focus of research efforts to understand this underlying heterogeneity. Clinical phenotypes in both adult and pediatric asthma have been determined using supervised definition-driven classification and unsupervised data-driven clustering methods. Efforts to understand the underlying inflammatory patterns of severe asthma have led to the seminal discovery of type 2-high versus type 2-low phenotypes and to the development of biologics targeted at type 2-high inflammation to reduce the rates of severe asthma exacerbations. Type 2-high asthma is characterized by upregulation of T helper 2 immune pathways including interleukin (IL)-4, IL-5, and IL-13 along with eosinophilic airway inflammation, sometimes allergic sensitization, and responsiveness to treatment with corticosteroids. Type 2-low asthma is poorly responsive to corticosteroids and is not as well characterized as type 2-high asthma. Type 2-low asthma is limited by being defined as the absence of type 2-high inflammatory markers. Choosing a biologic for the treatment of severe asthma involves the evaluation of a panel of biomarkers such as blood eosinophils, total and specific immunoglobulin E/allergic sensitization, and fractional exhaled nitric oxide. In this review, we focus on the underlying pathobiology of adult and pediatric asthma, discuss the different phenotype-based treatment options for adult and pediatric type 2-high with or without allergic asthma and type 2-low asthma, and describe a clinical phenotyping approach to patients to guide out-patient therapy. Finally, we end with a discussion of whether pediatric asthma exacerbations necessitating admission to an ICU constitute their own high-risk phenotype and/or whether it is a part of other previously defined high-risk subgroups such as difficult-to-control asthma, exacerbation-prone asthma, and severe treatment-resistant asthma.

Steroid-resistant asthma (SRA) is a form of asthma resistant to corticosteroid therapy, which is characterized by the presence of neutrophil-predominant inflammatory response and neutrophil extracellular traps (NETs) formation. Hyssopus cuspidatus Boriss., a traditional Uyghur medicine, is known for its efficacy in treating inflammatory lung conditions such as asthma. However, the therapeutic impact and underlying mechanisms of Hyssopus cuspidatus Boriss.'s volatile oil (HVO) in SRA have not been fully elucidated.

This study established an ovalbumin/lipopolysaccharide (OVA/LPS)-induced SRA mice model to evaluate the therapeutic effect of HVO on SRA. UPLC-QE-Orbitrap-MS was applied to analyze the serum compositions of HVO. Network pharmacology and molecular docking were employed to uncover the complex mechanisms of HVO in treating SRA and predict potential effective compounds in HVO. Furthermore, in vivo studies in SRA mice and in vitro studies using HL-60 cells and bone marrow neutrophils were conducted to validate the mechanism.

HVO could significantly ameliorate OVA/LPS-induced SRA symptoms, including airway hyperresponsiveness, airway inflammation, mucus overproduction and airway remodeling. 41 prototype compounds, 65 Phase I metabolites and 50 Phase II metabolites were identified in serum-containing HVO. The integration of network pharmacology with experimental validation revealed that HVO can inhibit the formation of NETs by targeting neutrophil elastase, thereby exerting a therapeutic influence on SRA. Meanwhile, molecular docking results showed that 3-methoxy-4-hydroxy mandelonitrile, 1,2,3,4-tetrahydro-1,5,7-trimethyl-naphthalene, cis-calamenene and aristol-1(10)-en-9-yl isovalerate may be the therapeutic compounds of HVO in treating SRA.

These findings suggest that HVO is a promising therapeutic candidate for neutrophil-dominant SRA by targeting NETs formation.

To evaluate the effectiveness of noninvasive positive pressure ventilation (NPPV) versus standard therapy in severe asthma exacerbations through meta-analysis.

Nine randomized controlled trials (344 patients) were analyzed from inception to August 2024. Primary outcomes included respiratory rate, forced expiratory volume in first second (FEV1), and oxygen saturation (SpO2). Random effect models and trial sequential analyses were employed.

NPPV demonstrated significant reduction in respiratory rate versus standard therapy (mean difference [MD] -3.97, 95% CI -7.32 to -0.61, p = 0.02), though with high heterogeneity (I2 = 87%). FEV1 showed significant improvement with NPPV (MD 15.56%, 95% CI 6.86 to 24.26, p < 0.001) based on two studies. SpO2 showed no significant improvement (MD 0.62%, 95% CI -0.14 to 1.37, p = 0.11). No differences were found between pediatric and adult populations. Trial sequential analyses indicated insufficient evidence for definitive conclusions regarding respiratory rate and SpO2 improvements.

While NPPV may benefit severe asthma patients, particularly in reducing respiratory rate and improving FEV1, current evidence is insufficient for recommending routine clinical use. Larger randomized controlled trials are needed to establish NPPV's effectiveness in severe asthma exacerbation treatment.

registration ID CRD42024580051.

Exercise-induced bronchoconstriction (EIB) refers to temporary lower airway narrowing that occurs during or after vigorous physical exertion, with a high incidence in athletes and individuals with pre-existing asthma. The pathophysiology of EIB is not completely understood, but it is thought to involve a complex interplay among airway epithelial changes, immune responses, and environmental interactions. Phenotypic differences are apparent among those affected by EIB. This clinical review aims to summarize the complex mechanisms underlying EIB, explore the role of biomarkers in the diagnosis and management, and identify current gaps in knowledge to pave the way for future scientific discoveries.

Asthma has an annual increasing morbidity rate and imposes a heavy social burden on public healthcare systems. The aim of this study was to use machine learning to identify asthma-specific genes for the prediction and diagnosis of asthma.

Differentially expressed genes (DEGs) related to asthma were identified by examining public sequencing data from the Gene Expression Omnibus, coupled with the support vector machine recursive feature elimination and least absolute shrinkage and selection operator regression model. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene set enrichment analysis and correlation analyses between gene and immune cell levels were performed. An ovalbumin-induced asthma mouse model was established, and eukaryotic reference transcriptome high-throughput sequencing was performed to identify genes expressed in mouse lung tissues.

Thirteen specific asthma genes were obtained from our dataset analysis (LOC100132287, CEACAM5, PRR4, CPA3, POSTN, LYPD2, TCN1, SCGB3A1, NOS2, CLCA1, TPSAB1, CST1, and C7orf26). The GO analysis demonstrated that DEGs linked to asthma were primarily related to positive regulation of guanylate cyclase activity, gpi anchor binding, peptidase activity and arginine binding. The renin-angiotensin system, arginine biosynthesis and arginine and proline metabolism were the key KEGG pathways of DEGs. Additionally, the genes CEACAM5, PRR4, CPA3, POSTN, CLCA1, and CST1 expression levels were positively associated with plasma cells and resting mast cells. The mouse model revealed elevated nos2 and clca1 expression in the asthmatic mouse group compared with that in normal mice, which was consistent with the findings in asthmatic patients.

This study identified new marker genes for the prediction and diagnosis of asthma, which can be further validated and applied clinically.

Diesel exhaust particles (DEP) have been proven to aggravate asthma pathogenesis. We previously demonstrated that concurrent exposure to house dust mite (HDM) and DEP in mice increases both eosinophils and neutrophils in bronchoalveolar lavage fluid (BALF) and also results in higher levels of neutrophil-recruiting chemokines and neutrophil extracellular trap (NET) formation compared to sole HDM, sole DEP or saline exposure. We aimed to evaluate whether treatment with anti-IL-5 can alleviate the asthmatic features in this mixed granulocytic asthma model. Moreover, we aimed to unravel whether neutrophils modulate the DEP-aggravated eosinophilic airway inflammation.

Female C57BL6/J mice were intranasally exposed to saline or HDM and DEP for 3 weeks (subacute model). Interference with eosinophils was performed by intraperitoneal administration of anti-IL-5 (TRFK5), which neutralizes IL-5. Interference with neutrophils and neutrophil elastase was performed by intraperitoneal anti-Ly6G and sivelestat administration, respectively. Outcome parameters included eosinophils subsets (homeostatic EOS and inflammatory EOS), proinflammatory cytokines, goblet cell hyperplasia and airway hyperresponsiveness.

The administration of anti-IL-5 significantly decreased eosinophilic responses, affecting both inflammatory and homeostatic eosinophil subsets, upon subacute HDM + DEP exposure while BAL neutrophils, NET formation and other asthma features remained present. Neutrophils were significantly reduced after anti-Ly6G administration in BALF, lung and blood without affecting the eosinophilic inflammation upon HDM + DEP exposure. Sivelestat treatment tended to decrease BALF inflammation, including eosinophils, upon HDM + DEP exposure, but did not affect lung inflammation.

Inhibition of IL-5 signalling, but not neutrophil interventions, significantly attenuates eosinophilic inflammation in a mouse model of mixed granulocytic asthma, elicited by air pollution exposure.

In prednisone-dependent severe asthma, uncontrolled sputum eosinophilia is associated with increased numbers of group 2 innate lymphoid cells (ILC2s). These cells represent a relatively steroid-insensitive source of interleukin-5 (IL-5) and IL-13 and are considered critical drivers of asthma pathology. The abundance of ILC subgroups in severe asthma with neutrophilic or mixed granulocytic (both eosinophilic and neutrophilic) airway inflammation, prone to recurrent infective exacerbations, remains unclear. Here, we found by flow cytometry that sputum ILC3s are increased in severe asthma with intense airway neutrophilia, whereas equivalently raised sputum ILC2s and ILC3s were found in severe asthma with mixed granulocytic inflammation. Unbiased clustering analyses identified an "intermediate-ILC2" population displaying markers of both ILC2s (prostaglandin D2 receptor 2; CRTH2, IL-5, and IL-13) and ILC3s (c-kit and IL-17A) that were most abundant in severe asthma with mixed granulocytic airway inflammation. Intermediate ILC2s correlated with airway neutrophilia and were associated with increased amounts of IL-1β and IL-18 in sputum supernatants. Coculture of sort-purified canonical ILC2s with IL-1β and IL-18 in vitro up-regulated c-kit and IL-17A as well as gene expression profiles related to both type 2 and type 17 inflammatory pathways. Together, we have identified an intermediate-ILC2 phenotype in the airways of individuals with severe mixed granulocytic asthma, representing a candidate therapeutic target for controlling neutrophilic airway inflammation.