Sputum neutrophil counts are associated with more severe asthma phenotypes using cluster analysis

Catalase-encapsulated matrix metalloproteinase-9 responsive nanogels for modulation of inflammatory response and treatment of neutrophilic asthma

Asthma is a chronic disease with typical pathological features such as airflow limitation, airway inflammation and remodeling. Of these, neutrophilic asthma is considered to be the more severe and corticosteroid-resistant subtype of asthma. Increasing evidence suggests that patients with neutrophilic asthma often accompany with dysbiosis of the internal microbiota, where the increased abundance of non-typeable Haemophilus influenzae (NTHi) is closely related to the neutrophilic asthma phenotype. Furthermore, emerging evidence suggests that reactive oxygen species (ROS) are pivotal in the pathogenesis of neutrophilic asthma. In this study, matrix metalloproteinase-9 (MMP-9)-responsive, catalase-loaded nanogels (M-CAT-NGs) were synthesized, which was composed of MMP-9-sensitive peptide (VPMS), arginine-grafted chitosan and maleimide (CS-Arg-Mal), catalase (CAT), sodium citrate (SC) and ε-poly(L-lysine) (ε-PLL). The M-CAT-NGs showed potent antimicrobial effects and exerted excellent therapeutic effects in the presence of MMP-9 by causing VPMS rupture and responsive release of CAT. In vitro experiments revealed that M-CAT-NGs effectively inhibited the proliferation of NTHi, Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli), while also demonstrating the capacity to modulate the inflammatory response induced by lipopolysaccharide (LPS) and hydrogen peroxide (H2O2) stimulation. In vivo experiments demonstrated that nebulized inhalation of M-CAT-NGs was effective in reducing airway hyperresponsiveness (AHR), alleviating inflammation, downregulating the expression level of ROS in the lung tissues, thus enabling the effective management of neutrophilic asthma. Thus, the development of M-CAT-NGs has shown strong potential for the clinical management of neutrophilic asthma by modulating the inflammatory response.

IL-25 expression in induced sputum may serve as a reliable biomarker in children with bronchial asthma

BACKGROUND

Asthma is a chronic respiratory disease characterized by reversible airway obstruction and persistent airway inflammation, presenting as a highly heterogeneous disorder in children. Further understanding of its complexity is essential to identify applicable biomarkers and targeted therapies. Interleukin-25 (IL-25) has been shown to play a critical role in the pathogenesis of asthma.

METHODS

To investigate the association between IL and 25 expression and clinical characteristics, we enrolled46 children with asthma (age 6-17 years)and15 age-matched healthy controls. Asthma patients were stratified intoGroup A (untreated, n = 24)andGroup B (treatment-controlled, n = 22). IL-25 protein levels in serum and IL-25 mRNA in induced sputum were quantified usingELISA and PCR, respectively.

RESULTS

No significant intergroup differences existed in age (P = 0.32), sex (P = 0.67), or BMI (P = 0.144).IL-25 mRNA in sputumwas significantly elevated in both groups versus controls (P < 0.001 in Group A and P < 0.05 in Group B).Sputum IL-25 protein levelswerehigher in Group A versus controls (P < 0.001) and Group B (P < 0.05). IL-25 mRNA expression in sputumwas significantly higher in Group A (without anti-asthma drugs) compared to Group B (with controlled asthma treated with anti-asthma drugs) (P < 0.05 in both induced sputum and blood). Furthermore, IL-25 mRNA expression correlated with CRP (P = 0.007), FeNO (P = 0.04), FEV1/FVC (%) (P = 0.01), induced sputum eosinophil count (%) (P = 0.03), disease severity (P = 0.042), and anti-asthma treatment (P < 0.05). Notably, IL-25 levels in induced sputum decreased significantly at both molecular and gene levels following anti-asthma treatment, suggesting its potential as a biomarker for evaluating treatment efficacy and asthma control.

CONCLUSION

IL-25 expression in induced sputum may serve as a reliable biomarker in children with bronchial asthma, though further large-scale studies are needed to confirm these findings.

Neutrophil Extracellular Traps and neutrophilic asthma

There are more than 260 million asthma patients worldwide. How to provide targeted long-term standardized treatment and management still confuses clinical workers and patients. Neutrophilic asthma is a special type of asthma which is difficult to diagnose clinically and often associated with severe asthma and glucocorticoid resistance. Neutrophil Extracellular Traps (NETs) play an important role in the pathogenesis of this type of asthma particularly in children. This article explores the mechanism of NETs production, their association with neutrophilic asthma, biomarkers, and possible treatment options. A more detailed discussion is also provided on the diagnosis and treatment of children with neutrophilic asthma. Educational Aims The readers will gain an improved understanding of.

Relationship between pediatric asthma and respiratory microbiota, intestinal microbiota: a narrative review

Pediatric asthma is a common chronic airway inflammatory disease that begins in childhood and its impact persists throughout all age stages of patients. With the continuous progress of detection technologies, numerous studies have firmly demonstrated that gut microbiota and respiratory microbiota are closely related to the occurrence and development of asthma, and related research is increasing day by day. This article elaborates in detail on the characteristics, composition of normal gut microbiota and lung microbiota at different ages and in different sites, as well as the connection of the gut-lung axis. Subsequently, it deeply analyzes various factors influencing microbiota colonization, including host factor, delivery mode, maternal dietary and infant feeding patterns, environmental microbial exposure and pollutants, and the use of antibiotics in early life. These factors are highly likely to play a crucial role in the onset process and disease progression of asthma. Research shows that obvious changes have occurred in the respiratory and gut microbiota of asthma patients, and these microbiomes exhibit different characteristics according to the phenotypes and endotypes of asthma. Finally, the article summarizes the microbiota-related treatment approaches for asthma carried out in recent years, including the application of probiotics, nutritional interventions, and fecal microbiota transplantation. These treatment modalities are expected to become new directions for future asthma treatment and bring new hope for solving the problem of childhood asthma.

Anti-ST2 antibody reduces airway hyperresponsiveness mediated by monocyte-derived macrophages during influenza A infection

Influenza A virus (IAV) infections trigger asthma attacks and cause airway hyperresponsiveness (AHR) in murine models. However, the mechanism by which AHR is induced remains to be fully elucidated. Here, we show that targeting the interleukin (IL)-33 suppression of tumorigenicity 2 (ST2) receptor complex with an anti-ST2 antibody during acute IAV infection of C57BL/6 mice reduced AHR, without affecting expansion of ILC2s and independently of IL-13. Among the lung inflammatory cells, the anti-ST2 antibody selectively reduced the monocyte-derived macrophages (MMs). Furthermore, AHR was reduced in C-C chemokine receptor 2 (CCR2)-knockout mice that have deficient MM recruitment. Depletion of MMs achieved by anti-Ly6C antibody administration also reduced AHR. The treatment of airway smooth muscle (ASM) with conditioned medium from IL-33-treated human THP-1-derived macrophages enhanced potassium chloride-induced ASM contraction. These findings suggest that MMs contribute to acute AHR following IAV infection in an IL-33-dependent manner, but independent of the ILC2/IL-13 axis. Additionally, IL-33 stimulates the release of macrophage-derived mediators that enhance airway smooth muscle contraction, offering a potential mechanistic basis for IAV-induced AHR.

Exploring the roles of airway dipeptidyl peptidase 1 in obstructive airway disease

Background

Dipeptidyl peptidase 1 (DPP1) exacerbates airway neutrophilic inflammation in bronchiectasis, which is characterised by airway dysfunction and dilation and chronic bacterial infection. However, little is known about the pathogenetic roles of DPP1 in obstructive airway diseases, including COPD, asthma and asthma-COPD overlap (ACO). Here, we tested the hypothesis that airway DPP1 could enhance neutrophilic inflammation and affect mucus plugging, airway dilation and the airway microbiome in patients with these diseases.

Methods

Sputum DPP1, cell differential count and microbiome were cross-sectionally evaluated in patients with COPD, asthma with airflow limitation and ACO. Sputum high mobility group box 1 (HMGB1) was measured to estimate airway epithelial damage. Chest computed tomography was also performed to visually assess mucus plugs and airway dilation with the Reiff score and quantify the total airway count and wall area percentage.

Results

68 patients were classified into high-DPP1/high-neutrophil (n=17), low-DPP1/high-neutrophil (n=37) and low-neutrophil (n=14) groups based on sputum DPP1 levels and neutrophil percentages. The rate of mucus plugging and the relative abundance of the phylum Firmicutes were significantly lower and the level of sputum HMGB1 was significantly greater in the high-DPP1/high-neutrophil group than in the low-DPP1/high-neutrophil group. Moreover, airway dilation without mucus plugging was observed only in the high-DPP1/high-neutrophil group (prevalence 29%).

Conclusions

High sputum DPP1 levels may reduce colonisation by the phylum Firmicutes and mucus plugging, but increase airway epithelial damage, which could induce airway dilation without mucus plugging in patients with obstructive airway disease with neutrophilic inflammation.

The immunology of asthma and chronic rhinosinusitis

Asthma and chronic rhinosinusitis (CRS) are common chronic inflammatory diseases of the respiratory tract that have increased in prevalence over the past five decades. The clinical relationship between asthma and CRS has been well recognized, suggesting a common pathogenesis between these diseases. Both diseases are driven by complex airway epithelial cell and immune cell interactions that occur in response to environmental triggers such as allergens, microorganisms and irritants. Advances, including a growing understanding of the biology of the cells involved in the disease, the application of multiomics technologies and the performance of large-scale clinical studies, have led to a better understanding of the pathophysiology and heterogeneity of asthma and CRS. This research has promoted the concept that these diseases consist of several endotypes, in which airway epithelial cells, innate lymphoid cells, T cells, B cells, granulocytes and their mediators are distinctly involved in the immunopathology. Identification of the disease heterogeneity and immunological markers has also greatly improved the protocols for biologic therapies and the clinical outcomes in certain subsets of patients. However, many clinical and research questions remain. In this Review, we discuss recent advances in characterizing the immunological mechanisms of asthma and CRS, with a focus on the main cell types and molecules involved in these diseases.

Innate immune reprogramming in circulating neutrophils of COPD patients

BACKGROUND

Chronic obstructive pulmonary disease (COPD) involves both local and systemic neutrophilic inflammation, with dysregulation in blood neutrophil numbers, frequencies, and functions.

OBJECTIVE

We sought to characterize the transcriptional and epigenetic profiles of circulating neutrophils in patients with COPD and explore correlations with neutrophil dysfunction and clinical disease parameters.

METHODS

Circulating neutrophils of patients with COPD and control donors were subjected to RNA-sequencing and genome-wide analysis of histone 3 lysine 4 trimethylation (H3K4me3) by chromatin immunoprecipitation coupled with sequencing. Neutrophils' activation was assessed by cytofluorimetric analysis, O2- release, and Candida albicans phagocytosis assays.

RESULTS

RNA- and chromatin immunoprecipitation-sequencing analysis of H3K4me3 revealed a poised state in genes involved in innate immune activation, resembling the phenotype observed in neutrophils from individuals who are BCG-vaccinated, referred to as "trained," that is marked by weak or no expression under resting conditions but ready to be expressed at higher levels on stimulation. The epigenetic signature identified in neutrophils from subjects who are BCG-vaccinated was enriched in COPD neutrophils. In particular, and consistent with what has been described in "trained" neutrophils, COPD neutrophils exhibited transcriptional reprogramming of metabolically relevant genes. Functionally, COPD neutrophils produced higher CXCL8 and IL1B levels, released more O2-, and displayed greater phagocytic activity on in vitro stimulation.

CONCLUSIONS

These findings suggest that COPD neutrophils undergo epigenetic, transcriptomic, and metabolic reprogramming, which enhances their responsiveness and aligns with the phenotype of neutrophils previously identified as trained, offering mechanistic insight into the functional dysregulation observed in COPD.

BTLA agonist attenuates Th17-driven inflammation in a mouse model of steroid-resistant asthma

Introduction

Steroid-resistant asthma does not respond adequately to corticosteroid treatment. The underlying mechanisms driving corticosteroid resistance remain poorly understood, partly due to the absence of suitable animal models. Identifying the immunomodulatory pathways and mechanisms driving steroid resistance is crucial for developing effective therapies.

Methods

In this study, we screened 58 murine strains exposed to house dust mite and identified that the BXD75 strain exhibited neutrophil-skewed, steroid-resistant asthma and elevated Th17 cells. RNA sequencing of lung CD4+ T cells from BXD75 was performed to identify immunomodulatory pathways involved in steroid-resistance. The effects of BTLA agonist treatment were assessed on airway hyperreactivity and lung inflammation.

Results

Transcriptomic analysis revealed increased HVEM expression and decreased BTLA expression, both critical immune regulators associated with stimulatory and inhibitory signaling, respectively. These T cells demonstrated enhanced inflammatory signaling through both canonical and non-canonical NF-κB pathways. BTLA agonist treatment in vivo reduced airway hyperreactivity and lung inflammation, while ex vivo treatment of Th17 cells induced inhibitory signaling via SHP-1, suppressed NF-κB signaling, reduced cell numbers, and lowered IL-17 levels.

Discussion

Our findings establish BXD75 mice as a model for steroid-resistant asthma and demonstrate that BTLA agonism attenuates airway hyperreactivity and lung inflammation, highlighting it as a potential therapeutic strategy.

Biomarker-driven drug development for allergic diseases and asthma: An FDA public workshop

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.

PLK1 Mediates the Proliferation and Contraction of Airway Smooth Muscle Cells and Has a Role in T2-High Asthma with Neutrophilic Inflammation Model

Background

Type 2 (T2)-high asthma with neutrophilic inflammation is characterized by airway eosinophilic and neutrophilic infiltration, hyperresponsiveness, remodeling, and insensitivity to steroid treatment. Sphingosine-1-phosphate (S1P), which has a crucial role in the development of asthma, promotes the proliferation and contraction of airway smooth muscle cells (ASMCs), contributing to the pathophysiological processes of asthma. However, the downstream mediator of S1P remains unclear, as does its role in T2-high asthma with neutrophilic inflammation.

Methods

Ovalbumin- and ozone-induced murine models were used to replicate T2-high asthma with neutrophilic inflammation and primary ASMCs were applied to explore the underlying effects. Through transcriptomic analysis, PLK1 was identified as a potential key molecule associated with S1P-induced proliferation and contraction. Functional studies were performed both in vitro and in vivo by pharmacological inhibition to validate the role of PLK1 and to evaluate the therapeutic effects of PLK1 inhibition.

Results

S1P level was elevated in the bronchoalveolar lavage fluid (BALF) of T2-high asthma with neutrophilic inflammation model, and promoted ASMCs proliferation and contraction. PLK1 expression increased in S1P-stimulated ASMCs and asthmatic lung tissues. Inhibition of PLK1 blocked S1P-induced ASMCs proliferation and contraction. In vivo, PLK1 inhibition reduced airway inflammation (particularly neutrophilic infiltration), airway remodeling (airway smooth muscle proliferation and collagen deposition), and airway hyperresponsiveness and resistance, improving lung function (of both large and small airways), with superior therapeutic effects to those of dexamethasone. In addition, PLK1 inhibition markedly reduced the BALF levels of IL-17A, IL-21 and IL-6, suggesting that PLK1 might exert its effects mainly through the regulation of Th17 pathway.

Conclusion

PLK1 mediates S1P-induced ASMC proliferation and contraction, and plays an important part in T2-high asthma with neutrophilic inflammation model, making it a potential therapeutic target for treating T2-high asthma with neutrophilic inflammation.

Investigation of the Number of Oral Bacteria in Patients with Chronic Obstructive Pulmonary Disease, Asthma, and Asthma and Chronic Obstructive Pulmonary Disease Overlap

Objective Bacteria in the airways are reportedly involved in the pathogenesis of chronic obstructive pulmonary disease (COPD) and asthma. In addition, oral bacteria are thought to contribute to respiratory diseases by migrating to the airway. Therefore, we investigated whether or not the number of oral bacteria influences COPD, asthma, and asthma and COPD overlap (ACO). Methods We analyzed the correlations between the number of oral bacteria and clinical variables, such as pulmonary function tests, in patients with COPD, asthma, and ACO whose condition was stable and who visited our center from August 2019 to December 2020. The number of oral bacteria was assessed using the dielectrophoretic impedance measurement method. Results In patients with COPD (n = 50), the number of oral bacteria was significantly negatively correlated with the percentage predicted forced expiratory volume in one second (%FEV1), percentage peak expiratory flow, and percentage forced vital capacity but was not correlated with the COPD Assessment Test. In patients with asthma (n = 32), it was significantly negatively correlated with the FEV1 percentage and with the increase in FEV1 in the reversibility test but not with fractional exhaled nitric oxide. In patients with ACO (n = 39), we found no significant correlation between the number of oral bacteria and any clinical variable. Conclusion The results suggest that the number of oral bacteria is associated with both lung capacity and airflow obstruction in patients with COPD and with airflow obstruction in patients with asthma.

Cough-Variant Asthma: A Review of Clinical Characteristics, Diagnosis, and Pathophysiology

Chronic cough is among the most common symptoms prompting medical care. Cough-variant asthma (CVA) is an asthma subset where cough is the primary symptom, without wheezing, chest tightness, or dyspnea. It is an important cause of chronic cough, estimated to account for 25% to 42% of cases, but likely underdiagnosed due to delayed recognition and pitfalls of diagnostic testing. Early recognition and treatment can reduce morbidity and delay its progression to more typical asthma. This review details the clinical characteristics, diagnosis, pathophysiology, and treatment of CVA and contrasts it with classic asthma and other causes of chronic cough.

Integrative Roles of Pro-Inflammatory Cytokines on Airway Smooth Muscle Structure and Function in Asthma

Asthma has become more appreciated for its heterogeneity with studies identifying type 2 and non-type 2 phenotypes/endotypes that ultimately lead to airflow obstruction, airway hyperresponsiveness, and remodeling. The pro-inflammatory environment in asthma influences airway smooth muscle (ASM) structure and function. ASM has a vast repertoire of inflammatory receptors that, upon activation, contribute to prominent features in asthma, notably immune cell recruitment and activation, hypercontractility, proliferation, migration, and extracellular matrix protein deposition. These pro-inflammatory responses in ASM can be mediated by both type 2 (e.g., IL-4, IL-13, and TSLP) and non-type 2 (e.g., TNFα, IFNγ, IL-17A, and TGFβ) cytokines, highlighting roles for ASM in type 2 and non-type 2 asthma phenotypes/endotypes. In recent years, there has been considerable advances in understanding how pro-inflammatory cytokines promote ASM dysfunction and impair responsiveness to asthma therapy, corticosteroids and long-acting β2-adrenergic receptor agonists (LABAs). Transcriptomic analyses on human ASM cells and tissues have expanded our knowledge in this area but have also raised new questions regarding ASM and its role in asthma. In this review, we discuss how pro-inflammatory cytokines, corticosteroids, and LABAs affect ASM structure and function, with particular focus on changes in gene expression and transcriptional programs in type 2 and non-type 2 asthma.

Chronic Inflammation in Asthma: Looking Beyond the Th2 Cell

Asthma is a common chronic inflammatory disease of the airways. A substantial number of patients present with severe and therapy-resistant asthma, for which the underlying biological mechanisms remain poorly understood. In most asthma patients, airway inflammation is characterized by chronic activation of type 2 immunity. CD4+ T helper 2 (Th2) cells are the canonical producers of the cytokines that fuel type 2 inflammation: interleukin (IL)-4, IL-5, IL-9, and IL-13. However, more recent findings have shown that other lymphocyte subsets, in particular group 2 innate lymphoid cells (ILC2s) and type 2 CD8+ cytotoxic T (Tc2) cells, can also produce large amounts of type 2 cytokines. Importantly, a substantial number of severe therapy-resistant asthma patients present with chronic type 2 inflammation, despite the high sensitivity of Th2 cells for suppression by corticosteroids-the mainstay drugs for asthma. Emerging evidence indicates that ILC2s and Tc2 cells are more abundant in severe asthma patients and can adopt corticosteroid-resistance states. Moreover, many severe asthma patients do not present with overt type 2 airway inflammation, implicating non-type 2 immunity as a driver of disease. In this review, we will discuss asthma pathophysiology and focus on the roles played by ILC2s, Tc2 cells, and non-type 2 lymphocytes, placing special emphasis on severe disease forms.

Vascular remodeling and TSLP/angiogenin overexpression in severe mixed asthma

BACKGROUND

Asthma with neutrophilic/mixed inflammation is a difficult-to-control clinical phenotype. Currently, vascular and matrix airway remodeling in asthma with neutrophilic/mixed inflammation is not well known. We aimed to evaluate the differences in vascular/smooth muscle/matrix related asthma remodeling in eosinophilic (EOS) and mixed/neutrophilic (MIXED) bronchial phenotypes in relation to asthma severity and exacerbation frequency.

METHODS

In this cross-sectional study, α-SMA+ cells (100µM beneath the basement membrane [BM]), BM thickness, vascular remodeling-related biomarkers (angiogenin, vascular endothelial growth factor [VEGF], CD31 and Protease-activated receptor 2 [PAR2]), alarmins (TSLP and Interleukin (IL)-33) were evaluated in bronchial sections from 40 mild-to-severe asthmatics (EOS: N = 19 and mixed/neutrophilic: N = 19/2) and 7 control subjects (CTRL).

RESULTS

The number of CD31+ and angiogenin+ cells was higher in MIXED than in EOS asthmatics (p < 0.05). In severe MIXED CD31+, TSLP+, α-SMA+, and angiogenin+ cells increased compared to mild MIXED/EOS or severe EOS (p < 0.05), but BM thickness was higher in severe vs. mild EOS (p < 0.05). MIXED frequent exacerbators had higher numbers of CD31+ and TSLP+ cells, whereas MIXED non-exacerbators had increased PAR2+ cells. CD31+ cells correlated with impairment of pulmonary functions, number of exacerbations, ICS dose, bronchial neutrophils, angiogenin, α-SMA, TSLP and IL-33 (p < 0.05). Finally, CD31 > 97.17 cells/mm2, angiogenin > 35.36 cells/mm2, and functional parameters such as FEV1, FEV1/FVC, TLC and FRC (%pred.) were found to be predictors of severe MIXED asthma.

CONCLUSION

The severe or frequent exacerbator asthmatics with bronchial mixed inflammatory profile are characterized by increased number of vessels and overexpression of TSLP and angiogenin, suggesting a pathogenetic link between mixed eosinophilic and neutrophilic inflammation and vascular remodeling.

Asthma Phenotypes and Biomarkers

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.

Type 1 Immune Responses Related to Viral Infection Influence Corticosteroid Response in Asthma

Rationale: Corticosteroid-responsive type 2 (T2) inflammation underlies the T2-high asthma endotype. However, we hypothesized that type 1 (T1) inflammation, possibly related to viral infection, may also influence corticosteroid response. Objectives: To determine the frequency and within-patient variability of T1-high, T2-high, and T1/T2-high asthma endotypes and whether virally influenced T1-high disease influences corticosteroid response in asthma. Methods: Patients in SARP-3 (Severe Asthma Research Program-3) had sputum collected at baseline, after intramuscular (triamcinolone acetonide) corticosteroid treatment, and at 1- and 3-year follow-ups. Sputum cell RNA was used for whole-transcriptome gene network and viral metagenomic analyses. We then profiled patients as highly expressing T1 and/or T2 gene networks and established the influence of these endotypes on corticosteroid responsiveness and the likelihood of viral transcript detection in the airways. Measurements and Main Results: We found that 22% and 35% of patients with asthma highly expressed T1 and T2 network genes, respectively, and that 8.5% highly expressed both networks. Asthma severity outcomes were worse in T2-high compared with T1-high asthma and most severe in the T1-high/T2-high subgroup. Corticosteroid treatment strongly suppressed T2 but poorly suppressed T1 gene expression, and corticosteroid-associated improvements in FEV1 occurred only in patients with T1-low/T2-high disease and not in patients with T1-high/T2-high disease. Viral metagenomic analyses uncovered that 24% of asthma sputum samples tested positive for a respiratory virus, and high viral carriage was associated with 14-fold increased risk of T1-high disease. Conclusions: Airway T1 immune responses are relatively common in asthma, are largely corticosteroid resistant, and are associated with subclinical viral infection.

Anti-IL-5 treatment, but not neutrophil interference, attenuates inflammation in a mixed granulocytic asthma mouse model, elicited by air pollution

INTRODUCTION

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

The role of neutrophils in allergic disease

Neutrophils are short-lived cells of the innate immune system and represent 50-70% of the circulating leucocytes. Their primary role is antimicrobial defence which they accomplish through rapid migration to sites of inflammation followed by phagocytosis, degranulation, and the release of neutrophil extracellular traps (NETosis). While previously considered terminally differentiated cells, they have been shown to have great adaptability and to play a role in conditions ranging from cancer to autoimmunity. This review focuses on their role in allergic disease. In particular: their role as potential amplifiers of type 1 hypersensitivity reactions leading to anaphylaxis; their involvement in alternative pathways of food and drug allergy; their role in allergic rhinitis and asthma and neutrophil dysfunction in atopic dermatitis. The use of potential biomarkers and therapeutic targets is also discussed with a view to guiding future research.

Factors associated with uncontrolled severe asthma in the biologic era

BACKGROUND

Despite the development of biologics for severe asthma, individuals with uncontrolled status persist, posing a significant social problem. This multicenter prospective study aimed to identify factors associated with the uncontrolled status of patients with severe asthma in the biologic era assessed using the Asthma Control Questionnaire (ACQ).

METHODS

Subjects with severe asthma diagnosed by respiratory specialists were enrolled from 11 hospitals. Clinical data and questionnaires were collected. We compared controlled (ACQ-5 <1.5) with uncontrolled severe asthma (ACQ-5 ≥1.5) and assessed factors linked to uncontrolled severe asthma using logistic regression analysis.

RESULTS

One hundred fifty-four patients were analyzed (median age, 66 years; 62.3 % female; 52.6 % administered biologics). Among them, 56 patients (36.4 %) had uncontrolled severe asthma (ACQ-5 ≥1.5). The uncontrolled group had more frequent exacerbations (≥2 times in the previous year) and elevated blood neutrophil counts compared with the controlled group. Factors associated with uncontrolled status were analyzed in the overall population, with patients stratified into two groups: those receiving biologics and those not receiving biologics. Multivariate analysis revealed that frequent exacerbations and elevated blood neutrophil counts were associated with uncontrolled status in the overall population and in patients without biologics, whereas elevated blood neutrophil counts were significantly associated with uncontrolled status in patients receiving biologics.

CONCLUSION

Elevated blood neutrophil counts and frequent exacerbations were independently associated with uncontrolled severe asthma. Specifically, elevated blood neutrophil counts were a significant factor related to uncontrolled status irrespective of biologics, suggesting their potential utility as a biomarker in the biologic era.

CTSS contributes to airway neutrophilic inflammation in mixed granulocytic asthma

BACKGROUND

Mixed granulocytic asthma (MGA) is usually associated with poor response to corticosteroid therapy and a high risk of severe asthma. Cathepsin S (CTSS) has been found to play an important role in various inflammatory diseases. This study was aimed to investigate the role of CTSS in MGA.

METHODS

Induced sputum was obtained from healthy subjects and asthma patients. Two murine models of MGA were established using either TDI (toluene diisocyanate) alone or OVA emulsified in CFA. LY3000328, a specific antagonist of CTSS, was therapeutically given to BALB/c mice after airway challenge with TDI or OVA. The effects of recombinant CTSS was tested in vivo, and Akt inhibition was used to explore a possible mechanism for CTSS-induced airway inflammation.

RESULTS

MGA patients have a significant higher sputum CTSS level than the health and subjects with other inflammatory phenotypes, which was positively correlated with sputum level of soluble E-cadherin (sE-cadherin), sputum neutrophils, FeNO, FEF25-75% and glucocorticoid dosage. Allergen exposure markedly increased CTSS level and pharmacological antagonism of CTSS with LY3000328 decreased airway hyperresponsiveness, airway neutrophil accumulation, as well as the release of IL-17 and sE-cadherin in murine models of MGA, yet had no effects on eosinophilic inflammation nor type 2 inflammatory cytokines (IL-4 and IL-5). In addition, intratracheal instillation of recombinant CTSS leads to neutrophil recruitment and overproduction of sE-cadherin in the lung tissues, which could be attenuated by inhibition of Akt signaling.

CONCLUSION

Our data suggested that CTSS contributes to airway neutrophilic inflammation in MGA through an Akt-dependent pathway.

The potential role of n-3 fatty acids and their lipid mediators on asthmatic airway inflammation

Asthma, is a common, significant and diverse condition marked by persistent airway inflammation, with a major impact on human health worldwide. The predisposing factors for asthma are complex and widespread. The beneficial effects of omega-3 (n-3) polyunsaturated fatty acids (PUFAs) in asthma have increasingly attracted attention recently. In asthma therapy, n-3 PUFAs may reduce asthma risk by controlling on levels of inflammatory cytokines and regulating recruitment of inflammatory cells in asthma. The specialized pro-resolving mediators (SPMs) derived from n-3 PUFAs, including the E- and D-series resolvins, protectins, and maresins, were discovered in inflammatory exudates and their biosynthesis by lipoxygenase mediated pathways elucidated., SPMs alleviated T-helper (Th)1/Th17 and type 2 cytokine immune imbalance, and regulated macrophage polarization and recruitment of inflammatory cells in asthma via specific receptors such as formyl peptide receptor 2 (ALX/FPR2) and G protein-coupled receptor 32. In conclusion, the further study of n-3 PUFAs and their derived SPMs may lead to novel anti-inflammatory asthma treatments.

Diagnostic value of serum thymus and activation-regulated chemokine (TARC) in fatal asthma

OBJECTIVES

Asthma, a chronic inflammatory airway disease, is characterized by airway hyperresponsiveness and structural changes. Accurate postmortem diagnosis is crucial because of legal and insurance implications, necessitating differentiation from other causes of sudden death. Thymus and activation-regulated chemokine (TARC) is a chemokine that potentially acts as a biomarker of asthma. This study evaluated the diagnostic value of serum TARC combined with immunoglobulin E (IgE) levels as biomarkers in forensic settings.

RESULTS

The subjects were 100 autopsy cases, categorized into fatal asthma (n = 25), acute myocardial infarction (AMI) (n = 37), and traumatic deaths (n = 38). TARC levels were significantly elevated in asthma (525.68 ± 801.87 pg/mL) compared with AMI (180.35 ± 109.37 pg/mL) and trauma (173.26 ± 105.01 pg/mL) cases. Similarly, serum IgE levels were higher in asthma (3363.72 ± 7023.46 KU/L) than in AMI (130.92 ± 260.79 KU/L) and trauma (134.53 ± 195.41 KU/L) cases. ROC curve analysis showed that serum TARC had a sensitivity of 68.0 % and specificity of 73.6 % (AUC 0.763, cut-off value of 225 pg/mL). In comparison, serum IgE had a sensitivity of 80 % and specificity of 86.1 % (AUC 0.881, cut-off value of 307 KU/L). The combined use of TARC and IgE increased the diagnostic specificity to 95.8 %.

CONCLUSIONS

Serum TARC and IgE are valuable biomarkers for diagnosing fatal asthma in forensic settings. While serum TARC levels correlate with Th2-mediated inflammation, the combined measurement of TARC and IgE enhances the diagnostic accuracy, providing significant specificity for confirming asthma diagnosis.

Increased TGFβ1, VEGF and IFN-γ in the Sputum of Severe Asthma Patients With Bronchiectasis

BACKGROUND

Bronchiectasis is one of the most common comorbidities in severe asthma. However, the mechanisms by which asthma promotes the development and progress of this condition are not well defined. This study aimed to analyze the inflammatory phenotypes and quantify the expression of proinflammatory and remodeling cytokines in asthma patients with and without bronchiectasis.

METHODS

The study sample comprised individuals with severe asthma and bronchiectasis (group AB, n=55) and a control population of individuals with severe asthma without bronchiectasis (group AC, n=45). Induced sputum samples were obtained and cell types determined by differential cell count. Proinflammatory and bronchial remodeling cytokines (IL-8, neutrophilic elastase, TGFβ1, VEGF, IFN-γ, TNF-α, and GM-CSF) were analyzed by immunoassay in sputum supernatant.

RESULTS

Neutrophilic inflammation was the primary phenotype in both asthma groups. Higher levels of TGFβ1, VEGF and IFN-γ were observed in asthma patients with bronchiectasis (group AB) than in controls (group AC) (15 vs 24pg/ml, p=0.014; 183 vs 272pg/ml, p=0.048; 0.85 vs 19pg/ml, p<0.001, respectively). Granulocyte-macrophage colony-stimulating factor (GM-CSF) levels were significantly lower in the AB group than in the AC group (1.2 vs 4.4pg/ml, p<0.001). IL-8, neutrophil elastase and TNF-α did not present significant differences between the groups.

CONCLUSIONS

Raised levels of TGFβ1 and VEGF cytokines may indicate airway remodeling activation in asthma patients with bronchiectasis. The type of inflammation in asthma patients did not differ according to the presence or absence of bronchiectasis.

Biomarkers in asthma, potential for therapeutic intervention

Asthma is a heterogeneous disease characterized by multiple phenotypes with varying risk factors and therapeutic responses. This Commentary describes research on biomarkers for T2-"high" and T2-"low" inflammation, a hallmark of the disease. Patients with asthma who exhibit an increase in airway T2 inflammation are classified as having T2-high asthma. In this endotype, Type 2 cytokines interleukins (IL)-4, IL-5, and IL-13, plus other inflammatory mediators, lead to increased eosinophilic inflammation and elevated fractional exhaled nitric oxide (FeNO). In contrast, T2-low asthma has no clear definition. Biomarkers are considered valuable tools as they can help identify various phenotypes and endotypes, as well as treatment response to standard treatment or potential therapeutic targets, particularly for biologics. As our knowledge of phenotypes and endotypes expands, biologics are increasingly integrated into treatment strategies for severe asthma. These treatments block specific inflammatory pathways or single mediators. While single or composite biomarkers may help to identify subsets of patients who might benefit from these treatments, only a few inflammatory biomarkers have been validated for clinical application. One example is sputum eosinophilia, a particularly useful biomarker, as it may suggest corticosteroid responsiveness or reflect non-compliance to inhaled corticosteroids. As knowledge develops, a meaningful goal would be to provide individualized care to patients with asthma.

Causal relationships between allergic and autoimmune diseases with chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a prevalent inflammatory airway disease affecting over 10% of the global population, leading to considerable socio-economic impacts, especially in developing countries. The pathogenesis of CRS is multifactorial, involving potential contributions from both genetic and environmental factors. While the influence of allergic and autoimmune diseases on CRS has been observed, the causal relationships between these diseases and CRS remain unclear. We extracted data from large-scale genome-wide association studies (GWAS) and utilized a bidirectional two-sample Mendelian randomization (MR) analysis to explore the causal relationships between CRS and ten autoimmune and allergic diseases, including asthma, allergic rhinitis (AR), atopic dermatitis (AD), psoriasis, type 1 diabetes (T1D), hypothyroidism, celiac disease (CeD), multiple sclerosis (MS), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE). Additionally, we conducted colocalization analysis to determine whether the allergic/autoimmune diseases showing statistical causal relationships with CRS are driven by the same genetic variants. The MR analysis identified that AR (OR = 1.30; 95% CI = 1.21-1.40; P = 3.26E-13), asthma (OR = 1.35; 95% CI = 1.25-1.45; P = 1.35E-14), and AD (OR = 1.17; 95% CI = 1.06-1.30; P = 0.003) were significantly associated with an increased risk of developing CRS. Interestingly, psoriasis (OR = 0.05; 95% CI = 0.01-0.37; P = 0.004) appeared to have a protective effect against CRS. Associations for T1D and hypothyroidism were also suggestive as potential risk factors for CRS. No significant associations in the reverse MR analysis, suggesting a one-directional relationship. Colocalization analysis indicated that asthma (PP.H4 = 0.99) shared the same genetic variant (IL-33 rs3939286) with CRS. In conclusion, our study confirmed the causal relationships between allergic and autoimmune diseases (AR, asthma, AD, and psoriasis) and CRS. Notably, we identified a shared genetic variant, rs3939286 in the IL-33 gene, between asthma and CRS, suggesting that targeting the IL-33 pathway may provide a therapeutic strategy for both diseases.

Release of sputum neutrophil granules is associated with pulmonary function and disease severity in childhood asthma

BACKGROUND

Myeloperoxidase (MPO) and human neutrophil lipocalin or neutrophil gelatinase-associated lipocalin (HNL/NGAL) are stored in neutrophil granulocytes and secreted upon activation of the cells. They have been proposed to reflect the degree of inflammation in the airways. However, their role as potential markers of disease severity in childhood asthma remains unknown. This study investigated the relationship between the expression of MPO and HNL/NGAL and childhood asthma.

METHODS

A total of 83 pediatric patients with asthma and 59 controls were enrolled. Using enzyme-linked immunosorbent assays, the human MPO and HNL/NGAL levels were measured in sputum supernatants. Assessments including spirometry, methacholine challenge test, and atopy test were conducted.

RESULTS

No difference in sputum neutrophil counts was observed between pediatric patients with asthma and controls. However, sputum MPO and HNL/NGAL levels were significantly higher in patients with asthma than in controls (p = 0.021 and p < 0.001, respectively), especially in patients with moderate-to-severe persistent asthma. In patients with asthma, sputum MPO and HNL/NGAL levels showed a positive correlation with sputum neutrophil counts (MPO, r = 0.433, p < 0.001; HNL/NGAL, r = 0.584, p < 0.001) and with each other (r = 0.628, p < 0.001). Moreover, sputum HNL/NGAL level demonstrated better ability to accurately reflect current pulmonary function, airway inflammation, and limitations than MPO level in this study.

CONCLUSIONS

Sputum MPO and HNL/NGAL levels, which reflect neutrophil activation in airways, were increased in pediatric patients with asthma. Moreover, sputum MPO and HNL/NGAL may serve as appropriate assessment indicators of asthma severity in pediatric patients.

IL-1β-induced epithelial cell and fibroblast transdifferentiation promotes neutrophil recruitment in chronic rhinosinusitis with nasal polyps

Neutrophilic inflammation contributes to multiple chronic inflammatory airway diseases, including asthma and chronic rhinosinusitis with nasal polyps (CRSwNP), and is associated with an unfavorable prognosis. Here, using single-cell RNA sequencing (scRNA-seq) to profile human nasal mucosa obtained from the inferior turbinates, middle turbinates, and nasal polyps of CRSwNP patients, we identify two IL-1 signaling-induced cell subsets-LY6D+ club cells and IDO1+ fibroblasts-that promote neutrophil recruitment by respectively releasing S100A8/A9 and CXCL1/2/3/5/6/8 into inflammatory regions. IL-1β, a pro-inflammatory cytokine involved in IL-1 signaling, induces the transdifferentiation of LY6D+ club cells and IDO1+ fibroblasts from primary epithelial cells and fibroblasts, respectively. In an LPS-induced neutrophilic CRSwNP mouse model, blocking IL-1β activity with a receptor antagonist significantly reduces the numbers of LY6D+ club cells and IDO1+ fibroblasts and mitigates nasal inflammation. This study implicates the function of two cell subsets in neutrophil recruitment and demonstrates an IL-1-based intervention for mitigating neutrophilic inflammation in CRSwNP.

High-CBD Extract (CBD-X) in Asthma Management: Reducing Th2-Driven Cytokine Secretion and Neutrophil/Eosinophil Activity

BACKGROUND/OBJECTIVES

Asthma is a chronic inflammatory disorder of the airways affecting over 10% of the global population. It is characterized by airway inflammation, mucus hypersecretion, and bronchial hyperresponsiveness, driven predominantly by type 2 helper T cells (Th2) and type 2 innate lymphoid cells (ILC2s) in a subset of patients. However, a significant portion of asthmatic individuals present with "type 2-low" asthma that is often refractory to standard inhaled corticosteroid (ICS) therapy. Therefore, developing innovative therapeutic strategies has become essential. Recent studies have highlighted cannabidiol (CBD) as a promising anti-inflammatory agent capable of modulating immune responses. This study investigates the therapeutic potential of a high-CBD extract (CBD-X) in asthma.

METHODS

We evaluated the effects of CBD-X on cells involved in asthma pathogenesis using primary human Th2 cells, neutrophils, and asthma mouse model.

RESULTS

Our findings indicate that CBD-X extract inhibits Th2 differentiation and reduces the secretion of IL-5 and IL-13, which are crucial cytokines in asthma. Additionally, CBD-X significantly reduces pro-inflammatory cytokines IL-8 and IL-6 in neutrophils and impairs their migration, a critical step in airway inflammation. In a murine asthma model, CBD-X administration led to marked downregulation of IgE and pro-asthmatic cytokines, along with reduced leukocyte, eosinophil, and neutrophil infiltration in lung tissues.

CONCLUSIONS

These results suggest that CBD-X extract could offer a novel and complementary approach to managing both type 2-high and type 2-low asthma by targeting key inflammatory pathways and modulating immune cell behavior.

Asthma and hypertension: the role of airway inflammation

Introduction

Asthma is a chronic inflammatory respiratory disease often associated with comorbidities. Among cardiovascular comorbidities, arterial hypertension seems to create an additional health burden in asthmatics. However, evidence on this relationship is lacking.

Objective

Our study aims to evaluate the characteristics of hypertensive asthmatics, focusing on the role of inflammation as a possible link between these diseases.

Methods

We conducted a monocentric retrospective analysis consecutively including asthmatics who underwent induced sputum (IS) at our asthma referral center. Patients were divided in two groups according to presence or absence of history of hypertension. Clinical, functional, and inflammatory (airway and systemic) data were collected.

Results

Data on two hundred and sixty asthmatic patients were analyzed. Seventy-nine (30.4%) of them had a diagnosis of hypertension requiring a specific pharmacological treatment. Asthmatics with hypertension were more frequently male (p = 0.047), older (p < 0.001), and with higher body max index (BMI) (p < 0.001) when compared to normotensive patients. No difference concerning asthma control, severity and pharmacological treatment was observed between the two groups (all p > 0.05); distribution of comorbidities and lung function impairment (forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC); all p < 0.05) were statistically different between groups. Mixed granulocytic airway inflammation was prevalent in the hypertensive asthmatics (p = 0.014). Interestingly, a multivariable analysis revealed that age ≥ 65 years and an increased percentage of sputum neutrophils (≥61%) were independent predictors of hypertensive status (p < 0.001).

Conclusion

Our data suggest that neutrophilic airway inflammation (as evaluated by induced sputum) is strictly associated with hypertension. In clinical practice, phenotyping asthmatic patients with comorbidities like hypertension could be useful also from a therapeutic point of view. Additional studies are mandatory to further elucidate the role of neutrophilic airway inflammation in asthma with cardiovascular diseases.

A clinician's guide to effects of obesity on childhood asthma and into adulthood

INTRODUCTION

Obesity, one of the most common chronic conditions affecting the human race globally, affects several organ systems, including the respiratory system, where it contributes to onset and high burden of asthma. Childhood onset of obesity-related asthma is associated with high persistent morbidity into adulthood.

AREAS COVERED

In this review, we discuss the disease burden in children and adults to highlight the overlap between symptoms and pulmonary function deficits associated with obesity-related asthma in both age ranges, and then discuss the potential role of three distinct mechanisms, that of mechanical fat load, immune perturbations, and of metabolic perturbations on the disease burden. We also discuss interventions, including medical interventions for weight loss such as diet modification, that of antibiotics and anti-inflammatory therapies, as well as that of surgical intervention on amelioration of burden of obesity-related asthma.

EXPERT OPINION

With increase in obesity-related asthma due to increasing burden of obesity, it is evident that it is a disease entity distinct from asthma among lean individuals. The time is ripe to investigate the underlying mechanisms, focusing on identifying novel therapeutic targets as well as consideration to repurpose medications effective for other obesity-mediated complications, such as insulin resistance, dyslipidemia and systemic inflammation.

Downregulation of otulin induces inflammasome activation in neutrophilic asthma

BACKGROUND

Neutrophilic asthma (NA) is a severe asthma phenotype associated with steroid resistance and IL-1β overproduction; however, the exact mechanism remains unclear. Moreover, the dysfunction of TNF-α signaling pathway, a regulator of IL-1β production, was associated with the deficiency of ovarian tumor protease deubiquitinase with linear linkage specificity (otulin) in autoimmune patients.

OBJECTIVE

We hypothesized that otulin downregulation in macrophages (Mφ) could trigger Mφ activation via the nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3 (NLRP3) inflammasome signaling pathway.

METHODS

We assessed the expressions of otulin in blood monocyte subsets from NA patients and in alveolar Mφ from NA mice. Additionally, we evaluated the functional consequences of otulin deficiency in bone marrow-derived Mφ. The effects of inhibiting receptor-interacting protein kinase (RIPK)-1 and RIPK-3 on neutrophils and group 3 innate lymphoid cells (ILC3s) were assessed in vitro and in vivo.

RESULTS

When comparing nonclassical monocytes, a significant downregulation of otulin in the intracellular components was observed in NA patients compared to healthy controls (P = .005). Moreover, isolated alveolar Mφ from the NA mice exhibited lower otulin expression compared to those from control mice. After otulin knockdown in bone marrow-derived Mφ, we observed spontaneous IL-1β production depending on NLRP3 inflammasome. Moreover, the infiltrated neutrophils and ILC3s were significantly decreased by combined treatment of RIPK-1 and RIPK-3 inhibitors through blocking IL-1β release in NA.

CONCLUSIONS

IL-1β overproduction caused by a deficiency of otulin, an upstream triggering factor, could be a promising diagnostic and therapeutic target for NA.

Investigation of lactotransferrin messenger RNA expression levels as an anti-type 2 asthma biomarker

BACKGROUND

Lactotransferrin (LTF) has an immunomodulatory function, and its expression levels are associated with asthma susceptibility.

OBJECTIVES

We sought to investigate LTF messenger RNA (mRNA) expression levels in human bronchial epithelial cells (BECs) as an anti-type 2 (T2) asthma biomarker.

METHODS

Association analyses between LTF mRNA expression levels in BECs and asthma-related phenotypes were performed in the Severe Asthma Research Program (SARP) cross-sectional (n = 155) and longitudinal (n = 156) cohorts using a generalized linear model. Correlation analyses of mRNA expression levels between LTF and all other genes were performed by Spearman correlation.

RESULTS

Low LTF mRNA expression levels were associated with asthma susceptibility and severity (P < .025), retrospective and prospective asthma exacerbations, and low lung function (P < 8.3 × 10-3). Low LTF mRNA expression levels were associated with high airway T2 inflammation biomarkers (sputum eosinophils and fractional exhaled nitric oxide; P < 8.3 × 10-3) but were not associated with blood eosinophils or total serum IgE. LTF mRNA expression levels were negatively correlated with expression levels of TH2 or asthma-associated genes (POSTN, NOS2, and MUC5AC) and eosinophil-related genes (IL1RL1, CCL26, and IKZF2) and positively correlated with expression levels of TH1 and inflammation genes (IL12A, MUC5B, and CC16) and TH17-driven cytokines or chemokines for neutrophils (CXCL1, CXCL6, and CSF3) (P < 3.5 × 10-6).

CONCLUSIONS

Low LTF mRNA expression levels in BECs are associated with asthma susceptibility, severity, and exacerbations through upregulation of airway T2 inflammation. LTF is a potential anti-T2 biomarker, and its expression levels may help determine the balance of eosinophilic and neutrophilic asthma.

Time to resolution of airway inflammation caused by bronchoalveolar lavage in healthy horses

BACKGROUND

Bronchoalveolar lavage (BAL) is a common procedure for evaluation of the equine lower airways. Time to resolution of post-BAL inflammation has not been clearly defined.

HYPOTHESIS

Residual inflammation, evident by changes in immune cell populations and inflammatory cytokines, will resolve by 72 hours after BAL.

ANIMALS

Six adult, healthy, institution-owned horses.

METHODS

Randomized, complete cross-over design. Each horse underwent 3 paired BALs, including a baseline and then 48, 72, and 96 hours later, with a 7-day washout between paired BALs. Each sample underwent cytological evaluation and cytokine concentrations were determined by a commercially available multiplex bead immunoassay. Statistical analysis was performed by multilevel mixed-effects Poisson regression analysis. Data are reported as marginal means and 95% confidence interval (CI).

RESULTS

Neutrophil, eosinophil and mast cell percentages were not significantly different at any time points. Macrophage percentages were higher at 72 hours (45.0 [95% CI, 41.6-48.4]%) and 96 hours (45.3 [95% CI, 42.9-47.7]%) vs baseline (37.4 [95% CI, 33.5-41.4]%; P < .001 and P = .01, respectively), and at 72 hours and 96 hours vs 48 hours (31.9 [95% CI, 28.1-35.6]%; P < .001). Neutrophil percentage was not significantly increased at 48 hours (P = .11). Interleukin (IL)-6 concentration was increased at 72 hours (5.22 [95% CI, 3.44-6.99] pg/mL) vs 48 hours (4.38 [95% CI, 2.99-5.78] pg/mL; P < .001).

CONCLUSIONS AND CLINICAL IMPORTANCE

Significant lung inflammation was not detected at 72 and 96 hours, suggesting that repeating BAL at 72 hours or more can be done without concern of residual inflammation.

PIP-seq identifies novel heterogeneous lung innate lymphocyte population activation after combustion product exposure

Innate lymphoid cells (ILCs) are a heterogeneous population that play diverse roles in airway inflammation after exposure to allergens and infections. However, how ILCs respond after exposure to environmental toxins is not well understood. Here we show a novel method for studying the heterogeneity of rare lung ILC populations by magnetic enrichment for lung ILCs followed by particle-templated instant partition sequencing (PIP-seq). Using this method, we were able to identify novel group 1 and group 2 ILC subsets that exist after exposure to both fungal allergen and burn pit-related constituents (BPC) that include dioxin, aromatic hydrocarbon, and particulate matter. Toxin exposure in combination with fungal allergen induced activation of specific ILC1/NK and ILC2 populations as well as promoted neutrophilic lung inflammation. Oxidative stress pathways and downregulation of specific ribosomal protein genes (Rpl41 and Rps19) implicated in anti-inflammatory responses were present after BPC exposure. Increased IFNγ expression and other pro-neutrophilic mediator transcripts were increased in BPC-stimulated lung innate lymphoid cells. Further, the addition of BPC induced Hspa8 (encodes HSC70) and aryl hydrocarbon transcription factor activity across multiple lung ILC subsets. Overall, using an airway disease model that develops after occupational and environmental exposures, we demonstrate an effective method to better understand heterogenous ILC subset activation.

Asthma Pathogenesis: Phenotypes, Therapies, and Gaps: Summary of the Aspen Lung Conference 2023

Although substantial progress has been made in our understanding of asthma pathogenesis and phenotypes over the nearly 60-year history of the Aspen Lung Conferences on asthma, many ongoing challenges exist in our understanding of the clinical and molecular heterogeneity of the disease and an individual patient's response to therapy. This report summarizes the proceedings of the 2023 Aspen Lung Conference, which was organized to review the clinical and molecular heterogeneity of asthma and to better understand the impact of genetic, environmental, cellular, and molecular influences on disease susceptibility, heterogeneity, and severity. The goals of the conference were to review new information about asthma phenotypes, cellular processes, and cellular signatures underlying disease heterogeneity and treatment response. The report concludes with ongoing gaps in our understanding of asthma pathobiology and provides some recommendations for future research to better understand the clinical and basic mechanisms underlying disease heterogeneity in asthma and to advance the development of new treatments for this growing public health problem.

An antibacterial, multifunctional nanogel for efficient treatment of neutrophilic asthma

Asthma is a chronic and heterogeneous disease affecting the lungs and respiratory tract. In particular, the neutrophil subtype of asthma was described as persistent, more severe, and corticosteroid-resistant. Growing evidence suggested that nontypeable Haemophilus influenzae (NTHi) infection contributes to the development of neutrophilic asthma, exacerbating clinical symptoms and increasing the associated medical burden. In this work, arginine-grafted chitosan (CS-Arg) was ionically cross-linked with tris(2-carboxyethyl) phosphine (TCEP), and a highly-efficient antimicrobial agent, poly-ε-L-Lysine (ε-PLL), was incorporated to prepare ε-PLL/CS-Arg/TCEP (ECAT) composite nanogels. The results showed that ECAT nanogels exhibited highly effective inhibition against the proliferation of NTHi, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). In addition, ECAT nanogels could effectively inhibit the formation of mucins aggregates in vitro, suggesting that the nanogel might have the potential to destroy mucin in respiratory disease. Furthermore, in the ovalbumin (OVA)/NTHi-induced Balb/c mice model of neutrophilic asthma, the number of neutrophils in the alveolar lavage fluid and the percentage of inflammatory cells in the blood were effectively reduced by exposure to tower nebulized administration of ECAT nanogels, and reversing airway hyperresponsiveness (AHR) and reducing inflammation in neutrophilic asthma mice. In conclusion, the construction of ECAT nanogels was a feasible anti-infective and anti-inflammatory therapeutic strategy, which demonstrated strong potential in the clinical treatment of neutrophilic asthma.

Profiling severe asthma: Any relevance for age? An analysis from Severe Asthma Network Italy (SANI) cohort

Background

Aging implies changes in terms of lung function, immune system, and respiratory and extra-respiratory comorbidities. Few studies have specifically addressed the relevance of age on severe asthma burden and control. We aimed to evaluate whether age acts as an independent determinant of asthma severity, in terms of clinical, functional, and inflammatory profile, and to explore potential cofactors that contribute to a more difficult disease control in different age groups.

Methods

Patients from Severe Asthma Network Italy (SANI) registry were retrospectively divided in subgroups according to their age. Cutoffs for age were established according to quartiles in order to obtain a comparable number of patients for each group, and then rounded for the sake of simplicity.

Results

Overall, 1805 severe asthma patients were analyzed. Lung function represented the most important age-related variable. On the opposite the level of asthma control was not differently distributed among age ranges. In young people the presence of atopy-related comorbidities (allergic rhinitis, atopic dermatitis) predominated, whilst systemic-metabolic and degenerative comorbidities such as diabetes, cardiovascular diseases, anxious-depressive syndrome, and osteoporosis prevailed in elderly. Bronchiectasis and sleep disturbances were significantly associated with age.

Conclusions

Despite that it cannot be considered a treatable trait, our study suggests that age should be evaluated within a personalized approach to severe asthma patients, in order to provide a better clinical profiling and a more tailored treatment strategy.

Advances in non-type 2 severe asthma: from molecular insights to novel treatment strategies

Asthma is a prevalent pulmonary disease that affects more than 300 million people worldwide and imposes a substantial economic burden. While medication can effectively control symptoms in some patients, severe asthma attacks, driven by airway inflammation induced by environmental and infectious exposures, continue to be a major cause of asthma-related mortality. Heterogeneous phenotypes of asthma include type 2 (T2) and non-T2 asthma. Non-T2 asthma is often observed in patients with severe and/or steroid-resistant asthma. This review covers the molecular mechanisms, clinical phenotypes, causes and promising treatments of non-T2 severe asthma. Specifically, we discuss the signalling pathways for non-T2 asthma including the activation of inflammasomes, interferon responses and interleukin-17 pathways, and their contributions to the subtypes, progression and severity of non-T2 asthma. Understanding the molecular mechanisms and genetic determinants underlying non-T2 asthma could form the basis for precision medicine in severe asthma treatment.

Endotypes of severe neutrophilic and eosinophilic asthma from multi-omics integration of U-BIOPRED sputum samples

BACKGROUND

Clustering approaches using single omics platforms are increasingly used to characterise molecular phenotypes of eosinophilic and neutrophilic asthma. Effective integration of multi-omics platforms should lead towards greater refinement of asthma endotypes across molecular dimensions and indicate key targets for intervention or biomarker development.

OBJECTIVES

To determine whether multi-omics integration of sputum leads to improved granularity of the molecular classification of severe asthma.

METHODS

We analyzed six -omics data blocks-microarray transcriptomics, gene set variation analysis of microarray transcriptomics, SomaSCAN proteomics assay, shotgun proteomics, 16S microbiome sequencing, and shotgun metagenomic sequencing-from induced sputum samples of 57 severe asthma patients, 15 mild-moderate asthma patients, and 13 healthy volunteers in the U-BIOPRED European cohort. We used Monti consensus clustering algorithm for aggregation of clustering results and Similarity Network Fusion to integrate the 6 multi-omics datasets of the 72 asthmatics.

RESULTS

Five stable omics-associated clusters were identified (OACs). OAC1 had the best lung function with the least number of severe asthmatics with sputum paucigranulocytic inflammation. OAC5 also had fewer severe asthma patients but the highest incidence of atopy and allergic rhinitis, with paucigranulocytic inflammation. OAC3 comprised only severe asthmatics with the highest sputum eosinophilia. OAC2 had the highest sputum neutrophilia followed by OAC4 with both clusters consisting of mostly severe asthma but with more ex/current smokers in OAC4. Compared to OAC4, there was higher incidence of nasal polyps, allergic rhinitis, and eczema in OAC2. OAC2 had microbial dysbiosis with abundant Moraxella catarrhalis and Haemophilus influenzae. OAC4 was associated with pathways linked to IL-22 cytokine activation, with the prediction of therapeutic response to anti-IL22 antibody therapy.

CONCLUSION

Multi-omics analysis of sputum in asthma has defined with greater granularity the asthma endotypes linked to neutrophilic and eosinophilic inflammation. Modelling diverse types of high-dimensional interactions will contribute to a more comprehensive understanding of complex endotypes.

KEY POINTS

Unsupervised clustering on sputum multi-omics of asthma subjects identified 3 out of 5 clusters with predominantly severe asthma. One severe asthma cluster was linked to type 2 inflammation and sputum eosinophilia while the other 2 clusters to sputum neutrophilia. One severe neutrophilic asthma cluster was linked to Moraxella catarrhalis and to a lesser extent Haemophilus influenzae while the second cluster to activation of IL-22.

PIP-Seq identifies novel heterogeneous lung innate lymphocyte population activation after combustion product exposure

Innate lymphoid cells (ILCs) are a heterogeneous population that play diverse roles in airway inflammation after exposure to allergens and infections. However, how ILCs respond after exposure to environmental toxins is not well understood. Here we show a novel method for studying the heterogeneity of rare lung ILC populations by magnetic enrichment for lung ILCs followed by particle-templated instant partition sequencing (PIP-seq). Using this method, we were able to identify novel group 1 and group 2 ILC subsets that exist after exposure to both fungal allergen and burn pit-related constituents (BPC) that include dioxin, aromatic hydrocarbon, and particulate matter. Toxin exposure in combination with fungal allergen induced activation of specific ILC1/NK and ILC2 populations as well as promoted neutrophilic lung inflammation. Oxidative stress pathways and downregulation of specific ribosomal protein genes ( Rpl41 and Rps19 ) implicated in anti-inflammatory responses were present after BPC exposure. Increased IFNγ expression and other pro-neutrophilic mediator transcripts were increased in BPC-stimulated lung innate lymphoid cells. Further, the addition of BPC induced Hspa8 (encodes HSC70) and aryl hydrocarbon transcription factor activity across multiple lung ILC subsets. Overall, using an airway disease model that develops after occupational and environmental exposures, we demonstrate an effective method to better understand heterogenous ILC subset activation.

Association of Obesity and Severe Asthma in Adults

The incidence of obesity and asthma continues to enhance, significantly impacting global public health. Adipose tissue is an organ that secretes hormones and cytokines, causes meta-inflammation, and contributes to the intensification of bronchial hyperreactivity, oxidative stress, and consequently affects the different phenotypes of asthma in obese people. As body weight increases, the risk of severe asthma increases, as well as more frequent exacerbations requiring the use of glucocorticoids and hospitalization, which consequently leads to a deterioration of the quality of life. This review discusses the relationship between obesity and severe asthma, the underlying molecular mechanisms, changes in respiratory function tests in obese people, its impact on the occurrence of comorbidities, and consequently, a different response to conventional asthma treatment. The article also reviews research on possible future therapies for severe asthma. The manuscript is a narrative review of clinical trials in severe asthma and comorbid obesity. The articles were found in the PubMed database using the keywords asthma and obesity. Studies on severe asthma were then selected for inclusion in the article. The sections: 'The classification connected with asthma and obesity', 'Obesity-related changes in pulmonary functional tests', and 'Obesity and inflammation', include studies on subjects without asthma or non-severe asthma, which, according to the authors, familiarize the reader with the pathophysiology of obesity-related asthma.

Obesity Enhances Non-Th2 Airway Inflammation in a Murine Model of Allergic Asthma

Obese patients with asthma present with aggravated symptoms that are also harder to treat. Here, we used a mouse model of allergic asthma sensitised and challenged to house dust mite (HDM) extracts to determine whether high-fat-diet consumption would exacerbate the key features of allergic airway inflammation. C57BL/6 mice were intranasally sensitised and challenged with HDM extracts over a duration of 3 weeks. The impact of high-fat-diet (HFD) vs. normal diet (ND) chow was studied on HDM-induced lung inflammation and inflammatory cell infiltration as well as cytokine production. HFD-fed mice had greater inflammatory cell infiltration around airways and blood vessels, and an overall more severe degree of inflammation than in the ND-fed mice (semiquantitative blinded evaluation). Quantitative assessment of HDM-associated Th2 responses (numbers of lung CD4+ T cells, eosinophils, serum levels of allergen-specific IgE as well as the expression of Th2 cytokines (Il5 and Il13)) did not show significant changes between the HFD and ND groups. Interestingly, the HFD group exhibited a more pronounced neutrophilic infiltration within their lung tissues and an increase in non-Th2 cytokines (Il17, Tnfa, Tgf-b, Il-1b). These findings provide additional evidence that obesity triggered by a high-fat-diet regimen may exacerbate asthma by involving non-Th2 and neutrophilic pathways.

IL-4 regulates neutrophilic pulmonary inflammation in a mouse model of bronchial asthma

Neutrophilic pulmonary inflammation in asthmatics substantially exacerbates the severity of the disease leading to resistance to conventional corticosteroid therapy. Many studies established the involvement of Th1- and Th17-cells and cytokines produced by them (IFNg, IL-17A, IL-17F etc.) in neutrophilic pulmonary inflammation. Recent studies revealed that IL-4 - a Th2-cytokine regulates neutrophil effector functions and migration. It was showed that IL-4 substantially reduces neutrophilic inflammation of the skin in a mouse model of cutaneous bacterial infection and blood neutrophilia in a mouse model systemic bacterial infection. However, there are no data available regarding the influence of IL-4 on non-infectious pulmonary inflammation. In the current study we investigated the effects of IL-4 in a previously developed mouse model of neutrophilic bronchial asthma. We showed that systemic administration of IL-4 significantly restricts neutrophilic inflammation of the respiratory tract probably through the suppression of Th1-/Th17-immune responses and downregulation of CXCR2. Additionally, pulmonary neutrophilic inflammation could be alleviated by IL-4-dependant polarization of N2 neutrophils and M2 macrophages, expressing anti-inflammatory TGFβ. Considering these, IL-4 might be used for reduction of exaggerated pulmonary neutrophilic inflammation and overcoming corticosteroid insensitivity of asthma patients.

Pre-asthma: a useful concept? A EUFOREA paper. Part 2-late onset eosinophilic asthma

The concept of pre-diabetes has led to provision of measures to reduce disease progression through identification of subjects at risk of diabetes. We previously considered the idea of pre-asthma in relation to allergic asthma and considered that, in addition to the need to improve population health via multiple measures, including reduction of exposure to allergens and pollutants and avoidance of obesity, there are several possible specific means to reduce asthma development in those most at risk (pre- asthma). The most obvious is allergen immunotherapy (AIT), which when given for allergic rhinitis (AR) has reasonable evidence to support asthma prevention in children (2) but also needs further study as primary prevention. In this second paper we explore the possibilities for similar actions in late onset eosinophilic asthma.

Ferroptosis contributes to airway epithelial E-cadherin disruption in a mixed granulocytic asthma mouse model

Aberrant expression of airway epithelial E-cadherin is a key feature of asthma, yet the underlying mechanisms are largely unknown. Ferroptosis is a novel form of regulated cell death involved in asthma pathogenesis. This study was aimed to evaluate the role of ferroptosis and to investigate whether ferroptosis mediates E-cadherin disruption in mixed granulocyte asthma (MGA). Two murine models of MGA were established using toluene diisocyanate (TDI) or ovalbumin with Complete Freund's Adjuvant (OVA/CFA). Specific antagonists of ferroptosis, including Liproxstatin-1 (Lip-1) and Ferrostatin-1 (Fer-1) were given to the mice. The allergen-exposed mice displayed markedly shrunk mitochondria in the airway epithelia, with decreased volume and denser staining accompanied by down-regulated GPX4 as well as up-regulated FTH1 and malondialdehyde, which are markers of ferroptosis. Decreased pulmonary expression of E-cadherin was also observed, with profound loss of membrane E-cadherin in the airway epithelia, as well as increased secretion of sE-cadherin. Treatment with Lip-1 not only showed potent protective effects against the allergen-induced airway hyperresponsiveness and inflammatory responses, but also rescued airway epithelial E-cadherin expression and inhibited the release of sE-cadherin. Taken together, our data demonstrated that ferroptosis mediates airway epithelial E-cadherin dysfunction in MGA.

Effect of GHX02 on an Asthma-Rhinitis Mouse Model Induced by Ovalbumin and Diesel Particulate Matter

Fine dust concentrations come in direct contact with the human respiratory system, thereby reducing lung function and causing respiratory diseases such as asthma and rhinitis. The aim of this study was to evaluate the efficacy of GHX02 (combination of four herbs [Trichosanthes kirilowii, Prunus armeniaca, Coptis japonica, and Scutellaria baicalensis]), a herbal extract with established efficacy against bronchitis and pulmonary disease, in the treatment of asthma accompanied by rhinitis aggravated by fine dust. Therefore, we constructed an asthma-rhinitis mouse model of Balb/c mice challenged with ovalbumin (OVA) and fine diesel particulate matter, which were administered with three concentrations of GHX02. GHX02 significantly inhibited the increase of total cells and immune cells in bronchoalveolar lavage fluid, lung tissue, and nasal ductal lymphoid tissue (NALT). GHX02 also reduced the severity of histological lung injury and the expression of interleukin (IL)-1α and nuclear factor kappa B (NF-κB), which regulate inflammatory responses. The results indicate that GHX02 inhibited the inflammatory immune response in mice. Therefore, this study highlights the potential of GHX02 as a treatment for patients with asthma accompanied by rhinitis. Balb/c mice were challenged with OVA and PM10D, and then treated with three concentration of GHX02. GHX02 significantly inhibited the increase of total cells, immune cells lymphocytes, neutrophils, and macrophages, as well as their expression in lung tissue. GHX02 significantly inhibited the increase of total cells and immune cells in NALT. GHX02 decreased the severity of histological lung injury, expression of IL-1α and NF-κB. This study suggests the probability that GHX02 is effective for asthma patients with rhinitis by inhibiting inflammatory immune response.

The Efficacy & Molecular Mechanisms of a Terpenoid Compound Ganoderic Acid C1 on Corticosteroid-Resistant Neutrophilic Airway Inflammation: In vivo and in vitro Validation

Introduction

Neutrophil predominant airway inflammation is associated with severe and steroid-resistant asthma clusters. Previously, we reported efficacy of ASHMI, a three-herb TCM asthma formula in a steroid-resistant neutrophil-dominant murine asthma model and further identified Ganoderic Acid C1 (GAC1) as a key ASHMI active compound in vitro. The objective of this study is to investigate GAC1 effect on neutrophil-dominant, steroid-resistant asthma in a murine model.

Methods

In this study, Balb/c mice were systematically sensitized with ragweed (RW) and alum and intranasally challenged with ragweed. Unsensitized/PBS challenged mice served as normal controls. Post sensitization, mice were given 4 weeks of oral treatment with GAC1 or acute dexamethasone (Dex) treatment at 48 hours prior to challenge. Pulmonary cytokines were measured by ELISA, and lung sections were processed for histology by H&E staining. Furthermore, GAC1 effect on MUC5AC expression and on reactive oxygen species (ROS) production in human lung epithelial cell line (NCI-H292) was determined by qRT-PCR and ROS assay kit, respectively. Computational analysis was applied to select potential targets of GAC1 in steroid-resistant neutrophil-dominant asthma. Molecular docking was performed to predict binding modes between GAC1 and Dex with TNF-α.

Results

The result of the study showed that chronic GAC1 treatment, significantly reduced pulmonary inflammation (P < 0.01-0.001 vs Sham) and airway neutrophilia (P < 0.01 vs Sham), inhibited TNF-α, IL-4 and IL-5 levels (P < 0.05-0.001 vs Sham). Acute Dex treatment reduced eosinophilic inflammation and IL-4, IL-5 levels, but had no effect on neutrophilia and TNF-α production. GAC1 treated H292 cells showed decreased MUC5AC gene expression and production of ROS (P < 0.001 vs stimulated/untreated cells). Molecular docking results showed binding energy of complex GAC1-TNF was -10.8 kcal/mol.

Discussion

GAC1 may be a promising anti-asthma botanical drug for treatment of steroid-resistant asthma.

Comorbidity of patients with noncommunicable diseases in general practice. Eurasian guidelines

Создание руководства поддержано Советом по терапевтическим наукам отделения клинической медицины Российской академии наук.