Airway basophils are increased and activated in eosinophilic asthma

Sequential engagement of adhesion molecules and cytokine receptors impacts both piecemeal and anaphylactic degranulation of human basophils

Basophils are rare granulocytes in circulation which home to tissues in a process depending on rolling, adhesion and cytokine exposure. However, it is still unclear how these steps affect basophil degranulation. Our aim was to imitate these processes associated with homing by sequential crosslinking of adhesion molecules and cytokine exposure and evaluate the effect on basophil piecemeal (PMD) and anaphylactic degranulation (AND). Blood donors with or without allergic asthma were recruited from an ongoing cohort study. Basophils were subjected to CD62L-, CD49d- or CD11b crosslinking and IL-3 or IL-33 stimulation in different orders followed by anti-IgE and fMLP stimulation. Basophil CD203c and CD63 expression were analysed by flow cytometry to determine PMD and AND, respectively. IL-3 induced PMD in basophils and combined with CD62L- or CD11b crosslinking, IL-3 potentiated the degranulation regardless of sequential order. IL-3 priming followed by adhesion molecule crosslinking induced AND and potentiated the effect of anti-IgE. CD62L- and CD11b crosslinking did not further potentiate this effect. CD49d crosslinking followed by IL-3 increased CD63 expression following anti-IgE. IL-3 potentiated the effect of fMLP on AND while adhesion molecule crosslinking did not. IL-33 had impact on PMD only when followed by adhesion molecule crosslinking but did not potentiate neither IgE-dependent nor IgE-independent degranulation. Our data indicate that sequential interactions between basophils, cytokines and adhesion molecule ligands have a decisive effect on basophil degranulation and that these interactions are operational for fine-tuning the activity of tissue dwelling basophils. These data should be considered when the effect of different pharmaceutical on basophil function is studied.

Effects of increasing sensitizing doses of ovalbumin on airway hyperresponsiveness in asthmatic mice

BACKGROUND

The dosage of ovalbumin (OVA) during the sensitization stage is considered a crucial factor in the development of airway hyperresponsiveness (AHR). However, the inconsistent dosages of sensitizing OVA used in current studies and the lack of research on their impact on AHR are notable limitations.

METHODS

We examined the impact of increasing sensitizing doses of OVA in a murine asthma model, which entailed initial sensitization with OVA followed by repeated exposure to OVA aerosols. BALB/c mice were primed with doses of OVA (0, 10, 20, 50, and 100 μg) plus 1 mg Alum on Days 0 and 7, and were challenged with OVA aerosols (10 mg/mL for 30 min) between Days 14 and 17. Antigen-induced AHR to methacholine (MCh), as well as histological changes, eosinophilic infiltration, and epithelial injury were assessed.

RESULTS

The result indicated that there are striking OVA dose-related differences in antigen-induced AHR to MCh. The most intense antigen-induced AHR to MCh was observed with sensitization at 50 μg, while weaker responses were seen at 10, 20, and 100 μg. Meanwhile, there was a significant increase in eosinophil count with sensitization at 50 μg. The changes of AHR were correlated with total cells count, lymphocytes count, eosinophils count, and basophils count in bronchoalveolar lavage fluid; however, it did not correlate with histological changes such as cellular infiltration into bronchovascular bundles and goblet cell hyperplasia of the bronchial epithelium.

CONCLUSION

Overall, this study demonstrated that sensitization with 50 μg of OVA resulted in the most significant AHR compared to other dosages. These findings may offer valuable insights for future research on mouse asthma modeling protocols.

The Unified Airway Hypothesis: Evidence From Specific Intervention With Anti-IL-5 Biologic Therapy

The unified airway hypothesis proposes that upper and lower airway diseases reflect a single pathological process manifesting in different locations within the airway. Functional, epidemiological, and pathological evidence has supported this well-established hypothesis for some time. However, literature on the pathobiologic roles/therapeutic targeting of eosinophils and IL-5 in upper and lower airway diseases (including asthma, chronic rhinosinusitis with nasal polyps [CRSwNP], and nonsteroidal anti-inflammatory drug-exacerbated respiratory disease) has recently emerged. This narrative review revisits the unified airway hypothesis by searching the scientific literature for recent learnings and clinical trial/real-world data that provide a novel perspective on its relevance for clinicians. According to the available literature, eosinophils and IL-5 have important pathophysiological roles in both the upper and lower airways, although the impact of eosinophils and IL-5 may vary in asthma and CRSwNP. Some differential effects of anti-IL-5 and anti-IL-5-receptor therapies in CRSwNP have been observed, requiring further investigation. However, pharmaceutical targeting of eosinophils and IL-5 in patients with upper, lower, and comorbid upper and lower airway inflammation has led to clinical benefit, supporting the hypothesis that these are linked conditions manifesting in different locations. Consideration of this approach may improve patient care and aid clinical decision making.

The Functional Role of Group 2 Innate Lymphoid Cells in Asthma

Asthma is a heterogeneous disease characterized by chronic airway inflammation. Group 2 innate lymphoid cells (ILC2) play an important role in the pathogenesis of asthma. ILC2s lack antigen-specific receptors and respond to epithelial-derived cytokines, leading to the induction of airway eosinophilic inflammation in an antigen-independent manner. Additionally, ILC2s might be involved in the mechanism of steroid resistance. Numerous studies in both mice and humans have shown that ILC2s induce airway inflammation through inflammatory signals, including cytokines and other mediators derived from immune or non-immune cells. ILC2s and T helper type 2 (Th2) cells collaborate through direct and indirect interactions to organize type 2 immune responses. Interestingly, the frequencies or numbers of ILC2 are increased in the blood and bronchoalveolar lavage fluid of asthma patients, and the numbers of ILC2s in the blood and sputum of severe asthmatics are significantly larger than those of mild asthmatics. These findings may contribute to the regulation of the immune response in asthma. This review article highlights our current understanding of the functional role of ILC2s in asthma.

Involvement of Transforming Growth Factor-β-Associated Kinase 1 in Fixed Airway Obstruction in Asthmatic Patients with Longer Disease Duration Independent on Airway Eosinophilia

Objective

Transforming growth factor-β-associated kinase 1 (TAK1) mediates non-canonical TGF-β signalling by promoting adhesive, migratory, proliferative and contractile responses of fibroblasts to TGF-β₁. However, TAK1 expression status in asthmatic patients with or without fixed airway obstruction (FAO) is unknown.

Patients and Methods

A total of 60 adult asthmatics with FAO were recruited and compared to 43 those without FAO (nFAO). TGF-β₁ concentrations, and total TAK1 and phosphorylated TAK1 (p-TAK1) levels were determined in sputum supernatants, cytospin, and whole cell lysate by ELISA, immunocytochemistry, and Western blot analysis, respectively, in asthmatics with and without FAO.

Results

Asthmatic patients with FAO had much greater sputum TGF-β₁ concentrations than those without FAO. This was independent of airway eosinophilia as there was no significant difference in TGF-β₁ levels between high and low eosinophil counts within FAO and nFAO groups. In contrast, patients with FAO in the presence of sputum eosinophilia had greater expression of TAK1 and p-TAK1 than those without sputum eosinophilia (P=0.0032 and P=0.0061, respectively). The Western Blot data of total TAK1 and p-TAK1 were consistent with the immunocytochemistry, showing upregulation in all sputum cell types (neutrophils, eosinophils, macrophages, lymphocytes and airway epithelial cells). In addition, total TAK1 expression negatively correlated with pre- and post-bronchodilator FEV₁/FVC ratio.

Conclusion

TAK1 may play a key role in asthmatic patients with fixed airway obstruction, which was independent of eosinophilic airway inflammation. The interruption of TAK1 might have favourable clinical impact.

CD25 as a unique marker on human basophils in stable-mildly symptomatic allergic asthma

Background

Basophils in acute asthma exacerbation are activated as evidenced by their increased expression levels of activation markers such as CD203c and CD63. However, whether basophils of allergic asthmatics who are in stable phase and have no asthma exacerbations display a specific and distinctive phenotype from those of healthy individuals has yet to be well characterized.

Objective

We aimed to identify the phenotype of basophils from allergic asthmatics in the stable phase and investigate whether such a phenotype is affected by ex vivo allergen stimulation.

Methods

We determined by flow cytometry, the expression of surface proteins such as CD25, CD32, CD63, CD69, CD203c, and CD300a and intracellular anti-apoptotic proteins BCL-2, BCL-xL, and MCL-1. We investigated these markers in blood basophils obtained from well-characterized patients with stable-mildly symptomatic form of allergic asthma with no asthma exacerbation and from healthy individuals. Moreover, we determined ex vivo CD63, CD69, and CD25 on blood basophils from stable-mildly symptomatic allergic asthmatics upon allergen stimulation.

Results

In contrast to all tested markers, CD25 was significantly increased on circulating basophils in the patient cohort with stable-mildly symptomatic allergic asthma than in healthy controls. The expression levels of CD25 on blood basophils showed a tendency to positively correlate with FeNO levels. Notably, CD25 expression was not affected by ex vivo allergen stimulation of blood basophils from stable-mildly symptomatic allergic asthma patients.

Conclusion

Our data identifies CD25 as a unique marker on blood basophils of the stable phase of allergic asthma but not of asthma exacerbation as mimicked by ex vivo allergen stimulation.

Basophils from allergy to cancer

Human basophils, first identified over 140 years ago, account for just 0.5-1% of circulating leukocytes. While this scarcity long hampered basophil studies, innovations during the past 30 years, beginning with their isolation and more recently in the development of mouse models, have markedly advanced our understanding of these cells. Although dissimilarities between human and mouse basophils persist, the overall findings highlight the growing importance of these cells in health and disease. Indeed, studies continue to support basophils as key participants in IgE-mediated reactions, where they infiltrate inflammatory lesions, release pro-inflammatory mediators (histamine, leukotriene C₄: LTC₄) and regulatory cytokines (IL-4, IL-13) central to the pathogenesis of allergic diseases. Studies now report basophils infiltrating various human cancers where they play diverse roles, either promoting or hampering tumorigenesis. Likewise, this activity bears remarkable similarity to the mounting evidence that basophils facilitate wound healing. In fact, both activities appear linked to the capacity of basophils to secrete IL-4/IL-13, with these cytokines polarizing macrophages toward the M2 phenotype. Basophils also secrete several angiogenic factors (vascular endothelial growth factor: VEGF-A, amphiregulin) consistent with these activities. In this review, we feature these newfound properties with the goal of unraveling the increasing importance of basophils in these diverse pathobiological processes.

Using induced sputum method in clinical practice in patients with bronchial asthma

This article presents an overview of modern statements of the induced sputum method; detailed description of the methods and protocols for taking sputum in adults and children, methods for processing the obtained substance. The paper describes in detail the features of the cellular composition of induced sputum in healthy individuals and in patients with bronchial asthma, emphasizes the importance of the eosinophilia level as a prognostic and diagnostic criterion of asthma and also determines the functions of other induced sputum cells such as neutrophils, macrophages, basophils. The article is illustrated with photographs of sputum microscopy. In addition to sputum cytology, we give accent to the possibility of using other research methods such as an identification of viral and bacterial pathogens, genomics, proteomics, lipidomics, metabolomics, determination of the concentration of various mediators in the sputum supernatant. The paper presents the ideas on biochemical inflammatory markers and remodelling of the respiratory tract in asthma, which can be determined in sputum (C3a anaphylatoxin, clusterin, periostin, eosinophil-derived neurotoxin, folliculin). In addition, we summarize the information on inflammatory phenotypes of bronchial asthma, emphasize their variability and modification depending on the period of the disease, prescribed treatment, intercurrent respiratory infections, and smoking. The article also presents detailed characteristics of eosinophilic, neutrophilic, mixed and small granulocyte phenotypes of bronchial asthma, and describes the most frequent correlations of phenotypes with the severity and course of the disease, with lung function parameters and other indicators. The paper gives an account of the possibilities of using the induced sputum method for a comprehensive assessment of the course, asthma controllability and the effectiveness of drug therapy, as well as for a personalized selection of an antiinflammatory drug considering the inflammatory phenotype.

Forthcoming complications in recovered COVID-19 patients with COPD and asthma; possible therapeutic opportunities

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been growing swiftly worldwide. Patients with background chronic pulmonary inflammations such as asthma or chronic obstructive pulmonary diseases (COPD) are likely to be infected with this virus. Of note, there is an argument that COVID-19 can remain with serious complications like fibrosis or other pathological changes in the pulmonary tissue of patients with chronic diseases. Along with conventional medications, regenerative medicine, and cell-based therapy could be alternative approaches to compensate for organ loss or restore injured sites using different stem cell types. Owing to unique differentiation capacity and paracrine activity, these cells can accelerate the healing procedure. In this review article, we have tried to scrutinize different reports related to the harmful effects of SARS-CoV-2 on patients with asthma and COPD, as well as the possible therapeutic effects of stem cells in the alleviation of post-COVID-19 complications. Video abstract.

Diagnostic Accuracy of Liquid Biomarkers in Airway Diseases: Toward Point-of-Care Applications

Background

Liquid biomarkers have shown increasing utility in the clinical management of airway diseases. Salivary and blood samples are particularly amenable to point-of-care (POC) testing due to simple specimen collection and processing. However, very few POC tests have successfully progressed to clinical application due to the uncertainty and unpredictability surrounding their diagnostic accuracy.

Objective

To review liquid biomarkers of airway diseases with well-established diagnostic accuracies and discuss their prospects for future POC applications.

Methodology

A literature review of publications indexed in Medline or Embase was performed to evaluate the diagnostic accuracy of liquid biomarkers for chronic obstructive pulmonary disease (COPD), asthma, laryngopharyngeal reflux (LPR), and COVID-19.

Results

Of 3,628 studies, 71 fulfilled the inclusion criteria. Sputum and blood eosinophils were the most frequently investigated biomarkers for the management of asthma and COPD. Salivary pepsin was the only biomarker with a well-documented accuracy for the diagnosis of LPR. Inflammatory blood biomarkers (e.g., CRP, D-dimers, ferritin) were found to be useful to predict the severity, complications, and mortality related to COVID-19 infection.

Conclusion

Multiple liquid biomarkers have well-established diagnostic accuracies and are thus amenable to POC testing in clinical settings.

Role of Basophils in a Broad Spectrum of Disorders

Basophils are the rarest granulocytes and have long been overlooked in immunological research due to their rarity and similarities with tissue-resident mast cells. In the last two decades, non-redundant functions of basophils have been clarified or implicated in a broad spectrum of immune responses, particularly by virtue of the development of novel analytical tools for basophils. Basophils infiltrate inflamed tissues of patients with various disorders, even though they circulate in the bloodstream under homeostatic conditions. Depletion of basophils results in the amelioration or exaggeration of inflammation, depending on models of disease, indicating basophils can play either beneficial or deleterious roles in a context-dependent manner. In this review, we summarize the recent findings of basophil pathophysiology under various conditions in mice and humans, including allergy, autoimmunity, tumors, tissue repair, fibrosis, and COVID-19. Further mechanistic studies on basophil biology could lead to the identification of novel biomarkers or therapeutic targets in a broad range of diseases.

The role of human mast cells in allergy and asthma

Mast cells are tissue-inhabiting cells that play an important role in inflammatory diseases of the airway tract. Mast cells arise in the bone marrow as progenitor cells and complete their differentiation in tissues exposed to the external environment, such as the skin and respiratory tract, and are among the first to respond to bacterial and parasitic infections. Mast cells express a variety of receptors that enable them to respond to a wide range of stimulants, including the high-affinity FcεRI receptor. Upon initial contact with an antigen, mast cells are sensitized with IgE to recognize the allergen upon further contact. FcεRI-activated mast cells are known to release histamine and proteases that contribute to asthma symptoms. They release a variety of cytokines and lipid mediators that contribute to immune cell accumulation and tissue remodeling in asthma. Mast cell mediators trigger inflammation and also have a protective effect. This review aims to update the existing knowledge on the mediators released by human FcεRI-activated mast cells, and to unravel their pathological and protective roles in asthma and allergy. In addition, we highlight other diseases that arise from mast cell dysfunction, the therapeutic approaches used to address them, and fill the gaps in our current knowledge. Mast cell mediators not only trigger inflammation but may also have a protective effect. Given the differences between human and animal mast cells, this review focuses on the mediators released by human FcεRI-activated mast cells and the role they play in asthma and allergy.

Basophils and their effector molecules in allergic disorders

Basophils are the rarest granulocytes which represent <1% of peripheral blood leukocytes. Basophils bear several phenotypic similarities to tissue-resident mast cells and therefore had been erroneously considered as blood-circulating mast cells. However, recent researches have revealed that basophils play nonredundant roles in allergic inflammation, protective immunity against parasitic infections and regulation of innate and acquired immunity. Basophils are recruited to inflamed tissues and activated in an IgE-dependent or IgE-independent manner to release a variety of effector molecules. Such molecules, including IL-4, act on various types of cells and play versatile roles, including the induction and termination of allergic inflammation and the regulation of immune responses. Recent development of novel therapeutic agents has enabled us to gain further insights into basophil biology in human disorders. In this review, we highlight the recent advances in the field of basophil biology with a particular focus on the role of basophils in allergic inflammation. Further studies on basophils and their effector molecules will help us identify novel therapeutic targets for treating allergic disorders.

Group 2 Innate Lymphoid Cells: Team Players in Regulating Asthma

Type 2 immunity helps protect the host from infection, but it also plays key roles in tissue homeostasis, metabolism, and repair. Unfortunately, inappropriate type 2 immune reactions may lead to allergy and asthma. Group 2 innate lymphoid cells (ILC2s) in the lungs respond rapidly to local environmental cues, such as the release of epithelium-derived type 2 initiator cytokines/alarmins, producing type 2 effector cytokines such as IL-4, IL-5, and IL-13 in response to tissue damage and infection. ILC2s are associated with the severity of allergic asthma, and experimental models of lung inflammation have shown how they act as playmakers, receiving signals variously from stromal and immune cells as well as the nervous system and then distributing cytokine cues to elicit type 2 immune effector functions and potentiate CD4⁺ T helper cell activation, both of which characterize the pathology of allergic asthma. Recent breakthroughs identifying stromal- and neuronal-derived microenvironmental cues that regulate ILC2s, along with studies recognizing the potential plasticity of ILC2s, have improved our understanding of the immunoregulation of asthma and opened new avenues for drug discovery.

Mast Cells as a Double Edged Sword in Immunity: Disorders of Mast Cell Activation and Therapeutic Management. Second of Two Parts

Mast cells (MCs) bear many receptors that allow them to respond to a variety of exogenous and endogenous stimuli. However, MC function is dual since they can initiate pathological events or protect the host against infectious challenges. The role of MCs in disease will be analyzed in a broad sense, describing cellular and molecular mechanisms related to their involvement in auto-inflammatory diseases, asthma, autoimmune diseases and cancer. On the other hand, their protective role in the course of bacterial, fungal and parasitic infections will also be illustrated. As far as treatment of MC-derived diseases is concerned, allergen immunotherapy as well as other attempts to reduce MC-activation will be outlined according to the recent data. Finally, in agreement with current literature and our own data polyphenols have been demonstrated to attenuate type I allergic reactions and contact dermatitis in response to nickel. The use of polyphenols in these diseases will be discussed also in view of MC involvement.

Sputum mast cell/basophil gene expression relates to inflammatory and clinical features of severe asthma

BACKGROUND

Mast cells (MCs) and basophils are important in asthma pathophysiology, however direct measurement is difficult, and clinical and inflammatory associations in severe asthma are poorly understood. Transcriptomic hallmarks of MCs/basophils may allow their measurement in sputum using gene expression.

OBJECTIVES

This study sought to develop and validate a sputum MC/basophil gene signature and investigate its relationship to inflammatory and clinical characteristics of severe asthma.

METHODS

A total of 134 candidate MC/basophil genes (identified by the Immunological Genome Project Consortium) were screened in sputum microarray for differential expression among control subjects (n = 18), patients with eosinophilic (n = 29), and patients with noneosinophilic asthma (n = 30). Candidate genes were validated by confirming correlation of gene expression with flow cytometry-quantified sputum MCs and basophils in a separate asthma cohort (n = 20). The validated gene signature was measured in a severe asthma cohort (n = 81), and inflammatory and clinical associations were tested.

RESULTS

Through microarray screening and subsequent validation, we found quantitative PCR gene expression of 8 targets correlated with sputum MCs/basophils: TPSAB1/TPSB2, CPA3, ENO2, GATA2, KIT, GPR56, HDC, SOCS2. In severe asthma, MC/basophil genes were associated with eosinophilic airway inflammation (GATA2, TPSB2, CPA3, GPR56, HDC, SOCS2), blood eosinophils (TPSB2, CPA3, GATA2, SOCS2, FCER1A, HDC), fractional exhaled NO (GATA2, SOCS2), decreased lung function (KIT, ENO2), and moderate exacerbation history (GATA2, SOCS2).

CONCLUSIONS

Quantitative PCR-based measures reflect varying sputum MC/basophil abundance, demonstrating associations of MCs/basophils with eosinophilic inflammation, spirometry and exacerbation history in severe asthma.

Molecular Analysis of IL-5 Receptor Subunit Alpha as a Possible Pharmacogenetic Biomarker in Asthma

Background: Asthma is a heterogeneous syndrome with a broad clinical spectrum and high drug response variability. The inflammatory response in asthma involves multiple effector cells and mediator molecules. Based on asthma immunopathogenesis, precision medicine can be a promising strategy for identifying biomarkers. Biologic therapies acting on the IL-5/IL-5 receptor axis have been developed. IL-5 promotes proliferation, differentiation and activation of eosinophils by binding to the IL-5 receptor, located on the surface of eosinophils and basophils. This study aimed to investigate the expression of IL5RA in patients with several types of asthma and its expression after treatment with benralizumab, a biologic directed against IL-5 receptor subunit alpha.

Methods: Sixty peripheral blood samples, 30 from healthy controls and 30 from asthmatic patients, were selected for a transcriptomic RNAseq study. Differential expression analysis was performed by statistical assessment of fold changes and P-values. A validation study of IL5RA expression was developed using qPCR in 100 controls and 187 asthmatic patients. The effect of benralizumab on IL5RA expression was evaluated in five patients by comparing expression levels between pretreatment and after 3 months of treatment. The IL5RA mRNA levels were normalized to GAPDH and TBP expression values for each sample. Calculations were made by the comparative ΔΔCt method. All procedures followed the MIQE guidelines.

Results:IL5RA was one of the most differentially overexpressed coding transcripts in the peripheral blood of asthmatic patients (P = 8.63E-08 and fold change of 2.22). In the qPCR validation study, IL5RA expression levels were significantly higher in asthmatic patients than in controls (P < 0.001). Significant expression differences were present in different asthmatic types. In the biological drug study, patients treated with benralizumab showed a significant decrease in IL5RA expression and blood eosinophil counts. A notable improvement in ACT and lung function was also observed in these patients.

Conclusions: These results indicate that IL5RA is overexpressed in patients with different types of asthma. It could help identify which asthmatic patients will respond more efficiently to benralizumab, moving toward a more personalized asthma management. Although further studies are required, IL5RA could play a role as a biomarker and pharmacogenetic factor in asthma.

Clinical Differences between Early- and Late-Onset Asthma: A Population-Based Cross-Sectional Study

Background

Limited information exists about the nature of late-onset asthma (LOA) without medication intervention when compared to early-onset asthma (EOA). Our goal was to understand how EOA and LOA affect clinical and pathophysiological features.

Methods

A population-based cross-sectional study was carried out in Zhongshan Hospital (Shanghai, China). EOA and LOA were based on age of diagnosis (before and after age 40 years, respectively). Clinical variables were collected with an emphasis on allergic features, analyzed, related, and compared using one-way ANOVA or Kruskal-Wallis test. Correlations between blood basophils and clinical data were evaluated by Spearman's rank test. Statistical analyses were conducted with SPSS v24.0.

Results

Of a total of 12,760 adults with cough, sputum, or chest tightness, 90 subjects with EOA (mean age ± standard deviation (SD):28.73 ± 5.89), 111 with LOA (mean age ± SD: 60.25 ± 9.85), and 106 with chronic obstructive pulmonary disease (COPD) (mean age ± SD: 61.58 ± 10.95) were selected. FEV₁/FVC (%), FEV₁% predicted, and FVC% predicted were all significantly lower in LOA compared to EOA (p < 0.01). The values of post-bronchodilator FEV₁ in bronchodilator reversibility testing were higher in the LOA and EOA groups compared to subjects with COPD (p < 0.01). Among allergic features, mite sensitization was most common in EOA patients, followed by LOA and COPD, whereas mold sensitization was more prevalent in LOA than EOA. Moreover, blood eosinophils were a typical feature of asthma in both EOA and LOA compared to COPD and controls (p < 0.01), and there were no differences in blood neutrophils in LOA compared to controls. Interestingly, blood basophils were increased in both EOA (p < 0.01) and LOA (p < 0.05) compared to COPD and controls. This variable correlated with eosinophils in EOA (r = 0.549, p=0.002) but not in LOA.

Conclusion

LOA is a distinct clinical entity from EOA. In LOA, atopy was less frequent and spirometry values were lower when compared to EOA. In EOA, blood basophils and eosinophils were significantly correlated owing to pathophysiological differences between the two forms of the disease.

Risk Factors Predicting Severe Asthma Exacerbations in Adult Asthmatics: A Real-World Clinical Evidence

PURPOSE

Minimizing the future risk of asthma exacerbation (AE) is one of the main goals of asthma management. We investigated prognostic factors for risk of severe AE (SAE) in a real-world clinical setting.

METHODS

This is an observational study evaluating subjects who were diagnosed with asthma and treated with anti-asthmatic medications from January 1995 to June 2018. Risk factors for SAE were analyzed in 2 treatment periods (during the initial 2 years and the following 3-10 years of treatment) using the big data of electronic medical records.

RESULTS

In this study, 5,058 adult asthmatics were enrolled; 1,335 (28.64%) experienced ≥ 1 SAE during the initial 2 years of treatment. Female sex, higher peripheral eosinophil/basophil counts, and lower levels of forced expiratory volume in 1 second (FEV1; %) were factors predicting the risk of SAEs (P < 0.001 for all). Higher serum total immunoglobulin E levels increased the risk of SAEs among the patients having ≤ 2 SAEs (P = 0.025). Patients with more frequent SAEs during the initial 2 years of treatment had significantly higher risks of SAEs during the following years of treatment (P < 0.001, for all) (patients with ≥ 4 SAEs, odds ratio [OR], 29.147; those with 3 SAEs, OR, 14.819; those with 2 SAEs, OR, 9.867; those with 1 SAE, OR, 5.116), had higher maintenance doses of systemic steroids, and showed more gradual decline in FEV1 (%) and FEV1/forced vital capacity levels maintained during the following years of treatment (P < 0.001 for all).

CONCLUSIONS

Asthmatics having risk factors for SAEs (female sex, higher peripheral eosinophil/basophil counts, and lower FEV1) should be strictly monitored to prevent future risk and improve clinical outcomes.

Beyond eosinophilia: inflammatory patterns in patients with asthma

Background: Recently, inflammatory cell ratios have gained importance as useful indicators in the categorization of asthma.Objective: We compared the concentration of white blood cells in peripheral blood, as well as their respective inflammatory cell ratios, between patients with asthma and a healthy control group.Methods: We performed cross-sectional analyses of the data obtained from 53 adult patients with asthma and 109 adult controls. In our study, we estimated and compared the following inflammatory cell ratios: Neutrophil-Lymphocyte Ratio (NLR), Eosinophil-Lymphocyte Ratio (ELR), Eosinophil-Neutrophil Ratio (ENR), Eosinophil-Monocyte Ratio (EMR), and Platelet-Lymphocyte Ratio (PLR). The magnitude of association was quantified with the odds ratio.Results: In both groups, the average age was 33 years. In asthmatic patients, we obtained the following results: eosinophils ≥ 400 cells/µl, accounted for 37.7%; basophils ≥ 110 cells/µl, comprised 37.7%; and monocytes < 320 cells/µl, reached 11.3%. In the control group, the results were as follows: 4.6%, 9.2% and 0.9%, respectively. When compared to the control group, asthmatic patients had higher odds of eosinophils ≥ 400 cells/µl (OR = 12.61, p < 0.0001); higher odds of basophils ≥ 110 cells/µl (OR = 6.00, p < 0.0001); and increased odds of monocytes < 320 cells/µl (OR = 13.79, p = 0.017). NLR did not differ between our two groups; however, ELR, ENR, EMR and PLR were significantly higher in the asthma group.Conclusions: Overall, patients with asthma have a higher concentration of eosinophils and basophils, fewer monocytes in their blood, and higher ratios of increased chronic inflammation.

Role of myeloid cells in the regulation of group 2 innate lymphoid cell-mediated allergic inflammation

Group 2 innate lymphoid cells (ILC2s) are an important component of the innate immune system that execute important effector functions at barrier surfaces, such as lung and skin. Like T helper type 2 cells, ILC2s are able to release high amounts of type 2 cytokines that are essential in inducing allergic inflammation and eliminating helminth infections. The past few years have contributed to our better understanding of the interactions between ILC2s and other cells of the immune system via soluble factors or in a cell-cell contact manner. Myeloid cells, including mononuclear leukocytes and polymorphonuclear leukocytes, are excellent sensors of tissue damage and infection and can influence ILC2 responses in the process of allergic inflammation. In this review, we summarize recent insights on how myeloid cell subsets regulate ILC2 activation with focus on soluble factors in the context of allergic inflammation.

Relationship of sputum mast cells with clinical and inflammatory characteristics of asthma

BACKGROUND

Mast cells (MCs) are innate immune cells that regulate atopic and non-atopic inflammation in the airways. MCs play a critical role in the pathogenesis of asthma, yet their relationship to airway and systemic inflammation and clinical characteristics of asthma is poorly understood.

OBJECTIVE

To quantify MCs in induced sputum samples and understand their relationship to airway and circulatory immune cells, and clinical variables in asthma.

METHODS

We employed flow cytometry of sputum samples to quantify MCs, basophils and other immune cells in 51 participants (45 asthma and 6 non-asthma controls). Relationship of MCs to airway (n = 45) and blood (n = 19) immune cells, participant demographics, asthma history, spirometry and airways hyperresponsiveness (AHR) to hypertonic saline was determined by correlation and comparison of cut-off-based sputum MC high vs low participants.

RESULTS

Mast cells, basophils and eosinophils were increased in asthma vs non-asthma control sputum. In asthma sputum, MCs, basophils and eosinophils were significantly intercorrelated, and MCs and basophils were elevated in participants with eosinophilic asthma. MCs and basophils, but not eosinophils, correlated with AHR. Sputum MC high asthma was characterized by an increased proportion of participants with uncontrolled asthma and reduced FEV₁ and FVC. Trends towards similar clinical associations with elevated MCs were observed in a paucigranulocytic subpopulation (n = 15) lacking airway eosinophilia or neutrophilia. Receiver operator characteristic (ROC) analysis showed peripheral blood eosinophil (PBE) count predicted elevated sputum eosinophils and basophils, but not MCs.

CONCLUSIONS AND CLINICAL RELEVANCE

Sputum MCs are elevated in asthma, and their measurement may be useful as they relate to key clinical features of asthma (spirometry, asthma control, AHR). PBE count did not predict airway MC status, suggesting direct measurement of airway MCs by sensitive methods such as flow cytometry should be further developed.

Severe eosinophilic asthma and aspirin-exacerbated respiratory disease associated to eosinophilic gastroenteritis treated with mepolizumab: a case report

Background

Mepolizumab (MEP) is the first anti Interleukin (IL)-5 add-on therapy approved for the treatment of severe refractory eosinophilic asthma.

Case presentation

We describe here the case of a 49 years-old woman with Aspirin-exacerbated respiratory disease (AERD), chronic rhinosinusitis, nasal polyposis and eosinophilic gastroenteritis successfully treated with MEP. Several laboratory and clinical items improved during therapy; moreover MEP showed to be useful as steroid sparing agent.

Conclusions

This case supports that the use of mepolizumab can be effective also in other eosinophilic conditions different from asthma and this opens to new therapeutic perspectives.

Progress in understanding hypersensitivity reactions to nonsteroidal anti-inflammatory drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs), the medications most commonly used for treating pain and inflammation, are the main triggers of drug hypersensitivity reactions. The latest classification of NSAIDs hypersensitivity by the European Academy of Allergy and Clinical Immunology (EAACI) differentiates between cross-hypersensitivity reactions (CRs), associated with COX-1 inhibition, and selective reactions, associated with immunological mechanisms. Three phenotypes fill into the first group: NSAIDs-exacerbated respiratory disease, NSAIDs-exacerbated cutaneous disease and NSAIDs-induced urticaria/angioedema. Two phenotypes fill into the second one: single-NSAID-induced urticaria/angioedema/anaphylaxis and single-NSAID-induced delayed reactions. Diagnosis of NSAIDs hypersensitivity is hampered by different factors, including the lack of validated in vitro biomarkers and the uselessness of skin tests. The advances achieved over recent years recommend a re-evaluation of the EAACI classification, as it does not consider other phenotypes such as blended reactions (coexistence of cutaneous and respiratory symptoms) or food-dependent NSAID-induced anaphylaxis. In addition, it does not regard the natural evolution of phenotypes and their potential interconversion, the development of tolerance over time or the role of atopy. Here, we address these topics. A state of the art on the underlying mechanisms and on the approaches for biomarkers discovery is also provided, including genetic studies and available information on transcriptomics and metabolomics.

Immunologic mechanisms in asthma

Asthma is a chronic airway disease, which affects more than 300 million people. The pathogenesis of asthma exhibits marked heterogeneity with many phenotypes defining visible characteristics and endotypes defining molecular mechanisms. With the evolution of novel biological therapies, patients, who do not-respond to conventional asthma therapy require novel biologic medications, such as anti-IgE, anti-IL-5 and anti-IL4/IL13 to control asthma symptoms. It is increasingly important for physicians to understand immunopathology of asthma and to characterize asthma phenotypes. Asthma is associated with immune system activation, airway hyperresponsiveness (AHR), epithelial cell activation, mucus overproduction and airway remodeling. Both innate and adaptive immunity play roles in immunologic mechanisms of asthma. Type 2 asthma with eosinophilia is a common phenotype in asthma. It occurs with and without visible allergy. The type 2 endotype comprises; T helper type 2 (Th2) cells, type 2 innate lymphoid cells (ILC2), IgE-secreting B cells and eosinophils. Eosinophilic nonallergic asthma is ILC2 predominated, which produces IL-5 to recruit eosinophil into the mucosal airway. The second major subgroup of asthma is non-type 2 asthma, which contains heterogeneous group of endoypes and phenotypes, such as exercise-induced asthma, obesity induced asthma, etc. Neutrophilic asthma is not induced by allergens but can be induced by infections, cigarette smoke and pollution. IL-17 which is produced by Th17 cells and type 3 ILCs, can stimulate neutrophilic airway inflammation. Macrophages, dendritic cells and NKT cells are all capable of producing cytokines that are known to contribute in allergic and nonallergic asthma. Bronchial epithelial cell activation and release of cytokines, such as IL-33, IL-25 and TSLP play a major role in asthma. Especially, allergens or environmental exposure to toxic agents, such as pollutants, diesel exhaust, detergents may affect the epithelial barrier leading to asthma development. In this review, we focus on the immunologic mechanism of heterogenous asthma phenotypes.

Novel Biological Therapies in Severe Asthma: Targeting the Right Trait

Asthma is a heterogeneous disease characterized by chronic airway inflammation that results in a wide spectrum of clinical manifestations. Patients with severe asthma represent a substantial share of consumption of healthcare resources and hospitalization. Moreover, these patients are at risk of increased morbidity and mortality. Recently, several phenotypes and endotypes of asthma have been identified. The identification of specific subtypes of asthma is fundamental for optimizing the clinical benefit of novel treatments. Although in most patients the disease can be controlled by some combination of pharmacologic agents, in some 5-10% of patients the disease remains uncontrolled. Several monoclonal antibodies (mAbs) targeting pathogenetic molecules (e.g., IgE, IL-5, IL- 5Rα, IL-4, IL-13, TSLP) are currently available or under development for the treatment of different forms of severe type 2 asthma. The identification of diagnostic and predictive biomarkers (e.g., IgE, blood eosinophil count, FeNO, periostin, etc.) has revolutioned the field of targeted therapy in severe asthma. Monoclonal antibodies targeting Th2-driven inflammation are generally safe in adult patients with moderate-to-severe asthma. The long-term safety of these biologics is a relevant issue that should be addressed. Unfortunately, little is known about non-type 2 asthma. Further studies are needed to identify biomarkers to guide targeted therapies of different forms of non-type 2 asthma.

Mixed cell type in airway inflammation is the dominant phenotype in asthma patients with severe chronic rhinosinusitis

BACKGROUND

Asthma often coexists with chronic rhinosinusitis (CRS). Recent studies revealed that sinus inflammation in asthmatic patients was related to eosinophilic inflammation. However, the relationship between the severity of CRS and four different sputum inflammatory phenotypes as defined by the proportion of eosinophils and neutrophils is unknown. The aim of this study was to examine the impact of the severity of CRS on lower airway and systemic inflammation in asthmatic patients.

METHODS

We enrolled 57 adult asthmatic patients who underwent sinus computed tomography (CT). The severity of CRS was evaluated by the Lund-Mackay score (LMS). The induced sputum inflammatory phenotype was defined by eosinophils (≥/<2%) and neutrophils (≥/<60%). Peripheral blood mononuclear cells (PBMC) were collected to examine cytokine productions.

RESULTS

The median LMS of subjects was 6 (interquartile range, 0-11.5). The sputum inflammatory cell phenotype was categorized as paucicellular (n = 14), neutrophilic (n = 11), eosinophilic (n = 20), or mixed (n = 12). LMS was positively correlated with the percentage of blood eosinophils, sputum eosinophils, and mean fluorescence intensity (MFI) of IL-5 on CD4⁺ T cells. In the severe CRS group (LMS, 12-24), the number of mixed cellular phenotypes was higher than that in the group without CRS (LMS, 0-4) and mild-to-moderate CRS group (LMS, 5-11).

CONCLUSIONS

In asthmatic patients with severe CRS, the proportion of the mixed cellular inflammatory phenotype was increased as well as eosinophilic inflammation.

Mast Cell-Mediated Orchestration of the Immune Responses in Human Allergic Asthma: Current Insights

Improving the lung function after experimental allergen challenge by blocking of mast cell (MC) mediators and the capability of MC mediators (including histamine, prostaglandin (PG) D2, and leukotriene (LT) C4) in induction of mucosal edema, bronchoconstriction, and mucus secretion provide evidence that MCs play a key role in pathophysiology of asthma. In asthma, the number of MCs increases in the airways and infiltration of MCs in a variety of anatomical sites including the epithelium, the submucosal glands, and the smooth muscle bundles occurs. MC localization within the ASM is accompanied with the hypertrophy and hyperplasia of the layer, and smooth muscle dysfunction that is mainly observed in forms of bronchial hyperresponsiveness, and variable airflow obstruction. Owing to the expression of a wide range of surface receptors and releasing various cytoplasmic mediators, MCs orchestrate the pathologic events of the disease. MC-released preformed mediators including chymase, tryptase, and histamine and de novo synthesized mediators such as PGD2, LTC4, and LTE4 in addition of cytokines mainly TGFβ1, TSLP, IL-33, IL-4, and IL-13 participate in pathogenesis of asthma. The release of MC mediators and MC/airway cell interactions during remodeling phase of asthma results in persistent cellular and structural changes in the airway wall mainly epithelial cell shedding, goblet cell hyperplasia, hypertrophy of ASM bundles, fibrosis in subepithelial region, abnormal deposition of extracellular matrix (ECM), increased tissue vascularity, and basement membrane thickening. We will review the current knowledge regarding the participation of MCs in each stage of asthma pathophysiology including the releasing mediators and their mechanism of action, expression of receptors by which they respond to stimuli, and finally the pharmaceutical products designed based on the strategy of blocking MC activation and mediator release.

A sputum 6-gene signature predicts future exacerbations of poorly controlled asthma

BACKGROUND

Improved diagnostic tools for predicting future exacerbation frequency in asthmatic patients are required. A sputum gene expression signature of 6 biomarkers (6-gene signature [6GS], including Charcot-Leyden crystal galectin [CLC]; carboxypeptidase 3 [CPA3]; deoxyribonuclease 1-like 3 [DNASE1L3]; alkaline phosphatase, liver/bone/kidney [ALPL]; CXCR2; and IL1B) predicts inflammatory and treatment response phenotypes in patients with stable asthma. Recently, we demonstrated that azithromycin (AZM) add-on treatment in patients with uncontrolled moderate-to-severe asthma significantly reduced asthma exacerbations (AMAZES clinical trial).

OBJECTIVES

We sought to test whether the 6GS predicts future exacerbation and inflammatory phenotypes in a subpopulation of AMAZES and to test the effect of AZM therapy on 6GS expression and prognostic capacity.

METHODS

One hundred forty-two patients (73 placebo-treated and 69 AZM-treated patients) had sputum stored for quantitative PCR of 6GS markers at baseline and after 48 weeks of treatment. Logistic regression and receiver operating characteristic and area under the curve (AUC) determination were performed on baseline measures, and in an exploratory analysis the predictive value of the 6GS was compared with conventional biomarkers for exacerbation and inflammatory phenotypes.

RESULTS

The 6GS significantly predicted all future exacerbation phenotypes tested. Calculated AUCs for the 6GS were significantly greater than AUCs for peripheral blood eosinophil counts, sputum neutrophil counts, and combined sputum eosinophil and neutrophil counts. 6GS AUCs were also numerically but not significantly greater than those for fractional exhaled nitric oxide values and sputum eosinophil counts. AZM treatment altered neither 6GS expression nor the predictive capacity of the 6GS for future exacerbation phenotypes. The 6GS was a significant predictor of airway inflammatory phenotype in this population.

CONCLUSION

We demonstrate that a sputum gene signature can predict future exacerbation phenotypes of asthma, with the greatest biomarker performance in identifying those who would experience frequent severe exacerbations. AZM therapy did not modify 6GS expression or biomarker performance, suggesting the therapeutic action of AZM is independent of 6GS-related inflammatory pathways.

Human mast cells and basophils-How are they similar how are they different?

Mast cells and basophils are key contributors to allergies and other inflammatory diseases since they are the most prominent source of histamine as well as numerous additional inflammatory mediators which drive inflammatory responses. However, a closer understanding of their precise roles in allergies and other pathological conditions has been marred by the considerable heterogeneity that these cells display, not only between mast cells and basophils themselves but also across different tissue locations and species. While both cell types share the ability to rapidly degranulate and release histamine following high-affinity IgE receptor cross-linking, they differ markedly in their ability to either react to other stimuli, generate inflammatory eicosanoids or release immunomodulating cytokines and chemokines. Furthermore, these cells display considerable pharmacological heterogeneity which has stifled attempts to develop more effective anti-allergic therapies. Mast cell- and basophil-specific transcriptional profiling, at rest and after activation by innate and adaptive stimuli, may help to unravel the degree to which these cells differ and facilitate a clearer understanding of their biological functions and how these could be targeted by new therapies.

Highlights and recent developments in airway diseases in EAACI journals (2017)

The European Academy of Allergy and Clinical Immunology (EAACI) owns three journals: Allergy, Pediatric Allergy and Immunology and Clinical and Translational Allergy. One of the major goals of EAACI is to support health promotion in which prevention of allergy and asthma plays a critical role and to disseminate the knowledge of allergy to all stakeholders including the EAACI junior members. There was substantial progress in 2017 in the identification of basic mechanisms of allergic and respiratory disease and the translation of these mechanisms into clinics. Better understanding of molecular and cellular mechanisms, efforts for the development of biomarkers for disease prediction, novel prevention and intervention studies, elucidation of mechanisms of multimorbidies, entrance of new drugs in the clinics as well as recently completed phase three clinical studies and publication of a large number of allergen immunotherapy studies and metaanalyses have been the highlights of the last year.

Therapeutic antibodies: A new era in the treatment of respiratory diseases?

Respiratory diseases affect millions of people worldwide, and account for significant levels of disability and mortality. The treatment of lung cancer and asthma with therapeutic antibodies (Abs) is a breakthrough that opens up new paradigms for the management of respiratory diseases. Antibodies are becoming increasingly important in respiratory medicine; dozens of Abs have received marketing approval, and many more are currently in clinical development. Most of these Abs target asthma, lung cancer and respiratory infections, while very few target chronic obstructive pulmonary disease - one of the most common non-communicable causes of death - and idiopathic pulmonary fibrosis. Here, we review Abs approved for or in clinical development for the treatment of respiratory diseases. We notably highlight their molecular mechanisms, strengths, and likely future trends.

Important and specific role for basophils in acute allergic reactions

IgE‐mediated allergic reactions involve the activation of effector cells, predominantly through the high‐affinity IgE receptor (FcεRI) on mast cells and basophils. Although the mast cell is considered the major effector cell during acute allergic reactions, more recent studies indicate a potentially important and specific role for basophils and their migration which occurs rapidly upon allergen challenge in humans undergoing anaphylaxis. We review the evidence for a role of basophils in contributing to clinical symptoms of anaphylaxis and discuss the possibility that basophil trafficking during anaphylaxis might be a pathogenic (to target organs) or protective (preventing degranulation in circulation) response. Finally, we examine the potential role of basophils in asthma exacerbations. Understanding the factors that regulate basophil trafficking and activation might lead to new diagnostic and therapeutic strategies in anaphylaxis and asthma.