Targeting of eosinophils in asthma

Severity of adult-onset asthma - a matter of blood neutrophils and severe obesity

BACKGROUND

Adult-onset asthma is associated with a poor treatment response. The aim was to study associations between clinical characteristics, asthma control and treatment in adult-onset asthma.

METHODS

Previous participants within the population-based Obstructive Lung Disease in Northern Sweden studies (OLIN) were in 2019-2020 invited to clinical examinations including structured interviews, spirometry, fractional exhaled nitric oxide (FeNO), skin prick test and blood sampling. In total, n = 251 individuals with adult-onset asthma (debut >15 years of age) were identified. Uncontrolled asthma was defined according to ERS/ATS and treatment step according to GINA (2019).

RESULTS

Among individuals with uncontrolled asthma (34%), severe obesity (16.3% vs 7.9%, p = 0.041) and elevated levels of blood neutrophils, both regarding mean level of blood neutrophils (4.25*109/L vs 3.67*109/L, p = 0.003), and proportions with ≥4*109/L (49.4% vs 33.3%, p = 0.017) and ≥5*109/L (32.1% vs 13.7%, p < 0.001) were more common than among those with controlled asthma. Adding the dimension of GINA treatment step 1-5, individuals with uncontrolled asthma on step 4-5 treatment had the highest proportions of blood neutrophils ≥5*109/L (45.5%), severe obesity (BMI≥35, 26.1%), dyspnea (mMRC≥2) (34.8%), and most impaired lung function in terms of FEV1%<80% of predicted (42.9%), FEV1

CONCLUSION

This study indicates that in adult-onset asthma, primarily non-type-2 characteristics such as obesity and blood neutrophils associate with poor asthma control and higher doses of inhaled corticosteroids.

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Key Words

• Body mass index
• Eosinophils
• Epidemiology
• Follow-up studies
• Neutrophils
• Sweden

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MESH Headings

• Humans
• Adult
• Neutrophils
• Obesity, Morbid/complications
• Nitric Oxide/therapeutic use
• Asthma/drug therapy
• Eosinophils
• Obesity/complications

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Affiliation(s)

Sofia Winsa-Lindmark Umeå University, Department of Public Health and Clinical Medicine, Section for Sustainable Health/The OLIN Unit, Sweden.
Caroline Stridsman Umeå University, Department of Public Health and Clinical Medicine, The OLIN Unit, Sweden
Axel Sahlin Umeå University, Department of Public Health and Clinical Medicine, Section for Sustainable Health/The OLIN Unit, Sweden
Linnea Hedman Umeå University, Department of Public Health and Clinical Medicine, Section for Sustainable Health/The OLIN Unit, Sweden
Nikolai Stenfors Umeå University, Department of Public Health and Clinical Medicine, The OLIN Unit, Sweden
Tomi Myrberg Umeå University, Department of Surgical and Perioperative Sciences, Anesthesiology and Intensive Care Medicine, Sweden
Anne Lindberg Umeå University, Department of Public Health and Clinical Medicine, The OLIN Unit, Sweden
Eva Rönmark Umeå University, Department of Public Health and Clinical Medicine, Section for Sustainable Health/The OLIN Unit, Sweden
Helena Backman Umeå University, Department of Public Health and Clinical Medicine, Section for Sustainable Health/The OLIN Unit, Sweden

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Can eosinophilia and neutrophil-lymphocyte ratio predict hospitalization in asthma exacerbation?

OBJECTIVE

Asthma is one of the most common diseases amongst children. Blood eosinophil count and neutrophil-lymphocyte ratio (NLR) are known as markers for phenotyping asthma. This study was performed to investigate blood eosinophil count and NLR as predictors of hospitalization in pediatric asthma exacerbations.

DATA SOURCES AND STUDY SELECTIONS

In this cross-sectional study, children admitted to hospital ward for more severe asthma exacerbation were compared with non-hospitalized children with moderate to severe asthma exacerbation whose asthma exacerbation was managed in emergency department or outpatient clinic. We investigated patients' characteristic and factors associated with hospitalization.

RESULTS

A total of 211 children with moderate to severe asthma exacerbation (mean age [Formula: see text] years old) were enrolled in the study including 91 hospitalized patients and 120 non-hospitalized patients. For the prediction of hospitalization, an ROC Curve analysis was performed and revealed a cut-off of 298 cells/µL and 2.52 of blood eosinophil count and NLR, respectively. In multivariate analysis, not using an asthma action plan (OR 2.22, 95% CI 1.09-4.49; P = 0.027), a blood eosinophil count [Formula: see text] 298 (OR 8.79, 95% CI 4.44-17.4; P < 0.001) and an NLR [Formula: see text] 2.52 (OR 2.13, 95% CI 1.09-4.14; P = 0.027) were associated with hospitalization.

CONCLUSION

Blood eosinophil count and NLR were found to be higher in hospitalized children with more severe asthma exacerbation compared to non-hospitalized patients. These markers can be indicators for asthma exacerbation severity.

Plasma based targeted metabolomic analysis reveals alterations of phosphatidylcholines and oxidative stress markers in guinea pig model of allergic asthma

Bronchial asthma is one of the most common, chronic respiratory diseases, characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyperresponsiveness and airway remodelling; with many cells and mediators involved. Metabolomics is a relatively new field in "omics" sciences enabling the identification of metabolome for better diagnostics and studying of diseases phenotype. The aim of this study was to investigate the role of targeted metabolomics study for better understanding of the bronchial asthma pathophysiology and finding potential biomarkers in experimental models of eosinophilic inflammation. Plasma level of 185 metabolites was measured with the AbsoluteIDQ™ p180 kit in guinea pigs with experimentally-induced allergic inflammation (n = 15) compared to naïve non-sensitised and non-challenged controls (n = 18). Of the 185 metabolites identified in plasma, 22 were significantly different and changed in ovalbumin sensitised animals. Plasma level of 13 phosphatidylcholines with saturated and unsaturated long-chain fatty acids, total phosphatidylcholines count, carnitine, symmetric dimethylarginine and its ratio to total unmodified arginine, and kynurenine to tryptophan ratio were found to be decreased, while phospholipase A2 activity indicator, tryptophan, taurine and ratio of methionine sulfoxide to unmodified methionine were found to be increased in sensitised guinea pigs compared to naïve controls. Targeted metabolomic analysis revealed significant differences in plasma metabolome of sensitised guinea pigs. Our observations point to the activation of inflammatory and immune pathways, as well as the involvement of oxidative stress.

Immune response patterns in non-communicable inflammatory skin diseases

Non-communicable inflammatory skin diseases (ncISD) such as psoriasis or atopic eczema are a major cause of global disease burden. Due to their impact and complexity, ncISD represent a major challenge of modern medicine. Dermatology textbooks describe more than 100 different ncISD based on clinical phenotype and histological architecture. In the last decades, this historical description was complemented by increasing molecular knowledge - and this knowledge is now being translated into specific therapeutics. Combining the enormous advances made in lymphocyte immunology and molecular genetics with clinical and histological phenotyping reveals six immune response patterns of the skin - type I immune cells cause the lichenoid pattern characterized by immune-mediated cell death of keratinocytes; type II immune cells underlie the eczematous pattern with impaired epidermal barrier, infection and eosinophils as well as the bullous pattern with loss of epithelial integrity; Th17 cells and ILC3 mediate the psoriatic pattern characterized by acanthosis, high metabolic activity and neutrophils; dysbalance of regulatory T cells causes either the fibrogenic pattern with rarefication of cells and dermal thickening or the granulomatous pattern defined by formation of granulomas. With more and more specific therapeutic agents approved, classifying ncISD also according to their immune response pattern will become highly relevant. This review defines the six immune response patterns of ncISD and highlights therapeutic strategies targeting key lymphocyte mediators.

CSL311, a novel, potent, therapeutic monoclonal antibody for the treatment of diseases mediated by the common β chain of the IL-3, GM-CSF and IL-5 receptors

The β common-signaling cytokines interleukin (IL)-3, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-5 stimulate pro-inflammatory activities of haematopoietic cells via a receptor complex incorporating cytokine-specific α and shared β common (βc, CD131) receptor. Evidence from animal models and recent clinical trials demonstrate that these cytokines are critical mediators of the pathogenesis of inflammatory airway disease such as asthma. However, no therapeutic agents, other than steroids, that specifically and effectively target inflammation mediated by all 3 of these cytokines exist. We employed phage display technology to identify and optimize a novel, human monoclonal antibody (CSL311) that binds to a unique epitope that is specific to the cytokine-binding site of the human βc receptor. The binding epitope of CSL311 on the βc receptor was defined by X-ray crystallography and site-directed mutagenesis. CSL311 has picomolar binding affinity for the human βc receptor, and at therapeutic concentrations is a highly potent antagonist of the combined activities of IL-3, GM-CSF and IL-5 on primary eosinophil survival in vitro. Importantly, CSL311 inhibited the survival of inflammatory cells present in induced sputum from human allergic asthmatic subjects undergoing allergen bronchoprovocation. Due to its high potency and ability to simultaneously suppress the activity of all 3 β common cytokines, CSL311 may provide a new strategy for the treatment of chronic inflammatory diseases where the human βc receptor is central to pathogenesis. The coordinates for the βc/CSL311 Fab complex structure have been deposited with the RCSB Protein Data Bank (PDB 5DWU).

Eosinophil-derived neurotoxin, elastase, and cytokine profile in effusion from eosinophilic otitis media

BACKGROUND

Eosinophilic otitis media (EOM) is an intractable disease characterized by a remarkably viscous effusion and accumulation of numerous eosinophils in both the middle ear effusion and the mucosa. The key factors in EOM pathogenesis remain unclear. The purpose of this study is to identify the important factors involved in EOM pathogenesis.

METHODS

Middle ear effusion samples were collected from 12 patients with EOM and 9 patients with secretory otitis media (SOM), as controls. Multiple cytokines in the effusion were measured using a Bio-Plex™ Human Cytokine 27-Plex panel. Eosinophil-derived neurotoxin (EDN) and elastase were measured by ELISA. The concentrations of EDN, elastase, and each cytokine were compared between the EOM and SOM groups. Furthermore, in the EOM group, each cytokine was examined for correlation with EDN and elastase.

RESULTS

EDN and elastase concentrations were significantly higher in the EOM group than in the SOM group (p < 0.05). IL-5, IL-1β, MIP-1α, G-CSF, IL-1ra, IL-4, IFN-γ, MIP-1β, IL-10, TNF-α, VEGF, and IL-2 concentration was significantly higher in the EOM group than in the SOM group (p < 0.05). Significant positive correlations were found between EDN and IL-1ra, IL-2, IL-5, IL-9, IL-13, eotaxin, MIP-1α, PDGF-BB, and RANTES in the EOM group (p < 0.05).

CONCLUSIONS

Our study showed that IL-5, IL-2, MIP-1α, and IL-1ra are the important factors involved in EOM pathogenesis. Furthermore, not only eosinophil, but also neutrophil are involved in middle ear inflammation of EOM.

Ovalbumin enhances YKL-40, IL-5, GM-CSF, and eotaxin expression simultaneously in primarily cultured mouse tracheal epithelial cells

Epithelial inflammation and eosinophil infiltration are crucial for the pathogenesis of asthma. Many inflammatory mediators, such as YKL-40, interleukin -5 (IL-5), granulocyte-macrophage colony-stimulating factor (GM-CSF), and eotaxin, are important for the development of allergic airway inflammation. This study is aimed at investigating the impact of treatment with ovalbumin (OVA) on the levels of those inflammatory mediators in primarily cultured mouse tracheal epithelial cells. Mouse tracheal epithelial cells were isolated and identified by immunofluorescent staining; the isolated mouse tracheal epithelial cells expressed cytokeratins. Treatment with OVA for 24 or 48 h significantly increased the relative levels of YKL-40, IL-5, GM-CSF, and eotaxin mRNA transcripts and YKL-40, IL-5, GM-CSF, and eotaxin proteins secreted in the supernatants of cultured cells, as compared with that in the untreated control cells (P < 0.01, P < 0.05, respectively). The levels of YKL-40 expression were correlated positively with the levels of IL-5, GM-CSF, and eotaxin expression in the OVA-treated cells. These data indicated that treatment with OVA simultaneously enhanced YKL-40, IL-5, GM-CSF, and eotaxin expression in the cultured mouse tracheal epithelial cells in vitro. These inflammatory mediators may synergistically contribute to the pathogenesis of allergic inflammation, and this study may help to understand the role of YKL-40 in the pathogenesis of asthma.

Eosinophilic inflammation in allergic asthma

Eosinophils are circulating granulocytes involved in pathogenesis of asthma. A cascade of processes directed by Th2 cytokine producing T-cells influence the recruitment of eosinophils into the lungs. Furthermore, multiple elements including interleukin (IL)-5, IL-13, chemoattractants such as eotaxin, Clara cells, and CC chemokine receptor (CCR)3 are already directly involved in recruiting eosinophils to the lung during allergic inflammation. Once recruited, eosinophils participate in the modulation of immune response, induction of airway hyperresponsiveness and remodeling, characteristic features of asthma. Various types of promising treatments for reducing asthmatic response are related to reduction in eosinophil counts both in human and experimental models of pulmonary allergic inflammation, showing that the recruitment of these cells really plays an important role in the pathophysiology of allergic diseases such asthma.

Th2 cytokine antagonists: potential treatments for severe asthma

INTRODUCTION

Asthma is a major disease burden worldwide. Treatment with steroids and long acting β-agonists effectively manage symptoms in many patients but do not treat the underlying cause of disease and have serious side effects when used long term and in children. Therapies targeting the underlying causes of asthma are urgently needed. T helper type 2 (Th2) cells and the cytokines they release are clinically linked to the presentation of all forms of asthma. They are the primary drivers of mild to moderate and allergic asthma. They also play a pathogenetic role in exacerbations and more severe asthma though other factors are also involved. Much effort using animal models and human studies has been dedicated to the identification of the pathogenetic roles of these cells and cytokines and whether inhibition of their activity has therapeutic benefit in asthma.

AREAS COVERED

We discuss the current status of Th2 cytokine antagonists for the treatment of asthma. We also discuss the potential for targeting Th2-inducing cytokines, Th2 cell receptors and signaling as well as the use of Th2 cell antagonists, small interfering oligonucleotides, microRNAs, and combination therapies.

EXPERT OPINION

Th2 antagonists may be most effective in particular asthma subtypes/endotypes where specific cytokines are known to be active through the analysis of biomarkers. Targeting common receptors and pathways used by these cytokines may have additional benefit. Animal models have been valuable in identifying therapeutic targets in asthma, however the results from such studies need to be carefully interpreted and applied to appropriately stratified patient cohorts in well-designed clinical studies and trials.