Type I IL-1 receptor (IL-1RI) as potential new therapeutic target for bronchial asthma

Effect of air pollution on asthma

Asthma is a chronic inflammatory airway disease characterized by respiratory symptoms, variable airflow obstruction, bronchial hyperresponsiveness, and airway inflammation. Exposure to air pollution has been linked to an increased risk of asthma development and exacerbation. This review aims to comprehensively summarize recent data on the impact of air pollution on asthma development and exacerbation. Specifically, we reviewed the effects of air pollution on the pathogenic pathways of asthma, including type 2 and non-type 2 inflammatory responses, and airway epithelial barrier dysfunction. Air pollution promotes the release of epithelial cytokines, driving TH2 responses, and induces oxidative stress and the production of proinflammatory cytokines. The enhanced type 2 inflammation, furthered by air pollution-induced dysfunction of the airway epithelial barrier, may be associated with the exacerbation of asthma. Disruption of the TH17/regulatory T cell balance by air pollutants is also related to asthma exacerbation. As the effects of air pollution exposure may accumulate over time, with potentially stronger impacts in the development of asthma during certain sensitive life periods, we also reviewed the effects of air pollution on asthma across the lifespan. Future research is needed to better characterize the sensitive period contributing to the development of air pollution-induced asthma and to map air pollution-associated epigenetic biomarkers contributing to the epigenetic ages onto asthma-related genes.

Tailored Biologics Selection in Severe Asthma

The management of severe asthma presents a significant challenge in asthma treatment. Over the past few decades, remarkable progress has been made in developing new treatments for severe asthma, primarily in the form of biological agents. These advances have been made possible through a deeper understanding of the underlying pathogenesis of asthma. Most biological agents focus on targeting specific inflammatory pathways known as type 2 inflammation. However, recent developments have introduced a new agent targeting upstream alarmin signaling pathways. This opens up new possibilities, and it is anticipated that additional therapeutic agents targeting various pathways will be developed in the future. Despite this recent progress, the mainstay of asthma treatment has long been inhalers. As a result, the guidelines for the appropriate use of biological agents are not yet firmly established. In this review, we aim to emphasize the current state of biological therapy for severe asthma and provide insights into its future prospects.

Lignosus rhinocerotis extract ameliorates airway inflammation and remodelling via attenuation of TGF-β1 and Activin A in a prolonged induced allergic asthma model

Allergic asthma is associated with chronic airway inflammation and progressive airway remodelling. The sclerotium of Lignosus rhinocerotis (Cooke) Ryvarden (Tiger Milk mushroom) is used traditionally to treat various illnesses, including asthma in Southeast Asia. This study was carried out to evaluate the effect of L. rhinocerotis extract (LRE) on airway inflammation and remodelling in a chronic model of asthma. The present study investigated the therapeutic effects of LRE on airway inflammation and remodelling in prolonged allergen challenged model in allergic asthma. Female Balb/C mice were sensitised using ovalbumin (OVA) on day 0 and 7, followed by OVA-challenged (3 times/week) for 2, 6 and 10 weeks. LRE (125, 250, 500 mg/kg) were administered by oral gavage one hour after every challenge. One group of mice were left untreated after the final challenge for two weeks. LRE suppressed inflammatory cells and Th2 cytokines (IL-4, IL-5 and IL-13) in BALF and reduced IgE level in the serum. LRE also attenuated eosinophils infiltration and goblet cell hyperplasia in the lung tissues; as well as ameliorated airway remodelling by reducing smooth muscle thickness and reducing the expressions of TGF-β1 and Activin A positive cell in the lung tissues. LRE attenuated airway inflammation and remodelling in the prolonged allergen challenge of allergic asthma model. These findings suggest the therapeutic potential of LRE as an alternative for the management of allergic asthma.

Mendelian randomization and genetic colocalization infer the effects of the multi-tissue proteome on 211 complex disease-related phenotypes

BACKGROUND

Human proteins are widely used as drug targets. Integration of large-scale protein-level genome-wide association studies (GWAS) and disease-related GWAS has thus connected genetic variation to disease mechanisms via protein. Previous proteome-by-phenome-wide Mendelian randomization (MR) studies have been mainly focused on plasma proteomes. Previous MR studies using the brain proteome only reported protein effects on a set of pre-selected tissue-specific diseases. No studies, however, have used high-throughput proteomics from multiple tissues to perform MR on hundreds of phenotypes.

METHODS

Here, we performed MR and colocalization analysis using multi-tissue (cerebrospinal fluid (CSF), plasma, and brain from pre- and post-meta-analysis of several disease-focus cohorts including Alzheimer disease (AD)) protein quantitative trait loci (pQTLs) as instrumental variables to infer protein effects on 211 phenotypes, covering seven broad categories: biological traits, blood traits, cancer types, neurological diseases, other diseases, personality traits, and other risk factors. We first implemented these analyses with cis pQTLs, as cis pQTLs are known for being less prone to horizontal pleiotropy. Next, we included both cis and trans conditionally independent pQTLs that passed the genome-wide significance threshold keeping only variants associated with fewer than five proteins to minimize pleiotropic effects. We compared the tissue-specific protein effects on phenotypes across different categories. Finally, we integrated the MR-prioritized proteins with the druggable genome to identify new potential targets.

RESULTS

In the MR and colocalization analysis including study-wide significant cis pQTLs as instrumental variables, we identified 33 CSF, 13 plasma, and five brain proteins to be putative causal for 37, 18, and eight phenotypes, respectively. After expanding the instrumental variables by including genome-wide significant cis and trans pQTLs, we identified a total of 58 CSF, 32 plasma, and nine brain proteins associated with 58, 44, and 16 phenotypes, respectively. For those protein-phenotype associations that were found in more than one tissue, the directions of the associations for 13 (87%) pairs were consistent across tissues. As we were unable to use methods correcting for horizontal pleiotropy given most of the proteins were only associated with one valid instrumental variable after clumping, we found that the observations of protein-phenotype associations were consistent with a causal role or horizontal pleiotropy. Between 66.7 and 86.3% of the disease-causing proteins overlapped with the druggable genome. Finally, between one and three proteins, depending on the tissue, were connected with at least one drug compound for one phenotype from both DrugBank and ChEMBL databases.

CONCLUSIONS

Integrating multi-tissue pQTLs with MR and the druggable genome may open doors to pinpoint novel interventions for complex traits with no effective treatments, such as ovarian and lung cancers.

Role of amygdala in stress-induced upregulation of airway IL-1 signaling in asthma

Psychological stress, an important contributor to asthma morbidity, potentiates the immune response to allergen, but the brain mechanisms mediating this response are not fully understood. The amygdala is likely to play an important role, given its sensitivity to threat and connectivity with descending immune modulatory pathways. In this study, we recruited thirty asthmatic participants and examined glucose metabolism in the amygdala, using [F-18]fluorodeoxyglucose positron emission tomography, during a laboratory stressor. Stress hormone and airway inflammatory measurements were also acquired. Results showed that activity in the amygdala was significantly increased during the stressor, compared to a matched control task (p < .05 corrected). Moreover, the increase in amygdala activity was associated with a greater increase in sputum IL-1R1 mRNA and alpha amylase response (p < .05 corrected), which were also positively correlated (p = .01). These findings suggest that heightened amygdala reactivity may contribute to asthma morbidity via descending proinflammatory sympathetic signaling pathways.

Interleukin-31: The "itchy" cytokine in inflammation and therapy

The cytokine interleukin-31 has been implicated in the pathophysiology of multiple atopic disorders such as atopic dermatitis (AD), allergic rhinitis, and airway hyper-reactivity. In AD, IL-31 has been identified as one of the main "drivers" of its cardinal symptom, pruritus. Here, we summarize the mechanisms by which IL-31 modulates inflammatory and allergic diseases. T_H 2 cells play a central role in AD and release high levels of T_H 2-associated cytokines including IL-31, thereby mediating inflammatory responses, initiating immunoregulatory circuits, stimulating itch, and neuronal outgrowth through activation of the heterodimeric receptor IL-31 receptor A (IL31RA)/Oncostatin M receptor (OSMRβ). IL31RA expression is found on human and murine dorsal root ganglia neurons, epithelial cells including keratinocytes and various innate immune cells. IL-31 is a critical cytokine involved in neuroimmune communication, which opens new avenues for cytokine modulation in neuroinflammatory diseases including AD/pruritus, as validated by recent clinical trials using an anti-IL-31 antibody. Accordingly, inhibition of IL-31-downstream signaling may be a beneficial approach for various inflammatory diseases including prurigo. However, as to whether downstream JAK inhibitors directly block IL-31-mediated-signaling needs to be clarified. Targeting the IL-31/IL31RA/OSMRβ axis appears to be a promising approach for inflammatory, neuroinflammatory, and pruritic disorders in the future.

ST2 expression and release by the bronchial epithelium is downregulated in asthma

BACKGROUND

The airway epithelium plays an important role in wound repair, host defense and is involved in the immunopathogenesis of asthma. Genome wide association studies have described associations between ST2/Interleukin (IL)-33 genes in asthma, but its role in bronchial epithelium is unclear.

METHODS

ST2 expression was examined in subjects with asthma and healthy controls in bronchial epithelium from biopsies (n = 27 versus n = 9) and brushings (n = 34 versus n = 20) by immunohistochemistry and RNA-Seq. In human primary bronchial epithelial cells ST2 mRNA and protein expression were assessed by qPCR, flow cytometry, Western blotting, and immunofluorescence. IL-33 function in epithelial cells was examined by intracellular calcium measurements, wound healing assays, and synthetic activation by gene array and ELISA.

RESULTS

Bronchial epithelial ST2 protein expression was significantly decreased in biopsies in subjects with asthma compared to healthy controls (P = .039). IL1RL1 gene expression in bronchial brushes was not different between health and disease. In vitro primary bronchial epithelial cells expressed ST2 and IL-33 stimulation led to an increase in intracellular calcium, altered gene expression, but had no effect upon wound repair. Epithelial cells released sST2 spontaneously, which was reduced following stimulation with TNFα or poly-IC. Stimulation by TNFα or poly-IC did not affect the total ST2 expression by epithelial cell whereas surface ST2 decreased in response to TNFα, but not poly-IC.

CONCLUSION

In asthma, bronchial epithelium protein expression of ST2 is decreased. Our in vitro findings suggest that this decrease might be a consequence of the pro-inflammatory environment in asthma or in response to viral infection.

Glycan-mediated functional assembly of IL-1RI: structural insights into completion of the current description for immune response

Interleukin 1 Receptor type I (IL-1RI) is a multi-domain transmembrane receptor that triggers the inflammatory response. Understanding its detailed mechanism of action is crucial for treating immune disorders. IL-1RI is activated upon formation of its functional assembly that occurs by binding of the IL-1 cytokine and the accessory protein (Il-1RAcP) to it. X-ray crystallography, small-Angle X-ray Scattering and molecular dynamics simulation studies showed that IL-1RI adopts two types of 'compact' and 'extended' conformational states in its dynamical pattern. Furthermore, glycosylation has shown to play a critical role in its activation process. Here, classical and accelerated atomistic molecular dynamics were carried out to examine the role of full glycosylation of IL-1RI and IL-1RAcP in arrangement of the functional assembly. Simulations showed that the 'compact' and 'extended' IL-1RI form two types of 'cytokine-inaccessible-non-signaling' and 'cytokine-accessible-signaling' assemblies with the IL-1RacP, respectively that are both abiding in the presence of glycans. Suggesting that the cytokine binding to IL-1RI is not required for the formation of IL-1RI-IL-1RAcP complex and the 'compact' complex could act as a down-regulatory mechanism. The 'extended' complex is maintained by formation of several persistent hydrogen bonds between the IL-1RI-IL-1RAcP inter-connected glycans. Taken together, it was shown that full glycosylation regulates formation of the IL-1RI functional assembly and play critical role in cytokine biding and triggering the IL-1RI involved downstream pathways in the cell.Communicated by Ramaswamy H. Sarma.

Shikonin Inhibits Der p 2-Induced Cytokine and Chemokine Expression in Dendritic Cells in Patients with Atopic Dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disorder. Shikonin, the active component of Lithospermum erythrorhizon extract, exhibits anti-inflammatory effects. The objective of the present study was to investigate the effect of shikonin on proinflammatory cytokines and chemokine in patients with AD. Ten patients with AD who were allergic to house dust mite (HDM) and seven healthy controls were recruited in this study. Peripheral blood mononuclear cells were isolated, and CD14⁺ cells were further selected and differentiated to dendritic cells. Dendritic cells stimulated using Der p 2, the major HDM allergen, were cotreated with shikonin for 24 hours, and dexamethasone was used as a control. Culture supernatants were collected, and proinflammatory cytokine and chemokine concentrations were analyzed using a multiplex assay system. Shikonin significantly inhibited Der p 2-induced expression of interleukin (IL)-6, IL-9, and IL-17A; monocyte chemoattractant protein (MCP)-1; macrophage inflammatory protein (MIP)-1α; MIP-1β; and Chemokine (C-C motif) ligand 5 (RANTES). The inhibitory effects of shikonin on IL-9, MIP-1β, and RANTES expression were stronger than those of dexamethasone. Therefore, Shikonin can be considered a promising drug for AD treatment because it inhibits different inflammatory cytokines expression.

Epithelial-interleukin-1 inhibits collagen formation by airway fibroblasts: Implications for asthma

In asthma, the airway epithelium has an impaired capacity to differentiate and plays a key role in the development of airway inflammation and remodeling through mediator release. The study objective was to investigate the release of (IL)-1 family members from primary airway epithelial-cells during differentiation, and how they affect primary airway fibroblast (PAF)-induced inflammation, extracellular matrix (ECM) production, and collagen I remodeling. The release of IL-1α/β and IL-33 during airway epithelial differentiation was assessed over 20-days using air-liquid interface cultures. The effect of IL-1 family cytokines on airway fibroblasts grown on collagen-coated well-plates and 3-dimensional collagen gels was assessed by measurement of inflammatory mediators and ECM proteins by ELISA and western blot, as well as collagen fiber formation using non-linear optical microscopy after 24-hours. The production of IL-1α is elevated in undifferentiated asthmatic-PAECs compared to controls. IL-1α/β induced fibroblast pro-inflammatory responses (CXCL8/IL-8, IL-6, TSLP, GM-CSF) and suppressed ECM-production (collagen, fibronectin, periostin) and the cell’s ability to repair and remodel fibrillar collagen I via LOX, LOXL1 and LOXL2 activity, as confirmed by inhibition with β-aminopropionitrile. These data support a role for epithelial-derived-IL-1 in the dysregulated repair of the asthmatic-EMTU and provides new insights into the contribution of airway fibroblasts in inflammation and airway remodeling in asthma.

Current perspectives on the role of interleukin-1 signalling in the pathogenesis of asthma and COPD

Asthma and chronic obstructive pulmonary disease (COPD) cause significant morbidity and mortality worldwide. In the context of disease pathogenesis, both asthma and COPD involve chronic inflammation of the lung and are characterised by the abnormal release of inflammatory cytokines, dysregulated immune cell activity and remodelling of the airways. To date, current treatments still only manage symptoms and do not reverse the primary disease processes. In recent work, interleukin (IL)-1α and IL-1β have been suggested to play important roles in both asthma and COPD. In this review, we summarise overwhelming pre-clinical evidence for dysregulated signalling of IL-1α and IL-1β contributing to disease pathogenesis and discuss the paradox of IL-1 therapeutic studies in asthma and COPD. This is particularly important given recent completed and ongoing clinical trials with IL-1 biologics that have had varying degrees of failure and success as therapeutics for disease modification in asthma and COPD.

Elevated Levels of Soluble ST2 were Associated with Rheumatoid Arthritis Disease Activity and Ameliorated Inflammation in Synovial Fibroblasts

Background:

Much evidence has demonstrated that interleukin (IL)-33 plays an important role in rheumatoid arthritis (RA). However, there have been limited studies about soluble ST2, a receptor for IL-33, in RA. The aims of this study were to detect the levels of ST2 in the serum and synovial fluid of RA patients and to reveal the association of these levels with disease activity and the function of ST2 in RA.

Methods:

A total of 56 RA patients and 38 age-matched healthy controls were enrolled in this study. Synovial fluid samples were collected from another 30 RA patients and 20 osteoarthritis patients. Serum and synovial fluid levels of ST2 were measured by ELISA. In addition, the levels of ST2 in the serum of RA patients before and after therapy were detected. The function of ST2 in RA was revealed by the results of an in vitro cell assay, where recombinant ST2 proteins were used to treat peripheral blood mononuclear cells (PBMCs) and RA synovial fibroblasts (RASFs).

Results:

Serum-soluble ST2 levels were significantly higher in RA patients (127.14 ± 61.43 pg/ml) than those in healthy controls (78.37 ± 41.93 pg/ml, P < 0.01). Synovial fluid-soluble ST2 levels (41.90 ± 33.58 pg/ml) were much higher in RA patients than those in osteoarthritis patients (19.71 ± 16.72 pg/ml, P < 0.05). RA patients who received effective therapy for 6 months showed decreased serum-soluble ST2 levels (113.01 ± 53.90 pg/ml) compared to baseline (139.59 ± 68.36 pg/ml) (P = 0.01). RA patients with high disease activity had higher serum-soluble ST2 levels (162.02 ± 56.78 pg/ml) than those with low disease activity (94.67 ± 40.27 pg/ml, P = 0.001). Soluble ST2 did not affect IL-1β, IL-6, IL-8, or tumor necrosis factor-α (TNF-α) expression in PBMCs from RA patients. However, soluble ST2 ameliorated the expressions of IL-33 and IL-1β but not that of IL-6, IL-8, or TNF-α in resting RASFs. Interestingly, in the RASFs stimulated by TNF-α plus IL-1β, soluble ST2 showed extensive suppressive effects on the expression of IL-6, IL-8, and TNF-α.

Conclusion:

Elevated levels of ST2 in the serum and synovial fluid were associated with disease activity and ameliorated IL-33 expression and IL-33-induced inflammation in RASFs, suggesting that soluble ST2 might be a potential therapeutic candidate for RA.

Matrix Metalloproteinase-9-Dependent Release of IL-1β by Human Eosinophils

Asthma is often associated with airway eosinophilia, and therapies targeting eosinophils are now available to treat severe eosinophilic asthma. Eosinophilic asthma is often due to a type-2 immune response and production of IL-5, which leads to eosinophilopiesis and recruitment of mature eosinophils in the airways. A concomitant type-2 and type-17 response has been reported in some individuals. IL-17 may be enhanced by IL-1β production and can lead to neutrophilic inflammation. In fact, both eosinophilic and neutrophilic (mixed granulocytic) inflammation are simultaneously present in a large population of patients with asthma. In monocyte/macrophage cell populations, release of mature IL-1β occurs via toll-like receptor ligand-induced activation of the inflammasome. Within the inflammasome, a cascade of events leads to the activation of caspase-1, which cleaves pro-IL-1β protein into a mature, releasable, and active form. We have demonstrated that eosinophils can release IL-1β in a Toll-like receptor ligand-independent fashion. The objective of this study was to determine the mechanisms underlying the production and maturation of IL-1β in cytokine-activated eosinophils. Using eosinophils from circulating blood and from bronchoalveolar lavage fluid after an airway allergen challenge, the present study demonstrates that cytokine-activated eosinophils express and release a bioactive form of IL-1β with an apparent size less than the typical 17 kDa mature form produced by macrophages. Using a zymography approach and pharmacological inhibitors, we identified matrix metalloproteinase-9 (MMP-9) as a protease that cleaves pro-IL-1β into a ~15 kDa form and allows the release of IL-1β from cytokine-activated eosinophils. Therefore, we conclude that activated eosinophils produce MMP-9, which causes the release of IL-1β in an inflammasome/caspase-1-independent manner. The production of IL-1β by eosinophils may be a link between the eosinophilic/type-2 immune response and the neutrophilic/type-17 immune response that is often associated with a more severe and treatment-refractory type of asthma.

Do Alarmins Have a Potential Role in Autism Spectrum Disorders Pathogenesis and Progression?

Autism spectrum disorders (ASDs) represent a disabling condition in early childhood. A number of risk factors were proposed in order to explain their pathogenesis. A multifactorial model was proposed, and data supported the implication of genetic and environmental factors. One of the most accepted speculations is the existence of an imbalance of the immune system. Altered levels of cytokines, chemokines and immunoglobulins were demonstrated in patients with ASDs; in particular, proinflammatory mediators were significantly increased. Alarmins are a multifunctional heterogeneous group of proteins, structurally belonging to specific cells or incorporated by them. They are released in the surrounding tissues as a consequence of cell damage or inflammation. Their functions are multiple as they could activate innate immunity or recruit and activate antigen-presenting cells stimulating an adaptive response. Alarmins are interesting both for understanding the inflammatory process and for diagnostic purposes as biomarkers. Moreover, recent studies, separately, showed that alarmins like interleukin (IL)-33, high-mobility group box 1 (HMGB1), heat-shock protein (HSP) and S100 protein (S100) could play a relevant role in the pathogenesis of ASDs. According to the literature, some of these alarmins could be suitable as biomarkers of inflammation in ASD. Other alarmins, by interfering with the immune system blocking pro-inflammatory mediators, could be the key for ameliorating symptoms and behaviours in autistic disorders.

Soluble ST2 suppresses IL-5 production by human basophilic KU812 cells, induced by epithelial cell-derived IL-33

BACKGROUND

Epithelial cell-derived IL-33 has an important role in the initiation and activation of innate allergic inflammation. IL-33 acts as a cytokine through the ST2 receptor (ST2L) and it stimulates the production of Th2 cytokines. Soluble ST2 (sST2) may regulate Th2 responses by neutralizing the activity of IL-33. Basophils express ST2L and produce IL-5 in response to IL-33. However, the role of the epithelial cell-basophil interaction and sST2 in IL-5 production remains unclear.

METHODS

Cultured human bronchial epithelial (hBE33) cells, that contained the human IL-33 gene (i.e., hBE33 cells) and a human basophilic cell line, KU812 cells, were used to study the epithelial cell-basophil interaction in the production of IL-5 induced by HDM.

RESULTS

At 15 min after incubation, HDM stimulated the rapid release of IL-33 from cultured hBE33 cells. IL-33 and the supernatant of HDM-treated hBE33 cells stimulated IL-5 production from KU812 cells. Anti-IL-33 antibody and anti-ST2 antibody treatment of KU812 cells suppressed IL-5 production, which had been induced by the supernatant of HDM-treated hBE33 cells. The hBE33 cells secreted sST2 in a time-dependent manner. The production of sST2 by KU812 cells co-cultured with hBE33 cells was significantly increased, compared with KU812 cells cultured with the supernatant of hBE33 cells. Soluble ST2 suppressed IL-5 production by KU812 cells, which was induced by the supernatant of HDM-treated hBE33 cells.

CONCLUSIONS

Epithelial cell-derived IL-33 promoted IL-5 production by KU812 cells. The subsequently produced sST2 has important roles in regulating Th2 responses.

IL-33/s-ST2 ratio, systemic symptoms, and basophil activation in Pru p 3-sensitized allergic patients

BACKGROUND

Although IL-33/ST2 axis is involved in the development of allergic diseases, its contribution in food allergy is still unknown.

METHODS

In this study, we assessed the serum levels of IL-33 and its s-ST2 receptor in 53 control patients (without allergic diseases), 47 peach (Pru p 3)-sensitized allergic patients (SAP), and in 68 non-Pru p 3-SAP. Basophil activation test (BAT) was used to assess the basophil activation due to allergen exposure before and after the addition of s-ST2 to the blood samples from 5 Pru p 3-SAP.

RESULTS

IL-33 levels in Pru p 3-SAP were higher than in non-Pru p 3-SAP and in normal controls. Lower s-ST2 levels were found in Pru p 3-SAP than in non-Pru p 3-SAP. IL-33/s-ST2 ratio was higher in Pru p 3-SAP than in both non-Pru p 3-SAP and controls. Higher IL-33/s-ST2 ratio was observed in Pru p 3-SAP with severe than in those with mild systemic symptoms. BAT analysis in Pru p 3-SAP showed a decrease in basophil activation due to Pru p 3 exposure after the addition of s-ST2 to the blood samples.

CONCLUSIONS

An imbalance in the baseline levels of IL-33/ST2 pathway is present in Pru p 3-SAP. The measurement of this pathway might be helpful to detect patients at a higher risk of developing severe systemic symptoms.

Sputum cell IL-1 receptor expression level is a marker of airway neutrophilia and airflow obstruction in asthmatic patients

BACKGROUND

Various clinical, biologic, or physiologic markers of asthma have been used to identify patient clusters and potential targets for therapy. However, these identifiers frequently overlap among the different asthma groups. For instance, both eosinophil and neutrophil counts are often increased in the airways of asthmatic patients despite their typical association with type 2 and type 17 immune response, respectively.

OBJECTIVES

We sought to determine whether inflammatory gene expression is related to patterns of airway inflammation and lung function and identify molecular markers for neutrophilic asthma.

METHODS

Expression levels of 17 genes characterizing type 1, type 2, and type 17 lymphocytes were measured in sputum samples from 48 participants with asthma. The relationships between gene expression levels and sputum cell differentials or measures of pulmonary function were examined by using partial least squares regression.

RESULTS

Gene expression levels were strongly associated with cell differentials, explaining 71% of variation in eosinophil counts and 64% of variation in neutrophil counts. The 3 genes with the strongest relationships to sputum neutrophil counts were IL1R1 (standardized regression coefficient [β] = +0.27, P = .005), IL1RAP (β = +0.32, P = .0004), and IL4R (β = +0.29, P = .002). Higher expression levels of IL1R1, IL1RAP, and IL4R were associated with reduced FEV₁/forced vital capacity ratio (β = -0.11, -0.08, and -0.10; P = .005, .07, and .05).

CONCLUSION

IL-1 receptor appears to be a marker of neutrophilic inflammation and airflow obstruction in patients with asthma, who have a wide range of disease severity. The IL-1 pathway might contribute to airway neutrophilia and is a potential therapeutic target in patients with neutrophilic asthma.

Developments in the field of allergy mechanisms in 2015 through the eyes of Clinical & Experimental Allergy

In the first of two papers we described the development in the field of allergy mechanisms as described by Clinical and Experimental Allergy in 2015. Experimental models of allergic disease, basic mechanisms, clinical mechanisms and allergens are all covered. A second paper will cover clinical aspects.

Role of the TSLP-DC-OX40L pathway in asthma pathogenesis and airway inflammation in mice

This study aimed to explore the effect of the TSLP-DC-OX40L pathway in asthma pathogenesis and airway inflammation in mice. For this, 65 male BALF/c mice were distributed among the control, asthma, immunoglobulin G (IgG) + asthma (IgG, 500 μg/500 μL, intratracheal injection of 50 μL each time), LY294002 (OX40L inhibitor) + asthma (intratracheal injection of 2 mg/kg LY294002), and anti-TSLP + asthma (intratracheal injection of 500 μg/500 μL TSLP antibody, 50 μL each time) groups. ELISA was applied to measure the serum levels of immunoglobulin E (IgE), ovalbumin (OVA)-sIgE, interleukin-4 (IL-4), IL-5, IL-13, and interferon-γ (IFN-γ); flow cytometry was employed to detect Treg cells and dendritic cell (DC) and lymphopoiesis. RT-qPCR and Western blot assays were used to measure the levels of TSLP, OX40L, T-bet, GATA-3, NF-κB, p38, and ERK. Treatment with LY294002 and anti-TSLP resulted in increases in the numbers of total cells, eosinophils, neutrophils, and lymphocytes in the bronchoalveolar lavage fluid; total serum levels of IgE, OVA-sIgE, IL-4, IL-5, and IL-13; levels of DC cells; lymphopoiesis; and levels of TSLP, OX40L, GATA-3, NF-κB, p38, and ERK, whereas there were decreases in the levels of IFN-γ and CD4⁺CD25⁺Treg cells; CD4⁺Foxp3⁺Treg cells; and T-bet. The TSLP-DC-OX40L pathway may contribute to asthma pathogenesis and airway inflammation by modulating the levels of CD4⁺CD25⁺Treg cells and inflammatory cytokines.

Development of an interleukin (IL)-33 sandwich ELISA kit specific for mature IL-33

Interleukin (IL)-33 is an inflammatory cytokine and belongs to the IL-1 family of cytokines. There are eleven members of the IL-1 family of cytokines and all have important roles in host defense against infections. Their levels are increased during infection and in various auto-inflammatory diseases. IL-33 is also associated with autoimmune diseases such as asthma, atopic dermatitis, rheumatoid arthritis, and atherosclerosis. IL-33 receptors consist of IL-1R4 and IL-1R3 to induce both Th1 and Th2 type immune response. Here we present the development of monoclonal antibodies (mAbs) against human mature IL-33. Recombinant human mature IL-33 protein was expressed in E. coli and purified by multi-step affinity chromatography. The human IL-33 activity was examined in HMC-1 and Raw 264.7 cells. Mice were immunized with the biologically active mature IL-33 to generate mAb against IL-33. The anti-IL-33 mAb (clone/4) was used as a capture antibody for a sandwich enzyme-linked immunosorbent assay (ELISA). This assay detects mature IL-33 with a high sensitivity (80 pg/mL) but does not recognize the biologically inactive precursor IL-33. This article describes the methods for a newly developed IL-33 ELISA kit that is specific for mature IL-33 and may be used to analyze bioactive mature IL-33 in various immunological diseases.

Holding the Inflammatory System in Check: TLRs and Their Targeted Therapy in Asthma

Inflammation is a complex biological response to detrimental stimuli and can be a double-edged sword. Inflammation plays a protective role in removing pathogenic factors, but dysregulated inflammation is associated with several major fatal diseases such as asthma, cancer, and cardiovascular diseases. Asthma is a complex heterogenous disease caused by genetic and environmental factors. TLRs are the primary proteins associated with the innate and adaptive immune responses to these fatal factors and play an important role in recognizing pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), which initiates the downstream immune response. Due to the complex TLRs cascade and nowadays unsuccessful control in asthma, new studies are focused on TLRs and other potential targets in TLR cascade to minimize airway inflammation.

Tracheal overexpression of IL-1β, IRAK-1 and TRAF-6 mRNA in obese-asthmatic male Wistar rats

OBJECTIVES

Human and animal studies have shown a close relationship between obesity and asthma severity. Here, we examined the effects of diet-induced obesity (DIO) on the expression levels of IL-1β, IRAK-1 and TRAF-6 mRNA in male Wistar rats tracheal after sensitization with ovalbumin (OVA).

MATERIALS AND METHODS

Twenty male Wistar rats divided to four groups, included, control group with normal diet (C+ND), OVA-sensitized group with normal diet (S+ND), control group with high-fat diet (C+HFD), and OVA-sensitized group with high-fat diet (S+HFD). All animals fed for 8 weeks with standard pelts or high-fat diet, and then were sensitized and challenged with OVA or saline for another 4 weeks with designed regimens. At the end of study, trachea isolated and examined for expression levels of IL-1β, IRAK-1 and TRAF-6 mRNA with RT-PCR method.

RESULTS

Diet-induced obesity groups developed increased weight, obesity indexes and lipid profiles (P<0.05 to P<0.001). The expression levels of IL-1β mRNA in OVA-sensitization groups (S+ND and S+HFD) showed a significantly increased when compared with control group. Also in S+HFD group, expression level of TRAF-6 mRNA was higher than other groups (P<0.001). IRAK-1 expression level was high in S+HFD compared with control group.IL-1β and TRAF-6 mRNA correlated positively with obesity indexes.

CONCLUSION

The results showed that DIO causes overexpression of IL-1β, IRAK-1 and TRAF-6 mRNA in an experimental model of asthma. Our results suggested that in obese-asthmatic conditions locally production and activation of pro-inflammatory agents can be increased. These findings showed that possible mechanism for obesity-asthma relationships.

IL-33/ST2 axis controls Th2/IL-31 and Th17 immune response in allergic airway diseases

IL-33 targeting ST2 receptor (T1/ST2), expressed on Th2 cell surface, regulates the production of cytokines like IL-17A and IL-31. We studied the role of IL-33/ST2 axis in IL-31 and IL-17A production in patients with allergic rhinitis (AR) and with concomitant allergic asthma and rhinitis (AAR). 20 healthy control subjects (HC), 14 AR and 17 AAR subjects were recruited and blood samples collected. IL-33, soluble ST2 (sST2), IL-17A and IL-31 plasma concentrations were measured by ELISA method. T1/ST2, IL-31 and IL-17A cellular expression were studied in peripheral blood mononuclear cells (PBMC) from HC, AR and AAR (n=6 for each group) by flow-cytometry. In vitro, we also evaluated the effect of beclomethasone dipropionate (BDP) on T1/ST2, IL-31 and IL-17A expression in CD3(+)T-cells from PBMC of AAR (n=6). Plasma levels of IL-33, IL-31 and IL-17A were significantly higher and sST2 was lower in patients with AR and AAR than in HC. IL-31 and IL-17A intracellular levels significantly increased, whereas T1/ST2 expression was significantly lower, in CD3(+)T-cells from AR and AAR compared to HC. Positive correlations were observed between plasmatic components of IL-33/ST2 axis and IL-31 in both AR and AAR and IL-17A in AAR. In vitro IL-31 and IL-17A intracellular levels decreased after BDP treatment, whereas T1/ST2 expression increased in cultured CD3(+)T-cells obtained from AAR. IL-33/ST2 axis is involved in Th2/IL-31 and Th17 immune response during the progression of allergic airway disease. In vitro BDP is able to control Th2/IL-31 and Th17 immune response in PBMC from allergic patients.

25-Hydroxyvitamin D, IL-31, and IL-33 in children with allergic disease of the airways

Low vitamin D is involved in allergic asthma and rhinitis. IL-31 and IL-33 correlate with Th2-associated cytokines in allergic disease. We investigated whether low vitamin D is linked with circulating IL-31 and IL-33 in children with allergic disease of the airways. 25-Hydroxyvitamin D [25(OH) Vit D], IL-31, and IL-33 plasma levels were measured in 28 controls (HC), 11 allergic rhinitis (AR) patients, and 35 allergic asthma with rhinitis (AAR) patients. We found significant lower levels of 25(OH) Vit D in AR and in AAR than in HC. IL-31 and IL-33 plasma levels significantly increased in AAR than HC. IL-31 and IL-33 positively correlated in AR and AAR. 25(OH) Vit D deficient AAR had higher levels of blood eosinophils, exacerbations, disease duration, and total IgE than patients with insufficient or sufficient 25(OH) Vit D. In AAR 25(OH) Vit D levels inversely correlated with total allergen sIgE score and total atopy index. IL-31 and IL-33 did not correlate with 25(OH) Vit D in AR and AAR. In conclusion, low levels of 25(OH) Vit D might represent a risk factor for the development of concomitant asthma and rhinitis in children with allergic disease of the airways independently of IL-31/IL-33 Th2 activity.

A robust high throughput platform to generate functional recombinant monoclonal antibodies using rabbit B cells from peripheral blood

We have developed a robust platform to generate and functionally characterize rabbit-derived antibodies using B cells from peripheral blood. The rapid high throughput procedure generates a diverse set of antibodies, yet requires only few animals to be immunized without the need to sacrifice them. The workflow includes (i) the identification and isolation of single B cells from rabbit blood expressing IgG antibodies, (ii) an elaborate short term B-cell cultivation to produce sufficient monoclonal antigen specific IgG for comprehensive phenotype screens, (iii) the isolation of VH and VL coding regions via PCR from B-cell clones producing antigen specific and functional antibodies followed by the sequence determination, and (iv) the recombinant expression and purification of IgG antibodies. The fully integrated and to a large degree automated platform (demonstrated in this paper using IL1RL1 immunized rabbits) yielded clonal and very diverse IL1RL1-specific and functional IL1RL1-inhibiting rabbit antibodies. These functional IgGs from individual animals were obtained at a short time range after immunization and could be identified already during primary screening, thus substantially lowering the workload for the subsequent B-cell PCR workflow. Early availability of sequence information permits one to select early-on function- and sequence-diverse antibodies for further characterization. In summary, this powerful technology platform has proven to be an efficient and robust method for the rapid generation of antigen specific and functional monoclonal rabbit antibodies without sacrificing the immunized animal.

Blockade of IL-33/ST2 ameliorates airway inflammation in a murine model of allergic asthma

OBJECTIVE

Interleukin (IL)-33 is involved in the development of lung inflammation by inducing or amplifying Th2 type-mediated responses in various animal models of allergic asthma. The ST2 gene is a member of the IL-1 receptor family, producing a transmembrane form (ST2L) and a soluble secreted form (sST2). sST2 has been shown to block this IL-33/ST2 signaling pathway. This study aimed to investigate whether anti-IL-33 and sST2 reduced airway inflammation in a murine model of asthma.

METHODS

BALB/c mice were sensitized and challenged with ovalbumin (OVA), and the effect of sST2 and anti-IL-33 antibody on airway inflammation and airway hyperresponsiveness (AHR) was evaluated. Furthermore, we measured changes in various cytokines in the bronchoalveolar lavage (BAL) fluid when treated with sST2 or anti-IL-33.

RESULTS

We observed that anti-IL-33 antibody and sST2 exert a negative regulation on OVA-mediated allergic airway inflammation. Both treatments reduced total cell counts and eosinophil counts in BAL fluid and AHR to methacholine. The Th2 cytokines, such as IL-4, IL-5, and IL-13 in BAL fluid were also significantly decreased after both treatments. However, there were no changes in the level of TGF- ß1 and IL-10 after each treatment.

CONCLUSIONS

These results suggest that anti-IL-33 as well as sST2 have therapeutic potential for allergic asthma through inhibition of Th2 cytokine production.

The endogenous Th17 response in NO2-promoted allergic airway disease is dispensable for airway hyperresponsiveness and distinct from Th17 adoptive transfer

Severe, glucocorticoid-resistant asthma comprises 5-7% of patients with asthma. IL-17 is a biomarker of severe asthma, and the adoptive transfer of Th17 cells in mice is sufficient to induce glucocorticoid-resistant allergic airway disease. Nitrogen dioxide (NO2) is an environmental toxin that correlates with asthma severity, exacerbation, and risk of adverse outcomes. Mice that are allergically sensitized to the antigen ovalbumin by exposure to NO2 exhibit a mixed Th2/Th17 adaptive immune response and eosinophil and neutrophil recruitment to the airway following antigen challenge, a phenotype reminiscent of severe clinical asthma. Because IL-1 receptor (IL-1R) signaling is critical in the generation of the Th17 response in vivo, we hypothesized that the IL-1R/Th17 axis contributes to pulmonary inflammation and airway hyperresponsiveness (AHR) in NO2-promoted allergic airway disease and manifests in glucocorticoid-resistant cytokine production. IL-17A neutralization at the time of antigen challenge or genetic deficiency in IL-1R resulted in decreased neutrophil recruitment to the airway following antigen challenge but did not protect against the development of AHR. Instead, IL-1R-/- mice developed exacerbated AHR compared to WT mice. Lung cells from NO2-allergically inflamed mice that were treated in vitro with dexamethasone (Dex) during antigen restimulation exhibited reduced Th17 cytokine production, whereas Th17 cytokine production by lung cells from recipient mice of in vitro Th17-polarized OTII T-cells was resistant to Dex. These results demonstrate that the IL-1R/Th17 axis does not contribute to AHR development in NO2-promoted allergic airway disease, that Th17 adoptive transfer does not necessarily reflect an endogenously-generated Th17 response, and that functions of Th17 responses are contingent on the experimental conditions in which they are generated.

IL-1 and T Helper Immune Responses

CD4 T cells play a critical role in mediating adaptive immunity to a variety of pathogens as well as in tumor immunity. If not adequately regulated, CD4 T cells can be also involved in autoimmunity, asthma, and allergic responses. During TCR activation in a particular cytokine milieu, naïve CD4 T cells may differentiate into one of several lineages of T helper (Th) cells, including Th1, Th2, and Th17, as defined by their pattern of cytokine production and function. IL-1, the prototypic proinflammatory cytokine, has been shown to influence growth and differentiation of immunocompetent lymphocytes. The differential expression of IL-1RI on human CD4 T cell subsets confers distinct capacities to acquire specific effector functions. In this review, we summarize the role of IL-1 on CD4 T cells, in terms of differentiation, activation, and maintenance or survival.

Human eosinophils release IL-1ß and increase expression of IL-17A in activated CD4+ T lymphocytes

BACKGROUND

Differentiation and activation of CD4(+) T cells is controlled by various cytokines produced by innate immune cells. We have shown that eosinophils (EOS) have the potential to influence Th1 and Th2 cytokine generation by CD4(+) cells, but their influence on IL-17A (IL-17) has not been established.

OBJECTIVE

The purpose of this study is to determine the effect of EOS on IL-17 production by lymphocytes.

METHODS

Pre-activated CD4(+) T cells were cultured in the presence of either autologous EOS or EOS culture supernatants. Expression of IL-17 was determined by real-time quantitative PCR (qPCR) after 5 h and protein level was measured after 48 h. To determine the effect of allergen-induced airway EOS on IL-17, subjects with mild allergic asthma underwent bronchoscopic segmental bronchoprovocation with allergen (SBP-Ag) after a treatment with an anti-IL-5 neutralizing antibody (mepolizumab) to reduce airway eosinophilia. IL-17 mRNA was measured in bronchoalveolar lavage (BAL) cells by qPCR.

RESULTS

In vitro, EOS significantly increased IL-17 production by CD4(+) T cells. Addition of exogenous IL-1ß increased expression of IL-17 mRNA by CD4(+) T cells. EOS expressed and released IL-1ß. Furthermore, levels of IL-1ß in EOS supernatants highly correlated with their ability to increase IL-17 expression by CD4(+) T cells, and neutralizing antibody to IL-1ß reduced expression of IL-17 mRNA. In vivo, reduction of EOS in the airway using mepolizumab was associated with diminished IL-17 expression after SBP-Ag.

CONCLUSIONS AND CLINICAL RELEVANCE

Our data demonstrate that EOS can promote IL-17 production through the release of IL-1ß. Enhanced IL-17 cytokine production is another mechanism by which EOS may participate in pathogenesis of allergic airway inflammation in asthma.

Cholesterol depletion in cell membranes of human airway epithelial cells suppresses MUC5AC gene expression

PURPOSE

If cholesterol in the cell membrane is depleted by treating cells with methyl-β-cyclodextrin (MβCD), the activities of transmembrane receptors are altered in a cell-specific and/or receptor-specific manner. The proinflammatory cytokines, IL-1β is potent inducers of MUC5AC mRNA and protein synthesis in human airway epithelial cells. Cells activated by IL-1β showed increased phosphorylation of extracellular signal regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). Thus, we investigated the effects of cholesterol depletion on the expression of MUC5AC in human airway epithelial cells and whether these alterations to MUC5AC expression were related to MAPK activity.

MATERIALS AND METHODS

After NCI-H292 cells were pretreated with 1% MβCD before adding IL-1β for 24 hours, MUC5AC mRNA expression was determined by reverse transcription- polymerase chain reaction (RT-PCR) and real time-PCR. Cholesterol depletion by MβCD was measured by modified microenzymatic fluorescence assay and filipin staining. The phosphorylation of IL-1 receptor, ERK and p38 MAPK, was analyzed by western blot.

RESULTS

Cholesterol in the cell membrane was significantly depleted by treatment with MβCD on cells. IL-1β-induced MUC5AC mRNA expression was decreased by MβCD and this decrease occurred IL-1-receptor- specifically. Moreover, we have shown that MβCD suppressed the activation of ERK1/2 and p38 MAPK in cells activated with IL-1β. This result suggests that MβCD-mediated suppression of IL-1β-induced MUC5AC mRNA operated via the ERK- and p38 MAPK-dependent pathway.

CONCLUSION

Cholesterol depletion in NCI-H292 cell membrane may be considered an anti-hypersecretory method since it effectively inhibits mucus secretion of respiratory epithelial cells.

Inducible IL-33 expression by mast cells is regulated by a calcium-dependent pathway

IL-33 is an IL-1 family cytokine that displays dual functions: a cytokine via its receptor, T1/ST2, or a chromatin-binding factor within the nucleus. Functionally, it promotes Th2-associated immunity by enhancing the activation and survival of several cell types. However, the pathways regulating IL-33 expression are still unclear. Although several cells display constitutive expression of IL-33, we showed previously that mast cells expressed low levels of IL-33 constitutively but that IL-33 was induced upon IgE-mediated activation. This was mediated via a calcium-dependent mechanism. In this study, we define the pathway through which this inducible IL-33 is regulated. Importantly, this pathway does not alter expression in cells with high constitutive IL-33 expression, such as epithelial cells or fibroblasts. Our data show that, upstream of calcium, inhibition of PI3K and Sphk activity decreases inducible IL-33 expression to IgE/Ag activation. Additionally, expression of Sphk1 short hairpin RNA prevents upregulation of IL-33 expression. Downstream of calcium, NFAT activity is necessary and sufficient for inducible IL-33 expression. We also demonstrate calcium-dependent transcription from two regions of the IL-33 gene that contain putative NFAT-binding sites, one upstream of exon 1 and one upstream of the start site. Interestingly, we show that blocking other calcium pathways, including inositol triphosphate receptor, or NF-κB inhibits IgE-driven IL-1β, another IL-1 family cytokine, but it has no influence on inducible IL-33 expression. In summary, our data demonstrate cell-specific differences in the regulation of IL-33 expression and define a pathway critical for the expression of inducible IL-33 by mast cells upon their activation.

Functional biomarkers of depression: diagnosis, treatment, and pathophysiology

Major depressive disorder (MDD) is a heterogeneous illness for which there are currently no effective methods to objectively assess severity, endophenotypes, or response to treatment. Increasing evidence suggests that circulating levels of peripheral/serum growth factors and cytokines are altered in patients with MDD, and that antidepressant treatments reverse or normalize these effects. Furthermore, there is a large body of literature demonstrating that MDD is associated with changes in endocrine and metabolic factors. Here we provide a brief overview of the evidence that peripheral growth factors, pro-inflammatory cytokines, endocrine factors, and metabolic markers contribute to the pathophysiology of MDD and antidepressant response. Recent preclinical studies demonstrating that peripheral growth factors and cytokines influence brain function and behavior are also discussed along with their implications for diagnosing and treating patients with MDD. Together, these studies highlight the need to develop a biomarker panel for depression that aims to profile diverse peripheral factors that together provide a biological signature of MDD subtypes as well as treatment response.

Asthma translational medicine: report card

Over the last 30 years, scientific research into asthma has focused almost exclusively on one component of the disorder - airway inflammation - as being the key underlying feature. These studies have provided a remarkably detailed and comprehensive picture of the events following antigen challenge that lead to an influx of T cells and eosinophils in the airways. Indeed, in basic research, even the term "asthma" has become synonymous with a T helper 2 cell-mediated disorder. From this cascade of cellular activation processes and mediators that have been identified it has been possible to pinpoint critical junctures for therapeutic intervention, leading experimentalists to produce therapies that are very effective in decreasing airway inflammation in animal models. Many of these compounds have now completed early Phase 2 "proof-of-concept" clinical trials so the translational success of the basic research model can be evaluated. This commentary discusses clinical results from 39 compounds and biologics acting at 23 different targets, and while 6 of these drugs can be regarded as a qualified success, none benefit the bulk of asthma sufferers. Despite this disappointing rate of success, the same immune paradigm and basic research models, with a few embellishments to incorporate newly identified cells and mediators, continue to drive target identification and drug discovery efforts. It is time to re-evaluate the focus of these efforts.