Airways epithelial exposure to Streptococcus pneumoniae in the presence of the alarmin IL-33 induces a novel subset of pro-inflammatory ILC2s promoting a mixed inflammatory response.

BACKGROUND: We have previously shown that asthma-like airways inflammation may be induced by topical exposure to respiratory tract pathogens such as S. pneumoniae (SP) in concert with epithelial alarmins such as IL-33. Details of the pathogenesis of this murine surrogate remain however unexplored. METHODS: Airways inflammation was induced by repeated, intranasal exposure of Il-4-/-, Rag1-/- and Rag2-/-Il2rg-/- mice (in which B lymphocyte IgE switching, adaptive and innate immunity are respectively ablated) as well as wild type mice to inactivated SP, IL-33 or both. Airways pathological changes were analysed, and the subsets and functions of locally accumulated ILC2s investigated by single cell RNA sequencing and flow cytometry. RESULTS: In the presence of IL-33, repeated exposure of the airways to inactivated SP caused marked eosinophil- and neutrophil-rich inflammation and local accumulation of ILC2s, which was retained in the Il-4-/- and Rag1-/- deficient mice but abolished in the Rag2-/-Il2rg-/- mice, an effect partly reversed by adoptive transfer of ILC2s. Single cell sequencing analysis of ILC2s recruited following SP and IL-33 exposure revealed a Klrg1+Ly6a+subset, expressing particularly elevated quantities of the pro-inflammatory cytokine IL-6, type 2 cytokines (IL-5 and IL-13) and MHC class II molecules, promoting type 2 inflammation as well as involved in neutrophil-mediated inflammatory responses. CONCLUSION: Local accumulation of KLRG1+Ly6a+ ILC2s in the lung tissue is a critical aspect of the pathogenesis of airways eosinophilic and neutrophil-rich inflammation induced by repeated exposure to SP in the presence of the epithelial alarmin IL-33.

Bacterial antigens and asthma: a comparative study of common respiratory pathogenic bacteria.

Objective: In a previous study we have shown that, in the presence of interleukin (IL)-33, repeated, per-nasal challenge of murine airways with Streptococcus pneumoniae (S. pneumoniae) organisms induces human asthma-like airways inflammation. It is not clear, however, whether this effect is unique or manifest in response to other common respiratory pathogens.Methods: To explore this, airways of BALB/c mice were repeatedly challenged per-nasally with formaldehyde-inactivated bacterial bodies in the presence or absence of murine recombinant IL-33. Serum concentrations of S.pneumoniae, Moraxella catarrhalis (M.catarrhalis) and Haemophilus influenzae (H.influenzae) lysates-specific IgE were measured in patients with asthma and control subjects.Results: We showed that in the presence of IL-33, repeated, per-nasal airways exposure to the bodies of these bacteria induced airways hyperresponsiveness (AHR) in the experimental mice. This was accompanied by cellular infiltration into bronchoalveolar lavage fluid (BALF), eosinophilic infiltration and mucous hypertrophy of the lung tissue, with elevated local expression of some type 2 cytokines and elevated, specific IgG and IgE in the serum. The precise characteristics of the inflammation evoked by exposure to each bacterial species were distinguishable.Conclusions: These results suggest that in the certain circumstances, inhaled or commensal bacterial body antigens of both Gram-positive (S. pneumoniae) and Gram-negative (M. catarrhalis and H. influenzae) respiratory tract bacteria may initiate type 2 inflammation typical of asthma in the airways. In addition, we demonstrated that human asthmatic patients manifest elevated serum concentrations of M.catarrhalis- and H.influenzae-specific IgE.

Allergen Immunotherapy for Asthma.

Allergen immunotherapy is a disease-modifying treatment for IgE-mediated allergies reducing disease burden and symptoms in patients with allergic rhinitis, with or without asthma. The growing evidence that allergen immunotherapy also has the potential to facilitate achieving asthma control in patients with allergic asthma resulted in its acknowledgment by international bodies (Global Initiative for Asthma and European Academy of Allergy and Clinical Immunology) as add-on treatment for mild/moderate asthma. Although there have been promising developments in biomarkers for patient selection and for allergen immunotherapy efficacy evaluation in patients with asthma, a lot more data are still required.

Cigarette smoke aggravates asthma via altering airways inflammation phenotypes and remodelling.

INTRODUCTION: Many asthmatic patients are exposed to cigarette smoke actively or passively, which contributes to asthma exacerbation and poor control. This study is to explore the effects of cigarette smoke on pathological changes in murine surrogate of asthma. METHODS: C57BL/6 mice were sensitised and challenged with ovalbumin (OVA) to establish a surrogate of asthma and then administered with cigarette smoke extract (CSE). Airways hyperresponsiveness (AHR) was measured using the Flexivent system. Histological staining (haematoxylin-eosin [HE], periodic acid Schiff [PAS], Congo red and Masson's trichrome) was employed to measure pathological changes in sections of lung tissue of experimental mice. Enzyme-linked immunosorbent assay (ELISA) was used to measure the concentrations of total and OVA-specific IgE, cytokines and chemokines (eotaxin-1, IL-13, IL-1ß, TNF-α, IL-17A, IL-33) in the lung tissue homogenates. Immunoreactivity for vWF and α-SMA in lung tissue sections was detected by immunohistochemistry. RESULTS: Exposure of the animals to CSE significantly reduced OVA-induced AHR, the number of eosinophils in bronchoalveolar lavage fluid (BALF) and eosinophils infiltrating into the lung tissue, as well as concentrations of some cytokines in lung homogenate. In contrast, it significantly enhanced the number of macrophages and M2 in BALF, as well as collagen deposition, smooth muscle thickness and alveolar destruction in lung tissue. CONCLUSION: CSE inhibits OVA-induced AHR, changes inflammation 'phenotypes', while accelerates some aspects of airways remodelling, which might contribute to worse symptoms and be refractory to anti-inflammation therapies for asthmatics.

Sphingosine-1-phosphate induces airway smooth muscle hyperresponsiveness and proliferation.

BACKGROUND: The emerging role of sphingosine-1-phosphate (S1P) in regulating smooth muscle functions has led to the exploration of the possibility that this sphingolipid could represent a potential therapeutic target in asthma and other lung diseases. Several studies in animal surrogates have suggested a role for S1P-mediated signaling in the regulation of airway smooth muscle (ASM) contraction, airway hyperresponsiveness, and airway remodeling, but evidence from human studies is lacking. OBJECTIVE: We sought to compare the responsiveness of the airways to S1P in healthy and asthmatic individuals in vivo, in isolated human airways ex vivo, and in murine airways dissected from healthy and house dust mite (HDM)-sensitized animals. METHODS: Airway responsiveness was measured by spirometry during inhalation challenges and by wire myography in airways isolated from human and mouse lungs. Thymidine incorporation and calcium mobilization assays were used to study human ASM cell responses. RESULTS: S1P did not induce contraction of airways isolated from healthy and HDM-exposed mice, nor in human airways. Similarly, there was no airway constriction observed in healthy and asthmatic subjects in response to increasing concentrations of inhaled S1P. However, a 30-minute exposure to S1P induced a significant concentration-dependent enhancement of airway reactivity to methacholine and to histamine in murine and human airways, respectively. HDM-sensitized mice demonstrated a significant increase in methacholine responsiveness, which was not further enhanced by S1P treatment. S1P also concentration-dependently enhanced proliferation of human ASM cells, an effect mediated through S1P receptor type 2, as shown by selective antagonism and S1P receptor type 2 small-interfering RNA knockdown. CONCLUSIONS: Our data suggest that S1P released locally into the airways may be involved in the regulation of ASM hyperresponsiveness and hyperplasia, defining a novel target for future therapies.

Early-life infection of the airways with Streptococcus pneumoniae exacerbates HDM-induced asthma in a murine model.

Respiratory tract infection early in life plays a significant role in the pathogenesis of asthma. In the present study we examine, using a murine surrogate, the effects of early life respiratory infection with Streptococcus pneumoniae (SP) on adult asthma induced by sensitisation and exposure to house dust mite (HDM) allergen. Mice (one week old) were infected with SP, then 3 weeks later sensitised to HDM emulsified with Al (OH)3 intraperitoneally and challenged intranasally with same allergen for up to a further 5 weeks to establish the asthma surrogate. Outcome measures were quantified using the FlexiVent apparatus, histology and immunohistology, ELISA and flow cytometry. The murine surrogates of asthma infected with SP early in life exhibited significantly more severe disease compared with the controls of mice without SP infection, as shown by airways responsiveness, inflammatory cellular infiltration of the airways, expression of markers of airways remodelling, serum concentrations of HDM-specific IgE and the concentrations of Th2-type cytokines and the numbers of activated Th2 and ILC2 cells in the lung tissues. These data are compatible with the hypothesis that early-life infection of the airways with SP exacerbates, at least in some individuals, subsequent HDM-induced allergic airways inflammation and associated asthma in adulthood in this murine surrogate.

Is Inhaler Technique Adequately Assessed and Reported in Clinical Trials of Asthma and Chronic Obstructive Pulmonary Disease Therapy? A Systematic Review and Suggested Best Practice Checklist.

BACKGROUND: Inhaled medications are central to treating asthma and chronic obstructive pulmonary disease (COPD), yet critical inhaler technique errors are made by up to 90% of patients. In the clinical research setting, recruitment of subjects with poor inhaler technique may give a false impression of both the benefits and the necessity of add-on treatments such as biologic therapies. OBJECTIVE: To assess the frequency with which inhaler technique is assessed and reliably optimized before and during patient enrollment into randomized controlled trials (RCTs) addressing the efficacy of topical therapy, and the escalation of therapy for asthma and COPD. METHODS: Systematic searches were conducted of PubMed and Embase for RCTs published in the past 10 years involving patients with a diagnosis of asthma or COPD undergoing escalation of baseline inhaled therapy (stepping up, changing, adding, switching, increasing, etc) or the introduction of biologic agents. RESULTS: Searches highlighted 1,014 studies, 118 of which were eligible after the removal of duplicates as well as screening and full text review. Of these, only 14 (11.9%) included accessible information in the methods section or referred to such information in online supplements or protocols concerning assessment of participants' inhaler technique. We therefore developed the proposed Best Practice Inhaler Technique Assessment and Reporting Checklist. CONCLUSIONS: Our study identifies a concerning lack of checking and correcting inhaler technique, or at least reporting that this was undertaken, before enrollment in asthma and COPD RCTs, which may affect the conclusions drawn. Mandating the use of a standardized checklist in RCT protocols and ensuring all published RCTs report checking and correcting inhaler technique before enrollment are important next steps.

Topical therapy with negative allosteric modulators of the calcium-sensing receptor (calcilytics) for the management of asthma: the beginning of a new era?

In this review article we present the evidence to date supporting the role of the calcium-sensing receptor (CaSR) as a key, pluripotential molecular trigger for asthma and speculate on the likely benefits of topical therapy of asthma with negative allosteric modulators of the CaSR: calcilytics.

B Cell Mobilization, Dissemination, Fine Tuning of Local Antigen Specificity and Isotype Selection in Asthma.

In order to better understand how the immune system interacts with environmental triggers to produce organ-specific disease, we here address the hypothesis that B and plasma cells are free to migrate through the mucosal surfaces of the upper and lower respiratory tracts, and that their total antibody repertoire is modified in a common respiratory tract disease, in this case atopic asthma. Using Adaptive Immune Receptor Repertoire sequencing (AIRR-seq) we have catalogued the antibody repertoires of B cell clones retrieved near contemporaneously from multiple sites in the upper and lower respiratory tract mucosa of adult volunteers with atopic asthma and non-atopic controls and traced their migration. We show that the lower and upper respiratory tracts are immunologically connected, with trafficking of B cells directionally biased from the upper to the lower respiratory tract and points of selection when migrating from the nasal mucosa and into the bronchial mucosa. The repertoires are characterized by both IgD-only B cells and others undergoing class switch recombination, with restriction of the antibody repertoire distinct in asthmatics compared with controls. We conclude that B cells and plasma cells migrate freely throughout the respiratory tract and exhibit distinct antibody repertoires in health and disease.

Repeated exposure to inactivated Streptococcus pneumoniae induces asthma-like pathological changes in mice in the presence of IL-33.

While environmental aeroallergens and epithelial alarmins such as IL-33 are firmly implicated in asthma, the possible role of Streptococcus pneumoniae (S. pneumoniae) antigens is less clear. To explore this, wild-type BALB/c mice were repeatedly challenged per-nasally with IL-33 and inactivated S. pneumoniae, either agent alone or diluent control. Some animals were rested then later re-challenged with inactivated S. pneumoniae alone. Serum concentrations of S. pneumoniae lysates-specific IgE were measured in patients with asthma and control subjects. Interestingly, in the presence of IL-33, repeated exposure to inactivated S. pneumoniae induced asthma-like pathological changes accompanied by a systemic adaptive immune response. Subsequent re-exposure of the sensitized animals to inactivated S. pneumoniae alone was able to induce such changes. The concentration of S. pneumoniae lysates-specific IgE was significantly elevated in the asthma patients. These data suggest that antigens derived from infectious microorganisms may participate in generating the mucosal inflammation which characterizes asthma.

IL-33 amplifies airways inflammation in a murine surrogate of asthma putatively via activation of dendritic cells.

Although contributions of IL-33 to pulmonary diseases, including asthma, have been well documented, the complexity of such regulation warrants additional exploration. To better understand the involvement of IL-33, we used a murine asthma surrogate based on sensitisation and challenge with dust mite extract in the presence/absence of IL-33. Murine models were established with Dermatophagoides farinae (Der f) to establish (1) the effect of co-administered rmIL-33; (2) the effect of prior glucocorticoid intervention; (3) the effect of IL-33 on challenge with sub-threshold dosage Der f. The effects of rmIL-33 on bone marrow-derived dendritic cells were explored in vitro. Mice challenged with Der f combined with IL-33 compared with diluent control evinced significantly more airways inflammation and local cytokine production which was less sensitive to inhibition by dexamethasone. IL-33 also induced airways hyperresponsiveness, eosinophilic inflammation and cytokine production in lung tissues of animals exposed to sub-threshold dosage of Der f. In vitro, IL-33-stimulated DCs showed a significantly elevated capacity to stimulate CD4+ T cell proliferation and cytokine production and were also significantly more resistant to dexamethasone-induced apoptosis. Our data suggest that IL-33 reduces the threshold for allergen-induced inflammation of the airways in acorticosteroid-resistant fashion possibly in part through acting on DCs, a phenomenon which may be relevant to the development of severe, corticosteroid-resistant airways obstruction in human asthmatic patients.

Role of the IL-33/ST2 axis in cigarette smoke-induced airways remodelling in chronic obstructive pulmonary disease.

BACKGROUND: Efficient therapy and potential prophylaxis are confounded by current ignorance of the pathogenesis of airway remodelling and blockade in COPD. OBJECTIVE: To explore the role of the IL-33/ST2 axis in cigarette smoke (CS) exposure-induced airways remodelling. METHODS: C57BL/6, BALB/c and IL-1RL1 -/- mice exposed to CS were used to establish an animal surrogate of COPD (air-exposed=5~8, CS-exposed=6~12). Hallmarks of remodelling were measured in mice. Cigarette smoke extract (CSE)-induced proliferation and protein production in vitro by fibroblasts in the presence of anti-interleukin-33 (anti-IL-33) or hST2 antibodies were measured. Expression of IL-33 and ST2 and other remodelling hallmarks were measured, respectively, in bronchoalveolar lavage fluid (BALF) (controls=20, COPD=20), serum (controls=59, COPD=90) and lung tissue sections (controls=11, COPD=7) from patients with COPD and controls. RESULTS: Wild-type mice exposed to CS elevated expression of hallmarks of tissue remodelling in the lungs and also in the heart, spleen and kidneys, which were significantly abrogated in the IL-1RL1 -/- mice. Fibroblasts exposed to CSE, compared with control, exhibited early cellular translocation of IL-33, accompanied by proliferation and elevated protein synthesis, all inhabitable by blockade of IL-33/ST2 signalling. Expression of IL-33 and ST2 and hallmarks of tissue remodelling were significantly and proportionally elevated in BALF, serum and tissue samples from patients with COPD. CONCLUSIONS: Exposure to CS induces remodelling changes in multiple organs. The data support the hypothesis that CS-induced lung collagen deposition is at least partly a result of CS-induced IL-33 translocation and release from local fibroblasts.

Calcilytics: a non-steroidal replacement for inhaled steroid and SABA/LABA therapy of human asthma?

INTRODUCTION: Asthma afflicts more than 300 million people. Contemporary mainstay therapies (inhaled corticosteroids and bronchodilators), prescribed empirically, control symptoms resulting from airways obstruction tolerably well in many patients but it is less clear that they alter the natural history of progressive airways inflammation and remodeling resulting in severe, therapy-resistant obstruction in a significant minority (5-10%), causing lifelong symptoms and elevated risk of recurrent hospital admission and death. Furthermore, no current anti-asthma drug targets bronchial smooth muscle hyperresponsiveness, a critical contributor to airways obstruction and the fundamental physiological abnormality characterizing asthma. Recent monoclonal antibody (biological) therapies reduce obstruction and exacerbations in some, but not all treated patients to an unpredictable extent, but are further limited by administration logistics and cost. AREAS COVERED: An overview of the cellular and molecular immunopathology of asthma, highlighting the need and logic for the development of a novel, non-steroidal, small molecule drug for topical delivery targeting bronchial smooth muscle hyperresponsiveness and airways inflammation, particularly corticosteroid-refractory inflammation. EXPERT OPINION: This article elaborates evidence supporting the hypothesis that topically delivered, inhaled antagonists of the calcium-sensing receptor (CaSR) have the potential to meet these requirements, and the practicality of repurposing existing, small molecule CaSR antagonists (calcilytics) for this purpose.

IL-33 induced airways inflammation is partially dependent on IL-9.

Asthma is an inflammatory disease of the airways and numerous cytokines contribute to this pathogenesis. It is shown that challenge of airways with IL-33 induces asthma-like pathological changes in mice, but the possible downstream cytokines in this process remain to be characterised. To explore this, we compared changes in the airways of wildtype (WT) and IL-9 deficient mice challenged with IL-33. In line with previous report, per-nasal challenge of WT mice with IL-33 significantly increased the responsiveness of the airways along with infiltration of inflammatory cells, goblet cell hyperplasia, collagen deposition and smooth muscle hypertrophy, and the expression of cytokines compared with control group. Surprisingly, all of these pathological changes were significantly attenuated in IL-9 deficient mice following identical IL-33 challenge. These data suggest that IL-9 is one downstream cytokine relevant to the effects of IL-33 in asthmatic airways and consequently a potential therapeutic target for the treatment of asthma.

Similarities and differences in the effects of sensitisation and challenge with Dermatophagoides farinae and Dermatophagoides pteronyssinus extracts in a murine asthma surrogate.

Patients with atopic asthma may become sensitised to the grain storage mite Dermatophagoides farinae (Der f), the house dust mite Dermatophagoides pteronyssinus (Der p) or both, but thus far little attention has been paid to date to possible variation in their pathophysiological effects. Here we present a side by side comparison of the effects of extracts of these two dust mites in a murine surrogate of atopic asthma. Compared with the Der p-challenged mice, however, the mice-challenged with Der f had favour changes in lung tissue elasticity and expression in matrix metalloproteinases in lung tissue, while the mice challenged with Der p showed more neutrophils infiltrating around the airway and stronger expression of steroid-resistant related cytokines in the lung tissue. Our data suggest that different dust mite crude extracts might lead different pathological characteristics, at least in murine models of asthma.

Combined blockade of IL-25, IL-33 and TSLP mediates amplified inhibition of airway inflammation and remodelling in a murine model of asthma.

BACKGROUND AND OBJECTIVE: Isolated blockade of IL-25, IL-33 and thymic stromal lymphopoietin (TSLP) has been shown to reduce airways inflammation and hyperresponsiveness in murine asthma model. The hypothesis that combined blockade of all three cytokines can accomplish this more effectively has never been addressed. METHODS: We studied a murine asthma model employing sensitization and challenge with ovalbumin (OVA) or saline control. To discern the effects of IL-33 blockade, we compared outcomes in strain identical, wild-type and IL-33 receptor (St2 -/- ) gene-deleted mice. We then examined, in the St2 -/- animals, the effects of additional, single or combined blockade of IL-25 and TSLP with blocking antibodies. Outcomes included airways reactivity, inflammatory cellular infiltration, epithelial cell metaplasia, deposition of fibrosis-related proteins, local Th2-type cytokine expression and total and specific serum IgE concentrations measured by ELISA and quantitative immunohistochemistry. RESULTS: St2 -/- gene deletion significantly reduced airways reactivity, inflammatory cellular infiltration, lung tissue expression of Th2 cytokines and fibrosis related proteins and serum total IgE in response to OVA sensitization and challenge. Additional administration of anti-IL-25 and anti-TSLP blocking antibodies to the St2 -/- mice further significantly reduced inflammation, Th2 cytokine expression, airways fibrosis and IgE production, while anti-TSLP alone reduced eosinophil infiltration and local IL-4 expression. The airways inflammatory cellular infiltrate and lung tissue expression of Th2 cytokine, but not fibrosis-related proteins were also reduced in the presence of isotype identical, control antibodies. CONCLUSION: Combined blockade of these three cytokines may better ameliorate airways pathological changes in this murine asthma model, with implications for human asthma.

Perceptions of COPD patients of the proposed withdrawal of inhaled corticosteroids prescribed outside guidelines: A qualitative study.

Global Initiative for Chronic Obstructive Lung Disease guidelines support the prescription of fixed combination inhaled corticosteroids (ICS) and long-acting ß-agonists in symptomatic COPD patients with frequent or severe exacerbations, with the aim of preventing them. ICS are frequently also prescribed to COPD patients with mild or moderate airflow limitation, outside guidelines, with the risk of unwanted effects. No investigation to date has addressed the views of these milder COPD patients on ICS withdrawal. The objective is to assess the views of COPD patients with mild or moderate airflow limitation on the staged withdrawal of ICS prescribed outside guidelines. One-to-one semi-structured qualitative interviews exploring COPD patients' views about ICS use and their attitudes to proposed de-prescription were conducted. Interviews were audio-recorded and transcribed verbatim. Thematic analysis was completed. Seventeen eligible COPD patients were interviewed. Many participants were not aware they were using an ICS. None was aware that prevention of exacerbations was the indication for ICS therapy or the risk of associated side effects. Some were unconcerned by what they perceived as low individual risk. Others expressed fears of worsening symptoms on withdrawal. Most with mild or moderate airflow limitation would have been willing to attempt withdrawal or titration to a lower dosage of ICS if advised by their clinician, particularly if a reasoned explanation were offered. Attitudes in this study to discontinuing ICS use varied. Knowledge of the drug itself, the indications for its prescription in COPD and potential for side effects, was scant. The proposed withdrawal of ICS is likely to be challenging and requires detailed conversations between patients and respiratory healthcare professionals.