Allergen Challenge Research Articles

Effects of Punctal Occlusion on Ocular Itching and Conjunctival Redness Associated with Allergic Conjunctivitis

Purpose Punctal occlusion using punctal plugs has been successfully used to treat the signs and symptoms of dry eye disease. However, the effects of punctal occlusion on the symptoms of allergic conjunctivitis (AC) have been less well documented. There is some concern among clinicians that punctal occlusion may make signs/symptoms of allergic conjunctivitis worse by trapping allergens on the eye. The objective of this post hoc analysis was to address this question and thus assess the effect of punctal occlusion alone on ocular itching and conjunctival redness associated with AC. Methods This was a pooled post hoc analysis of three randomized, double-blind, placebo insert-controlled clinical trials in subjects with AC. Enrolled subjects were generally healthy adults with ocular allergies and a positive skin test reaction to perennial and/or seasonal allergens. The study used a modified version of the traditional conjunctival allergen challenge (CAC) model, which included multiple, repeated allergen challenges following placement of the intracanalicular insert. Subjects were rechallenged on Days 6, 7 and 8; Days 13, 14 and 15; and Days 26, 27 and 28. Results The data set included 128 subjects that were administered placebo. Baseline mean (SD) ocular itching and conjunctival redness scores were 3.52 (0.44) and 2.97 (0.39), respectively. On post-insertion Days 7, 14 and 28, mean itching scores were 2.62, 2.26 and 1.91, respectively, representing 26%, 36% and 46% itching reductions, respectively (p < 0.001). On Days 7, 14 and 28, mean conjunctival redness scores were 1.98, 1.90, and 2.08, respectively, representing 33%, 36%, and 30% redness reductions, respectively (p < 0.001). Conclusions Based on this post hoc pooled analysis, punctal occlusion with a resorbable hydrogel intracanalicular insert did not worsen ocular itching or conjunctival redness in this patient population.

Profiles of immune infiltration in seasonal allergic rhinitis and related genes and pathways

BackgroundSeasonal allergic rhinitis (SAR) is a chronic inflammatory disease for which the molecular mechanism is unclear. MethodsWhole blood, CD4+ T cells in peripheral blood mononuclear cells (PBMCs), and CD4+ T cells in nasal mucosa from SAR-related datasets (GSE43497, GSE50223, and GSE49782) were downloaded from the Gene Expression Omnibus (GEO) database. Differences in SAR-associated immune cell infiltration in the PBMCs were analyzed using the CIBERSORT algorithm. Differential gene expression analysis was conducted between different groups. Gene set enrichment analysis (GSEA) was performed using the clusterProfiler package to explore functional changes in signaling pathways. ResultsThere was a significant increase in the proportion of CD8+ T cells and a significant decrease in the proportion of neutrophils in the whole blood of SAR patients after allergen challenge compared to SAR patients after diluent challenge. This pattern was also found in SAR patients compared to healthy controls (HCs) by flow cytometry. The NF-κB and Toll-like receptor signaling pathways were enriched in SAR patients following allergen challenge. The expression of CD4+ T cell marker genes and associated cytokines significantly differed between allergen-treated SAR patients, diluent-treated SAR patients and HCs. We also observed heightened CD4+ T cell related genes, cytokines and pathways activation in the nasal mucosa region of SAR patients after allergen challenge. ConclusionOur analysis revealed that T cell receptor signaling pathways, T helper 1 (Th1) /T helper 2 (Th2) cell differentiation may contribute to the development of SAR. The present study is the first bioinformatic analysis to quantify immune cell infiltration and identify underlying SAR mechanisms from combined microarray data and provides insight for further research into the molecular mechanisms of SAR.

Meta-omics profiling of the gut-lung axis illuminates metabolic networks and host-microbial interactions associated with elevated lung elastance in a murine model of obese allergic asthma.

Obesity and associated changes to the gut microbiome worsen airway inflammation and hyperresponsiveness in asthma. Obesogenic host-microbial metabolomes have altered production of metabolites that may influence lung function and inflammatory responses in asthma. To understand the interplay of the gut microbiome, metabolism, and host inflammation in obesity-associated asthma, we used a multi-omics approach to profile the gut-lung axis in the setting of allergic airway disease and diet-induced obesity. We evaluated an immunomodulator, nitro-oleic acid (NO2-OA), as a host- and microbial-targeted treatment intervention for obesity-associated allergic asthma. Allergic airway disease was induced using house dust mite and cholera toxin adjuvant in C57BL6/J mice with diet-induced obesity to model obesity-associated asthma. Lung function was measured by flexiVent following a week of NO2-OA treatment and allergen challenge. 16S rRNA gene (from DNA, taxa presence) and 16S rRNA (from RNA, taxa activity) sequencing, metabolomics, and host gene expression were paired with a Treatment-Measured-Response model as a data integration framework for identifying latent/hidden relationships with linear regression among variables identified from high-dimensional meta-omics datasets. Targeting both the host and gut microbiota, NO2-OA attenuated airway inflammation, improved lung elastance, and modified the gut microbiome. Meta-omics data integration and modeling determined that gut-associated inflammation, metabolites, and functionally active gut microbiota were linked to lung function outcomes. Using Treatment-Measured-Response modeling and meta-omics profiling of the gut-lung axis, we uncovered a previously hidden network of interactions between gut levels of amino acid metabolites involved in elastin and collagen synthesis, gut microbiota, NO2-OA, and lung elastance. Further targeted metabolomics analyses revealed that obese mice with allergic airway disease had higher levels of proline and hydroxyproline in the lungs. NO2-OA treatment reduced proline biosynthesis by downregulation of pyrroline-5-carboxylate reductase 1 (PYCR1) expression. These findings are relevant to human disease: adults with mild-moderate asthma and BMI ≥ 25 had higher plasma hydroxyproline levels. Our results suggest that changes to structural proteins in the lung airways and parenchyma may contribute to heightened lung elastance and serve as a potential therapeutic target for obese allergic asthma.

TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in allergic airway inflammation.

As a pattern recognition receptor which activates innate immune system, toll-like receptor 2 (TLR2) has been reportedly mediates allergic airway inflammation (AAI), yet the underlying mechanism remains elusive. Here, in a murine AAI model, TLR2-/- mice showed decreased airway inflammation, pyroptosis and oxidative stress. RNA-sequencing revealed that allergen-induced hif1 signaling pathway and glycolysis were significantly downregulated when TLR2 was deficient, which were confirmed by lung protein immunoblots. Glycolysis inhibitor 2-Deoxy-d-glucose (2-DG) inhibited allergen-induced airway inflammation, pyroptosis, oxidative stress and glycolysis in wild type (WT) mice, while hif1α stabilizer ethyl 3,4-dihydroxybenzoate (EDHB) restored theses allergen-induced changes in TLR2-/- mice, indicating TLR2-hif1α-mediated glycolysis contributes to pyroptosis and oxidative stress in AAI. Moreover, upon allergen challenge, lung macrophages were highly activated in WT mice but were less activated in TLR2-/- mice, 2-DG replicated while EDHB reversed such effect of TLR2 deficiency on lung macrophages. Likewise, both in vivo and ex vivo WT alveolar macrophages (AMs) exhibited higher TLR2/hif1α expression, glycolysis and polarization activation in response to ovalbumin (OVA), which were all inhibited in TLR2-/- AMs, suggesting AMs activation and metabolic switch are dependent on TLR2. Finally, depletion of resident AMs in TLR2-/- mice abolished while transfer of TLR2-/- resident AMs to WT mice replicated the protective effect of TLR2 deficiency on AAI when administered before allergen challenge. Collectively, we suggested that loss of TLR2-hif1α-mediated glycolysis in resident AMs ameliorates allergic airway inflammation that inhibits pyroptosis and oxidative stress, therefore the TLR2-hif1α-glycolysis axis in resident AMs may be a novel therapeutic target for AAI.

Neonatal helminth infection and chronic type 2 inflammation promotes immune suppression through FcγRIIb

Abstract Allergic diseases are rising in industrialized countries. This contrasts with rural communities where decreased allergic incidence correlates with increased prevalence of intestinal helminth infections. While helminths and their byproducts can ameliorate allergic inflammation in adult mice with established disease, it remains unknown if early-life exposure can prevent or delay allergic disease onset. We utilized a neonatal infection model with the gastrointestinal helminth Heligmosomoides polygyrusand found that neonatal H. polygyruscolonization results in chronic infection and type 2 inflammation. This study investigates how chronic and systemic type 2 hallmarks IL-4 and IgG1 may be involved in the long-term suppressive mechanisms induced by neonatal helminth colonization. We hypothesize that IL-4-induced upregulation of the sole inhibitory Fc receptor, FcγRIIb, allows for sustained suppression of T cell mediated inflammation by increasing the activation threshold of antigen presenting cells. Increasing this threshold prevents allergen-specific T cells from becoming optimally activated and instead promotes T cell tolerance. In addition to IL-4 increasing expression of FcγRIIb on macrophages, it promotes the production of its ligand IgG1, completing the suppressive circuit. This model predicts that elimination of FcγRIIb and/or IL-4 will result in greater T cell activation and allergic inflammation. Our in vivoand in vitrodata show that FcγRIIb is necessary for reducing allergic airway inflammation and T cell activation after allergen challenge. Taken together, these data support a model in which chronic helminth infection naturally mimics the suppressive effects of intravenous immunoglobulin therapy. Supported by the National Institutes of Health NIAID training grant (Training Program in Immunology; T32-AI07405)

Comparison of intrinsic allergenicity potentials of gliadins from durum and soft white wheats in an adjuvant-free mouse model

Abstract Wheat is one of the major allergenic foods capable of eliciting life-threatening anaphylaxis. Discovering potential hypo/hyper-allergenic wheat classes is imperative to advance our knowledge and manage wheat allergy. Durum wheat (genome AABB) and soft white wheat (genome AABBDD) are two commonly consumed wheats. However, whether there are differences in the intrinsic allergenicity potential between them is unknown. Here, we tested the hypothesis that gliadins extracted from durum and soft white wheats will differ in their intrinsic allergenicity in an adjuvant-free mouse model that uses skin sensitization followed by intraperitoneal (IP) allergen challenge. Balb/c female mice were produced and maintained on a plant protein-free diet during this study. Groups of mice (n=5–10/group) were exposed to gliadins or vehicle via the skin once a week for 9 weeks. IgE responses were analyzed by ELISA to determine sensitization. Systemic anaphylaxis upon IP challenge was quantified by hypothermic shock response (HSR); mucosal mast cell response (MMCR) was quantified by measuring MMCP-1 in the blood. Our results suggest that mice exhibited robust, but comparable levels of specific IgE antibody responses after skin exposures to both wheat gliadins elicited. HSRs induced upon IP challenges with gliadins from the two wheats displayed strikingly similar kinetics. Interestingly, soft white wheat gliadin was significantly more potent in eliciting MMCR compared to the durum wheat gliadin. We demonstrate for the first-time the similarities and differences in intrinsic allergenicity potentials of gliadins obtained from the two wheats. Supported by grants from USDA/NIFA Hatch Project MICL02486 (Accession Number: 1012322)

Probiotic-derived exopolysaccharide interferes with T H2 priming and inhibits allergic inflammation

Abstract Allergic asthma is an increasing burden in industrialized countries, where treatments are limited to targeting symptoms and end-stage effectors rather than root causes. In recent years, the use of prophylactic, inhaled probiotic cocktails has shown promise in preventing allergic asthma. However, the mechanisms by which such probiotics prevent allergic symptoms and the exact bacterial product(s) responsible for probiotic activity remain to be elucidated. In this study, we focused on exopolysaccharide (EPS) from Bacillus subtilis, a ubiquitous soil bacterium that is commonly found as a dietary supplement. We found that in a mouse model of allergic airway disease, EPS treatment, prior to allergic sensitization and challenge, limits lung mucus hypersecretion and eosinophilia. Furthermore, EPS treatment inhibited accumulation of T H2, but not T H1 and T H17 subsets. To determine whether EPS was affecting T H2 cell priming by dendritic cells (DCs), we compared the composition and phenotype of DCs in the lung and mediastinal lymph nodes (medLN) after EPS treatment. Surprisingly, pre-treatment with EPS induced DC maturation as measured by an increase in costimulatory molecules and a decrease in the ability to uptake allergen and migrate to the medLN. DC maturation by EPS was TLR4-dependent, as TLR4 KO DCs did not respond to EPS. Together, our data suggest that EPS inhibits allergic sensitization by inducing DC maturation prior to allergen exposure, thereby leading to decreased T H2 priming and allergic inflammation. Thus, we provide a potential mechanism by which inhalation of a single probiotic-derived molecule can prevent the development of allergic inflammation. Supported by grants from NIH (3R01 AI125644-05S1, 1F31 HL156659-01A1)

Evaluation of salt-soluble protein extract from an ancient wheat progenitor (Aegilops tauschii) for intrinsic allergenicity in an adjuvant-free mouse model of wheat allergy

Abstract Wheat allergies are a growing significant health concern around the globe. The ancient diploid wheat progenitor, Aegilops tauschii (genome DD), contributed to the genetic diversity of the common soft white wheat (Triticum aestivum, genomes AABBDD). The allergenic potential of Ae. tauschii is largely unknown. Here we tested the hypothesis that the the salt-soluble protein extract (SSPE) from Ae. tauschii will be intrinsically allergenic in an adjuvant-free mouse model of wheat allergy. The ancient wheat progenitor was grown at the Michigan State University greenhouse using the seeds stored at our wheat breeding program. The SSPE was prepared, characterized for quality, and then tested in the mouse model that uses skin sensitization followed by oral allergen challenge. Balb/c mice were produced and maintained on a plant protein-free diet. Groups of adult mice (n=10/group) were repeatedly exposed to SSPE or vehicle via the skin. Allergic sensitization was assessed by specific IgE (sIgE) response. Oral anaphylaxis was quantified by hypothermic shock response (HSR). The mucosal mast cell response (MMCR) was quantified by measuring MMCP-1 in the blood. Repeated skin exposure to SSPE but not the vehicle elicited robust sIgE response. Oral SSPE challenge but not vehicle challenge elicited significant, but a modest HSR as well as MMCR. In summary, we report the characterization of intrinsic allergenicity potential of the SSPE obtained from the Ae. tauschii wheat progenitor for the first time. Funding: USDA/NIFA. The United States Department of Agriculture (USDA)/National Institute of Food and Agriculture (NIFA); Hatch project MICL02486 (Accession Number: 1012322); Hatch project MICL01699; Agricultural and Food Research Initiative Competitive Program, grant number: 2018-67017-27876

Organ-specific allergen challenges in airway allergy: current utilities and future directions.

Atopy has been long used as the screening method for airway allergy. Nevertheless, aeroallergens can trigger respiratory symptoms not only in atopic patients (atopic respiratory allergy, ARA), but also in non-atopic subjects (local respiratory allergy, LRA). Moreover, ARA and LRA can coexist in the same patient, and this clinical scenario has been called dual respiratory allergy (DRA). When the clinical history cannot determine the relevance of sensitizations in ARA patients, nasal, conjunctival or bronchial allergen challenges (NAC, CAC and BAC, respectively) should be conducted. Moreover, these tests are required to identify patients with LRA and DRA. The clarification of the allergic triggers of airway diseases has a profound impact on the management strategies the patients can be offered. Importantly, allergen immunotherapy (AIT) remains as the only disease-modifying intervention for ARA. Recent data indicate that AIT might have a similar effect on LRA patients. Nevertheless, AIT success relies largely on the correct phenotyping of allergic individuals, and NAC, CAC and BAC are very helpful tools in this regard. In this review, we will summarize the main indications and methodology of CAC, NAC and BAC. Importantly, the clinical implementation of these tests might translate into precision medicine approaches and better health outcomes for patients with airway allergy.

IgG:FcγRIIb signals block effector programs of IgE:FcεRI-activated mast cells but spare survival pathways

IgE-induced mast cell (MC) degranulation can be inhibited by IgG antibodies, signaling via FcγRIIb, but the effects of IgG on IgE-induced MC transcription are unknown. We sought to assess inhibitory IgG:FcγRIIb effects on MC responses to IgE using complementary transcriptomic and functional approaches. RNA sequencing was performed on bone marrow-derived MCs from wild-type and FcγRIIb-deficient mice to identify genes activated following IgE receptor crosslinking that were further modulated in the presence of antigen-specific IgG in an FcγRIIb-dependent fashion. Parallel analyses of signaling pathways and allergic responses invivo were performed to assess the impact of these changes in gene expression. Rapid changes in the transcription of 879 genes occurred in MCs activated by IgE, peaking at 1 hour. Surprisingly, only 12% of these were altered by IgG signaling via FcγRIIb, including numerous transcripts involved in orchestrating type 2 responses linked to spleen tyrosine kinase signaling. Consistent with this finding, IgG suppressed IgE-induced phospho-intermediates in the spleen tyrosine kinase signaling pathway. Invivo studies confirmed that the IgG-mediated suppression of both systemic anaphylaxis and MC-driven tissue recruitment of inflammatory cells following allergen challenge was dependent on FcγRIIb. In contrast, genes in the STAT5a cell survival pathway were unaltered by IgG, and STAT5a phosphorylation increased after IgE-induced MC activation but was unaffected by IgG. Our findings indicate that inhibitory IgG:FcγRIIb signals block an IgE-induced proallergic program but spare a prosurvival program.

CD4+ T cells inhibit the generation of CD8+ epidermal-resident memory T cells directed against clinically relevant contact allergens.

CD8+ epidermal-resident memory T (TRM ) cells play central roles in local flare-up responses to experimental contact allergens by inducing massive influx of neutrophils to the epidermis upon allergen challenge. Whether similar immunopathogenic mechanisms are involved in the responses to clinically relevant contact allergens is unknown. The immune response to cinnamal, ρ-phenylenediamine (PPD) and methylisothiazolinone (MI) was studied in a well-established mouse model for allergic contact dermatitis that includes formation of TRM cells by ELISA, flow cytometry, fluorescence microscopy analyses and cell depletion protocols. We show that the formation of CD4+ and CD8+ epidermal TRM cells and the inflammatory response are highly allergen-dependent. However, the magnitude of the flare-up responses correlated with the number of epidermal CD8+ TRM cells, CXCL1/CXCL2 release and recruitment of neutrophils to the epidermis. Finally, depletion of CD4+ T cells strongly enhanced the number of epidermal CD8+ TRM cells, the flare-up response and the epidermal infiltration of neutrophils for all allergens. As the first, this study demonstrates that clinically relevant contact allergens have the ability to generate pathogenic, epidermal CD8+ TRM cells that recruit neutrophils following re-exposure to the allergen, but that this normally is counteracted by the simultaneous induction of anti-inflammatory CD4+ T cells.

The next generation virus-like particle platform for the treatment of peanut allergy.

Allergy to peanut is one of the leading causes of anaphylactic reactions among food allergic patients. Immunization against peanut allergy with a safe and protective vaccine holds a promise to induce durable protection against anaphylaxis caused by exposure to peanut. A novel vaccine candidate (VLP Peanut), based on virus-like particles (VLPs), is described here for the treatment of peanut allergy. VLP Peanut consist of two proteins: a capsid subunit derived from Cucumber mosaic virus engineered with a universal T cell epitope (CuMVTT ) and a CuMVTT subunit fused with peanut allergen Ara h 2 (CuMVTT -Ara h 2), forming mosaic VLPs. Immunizations with VLP Peanut in both naïve and peanut-sensitised mice resulted in a significant anti-Ara h 2 IgG response. Local and systemic protection induced by VLP Peanut were established in mouse models for peanut allergy following prophylactic, therapeutic and passive immunizations. Inhibition of FcγRIIb function resulted in a loss of protection, confirming the crucial role of the receptor in conferring cross protection against peanut allergens other than Ara h 2. VLP Peanut can be delivered to peanut-sensitized mice without triggering allergic reactions, whilst remaining highly immunogenic and offering protection against all peanut allergens. In addition, vaccination ablates allergic symptoms upon allergen challenge. Moreover, the prophylactic immunization setting conferred the protection against subsequent peanut-induced anaphylaxis, showing the potential for preventive vaccination. This highlights the effectiveness of VLP Peanut as a prospective break-through immunotherapy vaccine candidate towards peanut allergy. VLP Peanut has now entered clinical development with the study PROTECT.

Cystic Fibrosis Reprograms Airway Epithelial IL-33 Release and Licenses IL-33-Dependent Inflammation.

Rationale: Type 2 inflammation has been described in people with cystic fibrosis (CF). Whether loss of CFTR (cystic fibrosis transmembrane conductance regulator) function contributes directly to a type 2 inflammatory response has not been fully defined. Objectives: The potent alarmin IL-33 has emerged as a critical regulator of type 2 inflammation. We tested the hypothesis that CFTR deficiency increases IL-33 expression and/or release and deletion of IL-33 reduces allergen-induced inflammation in the CF lung. Methods: Human airway epithelial cells (AECs) grown from non-CF and CF cell lines and Cftr+/+ and Cftr-/- mice were used in this study. Pulmonary inflammation in Cftr+/+ and Cftr-/- mice with and without IL-33 or ST2 (IL-1 receptor-like 1) germline deletion was determined by histological analysis, BAL, and cytokine analysis. Measurements and Main Results: After allergen challenge, both CF human AECs and Cftr-/- mice had increased IL-33 expression compared with control AECs and Cftr+/+ mice, respectively. DUOX1 (dual oxidase 1) expression was increased in CF human AECs and Cftr-/- mouse lungs compared with control AECs and lungs from Cftr+/+ mice and was necessary for the increased IL-33 release in Cftr-/- mice compared with Cftr+/+ mice. IL-33 stimulation of Cftr-/- CD4+ T cells resulted in increased type 2 cytokine production compared with Cftr+/+ CD4+ T cells. Deletion of IL-33 or ST2 decreased both type 2 inflammation and neutrophil recruitment in Cftr-/- mice compared with Cftr+/+ mice. Conclusions: Absence of CFTR reprograms airway epithelial IL-33 release and licenses IL-33-dependent inflammation. Modulation of the IL-33/ST2 axis represents a novel therapeutic target in CF type 2-high and neutrophilic inflammation.

Dysbiotic lung microbial communities of neonates from allergic mothers confer neonate responsiveness to suboptimal allergen.

In humans and animals, offspring of allergic mothers have increased responsiveness to allergens. This is blocked in mice by maternal supplementation with α-tocopherol (αT). Also, adults and children with allergic asthma have airway microbiome dysbiosis with increased Proteobacteria and may have decreased Bacteroidota. It is not known whether αT alters neonate development of lung microbiome dysbiosis or whether neonate lung dysbiosis modifies development of allergy. To address this, the bronchoalveolar lavage was analyzed by 16S rRNA gene analysis (bacterial microbiome) from pups of allergic and non-allergic mothers with a basal diet or αT-supplemented diet. Before and after allergen challenge, pups of allergic mothers had dysbiosis in lung microbial composition with increased Proteobacteria and decreased Bacteroidota and this was blocked by αT supplementation. We determined whether intratracheal transfer of pup lung dysbiotic microbial communities modifies the development of allergy in recipient pups early in life. Interestingly, transfer of dysbiotic lung microbial communities from neonates of allergic mothers to neonates of non-allergic mothers was sufficient to confer responsiveness to allergen in the recipient pups. In contrast, neonates of allergic mothers were not protected from development of allergy by transfer of donor lung microbial communities from either neonates of non-allergic mothers or neonates of αT-supplemented allergic mothers. These data suggest that the dysbiotic lung microbiota is dominant and sufficient for enhanced neonate responsiveness to allergen. Importantly, infants within the INHANCE cohort with an anti-inflammatory profile of tocopherol isoforms had an altered microbiome composition compared to infants with a pro-inflammatory profile of tocopherol isoforms. These data may inform design of future studies for approaches in the prevention or intervention in asthma and allergic disease early in life.

Symptom Assessment of Patients with Allergic Rhinitis Using an Allergen Exposure Chamber

Allergen exposure chambers (AECs) are clinical facilities that allow the exposure of participants to allergenic and non-allergenic airborne particles. They provide stable particle concentrations under controlled environmental conditions. This is of great importance both for diagnostic purposes and for the monitoring of treatment effects. Here, a protocol and the technical prerequisites for performing a safe and effective allergen challenge in subjects sensitized to airborne allergens (i.e., house dust mite [HDM]) in the ALL-MED AEC are presented. With this method, triggering allergic symptoms corresponds to natural exposure. This can be used for an allergy diagnosis or as a plausible endpoint in clinical trials, particularly for allergen immunotherapy (AIT). A controlled environment (temperature, humidity, and carbon dioxide [CO2]) in the chamber must be maintained. Allergen particles must be dispersed evenly within the AEC at stable levels throughout the challenge. For this presentation, allergic rhinitis (AR) patients sensitive to HDM allergens were enrolled. AR symptoms were assessed by the following parameters: total nasal symptom score (TNSS), acoustic rhinometry (ARM), peak nasal inspiratory flow (PNIF), and nasal secretion weight. The safety of the procedure was assessed by the peak expiratory flow rate (PEFR) and the forced expiratory volume in the first second (FEV1). The allergic subjects developed symptoms within 120 min of the trial. On average, the most intense symptoms appeared after 60-90 min and, after reaching a plateau, remained stable until the end of the trial.

Vertical sleeve gastrectomy associates with airway hyperresponsiveness in a murine model of allergic airway disease and obesity.

Asthma is a chronic airway inflammatory disease marked by airway inflammation, remodeling and hyperresponsiveness to allergens. Allergic asthma is normally well controlled through the use of beta-2-adrenergic agonists and inhaled corticosteroids; however, a subset of patients with comorbid obesity experience resistance to currently available therapeutics. Patients with asthma and comorbid obesity are also at a greater risk for severe disease, contributing to increased risk of hospitalization. Bariatric surgery improves asthma control and airway hyperresponsiveness in patients with asthma and comorbid obesity, however, the underlying mechanisms for these improvements remain to be elucidated. We hypothesized that vertical sleeve gastrectomy (VSG), a model of metabolic surgery in mice, would improve glucose tolerance and airway inflammation, resistance, and fibrosis induced by chronic allergen challenge and obesity. Male C57BL/6J mice were fed a high fat diet (HFD) for 13 weeks with intermittent house dust mite (HDM) allergen administration to induce allergic asthma, or saline as control. At week 11, a subset of mice underwent VSG or Sham surgery with one week recovery. A separate group of mice did not undergo surgery. Mice were then challenged with HDM or saline along with concurrent HFD feeding for 1-1.5 weeks before measurement of lung mechanics and harvesting of tissues, both of which occurred 24 hours after the final HDM challenge. Systemic and pulmonary cytokine profiles, lung histology and gene expression were analyzed. High fat diet contributed to increased body weight, serum leptin levels and development of glucose intolerance for both HDM and saline treatment groups. When compared to saline-treated mice, HDM-challenged mice exhibited greater weight gain. VSG improved glucose tolerance in both saline and HDM-challenged mice. HDM-challenged VSG mice exhibited an increase in airway hyperresponsiveness to methacholine when compared to the non-surgery group. The data presented here indicate increased airway hyperresponsiveness in allergic mice undergoing bariatric surgery.

Nasal allergen challenge (NAC): Practical aspects and applications from an EU/US perspective—a Work Group Report of the AAAAI Rhinitis, Rhinosinusitis and Ocular Allergy Committee

Nasal allergen challenge (NAC) is applied in a variety of settings (research centres, specialty clinics and hospitals) as a useful diagnostic and research tool. NAC is indicated for diagnosis of seasonal and perennial allergic rhinitis, local allergic rhinitis, occupational rhinitis, to design the composition of allergen immunotherapy in polysensitized patients and to investigate the physio-pathological mechanisms of nasal diseases. NAC is currently a safe and reproducible technique, although it is time and resource consuming. NAC can be performed by a variety of methods, but the lack of a uniform technique for performing and recording the outcomes, represents a challenge for those considering NAC as a clinical tool in the office. The availability of standardized allergens for NAC is also different in each country. The objective of this workgroup report is to review the current information about NAC, focusing on the practical aspects and application for diagnosis of difficult rhinitis phenotypes (e.g. local allergic rhinitis, occupational rhinitis), taking into account the particular context of practice in the United States and the European Union.

CX3CR1+ Macrophage Facilitates the Resolution of Allergic Lung Inflammation via Interacting CCL26.

Rationale: The resolution of inflammation is an active process coordinated by mediators and immune cells to restore tissue homeostasis. However, the mechanisms for resolving eosinophilic allergic lung inflammation triggered by inhaled allergens have not been fully elucidated. Objectives: Our objectives were to investigate the cellular mechanism of tissue-resident macrophages involved in the resolution process of eosinophilic lung inflammation. Methods: For the study, we used the institutional review board-approved protocol for human subsegmental bronchoprovocation with allergen, mouse models for allergic lung inflammation, and novel transgenic mice, including a conditional CCL26 knockout. The samples were analyzed using mass cytometry, single-cell RNA sequencing, and biophysical and immunological analyses. Measurements and Main Results: We compared alveolar macrophage (AM) subsets in the BAL before and after allergen provocation. In response to provocation with inhaled allergens, the subsets of AMs are dynamically changed in humans and mice. In the steady state, the AM subset expressing CX3CR1 is a relatively small fraction in bronchoalveolar space and lung tissue but drastically increases after allergen challenges. This subset presents unique patterns of gene expression compared with classical AMs, expressing high C1q family genes. CX3CR1+ macrophages are activated by airway epithelial cell-derived CCL26 via a receptor-ligand interaction. The binding of CCL26 to the CX3CR1+ receptor induces CX3CR1+ macrophages to secrete C1q, subsequently facilitating the clearance of eosinophils. Furthermore, the depletion of CX3CR1 macrophages or CCL26 in airway epithelial cells delays the resolution of allergic lung inflammation displaying prolonged tissue eosinophilia. Conclusions: These findings indicate that the CCL26-CX3CR1 pathway is pivotal in resolving eosinophilic allergic lung inflammation.

Triple-tyrosine kinase inhibition by BIBF1000 attenuates airway and pulmonary arterial remodeling following chronic allergen challenges in mice

BackgroundAirway remodeling is an important pathological feature of chronic airway diseases, which leads to a progressive decline in lung function. The present study examined the anti-remodeling and anti- inflammatory effect of BIBF1000, a triple-tyrosine kinase inhibitor that targets VEGF, PDGF, and FGF receptor signaling in a mouse model of repeated ovalbumin (OVA) challenges.MethodsFemale Balb-c mice were immunized intraperitoneally on days 0 and 12 with 50 µg ovalbumin plus 1 mg of Al(OH)3 in 200 μl saline. Intranasal OVA challenges (20 µg/50 µl in PBS) were administered on days 26, 29, and 31, and were repeated twice a week for 3 months. Animals received vehicle or BIBF1000 (25 mg/kg, b.i.d.) through gavage from day 26 to the end of fourth month. On day 120, bronchoalveolar lavage (BAL) and lung tissue were collected for biochemical and immunohistological analysis.ResultsCompared to vehicle controls, treatment with BIBF1000 reduced the numbers of BAL eosinophils, macrophages, neutrophils, and lymphocytes by 70.0%, 57.9%, 47.5%, and 63.0%, respectively, and reduced IL-5 and IL-13 in BAL. Treatment with BIBF1000 reduced airway mucus secretion, peribronchial fibrosis, small airway, and pulmonary arterial wall thickness, compared to vehicle controls. Furthermore, treatment with BIBF1000 also reduced the expression of inflammatory mediators (TNF-α, IL-1β, IL-5, IL-13, MMP-2, MMP-9, COX-2, and iNOS) and inhibited ERK and AKT phosphorylation.ConclusionsThe protective effect afforded by triple-tyrosine kinase inhibition with BIBF1000 in reducing allergen-induced airway and arterial remodeling was associated with down-regulation of inflammatory mediators, as well as inhibition of ERK and AKT signaling pathways.

YKL-40 as a possible marker of neutrophilic asthma.

Asthma is a heterogeneous chronic disorder of the airways, with inflammation and bronchial hyperresponsiveness as its major underlying phenomena. Asthmatics vary in terms of inflammation pattern, concomitant pathologies, and factors aggravating the course of the disease. As a result, there is a need for sensitive and specific biomarkers that could facilitate diagnosing asthma as well as phenotyping in everyday practice. Chitinases and chitinase-like proteins (CLPs) seem promising in this field. Chitinases are evolutionarily conserved hydrolases that degrade chitin. In contrast, CLPs bind chitin but do not have degrading activity. Mammalian chitinases and CLPs are produced by neutrophils, monocytes, and macrophages in response to parasitic or fungal infections. Recently, several questions have been raised about their role in chronic airway inflammation. Several studies demonstrated that overexpression of CLP YKL-40 was associated with asthma. Moreover, it correlated with exacerbation rate, therapy resistance, poor control of symptoms, and, inversely, with FEV1. YKL-40 facilitated allergen sensitization and IgE production. Its concentration was elevated in bronchoalveolar lavage fluid after an allergen challenge. It was also found to promote the proliferation of bronchial smooth muscle cells and correlate with subepithelial membrane thickness. Thus, it may be involved in bronchial remodeling. Associations between YKL-40 and particular asthma phenotypes remain unclear. Some studies showed that YKL-40 correlates with blood eosinophilia and FeNO, suggesting a role in T2-high inflammation. Quite the opposite, cluster analyses revealed the highest upregulation in severe neutrophilic asthma and obesity-associated asthma. The main limitation in the practical application of YKL-40 as a biomarker is its low specificity. High serum levels of YKL-40 were also found in COPD and several malignancies, in addition to infectious and autoimmune diseases. To conclude, the level of YKL-40 correlates with asthma and some clinical features in the whole asthmatic population. The highest levels are found in neutrophilic and obesity-related phenotypes. However, due to its low specificity, the practical application of YKL-40 remains uncertain but could be useful in phenotyping, especially when combined with other biomarkers.