Mechanisms of allergen-specific immunotherapy and immune tolerance to allergens

Masked Delivery of Allergen in Nanoparticles Safely Attenuates Anaphylactic Response in Murine Models of Peanut Allergy

Food allergy is a growing health concern worldwide. Current allergen-specific immunotherapy (AIT) approaches require frequent dosing over extended periods of time and may induce anaphylaxis due to allergen-effector cell interactions. A critical need remains to develop novel approaches that refine AIT for the treatment of food allergies. Previous studies show that poly(lactide-co-glycolide) (PLG) nanoscale particles (NP) effectively suppress Th1- and Th17-driven immune pathologies. However, their ability to suppress the distinct Th2-polarized immune responses driving food allergy are unknown. Herein, we describe the safety and efficacy of NPs containing encapsulated peanut allergen in desensitizing murine models of peanut allergy. Peanut extract encapsulation allowed for the safe intravenous delivery of allergen relative to non-encapsulated approaches. Application of 2–3 doses, without the need for dose escalation, was sufficient to achieve prophylactic and therapeutic efficacy, which correlated with suppression of Th2-mediated disease and reduced mast cell degranulation. Efficacy was associated with strong reductions in a broad panel of Th1, Th2, and Th17 cytokines. These results demonstrate the ability of PLG NPs to suppress allergen-specific immune responses to induce a more tolerogenic phenotype, conferring protection from intragastric allergen challenge. These promising studies represent a step forward in the development of improved immunotherapies for food allergy.

Effects of Local Nasal Immunotherapy with FIP-fve Peptide and Denatured Tyrophagus putrescentiae for Storage Mite-Induced Airway Inflammation

Allergic diseases are affecting public health and have increased over the last decade. Sensitization to mite allergens is a considerable trigger for allergy development. Storage mite-Tyrophagus putrescentiae shows great significance of allergenic potential and clinical relevance. The fungal immunomodulatory peptide FIP-fve has been reported to possess immunomodulatory activity. We aimed to determine whether T. putrescentiae-induced sensitization and airway inflammation in mice could be downregulated by FIP-fve in conjunction with denatured T. putrescentiae (FIP-fve and DN-Tp). Immune responses and physiologic variations in immunoglobulins, leukocyte subpopulations, cytokine productions, pulmonary function, lung pathology, cytokines in CD4⁺ and Treg cells were evaluated after local nasal immunotherapy (LNIT). After the LNIT with FIP-fve and DN-Tp, levels of specific IgE, IgG1, and IgG2a in the sera and IgA in the bronchoalveolar lavage fluid (BALF) were significantly reduced. Infiltrations of inflammatory leukocytes (eosinophils, neutrophils, and lymphocytes) in the airway decreased significantly. Production of proinflammatory cytokines (IL-5, IL-13, IL-17F and IL-23) and chemokine (IL-8) were significantly reduced, and Th1-cytokine (IL-12) increased in the airway BALF after LNIT. Pulmonary functions of Penh values were significantly decreased after the methacholine challenge, which resulted in a reduction of airway hypersensitivity after LNIT. Bronchus pathology showed a reduction of inflammatory cell infiltration and epithelium damage after LNIT. The IL-4⁺/CD4⁺ T cells could be downregulated and the IFN-γ⁺/CD4⁺ T cells upregulated. The Treg-related immunity of IL-10 and Foxp3 expressions in CD4⁺CD25⁺ cells were both upregulated after LNIT. In conclusion, LNIT with FIP-fve and DN-Tp had an anti-inflammatory effect on mite-induced airway inflammations and possesses potential as an immunomodulatory therapy agent for allergic airway diseases.

Sophora flavescens Alkaloids and Corticosteroid Synergistically Augment IL-10/IL-5 Ratio with Foxp3-Gene-Epigenetic Modification in Asthma PBMCs

Background

It has been demonstrated that ASHMI (antiasthma-simplified herbal medicine intervention) can improve airway function and reduce inflammation in human asthmatic patients with high safety and tolerability. In addition, ASHMI significantly suppresses Th2 cytokine production and increases Th1 cytokine production in treating asthma.

Objective

Allergic asthma is associated with dysregulation of cytokines. We focused on IL-5 and IL-10 as signature Th2 and Treg cytokines to characterize ASHMI immunomodulatory components.

Methods

The effects of ASHMI and individual herbal constituents on IL-5 and IL-10 production by PBMCs from asthmatic subjects were determined ex vivo. Sophora flavescens (SF)-F2, containing alkaloid compounds, effects on PBMC IL-10 and IL-5 production in the presence or absence of dexamethasone (Dex), and on DNA methylation levels at the foxp3 gene promoter were determined.

Results

The ratio of anti-CD3/CD28 stimulated IL-10/IL-5 production by PBMCs from asthmatic subjects was significantly reduced compared to healthy subjects. In PBMCs from asthmatic subjects, ASHMI significantly reduced IL-5 production and increased IL-10 secretion in a dose-dependent manner (p < 0.05–0.01). SF-F2 was most effective in increasing IL-10, whereas SF-F4 (flavonoid compounds) was most effective in suppressing IL-5 production. Dex-treated PBMCs from asthma subjects showed a trend of increasing ratio of IL-10/IL-5 while demonstrating reduced levels in both IL-5 and IL-10 (p < 0.05). Co-culture with Dex and SF-F2 significantly prevented Dex suppression of IL-10, while retained Dex-suppression of IL-5 production, and increased IL-10/IL-5 ratio by Dex. Co-culture with SF-F2 and Dex significantly reduced DNA methylation levels at the foxp3 gene promoter at CpG⁻¹²⁶.

Conclusion

The SF alkaloid-rich fraction may be responsible for ASHMI induction of IL-10 production by PBMCs and plays a synergistic effect with Dex for augmenting IL-10/IL-5 ratio.

Bet v 1-displaying elastin-like polypeptide nanoparticles induce a strong humoral and weak CD4+ T-cell response against Bet v 1 in a murine immunogenicity model

There is growing concern about the toxicity of colloidal aluminum salts used as adjuvants in subcutaneous allergen immunotherapy (SCIT). Therefore, alternative adjuvants and delivery systems are being explored to replace alum in SCIT. We applied micellar elastin-like polypeptides (ELPs), a type of self-assembling protein, to replace alum as vaccine adjuvant in birch pollen SCIT. ELP and an ELP-Bet v 1 fusion protein were expressed in E. coli and purified by immuno-affinity chromatography and inverse-transition cycling (ITC). Nanoparticles self-assembled from ELP and a 9:1 ELP/ELP-Bet v 1 mixture were characterized by using dynamic light scattering and atomic force microscopy. Allergenicity was assessed by measuring mediator release from rat basophilic leukemia cells transformed with the human FcϵR1 and sensitized with sera derived from human birch pollen allergic patients. Humoral and T-cell immunity were investigated by immunizing naïve mice with the ELP/ELP-Bet v 1 nanoparticles or alum-adsorbed Bet v 1, both containing 36 µg Bet v 1. ELP and ELP/ELP-Bet v 1 self-assembled at 37°C into spherically shaped micelles with a diameter of ~45 nm. ELP conjugation made Bet v 1 hypo-allergenic (10-fold). Compared to alum-adsorbed Bet v 1, ELP/ELP-Bet v 1 nanoparticles induced stronger IgG responses with an earlier onset. Additionally, ELP/ELP-Bet v 1 did not induce Th2 skewing cytokines and IgE. The hypoallergenic character and strong humoral immune response in the absence of a Th2-skewing T-cell response make ELP-based nanoparticles a promising candidate to replace alum in SCIT.

Atopic dermatitis: Current standards of diagnosis and treatment, including the latest methods of management

Atopic dermatitis (AD) is a chronic relapsing disease which causes characteristic eczematous skin lesions. The most common symptoms of atopic dermatitis are persistent pruritus, xerosis, and skin lesions with a typical location and appearance that changes with the patient’s age. The prevalence of the disease in the pediatric population is estimated at 10% to 30%, while in adults it ranges from 1% to 3%. The number of people who suffer from AD is rising every year. The pathophysiology of the disease is complex and multifactorial. It involves elements of epidermal barrier dysfunction, alterations in cellular immune response, IgE hypersensitivity, and environmental factors. AD significantly reduces the quality of life of both patients and their families. Patients with AD are at higher risk for neuropsychiatric disorders such as depression, attention-deficit/hyperactivity disorder, and headaches. The decreased quality of life of AD patients and their families is associated with the discomfort of recurrent and chronic inflammatory skin lesions, persistent pruritus, and the inconvenience of long-term therapy. It also affects the psychological development of children, contributes to behavioral disorders (hyperactivity, hypersensitivity) and impacts many areas of family life such as sleep, leisure activities, and relationships between family members. The basic treatment of AD is avoidance of potential harmful factors, proper care in the treatment of exacerbations, topical corticosteroids, and calcineurin inhibitors in proactive therapy. In some patients who meet age criteria, phototherapy and cyclosporine should be considered. In individuals with severe AD who do not respond to topical treatment and who will not benefit from general therapy, dupilumab, a biologic drug, is the treatment of choice. Biologic treatment has an increasingly important place in the effective and modern therapy of AD. Currently, new biologic drugs are being researched, which may bring a therapeutic revolution in AD in the future. Allergen immunotherapy in patients with AD should be carefully evaluated on an individual basis, as proper selection of patients with documented IgE-dependent sensitization is important for the success of this therapy. Close collaboration with the patient and their caregivers, education, and psychological support as appropriate are integral to the treatment.

Allergen-Specific IgE and IgG4 as Biomarkers for Immunologic Changes during Subcutaneous Allergen Immunotherapy

(1) Background: Biomarkers of efficacy for subcutaneous immunotherapy (SCIT) on allergic rhinitis have not been evaluated in details. The present study aims to assess the relevance of measuring of sIgE, sIgG4 and IgE/IgG4 ratio during SCIT in patients with allergic rhinitis; (2) Methods: 20 patients, 13 men and 7 women aged 19 to 58 years, with clinically manifested seasonal and perennial allergic rhinitis were studied. At the initiation and in the end of the three-year course of SCIT serum allergen-specific IgE and IgG4 were measured with ImmunoCAP system. The sIgE/sIgG4 ratio was calculated as a biomarker for immunologic effectiveness; (3) Results: There was a significant increase of sIgG4 antibodies (p < 0.05), while at the end of SCIT for the sIgE levels no significant changes were seen (p > 0.05). Moreover, 90% of patients showed a decrease of the IgE/IgG4 ratio; (4) Conclusions: In most of treated patients with AR, SCIT with Bulgarian allergen products leads to clear immunological changes. After a 3-year of SCIT there is a significant increase in allergen specific IgG4 levels and both decrease of sIgE and IgE/IgG4 ratio. sIgE, sIgG4 and IgE/IgG4 ratio can be used as a substantial biomarker for predicting immunological effectiveness of SCIT.

Innovative robust basophil activation test using a novel gating strategy reliably diagnosing allergy with full automation

BACKGROUND

Allergy is one of the most common chronic diseases in Europe. Therefore, an increased need for specific and sensitive diagnostic tests that truly detect allergy exists. This study aimed at establishing a highly specific high-throughput and automated basophil activation test (BAT) that proves the existence of an allergy with utmost probability.

METHODS

BAT from 1104 samples was analyzed; a novel gating strategy with three antibodies (FcεRIα, CD203c, CD63) was established and compared with our published protocol (12 antibodies). Based on the novel gating strategy, storage conditions, automated measurement, and analyses using R (1376 samples out of 1389) were optimized to set up a high-throughput BAT.

RESULTS

No differences in sensitivity and specificity were found between the novel three antibody (FcεRIα, CD203c, CD63) and the 12 antibody gating strategy or between automated and manually analyzed samples (saving up to 90% of labor time). The time frame for basophil activation measurement after blood donation has been extended considerably (whole blood storage ≤7 days (RT) and 17 days (4°C) prior to BAT preparation and measurement). Respective storage conditions were optimized for samples after stimulation, staining, and preparation (≤7 days (RT) and 28 days (4°C)). These achievements were confirmed by a nationwide ring trial showing robustness and applicability of our BAT on a variety of flow cytometers.

CONCLUSION

Our considerable optimizations overcame the hurdles that until now prevented the BAT from being used as high-throughput allergy diagnostic test in routine laboratories and shall allow for collaborative studies between clinics and research centers.

Acupuncture, Shingles, and Allergen Immunotherapy

Background: The Varicella-zoster virus (VZV) remains dormant in the dorsal root ganglia and can become reactive later in a person's life. Factors such as stress, trauma, chronic disease, systemic illness, immune disorders, and age-related decline in host immunologic responses can potentially incite reactivation. Activation of VZV resulting in shingles following acupuncture has been reported in the literature previously, and some mechanisms have been proposed for this observation. Case: A patient with a history of total thyroidectomy for thyroid cancer presented with chronic neck pain. She was clinically and biochemically in a euthyroid state and on thyroid replacement therapy. She had a history of chickenpox, at age 13, and seasonal allergies. After her first acupuncture session, she received an allergy shot for her seasonal allergies. A day after the procedure, she developed a vesicular rash and was subsequently diagnosed with acute Herpes zoster. Subsequent acupuncture was withheld following this event. She received acyclovir and applied topical Aloe vera to the cutaneous lesions, and developed mild scarring, but did not experience postherpetic neuralgia. Conclusions: Acupuncture is a minor trauma that can predispose a patient to reactivation of VZV and shingles in the setting of immune activation with allergen immunotherapy.

Allergic Rhinitis: What Do We Know About Allergen-Specific Immunotherapy?

Allergic rhinitis (AR) is an IgE-mediated disease that is characterized by Th2 joint inflammation. Allergen-specific immunotherapy (AIT) is indicated for AR when symptoms remain uncontrolled despite medication and allergen avoidance. AIT is considered to have been effective if it alleviated allergic symptoms, decreased medication use, improved the quality of life even after treatment cessation, and prevented the progression of AR to asthma and the onset of new sensitization. AIT can be administered subcutaneously or sublingually, and novel routes are still being developed, such as intra-lymphatically and epicutaneously. AIT aims at inducing allergen tolerance through modification of innate and adaptive immunologic responses. The main mechanism of AIT is control of type 2 inflammatory cells through induction of various functional regulatory cells such as regulatory T cells (Tregs), follicular T cells (Tfr), B cells (Bregs), dendritic cells (DCregs), innate lymphoid cells (IL-10⁺ ILCs), and natural killer cells (NKregs). However, AIT has a number of disadvantages: the long treatment period required to achieve greater efficacy, high cost, systemic allergic reactions, and the absence of a biomarker for predicting treatment responders. Currently, adjunctive therapies, vaccine adjuvants, and novel vaccine technologies are being studied to overcome the problems associated with AIT. This review presents an updated overview of AIT, with a special focus on AR.

IFNG, FCER1A, PCDHB10 expression as a new potential marker of efficacy in grass pollen allergen-specific immunotherapy

Introduction

Allergen-specific immunotherapy (AIT) is the core treatment in allergic rhinitis and asthma. Although widely used, some patients do not benefit from treatment and there is no efficacy objective marker.

Aim

To define the profile of gene transcripts during the build-up phase of AIT and their comparison to the control group and then search for a viable efficacy marker in relation to patient symptoms.

Material and methods

AIT was administered in 22 patients allergic to grass pollen. Analysis of 15 selected transcript expression was performed in whole blood samples taken before AIT (sample A) and after reaching the maintenance dose (sample B). The control group included 25 healthy volunteers (sample C). The primary endpoint was Relative Quantification. The gene expression analysis was followed by clinical evaluation with the use of Allergy Control Score (ACS).

Results

Comparison between samples A and B of gene expression showed a significant increase in IFNG expression (p = 0.03). In relation to the control group, pretreatment samples from patients showed higher levels of AFAP1L1 (p = 0.006), COMMD8 (p = 0.001), PIK3CD (p = 0.027) and TWIST2 (p = 0.0003) in univariate analysis. A generalized linear regression model was built according to the Bayesian Information Criterion based on the IFNG, FCER1A and PCDHB10 expression pattern for prediction of the AIT outcome. The model showed a correlation in predicted and observed changes in ACS.

Conclusions

There is a significant change in the expression of IFNG during the build-up phase of AIT. The authors propose an in vitro model of AIT efficacy prediction for further validation.

REGN1908-1909 monoclonal antibodies block Fel d 1 in cat allergic subjects: Translational pharmacokinetics and pharmacodynamics

REGN1908‐1909, a 1:1 cocktail of two fully human IgG₄ monoclonal antibodies (mAbs), REGN1908 and REGN1909, is being evaluated for treatment of cat allergy. Both REGN1908 and REGN1909 bind to the dominant cat allergen, Fel d 1. Adults with cat allergy confirmed by skin prick test (SPT) were randomized to single subcutaneous administration of placebo (n = 6) or REGN1908‐1909 at doses of 150 (n = 6), 300 (n = 6), or 600 mg (n = 6). Blood samples were taken at prespecified time points for pharmacokinetic (PK) analysis and exploratory evaluation of biomarkers (IgE and SPT). Safety was assessed. Drug concentration‐time profiles in serum for ascending doses of REGN1908‐1909 were consistent with linear PKs. Noncompartmental analysis showed that maximum concentration (C_max) and exposure increased proportionately with dose, with similar time to maximum concentration (T_max) for REGN1908 and REGN1909 (6.2 to 8.2 days across doses), and a longer terminal half‐life for REGN1908 (~ 30 days) relative to REGN1909 (~ 21 days). Adverse events were not dose dependent; there were no dose‐limiting toxicities. REGN1908‐1909 is characterized by linear and dose‐proportional kinetics of the two individual mAb components. A single 600 mg dose maintains total mAb mean concentrations in serum above the target (mean of ~ 10 mg/L) for 8–12 weeks. Maintaining this mean target concentration resulted in translational pharmacodynamic effects: maximal mast cell degranulation in a passive cutaneous anaphylaxis mouse model, and maintenance of clinical efficacy measured by Total Nasal Symptom Score in a previous proof‐of‐mechanism study.

Targeting Mitochondrial-Derived Reactive Oxygen Species in T Cell-Mediated Autoimmune Diseases

Mitochondrial dysfunction resulting in oxidative stress could be associated with tissue and cell damage common in many T cell-mediated autoimmune diseases. Autoreactive CD4 T cell effector subsets (Th1,Th17) driving these diseases require increased glycolytic metabolism to upregulate key transcription factors (TF) like T-bet and RORγt that drive differentiation and proinflammatory responses. However, research in immunometabolism has demonstrated that mitochondrial-derived reactive oxygen species (ROS) act as signaling molecules contributing to T cell fate and function. Eliminating autoreactive T cells by targeting glycolysis or ROS production is a potential strategy to inhibit autoreactive T cell activation without compromising systemic immune function. Additionally, increasing self-tolerance by promoting functional immunosuppressive CD4 T regulatory (Treg) cells is another alternative therapeutic for autoimmune disease. Tregs require increased ROS and oxidative phosphorylation (OxPhos) for Foxp3 TF expression, differentiation, and anti-inflammatory IL-10 cytokine synthesis. Decreasing glycolytic activity or increasing glutathione and superoxide dismutase antioxidant activity can also be beneficial in inhibiting cytotoxic CD8 T cell effector responses. Current treatment options for T cell-mediated autoimmune diseases such as Type 1 diabetes (T1D), multiple sclerosis (MS), rheumatoid arthritis (RA), and systemic lupus erythematosus (SLE) include global immunosuppression, antibodies to deplete immune cells, and anti-cytokine therapy. While effective in diminishing autoreactive T cells, they can also compromise other immune responses resulting in increased susceptibility to other diseases and complications. The impact of mitochondrial-derived ROS and immunometabolism reprogramming in autoreactive T cell differentiation could be a potential target for T cell-mediated autoimmune diseases. Exploiting these pathways may delay autoimmune responses in T1D.

Intralymphatic immunotherapy for allergic rhinoconjunctivitis: a systematic review and meta-analysis

BACKGROUND

Intralymphatic immunotherapy (ILIT) is a new route of allergen-specific immunotherapy. Data confirming its effect is restricted to a small number of studies.

METHODOLOGY

A systematic review with meta-analysis was conducted. The short-term (less than 24 weeks), medium-term (24-52 weeks), and long-term (more than 52 weeks) effects of ILIT in patients with allergic rhinoconjunctivitis (ARC) were assessed. The outcomes were combined symptom and medication scores (CSMS), symptoms visual analog scale (VAS), disease-specific quality of life (QOL), specific IgG4 level, specific IgE level, and adverse events.

RESULTS

Eleven randomized controlled trials and 2 cohorts (483 participants) were included. Compared with placebo, short term benefits of ILIT for seasonal ARC improved CSMS, improved VAS and increased specific IgG4 level but did not change QOL or specific IgE level. Medium-term effect improved VAS. Data on the long-term benefit of ILIT remain unavailable and require longer term follow-up studies. There were no clinical benefits of ILIT for perennial ARC. ILIT was safe and well-tolerated.

CONCLUSION

ILIT showed short-term benefits for seasonal ARC. The sustained effects of ILIT were inconclusive. It was well tolerated.

Allergen Immunotherapy in Pediatric Respiratory Allergy

Purpose of Review

Atopic diseases such as asthma and allergic rhinitis are highly prevalent in children. Common triggers include tree and grass pollens, house dust mites, molds, and animal dander. These diseases are most often treated symptomatically; however, many patients show partial or poor response and require long-term medication use. Allergen immunotherapy (AIT) stands as the only treatment modality that can alter the underlying disease process and potentially offer a cure. In this review article, we discuss the merits of AIT with particular emphasis on its efficacy and safety in pediatric patients. We also discuss the challenges for AIT implementation and present an overview of current research that aims at improving its applicability for the treatment of allergic diseases.

Recent Findings

Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) are both safe and efficacious treatment options in children with allergic rhinitis and allergic asthma. Additionally, AIT has efficacy in preventing the development of asthma in children. Although there are clear advantages with AIT, there are challenges to overcome to optimize treatment. Solutions include improved diagnostics with pre-treatment biomarkers and molecular multiplex assays, biomarkers for prediction of response (e.g., basophil activation markers), improved allergen immunogenicity with the use of recombinant AIT, adjuvants, and allergoids, and lastly improved safety with the concurrent use of omalizumab.

Summary

AIT has shown safety and efficacy in major clinical trials for the treatment of allergic rhinitis and allergic asthma in children. AIT provides a curative treatment option for atopic disorders and should be considered in children with allergic rhinitis and allergic asthma. There are many continued advances being made in the field of allergy to further improve the safety and efficacy profile and shorten the duration of AIT treatment.

Advancement of antigen-specific immunotherapy: knowledge transfer between allergy and autoimmunity

Targeted restoration of immunological tolerance to self-antigens or innocuous environmental allergens represents the ultimate aim of treatment options in autoimmune and allergic disease. Antigen-specific immunotherapy (ASI) is the only intervention that has proven disease-modifying efficacy as evidenced by induction of long-term remission in a number of allergic conditions. Mounting evidence is now indicating that specific targeting of pathogenic T cells in autoinflammatory and autoimmune settings enables effective restoration of immune homeostasis between effector and regulatory cells and alters the immunological course of disease. Here, we discuss the key lessons learned during the development of antigen-specific immunotherapies and how these can be applied to inform future interventions. Armed with this knowledge and current high-throughput technology to track immune cell phenotype and function, it may no longer be a matter of ‘if’ but ‘when’ this ultimate aim of targeted tolerance restoration is realised.

It is no skin off my nose: The relationship between the skin and allergic rhinitis

OBJECTIVE

Evidence supports the relationship between the skin barrier and allergic conditions. This narrative review evaluates what role the cutaneous barrier may play in the pathogenesis, disease course, and management of allergic rhinitis (AR).

DATA SOURCES

A literature review of the MEDLINE (PubMed), Embase, Cochrane, and SCOPUS Sciverse databases was conducted to identify available evidence. Reference lists of pertinent papers were searched using a snowball technique.

STUDY SELECTIONS

Papers published in English from all years until December 2020 were included. Papers that did not address the relationship between AR and the skin and hypothesis papers were excluded.

RESULTS

The cutaneous barrier shares histologic characteristics with the sinonasal epithelial barrier, which may explain commonalities between AR and atopic dermatitis. A disruption in the epithelial barrier could be a common pathway in the development of multiple allergic conditions. The skin is a common target for the treatment of AR. Available data that look at the relationship between the skin and AR often include other topics such as other atopic disorders and the role of the epithelial barrier. Increased understanding of how the cutaneous barrier affects AR may lead to new innovations in its management.

CONCLUSION

The connection between the cutaneous barrier and AR holds possibilities for further investigation, and these may lead to a better understanding and future innovations for all atopic diseases.

Regulatory and IgE+ B Cells in Allergic Asthma

Allergic asthma is triggered by inhalation of environmental allergens resulting in bronchial constriction and inflammation, which leads to clinical symptoms such as wheezing, coughing, and difficulty breathing. Asthmatic airway inflammation is initiated by inflammatory mediators released by granulocytic cells. However, the immunoglobulin E (IgE) antibody is necessary for the initiation of the allergic cascade, and IgE is produced and released exclusively by memory B cells and plasma cells. Acute allergen exposure has also been shown to increase IgE levels in the airways of patients diagnosed with allergic asthma; however, more studies are needed to understand local airway inflammation. Additionally, regulatory B cells (B_regs) have been shown to modulate IgE-mediated inflammatory processes in allergic asthma pathogenesis, particularly in mouse models of allergic airway disease. However, the levels and function of these IgE⁺ B cells and B_regs remain to be elucidated in human models of asthma. The overall objective for this chapter is to provide detailed methodological, and insightful technological advances to study the biology of B cells in allergic asthma pathogenesis. Specifically, we will describe how to investigate the frequency and function of IgE⁺ B cells and B_regs in allergic asthma, and the kinetics of these cells after allergen exposure in a human asthma model.

DNA vaccines and recombinant allergens with reduced allergenic activity treat allergies

This review is intended to familiarize readers with major novel directions of developing allergy vaccines, their structure, as well as the mechanisms of forming a new immunological response in the course of the treating immunoglobulin E (IgE)-mediated allergic diseases. Currently, science offers a huge variety of new experimental forms of recombinant allergens with reduced allergenic activity and increased immunogenicity, or vice-versa, immune tolerance. Often, the mechanisms of their effect on the immune system are not fully understood. Scientific publications, including reviews covering this topic, allowed us identifying top priority areas in the development of allergy vaccines: recombinant hypoallergenic allergen derivatives, T cell epitope-based allergy vaccines, and B cell epitope-based allergy vaccines. In addition, the review discusses use of deoxyribonucleic acid (DNA) vaccines. Immunotherapy with DNA vaccines is the newest and least studied method of treating allergic diseases.

Passive Prophylactic Administration with a Single Dose of Anti-Fel d 1 Monoclonal Antibodies REGN1908-1909 in Cat Allergen-induced Allergic Rhinitis: A Randomized, Double-Blind, Placebo-controlled Clinical Trial

Rationale: Sensitization to Fel d 1 (Felis domesticus allergen 1) contributes to persistent allergic rhinitis and asthma. Existing treatment options for cat allergy, including allergen immunotherapy, are only moderately effective, and allergen immunotherapy has limited use because of safety concerns.

Objectives: To explore the relationship among the pharmacokinetic, clinical, and immunological effects of anti–Fel d 1 monoclonal antibodies (REGN1908–1909) in patients after treatment.

Methods: Patients received REGN1908–1909 (n = 36) or a placebo (n = 37) in a phase 1b study. Fel d 1–induced basophil and IgE-facilitated allergen binding responses were evaluated at baseline and Days 8, 29, and 85. Cytokine and chemokine concentrations in nasal fluids were measured, and REGN1908–1909 inhibition of allergen–IgE binding in patient serum was evaluated.

Measurements and Main Results: Peak serum drug concentrations were concordant with maximal observed clinical response. The anti–Fel d 1 IgE/cat dander IgE ratio in pretreatment serum correlated with Total Nasal Symptom Score improvement. The allergen-neutralizing capacity of REGN1908–1909 was observed in serum and nasal fluid and was detected in an inhibition assay. Type 2 cytokines (IL-4, IL-5, and IL-13) and chemokines (CCL17/TARC, CCL5/RANTES [regulated upon activation, normal T-cell expressed and secreted]) in nasal fluid were inhibited in REGN1908–1909–treated patients compared with placebo (P < 0.05 for all); IL-13 and IL-5 concentrations correlated with Total Nasal Symptom Score improvement. Ex vivo assays demonstrated that REGN1908 and REGN1909 combined were more potent than each alone for inhibiting FcεRI- and FcεRII (CD23)–mediated allergic responses and subsequent T-cell activation.

Conclusions: A single, passive-dose administration of Fel d 1–neutralizing IgG antibodies improved nasal symptoms in cat-allergic patients and was underscored by suppression of FcεRI-, FcεRII-, and T-helper cell type 2–mediated allergic responses.

Clinical trial registered with www.clinicaltrials.gov (NCT02127801)

Identification of biomarkers and pathogenesis in severe asthma by coexpression network analysis

BACKGROUND

Severe asthma is a heterogeneous inflammatory disease. The increase in precise immunotherapy for severe asthmatics requires a greater understanding of molecular mechanisms and biomarkers. In this study, we aimed to identify the underlying mechanisms and hub genes that determine asthma severity.

METHODS

Differentially expressed genes (DEGs) were identified based on bronchial epithelial brushings from mild and severe asthmatics. Then, weighted gene coexpression network analysis (WGCNA) was used to identify gene networks and the module most significantly associated with asthma severity. Furthermore, hub gene screening and functional enrichment analysis were performed. Replication with another dataset was conducted to validate the hub genes.

RESULTS

DEGs from 14 mild and 11 severe asthmatics were subjected to WGCNA. Six modules associated with asthma severity were identified. Three modules were positively correlated (P < 0.001) with asthma severity and contained genes that were upregulated in severe asthmatics. Functional enrichment analysis showed that genes in the most significant module were mainly enriched in neutrophil activation and degranulation, and cytokine receptor interaction. Hub genes included CXCR1, CXCR2, CCR1, CCR7, TLR2, FPR1, FCGR3B, FCGR2A, ITGAM, and PLEK; CXCR1, CXCR2, and TLR2 were significantly related to asthma severity in the validation dataset. The combination of ten hub genes exhibited a moderate ability to distinguish between severe and mild-moderate asthmatics.

CONCLUSION

Our results identified biomarkers and characterized potential pathogenesis of severe asthma, providing insight into treatment targets and prognostic markers.

Lower Functional and Proportional Characteristics of Cord Blood Treg of Male Newborns Compared with Female Newborns

Understanding the early events involved in the induction of immune tolerance to harmless environmental antigens and microbiota compounds could reveal potential targets for allergic disease therapy or prevention. Regulatory T cells (Treg), particularly induced Treg (iTreg), are crucial for the induction and maintenance of tolerance against environmental antigens including allergens. A decrease in the number and/or function of Treg or iTreg could represent an early predictor of allergy development. We analyzed proportional and functional properties of Treg in the cord blood of children of allergic mothers (neonates at high risk of allergy development) and healthy mothers (neonates with relatively low risk of allergy development). We observed a higher number of induced Treg in the cord blood of females compared to males, suggesting an impaired capacity of male immunity to set up tolerance to allergens, which could contribute to the higher incidence of allergy observed in male infants. The decreased proportion of iTreg in cord blood compared with maternal peripheral blood documents the general immaturity of the neonatal immune system. We observed a positive correlation in the demethylation of the Treg-specific demethylated region (TSDR) and the proportion of Treg in cord blood. Our data suggest that immaturity of the neonatal immune system is more severe in males, predisposing them to increased risk of allergy development.

Value of cord blood Treg population properties and function-associated characteristics for predicting allergy development in childhood

Allergic diseases represent some of the most common immunological disorders with high clinical and economic impact. Despite intensive research, there are still few universally accepted and reliable biomarkers capable of predicting their development at an early age. There is therefore a pressing need for identification of potential predictive factors and validation of their prognostic value by correlating them with allergy development. Dysbalance of the branches of immune response, most often excessive Th2 polarization, is the principal cause of allergic diseases. Regulatory T cells (Treg) are a crucial population for the timely establishment of physiological immune polarization and induction and maintenance of tolerance against environmental antigens. This makes them a potentially promising candidate for an early marker predicting allergy development. In our study, we analysed samples of cord blood of children of allergic mothers and children of healthy mothers by flow cytometry and retrospectively correlated the data with clinical allergy status of the children at the age of 6 to 10 years. Studied parameters included cord blood Treg population proportions and functional properties - intracellular presence of IL-10 and TGF-b, MFI of FoxP3. We observed higher percentage of Tregs in cord blood of children who did not develop allergy compared with allergic children. Further, we found higher numbers of IL-10+ Tregs in cord blood of healthy children of healthy mothers than in cord blood of children of allergic mothers and decreased TGF-b+ cord blood Tregs in the group of allergic children of allergic mothers compared to all other groups.

Clinical efficacy of sublingual allergen-specific immunotherapy in 22 cats with atopic dermatitis

BACKGROUND

Sublingual immunotherapy (SLIT) has been deployed in humans and dogs; to the best of the authors' knowledge, there are no published studies about the use of SLIT in cats.

OBJECTIVES

Evaluate the clinical efficacy of SLIT in atopic cats sensitized to dust and storage mites, assessing immunological changes associated with SLIT treatment.

ANIMALS

Twenty-two client-owned cats with clinical signs compatible with feline atopic dermatitis (fAD) and serum allergen-specific immunoglobulin (Ig)E against house dust and storage mites.

METHODS AND MATERIALS

Prospective, multicentre, open-label clinical trial. Individualized mite-specific SLIT was administered orally for 12 months. All cats underwent clinical examination to record SCORing feline allergic dermatitis (SCORFAD), pruritus Visual Analog Scale (pVAS) and serum allergen-specific IgE and IgG, every three months for 12 months.

RESULTS

Sixteen of 22 cats (73%) completed the study and three of six cats withdrawn from the study were included in an intention-to-treat analysis. SCORFAD and pVAS values decreased significantly from baseline (T0) to the third month of treatment (P = 0.0004 and P = 0.0013, respectively), with median total values ranging from 19 (6-44) (T0) to 2.5 (0-17) (T12) (P = 0.0001), and from 8 (6-10) (T0) to 2.3 (0-8) (T12) (P = 0.0001), respectively. Allergen-specific IgE values decreased significantly from the ninth month (T9) of treatment (P = 0.0032), with median scores decreasing from 56 (12-729) (T0) to 34 (0-158) (T12) (P = 0.0208). No significant differences in allergen-specific IgG values were observed throughout the study. No adverse effects related to the use of SLIT were reported.

CONCLUSIONS AND CLINICAL IMPORTANCE

Sublingual immunotherapy should be considered a rapid, effective, safe and well-tolerated treatment in cats with feline atopic dermatitis fAD.

Clinical Efficacy and Possible Mechanism of Endoscopic Vidian Neurectomy for House Dust Mite-Sensitive Allergic Rhinitis

BACKGROUND/AIMS

Endoscopic vidian neurectomy (EVN) for allergic rhinitis (AR) has good clinical effects. However, the pathophysiological basis of the effect of EVN on AR is still poorly understood. This study aimed to investigate the efficacy of EVN on house dust mite (HDM)-sensitive AR and the dynamic changes of serum immunoglobulin E and some immune regulatory factors.

METHODS

Twenty HDM-sensitive AR patients were treated with bilateral EVN (EVN group), 15 HDM-sensitive AR patients were treated with subcutaneous immunotherapy (SCIT group), and 15 healthy subjects served as healthy controls. Quality of daily life was assessed by the scores of the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQs). The visual analog scale was used to assess clinical efficacy. Serum molecules were measured by ELISA and the UNICAP system.

RESULTS

Compared with the SCIT group, the RQLQs in the EVN group were lower 12 months after treatment (both p < 0.05). There was no significant difference in improving nasal itching and sneezing (both p > 0.05), but the clinical efficacy of bilateral EVN was greater than SCIT in improving nasal obstruction, rhinorrhea, eye itching, and lachrymation 12 months after treatment (all p < 0.05). Compared with before treatment, the serum levels of total immunoglobulin E (tIgE), Dermatophagoides pteronyssinus- and Dermatophagoides farinae-specific immunoglobulin E (sIgE), and tumor necrosis factor (TNF)-α in the EVN group and the serum levels of TNF-α and interleukin-4 in the SCIT group were lower 12 months after treatment (all p < 0.05).

CONCLUSION

The short-term efficacy of bilateral EVN is more effective than SCIT in treating HDM-sensitive AR. This may be because the surgery reduced the tIgE and sIgE levels. TNF-α may be involved in the therapeutic mechanism.

Regulatory T cells mediated immunomodulation during asthma: a therapeutic standpoint

Asthma is an inflammatory disease of the lung airway network, which is initiated and perpetuated by allergen-specific CD4⁺ T cells, IgE antibodies, and a massive release of Th2 cytokines. The most common clinical manifestations of asthma progression include airway inflammation, pathological airway tissue and microvascular remodeling, which leads to airway hyperresponsiveness (AHR), and reversible airway obstruction. In addition to inflammatory cells, a tiny population of Regulatory T cells (Tregs) control immune homeostasis, suppress allergic responses, and participate in the resolution of inflammation-associated tissue injuries. Preclinical and clinical studies have demonstrated a tremendous therapeutic potential of Tregs in allergic airway disease, which plays a crucial role in immunosuppression, and rejuvenation of inflamed airways. These findings supported to harness the immunotherapeutic potential of Tregs to suppress airway inflammation and airway microvascular reestablishment during the progression of the asthma disease. This review addresses the therapeutic impact of Tregs and how Treg mediated immunomodulation plays a vital role in subduing the development of airway inflammation, and associated airway remodeling during the onset of disease.

New Therapeutic Horizons for Graves' Hyperthyroidism

Graves' hyperthyroidism is characterized by the presence of autoantibodies that stimulate the thyroid-stimulating hormone receptor (TSHR), resulting in uncontrolled secretion of excessive thyroid hormone. Conventional treatments, including antithyroid medication, radioiodine, or surgery have remained largely unchanged for the past 70 years and either lack efficacy for many patients, or result in lifelong thyroid hormone replacement therapy, in the case of the latter 2 options. The demand for new therapeutic options, combined with greater insight into basic immunobiology, has led to the emergence of novel approaches to treat Graves' hyperthyroidism. The current therapies under investigation include biologics, small molecules, and peptide immunomodulation. There is a growing focus on TSHR-specific treatment modalities, which carry the advantage of eliciting a specific, targeted approach, with the aim of avoiding disruption of the functioning immune system. These therapies present a new opportunity to supersede the inadequate treatments currently available for some Graves' patients, offering hope of successful restoration of euthyroidism without the need for ongoing therapy. Several of these therapeutic options have the potential to translate into clinical practice in the near future. This review provides a comprehensive summary of the recent advances and various stages of development of the novel therapeutic approaches to treat Graves' hyperthyroidism.

Precision Medicine in Hymenoptera Venom Allergy: Diagnostics, Biomarkers, and Therapy of Different Endotypes and Phenotypes

Allergic reactions to stings of Hymenoptera species may be severe and are potentially fatal deviations of the immunological response observed in healthy individuals. However, venom-specific immunotherapy (VIT) is an immunomodulatory approach able to cure venom allergy in the majority of affected patients. An appropriate therapeutic intervention and the efficacy of VIT not only depend on a conclusive diagnosis, but might also be influenced by the patient-specific manifestation of the disease. As with other diseases, it should be borne in mind that there are different endotypes and phenotypes of venom allergy, each of which require a patient-tailored disease management and treatment scheme. Reviewed here are different endotypes of sting reactions such as IgE-mediated allergy, asymptomatic sensitization or a simultaneous presence of venom allergy and mast cell disorders including particular considerations for diagnosis and therapy. Additionally, phenotypical manifestations of venom allergy, as e.g. differences in age of onset and disease severity, multiple sensitization or patients unsusceptible to therapy, are described. Moreover, biomarkers and diagnostic strategies that might reflect the immunological status of the patient and their value for therapeutic guidance are discussed. Taken together, the increasing knowledge of different disease manifestations in venom hypersensitivity and the growing availability of diagnostic tools open new options for the classification of venom allergy and, hence, for personalized medical approaches and precision medicine in Hymenoptera venom allergy.

Safety, Efficacy, and Preventive Role of Subcutaneous and Sublingual Allergen Immunotherapy for the Treatment of Pediatric Asthma

Allergen-specific immunotherapy is currently the only treatment with the potential to modify and prevent progression of allergic asthma in children. In clinical practice, it is available in two forms: subcutaneous immunotherapy and sublingual immunotherapy. Trials and meta-analyses showed both the safety and the short- and long-term benefits of allergen-specific immunotherapy in asthmatic children. However, its use and role in asthma remains controversial, since studies are largely heterogeneous. This is mainly due to the lack of consensus on the optimal primary outcome to be considered for clinical trials evaluating the efficacy of allergen-specific immunotherapy in asthma. Therefore, well-conducted researchis needed using standardized and validated tools to evaluate key outcomes in asthmatic children.

Combination blockade of OX40L and CD30L inhibits allergen-driven memory TH2 cell reactivity and lung inflammation

BACKGROUND

The selective reduction of memory T_H2 cell responses could be key to affording tolerance and protection from the recurrence of damaging allergic pathology.

OBJECTIVE

We asked whether TNF family costimulatory molecules cooperated to promote accumulation and reactivity of effector memory CD4 T cells to inhaled complex allergen, and whether their neutralization could promote airway tolerance to subsequent reexposure to allergen.

METHODS

Mice were sensitized intraperitoneally or intranasally with house dust mite and challenged with intranasal allergen after memory had developed. We assessed whether single or combined blockade of OX40L/CD252 and CD30L/CD153 inhibited memory T cells from driving acute asthmatic lung inflammation and protected mice following exposure to allergen at a later time.

RESULTS

OX40- or CD30-deficient animals showed strong or partial protection against allergic airway inflammation; however, neutralizing either molecule alone during the secondary response to allergen had little effect on the frequency of effector memory CD4 T cells formed and acute lung inflammation. In contrast, a significant reduction in eosinophilic inflammation was observed when OX40L and CD30L were simultaneously neutralized, with dual blockade inhibiting effector memory T_H2 cell expansion in the lungs, whereas formation of peripherally induced regulatory T cells remained intact. Moreover, dual blockade during the secondary response resulted in a tolerogenic state such that mice did not develop a normal tertiary memory T_H2 cell and lung inflammatory response when challenged weeks later with allergen.

CONCLUSION

Memory T-cell responses to complex allergens are controlled by several TNF costimulatory interactions, and their combination targeting might represent a strategy to reduce the severity of inflammatory reactions following reexposure to allergen.

Immunological Outcomes of Allergen-Specific Immunotherapy in Food Allergy

IgE-mediated food allergies are caused by adverse immunologic responses to food proteins. Allergic reactions may present locally in different tissues such as skin, gastrointestinal and respiratory tract and may result is systemic life-threatening reactions. During the last decades, the prevalence of food allergies has significantly increased throughout the world, and considerable efforts have been made to develop curative therapies. Food allergen immunotherapy is a promising therapeutic approach for food allergies that is based on the administration of increasing doses of culprit food extracts, or purified, and sometime modified food allergens. Different routes of administration for food allergen immunotherapy including oral, sublingual, epicutaneous and subcutaneous regimens are being evaluated. Although a wealth of data from clinical food allergen immunotherapy trials has been obtained, a lack of consistency in assessed clinical and immunological outcome measures presents a major hurdle for evaluating these new treatments. Coordinated efforts are needed to establish standardized outcome measures to be applied in food allergy immunotherapy studies, allowing for better harmonization of data and setting the standards for the future research. Several immunological parameters have been measured in food allergen immunotherapy, including allergen-specific immunoglobulin levels, basophil activation, cytokines, and other soluble biomarkers, T cell and B cell responses and skin prick tests. In this review we discuss different immunological parameters and assess their applicability as potential outcome measures for food allergen immunotherapy that may be included in such a standardized set of outcome measures.

Dust mite-derived Enterobacterial fimbriae H protein enforces the allergen specific immunotherapy in asthma mice

BACKGROUND

The mite alimentary canal contains plenty of microbiota. It is accepted that some of the microbial products function as adjuvants to speed up immune responses.

OBJECTIVES

We identified five bacterial proteins from dust mite, and Enterobacterial fimbriae H (FimH) was one of them. This study aims to test a hypothesis that the FimH protein enforces immunotherapy in asthmatic mice.

METHODS

Asthmatic mice were treated by allergen specific immunotherapy (ASIT) with rDer f1/f2 or rDer f1/f2 plus FimH. Changes in inflammatory cell infiltration, airway hyperreactivity, frequency of Tregs, splenic CD4⁺IFN-γ⁺ cells, and serum levels of TGF-β, IL-10, IL-13 and IL-17A of asthmatic mice were checked.

RESULTS

ASIT with rDer f1/f2 plus FimH reduced inflammatory cell infiltration, airway hyperreactivity (AHR), and levels of IgE and IgG1 compared to ASIT with rDer f1/f2 alone, but the levels of IgG2a increased. Asthmatic mice that underwent ASIT with rDer f1/f2 plus FimH showed increased frequency of Tregs, splenic CD4⁺IFN-γ⁺ cells, serum levels of TGF-β and IL-10; and deceased splenic CD4⁺IL-4⁺ cells, and serum levels of IL-13 and IL-17A. In vitro study showed FimH triggered IL-10 expression in a concentration dependent manner and facilitated the differentiation of Tregs.

CONCLUSION

Used as an adjuvant, FimH enforces the effect of ASIT in asthmatic mice via augmenting Tregs.

Trained immunity and tolerance in innate lymphoid cells, monocytes, and dendritic cells during allergen-specific immunotherapy

BACKGROUND

Despite the efficacy of allergen-specific immunotherapy (AIT), the role of trained immunity and tolerance in this process has not been elucidated.

OBJECTIVE

Here, we have performed a comprehensive longitudinal analysis of the systemic innate immune cell repertoire during the course of AIT.

METHODS

Patients with allergy received standard preseasonal subcutaneous AIT with allergoids to birch and/or grass. Healthy controls were monitored without any intervention. Flow cytometry of innate lymphoid cell (ILC), natural killer cell, monocyte cell, and dendritic cell (DC) subsets was performed at baseline, 3 months (birch season), 6 months (grass seasons), and 12 months after the therapy in patients or at similar seasonal time points in controls. Additional analyses were performed in the third-year birch and grass season.

RESULTS

We observed a durable decrease in group 2 ILCs and an increase of group 1 ILCs after AIT, with dynamic changes in their composition. We found that an expansion of CD127⁺CD25⁺⁺ clusters caused observed shifts in the heterogeneity of group 1 ILCs. In addition, we observed development of CD127⁺CD25⁺⁺c-Kit⁺ group 3 ILC clusters. Moreover, we found an increase in the number of intermediate monocytes in parallel with a reduction in nonclassical monocytes during the first year after AIT. Classical and intermediate monocytes presented significant heterogeneity in patients with allergy, but AIT reduced the HLA-DR⁺⁺ clusters. Finally, an increase in plasmacytoid DCs and CD141⁺ myeloid DCs was observed in individuals with allergy, whereas the number of CD1c⁺ myeloid DCs was reduced during the first year of AIT.

CONCLUSION

AIT induces changes in the composition and heterogeneity of circulating innate immune cells and brings them to the level observed in healthy individuals. Monitoring of ILCs, monocytes, and DCs during AIT might serve as a novel biomarker strategy.

Tolerance mechanisms in allergen immunotherapy

PURPOSE OF REVIEW

Allergen immunotherapy is the only treatment modality which alters the natural course of allergic diseases by restoring immune tolerance against allergens. Deeper understanding of tolerance mechanisms will lead to the development of new vaccines, which target immune responses and promote tolerance.

RECENT FINDINGS

Successful allergen immunotherapy (AIT) induces allergen-specific peripheral tolerance, characterized mainly by the generation of allergen-specific Treg cells and reduction of Th2 cells. At the early phase, AIT leads to a decrease in the activity and degranulation of mast cells and basophils and a decrease in inflammatory responses of eosinophils in inflamed tissues. Treg cells show their effects by secreting inhibitory cytokines including interleukin (IL)-10, transforming growth factor-β, interfering with cellular metabolisms, suppressing antigen presenting cells and innate lymphoid cells (ILCs) and by cytolysis. AIT induces the development of regulatory B cells producing IL-10 and B cells expressing allergen-specific IgG4. Recent investigations have demonstrated that AIT is also associated with the formation of ILC2reg and DCreg cells which contribute to tolerance induction.

SUMMARY

Research done so far, has shown that multiple molecular and cellular factors are dysregulated in allergic diseases and modified by AIT. Studies should now focus on finding the best target and ideal biomarkers to identify ideal candidates for AIT.

Allergen immunotherapy in children and adolescents with respiratory diseases

To date, the only disease-modifying treatment strategy for allergic rhinitis and asthma is allergen immunotherapy (AIT). There is evidence that AIT improves allergic rhinitis and asthma, such as reducing symptom severity and medication use and improving of quality of life, with a long-lasting effect after the end of the course. The recent clinical trials evidenced AIT effectiveness and safety in allergic asthma. Consequently, the current version of the GINA (Global Initiative for Asthma) guidelines recommend AIT as an add-on therapy for asthma. There is also evidence that AIT may exert preventive activity on the possible progression from allergic rhinitis to asthma in children and the onset of new sensitizations.

In vivo Induction of Functional Inhibitory IgG Antibodies by a Hypoallergenic Bet v 1 Variant

Allergic sensitization to the major allergen Bet v 1 represents the dominating factor inducing a vast variety of allergic symptoms in birch pollen allergic patients worldwide, including the pollen food allergy syndrome. In order to overcome the huge socio-economic burden associated with allergic diseases, allergen-specific immunotherapy (AIT) as a curative strategy to manage the disease was introduced. Still, many hurdles related to this treatment exist making AIT not the patients’ first choice. To improve the current situation, the development of hypoallergen-based drug products has raised attention in the last decade. Herein, we investigated the efficacy of the novel AIT candidate BM4, a hypoallergenic variant of Bet v 1, to induce treatment-relevant cross-reactive Bet v 1-specific IgG antibodies in two different mammals, Wistar rats and New Zealand White rabbits. We further analyzed the cross-reactivity of BM4-induced Wistar rat antibodies with the birch pollen-associated food allergens Mal d 1 and Cor a 1, and the functional capability of the induced antibodies to act as IgE-blocking IgG antibodies. Enzyme-linked immunosorbent assay (ELISA) was used to determine the titers of rat IgG1, IgG2a, IgG2b, and IgE, as well as rabbit IgG and IgE antibodies. To address the functional relevance of the induced IgG antibodies, the capacity of rat sera to suppress binding of human IgE to Bet v 1 was investigated by using an inhibition ELISA and an IgE-facilitated allergen-binding inhibition assay. We found that the treatment with BM4 induced elevated Bet v 1-specific IgG antibody titers in both mammalian species. In Wistar rats, high BM4-specific IgG1, IgG2a, and IgG2b titers (10⁴ to 10⁶) were induced, which cross-reacted with wild-type Bet v 1, and the homologous allergens Mal d 1 and Cor a 1. Rat allergen-specific IgG antibodies sustained upon treatment discontinuation. Sera of rats immunized with BM4 were able to significantly suppress binding of human IgE to the wild-type allergens and CD23-mediated human IgE-facilitated Bet v 1 binding on B cells. By contrast, treatment-induced IgE antibody levels were low or undetectable. In summary, BM4 induced a robust IgG immune response that efficiently blocked human IgE-binding to wild-type allergens, underscoring its potential therapeutic value in AIT.

Filling the Antibody Pipeline in Allergy: PIPE Cloning of IgE, IgG1 and IgG4 against the Major Birch Pollen Allergen Bet v 1

Birch pollen allergy is among the most prevalent pollen allergies in Northern and Central Europe. This IgE-mediated disease can be treated with allergen immunotherapy (AIT), which typically gives rise to IgG antibodies inducing tolerance. Although the main mechanisms of allergen immunotherapy (AIT) are known, questions regarding possible Fc-mediated effects of IgG antibodies remain unanswered. This can mainly be attributed to the unavailability of appropriate tools, i.e., well-characterised recombinant antibodies (rAbs). We hereby aimed at providing human rAbs of several classes for mechanistic studies and as possible candidates for passive immunotherapy. We engineered IgE, IgG1, and IgG4 sharing the same variable region against the major birch pollen allergen Bet v 1 using Polymerase Incomplete Primer Extension (PIPE) cloning. We tested IgE functionality and IgG blocking capabilities using appropriate model cell lines. In vitro studies showed IgE engagement with FcεRI and CD23 and Bet v 1-dependent degranulation. Overall, we hereby present fully functional, human IgE, IgG1, and IgG4 sharing the same variable region against Bet v 1 and showcase possible applications in first mechanistic studies. Furthermore, our IgG antibodies might be useful candidates for passive immunotherapy of birch pollen allergy.

Presence of positive skin prick tests to inhalant allergens and markers of T2 inflammation in subjects with chronic spontaneous urticaria (CSU): a systematic literature review

BACKGROUND

Current guidelines do not recommend performing aeroallergen skin prick testing (SPT) in chronic spontaneous urticaria (CSU).

OBJECTIVE

The objective of this review was to investigate the presence of aeroallergen sensitization and markers of T2 inflammation in subjects with CSU.

METHODS

Systematic literature reviews to identify all studies that evaluated the presence of T2 markers of allergic inflammation in CSU subjects were performed.

RESULTS

In 16 studies that assessed the prevalence of positive SPT to multiple aeroallergens in CSU, 38.5% of CSU subjects had positive SPT. In three controlled studies, 34.2% of CSU subjects had positive SPT to multiple aeroallergens, compared to 13.6% of controls (p = 0.047). In 18 studies that assessed the prevalence of house dust mite (HDM) positive SPT in CSU, 27.5% of CSU subjects had positive SPT. In three controlled studies, 27.5% of CSU subjects had positive SPT to HDM, compared to 2.1% of controls (p = 0.047). Overall, CSU subjects were 3.1 times more likely to be aeroallergen-sensitized (95% CI 1.7-5.8, p = 0.0002) and 6.1 times more likely to be HDM-sensitized (95% CI 3.7-9.9, p < 0.00001) than controls. Mean total serum IgE (tIgE) levels were 238 kU/L and median tIgE levels were 164 kU/L, which was greater than the upper 90th percentile of normal (< 137 kU/L). Compared to healthy controls, CSU subjects were 6.5 times more likely to have IgG autoantibody against FcεR1α (p = 0.001), 2.4 times more likely to have IgG anti-IgE antibody (p = 0.03) and 5 times more likely to have anti-thyroid peroxidase (anti-TPO) antibody (p = 0.02). When corticosteroids were withheld for ≥ 28 days, mean blood eosinophil percentage was elevated at 5.9% (normal < 4%), but other studies reporting absolute count found the mean was in the normal range, 239 × 10 6 / L (normal < 400 × 10 6 / L).

CONCLUSION

Increased aeroallergen sensitization, tIgE, autoantibodies and blood eosinophil percentage in the CSU subjects indicates the possible importance of T2 inflammation in the pathogenesis of CSU. Further studies may be warranted to determine if specific allergen avoidance, desensitization or improvement in the mucosal allergic inflammation present in asthma and/or rhinitis has any benefit in the management of CSU.

B-cell responses in allergen immunotherapy

PURPOSE OF REVIEW

The establishment of long-term clinical tolerance in AIT requires the involvement of basophils, mast cells, allergen-specific regulatory T and B cells, downregulation of effector type 2 responses, and increase in production of specific IgG, particularly immunglobulin G4 (IgG4) antibodies. This review aims to provide an overview of the role of B cells in AIT, their mechanism of action, and their potential for improving AIT.

RECENT FINDINGS

In-depth research of B cells has paved the way for improved diagnosis and research on allergic diseases. B cells play a central role in allergy and allergen tolerance through the production of immunglobulin E (IgE)-blocking antibodies. However, an increasing body of evidence has emerged supporting a role for B cells in regulating immune responses that extends beyond the production of antibodies. Regulatory B cells play an important role in immunosuppression, mediated by secretion of anti-inflammatory cytokines.

SUMMARY

Successful AIT establishes the reinstatement of immune tolerance toward allergens, reduces allergic symptoms, and improves clinical treatments in patients. B cells play a central role in this process through antibody-independent immune regulatory processes in addition to the production of IgE-blocking antibodies.

COVID-19 and Asthma: Reflection During the Pandemic

Coronavirus disease 2019 (COVID-19) is a global pandemic infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and abnormal, overactivated innate immunity and "cytokine storms" have been proposed as potential pathological mechanisms for rapid COVID-19 progression. Theoretically, asthmatic patients should have increased susceptibility and severity for SARS-CoV-2 infection due to a deficient antiviral immune response and the tendency for exacerbation elicited by common respiratory viruses. However, existing studies have not shown an expected prevalence of asthmatic individuals among COVID-19 patients. Certain aspects of type 2 immune response, including type 2 cytokines (IL-4, IL-13, etc.) and accumulation of eosinophils, might provide potential protective effects against COVID-19. Furthermore, conventional therapeutics for asthma, including inhaled corticosteroids, allergen immunotherapy (AIT), and anti-IgE monoclonal antibody, might also reduce the risks of asthmatics suffering infection of the virus through alleviating inflammation or enhancing antiviral defense. The interactions between COVID-19 and asthma deserve further attention and clarification.

AllergoOncology: ultra-low IgE, a potential novel biomarker in cancer-a Position Paper of the European Academy of Allergy and Clinical Immunology (EAACI)

Elevated serum IgE levels are associated with allergic disorders, parasitosis and specific immunologic abnormalities. In addition, epidemiological and mechanistic evidence indicates an association between IgE-mediated immune surveillance and protection from tumour growth. Intriguingly, recent studies reveal a correlation between IgE deficiency and increased malignancy risk. This is the first review discussing IgE levels and links to pathological conditions, with special focus on the potential clinical significance of ultra-low serum IgE levels and risk of malignancy. In this Position Paper we discuss: (a) the utility of measuring total IgE levels in the management of allergies, parasitosis, and immunodeficiencies, (b) factors that may influence serum IgE levels, (c) IgE as a marker of different disorders, and d) the relationship between ultra-low IgE levels and malignancy susceptibility. While elevated serum IgE is generally associated with allergic/atopic conditions, very low or absent IgE may hamper anti-tumour surveillance, indicating the importance of a balanced IgE-mediated immune function. Ultra-low IgE may prove to be an unexpected biomarker for cancer risk. Nevertheless, given the early stage of investigations conducted mostly in patients with diseases that influence IgE levels, in-depth mechanistic studies and stratification of malignancy risk based on associated demographic, immunological and clinical co-factors are warranted.

The Role of IgG4 in the Fine Tuning of Tolerance in IgE-Mediated Allergy and Cancer

Among the four immunoglobulin G (IgG) subclasses, IgG4 is the least represented in serum of a healthy human and it is considered an “odd” antibody. The IgG4 antibody has unique structural features that affect its biological function. These include the ability to undergo antigen-binding fragment (Fab)-arm exchange, to create fragment crystallizable (Fc) – Fc binding with other IgG4 and other IgG subclass antibodies, have a unique affinity profile for Fc gamma receptors (FcγRs) and no binding to complement component C1q. Altogether, these characteristics support anti-inflammatory roles of IgG4 leading to immune tolerance. Under conditions of chronic antigenic stimulation and Th2-type inflammation, both tissue and serum IgG4 levels are increased. This review seeks to highlight how in allergen immunotherapy IgG4 can confer a protective role as a “blocking” antibody and safeguard from subsequent allergen exposure, while IgG4 can confer immunomodulatory functions to support malignancy. While Th2 conditions drive polarization of macrophages to the M2a subtype, chronic antigen stimulation drives B cell class switching to IgG4 to further support phenotypical macrophage changes towards an M2b-like state. M2b-like macrophages can secrete chemokine (C-C motif) ligand 1 (CCL1) and interleukin-10 (IL-10) to support regulatory cell recruitment and to further shape a tolerogenic microenvironment. Thereby, IgG4 have a Janus-faced role, favorable in allergy but detrimental in cancer.

Efficacy of transdermal immunotherapy with biodegradable microneedle patches in a murine asthma model

BACKGROUND

House dust mite (HDM) is a well-known cause of asthma. Allergen-specific immunotherapy (AIT) can only modify the natural course of the disease. Conventional routes of HDM AIT are subcutaneous or sublingual. Subcutaneous immunotherapy (SCIT) has a disadvantage of systemic hypersensitive reaction, and the sublingual immunotherapy has a disadvantage of local allergic reaction and low drug adherence.

OBJECTIVE

To overcome the weak points of conventional AIT, we developed a HDM loaded biodegradable microneedle patch (MNP) for transdermal immunotherapy (TDIT). We aim to demonstrate the efficacy of TDIT in murine asthma model triggered by HDM compared with conventional SCIT.

METHODS

To make HDM asthma mouse model, 5-week-old BALB/c female mice were sensitized and challenged by intranasal administration of HDM. The mice were divided into 5 groups: sham, asthma, low (10 µg) and high dose (100 µg) SCIT, and TDIT (10 µg). To make HDM loaded MNP, droplet-born air blowing method was used. Airway hyperresponsiveness and allergic inflammation markers were analysed by bronchoalveolar lavage fluid, immunohistochemistry, serum immunoglobulin (Ig) analysis, and lung cytokine assays.

RESULTS

Airway hyperresponsiveness was ameliorated by TDIT. Eosinophilic inflammation in bronchoalveolar lavage was improved without adverse reactions. Reduction of Th2 (IL-4, IL-5, and IL-13) cytokines, and HDM-specific IgE, induction of Treg (IL-10, TGF-β), Th1 (IFN-γ) cytokines were observed. Eosinophilic infiltration, goblet cell hyperplasia, and subepithelial fibrosis were also alleviated by TDIT. These changes were more significant in the TDIT group than in subcutaneous AIT group.

CONCLUSION

In conclusion, HDM loaded biodegradable TDIT is a novel treatment option to treat asthma which showed more effectiveness and may have better safety profiles than conventional SCIT.

New and old adjuvants in allergen-specific immunotherapy: With a focus on nanoparticles

Allergic diseases have remarkably increased in recent years. Nowadays, efforts for curing and management of these disorders are an important concern worldwide. Allergen-specific immunotherapy (ASIT) has recently gained more attention as a means for the management of allergic diseases. Adjuvants or helper agents are materials applied for better stimulating and shifting of protective responses, and these belong to an extremely diverse collection of complexes. The main function of adjuvants includes acting as depot foundations, transferring vehicles, and immunostimulators. Immunostimulatory adjuvants have gained increasing attention for ASIT. In this regard, the present study provides a review of old and new adjuvants used in allergen immunotherapy.

Interleukin 10: the critical role of a pleiotropic cytokine in food allergy

Despite advances in research, the pathophysiology of food allergy has not yet been fully elucidated. IL-10 has both a pro- and anti-inflammatory effect on the development of food allergy and in order to understand its different immune-modulatory effects the factors that influence the inflammatory microenvironment need to be taken into account. Specific single nucleotide polymorphisms of the IL-10 gene seem to confer an increased risk of developing food allergy, but to date there is a substantial lack of genome- wide association studies regarding the genetic and epigenetic underpinnings of the disease. Special interest has been drawn to the development of allergen-specific regulatory CD4+CD25+ T-cells secreting IL-10 in the immunotherapy of allergic diseases. In addition, a distinct population of human tolerogenic dendritic cells (DC), DC-10 seems to hold great potential and could potentially serve as a therapeutic tool to improve the management of food allergy.

Functional Profile of Antigen Specific CD4+ T Cells in the Immune Response to Phospholipase A1 Allergen from Polybia paulista Venom

Insect venom can cause systemic allergic reactions, including anaphylaxis. Improvements in diagnosis and venom immunotherapy (VIT) are based on a better understanding of an immunological response triggered by venom allergens. Previously, we demonstrated that the recombinant phospholipase A1 (rPoly p 1) from Polybia paulista wasp venom induces specific IgE and IgG antibodies in sensitized mice, which recognized the native allergen. Here, we addressed the T cell immune response of rPoly p 1-sensitized BALB/c mice. Cultures of splenocytes were stimulated with Polybia paulista venom extract and the proliferation of CD8⁺ and CD4⁺ T cells and the frequency of T regulatory cells (Tregs) populations were assessed by flow cytometry. Cytokines were quantified in cell culture supernatants in ELISA assays. The in vitro stimulation of T cells from sensitized mice induces a significant proliferation of CD4⁺ T cells, but not of CD8⁺ T cells. The cytokine pattern showed a high concentration of IFN-γ and IL-6, and no significant differences to IL-4, IL-1β and TGF-β1 production. In addition, the rPoly p 1 group showed a pronounced expansion of CD4⁺CD25⁺FoxP3⁺ and CD4⁺CD25^-FoxP3⁺ Tregs. rPoly p 1 sensitization induces a Th1/Treg profile in CD4⁺ T cell subset, suggesting its potential use in wasp venom immunotherapy.

Allergen Immunotherapy in Pediatric Asthma: A Pragmatic Point of View

To date, the only disease-modifying treatment strategy for allergic rhinitis and asthma is allergen immunotherapy (AIT). There is evidence that AIT improves allergic rhinitis and asthma, such as reducing symptom severity and medication use and improving of quality of life, with a long-lasting effect after the end of the course. The recent clinical trials evidenced AIT effectiveness and safety in allergic asthma. Consequently, the current version of the GINA (Global Initiative for Asthma) guidelines recommend AIT as an add-on therapy for asthma. There is also evidence that AIT may exert preventive activity on the possible progression from allergic rhinitis to asthma in children and the onset of new sensitizations. The present review provides a pragmatic summary of the clinical indications of AIT in pediatric asthma, including the immunological mechanisms, the predictive biomarkers, and the safety issues in clinical practice.