Targeting membrane-expressed IgE B cell receptor with an antibody to the M1 prime epitope reduces IgE production

Reduction of circulating IgE and allergens by a pH-sensitive antibody with enhanced FcγRIIb binding

Allergen-crosslinked IgE triggers allergy by interacting with its receptor on basophils and mast cells. The anti-IgE monoclonal antibody omalizumab can alleviate allergy by competing with the receptor for IgE binding. However, along with neutralization, omalizumab also inhibits IgE degradation, which is clinically associated with high-dose and total IgE accumulation problems. In this study, we have developed an IgE-eliminating antibody on the basis of omalizumab, which has pH-dependent Fabs and an Fc with high affinity for FcγRIIb. In mice, the antibody rapidly eliminated total serum IgE to baseline levels and caused lower free IgE levels than omalizumab. At low dosages, the antibody also exhibited favorable IgE elimination effects. In addition, the antibody can degrade the corresponding allergen with the removal of IgE, addressing the allergy from its source. Introduction of the M252Y/S254T/T256E (YTE) mutation into this antibody prolongs its serum half-life without reducing potency. Thus, this engineered antibody holds a promising therapeutic option for allergy patients. Mechanistic insights are also included in this study.

IgE plasma cells are transcriptionally and functionally distinct from other isotypes

Understanding the phenotypic and transcriptional signature of immunoglobulin E (IgE)-producing cells is fundamental to plasma cell (PC) biology and development of therapeutic interventions for allergy. Here, using a mouse model of intranasal house dust mite (HDM) exposure, we showed that short-lived IgE PCs emerge in lung draining lymph nodes (dLNs) during early exposure (<3 weeks) and long-lived IgE PCs accumulate in the bone marrow (BM) with prolonged exposure (>7 weeks). IgE PCs had distinct surface and gene expression profiles in these different tissues compared with other Ig isotypes. IgE BMPCs up-regulated genes associated with prosurvival and BM homing, whereas IgE dLN PCs expressed genes associated with recent class switching and differentiation. IgE PCs also exhibited higher expression of endoplasmic reticulum (ER) stress and protein coding genes and higher antibody secretion rate when compared with IgG1. Overall, this study highlights the unique developmental path and transcriptional signature of short-lived and long-lived IgE PCs.

Therapeutic monoclonal antibodies in allergy: Targeting IgE, cytokine, and alarmin pathways

The etiology of allergy is closely linked to type 2 inflammatory responses ultimately leading to the production of allergen-specific immunoglobulin E (IgE), a key driver of many allergic conditions. At a high level, initial allergen exposure disrupts epithelial integrity, triggering local inflammation via alarmins including IL-25, IL-33, and TSLP, which activate type 2 innate lymphoid cells as well as other immune cells to secrete type 2 cytokines IL-4, IL-5 and IL-13, promoting Th2 cell development and eosinophil recruitment. Th2 cell dependent B cell activation promotes the production of allergen-specific IgE, which stably binds to basophils and mast cells. Rapid degranulation of these cells upon allergen re-exposure leads to allergic symptoms. Recent advances in our understanding of the molecular and cellular mechanisms underlying allergic pathophysiology have significantly shaped the development of therapeutic intervention strategies. In this review, we highlight key therapeutic targets within the allergic cascade with a particular focus on past, current and future treatment approaches using monoclonal antibodies. Specific targeting of alarmins, type 2 cytokines and IgE has shown varying degrees of clinical benefit in different allergic indications including asthma, chronic spontaneous urticaria, atopic dermatitis, chronic rhinosinusitis with nasal polyps, food allergies and eosinophilic esophagitis. While multiple therapeutic antibodies have been approved for clinical use, scientists are still working on ways to improve on current treatment approaches. Here, we provide context to understand therapeutic targeting strategies and their limitations, discussing both knowledge gaps and promising future directions to enhancing clinical efficacy in allergic disease management.

A therapeutic strategy to target distinct sources of IgE and durably reverse allergy

Immunoglobulin E (IgE) is a key driver of type 1 hypersensitivity reactions and allergic disorders, which are globally increasing in number and severity. Although eliminating pathogenic IgE may be a powerful way to treat allergy, no therapeutic strategy reported to date can fully ablate IgE production. Interleukin-4 receptor α (IL-4Rα) signaling is required for IgE class switching, and IL-4Rα blockade gradually reduces, but does not eliminate, IgE. The persistence of IgE after IL-4Rα blockade may be due to long-lived IgE+ plasma cells that maintain serological memory to allergens and thus may be susceptible to plasma cell-targeted therapeutics. We demonstrate that transient administration of a B cell maturation antigen x CD3 (BCMAxCD3) bispecific antibody markedly depletes IgE, as well as other immunoglobulins, by ablating long-lived plasma cells, although IgE and other immunoglobulins rapidly rebound after treatment. Concomitant IL-4Rα blockade specifically and durably prevents the reemergence of IgE by blocking IgE class switching while allowing the restoration of other immunoglobulins. Moreover, this combination treatment prevented anaphylaxis in mice. Together with additional cynomolgus monkey and human data, our studies demonstrate that allergic memory is primarily maintained by both non-IgE+ memory B cells that require class switching and long-lived IgE+ plasma cells. Our combination approach to durably eliminate pathogenic IgE has potential to benefit allergy in humans while preserving antibody-mediated immunity.

Promising treatment biomarkers in asthma

Asthma is a highly heterogenous disease which researchers over time have attempted to classify into different phenotypes and endotypes to improve diagnosis, prognosis and treatment. Earlier classifications based on reaction to environmental allergens, age, sex and lung function have evolved, and today, the use of precision medicine guided by biomarkers offers new perspectives on asthma management. Identifying biomarkers that may reveal the underlying pathophysiology of the disease will help to select the patients who will benefit most from specific treatments. This review explores the classification of asthma phenotypes and focuses on the most recent advances in using biomarkers to guide treatment.

Evaluation of the reproducibility of responses to nasal allergen challenge and effects of inhaled nasal corticosteroids

BACKGROUND

Similar immune responses in the nasal and bronchial mucosa implies that nasal allergen challenge (NAC) is a suitable early phase experimental model for drug development targeting allergic rhinitis (AR) and asthma. We assessed NAC reproducibility and the effects of intranasal corticosteroids (INCS) on symptoms, physiology, and inflammatory mediators.

METHODS

20 participants with mild atopic asthma and AR underwent three single blinded nasal challenges each separated by three weeks (NCT03431961). Cohort A (n = 10) underwent a control saline challenge, followed by two allergen challenges. Cohort B (n = 10) underwent a NAC with no treatment intervention, followed by NAC with 14 days pre-treatment with saline nasal spray (placebo), then NAC with 14 days pre-treatment with INCS (220 μg triamcinolone acetonide twice daily). Nasosorption, nasal lavage, blood samples, forced expiratory volume 1 (FEV1), total nasal symptom score (TNSS), peak nasal inspiratory flow (PNIF) were collected up to 24 h after NAC. Total and active tryptase were measured as early-phase allergy biomarkers (≤30 min) and IL-13 and eosinophil cell counts as late-phase allergy biomarkers (3-7 h) in serum and nasal samples. Period-period reproducibility was assessed by intraclass correlation coefficients (ICC), and sample size estimates were performed using effect sizes measured after INCS.

RESULTS

NAC significantly induced acute increases in nasosorption tryptase and TNSS and reduced PNIF, and induced late increases in nasosorption IL-13 with sustained reductions in PNIF. Reproducibility across NACs varied for symptoms and biomarkers, with total tryptase 5 min post NAC having the highest reproducibility (ICC = 0.91). Treatment with INCS inhibited NAC-induced IL-13 while blunting changes in TNSS and PNIF. For a similar crossover study, 7 participants per treatment arm are needed to detect treatment effects comparable to INCS for TNSS.

CONCLUSION

NAC-induced biomarkers and symptoms are reproducible and responsive to INCS. NAC is suitable for assessing pharmacodynamic activity and proof of mechanism for drugs targeting allergic inflammation.

We are memory: B-cell responses in allergy and tolerance

The significance of B-cell memory in sustaining IgE-mediated allergies but also ensuring the development of long-term allergen tolerance has remained enigmatic. However, well-thought murine and human studies have begun to shed more light on this highly disputed subject. The present mini review highlights important aspects, like the involvement of IgG1 memory B cells, the meaning of low- or high-affinity IgE antibody production, the impact of allergen immunotherapy, or the relevance of local memory established by ectopic lymphoid structures. Based on recent findings, future investigations should lead to deeper knowledge and the development of improved therapies treating allergic individuals.

Research Advances in Mast Cell Biology and Their Translation Into Novel Therapies for Anaphylaxis

Anaphylaxis is an acute, potentially life-threatening systemic allergic reaction for which there are no known reliable preventative therapies. Its primary cell mediator, the mast cell, has several pathophysiologic roles and functions in IgE-mediated reactions that continue to be poorly understood. Recent advances in the understanding of allergic mechanisms have identified novel targets for inhibiting mast cell function and activation. The prevention of anaphylaxis is within reach with new drugs that could modulate immune tolerance, mast cell proliferation and differentiation, and IgE regulation and production. Several US Food and Drug Administration-approved drugs for chronic urticaria, mastocytosis, and cancer are also being repurposed to prevent anaphylaxis. New therapeutics have not only shown promise in potential efficacy for preventing IgE-mediated reactions, but in some cases, they are able to inform us about mast cell mechanisms in vivo. This review summarizes the most recent advances in the treatment of anaphylaxis that have arisen from new pharmacologic tools and our current understanding of mast cell biology.

Aiming to IgE: Drug development in allergic diseases

The incidence of allergic disease significantly increases in recent decades, causing it become a major public health problem all over the world. The common allergic diseases such as allergic dermatitis, allergy rhinitis, allergic asthma and food allergy are mediated, at least in part, by immunoglobulin E (IgE), and so IgE acts as a central role in allergic diseases. IgE can interact with its high-affinity receptor (FcεRⅠ) which is primarily expressed on tissue-resident mast cells and circulating basophils, initiating intracellular signal transduction and then causing the activation and degranulation of mast cells and basophils. On the other hand, IgE interaction with its low-affinity receptor (CD23), can regulate various IgE-mediated immune responses including IgE-allergen complex presentation, IgE synthesis, the growth and differentiation of both B and T cells, and the secretion of pro-inflammatory mediators. With the deeper mechanism research for allergic diseases, new therapeutic strategies for interfering IgE are developed and receive a great attention. In this review, we summarize a current profile of therapeutic strategies for interfering IgE in allergic diseases. Besides, we suggest that targeting memory B cells (including long-lived plasma cells and (or) IgE⁺ memory B cells) may help to completely control allergic diseases, and highlight that the development of drugs synergistically aiming to multiple targets can be a better choice for improving treatment efficacy which results from allergic diseases as the systemic disorders caused by an impaired immune system.

Adverse Events for Monoclonal Antibodies in Patients with Allergic Rhinitis: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

(1) Background: Allergic rhinitis (AR) is a common disease in otolaryngology and novel biological therapies are required for clinical needs. To assess the tolerability of monoclonal antibodies, justifying their clinical applications, we presented a comprehensive safety profile of biologics in AR; (2) Methods: A systematic literature search was conducted following PRISMA guidelines for randomized clinical trials comparing monoclonal antibodies and placebo in AR. PubMed, Web of Science, Medline, and Cochrane were searched up until 9 January 2023. Among 3590 records in total, 12 studies with more than 2600 patients were included. Quality was assessed for all studies using Cochrane risk-of-bias tool for randomized trials, and subgrouped meta-analysis was performed; (3) Results: We accomplished an up-to-date literature overview and analysis on adverse events of monoclonal antibodies in AR. Total, common, severe, discontinuation-causing, and serious adverse events failed to reach statistical significance. Country was an essential factor for heterogeneity, and urticaria was the adverse event at highest risk (RR 2.81, 95% CI 0.79-9.95); (4) Conclusions: Monoclonal antibodies are considered well tolerated and relatively safe in patients with AR. The regions of patients and hypersensitive adverse reactions such as urticaria require a special caution in biological treatments in AR.

Drug delivery targets and strategies to address mast cell diseases

INTRODUCTION

Current and developing mast cell therapeutics are reliant on small molecule drugs and biologics, but few are truly selective for mast cells. Most have cellular and disease-specific limitations that require innovation to overcome longstanding challenges to selectively targeting and modulating mast cell behavior. This review is designed to serve as a frame of reference for new approaches that utilize nanotechnology or combine different drugs to increase mast cell selectivity and therapeutic efficacy.

AREAS COVERED

Mast cell diseases include allergy and related conditions as well as malignancies. Here, we discuss the targets of existing and developing therapies used to treat these disease pathologies, classifying them into cell surface, intracellular, and extracellular categories. For each target discussed, we discuss drugs that are either the current standard of care, under development, or have indications for potential use. Finally, we discuss how novel technologies and tools can be used to take existing therapeutics to a new level of selectivity and potency against mast cells.

EXPERT OPINION

There are many broadly and very few selectively targeted therapeutics for mast cells in allergy and malignant disease. Combining existing targeting strategies with technology like nanoparticles will provide novel platforms to treat mast cell disease more selectively.

Biologics as novel therapeutics for the treatment of allergy: Challenges and opportunities

Over the last 4 decades there has been a significant global increase in the incidence and prevalence of IgE-mediated allergy. Although much progress has been made in the management of allergy via patient education, pharmacotherapy and immunomodulatory treatment regimens, significant unmet need remains. Advancements in our knowledge base surrounding the type 2 immune response, production of IgE and maintenance of immunological memory has led the field to explore targeted intervention of allergic pathways using monoclonal antibodies (mAbs). Intervention at various stages of the allergic cascade offers the opportunity to prevent initiation and/or maintenance of the type 2 immune response and effectively provide therapeutic benefit to patients. Furthermore, a better understanding of the protective mechanisms involved in allergen specific immunotherapy (AIT) has led us to appreciate the interplay of immunoglobulins in the allergic response, specifically the benefit in shifting the IgG:IgE ratio in favor of functionally relevant blocking IgG. Thus, treatments that lower IgE or boost IgG with the ability to outcompete IgE binding to allergen also present a favorable approach in the treatment of allergy. In this short review we discuss and highlight recent advances in the use of biologics to treat severe allergy, highlighting the key challenges but also the significant opportunities and advances to date.

Monoclonal Antibodies in Treating Chronic Spontaneous Urticaria: New Drugs for an Old Disease

Background: H1-antihistamines (H1AH) represent the current mainstay of treatment for chronic spontaneous urticaria (CSU). However, the response to H1AH is often unsatisfactory, even with increased doses. Therefore, guidelines recommend the use of omalizumab as an add-on treatment in refractory CSU. This paved the way for the investigation of targeted therapies, such as monoclonal antibodies (mAbs), in CSU. Methods: A literature review was conducted including papers published between 2009 and 2022 and ongoing trials about the efficacy and safety of mAbs as treatment for CSU. Results: Twenty-nine articles, a trial with preliminary results, and seventeen ongoing or completed clinical trials on the use of mAbs in CSU were included. Randomized controlled trials (RCTs), meta-analysis, and real-life studies have proven the effectiveness and safety of omalizumab as a third-line treatment in refractory CSU. However, a percentage of patients remain unresponsive to omalizumab. Therefore, other mAbs, targeting different pathways, have been used off-label in case series and others are under investigation in RCTs. Most of them have showed promising results. Conclusions: Omalizumab remains the best choice to treat refractory CSU. Although results from other mAbs seem to be encouraging to achieve symptom control in refractory CSU, thus improving patients’ QoL, RCTs are needed to confirm their effectiveness and safety.

Anti-IL-5 therapies for asthma

BACKGROUND

This is the second update of previously published reviews in the Cochrane Library (2015, first update 2017). Interleukin-5 (IL-5) is the main cytokine involved in the proliferation, maturation, activation and survival of eosinophils, which cause airway inflammation and are a classic feature of asthma. Studies of monoclonal antibodies targeting IL-5 or its receptor (IL-5R) suggest they reduce asthma exacerbations, improve health-related quality of life (HRQoL) and lung function in appropriately selected patients, justifying their inclusion in the latest guidelines.

OBJECTIVES

To compare the effects of therapies targeting IL-5 signalling (anti-IL-5 or anti-IL-5Rα) with placebo on exacerbations, health-related quality-of-life (HRQoL) measures and lung function in adults and children with chronic asthma, and specifically in those with eosinophilic asthma refractory to existing treatments.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, and two trials registers, manufacturers' websites, and reference lists of included studies. The most recent search was 7 February 2022.

SELECTION CRITERIA

We included randomised controlled trials comparing mepolizumab, reslizumab and benralizumab versus placebo in adults and children with asthma.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and analysed outcomes using a random-effects model. We used standard methods expected by Cochrane.

MAIN RESULTS

Seventeen studies on about 7600 participants met the inclusion criteria. Six used mepolizumab, five used reslizumab, and six used benralizumab. One study using benralizumab was terminated early due to sponsor decision and contributed no data. The studies were predominantly on people with severe eosinophilic asthma, which was similarly but variably defined. One was in children aged 6 to 17 years; nine others included children over 12 years but did not report results by age group separately. We deemed the overall risk of bias to be low, with all studies contributing data of robust methodology. We considered the certainty of the evidence for all comparisons to be high overall using the GRADE scheme, except for intravenous (IV) mepolizumab and subcutaneous (SC) reslizumab because these are not currently licensed delivery routes. The anti-IL-5 treatments assessed reduced rates of 'clinically significant' asthma exacerbation (defined by treatment with systemic corticosteroids for three days or more) by approximately half in participants with severe eosinophilic asthma on standard care (at least medium-dose inhaled corticosteroids (ICS)) with poorly controlled disease (either two or more exacerbations in the preceding year or Asthma Control Questionnaire (ACQ) score of 1.5 or more), except for reslizumab SC. The rate ratios for these effects were 0.45 (95% confidence interval (CI) 0.36 to 0.55; high-certainty evidence) for mepolizumab SC, 0.53 (95% CI 0.44 to 0.64; moderate-certainty evidence) for mepolizumab IV, 0.43 (95% CI 0.33 to 0.55; high-certainty evidence) for reslizumab IV, and 0.59 (95% CI 0.52 to 0.66; high-certainty evidence) for benralizumab SC. Non-eosinophilic participants treated with benralizumab also showed a significant reduction in exacerbation rates, an effect not seen with reslizumab IV, albeit in only one study. No data were available for non-eosinophilic participants treated with mepolizumab. There were improvements in validated HRQoL scores with all anti-IL-5 agents in severe eosinophilic asthma. This met the minimum clinically important difference (MCID) for the broader St. George's Respiratory Questionnaire (SGRQ; 4-point change) for benralizumab only, but the improvement in the ACQ and Asthma Quality of Life Questionnaire (AQLQ), which focus on asthma symptoms, fell short of the MCID (0.5 point change for both ACQ and AQLQ) for all of the interventions. The evidence for an improvement in HRQoL scores in non-eosinophilic participants treated with benralizumab and reslizumab was weak, but the tests for subgroup difference were negative. All anti-IL-5 treatments produced small improvements in mean pre-bronchodilator forced expiratory flow in one second (FEV1) of between 0.08 L and 0.15 L in eosinophilic participants, which may not be sufficient to be detected by patients. There were no excess serious adverse events with any anti-IL-5 treatment; in fact, there was a reduction in such events with benralizumab, likely arising from fewer asthma-related hospital admissions. There was no difference compared to placebo in adverse events leading to discontinuation with mepolizumab or reslizumab, but significantly more discontinued benralizumab than placebo, although the absolute numbers were small (42/2026 (2.1%) benralizumab versus 11/1227 (0.9%) placebo). The implications for efficacy or adverse events are unclear.

AUTHORS' CONCLUSIONS

Overall this analysis supports the use of anti-IL-5 treatments as an adjunct to standard care in people with severe eosinophilic asthma and poor symptom control. These treatments roughly halve the rate of asthma exacerbations in this population. There is limited evidence for improved HRQoL scores and lung function, which may not meet clinically detectable levels. The studies did not report safety concerns for mepolizumab or reslizumab, or any excess serious adverse events with benralizumab, although there remains a question over adverse events significant enough to prompt discontinuation. Further research is needed on biomarkers for assessing treatment response, optimal duration and long-term effects of treatment, risk of relapse on withdrawal, non-eosinophilic patients, children (particularly under 12 years), comparing anti-IL-5 treatments to each other and, in patients meeting relevant eligibility criteria, to other biological (monoclonal antibody) therapies. For benralizumab, future studies should closely monitor rates of adverse events prompting discontinuation.

30 Years of Biotherapeutics Development-What Have We Learned?

Since the birth of biotechnology, hundreds of biotherapeutics have been developed and approved by the US Food and Drug Administration (FDA) for human use. These novel medicines not only bring significant benefit to patients but also represent precision tools to interrogate human disease biology. Accordingly, much has been learned from the successes and failures of hundreds of high-quality clinical trials. In this review, we discuss general and broadly applicable themes that have emerged from this collective experience. We base our discussion on insights gained from exploring some of the most important target classes, including interleukin-1 (IL-1), tumor necrosis factor α (TNF-α), IL-6, IL-12/23, IL-17, IL-4/13, IL-5, immunoglobulin E (IgE), integrins and B cells. We also describe current challenges and speculate about how emerging technological capabilities may enable the discovery and development of the next generation of biotherapeutics.

Tuning IgE: IgE-Associating Molecules and Their Effects on IgE-Dependent Mast Cell Reactions

The recent emergence of anti-immunoglobulin E (IgE) drugs and their candidates for humans has endorsed the significance of IgE-dependent pathways in allergic disorders. IgE is distributed locally in the tissues or systemically to confer a sensory mechanism in a domain of adaptive immunity to the otherwise innate type of effector cells, namely, mast cells and basophils. Bound on the high-affinity IgE receptor FcεRI, IgE enables fast memory responses against revisiting threats of venoms, parasites, and bacteria. However, the dysregulation of IgE-dependent reactions leads to potentially life-threatening allergic diseases, such as asthma and anaphylaxis. Therefore, reactivity of the IgE sensor is fine-tuned by various IgE-associating molecules. In this review, we discuss the mechanistic basis for how IgE-dependent mast cell activation is regulated by the IgE-associating molecules, including the newly developed therapeutic candidates.

Two Sides of the Coin: Mast Cells as a Key Regulator of Allergy and Acute/Chronic Inflammation

It is well known that mast cells (MCs) initiate type I allergic reactions and inflammation in a quick response to the various stimulants, including—but not limited to—allergens, pathogen-associated molecular patterns (PAMPs), and damage-associated molecular patterns (DAMPs). MCs highly express receptors of these ligands and proteases (e.g., tryptase, chymase) and cytokines (TNF), and other granular components (e.g., histamine and serotonin) and aggravate the allergic reaction and inflammation. On the other hand, accumulated evidence has revealed that MCs also possess immune-regulatory functions, suppressing chronic inflammation and allergic reactions on some occasions. IL-2 and IL-10 released from MCs inhibit excessive immune responses. Recently, it has been revealed that allergen immunotherapy modulates the function of MCs from their allergic function to their regulatory function to suppress allergic reactions. This evidence suggests the possibility that manipulation of MCs functions will result in a novel approach to the treatment of various MCs-mediated diseases.

The use of biologics in food allergy

BACKGROUND

Food allergy continues to pose problems due to its increased frequency and its increasingly high severity. In this context, alongside the traditional avoidance strategies of allergenic foods and desensitization through the cautious progression of exposure to foods in the context of oral immunotherapy (OIT), alternative strategies have made their way in the last decades. We review the possibilities of intervention in food allergy with the use of biological drugs capable of interfering with the synthesis of IgE, with their mechanisms of action, or with complex biological mechanisms that lead to the establishment of a food allergy.

METHODS

Repeated Entrez PubMed searches using the template algorithm "Food allergy" and "biologics" or "Omalizumab" or "Dupilumab" or "milk desensitization" or "oral tolerance induction" or "oral immunotherapy" or "Etokimab" or "Tezepelumab" or "Quilizumab" or "Ligelizumab" or "Tralokinumab" or "Nemolizumab" or "Mepolizumab" or "Reslizumab" or "Benralizumab". The authors' clinical experience in paediatric allergy units of University hospitals was also drawn upon.

RESULTS

The landscape in this context has changed dramatically over the past 10 years. We have acquired knowledge mainly on the effect of different types of anti-IgE treatments in poliallergic patients with food allergy, and in patients treated with OIT. However, other mediators are being targeted by specific biologic treatments. Among them, the alarmins Il-33 and TSLP, IL-4 and IL-13, eosinophil-related molecules as IL-6, IL-8, IL-10, IL-12, and mostly IL-5, and integrins involved in the pathogenesis of eosinophilic gastrointestinal diseases (EGIDs), as SIGLEC-8.

CONCLUSIONS

The ever-better knowledge of the mechanisms of food allergy allowing these developments will improve not only the perspective of patients with the most serious immediate food allergies such as anaphylaxis, but also those of patients with related diseases such as atopic dermatitis, eosinophilic esophagitis, and EGIDs. Biologics are also intended to complement OIT strategies that have developed over the years.

Biology and dynamics of B cells in the context of IgE-mediated food allergy

An increasing number of people suffer from IgE-mediated food allergies. The immunological mechanisms that cause IgE-mediated food allergy have been extensively studied. B cells play a key role in the development of IgE-mediated food allergies through the production of allergen-specific antibodies. While this particular function of B cells has been known for many years, we still do not fully understand the mechanisms that regulate the induction and maintenance of allergen-specific IgE production. It is still not fully understood where in the body IgE class switch recombination of food allergen-specific B cells occurs, and what processes are involved in the immunological memory of allergen-specific IgE responses. B cells can also contribute to the regulation of allergen-specific immune responses through other mechanisms such as antigen presentation and cytokine production. Recent technological advances have enabled highly detailed analysis of small subsets of B cells down to the single-cell level. In this review, we provide an overview of the current knowledge on the biology of B cells in relation to IgE-mediated food allergies.

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.

Anti-IgE for the Treatment of Chronic Urticaria

Urticaria and angioedema are very common. Management of chronic urticaria subtypes, which usually persist for many years, is challenging. Recent years have demonstrated that targeting IgE with antibodies provides a safe and efficient treatment approach. Whilst several anti-IgE antibodies have been developed, omalizumab is currently the only one approved for use. International and national guidelines recommend its use after failure of antihistamines at standard and increased dose. Whilst not yet approved, many new anti-IgE approaches are currently being investigated in pre-clinical studies or clinical trials. This non-systematic focused review summarizes current knowledge of omalizumab and other anti-IgE biologics in chronic urticaria using data extracted from PubMed, Google Scholar and clinical trial databases, clinicaltrials.gov and clinicaltrials.eu. For adults, there is good evidence from randomized clinical trials and real-world data that symptomatic treatment with omalizumab is efficacious and safe in chronic spontaneous urticaria (CSU), whereas evidence in chronic inducible urticaria (CINDU) and special populations is limited. Easy-to-use tools to identify non-responders and predict the required duration of treatment have not been established yet. Phase 2 b results of ligelizumab have not only demonstrated efficacy and safety but also superiority to omalizumab. Indeed, there is preliminary evidence that omalizumab non- or partial responders benefit from ligelizumab. Whereas further development of quilizumab was discontinued, other approaches, eg UB-221 or DARPins are under investigation. Anti-IgE treatment with omalizumab represents a landmark in the treatment of chronic urticaria, with and without angioedema, and there is light on the horizon suggesting success may come with various next-generation anti-IgE approaches.

Novel vaccines for allergen-specific immunotherapy

PURPOSE OF REVIEW

Allergen-specific immunotherapy (AIT) is a highly economic, effective and disease-modifying form of allergy treatment but requires accurate prescription and monitoring. New molecular approaches are currently under development to improve AIT by reducing treatment-related side effects, cumbersome protocols and patients' compliance. We review the current advances regarding refined diagnosis for prescription and monitoring of AIT and the development of novel molecular vaccines for AIT. Finally, we discuss prophylactic application of AIT.

RECENT FINDINGS

There is evidence that molecular allergy diagnosis not only assists in the prescription and monitoring of AIT but also allows a refined selection of patients to increase the likelihood of treatment success. New data regarding the effects of AIT treatment with traditional allergen extracts by alternative routes have become available. Experimental approaches for AIT, such as virus-like particles and cell-based treatments have been described. New results from clinical trials performed with recombinant hypoallergens and passive immunization with allergen-specific antibodies highlight the importance of allergen-specific IgG antibodies for the effect of AIT and indicate opportunities for preventive allergen-specific vaccination.

SUMMARY

Molecular allergy diagnosis is useful for the prescription and monitoring of AIT and may improve the success of AIT. Results with molecular allergy vaccines and by passive immunization with allergen-specific IgG antibodies indicate the importance of allergen-specific IgG capable of blocking allergen recognition by IgE and IgE-mediated allergic inflammation as important mechanism for the success of AIT. New molecular vaccines may pave the road towards prophylactic allergen-specific vaccination.

Targeting the FcεRI Pathway as a Potential Strategy to Prevent Food-Induced Anaphylaxis

Despite attempts to halt it, the prevalence of food allergy is increasing, and there is an unmet need for strategies to prevent morbidity and mortality from food-induced allergic reactions. There are no known medications that can prevent anaphylaxis, but several novel therapies show promise for the prevention of food-induced anaphylaxis through targeting of the high-affinity IgE receptor (FcϵRI) pathway. This pathway includes multiple candidate targets, including tyrosine kinases and the receptor itself. Small molecule inhibitors of essential kinases have rapid onset of action and transient efficacy, which may be beneficial for short-term use for immunotherapy buildup or desensitizations. Short courses of FDA-approved inhibitors of Bruton’s tyrosine kinase can eliminate IgE-mediated basophil activation and reduce food skin test size in allergic adults, and prevent IgE-mediated anaphylaxis in humanized mice. In contrast, biologics may provide longer-lasting protection, albeit with slower onset. Omalizumab is an anti-IgE antibody that sequesters IgE, thereby reducing FcϵRI expression on mast cells and basophils. As a monotherapy, it can increase the clinical threshold dose of food allergen, and when used as an adjunct for food immunotherapy, it decreases severe reactions during buildup phase. Finally, lirentelimab, an anti-Siglec-8 antibody currently in clinical trials, can prevent IgE-mediated anaphylaxis in mice through mast cell inhibition. This review discusses these and other emerging therapies as potential strategies for preventing food-induced anaphylaxis. In contrast to other food allergy treatments which largely focus on individual allergens, blockade of the FcϵRI pathway has the advantage of preventing clinical reactivity from any food.

Allergen bronchoprovocation test: an important research tool supporting precision medicine

PURPOSE OF REVIEW

Allergen bronchoprovocation test (ABT) has been used to study asthma pathophysiology and as a disease-modelling tool to assess the properties and efficacy of new asthma drugs. In view of the complexity and heterogeneity of asthma, which has driven the definition of several phenotypes and endotypes, we aim to discuss the role of ABT in the era of precision medicine and provide guidance for clinicians how to interpret and use available data to understand the implications for the benefits of asthma treatment.

RECENT FINDINGS

In this review, we summarize background knowledge and applications of ABT and provide an update with recent publications on this topic. In the past years, several studies have been published on ABT in combination with non-invasive and invasive airway samplings and innovative detection techniques allowing to study several inflammatory mechanisms linked to Th2-pathway and allergen-induced pathophysiology throughout the airways.

SUMMARY

ABT is a valuable research tool, which has strongly contributed to precision medicine by helping to define allergen-triggered key inflammatory pathways and airway pathophysiology, and thus helped to shape our understanding of allergen-driven asthma phenotypes and endotypes. In addition, ABT has been instrumental to assess the interactions and effects of new-targeted asthma treatments along these pathways.

Regulation of the humoral type 2 immune response against allergens and helminths

The type 2 immune response is associated with helminth infections and allergic inflammation where antibody production of the IgG1 and IgE isotypes can elicit protective or proinflammatory functions. Studies over the past few years revealed important new insights regarding the regulatory mechanisms orchestrating the humoral type 2 immune response. This includes investigations on B-cell extrinsic signals, such IL-4 and IL-21, derived from different T-helper cell subsets or discovery of new follicular helper T cells with regulatory or IgE-promoting activities. In addition, studies on B-cell intrinsic factors required for germinal center formation and class switch recombination, including the transcription factors STAT3, STAT6, and BCL-6, led to a better understanding of these processes in type 2 immune responses. Here, we review the current understanding of mechanisms controlling humoral type 2 immunity in vivo including the generation of IgE-producing plasma cells and the memory IgE response.

IgE in the Pathogenesis of SLE: From Pathogenic Role to Therapeutic Target

Systemic lupus erythematosus (SLE) is a multifactorial chronic autoimmune disease, marked by the presence of autoantibodies to nuclear antigens belonging to different isotype classes. For several years, IgE antibodies have been incriminated in the development of allergic diseases and parasitic infections and different anti-IgE therapies have been developed to encounter the pathogenic role of IgE in these pathologies. Recently, multiple studies showed the presence of elevated total IgE levels and demonstrated a pathogenic role of autoreactive IgE in SLE. This review aims to summarize the findings incriminating IgE and autoreactive IgE in the pathophysiology of SLE, to describe their functional outcomes on their targeted cells as well as to discuss different IgE-related therapeutic modalities that emerged and that may be beneficial for SLE patient care.

Chronic allergen exposure drives accumulation of long-lived IgE plasma cells in the bone marrow, giving rise to serological memory

Immunoglobulin E (IgE) plays an important role in allergic diseases. Nevertheless, the source of IgE serological memory remains controversial. We reexamined the mechanism of serological memory in allergy using a dual reporter system to track IgE⁺ plasma cells in mice. Short-term allergen exposure resulted in the generation of IgE⁺ plasma cells that resided mainly in secondary lymphoid organs and produced IgE that was unable to degranulate mast cells. In contrast, chronic allergen exposure led to the generation of long-lived IgE⁺ plasma cells that were primarily derived from sequential class switching of IgG1, accumulated in the bone marrow, and produced IgE capable of inducing anaphylaxis. IgE⁺ plasma cells were found in the bone marrow of human allergic, but not nonallergic donors, and allergen-specific IgE produced by these cells was able to induce mast cell degranulation when transferred to mice. These data demonstrate that long-lived IgE⁺ bone marrow plasma cells arise during chronic allergen exposure and establish serological memory in both mice and humans.

Past, present, and future of anti-IgE biologics

About 20 years after the identification of immunoglobulin E (IgE) and its key role in allergic hypersensitivity reactions against normally harmless substances, scientists have started inventing strategies to block its pathophysiological activity in 1986. The initial concept of specific IgE targeting through the use of anti-IgE antibodies has gained a lot of momentum and within a few years independent research groups have reported successful generation of first murine monoclonal anti-IgE antibodies. Subsequent generation of optimized chimeric and humanized versions of these antibodies has paved the way for the development of therapeutic anti-IgE biologicals as we know them today. With omalizumab, there is currently still only one therapeutic anti-IgE antibody approved for the treatment of allergic conditions. Since its application is limited to the treatment of moderate-to-severe persistent asthma and chronic spontaneous urticaria, major efforts have been undertaken to develop alternative anti-IgE biologicals that could potentially be used in a broader spectrum of allergic diseases. Several new drug candidates have been generated and are currently assessed in pre-clinical studies or clinical trials. In this review, we highlight the molecular properties of past and present anti-IgE biologicals and suggest concepts that might improve treatment efficacy of future drug candidates.

B Cell Responses in the Development of Mammalian Meat Allergy

Studies of meat allergic patients have shown that eating meat poses a serious acute health risk that can induce severe cutaneous, gastrointestinal, and respiratory reactions. Allergic reactions in affected individuals following meat consumption are mediated predominantly by IgE antibodies specific for galactose-α-1,3-galactose (α-gal), a blood group antigen of non-primate mammals and therefore present in dietary meat. α-gal is also found within certain tick species and tick bites are strongly linked to meat allergy. Thus, it is thought that exposure to tick bites promotes cutaneous sensitization to tick antigens such as α-gal, leading to the development of IgE-mediated meat allergy. The underlying immune mechanisms by which skin exposure to ticks leads to the production of α-gal-specific IgE are poorly understood and are key to identifying novel treatments for this disease. In this review, we summarize the evidence of cutaneous exposure to tick bites and the development of mammalian meat allergy. We then provide recent insights into the role of B cells in IgE production in human patients with mammalian meat allergy and in a novel mouse model of meat allergy. Finally, we discuss existing data more generally focused on tick-mediated immunomodulation, and highlight possible mechanisms for how cutaneous exposure to tick bites might affect B cell responses in the skin and gut that contribute to loss of oral tolerance.

Cholinergic Urticaria: Clinical Presentation and Natural History in a Tropical Country

BACKGROUND

Cholinergic urticaria (CholU) is a subset of chronic inducible urticaria characterized by the recurrent pinpoint-sized wheals that are induced by exercising or increasing core body temperature. Currently, the data of CholU in tropical climate is still limited.

OBJECTIVE

To investigate the clinical features and natural course of CholU in a tropical country.

MATERIALS AND METHODS

This retrospective chart review study analyzed the data of CholU patients aged over 18 years who visited Siriraj Urticaria Clinic, Siriraj Hospital, Bangkok, Thailand, between January 2007 and September 2019. Demographic data, clinical presentations, and results of provocation tests and other laboratory investigations were evaluated and compared with other studies reported in temperate zones.

RESULTS

Sixteen out of 2,175 chronic urticaria patients (0.7%) were diagnosed with CholU. The median age of CholU patients was 28.0 ± 11.7 years with male predominance (56.3%). Three patients (18.8%) had a history of atopy. Fifteen patients (93.8%) were positive to the exercise provocation test. Nonsedating antihistamine drugs were a main treatment (73.8%). Six patients (37.5%) were in remission at the time of the study, with a mean duration 4.3 years. The Kaplan-Meier survival analysis demonstrated that 12.5%, 35.5%, and 67.9% of patients would have disease remission within 1 year, 5 years, and 13 years, respectively.

CONCLUSIONS

The prevalence of CholU differs in each geographic region and is found to be low in tropical countries with a median duration 4.3 years. The prevalence of atopy and anaphylaxis with CholU is also lower in tropical countries than in temperate.

Chronic Spontaneous Urticaria: A Review of Pathological Mechanisms, Diagnosis, Clinical Management, and Treatment

Urticaria is a poorly understood and underestimated clinical condition characterised by the sudden onset of itchy wheals and/or angioedema, which usually resolve within 24 and 72 hours, respectively. It is generally classified as being acute (lasting <6 weeks) or chronic (continuous or intermittent for ≥6 weeks). Chronic urticaria can be further classified as chronic spontaneous urticaria (CSU) and chronic inducible urticaria, appearing in response to specific eliciting factors, such as heat, cold, or sun exposure, or following the application of pressure. Scientific advances have been made in the understanding of pathological mechanisms and treatment, especially associated with CSU. The exact pathological mechanism of how urticaria develops is still not yet fully understood, but the clinical implications on the patients’ quality of life are severe and have been associated with mental disorders and metabolic diseases. The diagnosis of urticaria is based on medical history and clinical manifestations. The treatment pathway begins with the administration of second-generation, nonsedating, nonimpairing histamine 1 receptor antihistamines and, in case of nonresponse, with new-generation biological drugs. The current review presents an update of the pathological mechanisms, diagnosis, clinical management, and treatment of CSU. It also focusses on the future implications of new-generation drugs and their effects on the clinical practice.

Cell-bound IgE and plasma IgE as a combined clinical diagnostic indicator for allergic patients

Allergic responses are mainly caused by IgE, which is often located on the cell surface. The current diagnostic method detects both allergen-specific IgE and total IgE levels, but a number of allergic patients have a normal serum IgE level, which is a poor clinical correlate for allergy. Here, we developed a simple method to detect the level of cell-bound IgE by dissociating it from blood cells with lactic acid. Dissociated cell-bound IgE and plasma IgE levels were detected using the same ELISA kit at the same time. We established two clinical cohorts: an allergic patient group and a healthy participant group. In general, cell-bound IgE correlated well with plasma IgE; however, some patients exhibited high cell-bound IgE levels but low plasma IgE levels. We recommended 350 ng/mL peripheral blood total IgE (cell-bound IgE + plasma IgE) as the cut-off value for allergy diagnosis. Using this indicator, 90.32% of our allergic patients were correctly diagnosed. The peripheral blood total IgE level is a promising clinical diagnostic indicator in allergic patients and will provide more guidance for allergy diagnosis and therapeutic evaluation.

Chinese Society of Allergy and Chinese Society of Otorhinolaryngology-Head and Neck Surgery Guideline for Chronic Rhinosinusitis

The current document is based on a consensus reached by a panel of experts from the Chinese Society of Allergy and the Chinese Society of Otorhinolaryngology-Head and Neck Surgery, Rhinology Group. Chronic rhinosinusitis (CRS) affects approximately 8% of Chinese adults. The inflammatory and remodeling mechanisms of CRS in the Chinese population differ from those observed in the populations of European descent. Recently, precision medicine has been used to treat inflammation by targeting key biomarkers that are involved in the process. However, there are no CRS guidelines or a consensus available from China that can be shared with the international academia. The guidelines presented in this paper cover the epidemiology, economic burden, genetics and epigenetics, mechanisms, phenotypes and endotypes, diagnosis and differential diagnosis, management, and the current status of CRS in China. These guidelines-with a focus on China-will improve the abilities of clinical and medical staff during the treatment of CRS. Additionally, they will help international agencies in improving the verification of CRS endotypes, mapping of eosinophilic shifts, the identification of suitable biomarkers for endotyping, and predicting responses to therapies. In conclusion, these guidelines will help select therapies, such as pharmacotherapy, surgical approaches and innovative biotherapeutics, which are tailored to each of the individual CRS endotypes.

Protective Effect of Circular RNA (CircRNA) Ddx17 in Ovalbumin (OVA)-Induced Allergic Rhinitis (AR) Mice

Background

CircRNAs are involved in multiple biological processes, especially when they act as sponges of miRNA. Thus, the present study investigated the effect of circDdx17 on allergic rhinitis (AR) in an animal model, and determined the miRNA that was involved in this effect.

Material/Methods

The AR model was created by repetitive stimulation of ovalbumin (OVA). The levels of mRNAs in plasma were determined by qPCR. CircDdx17 stability was assessed using RNase R. The interaction between circDdx17 and miR-17-5p was predicted by bioinformatics and confirmed by dual luciferase assay. Moreover, the frequencies of rubbing and sneezing and pathological changes were recorded, and OVA-specific IgE, tumor necrosis factor (TNF)-α, interleukin (IL)-4, and IL-5 levels were detected by ELISA.

Results

Levels of circDdx17 were decreased in OVA-induced AR mice, and miR-17-5p interacted with circDdx17 in spleen cells derived from mice. Moreover, circDdx17 overexpression reduced the expression of miR-17-5p, OVA-specific IgE, TNF-α, IL-4, and IL-5, as well as the frequencies of rubbing and sneezing, and alleviated pathological changes in OVA-induced AR mice.

Conclusions

CircDdx17 appears to have a protective effect on mice in the progression of AR. Specifically, overexpression of circDdx17 inhibited the expression of miR-17-5p and alleviated the condition of AR. Therefore, circDdx17 appears to be a good candidate for use in prevention of AR. However, the detailed mechanism underlying the circDdx17/miR-17-5p regulatory pathway requires further study.

Biologics in Children with Allergic Diseases

The prevalence of allergic diseases has been remarkably increased in the last decades. The global health burden of these conditions is substantial, since patients may experience disability, anxiety and emotional distress, social restrictions, and reduced quality of life and productivity, in particular, in the most severe cases. Recent advances in understanding the pathophysiology of allergic disorders have allowed identifying novel therapeutic strategies for the treatment of severe and uncontrolled allergic diseases. Although most studies have been performed in allergic asthma, biological drugs targeting other allergic diseases such as chronic spontaneous urticaria, atopic dermatitis, and food allergy are showing promising results. In this review, the most recent evidence on biologic therapies for allergic diseases, focusing on the pediatric age has been presented.

Emerging Biomarkers and Therapeutic Pipelines for Chronic Spontaneous Urticaria

Chronic spontaneous urticaria (CSU) is defined as the appearance of evanescent wheals, angioedema, or both, for at least 6 weeks. CSU is associated with intense pruritus and poor quality of life, with higher odds of reporting depression, anxiety, and sleep difficulty. As of yet, the assessment of the activity and course of the disease along with the response to several treatments in CSU are based purely on the patient's medical history and the use of the patient-reported outcomes. Recently, several reports have suggested that certain parameters could be considered as potential disease-related biomarkers. Moreover, with the advent of such biomarkers, newer biologic agents are coming forth to revolutionize the management of potential refractory diseases such as CSU. The purpose of this article is to review the most promising biomarkers related to important aspects of CSU, such as the disease activity, the therapeutic response, and the natural history of the disease, and discuss the mechanisms of action and therapeutic effectiveness of the latest agents available or currently under investigation for the management of antihistamine-refractory CSU. The knowledge of these features could have an important impact on the management and follow-up of patients with CSU.

Tracing IgE-Producing Cells in Allergic Patients

Immunoglobulin E (IgE) is the key immunoglobulin in the pathogenesis of IgE associated allergic diseases affecting 30% of the world population. Recent data suggest that allergen-specific IgE levels in serum of allergic patients are sustained by two different mechanisms: inducible IgE production through allergen exposure, and continuous IgE production occurring even in the absence of allergen stimulus that maintains IgE levels. This assumption is supported by two observations. First, allergen exposure induces transient increases of systemic IgE production. Second, reduction in IgE levels upon depletion of IgE from the blood of allergic patients using immunoapheresis is only temporary and IgE levels quickly return to pre-treatment levels even in the absence of allergen exposure. Though IgE production has been observed in the peripheral blood and locally in various human tissues (e.g., nose, lung, spleen, bone marrow), the origin and main sites of IgE production in humans remain unknown. Furthermore, IgE-producing cells in humans have yet to be fully characterized. Capturing IgE-producing cells is challenging not only because current staining technologies are inadequate, but also because the cells are rare, they are difficult to discriminate from cells bearing IgE bound to IgE-receptors, and plasma cells express little IgE on their surface. However, due to the central role in mediating both the early and late phases of allergy, free IgE, IgE-bearing effector cells and IgE-producing cells are important therapeutic targets. Here, we discuss current knowledge and unanswered questions regarding IgE production in allergic patients as well as possible therapeutic approaches targeting IgE.

Generation of IgE-specific cytotoxic T lymphocytes as a novel immunotherapeutic approach for the treatment of allergic asthma

INTRODUCTION

Overproduction of immunoglobulin E (IgE) by a subset of B cells plays a key role in the pathogenesis of allergic asthma. Anti-IgE monoclonal antibodies have been successfully used to treat the disease, but long-term application is required.

METHODS

For this study, cytotoxic T lymphocytes (CTLs) against IgE-producing B cells were generated ex vivo by stimulating naive CD8 T cells with IgE-derived peptides presented by Drosophila-derived artificial antigen-presenting cells. Based on the treatment of allergic asthma in mice, the inhibitive effect of this CTL on IgE responses and airway inflammation was determined with the enzyme-linked immunosorbent assay and histochemical method.

RESULTS

The IgE-specific CTLs effectively lysed target cells in vitro, while the adoptively transferred CTLs specifically inhibited IgE responses and airway inflammation in an asthmatic mouse model. The effect of IgE-specific CTLs is MHC (major histocompatibility complex) Class I-restricted and requires the expression of perforin.

CONCLUSION

IgE-specific CTLs generated ex vivo may provide a novel treatment for allergic asthma and lead to a new therapy for other immunological disorders.

[Immunology of chronic rhinosinusitis with nasal polyps as a basis for treatment with biologicals]

BACKGROUND

Chronic rhinosinusitis (CRS) is a heterogeneous and multifactorial inflammation of the nasal and paranasal mucosa. Until now, no internationally standardized classification could be developed. In most cases, CRS is phenotypically classified according to chronic rhinosinusitis with (CRScNP) and without nasal polyps (CRSsNP). However, recent studies could show that there are numerous endotypes within these phenotypes based on different inflammatory mechanisms. This review describes the important immunological mechanisms of CRScNP and highlights modern treatment options with biologicals directly addressing particular immunological processes.

METHODS

Current knowledge on immunological and molecular processes of CRS, particularly CRScNP, was extracted from Medline, PubMed, national and international study- and guideline-registers, and the Cochrane library by a systematic review of the literature.

RESULTS

Based on current literature, various immunological mechanisms for CRS and CRScNP could be identified. Relevant studies for the treatment of eosinophilic conditions such as asthma or CRScNP are presented and, if available, results of these studies are discussed.

CONCLUSION

The growing insight into the underlying immunological mechanisms of CRScNP could pave the way for new personalized treatment options such as biologicals in the future.

Immunotherapy and biologicals for the treatment of allergy to Hymenoptera stings

Introduction: Venom immunotherapy (VIT) is an effective treatment for Hymenoptera venom allergy. The occurrence of severe reactions (SRs) to VIT, although infrequent, hampers the achievement of tolerance to insect stings. Risk factors for such reactions include allergy to honeybee venom, concomitant mast cell disorders, and the build-up phase of VIT. A role for omalizumab has come forward in recent years. Areas covered: This article reviews the available literature on the efficacy of omalizumab in preventing SRs and allowing the attainment of VIT maintenance doses. Pre- and co-treatments with omalizumab were evaluated, with positive overall results. Adding omalizumab to VIT in patients with SRs generally results in tolerance to VIT, thus restoring its precious preventive value. Expert opinion: VIT is effective for patients with Hymenoptera venom allergy and is recommended to prevent further (possibly fatal) reactions to stings. Omalizumab has shown efficacy in protecting patients from VIT-related SRs, particularly in those at high risk of SRs because of mast cell disorders and/or honeybee venom allergy. Notwithstanding, the accepted dose and time course of omalizumab for achieving tolerability and ensuring safety during VIT are not yet defined. In the future, other biologicals may play a role in preventing SRs during VIT.

Precision/Personalized Medicine in Allergic Diseases and Asthma

Like many other chronic diseases, every allergic patient has different characteristics based on clinical course, treatment responsiveness and disease outcomes, which are associated with the genetic and epigenetic control of molecular mechanisms and environment. This variability necessitates the establishment of patient-tailored and precision approaches in handling allergic disorders. Better understanding of the underlying pathophysiological mechanisms for the development of allergic disorders will provide more rationale strategies based on individual cases in controlling and treating these disorders. Endotyping, phenotyping, genotyping and theratyping, and biomarkers are keywords in this area and have been gaining lots of attention in the field of precision medicine, which aims to revolutionize patient care and develop better prevention and treatment strategies. In addition, precision health is a new concept that brings precise approaches to the scene for being healthy and prevention of allergic disease and asthma. The specialty of allergy has a leading role in the field, because allergen-specific immunotherapy started 105 years ago, and is historically a leading personalized/precision medicine approach in all medicine disciplines providing the possibility of cure in an individualized manner instead of conventional symptomatic treatments.

Anti-IgE therapy for IgE-mediated allergic diseases: from neutralizing IgE antibodies to eliminating IgE+ B cells

Allergic diseases are inflammatory disorders that involve many types of cells and factors, including allergens, immunoglobulin (Ig)E, mast cells, basophils, cytokines and soluble mediators. Among them, IgE plays a vital role in the development of acute allergic reactions and chronic inflammatory allergic diseases, making its control particularly important in the treatment of IgE-mediated allergic diseases. This review provides an overview of the current state of IgE targeted therapy development, focusing on three areas of translational research: IgE neutralization in blood; IgE-effector cell elimination; and IgE⁺ B cell reduction. IgE-targeted medicines such as FDA approved drug Xolair (Omalizumab) represent a promising avenue for treating IgE-mediated allergic diseases given the pernicious role of IgE in disease progression. Additionally, targeted therapy for IgE-mediated allergic diseases may be advanced through cellular treatments, including the modification of effector cells.

Targeting IgE in allergic disease

Immunoglobulin E (IgE) represents the least abundant antibody isotype in human serum. Nevertheless, it has the ability to induce potent allergic reactions. As a key component in the development and manifestation of hypersensitivity responses against usually non-hazardous foreign substances, IgE has become a major target of investigation and the subject of multiple therapeutic approaches for the treatment of allergies. Recent advances in the understanding of pathophysiologic mechanisms underlying IgE-associated allergic disorders have led to the generation of new drug candidates that are currently in development or under clinical evaluation. In this review, we highlight molecular and structural mechanisms underlying the different anti-IgE molecules and suggest a concept of multi-level targeting using a new class of disruptive IgE inhibitors to potentially optimize treatment efficacy.

Approaches to target IgE antibodies in allergic diseases

IgE is the antibody isotype found at the lowest concentration in the circulation. However IgE can undeniably play an important role in mediating allergic reactions; best exemplified by the clinical benefits of anti-IgE monoclonal antibody (omalizumab) therapy for some allergic diseases. This review will describe our current understanding of the interactions between IgE and its main receptors FcεRI and CD23 (FcεRII). We will review the known and potential functions of IgE in health and disease: in particular, its detrimental roles in allergic diseases and chronic spontaneous urticaria, and its protective functions in host defense against parasites and venoms. Finally, we will present an overview of the drugs that are in clinical development or have therapeutic potential for IgE-mediated allergic diseases.

IgE-expressing memory B cells and plasmablasts are increased in blood of children with asthma, food allergy, and atopic dermatitis

Despite the critical role of soluble IgE in the pathology of IgE-mediated allergic disease, little is known about abnormalities in the memory B cells and plasma cells that produce IgE in allergic patients. We here applied a flow cytometric approach to cross-sectionally study blood IgE+ memory B cells and plasmablasts in 149 children with atopic dermatitis, food allergy, and/or asthma and correlated these to helper T(h)2 cells and eosinophils. Children with allergic disease had increased numbers of IgE+CD27- and IgE+CD27+ memory B cells and IgE+ plasmablasts, as well as increased numbers of eosinophils and Th2 cells. IgE+ plasmablast numbers correlated positively with Th2 cell numbers. These findings open new possibilities for diagnosis and monitoring of treatment in patients with allergic diseases.

Molecular Aspects of Allergens and Allergy

Immunoglobulin E (IgE)-associated allergy is the most common immune disorder. More than 30% of the population suffer from symptoms of allergy which are often severe, disabling, and life threatening such as asthma and anaphylaxis. Population-based birth cohort studies show that up to 60% of the world population exhibit IgE sensitization to allergens, of which most are protein antigens. Thirty years ago the first allergen-encoding cDNAs have been isolated. In the meantime, the structures of most of the allergens relevant for disease in humans have been solved. Here we provide an update regarding what has been learned through the use of defined allergen molecules (i.e., molecular allergology) and about mechanisms of allergic disease in humans. We focus on new insights gained regarding the process of sensitization to allergens, allergen-specific secondary immune responses, and mechanisms underlying allergic inflammation and discuss open questions. We then show how molecular forms of diagnosis and specific immunotherapy are currently revolutionizing diagnosis and treatment of allergic patients and how allergen-specific approaches may be used for the preventive eradication of allergy.