Biomarkers for monitoring clinical efficacy of allergen immunotherapy for allergic rhinoconjunctivitis and allergic asthma: an EAACI Position Paper

On the role of antibody affinity and avidity in the IgE-mediated allergic response

Type I hypersensitivity, also known as classical allergy, is mediated via allergen-specific IgE antibodies bound to type I FcR (FcεRI) on the surface of mast cells and basophils upon cross-linking by allergens. This IgE-mediated cellular activation may be blocked by allergen-specific IgG through multiple mechanisms, including direct neutralization of the allergen or engagement of the inhibitory receptor FcγRIIb which blocks IgE signal transduction. In addition, co-engagement of FcεRI and FcγRIIb by IgE-IgG-allergen immune complexes causes down regulation of receptor-bound IgE, resulting in desensitization of the cells. Both, activation of FcεRI by allergen-specific IgE and engagement of FcγRIIb by allergen-specific IgG are driven by allergen-binding. Here we delineate the distinct roles of antibody affinity versus avidity in driving these processes and discuss the role of IgG subclasses in inhibiting basophil and mast cell activation.

Reducing the solubility of the major birch pollen allergen Bet v 1 by particle-loading mitigates Th2 responses

BACKGROUND

Solubility is a common feature of allergens. However, the causative relationship between this protein-intrinsic feature and sensitization capacity of allergens is not fully understood. This study aimed to proof the concept of solubility as a protein intrinsic feature of allergens.

METHODS

The soluble birch pollen allergen Bet v 1 was covalently coupled to 1 μm silica particles. IgE-binding and -cross-linking capacity was assessed by inhibition ELISA and mediator release assay, respectively. Alterations in adjuvanticity by particle-loading were investigated by activation of dendritic cells, mast cells and the Toll-like receptor 4 pathway as well as by Th2 polarization in an IL-4 reporter mouse model. In BALB/c mice, particle-loaded and soluble Bet v 1 were compared in a model of allergic sensitization. Antigen uptake and presentation was analysed by restimulating human Bet v 1-specific T cell lines.

RESULTS

Covalent coupling of Bet v 1 to silica particles resulted in an insoluble antigen with retained IgE-binding and -cross-linking capacity and no increase in adjuvanticity. In vivo, particle-loaded Bet v 1 induced significantly lower Bet v 1-specific (s)IgE, whereas sIgG1 and sIgG2a levels remained unaffected. The ratio of Th2 to Th1 cells was significantly lower in mice sensitized with particle-loaded Bet v 1. Particle-loading of Bet v 1 resulted in a 24-fold higher T cell activation capacity in Bet v 1-specific T cell lines, indicating more efficient uptake and presentation than of soluble Bet v 1.

CONCLUSIONS

Our results show that solubility is a decisive factor contributing to the sensitization capacity of allergens. The reduction in sensitization capacity of insoluble, particle-loaded antigens results from enhanced antigen uptake and presentation compared to soluble allergens.

Allergen immunotherapy in asthma

Allergen immunotherapy (AIT), including SCIT and SLIT, is a treatment that involves the administration of allergens to which patients with allergic diseases have been sensitized. HDM-SCIT for asthma is indicated in cases of HDM-sensitized allergic asthma with normal lung function. HDM-SCIT improves asthma symptoms and AHR, and decreases the medication dose. Importantly, AIT can improve other allergic diseases complicated by asthma, such as allergic rhinitis, which can also contribute to the improvement of asthma symptoms. Several studies have suggested that HDM-SLIT also attenuates the risk of asthma exacerbations, and improves lung function in asthma cases with allergic rhinitis. Furthermore, AIT can modify the natural course of allergic diseases, including asthma. For example, the effects of AIT are maintained for at least several years after treatment discontinuation. AIT can prevent the onset of asthma when introduced in allergic rhinitis, and can also inhibit or reduce new allergen sensitizations. Recent data have suggested that AIT may suppress non-targeted allergen-induced immune responses in addition to targeted allergen-induced responses, and suppress infections of the lower respiratory tract by enhancing IFN responses.

Efficacy and safety of subcutaneous immunotherapy combined with omalizumab in children with dust mite-induced asthma

OBJECTIVE

To evaluate the benefits of combining omalizumab with specific immunotherapy (SCIT) in the treatment of children with bronchial asthma.

METHODS

In this study, 83 children with asthma were treated at the Allergy Department of Qingdao University from January 2019 to February 2020. Participants were divided into three groups: SCIT, combination (omalizumab + SCIT), and control (standard asthma medications). We assessed Asthma Control Questionnaire (ACQ) scores, Visual Analogue Scale (VAS) scores, and lung function at baseline, 24 wk, and 48 wk. Additionally, asthma medication scores were compared at 24 and 48 wk. Adverse reactions were monitored in both the SCIT and combination groups.

RESULTS

The combination group demonstrated lower ACQ scores at both 24 and 48 wk, and improved VAS scores at 48 wk compared to the other groups. Additionally, lung function parameters (FEV1 and FEF50) showed significant improvement in the combination group. Reduced asthma medication scores were noted in the combination group at 24 and 48 wk. Local adverse reactions were fewer in the combination group, and no systemic adverse reactions were reported.

CONCLUSION

Combining omalizumab with SCIT provides quicker asthma control, lowers medication requirements, and enhances lung function with fewer adverse effects, making it a safe and effective treatment for children with bronchial asthma.

Consistent efficacy and safety of sublingual immunotherapy tablets across allergens and geographic regions

Background: The clinical development program of the SQ grass, ragweed, tree, and house dust mite (HDM) sublingual immunotherapy (SLIT)-tablets for allergic rhinitis/conjunctivitis (AR/C) included clinical trials conducted in North America, Europe, and Japan. Objective: Data from these trials were analyzed to assess efficacy, immunologic mechanisms, and safety outcomes across allergens and geographic regions. Methods: Thirteen phase III, double-blind, placebo controlled trials in the subjects with AR/C were conducted in North America, Europe (including Russia), and Japan (N = 7763 analyzed). Trials were generally similar with respect to medical practice, target population, eligibility criteria, and efficacy and safety monitoring. Data were analyzed for the approved doses in North America and Europe. Four statistical models were used to enhance comparison of the efficacy end points among the trials. Results: The SLIT-tablets demonstrated consistent efficacy across allergens and regions, regardless of the statistical analysis used. Relative improvement in the primary efficacy end point compared with placebo by using the predefined protocol analysis ranged from 17.9% to 32.8%, 17.5% to 19.3%, 20.6% to 38.3%, and 39.6% with the grass, HDM, ragweed, and tree SLIT-tablets, respectively. The kinetics of specific immunoglobulin E (IgE) and IgG4 responses were similar among the allergens and regions. Local application-site reactions were the most common adverse events for all allergens and in all regions. Most treatment-related adverse events for all allergens and in all regions were mild in severity. The rate of systemic allergic reactions was similar across regions (0%-0.54%). Conclusion: Confirmatory phase III trials for SLIT-tablets in the treatment of AR/C showed consistent efficacy, immunologic, and safety outcomes across allergens and geographic regions.

Oral immunotherapy with enteric-coated capsules for allergic rhinitis caused by house dust mites

Background

Oral immunotherapy (OIT) is a promising allergen-specific approach in the management of food allergy; however, studies on OIT for allergic rhinitis (AR) have rarely been reported. The purpose of this study is to evaluate the efficacy and safety of OIT using enteric-coated capsules for AR induced by house dust mites.

Methods

A total of 49 patients with AR were enrolled, including 25 who received subcutaneous immunotherapy (SCIT) and 24 who received OIT. The clinical efficacy and safety in both groups were evaluated.

Results

After 1 year of treatment, both SCIT and OIT demonstrated significant therapeutic effects. OIT was found to be more effective than SCIT in reducing the total AR symptom score and improving the results of nasal provocation tests. Local and systemic adverse reactions were observed in the SCIT group, while none were reported in the OIT group.

Conclusion

OIT is an effective and safe treatment for mite-induced AR.

Development and validation of a health practitioner survey on ocular allergy

Survey studies have played a significant role in understanding the gaps in the knowledge and practices of health practitioners. However, there have been no such survey studies on Ocular Allergy (OA). Thus, the purpose of this study was to develop and validate a survey on OA to better understand the gaps in the diagnostic, treatment, and collaborative care approaches of health practitioners in OA. The survey is titled "Survey on Ocular Allergy for Health Practitioners (SOAHP)". SOAHP was developed in a five-stage process. First, item extraction via the use of a literature review, second, face and content validity, third, a pilot study, fourth, test-retest reliability, and fifth, finalisation of the survey. 65 items under 6 domains were initially generated in the item extraction phase. Content validity was conducted on 15 experts in the field. This was conducted twice to reach consensus whereby items and domains were added, edited, kept, or removed, resulting in 50 items under 7 domains. The pilot study was conducted on 15 participants from the five relevant health practitioner fields (Allergists/Immunologists, General Practitioners (GPs), Ophthalmologists, Optometrists and Pharmacists). This altered the survey further to 40 items under 7 domains. Test-retest reliability was conducted on 25 participants from the five health practitioner fields. Reliability was moderate to almost perfect for most (97%) investigated items. The finalised survey was 40 items under 7 domains. SOAHP is the first survey created to assess diagnostic, treatment and collaborative care approaches of Allergists/Immunologists, GPs, Ophthalmologists, Optometrists and Pharmacists on OA. SOAHP will be a useful tool in clinical research on OA.

[Allergen-specific immunotherapy : A brief overview in association with allergic conjunctivitis]

Allergen-specific immunotherapy (AIT) is the only causal and disease-modifying treatment for immunoglobulin E (IgE)-mediated type I allergies. Regular exposure to the causative allergen results in an immunomodulatory effect by which the predominant T‑helper (Th) 2 lymphocyte response is shifted to a Th1 lymphocyte response and more allergen-specific blocking immunoglobulins are produced. The approval of substances for AIT is regulated by the Therapy Allergens Ordinance (TAV). There are subcutaneous and/or sublingual AITs for the following indications: allergic rhinitis, allergic conjunctivitis, allergic asthma and insect venom allergy. In this article the indications for allergic conjunctivitis are discussed in particular. Clinical symptoms and a relevant type 1 sensitization are the prerequisites for the indications for AIT. The assessment of the indications and carrying out an AIT should only be carried out by physicians who have been trained in allergology.

Evaluation of the Cytokine Response Induced by Specific Allergen Immunotherapy in Patients with Vespa velutina Anaphylaxis

INTRODUCTION

Changes in the cytokine profile from type 2 to type 1 together with the induction of regulatory cells are expected during hymenoptera venom immunotherapy (VIT). The present study was aimed to investigate the changes in type 1, type 2, and regulatory cytokines induced by a Vespula spp. VIT in patients with anaphylaxis to Vespa velutina.

METHODS

Twenty consecutive patients with anaphylaxis due to Vespa velutina were treated with Vespula spp. VIT. Serum cytokines (IL-4, IL-5, IL-10, IL-13, and IFN-ɣ) were measured at baseline, 6, and 12 months after starting VIT.

RESULTS

A significant increase in serum IFN-y was detected after 6 and 12 months of VIT. An increase in serum IL-10 and a decrease in IL-5 were observed after 12 months. IL-4 was undetectable all along the study, and an unexpected increase of IL-13 was present at 12 months of treatment.

CONCLUSION

Vespula spp. VIT seems to be able to induce a shift to type 1 cytokine production measured through IFN-y levels and IL-10 production after, at least, 6 and 12 months of VIT, respectively.

Novel adjuvants in allergen-specific immunotherapy: where do we stand?

Type I hypersensitivity, or so-called type I allergy, is caused by Th2-mediated immune responses directed against otherwise harmless environmental antigens. Currently, allergen-specific immunotherapy (AIT) is the only disease-modifying treatment with the potential to re-establish clinical tolerance towards the corresponding allergen(s). However, conventional AIT has certain drawbacks, including long treatment durations, the risk of inducing allergic side effects, and the fact that allergens by themselves have a rather low immunogenicity. To improve AIT, adjuvants can be a powerful tool not only to increase the immunogenicity of co-applied allergens but also to induce the desired immune activation, such as promoting allergen-specific Th1- or regulatory responses. This review summarizes the knowledge on adjuvants currently approved for use in human AIT: aluminum hydroxide, calcium phosphate, microcrystalline tyrosine, and MPLA, as well as novel adjuvants that have been studied in recent years: oil-in-water emulsions, virus-like particles, viral components, carbohydrate-based adjuvants (QS-21, glucans, and mannan) and TLR-ligands (flagellin and CpG-ODN). The investigated adjuvants show distinct properties, such as prolonging allergen release at the injection site, inducing allergen-specific IgG production while also reducing IgE levels, as well as promoting differentiation and activation of different immune cells. In the future, better understanding of the immunological mechanisms underlying the effects of these adjuvants in clinical settings may help us to improve AIT.

Peripheral blood mononuclear cell transcriptome profile in a clinical trial with subcutaneous, grass pollen allergoid immunotherapy

INTRODUCTION

Allergen-specific immunotherapy (AIT) is the only disease-modifying treatment in allergic airway diseases. Underlying immunological mechanisms and candidate biomarkers, which may be translated into predictive/surrogate measures of clinical efficacy, remain an active area of research. The aim of this study was to evaluate Pollinex Quattro (PQ) Grass AIT induced immunomodulatory mechanisms, based on transcriptome profiling of peripheral blood mononuclear cells.

METHODS

119 subjects with grass pollen induced seasonal allergic rhinitis (SAR) were randomized in a 2:2:1:1 ratio to receive a cumulative dose of PQ Grass as a conventional or extended pre-seasonal regimen, placebo, or placebo with MicroCrystalline Tyrosine. Gene expression analysis was an exploratory endpoint evaluated in a subgroup of 30 subjects randomly selected from the four treatment arms. Samples were collected at three time points: screening (baseline), before the start of the grass pollen season and at the end of the season. This study was funded by the manufacturer of PQ.

RESULTS

Transcriptome analysis demonstrated that the most significant changes in gene expression, for both treatment regimens, were at the end of the grass pollen season, with the main Th1 candidate molecules (IL-12A, IFNγ) upregulated and Th2 signature cytokines downregulated (IL-4, IL-13, IL-9) (p < .05). Canonical pathways analysis demonstrated Th1, Th2, Th17 and IL-17 as the most significantly enriched pathways based on absolute value of activation z-score (IzI score ≥ 2, p < .05). Upstream regulator analysis showed pronounced inhibition of pro-inflammatory allergic molecules IgE, IL-17A, IL-17F, IL-25 (IL-17E) (IzI score ≥ 2, FDR < 0.05) and activation of pro-tolerogenic molecules IL-12A, IL-27, IL-35 (EBI3) at the end of the grass pollen season.

CONCLUSION

Peripheral blood mononuclear cells transcriptome profile showed an inhibition of Th2, Th17 pro-inflammatory allergic responses and immune deviation towards Th1 responses. PQ Grass extended regimen exhibited a superior mechanistic efficacy profile in comparison with PQ conventional regimen.

Mechanisms and Predictive Biomarkers of Allergen Immunotherapy in the Clinic

Allergen immunotherapy (AIT) remains to be the only disease-modifying treatment for IgE-mediated allergic diseases such as allergic rhinitis. It can provide long-term clinical benefits when given for 3 years or longer. Mechanisms of immune tolerance induction by AIT are underscored by the modulation of several compartments within the immune system. These include repair of disruption in epithelial barrier integrity, modulation of the innate immune compartment that includes regulatory dendritic cells and innate lymphoid cells, and adaptive immune compartments such as induction of regulatory T and B cells. Altogether, these are also associated with the dampening of allergen-specific TH2 and T follicular helper cell responses and subsequent generation of blocking antibodies. Although AIT is effective in modifying the immune response, there is a lack of validated and clinically relevant biomarkers that can be used to monitor desensitization, efficacy, and the likelihood of response, all of which can contribute to accelerating personalized medication and increasing patient care. Candidate biomarkers comprise humoral, cellular, metabolic, and in vivo biomarkers; however, these are primarily studied in small trials and require further validation. In this review, we evaluate the current candidates of biomarkers of AIT and how we can implement changes in future studies to help us identify clinically relevant biomarkers of safety, compliance, and efficacy.

Prevention Is Better than Cure: Impact of Allergen Immunotherapy on the Progression of Airway Disease

Allergen immunotherapy is highly effective for seasonal pollinosis. Three years of treatment results in long-term efficacy. This disease modification is accompanied by downregulation of allergen-specific Th2 responses and the induction of persistent specific IgG- and IgA-associated IgE-blocking activity. In children with seasonal rhinitis, both subcutaneous and sublingual pollen immunotherapy have been shown to reduce the development of asthma symptoms and asthma medication requirements. House dust mite tablet allergen immunotherapy has been shown to be effective for perennial mite-driven rhinitis in adults and children and may suppress asthma exacerbations, whereas its long-term efficacy has yet to be explored. The success of primary prevention of peanut allergy in childhood by introduction of peanut into the diet during infancy provides a strong rationale to explore whether primary prevention of inhalant allergies and asthma may also be possible. House dust mite allergy is a major risk factor for developing asthma. Preliminary data in at-risk children suggest that sublingual house dust mite immunotherapy initiated during infancy could reduce the onset of multiple allergen sensitizations and prevent the development of asthma at age 6 years. This possibility should now be explored in an adequately powered, prospectively randomized controlled trial.

Natural human Bet v 1-specific IgG antibodies recognize non-conformational epitopes whereas IgE reacts with conformational epitopes

BACKGROUND

The nature of epitopes on Bet v 1 recognized by natural IgG antibodies of birch pollen allergic patients and birch pollen-exposed but non-sensitized subjects has not been studied in detail.

OBJECTIVE

To investigate IgE and IgG recognition of Bet v 1 and to study the effects of natural Bet v 1-specific IgG antibodies on IgE recognition of Bet v 1 and Bet v 1-induced basophil activation.

METHODS

Sera from birch pollen allergic patients (BPA, n = 76), allergic patients without birch pollen allergy (NBPA, n = 40) and non-allergic individuals (NA, n = 48) were tested for IgE, IgG as well as IgG1 and IgG4 reactivity to folded recombinant Bet v 1, two unfolded recombinant Bet v 1 fragments comprising the N-terminal (F1) and C-terminal half of Bet v 1 (F2) and unfolded peptides spanning the corresponding sequences of Bet v 1 and the apple allergen Mal d 1 by ELISA or micro-array analysis. The ability of Bet v 1-specific serum antibodies from non-allergic subjects to inhibit allergic patients IgE or IgG binding to rBet v 1 or to unfolded Bet v 1-derivatives was assessed by competition ELISAs. Furthermore, the ability of serum antibodies from allergic and non-allergic subjects to modulate Bet v 1-induced basophil activation was investigated using rat basophilic leukaemia cells expressing the human FcεRI which had been loaded with IgE from BPA patients.

RESULTS

IgE antibodies from BPA patients react almost exclusively with conformational epitopes whereas IgG, IgG1 and IgG4 antibodies from BPA, NBPA and NA subjects recognize mainly unfolded and sequential epitopes. IgG competition studies show that IgG specific for unfolded/sequential Bet v 1 epitopes is not inhibited by folded Bet v 1 and hence the latter seem to represent cryptic epitopes. IgG reactivity to Bet v 1 peptides did not correlate with IgG reactivity to the corresponding Mal d 1 peptides and therefore does not seem to be a result of primary sensitization to PR10 allergen-containing food. Natural Bet v 1-specific IgG antibodies inhibited IgE binding to Bet v 1 only poorly and could even enhance Bet v 1-specific basophil activation.

CONCLUSION

IgE and IgG antibodies from BPA patients and birch pollen-exposed non-sensitized subjects recognize different epitopes. These findings explain why natural allergen-specific IgG do not protect against allergic symptoms and suggest that allergen-specific IgE and IgG have different clonal origin.

Effects of allergen immunotherapy on follicular regulatory T cells

PURPOSE OF REVIEW

Emerging evidence indicating that the dysfunction of T follicular regulatory (T FR ) cells contributes to excessive immunoglobulin E (IgE) production and the development of allergic diseases. Conversely, allergen immunotherapy (AIT) modulates T FR cells abundance and function to promote immune tolerance. This review focus on the role of T FR cells in allergic diseases and AIT, with the objective of providing novel insights into the mechanisms underlying immune tolerance of AIT and proposing the potential targeting of T FR cells in the context of allergic diseases.

RECENT FINDINGS

Numerous studies have consistently demonstrated that T FR cells play a pivotal role in the inhibition of class switch recombination to IgE in both humans and specific murine models. This suppression is attributed to the actions of neuritin and IL-10 secreted by T FR cells, which exert direct and indirect effects on B cells. In patients with allergic rhinitis, reduced frequencies of circulating or tonsillar T FR cells have been reported, along with impaired functionality in suppressing IgE production. AIT, whether administered subcutaneously or sublingually, reinstates the frequency and functionality of T FR cells in allergic rhinitis patients, accompanied by changes of the chromatin accessibility of T FR cells. The increase in T FR cell frequency following AIT is associated with the amelioration of clinical symptoms.

SUMMARY

T FR cells exert an inhibitory effect on IgE production and demonstrate a correlation with the clinical efficacy of AIT in patients with allergic rhinitis, suggesting T FR cells hold promise as a therapeutic target for allergic diseases and potential biomarker for AIT.

Standardization of clinical outcomes used in allergen immunotherapy in allergic asthma: An EAACI position paper

INTRODUCTION

In allergic asthma patients, one of the more common phenotypes might benefit from allergen immunotherapy (AIT) as add-on intervention to pharmacological treatment. AIT is a treatment with disease-modifying modalities, the evidence for efficacy is based on controlled clinical trials following standardized endpoint measures. However, so far there is a lack of a consensus for asthma endpoints in AIT trials. The aim of a task force (TF) of the European Academy of Allergy and Clinical Immunology (EAACI) is evaluating several outcome measures for AIT in allergic asthma.

METHODS

The following domains of outcome measures in asthmatic patients have been evaluated for this position paper (PP): (i) exacerbation rate, (ii) lung function, (iii) ICS withdrawal, (iv) symptoms and rescue medication use, (v) questionnaires (PROMS), (vi) bronchial/nasal provocation, (vii) allergen exposure chambers (AEC) and (viii) biomarkers.

RESULTS

Exacerbation rate can be used as a reliable objective primary outcome; however, there is limited evidence due to different definitions of exacerbation. The time after ICS withdrawal to first exacerbation is considered a primary outcome measure. Besides, the advantages and disadvantages and clinical implications of further domains of asthma endpoints in AIT trials are elaborated in this PP.

CONCLUSION

This EAACI-PP aims to highlight important aspects of current asthma measures by critically evaluating their applicability for controlled trials of AIT.

Predicting the therapeutic efficacy of AIT for asthma using clinical characteristics, serum allergen detection metrics, and machine learning techniques

Bronchial asthma is a prevalent non-communicable disease among children. The study collected clinical data from 390 children aged 4-17 years with asthma, with or without rhinitis, who received allergen immunotherapy (AIT). Combining these data, this paper proposed a predictive framework for the efficacy of mite subcutaneous immunotherapy in asthma based on machine learning techniques. Introducing the dispersed foraging strategy into the Salp Swarm Algorithm (SSA), a new improved algorithm named DFSSA is proposed. This algorithm effectively alleviates the imbalance between search speed and traversal caused by the fixed partitioning pattern in traditional SSA. Utilizing the fusion of boosting algorithm and kernel extreme learning machine, an AIT performance prediction model was established. To further investigate the effectiveness of the DFSSA-KELM model, this study conducted an auxiliary diagnostic experiment using the immunotherapy predictive medical data collected by the hospital. The findings indicate that selected indicators, such as blood basophil count, sIgE/tIgE (Der p) and sIgE/tIgE (Der f), play a crucial role in predicting treatment outcome. The classification results showed an accuracy of 87.18% and a sensitivity of 93.55%, indicating that the prediction model is an effective and accurate intelligent tool for evaluating the efficacy of AIT.

KAAACI Guidelines for Allergen Immunotherapy

Allergen immunotherapy (AIT) is a causative treatment for various allergic diseases such as allergic rhinitis, allergic asthma, and bee venom allergy that induces tolerance to offending allergens. The need for uniform practice guidelines in AIT is continuously growing because of the increasing discovery of potential candidates for AIT and evolving interest in new therapeutic approaches. This guideline is an updated version of the Korean Academy of Asthma Allergy and Clinical Immunology recommendations for AIT published in 2010. This updated guideline proposes an expert opinion by allergy, pediatrics, and otorhinolaryngology specialists with an extensive literature review. The guideline deals with basic knowledge and methodological aspects of AIT, including mechanisms, clinical efficacy, patient selection, allergens extract selection, schedule and doses, management of adverse reactions, efficacy measurements, and special consideration in pediatrics. The guidelines for sublingual immunotherapy will be covered in detail in a separate article.

B cells: The many facets of B cells in allergic diseases

B cells play a key role in our immune system through their ability to produce antibodies, suppress a proinflammatory state, and contribute to central immune tolerance. We aim to provide an in-depth knowledge of the molecular biology of B cells, including their origin, developmental process, types and subsets, and functions. In allergic diseases, B cells are well known to induce and maintain immune tolerance through the production of suppressor cytokines such as IL-10. Similarly, B cells protect against viral infections such as severe acute respiratory syndrome coronavirus 2 that caused the recent coronavirus disease 2019 pandemic. Considering the unique and multifaceted functions of B cells, we hereby provide a comprehensive overview of the current knowledge of B-cell biology and its clinical applications in allergic diseases, organ transplantation, and cancer.

Validation of AI-based software for objectification of conjunctival provocation test

Background

Provocation tests are widely used in allergology to objectively reveal patients' sensitivity to specific allergens. The objective quantification of an allergic reaction is a crucial characteristic of these tests. Because of the absence of objective quantitative measurements, the conjunctival provocation test (CPT) is a less frequently used method despite its sensitivity and simplicity.

Objective

We developed a new artificial intelligence (AI)-based method, called AllergoEye, for quantitative evaluation of conjunctival allergic reactions and validated it in a clinical study.

Methods

AllergoEye was implemented as a 2-component system. The first component is based on an Android smartphone camera for screening and imaging the patient's eye, and the second is personal computer-based for image analysis and quantification. For the validation of AllergoEye, an open-label, prospective, monocentric study was carried out on 41 patients. Standardized CPT was performed with sequential titration of grass allergens in 4 dilutions, with the reaction evaluated by subjective/qualitative symptom scores and by quantitative AllergoEye scores.

Results

AllergoEye demonstrated high sensitivity (98%) and specificity (90%) as compared with human estimation of allergic reaction. Tuning cutoff thresholds allowed us to increase the specificity of AllergoEye to 97%, at which point the correlation between detected sensitivity to allergen and specific IgE carrier-polymer system class becomes obvious. Strikingly, such correlation was not found with sensitivity to allergen detected on the basis of subjective and qualitative symptom scores.

Conclusion

The clinical validation demonstrated that AllergoEye is a sensitive and efficient instrument for objective measurement of allergic reactions in CPT for clinical studies as well as for routine therapy control.

The early-phase transcriptome and the clinical efficacy analysis in three modes of subcutaneous immunotherapy for allergic rhinitis

Background

Allergen immunotherapy is the only etiological treatment for allergic rhinitis.

Objective

To analyze the efficacy, safety, and mechanism of subcutaneous immunotherapy (SCIT).

Methods

The efficacy, safety, and serum immunological changes of 3 modes of subcutaneous immunotherapy were compared. Peripheral blood mononuclear cells (PBMC) transcriptome changes were obtained on the Illumina sequencing platforms. We confirmed differentially expressed genes (DEGs) by quantitative real-time polymerase chain reaction (PCR). The DEGs were analyzed by gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-protein interaction (PPI) networks. The correlation between the common DEGs and clinical indicators was analyzed by Origin 2022.

Results

The 3 SCITs were all effective after 1 year. The Combined Symptom and Medication Score (CSMS) and Visual Analog Score (VAS) in rush immunotherapy (RIT) are lowest after 24 and 48 weeks of treatment among the 3 groups. After treatment, the levels of sIgE, sIgE/tIgE, Th2 cytokines, Th17 cytokines, and percentage of peripheral eosinophils (EOS%) decreased significantly (P＜0.05), while the levels of Th1 type cytokines did not change significantly. Transcriptome analysis identified 24, 24, and 91 DEGs at W3 and 42, 52, 175 DEGs at W7 in conventional immunotherapy (CIT), cluster immunotherapy (CLIT), and RIT groups, respectively. The pathways and functions involved in SCIT include secretion of Th1/2 cytokines, immune cell differentiation. Unlike CIT and CLIT, DEGs are also involved in T cell tolerance induction, T cell anergy, and lymphocyte anergy in RIT. CXCR1, CXCR2, and IER3 had a specific effect on reflecting the improvement of symptoms in allergic rhinitis patients with SCIT.

Conclusion

The clinical efficacy of RIT appeared earlier than CIT and CLIT. Clinicians can use the highly conserved gene expression profile to evaluate responses to immunotherapy.

Potential Effects of AIT on Nonspecific Allergic Immune Responses or Symptoms

Allergen immunotherapy (AIT) is a treatment in which clinically corresponding allergens are administered to patients with allergic diseases, either by subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT), or by oral immunotherapy (OIT) in the case of food allergy. Since etiological allergens are administered to patients, AIT is presumed to modify mainly allergen-specific immune responses. In bronchial asthma, AIT with house dust mites (HDM) alleviates clinical symptoms, suppresses airway hyperresponsiveness, and reduces medication doses of HDM-sensitive asthmatics. Moreover, AIT can suppress the symptoms of other allergic diseases associated with asthma including allergic rhinitis. However, AIT sometimes reduces allergic symptoms not induced by the responsible allergens, such as non-targeted allergens, in clinical settings. Furthermore, AIT can suppress the spread of sensitization to new allergens that are not targeted allergens by AIT, suggesting the suppression of allergic immune responses in an allergen-nonspecific manner. In this review, the nonspecific suppression of allergic immune responses by AIT is discussed. AIT has been reported to increase regulatory T cells that produce IL-10, transforming growth factor-β, and IL-35, IL-10-producing regulatory B cells, and IL-10-producing innate lymphoid cells. These cells can suppress type-2 mediated immune responses mainly through the production of anti-inflammatory cytokines or a cell-cell contact mechanism, which may be involved in the nonspecific suppression of allergic immune responses by AIT.

Mechanisms of Allergen Immunotherapy and Potential Biomarkers for Clinical Evaluation

Allergen-immunotherapy (AIT) is an efficacious and disease-modifying treatment option for IgE-mediated diseases. Among these allergic rhinitis, insect venom allergy, food allergy, and allergic asthma are the most common candidates for AIT. AIT gives rise to clinical immunotolerance which may last for years after the treatment cessation. Mechanisms of AIT include suppression of allergic inflammation in target tissues and stimulation of the production of blocking antibodies, especially IgG4 and IgA. These mechanisms are followed by a reduction of underlying allergen-specific Th2 cell-driven responses to the allergens. Tolerance induction takes place through the desensitization of effector cells and stimulation of regulatory T cells that show their effects by mechanisms involving cell-cell cross-talk, but also other mechanisms, e.g., by the production of immunomodulatory cytokines such as, e.g., IL-10 and TGF-beta. From a personalized medical perspective, there is a need for clinical biomarkers of value in selecting responders and optimizing patient care during AIT. Also, a deeper understanding of underlying mechanistic processes will improve AIT's future outcomes. In this paper, the current knowledge of mechanisms in AIT is reviewed with a special focus on biomarkers of this therapy.

Comparison of allergen immunotherapy practice patterns in inhalant allergies in the United States of America and Europe: Similarities and differences 2023

IgE-mediated atopic diseases such as allergic rhinitis and rhinoconjunctivitis are common chronic diseases in the western world. Allergen immunotherapy (AIT) plays a fundamental role in the treatment of allergic patients by modulating the underlying immune mechanisms. Though this treatment is integrated in practice-patterns globally, many differences are found in the application of AIT on the national or international level due to heterogeneous methods, and clinical recommendations are given in different parts of the world. This review from authors in Europe and the United States highlights differences and similarities in important aspects of AIT application in the 2 global regions. First, the regulatory situation differs regarding marketing authorization and licensing. Secondly, differences are elaborated in manufacturing practices, marketing distribution and formulations of AIT products. Thirdly, clinical administration patterns in the current guidelines show similarities in indications and contraindications of AIT, but also are divergent in some practical aspects. Informing the readership on similarities, as well as differences of standards in AIT in the United States and Europe, the authors highlight the unmet need of thorough harmonization of standards of AIT, as it is the only disease modifying treatment option available for patients with allergic rhinitis and rhinoconjunctivitis.

Allergen immunotherapy: progress and future outlook

INTRODUCTION

Allergy, the immunological hypersensitivity to innocuous environmental compounds, is a global health problem. The disease triggers, allergens, are mostly proteins contained in various natural sources such as plant pollen, animal dander, dust mites, foods, fungi and insect venoms. Allergies can manifest with a wide range of symptoms in various organs, and be anything from just tedious to life-threatening. A majority of all allergy patients are self-treated with symptom-relieving medicines, while allergen immunotherapy (AIT) is the only causative treatment option.

AREAS COVERED

This review will aim to give an overview of the state-of-the-art allergy management, including the use of new biologics and the application of biomarkers, and a special emphasis and discussion on current research trends in the field of AIT.

EXPERT OPINION

Conventional AIT has proven effective, but the years-long treatment compromises patient compliance. Moreover, AIT is typically not offered in food allergy. Hence, there is a need for new, effective and safe AIT methods. Novel routes of administration (e.g. oral and intralymphatic), hypoallergenic AIT products and more effective adjuvants holds great promise. Most recently, the development of allergen-specific monoclonal antibodies for passive immunotherapy may also allow treatment of patients currently not treated or treatable.

Clinical and experimental treatment of allergic asthma with an emphasis on allergen immunotherapy and its mechanisms

Allergen immunotherapy (AIT) is currently the only form of treatment that modifies allergic asthma. Pharmacotherapy alone seeks to control the symptoms of allergic asthma, allergic rhinitis, and other atopic conditions. In contrast, AIT can induce long-term physiological modifications through the immune system. AIT enables individuals to live improved lives many years after treatment ends, where they are desensitized to the allergen(s) used or no longer have significant allergic reactions upon allergen provocation. The leading forms of treatment with AIT involve injections of allergen extracts with increasing doses via the subcutaneous route or drops/tablets via the sublingual route for several years. Since the initial attempts at this treatment as early as 1911 by Leonard Noon, the mechanisms by which AIT operates remain unclear. This literature-based review provides the primary care practitioner with a current understanding of the mechanisms of AIT, including its treatment safety, protocols, and long-term efficacy. The primary mechanisms underlying AIT include changes in immunoglobulin classes (IgA, IgE, and IgG), immunosuppressive regulatory T-cell induction, helper T cell type 2 to helper T cell type 1 cell/cytokine profile shifts, decreased early-phase reaction activity and mediators, and increased production of IL-10, IL-35, TGF-β, and IFN-γ. Using the databases PubMed and Embase, a selective literature search was conducted searching for English, full-text, reviews published between 2015 and 2022 using the keywords (with wildcards) "allerg*," "immunotherap*," "mechanis*," and "asthma." Among the cited references, additional references were identified using a manual search.

T-helper-2 cells and atopic disease: lessons learnt from inborn errors of immunity

Inborn errors of immunity (IEI) are caused by monogenic variants that affect the host response to bacterial, viral, and fungal pathogens. As such, individuals with IEI often present with severe, recurrent, and life-threatening infections. However, the spectrum of disease due to IEI is very broad and extends to include autoimmunity, malignancy, and atopic diseases such as eczema, atopic dermatitis, and food and environmental allergies. Here, I review IEI that affect cytokine signaling pathways that dysregulate CD4⁺ T-cell differentiation, resulting in increased T-helper-2 (Th2) cell development, function, and pathogenicity. These are elegant examples of how rare IEI can provide unique insights into more common pathologies such as allergic disease that are impacting the general population at increased frequency.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Long-term effects of ciclosporin and oclacitinib on mediators of tolerance, regulatory T-cells, IL-10 and TGF-β, in dogs with atopic dermatitis

BACKGROUND

Atopic dogs often are managed with allergen-specific immunotherapy (AIT) and concurrent dosages of ciclosporin (CSA) or oclacitinib to alleviate their clinical signs. Both drugs might affect proper tolerance induction by inhibiting regulatory T-cell (Treg) induction.

HYPOTHESIS/OBJECTIVES

We evaluated Treg cell numbers and serum interleukin (IL)-10 and transforming growth factor-beta (TGF-β)1 levels in dogs diagnosed with atopic dermatitis (AD) and successfully treated with either CSA or oclacitinib for nine or more months.

ANIMALS

We included 15 dogs receiving oclacitinib, 14 dogs treated with CSA, 15 healthy dogs, 13 dogs with untreated moderate-to-severe AD and 15 atopic dogs controlled with AIT.

MATERIALS AND METHODS

Peripheral blood CD4+CD25+FOXP3+ T-cell percentages were determined using flow cytometry. Serum concentrations of IL-10 and TGF-β1 were measured by enzyme-linked immunosorbent assay.

RESULTS

The percentage of Treg cells in the CSA group was significantly lower in comparison with the healthy group (p = 0.0003), the nontreated AD group (p = 0.0056) or the AIT group (p = 0.0186). There was no significant difference in Treg cell percentages between the CSA and oclacitinib groups, nor between the oclacitinib and the healthy, nontreated AD or AIT-treated dogs. No significant differences were detected in IL-10 and TGF-β1 serum concentrations between the five groups.

CONCLUSIONS AND CLINICAL RELEVANCE

Lower Treg cell percentages in the CSA-treated dogs suggest an impact of this drug on this cell population; however, it does not necessarily mean that it diminishes tolerance. Functionality and cytokine production may be more important than the number of Treg cells. Further studies evaluating the treatment outcome of dogs receiving AIT and concurrent drugs are needed to show clinical relevance.

Multimorbidity of Allergic Conditions in Urban Citizens of Southern China: A Real-World Cross-Sectional Study

Background: Extensive knowledge of allergic multimorbidities is required to improve the management of allergic diseases with the industrialization of China. However, the demography and allergen distribution patterns of allergic multimorbidities in China remain unclear, despite the increasing prevalence of allergies. Methods: This was a real-world, cross-sectional study of 1273 outpatients diagnosed with one or more allergic diseases in Guangzhou, the most populated city of southern China, with leading industrial and commercial centers, between April 2021 and March 2022. Seven allergic diseases (allergic rhinitis (AR), asthma (AS)/cough variant asthma (CVA), atopic dermatitis (AD)/eczema, food allergy (FA), allergic conjunctivitis (AC), drug allergy (DA), and anaphylaxis) were assessed. Positive rates of sensitization to different allergens were measured using an allergen detection system of the UniCAP (Pharmacia Diagnostics, Sweden) instrument platform to compare the groups of allergic multimorbidities against a single entity. Results: There were 659 (51.8%) males and 614 (48.2%) females aged from 4 months to 74 years included in the analysis. The study participants who were diagnosed with allergic diseases had an average of 1.6 diagnoses. Overall, 46.5% (592 of 1273) of the patients had more than one allergic condition, and allergic rhinitis was the most common type of multimorbidity. Women were more likely to suffer from an allergic disease alone, whereas allergic multimorbidities were more likely to be diagnosed in men (p = 0.005). In addition, allergic multimorbidities were common in all age groups, with an incidence ranging from 37.1% to 57.4%, in which children and adolescents were more frequently diagnosed with allergic multimorbidities than adults (18–60 years old) (all p < 0.05). Allergic multimorbidity was observed throughout the year. A difference in the positive rate of allergens sensitization and total immunoglobulin E (tIgE) levels between different allergic multimorbidities was observed. Conclusions: Allergic multimorbidities were very commonly found in nearly half of all patients with allergies. The proportion of allergic multimorbidities varied with the type of disease, sex, age, and allergen distribution pattern. These findings may help clinicians to develop “One health” strategies for the clinical management of allergic diseases.

Dissection of Antibody Responses of Gam-COVID-Vac-Vaccinated Subjects Suggests Involvement of Epitopes Outside RBD in SARS-CoV-2 Neutralization

Millions of people have been vaccinated with Gam-COVID-Vac but fine specificities of induced antibodies have not been fully studied. Plasma from 12 naïve and 10 coronavirus disease 2019 (COVID-19) convalescent subjects was obtained before and after two immunizations with Gam-COVID-Vac. Antibody reactivity in the plasma samples (n = 44) was studied on a panel of micro-arrayed recombinant folded and unfolded severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins and 46 peptides spanning the spike protein (S) and by immunoglobulin G (IgG) subclass enzyme-linked immunosorbent assay (ELISA). The ability of Gam-COVID-Vac-induced antibodies to inhibit binding of the receptor-binding domain (RBD) to its receptor angiotensin converting enzyme 2 (ACE2) was investigated in a molecular interaction assay (MIA). The virus-neutralizing capacity of antibodies was studied by the pseudo-typed virus neutralization test (pVNT) for Wuhan-Hu-1 and Omicron. We found that Gam-COVID-Vac vaccination induced significant increases of IgG1 but not of other IgG subclasses against folded S, spike protein subunit 1 (S1), spike protein subunit 2 (S2), and RBD in a comparable manner in naïve and convalescent subjects. Virus neutralization was highly correlated with vaccination-induced antibodies specific for folded RBD and a novel peptide (i.e., peptide 12). Peptide 12 was located close to RBD in the N-terminal part of S1 and may potentially be involved in the transition of the pre- to post-fusion conformation of the spike protein. In summary, Gam-COVID-Vac vaccination induced S-specific IgG1 antibodies in naive and convalescent subjects in a comparable manner. Besides the antibodies specific for RBD, the antibodies induced against a peptide close to the N-terminus of RBD were also associated with virus-neutralization.

Current advances in house dust mite allergen immunotherapy (AIT): Routes of administration, biomarkers and molecular allergen profiling

Allergy to house dust mites (HDM) is a perennial respiratory disease that affect more than half a billion people worldwide. Dermatophagoides pteronyssinus and D. farinae, two HDM species, are major sources of indoor allergens triggering allergic inflammation. Although symptomatic drugs are widely used to block the allergic reaction, allergen immunotherapy is the only curative treatment of IgE-mediated type I respiratory allergies. In this article, we review recent advances in various routes of allergen immunotherapy. We particularly focus on subcutaneous (SCIT) and sublingual (SLIT) immunotherapy, used as a reference therapy since they have transformed allergic treatments by improving symptoms (asthma and rhinitis) as well as the quality of life of patients. We also highlight recent data in more exploratory routes (i.e., oral, intralymphatic, epicutaneous and intradermal) and discuss respective advantages of various route, as well as their foreseen modes of action. Finally, we provide an update on biomarkers as well as on the relevance of the molecular profiling of allergic individuals related to treatment efficacy or asthma prediction.

Serum exosomal miR-146a-3p associates with disease severity and efficacy of sublingual immunotherapy in allergic rhinitis

BACKGROUND

Sublingual immunotherapy (SLIT) is an effective treatment for allergic rhinitis (AR), but its efficacy is variable among individuals. This study aimed to characterize serum exosome-derived microRNAs (miRNAs) and evaluate their abilities in predicting the efficacy of SLIT in AR.

METHODS

RNA sequencing was performed to explore differentially expressed exosomal miRNAs in serum exosomes between AR patients and healthy controls (HCs). Sequencing analysis results were verified in an independent cohort, and the correlations between the levels of exosome-derived miRNAs and disease severity were evaluated. The most promising miRNAs were further tested in two AR cohorts treated with SLIT to assess their abilities in predicting short and long-term efficacy, respectively.

RESULTS

The exosome-derived miRNAs profiling in the AR group was significantly different from the HC group, and differentially expressed genes were enriched and clustered in pathways such as PI3K-Akt and ErbB signalling pathways. The top three most significant miRNAs were verified by reverse transcription-polymerase chain reaction (qRT-PCR), and results showed that miR-146a-3p levels were significantly elevated in the AR group and correlated with the total and specific gE levels, the visual analogue scale of the total nasal symptom score (all p < 0.05). Further data in the first validation cohort suggested that miR-146a-3p levels were significantly downregulated in the effective group, and logistic regression showed that miR-146a-3p levels were associated with the short-term efficacy of SLIT(p < 0.05). The receiver operating characteristic (ROC) curve showed that miR-146a-3p could early predict SLIT efficacy (AUC = 0.669, p = 0.047). In the second validation cohort, miR-146a-3p levels were also decreased in the effective group and the ROC curve further confirmed its reliable accuracy in predicting the long-term efficacy of SLIT in AR patients (AUC = 0.749, p < 0.001).

CONCLUSION

Serum exosome-derived miRNAs may be involved in the development of AR and associated with its disease severity. Serum exosome-derived miR-146a-3p seems to be a novel biomarker for predicting the short and long-term efficacies of SLIT in AR patients.

EAACI Molecular Allergology User's Guide 2.0

Since the discovery of immunoglobulin E (IgE) as a mediator of allergic diseases in 1967, our knowledge about the immunological mechanisms of IgE-mediated allergies has remarkably increased. In addition to understanding the immune response and clinical symptoms, allergy diagnosis and management depend strongly on the precise identification of the elicitors of the IgE-mediated allergic reaction. In the past four decades, innovations in bioscience and technology have facilitated the identification and production of well-defined, highly pure molecules for component-resolved diagnosis (CRD), allowing a personalized diagnosis and management of the allergic disease for individual patients. The first edition of the "EAACI Molecular Allergology User's Guide" (MAUG) in 2016 rapidly became a key reference for clinicians, scientists, and interested readers with a background in allergology, immunology, biology, and medicine. Nevertheless, the field of molecular allergology is moving fast, and after 6 years, a new EAACI Taskforce was established to provide an updated document. The Molecular Allergology User's Guide 2.0 summarizes state-of-the-art information on allergen molecules, their clinical relevance, and their application in diagnostic algorithms for clinical practice. It is designed for both, clinicians and scientists, guiding health care professionals through the overwhelming list of different allergen molecules available for testing. Further, it provides diagnostic algorithms on the clinical relevance of allergenic molecules and gives an overview of their biology, the basic mechanisms of test formats, and the application of tests to measure allergen exposure.

Relationship between Food Allergy and Endotoxin Concentration and the Toleration Status at 2 Years: The Japan Environment and Children's Study

Changes in household endotoxin concentration may affect the prognosis of food allergy (FA), but data on the association between household endotoxin concentration and an already-developed FA are scarce. Thus, we investigated the association between environmental endotoxin exposure and tolerance to hen's egg (HE) and cow's milk (CM) using data from children participating in the Japan Environment and Children's Study who had HE allergies (n = 204) and CM allergy (n = 72) in their first year of life. We grouped the endotoxin results into quartiles 1-4 (Q1-Q4). In children with HE allergy and with CM allergy, there was no significant difference in the prevalence of tolerance to HE and CM at 2 years old when comparing endotoxin levels of the children in Q1 with those in Q2, Q3, and Q4, respectively. However, subgroup analyses by the presence of eczema and causal foods revealed that children in Q1 had a lower prevalence of tolerance to foods in some subgroup analyses and lower causal allergen-specific immunoglobulin G4 levels. Although an individually based approach against endotoxin according to background characteristics, such as eczema and causal foods, is necessary, preventing excessive endotoxin removal might contribute to FA resolution in some children.

Deciphering Differential Behavior of Immune Responses as the Foundation for Precision Dosing in Allergen Immunotherapy

Like in many fields of medicine, the concept of precision dosing has re-emerged in routine practice in allergology. Only one retrospective study on French physicians' practice has addressed this topic so far and generated preliminary data supporting dose adaptation, mainly based on experience, patient profile understanding and response to treatment. Both intrinsic and extrinsic factors shape the individual immune system response to allergen immunotherapy (AIT). Herein, we focus on key immune cells (i.e., dendritic cells, innate lymphoid cells, B and T cells, basophils and mast cells) involved in allergic disease and its resolution to further understand the effect of AIT on the phenotype, frequency or polarization of these cells. We strive to discriminate differences in immune responses between responders and non-responders to AIT, and discuss the eligibility of a non/low-responder subset for dose adaptation. A differential behavior in immune cells is clearly observed in responders, highlighting the importance of conducting clinical trials with large cohorts of well-characterized subjects to decipher the immune mechanism of AIT. We conclude that there is a need for designing new clinical and mechanistic studies to support the scientific rationale of dose adaptation in the interest of patients who do not properly respond to AIT.

Lack of Harmonized Adherence Criteria in Allergen Immunotherapy Prevents Comparison of Dosing and Application Strategies: A Scoping Review

Allergen immunotherapy (AIT) involves the application of increasing doses of allergen extract (as oral, sublingual, or subcutaneous immunotherapy) until immunologic tolerance is reached. Successful AIT relies on the consistent administration of allergen extract; therefore, adherence to these treatments is vital for compelling long-term results. Our review discusses the current terminology from adherence research in general, summarizes 25 current studies on adherence research in AIT in a scoping literature review, and delineates recommendations for tools and parameters for adherence research, aiming to improve outcomes in AIT. Almost every adherence study in AIT published to date used different tools, parameters, and data sources for measuring adherence and persistence rates. Unfortunately, an easily accessible, objective parameter or biomarker for monitoring treatment adherence and success has not yet been established for AIT. This situation calls for the development of an international core outcomes set for AIT that defines what is exactly meant by AIT adherence and how AIT adherence should be consistently measured. Therefore, we exemplarily present results and conclusions from adherence research in chronic diseases other than allergology. We aim to facilitate the development of advanced methods, considering the challenging disease specificities of these parameters in a routine care setting of AIT.

Molecular Aspects of Allergen-Specific Immunotherapy in Patients with Seasonal Allergic Rhinitis

A systematic review and narrative synthesis of publications was undertaken to analyze the role of component-resolved diagnosis technology in identifying polysensitization for the provision of allergen-specific immunotherapy to patients with seasonal allergic rhinitis. A search of publications was carried out in electronic databases in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search helped to identify 568 publications, 12 of which were included in this review. Overall, 3302 patients were enrolled. The major finding was that component-resolved diagnostics change the choice of relevant allergens for allergen-specific immunotherapy in at least 50% of cases. Sensitization to allergen components differs with age, type of disease, and overall disease duration. Patients who had both bronchial asthma and allergic rhinitis were sensitized to a larger number of allergens than patients who had bronchial asthma alone.

Monitoring of molecular profiling of allergen-antibody responses in HDM-immunotherapy patients

Among the potential hazards of HDM immunotherapy (AIT) with HDM allergenic extracts is the possible initiation of de novosensitizations caused by a lack of complementarity between a given HDM vaccine's content and a patient's molecular sensitization profile. To investigate whether immunotherapy with HDM extracts affects changes in the profile of sensitizations to allergens contained in the extract and whether neosensitizations occur. Serum samples from patients with HDM allergies (N=63) who received 1 year of treatment with subcutaneous AIT were tested for allergen-specific IgE (sIgE) reactivity to 7 microarrayed HDM allergen molecules (Der p 1, 2,10,11,23; D far 1 and 2) with ImmunoCAP. The HDM non-AIT patients (N=22) who did not receive immunotherapy constituted the study's control group. The obtained data were analysed at baseline and after 6 and 12 months. In the HDM-AIT group, no neosensitizations after 6 and 12 months of immunotherapy were reported. Conversely, in the HDM non-AIT group, only neosensitizations to Der p 10 were observed. In the study group, sIgE levels against the HDM extract of D. pteronyssinus, D. farinae, rDer p 1, rDer p 2 and Der f 2 decreased after 12 months of AIT (p< .05). SIgE levels against Der f 1, Der p 10, 11 and 23 remained unchanged in the course of 12 months of immunotherapy. In patients with allergic rhinitis with or without concomitant HDM-induced asthma treated with HDM AIT for 12 months, no neosensitizations related to the examined HDM molecules were observed.

Immunogenicity of a novel anti-allergic vaccine based on house dust mite purified allergens and a combination adjuvant in a murine prophylactic model

The outer-membrane-derived proteoliposome (PL) of Neisseria meningitidis has been reported as a potent vaccine adjuvant, inducing a Th1-skewed response. This work aimed to assess the immunogenicity of a novel anti-allergic vaccine candidate based on allergens from Dermatophagoides siboney house dust mite and a combination adjuvant containing PL and Alum. In a preventative experimental setting, BALB/c mice were administered with three doses containing 2 µg of Der s1 and 0.4 µg Der s2 allergen, PL and Alum, at 7 days intervals, by subcutaneous route. Furthermore, mice were subjected to an allergen aerosol challenge for 6 consecutive days. Serum IgE, IgG1, and IgG2a allergen-specific antibodies were assessed by ELISA. Cytokine levels in supernatants of D. siboney stimulated lymphocyte cultures and in bronchoalveolar lavage (BAL) were measured by ELISA. Lung tissues were subjected to histological examination. The vaccine prevented the development of both, systemic (IgE) and local allergic responses (featuring lower IL-4, and IL-5 levels in BAL) upon allergen exposure by the inhalant route. Histological examination showed also a diminished allergic inflammatory response in the lungs. After the allergen challenge, cytokine levels in stimulated lymphocyte cultures showed lower values of IL-13 and augmented IFN-γ and IL-10. The vaccine induced a mixed IgG2a/IgG1 antibody response; although only IgG2a was PL-dependent. Both, IgG1/IgE and IgG2a/IgE ratios, showed significantly greater values in vaccinated mice. The findings support a preventative anti-allergic effect associated with the induction of a Th1-like IFN-γ/IL-10 response. IgG1/IgE and IgG2a/IgE ratios could be useful biomarkers for translation into clinical trials.

Complement Factor H Is an Early Predictive Biomarker of the Therapeutic Efficacy of Sublingual Immunotherapy for Japanese Cedar Pollinosis

Sublingual immunotherapy for Japanese cedar pollinosis can improve the symptoms of allergic rhinitis and modify its natural course. However, sublingual immunotherapy requires a long treatment period and some patients do not respond to treatment. In this study, we aimed to identify biomarkers that could predict the efficacy of sublingual immunotherapy at an early stage. In this study, 40 patients from phase III trials were recruited and divided into good and poor response groups. Using peripheral blood mononuclear cells from before and two months after the start of medication, microarray, discriminant analysis, and real-time polymerase chain reaction were performed to extract candidate genes that could be biomarkers. Furthermore, these genes were validated in 30 patients in general clinical practice. Complement factor H was upregulated in the good response group and downregulated in the poor response group. Complement factor H may be a useful biomarker for predicting the efficacy of sublingual immunotherapy for Japanese cedar pollinosis at early time points after treatment initiation.

Chinese Guideline on Allergen Immunotherapy for Allergic Rhinitis: The 2022 Update

In the last few decades, there has been a progressive increase in the prevalence of allergic rhinitis (AR) in China, where it now affects approximately 250 million people. AR prevention and treatment include allergen avoidance, pharmacotherapy, allergen immunotherapy (AIT), and patient education, among which AIT is the only curative intervention. AIT targets the disease etiology and may potentially modify the immune system as well as induce allergen-specific immune tolerance in patients with AR. In 2017, a team of experts from the Chinese Society of Allergy (CSA) and the Chinese Allergic Rhinitis Collaborative Research Group (C2AR2G) produced the first English version of Chinese AIT guidelines for AR. Since then, there has been considerable progress in basic research of and clinical practice for AIT, especially regarding the role of follicular regulatory T (TFR) cells in the pathogenesis of AR and the use of allergen-specific immunoglobulin E (sIgE) in nasal secretions for the diagnosis of AR. Additionally, potential biomarkers, including TFR cells, sIgG4, and sIgE, have been used to monitor the incidence and progression of AR. Moreover, there has been a novel understanding of AIT during the coronavirus disease 2019 pandemic. Hence, there was an urgent need to update the AIT guideline for AR by a team of experts from CSA and C2AR2G. This document aims to serve as professional reference material on AIT for AR treatment in China, thus improving the development of AIT across the world.

Oral Tolerance Induction-Opportunities and Mechanisms

Oral tolerance is the active absence of response to food allergens, which involves complex mechanisms in the gut-associated lymphoid tissue. Food allergy results from the disruption of such tolerance or the absence of its establishment in the first place. It follows allergic sensitization with the production of allergen-specific IgE and results from the degranulation of basophils and mast cells on subsequent exposure to the allergen. Oral tolerance induction has been explored in the contexts of prevention and treatment of food allergy. Early introduction of allergenic foods (i.e., egg and peanut) in the diet of infants, before allergic sensitization occurs (i.e., via inflamed skin affected with eczema) has shown to be beneficial. Guidelines have changed to recommend the introduction of these allergenic foods by 6 months of age. For food allergic individuals, oral tolerance induction has been attempted using allergen-specific immunotherapy, which involves the administration of an allergen, modified or not, through various possible routes, including oral, sublingual, epicutaneous, and subcutaneous, with or without concomitant administration of antibody-based biologics. Further research into the immune mechanisms of food allergy and oral tolerance can lead to the identification of novel targets to suppress the food allergic response and reverse the current food allergy epidemic.

Subcutaneous birch pollen allergen immunotherapy with a depigmented polymerized extract shows only sustained and long-term efficacy in a subgroup of monosensitized adults and adolescents with allergic rhinitis

Background

Allergen immunotherapy (AIT) is an approved treatment for seasonal respiratory allergic diseases. A depigmented polymerized birch pollen extract for subcutaneous allergen immunotherapy (SCIT) has been demonstrated to be efficacious and safe in patients allergic to birch pollen and its homologous group.

Objective

To determine whether SCIT with a birch pollen formulation (5000 depigmented polymerized (DPP) units/mL) shows sustained and long‐term efficacy in adults and adolescents with birch‐pollen induced allergic rhinitis with or without intermittent asthma.

Methods

A multicentre (n = 66), double‐blind, placebo‐controlled Phase III clinical trial was performed in the Czech Republic, Finland, Germany, Latvia, Lithuania, Poland and Russia. Participants were randomized 2:1 to active treatment (birch 5000 DPP/ml) or placebo for three years of SCIT and followed up for two treatment‐free years. The primary efficacy endpoint was the EAACI's combined symptom and medication score for rhinoconjunctivitis (CSMS_EAACI).

Results

A total of 973 participants were screened and 649 were randomized (active treatment: n = 434; placebo: n = 215). The intention‐to‐treat analysis of the CSMS_EAACI in the overall study population did not demonstrate statistically significant differences in years 1, 2 and 3. In a post‐hoc analysis, among the subgroup of patients monosensitized to birch pollen allergen only (n = 200), we observed a statistically significant difference (active treatment vs. placebo) in the CSMS_EAACI in year 2, 3 and 5. The AIT's safety profile was good.

Conclusions

SCIT with a depigmented polymerized birch pollen extract was safe. Sustained and long‐term efficacy in years 2, 3 and 5 in monosensitized patients, but not in polysensitized patients was demonstrated.

(EudraCT 2012‐000414‐11)

Molecular reactivity profiling upon immunotherapy with a 300 IR sublingual house dust mite tablet reveals marked humoral changes towards major allergens

BACKGROUND

Molecular antibody reactivity profiles have not yet been studied in depth in patients treated by sublingual house dust mite (HDM) tablet immunotherapy. Humoral immune responses to a large panel of HDM mite allergens were studied using allergen microarray technology in a subset of clinically defined high and low responder patients from a double-blind placebo-controlled allergen-specific immunotherapy (AIT) trial using sublingual 300 IR HDM tablets.

METHODS

Serum levels of IgE, IgG and IgG₄ to 13 Dermatophagoides pteronyssinus molecules were measured at baseline and after 1-year AIT, using allergen microarrays in 100 subjects exhibiting high or low clinical benefit.

RESULTS

Der p 1, Der p 2 and Der p 23 were the most frequently recognized allergens in the study population. Patients with HDM-related asthma had significantly higher allergen-specific IgE levels to Der p 1 and Der p 23. No significant difference in the distribution of allergen sensitization pattern was observed between high and low responders. An increase in serum allergen-specific IgG and IgG₄ occurred upon AIT, in particular to allergens Der p 1, Der p 2 and Der p 23 (p < 0.0001).

CONCLUSIONS

We confirm for our study population that Der p 1- and Der p 23-specific IgE levels are associated with asthma. IgE reactivity profiles were not predicitive of sublingual AIT outcomes, with 300 IR tablets as efficacious in pauci- and multi-sensitized subjects. Our study is the first to demonstrate the induction of IgG and IgG₄  specific for the HDM allergens Der p 1, Der p 2 and Der p 23 by sublingual AIT.

Thermosensitive PLGA–PEG–PLGA Hydrogel as Depot Matrix for Allergen-Specific Immunotherapy

Allergen-specific immunotherapy (AIT) is the only currently available curative treatment option for allergic diseases. AIT often includes depot-forming and immunostimulatory adjuvants, to prolong allergen presentation and to improve therapeutic efficacy. The use of aluminium salts in AIT, which are commonly used as depot-forming adjuvants, is controversially discussed, due to health concerns and Th2-promoting activity. Therefore, there is the need for novel delivery systems in AIT with similar therapeutic efficacy compared to classical AIT strategies. In this study, a triblock copolymer (hydrogel) was assessed as a delivery system for AIT in a murine model of allergic asthma. We show that the hydrogel combines the advantages of both depot function and biodegradability at the same time. We further demonstrate the suitability of hydrogel to release different bioactive compounds in vitro and in vivo. AIT delivered with hydrogel reduces key parameters of allergic inflammation, such as inflammatory cell infiltration, mucus hypersecretion, and allergen-specific IgE, in a comparable manner to standard AIT treatment. Additionally, hydrogel-based AIT is superior in inducing allergen-specific IgG antibodies with potentially protective functions. Taken together, hydrogel represents a promising delivery system for AIT that is able to combine therapeutic allergen administration with the prolonged release of immunomodulators at the same time.

“In Litero” Screening: Retrospective Evaluation of Clinical Evidence to Establish a Reference List of Human Chemical Respiratory Sensitizers

Despite decades of investigation, test methods to identify respiratory sensitizers remain an unmet regulatory need. In order to support the evaluation of New Approach Methodologies in development, we sought to establish a reference set of low molecular weight respiratory sensitizers based on case reports of occupational asthma. In this context, we have developed an “in litero” approach to identify cases of low molecular weight chemical exposures leading to respiratory sensitization in clinical literature. We utilized the EPA-developed Abstract Sifter literature review tool to maximize the retrieval of publications relevant to respiratory effects in humans for each chemical in a list of chemicals suspected of inducing respiratory sensitization. The literature retrieved for each of these candidate chemicals was sifted to identify relevant case reports and studies, and then evaluated by applying defined selection criteria. Clinical diagnostic criteria were defined around exposure history, respiratory effects, and specific immune response to conclusively demonstrate occupational asthma as a result of sensitization, rather than irritation. This approach successfully identified 28 chemicals that can be considered as human respiratory sensitizers and used to evaluate the performance of NAMs as part of a weight of evidence approach to identify novel respiratory sensitizers. Further, these results have immediate implications for the development and refinement of predictive tools to distinguish between skin and respiratory sensitizers. A comparison of the protein binding mechanisms of our identified “in litero” clinical respiratory sensitizers shows that acylation is a prevalent protein binding mechanism, in contrast to Michael addition and Schiff base formation common to skin sensitizers. Overall, this approach provides an exemplary method to evaluate and apply human data as part of the weight of evidence when establishing reference chemical lists.

Mechanisms and biomarkers of subcutaneous immunotherapy and sublingual immunotherapy in allergen immunotherapy

There are currently no biomarkers that can accurately predict clinical outcomes and segregate responders from nonresponders in allergen immunotherapy (AIT). Therefore, identifying a reliable predictive biomarker is essential to enable clinicians to tailor personalized therapy. New developments in AIT biomarkers are currently being explored, and it would be important to identify key areas of development and their feasibility for use in the clinic. Biomarkers can be categorized broadly into seven domains: (i) Immunoglobulin E (IgE), (ii) IgG and IgA responses, (iii) IgE -facilitated allergen binding/blocking factor, (iv) basophil activation, (v) cytokines and chemokines, (vi) cellular markers, and (vii) in vivo biomarkers. Despite their potential, most biomarkers remain infeasible to be translated to the clinical setting due to requirements of complex instruments such as flow cytometry. The identification of suitable biomarkers remains key in predicting outcomes of AIT and requires more research. Additional exploration into integrative biomarkers may be required.