Effect of Epicutaneous Immunotherapy vs Placebo on Reaction to Peanut Protein Ingestion Among Children With Peanut Allergy: The PEPITES Randomized Clinical Trial

Peanut (Arachis hypogaea) allergen powder-dnfp for the mitigation of allergic reactions to peanuts in children and adolescents

INTRODUCTION

Peanut allergy can result in severe, sometimes fatal hypersensitivity reactions that place a considerable burden on the lives of patients. This article reviews the first approved immunotherapy for the mitigation of allergic reactions following accidental peanut exposure, peanut (Arachis hypogaea) allergen powder-dnfp (PTAH; Palforzia®, Aimmune Therapeutics).

AREAS COVERED

This article highlights the unmet need for patients with peanut allergy, describes the therapeutic landscape, and reviews the development of and clinical data for PTAH.

EXPERT OPINION

PTAH offers a standardized preparation of peanut allergen, with a tolerability and efficacy profile clearly defined through its robust clinical development and trial program. In children 4-17 years old, PTAH provides a standardized, approved product that many clinicians sought prior to initiating oral immunotherapy. PTAH reduced the likelihood of more severe reactions following exposure to peanut protein; although peanut avoidance remains essential, PTAH will enable more individuals with peanut allergy to participate in activities of daily life with less anxiety.

A Synopsis of Guidance for Allergic Rhinitis Diagnosis and Management From ICAR 2023

An updated edition of the International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR:AR) has recently been published. This consensus document, which included the participation of 87 primary authors and 40 additional consultant authors, who critically appraised evidence on 144 individual topics concerning allergic rhinitis, provides guidance for health care providers using the evidence-based review with recommendations (EBRR) methodology. This synopsis highlights topical areas including pathophysiology, epidemiology, disease burden, risk and protective factors, evaluation and diagnosis, aeroallergen avoidance and environmental controls, single and combination pharmacotherapy options, allergen immunotherapy (subcutaneous, sublingual, rush, cluster), pediatric considerations, alternative and emerging therapies, and unmet needs. Based on the EBRR methodology, ICAR:AR includes strong recommendations for the treatment of allergic rhinitis: (1) for the use of newer generation antihistamines compared with first-generation alternatives, intranasal corticosteroid, intranasal saline, combination therapy with intranasal corticosteroid plus intranasal antihistamine for patients not responding to monotherapy, and subcutaneous immunotherapy and sublingual tablet immunotherapy in properly selected patients; (2) against the use of oral decongestant monotherapy and routine use of oral corticosteroids.

Transitioning from epicutaneous to oral peanut immunotherapy

Introduction

Epicutaneous immunotherapy (EPIT) has been tested in clinical trials for children with peanut allergy (PA) for its safety and efficacy in inducing desensitization. Aside from peanut avoidance and symptom management, oral immunotherapy (OIT) is another option for PA patients. However, OIT can be associated with adverse events and pose safety concerns to children and their caregivers.

Methods

This study assessed 27 children who successfully completed a peanut EPIT trial. 18 of them transitioned to peanut OIT with starting doses ranging from 10-600 mg of peanut protein. Our aim was to learn more about the EPIT to OIT experience through descriptive survey responses and to gather information that may support the sequential use of the two immunotherapies for safe and positive outcomes that may not be achieved by either alone.

Results

Overall, children and their caregivers had less anxiety about starting OIT after having had peanut exposure through EPIT. Most children who transitioned from EPIT to OIT had no or minor symptoms initially, with symptoms lessening later in OIT. Most were also able to maintain or increase their peanut dose over time, achieving maintenance doses of 60-2,000 mg.

Discussion

In comparison with current literature on OIT for PA in children, the reported symptoms appeared less severe and less prevalent in the EPIT to OIT group. However, there were 3 participants who withdrew from OIT due to the development of intolerable symptoms. This study provides initial data in support of EPIT to OIT, and larger randomized controlled trials assessing effectiveness of the two therapies together are warranted.

Oral immunotherapy for food allergy: Translation from studies to clinical practice?

Oral immunotherapy (OIT) is now recognized as an alternative active treatment to strict food avoidance in certain patients with IgE-mediated food allergy. Studies have confirmed the efficacy of OIT to desensitize children with allergy to cow's milk, eggs, and peanuts. The benefits, risks, and constraints of OIT are becoming increasingly well understood. However, there is no consensual criteria to select patients to whom OIT could be proposed, and many issues remain to address including the definitions of desensitization and long-term efficacy, the assessment of patient's experience in real life, the optimization of buildup and maintenance protocols, and the utility of multiple food OIT. The recent authorization by medical agency concerning the first medicine for peanut OIT is a step forward towards higher standardization in the practice of OIT. This article summarizes in comprehensive narrative format data on efficacy, tolerance, impact on quality of life and adverse effects of OIT and discuss elements to consider in clinical practice before starting OIT.

Efficacy and safety of peanut epicutaneous immunotherapy in patients with atopic comorbidities

Background

Co-occurring atopic conditions are common in children with peanut allergy. As such, it is important to examine the safety and efficacy of epicutaneous immunotherapy with Viaskin Peanut 250 μg patch (VP250) in peanut-allergic children with these conditions.

Objective

We sought to compare efficacy and safety of VP250 versus placebo in peanut-allergic children with/without ongoing atopic conditions at baseline, including asthma, atopic dermatitis/eczema, or concomitant food allergy.

Methods

A subgroup analysis of peanut-allergic children aged 4 to 11 years enrolled in PEPITES (12 months) and REALISE (6 months) randomized, placebo-controlled, phase 3 trials was conducted. The efficacy outcome measure was the difference in prespecified responder rate between placebo and VP250 groups at month 12 based on eliciting dose of peanut protein using double-blind, placebo-controlled food challenge in PEPITES. Safety profiles were evaluated by baseline concomitant disease subgroup in all randomized subjects who received 1 or more dose of the study drug in PEPITES and REALISE pooled data.

Results

Responder rates were significantly (P < .05, all comparisons) greater with VP250 compared with placebo treatment regardless of whether subjects had other atopic conditions. Safety and tolerability profiles were generally similar across subgroups, with no new safety concerns detected. A trend for both higher responder rates and rates of local reactions was observed in subjects with baseline atopic dermatitis versus those without. In subjects with concomitant food allergy at baseline, higher rates of treatment-emergent adverse events, but not study discontinuations or overall rates of anaphylaxis, were observed.

Conclusions

The results support the safety and efficacy of VP250 for treating peanut-allergic children with or without concomitant atopic conditions.

Endpoints and Outcomes After Immunotherapy for Food Allergy: What Is Meaningful for Patients?

Multiple novel interventions for food allergy are currently at various stages of development with the goal of reducing or eliminating allergic reactions. However, the relative success of these therapeutics in achieving meaningful, long-term improvements to patients' lives is difficult to determine as there is currently very limited understanding of the degree of alignment between clinical trial efficacy endpoints and patient-centered outcomes. Furthermore, outcome measures used in clinical trials of food allergy immunotherapies vary widely, are often misinterpreted, and not necessarily consistent with what patients expect to achieve through treatment. This review aims to assist clinicians in critically interpreting outcomes reported in clinical trials and accurately communicating risks and outcomes to patients when practicing shared decision-making.

Treatment for food allergy: Current status and unmet needs

The treatment of food allergy has traditionally relied on avoidance of the offending food(s) and use of emergency medications in the event of accidental exposures. However, this long-standing paradigm is beginning to shift, as a variety of treatment approaches have been and are being developed. This report provides an overview of the past, present, and future landscape of interventional clinical trials for the treatment of food allergy. It focuses on specific issues related to participant characteristics, protocol design, and study end points in the key clinical trials in the literature and examine how differences between studies may impact the clinical significance of the study results. Recommendations are provided for the optimization of future trial designs and focus on specific unmet needs in this rapidly evolving field.

Current and future treatments for peanut allergy

Peanut allergy (PA) is a common, burdensome childhood disease that in most patients continues into adulthood and has historically been untreatable. However, peanut oral immunotherapy (POIT) is increasingly being incorporated into allergy practices, using both the first FDA-approved product, PTAH (previously AR101; Palforzia™, Aimmune Therapeutics), as well as store-bought peanut products. POIT in preschoolers continues to gain more acceptance as evidence accrues that it is a safe and feasible approach that may have distinct advantages. There are many new therapeutic interventions currently under study with a variety of different approaches and potential mechanisms. With respect to other forms of immunotherapy, none are currently approved, but the epicutaneous approach is the most well-studied and others are being actively investigated, including sublingual, subcutaneous, and intralymphatic. Biologics are gaining evidence both as adjunctive treatments to POIT and as monotherapy. Omalizumab is the most widely studied biologic for PA but others also have potential. Looking ahead to a future therapeutic landscape of choice, allergists will need to understand each patient's goal of treatment through shared decision-making and fully evaluate the risks, benefits, and alternatives of each new therapy.

Food Allergy and Eosinophilic Gastrointestinal Diseases-The Next 10 Years

The first report of food allergy desensitization was in 1908, at least a few years before the first published description of a diagnostic test for food allergy. It has taken almost 100 years for food allergy to move from passive management of avoidance to a more proactive approach including prevention and treatment. In parallel, this has been matched by recognition of eosinophil gastrointestinal diseases, which were first described in the 1980s (although eosinophilic esophagitis was itself described in 1978). As we celebrate 10 years of The Journal of Allergy and Clinical Immunology: In Practice, we take the opportunity to look into the future and speculate how our practice may develop over the next decade.

An overview of the current state of food desensitization

PURPOSE OF REVIEW

To highlight the current evidence on food desensitization in children with food allergy.

RECENT FINDINGS

Food Allergen Specific Immunotherapy (FA-AIT) is currently recognised as a treatment option for treating children with allergy at least to the main common foods (i.e. milk, egg and peanut). The oral route of administration has been proven to be the most effective in achieving desensitisation. Efforts are devoted to overcome the current unmet needs mainly related to safety issues and long-term efficacy, as well as adherence to the treatment and improvement of health-related quality of life. In this perspective, alternative routes of administration and adjunctive treatments are under investigation.

SUMMARY

The future of food allergy management is a personalised approach based on a shared decision-making that takes into account the needs of patients and families. Health professionals will be able to offer multiple treatment options, including FA-AIT with adjunctive or alternative therapies. Thus, patients should be correctly identified, using validated predictive factors, in order to select appropriate candidates for these therapies.

Information needs of patients considering oral immunotherapy for food allergy

While the historic management of food allergy includes avoidance strategies and allergic reaction treatment, oral immunotherapy (OIT) approaches have become more commonly integrated into therapeutic approaches. International guidelines, phase 3 trials and real-world experience have supported the implementation of this procedure. However, OIT is an elective, rarely curative procedure with inherent risks that necessitates an increased degree of health literacy for the patients and families. Families assume the responsibility of amateur healthcare providers to ensure the daily safe administration of the allergenic food. As such, it is incumbent upon physicians to ensure that families are prepared for this role. A thorough educational and shared decision-making approach is necessary during the counselling and consent process to adequately inform the families. Educated discussion about the efficacy and patient-centred effectiveness, therapeutic alternatives and family goals is required to align physician and patient expectations. A frank discussion about the struggles, practical challenges, risks and contraindications can help to develop an understanding of the risk mitigation strategies employed to maintain safety. Physicians should develop a proactive approach to educate families about this, at times, burdensome procedure. This educational approach should encourage ongoing support starting prior to consent through the maintenance visits. By preparing families for their unique management role, physicians can help ensure the safe and successful integration of OIT into the therapeutic offering for the management of food allergies.

Immunology of allergen immunotherapy

Allergen immunotherapy (AIT) is the only disease-modifying therapy for allergic disease. Through repeated inoculations of low doses of allergen-either as whole proteins or peptides-patients can achieve a homeostatic balance between inflammatory effectors induced and/or associated with allergen contact, and mediators of immunologic non-responsiveness, potentially leading to sustained clinical improvements. AIT for airborne/respiratory tract allergens and insect venoms have traditionally been supplied subcutaneously, but other routes and modalities of administration can also be effective. Despite differences of allergen administration, there are some similarities of immunologic responses across platforms, with a general theme involving the restructuring and polarization of adaptive and innate immune effector cells. Here we review the immunology of AIT across various delivery platforms, including subcutaneous, sublingual, epicutaneous, intradermal, and intralymphatic approaches, emphasizing shared mechanisms associated with achieving immunologic non-responsiveness to allergen.

Allergen immunotherapy for food allergy: Evidence and outlook

Food allergy represents a significant health issue characterized by a sizeable epidemiological burden, involving up to 5% of adults and up to 8% of children in the Western world. The elimination diet of the trigger food is the cornerstone of food allergy management. However, novel treatment options are most wanted to provide alternative strategies for this potentially fatal medical condition. Allergen immunotherapy for food allergy (FA-AIT) is considered an immunomodulatory intervention where regular exposure to increasing doses of food is performed in the context of an allergist's supervised protocol. The main objective is to decrease reactivity, attenuate life-threatening allergic episodes and reduce frequent access to the emergency department. Achieving food tolerance off-treatment is, however, the ultimate aim. In this review, we aim to summarize FA-AIT evidence and outlook.

Treating allergies via skin - Recent advances in cutaneous allergen immunotherapy

Subcutaneous allergen immunotherapy has been practiced clinically for decades to treat airborne allergies. Recently, the cutaneous route, which exploits the immunocompetence of the skin has received attention, which is evident from attempts to use it to treat peanut allergy. Delivery of allergens into the skin is inherently impeded by the barrier imposed by stratum corneum, the top layer of the skin. While the stratum corneum barrier must be overcome for efficient allergen delivery, excessive disruption of this layer can predispose to development of allergic inflammation. Thus, the most desirable allergen delivery approach must provide a balance between the level of skin disruption and the amount of allergen delivered. Such an approach should aim to achieve high allergen delivery efficiency across various skin types independent of age and ethnicity, and optimize variables such as safety profile, allergen dosage, treatment frequency, application time and patient compliance. The ability to precisely quantify the amount of allergen being delivered into the skin is crucial since it can allow for allergen dose optimization and can promote consistency and reproducibility in treatment response. In this work we review prominent cutaneous delivery approaches, and offer a perspective on further improvisation in cutaneous allergen-specific immunotherapy.

Update on pathomechanisms and treatments in allergic rhinitis

Allergic rhinitis (AR) is a global health problem with increasing prevalence and association with an enormous medical and socioeconomic burden. New recognition of immune cells such as type 2 innate lymphocytes (ILC2s), T helper (Th2) 2 cells, follicular helper T cells, follicular regulatory T cells, regulatory T cells, B cells, dendritic cells, and epithelial cells in AR pathogenesis has been updated in this review paper. An in-depth understanding of the mechanisms underlying AR will aid the identification of biomarkers associated with disease and ultimately provide valuable parameters critical to guide personalized targeted therapy. As the only etiological treatment option for AR, allergen-specific immunotherapy (AIT) has attracted increasing attention, with evidence for effectiveness of AIT recently demonstrated in several randomized controlled trials and long-term real-life studies. The exploration of biologics as therapeutic options has only involved anti-IgE and anti-type 2 inflammatory agents; however, the cost-effectiveness of these agents remains to be elucidated precisely. In the midst of the currently on-going COVID-19 pandemic, a global life-threatening disease, although some studies have indicated that AR is not a risk factor for severity and mortality of COVID-19, this needs to be confirmed in multi-centre, real-life studies of AR patients from different parts of 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.

Food allergy, mechanisms, diagnosis and treatment: Innovation through a multi-targeted approach

The incidence of food allergy (FA) has continued to rise over the last several decades, posing significant burdens on health and quality of life. Significant strides into the advancement of FA diagnosis, prevention, and treatment have been made in recent years. In an effort to lower reliance on resource-intensive food challenges, the field has continued work toward the development of highly sensitive and specific assays capable of high-throughput analysis to assist in the diagnosis FA. In looking toward early infancy as a critical period in the development of allergy or acquisition of tolerance, evidence has increasingly suggested that early intervention via the early introduction of food allergens and maintenance of skin barrier function may decrease the risk of FA. As such, large-scale investigations are underway evaluating infant feeding and the impact of emollient and steroid use in infants with dry skin for the prevention of allergy. On the other end of the spectrum, the past few years have been witness to an explosive increase in clinical trials of novel and innovative therapeutic strategies aimed at the treatment of FA in those whom the disease has already manifested. A milestone in the field, 2020 marked the approval of the first drug, oral peanut allergen, for the indication of peanut allergy. With a foundation of promising data supporting the safety and efficacy of single- and multi-allergen oral immunotherapy, current efforts have turned toward the use of probiotics, biologic agents, and modified allergens to optimize and improve upon existing paradigms. Through these advancements, the field hopes to gain footing in the ongoing battle against FA.

Predicting probability of tolerating discrete amounts of peanut protein in allergic children using epitope-specific IgE antibody profiling

BACKGROUND

IgE-epitope profiling can accurately diagnose clinical peanut allergy.

OBJECTIVE

We sought to determine whether sequential (linear) epitope-specific IgE (ses-IgE) profiling can provide probabilities of tolerating discrete doses of peanut protein in allergic subjects undergoing double-blind, placebo-controlled food challenges utilizing PRACTALL dosing.

METHODS

Sixty four ses-IgE antibodies were quantified in blood samples using a bead-based epitope assay. A pair of ses-IgEs that predicts Cumulative Tolerated Dose (CTD) was determined using regression in 75 subjects from the discovery cohort. This epitope-based predictor was validated on 331 subjects from five independent cohorts (ages 4-25 years). Subjects were grouped based on their predicted values and probabilities of reactions at each CTD threshold were calculated.

RESULTS

In discovery, an algorithm using two ses-IgE antibodies was correlated with CTDs (rho = 0.61, p < .05); this correlation was 0.51 (p < .05) in validation. Using the ses-IgE-based predictor, subjects were assigned into "high," "moderate," or "low" dose-reactivity groups. On average, subjects in the "high" group were four times more likely to tolerate a specific dose, compared with the "low" group. For example, predicted probabilities of tolerating 4, 14, 44, and 144 or 444 mg in the "low" group were 92%, 77%, 53%, 29%, and 10% compared with 98%, 95%, 94%, 88%, and 73% in the "high" group.

CONCLUSIONS

Accurate predictions of food challenge thresholds are complex due to factors including limited responder sample sizes at each dose and variations in study-specific challenge protocols. Despite these limitations, an epitope-based predictor was able to accurately identify CTDs and may provide a useful surrogate for peanut challenges.

Microneedle Transdermal Drug Delivery Systems for Allergen-Specific Immunotherapy, Skin Disease Treatment, and Vaccine Development

Transdermal drug delivery systems (TDDSs) overcome the hurdle of an intact skin barrier by penetrating the skin to allow molecules through. These systems reduce side effects associated with conventional hypodermic needles. Here, we introduce novel microneedle (MN) TDDSs that enhance drug delivery by creating micron-sized pores across the skin. Many MN TDDSs designed to deliver a diverse array of therapeutics, including allergen-specific immunotherapy, skin disease treatments, and vaccines, are under pre-clinical and clinical trials. Although epicutaneous approaches are emerging as new options for treating food allergy in many clinical trials, MN TDDSs could provide a more efficient and convenient route to deliver macromolecules. Furthermore, MN TDDSs may allow for safe vaccine delivery without permanent scars. MN TDDSs are a major emerging strategy for delivering novel vaccines and treatments for diseases, including skin diseases, allergic diseases, and so on.

Guideline on allergen immunotherapy in IgE-mediated allergic diseases: S2K Guideline of the German Society of Allergology and Clinical Immunology (DGAKI), Society of Pediatric Allergology and Environmental Medicine (GPA), Medical Association of German Allergologists (AeDA), Austrian Society of Allergology and Immunology (ÖGAI), Swiss Society for Allergology and Immunology (SSAI), German Dermatological Society (DDG), German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (DGHNO-KHC), German Society of Pediatrics and Adolescent Medicine (DGKJ), Society of Pediatric Pulmonology (GPP), German Respiratory Society (DGP), German Professional Association of Otolaryngologists (BVHNO), German Association of Paediatric and Adolescent Care Specialists (BVKJ), Federal Association of Pneumologists, Sleep and Respiratory Physicians (BdP), Professional Association of German Dermatologists (BVDD)

Not available.

Psychometric parameters of food allergy quality of life during an allergen immunotherapy trial

BACKGROUND

The Food Allergy Quality of Life Questionnaire-Parent Form (FAQLQ-PF) is a commonly used patient-reported outcome measure in food allergy (FA) research. It was developed before FA treatment clinical trials were commonplace and is used as a secondary outcome measure in pivotal FA treatment trials. We examined the psychometric properties of the FAQLQ-PF and its relevance to children with peanut allergy engaged in an epicutaneous immunotherapy (EPIT) clinical trial.

METHODS

Analysis was performed on 26 universally answered items of the FAQLQ-PF, from assessments undertaken during the phase 3 PEPITES study (baseline, Month 12), which examined the safety and efficacy of EPIT for children with peanut allergy aged 4-11 years. Item response theory (IRT) was used to assess psychometric parameters of the FAQLQ-PF (i.e., discrimination, difficulty, and information). Confirmatory factor analysis was also employed; reliability was assessed using McDonald's omega (ω) and Cronbach's alpha (α).

RESULTS

A total of 23 of 26 items presented very high discrimination levels (>1.7), and all 26 fell within the recommended difficulty threshold (between -1.5 and 1.5). The items contributed a reasonable information level for their respective factors/subdomains. The measure also presented a marginally acceptable model fit for the 3-factor structure (e.g., comparative fit index = 0.88, Tucker-Lewis index = 0.87) and good reliability levels across time points (ω and α > 0.90).

CONCLUSIONS

Herein, we present a novel reanalysis of the FAQLQ-PF items using IRT. The longitudinal performance of individual items and subscales was corroborated, and items with the highest discrimination were identified, showing that the tool is suitable for longitudinal measurements in FA treatment trials.

Safety of Epicutaneous Immunotherapy in Peanut-Allergic Children: REALISE Randomized Clinical Trial Results

BACKGROUND

Treatment options for peanut allergy are limited. In previous clinical trials, epicutaneous immunotherapy with a patch containing 250-μg peanut protein (Viaskin Peanut 250 μg [VP250]) was well tolerated and statistically superior to placebo in desensitizing peanut-allergic children.

OBJECTIVE

To examine the safety of VP250 in children, using a study design approximating potential real-world use.

METHODS

REAL LIfe Use and Safety of EPIT (REALISE) is a phase 3 multicenter study consisting of a 6-month, randomized, double-blind, placebo-controlled period followed by open-label active treatment. Children aged 4 to 11 years with physician diagnosis of peanut allergy received daily treatment with placebo (6 months) or VP250 (up to 36 months). Data from the 6-month, randomized, controlled phase of REALISE are reported.

RESULTS

Three hundred ninety-three children were randomized 3:1 to receive VP250 (n = 294) or placebo (n = 99) for 6 months; 284 (72.3%) children had a history of peanut anaphylaxis. According to parent diary, all participants receiving VP250 and 83.8% receiving placebo reported at least 1 episode of local skin reaction, with frequency decreasing over time. Only 4 participants (1.4%) receiving VP250 discontinued because of adverse events (AEs). Epinephrine was administered for allergic reactions attributed to VP250 in 7 children (2.4%), of whom 5 remained in the study; none involved severe anaphylaxis. Overall, AE rates were similar among participants with and without a history of peanut anaphylaxis.

CONCLUSIONS

In a study designed to mirror real-world use, VP250 was observed to be well tolerated in peanut-allergic children, consistent with previous phase 2b and 3 studies.

Food allergy: History, definitions and treatment approaches

Allergen-specific immunotherapy for the treatment of immunoglobulin E mediated food allergies, specifically oral, epicutaneous, and sublingual immunotherapies, are promising options that may provide an alternative to strict avoidance of the dietary allergen. Of these potential therapies, oral immunotherapy is the furthest along in development, with strong evidence of efficacy in clinical trials, and has achieved regulatory approval. Nevertheless, oral immunotherapy may not be a suitable therapy for some patients due to the risk of adverse effects. In contrast to oral immunotherapy, epicutaneous and sublingual immunotherapies have demonstrated modest efficacy in clinical trials, with a favorable adverse effect profile, which suggests that these therapies may be possible contenders to oral immunotherapy in certain clinical situations. Familiarity with the various treatment approaches is vital for guiding patients and families as more therapeutic modalities become available for use outside of the research setting.

Epicutaneous allergen immunotherapy induces a profound and selective modulation in skin dendritic cell subsets

BACKGROUND

Epicutaneous immunotherapy (EPIT) protocols have recently been developed to restore tolerance in patients with food allergy (FA). The mechanisms by which EPIT protocols promote desensitization rely on a profound immune deviation of pathogenic T and B cell responses.

OBJECTIVE

To date, little is known about the contribution of skin dendritic cells (skDCs) to T cell remodeling and EPIT efficacy.

METHODS

We capitalized on a preclinical model of food allergy to ovalbumin (OVA) to characterize the phenotype and functions of OVA⁺ skDCs throughout the course of EPIT.

RESULTS

Our results showed that both Langerhans cells (LCs) and dermal conventional cDC1 and cDC2 subsets retained their ability to capture OVA in the skin and to migrate toward the skin-draining lymph nodes during EPIT. However, their activation/maturation status was significantly impaired, as evidenced by the gradual and selective reduction of CD86, CD40, and OVA protein expression in respective subsets. Phenotypic changes during EPIT were also characterized by a progressive diversification of single cell gene signatures within each DC subset. Interestingly, we observed that OVA⁺ LCs progressively lost their capacity to prime CD4⁺ T_EFF, but gained T_REG stimulatory properties. In contrast, cDC1 were inefficient in priming CD4⁺ T_EFF or in reactivating T_MEMin vitro, while cDC2 retained moderate stimulatory properties, and progressively biased type-2 immunity toward type-1 and type-17 responses.

CONCLUSIONS

Our results therefore emphasize that the acquisition of distinct phenotypic and functional specializations by skDCs during EPIT is at the cornerstone of the desensitization process.

Allergen immunotherapy and/or biologicals for IgE-mediated food allergy: A systematic review and meta-analysis

Background

There is substantial interest in immunotherapy and biologicals in IgE‐mediated food allergy.

Methods

We searched six databases for randomized controlled trials about immunotherapy alone or with biologicals (to April 2021) or biological monotherapy (to September 2021) in food allergy confirmed by oral food challenge. We pooled the data using random‐effects meta‐analysis.

Results

We included 36 trials about immunotherapy with 2126 mainly child participants. Oral immunotherapy increased tolerance whilst on therapy for peanut (RR 9.9, 95% CI 4.5.–21.4, high certainty); cow's milk (RR 5.7, 1.9–16.7, moderate certainty) and hen's egg allergy (RR 8.9, 4.4–18, moderate certainty). The number needed to treat to increase tolerance to a single dose of 300 mg or 1000 mg peanut protein was 2.

Oral immunotherapy did not increase adverse reactions (RR 1.1, 1.0–1.2, low certainty) or severe reactions in peanut allergy (RR 1,6, 0.7–3.5, low certainty), but may increase (mild) adverse reactions in cow's milk (RR 3.9, 2.1–7.5, low certainty) and hen's egg allergy (RR 7.0, 2.4–19.8, moderate certainty). Epicutaneous immunotherapy increased tolerance whilst on therapy for peanut (RR 2.6, 1.8–3.8, moderate certainty). Results were unclear for other allergies and administration routes.

There were too few trials of biologicals alone (3) or with immunotherapy (1) to draw conclusions.

Conclusions

Oral immunotherapy improves tolerance whilst on therapy and is probably safe in peanut, cow's milk and hen's egg allergy. More research is needed about quality of life, cost and biologicals.

Development and validation of the food allergy severity score

BACKGROUND

The heterogeneity and lack of validation of existing severity scores for food allergic reactions limit standardization of case management and research advances. We aimed to develop and validate a severity score for food allergic reactions.

METHODS

Following a multidisciplinary experts consensus, it was decided to develop a food allergy severity score (FASS) with ordinal (oFASS) and numerical (nFASS) formats. oFASS with 3 and 5 grades were generated through expert consensus, and nFASS by mathematical modeling. Evaluation was performed in the EuroPrevall outpatient clinic cohort (8232 food reactions) by logistic regression with request of emergency care and medications used as outcomes. Discrimination, classification, and calibration were calculated. Bootstrapping internal validation was followed by external validation (logistic regression) in 5 cohorts (3622 food reactions). Correlation of nFASS with the severity classification done by expert allergy clinicians by Best-Worst Scaling of 32 food reactions was calculated.

RESULTS

oFASS and nFASS map consistently, with nFASS having greater granularity. With the outcomes emergency care, adrenaline and critical medical treatment, oFASS and nFASS had a good discrimination (receiver operating characteristic area under the curve [ROC-AUC]>0.80), classification (sensitivity 0.87-0.92, specificity 0.73-0.78), and calibration. Bootstrapping over ROC-AUC showed negligible biases (1.0 × 10^-6 -1.23 × 10^-3 ). In external validation, nFASS performed best with higher ROC-AUC. nFASS was strongly correlated (R 0.89) to best-worst scoring of 334 expert clinicians.

CONCLUSION

FASS is a validated and reliable method to measure severity of food allergic reactions. The ordinal and numerical versions that map onto each other are suitable for use by different stakeholders in different settings.

Targeted allergen-specific immunotherapy within the skin improves allergen delivery to induce desensitization to peanut

Aim: Epicutaneous immunotherapy (EPIT) with peanut has been demonstrated to be safe but efficacy may be limited by allergen uptake through the skin barrier. To enhance allergen uptake into the skin, the authors used peanut-coated microneedles and compared them with EPIT in a peanut allergy mouse model. Methods: Sensitized mice were treated with peanut-coated microneedles or peanut-EPIT and then challenged with peanut to determine protection. Results: Treatment with peanut-coated microneedles was safe and showed enhanced desensitization to peanut compared with peanut-EPIT administered via a similar schedule. Protection was associated with reduced Th2 immune responses and mast cell accumulation in the intestine. Conclusion: Peanut-coated microneedles have the potential to present a safe method of improving allergen delivery for cutaneous immunotherapy.

The Economic Burden of Food Allergy: What We Know and What We Need to Learn

Purpose of Review

Food allergy management and treatment require dietary modification, are associated with significant burdens, and affect food choices and behaviours. Emerging therapies, such as oral immunotherapy (OIT), provide a glimmer of hope for those living with the condition. Some burdens have received substantial focus, whereas many knowledge gaps on the significance of other impacts, including economic burden, remain.

Recent Findings

Evidence from many countries, but disproportionately from the United States, supports that food allergy carries significant healthcare and societal costs. Early introduction for the prevention of food allergies is theoretically cost-effective, but remains largely undescribed. Unique considerations, such as those to cow’s milk protein allergy, which affects a substantial proportion of infants, and adrenaline autoinjectors, which have a high cost-per-use, require a balance between cost-effectiveness to the healthcare system and adverse outcomes. Household costs have largely been explored in two countries, but owing to different healthcare structures and costs of living, comparisons are difficult, as are generalisations to other countries. Stock epinephrine in schools may present a cost-effective strategy, particularly in economically disadvantaged areas. Costs relating to OIT must be examined within both immediate benefits, such as protection from anaphylaxis, and long-term benefits, such as sustained unresponsiveness.

Summary

Although the absolute costs differ by region/country and type of food allergy, a consistent pattern persists: food allergy is a costly condition, to those who live with it, and the multiple stakeholders with which they interact.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40521-022-00306-5.

Reporting characteristics of journal infographics: a cross-sectional study

BACKGROUND

Infographics have become an increasingly popular method to present research findings and increase the attention research receives. As many scientific journals now use infographics to boost the visibility and uptake of the research they publish, infographics have become an important tool for medical education. It is unknown whether such infographics convey the key characteristics that are needed to make useful interpretations of the data such as an adequate description of the study population, interventions, comparators and outcomes; methodological limitations; and numerical estimates of benefits and harms. This study described whether infographics published in peer-reviewed health and medical research journals contain key characteristics that are needed to make useful interpretations of clinical research.

METHODS

In this cross-sectional study, we identified peer-reviewed journals listed in the top quintile of 35 unique fields of medicine and health research listed in the Journal Citation Reports database. Two researchers screened journals for the presence of infographics. We defined an infographic as a graphical visual representation of research findings. We extracted data from a sample of two of the most recent infographics from each journal. Outcomes were the proportion of infographics that reported key characteristics such as study population, interventions, comparators and outcomes, benefits, harms, effect estimates with measures of precision, between-group differences and conflicts of interest; acknowledged risk of bias, certainty of evidence and study limitations; and based their conclusions on the study's primary outcome.

RESULTS

We included 129 infographics from 69 journals. Most infographics described the population (81%), intervention (96%), comparator (91%) and outcomes (94%), but fewer contained enough information on the population (26%), intervention (45%), comparator (20%) and outcomes (55%) for those components of the study to be understood without referring to the main paper. Risk of bias was acknowledged in only 2% of infographics, and none of the 69 studies that had declared a conflict of interest disclosed it in the infographics.

CONCLUSIONS

Most infographics do not report sufficient information to allow readers to interpret study findings, including the study characteristics, results, and sources of bias. Our results can inform initiatives to improve the quality of the information presented in infographics.

Preventing allergies through the skin

OBJECTIVE

To inform readers of the current and forthcoming skin barrier interventions that have clinically relevant implications in the prevention of allergic sensitization and atopic diseases.

DATA SOURCES

Peer-reviewed journal articles indexed on PubMed and clinical trials referenced on clinicaltrials.gov were analyzed.

STUDY SELECTIONS

Literature searches from PubMed and clinicaltrials.gov were performed using combinations of the following search terms: prevention, allergy, atopy, skin, cutaneous, microbiome, microbiota, Staphylococcus aureus, atopic dermatitis, eczema, food allergy, and asthma.

RESULTS

The skin barrier represents an entry point for allergic sensitization and T_H2-mediated allergic disorders. Results from clinical trials designed to improve microbiome complexity and reduce S aureus colonization, provide skin barrier enhancement, and deliver epicutaneous immunotherapy are summarized and discussed in the context of primary, secondary, and tertiary prevention of allergic disease.

CONCLUSION

The skin barrier is a promising target for prevention of allergic disease, though clinical trial results thus far have been mixed, at best.

Peanut cross-contamination in randomly selected baked goods

BACKGROUND

The current standard of care for managing peanut allergy includes avoidance of peanut and use of injectable epinephrine; however, strict avoidance is difficult and accidental ingestion is common with potentially serious consequences. Despite vigilance and efforts to minimize the risk of accidental exposure, peanut protein cross-contamination continues to occur in a variety of foods, including baked goods.

OBJECTIVE

To assess and quantify the presence of peanut protein contamination in certain baked goods.

METHODS

Randomly selected baked goods were collected from bakeries in the New York and Miami metropolitan areas that sold a variety of ethnic cuisines. A second set of samples from the same bakeries was collected at least 1 week after to evaluate between-batch variability. Samples were sent to the Food Allergy Research and Resource Program to analyze peanut contamination by enzyme-linked immunosorbent assay. Consumption estimates were based on 2003 to 2010 National Health and Nutrition Examination Survey survey data.

RESULTS

Of 154 samples from 18 bakeries, 4 (2.6%) had detectable peanut contamination with peanut protein levels ranging from 0.1 mg/100 g to 650 mg/100 g. Consumption estimates for single occasion ingestion of a contaminated item ranged from 0.07 mg to 832 mg of peanut protein.

CONCLUSION

In this study, unintended peanut protein was present in a small, but not insignificant, proportion of baked goods, with the potential to trigger a reaction in individuals with peanut allergy. Some products contained high levels of unintended peanut protein. The current data support the potential for accidental exposure to peanut protein with its associated risk.

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

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

New and Emerging Concepts and Therapies for the Treatment of Food Allergy

Food allergy is an increasingly common disease that often starts in early childhood and lasts throughout life. Self-reported food allergy has risen at a rate of 1.2% per decade since 1988, and by 2018, the prevalence of food allergy in the United States was estimated to be 8% in children and 11% in adults.^- This prevalence has led to an economic burden of almost $25 billion annually. Despite these staggering statistics, as of the time of this writing, the Food and Drug Administration (FDA) has only approved one treatment for food allergy, which is limited to use in children with peanut allergy. Fortunately, a new horizon of therapeutic interventions, in all stages of development, lay ahead and hold promise for the near future.

One hundred and ten years of Allergen Immunotherapy: A journey from empiric observation to evidence

One hundred and ten years after Noon's first clinical report of the subcutaneous application of allergen extracts, allergen immunotherapy (AIT) has evolved as the most important pillar of the treatment of allergic patients. It is the only disease-modifying treatment option available and the evidence for its clinical efficacy and safety is broad and undisputed. Throughout recent decades, more insights into the underlying mechanisms, in particular the modulation of innate and adaptive immune responses, have been described. AIT is acknowledged by worldwide regulatory authorities, and following the regulatory guidelines for product development, AIT products are subject to a rigorous evaluation before obtaining market authorization. Knowledge and practice are anchored in international guidelines, such as the recently published series of the European Academy of Allergy and Clinical Immunology (EAACI). Innovative approaches continue to be further developed with the focus on clinical improvement by, for example, the usage of adjuvants, peptides, recombinants, modification of allergens, new routes of administration, and the concomitant use of biologicals. In addition, real-life data provide complementary and valuable information on the effectiveness and tolerability of this treatment option in the clinical routine. New mobile health technologies and big-data approaches will improve daily treatment convenience, adherence, and efficacy of AIT. However, the current coronavirus disease 2019 (COVID-19) pandemic has also had some implications for the feasibility and practicability of AIT. Taken together, AIT as the only disease-modifying therapy in allergic diseases has been broadly investigated over the past 110 years laying the path for innovations and further improvement.

Recent Advances in Allergen-Specific Immunotherapy in Humans: A Systematic Review

Allergen-specific immunotherapy (AIT) is presumed to modulate the natural course of allergic disease by inducing immune tolerance. However, conventional AITs, such as subcutaneous immunotherapy and sublingual immunotherapy, require long treatment durations and often provoke local or systemic hypersensitivity reactions. Therefore, only <5% of allergy patients receive AIT as second-line therapy. Novel administration routes, such as intralymphatic, intradermal and epicutaneous immunotherapies, and synthetic recombinant allergen preparations have been evaluated to overcome these limitations. We will review the updated views of diverse AIT methods, and discuss the limitations and opportunities of the AITs for the treatment of allergic diseases in humans.

Treatment Approaches to Food Allergy

IgE-mediated food allergies affect both children and adults and are associated with dramatic decreases in the quality of life. In the majority of cases, food allergens have to be avoided which may be difficult, particularly in patients who suffer from life-threatening symptoms following the ingestion of minimal doses of food allergens. Several novel therapeutic approaches have been studied during the recent past and are summarized in this review. Therapies with novel therapeutic monoclonal antibodies, innovative allergen-specific immunotherapies using subcutaneous, sublingual, or epicutaneous routes, and oral immunotherapies leading to increases of individual thresholds of tolerable foods upon their continuous ingestion showed promising results which may change future management strategies in moderate to severe food allergy.

Safety of Peanut (Arachis hypogaea) Allergen Powder-dnfp in Children and Teenagers With Peanut Allergy: A Pooled Summary of Phase 3 and Extension Trials

BACKGROUND

Peanut (Arachis hypogaea) allergen powder-dnfp (PTAH; previously known as AR101) is a daily oral immunotherapy approved to mitigate allergic reactions following accidental peanut exposure in peanut-allergic individuals aged 4-17 years.

OBJECTIVE

To comprehensively summarize the PTAH safety profile for up to ∼2 years of treatment.

METHODS

Safety and adverse event (AE) data from participants aged 4-17 years from three controlled, phase 3 and two open-label extension trials were pooled and assessed.

RESULTS

Of the 944 individuals receiving ≥1 PTAH dose, median exposure was ∼49 weeks; most participants experienced ≥1 treatment-related AE (TRAE; n=853; 90.4%). A total of 829 participants experienced TRAEs with a maximum severity of mild (n=497; 52.6%) or moderate (n=332; 35.2%); 24 participants (2.5%) experienced TRAEs graded as severe. Overall, 80 (9.5%) participants discontinued due to AEs; most experienced gastrointestinal symptoms and discontinued during the first 6 months. When adjusted for exposure, AEs and TRAEs occurred at a rate of 76.4 and 58.7 events/participant-year of exposure (PYE), respectively, during updosing; AEs and TRAEs decreased to 23.0 and 14.2, respectively, during 300-mg maintenance. Overall, exposure-adjusted rates of systemic allergic reactions were 0.12 events/PYE (mild), 0.11 events/PYE (moderate), and 0.01 events/PYE (severe [anaphylaxis]).

CONCLUSION

The safety profile of PTAH was consistent across trials, manageable, and improved over time. AEs were predominantly mild to moderate and all grades declined in frequency with continued treatment. These data can be used to facilitate shared decision-making discussions with patients and families considering treatment with PTAH.

CLINICAL IMPLICATIONS

During treatment with PTAH, the majority of children and teenagers experienced allergic symptoms that decreased in frequency and severity over time. These symptoms were consistent across PTAH trials, comparable with other allergen immunotherapies, and are familiar to allergists who practice allergen immunotherapy.

Mouse Models of Food Allergy in the Pursuit of Novel Treatment Modalities

The prevalence of IgE-mediated food allergies has increased dramatically in the past three decades, now affecting up to 10% of the US population. IgE-mediated food allergy is an immunologic disease, involving a variety of cells, including B and T cells, mast cells, basophils, ILC2s, and epithelial cells. Mouse models of food allergy mimic the overall immunologic processes known to exist in humans. Due to the limitations of invasive sampling of human tissue and the similarities of the human and mouse immune systems, comprehensive pathogenesis studies of food allergy have been performed in mouse models. Mouse models have been effective in elucidating the roles of non-oral routes of sensitization and identifying key cells and molecules involved in allergic sensitization. Furthermore, the development of novel therapeutic approaches for food allergy has been accelerated through the use of pre-clinical mouse models. Despite the groundbreaking findings stemming from research in mice, there are continued efforts to improve the translational utility of these models. Here, we highlight the achievements in understanding food allergy development and efforts to bring novel treatment approaches into clinical trials.

Role of the gut-skin axis in IgE-mediated food allergy and atopic diseases

PURPOSE OF REVIEW

In recent years, landmark clinical trials investigating the role of early oral exposure to food antigens for food allergy (FA) prevention have highlighted the importance of immunoregulatory pathways in the 'gut-skin axis'. This review highlights recent literature on the mechanisms of the immune system and microbiome involved in the gut-skin axis, contributing to the development of atopic dermatitis (AD), FA, allergic rhinitis (AR) and asthma. Therapeutic interventions harnessing the gut-skin axis are also discussed.

RECENT FINDINGS

Epicutaneous sensitization in the presence of AD is capable of inducing Th2 allergic inflammation in the intestinal tract and lower respiratory airways, predisposing one to the development of AR and asthma. Probiotics have demonstrated positive effects in preventing and treating AD, though there is no evident relationship of its beneficial effects on other allergic diseases. Prophylactic skin emollients use has not shown consistent protection against AD, whereas there is some evidence for the role of dietary changes in alleviating AD and airway inflammation. More randomized controlled trials are needed to clarify the potential of epicutaneous immunotherapy as a therapeutic strategy for patients with FA.

SUMMARY

The growing understanding of the gut-skin interactions on allergic disease pathogenesis presents novel avenues for therapeutic interventions which target modulation of the gut and/or skin.

Incidence of anaphylaxis and accidental peanut exposure: A systematic review

BACKGROUND

Peanut allergy (PA), a common food allergy, is increasing in prevalence and is associated with high rates of anaphylaxis. Prevalence of food-related anaphylaxis is higher in children and adolescents than in adults, and the pediatric incidence is increasing. We conducted a systematic literature review and meta-analysis to determine the incidence of peanut-induced anaphylaxis in children and/or adolescents with PA.

METHODS

Literature searches were conducted using the PubMed database and through supplemental methods. Eligible articles for inclusion were peer-reviewed studies published in English that reported the incidence of anaphylaxis in pediatric PA using the 2006 National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network criteria, sample size, and follow-up duration. Incidence rates were calculated as person-years at risk or a crude incidence rate was calculated. Meta-analyses of pooled data were conducted using the I² statistic as the measure of heterogeneity.

RESULTS

A total of 830 citations were screened; 8 met the study inclusion criteria and were selected for review. Pooled meta-analysis estimates of the incidence of (1) anaphylaxis among children/adolescents with food allergies, (2) anaphylaxis among children/adolescents with PA, and (3) accidental exposure to peanuts among children/adolescents with PA were 3.72 cases per 100 person-years (95% confidence interval [CI] = 2.35, 5.10), 2.74 cases per 100 person-years (95% CI = 1.42, 4.05), and 12.28 cases per 100 person-years (95% CI = 11.51, 13.05), respectively.

CONCLUSIONS

The risks of anaphylaxis among children with food allergies and those with PA contribute to the serious overall burden of PA and food allergy for children and their families.

Oral Immunotherapy for Food-Allergic Children: A Pro-Con Debate

The prevalence of food allergy has increased in recent years, especially in children. Allergen avoidance, and drugs in case of an allergic reaction, remains the standard of care in food allergy. Nevertheless, increasing attention has been given to the possibility to treat food allergy, through immunotherapy, particularly oral immunotherapy (OIT). Several OIT protocols and clinical trials have been published. Most of them focus on children allergic to milk, egg, or peanut, although recent studies developed protocols for other foods, such as wheat and different nuts. OIT efficacy in randomized controlled trials is usually evaluated as the possibility for patients to achieve desensitization through the consumption of an increasing amount of a food allergen, while the issue of a possible long-term sustained unresponsiveness has not been completely addressed. Here, we evaluated current pediatric OIT knowledge, focusing on the results of clinical trials and current guidelines. Specifically, we wanted to highlight what is known in terms of OIT efficacy and effectiveness, safety, and impact on quality of life. For each aspect, we reported the pros and the cons, inferable from published literature. In conclusion, even though many protocols, reviews and meta-analysis have been published on this topic, pediatric OIT remains a controversial therapy and no definitive generalized conclusion may be drawn so far. It should be an option provided by specialized teams, when both patients and their families are prone to adhere to the proposed protocol. Efficacy, long-term effectiveness, possible role of adjuvant therapies, risk of severe reactions including anaphylaxis or eosinophilic esophagitis, and impact on the quality of life of both children and caregivers are all aspects that should be discussed before starting OIT. Future studies are needed to provide firm clinical and scientific evidence, which should also consider patient reported outcomes.

Diversity of T cells in the skin: Novel insights

T cells populate the skin to provide an effective immunosurveillance against external insults and to maintain tissue homeostasis. Most cutaneous T cells are αβ T cells, however, γδ T cells also exist although in much lower frequency. Different subsets of αβ T cells can be found in the skin, such as short-lived effector T cells, central memory T cells, effector memory T cells, and tissue-resident memory T cells. Their differential biology, function, and location provide an ample spectrum of immune responses in the skin. Foxp3+ memory regulatory T cells have a pivotal role in maintaining homeostasis in the skin and their dysregulation has been linked with different skin pathologies. The skin also contains populations of non-classical T cells, such as γδ T cells, NK T cells, and MR1-restricted T cells. Their role in skin homeostasis and response to pathogens has been well established in the past years, however, there is also growing evidence of their role in mediating allergic skin inflammation and promoting sensitization to allergens. In this review, we provide an updated overview on the different subsets of T cells that populate the skin with a specific focus on their role in allergic skin inflammation.

From Allergen Molecules to Molecular Immunotherapy of Nut Allergy: A Hard Nut to Crack

Peanuts and tree nuts are two of the most common elicitors of immunoglobulin E (IgE)-mediated food allergy. Nut allergy is frequently associated with systemic reactions and can lead to potentially life-threatening respiratory and circulatory symptoms. Furthermore, nut allergy usually persists throughout life. Whether sensitized patients exhibit severe and life-threatening reactions (e.g., anaphylaxis), mild and/or local reactions (e.g., pollen-food allergy syndrome) or no relevant symptoms depends much on IgE recognition of digestion-resistant class I food allergens, IgE cross-reactivity of class II food allergens with respiratory allergens and clinically not relevant plant-derived carbohydrate epitopes, respectively. Accordingly, molecular allergy diagnosis based on the measurement of allergen-specific IgE levels to allergen molecules provides important information in addition to provocation testing in the diagnosis of food allergy. Molecular allergy diagnosis helps identifying the genuinely sensitizing nuts, it determines IgE sensitization to class I and II food allergen molecules and hence provides a basis for personalized forms of treatment such as precise prescription of diet and allergen-specific immunotherapy (AIT). Currently available forms of nut-specific AIT are based only on allergen extracts, have been mainly developed for peanut but not for other nuts and, unlike AIT for respiratory allergies which utilize often subcutaneous administration, are given preferentially by the oral route. Here we review prevalence of allergy to peanut and tree nuts in different populations of the world, summarize knowledge regarding the involved nut allergen molecules and current AIT approaches for nut allergy. We argue that nut-specific AIT may benefit from molecular subcutaneous AIT (SCIT) approaches but identify also possible hurdles for such an approach and explain why molecular SCIT may be a hard nut to crack.