Peanut allergy

Navigating Food Allergies: Advances in Diagnosis and Treatment Strategies

Food allergy is a major health concern worldwide, encompassing both immunologic and non-immunologic reactions. This review thoroughly examines the pathophysiology, clinical manifestations, and treatment options for various types of food allergies. Immunologic food allergies, including IgE-mediated reactions such as oral allergy syndrome and systemic anaphylaxis, pose various diagnostic and management challenges. Non-IgE-mediated reactions such as food protein-induced enterocolitis syndrome, dermatitis herpetiformis, and proctocolitis necessitate individualized patient care. In addition, mixed reactions such as eosinophilic esophagitis and atopic dermatitis complicate the clinical picture. Skin prick tests, serum-specific IgE tests, and oral food challenges are all necessary for accurate food allergy diagnosis. The primary therapeutic options are allergen avoidance, epinephrine-based emergency management, and emerging treatments like immunotherapy. Our review emphasizes the importance of multidisciplinary collaboration and ongoing research in improving our understanding and managing food allergies, promising a brighter future for those affected.

Development and evaluation of mouse anti-Ara h 1 and Ara h 3 IgE monoclonal antibodies for advancing peanut allergy research

Immediate hypersensitivity reactions to peanuts are a considerable public health concern due to the acute and severe IgE mediated reactions. To conduct research on the pathogenesis and therapeutics of peanut allergies, it is imperative to have mouse anti-crude peanut extract (CPE) IgE monoclonal antibodies (mAbs) for both in-vitro and in-vivo assays. Without these tools, it is difficult to advance research in this field. In this study, four hybridomas producing anti-CPE IgE mAbs were developed and the IgE mAbs were validated using immune-blot analysis, Sandwich ELISA, Indirect ELISA, a cell-based assay using RBL-2H3 cells, and footpad type I hypersensitivity reaction studies in mice. The results indicate that two of the four mAbs can be effectively used for both in-vitro and in-vivo peanut allergy studies, as they induce allergic reactions with sensitization alone in mice. These novel anti-Ara h1 and Ara h 3 IgE mAbs, in combination with the detailed protocols outlined in this article, offer valuable guidance for studying acute allergic reactions involving mast cells across various platforms. With some considerations, the IgE mAbs can significantly advance peanut allergy research.

Palforzia for Peanut Allergy: A Narrative Review and Update on a Novel Immunotherapy

With Palforzia appearing as the first oral immunotherapy for patients with peanut allergy, the present investigation aims to summarize recent clinical trials, the mechanism of dosing, and the real-world usage of this novel therapy. Palforzia offers a new avenue for treating the human allergic response in previous immune modulation refractory patients or patients who have undergone immune environment sensitivity testing, which allows for more specialized treatment. Current studies are focusing on certain age groups that have been shown to be more receptive to treatment. Further, studies are tailoring oral immunotherapy treatment alongside other immune modulators to elicit greater targeted immune tolerance. With an increasing prevalence of patient allergies, many questions remain surrounding the optimization of therapies in reaching therapeutic goals. Overall, Palforzia offers a hopeful treatment for peanut-allergic patients to attenuate their immune response while furthering research in related therapies.

A comprehensive review on glycation and its potential application to reduce food allergenicity

Food allergens are a major concern for individuals who are susceptible to food allergies and may experience various health issues due to allergens in their food. Most allergenic foods are subjected to heat treatment before being consumed. However, thermal processing and prolonged storage can cause glycation reactions to occur in food. The glycation reaction is a common processing method requiring no special chemicals or equipment. It may affect the allergenicity of proteins by altering the structure of the epitope, revealing hidden epitopes, concealing linear epitopes, or creating new ones. Changes in food allergenicity following glycation processing depend on several factors, including the allergen's characteristics, processing parameters, and matrix, and are therefore hard to predict. This review examines how glycation reactions affect the allergenicity of different allergen groups in allergenic foods.

A single priming event prevents oral tolerance to peanut

BACKGROUND

Indoor dust (ID) is a source of peanut proteins and immunostimulatory adjuvants (e.g. LPS) that can promote airway sensitization to peanut. We aimed to determine whether a single airway exposure to peanut plus adjuvant is sufficient to prevent oral tolerance.

METHODS

To determine the effect of a single priming event, C57BL/6J mice were exposed once to peanut plus adjuvant through the airway, followed by either airway or low-dose oral exposure to peanut, and assessed for peanut allergy. Oral tolerance was investigated by feeding high-dose peanut followed by airway sensitization. To determine whether a single priming could prevent oral tolerance, the high-dose peanut regimen was applied after a single airway exposure to peanut plus adjuvant. Peanut-specific IgE and IgG1 were quantified, and mice were challenged to peanut to assess allergy. Peanut-specific CD4+ memory T cells (CD4+ TCRβ+ CD44hi CD154+ ) were quantified in mediastinal lymph nodes following airway priming.

RESULTS

Mice co-exposed to peanut with LPS or ID through the airway were primed to develop peanut allergy after subsequent low-dose oral or airway exposures to peanut. Oral tolerance was induced in mice fed high-dose peanut prior to airway sensitization. In contrast, mice fed high-dose peanut following a single airway exposure to peanut plus adjuvant led to allergy. Peanut-specific CD4+ memory T cells were detected as early as 7 days after the single airway priming with peanut plus adjuvant, however, delaying peanut feeding even 1 day following priming led to allergy, whereas peanut feeding the same day as priming led to tolerance.

CONCLUSIONS

A single airway exposure to peanut plus adjuvant is sufficient to prime the immune system to develop allergy following subsequent high-dose oral exposure. These results highlight the importance of introducing peanut as early as possible to prevent sensitization through a non-oral priming event.

Environmental Exposure to Foods as a Risk Factor for Food Allergy

PURPOSE OF REVIEW

Many factors have been reported to contribute to the development of food allergy. Here, we summarize the role of environmental exposure to foods as a major risk factor for developing food allergy.

RECENT FINDINGS

Peanut proteins are detectable and biologically active in household environments, where infants spend a majority of their time, providing an environmental source of allergen exposure. Recent evidence from clinical studies and mouse models suggests both the airway and skin are routes of exposure that lead to peanut sensitization. Environmental exposure to peanut has been clearly associated with the development of peanut allergy, although other factors such as genetic predisposition, microbial exposures, and timing of oral feeding of allergens also likely contribute. Future studies should more comprehensively assess the contributions of each of these factors for a variety of food allergens to provide more clear targets for prevention of food allergy.

Peanut allergen inhibition prevents anaphylaxis in a humanized mouse model

Peanut-induced allergy is an immunoglobulin E (IgE)-mediated type I hypersensitivity reaction that manifests symptoms ranging from local edema to life-threatening anaphylaxis. Although there are treatments for symptoms in patients with allergies resulting from allergen exposure, there are few preventive therapies other than strict dietary avoidance or oral immunotherapy, neither of which are successful in all patients. We have previously designed a covalent heterobivalent inhibitor (cHBI) that binds in an allergen-specific manner as a preventive for allergic reactions. Building on previous in vitro testing, here, we developed a humanized mouse model to test cHBI efficacy in vivo. Nonobese diabetic-severe combined immunodeficient γc-deficient mice expressing transgenes for human stem cell factor, granulocyte-macrophage colony-stimulating factor, and interleukin-3 developed mature functional human mast cells in multiple tissues and displayed robust anaphylactic reactions when passively sensitized with patient-derived IgE monoclonal antibodies specific for peanut Arachis hypogaea 2 (Ara h 2). The allergic response in humanized mice was IgE dose dependent and was mediated by human mast cells. Using this humanized mouse model, we showed that cHBI prevented allergic reactions for more than 2 weeks when administered before allergen exposure. cHBI also prevented fatal anaphylaxis and attenuated allergic reactions when administered shortly after the onset of symptoms. cHBI impaired mast cell degranulation in vivo in an allergen-specific manner. cHBI rescued the mice from lethal anaphylactic responses during oral Ara h 2 allergen-induced anaphylaxis. Together, these findings suggest that cHBI has the potential to be an effective preventative for peanut-specific allergic responses in patients.

Dose and route of administration determine the efficacy of prophylactic immunotherapy for peanut allergy in a Brown Norway rat model

Introduction

Allergen-specific immunotherapy (IT) is emerging as a viable option for treatment of peanut allergy. Yet, prophylactic IT remains unexplored despite early introduction of peanut in infancy was shown to prevent allergy. There is a need to understand how allergens interact with the immune system depending on the route of administration, and how different dosages of allergen may protect from sensitisation and a clinical active allergy. Here we compared peanut allergen delivery via the oral, sublingual (SL), intragastric (IG) and subcutaneous (SC) routes for the prevention of peanut allergy in Brown Norway (BN) rats.

Methods

BN rats were administered PBS or three different doses of peanut protein extract (PPE) via either oral IT (OIT), SLIT, IGIT or SCIT followed by intraperitoneal (IP) injections of PPE to assess the protection from peanut sensitisation. The development of IgE and IgG1 responses to PPE and the major peanut allergens were evaluated by ELISAs. The clinical response to PPE was assessed by an ear swelling test (EST) and proliferation was assessed by stimulating splenocytes with PPE.

Results

Low and medium dose OIT (1 and 10 mg) and all doses of SCIT (1, 10, 100 µg) induced sensitisation to PPE, whereas high dose OIT (100 mg), SLIT (10, 100 or 1000 µg) or IGIT (1, 10 and 100 mg) did not. High dose OIT and SLIT as well as high and medium dose IGIT prevented sensitisation from the following IP injections of PPE and suppressed PPE-specific IgE levels in a dose-dependent manner. Hence, administration of peanut protein via different routes confers different risks for sensitisation and protection from peanut allergy development. Overall, the IgE levels toward the individual major peanut allergens followed the PPE-specific IgE levels.

Discussion

Collectively, this study showed that the preventive effect of allergen-specific IT is determined by the interplay between the specific site of PPE delivery for presentation to the immune system, and the allergen quantity, and that targeting and modulating tolerance mechanisms at specific mucosal sites may be a prophylactic strategy for prevention of peanut allergy.

Breastfeeding: Maternally Transferred Allergens in Breast Milk: Protective or Sensitizing?

According to a thorough literature search, the following allergen sources have been associated with allergy symptoms in the exclusively breastfed child: hen's egg, cow's milk, peanut, trout. Subsequently, several studies use the advantage of molecular allergology and investigate the potential transfer of single allergens into breastmilk. This is shown for caseins, whey proteins, gliadin, ovalbumin, ovomucoid, the peanut allergens Ara h 2 and Ara h 6, as well as the inhalant allergens Der p 1 and Blo t 5. It is still a matter of debate whether or not food allergens transferred via breastfeeding to the baby promote allergic sensitization or induce tolerance and via which mechanisms they may shift the immune response to the one or other side. Noteworthy, some breastfed children are described to be sensitized to foods before being exposed to solid foods, and this exposure may have occurred through breastmilk. In the light of these findings the investigation of food allergens transferred from the mother's diet into breastmilk and their impact on sensitization or allergy prevention remains a current topic in research. This review describes breastmilk in its composition and provides data on the identification of food allergens therein including human and mouse studies.

Peanut allergy diagnosis: Moving from basic to more elegant testing

Peanut allergy (PNA) is an IgE-mediated immune disorder, which merits particular attention due to its impact on the health and quality of life of millions of patients worldwide. PNA tends to develop in early life and resolves in only 20% of peanut-allergic children. It accounts for the majority of severe food-related allergic reactions. An accurate diagnosis of PNA is vital. In this review, we present the approach to the diagnosis of peanut allergy, starting from the history and proceeding to measures of overall sensitization and then to component-resolved diagnostics and oral food challenges as indicated. Additional testing in development includes basophil activation testing and determination of epitopes for peanut-allergic responses. Based on the literature, stepwise approaches and predictive models for diagnosing PNA are also presented.

Evolution of Immune Responses in Food Immunotherapy

Food allergies are a growing public health concern affecting approximately 8% of children and 10% of adults in the United States. Several immunotherapy approaches are under active investigation, including oral immunotherapy, epicutaneous immunotherapy, and sublingual immunotherapy. Each of these approaches uses a similar strategy of administering small, increasing amounts of allergen to the allergic subject. Immunologic studies have described changes in the T-cell compartment, serum and salivary immunoglobulin profile, and mast cell and basophil degranulation status in response to allergens. This review highlights the immunologic changes induced by food allergen-specific immunotherapy and discusses future directions in this field.

Screening of Nanobody Specific for Peanut Major Allergen Ara h 3 by Phage Display

Peanut allergy is a major health problem worldwide. Detection of food allergens is a critical aspect of food safety. The VHH domain of single chain antibody from camelids, also known as nanobody (Nb), showed its advantages in the development of biosensors because of its high stability, small molecular size, and ease of production. However, no nanobody specific to peanut allergens has been developed. In this study, we constructed a library with random triplets (NNK) in its CDR regions of a camel nanobody backbone. We screened the library with peanut allergy Ara h 3 and obtained several candidate nanobodies. One of the promising nanobodies, Nb16 was further biochemical characterization by gel filtration, isothermal titration calorimetry (ITC), cocrystallization, and Western blot in terms of its interaction with Ara h 3. Nb16 specifically binds to peanut major allergen Ara h 3 with a dissociation constant of 400 nM. Furthermore, we obtained the Ara h 3-Nb16 complex crystals. Structure analysis shows the packing mode is completely different between the Ara h 3-Nb16 complex crystal and the native Ara h 3 crystal. Structural determination of Ara h 3-Nb16 will provide the necessary information to understand the allergenicity of this important peanut allergen. The nanobody Nb16 may have application in the development of biosensors for peanut allergen detection.

Indoor dust acts as an adjuvant to promote sensitization to peanut through the airway

BACKGROUND

There is growing evidence that environmental peanut exposure through non-oral routes, including the skin and respiratory tract, can result in peanut sensitization. Environmental adjuvants in indoor dust can promote sensitization to inhaled antigens, but whether they contribute to peanut allergy development is unclear.

OBJECTIVE

We investigated whether indoor dust promotes airway sensitization to peanut and peanut allergy development in mice.

METHODS

Female and male C57BL/6J mice were exposed via the airways to peanut, indoor dust extract, or both for 2 weeks. Mice were then challenged with peanut and assessed for anaphylaxis. Peanut-specific immunoglobulins, peanut uptake by lung conventional dendritic cells (cDCs), lung innate cytokines, and T cell differentiation in lung-draining lymph nodes were quantified. Innate cytokine production by primary human bronchial epithelial cells exposed to indoor dust was also determined.

RESULTS

Inhalational exposure to low levels of peanut in combination with indoor dust, but neither alone, resulted in production of peanut-specific IgE and development of anaphylaxis upon peanut challenge. Indoor dust triggered production of innate cytokines in murine lungs and in primary human bronchial epithelial cells. Additionally, inhaled indoor dust stimulated maturation and migration of peanut-laden lung type 1 cDCs to draining lymph nodes. Inhalational exposure to peanut and indoor dust induced peanut-specific T helper 2 cell differentiation and accumulation of T follicular helper cells in draining lymph nodes, which were associated with increased B cell numbers and peanut-specific immunoglobulin production.

CONCLUSIONS & CLINICAL RELEVANCE

Indoor dust promotes airway sensitization to peanut and development of peanut allergy in mice. Our findings suggest that environmental adjuvants in indoor dust may be determinants of peanut allergy development in children.

A hybridization chain reaction coupled with gold nanoparticles for allergen gene detection in peanut, soybean and sesame DNAs

Food allergy is an abnormal immune response of the immune system to some foods, which has caused great harm to people's health. Therefore, it is particularly important to detect allergens in food. In this article, a hybridization chain reaction (HCR) was coupled with gold nanoparticles (AuNPs) to detect the allergen genes of peanut, soybean and sesame DNAs. Two hairpin probes (H1 and H2) were designed for the allergen target genes of peanut, soybean and sesame DNAs. In the presence of target DNA, the hybridization chain reaction was triggered by it producing long double-stranded DNA (dsDNA) products. In the gold nanoparticle system, long dsDNA couldn't be adsorbed on the surface of AuNPs. When the concentration of salt ions in the solution increased, gold nanoparticles accumulated and led to a decrease of ultraviolet absorption. In the absence of target DNA, no hybridization chain reaction occurred. The hairpin probes could be adsorbed on the surface of AuNPs and no accumulation happened for gold nanoparticles even if the concentration of salt ions in the solution was increased. This method required no enzymes and had a strong specificity, so it was very easy to distinguish target DNA from non-target DNA. The detection limit of three allergens detected by this method was as low as 0.5 nM. The feasibility of this method for the detection of commercial commodities had been demonstrated by the successful detection of the DNAs extracted from commercial commodities, which were treated with extreme thermostable single-stranded binding protein (ET SSB).

A graphene oxide-based paper chip integrated with the hybridization chain reaction for peanut and soybean allergen gene detection

Allergen genes of the peanut and soybean were selected as model targets. Four hairpin DNA probes, H1, H2, H3, H4 were designed. Cy3-labeled H1 and H2 were used to detect peanut DNA, while FAM-labeled H3 and H4 were used to detect soybean DNA. Graphene oxide (GO) was used as the adsorption material for capturing the hairpin probes, and as a selective fluorescence quencher to reduce the background signal. To develop an allergen gene detection system with a GO-based paper chip format, we integrated the hybridization chain reaction (HCR) with fluorescence resonance energy transfer (FRET) in our design. The results showed that in the absence of peanut DNA (TP) and soybean DNA (TS), the detection probes attached to the GO surface, which quenched their fluorescence. In the presence of TP or TS, however, complementary probe binding to the targets initiated HCR, producing long double-stranded DNA products that could not be absorbed onto the GO surface. Hence, a strong red or green fluorescent signal was generated. The detection limit for both peanut and soybean DNA was 1 nM using this method, indicating the high sensitivity of our approach. This method also exhibited good specificity and a single chip could be used to simultaneously detect two different targets.

"Inactive" ingredients in oral medications

Oral forms of medications contain "inactive" ingredients to enhance their physical properties. Using data analytics, we characterized the abundance and complexity of inactive ingredients in approved medications. A majority of medications contain ingredients that could cause adverse reactions, underscoring the need to maximize the tolerability and safety of medications and their inactive ingredients.

Mouse strain differences in response to oral immunotherapy for peanut allergy

Background

Promising therapies for food allergy are emerging, mostly based on animal experimentation. However, different mouse strains are used, which may make it hard to compare experiments. The current study investigated whether the immunological differences between C3H/HeOuJ (C3H) and BALB/c mice lead to differences in efficacy of peanut‐specific immunotherapy.

Methods

After sensitization using peanut extract (PE), C3H and BALB/c mice received oral immunotherapy (OIT) by intragastric dosing for three weeks. Hereafter, mice were exposed to PE via the intradermal, intragastric and intraperitoneal route, to determine allergic outcomes. Furthermore, PE‐specific antibody and cytokine production were determined and the number of various immune cells at different time points during the study were measured.

Results

OIT protected C3H mice against anaphylaxis, whereas no anaphylaxis was seen in BALB/c mice. In contrast, OIT induced an increase in MMCP‐1 levels in BALB/c mice but not in C3H mice. No effect of OIT on the acute allergic skin response was observed in either strain. Specific antibody responses showed similar patterns in both strains for IgA and IgG1. IgE levels were a tenfold higher in BALB/c mice and after the intragastric challenge (day 70) OIT‐treated BALB/c mice showed induced IgE levels. Moreover, in C3H mice IgG2a levels were higher and increased in response to OIT and challenges. After the final challenge, but not at other timepoints MLN‐derived lymphocytes from OIT‐treated BALB/c mice produced less IL‐13 and IL‐5 compared to control‐treated mice, whereas no differences were seen in case of C3H mice.

Conclusions

Taken together, these results show that the C3H strain is more suitable to study clinical outcomes of OIT, whereas the BALB/c strain is more optimal to study T cell responses.

Adjuvanted Immunotherapy Approaches for Peanut Allergy

Food allergies are a growing public health concern with an estimated 8% of US children affected. Peanut allergies are also on the rise and often do not spontaneously resolve, leaving individuals at-risk for potentially life-threatening anaphylaxis throughout their lifetime. Currently, two forms of peanut immunotherapy, oral immunotherapy (OIT) and epicutaneous immunotherapy (EPIT), are in Phase III clinical trials and have shown promise to induce desensitization in many subjects. However, there are several limitations with OIT and EPIT, such as allergic side effects, daily dosing requirements, and the infrequent outcome of long-term tolerance. Next-generation therapies for peanut allergy should aim to overcome these limitations, which may be achievable with adjuvanted immunotherapy. An adjuvant can be defined as anything that enhances, accelerates, or modifies an immune response to a particular antigen. Adjuvants may allow for lower doses of antigen to be given leading to decreased side effects; may only need to be administered every few weeks or months rather than daily exposures; and may induce a long-lasting protective effect. In this review article, we highlight examples of adjuvants and formulations that have shown pre-clinical efficacy in treating peanut allergy.

Anaphylaxis

Anaphylaxis is an acute, potentially fatal systemic allergic reaction with varied mechanisms and clinical presentations. Although prompt recognition and treatment of anaphylaxis are imperative, both patients and healthcare professionals often fail to recognize and diagnose early signs and symptoms of the condition. Clinical manifestations vary widely; however, the most common signs are cutaneous symptoms, including urticaria, angioedema, erythema and pruritus. Immediate intramuscular administration of epinephrine into the anterolateral thigh is first-line therapy, even if the diagnosis is uncertain. The mainstays of long-term management include specialist assessment, avoidance measures, and the provision of an epinephrine auto-injector and an individualized anaphylaxis action plan. This article provides an overview of the causes, clinical features, diagnosis and acute and long-term management of this serious allergic reaction.

No difference in human mast cells derived from peanut allergic versus non-allergic subjects

INTRODUCTION

Mast cells are the primary effector cells of allergy. This study aimed at characterizing human peripheral blood-derived mast cells (PBdMC) from peanut allergic and non-allergic subjects by investigating whether the molecular and stimulus-response profile of PBdMC discriminate between peanut allergic and healthy individuals.

METHODS

PBdMC were generated from eight peanut allergic and 10 non-allergic subjects. The molecular profile (cell surface receptor expression) was assessed using flow cytometry. The stimulus-response profile (histamine release induced by secretagogues, secretion of cytokines/chemokines and changes in miRNA expression following anti-IgE activation) was carried out with histamine release test, luminex multiplex assay and miRNA arrays.

RESULTS

Expression of activating receptors (FcϵRI, CD48, CD88, CD117, and C3aR) on PBdMC was not different among peanut allergic and non-allergic subjects. Likewise, inhibitory receptors (CD32, CD200R, CD300a, and siglec-8) displayed comparable levels of expression. Both groups of PBdMC were unresponsive to substance P, compound 48/80 and C5a but released comparable levels of histamine when stimulated with anti-IgE and C3a. Interestingly, among the secreted cytokines/chemokines (IL-8, IL-10, IL-13, IL-23, IL-31, IL-37, MCP-1, VEGF, GM-CSF) PBdMC from peanut allergic subjects showed a different secretion pattern of IL-31 compared to non-allergic subjects. Investigating miRNA expression from resting or activated PBdMC revealed no significantly difference between peanut allergic and non-allergic subjects.

CONCLUSION

The molecular and stimulus-response profile revealed that PBdMC from peanut allergic subjects differently express IL-31 compared to non-allergic subjects. However, since only one altered parameter was found among 893 investigated, it is still questionable if the pathophysiological mechanisms of peanut allergy are revealed in PBdMC.

Colorimetric LAMP microfluidic chip for detecting three allergens: peanut, sesame and soybean

Food allergies can greatly harm people's health, and therefore detecting allergens in foods is extremely important. By integrating loop-mediated isothermal amplification (LAMP) with a microfluidic chip, we have developed a method for detecting the allergen genes of peanut (Arachis hypogaea), sesame (Sesamum indicum), and soybean (Glycine max) using a colorimetric method suitable for the naked eye, known as the colorimetric LAMP microfluidic chip. In the presence of peanut, sesame, or soybean in the samples, the corresponding reaction well of the microfluidic chip will appear pink, or otherwise remain light brown. This method of detection is specific and can easily distinguish these three allergens from others in foods. The detection limit for peanut, sesame and soybean allergens was 0.4 ng/μL using the LAMP-microfluidic chip. The accuracy of this novel and rapid method was validated using allergenic foods obtained commercially and was comparable with that of the typical TaqMan real-time PCR method.

BSACI guideline for the diagnosis and management of peanut and tree nut allergy

Peanut nut and tree nut allergy are characterised by IgE mediated reactions to nut proteins. Nut allergy is a global disease. Limited epidemiological data suggest varying prevalence in different geographical areas. Primary nut allergy affects over 2% of children and 0.5% of adults in the UK. Infants with severe eczema and/or egg allergy have a higher risk of peanut allergy. Primary nut allergy presents most commonly in the first five years of life, often after the first known ingestion with typical rapid onset IgE-mediated symptoms. The clinical diagnosis of primary nut allergy can be made by the combination of a typical clinical presentation and evidence of nut specifc IgE shown by a positive skin prick test (SPT) or specific IgE (sIgE) test. Pollen food syndrome is a distinct disorder, usually mild, with oral/pharyngeal symptoms, in the context of hay fever or pollen sensitisation, which can be triggered by nuts. It can usually be distinguish clinically from primary nut allergy. The magnitude of a SPT or sIgE relates to the probability of clinical allergy, but does not relate to clinical severity. SPT of ≥ 8 mm or sIgE ≥ 15 KU/L to peanut is highly predictive of clinical allergy. Cut off values are not available for tree nuts. Test results must be interpreted in the context of the clinical history. Diagnostic food challenges are usually not necessary but may be used to confirm or refute a conflicting history and test result. As nut allergy is likely to be a long-lived disease, nut avoidance advice is the cornerstone of management. Patients should be provided with a comprehensive management plan including avoidance advice, patient specific emergency medication and an emergency treatment plan and training in administration of emergency medication. Regular re-training is required.

Oral and sublingual immunotherapy for egg allergy

BACKGROUND

Clinical egg allergy is a common food allergy. Current management relies upon strict allergen avoidance. Oral immunotherapy might be an optional treatment, through desensitization to egg allergen.

OBJECTIVES

To determine the efficacy and safety of oral and sublingual immunotherapy in children and adults with immunoglobulin E (IgE)-mediated egg allergy as compared to a placebo treatment or an avoidance strategy.

SEARCH METHODS

We searched 13 databases for journal articles, conference proceedings, theses and trials registers using a combination of subject headings and text words (last search 31 March 2017).

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing oral immunotherapy or sublingual immunotherapy administered by any protocol with placebo or an elimination diet. Participants were children or adults with clinical egg allergy.

DATA COLLECTION AND ANALYSIS

We retrieved 97 studies from the electronic searches. We selected studies, extracted data and assessed the methodological quality. We attempted to contact the study investigators to obtain the unpublished data, wherever possible. We used the I² statistic to assess statistical heterogeneity. We estimated a pooled risk ratio (RR) with 95% confidence interval (CI) for each outcome using a Mantel-Haenzel fixed-effect model if statistical heterogeneity was low (I² value less than 50%). We rated the quality of evidence for all outcomes using GRADE.

MAIN RESULTS

We included 10 RCTs that met our inclusion criteria, that involved a total of 439 children (oral immunotherapy 249; control intervention 190), aged 1 year to 18 years. Each study used a different oral immunotherapy protocol; none used sublingual immunotherapy. Three studies used placebo and seven used an egg avoidance diet as the control. Primary outcomes were: an increased amount of egg that can be ingested and tolerated without adverse events while receiving allergen-specific oral immunotherapy or sublingual immunotherapy, compared to control; and a complete recovery from egg allergy after completion of oral immunotherapy or sublingual immunotherapy, compared to control. Most children (82%) in the oral immunotherapy group could ingest a partial serving of egg (1 g to 7.5 g) compared to 10% of control group children (RR 7.48, 95% CI 4.91 to 11.38; RD 0.73, 95% CI 0.67 to 0.80). Fewer than half (45%) of children receiving oral immunotherapy were able to tolerate a full serving of egg compared to 10% of the control group (RR 4.25, 95% CI 2.77 to 6.53; RD 0.35, 95% CI 0.28 to 0.43). All 10 trials reported numbers of children with serious adverse events (SAEs) and numbers of children with mild-to-severe adverse events. SAEs requiring epinephrine/adrenaline presented in 21/249 (8.4%) of children in the oral immunotherapy group, and none in the control group. Mild-to-severe adverse events were frequent; 75% of children presented mild-to-severe adverse events during oral immunotherapy treatment versus 6.8% of the control group (RR 8.35, 95% CI 5.31 to 13.12). Of note, seven studies used an egg avoidance diet as the control. Adverse events occurred in 4.2% of children, which may relate to accidental ingestion of egg-containing food. Three studies used a placebo control with adverse events present in 2.6% of children. Overall, there was inconsistent methodological rigour in the trials. All studies enrolled small numbers of children and used different methods to provide oral immunotherapy. Eight included studies were judged to be at high risk of bias in at least one domain. Furthermore, the quality of evidence was judged to be low due to small numbers of participants and events, and possible biases.

AUTHORS' CONCLUSIONS

Frequent and increasing exposure to egg over one to two years in people who are allergic to egg builds tolerance, with almost everyone becoming more tolerant compared with a minority in the control group and almost half of people being totally tolerant of egg by the end of treatment compared with 1 in 10 people who avoid egg. However, nearly all who received treatment experienced adverse events, mainly allergy-related. We found that 1 in 12 children had serious allergic reactions requiring adrenaline, and some people gave up oral immunotherapy. It appears that oral immunotherapy for egg allergy is effective, but confidence in the trade-off between benefits and harms is low; because there was a small number of trials with few participants, and methodological problems with some trials.

Peanut Allergy: An Epidemiologic Analysis of a Large Database

OBJECTIVE

To confirm new observations on peanut allergy and answer current concerns that families and healthcare providers have about peanut allergy.

STUDY DESIGN

Children who presented with a story of peanut allergy or peanut sensitization were asked to participate in a registry, which allowed an analysis focused on questions that a food allergy support group had about children with peanut allergy or sensitization.

RESULTS

A total of 1070 children were entered into the registry over 5 years. Two-thirds had a reaction to peanut. Children with peanut allergy were predominantly male (63%), white (78%), and with private health insurance (80%). Most reactions involved the skin (55%) and anaphylaxis occurred in 35%. The median age of a reaction was 1 year old. Atopic dermatitis was noted in 60% and asthma in 41%. Additional food allergy was noted in 58%. When second exposures occurred 28% had a more severe reaction. Skin test size did not differentiate the type of a reaction and children with anaphylaxis had slightly higher specific IgE levels. Severe reactions with inadvertent exposure in children who were peanut sensitized was rare (<1%).

CONCLUSIONS

The strategies for peanut allergy prevention and treatment have evolved. The data obtained in this large registry can answer many questions that families and healthcare providers have during this transition.

A Mouse Model of Peanut Allergy Induced by Sensitization Through the Gastrointestinal Tract

Animal models of disease enable the study of the pathology, biomarkers, and treatments for the disease being studied. These models become particularly useful in the study of diseases, such as peanut allergy, that currently have no FDA-approved therapy options. Here, we describe a mouse model of peanut allergy using a peanut extract and cholera toxin that can be applied to both BALB/c and C3H/HeJ mouse strains. Sensitization is induced through the gastrointestinal tract resulting in elevated levels of peanut-specific IgE and anaphylaxis upon challenge with peanut proteins. This model has been used to study the cells and molecules involved in the development of peanut allergy and to evaluate novel immunotherapy approaches and the underlying mechanisms of immunotherapy. Potential utilities of this model are numerous and may include studies on microbial influences on peanut allergy and discovery of biomarkers of anaphylaxis.

Identification of a common Ara h 3 epitope recognized by both the capture and the detection monoclonal antibodies in an ELISA detection kit

Allergy to peanuts has become a common and severe problem, especially in westernized countries. In this study, we evaluated the target and epitope specificity of the capture and detection mouse monoclonal antibodies (mAbs) used in a commercial peanut allergen detection platform. We first identified the target of these antibodies as Ara h 3 and then used an overlapping peptide array of Ara h 3 to determine the antibody-binding epitopes. Further amino acids critical for the binding via alanine substitutions at individual amino acid residues within the epitope were mapped. Finally, inhibition ELISA and inhibition immunoblotting using a recombinant Ara h 3 protein were performed to confirm these results. Surprisingly, the capture and detection mAbs showed identical binding characteristics and were presumed to represent two isolates of the same clone, a notion supported by both isoelectric focusing electrophoresis and Liquid chromatography–mass spectrometry experiments. The simultaneous binding of a pair of identical mAbs to an individual allergen such as Ara h3 is attributed to the multivalency of the analyte and has implications for developing diagnostic assays for additional multimeric allergens.

Conjunctival provocation test in diagnosis of peanut allergy in children

BACKGROUND

Peanut allergy frequently causes severe allergic reactions. Diagnosis includes detection of IgE to peanuts in serum or by skin prick tests. While children may have allergic sensitization without having clinical peanut allergy, oral peanut challenge is often required for accurate diagnosis. The conjunctival provocation test is used for diagnosis and evaluation of treatment effect in inhalant allergies, but it has not been evaluated as a tool for diagnosing peanut allergy.

OBJECTIVE

To investigate whether the conjunctival provocation tests may be feasible, accurate and safe in diagnosing clinically relevant peanut allergy in patients with suspected peanut allergy.

METHODS

This cross-sectional case-control study in children with clinical or laboratory suspected peanut allergy included 102 children recruited from the regional paediatric departments and specialist practices during one year from April 2011. A peanut-tolerant control group of 28 children of similar age was recruited locally. A double-blind placebo-controlled conjunctival provocation test with peanut extract was performed in all children, while oral peanut provocation was performed as double-blind placebo-controlled challenge in children with suspected peanut allergy and as an open challenge in the control children.

RESULTS

All 81 children with a positive double-blind placebo-controlled oral food challenge (OFC) also had a positive conjunctival provocation test. None of the children with negative conjunctival provocation test had a positive OFC. The sensitivity and the specificity of the conjunctival provocation test were 0.96 and 0.83, respectively. No children had severe adverse reaction caused by the conjunctival provocation test, whereas 23 children suffered an anaphylactic reaction to the OFC.

CONCLUSION AND CLINICAL RELEVANCE

Conjunctival allergen challenge appears to be feasible, accurate and safe in diagnosing children referred for suspected peanut allergy.

Peanut oleosins associated with severe peanut allergy-importance of lipophilic allergens for comprehensive allergy diagnostics

BACKGROUND

Peanut allergy is one of the most common and most severe food allergies in Western countries and its accurate diagnosis to prevent potential life-threatening allergic reactions is crucial. However, aqueous extracts used for routine diagnostic measurements are devoid of lipophilic allergens such as oleosins. We have recently succeeded in the isolation and purification of these unique proteins, and the present study evaluates their allergenic potential and clinical relevance.

OBJECTIVE

We sought to assess allergenicity and sensitization prevalence of oleosins obtained from both raw and in-shell roasted peanuts. In addition, we tested the utilization of natural and recombinant oleosins for allergy diagnostic purposes.

METHODS

Oleosin sensitization, prevalence, and impact of thermal processing were analyzed by immunoblot with sera from 52 peanut-allergic individuals displaying different clinical phenotypes. The application of natural and recombinant oleosins for allergy diagnostics was investigated by basophil activation test (BAT). IgE-binding epitopes were identified by oligopeptide microarray.

RESULTS

Sensitization to oleosins was observed exclusively in peanut-allergic subjects suffering from severe systemic reactions. IgE-binding capacity of oleosins derived from in-shell roasted peanuts was increased as shown by immunoblot analysis and BAT. Both natural and recombinant molecules can be used to identify oleosin-sensitized patients by BAT. A linear epitope of Ara h 15 was determined that displays high similarity to other seed-derived oleosins.

CONCLUSIONS

Oleosins are clinically relevant peanut allergens and most likely associated with severe allergic symptoms. In-shell roasting increases their allergenicity, which is consistent with the observation that most allergic reactions are in connection with roasted peanuts.

Prediction of clinical peanut allergy status among children in Hamilton, Ontario using chart review data collected during 2012-2015

Background

Peanut sensitization does not necessarily indicate clinical peanut allergy, and uncertainty as to whether or not there is true peanut allergy can lead to increased anxiety and decreased quality of life for patients and their families. The gold standard for diagnosing clinical peanut allergy is the oral food challenge, but this method is time-consuming and can cause severe allergic reactions. It would therefore be beneficial to develop a tool for predicting clinical peanut allergy in peanut-sensitized individuals whose peanut allergy status is unknown so as to better determine who requires an oral food challenge for diagnosis.

Methods

Two separate studies were conducted. In Study 1, we recruited 100 participants from the allergy clinic at McMaster University and community allergy outpatient clinics in the greater Hamilton area. We examined 18 different variables from participants and used univariate and multivariable logistic regression analysis to determine how well these variables, singly and in combination, were able to predict clinical peanut allergy status. In Study 2, we conducted a retrospective chart review of a second cohort of 194 participants to investigate the reproducibility of our findings. This was a matched case–control study where 97 peanut-allergic participants were gender- and age-matched to 97 non-allergic control participants.

Results

Peanut skin prick test wheal size was the best predictor of clinical peanut allergy in both study cohorts. For every 1 mm increase in wheal size, the odds ratio of an individual having clinical peanut allergy was 2.36 in our first cohort and 4.85 in our second cohort. No other variable approached the predictive power of wheal size.

Conclusions

Peanut skin prick test wheal size is a robust predictor of clinical peanut reactivity. The findings of this study may be useful in guiding clinician decision-making regarding peanut allergy diagnostics.

Preparation and Analysis of Peanut Flour Used in Oral Immunotherapy Clinical Trials

BACKGROUND

Oral immunotherapy (OIT) is an investigational therapeutic approach for the treatment of food allergies. Characterization of the drug product used in oral immunotherapy trials for peanut allergy has not been reported.

OBJECTIVE

To quantify relative amounts of the major peanut allergens and microbial load present in peanut flour used in OIT trials and assess whether these parameters change over a 12-month period. We also anticipate that this report will serve as a guide for investigators seeking to conduct OIT trials under Food and Drug Administration-approved Investigational New Drug applications.

METHODS

Densitometric scanning of Ara h 1 and Ara h 2 resolved on SDS-PAGE gels was used to assess allergen content in peanut flour extracts. Microbial testing was conducted on peanut flour under US Pharmacopeia guidelines for the presence of Escherichia coli, salmonella, yeast, mold, and total aerobic bacteria. In addition, aflatoxin was quantified in peanut flour. Reported results were obtained from 4 unique lots of peanut flour.

RESULTS

Relative amounts of the major peanut allergens were similar between different lots of peanut flour and remained stable over a 12-month period. E coli and salmonella were absent from all lots of flour. Yeast, mold, total aerobic bacteria, and aflatoxin were within established US Pharmacopeia guidelines on all lots tested and remained within the criteria over a 12-month period.

CONCLUSIONS

Peanut flour used as a drug product contains the major peanut allergens and has low levels of potentially harmful microbes. Both these parameters remain stable over a 12-month period.

Peanut protein extraction conditions strongly influence yield of allergens Ara h 1 and 2 and sensitivity of immunoassays

The clinical importance of peanut (Arachis hypogaea) allergies demands standardized allergen extraction protocols. We determined the effectiveness of common extraction conditions (20 buffers, defatting reagents, extraction time/temperatures, processing, extraction repeats) on crude protein and Ara h 1 and 2 yields. Despite similar 1D-gel profiles, defatting with n-hexane resulted in significantly higher yields of crude protein, Ara h 1, and Ara h 2 than with diethyl ether. The yields were affected by the composition and pH of the extraction buffers and other conditions, but crude protein yield did not always correlate with Ara h 1 and 2 yields. Denaturants, reducing agents, acidic buffers, and thermal processing of peanuts perturbed allergen quantification in ELISAs, probably via exposure of additional epitopes. Allergen detection in 2D-Western blots with PBS resulted in greater sensitivity than with TBS or Tris. We recommend that allergen extraction conditions be selected based on the research question being investigated.

Heat processing of peanut seed enhances the sensitization potential of the major peanut allergen Ara h 6

SCOPE

Processing of food has been shown to impact IgE binding and functionality of food allergens. In the present study, we investigated the impact of heat processing on the sensitization capacity of Ara h 6, a major peanut allergen and one of the most potent elicitors of the allergic reaction.

METHODS AND RESULTS

Peanut extracts obtained from raw or heat-processed peanut and some fractions thereof were biochemically and immunochemically characterized. These extracts/fractions, purified Ara h 6, or recombinant Ara h 6 including Ara h 6 mutants lacking disulfide bridges were used in in vitro digestion tests and mouse models of experimental sensitization. Peanut roasting led to the formation of complexes of high molecular weight, notably between Ara h 6 and Ara h 1, which supported the induction of IgE specific to native Ara h 6. On the contrary, a fraction containing free monomeric 2S albumins or purified native Ara h 6 displayed no intrinsic allergenicity. In addition to complex formation, heat denaturation and/or partial destabilization enhanced Ara h 6 immunogenicity and increased its sensitivity to digestion.

CONCLUSION

These results suggest that sensitization potency and IgE binding capacity can be supported by different structures, modified and/or produced during food processing in interaction with other food constituents.

Three peanut-allergic/sensitized phenotypes with gender difference

BACKGROUND

Peanut-allergic reactions are heterogeneous ranging from mild symptoms to anaphylaxis.

OBJECTIVE

Identify peanut-allergic/sensitized phenotypes to personalize patient management.

METHODS

A combined factor and cluster analysis was used to study the phenotypes of 696 patients diagnosed with peanut sensitization and enrolled in the MIRABEL survey. The method was first applied to the 247 patients with an oral food challenge (OFC). It was then applied to the 449 patients without OFC to confirm the findings in an independent population.

RESULTS

Three independent clusters emerged from the OFC subgroup. Cluster 1, 'Severe peanut allergy with little allergic multi-morbidity' (123 subjects), had the highest proportion of patients with positive OFC (92%), a medium level of peanut protein inducing a positive OFC (235 mg), lower percentage of allergic multi-morbidity (2% asthma plus atopic dermatitis (A + AD), no cases of A + AD + multiple food allergies (MFA)). Cluster 2, 'Severe peanut allergy with frequent allergic multi-morbidity' (62 subjects), had a high proportion of patients with positive OFC (85%) with the lowest level of peanut protein inducing a positive OFC (112 mg), 89% allergic subjects, 100% with allergic multi-morbidity (A + AD) and 84% with A + AD + MFA. Cluster 3, 'Mild peanut-allergic/sensitized phenotype' (62 subjects), had the lowest mean age, the lowest proportion of patients with positive OFC (53%) with a high level of peanut protein inducing a positive OFC (770 mg), a low percentage of allergic multi-morbidity (48% A + AD + MFA). The two severe peanut-allergic phenotypes were more frequent in girls. The same clusters were found in the subgroup of patients without OFC.

CONCLUSION & CLINICAL RELEVANCE

Besides the classic markers associated with lower threshold doses of OFC (such as SPT and rAra h 2), allergic multi-morbidity and female gender should also be taken into account to better adapt the progressive dosage of provocation tests.

Prospective investigation on the transfer of Ara h 2, the most potent peanut allergen, in human breast milk

BACKGROUND

Peanut allergy is one of the most severe food allergies. Whether breastfeeding induces tolerance to peanuts or on the contrary, pre-disposes at risk-babies to occult allergic sensitization to peanuts is still a matter of discussion. We sought to investigate the transfer of the most potent peanut allergen Ara h 2 into human breast milk in a German breast milk study and to shed light on the time kinetics of Ara h 2 appearance.

METHODS

We recruited 32 lactating, non-peanut-allergic women and collected breast milk samples at different time points after consumption of 100 g dry roasted peanuts. Breast milk samples were investigated for Ara h 2 with different immunological methods: by 2D immunoblotting with a patient's serum, by affinity enrichment using a monoclonal antibody against Ara h 2 followed by LC-MS/MS-based detection and by a competitive inhibition ELISA for the detection of Ara h 2 and its digestion-resistant peptides (DRP-Ara h 2).

RESULTS

In a qualitative analysis, Ara h 2 could be identified in a breast milk sample by 2D immunoblot by means of a patient's serum and furthermore by immunoaffinity enrichment followed by LC-MS/MS analysis. In a semi-quantitative analysis, Ara h 2 and its digestion-resistant peptides were detected in the breast milk of 9 of 32 subjects. Evidence suggests that Ara h 2 is excreted individually either rapidly (after 1, 2, 3 or 4 h) or delayed (after 8 or 12 h) and in different concentrations.

CONCLUSIONS

Time and concentration of secreted Ara h 2 in breast milk appears to be individually regulated. The identification of Ara h 2 in breast milk is the prerequisite for the investigation of its sensitizing or tolerogenic properties.