Newly defined allergens in the WHO/IUIS Allergen Nomenclature Database during 01/2019-03/2021

Identification and semi-quantification of protein allergens in complex mixtures using proteomic and AllerCatPro 2.0 bioinformatic analyses: a proof-of-concept investigation

The demand for botanicals and natural substances in consumer products has increased in recent years. These substances usually contain proteins and these, in turn, can pose a risk for immunoglobulin E (IgE)-mediated sensitization and allergy. However, no method has yet been accepted or validated for assessment of potential allergenic hazards in such materials. In the studies here, a dual proteomic-bioinformatic approach is proposed to evaluate holistically allergenic hazards in complex mixtures of plants, insects, or animal proteins. Twelve commercial preparations of source materials (plant products, dust mite extract, and preparations of animal dander) known to contain allergenic proteins were analyzed by label-free proteomic analyses to identify and semi-quantify proteins. These were then evaluated by bioinformatics using AllerCatPro 2.0 (https://allercatpro.bii.a-star.edu.sg/) to predict no, weak, or strong evidence for allergenicity and similarity to source-specific allergens. In total, 4,586 protein sequences were identified in the 12 source materials combined. Of these, 1,665 sequences were predicted with weak or strong evidence for allergenic potential. This first-tier approach provided top-level information about the occurrence and abundance of proteins and potential allergens. With regards to source-specific allergens, 129 allergens were identified. The sum of the relative abundance of these allergens ranged from 0.8% (lamb's quarters) to 63% (olive pollen). It is proposed here that this dual proteomic-bioinformatic approach has the potential to provide detailed information on the presence and relative abundance of allergens, and can play an important role in identifying potential allergenic hazards in complex protein mixtures for the purposes of safety assessments.

Animal-derived food allergen: A review on the available crystal structure and new insights into structural epitope

Immunoglobulin E (IgE)-mediated food allergy is a rapidly growing public health problem. The interaction between allergens and IgE is at the core of the allergic response. One of the best ways to understand this interaction is through structural characterization. This review focuses on animal-derived food allergens, overviews allergen structures determined by X-ray crystallography, presents an update on IgE conformational epitopes, and explores the structural features of these epitopes. The structural determinants of allergenicity and cross-reactivity are also discussed. Animal-derived food allergens are classified into limited protein families according to structural features, with the calcium-binding protein and actin-binding protein families dominating. Progress in epitope characterization has provided useful information on the structural properties of the IgE recognition region. The data reveals that epitopes are located in relatively protruding areas with negative surface electrostatic potential. Ligand binding and disulfide bonds are two intrinsic characteristics that influence protein structure and impact allergenicity. Shared structures, local motifs, and shared epitopes are factors that lead to cross-reactivity. The structural properties of epitope regions and structural determinants of allergenicity and cross-reactivity may provide directions for the prevention, diagnosis, and treatment of food allergies. Experimentally determined structure, especially that of antigen-antibody complexes, remains limited, and the identification of epitopes continues to be a bottleneck in the study of animal-derived food allergens. A combination of traditional immunological techniques and emerging bioinformatics technology will revolutionize how protein interactions are characterized.

Advancing the allergenicity assessment of new proteins using a text mining resource

With a society increasingly demanding alternative protein food sources, new strategies for evaluating protein safety issues, such as allergenic potential, are needed. Large-scale and systemic studies on allergenic proteins are hindered by the limited and non-harmonized clinical information available for these substances in dedicated databases. A missing key information is that representing the symptomatology of the allergens, especially given in terms of standard vocabularies, that would allow connecting with other biomedical resources to carry out different studies related to human health. In this work, we have generated the first resource with a comprehensive annotation of allergens' symptomatology, using a text-mining approach that extracts significant co-mentions between these entities from the scientific literature (PubMed, ∼36 million abstracts). The method identifies statistically significant co-mentions between the textual descriptions of the two types of entities in the literature as indication of relationship. 1,180 clinical signs extracted from the Human Phenotype Ontology, the Medical Subject Heading terms of PubMed together with other allergen-specific symptoms, were linked to 1,036 unique allergens annotated in two main allergen-related public databases via 14,009 relationships. This novel resource, publicly available through an interactive web interface, could serve as a starting point for future manually curated compilation of allergen symptomatology.

Multiplexed transcriptional profiling of Dermatophagoides house dust mites allergens in human epithelium cells

Allergic asthma, a chronic disease characterized by airway inflammation, poses a significant public health concern. It is well-established that house dust mites (HDMs) are common inducers of allergic responses in individuals, particularly children. In central Taiwan, our research team observed that over 80% of allergic children exhibited sensitization to various HDMs species. This investigation aims to bridge the gap between these observations and a better understanding of the early fundamental mechanisms for preventing allergic diseases. Specifically, our study delves into the impact of crude extracts of HDMs on human epithelial BEAS-2B cells. Our findings, based on RNA sequencing (RNA-seq) analysis, shed light on how three major Dermatophagoides HDMs allergens activate a common Toll-like receptor signaling pathway in human epithelial cells within a 4-h treatment. During this process, the nuclear transcription factor NF-κB translocated into the cell nucleus within 30 min of allergen stimulation, triggering the expression of pro-inflammatory genes such as IL-6 and IL-8 over 4 h. Additionally, when the cells were treated with specific Dermatophagoides microceras (Der m) allergens, it resulted in the upregulation of genes that regulate type 1 diabetes mellitus (T1DM) signaling pathways. This led to the mediation of IL-12A inflammation. Furthermore, there was an increase in gene sets associated with cilia function and the microtubule cytoskeleton in human epithelial cells after treatment with a combination of Der m allergens and Dexamethasone. Additionally, OMICs analysis was conducted to examine the effects of HDMs allergenic stimulation on human epidermal cells. We aimed to improve our understanding of the molecular mechanisms within cells and identify potential targets and natural products in the treatment of asthma caused by HDMs allergens.

Anisakis simplex and urticaria. What we know about its real incidence and management in dermatological settings?

Acute or chronic infections have been described among causes of chronic urticaria (CU). Anisakidosis is a human disease caused by the ingestion of larval nematodes of the family Anisakidae. The infestation is acquired by eating raw seafood or undercooked fish and squid. There are considerable variations in the frequency of underlying causes in the different studies and in different countries, such as differences in diets and the prevalence of infections. Anisakis simplex has been recognized as a trigger of both acute and CU manifestations. However, there is still a lack of evidence about its management and treatment in dermatology. We, therefore, reviewed some biologic properties of Anisakis simplex in order to understand the relationship between its biology and the mechanism it uses to establish chronic dermatological conditions such as urticaria and cause late complications. In addition, we herein report some concerns about the effectiveness of systemic treatment in preventing complications and management in dermatological settings.

Effects of Flavourzyme and Alkaline Protease Treatment on Structure and Allergenicity of Peanut Allergen Ara h 1

Research background

Peanut allergy poses a significant threat to human health due to the increased risk of long-term morbidity at low doses. Modifying protein structure to affect sensitization is a popular topic.

Experimental approach

In this study, the purified peanut allergen Ara h 1 was enzymatically hydrolysed using Flavourzyme, alkaline protease or a combination of both. The binding ability of Ara h 1 to antibodies, gene expression and secretion levels of the proinflammatory factors interleukin-5 and interleukin-6 in Caco-2 cells was measured. Changes in the secondary and tertiary structures before and after treatment with Ara h 1 were analysed by circular dichroism and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

Results and conclusions

The results indicated a decrease of the allergenicity and proinflammatory ability of Ara h 1. The evaluation showed that the Flavourzyme and alkaline protease treatments caused particle shortening and aggregation. The fluorescence emission peak increased by 3.4-fold after the combined treatment with both proteases. Additionally, the secondary structure underwent changes and the hydrophobicity also increased 8.95-fold after the combined treatment.

Novelty and scientific contribution

These findings partially uncover the mechanism of peanut sensitization and provide an effective theoretical basis for the development of a new method of peanut desensitization.

Food Allergens of Plant and Animal Origin: Classification, Characteristics, and Properties

Food allergy is an adverse immune response to specific foods that can be either IgE-mediated or non-IgE mediated. The causes of IgE-mediated food allergy are multifactorial and involve genetic, dietary, and environmental factors. The prevalence of food allergy has increased over the last few decades, especially in urbanized, industrialized, and Westernized countries, and the epithelial barrier hypothesis has been recently suggested as a possible explanation for this increase. Food allergens of plant and animal origin are classified into a few families and superfamilies that are widely distributed and conserved. While it is known that food allergens share common properties, such as stability to enzymes and solubility, they also exhibit differential properties, and exceptions to the common characteristics exist. In recent years, novel characteristics of food allergens have been proposed based on their immunological properties and their ability to act as adjuvants or enhancers of the immune system.This chapter provides an overview of the current knowledge of food allergy, covering their prevalence, classification of food allergens from plant and animal origins, and recent advancements in the characterization of the properties of these allergens.

Microarray molecular mapping of horses with severe asthma

BACKGROUND

Severe asthma (SA) in horses, resembling human asthma, is a prevalent, debilitating allergic respiratory condition marked by elevated allergen-specific immunoglobulin E (IgE) against environmental proteins; however, research exploring the exposome's influence on IgE profiles is currently limited but holds paramount significance for diagnostic and therapeutic developments.

ANIMALS

Thirty-five sports horses were analyzed, consisting of environmentally matched samples from France (5 SA; 6 control), the United States (6 SA; 6 control), and Canada (6 SEA; 6 control).

METHODS

This intentional cross-sectional study investigated the sensitization profiles of SA-affected and healthy horses via serological antigen microarray profiling. Partial least square-discriminant analysis (PLS-DA) was used to identify and rank the importance of allergens for class separation (ie, affected/non-affected) as variable influence of projection (VIP), and allergen with commonality internationally established via frequency analysis.

RESULTS

PLS-DA models showed high discriminatory power in predicting SA in horses from Canada (area under the curve [AUC] 0.995) and France (AUC 0.867) but poor discriminatory power in horses from the United States (AUC 0.38). Hev b 5.0101, Cyn D, Der p 2, and Rum cr were the only shared allergens across all geographical groups.

CONCLUSIONS AND CLINICAL IMPORTANCE

Microarray profiling can identify specific allergenic components associated with SA in horses, while mathematical modeling of this data can be used for disease classification, highlighting the variability of sensitization profiles between geographical locations and emphasizing the importance of local exposure to the prevalence of different allergens. Frequency scoring analysis can identify important variables that contribute to the classification of SA across different geographical regions.

Immunoproteomics reveal increased serum IgG3/5 binding to Dermatophagoides and yeast protein antigens in severe equine asthma in a preliminary study

Introduction

Severe equine asthma (SEA) is a common, chronic respiratory disease of horses characterized by hyperreactivity to hay dust which has many similarities to severe neutrophilic asthma in humans. SEA-provoking antigens have not been comprehensively characterized, but molds and mites have been suggested as relevant sources. Here, we identified relevant antigen candidates using immunoproteomics with IgG isotype-binding analyses.

Methods

Proteins from Dermatophagoides pteronyssinus (Der p) were separated by two-dimensional gel electrophoresis followed by immunoblotting (2D immunoblots) resulting in a characteristic pattern of 440 spots. After serum incubation, antibody (Ig)-binding of all Ig (Pan-Ig) and IgG isotypes (type-2-associated IgG3/5, type-1-associated IgG4/7) was quantified per each spot and compared between asthmatic and healthy horses' sera (n=5 per group).

Results

Ig binding differences were detected in 30 spots. Pan-Ig binding was higher with asthmatics compared to healthy horses' sera on four spots, and IgG3/5 binding was higher on 18 spots. Small IgG4/7 binding differences were detected on 10 spots with higher binding with asthmatics' sera on four but higher binding with healthy horses' sera on six spots. Proteins from the spots with group differences including mite and yeast proteins were identified by liquid chromatography mass spectrometry. The latter likely originated from the feeding substrate of the Der p culture. Prioritized antigen candidates amongst the proteins identified were Der p 1, Der p 11, group 15 allergens, myosin heavy chain, and uncharacterized Der p proteins. Additionally, yeast enolases, alcohol dehydrogenase (ADH), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase, and heat shock proteins were prioritized. Eleven antigen candidates were tested for confirmation by ELISAs using the respective proteins separately. Differences in asthmatics vs. healthy horses' serum Ig binding to Der p 1, Der p 18, and three yeast enzymes (enolase, ADH, and PGK) confirmed these as promising antigens of immune responses in SEA.

Discussion

Antigens with relevance in SEA were newly identified by immunoproteomics, and yeast antigens were considered for SEA for the first time. Serum IgG3/5 binding to relevant antigens was increased in SEA and is a novel feature that points to increased type-2 responses in SEA but requires confirmation of the corresponding cellular responses.

Regulation of Macrophage Polarization in Allergy by Noncoding RNAs

Allergy is a type 2 immune reaction triggered by antigens known as allergens, including food and environmental substances such as peanuts, plant pollen, fungal spores, and the feces and debris of mites and insects. Macrophages are myeloid immune cells with phagocytic abilities that process exogenous and endogenous antigens. Upon activation, they can produce effector molecules such as cytokines as well as anti-inflammatory molecules. The dysregulation of macrophage function can lead to excessive type 1 inflammation as well as type 2 inflammation, which includes allergic reactions. Thus, it is important to better understand how macrophages are regulated in the pathogenesis of allergies. Emerging evidence highlights the role of noncoding RNAs (ncRNAs) in macrophage polarization, which in turn can modify the pathogenesis of various immune-mediated diseases, including allergies. This review summarizes the current knowledge regarding this topic and considers three classes of ncRNAs: microRNAs, long ncRNAs, and circular ncRNAs. Understanding the roles of these ncRNAs in macrophage polarization will provide new insights into the pathogenesis of allergies and identify potential novel therapeutic targets.

Allergenicity evaluation of quinoa proteins - A study in Brown Norway rats

The popularity of quinoa seeds has increased in the last decade due to their high nutritional value and natural gluten-free composition. Consumption of new proteins may pose a risk of introducing new allergies. In the present study the immunogenicity and sensitising capacity of quinoa proteins were assessed in a dose-response experiment in Brown Norway rats in comparison to proteins from spinach and peanut. Cross-reactivity between quinoa proteins and known allergens was evaluated by in silico analyses followed by analyses with 11 selected protein extracts and their anti-sera by means of ELISAs and immunoblotting. Further, an in vitro simulated gastro-duodenal digestion was performed. Quinoa proteins were found to have an inherent medium to high immunogenicity and sensitising capacity, being able to induce specific IgG1 and IgE levels higher than spinach but lower than peanut and elicit reactions of clinical relevance similar to peanut. Quinoa proteins were generally shown to resist digestion and retain capacity to bind quinoa-specific antibodies. Quinoa proteins were shown to be cross-reactive with peanut and tree nut allergens as high sequence homology and antibody cross-binding were demonstrated. Present study suggests that quinoa pose a medium to high level of allergenicity that should be further investigated in human studies.

The updated Structural Database of Allergenic Proteins (SDAP 2.0) provides 3D models for allergens and incorporated bioinformatics tools

Background

Allergenic proteins can cause IgE-mediated adverse reactions in sensitized individuals. Although the sequences of many allergenic proteins have been identified, bioinformatics data analysis with advanced computational methods and modeling is needed to identify the basis for IgE binding and cross-reactivity.

Objective

We aim to present the features and use of the updated Structural Database of Allergenic Proteins 2.0 (SDAP 2.0) webserver, a unique, publicly available resource to compare allergens using specially designed computational tools and new high-quality 3-D models for most known allergens.

Methods

Previously developed and novel software tools for identifying cross-reactive allergens using sequence and structure similarity are implemented in SDAP 2.0. A comprehensive set of high-quality 3-D models of most allergens was generated with the state-of-the-art AlphaFold 2 software. A graphics tool enables the interactive visualization of IgE epitopes on experimentally determined and modeled 3-D structures.

Results

A user can search for allergens similar to a given input sequence with the FASTA algorithm or the window-based World Health Organization/International Union of Immunological Societies (WHO/IUIS) guidelines on safety concerns of novel food products. Peptides similar to known IgE epitopes can be identified with the property distance tool and conformational epitopes by the Cross-React method. The updated database contains 1657 manually curated sequences including all allergens from the IUIS database, 334 experimentally determined X-ray or NMR structures, and 1565 3-D models. Each allergen/isoallergen is classified according to its protein family.

Conclusions

SDAP provides access to the steadily increasing information on allergenic structures and epitopes with integrated bioinformatics tools to identify and analyze their similarities. In addition to serving the research and regulatory community, it provides clinicians with tools to identify potential coallergies in a sensitive patient and can help companies to design hypoallergenic foods and immunotherapies.

Indoor aeroallergens from American cockroaches and mites initiate atopic march via cutaneous contact in a murine model

The progression of allergic diseases from atopic dermatitis in childhood to other allergic conditions such as asthma in later life is often referred to as the atopic march. In order to study the relationship between cutaneous sensitization by aeroallergen and atopic march, we established a mouse model to test the hypothesis using American cockroaches and house dust mites as the model allergens. Mice were sensitized via skin with native cockroach extract (CraA) or recombinant Per a 2 and Der p 2 proteins without adjuvant. Each mouse was subjected to a total of three 1-week patching sensitizations with a 2-week interval in between each application. The resulting immunological variables in sera, scratching behavior, airway hyperresponsiveness (AHR), and pathology of skin lesions and nasal mucosa were evaluated. In mice, application of CraA, rPer a 2, and rDer p 2 aeroallergens through skin patching induced significantly high levels of both total IgE and specific IgEs. The epicutaneous sensitization after a subsequent allergen challenge showed a significant increase in scratch bouts, AHR, epidermal thickness, and eosinophil counts in the skin compared with the control mice. In addition, stimulation of murine splenocytes with allergens increased higher levels of Th2 cytokines, anti-inflammatory cytokines, and chemokines excretion. Our study provides evidence supporting that epicutaneous sensitization to aeroallergens also led to nasal and airway symptoms comparable to atopic march as described in humans. We hope this new allergy model will be useful in the development of new preventive and therapeutic strategies aimed at stopping the atopic march.

Cross-reactive epitopes and their role in food allergy

Allergenic cross-reactivity among food allergens complicates the diagnosis and management of food allergy. This can result in many patients being sensitized (having allergen-specific IgE) to foods without exhibiting clinical reactivity. Some food groups such as shellfish, fish, tree nuts, and peanuts have very high rates of cross-reactivity. In contrast, relatively low rates are noted for grains and milk, whereas many other food families have variable rates of cross-reactivity or are not well studied. Although classical cross-reactive carbohydrate determinants are clinically not relevant, α-Gal in red meat through tick bites can lead to severe reactions. Multiple sensitizations to tree nuts complicate the diagnosis and management of patients allergic to peanut and tree nut. This review discusses cross-reactive allergens and cross-reactive carbohydrate determinants in the major food groups, and where available, describes their B-cell and T-cell epitopes. The clinical relevance of these cross-reactive B-cell and T-cell epitopes is highlighted and their possible impact on allergen-specific immunotherapy for food allergy is discussed.

Peanut Allergenicity: An Insight into Its Mitigation Using Thermomechanical Processing

Peanuts are the seeds of a legume crop grown for nuts and oil production. Peanut allergy has gained significant attention as a public health issue due to its increasing prevalence, high rate of sensitization, severity of the corresponding allergic symptoms, cross-reactivity with other food allergens, and lifelong persistence. Given the importance of peanuts in several sectors, and taking into consideration the criticality of their high allergic potential, strategies aiming at mitigating their allergenicity are urgently needed. In this regard, most of the processing methods used to treat peanuts are categorized as either thermal or thermomechanical techniques. The purpose of this review is to provide the reader with an updated outlook of the peanut’s allergens, their mechanisms of action, the processing methods as applied to whole peanuts, as well as a critical insight on their impact on the allergenicity. The methods discussed include boiling, roasting/baking, microwaving, ultrasonication, frying, and high-pressure steaming/autoclaving. Their effectiveness in alleviating the allergenicity, and their capacity in preserving the structural integrity of the treated peanuts, were thoroughly explored. Research data on this matter may open further perspectives for future relevant investigation ultimately aiming at producing hypoallergenic peanuts.

EAACI Molecular Allergology User's Guide 2.0

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

Cross-Serological Reaction of Glandless Cottonseed Proteins to Peanut and Tree Nut Allergic IgE

Food allergy is a potentially life-threatening health concern caused by immunoglobulin E (IgE) antibodies that mistakenly recognize normally harmless food proteins as threats. Peanuts and tree nuts contain several seed storage proteins that commonly act as allergens. Glandless cottonseed, lacking the toxic compound gossypol, is a new food source. However, the seed storage proteins in cottonseed may act as allergens. To assess this risk, glandless cottonseed protein extracts were evaluated for IgE binding by peanut and tree nut allergic volunteers. ELISA demonstrated that 25% of 32 samples had significant binding to cottonseed extracts. Immunoblot analysis with pooled sera indicated that IgE recognized a pair of bands migrating at approximately 50 kDa. Excision of these bands and subsequent mass-spectrometric analysis demonstrated peptide matches to cotton C72 and GC72 vicilin and legumin A and B proteins. Further, in silico analysis indicated similarity of the cotton vicilin and legumin proteins to peanut vicilin (Ara h 1) and cashew nut legumin (Ana o 2) IgE-binding epitopes among others. The observations suggest both the cotton vicilin and legumin proteins were recognized by the nut allergic IgE, and they should be considered for future allergen risk assessments evaluating glandless cottonseed protein products.

Identification of Potentially Tolerated Fish Species by Multiplex IgE Testing of a Multinational Fish-Allergic Patient Cohort

BACKGROUND

Although recent studies indicated that many fish-allergic patients may safely consume certain fish species, no clinical guidelines are available for identification of the exact species tolerated by specific patients.

OBJECTIVE

To investigate whether multiplex immunoglobulin E (IgE) testing reveals potentially tolerated fish through absence of IgE to parvalbumin (PV) and extracts from specific species.

METHODS

Sera from 263 clinically well-defined fish-allergic patients from Austria, China, Denmark, Luxembourg, Norway, and Spain were used in a research version of the ALEX² multiplex IgE quantification assay. Specific IgE to PVs from 10 fish species (9 bony and 1 cartilaginous), and to extracts from 7 species was quantified. The IgE signatures of individual patients and patient groups were analyzed using SPSS and R.

RESULTS

Up to 38% of the patients were negative to cod PV, the most commonly used molecule in fish allergy diagnosis. Forty-five patients (17%) tested negative to PVs but positive to the respective fish extracts, underlining the requirement for extracts for accurate diagnosis. Between 60% (Spain) and 90% (Luxembourg) of the patients were negative to PV and extracts from ray, a cartilaginous fish, indicating its potential tolerance. Up to 21% of the patients were negative to at least 1 bony fish species. Of the species analyzed, negativity to mackerel emerged as the best predictive marker of negativity to additional bony fish, such as herring and swordfish.

CONCLUSIONS

Parvalbumins and extracts from multiple fish species relevant for consumption should be used in fish-allergy diagnosis, which may help identify potentially tolerated species for individual patients.

Crustacean shellfish allergens: influence of food processing and their detection strategies

Despite the increasing popularity of crustacean shellfish among consumers due to their rich nutrients, they can induce a serious allergic response, sometimes even life-threatening. In the past decades, a variety of crustacean allergens have been identified to facilitate the diagnosis and management of crustacean allergies. Although food processing techniques can ease the risk of crustacean shellfish allergy, no available processing methods to tackle crustacean allergies thoroughly. Strict dietary avoidance of crustacean shellfish and its component is the best option for the protection of sensitized individuals, which should rely on the compliance of food labeling and, as such, on their verification by sensitive, reliable, and accurate detection techniques. In this present review, the physiochemical properties, structure aspects, and immunological characteristics of the major crustacean allergens have been described and discussed. Subsequently, the current research progresses on how various processing techniques cause the alterations and modifications in crustacean allergens to produce hypoallergenic crustacean food products were summarized and discussed. Particularly, various analytical methodologies employed in crustacean shellfish allergen detection, and the effect of food processing and matrix on these techniques, are also herein emphasized for the appropriate selection of analytical detection tools to safeguard consumers safety.

The Immune System Response to 15-kDa Barley Protein: A Mouse Model Study

Barley (Hordeum vulgare L.) proteins are taxonomically homologous to wheat proteins and react with sera from patients with baker’s asthma. In the current work, the crude extract of barley proteins was divided into six fractions on DEAE-Sepharose. Their immunoreactivity in reacting with sera from patients with a confirmed food allergy varied, and the 15-kDa fraction (B−FrVI) showed the strongest response. In silico analysis confirmed that 15-kDa B-FrVI protein belongs to the trypsin/amylase inhibitor family and to a group of MHC type II allergens. In the next step, the immunogenicity of the B-FrVI was examined in a mouse model. It was shown that, compared to the PBS group, administration of B-FrVI to mice induced almost 2× higher amounts of specific IgG, ~217, and IgA ~29, as early as day 28 after immunization, regardless of the route (intraperitoneal or oral) of antigen administration (p < 0.0001). An ELISpot for B-cell responses confirmed it. Stimulation of mesenteric lymphocytes with pure B-FrVI significantly increased (p < 0.001) the proliferation of lymphocytes from all groups compared to cells growing in media only and stimulated with lyophilized beer. The experiments prove the strong immunogenicity of the 15-kDa B-FrVI protein and provide a basis for future studies of the allergenic nature of this protein.

A native IgE in complex with profilin provides insights into allergen recognition and cross-reactivity

Allergies have become a rising health problem, where plentiful substances can trigger IgE-mediated allergies in humans. While profilins are considered minor allergens, these ubiquitous proteins are primary molecules involved in cross-reactivity and pollen-food allergy syndrome. Here we report the first crystal structures of murine Fab/IgE, with its chains naturally paired, in complex with the allergen profilin from Hevea brasiliensis (Hev b 8). The crystallographic models revealed that the IgE's six complementarity-determining regions (CDRs) interact with the allergen, comprising a rigid paratope-epitope surface of 926 Å2, which includes an extensive network of interactions. Interestingly, we also observed previously unreported flexibility at Fab/IgE's elbow angle, which did not influence the shape of the paratope. The Fab/IgE exhibits a high affinity for Hev b 8, even when using 1 M NaCl in BLI experiments. Finally, based on the encouraging cross-reactivity assays using two mutants of the maize profilin (Zea m 12), this antibody could be a promising tool in IgE engineering for diagnosis and research applications.

Food allergy across the globe

The prevalence of food allergy (FA) is increasing in some areas of the globe, highlighting the need for better strategies for prevention, diagnosis, and therapy. In the last few decades, we have made great strides in understanding the causes and mechanisms underlying FAs, prompting guideline updates. Earlier guidelines recommended avoidance of common food allergens during pregnancy and lactation and delaying the introduction of allergenic foods in children aged between 1 and 3 years. Recent guidelines for allergy prevention recommend consumption of a healthy and diverse diet without eliminating or increasing the consumption of allergenic foods during pregnancy or breast-feeding. Early introduction of allergenic foods is recommended by most guidelines for allergy prevention after a period of exclusive breast-feedng (6 months [World Health Organization] or 4 months [European Academy of Allergy and Clinical Immunology]). New diagnostics for FA have been developed with varied availability of these tests in different countries. Finally, the first oral immunotherapy drug for FA was approved by the US Food and Drug Administration and European Medicines Agency in 2020. In this review, we will address the global prevalence of FA, our current understanding of the causes of FA, and the latest guidelines for preventing, diagnosing, and treating FA. We will also discuss similarities and differences between FA guidelines.