Sensitization to acid-hydrolyzed wheat protein by transdermal administration to BALB/c mice, and comparison with gluten

Glutenin from the Ancient Wheat Progenitor Is Intrinsically Allergenic as It Can Clinically Sensitize Mice for Systemic Anaphylaxis by Activating Th2 Immune Pathway

Wheat allergy is a major type of food allergy with the potential for life-threatening anaphylactic reactions. Common wheat, Triticum aestivum (hexaploid, AABBDD genome), was developed using tetraploid wheat (AABB genome) and the ancient diploid wheat progenitor (DD genome)-Aegilops tauschii. The potential allergenicity of gluten from ancient diploid wheat is unknown. In this study, using a novel adjuvant-free gluten allergy mouse model, we tested the hypothesis that the glutenin extract from this ancient wheat progenitor will be intrinsically allergenic in this model. The ancient wheat was grown, and wheat berries were used to extract the glutenin for testing. A plant protein-free colony of Balb/c mice was established and used in this study. The intrinsic allergic sensitization potential of the glutenin was determined by measuring IgE response upon transdermal exposure without the use of an adjuvant. Clinical sensitization for eliciting systemic anaphylaxis (SA) was determined by quantifying the hypothermic shock response (HSR) and the mucosal mast cell response (MMCR) upon intraperitoneal injection. Glutenin extract elicited a robust and specific IgE response. Life-threatening SA associated and a significant MMCR were induced by the glutenin challenge. Furthermore, proteomic analysis of the spleen tissue revealed evidence of in vivo Th2 pathway activation. In addition, using a recently published fold-change analysis method, several immune markers positively and negatively associated with SA were identified. These results demonstrate for the first time that the glutenin from the ancient wheat progenitor is intrinsically allergenic, as it has the capacity to elicit clinical sensitization for anaphylaxis via activation of the Th2 pathway in vivo in mice.

Is Wheat Glutenin Extract Intrinsically Allergenic? Evaluation Using a Novel Adjuvant-Free Mouse Model of Systemic Anaphylaxis

Wheat is a prominent allergenic food that can trigger life-threatening anaphylaxis. Presently, it remains unclear whether wheat glutenin (WG) extract possesses inherent sensitization potential independently, without the use of adjuvants, and whether it can sensitize mice to the extent of inducing life-threatening systemic anaphylaxis. In this study, we tested the hypothesis that repeated skin exposures to WG extract without adjuvant will sensitize mice with the resultant anaphylactic reaction upon systemic WG challenge. Balb/c mice were bred and maintained on a strict plant protein-free diet and were repeatedly exposed to a WG extract or vehicle once a week for 9 weeks. WG-specific (s)IgE and total (t)IgE levels were quantified. Mice were challenged with WG extract to induce anaphylactic reactions as measured by hypothermic shock response (HSR) and mucosal mast cell degranulation response (MMCR). We also conducted proteomic analysis of 120 spleen immune markers. These skin-sensitized mice exhibited exposure-dependent IgE responses and near-fatal anaphylaxis upon challenge. Proteomic analysis identified seven dramatically elevated immune biomarkers in anaphylactic mice. These data reveal that WG is intrinsically allergenic, and that chronic skin exposure to WG extract can prime the mice for potentially fatal anaphylaxis.

Chronic application of alcohol-soluble gluten extract over undamaged skin causes clinical sensitization for life-threatening anaphylaxis via activation of systemic Th2 immune responses in mice

Introduction

Gluten allergy is a major public health problem that is growing at an alarming rate. Specific mechanisms underlying sensitization to gluten remain incompletely understood. Currently, it is unclear whether chronic exposure to alcohol-soluble gluten extract via undamaged skin has the capacity to clinically sensitize mice for life-threatening anaphylaxis. Using an adjuvant-free mouse model, here we tested the hypothesis that chronic application of alcohol-soluble durum gluten (ASDG) extract will clinically sensitize mice for life-threatening anaphylaxis.

Methods

This study was conducted in a gluten-free Balb/c mouse colony that was established and maintained on a plant protein-free diet. Groups of adult female mice were exposed dermally to ASDG extract or vehicle once a week for 9-weeks. Specific (s) and total (t) IgE levels were quantified. Mice were challenged systemically with ASDG to measure symptoms of systemic anaphylaxis. Hypothermic shock response (HSR) and mucosal mast cell degranulation response (MMCR) were determined upon challenge. Spleen Th1, Th2, and other immune markers were quantified.

Results

We found that chronic exposure to ASDG elicited robust elevation of sIgE and tIgE. Systemic challenge with ASDG, but not vehicle, elicited life-threatening anaphylaxis associated with dramatic HSR and MMCR. Correlation analysis demonstrated direct positive inter-relationships among IgE, HSR, and MMCR. Anaphylaxis was associated with significant elevation of prototypic Th2 but not Th1 immune markers in the spleen.

Discussion/Conclusion

Our study collectively demonstrates that ASDG is intrinsically allergenic; and chronic exposure to ASDG via undamaged skin can clinically sensitize mice for life-threatening anaphylaxis via activating the systemic Th2 immune responses.

The role of skin inflammation, barrier dysfunction, and oral tolerance in skin sensitization to gluten-derived hydrolysates in a rat model

BACKGROUND

Adverse reactions to wheat-containing skin care products have been linked to food allergy development.

OBJECTIVES

To determine the role of skin barrier dysfunction and inflammation in sensitization to gluten-derived hydrolysates via the skin in Brown Norway rats with and without oral tolerance to wheat.

METHODS

Skin barrier defect was induced by mechanical disruption, and skin inflammation was induced by topical application of SLS or MC903. Unmodified, enzyme hydrolyzed, or acid hydrolyzed gluten products were applied to the skin three times per week for 5 weeks. Subsequently, rats were orally gavaged with unmodified gluten.

RESULTS

Wheat-naïve rats were readily sensitized to gluten hydrolysates via the skin. Skin barrier defect and skin inflammation had little effect on the skin sensitization and hydrolysate-specific IgE levels. Oral administration of unmodified gluten promoted the production of unmodified gluten-specific IgE in rats sensitized via the skin. Sensitization through intact skin, disrupted skin barrier, or inflamed skin was unable to break tolerance to unmodified gluten in rats on a wheat-containing diet.

CONCLUSIONS

Mechanical skin barrier disruption and skin inflammation play a limited role in experimental skin sensitization to gluten-derived hydrolysates.

Preparation and in vitro-in vivo evaluation of QbD based acemetacin loaded transdermal patch formulations for rheumatic diseases

This research aimed to develop patches for transdermal delivery of acemetacin, which can be used to treat rheumatic diseasesand to determine their potential use. Patches were successfully created by solvent casting method using hydroxypropyl methylcellulose, propylene glycol, polyethylene glycol 400, tween 80, and dimethyl sulfoxide. Prepared patches were found using the Design of Experiments (DoE) method within the Quality by Design (QbD) approach. F1-ACM with a thickness of 0.1 ± 0.0 cm, a weight of 43.33 ± 6.29 mg, pH of 4.99 ± 0.24, moisture content of 18.33 ± 2.98%, a tensile strength of 9.196 ± 0.441 Mpa, elongation at break of 28.722 ± 0.803% and drug content of 100% was chosen as ideal formulation. 89.7% of ACM from F1-ACM was released in 5 min. F1-ACM significantly (p < 0.05) increased the response latency to the thermal stimulus at 90th (3.071 ± 0.517) and 120th (3.87 ± 0.332) min in the hot plate test. In the tail-flick experiment, F1-ACM significantly (p < 0.05) increased the reaction delay against heat stimuli at 90th (3.016 ± 0.695), 120th (2.884 ± 0.851), and 180th (2.893 ± 0.932) min. F1-ACM patch significantly (p < 0.001) inhibited paw edema formation at 1, 2, 3, 4, and 5 h after induction of inflammation as compared to the control group. Therefore, this formulation can be employed more efficiently for rheumatic disease.

An Adjuvant-Free Mouse Model Using Skin Sensitization Without Tape-Stripping Followed by Oral Elicitation of Anaphylaxis: A Novel Pre-Clinical Tool for Testing Intrinsic Wheat Allergenicity

Wheat is a major food allergen per the regulatory bodies of various nations. Hypersensitivity reactions to wheat have been steadily increasing for reasons that are not completely understood. Wheat-allergy models typically use adjuvants to induce sensitization to wheat proteins followed by an intraperitoneal challenge to elicit anaphylaxis. Although these models are very useful, they lack the ability to reveal the intrinsic allergenicity potential of wheat. To improve the mouse model of wheat allergy, we tested the hypothesis that repeated skin application of salt-soluble protein extract (SSPE) from durum wheat will clinically sensitize the mice to oral anaphylaxis to SSPE. Balb/c mice were bred and maintained on a plant-protein-free diet and used in the experiments. Adult female mice were exposed to SSPE once a week for 9 weeks via a solution on intact skin. Sensitization was measured by SSPE-specific IgE (sIgE) antibody and total IgE (tIgE) levels. Oral anaphylaxis was quantified by hypothermic shock response (HSR), and mucosal mast cell response (MMCR) was quantified by measuring MMCP-1 after oral challenge. Using single mouse data, correlation analyses were performed to determine the relationship among the allergenicity readouts. Spleen cytokines were quantified using a protein microarray method. Our results show that (i) repeated skin exposures to SSPE elicited robust increases in the sIgE and tIgE levels; (ii) skin exposure to SSPE was sufficient to sensitize mice for oral anaphylaxis and MMCR; (iii) both HSR and MMCR showed a strong correlation with each other, as well as with sIgE, and a modest correlation with tIgE levels; (iv) selected Th2/Th17/Th1 cytokines were elevated in skin-sensitized mice; and (v) oral allergen-challenged mice showed selective elevation of IL-6 and a panel of chemokines compared to saline-challenged mice. Together, we report the development and characterization of a novel adjuvant-free wheat-allergy mouse model that uses skin sensitization without tape-stripping followed by oral elicitation of anaphylaxis. Furthermore, validation of quantifiable wheat allergenicity readouts makes this model particularly suitable as a pre-clinical testing tool to assess the intrinsic sensitization/oral-anaphylaxis elicitation potential of novel wheat proteins (e.g., processed wheat) and to develop hypo/non-allergenic wheat products.

Acid Hydrolysis of Gluten Enhances the Skin Sensitizing Potential and Drives Diversification of IgE Reactivity to Unmodified Gluten Proteins

SCOPE

Personal care products containing hydrolyzed gluten have been linked to spontaneous sensitization through the skin, however the impact of the hydrolysate characteristics on the sensitizing capacity is generally unknown.

METHODS AND RESULTS

The physicochemical properties of five different wheat-derived gluten products (one unmodified, one enzyme hydrolyzed, and three acid hydrolyzed) are investigated, and the skin sensitizing capacity is determined in allergy-prone Brown Norway rats. Acid hydrolyzed gluten products exhibited the strongest intrinsic sensitizing capacity via the skin. All hydrolyzed gluten products induced cross-reactivity to unmodified gluten in the absence of oral tolerance to wheat, but were unable to break tolerance in animals on a wheat-containing diet. Still, the degree of deamidation in acid hydrolyzed products is associated with product-specific sensitization in wheat tolerant rats. Sensitization to acid hydrolyzed gluten products is associated with a more diverse IgE reactivity profile to unmodified gluten proteins compared to sensitization induced by unmodified gluten or enzyme hydrolyzed gluten.

CONCLUSION

Acid hydrolysis enhances the skin sensitizing capacity of gluten and drives IgE reactivity to more gluten proteins. This property of acid hydrolyzed gluten may be related to the degree of product deamidation, and could be a strong trigger of wheat allergy in susceptible individuals.

Assessment of Immune Responses in an Animal Model of Wheat Food Allergy via Epicutaneous Sensitization

Wheat allergy is a pathological event involving immunocompetent cells against ingested wheat allergen and is clearly associated with transdermal sensitization. However, the molecular mechanisms involved in the disease etiology are not completely understood. A complex cellular and tissue network linking to food allergy makes it difficult to understand the molecular mechanism of allergenicity. Animal models are valuable tools to deduce basic principles of human disease without invasive intervention trials. A mouse model of wheat allergy has provided insights into effects of skin exposure to wheat protein; it is a plausible route of human sensitization for wheat anaphylaxis. Further investigation of this model will capture the essential occurrence and flow of events, bringing useful clues to develop effective treatment and control strategies against wheat allergy. Here, we describe a method for analyzing the expression of cell surface molecules in single cells isolated from lymphoid tissue with flow cytometry. Sensitization by wheat extracts significantly increases antigen-specific T cells in the spleen. Collecting information regarding the contribution of immune cells to allergic sensitization in the development of wheat allergy would be useful in preventing and treating food allergies.

Bovine β-lactoglobulin-induced passive systemic anaphylaxis model using humanized NOG hIL-3/hGM-CSF transgenic mice

Food allergy is a common disease caused by intake of allergen-containing foods, such as milk, eggs, peanuts and wheat. Systemic anaphylaxis is a severe hypersensitive allergic reaction resulting from degranulation of mast cells or basophils after cross-linking of surface high-affinity IgE receptors (Fcε-RI) with allergen-specific IgE and allergens. In this study, we developed a novel human mast cell/basophil-engrafted mouse model that recapitulates systemic anaphylaxis triggered by β-lactoglobulin (BLG), a major allergen found in cow's milk. Human CD34+ hematopoietic stem cells were transferred into NOG (non-Tg) or NOG hIL-3/hGM-CSF transgenic (Tg) mice. After 14-16 weeks, bovine BLG-specific human IgE was intravenously injected into humanized mice, followed by intravenous or oral bovine BLG exposure 1 day later. Body temperature in Tg, but not in non-Tg, mice gradually decreased within 10 min, and 80% of Tg mice died within 1 h by intravenous BLG exposure. Serum histamine levels and anaphylaxis scores in Tg mice were markedly increased compared to non-Tg mice. Furthermore, these allergic symptoms were significantly inhibited by epinephrine treatment of the Tg mice. Therefore, the current NOG hIL-3/hGM-CSF Tg mouse model may be useful for development of novel anaphylaxis drugs for treatment of food allergies and for safety assessment of low-allergenicity extensively hydrolyzed cow's milk whey protein-based infant formulas.

An acid-hydrolyzed wheat protein activates the inflammatory and NF-κB pathways leading to long TSLP transcription in human keratinocytes

Hydrolyzed wheat proteins (HWPs) contained in cosmetics have occasionally caused immediate-type hypersensitivity following repeated skin exposure. Although the Cosmetic Ingredient Review Expert Panel concluded that < 3,500 Da HWP is safe for use in cosmetics, it remains biologically unknown how allergenic HWPs evoke immediate-type allergy percutaneously. Keratinocyte-derived thymic stromal lymphopoietin (TSLP) induces type 2 immune responses, which play an essential role in the pathogenesis of immediate-type allergy. Previously, we demonstrated that protein allergens in cultured human keratinocytes strongly induced long-form TSLP (loTSLP) transcription. However loTSLP-regulating signaling by HWP is poorly understood. In this study, we performed global gene expression analysis by microarray to investigate how the allergenic HWP acts on epidermal keratinocytes and the induction of loTSLP. Compared to human serum albumin (HSA), allergenic HWP induced a distinct gene expression pattern and preferentially activated various inflammatory pathways (High Mobility Group Box 1, Interleukin [IL]-6, IL-8, and acute phase response signaling). We identified 85 genes as potential nuclear factor-kappa B (NF-κB) target genes in GP19S-treated cells, compared with 29 such genes in HSA-treated cells. In addition, HWP specifically altered IL-17 signaling pathways in which transcription factors, NF-κB and activator protein-1, were activated. NF-κB signaling may be an important factor for HWP-induced inflammatory loTSLP transcription via inhibition assay. In conclusion, allergenic HWP caused an easily sensitizable milieu of activated inflammatory pathways and induced NF-κB-dependent loTSLP transcription in keratinocytes.

Allergenicity of Deamidated and/or Peptide-Bond-Hydrolyzed Wheat Gliadin by Transdermal Administration

Hydrochloric acid (HCl)-treated wheat protein (HWP) is widely used in various products, including foods, cosmetics and shampoos. Recently, immediate hypersensitivity towards facial soap containing HWP has been reported. HCl treatment of protein causes hydrolysis not only of main-chain amide bonds (peptide-bond hydrolysis) but also of side-chain ones (deamidation). We have already reported that gliadin, the main allergen in wheat, reduces allergenicity and increases digestibility by deamidation, indicating that deamidation and peptide-bond hydrolysis are effective to reduce the allergenicity of wheat protein. However, transdermally administered HWP is assumed to induce sensitization to orally administered wheat protein even in those who have been taking wheat products daily before sensitization. The present study was conducted to examine which structural change is responsible for the induction of cutaneous sensitization by comparing the allergenicity of deamidated and/or peptide-bond-hydrolyzed wheat gliadin. Because we have developed a deamidation method without causing peptide-bond hydrolysis, only deamidated wheat gliadin is available. Therefore, after deamidated-only, hydrolyzed-only, and deamidated and hydrolyzed gliadins were transdermally administered to mice for several weeks, the corresponding gliadin was intraperitoneally administered and allergenicity was evaluated. Transdermal administration of deamidated and hydrolyzed gliadin induced severe allergic reaction, while that of deamidated-only and hydrolyzed-only gliadin showed almost no allergic response. This result indicates that both deamidation and peptide-bond hydrolysis are necessary to increase the allergenic potency of transdermally administered wheat gliadin.

Mechanisms of Wheat Allergenicity in Mice: Comparison of Adjuvant-Free vs. Alum-Adjuvant Models

Wheat protein is considered a major type of food allergen in many countries including the USA. The mechanisms of allergenicity of wheat proteins are not well understood at present. Both adjuvant-based and adjuvant-free mouse models are reported for this food allergy. However, it is unclear whether the mechanisms underlying wheat allergenicity in these two types of models are similar or different. Therefore, we compared the molecular mechanisms in a novel adjuvant-free (AF) model vs. a conventional alum-adjuvant (AA) model of wheat allergy using salt-soluble wheat protein (SSWP). In the AF model, Balb/cJ mice were sensitized with SSWP via skin exposure. In the AA model, mice were sensitized by an intraperitoneal injection of SSWP with alum. In both models, allergic reactions were elicited using an identical protocol. Robust IgE as well as mucosal mast cell protein-1 responses were elicited similarly in both models. However, an analysis of the spleen immune markers identified strikingly different molecular activation patterns in these two models. Furthermore, a number of immune markers associated with intrinsic allergenicity were also identified in both models. Since the AF model uses skin exposure without an adjuvant, the mechanisms in the AF model may more closely simulate the human wheat allergenicity mechanisms from skin exposure in occupational settings such as in the baking industry.

Gluten tolerance prevents oral sensitization with enzymatic or acid hydrolyzed gluten: A study in Brown Norway rats

Background

There are several reports describing allergy to hydrolyzed wheat products. After a large outbreak in Japan it was established that sensitization was caused by skin contact with acid hydrolyzed gluten in soap. It is still not clear if other forms of hydrolyzed gluten may sensitize, and if the skin is the only relevant route of sensitization in humans and to what extent oral tolerance to wheat play a role.

Objectives

The aim of the present study was to examine if wheat-tolerant rats may be sensitized via the oral or i.p. route when exposed to gluten, enzymatic or acid hydrolyzed gluten.

Methods

Brown Norway rats, tolerant to wheat, were dosed by three i.p. injections without adjuvant or by oral gavage daily for 35 days with the three gluten products, respectively. Sera were analyzed by ELISA for specific IgG1 and IgE. In addition inhibition and avidity ELISAs were performed. Results were compared to a similar study in rats naïve to wheat.

Results

More than half the animals had measurable IgG1 at the start of the dosing period. I.p. immunization resulted in significant specific IgG1 and IgE to the antigen used for immunization but significantly lower than in naïve rats. The results of inhibition and avidity ELISA’s indicate that the underlying tolerance to epitopes common to the three products influences the immune response. Oral dosing did not induce significant changes in response to either gluten or the hydrolyzed gluten product used for dosing.

Conclusions

The study shows that i.p. immunization with the three products can break the underlying tolerance to wheat. Exposure by the oral route to enzymatic or acid hydrolyzed gluten is very unlikely to break an already established tolerance to gluten and induce sensitization.

Deamidation and Enzymatic Hydrolysis of Gliadins Alter Their Processing by Dendritic Cells in Vitro

Gliadins are major wheat allergens. Their treatment by acid or enzymatic hydrolysis has been shown to modify their allergenic potential. As the interaction of food proteins with dendritic cells (DCs) is a key event in allergic sensitization, we wished to investigate whether deamidation and enzymatic hydrolysis influence gliadin processing by DC and to examine the capacity of gliadins to activate DCs. We compared the uptake and degradation of native and modified gliadins by DCs using mouse bone marrow-derived DCs. We also analyzed the effects of these interactions on the phenotypes of DCs and T helper (Th) lymphocytes. Modifying gliadins induced a change in physicochemical properties (molecular weight, hydrophobicity, and sequence) and also in the peptide size. These alterations in turn led to increased uptake and intracellular degradation of the proteins by DCs. Native gliadins (NGs) (100 μg/mL), but not modified gliadins, increased the frequency of DC expressing CD80 (15.41 ± 2.36% vs 6.81 ± 1.10%, p < 0.001), CCR7 (28.53 ± 8.17% vs 17.88 ± 2.53%, p < 0.001), CXCR4 (70.14 ± 4.63% vs 42.82 ± 1.96%, p < 0.001), and CCR7-dependent migration (2.46 ± 1.45 vs 1.00 ± 0.22, p < 0.01) compared with NGs. This was accompanied by Th lymphocyte activation (30.37 ± 3.87% vs 21.53 ± 3.14%, p < 0.1) and proliferation (16.39 ± 3.97% vs 9.31 ± 2.80%, p > 0.1). Moreover, hydrolysis decreases the peptide size and induces an increase in gliadin uptake and degradation. Deamidation and extensive enzymatic hydrolysis of gliadins modify their interaction with DCs, leading to alteration of their immunostimulatory capacity. These findings demonstrate the strong relationship between the biochemical characteristics of proteins and immune cell interactions.

Advances in Molecular Mechanisms of Wheat Allergenicity in Animal Models: A Comprehensive Review

The prevalence of wheat allergy has reached significant levels in many countries. Therefore, wheat is a major global food safety and public health issue. Animal models serve as critical tools to advance the understanding of the mechanisms of wheat allergenicity to develop preventive and control methods. A comprehensive review on the molecular mechanisms of wheat allergenicity using animal models is unavailable at present. There were two major objectives of this study: To identify the lessons that animal models have taught us regarding the molecular mechanisms of wheat allergenicity and to identify the strengths, challenges, and future prospects of animal models in basic and applied wheat allergy research. Using the PubMed and Google Scholar databases, we retrieved and critically analyzed the relevant articles and excluded celiac disease and non-celiac gluten sensitivity. Our analysis shows that animal models can provide insight into the IgE epitope structure of wheat allergens, effects of detergents and other chemicals on wheat allergenicity, and the role of genetics, microbiome, and food processing in wheat allergy. Although animal models have inherent limitations, they are critical to advance knowledge on the molecular mechanisms of wheat allergenicity. They can also serve as highly useful pre-clinical testing tools to develop safer genetically modified wheat, hypoallergenic wheat products, novel pharmaceuticals, and vaccines.

Safety Assessment of Hydrolyzed Wheat Protein and Hydrolyzed Wheat Gluten as Used in Cosmetics

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) reviewed the product use, formulation, and safety data on hydrolyzed wheat protein and hydrolyzed wheat gluten, which function as skin- and hair-conditioning agents. The Panel determined that data from clinical and laboratory studies were sufficient to demonstrate that these ingredients will not elicit type 1 immediate hypersensitivity reactions in sensitized individuals and will not induce sensitization when the polypeptide lengths of the hydrolysates do not exceed 30 amino acids. The Panel concluded that hydrolyzed wheat gluten and hydrolyzed wheat protein are safe for use in cosmetics when formulated to restrict peptides to an average molecular weight of 3,500 Da or less.

Plant and Microalgae Derived Peptides Are Advantageously Employed as Bioactive Compounds in Cosmetics

Bioactive peptides (BP) are specific protein fragments that are physiologically important for most living organisms. It is proven that in humans they are involved in a wide range of therapeutic activities as antihypertensive, antioxidant, anti-tumoral, anti-proliferative, hypocholesterolemic, and anti-inflammatory. In plants, BP are involved in the defense response, as well as in the cellular signaling and the development regulation. Most of the peptides used as ingredients in health-promoting foods, dietary supplements, pharmaceutical, and cosmeceutical preparations are obtained by chemical synthesis or by partial digestion of animal proteins. This makes them not fully accepted by the consumers because of the risks associated with solvent contamination or the use of animal derived substances. On the other hand, plant and microalgae derived peptides are known to be selective, effective, safe, and well tolerated once consumed, thus they have got a great potential for use in functional foods, drugs, and cosmetic products. In fact, the interest in the plant and microalgae derived BP is rapidly increasing and in this review, we highlight and discuss the current knowledge about their studies and applications in the cosmetic field.

An Animal Model for Wheat Allergy Skin Sensitisation: A Comparative Study in Naive versus Tolerant Brown Norway Rats

BACKGROUND

Allergic sensitisation to foods may occur in infancy without prior oral exposure to the offending food, leading to the assumption that food allergy sensitisation may occur through the skin. Concerns have been raised regarding the safety of use of personal care products containing hydrolysed wheat proteins, since these products have been shown to induce allergy through the skin, and even cause an abrogation of an already established oral tolerance.

OBJECTIVE

To establish an animal model for food allergy skin sensitisation and compare the sensitising capacity of an unmodified and an acid-hydrolysed gluten product via slightly damaged skin in naïve versus tolerant rats.

METHODS

Gluten products were applied on the slightly damaged skin of naïve or tolerant Brown Norway (BN) rats without adjuvant 3 times per week for 3 or 5 consecutive weeks. The effect of the skin applications was evaluated by means of different ELISAs and immunoblotting.

RESULTS

A robust animal model was developed for food allergy skin sensitisation. In naïve rats, both gluten products were able to induce a statistically significant level of specific antibodies and sensitise through the skin, but in the wheat-tolerant rats, only the acid-hydrolysed gluten was able to sensitise through the skin, albeit at a level much lower than in the naïve rats. Results showed that new epitopes had been developed as a result of acid hydrolysis but original epitopes were maintained. This may explain why only the acid-hydrolysed gluten could induce specific antibody responses in the tolerant animals.

CONCLUSIONS

This study showed that it is possible to sensitise BN rats through slightly damaged skin, and that the sensitising capacity is heavily influenced by the tolerance status of their immune system and the degree of modification of the wheat products.

Allergic reactions to hydrolysed wheat proteins: clinical aspects and molecular structures of the allergens involved

Wheat gluten can be chemically or enzymatically hydrolysed to produce functional ingredients useful in food and cosmetics. However severe allergies to hydrolysed wheat proteins (HWP) have been described in Europe and Japan since the early 2000's. Triggering proteins and IgE epitopes were described both for French and Japanese cohorts and appeared remarkably similar leading to define a new wheat allergic entity. Deamidation induced by functionalisation generate neo-allergens responsible for this particular allergy. This article aims to review the processes leading to deamidation and the clinical features of the patients suffering from this allergy. Then the molecular determinants involved in HWP-allergy were exhaustively described and hypothesis regarding the sensitizing mechanism of HWP-allergy are discussed. Finally, current regulation and tools aiming at managing this risk associated with HWP are presented.

Development and validation of a mouse-based primary screening method for testing relative allergenicity of proteins from different wheat genotypes

BACKGROUND

Wheat allergy is a major food allergy that has reached significant levels of global public health concern. Potential variation in allergenicity among different wheat genotypes is not well studied at present largely due to the unavailability of validated methods. Here, we developed and validated a novel mouse-based primary screening method for this purpose.

METHODS

Groups of Balb/c mice weaned on-to a plant protein-free diet were sensitized with salt-soluble protein (SSP) extracted from AABB genotype of wheat (durum, Carpio variety). After confirming clinical sensitization for anaphylaxis, mice were boosted 7 times over a 6-month period. Using a pooled-plasma mini bank, a wheat-specific IgE-inhibition (II)-ELISA was optimized. Then the relative allergenicity of SSPs from tetraploid (AABB), hexaploid (AABBDD) and diploid (DD) wheat genotypes were determined. The IC₅₀/IC₇₅ values were estimated using IgE inhibition curves.

RESULTS

The optimized II-ELISA with an inhibition time of 2.5 h had a co-efficient of variation of <2%. Primary screening for relative allergenicity demonstrated that IgE binding to AABB-SSP was significantly abolished by the other two wheat genotypes. Compared to AABB, the relative allergenicity of SSPs of AABBDD and DD were significantly lower (p < .01). Furthermore, IgE inhibition curves showed significant differences in IC₅₀ and IC₇₅ values among the three wheat genotypes.

CONCLUSION

We report a novel mouse-based primary screening method of testing relative allergenicity of wheat proteins from three different wheat genotypes for the first time. This method is expected to have broad applications in wheat allergy research.

Lipopolysaccharide interferes with the use of the human Cell Line Activation Test to determine the allergic potential of proteins

It was believed that high molecular weight molecules including proteins cannot penetrate the skin. However, protein penetration through disrupted/ruptured skin has been reported recently, thus carrying the potential for inducing an allergic response. We used the human Cell Line Activation Test (h-CLAT), an in vitro skin sensitization test, to assess the allergic potential of proteins by measuring levels of CD86 and CD54 in the human monocytic leukemia cell line THP-1. Six allergens including ovalbumin (OVA) and human serum albumin (HSA; negative control) upregulated CD86 and/or CD54; a false-positive result was obtained using HSA. This was caused by lipopolysaccharide (LPS) contamination. Naturally derived materials often include LPS at various concentrations and may influence protein induction of CD86 and CD54. Additionally, polymyxin B, an LPS inhibitor, could not completely overcome the effect of LPS. Therefore, if test proteins contain ≥0.1 EU/mL LPS, their allergenic potency will not be assessed accurately using h-CLAT. These data show that naturally occurring materials or those derived from living organisms should be evaluated for their LPS content. It is important to confirm the applicability of in vitro methods such as h-CLAT for assessing the allergenic potency of naturally occurring proteins; our findings can be a foundation for future studies.

A chimeric IgE that mimics IgE from patients allergic to acid-hydrolyzed wheat proteins is a novel tool for in vitro allergenicity assessment of functionalized glutens

Background

Acid-hydrolyzed wheat proteins (acid-HWPs) have been shown to provoke severe allergic reactions in Europe and Japan that are distinct from classical wheat allergies. Acid-HWPs were shown to contain neo-epitopes induced by the deamidation of gluten proteins. However, products with variable rates of deamidation can be found.

Objectives

In this work, we studied the effect of the extent of wheat proteins deamidation on its allergenicity. A recombinant chimeric IgE was produced and compared to patients’ IgE for its capacity to assess the IgE-mediated triggering potential of acid-HWPs.

Methods

Sera from acid-HWP allergic patients were analyzed via ELISA and a functional basophil assay for their IgE reactivity to wheat proteins with different deamidation levels. A chimeric mouse/human IgE (chIgE-DG1) specific for the main neo-epitope, QPEEPFPE, involved in allergy to acid-HWPs was characterized with respect to its functionality and its reactivity compared to that of patients’ IgE.

Results

Acid-HWPs with medium (30%) and high (50–60%) deamidation levels displayed a markedly stronger IgE binding and capacity to activate basophils than those of samples with weak (15%) deamidation levels. The monoclonal chIgE-DG1 allowed basophil degranulation in the presence of deamidated wheat proteins. ChIgE-DG1 was found to mimic patients’ IgE reactivity and displayed the same ability to rank acid-HWP products in a degranulation assay.

Conclusion

Increasing the deamidation level of products from 15% to 60% resulted in an approximately 2-fold increase in their antigenicity and a 100-fold increase in their eliciting potential. The chimeric ChIgE-DG1 may be a useful tool to evaluate functionalized glutens for their allergenic potential. By mimicking patient sera reactivity, chIgE-DG1 also provided data on the patients' IgE repertoire and on the functionality of certain repeated epitopes in gluten proteins.

A Mouse Model of Anaphylaxis and Atopic Dermatitis to Salt-Soluble Wheat Protein Extract

BACKGROUND

Wheat allergy and other immune-mediated disorders triggered by wheat proteins are growing at an alarming rate for reasons not well understood. A mouse model to study hypersensitivity responses to salt-soluble wheat protein (SSWP) extract is currently unavailable. Here we tested the hypothesis that SSWP extract from wheat will induce sensitization as well as allergic disease in mice.

METHODS

Female BALB/cJ mice were weaned onto a plant protein-free diet. The mice were injected a total of 4 times with an SSWP (0.01 mg/mouse) fraction extracted from durum wheat along with alum as an adjuvant. Blood was collected biweekly and SSWP-specific IgE (SIgE) and total IgE (TIgE) levels were measured using ELISA. Systemic anaphylaxis upon intraperitoneal injection with SSWP was quantified by hypothermia shock response (HSR). Mucosal mast cell degranulation was measured by the elevation of mMCP-1 in the blood. The mice were monitored for dermatitis. Skin tissues were used in histopathology and for measuring cytokine/chemokine/adhesion molecule levels using a protein microarray system.

RESULTS

Injection with SSWP resulted in time-dependent SIgE antibody responses associated with the elevation of TIgE concentration. Challenge with SSWP elicited severe HSR that correlated with a significant elevation of plasma mMCP-1 levels. Sensitized mice developed facial dermatitis associated with mast cell degranulation. Lesions expressed significant elevation of Th2/Th17/Th1 cytokines and chemokines and E-selectin adhesion molecule.

CONCLUSION

Here we report a mouse model of anaphylaxis and atopic dermatitis to SSWP extract that may be used for further basic and applied research on wheat allergy.

Evaluation of the cross-reactivity of antigens in Glupearl 19S and other hydrolysed wheat proteins in cosmetics

Background

In Japan, over 2000 users of a facial soap containing Glupearl 19S (GP19S), a hydrolysed wheat protein (HWP), developed immediate‐type systemic wheat allergy (HWP‐IWA), and ∼70% of them developed associated contact urticaria.

Objectives

We investigated whether HWP‐IWA patients cross‐react with other HWPs, and analysed HWP antigenic characteristics.

Methods

We used 10 types of HWP that are commercially available as cosmetic ingredients, and 16 subjects with HWP‐IWA. We performed an enzyme‐linked immunosorbent assay (ELISA) to evaluate the reactivity to each HWP, and western blotting to evaluate the characteristics of the antigens by using HWP‐IWA patients' serum IgE antibodies. We also performed prick tests with the HWPs.

Results

The patients reacted to four other HWPs in addition to GP19S, according to ELISA, and this was confirmed by strong reactions in the prick tests to the same four types of HWP. Smears of antigens with molecular weights ranging from the high range to the low range were seen on western blotting with the four HWPs that showed strong reactions in the ELISA and prick tests.

Conclusions

HWP‐IWA patients cross‐react with other HWPs. The antigens that they cross‐reacted to had a molecular weight distribution similar to that of GP19S present in the HWPs.

Update on food allergy

Food allergies are a global health issue with increasing prevalence. Allergic reactions can range from mild local symptoms to severe anaphylactic reactions. Significant progress has been made in diagnostic tools such as component-resolved diagnostics and its impact on risk stratification as well as in therapeutic approaches including biologicals. However, a cure for food allergy has not yet been achieved and patients and their families are forced to alter eating habits and social engagements, impacting their quality of life. New technologies and improved in vitro and in vivo models will advance our knowledge of the pathogenesis of food allergies and multicenter-multinational cohort studies will elucidate interactions between genetic background, lifestyle, and environmental factors. This review focuses on new insights and developments in the field of food allergy and summarizes recently published articles.

Update on skin allergy

Skin diseases with an allergic background such as atopic dermatitis, allergic contact dermatitis, and urticaria are very common. Moreover, diseases arising from a dysfunction of immune cells and/or their products often manifest with skin symptoms. This review aims to summarize recently published articles in order to highlight novel research findings, clinical trial results, and current guidelines on disease management. In recent years, an immense progress has been made in understanding the link between skin barrier dysfunction and allergic sensitization initiating the atopic march. In consequence, new strategies for treatment and prevention have been developed. Novel pathogenic insights, for example, into urticaria, angioedema, mastocytosis, led to the development of new therapeutic approaches and their implementation in daily patient care. By understanding distinct pathomechanisms, for example, the role of IL-1, novel entities such as autoinflammatory diseases have been described. Considerable effort has been made to improve and harmonize patient management as documented in several guidelines and position papers.

Epidemiological link between wheat allergy and exposure to hydrolyzed wheat protein in facial soap

BACKGROUND

Recent studies have highlighted the importance of extra-intestinal routes of sensitization to food-related allergens as the cause of epidemics of food allergy. Instances of Japanese women developing food allergy to wheat after exposure to hydrolyzed wheat protein (HWP) present in facial soap have been reported. However, the epidemiologic impact of these ingredients as a cause of food allergy has not been well studied.

METHODS

To clarify the epidemiological relationship between food allergy to wheat and contact exposure to HWP, a case-control study of Japanese women aged 20-54 years with self-reported wheat allergy (WA) (cases, n = 157) and age-matched control subjects without WA (controls, n = 449) was performed using a large-scale Web-based research panel. Subjects answered a Web-based questionnaire regarding the use of skin and hair care products, as well as other possible risk factors.

RESULTS

Current use of an HWP-containing facial soap (Cha no Shizuku; Yuka) was significantly associated with an increased risk of WA (adjusted odds ratio, 2.6; 95% confidence interval, 1.2-5.7; frequencies of current use in cases and controls; 11% and 6%, respectively). Use of Cha no Shizuku was more common in subjects with more recent-onset WA, implying that this soap may have contributed to the recent epidemic of WA.

CONCLUSIONS

An epidemiological relationship between WA and contact exposure to HWP has been documented. This study implicates a possible role of contact exposure to food-derived protein hydrolysates as a risk factor for the development of food allergy manifesting itself as anaphylaxis.

Acid hydrolysis of wheat gluten induces formation of new epitopes but does not enhance sensitizing capacity by the oral route: a study in "gluten free" Brown Norway rats

Background

Acid hydrolyzed wheat proteins (HWPs) are used in the food and cosmetic industry as emulsifiers. Cases of severe food allergic reactions caused by HWPs have been reported. Recent data suggest that these reactions are caused by HWPs produced by acid hydrolysis.

Objectives

To examine the sensitizing capacity of gluten proteins per se when altered by acid or enzymatic hydrolysis relative to unmodified gluten in rats naïve to gluten.

Methods

High IgE-responder Brown Norway (BN) rats bred on a gluten-free diet were sensitized without the use of adjuvant to three different gluten products (unmodified, acid hydrolyzed and enzymatic hydrolyzed). Rats were sensitized by intraperitoneal (i.p.) immunization three times with 200 µg gluten protein/rat or by oral dosing for 35 days with 0.2, 2 or 20 mg gluten protein/rat/day. Sera were analyzed for specific IgG and IgE and IgG-binding capacity by ELISA. IgE functionality was measured by rat basophilic leukemia (RBL) assay.

Results

Regardless of the route of dosing, all products had sensitizing capacity. When sensitized i.p., all three gluten products induced a strong IgG1 response in all animals. Acid hydrolyzed gluten induced the highest level of specific IgE but with a low functionality. Orally all three gluten products induced specific IgG1 and IgE but with different dose-response relations. Sensitizing rats i.p. or orally with unmodified or enzymatic hydrolyzed gluten induced specific IgG1 responses with similar binding capacity which was different from that of acid hydrolyzed gluten indicating that acid hydrolysis of gluten proteins induces formation of ‘new’ epitopes.

Conclusions

In rats not tolerant to gluten acid hydrolysis of gluten enhances the sensitizing capacity by the i.p. but not by the oral route. In addition, acid hydrolysis induces formation of new epitopes. This is in contrast to the enzymatic hydrolyzed gluten having an epitope pattern similar to unmodified gluten.