Vicilin allergens of peanut and tree nuts (walnut, hazelnut and cashew nut) share structurally related IgE-binding epitopes

In vitro evaluation of digestive and endolysosomal enzymes to cleave CML-modified Ara h 1 peptides

Ara h 1 is a major peanut allergen. Processing-induced modifications may modulate the allergenic potency of Ara h 1. Carboxymethyl lysine (CML) modifications are a commonly described nonenzymatic modification on food proteins. In the current study, we tested the ability of digestive and endolysosomal proteases to cleave CML-modified and unmodified Ara h 1 peptides. Mass spectrometric analyses of the digested peptides demonstrate that carboxymethylation of lysine residues renders these peptides refractory to trypsin digestion. We did not detect observable differences in the simulated gastric fluid or endolysosomal digestion between the parental and CML-modified peptides. One of the tested peptides contains a lysine residue previously shown to be CML modified laying in a previously mapped linear IgE epitope, but we did not observe a difference in IgE binding between the modified and parental peptides. Our findings suggest a molecular mechanism for the increased resistance of peanut allergens modified by thermal processing, such as Ara h 1, to digestion in intestinal fluid after heating and could help explain how food processing-induced modifications may lead to more potent food allergens by acting to protect intact IgE epitopes from digestion by proteases targeting lysine residues.

Peanut allergy is common among hazelnut-sensitized subjects but is not primarily the result of IgE cross-reactivity

BACKGROUND

Hazelnut and peanut are botanically unrelated foods, but patients are often sensitized and allergic to both, for reasons that are not well understood.

METHODS

To investigate molecular cosensitization and cross-reactivity to peanut in hazelnut-sensitized individuals, children (n = 81) and adults (n = 80) were retrospectively selected based on sensitization to hazelnut. IgE to hazelnut extract, Cor a 1, 8, 9 and 14, to peanut extract, Ara h 1, 2, 3, 8 and 9, and to Bet v 1 was determined by ImmunoCAP. Allergy to hazelnut and peanut was established by DBPCFC and/or detailed clinical history. Patients were either tolerant or displayed subjective or objective symptoms to either food. IgE cross-reactivity between hazelnut and peanut storage proteins was assessed by reciprocal ImmunoCAP inhibition experiments.

RESULTS

Of the 161 hazelnut-sensitized subjects, 109 (68%) were also sensitized to peanut, and 73 (45%) had clinical expression of allergy to peanut that was not associated with the presence or severity of hazelnut allergy. Instead, it was associated with IgE reactivity to peanut storage proteins, in particular Ara h 2. No cross-reactivity could be detected between Ara h 2 and Cor a 14, and 2 of 13 subjects displayed extensive cross-reactivity between 11S globulins; in plasma of both individuals, Ara h 3 almost completely inhibited IgE binding to Cor a 9.

CONCLUSIONS

Peanut allergy is not primarily the result of IgE cross-reactivity to hazelnut storage proteins. IgE to Cor a 14 and Ara h 2 may serve as useful markers of primary sensitization to hazelnut and peanut, respectively.

The development of a standardised diet history tool to support the diagnosis of food allergy

The disparity between reported and diagnosed food allergy makes robust diagnosis imperative. The allergy-focussed history is an important starting point, but published literature on its efficacy is sparse. Using a structured approach to connect symptoms, suspected foods and dietary intake, a multi-disciplinary task force of the European Academy of Allergy and Clinical Immunology developed paediatric and adult diet history tools. Both tools are divided into stages using traffic light labelling (red, amber and green). The red stage requires the practitioner to gather relevant information on symptoms, atopic history, food triggers, foods eaten and nutritional issues. The amber stage facilitates interpretation of the responses to the red-stage questions, thus enabling the practitioner to prepare to move forward. The final green stage provides a summary template and test algorithm to support continuation down the diagnostic pathway. These tools will provide a standardised, practical approach to support food allergy diagnosis, ensuring that all relevant information is captured and interpreted in a robust manner. Future work is required to validate their use in diverse age groups, disease entities and in different countries, in order to account for differences in health care systems, food availability and dietary norms.

Walnut allergens: molecular characterization, detection and clinical relevance

Food-induced allergies have been regarded as an emergent problem of public health. Classified as important allergenic ingredients, the presence of walnut and other nuts as hidden allergens in processed foods constitutes a risk for sensitized individuals, being a real problem of allergen management. Attending to the increasing importance dedicated to walnut allergy, this review intends to provide the relevant and up-to-date information on main issues such as the prevalence of walnut allergy, the clinical threshold levels, the molecular characterization of walnut allergens and their clinical relevance, as well as the methodologies for walnut allergen detection in foods. As the walnut used in human diet comes from Juglans regia and Juglans nigra, the molecular characterization of the allergens from both species included in the prolamins (Jug r 1, Jug n 1 and Jug r 3), cupins (Jug r 2, Jug n 2 and Jug r 4) and profilins (Jug r 5), together with respective clinical relevance, were compiled in this review. The most recent progresses on walnut allergen detection techniques (protein- and DNA-based) are described and critically compared, including the emergent multitarget approaches.

Dubois AE, Gerth van Wijk R, Wichers HJ, de Jong NW. Systematic review on cashew nut allergy

Recent studies on cashew nut allergy suggest that the prevalence of cashew nut allergy is increasing. Cashew nut consumption by allergic patients can cause severe reactions, including anaphylaxis. This review summarizes current knowledge on cashew nut allergy to facilitate timely clinical recognition and to promote awareness of this emerging food allergy amongst clinicians. The goal of this study is to present a systematic review focused on the clinical aspects of allergy to cashew nut including the characteristics of cashew nut, the prevalence, allergenic components, cross-reactivity, diagnosis and management of cashew nut allergy. The literature search yielded 255 articles of which 40 met our selection criteria and were considered to be relevant for this review. The 40 articles included one prospective study, six retrospective studies and seven case reports. The remaining 26 papers were not directly related to cashew nut allergy. The literature suggests that the prevalence of cashew nut allergy is increasing, although the level of evidence for this is low. A minimal amount of cashew nut allergen may cause a severe allergic reaction, suggesting high potency comparable with other tree nuts and peanuts. Cashew allergy is clearly an underestimated important healthcare problem, especially in children.

Cross-reactivity of peanut allergens

Peanut seeds are currently widely used as source of human food ingredients in the United States of America and in European countries due to their high quality protein and oil content. This article describes the classification and molecular biology of peanut seed allergens with particular reference to their cross-reactivities. Currently, the IUIS allergen nomenclature subcommittee accepts 12 peanut allergens. Two allergens belong to the cupin and four to the prolamin superfamily, and six are distributed among profilins, Bet v 1-like proteins, oleosins, and defensins. Clinical observations frequently report an association of peanut allergy with allergies to legumes, tree nuts, seeds, fruits and pollen. Molecular cross-reactivity has been described between members of the Bet v 1-like proteins, the non-specific lipid transfer proteins, and the profilins. This review also addresses the less well-studied cross-reactivity between cupin and prolamin allergens of peanuts and of other plant food sources and the recently discovered cross-reactivity between peanut allergens of unrelated protein families.

Isolated IgE reactivity to native walnut vicilin-like protein (nJug r 2) on ISAC™ microarray is due to cross-reactive carbohydrate epitopes

BACKGROUND

The last version of the microarray-based testing ImmunoCAP ISAC 112™ includes the native walnut (Junglans regia) molecules 2S albumin (nJug r 1), vicilin (nJug r 2) and lipid transfer protein (nJug r 3). In view of the many unexpected cases of isolated positivity to nJug r 2 occurring in daily practice, we evaluated the association of these reactivities with clinical symptoms, as well as the relationship between sIgE and nJug r 2 and cross-reactive carbohydrate determinants (CCDs).

METHODS

Sera from 320 consecutive allergic outpatients tested by ImmuoCAP ISAC™ 112 were considered. The medical records of all nJug r 2 positive patients were reviewed to assess clinical symptoms related to walnut allergy. A linear regression analysis was performed to evaluate the correlation between nJug r 2 and CCDs (nMUXF3) sIgE values, and a CAP inhibition assay was carried out to confirm the possible cross-reactivity between CCDs and nJug r 2.

RESULTS

Thirty-seven out of 320 sera tested (11.6%) were positive to nJug r 2. Among them three (8.1%) and eight (21.6%) scored positive for nJug r 1 and nJug r 3 as well, respectively. Twenty-seven (73%) sera showed isolated nJug r 2 positivity. Only nJug r 1 reactors had symptoms referred to walnut allergy. Twenty-five/37 nJug r 2-positive sera (67.6%) showed a simultaneous positivity to nMUXF3 and a significant correlation (p<0.0001) between the IgE levels to nJug r 2 and nMUXF3 (r²=0.787). After incubation with nMUXF3 a complete inhibition of sIgE reactivity to both nMUXF3 and nJug r 2 was shown.

CONCLUSIONS

The unexpected isolated sIgE reactivity to nJug r 2 found by ImmunoCAP ISAC™ 112 is frequently related to reactivity to cross-reactive carbohydrate epitopes and it is lacking clinical significance.

Allergenic properties and differential response of walnut subjected to processing treatments

The aim of this study was to investigate changes in walnut allergenicity after processing treatments by in vitro techniques and physiologically relevant assays. The allergenicity of walnuts subjected to high hydrostatic pressure and thermal/pressure treatments was evaluated by IgE-immunoblot and antibodies against walnut major allergen Jug r 4. The ability of processed walnut to cross-link IgE on effector cells was evaluated using a rat basophil leukaemia cell line and by skin prick testing. Susceptibility to gastric and duodenal digestion was also evaluated. The results showed that walnuts subjected to pressure treatment at 256 kPa, 138 °C, were able to diminish the IgE cross-linking capacity on effector cells more efficiently than high pressure treated walnuts. IgE immunoblot confirmed these results. Moreover, higher susceptibility to digestion of pressure treated walnut proteins was observed. The use of processed walnuts with decreased IgE binding capacity could be a potential strategy for walnut tolerance induction.

Peanut allergens: an overview

Peanut is recognized as a potent food allergen producing one of the most frequent food allergies. This fact has originated the publication of an elevated number of scientific reports dealing with peanut allergens and, especially, the prevalence of peanut allergy. For this reason, the information available on peanut allergens is increasing and the debate about peanut allergy is always renewed. This article reviews the information currently available on peanut allergens and on the techniques used for their chemical characterization. Moreover, a general overview on the current biotechnological approaches used to reduce or eliminate peanut allergens is also provided.

Conformational epitope mapping of Pru du 6, a major allergen from almond nut

Tree nuts are a widely consumed food. Although enjoyed safely by most individuals, allergic reactions to tree nuts, including almond, are not uncommon. Almond prunin (Pru du 6), an 11S globulin (legumin), is an abundant nut seed protein and a major allergen. Conformational epitope mapping studies of prunin have been performed with a murine monoclonal antibody (mAb) 4C10. This mAb reacts with non-reduced but not reduced prunin in immunoblotting assays, indicating the recognition of a conformational epitope. 4C10 competes with patient IgE, as assessed by ELISA, indicating clinical significance of the epitope. To characterize the 4C10 epitope, hydrogen/deuterium exchange (HDX) monitored by 14.5 T Fourier transform ion cyclotron resonance mass spectrometry (MS) was performed on the native prunin-4C10 complex and on uncomplexed native prunin. Several epitope candidate peptides that differ in deuterium uptake between the complexed and uncomplexed forms were identified. The epitope was further mapped by analyzing chimeric molecules incorporating segments of the homologous soybean allergen, Gly m 6, in immunoassays. These data indicate that the 4C10 epitope overlaps with a subset of patient IgE binding epitopes on almond prunin and further supports HDX-MS as a valid technique for mapping conformational epitopes.

Assessment of 3D models for allergen research

Allergenic proteins must crosslink specific IgE molecules, bound to the surface of mast cells and basophils, to stimulate an immune response. A structural understanding of the allergen-IgE interface is needed to predict cross-reactivities between allergens and to design hypoallergenic proteins. However, there are less than 90 experimentally determined structures available for the approximately 1500 sequences of allergens and isoallergens cataloged in the Structural Database of Allergenic Proteins. To provide reliable structural data for the remaining proteins, we previously produced more than 500 3D models using an automated procedure, with strict controls on template choice and model quality evaluation. Here, we assessed how well the fold and residue surface exposure of 10 of these models correlated with recently published experimental 3D structures determined by X-ray crystallography or NMR. We also discuss the impact of intrinsically disordered regions on the structural comparison and epitope prediction. Overall, for seven allergens with sequence identities to the original templates higher than 27%, the backbone root-mean square deviations were less than 2 Å between the models and the subsequently determined experimental structures for the ordered regions. Further, the surface exposure of the known IgE epitopes on the models of three major allergens, from peanut (Ara h 1), latex (Hev b 2), and soy (Gly m 4), was very similar to the experimentally determined structures. For the three remaining allergens with lower sequence identities to the modeling templates, the 3D folds were correctly identified. However, the accuracy of those models is not sufficient for a reliable epitope mapping.

Ara h 1 structure is retained after roasting and is important for enhanced binding to IgE

SCOPE

Ara h 1 from roasted peanut binds higher levels of serum immunoglobulin E than raw peanuts and this is likely due to the Maillard reaction. While Ara h 1 linear IgE epitopes have been mapped, the presence and importance of structural epitopes is not clear.

METHODS AND RESULTS

Mass spectrometry, immunoblot, ELISA, circular dichroism (CD), and structural analysis were used to compare structural and subsequent IgE-binding differences in Ara h 1 purified from raw (N) and roasted peanuts (R) and denatured Ara h 1 (D). Although N and R had similar CD spectra, the latter bound significantly more IgE. Decreased IgE binding was seen with the loss of secondary structure. This same IgE-binding pattern [R > N > D] was seen for the sera of ten peanut allergic patients. While the majority of linear epitopes are located on surface and structured regions of Ara h 1, our study shows that conformational epitopes of Ara h 1 bind better to IgE than linear epitopes.

CONCLUSION

Enhanced IgE binding to roasted Ara h 1 could be due to alterations such as chemical modifications to individual amino acids or increased epitope exposure. IgE binding is significantly reduced with loss of structure.

Structural and immunologic characterization of Ara h 1, a major peanut allergen

Allergic reactions to peanuts and tree nuts are major causes of anaphylaxis in the United States. We compare different properties of natural and recombinant versions of Ara h 1, a major peanut allergen, through structural, immunologic, and bioinformatics analyses. Small angle x-ray scattering studies show that natural Ara h 1 forms higher molecular weight aggregates in solution. In contrast, the full-length recombinant protein is partially unfolded and exists as a monomer. The crystal structure of the Ara h 1 core (residues 170-586) shows that the central part of the allergen has a bicupin fold, which is in agreement with our bioinformatics analysis. In its crystalline state, the core region of Ara h 1 forms trimeric assemblies, while in solution the protein exists as higher molecular weight assemblies. This finding reveals that the residues forming the core region of the protein are sufficient for formation of Ara h 1 trimers and higher order oligomers. Natural and recombinant variants of proteins tested in in vitro gastric and duodenal digestion assays show that the natural protein is the most stable form, followed by the recombinant Ara h 1 core fragment and the full-length recombinant protein. Additionally, IgE binding studies reveal that the natural and recombinant allergens have different patterns of interaction with IgE antibodies. The molecular basis of cross-reactivity between vicilin allergens is also elucidated.

Walnut allergy in peanut-allergic patients: significance of sequential epitopes of walnut homologous to linear epitopes of Ara h 1, 2 and 3 in relation to clinical reactivity

BACKGROUND

Peanut allergy is a frequent and potentially life-threatening food allergy. Despite the large taxonomic distance between the plants, peanut-allergic patients often react to tree nuts such as walnuts. While the allergens of peanut and walnut have a high degree of homology in their amino-acid sequences, it is unknown whether this similarity is responsible for the observed co-reactivity. Therefore, we analyzed the binding of specific IgE antibodies to sequential epitopes of peanut and walnut in peanut-allergic patients with and without walnut allergy.

METHODS

The IgE binding to previously described sequential epitopes of peanut and the homologous regions of walnut was assessed in 32 peanut-allergic patients using a peptide microarray technology. Twelve patients had a clinically relevant walnut allergy and 20 were tolerant to walnut. Inhibition assays with peanut peptides and corresponding walnut sequences were performed to show specific binding to sequential epitopes.

RESULTS

No differences in the recognition of sequential epitopes could be found between peanut-allergic patients with or without walnut allergy. Only a few patients showed IgE binding to walnut sequences that corresponded to sequential epitopes of peanut. In the inhibition assays, no relevant cross-reacting IgE antibodies could be detected for the peptides analyzed.

CONCLUSION

Our results indicate that although they share a rather high degree of homology with the corresponding regions of walnut allergens, the sequence stretches previously identified as sequential IgE binding epitopes of Ara h 1, Ara h 2 and Ara h 3 have no IgE binding equivalents in walnut allergens.

Impact of Maillard reaction on immunoreactivity and allergenicity of the hazelnut allergen Cor a 11

Few studies exist on the influence of processing methods on structural changes and allergenic potential of hazelnut proteins. This study focused on the effect of glycation (Maillard reaction) on the immunoreactivity and degranulation capacity of the purified hazelnut 7S globulin, Cor a 11. After heating, the extent of the Maillard reaction, sensitivity to proteolysis, binding of human IgE or rabbit IgG, and degranulation capacity were analyzed. Changes in electrophoretic mobility, amount of free amino groups, and contents of bound sugar and fructosamine indicated that glycation of Cor a 11 occurred at all conditions. Glycation at 37 °C did not influence the specific IgG or IgE binding and was decreased after heating at 60 and 145 °C. Heating, with or without glucose, at 145 °C increased basophil degranulation capacity. The results suggest that glycation of Cor a 11 at 60 and 145 °C may decrease the IgE/IgG binding properties but not the degranulation capacity of basophils. This is possibly related to aggregation of the proteins as a result of the Maillard reaction.

The frontiers of mass spectrometry-based techniques in food allergenomics

In the last years proteomic science has started to provide an important contribution to the disclosure of basic aspects of food-related diseases. Among these, the identification of proteins involved in food allergy and their mechanism of activation of toxicity. Elucidation of these key issues requires the integration of clinical, immunological, genomic and proteomic approaches. These combined research efforts are aimed to obtain structural and functional information to assist the development of novel, more reliable and powerful diagnostic protocols alternative to the currently available procedures, mainly based on food challenge tests. Another crucial aspect related to food allergy is the need for methods to detect trace amounts of allergenic proteins in foods. Mass spectrometry is the only non-immunological method for high-specificity and high-sensitivity detection of allergens in foods. Nowadays, once provided the appropriate sample handling and the correct operative conditions, qualitative and quantitative determination of allergens in foods and ingredients can be efficiently obtained by MALDI-TOF-MS and LC-MS/MS methods, with limits of detection and quantification in the low-ppb range. The availability of accurate and fast alternatives to immunological ELISA tests may also enable the development of novel therapeutic strategies and food processing technologies to aid patients with food allergy or intolerance, and to support allergen labelling and certification processes, all issues where the role of proteomic science is emerging.

Assessment of allergenicity of diploid and hexaploid wheat genotypes: identification of allergens in the albumin/globulin fraction

Wheat is an important part of the daily diet of millions of people. However, this staple food is also responsible for food allergies. Ancient cultivars of wheat are gaining interest today but nothing is known about their allergenicity. Many wheat proteins have been reported as causative food allergens, including some prolamin-type gluten proteins, and salt soluble proteins of the albumin/globulin (A/G) type. The objective of this work is to obtain information about the allergenicity of the salt soluble A/G fraction of an ancient diploid cultivar compared with a standard hexaploid bread wheat cultivar using 20 sera from patients with wheat allergy. Differences in the IgE reactivity of sera towards the two genotypes were quantified by ELISA. Qualitative differences in IgE-binding proteins were searched after 1D or 2D electrophoresis. For most of the sera, the concentration in A/G specific IgE was higher for the hexaploid T. aestivum (cv Récital) than for the diploid T. monococcum (cv Engrain). The analysis of 2D spots revealed by immunoblotting leads to the identification by mass spectrometry of 39 IgE-binding proteins, some of them unknown until now as wheat allergens. Numerous allergens were identified, differences observed between Engrain and Récital will be discussed.

Clinical allergy to hazelnut and peanut: identification of T cell cross-reactive allergens

BACKGROUND

Peanut and tree nut allergies are life-threatening conditions for many affected individuals worldwide. Currently there is no cure. While co-allergy to peanut and tree nuts is a common clinical observation, and IgE cross-reactivity between peanut and tree nuts is reported, T cell cross-reactivity is poorly defined.

METHODS

Hazelnut-specific T cell lines were established using peripheral blood mononuclear cells from 5 subjects with co-allergy to hazelnut and peanut. These lines were stimulated with hazelnut and peanut extracts and purified major peanut allergens, Ara h 1 and Ara h 2. Proliferation was determined by (3)H-thymidine incorporation and secretion of key Th1 (IFN-γ) and Th2 (IL-5) cytokines analysed by ELISA.

RESULTS

Hazelnut-specific T cell lines from all 5 subjects proliferated upon stimulation with both hazelnut and peanut extracts and for 4 subjects, to Ara h 1 and/or Ara h 2. Proliferating cells were mainly CD4+ T cells and produced both IL-5 and IFN-γ in response to hazelnut and peanut stimulation. Mitogenicity of extracts and allergens was excluded by their lack of stimulation of house dust mite-specific T cells.

CONCLUSION

Our finding that hazelnut and peanut co-allergy is associated with cross-reactive T cell responses, driven partly by cross-reactivity to the major peanut allergens Ara h 1 and Ara h 2, points to future development of allergen immunotherapy by targeting cross-reactive T cells.

Liquid chromatography and mass spectrometry in food allergen detection

Food allergy is an important issue in the field of food safety because of the hazards for affected persons and the hygiene requirements and legal regulations imposed on the food industry. Consumer protection and law enforcement require suitable analytical techniques for the detection of allergens in foods. Immunological methods are currently preferred; however, confirmatory alternatives are needed. The determination of allergenic proteins by liquid chromatography and mass spectrometry has greatly advanced in recent years, and gel-free allergenomics is becoming a routinely used approach for the identification and quantitation of food allergens. The present review provides a brief overview of the principles of proteomic procedures, various chromatographic set ups, and mass spectrometry instrumentation used in allergenomics. A compendium of published liquid chromatography methods, proteomic analyses, typical marker peptides, and quantitative assays for 14 main allergy-causing foods is also included.

Childhood Food Allergy: A Singaporean Perspective

Food allergy is defined as reaction to a food which has an immunologic mechanism. Its prevalence is increasing in children globally and is therefore of increasing clinical importance. A useful clinical approach is to distinguish food allergic reactions by the timing of clinical reaction in relation to food exposure and classified as immediate (generally IgE-mediated) and delayed (generally non-IgE-mediated), with the exception of eczema and eosinophilic gastrointestinal disease, which, when associated with food allergy may be associated with either mechanism. This review is aimed at providing the clinician with a Singaporean perspective on the clinical approach and management of these disorders. Key words: Asia, Children, Food allergy

Diagnosis of food allergy based on oral food challenge test

Diagnosis of food allergy should be based on the observation of allergic symptoms after intake of the suspected food. The oral food challenge test (OFC) is the most reliable clinical procedure for diagnosing food allergy. The OFC is also applied for the diagnosis of tolerance of food allergy. The Japanese Society of Pediatric Allergy and Clinical Immunology issued the 'Japanese Pediatric Guideline for Oral Food Challenge Test in Food Allergy 2009' in April 2009, to provide information on a safe and standardized method for administering the OFC. This review focuses on the clinical applications and procedure for the OFC, based on the Japanese OFC guideline.

Immunochemical characterization of Glycine max L. Merr. var Raiden, as a possible hypoallergenic substitute for cow's milk-allergic patients

BACKGROUND

Cows' milk allergy (CMA) is the most common cause of food allergy in infancy. The only proven treatment is the complete elimination of cows' milk proteins (CMPs) from the diet by means of hypoallergenic formulas. Soybean-based formulae are widely used although intolerance to soy has been reported to occur in 15-40% of infants with CMA.

OBJECTIVE

The aim of this work was to analyse the in vitro reactivity of the soybean cultivar Raiden, which naturally lacks glycinin A(4)A(5)B(3), to evaluate whether this genotype could be a safe CMP substitute for CMA patients.

METHODS

The reactivity of conventional soybean (CS) and Raiden soybean (RS) genotypes and also recombinant glycinin A(4)A(5)B(3) and alphabeta-conglycinin with casein-specific monoclonal antibodies and CMP-specific polyclonal serum was evaluated by immunoblotting and ELISA. A sequential competitive ELISA with the polyclonal antiserum and different soluble inhibitors was performed. In addition, an indirect ELISA with sera of atopic children with CMA was carried out to analyse the IgE-binding capacity of the different soybean components.

RESULTS

We have shown that CS contains four components that cross-react with CMP, while RS has only one. The remaining cross-reactive component in RS was identified as alpha-subunit beta-conglycinin. By means of inhibitory ELISA, we demonstrated that CS, RS and the alpha-subunit beta-conglycinin extracts inhibited the binding of CMP-specific antibodies to the CMP-coated solid phase. Finally, we showed that CS, RS and the recombinant proteins were recognized by human CMP-specific IgE antibodies.

CONCLUSION

This work shows that although Raiden has fewer cross-reactive components than conventional soybean, it still has a residual cross-reactive component: the alpha-subunit beta-conglycinin. This reactivity might make this genotype unsuitable to treat CMA and also explains adverse reactions to soybean in CMA infants.

Comprehensive royal jelly (RJ) proteomics using one- and two-dimensional proteomics platforms reveals novel RJ proteins and potential phospho/glycoproteins

Royal jelly (RJ) is an exclusive food for queen honey bee (Apis mellifera L.) that is synthesized and secreted by young worker bees. RJ is also widely used in medical products, cosmetics, and as health foods. However, little is known about RJ functionality and the total protein components, although recent research is attempting to unravel the RJ proteome. We have embarked on a detailed investigation of the RJ proteome, using a modified protein extraction protocol and two complementary proteomics approaches, one- and two-dimensional gel electrophoresis (1-DGE and 2-DGE) in conjunction with tandem mass spectrometry. Simultaneously, we examined total soluble protein from RJ collected at 24, 48, and 72 h after honey bee larvae deposition twice (in two flower blooming seasons), to check differences, if any, in RJ proteome therein. Both 1- and 2-D gels stained with silver nitrate revealed similar protein profiles among these three time points. However, we observed a clear difference in two bands (ca. MW of 55 and 75 kDa) on 1-D gel between the first and the second collection of RJ. A similar difference was also observed in the 2-D gel. Except for this difference, the protein profiles were similar at the 3 time points. As the RJ from 48 (or sometimes 72) is commercially used, we selected the RJ sample at 48 h for detailed analysis with the first collection. 1-DGE identified 90 and 15 proteins from the first and second selection, respectively; in total, 47 nonredundant proteins were identified. 2-DGE identified 105 proteins comprising 14 nonredundant proteins. In total, 52 nonredundant proteins were identified in this study, and other than the major royal jelly protein family and some other previously identified proteins, 42 novel proteins were identified. Furthermore, we also report potentially post-translationally modified (phosphorylation and glycosylation) RJ proteins based on the Pro-Q diamond/emerald phosphoprotein/glycoprotein gel stains; MRJP 2p and 7p were suggested as potential phosphoproteins. The 2-DGE data were integrated to develop a 2-D gel reference map, and all data are accessible through RJ proteomics portal (http://foodfunc.agr.ibaraki.ac.jp/RJP.html).