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Bernard H, Turner PJ, Ah-Leung S, Ruiz-Garcia M, Clare Mills EN, Adel-Patient K. Circulating Ara h 6 as a marker of peanut protein absorption in tolerant and allergic humans following ingestion of peanut-containing foods. Clin Exp Allergy 2020; 50:1093-1102. [PMID: 32648641 DOI: 10.1111/cea.13706] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 03/30/2020] [Accepted: 05/29/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND Bioaccessibility of food allergens may be a key determinant of allergic reactions. OBJECTIVE To develop a protocol allowing the detection of the major peanut allergen, Ara h 6, in the bloodstream following ingestion of low amounts of peanut and to compare Ara h 6 bioaccessibility by food matrix. We further assessed for differences in absorption in healthy versus peanut-allergic volunteers. METHODS A blood pretreatment combining acidic shock and thermal treatment was developed. This protocol was then applied to blood samples collected from human volunteers (n = 6, healthy controls; n = 14, peanut-allergic patients) at various time-points following ingestion of increasing levels of peanut incurred in different food matrices (cookies, peanut butter and chocolate dessert). Immunodetection was performed using an in-house immunoassay. RESULTS An original pretreatment protocol was optimized, resulting in irreversible dissociation of human antibodies-Ara h 6 immune complex, thus rendering Ara h 6 accessible for its immunodetection. Ara h 6 was detected in samples from all volunteers following ingestion of 300-1000 mg peanut protein, although variations in the kinetics of passage were observed between individuals and matrices. Interestingly, in peanut-allergic subjects, Ara h 6 could be detected following ingestion of lower doses and at higher concentrations than in non-allergic volunteers. CONCLUSIONS AND CLINICAL RELEVANCE The kinetics and intensity of Ara h 6 passage in bloodstream depend on both individual and food matrix. Peanut-allergic patients appear to demonstrate higher absorption rate, the clinical significance of which warrants further evaluation.
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Affiliation(s)
- Hervé Bernard
- CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS)/ Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Paul J Turner
- Section of Inflammation, Repair & Development, National Heart & Lung Institute, Imperial College London, London, UK
| | - Sandrine Ah-Leung
- CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS)/ Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Monica Ruiz-Garcia
- Section of Inflammation, Repair & Development, National Heart & Lung Institute, Imperial College London, London, UK
| | - Elizabeth Naomi Clare Mills
- Division of Infection, Immunity and Respiratory Medicine, School of Biological Sciences and Manchester Institute of Biotechnology, Manchester Academic Health Sciences Centre, University of Manchester, Manchester, UK
| | - Karine Adel-Patient
- CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS)/ Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
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Hilu KW, Friend SA, Vallanadu V, Brown AM, Hollingsworth LR 4th, Bevan DR. Molecular evolution of genes encoding allergen proteins in the peanuts genus Arachis: Structural and functional implications. PLoS One 2019; 14:e0222440. [PMID: 31675366 DOI: 10.1371/journal.pone.0222440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/29/2019] [Indexed: 12/14/2022] Open
Abstract
Food allergies are severe immune responses to plant and animal products mediated by immunoglobulin E (IgE). Peanuts (Arachis hypogaea L.) are among the top 15 crops that feed the world. However, peanuts is among the “big eight food allergens”, and allergies induced by peanuts are a significant public health problem and a life-threatening concern. Targeted mutation studies in peanuts demonstrate that single residue alterations in these allergen proteins could result in substantial reduction in allergenicity. Knowledge of peanut allergen proteins is confined to the allotetraploid crop and its two progenitors. We explored frequencies and positions of natural mutations in the hyperallergenic homologues Ara h 2 and Ara h 6 in newly generated sequences for 24 Arachis wild species and the crop species, assessed potential mutational impact on allergenicity using immunoblots and structural modeling, and evaluated whether these mutations follow evolutionary trends. We uncovered a wealth of natural mutations, both substitutions and gaps, including the elimination of immunodominant epitopes in some species. These molecular alterations appear to be associated with substantial reductions in allergenicity. The study demonstrated that Ara h 2 and Ara h 6 follow contrasting modes of natural selection and opposing mutational patterns, particularly in epitope regions. Phylogenetic analysis revealed a progressive trend towards immunodominant epitope evolution in Ara h 2. The findings provide valuable insight into the interactions among mutations, protein structure and immune system response, thus presenting a valuable platform for future manipulation of allergens to minimize, treat or eliminate allergenicity. The study strongly encourages exploration of genepools of economically important plants in allergenicity research.
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Pi X, Wan Y, Yang Y, Li R, Wu X, Xie M, Li X, Fu G. Research progress in peanut allergens and their allergenicity reduction. Trends Food Sci Technol 2019; 93:212-20. [DOI: 10.1016/j.tifs.2019.09.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hazebrouck S, Guillon B, Paty E, Dreskin SC, Adel-Patient K, Bernard H. Variable IgE cross-reactivity between peanut 2S-albumins: The case for measuring IgE to both Ara h 2 and Ara h 6. Clin Exp Allergy 2019; 49:1107-1115. [PMID: 31108010 DOI: 10.1111/cea.13432] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 04/15/2019] [Accepted: 04/25/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND 2S-albumins Ara h 2 and Ara h 6 are the most potent peanut allergens and levels of specific immunoglobulin E (IgE) towards these proteins are good predictors of clinical reactivity. Because of structural homologies, Ara h 6 is generally considered to cross-react extensively with Ara h 2. OBJECTIVE We aimed to quantify the IgE cross-reactivity between Ara h 2 and Ara h 6. METHODS Peanut 2S-albumins were purified from raw peanuts. The IgE cross-reactivity between Ara h 2 and Ara h 6 was evaluated with 32 sera from French and US peanut-allergic patients by measuring the residual IgE-binding to one 2S-albumin after depletion of IgE antibodies recognizing the other 2S-albumin. The IgE cross-reactivity between Ara h 2 and Ara h 6 was further investigated by competitive inhibition of IgE-binding and by a model of mast cell degranulation. RESULTS A highly variable level of IgE cross-reactivity was revealed among the patients. The mean fraction of cross-reactive IgE antibodies represented only 17.1% of 2S-albumins-specific IgE antibodies and was lower than the mean fraction of IgE specific to Ara h 2 (57.4%) or to Ara h 6 (25.5%). The higher level of Ara h 2-specific IgE was principally due to the IgE-binding capacity of an insertion containing the repeated immunodominant linear epitope DPYSPOH S. The impact of IgE cross-reactivity on diagnostic testing was illustrated with a serum displaying an Ara h 6-specific IgE response of 26 UI/mL that was not associated with the capacity of Ara h 6 to trigger mast cell degranulation. CONCLUSIONS & CLINICAL RELEVANCE Immunoglobulin E antibodies specific to peanut 2S-albumins are mainly non-cross-reactive, but low-affinity cross-reactivity can affect diagnostic accuracy. Testing IgE-binding to a mixture of 2S-albumins rather than to each separately may enhance diagnostic performance.
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Affiliation(s)
- Stéphane Hazebrouck
- Service de Pharmacologie et Immunoanalyse (SPI), Laboratoire d'Immuno-Allergie Alimentaire, CEA, INRA, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Blanche Guillon
- Service de Pharmacologie et Immunoanalyse (SPI), Laboratoire d'Immuno-Allergie Alimentaire, CEA, INRA, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Evelyne Paty
- Université Paris Descartes-Assistance Publique des Hôpitaux de Paris, Hôpital Necker Enfants Malades, Paris, France
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, Denver School of Medicine, University of Colorado, Aurora, Colorado
| | - Karine Adel-Patient
- Service de Pharmacologie et Immunoanalyse (SPI), Laboratoire d'Immuno-Allergie Alimentaire, CEA, INRA, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Hervé Bernard
- Service de Pharmacologie et Immunoanalyse (SPI), Laboratoire d'Immuno-Allergie Alimentaire, CEA, INRA, Université Paris-Saclay, Gif-sur-Yvette, France
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Mamone G, Di Stasio L, De Caro S, Picariello G, Nicolai MA, Ferranti P. Comprehensive analysis of the peanut allergome combining 2-DE gel-based and gel-free proteomics. Food Res Int 2019; 116:1059-1065. [DOI: 10.1016/j.foodres.2018.09.045] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 09/03/2018] [Accepted: 09/17/2018] [Indexed: 02/04/2023]
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de Jong GAH, Jayasena S, Johnson P, Marsh J, Apostolovic D, van Hage M, Nordlee J, Baumert J, Taylor SL, Roucairol C, de Jongh H, Koppelman SJ. Purification and Characterization of Naturally Occurring Post-Translationally Cleaved Ara h 6, an Allergen That Contributes Substantially to the Allergenic Potency of Peanut. J Agric Food Chem 2018; 66:10855-10863. [PMID: 30284821 DOI: 10.1021/acs.jafc.8b03140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The 2S albumin Ara h 6 is one of the most important peanut allergens. A post-translationally cleaved Ara h 6 (pAra h 6) was purified from Virginia type peanuts, and the cleavage site was mapped using high-resolution mass spectrometry. Compared to intact Ara h 6, pAra h 6 lacks a 5-amino acid stretch, resembling amino acids 43-47 (UniProt accession number Q647G9) in the nonstructured loop. Consequently, pAra h 6 consists of two chains: an N-terminal chain of approximately 5 kDa and a C-terminal chain of approximately 9 kDa, held together by disulfide bonds. Intermediate post-translationally cleaved products, in which this stretch is cleaved yet still attached to one of the subunits, are also present. The secondary structure and immunoglobulin E (IgE) binding of pAra h 6 resembles that of intact Ara h 6, indicating that the loss of the nonstructured loop is not critical for maintaining the protein structure. Commercially available monoclonal and polyclonal immunoglobulin G (IgG) antibodies directed to Ara h 6 react with both intact Ara h 6 and pAra h 6, suggesting that the involved epitopes are not located in the area that is post-translationally cleaved. No differences between intact Ara h 6 and pAra h 6 in terms of IgE binding were found, suggesting that the area that is post-translationally cleaved is not involved in IgE epitopes either. For all main cultivars Runner, Virginia, Valencia, and Spanish, intact Ara h 6 and pAra h 6 occur in peanut at similar levels, indicating that pAra h 6 is a consistent and important contributor to the allergenic potency of peanut.
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Affiliation(s)
| | - Shyamali Jayasena
- Food Allergy Research and Resource Program, Department of Food Science & Technology , University of Nebraska , 279 Food Innovation Center , Lincoln , Nebraska 68588-6207 , United States
| | - Phil Johnson
- Food Allergy Research and Resource Program, Department of Food Science & Technology , University of Nebraska , 279 Food Innovation Center , Lincoln , Nebraska 68588-6207 , United States
| | - Justin Marsh
- Food Allergy Research and Resource Program, Department of Food Science & Technology , University of Nebraska , 279 Food Innovation Center , Lincoln , Nebraska 68588-6207 , United States
| | - Danijela Apostolovic
- Immunology and Allergy Unit, Department of Medicine Solna , Karolinska Institutet , 171 77 Stockholm , Sweden
| | - Marianne van Hage
- Immunology and Allergy Unit, Department of Medicine Solna , Karolinska Institutet , 171 77 Stockholm , Sweden
| | - Julie Nordlee
- TNO , Utrechtseweg 48 , 3704 HE , Zeist , The Netherlands
| | - Joe Baumert
- TNO , Utrechtseweg 48 , 3704 HE , Zeist , The Netherlands
| | - Steve L Taylor
- TNO , Utrechtseweg 48 , 3704 HE , Zeist , The Netherlands
| | - Camille Roucairol
- DBV Technologies , Development Department , 92120 Montrouge , France
| | | | - Stef J Koppelman
- Food Allergy Research and Resource Program, Department of Food Science & Technology , University of Nebraska , 279 Food Innovation Center , Lincoln , Nebraska 68588-6207 , United States
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Abstract
Peanut allergens have the potential to negatively impact on the health and quality of life of millions of consumers worldwide. The seeds of the peanut plant Arachis hypogaea contain an array of allergens that are able to induce the production of specific IgE antibodies in predisposed individuals. A lot of effort has been focused on obtaining the sequences and structures of these allergens due to the high health risk they represent. At present, 16 proteins present in peanuts are officially recognized as allergens. Research has also focused on their in-depth immunological characterization as well as on the design of modified hypoallergenic derivatives for potential use in clinical studies and the formulation of strategies for immunotherapy. Detailed research protocols are available for the purification of natural allergens as well as their recombinant production in bacterial, yeast, insect, and algal cells. Purified allergen molecules are now routinely used in diagnostic multiplex protein arrays for the detection of the presence of allergen-specific IgE. This review gives an overview on the wealth of knowledge that is available on individual peanut allergens.
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Affiliation(s)
- Chiara Palladino
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Heimo Breiteneder
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
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Bavaro SL, Di Stasio L, Mamone G, De Angelis E, Nocerino R, Canani RB, Logrieco AF, Montemurro N, Monaci L. Effect of thermal/pressure processing and simulated human digestion on the immunoreactivity of extractable peanut allergens. Food Res Int 2018; 109:126-37. [PMID: 29803434 DOI: 10.1016/j.foodres.2018.04.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 04/06/2018] [Accepted: 04/12/2018] [Indexed: 11/24/2022]
Abstract
Peanut allergy is one of the most widespread types of food allergies especially affecting developed countries. To reduce the risk of triggering allergic reactions, several technological strategies have been devised to modify or remove allergens from foods. Herein we investigated the combination of high temperature and pressure on the modulation of peanuts immunoreactivity after simulated gastro-duodenal digestion. Extractable proteins of raw and autoclaved peanuts were separated on SDS-PAGE and immunogenicity was assessed by ELISA and Western Blot analyses. Proteins surviving the heat treatment and reacting towards allergic patients' sera were analysed and attributed to Ara h 3 and Ara h 1 proteins by untargeted LC-high resolution-MS/MS. A progressive reduction in the intensity of the major allergen proteins was also highlighted in the protein fraction extracted from autoclaved peanuts, with a total disappearance of the high molecular allergens when samples were preliminary exposed to 2 h hydration although the lower molecular weight fraction was not investigated in the present work. Furthermore, raw and processed peanuts underwent simulated digestion experiments and the IgE binding was assessed by using allergic patients' sera. The persistence of an immunoreactive band was displayed around 20 kDa. In conclusion, the synergistic effects of heat and pressure played a pivotal role in the disappearance of the major peanut allergens also contributing to the significant alteration of the final immunoreactivity. In addition, the surviving of allergenic determinants in peanuts after gastrointestinal breakdown provides more insights on the fate of allergenic proteins after autoclaving treatments.
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Korte R, Happe J, Brümmer I, Brockmeyer J. Structural Characterization of the Allergenic 2S Albumin Cor a 14: Comparing Proteoform Patterns across Hazelnut Cultivars. J Proteome Res 2017; 16:988-998. [PMID: 28112517 DOI: 10.1021/acs.jproteome.6b00924] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The hazelnut allergen Cor a 14 belongs to the 2S albumins, a family of heterodimeric seed storage proteins exhibiting a high degree of structural diversity. Given its relevance as an allergen and the potential to elicit severe reactions, elucidation of the sequence heterogeneity of naturally occurring Cor a 14 is essential for the development of reliable diagnostics and risk evaluation. We therefore performed a comprehensive survey on the proteoforms of Cor a 14 and determined their quantitative distribution in three different hazelnut cultivars by a combinatory HPLC-HRMS approach including bottom-up and intact mass analysis. Compared with the Cor a 14 prototype sequence, we identified three sequence polymorphisms, two of the small and one of the large subunit, and elucidated their specific pairing on the protein level. Furthermore, we located a pronounced microheterogeneity on the protein termini and, for the first time, provide data on varying proteoform patterns between different cultivars of an allergenic seed. Together, these data present the basis for a more detailed investigation on the allergenicity of Cor a 14 in different cultivars and constitute, to be best of our knowledge, the largest set of proteoforms so far reported for a 2S albumin.
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Affiliation(s)
- Robin Korte
- Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster , Corrensstraße 45, 48149 Münster, Germany
| | - Jana Happe
- Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster , Corrensstraße 45, 48149 Münster, Germany
| | - Ina Brümmer
- Analytical Food Chemistry, University of Stuttgart , Allmandring 5b, 70569 Stuttgart, Germany
| | - Jens Brockmeyer
- Institute of Food Chemistry, Westfälische Wilhelms-Universität Münster , Corrensstraße 45, 48149 Münster, Germany.,Analytical Food Chemistry, University of Stuttgart , Allmandring 5b, 70569 Stuttgart, Germany
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JanssenDuijghuijsen LM, Wichers HJ, van Norren K, Keijer J, Baumert JL, de Jong GA, Witkamp RF, Koppelman SJ. Detection of peanut allergen in human blood after consumption of peanuts is skewed by endogenous immunoglobulins. J Immunol Methods 2017; 440:52-7. [PMID: 27845035 DOI: 10.1016/j.jim.2016.11.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/07/2016] [Accepted: 11/08/2016] [Indexed: 12/16/2022]
Abstract
Some studies have suggested that allergens may appear in the circulation after ingestion of allergenic food sources. The reported levels of allergen in serum, however, are low, and conclusions between studies differ. Here, we investigated factors that determine the detection of allergens in serum after consumption of peanuts. Ten healthy volunteers ingested 100g of light-roasted peanuts. Serum samples were taken at regular intervals for six hours. A double monoclonal sandwich ELISA was used to analyse the presence and quantity of the major peanut allergen Ara h 6 in serum. In 4 out of 10 subjects, no Ara h 6 could be detected. Purified Ara h 6 that was digested in vitro was still reactive in the ELISA, rejecting the possibility that digestion leads to small peptides that could not be detected. Spiking of purified Ara h 6 in baseline serum showed that the pre-ingestion serum of these four subjects partially prevented Ara h 6 to react in the ELISA, with a reduction of reactivity of up to 3 orders of magnitude or more. Pre-ingestion serum of the other six subjects did not show such an effect. The reduction of reactivity of Ara h 6 coincided with high titres of IgG and IgG4, and removal of IgG from pre-ingestion serum abolished this effect completely, indicating that IgG and IgG4 inhibited the reactivity of Ara h6 in the ELISA. We conclude that some individuals have IgG and IgG4 against food allergens in their blood, which interferes with detection of such food allergens in serum. Because this effect does not occur for each individual, the possibility of such interference should be taken into consideration when interpreting immunochemical studies on the absorption of food allergens in serum.
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Guillon B, Bernard H, Drumare MF, Hazebrouck S, Adel-Patient K. Heat processing of peanut seed enhances the sensitization potential of the major peanut allergen Ara h 6. Mol Nutr Food Res 2016; 60:2722-2735. [PMID: 27374416 PMCID: PMC5213772 DOI: 10.1002/mnfr.201500923] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 11/11/2022]
Abstract
SCOPE Processing of food has been shown to impact IgE binding and functionality of food allergens. In the present study, we investigated the impact of heat processing on the sensitization capacity of Ara h 6, a major peanut allergen and one of the most potent elicitors of the allergic reaction. METHODS AND RESULTS Peanut extracts obtained from raw or heat-processed peanut and some fractions thereof were biochemically and immunochemically characterized. These extracts/fractions, purified Ara h 6, or recombinant Ara h 6 including Ara h 6 mutants lacking disulfide bridges were used in in vitro digestion tests and mouse models of experimental sensitization. Peanut roasting led to the formation of complexes of high molecular weight, notably between Ara h 6 and Ara h 1, which supported the induction of IgE specific to native Ara h 6. On the contrary, a fraction containing free monomeric 2S albumins or purified native Ara h 6 displayed no intrinsic allergenicity. In addition to complex formation, heat denaturation and/or partial destabilization enhanced Ara h 6 immunogenicity and increased its sensitivity to digestion. CONCLUSION These results suggest that sensitization potency and IgE binding capacity can be supported by different structures, modified and/or produced during food processing in interaction with other food constituents.
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Affiliation(s)
- Blanche Guillon
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Hervé Bernard
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Marie-Françoise Drumare
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Stéphane Hazebrouck
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Karine Adel-Patient
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
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Javaux C, Stordeur P, Azarkan M, Mascart F, Baeyens-Volant D. Isolation of a thiol-dependent serine protease in peanut and investigation of its role in the complement and the allergic reaction. Mol Immunol 2016; 75:133-43. [DOI: 10.1016/j.molimm.2016.05.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 04/19/2016] [Accepted: 05/04/2016] [Indexed: 11/29/2022]
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Vanga SK, Singh A, Raghavan V. Effect of thermal and electric field treatment on the conformation of Ara h 6 peanut protein allergen. INNOV FOOD SCI EMERG 2015; 30:79-88. [DOI: 10.1016/j.ifset.2015.03.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Khuda SE, Jackson LS, Fu TJ, Williams KM. Effects of processing on the recovery of food allergens from a model dark chocolate matrix. Food Chem 2015; 168:580-7. [DOI: 10.1016/j.foodchem.2014.07.084] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 06/11/2014] [Accepted: 07/15/2014] [Indexed: 10/25/2022]
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Bernard H, Guillon B, Drumare MF, Paty E, Dreskin SC, Wal JM, Adel-Patient K, Hazebrouck S. Allergenicity of peanut component Ara h 2: Contribution of conformational versus linear hydroxyproline-containing epitopes. J Allergy Clin Immunol 2014; 135:1267-74.e1-8. [PMID: 25483599 DOI: 10.1016/j.jaci.2014.10.025] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 10/03/2014] [Accepted: 10/06/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND The 2S-albumin Ara h 2 is the most potent peanut allergen and a good predictor of clinical reactivity in allergic children. Posttranslational hydroxylation of proline residues occurs in DPYSP(OH)S motifs, which are repeated 2 or 3 times in different isoforms. OBJECTIVES We investigated the effect of proline hydroxylation on IgE binding and the relative contributions of linear and conformational epitopes to Ara h 2 allergenicity. METHODS Peptides containing DPYSP(OH)S motifs were synthesized. A recombinant variant of Ara h 2 without DPYSP(OH)S motifs was generated by means of deletion mutagenesis. IgE reactivity of 18 French and 5 American patients with peanut allergy toward synthetic peptides and recombinant allergens was assessed by using IgE-binding inhibition assays and degranulation tests of humanized rat basophilic leukemia cells. RESULTS Hydroxyproline-containing peptides exhibited an IgE-binding activity equivalent to that of the unfolded Ara h 2. In contrast, corresponding peptides without hydroxyprolines displayed a very weak IgE-binding capacity. Despite removal of the DPYSP(OH)S motifs, the deletion variant still displayed Ara h 2 conformational epitopes. The IgE-binding capacity of Ara h 2 was then recapitulated with an equimolar mixture of a hydroxylated peptide and the deletion variant. Hydroxylated peptides of 15 and 27 amino acid residues were also able to trigger cell degranulation. CONCLUSIONS Sensitization toward linear and conformational epitopes of Ara h 2 is variable among patients with peanut allergy. Optimal IgE binding to linear epitopes of Ara h 2 requires posttranslational hydroxylation of proline residues. The absence of hydroxyprolines could then affect the accuracy of component-resolved diagnostics by using rAra h 2.
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Affiliation(s)
- Hervé Bernard
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Blanche Guillon
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Marie-Françoise Drumare
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Evelyne Paty
- Université Paris Descartes-Assistance Publique des Hôpitaux de Paris, Hôpital Necker Enfants Malades, Paris, France
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, Colo
| | - Jean-Michel Wal
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Karine Adel-Patient
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Stéphane Hazebrouck
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France.
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Bernard H, Ah-Leung S, Drumare MF, Feraudet-Tarisse C, Verhasselt V, Wal JM, Créminon C, Adel-Patient K. Peanut allergens are rapidly transferred in human breast milk and can prevent sensitization in mice. Allergy 2014; 69:888-97. [PMID: 24773443 DOI: 10.1111/all.12411] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Abstract
BACKGROUND Food allergens have been evidenced in breast milk under physiological conditions, but the kinetic and the role of this passage in food allergies are still unclear. We then aimed to analyze the passage of peanut allergens in human breast milk and their allergenicity/immunomodulatory properties. METHODS Human breast milk was collected from two non-atopic peanut-tolerant mothers before and at different time points after ingestion of 30 g of commercial roasted peanut. Ara h 6, Ara h 6 immune complexes, and the IgE binding capacity of breast milk samples were measured using specific immunoassays. Their allergenic functionality was then assessed using cell-based assay. Finally, human breast milk obtained before or after peanut ingestion was administered intragastrically to BALB/c mice at different ages, and mice were further experimentally sensitized to peanut using cholera toxin. RESULTS Ara h 6 is detected as soon as 10 min after peanut ingestion, with peak values observed within the first hour after ingestion. The transfer is long-lasting, small quantities of peanut allergens being detected over a 24-h period. IgG-Ara h 6 and IgA-Ara h 6 immune complexes are evidenced, following a different kinetic of excretion than free allergens. Peanut allergens transferred in milk are IgE reactive and can induce an allergic reaction in vitro. However, administration of human breast milk to young mice, notably before weaning, does not lead to sensitization, but instead to partial oral tolerance. CONCLUSION The low quantities of immunologically active allergens transferred through breast milk may prevent instead of priming allergic sensitization to peanut.
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Affiliation(s)
- H. Bernard
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - S. Ah-Leung
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - M.-F. Drumare
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - C. Feraudet-Tarisse
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - V. Verhasselt
- EA 6302 Tolérance Immunitaire; Hôpital de l'Archet; Université de Nice Sophia-Antipolis; Nice France
| | - J.-M. Wal
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - C. Créminon
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - K. Adel-Patient
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
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18
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Koid AE, Chapman MD, Hamilton RG, van Ree R, Versteeg SA, Dreskin SC, Koppelman SJ, Wünschmann S. Ara h 6 complements Ara h 2 as an important marker for IgE reactivity to peanut. J Agric Food Chem 2014; 62:206-13. [PMID: 24328145 PMCID: PMC4055559 DOI: 10.1021/jf4022509] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The similarities of two major peanut allergens, Ara h 2 and Ara h 6, in molecular size, amino acid sequence, and structure have made it difficult to obtain natural Ara h 6 free of Ara h 2. The objectives of this study were to purify natural Ara h 6 that is essentially free of Ara h 2 and to compare its IgE reactivity and potency in histamine release assays to Ara h 2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the highly purified allergen (<0.01% Ara h 2) revealed a single 14.5 kD band, and the identity of Ara h 6 was confirmed by liquid chromatography-tandem mass spectrometry. Ara h 6 showed a higher seroprevalence in chimeric IgE enzyme-linked immunosorbent assay (n = 54) but a weaker biological activity in basophil histamine release assays than Ara h 2. Purified Ara h 6 will be useful for diagnostic IgE antibody assays as well as molecular and cellular studies to investigate the immunological mechanisms of peanut allergy.
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Affiliation(s)
- Audrey E Koid
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
| | - Martin D Chapman
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
| | - Robert G Hamilton
- Johns Hopkins University School of Medicine, 600 N Wolfe St #6-113, Baltimore, MD 21287
| | - Ronald van Ree
- Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam-Zuidoost, The Netherlands
| | - Serge A Versteeg
- Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam-Zuidoost, The Netherlands
| | - Stephen C Dreskin
- University of Colorado Denver, School of Medicine, 1250 14th St, Denver, CO 80202
| | | | - Sabina Wünschmann
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
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19
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Abstract
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.
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Affiliation(s)
- Jorge Sáiz
- Department of Chemistry I, Faculty of Biology, Environmental Sciences, and Chemistry, University of Alcalá, 28871 Alcalá de Henares, Madrid, Spain
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20
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Apostolovic D, Luykx D, Warmenhoven H, Verbart D, Stanic-Vucinic D, de Jong GAH, Velickovic TC, Koppelman SJ. Reduction and alkylation of peanut allergen isoforms Ara h 2 and Ara h 6; characterization of intermediate- and end products. Biochim Biophys Acta 2013; 1834:2832-42. [PMID: 24145103 DOI: 10.1016/j.bbapap.2013.10.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 09/12/2013] [Accepted: 10/04/2013] [Indexed: 10/26/2022]
Abstract
Conglutins, the major peanut allergens, Ara h 2 and Ara h 6, are highly structured proteins stabilized by multiple disulfide bridges and are stable towards heat-denaturation and digestion. We sought a way to reduce their potent allergenicity in view of the development of immunotherapy for peanut allergy. Isoforms of conglutin were purified, reduced with dithiothreitol and subsequently alkylated with iodoacetamide. The effect of this modification was assessed on protein folding and IgE-binding. We found that all disulfide bridges were reduced and alkylated. As a result, the secondary structure lost α-helix and gained some β-structure content, and the tertiary structure stability was reduced. On a functional level, the modification led to a strongly decreased IgE-binding. Using conditions for limited reduction and alkylation, partially reduced and alkylated proteins were found with rearranged disulfide bridges and, in some cases, intermolecular cross-links were found. Peptide mass finger printing was applied to control progress of the modification reaction and to map novel disulfide bonds. There was no preference for the order in which disulfides were reduced, and disulfide rearrangement occurred in a non-specific way. Only minor differences in kinetics of reduction and alkylation were found between the different conglutin isoforms. We conclude that the peanut conglutins Ara h 2 and Ara h 6 can be chemically modified by reduction and alkylation, such that they substantially unfold and that their allergenic potency decreases.
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Affiliation(s)
- Danijela Apostolovic
- HAL Allergy B.V., J.H. Oortweg 15-17, 2333 CH Leiden, The Netherlands; Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11 000 Belgrade, Serbia
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21
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Zhuang Y, Durrani S, Hodges BDM, Dreskin SC, Chen X. Expression of recombinant Ara h 6 in Pichia pastoris but not in Escherichia coli preserves allergic effector function and allows assessment of specific mutations. Mol Nutr Food Res 2012; 56:986-95. [PMID: 22707273 DOI: 10.1002/mnfr.201100827] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
SCOPE Ara h 6 has recently been recognized as an important peanut allergen. Recombinant allergens have been used for analysis of IgE binding, but have not been used to analyze the allergic effector activity that is more relevant to allergic reactions. METHODS AND RESULTS Ara h 6 was expressed as a recombinant protein in both Escherichia coli and Pichia pastoris (rAra h 6-E. coli and rAra h 6-Pichia, respectively). Effector activity was assayed by measuring degranulation of RBL SX-38 cells sensitized with IgE from patients with severe peanut allergy. Compared to native Ara h 6 (nAra h 6), rAra h 6-Pichia had intact effector function whereas rAra h 6-E. coli had significantly reduced function. The lower effector activity in rAra h 6-E. coli compared to nAra h 6 and rAra h 6-Pichia did not appear to be due to differences in posttranslational modifications (analyzed by mass spectrometry and staining for carbohydrates) and may be due to subtle alteration(s) of folding seen on CD analysis and on nonreduced gels. Finally, we introduced point mutations in four important IgE-binding linear epitopes of Ara h 6 and found dramatically reduced allergic effector activity. CONCLUSION Our studies demonstrate the utility of fully functional rAra h 6-Pichia as a starting point for analysis of specific mutations that adversely affect allergic effector function.
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Affiliation(s)
- Yonghua Zhuang
- Department of Medicine, Division of Allergy and Clinical Immunology, University of Colorado Denver, Aurora, CO 80045, USA
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Chen X, Wang Q, El-Mezayen R, Zhuang Y, Dreskin SC. Ara h 2 and Ara h 6 have similar allergenic activity and are substantially redundant. Int Arch Allergy Immunol 2012; 160:251-8. [PMID: 23075924 DOI: 10.1159/000341642] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 07/06/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The moderately homologous (approx. 60%) proteins Ara h 2 and Ara h 6 are the most potent peanut allergens. This study was designed to define the relative individual contributions of Ara h 2 and Ara h 6 to the overall allergenic activity of a crude peanut extract (CPE). METHODS Ara h 2 and Ara h 6 were removed from CPE by gel filtration chromatography. Ara h 2.01, Ara h 2.02 and Ara h 6 were further purified (>99%). The potency of each allergen and the ability of these allergens to reconstitute the allergenic activity of CPE depleted of Ara h 2 and Ara h 6 was measured with RBL SX-38 cells sensitized with IgE from sensitized peanut allergic patients. RESULTS The potency of the native proteins were significantly different (p < 0.0001) although not dramatically so, with a rank order of Ara h 2.01 > Ara h 2.02 > Ara h 6. The addition of either purified Ara h 2 or Ara h 6 independently at their original concentration to CPE depleted of both Ara h 2 and Ara h 6 restored 80-100% of the original CPE allergenic activity. Addition of both Ara h 2 and Ara h 6 consistently completely restored the allergenic activity of CPE. CONCLUSIONS These studies indicate that either Ara h 2 or Ara h 6 independently can account for most of the allergenic activity in a CPE and demonstrate important redundancy in the allergenic activity of these related molecules.
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Affiliation(s)
- Xueni Chen
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO 80045, USA
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23
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Hazebrouck S, Guillon B, Drumare MF, Paty E, Wal JM, Bernard H. Trypsin resistance of the major peanut allergen Ara h 6 and allergenicity of the digestion products are abolished after selective disruption of disulfide bonds. Mol Nutr Food Res 2012; 56:548-57. [DOI: 10.1002/mnfr.201100614] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Stéphane Hazebrouck
- INRA, UR 496, Unité d’Immuno-Allergie Alimentaire, CEA/iBiTeC-S/SPI, CEA de Saclay; Gif-sur-Yvette France
| | - Blanche Guillon
- INRA, UR 496, Unité d’Immuno-Allergie Alimentaire, CEA/iBiTeC-S/SPI, CEA de Saclay; Gif-sur-Yvette France
| | - Marie-Françoise Drumare
- INRA, UR 496, Unité d’Immuno-Allergie Alimentaire, CEA/iBiTeC-S/SPI, CEA de Saclay; Gif-sur-Yvette France
| | - Evelyne Paty
- Université Paris Descartes Assistance Publique des Hôpitaux de Paris; Hôpital Necker Enfants Malades; Paris France
| | - Jean-Michel Wal
- INRA, UR 496, Unité d’Immuno-Allergie Alimentaire, CEA/iBiTeC-S/SPI, CEA de Saclay; Gif-sur-Yvette France
| | - Hervé Bernard
- INRA, UR 496, Unité d’Immuno-Allergie Alimentaire, CEA/iBiTeC-S/SPI, CEA de Saclay; Gif-sur-Yvette France
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Vissers YM, Blanc F, Skov PS, Johnson PE, Rigby NM, Przybylski-Nicaise L, Bernard H, Wal JM, Ballmer-Weber B, Zuidmeer-Jongejan L, Szépfalusi Z, Ruinemans-Koerts J, Jansen APH, Savelkoul HFJ, Wichers HJ, Mackie AR, Mills CEN, Adel-Patient K. Effect of heating and glycation on the allergenicity of 2S albumins (Ara h 2/6) from peanut. PLoS One 2011; 6:e23998. [PMID: 21901150 PMCID: PMC3162016 DOI: 10.1371/journal.pone.0023998] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Accepted: 07/29/2011] [Indexed: 11/19/2022] Open
Abstract
Background Peanut allergy is one of the most common and severe food allergies, and processing is known to influence the allergenicity of peanut proteins. We aimed to establish the effect of heating and glycation on the IgE-binding properties and biological activity of 2S albumins (Ara h 2/6) from peanut. Methodology/Principal Findings Native Ara h 2/6 was purified from raw peanuts and heated in solution (15 min, 110°C) in the presence or absence of glucose. Ara h 2 and 6 were also purified from roasted peanut. Using PBMC and sera from peanut-allergic patients, the cellular proliferative potency and IgE reactivity (reverse EAST inhibition) and functionality (basophil degranulation capacity) of allergens were assessed. Heating Ara h 2/6 at 110°C resulted in extensive denaturation, hydrolysis and aggregation of the protein, whilst Ara h 2 and 6 isolated from roasted peanut retained its native conformation. Allergen stimulation of PBMC induced proliferation and Th2 cytokine secretion which was unaffected by thermal processing. Conversely, IgE reactivity and functionality of Ara h 2/6 was decreased by heating. Whilst heating-glycation further reduced the IgE binding capacity of the proteins, it moderated their loss of histamine releasing capacity. Ara h 2 and 6 purified from roasted peanut demonstrated the same IgE reactivity as unheated, native Ara h 2/6. Conclusions/Significance Although no effect of processing on T-cell reactivity was observed, heat induced denaturation reduced the IgE reactivity and subsequent functionality of Ara h 2/6. Conversely, Ara h 2 and 6 purified from roasted peanut retained the structure and IgE reactivity/functionality of the native protein which may explain the allergenic potency of this protein. Through detailed molecular study and allergenicity assessment approaches, this work then gives new insights into the effect of thermal processing on structure/allergenicity of peanut proteins.
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Affiliation(s)
- Yvonne M Vissers
- Cell Biology and Immunology Group, Wageningen University and Research Centre, Wageningen, The Netherlands
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Radosavljevic J, Dobrijevic D, Jadranin M, Blanusa M, Vukmirica J, Cirkovic Velickovic T. Insights into proteolytic processing of the major peanut allergen Ara h 2 by endogenous peanut proteases. J Sci Food Agric 2010; 90:1702-1708. [PMID: 20564442 DOI: 10.1002/jsfa.4005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
BACKGROUND The major peanut allergens are Ara h 1, Ara h 2 and Ara h 6. Proteolytic processing has been shown to be required for the maturation process of Ara h 6. The aim of this study was to examine whether Ara h 2 undergoes proteolytic processing and, if so, whether proteolytic processing influences its ability to bind human immunoglobulin E (IgE). RESULTS Ara h 2 isolated from peanut extract under conditions of protease inhibition revealed a single additional peak for its two known isoforms (Ara h 2.01 and Ara h 2.02), corresponding to a C-terminally truncated form lacking a dipeptide (RY). Ara h 2 isolated in the absence of protease inhibition, however, yielded two additional peaks, identified as C-terminally truncated forms lacking either a dipeptide (RY) or a single tyrosine residue. The IgE-binding capacity of the Ara h 2 truncated forms was not altered. CONCLUSION Ara h 2 undergoes proteolytic processing by peanut proteases that involves C-terminal removal of a dipeptide. Hence Ara h 2 isolated from peanut extract is a complex mixture of two isoforms expressed by different genes, Ara h 2.01 and Ara h 2.02, as well as truncated forms generated by the proteolytic processing of these isoforms.
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Affiliation(s)
- Jelena Radosavljevic
- Department of Biochemistry, Faculty of Chemistry, University of Belgrade, Studentski Trg 12-16, Belgrade, Serbia.
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Schmidt H, Gelhaus C, Latendorf T, Nebendahl M, Petersen A, Krause S, Leippe M, Becker WM, Janssen O. 2-D DIGE analysis of the proteome of extracts from peanut variants reveals striking differences in major allergen contents. Proteomics 2009; 9:3507-21. [PMID: 19609960 DOI: 10.1002/pmic.200800938] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Over the last decade, an increasing prevalence of peanut allergies was observed worldwide. Peanuts are meanwhile categorized among the most dangerous food allergens. This is particularly relevant since peanut-derived ingredients are widely used in industrial food production. To minimize the problem of hidden food allergens causing severe anaphylactic reactions, pre-packaged food containing peanut components needs to be classified according to European ruling since 2005. Food companies search for strategies to reduce the allergenicity of peanut-derived food additives either by genetically altering the allergen content or by identifying peanut varieties with low levels of major allergens. In our study, we focused on peanut extracts from Indonesia that apparently contain lower levels of the major Arachis hypogaea allergen 1 (Ara h 1). Basic extracts of Virginia-type and Indonesian peanuts were compared by 1- and 2-DE. We identified more than hundred individual components in these extracts by MS and provide a high-resolution allergen map that also includes so far unknown fragments of major peanut allergens. The reduced level of Ara h 1 associated with a significantly lower abundance of the most potent peanut allergen Ara h 2 in various Indonesian peanuts was also confirmed by Western blotting with monoclonal antibodies and sera of allergic patients.
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Affiliation(s)
- Hendrik Schmidt
- Laboratory for Molecular Immunology, Institute for Immunology, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany
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Blanc F, Adel-Patient K, Drumare MF, Paty E, Wal JM, Bernard H. Capacity of purified peanut allergens to induce degranulation in a functional in vitro assay: Ara h 2 and Ara h 6 are the most efficient elicitors. Clin Exp Allergy 2009; 39:1277-85. [PMID: 19538351 DOI: 10.1111/j.1365-2222.2009.03294.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Peanut is a most common and potent food allergen. Many peanut allergens have been characterized using, in particular, IgE-binding studies. OBJECTIVES We optimized an in vitro functional assay to assess the capacity of peanut allergens to degranulate humanized rat basophilic leukaemia cells, RBL SX-38 cells, after sensitization by serum IgE from peanut-allergic patients. We thus compared the activity of the main peanut allergens, i.e. Ara h 1, Ara h 2, Ara h 3 and Ara h 6, purified from roasted peanut. METHODS Sera of 12 peanut-allergic patients were collected and total and peanut-specific IgE were measured. They were used to sensitize RBL SX-38 cells and the degranulation was induced by incubation with ranging concentrations of a whole peanut protein extract or of purified peanut allergens. The mediator release was quantified by the determination of beta-hexosaminidase activity in the supernatant. The intensity of the degranulation was expressed as maximum release and as EC50, corresponding to the dose of allergen that induced 50% of the maximum release. RESULTS For each serum, only 10 IU/mL of human IgE was necessary to sensitize the cells and obtain an optimal degranulation. With all the allergens, the release was positively correlated with the concentration of allergen-specific IgE in the serum used to sensitize the cells. The medians of EC50 obtained for Ara h 2 and Ara h 6 were 2.1 and 2.8 pm, respectively, while they were much higher for Ara h 3 and Ara h 1 (65 and 150 pm, respectively). CONCLUSION The RBL SX-38 release assay proved to be sensitive, specific and reproducible. It allowed the comparison of the degranulation potential of different peanut allergens. For all the sera tested, Ara h 2 and Ara h 6 were more potent than Ara h 1 or Ara h 3.
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Affiliation(s)
- F Blanc
- INRA, UR496, Unité d'Immuno-Allergie Alimentaire, Gif sur Yvette, Cedex, France
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Sordet C, Culerrier R, Granier C, Didier A, Rougé P. IgE-binding epitopic peptide mapping on a three-dimensional model built for the 13S globulin allergen of buckwheat (Fagopyrum esculentum). Peptides 2009; 30:1021-7. [PMID: 19463732 DOI: 10.1016/j.peptides.2009.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Revised: 03/05/2009] [Accepted: 03/05/2009] [Indexed: 11/25/2022]
Abstract
The three-dimensional model built for the 13S globulin allergen of buckwheat (Fagopyrum esculentum) consists of three protomers exhibiting the cupin motif, arranged in a homotrimer around a three-fold symmetry axis. Using the SPOT technique, 11 continuous IgE-binding epitopic peptides were characterized on the molecular surface of the 13S globulin allergen of buckwheat. Except for one of them, they all correspond to well exposed regions containing electropositiveley and/or electronegatively charged residues, which cover up to 40% of the molecular surface of the allergen. Some of these epitopes come in close contact to probably create more extended discontinuous epitopes, especially those located on the edge of the 13S globulin homotrimer. Half of the identified epitope peptides remain unaltered in a core structure protected against hydrolysis by digestive proteases and are thus assumed to promote the allergenicity of the 13S globulin. In addition, a few of these epitopes coincide with sequential IgE-binding epitopes previously characterized in soybean 11S globulins, that could account for the IgE-binding cross-reactions observed between soybean and buckwheat in Western blot experiments.
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Affiliation(s)
- Camille Sordet
- UMR-CNRS 5546, Université de Toulouse, Castanet Tolosan, France
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Bernard H, Drumare MF, Guillon B, Paty E, Scheinmann P, Wal JM. Immunochemical characterisation of structure and allergenicity of peanut 2S albumins using different formats of immunoassays. Anal Bioanal Chem 2009; 395:139-46. [DOI: 10.1007/s00216-009-2842-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/04/2009] [Accepted: 05/07/2009] [Indexed: 11/25/2022]
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Porterfield HS, Murray KS, Schlichting DG, Chen X, Hansen KC, Duncan MW, Dreskin SC. Effector activity of peanut allergens: a critical role for Ara h 2, Ara h 6, and their variants. Clin Exp Allergy 2009; 39:1099-108. [PMID: 19438581 DOI: 10.1111/j.1365-2222.2009.03273.x] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
RATIONALE An important property of allergens is their ability to cross-link IgE and activate mast cells and basophils. The effector activity of peanut allergens has not been well characterized. METHODS Crude extracts of fresh peanut flour were fractionated by gel filtration. Effector function was assayed by measuring degranulation of RBL SX-38 cells sensitized with IgE from individual sera and from pools of sera of peanut-allergic donors. RESULTS Following gel filtration, 75 +/- 7% of the applied protein and 76 +/- 16% (n=3) of the applied activity (assayed with a pool of 11 sera) were recovered in the resultant fractions. The majority (85 +/- 2%; n=3) of the recovered activity resided in a fraction with a theoretical average molecular weight of approximately 20 kDa and a range of 13-25 kDa. When all the individual fractions were recombined, the measured activity was similar to that of the original extract [140 +/- 43% when measured with a pool of serum (n=2) and 66 +/- 7% when measured with individual sera (n=4)]; when all individual fractions excluding the 20 kDa fraction were recombined, the measured activity was only 8 +/- 2% (n=2) of the original extract when assayed with the serum pool and 10 +/- 4% (n=3) when assayed with the individual sera. Two-dimensional gel electrophoresis of this biologically active fraction revealed >60 protein spots. Analysis of 50 of the most prominent spots by matrix-assisted laser-desorption ionization time-of-flight mass spectrometry and of the full mixture by automated tandem mass spectrometry coupled to online capillary liquid chromatography revealed that >97% of the protein mass consisted of Ara h 2.0101, Ara h 2.0201, Ara h 6 isoforms, and variants of these proteins. CONCLUSIONS Ara h 2 and Ara h 6 account for the majority of the effector activity found in a crude peanut extract.
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Affiliation(s)
- H S Porterfield
- Department of Medicine, University of Colorado at Denver, Aurora, CO 80262, USA
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Marsh J, Rigby N, Wellner K, Reese G, Knulst A, Akkerdaas J, van Ree R, Radauer C, Lovegrove A, Sancho A, Mills C, Vieths S, Hoffmann-Sommergruber K, Shewry PR. Purification and characterisation of a panel of peanut allergens suitable for use in allergy diagnosis. Mol Nutr Food Res 2009; 52 Suppl 2:S272-85. [PMID: 18727014 DOI: 10.1002/mnfr.200700524] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Peanut is a major cause of type 1 hypersensitive reactions including anaphylaxis. This results from the presence of a number of protein allergens, six of which are being studied as part of the EU FP6 EuroPrevall programme. These are Ara h 1 (7S globulin), Ara h 2, Ara h 6 (2S albumins), Ara h 3/4 (11S globulins) and Ara h 8 (Bet v 1 homologue). Methods for the purification of Ara h 1, Ara h 3/4, Ara h 2 and Ara h 6 from peanut seeds and for the production of recombinant Ara h 8 in Escherichia coli are described with spectroscopic analyses being used to confirm that they are authentically folded. N-terminal sequencing of the proteins purified from peanut seeds also revealed details of the differences between isoforms and their generation by proteolytic processing within the seed. Preliminary IgE binding studies of the purified allergens confirmed that they retained their immunological properties indicating their suitability for use in allergy diagnosis.
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Affiliation(s)
- Justin Marsh
- Rothamsted Research, Harpenden, Hertfordshire, UK
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Guimaraes V, Drumare MF, Ah-Leung S, Lereclus D, Bernard H, Créminon C, Wal JM, Adel-Patient K. Comparative study of the adjuvanticity ofBacillus thuringiensisCry1Ab protein and cholera toxin on allergic sensitisation and elicitation to peanut. FOOD AGR IMMUNOL 2008. [DOI: 10.1080/09540100802495651] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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Wischke C, Schwendeman SP. Principles of encapsulating hydrophobic drugs in PLA/PLGA microparticles. Int J Pharm 2008; 364:298-327. [PMID: 18621492 DOI: 10.1016/j.ijpharm.2008.04.042] [Citation(s) in RCA: 533] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 04/29/2008] [Accepted: 04/29/2008] [Indexed: 10/22/2022]
Abstract
Injectable biodegradable and biocompatible copolymers of lactic and glycolic acid (PLGA) are an important advanced delivery system for week-to-month controlled release of hydrophobic drugs (e.g., from biopharmaceutical classification system class IV), which often display poor oral bioavailability. The basic principles and considerations to develop such microparticle formulations is reviewed here based on a comprehensive study of papers and patents from the beginnings of hydrophobic drug encapsulation in polylactic acid and PLGA up through the very recent literature. Challenges with the diversity of drug properties, microencapsulation methods, and organic solvents are evaluated in light of the precedence of commercialized formulations and with a focus on decreasing the time to lab-scale encapsulation of water-insoluble drug candidates in the early stage of drug development. The influence of key formulation variables on final microparticle characteristics, and how best to avoid undesired microparticle properties, is analyzed mechanistically. Finally, concepts are developed to manage the common issues of maintaining sink conditions for in vitro drug release assays of hydrophobic compounds. Overall, against the backdrop of an increasing number of new, poorly orally available drug entities entering development, microparticle delivery systems may be a viable strategy to rescue an otherwise undeliverable substance.
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Affiliation(s)
- Christian Wischke
- Department of Pharmaceutical Sciences, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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