51
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Wu Z, Zhou N, Xiong F, Li X, Yang A, Tong P, Tang R, Chen H. Allergen composition analysis and allergenicity assessment of Chinese peanut cultivars. Food Chem 2015; 196:459-65. [PMID: 26593515 DOI: 10.1016/j.foodchem.2015.09.070] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Revised: 08/25/2015] [Accepted: 09/16/2015] [Indexed: 11/17/2022]
Abstract
Peanut (Arachis hypogaea) is among the eight major food allergens in the world. Several attempts have been made to decrease or eliminate the allergenicity of peanut. Systemic screening of thousands of peanut cultivars may identify peanut with low allergenicity. In this study, the allergen compositions of 53 Chinese peanut cultivars were characterized, and their allergenicity to sera IgE of Chinese patients and in a mouse model was assessed. Contents of total protein and allergens were quantified by SDS-PAGE and densitometry analysis on gel. Although the contents of allergens broadly varied among cultivars, they were related to one another. The IgE binding capacity of cultivars was tested by ELISA, and their allergenicity was further evaluated in a mouse model by oral sensitization. Results showed that the allergenicity of peanut was affected by allergen composition rather than a single allergen. Peanut cultivars with low allergenicity may contain more Ara h 3/4 (24 kDa), Ara h 2 and less Ara h 3/4 (43, 38, and 36 kDa), Ara h 6. Screening based on allergen composition would facilitate the identification of low-allergenic peanut.
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Affiliation(s)
- Zhihua Wu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Sino-German Joint Research Institute, Nanchang University, Nanchang 330047, China
| | - Ningling Zhou
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Sino-German Joint Research Institute, Nanchang University, Nanchang 330047, China; Department of Food Science, Nanchang University, Nanchang 330047, China
| | - Faqian Xiong
- Cash Crops Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Xin Li
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Department of Food Science, Nanchang University, Nanchang 330047, China
| | - Anshu Yang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Sino-German Joint Research Institute, Nanchang University, Nanchang 330047, China
| | - Ping Tong
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China
| | - Ronghua Tang
- Cash Crops Research Institute, Guangxi Academy of Agricultural Sciences, Nanning 530007, China
| | - Hongbing Chen
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Sino-German Joint Research Institute, Nanchang University, Nanchang 330047, China.
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52
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Leung NY, Wai CY, Ho MH, Liu R, Lam KS, Wang JJ, Shu SA, Chu KH, Leung PS. Screening and identification of mimotopes of the major shrimp allergen tropomyosin using one-bead-one-compound peptide libraries. Cell Mol Immunol 2015; 14:308-318. [PMID: 26364917 DOI: 10.1038/cmi.2015.83] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/06/2015] [Accepted: 08/06/2015] [Indexed: 12/18/2022] Open
Abstract
The one-bead-one-compound (OBOC) combinatorial peptide library is a powerful tool to identify ligand and receptor interactions. Here, we applied the OBOC library technology to identify mimotopes specific to the immunoglobulin E (IgE) epitopes of the major shellfish allergen tropomyosin. OBOC peptide libraries with 8-12 amino acid residues were screened with serum samples from patients with shellfish allergy for IgE mimotopes of tropomyosin. Twenty-five mimotopes were identified from the screening and their binding reactivity to tropomyosin-specific IgE was confirmed by peptide ELISA. These mimotopes could be divided into seven clusters based on sequence homology, and epitope mapping by EpiSearch of the clustered mimotopes was performed to characterize and confirm the validity of mimotopes. Five out of six of the predicted epitopes were found to overlap with previously identified epitopes of tropomyosin. To further confirm the mimicry potential of mimotopes, BALB/c mice were immunized with mimotopes conjugated to keyhole limpet hemocyanin and assayed for their capacity to induce tropomyosin-specific antibodies. BALB/c mice that received mimotope immunization were found to have an elevated level of tropomyosin-specific immunoglobulin G, but not mice that received an irrelevant mimotope. This study pioneers the successful application of the OBOC libraries using whole sera to screen and identify multiple shrimp allergen mimotopes and validates their mimicry potential using in vitro, in vivo, and in silico methods.Cellular & Molecular Immunology advance online publication, 14 september 2015; doi:10.1038/cmi.2015.83.
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Affiliation(s)
- Nicki Yh Leung
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Christine Yy Wai
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Marco Hk Ho
- Department of Pediatrics and Adolescent Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Ruiwu Liu
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA 95616, USA
| | - Kit S Lam
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA 95616, USA
| | - Jin Jun Wang
- Division of Rheumatology/Allergy, School of Medicine, University of California, Davis, CA 95616, USA
| | - Shang An Shu
- Division of Rheumatology/Allergy, School of Medicine, University of California, Davis, CA 95616, USA
| | - Ka Hou Chu
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
| | - Patrick Sc Leung
- Division of Rheumatology/Allergy, School of Medicine, University of California, Davis, CA 95616, USA
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53
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Christiansen A, Kringelum JV, Hansen CS, Bøgh KL, Sullivan E, Patel J, Rigby NM, Eiwegger T, Szépfalusi Z, de Masi F, Nielsen M, Lund O, Dufva M. High-throughput sequencing enhanced phage display enables the identification of patient-specific epitope motifs in serum. Sci Rep 2015; 5:12913. [PMID: 26246327 PMCID: PMC4650709 DOI: 10.1038/srep12913] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 07/08/2015] [Indexed: 12/13/2022] Open
Abstract
Phage display is a prominent screening technique with a multitude of applications including therapeutic antibody development and mapping of antigen epitopes. In this study, phages were selected based on their interaction with patient serum and exhaustively characterised by high-throughput sequencing. A bioinformatics approach was developed in order to identify peptide motifs of interest based on clustering and contrasting to control samples. Comparison of patient and control samples confirmed a major issue in phage display, namely the selection of unspecific peptides. The potential of the bioinformatic approach was demonstrated by identifying epitopes of a prominent peanut allergen, Ara h 1, in sera from patients with severe peanut allergy. The identified epitopes were confirmed by high-density peptide micro-arrays. The present study demonstrates that high-throughput sequencing can empower phage display by (i) enabling the analysis of complex biological samples, (ii) circumventing the traditional laborious picking and functional testing of individual phage clones and (iii) reducing the number of selection rounds.
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Affiliation(s)
- Anders Christiansen
- Department of Micro- and Nanotechnology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Jens V Kringelum
- Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Christian S Hansen
- Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Katrine L Bøgh
- National Food Institute, Technical University of Denmark, Søborg, Denmark
| | - Eric Sullivan
- Roche NimbleGen, Madison, Wisconsin, the United States of America
| | - Jigar Patel
- Roche NimbleGen, Madison, Wisconsin, the United States of America
| | - Neil M Rigby
- Institute of Food Research, Norwich, United Kingdom
| | - Thomas Eiwegger
- Department of Paediatrics, Medical University of Vienna, Vienna, Austria
| | - Zsolt Szépfalusi
- Department of Paediatrics, Medical University of Vienna, Vienna, Austria
| | - Federico de Masi
- Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Morten Nielsen
- 1] Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark [2] Instituto de Investigaciones Biotecnológicas, Universidad Nacional de San Martín, Buenos Aires, Argentina
| | - Ole Lund
- Center for Biological Sequence Analysis, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Martin Dufva
- Department of Micro- and Nanotechnology, Technical University of Denmark, Kgs. Lyngby, Denmark
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54
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Sealey-Voyksner J, Zweigenbaum J, Voyksner R. Discovery of highly conserved unique peanut and tree nut peptides by LC-MS/MS for multi-allergen detection. Food Chem 2015; 194:201-11. [PMID: 26471545 DOI: 10.1016/j.foodchem.2015.07.043] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/18/2015] [Accepted: 07/09/2015] [Indexed: 12/12/2022]
Abstract
Proteins unique to peanuts and various tree nuts have been extracted, subjected to trypsin digestion and analysis by liquid chromatography/quadrupole time-of-flight mass spectrometry, in order to find highly conserved peptides that can be used as markers to detect peanuts and tree nuts in food. The marker peptide sequences chosen were those found to be present in both native (unroasted) and thermally processed (roasted) forms of peanuts and tree nuts. Each peptide was selected by assuring its presence in food that was processed or unprocessed, its abundance for sensitivity, sequence size, and uniqueness for peanut and each specific variety of tree nut. At least two peptides were selected to represent peanut, almond, pecan, cashew, walnut, hazelnut, pine nut, Brazil nut, macadamia nut, pistachio nut, chestnut and coconut; to determine the presence of trace levels of peanut and tree nuts in food by a novel multiplexed LC-MS method.
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Affiliation(s)
| | - Jerry Zweigenbaum
- Agilent Technologies, Inc., 2850 Centerville Road, Wilmington, DE, USA
| | - Robert Voyksner
- LCMS Limited, 1502 West Hwy NC-54, Suite 504, Durham, NC, USA.
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55
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Hoh RA, Joshi SA, Liu Y, Wang C, Roskin KM, Lee JY, Pham T, Looney TJ, Jackson KJL, Dixit VP, King J, Lyu SC, Jenks J, Hamilton RG, Nadeau KC, Boyd SD. Single B-cell deconvolution of peanut-specific antibody responses in allergic patients. J Allergy Clin Immunol 2015; 137:157-167. [PMID: 26152318 DOI: 10.1016/j.jaci.2015.05.029] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Revised: 05/09/2015] [Accepted: 05/15/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND The frequencies, cellular phenotypes, epitope specificity, and clonal diversity of allergen-specific B cells in patients with food allergy are not fully understood but are of major pathogenic and therapeutic significance. OBJECTIVE We sought to characterize peanut allergen-specific B-cell populations and the sequences and binding activities of their antibodies before and during immunotherapy. METHODS B cells binding fluorescently labeled Ara h 1 or Ara h 2 were phenotyped and isolated by means of flow cytometric sorting from 18 patients at baseline and 13 patients during therapy. Fifty-seven mAbs derived from allergen-binding single B cells were evaluated by using ELISA, Western blotting, and peptide epitope mapping. Deep sequencing of the B-cell repertoires identified additional members of the allergen-specific B-cell clones. RESULTS Median allergen-binding B-cell frequencies were 0.0097% (Ara h 1) or 0.029% (Ara h 2) of B cells in baseline blood from allergic patients and approximately 3-fold higher during immunotherapy. Five of 57 allergen-specific cells belonged to clones containing IgE-expressing members. Almost all allergen-specific antibodies were mutated, and binding to both conformational and linear allergen epitopes was detected. Increasing somatic mutation of IgG4 members of a clone was seen in immunotherapy, whereas IgE mutation levels in the clone did not increase. CONCLUSION Most peanut allergen-binding B cells isolated by means of antigen-specific flow sorting express mutated and isotype-switched antibodies. Immunotherapy increases their frequency in the blood, and even narrowly defined allergen epitopes are recognized by numerous distinct B-cell clones in a patient. The results also suggest that oral immunotherapy can stimulate somatic mutation of allergen-specific IgG4.
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Affiliation(s)
- Ramona A Hoh
- Department of Pathology, Stanford University, Stanford, Calif
| | - Shilpa A Joshi
- Department of Pathology, Stanford University, Stanford, Calif
| | - Yi Liu
- Department of Pathology, Stanford University, Stanford, Calif; Biomedical Informatics Training Program, Stanford University, Stanford, Calif
| | - Chen Wang
- Department of Pathology, Stanford University, Stanford, Calif
| | | | - Ji-Yeun Lee
- Department of Pathology, Stanford University, Stanford, Calif
| | - Tho Pham
- Department of Pathology, Stanford University, Stanford, Calif
| | - Tim J Looney
- Department of Pathology, Stanford University, Stanford, Calif
| | | | | | - Jasmine King
- Department of Pathology, Stanford University, Stanford, Calif
| | - Shu-Chen Lyu
- Department of Pediatrics, Stanford University, Stanford, Calif
| | - Jennifer Jenks
- Department of Pediatrics, Stanford University, Stanford, Calif
| | - Robert G Hamilton
- Division of Allergy and Clinical Immunology, School of Medicine, Johns Hopkins University, Baltimore, Md
| | - Kari C Nadeau
- Department of Pediatrics, Stanford University, Stanford, Calif
| | - Scott D Boyd
- Department of Pathology, Stanford University, Stanford, Calif.
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56
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Wollmann E, Hamsten C, Sibanda E, Ochome M, Focke-Tejkl M, Asarnoj A, Önell A, Lilja G, Gallerano D, Lupinek C, Thalhamer T, Weiss R, Thalhamer J, Wickman M, Valenta R, van Hage M. Natural clinical tolerance to peanut in African patients is caused by poor allergenic activity of peanut IgE. Allergy 2015; 70:638-52. [PMID: 25683061 DOI: 10.1111/all.12592] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2015] [Indexed: 11/30/2022]
Abstract
BACKGROUND In Africa, peanuts are frequently consumed, but severe allergic reactions are rare. We investigated immunological patterns of clinical tolerance to peanut in peanut-sensitized but asymptomatic patients from central Africa compared to peanut-allergic and peanut-sensitized but asymptomatic patients from Sweden. METHODS Sera from allergic patients (n = 54) from Zimbabwe sensitized to peanut but without allergic symptoms to peanut, and sera from peanut-allergic (n = 25) and peanut-sensitized but asymptomatic (n = 25) patients from Sweden were analyzed toward peanut allergen components (Ara h 1-3, 6, 8-9) and other allergen molecules from important allergen sources using microarray. IgE to Ara h 2 peptide epitopes was analyzed, and allergenic activity was assessed by basophil activation assay. RESULTS Forty-six percent of the African and all peanut-allergic Swedish patients showed IgE toward one of the highly allergenic peanut allergens (Ara h 1-3, 6, 9). However, 48% of the African patients had IgE to cross-reactive carbohydrate determinants (CCDs) with low allergenic activity and 60% of the Swedish asymptomatic patients had IgE against the PR protein Ara h 8. IgG and IgG4 specificities and levels could not discriminate between the African asymptomatic and Swedish peanut-allergic patients. Asymptomatic patients almost lacked IgE to Ara h 2 peptides, which were recognized by peanut-allergic patients. Peanut IgE from peanut asymptomatic patients showed poor allergenic activity compared with IgE from peanut-allergic patients. CONCLUSIONS Natural clinical tolerance to peanut in the African patients can be caused by IgE to low allergenic peanut components and by poor allergenic activity of peanut-specific IgE.
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Affiliation(s)
- E. Wollmann
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - C. Hamsten
- Department of Medicine Solna; Clinical Immunology and Allergy Unit; Karolinska Institutet and University Hospital; Stockholm Sweden
- Center for Inflammatory Diseases; Karolinska Institutet; Stockholm Sweden
| | - E. Sibanda
- University of Zimbabwe Medical School; Harare Zimbabwe
| | - M. Ochome
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - M. Focke-Tejkl
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - A. Asarnoj
- Department of Medicine Solna; Clinical Immunology and Allergy Unit; Karolinska Institutet and University Hospital; Stockholm Sweden
- Astrid Lindgren Children's Hospital; Stockholm Sweden
| | - A. Önell
- Thermo Fisher Scientific ImmunoDiagnostics; Uppsala Sweden
| | - G. Lilja
- Department of Pediatrics; Sachs' Children's Hospital; Stockholm Sweden
| | - D. Gallerano
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - C. Lupinek
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - T. Thalhamer
- Department of Molecular Biology; University of Salzburg; Salzburg Austria
| | - R. Weiss
- Department of Molecular Biology; University of Salzburg; Salzburg Austria
| | - J. Thalhamer
- Department of Molecular Biology; University of Salzburg; Salzburg Austria
| | - M. Wickman
- Department of Pediatrics; Sachs' Children's Hospital; Stockholm Sweden
- Institute of Environmental Medicine; Karolinska Institutet; Stockholm Sweden
| | - R. Valenta
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center for Pathophysiology, Infectiology and Immunology; Medical University of Vienna; Vienna Austria
| | - M. van Hage
- Department of Medicine Solna; Clinical Immunology and Allergy Unit; Karolinska Institutet and University Hospital; Stockholm Sweden
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57
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Kühne Y, Reese G, Ballmer-Weber BK, Niggemann B, Hanschmann KM, Vieths S, Holzhauser T. A Novel Multipeptide Microarray for the Specific and Sensitive Mapping of Linear IgE-Binding Epitopes of Food Allergens. Int Arch Allergy Immunol 2015; 166:213-24. [PMID: 25924626 DOI: 10.1159/000381344] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 02/27/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The identification of B-cell epitopes of food allergens can possibly lead to novel diagnostic tools and therapeutic reagents for food allergy. We sought to develop a flexible, low-tech, cost-effective and reproducible multipeptide microarray for the research environment to enable large-scale screening of IgE epitopes of food allergens. METHODS Overlapping peptides (15-mer, 4 amino acid offset) covering the primary sequence of either peanut allergen Ara h 1 or all 3 subunits of the soybean allergen Gly m 5 were simultaneously synthesized in-house on a porous cellulose matrix. Identical peptide microarrays created with up to 384 duplicate peptide-cellulose microspots each were investigated for specificity and sensitivity in IgE immunodetection and in direct experimental comparison to the formerly established SPOT™ membrane technique. RESULTS The in-house microarray identified with 98% reproducibility the same IgE-binding peptides as the SPOT™ membrane technique. Additional IgE-binding peptides were identified using the microarray. While the sensitivity was increased between 2- and 20-fold, the amount of human serum required was reduced by at least two thirds over the SPOT™ membrane technique using the microarray. After subtraction of the potential background, we did not observe non-specific binding to the presented peptides on microarray. CONCLUSIONS The novel peptide microarray allows simple and cost-effective screening for potential epitopes of large allergenic legume seed storage proteins, and it could be adapted for other food allergens as well, to study allergenic epitopes at the individual subject level in large paediatric and adult study groups of food allergic subjects.
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Affiliation(s)
- Yvonne Kühne
- Division of Allergology, Paul-Ehrlich-Institut, Langen, Germany
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58
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Mattison CP, Dinter J, Berberich MJ, Chung SY, Reed SS, Le Gall S, Grimm CC. In vitro evaluation of digestive and endolysosomal enzymes to cleave CML-modified Ara h 1 peptides. Food Sci Nutr 2015; 3:273-83. [PMID: 26288719 PMCID: PMC4534154 DOI: 10.1002/fsn3.215] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 02/10/2015] [Indexed: 12/15/2022] Open
Abstract
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.
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Affiliation(s)
- Christopher P Mattison
- United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124
| | - Jens Dinter
- Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139 ; Harvard Medical School Boston, Massachusetts
| | - Matthew J Berberich
- Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139
| | - Si-Yin Chung
- United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124
| | - Shawndrika S Reed
- United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124
| | - Sylvie Le Gall
- Ragon Institute of MGH, MIT and Harvard 400 Technology Square, Cambridge, Massachusetts, 02139 ; Harvard Medical School Boston, Massachusetts
| | - Casey C Grimm
- United States Department of Agriculture - Agricultural Research Service - Southern Regional Research Center 1100 Robert E. Lee Blvd., New Orleans, Louisiana, 70124
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Sharma P, Gaur SN, Goel N, Arora N. Engineered hypoallergenic variants of osmotin demonstrate hypoallergenicity with in vitro and in vivo methods. Mol Immunol 2015; 64:46-54. [DOI: 10.1016/j.molimm.2014.10.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 10/13/2014] [Accepted: 10/25/2014] [Indexed: 12/15/2022]
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60
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Abstract
Peanut allergy is an IgE-mediated, persisting immune disorder that is of major concern worldwide. Currently, no routine immunotherapy is available to treat this often severe and sometimes fatal food allergy. Traditional subcutaneous allergen immunotherapy with crude peanut extracts has proven not feasible due to the high risk of severe systemic side effects. The allergen-specific approaches under preclinical and clinical investigation comprise subcutaneous, oral, sublingual and epicutaneous immunotherapy with whole-peanut extracts as well as applications of hypoallergenic peanut allergens or T cell epitope peptides. Allergen-nonspecific approaches include monoclonal anti-IgE antibodies, TCM herbal formulations and Toll-like receptor 9-based immunotherapy. The potential of genetically engineered plants with reduced allergen levels is being explored as well as the beneficial influence of lactic acid bacteria and soybean isoflavones on peanut allergen-induced symptoms. Although the underlying mechanisms still need to be elucidated, several of these strategies hold great promise. It can be estimated that individual strategies or a combination thereof will result in a successful immunotherapy regime for peanut-allergic individuals within the next decade.
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Affiliation(s)
- Merima Bublin
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
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61
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Hurlburt BK, McBride JK, Nesbit JB, Ruan S, Maleki SJ. Purification of Recombinant Peanut Allergen Ara h 1 and Comparison of IgE Binding to the Natural Protein. Foods 2014; 3:642-657. [PMID: 28234343 PMCID: PMC5302246 DOI: 10.3390/foods3040642] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Revised: 11/24/2014] [Accepted: 11/29/2014] [Indexed: 11/16/2022] Open
Abstract
Allergic reactions to food are on the rise worldwide and there is a corresponding increase in interest to understand the molecular mechanisms responsible. Peanut allergies are the most problematic because the reaction often persists into adulthood and can be as severe as anaphylaxis and death. The purpose of the work presented here was to develop a reproducible method to produce large quantities of pure recombinant Ara h 1(rAra h 1) that will enable standardization of immunological tests for patients and allow structural and immunological studies on the wild type and mutagenized forms of the protein. Ara h 1 is initially a pre-pro-protein which, following two endoproteolytic cleavages, becomes the mature form found in peanut. The mature form however has flexible regions that make it refractory to some structural studies including crystallography. Therefore, independent purification of the mature and core regions was desirable. Expression constructs were synthesized cDNA clones for each in a pET plasmid vector without tags. Codons were optimized for expression in E. coli. High-level expression was achieved in BL21 strains. Purification to near homogeneity was achieved by a combination of ammonium sulfate precipitation and ion exchange chromatography. The purified rAra h 1 was then compared with natural Ara h 1 for IgE binding. All patients recognized both the folded natural and rAra h 1, but the IgE binding to the rArah1 was significantly reduced in comparison to the natural allergen, which could potentially make it useful for immunotherapeutic purposes.
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Affiliation(s)
- Barry K Hurlburt
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 1100 Robert E. Lee, Blvd., New Orleans, LA 70124, USA.
| | - Jane K McBride
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 1100 Robert E. Lee, Blvd., New Orleans, LA 70124, USA.
| | - Jacqueline B Nesbit
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 1100 Robert E. Lee, Blvd., New Orleans, LA 70124, USA.
| | - Sanbao Ruan
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 1100 Robert E. Lee, Blvd., New Orleans, LA 70124, USA.
| | - Soheila J Maleki
- Southern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 1100 Robert E. Lee, Blvd., New Orleans, LA 70124, USA.
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62
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Baar A, Pahr S, Constantin C, Giavi S, Papadopoulos NG, Pelkonen AS, Mäkelä MJ, Scheiblhofer S, Thalhamer J, Weber M, Ebner C, Mari A, Vrtala S, Valenta R. The high molecular weight glutenin subunit Bx7 allergen from wheat contains repetitive IgE epitopes. Allergy 2014; 69:1316-23. [PMID: 24943225 DOI: 10.1111/all.12464] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/16/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Wheat is one of the most common food allergen sources for children and adults. The aim of this study was to characterize new wheat allergens using an IgE discovery approach and to investigate their IgE epitopes. METHODS A cDNA expression library representing the wheat transcriptome was constructed in phage lambda gt11 and screened with IgE antibodies from wheat food allergic patients. IgE-reactive cDNA clones coding for portions of high molecular weight (HMW) glutenin subunits were identified by sequence analysis of positive clones. IgE epitopes were characterized using recombinant fragments from the HMW Bx7 and synthetic peptides thereof for testing of allergic patients' sera and in basophil degranulation assays. RESULTS We found that the major IgE-reactive areas of HMW glutenins are located in the repetitive regions of the protein and could show that two independent IgE-reactive fragments from HMW Bx7 contained repetitive IgE epitopes. CONCLUSIONS Our results demonstrate that IgE antibodies from wheat food allergic patients can recognize repetitive epitopes in one of the important wheat food allergens. Recombinant HMW Bx7 may be included into the panel of allergens for component-resolved diagnosis of wheat food allergy.
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Affiliation(s)
- A. Baar
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
- Christian Doppler Laboratory for the Development of Allergen Chips; Medical University of Vienna; Vienna Austria
| | - S. Pahr
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
- Christian Doppler Laboratory for the Development of Allergen Chips; Medical University of Vienna; Vienna Austria
| | - C. Constantin
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
| | - S. Giavi
- Allergy and Immunology Research Centre; University of Athens; Athens Greece
| | - N. G. Papadopoulos
- Allergy and Immunology Research Centre; University of Athens; Athens Greece
| | - A. S. Pelkonen
- Skin and Allergy Hospital; Helsinki University Central Hospital; Helsinki Finland
| | - M. J. Mäkelä
- Skin and Allergy Hospital; Helsinki University Central Hospital; Helsinki Finland
| | - S. Scheiblhofer
- Department of Molecular Biology; University of Salzburg; Salzburg Austria
| | - J. Thalhamer
- Department of Molecular Biology; University of Salzburg; Salzburg Austria
| | - M. Weber
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
| | - C. Ebner
- Ambulatory for Allergy and Clinical Immunology; Vienna Austria
| | - A. Mari
- Associated Centers for Molecular Allergology; Rome Italy
| | - S. Vrtala
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
- Christian Doppler Laboratory for the Development of Allergen Chips; Medical University of Vienna; Vienna Austria
| | - R. Valenta
- Division of Immunopathology; Department of Pathophysiology and Allergy Research; Center of Pathophysiology, Infectiology & Immunology; Vienna General Hospital; Medical University of Vienna; Vienna Austria
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63
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Taliercio E, Loveless TM, Turano MJ, Kim SW. Identification of epitopes of the β subunit of soybean β-conglycinin that are antigenic in pigs, dogs, rabbits and fish. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2014; 94:2289-94. [PMID: 24415270 DOI: 10.1002/jsfa.6556] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 11/01/2013] [Accepted: 01/10/2014] [Indexed: 06/03/2023]
Abstract
BACKGROUND β-Conglycinin (conglycinin) is one of the major seed storage proteins of soybean. Conglycinin is a 7S trimer composed of different combinations of β, α and α' subunits. All subunits of conglycinin have been reported to be allergenic in humans. The goal of this research is to identify epitopes of the β subunit of conglycinin that are antigenic in multiple animal species. RESULTS Sera from pigs, dogs, rabbits and hybrid striped bass that had antibodies against soybean conglycinin were identified by ELISA. Most of these sera recognized peptides that represent the β subunit of conglycinin. One antigenic region of the β subunit of conglycinin had considerable overlap among all species tested. One region that was similar to a peanut allergenic epitope in humans overlapped with a region that binds IgE from dogs. One region was antigenic in multiple rabbits and pigs, suggesting it may play a role in the response of pigs to soybean in the diet. CONCLUSION One region of the β subunit of conglycinin is an important antigen across species and abuts a region similar to the peanut allergen ARA h 1. A second region is particularly antigenic in pigs and rabbits. Variants of these antigenic regions of the β subunit of conglycinin may be useful in determining the role these regions play in the health of animals fed soybean. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.
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Abstract
Presently, allergy diagnosis and therapy procedures are undergoing a transition phase in which allergen extracts are being step-by-step replaced by molecule-based products. The new developments will allow clinicians to obtain detailed information on sensitization patterns, more accurate interpretation of allergic symptoms, and thus improved patients' management. In this respect, recombinant technology has been applied to develop this new generation of molecule-based allergy products. The use of recombinant allergens allows full validation of identity, quantity, homogeneity, structure, aggregation, solubility, stability, IgE-binding and the biologic potency of the products. In contrast, such parameters are extremely difficult to assay and standardize for extract-based products. In addition to the possibility of bulk production of wild type molecules for diagnostic purposes, recombinant technology opened the possibility of developing safer and more efficacious products for allergy therapy. A number of molecule-based hypoallergenic preparations have already been successfully evaluated in clinical trials, bringing forward the next generation of allergy vaccines. In this contribution, we review the latest developments in allergen characterization, molecule-based allergy diagnosis, and the application of recombinant allergens in therapeutic setups. A comprehensive overview of clinical trials using recombinant allergens as well as synthetic peptides is presented.
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Affiliation(s)
- Fatima Ferreira
- Christian Doppler Laboratory for Allergy Diagnosis and Therapy, Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
| | - Martin Wolf
- Christian Doppler Laboratory for Allergy Diagnosis and Therapy, Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Michael Wallner
- Christian Doppler Laboratory for Allergy Diagnosis and Therapy, Department of Molecular Biology, University of Salzburg, Salzburg, Austria
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65
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Bøgh K, Nielsen H, Eiwegger T, Madsen C, Mills E, Rigby N, Szépfalusi Z, Roggen E. IgE versus IgG4 epitopes of the peanut allergen Ara h 1 in patients with severe allergy. Mol Immunol 2014; 58:169-76. [DOI: 10.1016/j.molimm.2013.11.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 11/21/2013] [Indexed: 10/25/2022]
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66
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Lisson M, Novak N, Erhardt G. Immunoglobulin E epitope mapping by microarray immunoassay reveals differences in immune response to genetic variants of caseins from different ruminant species. J Dairy Sci 2014; 97:1939-54. [DOI: 10.3168/jds.2013-7355] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 12/08/2013] [Indexed: 12/25/2022]
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67
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Prickett SR, Voskamp AL, Phan T, Dacumos-Hill A, Mannering SI, Rolland JM, O'Hehir RE. Ara h 1 CD4+ T cell epitope-based peptides: candidates for a peanut allergy therapeutic. Clin Exp Allergy 2014; 43:684-97. [PMID: 23711131 PMCID: PMC3709139 DOI: 10.1111/cea.12113] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 02/25/2013] [Accepted: 02/27/2013] [Indexed: 12/01/2022]
Abstract
Background Peanut allergy is a life-threatening condition; there is currently no cure. While whole allergen extracts are used for specific immunotherapy for many allergies, they can cause severe reactions and even fatalities in peanut allergy. Objective To identify short, HLA-degenerate CD4+ T cell epitope-based peptides of the major peanut allergen Ara h 1 that target allergen-specific T cells without causing IgE-mediated inflammatory cell activation, as candidates for safe peanut-specific immunotherapy. Methods Ara h 1-specific CD4+ T cell lines (TCL) were generated from peripheral blood mononuclear cells (PBMC) of peanut-allergic subjects using CFSE-based methodology. T cell epitopes were identified using CFSE and thymidine-based proliferation assays. Epitope HLA-restriction was investigated using blocking antibodies, HLA-genotyping and epitope prediction algorithms. Functional peanut-specific IgE reactivity to peptides was assessed by basophil activation assay. Results A total of 145 Ara h 1-specific TCL were generated from 18 HLA-diverse peanut-allergic subjects. The TCL recognized 20-mer peptides throughout Ara h 1. Nine 20-mers containing the most frequently recognized epitopes were selected and their recognition confirmed in 18 additional peanut-allergic subjects. Ten core epitopes were mapped within these 20-mers. These were HLA-DQ and/or HLA–DR restricted, with each presented on at least two different HLA-molecules. Seven short (≤ 20 aa) non-basophil-reactive peptides encompassing all core epitopes were designed and validated in peanut-allergic donor PBMC T cell assays. Conclusions and Clinical Relevance Short CD4+ T cell epitope-based Ara h 1 peptides were identified as novel candidates for a safe, T cell targeted peanut-specific immunotherapy for HLA-diverse populations.
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Affiliation(s)
- S R Prickett
- Department of Immunology, Monash University, Melbourne, Vic., Australia
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68
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Jin T, Wang Y, Chen YW, Fu TJ, Kothary MH, McHugh TH, Zhang Y. Crystal structure of Korean pine (Pinus koraiensis) 7S seed storage protein with copper ligands. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:222-8. [PMID: 24328105 DOI: 10.1021/jf4039887] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
The prevalence of food allergy has increased in recent years, and Korean pine vicilin is a potential food allergen. We have previously reported the crystallization of Korean pine vicilin purified from raw pine nut. Here we report the isolation of vicilin mRNA and the crystal structure of Korean pine vicilin at 2.40 Å resolution. The overall structure of pine nut vicilin is similar to the structures of other 7S seed storage proteins and consists of an N-terminal domain and a C-terminal domain. Each assumes a cupin fold, and they are symmetrically related about a pseudodyad axis. Three vicilin molecules form a doughnut-shaped trimer through head-to-tail association. Structure characterization of Korean pine nut vicilin unexpectedly showed that, in its native trimeric state, the vicilin has three copper ligands. Sequence alignments suggested that the copper-coordinating residues were conserved in winter squash, sesame, tomato, and several tree nuts, while they were not conserved in a number of legumes, including peanut and soybean. Additional studies are needed to assess whether the copper-coordinating property of vicilins has a biological function in the relevant plants. The nutritional value of this copper-coordinating protein in tree nuts and other edible seeds may be worth further investigations.
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Affiliation(s)
- Tengchuan Jin
- Department of Biology, Illinois Institute of Technology , 3101 South Dearborn Street, Chicago, Illinois 60616, United States
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69
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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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70
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Price D, Ackland L, Suphioglu C. Nuts 'n' guts: transport of food allergens across the intestinal epithelium. Asia Pac Allergy 2013; 3:257-65. [PMID: 24260731 PMCID: PMC3826608 DOI: 10.5415/apallergy.2013.3.4.257] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 10/04/2013] [Indexed: 01/07/2023] Open
Abstract
The increase in the incidence of food allergy is a growing problem for the western world. This review will focus on the findings from several macromolecular epithelial transport experiments and drug permeability studies to provide a recent comprehension of food allergen intestinal epithelial cell transport and the allergen-epithelial relationship. Specifically, this review will aim to answer whether allergens can permeate the intestinal barrier directly via intestinal epithelial cells, and whether this mode of transport affects downstream immune reactions. By improving our understanding of the interactions which take place during exposure of food allergens with the intestinal epithelium, we can begin to understand whether the epithelial barrier plays a major role in the allergic sensitization process rather than simply restricting the entry of allergens to the underlying lamina propria.
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Affiliation(s)
- Dwan Price
- Centre for Cellular and Molecular Biology, School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, Burwood, VIC 3125, Australia. ; NeuroAllergy Research Laboratory, School of Life and Environmental Sciences, Faculty of Science, Engineering and Built Environment, Deakin University, Geelong, VIC 3216, Australia
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71
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Radosavljevic J, Nordlund E, Mihajlovic L, Krstic M, Bohn T, Buchert J, Velickovic TC, Smit J. Sensitizing potential of enzymatically cross-linked peanut proteins in a mouse model of peanut allergy. Mol Nutr Food Res 2013; 58:635-46. [DOI: 10.1002/mnfr.201300403] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/22/2013] [Accepted: 07/30/2013] [Indexed: 01/01/2023]
Affiliation(s)
| | | | - Luka Mihajlovic
- University of Belgrade; Faculty of Chemistry; Belgrade Serbia
| | - Maja Krstic
- University of Belgrade; Faculty of Chemistry; Belgrade Serbia
| | - Torsten Bohn
- Centre de Recherche Public - Gabriel Lippmann; Belvaux Luxembourg
| | | | | | - Joost Smit
- Institute for Risk Assessment Sciences; Utrecht University; Utrecht The Netherlands
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72
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Zhou Y, Wang JS, Yang XJ, Lin DH, Gao YF, Su YJ, Yang S, Zhang YJ, Zheng JJ. Peanut Allergy, Allergen Composition, and Methods of Reducing Allergenicity: A Review. INTERNATIONAL JOURNAL OF FOOD SCIENCE 2013; 2013:909140. [PMID: 26904614 PMCID: PMC4745518 DOI: 10.1155/2013/909140] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 06/23/2013] [Accepted: 06/24/2013] [Indexed: 12/22/2022]
Abstract
Peanut allergy affects 1-2% of the world's population. It is dangerous, and usually lifelong, and it greatly decreases the life quality of peanut-allergic individuals and their families. In a word, peanut allergy has become a major health concern worldwide. Thirteen peanut allergens are identified, and they are briefly introduced in this paper. Although there is no feasible solution to peanut allergy at present, many methods have shown great promise. This paper reviews methods of reducing peanut allergenicity, including physical methods (heat and pressure, PUV), chemical methods (tannic acid and magnetic beads), and biological methods (conventional breeding, irradiation breeding, genetic engineering, enzymatic treatment, and fermentation).
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Affiliation(s)
- Yang Zhou
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
| | - Jin-shui Wang
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, China
| | - Xiao-jia Yang
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
| | - Dan-hua Lin
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
| | - Yun-fang Gao
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
| | - Yin-jie Su
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
| | - Sen Yang
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, China
| | - Yan-jie Zhang
- College of Bioengineering, Henan University of Technology, Zhengzhou 450001, China
| | - Jing-jing Zheng
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450001, China
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73
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IgE cross-reactivity between the major peanut allergen Ara h 2 and the nonhomologous allergens Ara h 1 and Ara h 3. J Allergy Clin Immunol 2013; 132:118-24. [DOI: 10.1016/j.jaci.2013.01.022] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 12/14/2012] [Accepted: 01/17/2013] [Indexed: 11/20/2022]
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74
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Dam S, Thaysen-Andersen M, Stenkjær E, Lorentzen A, Roepstorff P, Packer NH, Stougaard J. Combined N-glycome and N-glycoproteome analysis of the Lotus japonicus seed globulin fraction shows conservation of protein structure and glycosylation in legumes. J Proteome Res 2013; 12:3383-92. [PMID: 23799247 DOI: 10.1021/pr400224s] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Legume food allergy, such as allergy toward peanuts and soybeans, is a health issue predicted to worsen as dietary advice recommends higher intake of legume-based foods. Lotus japonicus (Lotus) is an established legume plant model system for studies of symbiotic and pathogenic microbial interactions and, due to its well characterized genotype/phenotype and easily manipulated genome, may also be suitable for studies of legume food allergy. Here we present a comprehensive study of the Lotus N-glycoproteome. The global and site-specific N-glycan structures of Lotus seed globulins were analyzed using mass spectrometry-based glycomics and glycoproteomics techniques. In total, 19 N-glycan structures comprising high mannose (∼20%), pauci-mannosidic (∼40%), and complex forms (∼40%) were determined. The pauci-mannosidic and complex N-glycans contained high amounts of the typical plant determinants β-1,2-xylose and α-1,3-fucose. Two abundant Lotus seed N-glycoproteins were site-specifically profiled; a predicted lectin containing two fully occupied N-glycosylation sites carried predominantly pauci-mannosidic structures in different distributions. In contrast, Lotus convicilin storage protein 2 (LCP2) carried exclusively high mannose N-glycans similar to its homologue, Ara h 1, which is the major allergen in peanut. In silico investigation confirmed that peanut Ara h 1 and Lotus LCP2 are highly similar at the primary and higher protein structure levels. Hence, we suggest that Lotus has the potential to serve as a model system for studying the role of seed proteins and their glycosylation in food allergy.
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Affiliation(s)
- Svend Dam
- Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark
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75
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Hebling CM, McFarland MA, Callahan JH, Ross MM. Global proteomic screening of protein allergens and advanced glycation endproducts in thermally processed peanuts. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:5638-5648. [PMID: 23039025 DOI: 10.1021/jf303554t] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Peanuts (Arachis hypogaea) are the cause of one of the most prevalent food allergies worldwide. Thermal processing (e.g., roasting) of peanuts and peanut-containing foods results in complex chemical reactions that alter structural conformations of peanut proteins, preventing accurate detection of allergens by most immunochemical and targeted screening methodologies. To improve food allergen detection and support more accurate food labeling, traditional methods for peanut protein extraction were modified to include protein denaturants and solubilization agents. Qualitative characterization by SDS-PAGE and Western blot analyses of raw and variably roasted peanut extracts confirmed improvements in total protein recovery and provided evidence for the incorporation of Ara h 1, Ara h 3, and, to a lesser extent, Ara h 2 into high molecular weight protein complexes upon roasting. Relative quantification of allergens in peanut lysates was accomplished by label-free spectral feature (MS1) LC-MS/MS methodologies, by which peanut allergen peptides exhibiting a differential MS response in raw versus roasted peanuts were considered to be candidate targets of thermal modification. Identification of lysine-modified Maillard advanced glycation endproducts (AGE) by LC-MS/MS confirmed the formation of (carboxymethyl)lysine (CML), (carboxyethyl)lysine (CEL), and pyrraline (Pyr) protein modifications on Ara h 1 and Ara h 3 tryptic peptides in roasted peanut varieties. These results suggest that complex processed food matrices require initial analysis by an untargeted LC-MS/MS approach to determine optimum analytes for subsequent targeted allergen analyses.
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Affiliation(s)
- Christine M Hebling
- Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration , 5100 Paint Branch Parkway, College Park, Maryland 20740, United States
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76
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Walczyk NE, Smith PMC, Tovey E, Wright GC, Fleischfresser DB, Roberts TH. Analysis of crude protein and allergen abundance in peanuts (Arachis hypogaea cv. Walter) from three growing regions in Australia. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:3714-3725. [PMID: 23495786 DOI: 10.1021/jf305347r] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The effects of plant growth conditions on concentrations of proteins, including allergens, in peanut ( Arachis hypogaea L.) kernels are largely unknown. Peanuts (cv. Walter) were grown at five sites (Taabinga, Redvale, Childers, Bundaberg, and Kairi) covering three commercial growing regions in Queensland, Australia. Differences in temperature, rainfall, and solar radiation during the growing season were evaluated. Kernel yield varied from 2.3 t/ha (Kairi) to 3.9 t/ha (Childers), probably due to differences in solar radiation. Crude protein appeared to vary only between Kairi and Childers, whereas Ara h 1 and 2 concentrations were similar in all locations. 2D-DIGE revealed significant differences in spot volumes for only two minor protein spots from peanuts grown in the five locations. Western blotting using peanut-allergic serum revealed no qualitative differences in recognition of antigens. It was concluded that peanuts grown in different growing regions in Queensland, Australia, had similar protein compositions and therefore were unlikely to show differences in allergenicity.
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Affiliation(s)
- Nicole E Walczyk
- Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, Australia
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77
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Abstract
Food allergy has become a major public health concern in westernized countries, and allergic reactions to peanuts are particularly common and severe. Allergens are defined as antigens that elicit an IgE response, and most allergenic materials (e.g., pollens, danders, and foods) contain multiple allergenic proteins. This has led to the concept that there are "major" allergens and allergens of less importance. "Major allergens" have been defined as allergens that bind a large amount of IgE from the majority of patients and have biologic activity. However, the ability of an allergen to cross-link complexes of IgE and its high-affinity receptor FcεRI (IgE/FcεRI), which we have termed its allergic effector activity, does not correlate well with assays of IgE binding. To identify the proteins that are the most active allergens in peanuts, we and others have employed in vitro model assays of allergen-mediated cross-linking of IgE/FcεRI complexes and have demonstrated that the most potent allergens are not necessarily those that bind the most IgE. The importance of a specific allergen can be determined by measuring the allergic effector activity of that allergen following purification under non-denaturing conditions and by specifically removing the allergen from a complex allergenic extract either by chromatography or by specific immunodepletion. In our studies of peanut allergens, our laboratory has found that two related allergens, Ara h 2 and Ara h 6, together account for the majority of the effector activity in a crude peanut extract. Furthermore, murine studies demonstrated that Ara h 2 and Ara h 6 are not only the major elicitors of anaphylaxis in this system, but also can effectively desensitize peanut-allergic mice. As a result of these observations, we propose that the definition of a major allergen should be based on the potency of that allergen in assays of allergic effector activity and demonstration that removal of that allergen from an extract results in loss of potency. Using these criteria, Ara h 2 and Ara h 6 are the major peanut allergens.
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Affiliation(s)
- Yonghua Zhuang
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado School of Medicine, 12700 E. 19th Ave., Room 10C03, Aurora, CO 80045, USA
| | - Stephen C. Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado School of Medicine, 12700 E. 19th Ave., Room 10C03, Aurora, CO 80045, USA
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78
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Wang Y, Fu TJ, Howard A, Kothary MH, McHugh TH, Zhang Y. Crystal structure of peanut (Arachis hypogaea) allergen Ara h 5. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:1573-1578. [PMID: 23350842 DOI: 10.1021/jf303861p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Profilins from numerous species are known to be allergens, including food allergens, such as peanut ( Arachis hypogaea ) allergen Ara h 5, and pollen allergens, such as birch allergen Bet v 2. Patients with pollen allergy can also cross-react to peanut. Structural characterization of allergens will allow a better understanding of the allergenicity of food allergens and their cross-reactivities. The three-dimensional structures of most known food allergens remain to be elucidated. Here, we report the first crystallographic study of a food allergen in the profilin family. The structure of peanut allergen Ara h 5 was determined, and the resolution of the final refined structure was 1.1 Å. Structure alignment revealed that Ara h 5 is more similar to Bet v 2 than to Hev b 8, although sequence alignment suggested that Ara h 5 is more closely related to Hev b 8 than to Bet v 2, indicating that homology-model-based prediction of immunoglobulin E epitopes needs to be interpreted with caution.
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Affiliation(s)
- Yang Wang
- Department of Biological and Chemical Sciences, Illinois Institute of Technology, Chicago, Illinois 60616, United States
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79
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Roggen EL. Recent developments with B-cell epitope identification for predictive studies. J Immunotoxicol 2012; 3:137-49. [PMID: 18958694 DOI: 10.1080/15476910600845690] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
This review discusses currently available methods for predicting B-cell epitopes on proteins. The use of animals for assessing protein immunogenicity is addressed primarily to highlight the differences in B- and T-cell epitope recognition between species. These differences have to be considered when interpreting potential B-cell epitopes identified by the methods addressed here. "In vitro alternatives" focuses on the strengths and limitations of peptide-based technologies. Three types of computer-based methods for identifying potential B-cell epitopes are discussed: (i) methods applying physico-chemical and structural propensity scales for predicting linear epitopes from the primary structure of a protein, (ii) comparative methods basing prediction upon amino acid sequence and structural similarities between antigenically known and unknown proteins, and (iii) a method combining structural features with a B-cell epitope motif database for predicting linear and conformational antigenic determinants. With respect to human safety, the usefulness of antibody-based tests is limited to comparative studies between an antigenically known protein and variants thereof. Similarly, computer-based methods using data mining can address similarities in B-cell epitope profiles between related proteins, if a proper cut off can be defined for the minimal amino acid sequence similarity required for obtaining an acceptable accuracy. Among the physico-chemical and structural scales, scales identifying in a protein hairpin and non-specific turns seem useful for predicting epitopes with a continuous primary binding site. When conformational epitopes have to be identified as well, a novel computer-based tool seems to be the most promising alternative to X-ray crystallography. However, both methods remain to be extensively evaluated and validated. Thus, promising tools for B-cell epitope identification have been developed. But, no validated method for B-cell epitope identification on antigenically unknown proteins is available yet.
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80
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Menna T, Cassese G, Modugno F, Chersi A, Buono C, Ruffilli A. Characterization of a dodecapeptide containing a dominant epitope of Par j 1 and Par o 1, the major allergens of P. judaica and P. officinalis pollen. Allergy 2012. [DOI: 10.1111/j.1398-9995.1999.tb05151.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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81
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Bøgh KL, Nielsen H, Madsen CB, Mills ENC, Rigby N, Eiwegger T, Szépfalusi Z, Roggen EL. IgE epitopes of intact and digested Ara h 1: a comparative study in humans and rats. Mol Immunol 2012; 51:337-46. [PMID: 22555070 DOI: 10.1016/j.molimm.2012.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 04/02/2012] [Accepted: 04/08/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Allergen epitope characterization provides valuable information useful for the understanding of proteins as food allergens. It is believed that IgE epitopes in general are conformational, nevertheless, for food allergens known to sensitize through the gastrointestinal tract linear epitopes have been suggested to be of great importance. OBJECTIVE The aim of this study was to identify IgE specific epitopes of intact and digested Ara h 1, and to compare epitope patterns between humans and rats. METHODS Sera from five peanut allergic patients and five Brown Norway rats were used to identify intact and digested Ara h 1-specific IgE epitopes by competitive immunoscreening of a phage-displayed random hepta-mer peptide library using polyclonal IgE from the individual sera. The resulting peptide sequences were mapped on the surface of a three-dimensional structure of the Ara h 1 molecule to mimic epitopes using a computer-based algorithm. RESULTS Patients as well as rats were shown to have individual IgE epitope patterns. All epitope mimics were conformational and found to cluster into three different areas of the Ara h 1 molecule. Five epitope motifs were identified by patient IgE, which by far accounted for most of the eluted peptide sequences. Epitope patterns were rather similar for both intact and digested Ara h 1 as well as for humans and rats. CONCLUSIONS Individual patient specific epitope patterns have been identified for the major allergen Ara h 1. IgE binding epitopes have been suggested as biomarkers for persistency and severity of food allergy, wherefore recognition of particular epitope patterns or motifs could be a valuable tool for prevention, diagnosis, and treatment of food allergy.
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Affiliation(s)
- K L Bøgh
- National Food Institute, Division of Toxicology and Risk Assessment, Technical University of Denmark, Mørkhøj Bygade 19, Søborg, Denmark.
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82
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Lin J, Bruni FM, Fu Z, Maloney J, Bardina L, Boner AL, Gimenez G, Sampson HA. A bioinformatics approach to identify patients with symptomatic peanut allergy using peptide microarray immunoassay. J Allergy Clin Immunol 2012; 129:1321-1328.e5. [PMID: 22444503 DOI: 10.1016/j.jaci.2012.02.012] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 01/09/2012] [Accepted: 02/09/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Peanut allergy is relatively common, typically permanent, and often severe. Double-blind, placebo-controlled food challenge is considered the gold standard for the diagnosis of food allergy-related disorders. However, the complexity and potential of double-blind, placebo-controlled food challenge to cause life-threatening allergic reactions affects its clinical application. A laboratory test that could accurately diagnose symptomatic peanut allergy would greatly facilitate clinical practice. OBJECTIVE We sought to develop an allergy diagnostic method that could correctly predict symptomatic peanut allergy by using peptide microarray immunoassays and bioinformatic methods. METHODS Microarray immunoassays were performed by using the sera from 62 patients (31 with symptomatic peanut allergy and 31 who had outgrown their peanut allergy or were sensitized but were clinically tolerant to peanut). Specific IgE and IgG(4) binding to 419 overlapping peptides (15 mers, 3 offset) covering the amino acid sequences of Ara h 1, Ara h 2, and Ara h 3 were measured by using a peptide microarray immunoassay. Bioinformatic methods were applied for data analysis. RESULTS Individuals with peanut allergy showed significantly greater IgE binding and broader epitope diversity than did peanut-tolerant individuals. No significant difference in IgG(4) binding was found between groups. By using machine learning methods, 4 peptide biomarkers were identified and prediction models that can predict the outcome of double-blind, placebo-controlled food challenges with high accuracy were developed by using a combination of the biomarkers. CONCLUSIONS In this study, we developed a novel diagnostic approach that can predict peanut allergy with high accuracy by combining the results of a peptide microarray immunoassay and bioinformatic methods. Further studies are needed to validate the efficacy of this assay in clinical practice.
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Affiliation(s)
- Jing Lin
- Pediatric Allergy and Immunology, Mount Sinai School of Medicine, New York, NY 10029, USA.
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83
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Bøgh KL, Barkholt V, Rigby NM, Mills ENC, Madsen CB. Digested Ara h 1 loses sensitizing capacity when separated into fractions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:2934-2942. [PMID: 22364549 DOI: 10.1021/jf2052306] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The major peanut allergen Ara h 1 is an easily digestible protein under physiological conditions. The present study revealed that pepsin digestion products of Ara h 1 retained the sensitizing potential in a Brown Norway rat model, while this sensitizing capacity was lost by separating the digest into fractions by gel permeation chromatography. Protein chemical analysis showed that the peptide composition as well as the aggregation profiles of the fractions of Ara h 1 digest differed from that of the whole pool. These results indicate that the sensitizing capacity of digested Ara h 1 is a consequence of the peptides being in an aggregated state resembling the intact molecule or that most peptides of the digests need to be present in the same solution, having a synergistic or adjuvant effect and thereby augmenting the immune response against other peptides.
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Affiliation(s)
- Katrine L Bøgh
- National Food Institute, Division of Toxicology and Risk Assessment, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
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84
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Maleki SJ, Teuber SS, Cheng H, Chen D, Comstock SS, Ruan S, Schein CH. Computationally predicted IgE epitopes of walnut allergens contribute to cross-reactivity with peanuts. Allergy 2011; 66:1522-9. [PMID: 21883278 DOI: 10.1111/j.1398-9995.2011.02692.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Cross-reactivity between peanuts and tree nuts implies that similar immunoglobulin E (IgE) epitopes are present in their proteins. OBJECTIVE To determine whether walnut sequences similar to known peanut IgE-binding sequences, according to the property distance (PD) scale implemented in the Structural Database of Allergenic Proteins, react with IgE from sera of patients with allergy to walnut and/or peanut. METHODS Patient sera were characterized by western blotting for IgE binding to nut protein extracts and to peptides from walnut and peanut allergens, similar to known peanut epitopes as defined by low PD values, synthesized on membranes. Competitive enzyme-linked immunosorbent assay (ELISA) was used to show that peanut and predicted walnut epitope sequences compete with purified Ara h 2 for binding to IgE in serum from a cross-reactive patient. RESULTS Sequences from the vicilin walnut allergen Jug r 2, which had low PD values to epitopes of the peanut allergen Ara h 2, a 2S albumin, bound to IgE in sera from five patients who reacted to either walnut or peanut or both. A walnut epitope recognized by sera from six patients mapped to a surface-exposed region on a model of the N-terminal pro-region of Jug r 2. This predicted walnut epitope competed for IgE binding to Ara h 2 in serum as well as the known IgE epitope from Ara h 2. CONCLUSIONS Sequences with low PD value (< 8.5) to known IgE epitopes could contribute to cross-reactivity between allergens. This further validates the PD scoring method for predicting cross-reactive epitopes in allergens.
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Affiliation(s)
- S J Maleki
- U.S. Department of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA 70124, USA.
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85
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86
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Chruszcz M, Maleki SJ, Majorek KA, Demas M, Bublin M, Solberg R, Hurlburt BK, Ruan S, Mattisohn CP, Breiteneder H, Minor W. Structural and immunologic characterization of Ara h 1, a major peanut allergen. J Biol Chem 2011; 286:39318-27. [PMID: 21917921 PMCID: PMC3234756 DOI: 10.1074/jbc.m111.270132] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 09/10/2011] [Indexed: 11/06/2022] Open
Abstract
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.
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Affiliation(s)
- Maksymilian Chruszcz
- From the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908
| | - Soheila J. Maleki
- the Agriculture Research Service, Southern Regional Research Center, United States Department of Agriculture, New Orleans, Louisiana 70124, and
| | - Karolina A. Majorek
- From the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908
| | - Matthew Demas
- From the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908
| | - Merima Bublin
- the Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, 1090 Austria
| | - Robert Solberg
- From the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908
| | - Barry K. Hurlburt
- the Agriculture Research Service, Southern Regional Research Center, United States Department of Agriculture, New Orleans, Louisiana 70124, and
| | - Sanbao Ruan
- the Agriculture Research Service, Southern Regional Research Center, United States Department of Agriculture, New Orleans, Louisiana 70124, and
| | - Christopher P. Mattisohn
- the Agriculture Research Service, Southern Regional Research Center, United States Department of Agriculture, New Orleans, Louisiana 70124, and
| | - Heimo Breiteneder
- the Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology & Immunology, Medical University of Vienna, Waehringer Guertel 18-20, Vienna, 1090 Austria
| | - Wladek Minor
- From the Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908
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87
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Rosenfeld L, Shreffler W, Bardina L, Niggemann B, Wahn U, Sampson HA, Beyer K. 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. Int Arch Allergy Immunol 2011; 157:238-45. [PMID: 22042002 DOI: 10.1159/000327841] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 03/25/2011] [Indexed: 12/30/2022] Open
Abstract
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.
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Affiliation(s)
- Leonard Rosenfeld
- Department of Pediatric Pneumology and Immunology, University Children's Hospital Charité, Berlin, Germany
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88
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Cabanos C, Urabe H, Tandang-Silvas MR, Utsumi S, Mikami B, Maruyama N. Crystal structure of the major peanut allergen Ara h 1. Mol Immunol 2011; 49:115-23. [DOI: 10.1016/j.molimm.2011.08.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 07/30/2011] [Accepted: 08/06/2011] [Indexed: 11/27/2022]
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Prediction of B-cell linear epitopes with a combination of support vector machine classification and amino acid propensity identification. J Biomed Biotechnol 2011; 2011:432830. [PMID: 21876642 PMCID: PMC3163029 DOI: 10.1155/2011/432830] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 06/28/2011] [Indexed: 12/29/2022] Open
Abstract
Epitopes are antigenic determinants that are useful because they induce B-cell antibody production and stimulate T-cell activation. Bioinformatics can enable rapid, efficient prediction of potential epitopes. Here, we designed a novel B-cell linear epitope prediction system called LEPS, Linear Epitope Prediction by Propensities and Support Vector Machine, that combined physico-chemical propensity identification and support vector machine (SVM) classification. We tested the LEPS on four datasets: AntiJen, HIV, a newly generated PC, and AHP, a combination of these three datasets. Peptides with globally or locally high physicochemical propensities were first identified as primitive linear epitope (LE) candidates. Then, candidates were classified with the SVM based on the unique features of amino acid segments. This reduced the number of predicted epitopes and enhanced the positive prediction value (PPV). Compared to four other well-known LE prediction systems, the LEPS achieved the highest accuracy (72.52%), specificity (84.22%), PPV (32.07%), and Matthews' correlation coefficient (10.36%).
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90
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Glesner J, Wünschmann S, Li M, Gustchina A, Wlodawer A, Himly M, Chapman MD, Pomés A. Mechanisms of allergen-antibody interaction of cockroach allergen Bla g 2 with monoclonal antibodies that inhibit IgE antibody binding. PLoS One 2011; 6:e22223. [PMID: 21789239 PMCID: PMC3137622 DOI: 10.1371/journal.pone.0022223] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Accepted: 06/20/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Cockroach allergy is strongly associated with asthma, and involves the production of IgE antibodies against inhaled allergens. Reports of conformational epitopes on inhaled allergens are limited. The conformational epitopes for two specific monoclonal antibodies (mAb) that interfere with IgE antibody binding were identified by X-ray crystallography on opposite sites of the quasi-symmetrical cockroach allergen Bla g 2. METHODOLOGY/PRINCIPAL FINDINGS Mutational analysis of selected residues in both epitopes was performed based on the X-ray crystal structures of the allergen with mAb Fab/Fab' fragments, to investigate the structural basis of allergen-antibody interactions. The epitopes of Bla g 2 for the mAb 7C11 or 4C3 were mutated, and the mutants were analyzed by SDS-PAGE, circular dichroism, and/or mass spectrometry. Mutants were tested for mAb and IgE antibody binding by ELISA and fluorescent multiplex array. Single or multiple mutations of five residues from both epitopes resulted in almost complete loss of mAb binding, without affecting the overall folding of the allergen. Preventing glycosylation by mutation N268Q reduced IgE binding, indicating a role of carbohydrates in the interaction. Cation-π interactions, as well as electrostatic and hydrophobic interactions, were important for mAb and IgE antibody binding. Quantitative differences in the effects of mutations on IgE antibody binding were observed, suggesting heterogeneity in epitope recognition among cockroach allergic patients. CONCLUSIONS/SIGNIFICANCE Analysis by site-directed mutagenesis of epitopes identified by X-ray crystallography revealed an overlap between monoclonal and IgE antibody binding sites and provided insight into the B cell repertoire to Bla g 2 and the mechanisms of allergen-antibody recognition, including involvement of carbohydrates.
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Affiliation(s)
- Jill Glesner
- INDOOR Biotechnologies, Inc., Charlottesville, Virginia, United States of America
| | - Sabina Wünschmann
- INDOOR Biotechnologies, Inc., Charlottesville, Virginia, United States of America
| | - Mi Li
- Basic Research Program, SAIC-Frederick, Frederick, Maryland, United States of America
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - Alla Gustchina
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - Alexander Wlodawer
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - Martin Himly
- Division of Allergy and Immunology, Department of Molecular Biology, University of Salzburg, Salzburg, Austria
| | - Martin D. Chapman
- INDOOR Biotechnologies, Inc., Charlottesville, Virginia, United States of America
| | - Anna Pomés
- INDOOR Biotechnologies, Inc., Charlottesville, Virginia, United States of America
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91
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Jiang S, Wang S, Sun Y, Zhou Z, Wang G. Molecular characterization of major allergens Ara h 1, 2, 3 in peanut seed. PLANT CELL REPORTS 2011; 30:1135-1143. [PMID: 21305299 DOI: 10.1007/s00299-011-1022-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 01/12/2011] [Accepted: 01/21/2011] [Indexed: 05/30/2023]
Abstract
Peanut is among the most commonly used dietary seeds, but peanut allergens, especially Ara h 1 (Arachis hypogaea allergy 1), 2 and 3, can cause severe IgE-mediated reactions. In this study, the molecular characterization and expression pattern of three allergens in peanut LUHUA 8, the representative of the cultivated lines in China, are reported. In situ hybridization and real time PCR analysis revealed high expression levels and different tissue expression patterns of the three allergens, which might be connected with many aspects, such as the strong conservation of intron phase of the allergen genes, the low energy of the mRNA's regions, and the complicated post-translational modifications. Furthermore, the different sequences between the cloned allergens and the reported sequences previously involved the charged amino acids especially in IgE epitopes, which might alter specific physicochemical and physiological properties, and thus influence the immunity of the allergens. The identification of the specific features of the allergen genes would be of considerable importance to the basic understanding of the specific characteristics of peanut seed allergens.
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Affiliation(s)
- Shengjuan Jiang
- College of Life Science, Anhui Science and Technology University, Anhui Fengyang 233100, China.
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92
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Hurlburt BK, Schmitt D, Isleib TG, Cheng H, Garvey C, Koenig RL, Maleki SJ. Production of pure protein and antibodies and development of immunoassays to detect Ara h 3 levels in peanut varieties. Int J Food Sci Technol 2011. [DOI: 10.1111/j.1365-2621.2011.02645.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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93
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Knoll JE, Ramos ML, Zeng Y, Holbrook CC, Chow M, Chen S, Maleki S, Bhattacharya A, Ozias-Akins P. TILLING for allergen reduction and improvement of quality traits in peanut (Arachis hypogaea L.). BMC PLANT BIOLOGY 2011; 11:81. [PMID: 21569438 PMCID: PMC3113929 DOI: 10.1186/1471-2229-11-81] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2011] [Accepted: 05/12/2011] [Indexed: 05/20/2023]
Abstract
BACKGROUND Allergic reactions to peanuts (Arachis hypogaea L.) can cause severe symptoms and in some cases can be fatal, but avoidance is difficult due to the prevalence of peanut-derived products in processed foods. One strategy of reducing the allergenicity of peanuts is to alter or eliminate the allergenic proteins through mutagenesis. Other seed quality traits could be improved by altering biosynthetic enzyme activities. Targeting Induced Local Lesions in Genomes (TILLING), a reverse-genetics approach, was used to identify mutations affecting seed traits in peanut. RESULTS Two similar copies of a major allergen gene, Ara h 1, have been identified in tetraploid peanut, one in each subgenome. The same situation has been shown for major allergen Ara h 2. Due to the challenge of discriminating between homeologous genes in allotetraploid peanut, nested PCR was employed, in which both gene copies were amplified using unlabeled primers. This was followed by a second PCR using gene-specific labeled primers, heteroduplex formation, CEL1 nuclease digestion, and electrophoretic detection of labeled fragments. Using ethyl methanesulfonate (EMS) as a mutagen, a mutation frequency of 1 SNP/967 kb (3,420 M2 individuals screened) was observed. The most significant mutations identified were a disrupted start codon in Ara h 2.02 and a premature stop codon in Ara h 1.02. Homozygous individuals were recovered in succeeding generations for each of these mutations, and elimination of Ara h 2.02 protein was confirmed. Several Ara h 1 protein isoforms were eliminated or reduced according to 2D gel analyses. TILLING also was used to identify mutations in fatty acid desaturase AhFAD2 (also present in two copies), a gene which controls the ratio of oleic to linoleic acid in the seed. A frameshift mutation was identified, resulting in truncation and inactivation of AhFAD2B protein. A mutation in AhFAD2A was predicted to restore function to the normally inactive enzyme. CONCLUSIONS This work represents the first steps toward the goal of creating a peanut cultivar with reduced allergenicity. TILLING in peanut can be extended to virtually any gene, and could be used to modify other traits such as nutritional properties of the seed, as shown in this study.
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Affiliation(s)
- Joseph E Knoll
- Department of Horticulture/NESPAL, University of Georgia-Tifton Campus, Tifton, GA 31793, USA
- USDA-ARS Crop Genetics and Breeding Research Unit, Tifton, GA 31793, USA
| | - M Laura Ramos
- Department of Horticulture/NESPAL, University of Georgia-Tifton Campus, Tifton, GA 31793, USA
| | - Yajuan Zeng
- Department of Horticulture/NESPAL, University of Georgia-Tifton Campus, Tifton, GA 31793, USA
| | - C Corley Holbrook
- USDA-ARS Crop Genetics and Breeding Research Unit, Tifton, GA 31793, USA
| | - Marjorie Chow
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Sixue Chen
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL 32611, USA
| | - Soheila Maleki
- USDA-ARS Southern Regional Research Center, New Orleans, LA 70124, USA
| | - Anjanabha Bhattacharya
- Department of Horticulture/NESPAL, University of Georgia-Tifton Campus, Tifton, GA 31793, USA
| | - Peggy Ozias-Akins
- Department of Horticulture/NESPAL, University of Georgia-Tifton Campus, Tifton, GA 31793, USA
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Kim KBWR, Lee SY, Song EJ, Kim KE, Ahn DH. Effect of heat and autoclave on allergenicity of porcine serum albumin. Food Sci Biotechnol 2011. [DOI: 10.1007/s10068-011-0063-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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95
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Rougé P, Brunet E, Borges JP, Jauneau A, Saggio B, Bourrier T, Rancé F, Didier A, Barre A. Les protéines à motif cupine : allergènes majeurs des graines. REVUE FRANCAISE D ALLERGOLOGIE 2011. [DOI: 10.1016/j.reval.2010.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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96
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Li M, Gustchina A, Glesner J, Wünschmann S, Vailes LD, Chapman MD, Pomés A, Wlodawer A. Carbohydrates contribute to the interactions between cockroach allergen Bla g 2 and a monoclonal antibody. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 186:333-40. [PMID: 21123808 PMCID: PMC3099132 DOI: 10.4049/jimmunol.1002318] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The crystal structure of a murine mAb, 4C3, that binds to the C-terminal lobe of the cockroach allergen Bla g 2 has been solved at 1.8 Å resolution. Binding of 4C3 involves different types of molecular interactions with its epitope compared with those with the mAb 7C11, which binds to the N-terminal lobe of Bla g 2. We found that the 4C3 surface epitope on Bla g 2 includes a carbohydrate moiety attached to Asn(268) and that a large number of Ag-Ab contacts are mediated by water molecules and ions, most likely zinc. Ab binding experiments conducted with an enzymatically deglycosylated Bla g 2 and a N268Q mutant showed that the carbohydrate contributes, without being essential, to the Bla g 2-4C3 mAb interaction. Inhibition of IgE Ab binding by the mAb 4C3 shows a correlation of the structurally defined epitope with reactivity with human IgE. Site-directed mutagenesis of the 4C3 mAb epitope confirmed that the amino acids Lys(251), Glu(233), and Ile(199) are important for the recognition of Bla g 2 by the 4C3 mAb. The results show the relevance of x-ray crystallographic studies of allergen-Ab complexes to identify conformational epitopes that define the antigenic surface of Bla g 2.
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Affiliation(s)
- Mi Li
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA
- Basic Research Program, SAIC-Frederick, Frederick, MD 21702, USA
| | - Alla Gustchina
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA
| | - Jill Glesner
- INDOOR Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA 22903, USA
| | - Sabina Wünschmann
- INDOOR Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA 22903, USA
| | - Lisa D. Vailes
- INDOOR Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA 22903, USA
| | - Martin D. Chapman
- INDOOR Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA 22903, USA
| | - Anna Pomés
- INDOOR Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA 22903, USA
| | - Alexander Wlodawer
- Macromolecular Crystallography Laboratory, National Cancer Institute, Frederick, MD 21702, USA
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Prickett SR, Voskamp AL, Dacumos-Hill A, Symons K, Rolland JM, O'Hehir RE. Ara h 2 peptides containing dominant CD4+ T-cell epitopes: candidates for a peanut allergy therapeutic. J Allergy Clin Immunol 2010; 127:608-15.e1-5. [PMID: 21093025 DOI: 10.1016/j.jaci.2010.09.027] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 08/26/2010] [Accepted: 09/23/2010] [Indexed: 11/30/2022]
Abstract
BACKGROUND Peanut allergy is a life-threatening condition; there is currently no cure. Although whole allergen extracts are used for specific immunotherapy for many allergies, they can cause severe reactions, and even fatalities, in peanut allergy. OBJECTIVE This study aimed to identify short, T-cell epitope-based peptides that target allergen-specific CD4(+) T cells but do not bind IgE as candidates for safe peanut-specific immunotherapy. METHODS Multiple CD4(+) T-cell lines specific for the major peanut allergen Ara h 2 were generated from PBMCs of 16 HLA-diverse subjects with peanut allergy by using 5,6-carboxyfluorescein diacetate succinimidylester-based methodology. Proliferation and ELISPOT assays were used to identify dominant epitopes recognized by T-cell lines and to confirm recognition by peripheral blood T cells of epitope-based peptides modified for therapeutic production. HLA restriction of core epitope recognition was investigated by using anti-HLA blocking antibodies and HLA genotyping. Serum-IgE peptide-binding was assessed by dot-blot. RESULTS Five dominant CD4(+) T-cell epitopes were identified in Ara h 2. In combination, these were presented by HLA-DR, HLA-DP, and HLA-DQ molecules and recognized by T cells from all 16 subjects. Three short peptide variants containing these T-cell epitopes were designed with cysteine-to-serine substitutions to facilitate stability and therapeutic production. Variant peptides showed HLA-binding degeneracy, did not bind peanut-specific serum IgE, and could directly target T(H)2-type T cells in peripheral blood of subjects with allergy. CONCLUSION Short CD4(+) T-cell epitope-based Ara h 2 peptides were identified as novel candidates for a T-cell-targeted peanut-specific immunotherapy for an HLA-diverse population.
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Affiliation(s)
- Sara R Prickett
- Department of Immunology, Monash University, Melbourne, Australia
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Verma AK, Misra A, Subash S, Das M, Dwivedi PD. Computational allergenicity prediction of transgenic proteins expressed in genetically modified crops. Immunopharmacol Immunotoxicol 2010; 33:410-22. [PMID: 20964517 DOI: 10.3109/08923973.2010.523704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Development of genetically modified (GM) crops is on increase to improve food quality, increase harvest yields, and reduce the dependency on chemical pesticides. Before their release in marketplace, they should be scrutinized for their safety. Several guidelines of different regulatory agencies like ILSI, WHO Codex, OECD, and so on for allergenicity evaluation of transgenics are available and sequence homology analysis is the first test to determine the allergenic potential of inserted proteins. Therefore, to test and validate, 312 allergenic, 100 non-allergenic, and 48 inserted proteins were assessed for sequence similarity using 8-mer, 80-mer, and full FASTA search. On performing sequence homology studies, ~94% the allergenic proteins gave exact matches for 8-mer and 80-mer homology. However, 20 allergenic proteins showed non-allergenic behavior. Out of 100 non-allergenic proteins, seven qualified as allergens. None of the inserted proteins demonstrated allergenic behavior. In order to improve the predictability, proteins showing anomalous behavior were tested by Algpred and ADFS separately. Use of Algpred and ADFS softwares reduced the tendency of false prediction to a great extent (74-78%). In conclusion, routine sequence homology needs to be coupled with some other bioinformatic method like ADFS/Algpred to reduce false allergenicity prediction of novel proteins.
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Affiliation(s)
- Alok Kumar Verma
- Food Toxicology Division, Indian Institute of Toxicology Research, Council of Scientific and Industrial Research, Lucknow, Uttar Pradesh, India
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Greater epitope recognition of shrimp allergens by children than by adults suggests that shrimp sensitization decreases with age. J Allergy Clin Immunol 2010; 125:1286-1293.e3. [PMID: 20471069 DOI: 10.1016/j.jaci.2010.03.010] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 03/12/2010] [Accepted: 03/16/2010] [Indexed: 11/20/2022]
Abstract
BACKGROUND Shellfish allergy is a long-lasting disorder typically affecting adults. Despite its high prevalence, there is limited information about allergenic shrimp proteins and the epitopes implicated in such allergic reactions. OBJECTIVE We sought to identify the IgE-binding epitopes of the 4 shrimp allergens and to characterize epitope recognition profiles of children and adults with shrimp allergy. METHODS Fifty-three subjects, 34 children and 19 adults, were selected with immediate allergic reactions to shrimp, increased shrimp-specific serum IgE levels, and positive immunoblot binding to shrimp. Study subjects and 7 nonatopic control subjects were tested by means of peptide microarray for IgE binding with synthetic overlapping peptides spanning the sequences of Litopenaeus vannamei shrimp tropomyosin, arginine kinase (AK), myosin light chain (MLC), and sarcoplasmic calcium-binding protein (SCP). The Wilcoxon test was used to determine significant differences in z scores between patients and control subjects. RESULTS The median shrimp IgE level was 4-fold higher in children than in adults (47 vs 12.5 kU(A)/L). The frequency of allergen recognition was higher in children (tropomyosin, 81% [94% for children and 61% for adults]; MLC, 57% [70% for children and 31% for adults]; AK, 51% [67% for children and 21% for adults]; and SCP, 45% [59% for children and 21% for adults]), whereas control subjects showed negligible binding. Seven IgE-binding regions were identified in tropomyosin by means of peptide microarray, confirming previously identified shrimp epitopes. In addition, 3 new epitopes were identified in tropomyosin (epitopes 1, 3, and 5b-c), 5 epitopes were identified in MLC, 3 epitopes were identified in SCP, and 7 epitopes were identified in AK. Interestingly, frequency of individual epitope recognition, as well as intensity of IgE binding, was significantly greater in children than in adults for all 4 proteins. CONCLUSIONS Children with shrimp allergy have greater shrimp-specific IgE antibody levels and show more intense binding to shrimp peptides and greater epitope diversity than adults.
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Chiang WC, Pons L, Kidon MI, Liew WK, Goh A, Wesley Burks A. Serological and clinical characteristics of children with peanut sensitization in an Asian community. Pediatr Allergy Immunol 2010; 21:e429-38. [PMID: 19702675 DOI: 10.1111/j.1399-3038.2009.00930.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In the past two decades, peanut allergy prevalence has increased in the West but has been perceived as having remained low in Asia. To review the clinical presentation of Asian children with peanut hypersensitivity and measure their IgE responses to major peanut allergens. We enrolled 31 children presenting with various allergies and a positive skin prick test to peanut from the Children's hospital outpatient allergy clinic in Singapore. A detailed questionnaire was completed by parents. The children's serum IgE specific to native Ara h 1, native Ara h 2, and recombinant Ara h 3 were detected using ELISA. Of the 31 patients, 19 had previously documented reactions to peanuts, while 12 had no previous clinical reaction. Most, 89.5% (17/19) of first reactions featured skin changes (urticaria, erythema, angioedema), but only 36.8% (7/19) involved skin symptoms alone. Respiratory symptoms and GI symptoms occurred in 42.1% and 26.3% of patients respectively and did not occur as the sole manifestation of reaction. The most common GI manifestation was emesis, present in 26.3% (5/19) of subjects. Two children experienced impaired consciousness with systemic, anaphylactic events. Although most sought treatment for their first peanut reaction only one patient received epinephrine. Half of our patients reported a subsequent accidental ingestion after the diagnosis of peanut allergy, with a median time from diagnosis to first accidental ingestion of 4 months and a reported increased severity of reaction in approximately half of the repeat exposures. Eighty-seven percent of children had specific IgE directed against at least one of the major peanut allergens. Among all patients, 87.1% had IgE specific to both Ara h 1 and Ara h 2 and 54.8% to rAra h 3. Asian children with peanut sensitization have clinically similar presentations and respond to the same major allergenic proteins as their Western counterparts. The perceived differences between the populations in this context do not stem from divergent clinical or immunological responses.
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Affiliation(s)
- Wen Chin Chiang
- Department of Paediatric Medicine, Kandang Kerbau Children's Hospital, Singapore.
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