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Pomés A, Smith SA, Chruszcz M, Mueller GA, Brackett NF, Chapman MD. Precision engineering for localization, validation, and modification of allergenic epitopes. J Allergy Clin Immunol 2024; 153:560-571. [PMID: 38181840 PMCID: PMC10939758 DOI: 10.1016/j.jaci.2023.12.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/20/2023] [Accepted: 12/29/2023] [Indexed: 01/07/2024]
Abstract
The allergen-IgE interaction is essential for the genesis of allergic responses, yet investigation of the molecular basis of these interactions is in its infancy. Precision engineering has unveiled the molecular features of allergen-antibody interactions at the atomic level. High-resolution technologies, including x-ray crystallography, nuclear magnetic resonance spectroscopy, and cryo-electron microscopy, determine allergen-antibody structures. X-ray crystallography of an allergen-antibody complex localizes in detail amino acid residues and interactions that define the epitope-paratope interface. Multiple structures involving murine IgG mAbs have recently been resolved. The number of amino acids forming the epitope broadly correlates with the epitope area. The production of human IgE mAbs from B cells of allergic subjects is an exciting recent development that has for the first time enabled an actual IgE epitope to be defined. The biologic activity of defined IgE epitopes can be validated in vivo in animal models or by measuring mediator release from engineered basophilic cell lines. Finally, gene-editing approaches using the Clustered Regularly Interspaced Short Palindromic Repeats technology to either remove allergen genes or make targeted epitope engineering at the source are on the horizon. This review presents an overview of the identification and validation of allergenic epitopes by precision engineering.
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Affiliation(s)
| | - Scott A Smith
- Vanderbilt University Medical Center, Nashville, Tenn
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2
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Canon N, Schein CH, Braun W, Negi SS, Chen X, Kulis MD, Kim EH, Pathy V, Pozzoli M, Liu W, Dreskin SC. Alanine Scanning of the Unstructured Region of Ara h 2 and of a Related Mimotope Reveals Critical Amino Acids for IgE Binding. Mol Nutr Food Res 2023; 67:e2300134. [PMID: 37706599 PMCID: PMC10840829 DOI: 10.1002/mnfr.202300134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 07/26/2023] [Indexed: 09/15/2023]
Abstract
SCOPE The unstructured region of Ara h 2, referred to as epitope 3, contains a repeated motif, DYPSh (h = hydroxyproline) that is important for IgE binding. METHODS AND RESULTS IgE binding assays to 20mer and shorter peptides of epitope 3, defines a 16mer core sequence containing one copy of the DPYSh motif, DEDSYERDPYShSQDP. This study performs alanine scanning of this and a related 12mer mimotope, LLDPYAhRAWTK. IgE binding, using a pool of 10 sera and with individual sera, is greatly reduced when alanine is substituted for aspartate at position 8 (D8; p < 0.01), tyrosine at position 10 (Y10; p < 0.01), and hydroxyproline at position 12 (h12; p < 0.001). IgE binding to alanine-substituted peptides of a mimotope containing the DPY_h motif confirm the critical importance of Y (p < 0.01) and h (p < 0.01), but not D. Molecular modeling of the core and mimotope suggests an h-dependent conformational basis for the recognition of these sequences by polyclonal IgE. CONCLUSIONS IgE from pooled sera and individual sera differentially bound amino acids throughout the sequences of Epitope 3 and its mimotope, with Y10 and h12 being most important for all sera. These results are highly significant for designing hypoallergenic forms of Ara h 2.
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Affiliation(s)
- Nicole Canon
- Division of Allergy and Immunology, Kelsey-Seybold Clinic, Houston, TX
| | - Catherine H. Schein
- Institute for Human Infections and Immunity (IHII), The University of Texas Medical Branch, Galveston, TX
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX
| | - Werner Braun
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX
| | - Surendra S. Negi
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX
| | - Xueni Chen
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO
| | - Michael D. Kulis
- Division of Pediatric Allergy and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Edwin H. Kim
- Division of Pediatric Allergy and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Vidya Pathy
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO
| | - Marina Pozzoli
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO
| | - Weimin Liu
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO
| | - Stephen C. Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO
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Smith BRE, Reid Black K, Bermingham M, Agah S, Glesner J, Versteeg SA, van Ree R, Pena-Amelunxen G, Aglas L, Smith SA, Pomés A, Chapman MD. Unique allergen-specific human IgE monoclonal antibodies derived from patients with allergic disease. FRONTIERS IN ALLERGY 2023; 4:1270326. [PMID: 37901762 PMCID: PMC10602672 DOI: 10.3389/falgy.2023.1270326] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
Introduction Allergic reactions are mediated by human IgE antibodies that bind to and cross-link allergen molecules. The sites on allergens that are recognized by IgE antibodies have been difficult to investigate because of the paucity of IgE antibodies in a human serum. Here, we report the production of unique human IgE monoclonal antibodies to major inhaled allergens and food allergens that can be produced at scale in perpetuity. Materials and methods The IgE antibodies were derived from peripheral blood mononuclear cells of symptomatic allergic patients, mostly children aged 3-18 years, using hybridoma fusion technology. Total IgE and allergen-specific IgE was measured by ImmunoCAP. Their specificity was confirmed through ELISA and immunoblotting. Allergenic potency measurements were determined by ImmunoCAP inhibition. Biological activity was determined in vitro by comparing β-hexosaminidase release from a humanized rat basophilic cell line. Results Human IgE monoclonal antibodies (n = 33) were derived from 17 allergic patients with symptoms of allergic rhinitis, asthma, atopic dermatitis, food allergy, eosinophilic esophagitis, or red meat allergy. The antibodies were specific for five inhaled allergens, nine food allergens, and alpha-gal and had high levels of IgE (53,450-1,702,500 kU/L) with ratios of specific IgE to total IgE ranging from <0.01 to 1.39. Sigmoidal allergen binding curves were obtained through ELISA, with low limits of detection (<1 kU/L). Allergen specificity was confirmed through immunoblotting. Pairs of IgE monoclonal antibodies to Ara h 6 were identified that cross-linked after allergen stimulation and induced release of significant levels of β-hexosaminidase (35%-80%) from a humanized rat basophilic cell line. Conclusions Human IgE monoclonal antibodies are unique antibody molecules with potential applications in allergy diagnosis, allergen standardization, and identification of allergenic epitopes for the development of allergy therapeutics. The IgE antibody probes will enable the unequivocal localization and validation of allergenic epitopes.
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Affiliation(s)
| | | | | | - Sayeh Agah
- InBio, Charlottesville, VA, United States
| | | | - Serge A. Versteeg
- Department of Experimental Immunology, Amsterdam University Medical Center, Amsterdam, Netherlands
| | - Ronald van Ree
- Department of Experimental Immunology, Amsterdam University Medical Center, Amsterdam, Netherlands
| | | | - Lorenz Aglas
- Department of Biosciences and Medical Biology, University of Salzburg, Salzburg, Austria
| | - Scott A. Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Anna Pomés
- InBio, Charlottesville, VA, United States
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4
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Zhao Q, Wang Y, Zhu Z, Zhao Q, Zhu L, Jiang L. Efficient reduction of β-lactoglobulin allergenicity in milk using Clostridium tyrobutyricum Z816. FOOD SCIENCE AND HUMAN WELLNESS 2023. [DOI: 10.1016/j.fshw.2022.09.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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5
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Zhao J, Li Y, Xu L, Zeng J, Liu Y, Timira V, Zhang Z, Lin H, Li Z. Thermal induced the structural alterations, increased IgG/IgE binding capacity and reduced immunodetection recovery of tropomyosin from shrimp (Litopenaeus vannamei). Food Chem 2022; 391:133215. [DOI: 10.1016/j.foodchem.2022.133215] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 04/22/2022] [Accepted: 05/11/2022] [Indexed: 12/24/2022]
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Hazebrouck S, Patil SU, Guillon B, Lahood N, Dreskin SC, Adel-Patient K, Bernard H. Immunodominant conformational and linear IgE epitopes lie in a single segment of Ara h 2. J Allergy Clin Immunol 2022; 150:131-139. [PMID: 35150723 PMCID: PMC10440805 DOI: 10.1016/j.jaci.2021.12.796] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 12/16/2021] [Accepted: 12/27/2021] [Indexed: 11/21/2022]
Abstract
BACKGROUND Contribution of conformational epitopes to the IgE reactivity of peanut allergens Ara h 2 and Ara h 6 is at least as important as that of the linear epitopes. However, little is known about these conformational IgE-binding epitopes. OBJECTIVE We investigated the distribution of conformational epitopes on chimeric 2S-albumins. METHODS Recombinant chimeras were generated by exchanging structural segments between Ara h 2 and Ara h 6. Well-refolded chimeras, as verified by circular dichroism analysis, were then used to determine the epitope specificity of mAbs by performing competitive inhibition of IgG binding. Furthermore, we delineated the contribution of each segment to the overall IgE reactivity of both 2S-albumins by measuring the chimeras' IgE-binding capacity with sera from 21 patients allergic to peanut. We finally assessed chimeras' capacity to trigger mast cell degranulation. RESULTS Configuration of the conformational epitopes was preserved in the chimeras. Mouse IgG mAbs, raised against natural Ara h 6, and polyclonal human IgE antibodies recognized different conformational epitopes distributed all along Ara h 6. In contrast, we identified human IgG mAbs specific to different Ara h 2 linear or conformational epitopes located in all segments except the C-terminal one. The major conformational IgE-binding epitope of Ara h 2 was located in a segment located between residues 33 and 81 that also contains the major linear hydroxyproline-containing epitope. Accordingly, this segment is critical for the capacity of Ara h 2 to induce mast cell degranulation. CONCLUSIONS Chimeric 2S-albumins provide new insights on the conformational IgE-binding epitopes of Ara h 2 and Ara h 6. Proximity of the immunodominant linear and conformational IgE-binding epitopes probably contributes to the high allergenic potency of Ara h 2.
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Affiliation(s)
- Stéphane Hazebrouck
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SPI, Gif-sur-Yvette, France.
| | - Sarita U Patil
- Department of Medicine, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, the Food Allergy Center, Massachusetts General Hospital for Children, and Harvard Medical School, Boston, Mass
| | - Blanche Guillon
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SPI, Gif-sur-Yvette, France
| | - Nicole Lahood
- Department of Medicine, Division of Rheumatology, Allergy, and Immunology, Massachusetts General Hospital, the Food Allergy Center, Massachusetts General Hospital for Children, and Harvard Medical School, Boston, Mass
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado-Denver, Aurora, Colo
| | - Karine Adel-Patient
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SPI, Gif-sur-Yvette, France
| | - Hervé Bernard
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SPI, Gif-sur-Yvette, France
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Li WY, Cai ZL, Zhang BP, Chen JJ, Ji K. Identification of an immunodominant IgE epitope of Der p 39, a novel allergen of Dermatophagoides pteronyssinus. World Allergy Organ J 2022; 15:100651. [PMID: 35600837 PMCID: PMC9096144 DOI: 10.1016/j.waojou.2022.100651] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/11/2022] [Accepted: 04/12/2022] [Indexed: 11/16/2022] Open
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8
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Hazebrouck S, Canon N, Dreskin SC. The Effector Function of Allergens. FRONTIERS IN ALLERGY 2022; 3:818732. [PMID: 35386644 PMCID: PMC8974742 DOI: 10.3389/falgy.2022.818732] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/14/2022] [Indexed: 01/29/2023] Open
Abstract
Allergens are antigens that generate an IgE response (sensitization) in susceptible individuals. The allergenicity of an allergen can be thought of in terms of its ability to sensitize as well as its ability to cross-link IgE/IgE receptor complexes on mast cells and basophils leading to release of preformed and newly formed mediators (effector activity). The identity of the allergens responsible for sensitization may be different from those that elicit an allergic response. Effector activity is determined by (1) the amount of specific IgE (sIgE) and in some circumstances the ratio of sIgE to total IgE, (2) the number of high affinity receptors for IgE (FcεR1) on the cell surface, (3) the affinity of binding of sIgE for its epitope and, in a polyclonal response, the collective avidity, (4) the number and spatial relationships of IgE binding epitopes on the allergen and (5) the presence of IgG that can bind to allergen and either block binding of sIgE and/or activate low affinity IgG receptors that activate intracellular inhibitory pathways. This review will discuss these important immunologic and physical properties that contribute to the effector activity of allergens.
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Affiliation(s)
- Stéphane Hazebrouck
- Université Paris Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SPI, Gif-sur-Yvette, France
| | - Nicole Canon
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO, United States
| | - Stephen C. Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO, United States
- *Correspondence: Stephen C. Dreskin
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9
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Ho CW, Hsu JL, Chen SH, Liaw ET, Liu SS, Huang ES, Chen YK, Jean Huang CC, Yu HS. Development and validation of mass spectrometry-based method for detecting shrimp allergen tropomyosin. Lebensm Wiss Technol 2021. [DOI: 10.1016/j.lwt.2021.112367] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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10
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Chen G, Shrock EL, Li MZ, Spergel JM, Nadeau KC, Pongracic JA, Umetsu DT, Rachid R, MacGinnitie AJ, Phipatanakul W, Schneider L, Oettgen HC, Elledge SJ. High-resolution epitope mapping by AllerScan reveals relationships between IgE and IgG repertoires during peanut oral immunotherapy. CELL REPORTS MEDICINE 2021; 2:100410. [PMID: 34755130 PMCID: PMC8563412 DOI: 10.1016/j.xcrm.2021.100410] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 07/18/2021] [Accepted: 09/21/2021] [Indexed: 10/24/2022]
Abstract
Peanut allergy can result in life-threatening reactions and is a major public health concern. Oral immunotherapy (OIT) induces desensitization to food allergens through administration of increasing amounts of allergen. To dissect peanut-specific immunoglobulin E (IgE) and IgG responses in subjects undergoing OIT, we have developed AllerScan, a method that leverages phage-display and next-generation sequencing to identify the epitope targets of peanut-specific antibodies. We observe a striking diversification and boosting of the peanut-specific IgG repertoire after OIT and a reduction in pre-existing IgE levels against individual epitopes. High-resolution epitope mapping reveals shared recognition of public epitopes in Ara h 1, 2, 3, and 7. In individual subjects, OIT-induced IgG specificities overlap extensively with IgE and exhibit strikingly similar antibody footprints, suggesting related clonal lineages or convergent evolution of peanut-specific IgE and IgG B cells. Individual differences in epitope recognition identified via AllerScan could inform safer and more effective personalized immunotherapy.
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Affiliation(s)
- Genghao Chen
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA.,Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA 02115, USA
| | - Ellen L Shrock
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA.,Program in Biological and Biomedical Sciences, Harvard University, Cambridge, MA 02115, USA
| | - Mamie Z Li
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA
| | - Jonathan M Spergel
- Division of Allergy and Immunology, Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, Perelman School of Medicine of University of Pennsylvania, Philadelphia, PA, USA
| | - Kari C Nadeau
- Department of Medicine, Sean N Parker Center for Allergy and Asthma Research, Stanford University, Palo Alto, CA, USA
| | - Jacqueline A Pongracic
- Division of Pediatric Allergy and Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.,Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA
| | - Dale T Umetsu
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Rima Rachid
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew J MacGinnitie
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Wanda Phipatanakul
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Lynda Schneider
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Hans C Oettgen
- Division of Immunology, Department of Pediatrics, Boston Children's Hospital, Boston, MA 02115, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Stephen J Elledge
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.,Division of Genetics, Department of Medicine, Howard Hughes Medical Institute, Brigham and Women's Hospital, Boston, MA 02115, USA
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11
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Dreskin SC, Koppelman SJ, Andorf S, Nadeau KC, Kalra A, Braun W, Negi SS, Chen X, Schein CH. The importance of the 2S albumins for allergenicity and cross-reactivity of peanuts, tree nuts, and sesame seeds. J Allergy Clin Immunol 2021; 147:1154-1163. [PMID: 33217410 PMCID: PMC8035160 DOI: 10.1016/j.jaci.2020.11.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 11/06/2020] [Accepted: 11/10/2020] [Indexed: 12/17/2022]
Abstract
Allergies to peanuts, tree nuts, and sesame seeds are among the most important food-related causes of anaphylaxis. Important clinical questions include: Why is there a variable occurrence of coallergy among these foods and Is this immunologically mediated? The clinical and immunologic data summarized here suggest an immunologic basis for these coallergies that is based on similarities among the 2S albumins. Data from component resolved diagnostics have highlighted the relationship between IgE binding to these allergens and the presence of IgE-mediated food allergy. Furthermore, in vitro and in vivo experiments provide strong evidence that the 2S albumins are the most important allergens in peanuts for inducing an allergic effector response. Although the 2S albumins are diverse, they have a common disulfide-linked core with similar physicochemical properties that make them prime candidates to explain much of the observed coallergy among peanuts, tree nuts, and sesame seeds. The well-established frequency of cashew and pistachio nut coallergy (64%-100%) highlights how the structural similarities among their 2S albumins may account for observed clinical cross-reactivity. A complete understanding of the physicochemical properties of the 2S albumins in peanuts, tree nuts, and sesame seeds will enhance our ability to diagnose, treat, and ultimately prevent these allergies.
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Affiliation(s)
- Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, Colo.
| | - Stef J Koppelman
- Food Allergy Research and Resource Program, Department of Food Science and Technology, University of Nebraska, Lincoln, Neb
| | - Sandra Andorf
- Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Division of Allergy and Immunology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio; Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Stanford, Calif
| | - Kari C Nadeau
- Sean N. Parker Center for Allergy and Asthma Research, Stanford University School of Medicine, Stanford, Calif
| | - Anjeli Kalra
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, Colo
| | - Werner Braun
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, Tex; Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, Tex
| | - Surendra S Negi
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, Tex; Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, Tex
| | - Xueni Chen
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, Colo
| | - Catherine H Schein
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, Tex; Institute for Human Infection and Immunity, The University of Texas Medical Branch, Galveston, Tex.
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Digestomics of Cow's Milk: Short Digestion-Resistant Peptides of Casein Form Functional Complexes by Aggregation. Foods 2020; 9:foods9111576. [PMID: 33143174 PMCID: PMC7692894 DOI: 10.3390/foods9111576] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/18/2020] [Accepted: 10/26/2020] [Indexed: 01/28/2023] Open
Abstract
The aim of this study was to identify short digestion-resistant peptides (SDRPs) released by pepsin digestion of the whole cow’s milk and examine their IgE reactivity and allergenicity. Raw milk was subjected to simulated gastric digestion. SDRPs were fractionated from the digests and identified by MS. Milk SDRPs were evaluated for aggregability, propensity to compete for IgE binding with individual milk allergens, and ability to bind IgG4 from allergic and milk-tolerant individuals. The majority of milk SDRPs originated from caseins (97% of peptides) and overlapped with the known IgE epitopes of cow’s milk allergens. SDRPs competed with milk proteins for binding to human IgE and readily formed aggregates. The average peptide length was 10.6 ± 3.5 amino acids. The ability to provoke allergenic in vivo responses was confirmed by skin-prick testing (SPT) in five milk-allergic subjects. This was attributed to the peptide ability to aggregate into non-covalent complexes. SDRPs are able to induce response in SPT, but only in 50% of the sera SDRPs were able to inhibit IgG4 binding to caseins. Hence, SDRPs corresponding to the mainly continuous epitopes of milk proteins induce allergenic in vivo responses in milk-allergic subjects due to aggregation.
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13
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Sánchez-Ruano L, de la Hoz B, Martínez-Botas J. Clinical utility of microarray B-cell epitope mapping in food allergies: A systematic review. Pediatr Allergy Immunol 2020; 31:175-185. [PMID: 31655013 DOI: 10.1111/pai.13141] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Revised: 09/13/2019] [Accepted: 09/30/2019] [Indexed: 11/29/2022]
Abstract
BACKGROUND Peptide microarray technology has been proposed as a useful tool for diagnosing food allergy. However, there is considerable heterogeneity in the clinical methods and analytical procedures used to assess its diagnostic and prognostic performance. We performed a systematic review of studies that have used B-cell epitopes by peptide microarray in food allergies to identify the clinical utility of this immunologic technique. METHODS Studies were screened in PubMed, Web of Science, and Embase according to an established keyword algorithm. Data extraction was performed, and information was collected in an Excel database. Descriptive analysis was carried out using Stata software. RESULTS Thirty relevant studies were identified. Most articles were cross-sectional (n = 24), included epitope mapping (n = 9), and assessed diagnostic utility (n = 11). All studies recruited allergic patients, and some included additional patients (sensitized, persistent, and tolerant). The primary microarray variables studied were IgE intensity (n = 29), IgG4 intensity (n = 15), and number of peptides (n = 17). Statistical approaches differed significantly between studies, with the Wilcoxon test being the most frequently used (n = 10). CONCLUSIONS Sensitization to particular epitopes of milk, peanut, and shrimp allergens can be used to determine clinical reactivity, persistence, severity, or response to oral immunotherapy; however, important methodological questions need to be addressed before drawing definitive conclusions. More research is needed to address the accuracy and clinical benefits of microarray-based technology. Standards are required to improve consistency and reproducibility, and to allow for better understanding of research findings.
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Affiliation(s)
- Laura Sánchez-Ruano
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal (IRYCIS), Madrid, Spain
| | - Belén de la Hoz
- Servicio de Alergología, Hospital Universitario Ramón y Cajal (IRYCIS), Madrid, Spain.,ARADyAL Network RD16/0006/0009, Instituto de Salud Carlos III, Madrid, Spain
| | - Javier Martínez-Botas
- Servicio de Bioquímica-Investigación, Hospital Universitario Ramón y Cajal (IRYCIS), Madrid, Spain.,CIBER de Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de Salud Carlos III, Madrid, Spain
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14
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Ole e 15 and its human counterpart -PPIA- chimeras reveal an heterogeneous IgE response in olive pollen allergic patients. Sci Rep 2019; 9:15027. [PMID: 31636292 PMCID: PMC6803672 DOI: 10.1038/s41598-019-51005-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/16/2019] [Indexed: 12/27/2022] Open
Abstract
Olive pollen is a major cause of immunoglobulin E (IgE)-mediated allergy in Mediterranean countries. It is expected to become a worldwide leading allergenic source because olive cultivation is increasing in many countries. Ole e 15 belongs to the cyclophilin pan-allergen family, which includes highly cross-reactive allergens from non-related plant, animal and mold species. Here, the amino acid differences between Ole e 15 and its weak cross-reactive human homolog PPIA were grafted onto Ole e 15 to assess the contribution of specific surface areas to the IgE-binding. Eight Ole e 15-PPIA chimeras were produced in E. coli, purified and tested with 20 sera from Ole e 15-sensitized patients with olive pollen allergy by ELISA experiments. The contribution of linear epitopes was analyzed using twelve overlapping peptides spanning the entire Ole e 15 sequence. All the patients displayed a diverse reduction of the IgE-reactivity to the chimeras, revealing a highly polyclonal and patient-specific response to Ole e 15. IgE-epitopes are distributed across the entire Ole e 15 surface. Two main surface areas containing relevant conformational epitopes have been characterized. This is the first study to identify important IgE-binding regions on the surface of an allergenic cyclophilin.
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15
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Tscheppe A, Palmberger D, van Rijt L, Kalic T, Mayr V, Palladino C, Kitzmüller C, Hemmer W, Hafner C, Bublin M, van Ree R, Grabherr R, Radauer C, Breiteneder H. Development of a novel Ara h 2 hypoallergen with no IgE binding or anaphylactogenic activity. J Allergy Clin Immunol 2019; 145:229-238. [PMID: 31525384 PMCID: PMC7100897 DOI: 10.1016/j.jaci.2019.08.036] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 07/31/2019] [Accepted: 08/16/2019] [Indexed: 02/03/2023]
Abstract
Background To date, no safe allergen-specific immunotherapy for patients with peanut allergy is available. Previous trials were associated with severe side effects. Objective We sought to determine the relative importance of conformational and linear IgE-binding epitopes of the major peanut allergen Ara h 2 and to produce a hypoallergenic variant with abolished anaphylactogenic activity. Methods Wild-type Ara h 2 and a mutant lacking the loops containing linear IgE epitopes were produced in insect cells. Conformational IgE epitopes were removed by unfolding these proteins through reduction and alkylation. IgE binding was tested by means of ELISA with sera from 48 Ara h 2–sensitized patients with peanut allergy. Basophil activation and T-cell proliferation were tested with blood samples from selected patients. Anaphylactogenic potency was tested by using intraperitoneal challenge of mice sensitized intragastrically to peanut extract. Results Patients’ IgE recognized conformational and linear epitopes in a patient-specific manner. The unfolded mutant lacking both types of epitopes displayed significantly lower IgE binding (median ELISA OD, 0.03; interquartile range, 0.01-0.06) than natural Ara h 2 (median ELISA OD, 0.99; interquartile range, 0.90-1.03; P < .01). Basophil activation by unfolded mutant Ara h 2 was low (median area under the curve, 72 vs 138 for native wild-type Ara h 2; P < .05), but its ability to induce T-cell proliferation was retained. Unfolded mutants without conformational epitopes did not induce anaphylaxis in peanut-sensitized mice. Conclusions By removing conformational and linear IgE epitopes, a hypoallergenic Ara h 2 mutant with abolished IgE binding and anaphylactogenic potency but retained T-cell activation was generated.
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Affiliation(s)
- Angelika Tscheppe
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Dieter Palmberger
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Leonie van Rijt
- Department of Experimental Immunology, Amsterdam UMC, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Tanja Kalic
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Vanessa Mayr
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Chiara Palladino
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Claudia Kitzmüller
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Christine Hafner
- Department of Dermatology, University Hospital St Pölten, Karl Landsteiner University of Health Sciences, St Pölten, and the Karl Landsteiner Institute for Dermatological Research, St Pölten, Austria
| | - Merima Bublin
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Ronald van Ree
- Department of Experimental Immunology, Amsterdam UMC, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands; Department of Otorhinolaryngology, Amsterdam UMC, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Reingard Grabherr
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Christian Radauer
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
| | - Heimo Breiteneder
- Institute of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
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16
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Identification of pyruvate kinase 2 as a possible crab allergen and analysis of allergenic proteins in crabs consumed in Taiwan. Food Chem 2019; 289:413-418. [PMID: 30955631 DOI: 10.1016/j.foodchem.2019.03.074] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 03/15/2019] [Accepted: 03/16/2019] [Indexed: 11/20/2022]
Abstract
In Taiwan, crab is one of the main causes for food allergy. Several proteins are recognized as crustacean allergens, and tropomyosin is known to be the major one. However, sensitization patterns of Taiwanese patients to crustacean allergens remain unclear. Therefore, we analyzed the specific-IgE binding ability of crucifix crab (Charybdis feriatus) allergens by western blot using patients' sera. In particular, we found a 56 kDa protein in crucifix crab reacted with specific-IgEs in patients' sera, and we further identified the protein as a novel crab allergen pyruvate kinase 2. Additionally, little is known about tropomyosin contents in crabs consumed in Taiwan. Thus, we also quantified the levels of tropomyosin by using enzyme-linked immunosorbent assay (ELISA) among raw and cooked crab species. Our results showed tropomyosin levels varied depending on crab species. In summary, these findings improve the understanding of crustacean allergens and contribute to the clinical diagnosis of crustacean allergies.
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17
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Designer covalent heterobivalent inhibitors prevent IgE-dependent responses to peanut allergen. Proc Natl Acad Sci U S A 2019; 116:8966-8974. [PMID: 30962381 PMCID: PMC6500160 DOI: 10.1073/pnas.1820417116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Allergies are a result of allergen proteins cross-linking allergen-specific IgE (sIgE) on the surface of mast cells and basophils. The diversity and complexity of allergen epitopes, and high-affinity of the sIgE-allergen interaction have impaired the development of allergen-specific inhibitors of allergic responses. This study presents a design of food allergen-specific sIgE inhibitors named covalent heterobivalent inhibitors (cHBIs) that selectively form covalent bonds to only sIgEs, thereby permanently inhibiting them. Using screening reagents termed nanoallergens, we identified two immunodominant epitopes in peanuts that were common in a population of 16 allergic patients. Two cHBIs designed to inhibit only these two epitopes completely abrogated the allergic response in 14 of the 16 patients in an in vitro assay and inhibited basophil activation in an allergic patient ex vivo analysis. The efficacy of the cHBI design has valuable clinical implications for many allergen-specific responses and more broadly for any antibody-based disease.
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19
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Faisal M, Vasiljevic T, Donkor ON. Effects of selected processing treatments on antigenicity of banana prawn (Fenneropenaeus merguiensis
) tropomyosin. Int J Food Sci Technol 2018. [DOI: 10.1111/ijfs.13922] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Md Faisal
- Advanced Food Systems Research Unit; Institute of Sustainable Industries & Liveable Cities and College of Health and Biomedicine; Victoria University; Werribee Campus, PO Box 14428 Melbourne Vic. 8001 Australia
| | - Todor Vasiljevic
- Advanced Food Systems Research Unit; Institute of Sustainable Industries & Liveable Cities and College of Health and Biomedicine; Victoria University; Werribee Campus, PO Box 14428 Melbourne Vic. 8001 Australia
| | - Osaana N. Donkor
- Advanced Food Systems Research Unit; Institute of Sustainable Industries & Liveable Cities and College of Health and Biomedicine; Victoria University; Werribee Campus, PO Box 14428 Melbourne Vic. 8001 Australia
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20
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Abstract
With the increased global awareness and rise in food allergies, a multifold interest in food allergens is evident. The presence of undeclared food allergens results in expensive food recalls and increased risks of anaphylaxis for the sensitive individuals. Regardless of the allergenic food, the immunogen needs to be identified and detected before making any efforts to inactivate/eliminate it. In type I food allergies, protein immunogen cross-links immunoglobulin E, leading to basophil/mast cell degranulation, resulting in the symptoms that range from mild irritation to anaphylaxis. A portion/part of the protein, known as the epitope, can interact with either antibodies to elicit allergic reactions or T-cell receptors to initiate allergic sensitization. Antibody-recognized epitopes can be either a linear sequence of amino acids (linear epitope) or a three-dimensional motif (conformational epitope), while T-cell-receptor-recognized epitopes are exclusively linear peptides. Identifying and characterizing human-allergy-relevant epitopes are important for allergy diagnosis/prognosis, immunotherapy, and developing food processing methods that can reduce/eliminate immunogencity/immunoreactivity of the allergen.
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Affiliation(s)
- Changqi Liu
- School of Exercise and Nutritional Sciences, College of Health and Human Services , San Diego State University , 308 ENS Building, 5500 Campanile Drive , San Diego , California 92182-7251 , United States
| | - Shridhar K Sathe
- Department of Nutrition, Food & Exercise Sciences, College of Human Sciences , Florida State University , 402 SAN, 120 Convocation Way , Tallahassee , Florida 32306-1493 , United States
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21
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Zaffran VD, Sathe SK. Immunoreactivity of Biochemically Purified Amandin from Thermally Processed Almonds (Prunus dulcis L.). J Food Sci 2018; 83:1805-1809. [PMID: 29905947 DOI: 10.1111/1750-3841.14206] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 04/29/2018] [Accepted: 05/02/2018] [Indexed: 11/30/2022]
Abstract
Almond seeds were subjected to select thermal processing and amandin was purified from processed and unprocessed (control) seeds using cryoprecipitation. Amandin immunoreactivity was assessed using two murine monoclonal antibodies (mAbs)-4C10 and 4F10 detecting human IgE-relevant conformational and linear epitopes, respectively. Overall amandin immunoreactivity following thermal treatment ranged from 64.9% to 277.8% (4C10) and 81.3% to 270.3% (4F10). Except for autoclaving (121 °C, 15 psi, 30 min) and roasting (160 °C, 30 min), the tested processing conditions resulted in increased immunoreactivity as determined by mAbs 4C10 and 4F10-based enzyme-linked immunosorbent assays (ELISAs). A significant, yet not complete, reduction in immunoreactivity was caused by autoclaving (121 °C, 15 psi, 30 min) and roasting (160 °C, 30 min). Western- and dot-blot immunoassays corroborated the ELISA results, confirming amandin thermal stability. PRACTICAL APPLICATION The tested immunoassays indicated amandin to be stable, regardless of the targeted epitope and the processing method that whole almond seeds were subjected to.
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Affiliation(s)
- Valerie D Zaffran
- Dept. of Nutrition, Food & Exercise Sciences, Florida State Univ., Tallahassee, FL, 32306-1493, U.S.A
| | - Shridhar K Sathe
- Dept. of Nutrition, Food & Exercise Sciences, Florida State Univ., Tallahassee, FL, 32306-1493, U.S.A
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22
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Seafood allergy: A comprehensive review of fish and shellfish allergens. Mol Immunol 2018; 100:28-57. [PMID: 29858102 DOI: 10.1016/j.molimm.2018.04.008] [Citation(s) in RCA: 188] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 04/11/2018] [Accepted: 04/16/2018] [Indexed: 11/23/2022]
Abstract
Seafood refers to several distinct groups of edible aquatic animals including fish, crustacean, and mollusc. The two invertebrate groups of crustacean and mollusc are, for culinary reasons, often combined as shellfish but belong to two very different phyla. The evolutionary and taxonomic diversity of the various consumed seafood species poses a challenge in the identification and characterisation of the major and minor allergens critical for reliable diagnostics and therapeutic treatments. Many allergenic proteins are very different between these groups; however, some pan-allergens, including parvalbumin, tropomyosin and arginine kinase, seem to induce immunological and clinical cross-reactivity. This extensive review details the advances in the bio-molecular characterisation of 20 allergenic proteins within the three distinct seafood groups; fish, crustacean and molluscs. Furthermore, the structural and biochemical properties of the major allergens are described to highlight the immunological and subsequent clinical cross-reactivities. A comprehensive list of purified and recombinant allergens is provided, and the applications of component-resolved diagnostics and current therapeutic developments are discussed.
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23
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Lozano-Ojalvo D, López-Fandiño R. Immunomodulating peptides for food allergy prevention and treatment. Crit Rev Food Sci Nutr 2017; 58:1629-1649. [PMID: 28102702 DOI: 10.1080/10408398.2016.1275519] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Among the most promising strategies currently assayed against IgE-mediated allergic diseases stands the possibility of using immunomodulating peptides to induce oral tolerance toward offending food allergens or even to prevent allergic sensitization. This review focuses on the beneficial effects of food derived immunomodulating peptides on food allergy, which can be directly exerted in the intestinal tract or once being absorbed through the intestinal epithelial barrier to interact with immune cells. Food peptides influence intestinal homeostasis by maintaining and reinforcing barrier function or affecting intestinal cell-signalling to nearby immune cells and mucus secretion. In addition, they can stimulate cells of the innate and adaptive immune system while supressing inflammatory responses. Peptides represent an attractive alternative to whole allergens to enhance the safety and efficacy of immunotherapy treatments. The conclusions drawn from curative and preventive experiments in murine models are promising, although there is a need for more pre-clinical studies to further explore the immunomodulating strategy and its mechanisms and for a deeper knowledge of the peptide sequence and structural requirements that determine the immunoregulatory function.
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Affiliation(s)
- Daniel Lozano-Ojalvo
- a Instituto de Investigación en Ciencias de la Alimentación (CIAL, CSIC-UAM) , Madrid , Spain
| | - Rosina López-Fandiño
- a Instituto de Investigación en Ciencias de la Alimentación (CIAL, CSIC-UAM) , Madrid , Spain
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24
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Chen X, Dreskin SC. Application of phage peptide display technology for the study of food allergen epitopes. Mol Nutr Food Res 2017; 61. [PMID: 27995755 DOI: 10.1002/mnfr.201600568] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 11/09/2016] [Accepted: 12/05/2016] [Indexed: 12/16/2022]
Abstract
Phage peptide display technology has been used to identify IgE-binding mimotopes (mimics of natural epitopes) that mimic conformational epitopes. This approach is effective in the characterization of those epitopes that are important for eliciting IgE-mediated allergic responses by food allergens and those that are responsible for cross-reactivity among allergenic food proteins. Application of this technology will increase our understanding of the mechanisms whereby food allergens elicit allergic reactions, will facilitate the discovery of diagnostic reagents and may lead to mimotope-based immunotherapy.
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Affiliation(s)
- Xueni Chen
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
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25
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Mahajan A, Youssef LA, Cleyrat C, Grattan R, Lucero SR, Mattison CP, Erasmus MF, Jacobson B, Tapia L, Hlavacek WS, Schuyler M, Wilson BS. Allergen Valency, Dose, and FcεRI Occupancy Set Thresholds for Secretory Responses to Pen a 1 and Motivate Design of Hypoallergens. THE JOURNAL OF IMMUNOLOGY 2016; 198:1034-1046. [PMID: 28039304 DOI: 10.4049/jimmunol.1601334] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 11/30/2016] [Indexed: 11/19/2022]
Abstract
Ag-mediated crosslinking of IgE-FcεRI complexes activates mast cells and basophils, initiating the allergic response. Of 34 donors recruited having self-reported shrimp allergy, only 35% had significant levels of shrimp-specific IgE in serum and measurable basophil secretory responses to rPen a 1 (shrimp tropomyosin). We report that degranulation is linked to the number of FcεRI occupied with allergen-specific IgE, as well as the dose and valency of Pen a 1. Using clustered regularly interspaced palindromic repeat-based gene editing, human RBLrαKO cells were created that exclusively express the human FcεRIα subunit. Pen a 1-specific IgE was affinity purified from shrimp-positive plasma. Cells primed with a range of Pen a 1-specific IgE and challenged with Pen a 1 showed a bell-shaped dose response for secretion, with optimal Pen a 1 doses of 0.1-10 ng/ml. Mathematical modeling provided estimates of receptor aggregation kinetics based on FcεRI occupancy with IgE and allergen dose. Maximal degranulation was elicited when ∼2700 IgE-FcεRI complexes were occupied with specific IgE and challenged with Pen a 1 (IgE epitope valency of ≥8), although measurable responses were achieved when only a few hundred FcεRI were occupied. Prolonged periods of pepsin-mediated Pen a 1 proteolysis, which simulates gastric digestion, were required to diminish secretory responses. Recombinant fragments (60-79 aa), which together span the entire length of tropomyosin, were weak secretagogues. These fragments have reduced dimerization capacity, compete with intact Pen a 1 for binding to IgE-FcεRI complexes, and represent a starting point for the design of promising hypoallergens for immunotherapy.
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Affiliation(s)
- Avanika Mahajan
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Lama A Youssef
- Department of Pharmaceutics and Pharmaceutical Technology, School of Pharmacy, Damascus University, Damascus, Syria.,National Commission for Biotechnology, Damascus, Syria
| | - Cédric Cleyrat
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Rachel Grattan
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Shayna R Lucero
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Christopher P Mattison
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, LA 70124
| | - M Frank Erasmus
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131
| | - Bruna Jacobson
- Department of Computer Sciences, University of New Mexico, Albuquerque, NM 87131
| | - Lydia Tapia
- Department of Computer Sciences, University of New Mexico, Albuquerque, NM 87131
| | - William S Hlavacek
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545.,Theoretical Biology and Biophysics Group, Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545; and
| | - Mark Schuyler
- Department of Medicine, University of New Mexico, Albuquerque, NM 87131
| | - Bridget S Wilson
- Department of Pathology, University of New Mexico, Albuquerque, NM 87131;
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Chen X, Negi SS, Liao S, Gao V, Braun W, Dreskin SC. Conformational IgE epitopes of peanut allergens Ara h 2 and Ara h 6. Clin Exp Allergy 2016; 46:1120-1128. [PMID: 27238146 DOI: 10.1111/cea.12764] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/11/2016] [Accepted: 05/14/2016] [Indexed: 12/01/2022]
Abstract
BACKGROUND Cross-linking of IgE antibody by specific epitopes on the surface of mast cells is a prerequisite for triggering symptoms of peanut allergy. IgE epitopes are frequently categorized as linear or conformational epitopes. Although linear IgE-binding epitopes of peanut allergens have been defined, little is known about conformational IgE-binding epitopes. OBJECTIVE To identify clinically relevant conformational IgE epitopes of the two most important peanut allergens, Ara h 2 and Ara h 6, using phage peptide library. METHODS A phage 12mer peptide library was screened with allergen-specific IgE from 4 peanut-allergic patients. Binding of the mimotopes to IgE from a total of 29 peanut-allergic subjects was measured by ELISA. The mimotope sequences were mapped on the surface areas of Ara h 2 and Ara h 6 using EpiSearch. RESULTS Forty-one individual mimotopes were identified that specifically bind anti- Ara h 2/Ara h 6 IgE as well as rabbit anti-Ara h 2 and anti-Ara h 6 IgG. Sequence alignment showed that none of the mimotope sequences match a linear segment of the Ara h 2 or Ara h 6 sequences. EpiSearch analysis showed that all the mimotopes mapped to surface patches of Ara h 2 and Ara h 6. Eight of the mimotopes were recognized by more than 90% of the patients, suggesting immunodominance. Each patient had distinct IgE recognition patterns but the recognition frequency was not correlated to the concentration of peanut specific IgE or to clinical history. CONCLUSIONS The mimotopes identified in this study represent conformational epitopes. Identification of similar surface patches on Ara h 2 and Ara h 6 further underscores the similarities between these two potent allergens.
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Affiliation(s)
- Xueni Chen
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO
| | - Surendra S Negi
- Sealy Center for Structural Biology and Molecular Biophysics, Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555
| | - Sumei Liao
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO
| | - Valerie Gao
- Molecular Cellular Developmental Biology, University of Colorado, Boulder, CO
| | - Werner Braun
- Sealy Center for Structural Biology and Molecular Biophysics, Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO
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Abstract
Food allergy is receiving increased attention in recent years. Because there is currently no known cure for food allergy, avoiding the offending food is the best defense for sensitive individuals. Type I food allergy is mediated by food proteins, and thus, theoretically, any food protein is a potential allergen. Variability of an individual's immune system further complicates attempts to understand allergen-antibody interaction. In this article, we briefly review food allergy occurrence, prevalence, mechanisms, and detection. Efforts aimed at reducing/eliminating allergens through food processing are discussed. Future research needs are addressed.
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Affiliation(s)
- Shridhar K Sathe
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, Florida 30306-1493;
| | - Changqi Liu
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, Florida 30306-1493;
| | - Valerie D Zaffran
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, Florida 30306-1493;
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28
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Tao B, Bernardo K, Eldi P, Chegeni N, Wiese M, Colella A, Kral A, Hayball J, Smith W, Forsyth K, Chataway T. Extended boiling of peanut progressively reduces IgE allergenicity while retaining T cell reactivity. Clin Exp Allergy 2016; 46:1004-14. [DOI: 10.1111/cea.12740] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 03/09/2016] [Accepted: 03/31/2016] [Indexed: 11/30/2022]
Affiliation(s)
- B. Tao
- Department of Paediatrics and Child Health; Flinders University of South Australia; Adelaide SA Australia
- Flinders Proteomics Facility; Department of Human Physiology; Flinders University of South Australia; Adelaide SA Australia
| | - K. Bernardo
- Flinders Proteomics Facility; Department of Human Physiology; Flinders University of South Australia; Adelaide SA Australia
| | - P. Eldi
- School of Pharmacy and Medical Sciences; University of South Australia; Adelaide SA Australia
| | - N. Chegeni
- Flinders Proteomics Facility; Department of Human Physiology; Flinders University of South Australia; Adelaide SA Australia
| | - M. Wiese
- School of Pharmacy and Medical Sciences; University of South Australia; Adelaide SA Australia
| | - A. Colella
- Department of Immunology; Flinders University of South Australia; Adelaide SA Australia
| | - A. Kral
- Department and School of Medicine; University of Adelaide; Adelaide SA Australia
| | - J. Hayball
- School of Pharmacy and Medical Sciences; University of South Australia; Adelaide SA Australia
| | - W. Smith
- Department and School of Medicine; University of Adelaide; Adelaide SA Australia
| | - K. Forsyth
- Department of Paediatrics and Child Health; Flinders University of South Australia; Adelaide SA Australia
| | - T. Chataway
- Flinders Proteomics Facility; Department of Human Physiology; Flinders University of South Australia; Adelaide SA Australia
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29
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Deak PE, Vrabel MR, Pizzuti VJ, Kiziltepe T, Bilgicer B. Nanoallergens: A multivalent platform for studying and evaluating potency of allergen epitopes in cellular degranulation. Exp Biol Med (Maywood) 2016; 241:996-1006. [PMID: 27188517 DOI: 10.1177/1535370216644533] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Degranulation caused by type I hypersensitivity (allergies) is a complex biophysical process, and available experimental models for studying relevant immunoglobulin E binding epitopes on allergen proteins lack the ability to adequately evaluate, rank, and associate these epitopes individually and with each other. In this study, we propose a new allergy model system for studying potential allergen epitopes using nanoallergens, liposomes modified to effectively display IgE binding epitopes/haptens. By utilizing the covalently conjugated lipid tails on two hapten molecules (dinitrophenol and dansyl), hapten molecules were successfully incorporated into liposomes with high precision to form nanoallergens. Nanoallergens, with precisely controlled high-particle valency, can trigger degranulation with much greater sensitivity than commonly used bovine serum albumin conjugates. In rat basophil leukemia cell experiments, nanoallergens with only 2% hapten loading were able to trigger degranulation in vitro at concentrations as low as 10 pM. Additionally, unlike bovine serum albumin-hapten conjugates, nanoallergens allow exact control over particle size and valency. By varying the nanoallergen parameters such as size, valency, monovalent affinity of hapten, and specific IgE ratios, we exposed the importance of these variables on degranulation intensity while demonstrating nanoallergens' potential for evaluating both high- and low-affinity epitopes. The data presented in this article establish nanoallergen platform as a reliable and versatile allergy model to study and evaluate allergen epitopes in mast cell degranulation.
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Affiliation(s)
- Peter E Deak
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, IN 46556, USA
| | - Maura R Vrabel
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, IN 46556, USA
| | - Vincenzo J Pizzuti
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, IN 46556, USA
| | - Tanyel Kiziltepe
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, IN 46556, USA Advanced Diagnostics and Therapeutics, University of Notre Dame, IN 46556, USA
| | - Basar Bilgicer
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, IN 46556, USA Advanced Diagnostics and Therapeutics, University of Notre Dame, IN 46556, USA Department of Chemistry and Biochemistry, University of Notre Dame, IN 46556, USA
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Aiello D, Materazzi S, Risoluti R, Thangavel H, Di Donna L, Mazzotti F, Casadonte F, Siciliano C, Sindona G, Napoli A. A major allergen in rainbow trout (Oncorhynchus mykiss): complete sequences of parvalbumin by MALDI tandem mass spectrometry. MOLECULAR BIOSYSTEMS 2016; 11:2373-82. [PMID: 26111497 DOI: 10.1039/c5mb00148j] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Fish parvalbumin (PRVB) is an abundant and stable protein in fish meat. The variation in cross-reactivity among individuals is well known and explained by a broad repertoire of molecular forms and differences between IgE-binding epitopes in fish species. PVRB has "sequential" epitopes, which retain their IgE-binding capacity and allergenicity also after heating and digestion using proteolytic enzymes. From the allergonomics perspective, PRVB is still a challenging target due to its multiple isoforms present at different degrees of distribution. Little information is available in the databases about PVRBs from Oncorhynchus mykiss. At present, only two validated, incomplete isoforms of this species are included in the protein databases: parvalbumin beta 1 (P86431) and parvalbumin beta 2 (P86432). A simple and rapid protocol has been developed for selective solubilization of PRVB from the muscle of farmed rainbow trout (Oncorhynchus mykiss), followed by calcium depletion, proteolytic digestion, MALDI MS, and MS/MS analysis. With this strategy thermal allergen release was assessed and PRVB1 (P86431), PRVB1.1, PRVB2 (P86432) and PRVB2.1 variants from the rainbow trout were sequenced. The correct ordering of peptide sequences was aided by mapping the overlapping enzymatic digests. The deduced peptide sequences were arranged and the theoretical molecular masses (Mr) of the resulting sequences were calculated. Experimental masses (Mr) of each PRVB variant were measured by linear MALDI-TOF.
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Affiliation(s)
- Donatella Aiello
- Department of Chemistry and Chemical Technologies, University of Calabria, Via P. Bucci, Cubo 12/D, 87036 Arcavacata di Rende (CS), Italy.
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Benedé S, López-Expósito I, Molina E, López-Fandiño R. Egg proteins as allergens and the effects of the food matrix and processing. Food Funct 2016; 6:694-713. [PMID: 25598200 DOI: 10.1039/c4fo01104j] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Hen eggs are an important and inexpensive source of high-quality proteins in the human diet. Egg, either as a whole or its constituents (egg yolk and white), is a key ingredient in many food products by virtue of its nutritional value and unique functional properties, such as emulsifying, foaming, and gelling. Nevertheless, egg is also known because of its allergenic potential and, in fact, it is the second most frequent source of allergic reactions, particularly in children. This review deals with the structural or functional properties of egg proteins that make them strong allergens. Their ability to sensitize and/or elicit allergic reactions is linked to their resistance to gastroduodenal digestion, which ultimately allows them to interact with the intestinal mucosa where absorption occurs. The factors that affect protein digestibility, whether increasing it, decreasing it, or inducing a different proteolysis pattern, and their influence on their capacity to induce or trigger an allergic reaction are discussed. Special attention is paid to the effect of the food matrix and the processing practices on the capacity of egg proteins to modulate the immune response.
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Affiliation(s)
- S Benedé
- Instituto de Investigación en Ciencias de la Alimentación (CIAL, CSIC-UAM), Nicolás Cabrera 9, 28049 Madrid, Spain.
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Otsu K, Guo R, Dreskin SC. Epitope analysis of Ara h 2 and Ara h 6: characteristic patterns of IgE-binding fingerprints among individuals with similar clinical histories. Clin Exp Allergy 2015; 45:471-84. [PMID: 25213872 DOI: 10.1111/cea.12407] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2014] [Revised: 07/15/2014] [Accepted: 08/14/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Ara h 2 and Ara h 6 are moderately homologous and highly potent peanut allergens. OBJECTIVE To identify IgE-binding linear epitopes of Ara h 6, compare them to those of Ara h 2, and to stratify binding based on clinical histories. METHODS Thirty highly peanut-allergic subjects were stratified by clinical history. Sera were diluted to contain the same amount of anti-peanut IgE. IgE binding to overlapping 20-mer peptides of Ara h 2 and Ara h 6 was assessed using microarrays. RESULTS Each subject had a unique IgE-binding fingerprint to peptides; these data were coalesced into epitope binding. IgE from subjects with a history of more severe reactions (n = 19) had a smaller frequency of binding events (BEs) for both Ara h 2 (52 BEs of 152 (19X8epitopes) possible BEs and Ara h 6 (13 BEs of 133 (19X7 epitopes) possible BEs) compared to IgE from those with milder histories (n = 11) (Ara h 2: 47 BEs of 88 (11X8 epitopes) possible BEs, P < 0.01; Ara h 6: 25 BEs of 77 (11X7 epitopes) possible BEs, P < 0.001). Using an unsupervised hierarchal cluster analysis, subjects with similar histories tended to cluster. We have tentatively identified a high-risk pattern of binding to peptides of Ara h 2 and Ara h 6, predominantly in subjects with a history of more severe reactions (OR = 12.6; 95% CI: 2.0-79.5; P < 0.01). CONCLUSIONS AND CLINICAL RELEVANCE IgE from patients with more severe clinical histories recognize fewer linear epitopes of Ara h 2 and Ara h 6 than do subjects with milder reactions and bind these epitopes in characteristic patterns. Close examination of IgE binding to epitopes of Ara h 2 and Ara h 6 may have prognostic value.
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Affiliation(s)
- K Otsu
- Division of Allergy and Clinical Immunology and Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
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Minkiewicz P, Darewicz M, Iwaniak A, Sokołowska J, Starowicz P, Bucholska J, Hrynkiewicz M. Common Amino Acid Subsequences in a Universal Proteome--Relevance for Food Science. Int J Mol Sci 2015; 16:20748-73. [PMID: 26340620 PMCID: PMC4613229 DOI: 10.3390/ijms160920748] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/18/2015] [Accepted: 08/24/2015] [Indexed: 02/06/2023] Open
Abstract
A common subsequence is a fragment of the amino acid chain that occurs in more than one protein. Common subsequences may be an object of interest for food scientists as biologically active peptides, epitopes, and/or protein markers that are used in comparative proteomics. An individual bioactive fragment, in particular the shortest fragment containing two or three amino acid residues, may occur in many protein sequences. An individual linear epitope may also be present in multiple sequences of precursor proteins. Although recent recommendations for prediction of allergenicity and cross-reactivity include not only sequence identity, but also similarities in secondary and tertiary structures surrounding the common fragment, local sequence identity may be used to screen protein sequence databases for potential allergens in silico. The main weakness of the screening process is that it overlooks allergens and cross-reactivity cases without identical fragments corresponding to linear epitopes. A single peptide may also serve as a marker of a group of allergens that belong to the same family and, possibly, reveal cross-reactivity. This review article discusses the benefits for food scientists that follow from the common subsequences concept.
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Affiliation(s)
- Piotr Minkiewicz
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Małgorzata Darewicz
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Anna Iwaniak
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Jolanta Sokołowska
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Piotr Starowicz
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Justyna Bucholska
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
| | - Monika Hrynkiewicz
- Department of Food Biochemistry, University of Warmia and Mazury in Olsztyn, Plac Cieszyński 1, Olsztyn-Kortowo 10-726, Poland.
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Pomés A, Chruszcz M, Gustchina A, Wlodawer A. Interfaces between allergen structure and diagnosis: know your epitopes. Curr Allergy Asthma Rep 2015; 15:506. [PMID: 25750181 DOI: 10.1007/s11882-014-0506-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Allergy diagnosis is based on the patient's clinical history and can be strengthened by tests that confirm the origin of sensitization. In the past 25 years, these tests have evolved from the exclusive in vivo or in vitro use of allergen extracts, to complementary molecular-based diagnostics that rely on in vitro measurements of IgE reactivity to individual allergens. For this to occur, an increase in our understanding of the molecular structure of allergens, largely due to the development of technologies such as molecular cloning and expression of recombinant allergens, X-ray crystallography, or nuclear magnetic resonance (NMR), has been essential. New in vitro microarray or multiplex systems are now available to measure IgE against a selected panel of purified natural or recombinant allergens. The determination of the three-dimensional structure of allergens has facilitated detailed molecular studies, including the analysis of antigenic determinants for diagnostic purposes.
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Affiliation(s)
- Anna Pomés
- Basic Research, Indoor Biotechnologies, Inc., 1216 Harris Street, Charlottesville, VA, 22903, USA,
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Guan X, Noble KA, Tao Y, Roux KH, Sathe SK, Young NL, Marshall AG. Epitope mapping of 7S cashew antigen in complex with antibody by solution-phase H/D exchange monitored by FT-ICR mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2015; 50:812-819. [PMID: 26169135 DOI: 10.1002/jms.3589] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 02/12/2015] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
The potential epitope of a recombinant food allergen protein, cashew Ana o 1, reactive to monoclonal antibody, mAb 2G4, has been mapped by solution-phase amide backbone H/D exchange (HDX) monitored by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Purified mAb 2G4 was incubated with recombinant Ana o 1 (rAna o 1) to form antigen:monoclonal antibody (Ag:mAb) complexes. Complexed and uncomplexed (free) rAna o 1 were then subjected to HDX-MS analysis. Five regions protected from H/D exchange upon mAb binding are identified as potential conformational epitope-contributing segments.
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Affiliation(s)
- Xiaoyan Guan
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310, USA
| | - Kyle A Noble
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Yeqing Tao
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL, 32306, USA
| | - Kenneth H Roux
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Shridhar K Sathe
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, 32306, USA
| | - Nicolas L Young
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310, USA
| | - Alan G Marshall
- National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, FL, 32310, USA
- Department of Chemistry and Biochemistry, Florida State University, 95 Chieftain Way, Tallahassee, FL, 32306, USA
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Bernard H, Guillon B, Drumare MF, Paty E, Dreskin SC, Wal JM, Adel-Patient K, Hazebrouck S. Allergenicity of peanut component Ara h 2: Contribution of conformational versus linear hydroxyproline-containing epitopes. J Allergy Clin Immunol 2014; 135:1267-74.e1-8. [PMID: 25483599 DOI: 10.1016/j.jaci.2014.10.025] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 10/03/2014] [Accepted: 10/06/2014] [Indexed: 10/24/2022]
Abstract
BACKGROUND The 2S-albumin Ara h 2 is the most potent peanut allergen and a good predictor of clinical reactivity in allergic children. Posttranslational hydroxylation of proline residues occurs in DPYSP(OH)S motifs, which are repeated 2 or 3 times in different isoforms. OBJECTIVES We investigated the effect of proline hydroxylation on IgE binding and the relative contributions of linear and conformational epitopes to Ara h 2 allergenicity. METHODS Peptides containing DPYSP(OH)S motifs were synthesized. A recombinant variant of Ara h 2 without DPYSP(OH)S motifs was generated by means of deletion mutagenesis. IgE reactivity of 18 French and 5 American patients with peanut allergy toward synthetic peptides and recombinant allergens was assessed by using IgE-binding inhibition assays and degranulation tests of humanized rat basophilic leukemia cells. RESULTS Hydroxyproline-containing peptides exhibited an IgE-binding activity equivalent to that of the unfolded Ara h 2. In contrast, corresponding peptides without hydroxyprolines displayed a very weak IgE-binding capacity. Despite removal of the DPYSP(OH)S motifs, the deletion variant still displayed Ara h 2 conformational epitopes. The IgE-binding capacity of Ara h 2 was then recapitulated with an equimolar mixture of a hydroxylated peptide and the deletion variant. Hydroxylated peptides of 15 and 27 amino acid residues were also able to trigger cell degranulation. CONCLUSIONS Sensitization toward linear and conformational epitopes of Ara h 2 is variable among patients with peanut allergy. Optimal IgE binding to linear epitopes of Ara h 2 requires posttranslational hydroxylation of proline residues. The absence of hydroxyprolines could then affect the accuracy of component-resolved diagnostics by using rAra h 2.
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Affiliation(s)
- Hervé Bernard
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Blanche Guillon
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Marie-Françoise Drumare
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Evelyne Paty
- Université Paris Descartes-Assistance Publique des Hôpitaux de Paris, Hôpital Necker Enfants Malades, Paris, France
| | - Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, Colo
| | - Jean-Michel Wal
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Karine Adel-Patient
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France
| | - Stéphane Hazebrouck
- INRA, UR 496, Unité d'Immuno-Allergie Alimentaire, Jouy-en-Josas, France; CEA, iBiTecS/Service de Pharmacologie et d'Immunoanalyse, Gif-sur-Yvette, France.
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Chlorovirus Skp1-binding ankyrin repeat protein interplay and mimicry of cellular ubiquitin ligase machinery. J Virol 2014; 88:13798-810. [PMID: 25253343 DOI: 10.1128/jvi.02109-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The ubiquitin-proteasome system is targeted by many viruses that have evolved strategies to redirect host ubiquitination machinery. Members of the genus Chlorovirus are proposed to share an ancestral lineage with a broader group of related viruses, nucleo-cytoplasmic large DNA viruses (NCLDV). Chloroviruses encode an Skp1 homolog and ankyrin repeat (ANK) proteins. Several chlorovirus-encoded ANK repeats contain C-terminal domains characteristic of cellular F-boxes or related NCLDV chordopox PRANC (pox protein repeats of ankyrin at C-terminal) domains. These observations suggested that this unique combination of Skp1 and ANK repeat proteins might form complexes analogous to the cellular Skp1-Cul1-F-box (SCF) ubiquitin ligase complex. We identified two ANK proteins from the prototypic chlorovirus Paramecium bursaria chlorella virus-1 (PBCV-1) that functioned as binding partners for the virus-encoded Skp1, proteins A682L and A607R. These ANK proteins had a C-terminal Skp1 interactional motif that functioned similarly to cellular F-box domains. A C-terminal motif of ANK protein A682L binds Skp1 proteins from widely divergent species. Yeast two-hybrid analyses using serial domain deletion constructs confirmed the C-terminal localization of the Skp1 interactional motif in PBCV-1 A682L. ANK protein A607R represents an ANK family with one member present in all 41 sequenced chloroviruses. A comprehensive phylogenetic analysis of these related ANK and viral Skp1 proteins suggested partnered function tailored to the host alga or common ancestral heritage. Here, we show protein-protein interaction between corresponding family clusters of virus-encoded ANK and Skp1 proteins from three chlorovirus types. Collectively, our results indicate that chloroviruses have evolved complementing Skp1 and ANK proteins that mimic cellular SCF-associated proteins. IMPORTANCE Viruses have evolved ways to direct ubiquitination events in order to create environments conducive to their replication. As reported in the manuscript, the large chloroviruses encode several components involved in the SCF ubiquitin ligase complex including a viral Skp1 homolog. Studies on how chloroviruses manipulate their host algal ubiquitination system will provide insights toward viral protein mimicry, substrate recognition, and key interactive domains controlling selective protein degradation. These findings may also further understanding of the evolution of other large DNA viruses, like poxviruses, that are reported to share the same monophyly lineage as chloroviruses.
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Cell-based immunological assay: complementary applications in evaluating the allergenicity of foods with FAO/WHO guidelines. Food Res Int 2014. [DOI: 10.1016/j.foodres.2014.04.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Abstract
Peanut seeds are currently widely used as source of human food ingredients in the United States of America and in European countries due to their high quality protein and oil content. This article describes the classification and molecular biology of peanut seed allergens with particular reference to their cross-reactivities. Currently, the IUIS allergen nomenclature subcommittee accepts 12 peanut allergens. Two allergens belong to the cupin and four to the prolamin superfamily, and six are distributed among profilins, Bet v 1-like proteins, oleosins, and defensins. Clinical observations frequently report an association of peanut allergy with allergies to legumes, tree nuts, seeds, fruits and pollen. Molecular cross-reactivity has been described between members of the Bet v 1-like proteins, the non-specific lipid transfer proteins, and the profilins. This review also addresses the less well-studied cross-reactivity between cupin and prolamin allergens of peanuts and of other plant food sources and the recently discovered cross-reactivity between peanut allergens of unrelated protein families.
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Gepp B, Lengger N, Bublin M, Hemmer W, Breiteneder H, Radauer C. Chimeras of Bet v 1 and Api g 1 reveal heterogeneous IgE responses in patients with birch pollen allergy. J Allergy Clin Immunol 2014; 134:188-94. [PMID: 24529686 PMCID: PMC4085476 DOI: 10.1016/j.jaci.2013.12.1073] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 12/03/2013] [Accepted: 12/19/2013] [Indexed: 02/05/2023]
Abstract
BACKGROUND Characterization of IgE-binding epitopes of allergens and determination of their patient-specific relevance is crucial for the diagnosis and treatment of allergy. OBJECTIVE We sought to assess the contribution of specific surface areas of the major birch pollen allergen Bet v 1.0101 to binding IgE of individual patients. METHODS Four distinct areas of Bet v 1 representing in total 81% of its surface were grafted onto the scaffold of its homolog, Api g 1.0101, to yield the chimeras Api-Bet-1 to Api-Bet-4. The chimeras were expressed in Escherichia coli and purified. IgE binding of 64 sera from Bet v 1-sensitized subjects with birch pollen allergy was determined by using direct ELISA. Specificity was assessed by means of inhibition ELISA. RESULTS rApi g 1.0101, Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4 bound IgE from 44%, 89%, 80%, 78%, and 48% of the patients, respectively. By comparing the amount of IgE binding to the chimeras and to rApi g 1.0101, 81%, 70%, 75%, and 45% of the patients showed significantly enhanced IgE binding to Api-Bet-1, Api-Bet-2, Api-Bet-3, and Api-Bet-4, respectively. The minority (8%) of the sera revealed enhanced IgE binding exclusively to a single chimera, whereas 31% showed increased IgE binding to all 4 chimeras compared with rApi g 1.0101. The chimeras inhibited up to 70% of IgE binding to rBet v 1.0101, confirming the specific IgE recognition of the grafted regions. CONCLUSION The Bet v 1-specific IgE response is polyclonal, and epitopes are spread across the entire Bet v 1 surface. Furthermore, the IgE recognition profile of Bet v 1 is highly patient specific.
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Affiliation(s)
- Barbara Gepp
- Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Nina Lengger
- Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | - Merima Bublin
- Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Heimo Breiteneder
- Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.
| | - Christian Radauer
- Department of Pathophysiology and Allergy Research, Center for Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria
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Kulis M. Carrying peptides towards the ideal allergen-specific immunotherapy. Clin Exp Allergy 2014; 44:157-9. [DOI: 10.1111/cea.12249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- M. Kulis
- Department of Pediatrics; School of Medicine; University of North Carolina at Chapel Hill; Chapel Hill NC USA
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Kamath SD, Rahman AMA, Voskamp A, Komoda T, Rolland JM, O'Hehir RE, Lopata AL. Effect of heat processing on antibody reactivity to allergen variants and fragments of black tiger prawn: A comprehensive allergenomic approach. Mol Nutr Food Res 2014; 58:1144-55. [PMID: 24420734 DOI: 10.1002/mnfr.201300584] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2013] [Revised: 11/07/2013] [Accepted: 11/27/2013] [Indexed: 11/08/2022]
Abstract
SCOPE Prawn allergy is one of the leading causes of IgE-mediated hypersensitivity to food. Alterations of IgE-antibody reactivity to prawn allergens due to thermal processing are not fully understood. The aim of this study was to analyze the impact of heating on prawn allergens using a comprehensive allergenomic approach. METHODS AND RESULTS Proteins from raw and heat-processed black tiger prawn (Penaeus monodon) extracts as well as recombinant tropomyosin (rPen m1) were analyzed by SDS-PAGE and immunoblotting using sera from 16 shellfish allergic patients. IgE antibody binding proteins were identified by advanced mass spectroscopy, characterized by molecular structure analysis and their IgE reactivity compared among the prepared black tiger prawn extracts. Heat processing enhanced the overall patient IgE binding to prawn extracts and increased recognition of a number of allergen variants and fragments of prawn allergens. Allergens identified were tropomyosin, myosin light chain, sarcoplasmic calcium binding protein, and putative novel allergens including triose phosphate isomerase, aldolase, and titin. CONCLUSION Seven allergenic proteins are present in prawns, which are mostly heat-stable and form dimers or oligomers. Thermal treatment enhanced antibody reactivity to prawn allergens as well as fragments and should be considered in the diagnosis of prawn allergy and detection of crustacean allergens in processed food.
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Affiliation(s)
- Sandip D Kamath
- School of Pharmacy and Molecular Science, Centre for Biodiscovery and Molecular Development of Therapeutics, James Cook University, Townsville, Queensland, Australia
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Impact of heat processing on the detection of the major shellfish allergen tropomyosin in crustaceans and molluscs using specific monoclonal antibodies. Food Chem 2013; 141:4031-9. [DOI: 10.1016/j.foodchem.2013.06.105] [Citation(s) in RCA: 108] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 06/02/2013] [Accepted: 06/24/2013] [Indexed: 11/21/2022]
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Benedé S, López-Expósito I, Giménez G, Grishina G, Bardina L, Sampson HA, Molina E, López-Fandiño R. In vitro digestibility of bovine β-casein with simulated and human oral and gastrointestinal fluids. Identification and IgE-reactivity of the resultant peptides. Food Chem 2013; 143:514-21. [PMID: 24054275 DOI: 10.1016/j.foodchem.2013.07.110] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Revised: 07/16/2013] [Accepted: 07/20/2013] [Indexed: 01/03/2023]
Abstract
Stability during digestion is considered an important feature in determining the allergenicity of food proteins. This study aimed to provide an immunological characterisation of the digestion products of the major cow's milk allergen β-casein (β-CN) produced by in vitro orogastrointestinal hydrolysis with simulated and human digestive fluids. β-CN was unaffected by oral digestion, but quickly broke down during the early stages of gastric digestion. The degradation with human fluids was faster than that with commercial enzymes. There were similarities in the peptide patterns of the hydrolysates produced in both models, showing 20 peptides in common after gastric digestion. After gastroduodenal digestion, the human fluids gave less numerous and shorter peptides. The IgE binding of most of the individual sera used to the hydrolysates produced with simulated and human fluids increased at the end of the gastric phase and decreased when the duodenal digestion was completed. Two IgE-binding synthetic peptides: β-CN (57-68) and β-CN (82-93), which matched fragments released by β-CN following in vitro digestion with simulated and human fluids, consisted of the most immunoreactive areas of the protein. The similarities found between the in vitro simulated digestion system and that using human digestive fluids suggest that the former would provide a reasonably good estimation of the potential allergenicity of protein digests.
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Affiliation(s)
- Sara Benedé
- Instituto de Investigación en Ciencias de la Alimentación (CIAL), CSIC-UAM, Madrid, Spain
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Zhang Q, Noble KA, Mao Y, Young NL, Sathe SK, Roux KH, Marshall AG. Rapid screening for potential epitopes reactive with a polycolonal antibody by solution-phase H/D exchange monitored by FT-ICR mass spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1016-1025. [PMID: 23681851 DOI: 10.1007/s13361-013-0644-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Revised: 04/03/2013] [Accepted: 04/03/2013] [Indexed: 06/02/2023]
Abstract
The potential epitopes of a recombinant food allergen protein, cashew Ana o 2, reactive to polyclonal antibodies, were mapped by solution-phase amide backbone H/D exchange (HDX) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ana o 2 polyclonal antibodies were purified in the serum from a goat immunized with cashew nut extract. Antibodies were incubated with recombinant Ana o 2 (rAna o 2) to form antigen:polyclonal antibody (Ag:pAb) complexes. Complexed and uncomplexed (free) rAna o 2 were then subjected to HDX-MS analysis. Four regions protected from H/D exchange upon pAb binding are identified as potential epitopes and mapped onto a homologous model.
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Affiliation(s)
- Qian Zhang
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA
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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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Myrset HR, Fæste CK, Kristiansen PE, Dooper MM. Mapping of the Immunodominant Regions of Shrimp Tropomyosin Pan b 1 by Human IgE-Binding and IgE Receptor Crosslinking Studies. Int Arch Allergy Immunol 2013; 162:25-38. [DOI: 10.1159/000350791] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 03/15/2013] [Indexed: 11/19/2022] Open
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Starkl P, Felix F, Krishnamurthy D, Stremnitzer C, Roth-Walter F, Prickett SR, Voskamp AL, Willensdorfer A, Szalai K, Weichselbaumer M, O'Hehir RE, Jensen-Jarolim E. An unfolded variant of the major peanut allergen Ara h 2 with decreased anaphylactic potential. Clin Exp Allergy 2013. [PMID: 23181796 DOI: 10.1111/cea.12031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Peanut allergy causes severe type 1 hypersensitivity reactions and conventional immunotherapy against peanut allergy is associated with a high risk of anaphylaxis. OBJECTIVE Our current study reports proof of concept experiments on the safety of a stably denatured variant of the major peanut allergen Ara h 2 for immunotherapy. We determined the impact of structure loss of Ara h 2 on its IgE binding and basophil degranulation capacity, T cell reactivity as well as anaphylactic potential. METHODS The secondary structure of untreated and reduced/alkylated Ara h 2 variants was determined by circular dichroism spectroscopy. We addressed human patient IgE binding to Ara h 2 by ELISA and Western blot experiments. RBL-SX38 cells were used to test the degranulation induced by untreated and reduced/alkylated Ara h 2. We assessed the anaphylactic potential of Ara h 2 variants by challenge of sensitized BALB/c mice. T cell reactivity was investigated using human Ara h 2-specific T cell lines and splenocytes isolated from sensitized mice. RESULTS Reduction/alkylation of Ara h 2 caused a decrease in IgE binding capacity, basophil degranulation and anaphylactic potential in vivo. However, the human T cell response to reduced/alkylated and untreated Ara h 2 was comparable. Mouse splenocytes showed higher metabolic activity upon stimulation with reduced/alkylated Ara h 2 and released similar IL-4, IL-13 and IFNγ levels upon treatment with either Ara h 2 variant. CONCLUSIONS AND CLINICAL RELEVANCE Reduced/alkylated Ara h 2 might be a safer alternative than native Ara h 2 for immunotherapeutic treatment of peanut allergic patients.
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Affiliation(s)
- P Starkl
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
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Transport across Caco-2 monolayers of peptides arising from in vitro digestion of bovine milk proteins. Food Chem 2013; 139:203-12. [PMID: 23561097 DOI: 10.1016/j.foodchem.2013.01.063] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2012] [Revised: 01/05/2013] [Accepted: 01/08/2013] [Indexed: 11/22/2022]
Abstract
The entire panel of peptides produced from caseins (CN) and whey proteins (WP) that survive in vitro sequential gastro-pancreatic digestion and translocate across monolayers of Caco-2 cells, used as a model of the intestinal epithelium, has been characterised by HPLC and mass spectrometry. Among the milk-derived bioactive peptides, only minor amounts of mono-phosphorylated peptides arising from αs1- and β-CN were detected. The absorption behaviour of two resistant β-lactoglobulin (β-Lg) domains, β-Lg 125-135 and β-Lg 40-60, was studied in detail using synthetic peptides. The IgE-binding properties of the digests recovered from the apical and basolateral monolayer compartments were evaluated by dot-blot, using the sera of milk allergic children (N=5). Outcomes indicated β-Lg 127-135 as a possible "immune sensitising factor"in vivo. The almost complete loss of the IgE-affinity of CN and WP after digestion points out the need to design in vivo experiments to track the metabolic fate of dietary proteins.
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Zhuang Y, Durrani S, Hodges BDM, Dreskin SC, Chen X. Expression of recombinant Ara h 6 in Pichia pastoris but not in Escherichia coli preserves allergic effector function and allows assessment of specific mutations. Mol Nutr Food Res 2012; 56:986-95. [PMID: 22707273 DOI: 10.1002/mnfr.201100827] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
SCOPE Ara h 6 has recently been recognized as an important peanut allergen. Recombinant allergens have been used for analysis of IgE binding, but have not been used to analyze the allergic effector activity that is more relevant to allergic reactions. METHODS AND RESULTS Ara h 6 was expressed as a recombinant protein in both Escherichia coli and Pichia pastoris (rAra h 6-E. coli and rAra h 6-Pichia, respectively). Effector activity was assayed by measuring degranulation of RBL SX-38 cells sensitized with IgE from patients with severe peanut allergy. Compared to native Ara h 6 (nAra h 6), rAra h 6-Pichia had intact effector function whereas rAra h 6-E. coli had significantly reduced function. The lower effector activity in rAra h 6-E. coli compared to nAra h 6 and rAra h 6-Pichia did not appear to be due to differences in posttranslational modifications (analyzed by mass spectrometry and staining for carbohydrates) and may be due to subtle alteration(s) of folding seen on CD analysis and on nonreduced gels. Finally, we introduced point mutations in four important IgE-binding linear epitopes of Ara h 6 and found dramatically reduced allergic effector activity. CONCLUSION Our studies demonstrate the utility of fully functional rAra h 6-Pichia as a starting point for analysis of specific mutations that adversely affect allergic effector function.
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Affiliation(s)
- Yonghua Zhuang
- Department of Medicine, Division of Allergy and Clinical Immunology, University of Colorado Denver, Aurora, CO 80045, USA
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