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Cossette BJ, Shetty S, Issah LA, Collier JH. Self-Assembling Allergen Vaccine Platform Raises Therapeutic Allergen-Specific IgG Responses without Induction of Systemic Allergic Responses. ACS Biomater Sci Eng 2024; 10:1819-1829. [PMID: 38366973 PMCID: PMC11382287 DOI: 10.1021/acsbiomaterials.3c01945] [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] [Indexed: 02/19/2024]
Abstract
Allergen immunotherapies are often successful at desensitizing allergic patients but can require life-long dosing and suffer from frequent adverse events including instances of systemic anaphylaxis, leading to poor patient compliance and high cost. Allergen vaccines, in turn, can generate more durable immunological allergen desensitization with far fewer doses. However, like immunotherapies, allergen vaccines are often highly reactogenic in allergic patients, hampering their use in therapeutic settings. In this work, we utilize a peptide-based self-assembling nanofiber platform to design allergen vaccines against allergen B-cell epitopes that do not elicit systemic anaphylaxis when administered subcutaneously to allergic mice. We show that, in contrast to protein vaccines, nanofiber vaccines prevent leakage of allergen material into the vascular compartment, a feature that likely underpins their reduced systemic reactogenicity. Further, we show that our allergen vaccine platform elicits therapeutic IgG antibody responses capable of desensitizing allergic mice to allergen-induced Type I hypersensitivity reactions. Finally, we have demonstrated a proof-of-concept for the therapeutic potential of nanofiber-based peanut allergen vaccines directed against peanut allergen-derived epitopes.
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Affiliation(s)
- Benjamin J Cossette
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Shamitha Shetty
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Luqman A Issah
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
| | - Joel H Collier
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States
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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] [Key Words] [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
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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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Nesbit JB, Schein CH, Braun BA, Gipson SAY, Cheng H, Hurlburt BK, Maleki SJ. Epitopes with similar physicochemical properties contribute to cross reactivity between peanut and tree nuts. Mol Immunol 2020; 122:223-231. [PMID: 32442779 DOI: 10.1016/j.molimm.2020.03.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 02/11/2020] [Accepted: 03/26/2020] [Indexed: 12/28/2022]
Abstract
Many individuals with peanut (PN) allergy have severe reactions to tree nuts (TN) such as walnuts or cashews. Although allergenic proteins in TN and PN have overall low identity, they share discrete sequences similar in physicochemical properties (PCP) to known IgE epitopes. Here, PCP-consensus peptides (cp, 13 aa and 31 aa) were identified from an alignment of epitope rich regions of walnut vicilin, Jug r 2, leader sequence (J2LS) and cross-reactive epitopes in the 2S albumins of peanut and synthesized. A peptide similarity search in the Structural Database of Allergenic Proteins (SDAP) revealed a network of peptides similar (low property distance, PD) to the 13 aa cp (13cp) in many different plant allergens. Peptides similar to the 13cp in PN and TN allergens bound IgE from sera of patients allergic to PN and TN in peptide microarray analysis. The 13cp was used to produce a rabbit consensus peptide antibody (cpAB) that detected proteins containing repeats similar to the 13cp in western blots of various nut extracts, in which reactive proteins were identified by mass spectrometry. The cpAB bound more specifically to allergens and nut extracts containing multiple repeats similar to the 13 cp, such as almond (Pru du 6), peanut (Ara h 2) and walnut (Jug r 2). IgE binding to various nut extracts is inhibited by recombinant J2LS sequence and synthetic 31cp. Thus, several repeated sequences similar to the 13cp are bound by IgE. Multiple similar repeats in several allergens could account for reaction severity and clinically relevant cross-reactivity to PN and TN. These findings may help improve detection, diagnostic, and therapeutic tools.
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Affiliation(s)
- Jacqueline B Nesbit
- Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States
| | - Catherine H Schein
- Department of Biochemistry and Molecular Biology, Institute for Human Infection and Immunity, University of Texas Medical Branch at Galveston (UTMB), TX, United States.
| | - Benjamin A Braun
- Department of Computer Science, Stanford University, United States
| | - Stephen A Y Gipson
- Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States
| | - Hsiaopo Cheng
- Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States
| | - Barry K Hurlburt
- Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States
| | - Soheila J Maleki
- Dept of Agriculture-Agricultural Research Service-Southern Regional Research Center (USDA-ARS-SRRC), New Orleans, LA, United States.
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Dreskin SC, Germinaro M, Reinhold D, Chen X, Vickery BP, Kulis M, Burks AW, Negi SS, Braun W, Chambliss JM, Eglite S, McNulty CMG. IgE binding to linear epitopes of Ara h 2 in peanut allergic preschool children undergoing oral Immunotherapy. Pediatr Allergy Immunol 2019; 30:817-823. [PMID: 31437325 PMCID: PMC6906227 DOI: 10.1111/pai.13117] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/10/2019] [Accepted: 07/31/2019] [Indexed: 02/06/2023]
Abstract
BACKGROUND For patients with peanut allergy, there are currently no methods to predict who will develop sustained unresponsiveness (SU) after oral immunotherapy (OIT). OBJECTIVE Assess IgE binding to peanut (PN), Ara h 2, and specific linear epitopes of Ara h 2 as predictors of the important clinical parameters: eliciting dose threshold and attainment of SU following OIT. METHODS Samples and clinical data were collected from children undergoing OIT. PN- and Ara h 2-sIgE were quantified by ImmunoCAP® . IgE binding to linear peptides of Ara h 2 and Ara h 6 was measured with peptide microarrays. RESULTS Values of PN-sIgE correlated with eliciting dose (P = .001) and with a higher likelihood of achieving SU (P < .0001), but these relationships were lost at higher values for PN-sIgE (≥14 kIU for eliciting dose and ≥35 kIU/L for SU). In subjects with PN-sIgE ≥ 14 kIU/L, binding of IgE to epitopes 5 and 6 of Ara h 2 was associated with a lower eliciting dose at baseline challenge (P < .001; Pc < .02). In subjects with PN-sIgE ≥ 35 kIU/L, a combined model of IgE binding to epitopes 1, 5 and 6 with PN-sIgE was highly predictive of attainment of SU (AUC of 0.86; P = .0067). CONCLUSION In young patients with peanut allergy, measurement of PN-sIgE and IgE binding to specific linear epitopes of Ara h 2 in baseline samples may allow stratification of patients regarding sensitivity to challenge and outcome of OIT.
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Affiliation(s)
- Stephen C Dreskin
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
| | | | | | - Xueni Chen
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
| | - Brian P Vickery
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Michael Kulis
- Division of Allergy and Immunology, Department of Pediatrics, University of North Carolina-Chapel Hill, NC, USA
| | - A Wesley Burks
- Division of Allergy and Immunology, Department of Pediatrics, University of North Carolina-Chapel Hill, NC, USA
| | - 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, USA
| | - Werner Braun
- Sealy Center for Structural Biology and Molecular Biophysics, Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA
| | - Jeffery M Chambliss
- Division of Allergy and Immunology, Department of Pediatrics, University of Texas, Dallas, TX, USA
| | - Spodra Eglite
- Division of Allergy and Clinical Immunology, Departments of Medicine and Immunology, University of Colorado Denver, Aurora, CO, USA
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Deak PE, Vrabel MR, Kiziltepe T, Bilgicer B. Determination of Crucial Immunogenic Epitopes in Major Peanut Allergy Protein, Ara h2, via Novel Nanoallergen Platform. Sci Rep 2017; 7:3981. [PMID: 28638052 PMCID: PMC5479826 DOI: 10.1038/s41598-017-04268-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 05/10/2017] [Indexed: 12/16/2022] Open
Abstract
Current methods for detection and diagnosis of allergies do not provide epitope specific immunogenic information and hence lack critical information that could aid in the prediction of clinical responses. To address this issue, we developed a nanoparticle based platform, called nanoallergens that enable multivalent display of potential allergy epitopes for determining the immunogenicity of each IgE binding epitope. By synthesizing nanoallergens that present various epitopes from the major peanut allergen, Ara h2, we directly determined the immunogenicity of each epitope, alone and in combination with other epitopes, using patient sera. This information provided insights on which epitopes are most critical for physiological responses to Ara h2 and revealed the importance of both high and low affinity epitopes for allergic responses. We anticipate the nanoallergen platform to be used to provide information regarding allergic reactions and therefore potentially aid in more accurate diagnosis and design of personalized treatment options.
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Affiliation(s)
- Peter E Deak
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Maura R Vrabel
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Tanyel Kiziltepe
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA
- Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Basar Bilgicer
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN, 46556, USA.
- Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN, 46556, USA.
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN, 46556, USA.
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7
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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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8
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Peanut protein extraction conditions strongly influence yield of allergens Ara h 1 and 2 and sensitivity of immunoassays. Food Chem 2016; 221:335-344. [PMID: 27979211 DOI: 10.1016/j.foodchem.2016.10.063] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 09/12/2016] [Accepted: 10/13/2016] [Indexed: 11/21/2022]
Abstract
The clinical importance of peanut (Arachis hypogaea) allergies demands standardized allergen extraction protocols. We determined the effectiveness of common extraction conditions (20 buffers, defatting reagents, extraction time/temperatures, processing, extraction repeats) on crude protein and Ara h 1 and 2 yields. Despite similar 1D-gel profiles, defatting with n-hexane resulted in significantly higher yields of crude protein, Ara h 1, and Ara h 2 than with diethyl ether. The yields were affected by the composition and pH of the extraction buffers and other conditions, but crude protein yield did not always correlate with Ara h 1 and 2 yields. Denaturants, reducing agents, acidic buffers, and thermal processing of peanuts perturbed allergen quantification in ELISAs, probably via exposure of additional epitopes. Allergen detection in 2D-Western blots with PBS resulted in greater sensitivity than with TBS or Tris. We recommend that allergen extraction conditions be selected based on the research question being investigated.
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Guillon B, Bernard H, Drumare MF, Hazebrouck S, Adel-Patient K. Heat processing of peanut seed enhances the sensitization potential of the major peanut allergen Ara h 6. Mol Nutr Food Res 2016; 60:2722-2735. [PMID: 27374416 PMCID: PMC5213772 DOI: 10.1002/mnfr.201500923] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 05/27/2016] [Accepted: 06/08/2016] [Indexed: 11/11/2022]
Abstract
SCOPE Processing of food has been shown to impact IgE binding and functionality of food allergens. In the present study, we investigated the impact of heat processing on the sensitization capacity of Ara h 6, a major peanut allergen and one of the most potent elicitors of the allergic reaction. METHODS AND RESULTS Peanut extracts obtained from raw or heat-processed peanut and some fractions thereof were biochemically and immunochemically characterized. These extracts/fractions, purified Ara h 6, or recombinant Ara h 6 including Ara h 6 mutants lacking disulfide bridges were used in in vitro digestion tests and mouse models of experimental sensitization. Peanut roasting led to the formation of complexes of high molecular weight, notably between Ara h 6 and Ara h 1, which supported the induction of IgE specific to native Ara h 6. On the contrary, a fraction containing free monomeric 2S albumins or purified native Ara h 6 displayed no intrinsic allergenicity. In addition to complex formation, heat denaturation and/or partial destabilization enhanced Ara h 6 immunogenicity and increased its sensitivity to digestion. CONCLUSION These results suggest that sensitization potency and IgE binding capacity can be supported by different structures, modified and/or produced during food processing in interaction with other food constituents.
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Affiliation(s)
- Blanche Guillon
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Hervé Bernard
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Marie-Françoise Drumare
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Stéphane Hazebrouck
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Karine Adel-Patient
- UMR CEA-INRA Service de Pharmacologie et d'Immunoanalyse, Université Paris-Saclay, Gif-sur-Yvette, France
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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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11
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Allergenicity attributes of different peanut market types. Food Chem Toxicol 2016; 91:82-90. [DOI: 10.1016/j.fct.2016.02.016] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 01/28/2016] [Accepted: 02/19/2016] [Indexed: 11/20/2022]
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12
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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: 58] [Impact Index Per Article: 6.4] [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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13
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van Hoffen E, van der Kleij HPM, den Hartog Jager CF, van Doorn WA, Knol EF, Opstelten DJ, Koppelman SJ, Knulst AC. Chemical modification of peanut conglutin reduces IgE reactivity but not T cell reactivity in peanut-allergic patients. Clin Exp Allergy 2015; 44:1558-66. [PMID: 24717146 DOI: 10.1111/cea.12319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 02/15/2014] [Accepted: 03/24/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Specific immunotherapy for peanut allergy is associated with significant side-effects. Chemically modified allergens may provide a safer alternative. OBJECTIVE This study aimed to analyse the immunogenicity and allergenicity of modified peanut conglutin. METHODS Native peanut conglutin and two modifications thereof were generated (RA and RAGA). Conglutin-specific T cell lines from 11 peanut-allergic patients were analysed for proliferation and cytokine production. Sera from 14 patients were analysed for IgE/IgG1/IgG4 binding by immunoblot and ELISA. IgE reactivity was analysed by direct and indirect basophil activation test (BAT), in presence and absence of patient plasma or CD32-blocking antibodies. RESULTS T cell proliferation to RA was unchanged, and proliferation to RAGA was reduced compared to native conglutin. Cytokine profiles remained unchanged. IgE, IgG1 and IgG4 binding to RA and RAGA was significantly reduced. In the direct BAT, the relative potency of modified conglutin was decreased in 67% and increased/similar in 33% of the patients. In the indirect BAT, RA and RAGA were 10-100 times less potent than native conglutin. Addition of plasma to the indirect BAT increased the relative potency of modified conglutin in patients with high peanut-specific IgG levels. This was mediated via blocking of the response to native conglutin, most likely by soluble IgG, and not via CD32. CONCLUSION AND CLINICAL RELEVANCE Chemical modification of peanut conglutin by RA retains immunogenicity and reduces allergenicity and may be a promising approach for development of a curative treatment for peanut allergy. In a subgroup of patients, where the reactivity of native conglutin is already partially blocked by IgG, the effect of the modification of conglutin is less pronounced.
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Affiliation(s)
- E van Hoffen
- Department of Dermatology/Allergology, University Medical Center Utrecht, Utrecht, The Netherlands
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14
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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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15
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Handlogten MW, Deak PE, Bilgicer B. Two-allergen model reveals complex relationship between IgE crosslinking and degranulation. ACTA ACUST UNITED AC 2014; 21:1445-51. [PMID: 25308278 DOI: 10.1016/j.chembiol.2014.08.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 08/16/2014] [Accepted: 08/20/2014] [Indexed: 11/16/2022]
Abstract
Allergy is an immune response to complex mixtures of multiple allergens, yet current models use a single synthetic allergen. Multiple allergens were modeled using two well-defined tetravalent allergens, each specific for a distinct IgE, thus enabling a systematic approach to evaluate the effect of each allergen and percentage of allergen-specific IgE on mast cell degranulation. We found the overall degranulation response caused by two allergens is additive for low allergen concentrations or low percent specific IgE, does not change for moderate allergen concentrations with moderate to high percent specific IgE, and is reduced for high allergen concentrations with moderate to high percent specific IgE. These results provide further evidence that supraoptimal IgE crosslinking decreases the degranulation response and establishes the two-allergen model as a relevant experimental system to elucidate mast cell degranulation mechanisms.
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Affiliation(s)
- Michael W Handlogten
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Peter E Deak
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Basar Bilgicer
- Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46556, USA; Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA; Advanced Diagnostics and Therapeutics, University of Notre Dame, Notre Dame, IN 46556, USA.
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16
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Mattison CP, Desormeaux WA, Wasserman RL, Yoshioka-Tarver M, Condon B, Grimm CC. Decreased immunoglobulin E (IgE) binding to cashew allergens following sodium sulfite treatment and heating. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:6746-6755. [PMID: 24926808 DOI: 10.1021/jf501117p] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cashew nut and other nut allergies can result in serious and sometimes life-threatening reactions. Linear and conformational epitopes within food allergens are important for immunoglobulin E (IgE) binding. Methods that disrupt allergen structure can lower IgE binding and lessen the likelihood of food allergy reactions. Previous structural and biochemical data have indicated that 2S albumins from tree nuts and peanuts are potent allergens, and that their structures are sensitive to strong reducing agents such as dithiothreitol. This study demonstrates that the generally regarded as safe (GRAS) compound sodium sulfite effectively disrupted the structure of the cashew 2S albumin, Ana o 3, in a temperature-dependent manner. This study also showed that sulfite is effective at disrupting the disulfide bond within the cashew legumin, Ana o 2. Immunoblotting and ELISA demonstrated that the binding of cashew proteins by rabbit IgG or IgE from cashew-allergic patients was markedly lowered following treatment with sodium sulfite and heating. The results indicate that incorporation of sodium sulfite, or other food grade reagents with similar redox potential, may be useful processing methods to lower or eliminate IgE binding to food allergens.
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Affiliation(s)
- Christopher P Mattison
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, New Orleans, Louisiana 70124, United States
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17
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Bernard H, Ah-Leung S, Drumare MF, Feraudet-Tarisse C, Verhasselt V, Wal JM, Créminon C, Adel-Patient K. Peanut allergens are rapidly transferred in human breast milk and can prevent sensitization in mice. Allergy 2014; 69:888-97. [PMID: 24773443 DOI: 10.1111/all.12411] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2014] [Indexed: 12/29/2022]
Abstract
BACKGROUND Food allergens have been evidenced in breast milk under physiological conditions, but the kinetic and the role of this passage in food allergies are still unclear. We then aimed to analyze the passage of peanut allergens in human breast milk and their allergenicity/immunomodulatory properties. METHODS Human breast milk was collected from two non-atopic peanut-tolerant mothers before and at different time points after ingestion of 30 g of commercial roasted peanut. Ara h 6, Ara h 6 immune complexes, and the IgE binding capacity of breast milk samples were measured using specific immunoassays. Their allergenic functionality was then assessed using cell-based assay. Finally, human breast milk obtained before or after peanut ingestion was administered intragastrically to BALB/c mice at different ages, and mice were further experimentally sensitized to peanut using cholera toxin. RESULTS Ara h 6 is detected as soon as 10 min after peanut ingestion, with peak values observed within the first hour after ingestion. The transfer is long-lasting, small quantities of peanut allergens being detected over a 24-h period. IgG-Ara h 6 and IgA-Ara h 6 immune complexes are evidenced, following a different kinetic of excretion than free allergens. Peanut allergens transferred in milk are IgE reactive and can induce an allergic reaction in vitro. However, administration of human breast milk to young mice, notably before weaning, does not lead to sensitization, but instead to partial oral tolerance. CONCLUSION The low quantities of immunologically active allergens transferred through breast milk may prevent instead of priming allergic sensitization to peanut.
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Affiliation(s)
- H. Bernard
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - S. Ah-Leung
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - M.-F. Drumare
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - C. Feraudet-Tarisse
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - V. Verhasselt
- EA 6302 Tolérance Immunitaire; Hôpital de l'Archet; Université de Nice Sophia-Antipolis; Nice France
| | - J.-M. Wal
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - C. Créminon
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
| | - K. Adel-Patient
- INRA; UR496 Unité d'Immuno-Allergie Alimentaire; Jouy-en-Josas France
- CEA; IBiTecS; Service de Pharmacologie et d'Immunoanalyse; Gif-sur-Yvette France
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18
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Mayorga C, Gomez F, Aranda A, Koppelman SJ, Diaz-Perales A, Blanca-López N, Blazquez AB, Blanca M, Torres MJ. Basophil response to peanut allergens in Mediterranean peanut-allergic patients. Allergy 2014; 69:964-8. [PMID: 24816395 DOI: 10.1111/all.12421] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2014] [Indexed: 11/30/2022]
Abstract
Ara h 1, Ara h 2, and Ara h 3 are important sensitizers in peanut allergy. Ara h 9 has also been shown to be relevant in the Mediterranean area. We evaluated the basophil response to peanut allergens and Pru p 3 in Mediterranean patients: Group 1, peanut and peach allergy; Group 2, peanut allergy and tolerance to peach; Group 3, peach allergy and tolerance to peanut; Group 4, nonallergic subjects that tolerate both peanut and peach. Compared to controls (Group 4), there was an increased basophil activation with Ara h 2 (P = 0.031) and Pru p 3 (P = 0.009) in Group 1 and with Ara h 1 (P = 0.016), Ara h 2 (P = 0.001), and Ara h 9 (P = 0.016) in Group 2. Importantly, only Ara h 2 showed an increased activation (P = 0.009) in Group 2 compared to Group 3. Ara h 2 is the best discriminating allergen for peanut allergy diagnosis in a Mediterranean population showing two patterns: patients also allergic to peach, responding to Ara h 2 and Pru p 3, and patients allergic only to peanut, responding to Ara h 1, Ara h 2, and Ara h 9.
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Affiliation(s)
- C. Mayorga
- Research Laboratory; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
- UGC Allergy; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
| | - F. Gomez
- UGC Allergy; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
| | - A. Aranda
- Research Laboratory; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
| | - S. J. Koppelman
- University of Nebraska; Lincoln NE USA
- HAL Allergy; Leiden the Netherlands
| | - A. Diaz-Perales
- Centre for Plant Biotechnology and Genomics UPM-INIA; Pozuelo de Alarcón; Madrid Spain
| | | | - A. B. Blazquez
- Research Laboratory; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
| | - M. Blanca
- UGC Allergy; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
| | - M. J. Torres
- UGC Allergy; IBIMA; Regional University Hospital of Malaga; UMA; Malaga Spain
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19
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Maleki SJ, Schmitt DA, Galeano M, Hurlburt BK. Comparison of the Digestibility of the Major Peanut Allergens in Thermally Processed Peanuts and in Pure Form. Foods 2014; 3:290-303. [PMID: 28234320 PMCID: PMC5302360 DOI: 10.3390/foods3020290] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/08/2014] [Accepted: 04/25/2014] [Indexed: 11/16/2022] Open
Abstract
It has been suggested that the boiling or frying of peanuts leads to less allergenic products than roasting. Here, we have compared the digestibility of the major peanut allergens in the context of peanuts subjected to boiling, frying or roasting and in purified form. The soluble peanut extracts and the purified allergens were digested with either trypsin or pepsin and analyzed by gel electrophoresis and western blot. T-cell proliferation was measured for the purified allergens. In most cases, boiled and raw peanut proteins were similarly digestible, but the Ara h 1 protein in the boiled extracts was more resistant to digestion. Most proteins from fried and roasted peanuts were more resistant to digestion than in raw and boiled samples, and more IgE binding fragments survived digestion. High-molecular-weight fragments of Ara h1 were resistant to digestion in fried and roasted samples. Ara h 1 and Ara h 2 purified from roasted peanuts were the most resistant to digestion, but differed in their ability to stimulate T-cells. The differences in digestibility and IgE binding properties of the major allergens in roasted, fried and boiled peanuts may not explain the difference between the prevalence of peanut allergy in different countries that consume peanut following these varied processing methods.
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Affiliation(s)
- Soheila J Maleki
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA.
| | - David A Schmitt
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA.
| | - Maria Galeano
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA.
| | - Barry K Hurlburt
- Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 1100 Robert E. Lee Blvd, New Orleans, LA 70124, USA.
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20
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Koid AE, Chapman MD, Hamilton RG, van Ree R, Versteeg SA, Dreskin SC, Koppelman SJ, Wünschmann S. Ara h 6 complements Ara h 2 as an important marker for IgE reactivity to peanut. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:206-13. [PMID: 24328145 PMCID: PMC4055559 DOI: 10.1021/jf4022509] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The similarities of two major peanut allergens, Ara h 2 and Ara h 6, in molecular size, amino acid sequence, and structure have made it difficult to obtain natural Ara h 6 free of Ara h 2. The objectives of this study were to purify natural Ara h 6 that is essentially free of Ara h 2 and to compare its IgE reactivity and potency in histamine release assays to Ara h 2. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the highly purified allergen (<0.01% Ara h 2) revealed a single 14.5 kD band, and the identity of Ara h 6 was confirmed by liquid chromatography-tandem mass spectrometry. Ara h 6 showed a higher seroprevalence in chimeric IgE enzyme-linked immunosorbent assay (n = 54) but a weaker biological activity in basophil histamine release assays than Ara h 2. Purified Ara h 6 will be useful for diagnostic IgE antibody assays as well as molecular and cellular studies to investigate the immunological mechanisms of peanut allergy.
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Affiliation(s)
- Audrey E Koid
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
| | - Martin D Chapman
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
| | - Robert G Hamilton
- Johns Hopkins University School of Medicine, 600 N Wolfe St #6-113, Baltimore, MD 21287
| | - Ronald van Ree
- Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam-Zuidoost, The Netherlands
| | - Serge A Versteeg
- Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam-Zuidoost, The Netherlands
| | - Stephen C Dreskin
- University of Colorado Denver, School of Medicine, 1250 14th St, Denver, CO 80202
| | | | - Sabina Wünschmann
- INDOOR Biotechnologies, Inc., 1216 Harris St, Charlottesville, VA 22903
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21
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Apostolovic D, Luykx D, Warmenhoven H, Verbart D, Stanic-Vucinic D, de Jong GAH, Velickovic TC, Koppelman SJ. Reduction and alkylation of peanut allergen isoforms Ara h 2 and Ara h 6; characterization of intermediate- and end products. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:2832-42. [PMID: 24145103 DOI: 10.1016/j.bbapap.2013.10.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Revised: 09/12/2013] [Accepted: 10/04/2013] [Indexed: 10/26/2022]
Abstract
Conglutins, the major peanut allergens, Ara h 2 and Ara h 6, are highly structured proteins stabilized by multiple disulfide bridges and are stable towards heat-denaturation and digestion. We sought a way to reduce their potent allergenicity in view of the development of immunotherapy for peanut allergy. Isoforms of conglutin were purified, reduced with dithiothreitol and subsequently alkylated with iodoacetamide. The effect of this modification was assessed on protein folding and IgE-binding. We found that all disulfide bridges were reduced and alkylated. As a result, the secondary structure lost α-helix and gained some β-structure content, and the tertiary structure stability was reduced. On a functional level, the modification led to a strongly decreased IgE-binding. Using conditions for limited reduction and alkylation, partially reduced and alkylated proteins were found with rearranged disulfide bridges and, in some cases, intermolecular cross-links were found. Peptide mass finger printing was applied to control progress of the modification reaction and to map novel disulfide bonds. There was no preference for the order in which disulfides were reduced, and disulfide rearrangement occurred in a non-specific way. Only minor differences in kinetics of reduction and alkylation were found between the different conglutin isoforms. We conclude that the peanut conglutins Ara h 2 and Ara h 6 can be chemically modified by reduction and alkylation, such that they substantially unfold and that their allergenic potency decreases.
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Affiliation(s)
- Danijela Apostolovic
- HAL Allergy B.V., J.H. Oortweg 15-17, 2333 CH Leiden, The Netherlands; Faculty of Chemistry, University of Belgrade, Studentski trg 16, 11 000 Belgrade, Serbia
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22
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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: 27] [Impact Index Per Article: 2.5] [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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23
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Abstract
Food allergy has become a major public health concern in westernized countries, and allergic reactions to peanuts are particularly common and severe. Allergens are defined as antigens that elicit an IgE response, and most allergenic materials (e.g., pollens, danders, and foods) contain multiple allergenic proteins. This has led to the concept that there are "major" allergens and allergens of less importance. "Major allergens" have been defined as allergens that bind a large amount of IgE from the majority of patients and have biologic activity. However, the ability of an allergen to cross-link complexes of IgE and its high-affinity receptor FcεRI (IgE/FcεRI), which we have termed its allergic effector activity, does not correlate well with assays of IgE binding. To identify the proteins that are the most active allergens in peanuts, we and others have employed in vitro model assays of allergen-mediated cross-linking of IgE/FcεRI complexes and have demonstrated that the most potent allergens are not necessarily those that bind the most IgE. The importance of a specific allergen can be determined by measuring the allergic effector activity of that allergen following purification under non-denaturing conditions and by specifically removing the allergen from a complex allergenic extract either by chromatography or by specific immunodepletion. In our studies of peanut allergens, our laboratory has found that two related allergens, Ara h 2 and Ara h 6, together account for the majority of the effector activity in a crude peanut extract. Furthermore, murine studies demonstrated that Ara h 2 and Ara h 6 are not only the major elicitors of anaphylaxis in this system, but also can effectively desensitize peanut-allergic mice. As a result of these observations, we propose that the definition of a major allergen should be based on the potency of that allergen in assays of allergic effector activity and demonstration that removal of that allergen from an extract results in loss of potency. Using these criteria, Ara h 2 and Ara h 6 are the major peanut allergens.
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Affiliation(s)
- Yonghua Zhuang
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado School of Medicine, 12700 E. 19th Ave., Room 10C03, Aurora, CO 80045, USA
| | - Stephen C. Dreskin
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado School of Medicine, 12700 E. 19th Ave., Room 10C03, Aurora, CO 80045, USA
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24
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Shi X, Guo R, White BL, Yancey A, Sanders TH, Davis JP, Burks AW, Kulis M. Allergenic Properties of Enzymatically Hydrolyzed Peanut Flour Extracts. Int Arch Allergy Immunol 2013; 162:123-30. [DOI: 10.1159/000351920] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2012] [Accepted: 05/02/2013] [Indexed: 11/19/2022] Open
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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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26
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Chen X, Wang Q, El-Mezayen R, Zhuang Y, Dreskin SC. Ara h 2 and Ara h 6 have similar allergenic activity and are substantially redundant. Int Arch Allergy Immunol 2012; 160:251-8. [PMID: 23075924 DOI: 10.1159/000341642] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 07/06/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The moderately homologous (approx. 60%) proteins Ara h 2 and Ara h 6 are the most potent peanut allergens. This study was designed to define the relative individual contributions of Ara h 2 and Ara h 6 to the overall allergenic activity of a crude peanut extract (CPE). METHODS Ara h 2 and Ara h 6 were removed from CPE by gel filtration chromatography. Ara h 2.01, Ara h 2.02 and Ara h 6 were further purified (>99%). The potency of each allergen and the ability of these allergens to reconstitute the allergenic activity of CPE depleted of Ara h 2 and Ara h 6 was measured with RBL SX-38 cells sensitized with IgE from sensitized peanut allergic patients. RESULTS The potency of the native proteins were significantly different (p < 0.0001) although not dramatically so, with a rank order of Ara h 2.01 > Ara h 2.02 > Ara h 6. The addition of either purified Ara h 2 or Ara h 6 independently at their original concentration to CPE depleted of both Ara h 2 and Ara h 6 restored 80-100% of the original CPE allergenic activity. Addition of both Ara h 2 and Ara h 6 consistently completely restored the allergenic activity of CPE. CONCLUSIONS These studies indicate that either Ara h 2 or Ara h 6 independently can account for most of the allergenic activity in a CPE and demonstrate important redundancy in the allergenic activity of these related molecules.
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Affiliation(s)
- Xueni Chen
- Division of Allergy and Clinical Immunology, Department of Medicine, University of Colorado Denver, Aurora, CO 80045, USA
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Catalán Ú, Fernández-Castillejo S, Anglès N, Morelló JR, Yebras M, Solà R. Inhibition of the transcription factor c-Jun by the MAPK family, and not the NF-κB pathway, suggests that peanut extract has anti-inflammatory properties. Mol Immunol 2012; 52:125-32. [PMID: 22673210 DOI: 10.1016/j.molimm.2012.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Revised: 05/08/2012] [Accepted: 05/09/2012] [Indexed: 12/15/2022]
Abstract
BACKGROUND Tumor necrosis factor-α (TNF-α) is involved in inflammatory responses in atherosclerosis. We propose an in vitro cellular assay to evaluate the anti-inflammatory mechanisms of potential modifiers such as food extracts. In the current model we assessed an anti-inflammatory effect of polyphenol-rich peanut extract in lipopolysaccharide (LPS)-induced THP-1 monocytes. METHODS THP-1 monocytes were incubated with peanut extract (5, 25, 50 and 100 μg/mL) consisting of 39% flavonols, 37% flavanols and 24% phenolic acid (or BAY 11-7082 (5 μM) as experiment control) for 1 h and then stimulated with LPS (500 ng/mL) for 4 h. Cytotoxicity was measured as lactate dehydrogenase (LDH) activity release. NF-κB and MAPK family were determined by TransAm kit while TNF-α mRNA levels and its mRNA stability by RT-PCR. Intra- and extracellular TNF-α protein was measured by ELISA, and TNF-α converting enzyme (TACE) activity by a fluorimetric assay. RESULTS Peanut extract inhibited the maximal LPS-induced extracellular TNF-α protein secretion by 18%, 29% and 47% at 25, 50 and 100 μg/mL, respectively (P<0.05). LPS stimulation revealed that 85% of TNF-α was released extracellularly while 15% remained intracellular. Peanut extract did not modify NF-κB but, instead, reduced c-Jun transcription factor activity (P<0.05), decreased TNF-α mRNA (albeit non-significantly) and had no effect on mRNA stability and TACE activity. CONCLUSION Polyphenol-rich peanut extract reduces extracellular TNF-α protein by inhibiting c-Jun transcription factor from MAPK family, suggesting an anti-inflammatory effect. The proposed THP-1 monocyte model could be used to assess food extract impact (site and size effects) on the inflammation pathway.
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Affiliation(s)
- Úrsula Catalán
- Unitat de Recerca en Lípids i Arteriosclerosi, CIBERDEM, Hospital Universitari Sant Joan, IISPV, Universitat Rovira i Virgili, Reus, Tarragona, Spain
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Kulis M, Chen X, Lew J, Wang Q, Patel OP, Zhuang Y, Murray KS, Duncan MW, Porterfield HS, W Burks A, Dreskin SC. The 2S albumin allergens of Arachis hypogaea, Ara h 2 and Ara h 6, are the major elicitors of anaphylaxis and can effectively desensitize peanut-allergic mice. Clin Exp Allergy 2012; 42:326-36. [PMID: 22288514 DOI: 10.1111/j.1365-2222.2011.03934.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Ara h 2 and Ara h 6, co-purified together in a 13-25 kD fraction (Ara h 2/6; 20 kD fraction) on gel filtration chromatography, account for the majority of effector activity in a crude peanut extract (CPE) when assayed with RBL SX-38 cells sensitized with IgE from human peanut allergic sera. OBJECTIVES To determine if Ara h 2/6 are the primary peanut allergens responsible for allergic reactions in vivo and to determine if Ara h 2/6 would be sufficient to prevent allergic reactions to a complete CPE. METHODS An oral sensitization mouse model of peanut allergy was used to assess the activity of Ara h 2/6 (20 kD) and CPE without the 20 kD fraction (CPE w/o 20 kD) for allergic provocation challenge and immunotherapy. The activity of these preparations was also tested in an assay of histamine release from human basophils in whole blood. RESULTS Compared with mice challenged with control CPE, mice challenged with CPE w/o 20 kD experienced reduced symptoms (P < 0.05) and a smaller decrease in body temperature (P < 0.01). Results with the basophil histamine release assay corroborated these findings (P < 0.01). The mouse model was also used to administer Ara h 2/6 (20 kD) in an immunotherapy protocol, in which peanut-allergic mice treated with the 20 kD fraction experienced significantly reduced symptoms, changes in body temperature, and mast cell protease (MMCP-1) release compared with placebo (P < 0.01 for all parameters). Importantly, immunotherapy with the 20 kD fraction was just as effective as treatment with CPE, whereas CPE w/o 20 kD was significantly less effective for higher dose peanut challenges. CONCLUSIONS AND CLINICAL RELEVANCE Ara h 2/6 are the most potent peanut allergens in vivo and can be used to desensitize peanut-allergic mice. These results have potential implications for clinical research in the areas of diagnosis and immunotherapy for peanut allergy.
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Affiliation(s)
- M Kulis
- Department of Pediatric Allergy and Immunology, Duke University Medical Center, Durham, NC, USA
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