Bet v 1 - a Trojan horse for small ligands boosting allergic sensitization?

Claudia Asam, AL Batista, AH Moraes, VS de Paula, FC Almeida, Lorenz Aglas, C Kitzmüller, B Bohle, C Ebner, Fatima Ferreira, Michael Wallner, AP Valente

    Research output: Contribution to journalArticle

    Abstract

    BACKGROUND: Birch pollen allergy represents the main cause of winter and spring pollinosis in the temperate climate zone of the northern hemisphere and sensitization towards Bet v 1, the major birch pollen allergen, affects over 100 million allergic patients. The major birch pollen allergen Bet v 1 has been described as promiscuous acceptor for a wide variety of hydrophobic ligands.

    OBJECTIVE: In search of intrinsic properties of Bet v 1, which account responsible for the high allergenic potential of the protein, we thought to investigate the effects of ligand-binding on immunogenic as well as allergenic properties.

    METHODS: As surrogate ligand of Bet v 1 sodium deoxycholate (DOC) was selected. Recombinant and natural Bet v 1 were characterised physico-chemically as well as immunologically in the presence or absence of DOC, and an animal model of allergic sensitization was established. Moreover, human IgE binding to Bet v 1 was analysed by nuclear magnetic resonance (NMR) spectroscopy.

    RESULTS: Ligand-binding had an overall stabilizing effect on Bet v 1. This translated in a Th2 skewing of the immune response in a mouse model. Analyses of human IgE binding on Bet v 1 in mediator release assays revealed that ligand-bound allergen-induced degranulation at lower concentrations; however, in basophil activation tests with human basophils ligand-binding did not show this effect. For the first time, human IgE epitopes on Bet v 1 were determined using antibodies isolated from patients' sera. The IgE epitope mapping of Bet v 1 demonstrated the presence of multiple binding regions.

    CONCLUSIONS AND CLINICAL RELEVANCE: Deoxycholate binding stabilizes conformational IgE epitopes on Bet v 1; however, the epitopes themselves remain unaltered. Therefore, we speculate that humans are exposed to both ligand-bound and free Bet v 1 during sensitization, disclosing the ligand-binding cavity of the allergen as key structural element.

    Original languageEnglish
    Pages (from-to)1083-93
    Number of pages11
    JournalClinical and Experimental Allergy
    Volume44
    Issue number8
    DOIs
    Publication statusPublished - Aug 2014

    Fields of Science and Technology Classification 2012

    • 302 Clinical Medicine
    • 106 Biology

    Keywords

    • Allergens/chemistry
    • Animals
    • Antigens, Plant/chemistry
    • Basophil Degranulation Test
    • Basophils/immunology
    • Betula/adverse effects
    • Cell Degranulation/immunology
    • Cell Line
    • Deoxycholic Acid/chemistry
    • Disease Models, Animal
    • Epitope Mapping
    • Epitopes/immunology
    • Female
    • Humans
    • Immunization
    • Immunoglobulin E/immunology
    • Ligands
    • Mice
    • Models, Molecular
    • Pollen/immunology
    • Protein Binding
    • Protein Conformation
    • Protein Stability
    • Recombinant Proteins/chemistry
    • Rhinitis, Allergic, Seasonal/immunology
    • Thermodynamics

    Cite this

    Asam, C., Batista, AL., Moraes, AH., Paula, VS. D., Almeida, FC., Aglas, L., ... Valente, AP. (2014). Bet v 1 - a Trojan horse for small ligands boosting allergic sensitization? Clinical and Experimental Allergy, 44(8), 1083-93. https://doi.org/10.1111/cea.12361