Fold stability during endolysosomal acidification is a key factor for allergenicity and immunogenicity of the major birch pollen allergen

Background The search for intrinsic factors, which account for a protein's capability to act as an allergen, is ongoing. Fold stability has been identified as a molecular feature that affects processing and presentation, thereby influencing an antigen's immunologic properties. Objective We...

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Published in:Journal of allergy and clinical immunology 2016-05, Vol.137 (5), p.1525-1534
Main Authors: Machado, Yoan, MSc, Freier, Regina, MSc, Scheiblhofer, Sandra, PhD, Thalhamer, Theresa, PhD, Mayr, Melissa, BSc, Briza, Peter, PhD, Grutsch, Sarina, PhD, Ahammer, Linda, MSc, Fuchs, Julian E., PhD, Wallnoefer, Hannes G., PhD, Isakovic, Almedina, MSc, Kohlbauer, Vera, MSc, Hinterholzer, Arthur, BSc, Steiner, Markus, MSc, Danzer, Martin, MSc, Horejs-Hoeck, Jutta, PhD, Ferreira, Fatima, PhD, Liedl, Klaus R., PhD, Tollinger, Martin, PhD, Lackner, Peter, PhD, Johnson, Christopher M., PhD, Brandstetter, Hans, PhD, Thalhamer, Josef, PhD, Weiss, Richard, PhD
Format: Article
Language:English
Subjects:
Allergens - chemistry
Allergens - genetics
Allergens - immunology
Allergic sensitization
Allergies
Allergy and Immunology
Animals
antigen processing and presentation
Antigens
Antigens, Plant - chemistry
Antigens, Plant - genetics
Antigens, Plant - immunology
Bet v 1
Colleges & universities
endolysosomal degradation
Endosomes
Female
Fourier transforms
Hydrogen-Ion Concentration
Immunoglobulin E - immunology
Immunoglobulin G - immunology
Ligands
Mechanisms of Allergy and Clinical Immunology
Mice, Inbred BALB C
molecular allergology
Mutation
NMR
Nuclear magnetic resonance
Pollen
Pollen - immunology
Protein Folding
Protein Stability
Spectrum analysis
structural stability
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Summary:Background The search for intrinsic factors, which account for a protein's capability to act as an allergen, is ongoing. Fold stability has been identified as a molecular feature that affects processing and presentation, thereby influencing an antigen's immunologic properties. Objective We assessed how changes in fold stability modulate the immunogenicity and sensitization capacity of the major birch pollen allergen Bet v 1. Methods By exploiting an exhaustive virtual mutation screening, we generated mutants of the prototype allergen Bet v 1 with enhanced thermal and chemical stability and rigidity. Structural changes were analyzed by means of x-ray crystallography, nuclear magnetic resonance, and molecular dynamics simulations. Stability was monitored by using differential scanning calorimetry, circular dichroism, and Fourier transform infrared spectroscopy. Endolysosomal degradation was simulated in vitro by using the microsomal fraction of JAWS II cells, followed by liquid chromatography coupled to mass spectrometry. Immunologic properties were characterized in vitro by using a human T-cell line specific for the immunodominant epitope of Bet v 1 and in vivo in an adjuvant-free BALB/c mouse model. Results Fold stabilization of Bet v 1 was pH dependent and resulted in resistance to endosomal degradation at a pH of 5 or greater, affecting presentation of the immunodominant T-cell epitope in vitro . These properties translated in vivo into a strong allergy-promoting TH 2-type immune response. Efficient TH 2 cell activation required both an increased stability at the pH of the early endosome and efficient degradation at lower pH in the late endosomal/lysosomal compartment. Conclusions Our data indicate that differential pH-dependent fold stability along endosomal maturation is an essential protein-inherent determinant of allergenicity.
ISSN:0091-6749
1097-6825
DOI:10.1016/j.jaci.2015.09.026