Format

Send to

Choose Destination
J Allergy Clin Immunol. 2016 May;137(5):1525-34. doi: 10.1016/j.jaci.2015.09.026. Epub 2015 Nov 11.

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

Author information

1
Department of Molecular Biology, University of Salzburg, Salzburg, Austria.
2
Center of Molecular Biosciences & Institute of Organic Chemistry, University of Innsbruck, Innsbruck, Austria.
3
Center of Molecular Biosciences & Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria.
4
Austrian Red Cross, Blood Transfusion Service for Upper Austria, Linz, Austria.
5
MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
6
Department of Molecular Biology, University of Salzburg, Salzburg, Austria. Electronic address: Richard.Weiss@sbg.ac.at.

Abstract

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 TH2-type immune response. Efficient TH2 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.

KEYWORDS:

Allergic sensitization; Bet v 1; antigen processing and presentation; endolysosomal degradation; molecular allergology; structural stability

PMID:
26559323
PMCID:
PMC4877439
DOI:
10.1016/j.jaci.2015.09.026
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center