Structure of intact IgE and the mechanism of ligelizumab revealed by electron microscopy.
IgE
antibody structure
electron microscopy
flexibility
therapeutic antibody
Journal
Allergy
ISSN: 1398-9995
Titre abrégé: Allergy
Pays: Denmark
ID NLM: 7804028
Informations de publication
Date de publication:
08 2020
08 2020
Historique:
received:
01
11
2019
revised:
10
01
2020
accepted:
22
01
2020
pubmed:
11
2
2020
medline:
15
5
2021
entrez:
11
2
2020
Statut:
ppublish
Résumé
IgE is the central antibody isotype in TH2-biased immunity and allergic diseases. The structure of intact IgE and the impact of IgE-targeting molecules on IgE however remain elusive. In order to obtain insights into IgE biology and the clinical impact, we aimed for structure determination of IgE and the complex of IgE with the anti-IgE antibody ligelizumab. Structures of two distinct intact IgE with specificity for cross-reactive carbohydrate determinants and Der p 2 as well as complexes of ligelizumab-Fab with IgE and IgE Fc were assessed by negative stain electron microscopy and solution scattering. Inhibition of IgE binding and displacement of receptor-bound IgE were assessed using cellular assays, basophil activation testing and ELIFAB assays. Our data reveal that the investigated IgE molecules share an overall rigid conformation. In contrast to the IgE Fc fragment, the IgE Fc in intact IgE is significantly less asymmetrically bent. The proximal and the distal Fabs are rigidly tethered to the Fc. Binding of ligelizumab to IgE in a 2:1 stoichiometry induces an extended and twofold symmetrical conformation of IgE, which retains a rigid Fab-Fc architecture. Analyses of effector cell activation revealed that ligelizumab inhibits IgE binding without displacing receptor-bound IgE. Together with an interference of CD23 binding, the data underline a functional activity similar to omalizumab. Our data reveal the first structures of intact IgE suggesting that the IgE Fab is fixed relative to the Fc. Furthermore, we provide a structural rationale for the inhibitory mechanism of ligelizumab.
Sections du résumé
BACKGROUND
IgE is the central antibody isotype in TH2-biased immunity and allergic diseases. The structure of intact IgE and the impact of IgE-targeting molecules on IgE however remain elusive. In order to obtain insights into IgE biology and the clinical impact, we aimed for structure determination of IgE and the complex of IgE with the anti-IgE antibody ligelizumab.
METHODS
Structures of two distinct intact IgE with specificity for cross-reactive carbohydrate determinants and Der p 2 as well as complexes of ligelizumab-Fab with IgE and IgE Fc were assessed by negative stain electron microscopy and solution scattering. Inhibition of IgE binding and displacement of receptor-bound IgE were assessed using cellular assays, basophil activation testing and ELIFAB assays.
RESULTS
Our data reveal that the investigated IgE molecules share an overall rigid conformation. In contrast to the IgE Fc fragment, the IgE Fc in intact IgE is significantly less asymmetrically bent. The proximal and the distal Fabs are rigidly tethered to the Fc. Binding of ligelizumab to IgE in a 2:1 stoichiometry induces an extended and twofold symmetrical conformation of IgE, which retains a rigid Fab-Fc architecture. Analyses of effector cell activation revealed that ligelizumab inhibits IgE binding without displacing receptor-bound IgE. Together with an interference of CD23 binding, the data underline a functional activity similar to omalizumab.
CONCLUSIONS
Our data reveal the first structures of intact IgE suggesting that the IgE Fab is fixed relative to the Fc. Furthermore, we provide a structural rationale for the inhibitory mechanism of ligelizumab.
Substances chimiques
Antibodies, Monoclonal, Humanized
0
Receptors, IgE
0
Omalizumab
2P471X1Z11
Immunoglobulin E
37341-29-0
ligelizumab
L8LE0L691T
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
1956-1965Informations de copyright
© 2020 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.
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