Generation of high affinity ICAM-1-specific nanobodies and evaluation of their suitability for allergy treatment

Ines Zettl, Tatiana Ivanova, Mohammed Zghaebi, Marina V. Rutovskaya, Isabella Ellinger, Oksana Goryainova, Jessica Kollárová, Sergio Villazala-Merino, Christian Lupinek, Christina Weichwald, Anja Drescher, Julia Eckl-Dorna, Sergei V. Tillib, Sabine Flicker.

Front Immunol. 2022 Nov 9;13:1022418.
doi: 10.3389/fimmu.2022.1022418

Pollen allergy is considered one of the most common IgE-mediated hypersensitivity disorders and represents a global health and economic burden. The nose is an important site of allergen entry, where trans-epithelial allergen penetration and subsequent IgE-mediated allergic inflammation can potentially be inhibited. Topically applied allergen-specific IgG antibodies that are able to catch allergens on the apical side and efficiently block allergen penetration of the epithelial barrier have been reported. These antibodies were chemically conjugated to IgG antibodies specific for Intercellular Adhesion Molecule 1 (ICAM-1), a molecule highly expressed during allergic inflammation, to anchor them to the apical side of epithelial cells. To produce well defined antibody constructs at reasonable expenses, we were interested to generate nanobody-based constructs specific for ICAM-1 and allergens. We have previously characterized nanobodies specific for the major birch pollen allergen Bet v 1 and here we report the generation and characterization of ICAM-1-specific nanobodies.

Nanobodies were obtained from a camel immunized with ICAM-1 and a strong binder was selected after phage display. The isolated nanobody (Nb44) specifically recognized ICAM-1 expressed on the human bronchial epithelial cell line 16HBE14o-, our surrogate for the nasal cavity. More importantly, Nb44 was not internalized upon ICAM-1 binding (up to 24 hours). Additionally, it displayed high affinity to ICAM-1 and slow off-rates comparable to monoclonal IgG antibodies.

These characteristics (high affinity to ICAM-1 and lack of internalization) render our isolated nanobody a suitable candidate to engineer heterodimers with allergen-specific nanobodies in order to develop topical treatments of pollen allergy.

This study was supported by the Austrian Science Fund (FWF) grants I3946-B33 and F4607, by the Russian Foundation for Basic Research (RFBR) grant 18-515-14003 and by the Country of Lower Austria’s funded Danube Allergy Research Cluster.