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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Chem. | doi: 10.3389/fchem.2019.00650

Systematic dual targeting of dendritic cell C-type Lectin Receptor DC-SIGN and TLR7 using a trifunctional mannosylated antigen

 Eveline R. Li1,  Tim P. Hogervorst2,  Silvia Achilli3, 4, Sven C. Bruijns1,  Tim Arnoldus1,  Corinne Vivès4, Chung C. Wong2, Michel Thépaut4, Nico J. Meeuwenoord2, Hans Elst van den2, Herman S. Overkleeft2, Gijs A. Marel van der2, Dmitri V. Filippov2,  Sandra J. Van Vliet1,  Franck Fieschi4,  Jeroen D. Codée2* and  Yvette Van Kooyk1*
  • 1Amsterdam UMC, Vrije Universiteit Amsterdam, dept. of Molecular Cell Biology and Immunology, Cancer Center Amsterdam, Amsterdam Infection and Immunity Institute, Netherlands
  • 2Department of Bio-organic Synthesis, Faculty of Science, Leiden Institute of Chemistry, Leiden University, Netherlands
  • 3Univ. Grenoble Alpes, CNRS, Departement de Pharmacochimie Moléculaire, 38044 Grenoble, France Institut de Biologie Structurale (present address), France
  • 4Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale, 38044, France

Dendritic Cells (DCs) are important initiators of adaptive immunity, and they possess a multitude of Pattern Recognition Receptors (PRR) to generate an adequate T cell mediated immunity against invading pathogens. PRR ligands are frequently conjugated to tumor-associated antigens in a vaccination strategy to enhance the immune response towards such antigens. One of these PPRs, DC-SIGN, a member of the C-type lectin receptor family, has been extensively targeted with Lewis structures and mannose glycans, often presented in multivalent fashion. We synthesized a library of well-defined mannosides (mono-, di- and tri-mannosides), based on known ‘high mannose’ structures, that we presented in a systematically increasing number of copies (n=1, 2, 3 or 6), allowing us to simultaneously study the effect of mannoside configuration and multivalency on DC-SIGN binding via surface plasmon resonance and flow cytometry. Hexavalent presentation of the clusters showed the highest binding affinity, with the hexa-α1,2-di-mannoside being the most potent ligand. The four highest binding hexavalent mannoside structures were conjugated to a model melanoma gp100-peptide antigen and further equipped with a Toll-like receptor 7 (TLR7)-agonist as adjuvant for DC maturation, creating a trifunctional vaccine conjugate. Interestingly, DC-SIGN affinity of the mannoside clusters did not directly correlate with antigen presentation enhancing properties and the α1,2-di-mannoside cluster with the highest binding affinity in our library even hampered T cell activation.
Overall, this systematic study has demonstrated that multivalent glycan presentation can improve DC-SIGN binding but enhanced binding cannot be directly translated into enhanced antigen presentation and the sole assessment of binding affinity is thus insufficient to determine further functional biological activity. Furthermore, we show that well-defined antigen conjugates combining two different PRR ligands can be generated in a modular fashion to increase the effectiveness of vaccine constructs.

Keywords: DC-SIGN, dendritic cell – specific intercellular adhesion molecule 3 grabbing non-integrin, TLR7, glyco-antigen, vaccine model, peptide conjugate, Tumor-associated antigens, Mannoside

Received: 19 Jun 2019; Accepted: 11 Sep 2019.

Copyright: © 2019 Li, Hogervorst, Achilli, Bruijns, Arnoldus, Vivès, Wong, Thépaut, Meeuwenoord, Elst van den, Overkleeft, Marel van der, Filippov, Van Vliet, Fieschi, Codée and Van Kooyk. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Mx. Jeroen D. Codée, Department of Bio-organic Synthesis, Faculty of Science, Leiden Institute of Chemistry, Leiden University, Leiden, Netherlands, jcodee@chem.leidenuniv.nl
Prof. Yvette Van Kooyk, Amsterdam UMC, Vrije Universiteit Amsterdam, dept. of Molecular Cell Biology and Immunology, Cancer Center Amsterdam, Amsterdam Infection and Immunity Institute, Amsterdam, Netherlands, Y.vanKooyk@vumc.nl