RÉSUMÉ
Novel molecules that directly target the neonatal Fc receptor (FcRn) and/or Fc gamma receptors (FcγRs) are emerging as promising treatments for immunoglobulin G (IgG)-dependent autoimmune pathologies. Mutated Fc regions and monoclonal antibodies that target FcRn are currently in clinical development and hold promise for reducing the levels of circulating IgG. Additionally, engineered structures containing multimeric Fc regions allow the dual targeting of FcRn and FcγRs; however, their tolerance needs to first be validated in phase I clinical studies. Here, for the first time, we have developed a modified monomeric recombinant Fc optimized for binding to all FcRns and FcγRs without the drawback of possible tolerance associated with FcγR cross-linking. A rational approach using Fc engineering allowed the selection of LFBD192, an Fc with a combination of six mutations that exhibits improved binding to human FcRn and FcγR as well as mouse FcRn and FcγRIV. The potency of LFBD192 was compared with that of intravenous immunoglobulin (IVIg), an FcRn blocker (Fc-MST-HN), and a trimeric Fc that blocks FcRn and/or immune complex-mediated cell activation through FcγR without triggering an immune reaction in several in vitro tests and validated in three mouse models of autoimmune disease.
Sujet(s)
Antirhumatismaux/pharmacologie , Arthrite expérimentale/prévention et contrôle , Auto-immunité/effets des médicaments et des substances chimiques , Fragments Fc des immunoglobulines/pharmacologie , Récepteur Fc/antagonistes et inhibiteurs , Récepteurs du fragment Fc des IgG/antagonistes et inhibiteurs , Animaux , Antirhumatismaux/métabolisme , Arthrite expérimentale/génétique , Arthrite expérimentale/immunologie , Arthrite expérimentale/métabolisme , Fixation compétitive , Complément C5a/métabolisme , Femelle , Antigènes d'histocompatibilité de classe I/génétique , Antigènes d'histocompatibilité de classe I/immunologie , Antigènes d'histocompatibilité de classe I/métabolisme , Humains , Fragments Fc des immunoglobulines/génétique , Fragments Fc des immunoglobulines/immunologie , Fragments Fc des immunoglobulines/métabolisme , Interleukine-2/métabolisme , Cellules Jurkat , Cinétique , Souris de lignée C57BL , Souris transgéniques , Mutation , Phagocytose/effets des médicaments et des substances chimiques , Agrégation plaquettaire/effets des médicaments et des substances chimiques , Liaison aux protéines , Ingénierie des protéines , Récepteur Fc/génétique , Récepteur Fc/immunologie , Récepteur Fc/métabolisme , Récepteurs du fragment Fc des IgG/génétique , Récepteurs du fragment Fc des IgG/immunologie , Récepteurs du fragment Fc des IgG/métabolisme , Voie de sécrétion , Transduction du signal , Cellules THP-1RÉSUMÉ
The long serum t 1/2 of IgGs is ensured by their interaction with the neonatal Fc receptor (FcRn), which salvages IgG from intracellular degradation. Fc glycosylation is thought not to influence FcRn binding and IgG longevity in vivo. In this article, we demonstrate that hypersialylation of asparagine 297 (N297) enhances IgG serum persistence. This polarized glycosylation is achieved using a novel Fc mutation, a glutamate residue deletion at position 294 (Del) that endows IgGs with an up to 9-fold increase in serum lifespan. The strongest impact was observed when the Del was combined with Fc mutations improving FcRn binding (Del-FcRn+). Enzymatic desialylation of a Del-FcRn+ mutant or its production in a cell line unable to hypersialylate reduced the in vivo serum t 1/2 of the desialylated mutants to that of native FcRn+ mutants. Consequently, our study proves that sialylation of the N297 sugar moiety has a direct impact on human IgG serum persistence.