RESUMO
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.
Assuntos
Antirreumáticos/farmacologia , Artrite Experimental/prevenção & controle , Autoimunidade/efeitos dos fármacos , Fragmentos Fc das Imunoglobulinas/farmacologia , Receptores Fc/antagonistas & inibidores , Receptores de IgG/antagonistas & inibidores , Animais , Antirreumáticos/metabolismo , Artrite Experimental/genética , Artrite Experimental/imunologia , Artrite Experimental/metabolismo , Ligação Competitiva , Complemento C5a/metabolismo , Feminino , Antígenos de Histocompatibilidade Classe I/genética , Antígenos de Histocompatibilidade Classe I/imunologia , Antígenos de Histocompatibilidade Classe I/metabolismo , Humanos , Fragmentos Fc das Imunoglobulinas/genética , Fragmentos Fc das Imunoglobulinas/imunologia , Fragmentos Fc das Imunoglobulinas/metabolismo , Interleucina-2/metabolismo , Células Jurkat , Cinética , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Fagocitose/efeitos dos fármacos , Agregação Plaquetária/efeitos dos fármacos , Ligação Proteica , Engenharia de Proteínas , Receptores Fc/genética , Receptores Fc/imunologia , Receptores Fc/metabolismo , Receptores de IgG/genética , Receptores de IgG/imunologia , Receptores de IgG/metabolismo , Via Secretória , Transdução de Sinais , Células THP-1RESUMO
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.
