Immunization with MOG fused to a novel single chain fragment variable (scFv) for murine DEC-205 suppresses allergic experimental encephalomyelitis (EAE) in mice. (106.12)

Abstract

Abstract The antigenreceptor DEC-205 is expressed by Dendritic cells (DC) and greatly increases antigen presentation. We have shown that in vivo loading of DC with antigen via anti-DEC-205:antigen conjugates induces immunosuppressive regulatory T-cells (Treg). Therefore we set out to create single chain fragment variables (scFv) specific for DEC-205 fused with the EAE antigen MOG, to target non-activated DC for induction of tolerance to EAE in vivo. A non-binding anti-b-gal scFv:MOG was created as control. ScFv:MOG fusions proteins were expressed and purified, and immunohistochemical staining of cytospins from isolated CD11c+ cells displayed a positive staining for DEC-scFv, colocalizing with MHC class II. For functional testing DEC-scFv:MOG was injected into mice. Lymph node DC were isolated thereafter and cocultivated with MOG-specific (2D2) T-cells. Strong T-cell proliferation was induced by DC from mice injected with DEC-scFv:MOG in contrast to controls. When analyzing the T-cell populations in DEC-scFv:MOG injected mice, we found enhanced numbers of CD4+CD25+FoxP3+ Treg (16% of CD4) as compared to control animals (10% of CD4). Most importantly, when EAE was induced in either DEC-scFv-MOG-injected or in control mice, none of the DEC-scFv:MOG injected mice developed EAE symptoms. In contrast, all animals in the control group developed a severe EAE. Thus, these data indicate that targeting of MOG to steady state DC in vivo prevents EAE by a Treg-driven mechanism.