IFN-β Facilitates Neuroantigen-Dependent Induction of CD25+ FOXP3+ Regulatory T Cells That Suppress Experimental Autoimmune Encephalomyelitis

This study introduces a flexible format for tolerogenic vaccination that incorporates IFN-beta and neuroantigen (NAg) in the Alum adjuvant. Tolerogenic vaccination required all three components, IFN-beta, NAg, and Alum, for inhibition of experimental autoimmune encephalomyelitis (EAE) and induction of tolerance. Vaccination with IFN-beta + NAg in Alum ameliorated NAg-specific sensitization and inhibited EAE in C57BL/6 mice in pretreatment and therapeutic regimens. Tolerance induction was specific for the tolerogenic vaccine Ag PLP178-191 or myelin oligodendrocyte glycoprotein (MOG) 35-55 in proteolipid protein-and MOG-induced models of EAE, respectively, and was abrogated by pretreatment with a depleting anti-CD25 mAb. IFN-beta/Alum-based vaccination exhibited hallmarks of infectious tolerance, because IFN-beta(+) OVA in Alum-specific vaccination inhibited EAE elicited by OVA + MOG in CFA but not EAE elicited by MOG in CFA. IFN-beta(+) NAg in Alum vaccination elicited elevated numbers and percentages of FOXP3(+) T cells in blood and secondary lymphoid organs in 2D2 MOG-specific transgenic mice, and repeated boosters facilitated generation of activated CD44(high) CD25(+) regulatory T cell (Treg) populations. IFN-beta and MOG35-55 elicited suppressive FOXP3(+) Tregs in vitro in the absence of Alum via a mechanism that was neutralized by anti-TGF-beta and that resulted in the induction of an effector CD69(+) CTLA-4(+) IFNAR(+) FOXP3(+) Treg subset. In vitro IFN-beta(+) MOG-induced Tregs inhibited EAE when transferred into actively challenged recipients. Unlike IFN-beta(+) NAg in Alum vaccines, vaccination with TGF-beta + MOG35-55 in Alum did not increase Treg percentages in vivo. Overall, this study indicates that IFN-beta(+) NAg in Alum vaccination elicits NAg-specific, suppressive CD25(+) Tregs that inhibit CNS autoimmune disease. Thus, IFN-beta has the activity spectrum that drives selective responses of suppressive FOXP3(+) Tregs.