Vaccination without Autoantigen Protects against Collagen II-Induced Arthritis via Immune Deviation and Regulatory T Cells

Abstract

Anti-inflammation immunotherapy has been successfully applied for the treatment of autoimmune diseases. Mucosal vaccines against autoimmune disorders are beneficial by influencing the regulatory compartment of gut and systemic adaptive immune systems. A Salmonella vector expressing colonization factor Ag I (CFA/I), shown to behave as an anti-inflammatory vaccine, stimulates the production of CD4⁺CD25⁺ T cells and regulatory cytokines. In this work, we queried whether Salmonella-CFA/I can protect DBA/1 mice from collagen-induced arthritis. The incidence of arthritis and cartilage loss in vaccinated DBA/1 mice was remarkably lower when compared with unprotected mice. Clinical findings were accompanied by the suppression of inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-27. Vaccination evoked a multi-tier response consisting of IL-4 producing Th2 cells, an increased production of TGF-β by CD4⁺ T cells, and suppression of collagen II-specific CD4⁺ T cell proliferation. To assess the contribution of Salmonella-CFA/I-primed CD4⁺ T cells, adoptive transfer studies with total CD4⁺, CD4⁺CD25⁻, or CD4⁺CD25⁺ T cells were performed 15 days postchallenge. Mice receiving either subset showed reduced disease incidence and low clinical scores; however, mice receiving total CD4⁺ T cells showed delayed disease onset by 10 days with reduced clinical scores, reduced IL-17 and IL-27, but enhanced IL-4, IL-10, IL-13, and TGF-β. Inhibition of TGF-β or IL-4 compromised protective immunity. These data show that Salmonella-CFA/I vaccination of DBA/1 mice protects against collagen-induced arthritis by stimulating TGF-β- and IL-4-producing regulatory CD4⁺ T cells.