Title: Tolerance in the Absence of Autoantigen
Volume: 7
Issue: 3
Author(s): D. W. Pascual, J. Ochoa-Reparaz, A. Rynda and X. Yang
Affiliation:
Keywords:
Vaccine, regulatory T cells, Th1Th2Th17 cells, EAE, bacteria
Abstract: Regulatory T (Treg) cells show promise for treating autoimmune diseases, but their induction to elevated potency has been problematic when the most optimally derived cells are from diseased animals. To circumvent reliance on auto-antigen reactive Treg cells, stimulation to vaccine antigens (Ags) may offer a viable alternative while maintaining potency to protect against proinflammatory diseases. Our Salmonella vaccine expressing colonization factor Ag I (CFA/I) possesses anti-inflammatory properties, evident by elevated Th2 cell responses, reduced inflammatory cell infiltrates in the Peyers patches, and an absence of proinflammatory cytokine production by infected macrophages. Given these findings, we hypothesized whether this vaccine would be protective against experimental autoimmune encephalomyelitis (EAE). As such, Salmonella-CFA/I protected in both prophylactic and therapeutic paradigms against proteolipid protein (PLP139-151)-mediated EAE in SJL mice. The protected mice showed significantly reduced clinical disease and subsequent resolution when compared to PBS-treated controls. Histopathological studies showed reduced demyelination and no inflammation of spinal cords when compared to PBS- or Salmonella vector-treated mice. To ascertain whether the observed immune deviation was in part supported by Treg cells, analysis revealed involvement of FoxP3+ CD25+ CD4+ T cells. Adoptive transfer of induced TGF-β+ Treg cells from vaccinated mice showed complete protection against PLP139-151 challenge, but not by naive Treg cells. Partial protection to EAE was also achieved by the adoptive transfer of CD25- CD4+ T cells, suggesting that Th2 cells also contributed. Thus, these data show that Treg cells are induced by oral vaccination with Salmonella-CFA/I contributing to the efficacious treatment of autoimmune disease.
