Type1 IFN signaling on Tregs modulates the migration of Myeloid Derived Suppressor Cells

Abstract

Abstract Multiple sclerosis is an autoimmune disorder whose severity is reduced with immune suppressive drugs. Therapeutic intervention with interferon-beta reduces disease exacerbations and delays relapses. The receptor for type 1 interferon, IFNAR, is present on virtually all cell types making it difficult to dissect the mechanisms involved. To address this issue, we induced experimental autoimmune encephalomyelitis (EAE) in mice with a conditional deletion (cKO) of IFNAR in T regulatory (Treg) cells (IFNARfl/flxFoxp3YFP-Cre). cKO mice developed severe EAE with an earlier onset than control mice. Although Treg cells from cKO mice appeared to be more activated, the activation status of and effector cytokine production by CD4+T cells in the draining lymph nodes (dLN) was similar in WT and cKO mice during the priming phase, but higher in cKO CD4+T cells in the effector phase. Interestingly, we noted a substantial reduction of myeloid derived suppressor cells (MDSCs) in the dLN of cKO mice, while generation of MDSCs in bone marrow and recruitment to spleen of WT and cKO mice were comparable. Surprisingly, we noted a decrease in the production of monocyte and granulocyte cell recruiting chemokine ligands by CD4+ and CD8+ T cells, B cells and endothelial cells in the dLN during the priming phase in the cKO mice. While modulation of Treg cell number and function by MDSCs has been documented, this study is one of the first to demonstrate that Treg cells modify the lymph node microenvironment by modulating MDSC homing and raises the possibility of a novel role for Treg cells in regulating the kinetics of MDSC recruitment during inflammatory conditions. This research was supported by the Intramural Research Program of NIAID, NIH.