Myeloid-Derived Suppressor Cells Mediate Inflammation Resolution in Humans and Mice with Autoimmune Uveoretinitis

Resolution of inflammation is an active process that leads to tissue homeostasis and involves multiple cellular and molecular mechanisms. Myeloid-derived suppressor cells (MDSCs) have recently emerged as important cellular components in the resolution of inflammation because of their activities to suppress T cell activation. In this article, we show that HLA-DR^-CD11b⁺CD33⁺CD14⁺ human MDSCs and CD11b⁺Ly6G^-Ly6C⁺ mouse MDSCs markedly increased in patients and mice during and before the resolution phase of autoimmune uveoretinitis. CD11b⁺Ly6C⁺ monocytes isolated from autoimmune uveoretinitis mice were able to suppress T cell proliferation in culture, and adoptive transfer of the cells accelerated the remission of autoimmune uveoretinitis in mice. Alternatively, depletion of CD11b⁺Ly6C⁺ monocytes at the resolution phase, but not CD11b⁺Ly6G⁺ granulocytes, exacerbated the disease. These findings collectively indicate that monocytic MDSCs serve as regulatory cells mediating the resolution of autoimmune uveoretinitis.