A Tolerogenic Artificial APC Durably Ameliorates Experimental Autoimmune Encephalomyelitis by Directly and Selectively Modulating Myelin Peptide-Autoreactive CD4+ and CD8+ T Cells

In this study, a tolerogenic artificial APC (TaAPC) was developed to directly and selectively modulate myelin-autoreactive CD4(+) and CD8(+) T cells in the myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide-induced experimental autoimmune encephalomyelitis in C57BL/6J mice. Cell-sized polylactic-coglycolic acid microparticles were generated to cocouple target Ags (MOG(40-54)/H-2D(b)-Ig dimer, MOG(35-55)/I-A(b) multimer), regulatory molecules (anti-Fas and PD-L1-Fc), and self-marker CD47-Fc and encapsulate inhibitory cytokine (TGF-beta 1). Four infusions of the TaAPCs markedly and durably inhibited the experimental autoimmune encephalomyelitis progression and reduced the local inflammation in CNS tissue. They circulated throughout vasculature into peripheral lymphoid tissues and various organs, but not into brain, with retention of 36 h and exerted direct effects on T cells in vivo and in vitro. Two infusions of the TaAPCs depleted 65-79% of MOG(35-55)-specific CD4(+) and 46-62% of MOG(40-54)-specific CD8(+) T cells in peripheral blood, spleen, and CNS tissues in an Ag-specific manner and regulatory molecule-dependent fashion; induced robust T cell apoptosis; inhibited the activation and proliferation of MOG peptide-reactive T cells; reduced MOG peptide-reactive Th1, Th17, and Tc17 cells; and expanded regulatory T cells. They also inhibited IFN-g/IL-17A secretion and elevated IL-10/TGF-beta 1 production in splenocytes but not in CNS tissue. More importantly, the TaAPCs treatment did not obviously suppress the overall immune function of host. To our knowledge, this study provides the first experimental evidence for the capability of TaAPCs to directly modulate autoreactive T cells by surface presentation of multiple ligands and paracrine release of cytokine, thus suggesting a novel Ag-specific immunotherapy for the T cell-mediated autoimmune diseases.