Induction of Indoleamine 2,3-Dioxygenase Expression by Interferon-g in Human Mesenchymal Stem Cells Inhibits Graft Versus Host Disease

Abstract

Abstract 4698 Background:It is important to overcome the limitations such as graft rejection and graft versus host disease (GvHD) in allogeneic hematopoietic stem cell transplantation. Mesenchymal stem cells (MSCs), which evoke only minimal immune reactivity, may have anti-inflammatory and immunomodulatory effects. Purpose:In this study, we aimed to identify the immunomodulatory properties of human MSCs and to elucidate the possible mechanism of their properties for clinical treatment of allogeneic conflicts using MSCs. Materials & Methods:We conducted a comparative analysis about the immunomodulatory properties of MSCs derived from adult human tissues, including bone marrow (BM), adipose tissues (AT), umbilical cord blood (CB), and cord Wharton's jelly (WJ), in vitro and in vivo models. Results:AT-MSCs, CB-MSCs, and WJ-MSCs effectively suppressed phytohemagglutinin (PHA)-induced T-cell proliferation as effectively as did BM-MSCs. Levels of interferon (IFN)-g secreted from activated T-cells increased over time, but these levels were significantly reduced when cocultured with each type of MSCs. In addition, expression of indoleamine 2,3-dioxygenase (IDO) increased in MSCs treated with IFN-γ via JAK/STAT1 signaling pathways. Treatment with anti-IFN-g antibodies, JAK1/2 inhibitor or STAT1 siRNA restored PHA-induced T-cell proliferation. Use of an antagonist, 1-methyl-L-tryptophan, also restored PHA-induced T-cell proliferation, suggesting that IDO contributes to IFN-g-induced immunosuppression in MSCs. Moreover, infusion of IFN-g-treated MSCs decreased symptoms for human peripheral blood-derived mononuclear cells-induced GvHD in NOD/SCID mice, which resulted in an increase of survival rate of in vivo GvHD model. Conclusion:These data indicate that IFN-γ produced by activated T-cells is correlated with induction of IDO expression in MSCs by IFN-γ receptor/JAK/STAT1 pathway, which resulted in suppression of T-cell proliferation. Our findings suggest that MSCs derived from BM, AT, CB, or WJ could be used for clinical treatment of allogeneic conflicts. Disclosures:No relevant conflicts of interest to declare.