Graft-versus-host disease (GVHD) is the leading cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation, an established therapy for patients with hematological malignancies. Current strategies to diminish GVHD include T-cell depletion and immunosuppressive drugs, which are associated with an increased risk of tumor relapse, opportunistic infection, and/or toxicity. Novel approaches acting intrinsically on the immune system are clearly needed. Myeloid-derived suppressor cells (MDSCs) consist of a population of myeloid precursor cells that exhibit potent suppressive activities capable of dampening anti-tumor responses, autoimmunity, and allo-responses in graft-versus-host diseases (GVHD) and organ transplantation. Our preliminary results indicate that MDSCs have several attractive attributes as helper cells to inhibit GVHD without significantly compromising graft-versus-leukemia/lymphoma (GVL) in a murine model, resulting in the establishment of long-term survival. Recently, we also demonstrated that MDSCs acquire M1 or M2 functional macrophage phenotypes through regulation of PIR-B (paired immunoblobulin-like receptor B and human counterpart inhibitory immunoglobulin-like receptors B, LILRBs) signaling, which may facilitate the development of antitumor responses or mediate immune suppression and Treg activation, respectively. The objective of this proposal is to understand the mechanism by which MDSC biological function is regulated and to devise an optimized protocol for directing the functional activities of MDSC toward suppression of GVHD while allowing sufficient GVL activity to eradicate tumors. Based on the results of ou preliminary studies, we hypothesize that: (i) The functional phenotype of MDSC can be modulated by PIR-BL ligation and (ii) The presence of MDSCs with a persistent M2 functional phenotype may be sufficient to prevent GHVD and retain GVL ability.
Three specific aims will be pursued:
Aim 1. Study the regulation of MDSC function and the associated effects on GVHD.
Aim 2. Study the effects of PIR-B ligation on MDSC as related to inhibition of GVHD and the corresponding signaling regulation in an irradiated host.
Aim 3. Study the mechanism and effects of MDSC mediated regulation of GVHD vs. GVL through PIR-B/LILRB engagement in mouse GVHD models and in a human xenograft NSG mouse model. The proposed studies will provide the basis and scientific principles for future clinical translation.

Public Health Relevance

The goal of this project is: 1) to identify the MDSC linage commitment for the effect on GVHD vs. GVL~ 2) the mechanism underlying Using PIRB ligand to control MDSCs differentiation and achieve better therapeutic outcome. The information gained from these studies will provide the basis for the mobilization and modulation of human MDSCs from bone marrow for use in clinical settings.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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Transplantation, Tolerance, and Tumor Immunology (TTT)
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Muszynski, Karen
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Icahn School of Medicine at Mount Sinai
Internal Medicine/Medicine
Schools of Medicine
New York
United States
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Eisenstein, Samuel; Coakley, Brian A; Briley-Saebo, Karen et al. (2013) Myeloid-derived suppressor cells as a vehicle for tumor-specific oncolytic viral therapy. Cancer Res 73:5003-15
Ma, Ge; Pan, Ping-Ying; Eisenstein, Samuel et al. (2011) Paired immunoglobin-like receptor-B regulates the suppressive function and fate of myeloid-derived suppressor cells. Immunity 34:385-95
Meseck, Marcia; Huang, Tiangui; Ma, Ge et al. (2011) A functional recombinant human 4-1BB ligand for immune costimulatory therapy of cancer. J Immunother 34:175-82
Kao, Johnny; Ko, Eric C; Eisenstein, Samuel et al. (2011) Targeting immune suppressing myeloid-derived suppressor cells in oncology. Crit Rev Oncol Hematol 77:12-9
Pan, Ping-Ying; Ma, Ge; Weber, Kaare J et al. (2010) Immune stimulatory receptor CD40 is required for T-cell suppression and T regulatory cell activation mediated by myeloid-derived suppressor cells in cancer. Cancer Res 70:99-108
Boros, Peter; Ochando, Jordi C; Chen, Shu-Hsia et al. (2010) Myeloid-derived suppressor cells: natural regulators for transplant tolerance. Hum Immunol 71:1061-6