Eleni Kontaki1, Dimitrios T Boumpas1, Maria Tzardi2, Ioannis A Mouzas3, Konstantinos A Papadakis3, Panayotis Verginis4. 1. a Laboratory of Autoimmunity and Inflammation , University of Crete Medical School, and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology , Heraklion , Greece. 2. b Laboratory of Cytopathology , University of Crete Medical School , Heraklion , Greece. 3. c Division of Gastroenterology , University of Crete Medical School , Heraklion , Greece , and. 4. d Division of Clinical , Experimental Surgery, & Translational Research, Biomedical Research Foundation of the Academy of Athens , Athens , Greece.
Abstract
BACKGROUND AND AIMS: Myeloid-derived suppressor cells (MDSCs) encompass a novel population of suppressor cells and a potential candidate for cell-based therapies in inflammatory diseases. Herein, we investigated their immunomodulatory properties in experimental inflammatory colitis and T cell-mediated immune responses in inflammatory bowel disease (IBD) patients. METHODS: MDSCs (defined as CD14-HLA-DR-/lowCD33+CD15+) numbers were determined in peripheral blood (PB) from IBD patients. PB MDSC function was assessed in vitro. Experimental colitis was induced upon 2,4,6-trinitrobenzene sulfonic acid (TNBS) treatment and MDSCs were characterized by flow cytometry. The in vivo suppressive potential of bone marrow (BM)-derived MDSCs (BM-MDSCs) was tested by using both depleting and adoptive transfer strategies. RESULTS: MDSCs were enriched in the periphery of IBD patients during active disease. TNBS colitis induced amplification of MDSCs, particularly of the granulocytic (Ly6G+) subset during the effector phase of disease. Of interest, BM-MDSCs potently suppressed CD4+ T cell responses under steady state but failed to control colitis-associated immune responses in vivo. Mechanistically, under the colonic inflammatory milieu MDSCs switched phenotype (decreased proportion of Gr1high and increased numbers of Gr1low) and downregulated CCAAT/enhancer-binding protein beta (CEBPβ) expression, a critical transcription factor for the suppressive function of MDSCs. In accordance with the murine data, human CD33 + CD15+ MDSCs from peripheral blood of IBD patients not only failed to suppress autologous T cell responses but instead enhanced T cell proliferation in vitro. CONCLUSIONS: Our findings demonstrate an aberrant function of MDSCs in experimental inflammatory colitis and in IBD-associated immune responses in vitro. Delineation of the mechanisms that underlie the loss of MDSCs function in IBD may provide novel therapeutic targets.
BACKGROUND AND AIMS: Myeloid-derived suppressor cells (MDSCs) encompass a novel population of suppressor cells and a potential candidate for cell-based therapies in inflammatory diseases. Herein, we investigated their immunomodulatory properties in experimental inflammatory colitis and T cell-mediated immune responses in inflammatory bowel disease (IBD) patients. METHODS: MDSCs (defined as CD14-HLA-DR-/lowCD33+CD15+) numbers were determined in peripheral blood (PB) from IBDpatients. PB MDSC function was assessed in vitro. Experimental colitis was induced upon 2,4,6-trinitrobenzene sulfonic acid (TNBS) treatment and MDSCs were characterized by flow cytometry. The in vivo suppressive potential of bone marrow (BM)-derived MDSCs (BM-MDSCs) was tested by using both depleting and adoptive transfer strategies. RESULTS: MDSCs were enriched in the periphery of IBDpatients during active disease. TNBS colitis induced amplification of MDSCs, particularly of the granulocytic (Ly6G+) subset during the effector phase of disease. Of interest, BM-MDSCs potently suppressed CD4+ T cell responses under steady state but failed to control colitis-associated immune responses in vivo. Mechanistically, under the colonic inflammatory milieu MDSCs switched phenotype (decreased proportion of Gr1high and increased numbers of Gr1low) and downregulated CCAAT/enhancer-binding protein beta (CEBPβ) expression, a critical transcription factor for the suppressive function of MDSCs. In accordance with the murine data, humanCD33 + CD15+ MDSCs from peripheral blood of IBDpatients not only failed to suppress autologous T cell responses but instead enhanced T cell proliferation in vitro. CONCLUSIONS: Our findings demonstrate an aberrant function of MDSCs in experimental inflammatory colitis and in IBD-associated immune responses in vitro. Delineation of the mechanisms that underlie the loss of MDSCs function in IBD may provide novel therapeutic targets.
Authors: Young Suk Lee; Eduardo Davila; Tianshu Zhang; Hugh P Milmoe; Stefanie N Vogel; Jonathan S Bromberg; Joseph R Scalea Journal: Innate Immun Date: 2019-01 Impact factor: 2.680