title: IFN-gamma and TNF-alpha differentially regulate immunomodulation by murine mesenchymal stem cells.
abstract: Murine mesenchymal stem cells (MSC) have the ability to inhibit allogeneic immune responses. Two different mechanisms, either cell contact-dependent or independent, have been proposed to account for this immunosuppression. The focus of this study was to elucidate the involvement of soluble suppressive factors secreted by murine MSC in an inflammatory setting, and their role in MSC immunomodulation. In a non-inflammatory environment, bone marrow derived murine MSC constitutively expressed low levels of COX-2, PGE-2, TGF-beta1 and HGF, but not IL-10, PD-1, PD-L1 or PD-L2. These MSC were able to significantly reduce alloantigen driven proliferation in mixed lymphocyte reactions as well as mitogen driven proliferation. The pro-inflammatory cytokines IFN-gamma and TNF-alpha did not ablate MSC mediated immunosuppression. MSC expression of PGE-2, IDO and PD-L1 was differentially regulated by these cytokines. COX-2 and PGE-2 expression by MSC were upregulated by both IFN-gamma and TNF-alpha, and using a biochemical inhibitor this was shown to have an essential, non-redundant role in modulating alloantigen-driven proliferation. However, the surface expression of PD-L1 was induced by IFN-gamma but not TNF-alpha and similarly functional IDO expression was only induced by IFN-gamma stimulation. Blocking studies using neutralising antibodies and biochemical antagonists revealed that while PD-L1 induction was not essential, IDO expression was a prerequisite for IFN-gamma mediated MSC immunomodulation. These data demonstrate that murine MSC expression of immunomodulatory factors dramatically changes in a pro-inflammatory environment and that IFN-gamma in particular has an important role in regulating MSC immunomodulatory factor expression.
authors.affiliation: Mucosal Immunology Laboratory, Institute of Immunology, National University of Ireland Maynooth, Maynooth, Co. Kildare, Ireland.
authors.forename: Karen
authors.initials: K
authors.lastname: English
authors.forename: Frank P
authors.initials: FP
authors.lastname: Barry
authors.forename: Ciara P
authors.initials: CP
authors.lastname: Field-Corbett
authors.forename: Bernard P
authors.initials: BP
authors.lastname: Mahon
mesh_terms: D000818:Animals; D018122:B7-1 Antigen / Q000378:metabolism; D060890:B7-H1 Antigen; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D016207:Cytokines / Q000276:immunology*; D015232:Dinoprostone / Q000378:metabolism; D005260:Female; D007155:Immunologic Factors / Q000276:immunology; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism; D007213:Indomethacin / Q000494:pharmacology; D007371:Interferon-gamma / Q000276:immunology* / Q000378:metabolism; D007959:Lymphocyte Culture Test, Mixed; D008562:Membrane Glycoproteins / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000276:immunology* / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D010455:Peptides / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology* / Q000378:metabolism
chemical_list: D018122:B7-1 Antigen; D060890:B7-H1 Antigen; C498919:Cd274 protein, mouse; D016861:Cyclooxygenase Inhibitors; D016207:Cytokines; D007155:Immunologic Factors; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D008562:Membrane Glycoproteins; D010455:Peptides; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D007213:Indomethacin