title: A GMCSF and IL-15 fusokine leads to paradoxical immunosuppression in vivo via asymmetrical JAK/STAT signaling through the IL-15 receptor complex.
abstract: We hypothesized that a granulocyte macrophage colony-stimulating factor (GMCSF) and interleukin 15 (IL-15) fusokine (GIFT15) would possess greater immune-stimulatory properties than their combined use. Unexpectedly, tumor cells engineered to secrete GIFT15 protein led to suppression of natural killer (NK) and NKT-cell recruitment in vivo, suggesting an unanticipated immune-suppressive effect. We found GIFT15 to have pleiotropic effects on an array of immune-competent cells. Among these, macrophages treated with GIFT15 secrete de novo the tissue inhibitor of metalloproteinase-2 (TIMP-2); activated matrix metalloproteinase-2 (MMP-2); transforming growth factor-beta (TGF-beta); as well as vascular endothelial growth factor (VEGF). We show that the GIFT15 fusokine has increased affinity for the alpha chain component of the IL-15R, leading to aberrant signaling through the beta chain manifested by the hyperphosphorylation of STAT3 both in macrophages and splenocytes. Suppression of common gamma chain-mediated STAT5 phosphorylation and blockade of the IL-15-dependent IFN-gamma response in mouse splenocytes were also observed. We tested GIFT15 as an immunosuppressor and demonstrated that it allowed engraftment of allogeneic B16F0 and human xenograft U87GM glioma cells in immunocompetent mice. Thus, GIFT15 defines a new class of fusokine that mediates proangiogenic and immunosuppressive effects via aberrant signaling by the IL-15R in lymphomyeloid cells.
authors.affiliation: Montreal Centre for Experimental Therapeutics in Cancer, Jewish General Hospital, McGill University, Montreal, QC, Canada.
authors.forename: Moutih
authors.initials: M
authors.lastname: Rafei
authors.forename: Jian Hui
authors.initials: JH
authors.lastname: Wu
authors.forename: Borhane
authors.initials: B
authors.lastname: Annabi
authors.forename: Laurence
authors.initials: L
authors.lastname: Lejeune
authors.forename: Moïra
authors.initials: M
authors.lastname: François
authors.forename: Jacques
authors.initials: J
authors.lastname: Galipeau
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D016207:Cytokines; D005260:Female; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000276:immunology / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D019409:Interleukin-15 / Q000276:immunology / Q000378:metabolism; D053612:Janus Kinases / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000378:metabolism; D008213:Lymphocyte Activation; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D053647:Receptors, Interleukin-15 / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D013602:T-Lymphocytes, Cytotoxic / Q000378:metabolism
chemical_list: D016207:Cytokines; C518130:GIFT15 protein; D019409:Interleukin-15; D053647:Receptors, Interleukin-15; D011993:Recombinant Fusion Proteins; D050791:STAT Transcription Factors; D007371:Interferon-gamma; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D053612:Janus Kinases