title: Expression of interleukin (IL)-18 and functional IL-18 receptor on human vascular endothelial cells, smooth muscle cells, and macrophages: implications for atherogenesis.
abstract: Although considerable evidence implicates the cytokine interferon (IFN)-gamma in atherogenesis, the proximal inducers and the range of sources of its expression remain unknown. This study tested the hypothesis that interleukin (IL)-18 regulates IFN-gamma expression during atherogenesis. Indeed, human atheroma in situ expressed IL-18 and elevated levels of its receptor subunits, IL-18Ralpha/beta, compared with nondiseased arterial tissue. IL-18 occurred predominantly as the mature, 18-kD form and colocalized with mononuclear phagocytes (MPhi), while endothelial cells (ECs), smooth muscle cells (SMCs), and MPhi all expressed IL-18Ralpha/beta. Correspondingly in vitro, only MPhi expressed IL-18, while all three cell types displayed the IL-18Ralpha/beta complex constitutively, exhibiting enhanced expression upon stimulation with LPS, IL-1beta, or tumor necrosis factor (TNF)-alpha. IL-18 signaling evoked effectors involved in atherogenesis, e.g., cytokines (IL-6), chemokines (IL-8), intracellular adhesion molecules (ICAM)-1, and matrix metalloproteinases (MMP-1/-9/-13), demonstrating functionality of the receptor on ECs, SMCs, and MPhi. Finally, IL-18, particularly in combination with IL-12, induced the expression of IFN-gamma in cultured MPhi and, surprisingly, in SMCs (but not in ECs). The expression of functional IL-18 and IL-18 receptor on human atheroma-associated ECs, SMCs, and MPhi, and its unexpected ability to induce IFN-gamma expression in SMCs, suggests a novel paracrine proinflammatory pathway operating during atherogenesis.
authors.affiliation: Leducq Center for Cardiovascular Research, Cardiovascular Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
authors.forename: Norbert
authors.initials: N
authors.lastname: Gerdes
authors.forename: Galina K
authors.initials: GK
authors.lastname: Sukhova
authors.forename: Peter
authors.initials: P
authors.lastname: Libby
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Reynolds
authors.forename: James L
authors.initials: JL
authors.lastname: Young
authors.forename: Uwe
authors.initials: U
authors.lastname: Schönbeck
mesh_terms: D001161:Arteriosclerosis / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D020382:Interleukin-18 / Q000096:biosynthesis* / Q000276:immunology; D053727:Interleukin-18 Receptor alpha Subunit; D008264:Macrophages / Q000276:immunology / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000276:immunology / Q000378:metabolism*; D019899:Paracrine Communication; D018123:Receptors, Interleukin / Q000096:biosynthesis* / Q000276:immunology; D053724:Receptors, Interleukin-18
chemical_list: C508572:IL18R1 protein, human; D018836:Inflammation Mediators; D020382:Interleukin-18; D053727:Interleukin-18 Receptor alpha Subunit; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; D018799:Intercellular Adhesion Molecule-1; D007371:Interferon-gamma; D008666:Metalloendopeptidases