title: Interleukin-1 potently contributes to 25-hydroxycholesterol-induced synergistic cytokine production in smooth muscle cell-monocyte interactions.
abstract: OBJECTIVE
  Inflammation is essential for atherogenesis. Cholesterol, a cardiovascular risk factor, may activate inflammation in the vessel wall during this process. Cytokine-mediated interactions of human monocytes with vascular smooth muscle cells (SMCs) may perpetuate this process.
  
  
  METHODS
  We investigated the capacity of the cholesterol metabolite 25-hydroxycholesterol to induce inflammatory mediators in cocultures of freshly isolated monocytes with SMCs. We determined the role of interleukin-(IL)-1 in this interaction using qPCR, bioassays, ELISA and western blot. Cocultures with SMC to monocyte ratios from 1:4 to 1:20 were tested.
  
  
  RESULTS
  In separate SMC and monocyte cultures (monocultures) 25-hydroxycholesterol only poorly activated IL-1, IL-6 and MCP-1 production, whereas LPS stimulated much higher cytokine levels than unstimulated cultures. In contrast, cocultures of SMCs and monocytes stimulated with 25-hydroxycholesterol produced hundredfold higher cytokine levels than the corresponding monocultures. Blocking experiments with IL-1-receptor antagonist showed that IL-1 decisively contributed to the 25-hydroxycholesterol-induced synergistic IL-6 and MCP-1 production. The presence of intracellular IL-1β precursor, released mature IL-1β, and caspase-1 p10 indicated that the inflammasome was involved in this process. Determination of IL-1-mRNA in Transwell experiments indicated that the monocytes are the major source of IL-1, which subsequently activates the SMCs, the primary source of IL-6 in the coculture.
  
  
  CONCLUSIONS
  Taken together, these interactions between local vessel wall cells and invading monocytes may multiply cholesterol-triggered inflammation in the vessel wall, and IL-1 may play a key role in this process. The data also indicate that lower cholesterol levels than expected from monocultures may suffice to initiate inflammation in the tissue.
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Hang
authors.initials: H
authors.lastname: Fu
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Spieler
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Großmann
authors.affiliation: Institut für Medizinische Immunologie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Dagmar
authors.initials: D
authors.lastname: Riemann
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Marie
authors.initials: M
authors.lastname: Larisch
authors.affiliation: Zentrum für Medizinische Grundlagenforschung, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Hiebl
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Schlecht
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Jaschke
authors.affiliation: Universitätsklinik und Poliklinik für Herz- und Thoraxchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Babett
authors.initials: B
authors.lastname: Bartling
authors.affiliation: Universitätsklinik und Poliklinik für Herz- und Thoraxchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Britt
authors.initials: B
authors.lastname: Hofmann
authors.affiliation: Institut für Medizinische Epidemiologie, Biometrie und Informatik; Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Unverzagt
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Koch
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Pilowski
authors.affiliation: Universitätsklinik und Poliklinik für Herz- und Thoraxchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Simm
authors.affiliation: Universitätsklinik und Poliklinik für Herz- und Thoraxchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Rolf-Edgar
authors.initials: RE
authors.lastname: Silber
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Gielen
authors.affiliation: Institut für Medizinische Immunologie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Barbara
authors.initials: B
authors.lastname: Seliger
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Schlitt
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Ebelt
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Müller-Werdan
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Buerke
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany.
authors.forename: Karl
authors.initials: K
authors.lastname: Werdan
authors.affiliation: Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. Electronic address: Harald.Loppnow@uk-halle.de.
authors.forename: Harald
authors.initials: H
authors.lastname: Loppnow
mesh_terms: D050197:Atherosclerosis / Q000378:metabolism; D015153:Blotting, Western; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis; D018920:Coculture Techniques; D016207:Cytokines / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism*; D007113:Immunity, Innate; D007249:Inflammation; D053583:Interleukin-1beta / Q000378:metabolism*; D015850:Interleukin-6 / Q000096:biosynthesis; D009000:Monocytes / Q000166:cytology* / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology*; D016133:Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: C111835:CCL2 protein, human; D018932:Chemokine CCL2; D016207:Cytokines; D006888:Hydroxycholesterols; D053583:Interleukin-1beta; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; C007997:25-hydroxycholesterol
keywords: Atherogenesis; Cell interaction; Cholesterol; Inflammasome; Innate immunity; Interleukin; Monocytes; Smooth muscle cells