Hang Fu1, Florian Spieler1, Julia Großmann1, Dagmar Riemann2, Marie Larisch1, Bernhard Hiebl3, Kathrin Schlecht1, Carolin Jaschke1, Babett Bartling4, Britt Hofmann4, Susanne Unverzagt5, Susanne Koch1, Claudia Pilowski1, Andreas Simm4, Rolf-Edgar Silber4, Stephan Gielen1, Barbara Seliger2, Axel Schlitt1, Henning Ebelt1, Ursula Müller-Werdan1, Michael Buerke1, Karl Werdan1, Harald Loppnow6. 1. Universitätsklinik und Poliklinik für Innere Medizin III, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. 2. Institut für Medizinische Immunologie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. 3. Zentrum für Medizinische Grundlagenforschung, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. 4. Universitätsklinik und Poliklinik für Herz- und Thoraxchirurgie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. 5. Institut für Medizinische Epidemiologie, Biometrie und Informatik; Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, Halle (Saale), Germany. 6. 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.
Abstract
OBJECTIVES: 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. CONCLUSION: 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.
OBJECTIVES: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-1p10 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. CONCLUSION: 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: Hang Fu; Mohamad Alabdullah; Julia Großmann; Florian Spieler; Reem Abdosh; Veronika Lutz; Katrin Kalies; Kai Knöpp; Max Rieckmann; Susanne Koch; Michel Noutsias; Claudia Pilowski; Jochen Dutzmann; Daniel Sedding; Stefan Hüttelmaier; Kazuo Umezawa; Karl Werdan; Harald Loppnow Journal: Cell Death Dis Date: 2019-11-21 Impact factor: 8.469