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Grote K, Nicolai M, Schubert U, Schieffer B, Troidl C, Preissner KT, Bauer S, Fischer S. Extracellular Ribosomal RNA Acts Synergistically with Toll-like Receptor 2 Agonists to Promote Inflammation. Cells 2022; 11:cells11091440. [PMID: 35563745 PMCID: PMC9103112 DOI: 10.3390/cells11091440] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 02/04/2023] Open
Abstract
Self-extracellular RNA (eRNA), which is released under pathological conditions from damaged tissue, has recently been identified as a new alarmin and synergistic agent together with toll-like receptor (TLR)2 ligands to induce proinflammatory activities of immune cells. In this study, a detailed investigation of these interactions is reported. The macrophage cell line J774 A.1 or C57 BL/6 J wild-type mice were treated with 18S rRNA and different TLR2 agonists. Gene and protein expression of tumor necrosis factor (Tnf)-α; interleukin (Il)-1β, Il-6; or monocyte chemoattractant protein (Mcp)-1 were analyzed and furthermore in vitro binding studies to TLR2 were performed. The TLR2/TLR6-agonist Pam2 CSK4 (Pam2) together with 18S rRNA significantly increased the mRNA expression of inflammatory genes and the release of TNF-α from macrophages in a TLR2- and nuclear factor kappa B (NF-κB)-dependent manner. The injection of 18S rRNA/Pam2 into mice increased the cytokine levels of TNF-α, IL-6, and MCP-1 in the peritoneal lavage. Mechanistically, 18S rRNA built complexes with Pam2 and thus enhanced the affinity of Pam2 to TLR2. These results indicate that the alarmin eRNA, mainly consisting of rRNA, sensitizes TLR2 to enhance the innate immune response under pathological conditions. Thus, rRNA might serve as a new target for the treatments of bacterial and viral infections.
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Affiliation(s)
- Karsten Grote
- Cardiology & Angiology, Medical School, Philipps-University, 35043 Marburg, Germany; (K.G.); (B.S.)
| | - Marina Nicolai
- Institute of Immunology, Medical School, Philipps-University, 35043 Marburg, Germany; (M.N.); (S.B.)
| | - Uwe Schubert
- Institute of Biochemistry, Medical School, Justus-Liebig-University, 35392 Giessen, Germany;
| | - Bernhard Schieffer
- Cardiology & Angiology, Medical School, Philipps-University, 35043 Marburg, Germany; (K.G.); (B.S.)
| | - Christian Troidl
- Medical Clinic I, Cardiology/Angiology, Campus Kerckhoff, Justus-Liebig-University, 61231 Bad Nauheim, Germany;
- Department Cardiology, Kerckhoff-Heart Research Institute, Medical School, Justus-Liebig-University, 35392 Giessen, Germany;
| | - Klaus T. Preissner
- Department Cardiology, Kerckhoff-Heart Research Institute, Medical School, Justus-Liebig-University, 35392 Giessen, Germany;
| | - Stefan Bauer
- Institute of Immunology, Medical School, Philipps-University, 35043 Marburg, Germany; (M.N.); (S.B.)
| | - Silvia Fischer
- Institute of Biochemistry, Medical School, Justus-Liebig-University, 35392 Giessen, Germany;
- Department Cardiology, Kerckhoff-Heart Research Institute, Medical School, Justus-Liebig-University, 35392 Giessen, Germany;
- Correspondence:
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