Elevated pre-activation basal level of nuclear NF-κB in native macrophages accelerates LPS-induced translocation of cytosolic NF-κB into the cell nucleus

• Published in: Scientific reports Vol. 9; no. 1; p. 4563
• Main Authors: Bagaev, Alexander V., Garaeva, Anastasiya Y., Lebedeva, Ekaterina S., Pichugin, Alexey V., Ataullakhanov, Ravshan I., Ataullakhanov, Fazly I.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 14.03.2019; Nature Publishing Group
• Subjects: 14; 14/19; 631/114/2391; 631/250/516/1909; 64/60; 96/1; 96/31; 96/95; Bacterial diseases; Bone marrow; Cell activation; Cell Line; Cell lines; Cell Nucleus - metabolism; Cytosol - metabolism; Humanities and Social Sciences; Immune response; Immune system; Innate immunity; Kinetics; Lipopolysaccharides; Lipopolysaccharides - immunology; Macrophage Activation - immunology; Macrophages; Macrophages - immunology; Macrophages - metabolism; Mathematical models; Models, Biological; multidisciplinary; NF-kappa B - metabolism; NF-κB protein; Nuclear transport; Peritoneum; Phosphorylation; Protein Transport; Science; Science (multidisciplinary); Signal Transduction; TLR4 protein; Toll-Like Receptor 4 - agonists; Toll-Like Receptor 4 - metabolism; Toll-like receptors; Transcription activation; Translocation; Ubiquitination
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-36052-5

Signaling via Toll-like receptor 4 (TLR4) in macrophages constitutes an essential part of the innate immune response to bacterial infections. Detailed and quantified descriptions of TLR4 signal transduction would help to understand and exploit the first-line response of innate immune defense. To date, most mathematical modelling studies were performed on transformed cell lines. However, properties of primary macrophages differ significantly. We therefore studied TLR4-dependent activation of NF-κB transcription factor in bone marrow-derived and peritoneal primary macrophages. We demonstrate that the kinetics of NF-κB phosphorylation and nuclear translocation induced by a wide range of bacterial lipopolysaccharide (LPS) concentrations in primary macrophages is much faster than previously reported for macrophage cell lines. We used a comprehensive combination of experiments and mathematical modeling to understand the mechanisms of this rapid response. We found that elevated basal NF-κB in the nuclei of primary macrophages is a mechanism increasing native macrophage sensitivity and response speed to the infection. Such pre-activated state of macrophages accelerates the NF-κB translocation kinetics in response to low agonist concentrations. These findings enabled us to refine and construct a new model combining both NF-κB phosphorylation and translocation processes and predict the existence of a negative feedback loop inactivating phosphorylated NF-κB.