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Published on: January 12, 2020
Intracellular Staphylococcus aureus-induced NF-κB activation and proinflammatory responses of P815 cells are mediated
Xuhua Xie1, Lili Wang1, Fengyun Gong1
1Department of Infectious Diseases, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
Abstract:
Staphylococcus aureus (S. aureus) is an important human pathogen which can cause a chronic condition with a high relapse rate despite the aggressive antimicrobial treatment. Recent studies showed that intracellular pattern recognition receptors (including NOD) in response to bacteria or bacterial products play a proinflammatory role by activating nuclear transcription factor-κB (NF-κB). But how NOD2 mediates the proinflammatory response to S. aureus in mast cells (MCs) is unclear. So, in this study, we attempted to examine the role of NOD2 in inflammatory responses of MCs to S. aureus. P815 cells (a mouse mast cell line) were cultured. Real-time PCR was used to detect the NOD2 mRNA expression in P815 cells during S. aureus infection. The siRNA against NOD2 gene was synthesized and transfected into S. aureus-infected P815 cells. By using the methods of ELISA and flow cytometry, the effects of NOD2 gene silencing on cell phagocytosis, cytokine secretion, NF-κB activation and cell apoptosis of the S. aureus-infected P815 cells were examined. It was found that S. aureus infection could increase the expression of NOD2 mRNA in P815 cells. NOD2 gene interference in P815 cells reduced the number of S. aureus engulfed by P815 cells, the level of cytokines and the activation of NF-κB. In addition, S. aureus could induce the apoptosis of P815 cells, but NOD2 gene silencing did not affect the cell apoptosis rate. Our data suggested that NOD2 plays a key role in pathogen recognition, signal transduction, and NF-κB activation in the inflammatory responses of MCs infected by S. aureus.
Insights
Staphylococcus aureus infection activates NOD2 in mast cells, increasing inflammation and pathogen recognition. Silencing NOD2 reduces these inflammatory responses but does not impact cell apoptosis.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Staphylococcus aureus (S. aureus) is a significant human pathogen causing chronic infections with high relapse rates.
- Intracellular pattern recognition receptors, like NODs, are implicated in pro-inflammatory responses via NF-κB activation.
- The specific role of NOD2 in S. aureus-induced inflammation within mast cells remains largely uncharacterized.
Purpose of the Study:
- To investigate the role of NOD2 in mediating the inflammatory responses of mast cells (MCs) upon S. aureus infection.
- To elucidate the molecular mechanisms by which NOD2 influences S. aureus recognition and subsequent inflammatory signaling in MCs.
Main Methods:
- Utilized P815 cells (a mouse mast cell line) for in vitro experiments.
- Employed Real-time PCR to quantify NOD2 mRNA expression during S. aureus infection.
- Applied siRNA-mediated gene silencing of NOD2, followed by ELISA and flow cytometry to assess phagocytosis, cytokine secretion, NF-κB activation, and apoptosis.
Main Results:
- S. aureus infection significantly upregulated NOD2 mRNA expression in P815 cells.
- NOD2 gene silencing led to decreased S. aureus phagocytosis by mast cells.
- Interference with NOD2 reduced pro-inflammatory cytokine secretion and NF-κB activation.
- NOD2 silencing did not alter the rate of S. aureus-induced mast cell apoptosis.
Conclusions:
- NOD2 plays a critical role in S. aureus recognition and subsequent inflammatory signaling in mast cells.
- NOD2 is essential for pathogen sensing, signal transduction, and NF-κB activation during S. aureus infection in MCs.
- Targeting NOD2 may offer therapeutic potential for managing S. aureus-induced inflammatory conditions.
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