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Published on: November 9, 2019
Modulation of proinflammatory NF-κB signaling by ectromelia virus in RAW 264.7 murine macrophages
Justyna Struzik1, Lidia Szulc-Dąbrowska, Diana Papiernik
1Department of Preclinical Sciences, Faculty of Veterinary Medicine, Warsaw University of Life Sciences - SGGW, Ciszewskiego 8, 02-786, Warsaw, Poland.
Abstract:
Macrophages are antigen-presenting cells (APCs) that play a crucial role in the innate immune response and may be involved in both clearance and spread of viruses. Stimulation of macrophages via Toll-like receptors (TLRs) results in activation of nuclear factor κB (NF-κB) and synthesis of proinflammatory cytokines. In this work, we show modulation of proinflammatory NF-κB signaling by a member of the family Poxviridae, genus Orthopoxvirus--ectromelia virus (ECTV)--in RAW 264.7 murine macrophages. ECTV interfered with p65 NF-κB nuclear translocation induced by TLR ligands such as lipopolysaccharide (LPS) (TLR4), polyinosinic-polycytidylic acid (poly(I:C)) (TLR3) and diacylated lipopeptide Pam2CSK4 (TLR2/6). We observed that ECTV modulates phosphorylation of Ser32 of inhibitor of κB (IκBα) and Ser536 of p65. Interference of ECTV with TLR signaling pathways implied that proinflammatory cytokine synthesis was inhibited. Our studies provide new insights into the strategies of proinflammatory signaling modulation by orthopoxviruses during their replication cycle in immune cells. Understanding important immune interactions between viral pathogens and APCs might contribute to the identification of drug targets and the development of vaccines.
Insights
Ectromelia virus (ECTV) disrupts key immune signaling pathways in macrophages, specifically blocking nuclear factor-kappa B (NF-κB) activation. This viral interference with Toll-like receptor (TLR) signaling inhibits the production of inflammatory cytokines, impacting the immune response to viral infection.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Macrophages are critical antigen-presenting cells (APCs) in innate immunity, influencing viral clearance and spread.
- Toll-like receptor (TLR) stimulation activates nuclear factor-kappa B (NF-κB) signaling, leading to proinflammatory cytokine synthesis.
Purpose of the Study:
- To investigate how ectromelia virus (ECTV), an orthopoxvirus, modulates NF-κB signaling in murine macrophages.
- To elucidate the mechanisms by which ECTV interferes with TLR-mediated immune responses.
Main Methods:
- Utilized RAW 264.7 murine macrophages stimulated with various TLR ligands (LPS, poly(I:C), Pam2CSK4).
- Assessed the effect of ECTV infection on p65 NF-κB nuclear translocation.
- Analyzed the phosphorylation status of IκBα and p65.
Main Results:
- ECTV infection inhibited p65 NF-κB nuclear translocation induced by TLR ligands.
- ECTV modulated the phosphorylation of IκBα (Ser32) and p65 (Ser536).
- Interference with TLR signaling led to the inhibition of proinflammatory cytokine synthesis.
Conclusions:
- ECTV employs strategies to modulate proinflammatory NF-κB signaling during replication in immune cells.
- Understanding orthopoxvirus interactions with APCs can reveal potential drug targets and vaccine development avenues.
