Notch signaling regulates the responses of lipopolysaccharide-stimulated macrophages in the presence of immune complexes

PLoS One. 2018 Jun 11;13(6):e0198609. doi: 10.1371/journal.pone.0198609. eCollection 2018.

Abstract

Macrophages exhibit diverse effector phenotypes depending on the stimuli and their microenvironment. Classically activated macrophages are primed with interferon (IFN)γ and stimulated with pathogen-associated molecular patterns. They produce inflammatory mediators and inflammatory cytokines, such as IL-12. In the presence of immune complexes (ICs), activated macrophages have decreased IL-12 production and increased IL-10 production and presumably act as regulatory macrophages. Notch signaling has been shown to regulate the effector functions of classically activated macrophages. In this study, we investigated whether Notch signaling is active in lipopolysaccharide (LPS)-stimulated macrophages in the presence of ICs. LPS/IC stimulation increased the level of cleaved Notch1 in murine macrophages, while IC stimulation alone did not. Delta-like 4, but not Jagged1, was responsible for generating cleaved Notch1. The activation of Notch signaling by LPS/ICs depended upon NF-κB and MEK/Erk pathway activation. Macrophages with the targeted deletion of Rbpj, which encodes a DNA-binding protein central to canonical Notch signaling, produced significantly less IL-10 upon LPS/IC stimulation. A similar impact on IL-10 production was observed when Notch signaling was inhibited with a gamma-secretase inhibitor (GSI). Defects in NF-κB p50 nuclear localization were observed in GSI-treated macrophages and in Rbpj-/- macrophages, suggesting cross-regulation between the Notch and NF-κB pathways. Transcriptomic analysis revealed that Notch signaling regulates the transcription of genes involved in the cell cycle, macrophage activation, leukocyte migration and cytokine production in LPS/IC-stimulated macrophages. Taken together, these results suggest that the Notch signaling pathway plays an important role in regulating the functions of macrophages activated by LPS and ICs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigen-Antibody Complex / pharmacology
  • Bone Marrow Cells / cytology
  • Cells, Cultured
  • Immunoglobulin J Recombination Signal Sequence-Binding Protein / deficiency
  • Immunoglobulin J Recombination Signal Sequence-Binding Protein / genetics
  • Interferon-gamma / pharmacology
  • Interleukin-10 / genetics
  • Interleukin-10 / metabolism
  • Interleukin-12 / genetics
  • Interleukin-12 / metabolism
  • Lipopolysaccharides / pharmacology*
  • Macrophages / cytology
  • Macrophages / drug effects
  • Macrophages / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Mitogen-Activated Protein Kinases / metabolism
  • NF-kappa B / metabolism
  • Receptors, Notch / metabolism*
  • Signal Transduction / drug effects*

Substances

  • Antigen-Antibody Complex
  • Immunoglobulin J Recombination Signal Sequence-Binding Protein
  • Lipopolysaccharides
  • NF-kappa B
  • Rbpj protein, mouse
  • Receptors, Notch
  • Interleukin-10
  • Interleukin-12
  • Interferon-gamma
  • Mitogen-Activated Protein Kinases

Grant support

This work was supported in part by the Thailand Research Fund (TRF grant no. BRG5880007), the Ratchadaphiseksomphot Endowment Fund (2013), Chulalongkorn University (Sci-Super 2014-023), and the grant for Chulalongkorn Research Scholars from the Ratchadaphiseksomphot Fund from Chulalongkorn University and Chulalongkorn Academic Advancement into Its 2nd Century Project to TP. WW is supported by the Thailand Research Fund through the Royal Golden Jubilee Ph.D. Program (PHD/0337/2551). PK is supported by a postdoctoral fellowship from the Ratchadaphiseksomphot Fund (The Graduate School of Chulalongkorn University).