Priming exposures to lipopolysaccharides do not affect the induction of Polycomb target genes upon re-exposure

PLoS One. 2020 Apr 14;15(4):e0231498. doi: 10.1371/journal.pone.0231498. eCollection 2020.

Abstract

The Polycomb group (PcG) proteins are chromatin factors underlying the process of transcriptional memory to preserve developmental decisions and keep cellular identities. However, not only developmental signals need to be memorized and thus maintained during the life of an organism. For host protection against pathogens, also a memory of previous exposures to an immunogenic stimulus is crucial to mount a more protective immune response upon re-exposure. The antigen-specific adaptive immunity in vertebrates is an example of such a memory to previous immunogenic stimulation. Recently, adaptive characteristics were also attributed to innate immunity, which was classically seen to lack memory. However, the mechanistic details of an adaptive innate immune response are yet to be fully understood and chromatin-based epigenetic mechanisms seem to play an important role in this phenomenon. Possibly, PcG proteins can contribute to such an epigenetic innate immune memory. In this study, we analyzed whether the PcG system can mediate a transcriptional memory of exposure to lipopolysaccharides (LPS). To this end, various forms of LPS pre-treatment were applied to reporter cells and expression kinetics of PcG target genes were analyzed after a second LPS exposure. Neither single nor multiple LPS pre-treatment affected the induction of endogenous LPS-responsive transcripts upon re-exposure. Altogether, our extensive analyses did not provide any evidence for a PcG system-mediated memory of LPS stimulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptive Immunity / genetics
  • Adaptive Immunity / immunology
  • Animals
  • Cell Line
  • Chromatin / genetics
  • Drosophila / immunology
  • Drosophila / metabolism
  • Drosophila Proteins / metabolism
  • Epigenesis, Genetic / genetics
  • Immunity, Innate / genetics
  • Immunity, Innate / immunology
  • Immunologic Memory / genetics*
  • Immunologic Memory / immunology
  • Lipopolysaccharides / genetics
  • Lipopolysaccharides / immunology
  • Polycomb-Group Proteins / genetics*
  • Polycomb-Group Proteins / immunology*
  • Polycomb-Group Proteins / metabolism

Substances

  • Chromatin
  • Drosophila Proteins
  • Lipopolysaccharides
  • Polycomb-Group Proteins

Grants and funding

The research of MG, GA and RP was supported by the ETH Zurich (www.ethz.ch) and an SNF Sinergia grant (CRSII3_160766) (www.snf.ch). MG received a fellowship from the German Academic Scholarship Foundation (www.studienstiftung.de). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.