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Experimental Infection with Listeria monocytogenes as a Model for Studying Host Interferon-γ Responses
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Different epithelial cell response to membrane vesicles produced by Listeria monocytogenes cultured with or without

So-Hyun Jun1, Taewon Lee2, Je-Chul Lee1

  • 1Department of Microbiology, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.

Microbial Pathogenesis
|May 24, 2019
PubMed

Insights

Salt stress alters Listeria monocytogenes membrane vesicles (MVs), impacting their ability to induce inflammatory responses in colon cells. MVs from unstressed bacteria increased cytokine gene expression more than those from stressed bacteria.

Area of Science:

  • Microbiology
  • Immunology
  • Cell Biology

Background:

  • Listeria monocytogenes, a pathogen causing listeriosis, produces membrane vesicles (MVs) in vitro.
  • Previous research established the capacity of L. monocytogenes to generate MVs.

Purpose of the Study:

  • To investigate how MVs from L. monocytogenes, cultured under salt stress, influence cytotoxicity and pro-inflammatory responses in Caco-2 colon epithelial cells.
  • To compare the effects of MVs produced with and without salt stress.

Main Methods:

  • Purification of MVs from wild-type L. monocytogenes and a ΔsigB mutant strain, cultured with or without salt stress.
  • Treatment of Caco-2 cells with purified MVs.
  • Assessment of Caco-2 cell viability, and gene expression analysis for pro-inflammatory cytokines and chemokines.
  • Treatment of MVs with lysozyme or ethylenediaminetetraacetic acid (EDTA) to investigate the role of MV components.

Main Results:

  • MVs from both wild-type and ΔsigB mutant strains did not decrease Caco-2 cell viability, irrespective of salt stress during bacterial culture.
  • Both types of MVs stimulated pro-inflammatory cytokine and chemokine gene expression in Caco-2 cells.
  • MVs from bacteria cultured without salt stress induced significantly higher expression of pro-inflammatory cytokine genes compared to those from salt-stressed bacteria.
  • Conversely, MVs from salt-stressed bacteria led to significantly higher expression of chemokine genes.
  • Lysozyme or EDTA treatment partially inhibited the expression of interleukin (IL)-1β and IL-8 genes induced by intact MVs.

Conclusions:

  • Salt stress modifies L. monocytogenes MVs, leading to differential pro-inflammatory responses in host cells.
  • The composition or structure of MVs is affected by salt stress, influencing their interaction with host cells.
  • These findings highlight the role of environmental factors in shaping the immunomodulatory potential of bacterial MVs.
Keywords:
Cell viabilityListeria monocytogenesMembrane vesiclesPro-inflammatory cytokinesSalt stress

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