Abstract

The type VI secretion system (T6SS) is used by bacteria to deliver toxic effectors directly into target cells. Most T6SSs mediate antibacterial activities, whereas the potential anti-eukaryotic role of T6SS remains understudied. Here, we found a Vibrio T6SS that delivers two novel effectors into mammalian host immune cells. We showed that these effectors induce a pyroptotic cell death in a phagocytosis-dependent manner; we identified the NLRP3 inflammasome as being the underlying mechanism leading to the T6SS-induced pyroptosis. Moreover, we identified a compensatory T6SS-induced pathway that is activated upon inhibition of the canonical pyroptosis pathway. Genetic analyses revealed possible horizontal spread of this T6SS and its anti-eukaryotic effectors into emerging pathogens in the marine environment. Our findings reveal novel T6SS effectors that activate the host inflammasome and possibly contribute to virulence and to the emergence of bacterial pathogens.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting file

Article and author information

Author details

  1. Hadar Cohen

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  2. Noam Baram

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  3. Chaya Mushka Fridman

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  4. Liat Edry-Botzer

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    Competing interests
    The authors declare that no competing interests exist.
  5. Dor Salomon

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    For correspondence
    dorsalomon@mail.tau.ac.il
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-2009-9453
  6. Motti Gerlic

    Department of Clinical Microbiology and Immunology, Tel Aviv University, Tel Aviv, Israel
    For correspondence
    mgerlic@tauex.tau.ac.il
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-9518-1833

Funding

Israel Science Foundation (2174/22)

  • Dor Salomon
  • Motti Gerlic

Israel Science Foundation (920/17)

  • Dor Salomon
  • Motti Gerlic

Tel Aviv University Recanati

  • Dor Salomon
  • Motti Gerlic

Clore Israel Foundation

  • Chaya Mushka Fridman

Manna Center Program, Tel Aviv University

  • Chaya Mushka Fridman

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Reviewing Editor

  1. Carla V Rothlin, Yale University, United States

Ethics

Animal experimentation: This study was performed in strict accordance with the recommendations in the Guide for the Care and Use of Laboratory Animals of the National Institutes of Health. All of the animals were handled according to approved institutional animal care and use committee (IACUC) protocols of Tel Aviv University. The protocol was approved by the Committee on the Ethics of Animal Experiments of Tel Aviv University (Permit Number: 01-20-072).Experiments were performed according to the guidelines of the Institute's Animal Ethics Committees.

Version history

  1. Preprint posted: August 12, 2022 (view preprint)
  2. Received: August 17, 2022
  3. Accepted: August 24, 2022
  4. Accepted Manuscript published: September 26, 2022 (version 1)
  5. Version of Record published: October 7, 2022 (version 2)

Copyright

© 2022, Cohen et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Hadar Cohen
  2. Noam Baram
  3. Chaya Mushka Fridman
  4. Liat Edry-Botzer
  5. Dor Salomon
  6. Motti Gerlic
(2022)
Post-phagocytosis activation of NLRP3 inflammasome by two novel T6SS effectors
eLife 11:e82766.
https://doi.org/10.7554/eLife.82766

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https://doi.org/10.7554/eLife.82766