1. Immunology and Inflammation
  2. Microbiology and Infectious Disease

Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens

  1. Shaun Steele
  2. Lauren Radlinski
  3. Sharon Taft-Benz
  4. Brunton Jason
  5. Thomas H Kawula  Is a corresponding author
  1. University of North Carolina at Chapel Hill, United States
https://doi.org/10.7554/eLife.10625
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  1. Shaun Steele
  2. Lauren Radlinski
  3. Sharon Taft-Benz
  4. Brunton Jason
  5. Thomas H Kawula
(2016)
Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens
eLife 5:e10625.
https://doi.org/10.7554/eLife.10625
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Abstract

Macrophages are myeloid-derived phagocytic cells and one of the first immune cell types to respond to microbial infections. However, a number of bacterial pathogens are resistant to the antimicrobial activities of macrophages and can grow within these cells. Macrophages have other immune surveillance roles including the acquisition of cytosolic components from multiple types of cells. We hypothesized that intracellular pathogens that can replicate within macrophages could also exploit cytosolic transfer to facilitate bacterial spread. We found that viable Francisella tularensis, as well as Salmonella enterica bacteria transferred from infected cells to uninfected macrophages along with other cytosolic material through a transient, contact dependent mechanism. Bacterial transfer occurred when the host cells exchanged plasma membrane proteins and cytosol via a trogocytosis related process leaving both donor and recipient cells intact and viable. Trogocytosis was strongly associated with infection in mice, suggesting that direct bacterial transfer occurs by this process in vivo.

Article and author information

Author details

  1. Shaun Steele

    University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    The authors declare that no competing interests exist.

  2. Lauren Radlinski

    University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    The authors declare that no competing interests exist.

  3. Sharon Taft-Benz

    University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    The authors declare that no competing interests exist.

  4. Brunton Jason

    University of North Carolina at Chapel Hill, Chapel Hill, United States
    Competing interests
    The authors declare that no competing interests exist.

  5. Thomas H Kawula

    University of North Carolina at Chapel Hill, Chapel Hill, United States
    For correspondence
    kawula@med.unc.edu
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Denise Monack, Stanford, 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 (#13-213.0) of the University of North Carolina.

Version history

  1. Received: August 5, 2015
  2. Accepted: January 22, 2016
  3. Accepted Manuscript published: January 23, 2016 (version 1)
  4. Version of Record published: February 26, 2016 (version 2)

Copyright

© 2016, Steele 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. Shaun Steele
  2. Lauren Radlinski
  3. Sharon Taft-Benz
  4. Brunton Jason
  5. Thomas H Kawula
(2016)
Trogocytosis-associated cell to cell spread of intracellular bacterial pathogens
eLife 5:e10625.
https://doi.org/10.7554/eLife.10625

Share this article

https://doi.org/10.7554/eLife.10625

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Further reading

    1. Microbiology and Infectious Disease

    Francisella tularensis enters a double membraned compartment following cell-cell transfer

    Shaun P Steele, Zach Chamberlain ... Thomas H Kawula
    Research Advance Updated

    Previously, we found that phagocytic cells ingest bacteria directly from the cytosol of infected cells without killing the initially infected cell (Steele et al., 2016). Here, we explored the events immediately following bacterial transfer. Francisella tularensis bacteria acquired from infected cells were found within double-membrane vesicles partially composed from the donor cell plasma membrane. As with phagosomal escape, the F. tularensis Type VI Secretion System (T6SS) was required for vacuole escape. We constructed a T6SS inducible strain and established conditions where this strain is trapped in vacuoles of cells infected through bacterial transfer. Using this strain we identified bacterial transfer events in the lungs of infected mice, demonstrating that this process occurs in infected animals. These data and electron microscopy analysis of the transfer event revealed that macrophages acquire cytoplasm and membrane components of other cells through a process that is distinct from, but related to phagocytosis.

    1. Immunology and Inflammation
    2. Microbiology and Infectious Disease

    Intracellular Bacteria: Catch me if you can

    Emilie Bourdonnay, Thomas Henry
    Insight

    Direct contact between host cells allows some bacteria to spread within the body without being attacked by the immune system.

    1. Immunology and Inflammation

    Downregulation of Mirlet7 miRNA family promotes Tc17 differentiation and emphysema via de-repression of RORγt

    Phillip A Erice, Xinyan Huang ... Antony Rodriguez
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    Environmental air irritants including nanosized carbon black (nCB) can drive systemic inflammation, promoting chronic obstructive pulmonary disease (COPD) and emphysema development. The let-7 microRNA (Mirlet7 miRNA) family is associated with IL-17-driven T cell inflammation, a canonical signature of lung inflammation. Recent evidence suggests the Mirlet7 family is downregulated in patients with COPD, however, whether this repression conveys a functional consequence on emphysema pathology has not been elucidated. Here, we show that overall expression of the Mirlet7 clusters, Mirlet7b/Mirlet7c2 and Mirlet7a1/Mirlet7f1/Mirlet7d, are reduced in the lungs and T cells of smokers with emphysema as well as in mice with cigarette smoke (CS)- or nCB-elicited emphysema. We demonstrate that loss of the Mirlet7b/Mirlet7c2 cluster in T cells predisposed mice to exaggerated CS- or nCB-elicited emphysema. Furthermore, ablation of the Mirlet7b/Mirlet7c2 cluster enhanced CD8+IL17a+ T cells (Tc17) formation in emphysema development in mice. Additionally, transgenic mice overexpressing Mirlet7g in T cells are resistant to Tc17 and CD4+IL17a+ T cells (Th17) development when exposed to nCB. Mechanistically, our findings reveal the master regulator of Tc17/Th17 differentiation, RAR-related orphan receptor gamma t (RORγt), as a direct target of Mirlet7 in T cells. Overall, our findings shed light on the Mirlet7/RORγt axis with Mirlet7 acting as a molecular brake in the generation of Tc17 cells and suggest a novel therapeutic approach for tempering the augmented IL-17-mediated response in emphysema.