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.

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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.

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.

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.

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    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.

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    ACK1 and BRK non-receptor tyrosine kinase deficiencies are associated with familial systemic lupus and involved in efferocytosis

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    Systemic lupus erythematosus (SLE) is an autoimmune disease, the pathophysiology and genetic basis of which are incompletely understood. Using a forward genetic screen in multiplex families with SLE, we identified an association between SLE and compound heterozygous deleterious variants in the non-receptor tyrosine kinases (NRTKs) ACK1 and BRK. Experimental blockade of ACK1 or BRK increased circulating autoantibodies in vivo in mice and exacerbated glomerular IgG deposits in an SLE mouse model. Mechanistically, NRTKs regulate activation, migration, and proliferation of immune cells. We found that the patients’ ACK1 and BRK variants impair efferocytosis, the MERTK-mediated anti-inflammatory response to apoptotic cells, in human induced pluripotent stem cell (hiPSC)-derived macrophages, which may contribute to SLE pathogenesis. Overall, our data suggest that ACK1 and BRK deficiencies are associated with human SLE and impair efferocytosis in macrophages.