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Isolation Protocol of Mouse Monocyte-derived Dendritic Cells and Their Subsequent In Vitro Activation with Tumor Immune Complexes
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The type III pseudomonal exotoxin U activates the c-Jun NH2-terminal kinase pathway and increases human epithelial

Alayne Cuzick1, Fiona R Stirling, Susan L Lindsay

  • 1Division of Immunology, Infection and Inflammation, University of Glasgow, Western Infirmary, Glasgow G11 6NT, United Kingdom.

Infection and Immunity
|June 23, 2006
PubMed

Insights

Pseudomonas aeruginosa

Area of Science:

  • Microbiology
  • Immunology
  • Cell Biology

Background:

  • Bacterial type III secretion systems (TTSS) deliver toxins that modulate host cell signaling and inflammatory responses.
  • Understanding these interactions is crucial for combating bacterial infections, particularly in the respiratory tract.

Purpose of the Study:

  • To investigate the role of Pseudomonas aeruginosa type III secreted toxins in human respiratory epithelial cell inflammatory responses.
  • To elucidate the specific pathways and mechanisms involved in host cell activation by these toxins.

Main Methods:

  • Utilized Pseudomonas aeruginosa strains with specific gene deletions in TTSS toxins.
  • Analyzed interleukin-8 (IL-8) production in human respiratory epithelial cells.
  • Investigated activation of mitogen-activated protein kinase (MAPK) pathways, including JNK and AP-1 signaling.

Main Results:

  • IL-8 production was primarily dependent on the type III secretion of exotoxin U (ExoU), a phospholipase.
  • ExoU activated the c-Jun NH(2)-terminal kinase (JNK) pathway, leading to activator protein-1 (AP-1) activation.
  • This pathway activation was dependent on ExoU's lipase activity but independent of host cell death.

Conclusions:

  • ExoU-mediated activation of the JNK/AP-1 pathway represents a novel mechanism for bacterial induction of host inflammatory responses.
  • This process may contribute to increased epithelial permeability and pathogen spread during Pseudomonas aeruginosa infections.

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