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Outer membrane protein A of Escherichia coli O157:H7 stimulates dendritic cell activation

Alfredo G Torres1, Yongguo Li, Christopher B Tutt

  • 1Department of Microbiology and Immunology, 301 University Blvd., University of Texas Medical Branch, Galveston, Texas 77555-1070, USA. altorres@utmb.edu

Infection and Immunity
|April 20, 2006
PubMed

Insights

Outer membrane protein A (OmpA) from enterohemorrhagic E. coli stimulates dendritic cells to produce cytokines like IL-1, IL-10, and IL-12. However, OmpA was not essential for bacterial binding or immune cell migration across intestinal cells.

Area of Science:

  • Immunology
  • Microbiology
  • Cell Biology

Background:

  • Outer membrane protein A (OmpA) is a crucial protein in the outer membrane of Gram-negative bacteria, including Escherichia coli.
  • In enterohemorrhagic E. coli (EHEC) O157:H7, OmpA is implicated in interactions with intestinal cells and modulating immune responses during infection.

Purpose of the Study:

  • To investigate the role of EHEC OmpA in stimulating cytokine production by dendritic cells (DCs).
  • To assess the impact of OmpA on DC migration across intestinal epithelial cells.

Main Methods:

  • Murine dendritic cells were treated with EHEC OmpA to analyze cytokine secretion (IL-1, IL-10, IL-12).
  • The study examined the OmpA-mediated effect independently of Toll-like receptor 4 (TLR4).
  • DC migration and cytokine production by Caco-2 intestinal cells were evaluated.

Main Results:

  • EHEC OmpA dose-dependently induced secretion of IL-1, IL-10, and IL-12 from murine DCs, independent of TLR4.
  • DCs showed varied responses to OmpA, and OmpA-specific antibodies enhanced cytokine secretion.
  • OmpA was necessary for EHEC binding to Caco-2 cells but not for cytokine induction by these cells or DC migration.

Conclusions:

  • EHEC OmpA plays a role in activating dendritic cells to produce key cytokines, suggesting involvement in the early immune response to infection.
  • While OmpA influences DC cytokine production, other EHEC surface factors may also contribute to the immune stimulation.
  • OmpA's role in bacterial adhesion to the intestinal epithelium is confirmed, but it does not directly mediate DC migration across it.

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