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Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria
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Published on: September 16, 2013

Cellular activating properties and morphology of membrane-bound and purified meningococcal lipopolysaccharide

A Bjerre1, B Brusletto, E Rosenqvist

  • 1Department of Pediatrics, Ullevål University Hospital, Oslo, Norway. a.k.bjerre@ioks.uio.no

Journal of Endotoxin Research
|August 25, 2001
PubMed

Insights

Native outer membrane vesicles (nOMV) from Neisseria meningitidis, like purified lipopolysaccharides (LPS), strongly activate immune cells. Depleted OMV (dOMV) showed minimal immune response, indicating LPS is key to meningococcal pathogenesis.

Area of Science:

  • Immunology
  • Microbiology
  • Biochemistry

Background:

  • Neisseria meningitidis causes severe meningitis and sepsis.
  • Disease severity correlates with plasma lipopolysaccharide (LPS) levels.
  • LPS is released via outer membrane vesicles (OMVs).

Purpose of the Study:

  • Compare biological activities of native OMVs (nOMV), purified N. meningitidis LPS (Nm-LPS), and LPS-depleted OMV (dOMV).
  • Investigate the role of LPS in OMV-mediated immune activation.

Main Methods:

  • Quantified LPS in nOMV using KDO spectrophotometry and SDS-PAGE.
  • Assessed morphology via transmission electron microscopy.
  • Measured biological reactivity using Limulus amoebocyte lysate (LAL) assay, monocyte assays, and whole blood models measuring TNF-alpha, IL-6, and monocyte procoagulant activity (PCA).

Main Results:

  • nOMV and purified Nm-LPS induced dose-dependent immune responses (TNF-alpha, IL-6, PCA).
  • dOMV induced minimal responses, highlighting LPS's role.
  • LAL activity was higher for nOMV than for Nm-LPS.
  • Anti-CD14 antibody significantly reduced cellular responses to nOMV and Nm-LPS.

Conclusions:

  • N. meningitidis OMVs activate immune cells similarly to purified LPS.
  • LPS is the primary driver of OMV-induced immune responses.
  • CD14 is crucial for mediating cellular responses to both nOMV and Nm-LPS.

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