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Outer membrane protein A (OmpA), peptidoglycan-associated lipoprotein (PAL), and murein lipoprotein (MLP) are

J Hellman1, H S Warren

  • 1Department of Anesthesia and Critical Care, Massachusetts General Hospital, Charlestown, MA, USA. jhellman@partners.org

Journal of Endotoxin Research
|August 25, 2001
PubMed

Insights

Gram-negative bacteria outer membrane proteins (OMPs) like OmpA, PAL, and MLP are released with LPS during sepsis. These proteins, associated with LPS, circulate in septic blood, indicating a potential diagnostic marker for Gram-negative sepsis.

Area of Science:

  • Microbiology
  • Immunology
  • Biochemistry

Background:

  • Escherichia coli incubated in human serum release complexes of outer membrane proteins (OMPs) and lipopolysaccharide (LPS).
  • Key OMPs identified include outer membrane protein A (OmpA), peptidoglycan-associated lipoprotein (PAL), and murein lipoprotein (MLP), conserved in Gram-negative bacteria.
  • These OMPs are recognized by IgG in antisera against rough bacterial strains like E. coli J5 (J5 IgG).

Purpose of the Study:

  • To investigate the release and circulation of OmpA, PAL, and MLP in a rat wound infection model of sepsis.
  • To determine if these OMPs form complexes with LPS during experimental Gram-negative sepsis.

Main Methods:

  • Plasma was collected from rats with E. coli O18 sepsis.
  • LPS was affinity-purified using a monoclonal antibody.
  • Plasma filtrates were incubated with J5 IgG conjugated to magnetic beads.
  • Purified samples were analyzed for OMPs using immunoblotting.

Main Results:

  • OmpA, PAL, and MLP were released and found in complexes with LPS in septic rat blood.
  • PAL was consistently detected in samples purified using J5 IgG.
  • The findings confirm the release and circulation of these OMPs during experimental Gram-negative sepsis.

Conclusions:

  • OmpA, PAL, and MLP are released and circulate in the bloodstream during experimental Gram-negative sepsis.
  • A significant portion of these released OMPs are tightly associated with LPS.
  • These findings suggest potential roles for these OMP-LPS complexes in sepsis pathogenesis or as diagnostic indicators.

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