LPS from Neisseria meningitidis is crucial for inducing monocyte- and microparticle-associated tissue factor activity but not for tissue factor expression

Innate Immun. 2012 Aug;18(4):580-91. doi: 10.1177/1753425911428230. Epub 2011 Dec 16.

Abstract

Neisseria meningitidis causes sepsis with coagulopathy. The present study evaluated the tissue factor (TF)-inducing capacity of bacterial LPS in different presentation forms, i.e. membrane-bound LPS versus purified LPS, and of non-LPS components of N. meningitidis. By using a wild-type N. meningitidis, a mutant N. meningitidis lacking LPS (LPS-deficient N. meningitidis), purified LPS from N. meningitidis and Escherichia coli, we measured TF-expression and TF-activity on human monocytes and microparticles (MPs). The effect of TF-modulators, such as phosphatidylserine (PS), tissue factor pathway inhibitor (TFPI) and recombinant IL-10 (rhIL-10) was investigated. In plasmas from meningococcal patients, fibrinopeptide A (FPA), LPS and IL-10 were quantified. Monocytes and MPs exposed to purified LPS or wild-type N. meningitidis had much higher TF-activity than monocytes and MPs exposed to LPS-deficient N. meningitidis (clot formation assay). Incubation with wild-type N. meningitidis, but also LPS-deficient N. meningitidis, resulted in TF-expression on monocytes (flow cytometry, qRT-PCR). Increased cellular TF-activity is associated with coincident surface-exposure of PS and the number of monocytes positive for both PS and TF was significantly higher for monocytes exposed to wild-type N. meningitidis (7.6%) compared with monocytes exposed to LPS-deficient N. meningitidis (1.8%). Treatment with rhIL-10 reduced monocyte- and MP-associated TF-activity, the number of monocytes positive for both TF and PS, and microvesiculation. Patients with meningococcal septicemia had significantly higher levels of LPS, FPA and IL-10 than patients with distinct meningitis. Our results indicate that LPS from N. meningitidis is crucial for inducing TF-activity, but not for monocyte- and MP-associated TF-expression. TF-activity seems to require coincident expression of TF and PS on monocytes, and LPS induces such double-positive monocytes.

MeSH terms

  • Blood Coagulation / drug effects
  • Blood Coagulation / immunology
  • Cell-Derived Microparticles / drug effects
  • Cell-Derived Microparticles / immunology*
  • Cells, Cultured
  • Escherichia coli / immunology
  • Escherichia coli Infections / immunology
  • Fibrinopeptide A / metabolism
  • Gene Expression Regulation, Bacterial / drug effects
  • Humans
  • Interleukin-10 / pharmacology
  • Lipopolysaccharides / immunology*
  • Lipoproteins / pharmacology
  • Meningitis, Meningococcal / blood
  • Meningitis, Meningococcal / immunology*
  • Meningitis, Meningococcal / microbiology
  • Meningococcal Infections / blood
  • Meningococcal Infections / immunology*
  • Meningococcal Infections / microbiology
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Neisseria meningitidis, Serogroup B / immunology*
  • Neisseria meningitidis, Serogroup B / metabolism
  • Phosphatidylserines / pharmacology
  • Thromboplastin / genetics
  • Thromboplastin / metabolism*

Substances

  • Lipopolysaccharides
  • Lipoproteins
  • Phosphatidylserines
  • lipoprotein-associated coagulation inhibitor
  • Interleukin-10
  • Fibrinopeptide A
  • Thromboplastin