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Exogenous phosphatidic acid with saturated short-chain fatty acyl groups induces superoxide anion release from guinea

A Tokumura1, T Moriyama, H Minamino

  • 1Faculty of Pharmaceutical Sciences, University of Tokushima, Japan.

Biochimica Et Biophysica Acta
|January 7, 1997
PubMed

Insights

Short-chain fatty acid phosphatidates (PA) trigger superoxide anion (O2-) production in guinea pig leukocytes. PA8:0 was most effective, with mechanisms depending on PA concentration and involving protein kinases and Ca2+.

Area of Science:

  • Immunology
  • Cellular Biology
  • Biochemistry

Background:

  • Polymorphonuclear leukocytes (PMN) are critical immune cells involved in host defense.
  • Superoxide anion (O2-) production by PMN is a key component of the inflammatory response.
  • Phosphatidates (PA) are signaling lipids with potential roles in cellular activation.

Purpose of the Study:

  • To investigate the ability of short-chain fatty acid phosphatidates (PA) to induce superoxide anion (O2-) production in guinea pig PMN.
  • To characterize the mechanisms underlying PA-induced O2- production, including concentration-dependency and involvement of signaling pathways.
  • To determine the role of extracellular calcium (Ca2+) and protein kinases in these responses.

Main Methods:

  • Treatment of guinea pig peritoneal PMN with various short-chain fatty acid PAs (PA6:0, PA8:0, PA10:0, PA12:0).
  • Measurement of superoxide anion (O2-) production using spectrophotometric assays.
  • Investigation of signaling pathways using specific inhibitors (staurosporine, TMB-8, H-7) and varying extracellular Ca2+ concentrations.
  • Examination of [14C]PA8:0 metabolism in PMN.

Main Results:

  • Four species of short-chain fatty acid PAs induced sustained O2- production in PMN after a lag phase, with PA8:0 being the most potent.
  • Extracellular Ca2+ modulated O2- release, reducing it for PA10:0 and PA12:0 but not PA6:0 or PA8:0.
  • PA8:0-induced O2- production occurred via distinct mechanisms dependent on concentration: a protein kinase-dependent pathway at low concentrations (1-3 microM) and a predominant protein kinase-independent pathway at higher concentrations (≥10 microM).
  • A transient O2- production at higher concentrations (30-100 microM) was mediated by a protein kinase-dependent mechanism sensitive to H-7, followed by sustained production driven by the protein kinase-independent pathway.

Conclusions:

  • Short-chain fatty acid phosphatidates directly stimulate O2- production in PMN through multiple concentration-dependent mechanisms.
  • Protein kinase-dependent and -independent pathways, along with extracellular Ca2+, play significant roles in regulating PA-induced O2- generation.
  • PA itself, rather than its metabolites like diacylglycerol, appears to be the primary inducer of O2- production via these pathways.

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