Platelet microparticles are internalized in neutrophils via the concerted activity of 12-lipoxygenase and secreted phospholipase A2-IIA

Proc Natl Acad Sci U S A. 2015 Jul 7;112(27):E3564-73. doi: 10.1073/pnas.1507905112. Epub 2015 Jun 23.


Platelets are anucleated blood elements highly potent at generating extracellular vesicles (EVs) called microparticles (MPs). Whereas EVs are accepted as an important means of intercellular communication, the mechanisms underlying platelet MP internalization in recipient cells are poorly understood. Our lipidomic analyses identified 12(S)-hydroxyeicosatetranoic acid [12(S)-HETE] as the predominant eicosanoid generated by MPs. Mechanistically, 12(S)-HETE is produced through the concerted activity of secreted phospholipase A2 IIA (sPLA2-IIA), present in inflammatory fluids, and platelet-type 12-lipoxygenase (12-LO), expressed by platelet MPs. Platelet MPs convey an elaborate set of transcription factors and nucleic acids, and contain mitochondria. We observed that MPs and their cargo are internalized by activated neutrophils in the endomembrane system via 12(S)-HETE. Platelet MPs are found inside neutrophils isolated from the joints of arthritic patients, and are found in neutrophils only in the presence of sPLA2-IIA and 12-LO in an in vivo model of autoimmune inflammatory arthritis. Using a combination of genetically modified mice, we show that the coordinated action of sPLA2-IIA and 12-LO promotes inflammatory arthritis. These findings identify 12(S)-HETE as a trigger of platelet MP internalization by neutrophils, a mechanism highly relevant to inflammatory processes. Because sPLA2-IIA is induced during inflammation, and 12-LO expression is restricted mainly to platelets, these observations demonstrate that platelet MPs promote their internalization in recipient cells through highly regulated mechanisms.

Keywords: 12-lipoxygenase; microparticles; neutrophils; phospholipase A2; platelets.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / metabolism
  • Animals
  • Arachidonate 12-Lipoxygenase / genetics
  • Arachidonate 12-Lipoxygenase / metabolism*
  • Arthritis, Experimental / genetics
  • Arthritis, Experimental / metabolism
  • Arthritis, Rheumatoid / genetics
  • Arthritis, Rheumatoid / metabolism
  • Blood Platelets / enzymology
  • Blood Platelets / metabolism*
  • Cell Line
  • Cell-Derived Microparticles / enzymology
  • Cell-Derived Microparticles / metabolism*
  • Cell-Derived Microparticles / ultrastructure
  • Cells, Cultured
  • Endocytosis
  • Group II Phospholipases A2 / genetics
  • Group II Phospholipases A2 / metabolism*
  • Humans
  • Immunoblotting
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Microscopy, Confocal
  • Microscopy, Electron
  • Mitochondria / metabolism
  • Mitochondria / ultrastructure
  • Neutrophils / metabolism*
  • Neutrophils / ultrastructure
  • RNA / genetics
  • RNA / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Synovial Fluid / metabolism


  • 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid
  • RNA
  • Arachidonate 12-Lipoxygenase
  • Group II Phospholipases A2