Platelet polyphosphates are proinflammatory and procoagulant mediators in vivo

Cell. 2009 Dec 11;139(6):1143-56. doi: 10.1016/j.cell.2009.11.001.


Platelets play a central role in thrombosis, hemostasis, and inflammation. We show that activated platelets release inorganic polyphosphate (polyP), a polymer of 60-100 phosphate residues that directly bound to and activated the plasma protease factor XII. PolyP-driven factor XII activation triggered release of the inflammatory mediator bradykinin by plasma kallikrein-mediated kininogen processing. PolyP increased vascular permeability and induced fluid extravasation in skin microvessels of mice. Mice deficient in factor XII or bradykinin receptors were resistant to polyP-induced leakage. PolyP initiated clotting of plasma via the contact pathway. Ablation of intrinsic coagulation pathway proteases factor XII and factor XI protected mice from polyP-triggered lethal pulmonary embolism. Targeting polyP with phosphatases interfered with procoagulant activity of activated platelets and blocked platelet-induced thrombosis in mice. Addition of polyP restored defective plasma clotting of Hermansky-Pudlak Syndrome patients, who lack platelet polyP. The data identify polyP as a new class of mediator having fundamental roles in platelet-driven proinflammatory and procoagulant disorders.

Publication types

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

MeSH terms

  • Animals
  • Blood Platelets / metabolism*
  • Bradykinin / metabolism
  • Factor XII / genetics
  • Factor XII / metabolism
  • Fibrin / metabolism
  • Hermanski-Pudlak Syndrome / metabolism
  • Humans
  • Inflammation Mediators / metabolism*
  • Mice
  • Peptide Hydrolases / metabolism
  • Plasma
  • Polyphosphates / metabolism*
  • Receptors, Bradykinin / metabolism
  • Thrombosis / metabolism


  • Inflammation Mediators
  • Polyphosphates
  • Receptors, Bradykinin
  • Factor XII
  • Fibrin
  • Peptide Hydrolases
  • Bradykinin