Regulation of macrophage procoagulant responses by the tissue factor cytoplasmic domain in endotoxemia

Blood. 2007 Jun 15;109(12):5251-9. doi: 10.1182/blood-2006-10-051334. Epub 2007 Mar 1.

Abstract

Tissue factor (TF) is the primary initiator of coagulation, and the TF pathway mediates signaling through protease-activated receptors (PARs). In sepsis, TF is up-regulated as part of the proinflammatory response in lipopolysaccharide (LPS)-stimulated monocytes leading to systemic coagulation activation. Here we demonstrate that TF cytoplasmic domain-deleted (TF(Delta CT)) mice show enhanced and prolonged systemic coagulation activation relative to wild-type upon LPS challenge. However, TF(Delta CT) mice resolve inflammation earlier and are protected from lethality independent of changes in coagulation. Macrophages from LPS-challenged TF(Delta CT) mice or LPS-stimulated, in vitro-differentiated bone marrow-derived macrophages show increased TF mRNA and functional activity relative to wild-type, identifying up-regulation of macrophage TF expression as a possible cause for the increase in coagulation of TF(Delta CT) mice. Increased TF expression of TF(Delta CT) macrophages does not require PAR2 and is specific for toll-like receptor, but not interferon gamma receptor, signaling. The presence of the TF cytoplasmic domain suppresses ERK1/2 phosphorylation that is reversed by p38 inhibition leading to enhanced TF expression specifically in wild-type but not TF(Delta CT) mice. The present study demonstrates a new role of the TF cytoplasmic domain in an autoregulatory pathway that controls LPS-induced TF expression in macrophages and procoagulant responses in endotoxemia.

Publication types

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

MeSH terms

  • Animals
  • Blood Coagulation*
  • Cytoplasm / chemistry
  • Endotoxemia / blood*
  • Endotoxemia / chemically induced
  • Lipopolysaccharides / pharmacology
  • Macrophages / physiology*
  • Mice
  • Mice, Knockout
  • Mice, Mutant Strains
  • RNA, Messenger / analysis
  • Signal Transduction
  • Thromboplastin / chemistry
  • Thromboplastin / genetics
  • Thromboplastin / physiology*

Substances

  • Lipopolysaccharides
  • RNA, Messenger
  • Thromboplastin