C1-inhibitor efficiently inhibits Escherichia coli-induced tissue factor mRNA up-regulation, monocyte tissue factor expression and coagulation activation in human whole blood

Clin Exp Immunol. 2013 Aug;173(2):217-29. doi: 10.1111/cei.12098.


Both the complement system and tissue factor (TF), a key initiating component of coagulation, are activated in sepsis, and cross-talk occurs between the complement and coagulation systems. C1-inhibitor (C1-INH) can act as a regulator in both systems. Our aim in this study was to examine this cross-talk by investigating the effects of C1-INH on Escherichia coli-induced haemostasis and inflammation. Fresh human whole blood collected in lepirudin was incubated with E. coli or ultrapurified E. coli lipopolysaccharide (LPS) in the absence or presence of C1-INH or protease-inactivated C1-INH. C3 activation was blocked by compstatin, a specific C3 convertase inhibitor. TF mRNA was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR), and TF surface expression was measured by flow cytometry. In plasma, the terminal complement complex, prothrombin F1·2 (PTF1·2) and long pentraxin 3 (PTX3) were measured by enzyme-linked immunosorbent assay (ELISA). Cytokines were analysed using a multiplex kit. C1-INH (1·25-5 mg/ml) reduced both LPS- and E. coli-induced coagulation, measured as a reduction of PTF1·2 in plasma, efficiently and dose-dependently (P < 0·05). Both LPS and E. coli induced marked up-regulation of TF mRNA levels and surface expression on whole blood monocytes. This up-regulation was reduced efficiently by treatment with C1-INH (P < 0·05). C1-INH reduced the release of PTX3 (P < 0·05) and virtually all cytokines measured (P < 0·05). Complement activation was inhibited more efficiently with compstatin than with C1-INH. C1-INH inhibited most of the other readouts more efficiently, consistent with additional non-complement-dependent effects. These results indicate that complement plays a role in activating coagulation during sepsis and that C1-INH is a broad-spectrum attenuator of the inflammatory and haemostatic responses.

Keywords: C1-inhibitor; coagulation; complement; tissue factor; whole blood.

Publication types

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

MeSH terms

  • Blood Coagulation
  • C-Reactive Protein / metabolism
  • Cells, Cultured
  • Coculture Techniques
  • Complement C1 Inactivator Proteins / genetics
  • Complement C1 Inactivator Proteins / metabolism*
  • Complement C1 Inhibitor Protein
  • Escherichia coli / immunology*
  • Female
  • Gene Expression Regulation / drug effects
  • Humans
  • Lipopolysaccharides / immunology
  • Male
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Peptide Fragments / blood
  • Prothrombin
  • RNA, Messenger / analysis
  • Sepsis / drug therapy
  • Sepsis / immunology*
  • Serum Amyloid P-Component / metabolism
  • Thromboplastin / genetics
  • Thromboplastin / metabolism*


  • Complement C1 Inactivator Proteins
  • Complement C1 Inhibitor Protein
  • Lipopolysaccharides
  • Peptide Fragments
  • RNA, Messenger
  • SERPING1 protein, human
  • Serum Amyloid P-Component
  • prothrombin fragment 1.2
  • PTX3 protein
  • Prothrombin
  • C-Reactive Protein
  • Thromboplastin