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Redirection of the reaction between activated protein C and a serpin to the substrate pathway

Andrey A Komissarov1, Peter A Andreasen, Paul J Declerck

  • 1Department of Chemistry, Portland State University, P. O. Box 751, Portland, OR 97207-0751, USA. akomiss@pdx.edu

Thrombosis Research
|November 30, 2007
PubMed

Insights

Targeting plasminogen activator inhibitor 1 (PAI-1) with specific antibodies can protect activated protein C (APC) from inactivation. This strategy enhances APC’s therapeutic potential in severe sepsis by neutralizing PAI-1.

Area of Science:

  • Biochemistry
  • Pharmacology
  • Immunology

Background:

  • Activated protein C (APC) is a crucial therapeutic agent for severe sepsis, but its efficacy is limited by inactivation from serine protease inhibitors (serpins).
  • Elevated levels of plasminogen activator inhibitor 1 (PAI-1), a specific serpin, are linked to poor outcomes in sepsis and disseminated intravascular coagulation.
  • Developing methods to protect APC from PAI-1 inactivation is essential for improving sepsis treatment.

Purpose of the Study:

  • To investigate intermolecular mechanisms for redirecting the reaction between PAI-1 and APC.
  • To explore the potential of neutralizing PAI-1 to enhance APC's therapeutic efficiency.

Main Methods:

  • Utilized SDS PAGE and fluorescence spectroscopy to analyze the reaction kinetics and stoichiometry.
  • Studied the effects of anti-PAI-1 monoclonal antibodies (mAbs), vitronectin, and their fragments.

Main Results:

  • Monoclonal antibodies targeting the alpha-helix F region of PAI-1 redirected 70-80% of the APC-PAI-1 reaction to the substrate pathway.
  • Vitronectin and its SMB domain enhanced the effect of mAbs but did not alter reaction stoichiometry.
  • Vitronectin increased the APC-PAI-1 reaction rate, while mAbs and the SMB domain did not.

Conclusions:

  • Ligands that bind to PAI-1's alpha-helix F can protect APC from inhibition, suggesting a therapeutic strategy.
  • The universal nature of proteinase/serpin interactions allows for similar approaches to enhance the inactivation of other serpins, preserving APC activity.
  • Targeting APC inhibitors pharmacologically offers potential therapeutic benefits in sepsis and related conditions.
Abstract

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