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CRIT peptide interacts with factor B and interferes with alternative pathway activation

Kwok-Min Hui1, Bergljót Magnadóttir, Jürg A Schifferli

  • 1University Hospital Basel, Immunonephrology, Department of Research, Hebelstrasse 20, CH-4031 Basel, Switzerland. 12min@mail.hongkong.com

Biochemical and Biophysical Research Communications
|April 8, 2006
PubMed

Insights

Complement C2 receptor inhibitor trispanning (CRIT) peptide CRIT-H17 blocks alternative pathway (AP) complement activation by inhibiting factor B cleavage. This peptide shows potential for modulating AP-driven inflammatory diseases.

Area of Science:

  • Immunology
  • Complement system biology

Background:

  • Complement C2 receptor inhibitor trispanning (CRIT) targets the classical pathway (CP) C3 convertase.
  • The C-terminal peptide CRIT-H17 mimics C4b binding to C2.
  • Similarities exist between CP and alternative pathway (AP) C3 convertases.

Purpose of the Study:

  • To investigate the effect of CRIT-H17 on the AP of the complement system.
  • To determine the mechanism of CRIT-H17 inhibition on AP activation.

Main Methods:

  • ELISA and immunoblot assays to detect CRIT-H17 binding to factor B (FB).
  • Inhibition assays for factor D-mediated cleavage of FB.
  • Hemolytic assays using C2-deficient serum to assess AP activation.

Main Results:

  • CRIT-H17 blocked factor D-mediated cleavage of factor B.
  • CRIT-H17 directly bound to factor B.
  • CRIT-H17 did not affect C3bB complex assembly or exhibit decay-accelerating activity.
  • CRIT-H17 inhibited AP complement activation in a hemolytic assay.

Conclusions:

  • CRIT-H17 peptide inhibits AP complement activation by interfering with factor B function.
  • CRIT-H17 represents a potential therapeutic agent for AP-mediated diseases.

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