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P43 Complement C3 in diabetes: hypofibrinolysis, glycation and inhibiting interaction with fibrinogen to reduce cardiovascular risk
  1. RJ King1,
  2. K Schuett2,
  3. C Tiede3,
  4. V Jankowski4,
  5. V John1,
  6. A Trehan1,
  7. K Simmons5,
  8. S Ponnambalam6,
  9. CWG Fishwick5,
  10. MJ McPherson3,
  11. DC Tomlinson3,
  12. RA Ajjan1
  1. 1Leeds Institute for Cardiovascular and Metabolic Medicine
  2. 2Department of Internal Medicine I, University Hospital Aachen, Germany
  3. 3Bioscreening Technology Group in the School of Molecular and Cellular Biology
  4. 4Institute for Molecular Cardiovascular Research, Aachen University, Germany
  5. 5School of Chemistry
  6. 6School of Molecular and Cellular Biology, University of Leeds, UK

Abstract

Aims Complement C3 compromises fibrin clot lysis but the effect of diabetes on C3 fibrinolytic properties are unknown and fibrinogen interaction sites remain to be elucidated. We investigated i) inter-individual variability in the fibrinolytic properties ofC3 in diabetes ii) binding sites between fibrinogen and C3 and iii) modulation of fibrin clot lysis by manipulating fibrinogen-C3 interactions.

Methods Turbidimetric studies analysed the effect of C3 on fibrinolysis. Mass spectrometry, microarray screening and molecular modelling evaluated C3 glycation and interaction sites with fibrinogen. A novel, non-antibody binding protein (NABP) was used to modulate C3-fibrinogen interaction.

Results C3 from diabetes patients (n = 12) showed enhanced antifibrinolytic activity, prolonging lysis time by 522 ± 166 sec compared with 195 ± 105 sec for control protein (n = 12; p = 0.04). C3 from diabetes patients, which showed glycation of multiple lysine residues, demonstrated greater inter-individual variability in lysis prolongation compared with control protein (5–51% and 5–18%, respectively). Peptide microarray screening identified 2 peptide motifs within fibrinogen β chain (residues 424–433, 435–445) that interact with C3, suggesting these are C3-fibrinogen interaction sites. One fibrinogen-binding NABP resulted in complete abolition of C3 induced prolongation of lysis (728 ± 25.1 seconds to 632 ± 23.7 seconds, p = 0.005) and molecular modelling predicted that NABP binds fibrinogen in an area adjacent to C3-fibrinogen interaction sites.

Conclusion/Interpretation C3 from patients with diabetes has enhanced antifibrinolytic properties and displays large inter-individual variability. Fibrinogen β-chain represents one binding site with C3 and inhibition of fibrinogen-C3 interaction using NABP may help to identify novel therapeutic targets for reduction of thrombosis risk in diabetes.

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