Manuscript handled by: D. Monroe
Identification and characterization of α1-antitrypsin in fibrin clots
Article first published online: 15 JUL 2013
© 2013 International Society on Thrombosis and Haemostasis
Journal of Thrombosis and Haemostasis
Volume 11, Issue 7, pages 1319–1328, July 2013
How to Cite
Identification and characterization of α1-antitrypsin in fibrin clots. J Thromb Haemost 2013; 11: 1319–28., , , , .
Final decision: D. Lane, 26 April 2013
- Issue published online: 15 JUL 2013
- Article first published online: 15 JUL 2013
- Accepted manuscript online: 7 MAY 2013 01:29AM EST
- Manuscript Accepted: 26 APR 2013
- Manuscript Received: 12 JUN 2012
- alpha 1-antitrypsin;
Background and Objectives
Preliminary studies indicated that α1-antitrypsin (A1AT) is the most abundant protein that is non-covalently bound to fibrin clots prepared from plasma. The aim of this study was to identify and characterize fibrin(ogen)-bound A1AT.
Methods and Results
Plasma clots were prepared and extensively washed with saline. Clot-bound A1AT could only be extracted using denaturing agents such as urea, thiourea or SDS, pointing to an apparently strong association. Purified fibrinogen, but still containing A1AT as a contaminant, was gel filtered, which showed that the A1AT was bound to fibrinogen. A specific ELISA detected the presence of A1AT-fibrinogen complexes in both purified fibrinogen and pooled normal plasma. Finally, fibrin(ogen)-Sepharose chromatography indicated that A1AT purified from plasma contained a small fraction of fibrin(ogen)-binding A1AT. To study the inhibitory activity of fibrin(ogen)-bound A1AT, both fibrinogen containing A1AT and washed plasma clots were incubated with increasing amounts of elastase. SDS-PAGE and Western blotting showed under both conditions the generation of the A1AT-elastase complex as well as cleaved A1AT. The inhibitory activity of fibrin(ogen)-bound A1AT was also demonstrated by measuring elastase-induced lysis of fibrin clots.
Fibrin clots contain strongly bound A1AT, which is functionally active as a serine protease inhibitor (serpin). This A1AT might play a role in the local regulation of proteases involved in coagulation or fibrinolysis and represent a novel link between the inflammatory and hemostatic systems.