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Comprehensive Analysis of Procoagulant Platelets Exhibiting Features of Necrosis, Apoptosis and Platelet Activation
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The lectin complement pathway serine proteases (MASPs) represent a possible crossroad between the coagulation and
H Kozarcanin1, C Lood2, L Munthe-Fog3
1Department of Immunology, Genetics and Pathology, Rudbeck Laboratory C5:3, Uppsala University, Uppsala, Sweden.
Journal of Thrombosis and Haemostasis : JTH
|November 29, 2015
Summary
Activated platelets and fibrin trigger the lectin pathway's MASP-1 and MASP-2 proteases during blood clotting. This finding reveals a potential new mechanism in thromboinflammation, linking complement and coagulation systems.
Area of Science:
- Immunology
- Biochemistry
- Hematology
Background:
- The lectin pathway (LP) proteases MASP-1 and MASP-2, when activated, can cleave key coagulation factors in vitro.
- In vivo studies indicate MASP-1's role in thrombogenesis.
Purpose of the Study:
- To identify the mechanisms that trigger LP activation during thrombotic events.
- To investigate the interaction between the complement and coagulation systems.
Main Methods:
- Development of novel sandwich-ELISAs to quantify complexes of MASP-1/MASP-2 with C1 inhibitor (C1-INH) or antithrombin (AT).
- Flow cytometry to detect platelet binding of Ficolin proteins.
- SDS-PAGE/Western blotting to analyze protein interactions.
Main Results:
- Activated platelets bind Ficolin-1, -2, and -3, leading to MASP-1 and MASP-2 activation.
- Fibrin and fibrin fragment DD activate MASP-1 and MASP-2.
- MASP-1/MASP-2 activation by fibrin occurs during clotting, independent of heparin, and is neutralized by AT.
- Elevated activated MASP-1/MASP-2 levels correlate with thrombotic disease markers in patients.
Conclusions:
- MASP-1 and MASP-2 are activated during blood clotting.
- Activated platelets and fibrin generation trigger this activation in vitro and in vivo.
- This represents a novel activation and amplification pathway in thromboinflammation.
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