Factor XII and Neutrophil Extracellular Traps in Thrombosis - Crosstalk between Coagulation and Inflammation

Abstract

BACKGROUND: Thrombosis is a common disease in the western world. Coagulation factor XII (FXII) has been considered irrelevant for coagulation for a long time, but newer research shows its major role in many thrombotic diseases. This project aimed to characterize a deep vein thrombosis model in mice, to establish immunostainings for FXII and its potential activators, and to use those stainings to analyse the thrombosis model. METHODS: Frozen and paraffin sections of murine deep vein thrombosis were stained with Haematoxylin and Eosin a Picrosirius red. A protocol for immunofluorescence was tested and enhanced, and stainings for neutrophil granulocytes, neutrophil extracellular traps (NETs), platelets, and FXII/FXIIa were established. RESULTS: The results show that the thrombus size as well as the amount of red blood cells decreases over time, while the amount of collagen increases. The leucocyte density increases as well, and NETs show a maximum after 2 days. Platelets show a non-significant tendency to increase over time. FXII increases from 6 hours to 2 days after thrombus formation and stays on the same level afterwards. In double stainings, FXII shows an association with DNA and histones. DISCUSSION/CONCLUSION: The results show the process of thrombus reorganization and resolution. NETs are found in later states of thrombosis and are likely to influence thrombus formation, stability, and reorganization with over all procoagulant properties. FXII initiates coagulation but probably also plays a role in thrombus organization in this setting. Neutrophil derived FXII could be an additional source of FXII.