CC BY-NC-ND 4.0 · Thromb Haemost 2018; 118(12): 2074-2085
DOI: 10.1055/s-0038-1675229
Cellular Haemostasis and Platelets
Georg Thieme Verlag KG Stuttgart · New York

Neutrophil-Mediated Proteolysis of Thrombospondin-1 Promotes Platelet Adhesion and String Formation

Katharina Seif
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Lejla Alidzanovic
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Barbara Tischler
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Nahla Ibrahim
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Branislav Zagrapan
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Sabine Rauscher
2  Core Facility Imaging, Medical University of Vienna, Vienna, Austria
,
Manuel Salzmann
3  Centre for Physiology and Pharmacology, Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
,
Lena Hell
4  Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
,
Lisa-Marie Mauracher
4  Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
,
Ulrich Budde
5  MEDILYS Laborgesellschaft mbH, Hamburg, Germany
,
Johannes A. Schmid
3  Centre for Physiology and Pharmacology, Institute of Vascular Biology and Thrombosis Research, Medical University of Vienna, Vienna, Austria
,
Bernd Jilma
6  Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria
,
Ingrid Pabinger
4  Clinical Division of Haematology and Haemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria
,
Alice Assinger
7  Centre for Physiology and Pharmacology, Institute of Physiology, Medical University of Vienna, Vienna, Austria
,
Patrick Starlinger
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
,
Christine Brostjan
1  Department of Surgery, Surgical Research Laboratory, Medical University of Vienna, Vienna, Austria
› Author Affiliations
Funding This work was supported by the Austrian Science Fund (project SFB-54 P09).
Further Information

Publication History

13 January 2018

12 September 2018

Publication Date:
12 November 2018 (eFirst)

Abstract

Thrombospondin-1 (TSP-1) is primarily expressed by platelets and endothelial cells (ECs) and rapidly released upon their activation. It functions in haemostasis as a bridging molecule in platelet aggregation, by promoting platelet adhesion to collagen and by protecting von Willebrand factor strings from degradation. In blood of patients undergoing surgery and in co-cultures of neutrophils with platelets or ECs, we observed proteolysis of the 185 kDa full-length TSP-1 to a 160-kDa isoform. We hypothesized that TSP-1 processing may alter its haemostatic properties. Selective enzyme inhibitors in co-cultures revealed that neutrophil proteases elastase and cathepsin G mediate TSP-1 processing. The cut site of cathepsin G was mapped to TSP-1 amino acids R237/T238 by Edman sequencing. Formation of neutrophil extracellular traps protected TSP-1 from complete degradation and promoted controlled processing to the 160-kDa isoform. Haemostatic properties were tested by platelet aggregation, adhesion, coagulation and string formation under flow. Platelets from TSP-1 deficient mice did not differ from wild-type in platelet aggregation but showed severe impairment of platelet adhesion to collagen and string formation under flow. Reconstitution experiments revealed that the 160-kDa TSP-1 isoform was markedly more potent than the 185-kDa full-length molecule in restoring function. Thus, TSP-1 processing by neutrophil proteases yields a 160-kDa isoform which shows enhanced potency to promote platelet adhesion and string formation. This finding reveals a novel mechanism of neutrophil-mediated thrombus formation and provides first evidence for the impact of TSP-1 proteolysis on its haemostatic properties.

Supplementary Material