Venous and Arterial Thromboses: Two Sides of the Same Coin?

2017 ◽  
Vol 44 (03) ◽  
pp. 239-248 ◽  
Author(s):  
Giuseppe Lippi ◽  
Emmanuel Favaloro

AbstractArterial and venous thromboses are sustained by development of intraluminal thrombi, respectively, within the venous and arterial systems. The composition and structure of arterial and venous thrombi have been historically considered as being very different. Arterial thrombi (conventionally defined as “white”) have been traditionally proposed to be composed mainly of fibrin and platelet aggregates, whilst venous thrombi (conventionally defined as “red”) have been proposed as mostly being enriched in fibrin and erythrocytes. This archaic dichotomy seems ever more questionable, since it barely reflects the pathophysiology of thrombus formation in vivo. Both types of thrombi are actually composed of a complex fibrin network but, importantly, also contain essentially the same blood-borne cells (i.e., red blood cells, leukocytes, and platelets), and it is only the relative content of these individual elements that differ between venous and arterial clots or, otherwise, between thrombi generated under different conditions of blood flow and shear stress. Convincing evidence now suggests that either white or red intracoronary thrombi may be present in patients with myocardial infarction and, even more importantly, red thrombi may be more prone to distal embolization during percutaneous coronary intervention than those with lower content of erythrocytes. Conversely, it is now accepted that components traditionally considered to be involved “only” in arterial thrombosis are also represented in venous thrombosis. Thus, platelets comprise important components of venous clots, although they may be present in lower amounts here than in arterial thrombi, and von Willebrand factor is also represented in both arterial and venous thrombi. Of importance, such evidence thus supports the concept that adjunctive treatment normally associated to prevention of arterial thrombosis (e.g., aspirin) may have a role also in prevention and treatment of venous thrombosis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1797-1797 ◽  
Author(s):  
Wolfgang Bergmeier ◽  
Crystal L. Piffath ◽  
Tobias Goerge ◽  
Stephen M. Cifuni ◽  
Zaverio M. Ruggeri ◽  
...  

Abstract GPIbα binding to von Willebrand factor (VWF) exposed at a site of vascular injury is thought to be the first step in the formation of a hemostatic plug. However, our previous studies in VWF-deficient mice demonstrated delayed but not absent arterial thrombus formation suggesting that, under these conditions, GPIbα may bind other ligands or that a receptor other than GPIbα can mediate platelet adhesion. Here we studied thrombus formation in transgenic mice expressing GPIbα in which the extracellular domain was replaced by that of the human interleukin-4 receptor (IL4Rα/GPIbα-tg mice). Platelet adhesion to ferric chloride-treated mesenteric arterioles in IL4Rα/GPIbα-tg mice was virtually absent in contrast to avid adhesion in wild-type (WT) mice. As a consequence, arterial thrombus formation was completely inhibited in the mutant mice. Our studies further show that, when infused into WT recipient mice, IL4Rα/GPIbα-tg platelets or WT platelets lacking the 45 kD N-terminal domain of GPIbα failed to incorporate into growing arterial thrombi, even if the platelets were activated prior to infusion. Surprisingly, platelets lacking β3 integrins, which are unable to form thrombi on their own, incorporated efficiently into WT thrombi. Our studies provide in vivo evidence that GPIbα is absolutely required for recruitment of platelets to both exposed subendothelium and thrombi under arterial flow conditions. Thus, GPIbα contributes to arterial thrombosis by important adhesion mechanisms independent of the binding to VWF.


Blood ◽  
2002 ◽  
Vol 99 (10) ◽  
pp. 3623-3628 ◽  
Author(s):  
Dongmei Wu ◽  
Karen Vanhoorelbeke ◽  
Nancy Cauwenberghs ◽  
Muriel Meiring ◽  
Hilde Depraetere ◽  
...  

The interaction between collagen, von Willebrand factor (VWF), and glycoprotein Ib is the first step in hemostasis and thrombosis especially under high shear conditions. We studied the inhibition of the VWF-collagen interaction by using an antihuman VWF monoclonal antibody 82D6A3 to prevent arterial thrombosis in baboons to develop a new kind of antithrombotic strategy and determine for the first time experimental in vivo data concerning the importance of the collagen-VWF interaction. We used a modified Folts model to study the antithrombotic efficacy of 82D6A3, where cyclic flow reductions (CFRs) were measured in the femoral artery. Administering a dose of 100, 300, and 600 μg/kg resulted in a 58.3%, 100%, and 100% reduction in the CFRs, respectively. When 100 μg/kg 82D6A3 was infused into the baboons, 80% of VWF-A3 domain was occupied, corresponding to 30% to 36% ex vivo inhibition of VWF binding to collagen, with no prolongation of the bleeding time. The bleeding time was also not significantly prolonged when the CFRs were abolished at doses of 300 μg/kg and 600 μg/kg. At these doses 100% of VWF was occupied by the antibody and 100% ex vivo inhibition of the VWF-collagen binding was observed. 82D6A3 has a high affinity for VWF; after 48 hours still 68% VWF (300μg/kg) was occupied with a pharmacologic effect up to 5 hours after administration (80%-100% occupancy). In conclusion, these results clearly indicate that the VWF-collagen interaction is important in vivo in thrombosis under high shear conditions and thus might be a new target for preventing arterial thrombosis.


1992 ◽  
Vol 67 (04) ◽  
pp. 453-457 ◽  
Author(s):  
Raelene L Kinlough-Rathbone ◽  
Marian A Packham ◽  
Dennis W Perry ◽  
J Fraser Mustard ◽  
Marco Cattaneo

SummaryThe stability of platelet aggregates is influenced by the extent of the release of granule contents; if release is extensive and aggregation is prolonged, deaggregation is difficult to achieve. The relative importance of the contributions of released substances to aggregate stability are not known, although stable thrombin-induced aggregates form in platelet-rich plasma from patients with barely detectable plasma or platelet fibrinogen, and ADP stabilizes thrombin-induced aggregates of platelets from patients with delta storage pool deficiency which otherwise deaggregate more readily than normal platelets. We degranulated platelets with thrombin (0.9 U/ml caused greater than 90% loss of delta and alpha granule contents) and recovered them as individual platelets in fresh medium. The degranulated platelets were reaggregated by thrombin (2 U/ml). To prevent continuing effects of thrombin, FPRCH2C1 was added when thrombin-induced aggregation of thrombin-degranulated platelets reached its maximum. EDTA (5 mM) or EGTA (5 mM) added at maximum aggregation did not deaggregate these platelets, indicating that the stability of these aggregates does not depend on Ca2+ in the medium. Whereas with control platelets a combination of PGE1 (10 μM) and chymotrypsin(10 U/ml) was required for deaggregation, with thrombin-degranulated platelets either PGE1 or chymo-trypsin alone caused extensive deaggregation. The rate and extent of deaggregation of thrombin-degranulated platelets by a combination of PGE1 and chymotrypsin was greater than with control platelets.Electron microscope gold immunocytochemistry using antihuman fibrinogen IgG, anti-von Willebrand factor and anti-fibronectin showed a) that fibrinogen in the vacuoles of degranulated platelets was visible at focal points of platelet contact in the aggregates, but that large areas of platelet contact had no fibrinogen detectable between them; and b) in comparison to fibrinogen, little fibronectin or von Willebrand factor (vWf) was detectable in the platelets.Since the linkages between thrombin-degranulated platelets reaggregated by thrombin can be disrupted either by raising cAMP (thus making glycoprotein IIb/IIIa unavailable) or by proteolysis, these linkages are less stable than those formed between normal platelets. It might therefore be expected that platelets that take part in thrombus formation and then recirculate are likely to form less stable thrombi than platelets that have not released their granule contents.


Blood ◽  
2020 ◽  
Author(s):  
Reiner K. Mailer ◽  
Mikel Allende ◽  
Marco Heestermans ◽  
Michaela Schweizer ◽  
Carsten Deppermann ◽  
...  

Polyphosphate is a procoagulant inorganic polymer of linear linked orthophosphate residues. Multiple investigations have established the importance of platelet polyphosphate in blood coagulation, however the mechanistic details of polyphosphate homeostasis in mammalian species remain largely undefined. Here, we show that xenotropic and polytropic retrovirus receptor 1 (XPR1) regulates polyphosphate in platelets and is implicated in thrombosis in vivo. We used bioinformatic analyses of omics data to identify XPR1 as a major phosphate transporter in platelets. Xpr1 mRNA and protein expression inversely correlated with intracellular polyphosphate content and release. Pharmacological interference with XPR1 activity increased polyphosphate stores, led to enhanced platelet-driven coagulation and amplified thrombus formation under flow via the polyphosphate/factor XII pathway. Conditional gene deletion of Xpr1 in platelets resulted in polyphosphate accumulation, accelerated arterial thrombosis, and augmented activated platelet-driven pulmonary embolism without increasing bleeding in mice. These data identify platelet XPR1 as an integral regulator of platelet polyphosphate metabolism highlighting a fundamental role for phosphate homeostasis in thrombosis.


2020 ◽  
Vol 120 (03) ◽  
pp. 466-476
Author(s):  
Sibgha Tahir ◽  
Andreas H. Wagner ◽  
Steffen Dietzel ◽  
Hanna Mannell ◽  
Joachim Pircher ◽  
...  

Abstract Background von Willebrand factor (vWF) plays an important role in platelet activation. CD40–CD40 ligand (CD40L) induced vWF release has been described in large vessels and cultured endothelium, but its role in the microcirculation is not known. Here, we studied whether CD40 is expressed in murine microvessels in vivo, whether CD40L induces platelet adhesion and leukocyte activation, and how deficiency of the vWF cleaving enzyme ADAMTS13 affects these processes. Methods and Results The role of CD40L in the formation of beaded platelet strings reflecting their adhesion to ultralarge vWF fibers (ULVWF) was analyzed in the murine cremaster microcirculation in vivo. Expression of CD40 and vWF was studied by immunohistochemistry in isolated and fixed cremasters. Microvascular CD40 was only expressed under inflammatory conditions and exclusively in venous endothelium. We demonstrate that CD40L treatment augmented the number of platelet strings, reflecting ULVWF multimer formation exclusively in venules and small veins. In ADAMTS13 knockout mice, the number of platelet strings further increased to a significant extent. As a consequence extensive thrombus formation was induced in venules of ADAMTS13 knockout mice. In addition, circulating leukocytes showed primary and rapid adherence to these platelet strings followed by preferential extravasation in these areas. Conclusion CD40L is an important stimulus of microvascular endothelial ULVWF release, subsequent platelet string formation and leukocyte extravasation but only in venous vessels under inflammatory conditions. Here, the lack of ADAMTS13 leads to severe thrombus formation. The results identify CD40 expression and ADAMTS13 activity as important targets to prevent microvascular inflammatory thrombosis.


2018 ◽  
Vol 38 (04) ◽  
pp. 203-210 ◽  
Author(s):  
Rüdiger Scharf

AbstractPlatelets react immediately in response to traumatic vascular injury by adhesion, activation, aggregation and subsequent haemostatic plug formation. While this reaction pattern is essential for haemostasis, platelet responses can also cause occlusive thrombi in diseased arteries, leading to myocardial infarction or stroke. Initially, flowing platelets are captured from the circulation to vascular lesions. This step is mediated by glycoprotein (GP) Ib-IX-V interacting with immobilized von Willebrand factor (VWF) on exposed subendothelial components. Tethered platelets can now bind to collagen through GPVI and integrin α2β1. Outside-in signals from the adhesion receptors act synergistically with inside-out signals from soluble stimuli and induce platelet activation. These mediators operate through G protein–coupled receptors and reinforce adhesion and activation. Typical manifestations of activated platelets include calcium mobilization, procoagulant activity, cytoskeletal reorganization, granule secretion and aggregation. This requires activation of integrin αIIbβ3 with shifting into a high-affinity state and is indispensable to bind soluble fibrinogen, VWF and fibronectin. The multiple interactions and the impact of thrombin result in firm adhesion and recruitment of circulating platelets into growing aggregates. A fibrin meshwork supports stabilization of haemostatic thrombi and prevents detachment by the flowing blood. This two-part review provides an overview of platelet activation and signal transduction mechanisms with a focus on αIIbβ3-mediated outside-in signaling in integrin variants. In the first part, a three-stage model of platelet recruitment and activation in vivo is presented. Along with that, platelet responses upon exposure to thrombogenic surfaces followed by platelet-to-platelet interactions and formation of haemostatic thrombi are discussed. Moreover, several determinants involved in pathological thrombosis will be reviewed.


2001 ◽  
Vol 86 (12) ◽  
pp. 1512-1520 ◽  
Author(s):  
Chi-ho Yun ◽  
Hyoung-sik Seo ◽  
Takaki Koga ◽  
Takashi Dan ◽  
Hak-yeop Kim ◽  
...  

SummaryThe antithrombotic efficacy of AT-1459, a novel, direct thrombin inhibitor (Ki = 4.9 nM) was evaluated in rat models of venous thrombosis combined with a bleeding time test and arterial thrombosis.After drugs were given by i. v. bolus injection plus a continuous infusion, the ID50 (a dose that exhibits 50% inhibition of thrombus formation over each vehicle group) values of AT-1459, argatroban, and dalteparin were 0.04 mg/kg plus 0.04 mg/kg/h, 0.1 mg/kg plus 0.4 mg/ kg/h, and 13.0 IU/kg plus 26.0 IU/kg/h, respectively, in the venous thrombosis study. The BT2 (a dose that causes 2-fold prolongation of bleeding time over each vehicle group) values of AT-1459, argatroban, and dalteparin were 0.9 mg/kg plus 0.9 mg/kg/h, 1.0 mg/kg plus 0.6 mg/kg/h, and 345.5 IU/kg plus 691.0 IU/kg/h in the rat tail transection model. The ratios of BT2/ID50 of AT-1459, argatroban, and dalteparin were 22.5, 10.0, and 26.6, respectively.In a rat model of arterial thrombosis induced by topical FeCl2 application, intravenous administration of AT-1459, argatroban, and dalteparin improved the vessel patency significantly (P <0.01) at 0.6 mg/kg plus 0.6 mg/kg/h, 0.6 mg/kg plus 2.4 mg/kg/h, and 300 IU/kg plus 600 IU/kg/h, respectively.The oral antithrombotic effect of AT-1459 lasted for 6 after administering 30 mg/kg and improved the vessel patency significantly 1 h after administering the same dose in venous and arterial thrombosis models, respectively, with a rapid onset of action. Warfarin also inhibited thrombus weight and improved the vessel patency significantly after oral administration of 0.3 mg/kg for three consecutive days in the same study. The antithrombotic and hemorrhagic effects of all drugs studied were correlated with plasma concentration or clotting times.These results suggest that AT-1459 may be clinically useful as an orally available antithrombotic agent for the prevention of venous and arterial thrombosis.


2001 ◽  
Vol 85 (05) ◽  
pp. 837-844 ◽  
Author(s):  
Angela Bertagna ◽  
Nadia Jahroudi

SummaryIonizing irradiation in patients is proposed to cause thrombus formation. An increase in von Willebrand factor secretion in response to irradiation is a major contributing factor to thrombus formation. We have previously reported that the increased VWF secretion in response to irradiation is mediated at the transcriptional level. The VWF core promoter fragment (sequences –90 to +22) was shown to contain the necessary cis-acting element(s) to mediate the irradiation response of the VWF gene. Here we report that a CCAAT element in the VWF promoter is the cis-acting element necessary for irradiation induction and that the NFY transcription factor interacts with this element. These analyses demonstrate that inhibition of NFY’s interaction with the CCAAT element abolishes the irradiation induction of the VWF promoter. These results provide a novel role for NFY and add this factor to the small list of irradiation-responsive transcription factors. Coimmunoprecipitation experiments demonstrated that NFY is associated with the histone acetylase P/CAF in vivo and that irradiation resulted in an increased association of NFY with coactivator P/CAF. We propose that irradiation induction of the VWF promoter involves a mechanism resulting in increased recruitment of the coactivator P/CAF to the promoter via the NFY transcription factor.


1979 ◽  
Author(s):  
H. Yamazaki ◽  
T. Motomiya ◽  
T. Sano

Although an interaction between platelets and arteriosclerotic vessel wall is thought to be important in thrombus formation, a little information was obtained in clinical subjects. We have reported that platelet aggregation Increased in patients with IHD after exercise. To analyse the mechanism of this phenomenon, changes in platelet sensitivity to ADP aggregation, plasma von Willebrand factor and beta-thromboglobulin level were measured in 30 IHD and 30 healthy controls before and Immediately after an isometric exercise (handgrip of 50% voluntary contraction for 2 min). Platelet sensitivity and vWF were determined by original methods detecting microscopically the highest dilution of serially two-fold diluted ADP or test plasma mixed with ristocetin to give platelet aggregation. Beta-TG was measured by RIA Kit. An effect of anti-platelet drug was also observed in IHD. The patients with IHD were administered with placebo or dipyridamole (400 mg/day for 4 weeks) in a crossover single blind fashion. Under placebo, platelet sensitivity to aggregation, vWF and beta-TG increased immediately after the exercise with a statistical significance in IHD. In the healthy control and IHD under dipyridamole, these increases were not observed. The phenomenon may suggest that platelets circulating in sclerotic vessels tend to release and are enhanced in reactivity with smaller stimuli than those in healthy. Such changes might be prevented with dipyridamole.


Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3057-3057
Author(s):  
Richard Robins ◽  
Peter Carmeliet ◽  
Mark Blostein

Abstract Abstract 3057 Poster Board II-1033 Gas6 is the vitamin-K dependent protein product of growth arrest specific gene 6. A genetic deficiency of this protein protects mice against experimentally induced thrombosis without causing a bleeding diathesis. Protection from thrombosis results from a deficiency in platelet aggregation and secretion. In addition to being expressed by platelets, Gas6 and its receptors are also expressed by vascular cells including the endothelium, an organ known to play a role in the hemostatic balance. While endothelial Gas6 has been shown to promote inflammation and cell survival, it remains unknown if it contributes to the pathophysiology of venous thrombosis. To answer this question, we employed a bone marrow transplantation (BMT) strategy using wild type and Gas6 null mice to create chimeric mice with combined genotypes in the vascular and platelet compartments. Mice were exposed to a dose of radiation optimized to maximize both survival and ablation of recipient marrow. Irradiated mice were then infused with bone marrow cells isolated from the femurs and tibias of donor mice and were allowed a one month recovery period for hematologic reconstitution. Success of marrow uptake was confirmed by PCR. They were then subjected to the Ferric Chloride model of venous thrombosis in the Inferior Vena Cava (IVC). Four groups of transplanted mice were studied. Results from these BMT experiment show a contributing effect by both endothelial as well as platelet Gas6 to thrombus formation (n=8, p<0.01). Mice with combined genotypes (Gas6-/- into WT and WT into Gas6 -/-) show an intermediate thrombus weight suggesting that both vascular and platelet derived Gas6 are both responsible for thrombosis pathology. Therefore, Gas6 at both sites could be potential targets in treating venous thrombosis. Disclosures No relevant conflicts of interest to declare.


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