Platelet Signaling in Primary Haemostasis and Arterial Thrombus Formation: Part 1

2018 ◽  
Vol 38 (04) ◽  
pp. 203-210 ◽  
Author(s):  
Rüdiger Scharf
Keyword(s):  
Platelet Activation ◽  
Thrombus Formation ◽  
Vascular Lesions ◽  
Arterial Thrombus ◽  
Platelet Signaling ◽  
Transduction Mechanisms ◽  
Granule Secretion ◽  
Von Willebrand ◽  
The Impact

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.

A Humanin Analog Attenuates Platelet Responses to Vascular Injury

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1131-1131 ◽  
Author(s):  
Lijie Ren ◽  
Qiang Li ◽  
Zhao Zeng ◽  
Peipei Mou ◽  
Xiaohui Liu ◽  
...  
Keyword(s):  
Amino Acid ◽  
Platelet Activation ◽  
Thrombus Formation ◽  
Ischemia Reperfusion ◽  
Treated Group ◽  
Human Platelets ◽  
Control Group ◽  
Arterial Thrombus ◽  
Group 3

Abstract Abstract 1131 Humanin (HN), a 24-amino acid endogenous antiapoptotic peptide, was initially shown to protect against neuronal cell death by Alzheimer's disease-related insults. It has recently been found that an exogenous analog of HN (HNG) in which the 14th amino acid serine is replaced with glycine protected against cerebral and cardiac ischemia reperfusion (I/R) injury in cortical neurons and cardiomyocytes, respectively. Platelet activation and thrombus formation has been shown to play an important role during I/R injury by exacerbating the extent of the infarct size. However, it is presently unknown whether HNG affects platelet function and the subsequent arterial thrombus formation. We thus examined whether HNG affects platelet activation and thrombus formation both in vitro and in vivo. Human platelets were isolated from healthy adults. Preincubation of washed human platelets with HNG (4μM) reduced collagen- or convulxin-induced platelet aggregation by 56.8% (P<0.05) and 71.9% (P<0.001), respectively. Similarly, HNG significantly reduced ATP release stimulated by collagen or convulxin. Convulxin-induced P-selectin expression and fibrinogen binding on single platelet was inhibited by HNG, as measured by flow cytometry. Moreover, HNG reduced platelet spreading on the fibrinogen coated surface by 62.9 % (P <0.05). Western blot revealed a reduction of platelet AKT phosphorylation by HNG upon collagen stimulation, implying the involvement of PI3K pathway. In addition, MAPK P38 phosphorylation by collagen and convulxin was also reduced by HNG. HNG effects on thrombus formation were tested in vivo in a ferric chloride-induced carotid artery injury model in mice. The intraperitoneal injection of HNG (25μg/kg) to male C57BL6/J mice significantly extended the first occlusion time (7.3±0.4 min, N=10), when compared to the saline injected littermates (5.4±0.7 min, N=12) (P <0.05). Furthermore, the number of mice that formed stable thrombus was less in the HNG–treated group (3/13) than the control group (6/13), while the non-occlusion mouse number was more in the HNG-treated group (3/13) than the control group (1/13). Together, these data show that HNG inhibits platelet activation and arterial thrombus formation. This might suggest that the protective effects of HNG against ischemia reperfusion injury could be, in part, via attenuating platelet activation. Therefore, HNG could be a potential therapeutic agent in thrombotic and cardiovascular disorders. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Bruton tyrosine kinase is essential for botrocetin/VWF-induced signaling and GPIb-dependent thrombus formation in vivo

Blood ◽  
2006 ◽  
Vol 108 (8) ◽  
pp. 2596-2603 ◽  
Author(s):  
Junling Liu ◽  
Malinda E. Fitzgerald ◽  
Michael C. Berndt ◽  
Carl W. Jackson ◽  
T. Kent Gartner
Keyword(s):  
Tyrosine Kinase ◽  
Thrombus Formation ◽  
Dependent Manner ◽  
Akt Phosphorylation ◽  
Atp Secretion ◽  
Arterial Thrombus ◽  
Bruton Tyrosine Kinase ◽  
Von Willebrand ◽  
Willebrand Factor

AbstractBotrocetin (bt)-facilitated binding of von Willebrand factor (VWF) to the platelet membrane glycoprotein (GP) Ib-IX-V complex on platelets in suspension initiates a signaling cascade that causes αIIbβ3 activation and platelet aggregation. Previous work has demonstrated that bt/VWF-mediated agglutination activates αIIbβ3 and elicits ATP secretion in a thromboxane A2 (TxA2)-dependent manner. The signaling that results in TxA2 production was shown to be initiated by Lyn, enhanced by Src, and propagated through Syk, SLP-76, PI3K, PLCγ2, and PKC. Here, we demonstrate that the signaling elicited by GPIb-mediated agglutination that results in TxA2 production is dependent on Bruton tyrosine kinase (Btk). The results demonstrate that Btk is downstream of Lyn, Syk, SLP-76, and PI3K; upstream of ERK1/2, PLCγ2, and PKC; and greatly enhances Akt phosphorylation. The relationship(s), if any, between ERK1/2, PLCγ2, and PKC were not elucidated. The requirement for Btk and TxA2 receptor function in GPIb-dependent arterial thrombosis was confirmed in vivo by characterizing blood flow in ferric chloride-treated mouse carotid arteries. These results demonstrate that the Btk family kinase, Tec, cannot provide the function(s) missing because of the absence of Btk and that Btk is essential for both bt/VWF-mediated agglutination-induced TxA2 production and GPIb-dependent stable arterial thrombus formation in vivo.

CLEC-2 is an essential platelet-activating receptor in hemostasis and thrombosis

Blood ◽  
2009 ◽  
Vol 114 (16) ◽  
pp. 3464-3472 ◽  
Author(s):  
Frauke May ◽  
Ina Hagedorn ◽  
Irina Pleines ◽  
Markus Bender ◽  
Timo Vögtle ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Thrombus Formation ◽  
Antibody Treatment ◽  
Cellular Activation ◽  
Primary Hemostasis ◽  
Arterial Thrombus ◽  
Normal Adhesion

Abstract Damage to the integrity of the vessel wall leads to exposure of the subendothelial extracellular matrix (ECM), triggering platelet activation and aggregation. This process is essential for primary hemostasis but it may also lead to arterial thrombosis. Although the mechanisms underlying platelet activation on the ECM are well explored, it is less clear which receptors mediate cellular activation in a growing thrombus. Here we studied the role of the recently identified C-type lectin-like receptor 2 (CLEC-2) in this process. We show that anti–CLEC-2 antibody treatment of mice leads to complete and highly specific loss of CLEC-2 in circulating platelets for several days. CLEC-2–deficient platelets displayed normal adhesion under flow, but subsequent aggregate formation was severely defective in vitro and in vivo. As a consequence, CLEC-2 deficiency was associated with increased bleeding times and profound protection from occlusive arterial thrombus formation. These results reveal an essential function of CLEC-2 in hemostasis and thrombosis.

scholarly journals Diacylglycerol kinase ζ is a negative regulator of GPVI-mediated platelet activation

2019 ◽  
Vol 3 (7) ◽  
pp. 1154-1166 ◽  
Author(s):  
Alyssa J. Moroi ◽  
Nicole M. Zwifelhofer ◽  
Matthew J. Riese ◽  
Debra K. Newman ◽  
Peter J. Newman
Keyword(s):  
Platelet Activation ◽  
Bleeding Time ◽  
Thrombus Formation ◽  
Negative Regulator ◽  
Platelet Surface ◽  
Rotational Thromboelastometry ◽  
Surface Receptors ◽  
Glycoprotein Vi ◽  
Granule Secretion

Abstract Diacylglycerol kinases (DGKs) are a family of enzymes that convert diacylglycerol (DAG) into phosphatidic acid (PA). The ζ isoform of DGK (DGKζ) has been reported to inhibit T-cell responsiveness by downregulating intracellular levels of DAG. However, its role in platelet function remains undefined. In this study, we show that DGKζ was expressed at significant levels in both platelets and megakaryocytes and that DGKζ-knockout (DGKζ-KO) mouse platelets were hyperreactive to glycoprotein VI (GPVI) agonists, as assessed by aggregation, spreading, granule secretion, and activation of relevant signal transduction molecules. In contrast, they were less responsive to thrombin. Platelets from DGKζ-KO mice accumulated faster on collagen-coated microfluidic surfaces under conditions of arterial shear and stopped blood flow faster after ferric chloride–induced carotid artery injury. Other measures of hemostasis, as measured by tail bleeding time and rotational thromboelastometry analysis, were normal. Interestingly, DGKζ deficiency led to increased GPVI expression on the platelet and megakaryocyte surfaces without affecting the expression of other platelet surface receptors. These results implicate DGKζ as a novel negative regulator of GPVI-mediated platelet activation that plays an important role in regulating thrombus formation in vivo.

The Role of Platelet Adhesion Receptor GPIb α Far Exceeds That of Its Main Ligand von Willebrand Factor in Arterial Thrombosis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1797-1797 ◽  
Author(s):  
Wolfgang Bergmeier ◽  
Crystal L. Piffath ◽  
Tobias Goerge ◽  
Stephen M. Cifuni ◽  
Zaverio M. Ruggeri ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Arterial Thrombosis ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Interleukin 4 ◽  
Arterial Thrombus ◽  
A Site ◽  
Von Willebrand ◽  
Willebrand Factor

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.

scholarly journals Impaired platelet activation and cAMP homeostasis in MRP4-deficient mice

Blood ◽  
2015 ◽  
Vol 126 (15) ◽  
pp. 1823-1830 ◽  
Author(s):  
Benoit Decouture ◽  
Elise Dreano ◽  
Tiphaine Belleville-Rolland ◽  
Orjeta Kuci ◽  
Blandine Dizier ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Platelet Activation ◽  
Thrombus Formation ◽  
Key Points ◽  
Platelet Signaling ◽  
Deficient Mice ◽  
Kinase A

Key PointsIn vivo and in vitro thrombus formation is altered in MRP4-deficient mice. MRP4 modulates the cAMP–protein kinase A platelet signaling pathway.

scholarly journals ANXA7 Regulates Platelet Lipid Metabolism and Ca 2+ Release in Arterial Thrombosis

2021 ◽  
Author(s):  
Mailin-Christin Manke ◽  
Sascha Geue ◽  
Cristina Coman ◽  
Bing Peng ◽  
Ferdinand Kollotzek ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Platelet Activation ◽  
Arterial Thrombosis ◽  
Thrombus Formation ◽  
Vascular Occlusion ◽  
Bioactive Metabolites ◽  
Platelet Signaling ◽  
Intracellular Ca ◽  
Coated Surfaces

Rationale: Platelet activation after contact to subendothelial collagen leads to acute arterial thrombosis. Annexin A7 (ANXA7) is a phospholipid-binding protein participating in the regulation of intracellular Ca 2+ and exocytosis. Objective: The present study aimed to determine the role of ANXA7 in platelet Ca 2+ signaling and lipid metabolism during platelet activation in arterial thrombosis using the ANXA7 inhibitor ABO and gene-targeted mice lacking Anxa7 ( Anxa7 -/- ). Methods and Results: ANXA7 is strongly expressed in platelets. Functionally, luminescence aggregometry revealed significantly abrogated aggregation and secretion of ABO-treated or Anxa7 -/- platelets when compared with untreated or Anxa7+/+ platelets after activation with collagen or the GPVI-specific agonist collagen-related peptide (CRP). Furthermore, while both thrombus formation on collagen-coated surfaces under high arterial shear rates in ABO-treated or Anxa7-deficient whole blood, and thrombotic vascular occlusion after FeCl3-induced injury in vivo in Anxa7 -/- bone marrow chimeric mice were significantly diminished, no prolongation of bleeding time was observed in ABO-treated or Anxa7 -/- mice. Fura-2-AM spectrofluorimetry unraveled a blunted [Ca2+]i increase in ABO-treated or Anxa7 -/- platelets after GPVI stimulation. Due to an abolished PLCy2 phosphorylation, Anxa7 -/- platelets displayed abrogated intracellular Ca 2+ mobilization following CRP-dependent platelet activation. Quantitative lipidomics analysis further revealed that ANXA7 critically affects platelet oxylipin metabolism following GPVI-dependent platelet activation. Anxa7 -/- platelets showed a significantly reduced generation of several bioactive metabolites, particularly TxA 2 and 12(S)-HETE. Finally, defective PLCy2 phosphorylation and blunted [Ca 2+ ]i increase in Anxa7 -/- platelets could be rescued by exogenous addition of 12(S)-HETE, indicating that ANXA7 is a critical regulator of the platelet 12-lipoxygenase in GPVI-dependent platelet Ca 2+ signaling during arterial thrombosis. Conclusions: The present study unravels ANXA7 as a regulator of oxylipin metabolism and Ca 2+ -dependent platelet activation downstream of GPVI. ANXA7 plays an important role in platelet signaling during arterial thrombosis and thus may reflect a promising target for novel antiplatelet strategies.

scholarly journals Extract of Seaweed Codium fragile Inhibits Integrin αIIbβ3-Induced Outside-in Signaling and Arterial Thrombosis

2021 ◽  
Vol 12 ◽  
Author(s):  
Tae In Kim ◽  
Yeon-Ji Kim ◽  
Kyungho Kim
Keyword(s):  
Bleeding Time ◽  
Thrombus Formation ◽  
Inhibitory Effect ◽  
Clot Retraction ◽  
Codium Fragile ◽  
Arterial Thrombus ◽  
Granule Secretion ◽  
Platelet Spreading ◽  
Αiibβ3 Integrin

Seaweeds are thought to be promising candidates for functional foods and to help prevent thrombotic and related cardiovascular diseases. Codium fragile (Suringer) Hariot has been traditionally used as a culinary ingredient, and it possesses a range of biological activities, including the inhibition of platelet function. However, the mechanism of this inhibition is unclear. The aim of this study was to examine the inhibitory effect of C. fragile in platelet function. The antiplatelet activity of C. fragile on agonist-activated platelet aggregation, granule secretion, calcium mobilization, platelet spreading, and clot retraction was assessed. The phosphorylation of c-Src, Syk, PLCγ2, and several proteins involving in the αIIbβ3 integrin outside-in signaling pathway were also studied in thrombin and CRP-stimulated platelets. The antithrombotic effect was investigated in mice using ferric chloride-induced arterial thrombus formation in vivo. Transection tail bleeding time was used to evaluate whether C. fragile inhibited primary hemostasis. The main components and contents of C. fragile ethanol extract were confirmed by GC-MS analysis. C. fragile significantly impaired agonist-induced platelet aggregation granule secretion, calcium mobilization, platelet spreading, and clot retraction. Biochemical analysis revealed that C. fragile inhibited the agonist-induced activation of c-Src, Syk, and PLCγ2, as well as the phosphorylation of PI3K, AKT, and mitogen-activated protein kinases (MAPKs). The inhibitory effect of C. fragile resulted from an inhibition of platelet αIIbβ3 integrin outside-in signal transduction during cell activation. Oral administration of C. fragile efficiently blocked FeCl3-induced arterial thrombus formation in vivo without prolonging bleeding time. GC-MS analysis revealed that phytol was the main constituent and the total content of isomers was 160.8 mg/kg. Our results demonstrated that C. fragile suppresses not only the inside-out signaling of αIIbβ3 integrin but also outside-in signal transmission. Therefore, C. fragile could be an effective antiplatelet therapeutic candidate.

scholarly journals Dietary α-Linolenic Acid Inhibits Arterial Thrombus Formation, Tissue Factor Expression, and Platelet Activation

2011 ◽  
Vol 31 (8) ◽  
pp. 1772-1780 ◽  
Author(s):  
Erik W. Holy ◽  
Marc Forestier ◽  
Eva K. Richter ◽  
Alexander Akhmedov ◽  
Florian Leiber ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Linolenic Acid ◽  
Platelet Activation ◽  
Thrombus Formation ◽  
Tissue Factor Expression ◽  
Arterial Thrombus ◽  
Factor Expression

Partially desulfated heparin modulates the interaction between anti-protamine/heparin antibodies and platelets

2016 ◽  
Vol 115 (02) ◽  
pp. 324-332 ◽  
Author(s):  
Rabie Jouni ◽  
Heike Zöllner ◽  
Ahmad Khadour ◽  
Jan Wesche ◽  
Anne Grotevendt ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Factor ◽  
Standard Drug ◽  
Platelet Surface ◽  
Minimal Impact ◽  
Platelet Survival ◽  
Heparin Complexes ◽  
The Impact

SummaryProtamine (PRT) is the standard drug to neutralise heparin. PRT/heparin complexes induce an immune response similar to that observed in heparin-induced thrombocytopenia (HIT). Partially desulfated heparin (ODSH) was shown to interfere with anti-platelet factor 4/heparin antibodies (Abs), which are responsible for HIT. In this study, we analyse the impact of ODSH on the interaction between anti-PRT/heparin Abs and platelets. The ability of ODSH to prevent anti-PRT/heparin Ab-induced platelet destruction in vivo was investigated using the NOD/ SCID mouse model. ODSH improved platelet survival in the presence of PRT, heparin and anti-PRT/heparin Abs (median platelet survival after 300 minutes (min) with 20 μg/ml ODSH: 75 %, range 70–81 % vs without ODSH: 49%, range 44–59%, p=0.006). Furthermore, when ODSH was applied 60 min after Ab injection platelet survival was improved (median platelet survival after 300 min with ODSH: 83 %, range 77–93 % vs without ODSH: 59 %, range 29–61 %, p=0.02). In in vitro experiments ODSH inhibited platelet activation at concentrations > 16 μg/mL (p< 0.001), as well as PRT/heparin complex binding to platelets (mean fluorescence intensity [MFI] without ODSH: 85 ± 14 vs with ODSH: 15 ± 0.6, p=0.013). ODSH also displaced pre-bound complexes from the platelet surface (MFI without ODSH: 324 ± 43 vs with 32 μg/ml ODSH: 53 ± 9, p< 0.001). While interfering with platelet activation by anti-PRT/heparin Abs, up to a concentration of 16 μg/ml, ODSH had only minimal impact on neutralisation of heparin by PRT. In conclusion, our study shows that ODSH is able to inhibit platelet activation and destruction suggesting a potential clinical use to reduce anti-PRT/heparin Ab-mediated adverse effects.

Sign in / Sign up

Export Citation Format

Share Document