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Cells Oct 20211,8-cineole, a monoterpenoid is a major component of eucalyptus oil and has been proven to possess numerous beneficial effects in humans. Notably, 1,8-cineole is the...
1,8-cineole, a monoterpenoid is a major component of eucalyptus oil and has been proven to possess numerous beneficial effects in humans. Notably, 1,8-cineole is the primary active ingredient of a clinically approved drug, Soledum which is being mainly used for the maintenance of sinus and respiratory health. Due to its clinically valuable properties, 1,8-cineole has gained significant scientific interest over the recent years specifically to investigate its anti-inflammatory and antioxidant effects. However, the impact of 1,8-cineole on the modulation of platelet activation, thrombosis and haemostasis was not fully established. Therefore, in this study, we demonstrate the effects of 1,8-cineole on agonists-induced platelet activation, thrombus formation under arterial flow conditions and haemostasis in mice. 1,8-cineole largely inhibits platelet activation stimulated by glycoprotein VI (GPVI) agonists such as collagen and cross-linked collagen-related peptide (CRP-XL), while it displays minimal inhibitory effects on thrombin or ADP-induced platelet aggregation. It inhibited inside-out signalling to integrin αIIbβ3 and outside-in signalling triggered by the same integrin as well as granule secretion and intracellular calcium mobilisation in platelets. 1,8-cineole affected thrombus formation on collagen-coated surface under arterial flow conditions and displayed a minimal effect on haemostasis of mice at a lower concentration of 6.25 µM. Notably, 1,8-cineole was found to be non-toxic to platelets up to 50 µM concentration. The investigation on the molecular mechanisms through which 1,8-cineole inhibits platelet function suggests that this compound affects signalling mediated by various molecules such as AKT, Syk, LAT, and cAMP in platelets. Based on these results, we conclude that 1,8-cineole may act as a potential therapeutic agent to control unwarranted platelet reactivity under various pathophysiological settings.
Topics: Animals; Blood Platelets; Cells, Cultured; Eucalyptol; Hemostasis; Humans; Mice; Platelet Activation; Platelet Aggregation; Thrombosis
PubMed: 34685597
DOI: 10.3390/cells10102616 -
Platelets Jan 2021The canalicular system (CS) has been defined as: an inward, invaginated membrane connector that supports entry into and exit from the platelet; a static structure...
The canalicular system (CS) has been defined as: an inward, invaginated membrane connector that supports entry into and exit from the platelet; a static structure stable during platelet isolation; and the major source of plasma membrane (PM) for surface area expansion during activation. Recent analysis from STEM tomography and serial block face electron microscopy has challenged the relative importance of CS as the route for granule secretion. Here, We used 3D ultrastructural imaging to reexamine the CS in mouse platelets by generating high-resolution 3D reconstructions to test assumptions 2 and 3. Qualitative and quantitative analysis of whole platelet reconstructions, obtained from immediately fixed or washed platelets fixed post-washing, indicated that CS, even in the presence of activation inhibitors, reorganized during platelet isolation to generate a more interconnected network. Further, CS redistribution into the PM at different times, post-activation, appeared to account for only about half the PM expansion seen in thrombin-activated platelets, , suggesting that CS reorganization is not sufficient to serve as a dominant membrane reservoir for activated platelets. In sum, our analysis highlights the need to revisit past assumptions about the platelet CS to better understand how this membrane system contributes to platelet function.
Topics: Animals; Humans; Imaging, Three-Dimensional; Mice; Platelet Activation
PubMed: 32000578
DOI: 10.1080/09537104.2020.1719993 -
Thrombosis and Haemostasis Jul 1995The first stage in signal transduction in platelets is interaction between the agonist (or adhesive protein) and its receptor. Changes in conformation or clustering... (Review)
Review
The first stage in signal transduction in platelets is interaction between the agonist (or adhesive protein) and its receptor. Changes in conformation or clustering induced by binding activate signalling on the cytoplasmic side of the platelet membrane. Platelets contain several families of receptors such as the leucine rich repeat group, GPIb-V-IX, involved in adhesion to von Willebrand factor and modulation of the thrombin response. Platelet integrins include GPIIb-IIIa (alpha IIb beta 3), the receptor for fibrinogen and the major mediator of aggregation, which is also a critical signal transducer both inside-out and outside-in to modulate primary signals. Molecules implicated as collagen receptors include the integrin alpha 2 beta 1, CD36 and GPVI and involve a novel signalling pathway. Many seven transmembrane receptors have been identified; current interest is in the proteolytic and purinergic families.
Topics: Animals; Humans; Integrins; Macromolecular Substances; Models, Biological; Platelet Activation; Platelet Adhesiveness; Platelet Aggregation; Platelet Membrane Glycoproteins; Protein Conformation; Receptors, Cell Surface; Receptors, Collagen; Signal Transduction
PubMed: 8578442
DOI: No ID Found -
Journal of Thrombosis and Thrombolysis Aug 2017Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet...
Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet thrombin receptors. The aim was to investigate the effect of dabigatran on platelet activation and platelet aggregation. Healthy donor blood was incubated with dabigatran 0, 50, 500 ng/mL, corresponding to the therapeutic range of dabigatran peak plasma concentrations, and 10,000 ng/mL comprising a supra-therapeutic dabigatran plasma level. Platelet aggregation was tested with 96-well aggregometry. Flow cytometry was used to test platelet activation and platelet thrombin receptor expression (SPAN-12 and WEDE-15 expression). Agonists were thrombin, thrombin receptor-activating peptide, protease-activated receptor-4 agonist, collagen, collagen-related peptide, arachidonic acid, and adenosine diphosphate. All concentrations of dabigatran fully inhibited platelet aggregation for thrombin up to 2 IU/mL, while dabigatran did not affect platelet aggregation by other agonists. Platelet activation (percentage of platelets positive for activated GPIIb/IIIa, CD63, P-selectin) was reduced after thrombin stimulation in samples with dabigatran levels ≥500 ng/mL. After stimulation with thrombin, the percentage of activated GPIIb/IIIa-positive platelets was 99.8 ± 0.2% without dabigatran, 14.7 ± 4.7% with 500 ng/mL dabigatran, and 4.2 ± 0.2% with 10,000 ng/mL dabigatran, both p < 0.001 when compared to samples without dabigatran. Also, the receptor expression of GPIIb/IIIa, CD63, and P-selectin were reduced after dabigatran treatment. The expression of thrombin receptors was reduced at dabigatran on ≥ 500 ng/mL. In conclusion, dabigatran exclusively inhibits thrombin-induced platelet activation and aggregation with a dose-dependent response. Platelet stimulation with other agonists was not affected by dabigatran.
Topics: Antithrombins; Blood Specimen Collection; Dabigatran; Dose-Response Relationship, Drug; Drug Interactions; Healthy Volunteers; Humans; Platelet Activation; Platelet Aggregation; Thrombin
PubMed: 28580515
DOI: 10.1007/s11239-017-1512-2 -
Current Opinion in Pharmacology Apr 2003Activation of P2Y(1) and P2Y(12) receptors, through secreted ADP that is stimulated by agonists such as thrombin, thromboxane and collagen, is a major mechanism of... (Review)
Review
Activation of P2Y(1) and P2Y(12) receptors, through secreted ADP that is stimulated by agonists such as thrombin, thromboxane and collagen, is a major mechanism of platelet activation. P2X(1) receptors also participate in platelet shape change and potentiation of calcium mobilization. The cloning of the P2Y(12) receptor and its subsequent knockout in mice promises further understanding of its downstream signaling events.
Topics: Animals; Blood Platelets; Humans; Platelet Activation; Platelet Aggregation; Receptors, Purinergic
PubMed: 12681240
DOI: 10.1016/s1471-4892(03)00007-9 -
Blood Cells 1990Platelets may become activated in a number of clinical disorders and participate in thrombus formation. Blood tests reflecting in vivo activation are therefore... (Review)
Review
Platelets may become activated in a number of clinical disorders and participate in thrombus formation. Blood tests reflecting in vivo activation are therefore potentially useful in evaluating patients with thrombotic diseases. Three types of monoclonal antibodies have been described that react preferentially with activated platelets. Antibodies against a 53-kD lysosomal granule protein, and antibodies that recognize a 140-kD alpha-granule protein, are two types expressed on the platelet surface during secretion. A third type is not dependent on secretion and recognizes activation-dependent changes in the configuration or microenvironment of the platelet glycoprotein IIb/IIIa complex. Several procedures were used to detect platelet activation, using radiolabeled or fluorescent antibodies. In a number of disorders, changes in platelets, reflecting activation, could be detected. For the study of in vitro and in vivo platelet activation, these tests may be useful, but further studies are needed to confirm the power and efficiency of this approach compared to other routine tests.
Topics: Antibodies, Monoclonal; Humans; Platelet Activation
PubMed: 2190650
DOI: No ID Found -
The Journal of Trauma and Acute Care... Sep 2014Autologous platelet gel therapy using platelet-rich plasma has emerged as a promising alternative for chronic wound healing, hemostasis, and wound infection control. A...
BACKGROUND
Autologous platelet gel therapy using platelet-rich plasma has emerged as a promising alternative for chronic wound healing, hemostasis, and wound infection control. A critical step for this therapeutic approach is platelet activation, typically performed using bovine thrombin (BT) and calcium chloride. However, exposure of humans to BT can stimulate antibody formation, potentially resulting in severe hemorrhagic or thrombotic complications. Electric pulse stimulation using nanosecond PEFs (pulse electric fields) is an alternative, nonbiochemical platelet activation method, thereby avoiding exposure to xenogeneic thrombin and associated risks.
METHODS
In this study, we identified specific requirements for a clinically relevant activator instrument by dynamically measuring current, voltage, and electric impedance for platelet-rich plasma samples. From these samples, we investigated the profile of growth factors released from human platelets with electric pulse stimulation versus BT, specifically platelet-derived growth factor, transforming growth factor β, and epidermal growth factor, using commercial enzyme-linked immunosorbent assay kits.
RESULTS
Electric pulse stimulation triggers growth factor release from platelet α-granules at the same or higher level compared with BT.
CONCLUSION
Electric pulse stimulation is a fast, inexpensive, easy-to-use platelet activation method for autologous platelet gel therapy.
Topics: Animals; Cattle; Electric Stimulation; Enzyme-Linked Immunosorbent Assay; Epidermal Growth Factor; Humans; Platelet Activation; Platelet-Derived Growth Factor; Platelet-Rich Plasma; Thrombin; Transforming Growth Factor beta
PubMed: 25159369
DOI: 10.1097/TA.0000000000000322 -
ASAIO Journal (American Society For... 2011The Levitronix PediVAS is an extracorporeal magnetically levitated pediatric ventricular assist system with an optimal flow rate range of 0.3-1.5 L/min. The system is...
The Levitronix PediVAS is an extracorporeal magnetically levitated pediatric ventricular assist system with an optimal flow rate range of 0.3-1.5 L/min. The system is being tested in preclinical studies to assess hemodynamic performance and biocompatibility. The PediVAS was implanted in nine ovines for 30 days using either commercially available cannulae (n = 3) or customized Levitronix cannulae (n = 6). Blood biocompatibility in terms of circulating activated platelets was measured by flow cytometric assays to detect P-selectin. Platelet activation was further examined after exogenous agonist stimulation. Platelet activation increased after surgery and eventually returned to baseline in animal studies where minimal kidney infarcts were observed. Platelet activation remained elevated for the duration of the study in animals where a moderate number of kidney infarcts with or without thrombotic deposition in the cannulae were observed. When platelet activation did return to baseline, platelets appropriately responded to agonist stimulation, signifying conserved platelet function after PediVAS implant. Platelet activation returned to baseline in the majority of studies, representing a promising biocompatibility result for the Levitronix PediVAS.
Topics: Animals; Flow Cytometry; Heart-Assist Devices; Materials Testing; Models, Animal; Platelet Activation; Sheep
PubMed: 21989419
DOI: 10.1097/MAT.0b013e31822e2535 -
Journal of Proteomics Jun 2022The cAMP-protein kinase A (PKA) pathway in platelets is important for both platelet activation and inactivation. We hypothesize that proteins/processes downstream of the...
The cAMP-protein kinase A (PKA) pathway in platelets is important for both platelet activation and inactivation. We hypothesize that proteins/processes downstream of the cAMP-PKA pathway that are regulated after platelet activation ánd subsequent inactivation can serve as a "switch" in platelet activation and inhibition. We used a STRING-based protein-protein interaction network from proteins of interest distilled from publicly available quantitative platelet proteome datasets. The protein network was integrated with biological pathway information by functional enrichment analysis, phosphorylation by PKA, and drug-target information. Functional enrichment analysis revealed biological processes related to vesicle secretion and cytoskeletal reorganization to be overrepresented among these 30 proteins coinciding with topological clusters in the network. Our method identified proteins/processes with functions related to vesicle transport, cyclin-dependent protein kinases, tight junctions, and small GTPases as potential switches in platelet activation and inhibition. Next to established enzymes in cAMP-PKA signaling, such as PDE3A, proteins with an unknown/less well-known role in platelet biology, such as Stonin-2 and ABLIM-3, emerged from our analysis as interesting candidates for reversal of platelet activation. Our method can be used to repurpose existing datasets and provide a coherent overview of mechanisms involved to predict novel connections, by visually integrating multiple datasets. SIGNIFICANCE: This article presents a novel approach of visually incorporating multiple existing tools and proteomics datasets and in doing so provides novel insight into the complex molecular mechanisms involved in platelet activation. Using our approach, we also highlight several interesting candidates for future research into pathologies with high platelet reactivity.
Topics: Blood Platelets; Cyclic AMP; Phosphorylation; Platelet Activation; Proteomics
PubMed: 35351662
DOI: 10.1016/j.jprot.2022.104577 -
Biological Chemistry 2000Activation of platelets plays a central role in hemostasis as well as in various thromboembolic diseases like myocardial infarction or stroke. Most platelet activating... (Review)
Review
Activation of platelets plays a central role in hemostasis as well as in various thromboembolic diseases like myocardial infarction or stroke. Most platelet activating stimuli function through receptors which couple to heterotrimeric G proteins of the Gi, Gq and G12 families. Recent studies have elucidated the roles of individual G proteins in the regulation of platelet functions like shape change, aggregation and granule secretion. The signaling pathways mediated by heterotrimeric G proteins operate synergistically to induce a full activation of platelets. This review summarizes recent progress in the understanding of upstream regulation of platelet activation through G protein-coupled receptors.
Topics: Heterotrimeric GTP-Binding Proteins; Platelet Activation; Platelet Aggregation; Receptors, Cell Surface
PubMed: 10937869
DOI: 10.1515/BC.2000.051