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Thrombosis and Haemostasis Mar 2023The adhesion G protein-coupled receptor GPR56 mediates cell-cell and cell-extracellular matrix interactions. To examine the function of GPR56 in platelet activation and...
The adhesion G protein-coupled receptor GPR56 mediates cell-cell and cell-extracellular matrix interactions. To examine the function of GPR56 in platelet activation and arterial thrombosis, we generated GPR56-knockout mice and evaluated GPR56 expression in human and mouse platelets. The results revealed that the levels of the GPR56 N-terminal fragment were significantly higher on the first day after myocardial infarction than on the seventh day in the plasma of patients with ST-segment-elevation myocardial infarction. Next, we investigated the effects of GPR56 on platelet function in vitro and in vivo. We observed that collagen-induced aggregation and adenosine triphosphate release were reduced in platelets. Furthermore, P-selectin expression on the platelet surface was also reduced, and the spreading area on immobilized collagen was decreased in platelets. Furthermore, collagen-induced platelet activation in human platelets was inhibited by an anti-GPR56 antibody. mice showed an extended time to the first occlusion in models with cremaster arteriole laser injury and FeCl-induced carotid artery injury. GPR56 activated the G protein 13 signaling pathway following collagen stimulation, which promoted platelet adhesion and thrombus formation at the site of vascular injury. Thus, our study confirmed that GPR56 regulated the formation of arterial thrombosis. Inhibition of the initial response of GPR56 to collagen could significantly inhibit platelet activation and thrombus formation. Our results provide new insights for research into antiplatelet drugs.
Topics: Humans; Mice; Animals; Platelet Aggregation; Platelet Activation; Blood Platelets; Thrombosis; Mice, Knockout; Myocardial Infarction; Collagen; Receptors, G-Protein-Coupled
PubMed: 36402131
DOI: 10.1055/a-1983-0457 -
Scientific Reports May 2021Understanding the platelet activation molecular pathways by characterizing specific protein clusters within platelets is essential to identify the platelet activation...
Understanding the platelet activation molecular pathways by characterizing specific protein clusters within platelets is essential to identify the platelet activation state and improve the existing therapies for hemostatic disorders. Here, we employed various state-of-the-art super-resolution imaging and quantification methods to characterize the platelet spatiotemporal ultrastructural change during the activation process due to phorbol 12-myristate 13-acetate (PMA) stimuli by observing the cytoskeletal elements and various organelles at nanoscale, which cannot be done using conventional microscopy. Platelets could be spread out with the guidance of actin and microtubules, and most organelles were centralized probably due to the limited space of the peripheral thin regions or the close association with the open canalicular system (OCS). Among the centralized organelles, we provided evidence that granules are fused with the OCS to release their cargo through enlarged OCS. These findings highlight the concerted ultrastructural reorganization and relative arrangements of various organelles upon activation and call for a reassessment of previously unresolved complex and multi-factorial activation processes.
Topics: Actin Cytoskeleton; Humans; Organelles; Platelet Activation; Tetradecanoylphorbol Acetate
PubMed: 34006947
DOI: 10.1038/s41598-021-89799-9 -
International Journal of Molecular... Jun 2023Through a process termed , platelets cause thrombi to shrink and become more stable. After platelets are activated via inside-out signaling, glycoprotein αIIbβIII...
Through a process termed , platelets cause thrombi to shrink and become more stable. After platelets are activated via inside-out signaling, glycoprotein αIIbβIII binds to fibrinogen and initiates a cascade of intracellular signaling that ends in actin remodeling, which causes the platelet to change its shape. Clot retraction is also important for wound healing. Although the detailed molecular biology of clot retraction is only partially understood, various substances and physiological conditions modulate clot retraction. In this review, we describe some of the current literature pertaining to clot retraction modulators. In addition, we discuss compounds from , , and that diminish clot retraction and have numerous other health benefits. Caffeic acid and diindolylmethane, both common in plants and vegetables, likewise reduce clot retraction, as do all-trans retinoic acid (a vitamin A derivative), two MAP4K inhibitors, and the chemotherapeutic drug Dasatinib. Conversely, the endogenous anticoagulant Protein S (PS) and the matricellular protein secreted modular calcium-binding protein 1 (SMOC1) both enhance clot retraction. Most studies aiming to identify mechanisms of clot retraction modulators have focused on the increased phosphorylation of vasodilator-stimulated phosphoprotein and inositol 1,4,5-triphosphate receptor I and the decreased phosphorylation of various phospholipases (e.g., phospholipase A2 (PLA) and phosphatidylinositol-specific phospholipase Cγ2 (PLCγ), c-Jun N-terminal kinase, and (PI3Ks). One study focused on the decreased phosphorylation of Sarcoma Family Kinases (SFK), and others have focused on increased cAMP levels and the downregulation of inflammatory markers such as thromboxanes, including thromboxane A2 (TXA) and thromboxane B2 (TXB); prostaglandin A2 (PGE2); reactive oxygen species (ROS); and cyclooxygenase (COX) enzyme activity. Additionally, pregnancy, fibrinolysis, and the autoimmune condition systemic lupus erythematosus all seem to affect, or at least have some relation with, clot retraction. All the clot retraction modulators need in-depth study to explain these effects.
Topics: Blood Platelets; Clot Retraction; Phosphorylation; Platelet Aggregation; Signal Transduction
PubMed: 37445780
DOI: 10.3390/ijms241310602 -
The Journal of Pharmacology and... May 202212-lipoxigenase (12-LOX) is implicated in regulation of platelet activation processes and can be a new promising target for antiplatelet therapy. However, investigations...
12-lipoxigenase (12-LOX) is implicated in regulation of platelet activation processes and can be a new promising target for antiplatelet therapy. However, investigations of 12-LOX were restricted by the lack of specific and potent 12-LOX inhibitors and by controversial data concerning the role of 12-LOX metabolites in platelet functions. A novel specific 12-LOX inhibitor ML355 was shown to inhibit platelet aggregation without adverse side effects on hemostasis; however, the molecular mechanisms of its action on platelets are poorly understood. Here, we showed that ML355 inhibited platelet activation induced by thrombin or thromboxane A, but not by collagen-related peptide. ML355 blocked protein kinase B, phosphoinositide 3-kinase, and extracellular signal-regulated kinase, but not p38 kinase, spleen tyrosine kinase (Syk), or phospholipase C2 phosphorylation in activated platelets. The main inhibitory effect of low doses of ML355 (1-20 μM) on thrombin activated platelets was mediated by the decrease in reactive oxygen species level, whereas high doses of ML355 (50 μM) caused cyclic adenosine monophosphate activation. ML355 did not affect the activity of nitric oxide-dependent soluble guanylyl cyclase, nor did it affect the relaxation of preconstricted aortic rings in mice. ML355 itself did not affect platelet viability, but at 50 μM dose blocked caspase-dependent apoptosis induced by B-cell lymphoma II inhibitor ABT-737. SIGNIFICANCE STATEMENT: The current paper provides novel and original data concerning molecular mechanisms of 12-LOX inhibitor ML355 action on platelets. These data reveal antiplatelet and protective effects of ML355 on platelets and may be of importance for both antiplatelet and anticancer therapy.
Topics: Animals; Apoptosis; Biphenyl Compounds; Blood Platelets; Mice; Nitrophenols; Phosphatidylinositol 3-Kinases; Piperazines; Platelet Activation; Platelet Aggregation; Platelet Aggregation Inhibitors; Sulfonamides; Thrombin
PubMed: 35197320
DOI: 10.1124/jpet.121.000973 -
Clinica Chimica Acta; International... Aug 2020Diabetes can lead to serious pathological changes in the microvascular system, which in turn leads to functional damage of related tissues that affects the quality of... (Review)
Review
BACKGROUND
Diabetes can lead to serious pathological changes in the microvascular system, which in turn leads to functional damage of related tissues that affects the quality of life of patients. The mechanism of microcirculation disturbance in diabetes is not well understood; however, the inflammatory damage and dysgenesis of blood vessels based on oxidative and hyperosmotic stress is considered to be a key factor. In addition, with in-depth studies of platelet function, the study of platelet inflammatory function has become popular in recent years.
OBJECTIVE
The present manuscript reviews the new knowledge of platelet immune inflammatory function and the mechanism of diabetic microangiopathy, and emphasizes the relationship between them.
CONCLUSION
The nuclear factor-κB (NF-κB) pathway has always been regarded as a typical pro-inflammatory signaling pathway in different nucleated cells, and NF-κB is also expressed in platelets. Although the signaling pathway of NF-κB in platelets is not completely understood, numerous studies have confirmed its function in platelet immune inflammation. The signaling pathway of the development of diabetic microangiopathy is partially cross-linked with the platelet NF-κB pathway. In addition, platelets can release various chemokines to aggravate vascular endothelial cell injury, indicating that platelets may serve a key role in the mechanism of diabetic microangiopathy.
Topics: Animals; Diabetic Angiopathies; Humans; Inflammation; NF-kappa B; Platelet Activation
PubMed: 32376322
DOI: 10.1016/j.cca.2020.04.042 -
Journal of Cardiovascular Pharmacology... May 2020Antiplatelet therapy reduces atherothrombotic risk and has therefore become a cornerstone in the treatment of cardiovascular disease. Aspirin, adenosine diphosphate P2Y... (Review)
Review
Antiplatelet therapy reduces atherothrombotic risk and has therefore become a cornerstone in the treatment of cardiovascular disease. Aspirin, adenosine diphosphate P2Y receptor antagonists, glycoprotein IIb/IIIa inhibitors, and the thrombin receptor blocker vorapaxar are effective antiplatelet agents but significantly increase the risk of bleeding. Moreover, atherothrombotic events still impair the prognosis of many patients with cardiovascular disease despite established antiplatelet therapy. Over the last years, advances in the understanding of thrombus formation and hemostasis led to the discovery of various new receptors and signaling pathways of platelet activation. As a consequence, many new antiplatelet agents with high antithrombotic efficacy and supposedly only moderate effects on regular hemostasis have been developed and yielded promising results in preclinical and early clinical studies. Although their long journey from animal studies to randomized clinical trials and finally administration in daily clinical routine has just begun, some of the new agents may in the future become meaningful additions to the pharmacological armamentarium in cardiovascular disease.
Topics: Animals; Blood Platelets; Cardiovascular Diseases; Drug Development; Drug Discovery; Hemorrhage; Humans; Molecular Targeted Therapy; Platelet Activation; Platelet Aggregation Inhibitors; Signal Transduction; Treatment Outcome
PubMed: 31960728
DOI: 10.1177/1074248419899314 -
PloS One 2023The increased procoagulant platelets and platelet activation are associated with thrombosis in COVID-19. In this study, we investigated platelet activation in COVID-19...
BACKGROUND
The increased procoagulant platelets and platelet activation are associated with thrombosis in COVID-19. In this study, we investigated platelet activation in COVID-19 patients and their association with other disease markers.
METHODS
COVID-19 patients were classified into three severity groups: no pneumonia, mild-to-moderate pneumonia, and severe pneumonia. The expression of P-selectin and activated glycoprotein (aGP) IIb/IIIa on the platelet surface and platelet-leukocyte aggregates were measured prospectively on admission days 1, 7, and 10 by flow cytometry.
RESULTS
P-selectin expression, platelet-neutrophil, platelet-lymphocyte, and platelet-monocyte aggregates were higher in COVID-19 patients than in uninfected control individuals. In contrast, aGPIIb/IIIa expression was not different between patients and controls. Severe pneumonia patients had lower platelet-monocyte aggregates than patients without pneumonia and patients with mild-to-moderate pneumonia. Platelet-neutrophil and platelet-lymphocyte aggregates were not different among groups. There was no change in platelet-leukocyte aggregates and P-selectin expression on days 1, 7, and 10. aGPIIb/IIIa expression was not different among patient groups. Still, adenosine diphosphate (ADP)-induced aGPIIb/IIIa expression was lower in severe pneumonia than in patients without and with mild-to-moderate pneumonia. Platelet-monocyte aggregates exhibited a weak positive correlation with lymphocyte count and weak negative correlations with interleukin-6, D-dimer, lactate dehydrogenase, and nitrite.
CONCLUSION
COVID-19 patients have higher platelet-leukocyte aggregates and P-selectin expression than controls, indicating increased platelet activation. Compared within patient groups, platelet-monocyte aggregates were lower in severe pneumonia patients.
Topics: Humans; P-Selectin; Monocytes; COVID-19; Blood Platelets; Platelet Activation; Platelet Glycoprotein GPIIb-IIIa Complex; Flow Cytometry; Platelet Aggregation
PubMed: 36888618
DOI: 10.1371/journal.pone.0282785 -
International Journal of Molecular... Aug 2023COVID-19 has been a diagnostic and therapeutic challenge. It has marked a paradigm shift when considering other types of pneumonia etiology. We analyzed the biomarkers...
COVID-19 has been a diagnostic and therapeutic challenge. It has marked a paradigm shift when considering other types of pneumonia etiology. We analyzed the biomarkers related to endothelial damage and immunothrombosis in COVID-19 in comparison to community-acquired pneumonia (CAP) through a case-control study of 358 patients with pneumonia (179 hospitalized with COVID-19 vs. 179 matched hospitalized with CAP). Endothelial damage markers (endothelin and proadrenomedullin), neutrophil extracellular traps (NETs) (citrullinated-3 histone, cell-free DNA), and platelet activation (soluble P-selectin) were measured. In-hospital and 1-year follow-up outcomes were evaluated. Endothelial damage, platelet activation, and NET biomarkers are significantly higher in CAP compared to COVID-19. In-hospital mortality in COVID-19 was higher compared to CAP whereas 1-year mortality and cardiovascular complications were higher in CAP. In the univariate analysis (OR 95% CIs), proADM and endothelin were associated with in-hospital mortality (proADM: CAP 3.210 [1.698-6.070], COVID-19 8.977 [3.413-23.609]; endothelin: CAP 1.014 [1.006-1.022], COVID-19 1.024 [1.014-1.034]), in-hospital CVE (proADM: CAP 1.623 [1.080-2.439], COVID-19 2.146 [1.186-3.882]; endothelin: CAP 1.005 [1.000-1.010], COVID-19 1.010 [1.003-1.018]), and 1-year mortality (proADM: CAP 2.590 [1.644-4.080], COVID-19 13.562 [4.872-37.751]; endothelin: CAP 1.008 [1.003-1.013], COVID-19 1.026 [1.016-1.037]). In conclusion, COVID-19 and CAP showed different expressions of endothelial damage and NETs. ProADM and endothelin are associated with short- and long-term mortality.
Topics: Humans; COVID-19; Case-Control Studies; Extracellular Traps; Pneumonia; Platelet Activation; Community-Acquired Infections
PubMed: 37686001
DOI: 10.3390/ijms241713194 -
Thrombosis Research Apr 2021Patients with cancer are at a high risk of venous thromboembolism (VTE), studies have shown that high expression of podoplanin (PDPN) in tumors is associated with...
BACKGROUND
Patients with cancer are at a high risk of venous thromboembolism (VTE), studies have shown that high expression of podoplanin (PDPN) in tumors is associated with increased risk of VTE.
METHODS
Two human malignant cell lines (NCI-H226 and C8161) expressing high levels of PDPN were selected to explore the role of platelet in cancer-associated venous thrombosis in vitro and in vivo. Immunohistochemical staining using anti-PDPN antibody was performed in the pulmonary carcinoma patients.
RESULTS
Both NCI-H226 and C8161 cells expressing high PDPN triggered platelet activation via CLEC-2 in vitro, which was abrogated by an anti-PDPN antibody SZ-168. Furthermore, the in vivo study revealed that injection of CHO-PDPN or C8161 in two mouse model of venous thrombosis activated platelets, increased platelet counts and enhanced thrombosis. More importantly, PDPN-enhanced thrombosis was reduced in mice treated with SZ168. A total of 63.3% tumor specimens stained positive for PDPN. High PDPN expression was associated with an increased risk of VTE and poor prognosis.
CONCLUSIONS
PDPN expression in tumors induced platelet activation and was related to a high risk of VTE via platelet activation. SZ168 inhibited PDPN-induced platelet activation in vitro and decreased the incidence of VTE in mice.
Topics: Animals; Blood Platelets; Humans; Membrane Glycoproteins; Mice; Neoplasms; Platelet Activation; Thrombosis; Venous Thrombosis
PubMed: 33548843
DOI: 10.1016/j.thromres.2021.01.008 -
Seminars in Thrombosis and Hemostasis Jul 2024This article represents a republication of an article originally published in STH in 2005. This republication is to help celebrate 50 years of publishing for STH. The... (Review)
Review
This article represents a republication of an article originally published in STH in 2005. This republication is to help celebrate 50 years of publishing for STH. The original abstract follows.Platelets are specialized blood cells that play central roles in physiologic and pathologic processes of hemostasis, inflammation, tumor metastasis, wound healing, and host defense. Activation of platelets is crucial for platelet function that includes a complex interplay of adhesion and signaling molecules. This article gives an overview of the activation processes involved in primary and secondary hemostasis, for example, platelet adhesion, platelet secretion, platelet aggregation, microvesicle formation, and clot retraction/stabilization. In addition, activated platelets are predominantly involved in cross-talk to other blood and vascular cells. Stimulated "sticky" platelets enable recruitment of leukocytes at sites of vascular injury under high shear conditions. Platelet-derived microparticles as well as soluble adhesion molecules, sP-selectin and sCD40L, shed from the surface of activated platelets, are capable of activating, in turn, leukocytes and endothelial cells. This article focuses further on the new view of receptor-mediated thrombin generation of human platelets, necessary for the formation of a stable platelet-fibrin clot during secondary hemostasis. Finally, special emphasis is placed on important stimulatory and inhibitory signaling pathways that modulate platelet function.
Topics: Humans; Blood Platelets; Hemostasis; Platelet Activation; Platelet Adhesiveness; Signal Transduction; Platelet Aggregation
PubMed: 38086407
DOI: 10.1055/s-0043-1777305